REFRIGERANT REPO RT 20
A-501-20 EN Refrigerant Report
Contents Page Essential revisions/supplements vs. 19th edition Refrigerant development and legal situation 3
Alternative refrigerants – overview 4
Environmental aspects 6 Global Warming and TEWI Factor 6 Eco-Efficiency 7
HCFC refrigerants 8 R22 as transitional refrigerant 8
HFC refrigerants 9 R134a as a substitute for R12 and R22 9 Alternatives to R134a 11
Refrigerant blends 13
Substitutes for R22 in refrigeration systems 17 R404A and R507A as substitutes for R22 and R502 17 R407A, R407B, R407F, R407H and R422A as substitutes for R22 and R502 18
Substitutes for R22 in air conditioning systems and heat pumps 20 R407C as substitute for R22 // R410A as substitute for R22 20 R417A, R417B, R422D, R438A and R427A as substitutes for R22 22 R32 as substitute for R22 23
"Low GWP" HFOs and HFO/HFC blends as alternatives to HFCs 24 Aspects on the development 24 R134a alternatives 24 Substitutes for R404A/R507A and R410A 25 Further development projects 26
Halogen free (natural) refrigerants 28
NH 3 (Ammonia) as alternative refrigerant 28 R723 (NH 3/DME) as an alternative to NH 3 29 R290 (Propane) as alternative refrigerant // Propylene (R1270) as an alternative to Propane 30
Carbon dioxide R744 (CO 2) as an alternative refrigerant and secondary fluid 33 Refrigerants for special applications 37
Lubricants for compressors 40
Refrigerant properties 41
Application ranges 43
Overview lubricants 44
to the digital Refrigerant Report This edition supersedes all previous issues. Refrigerant development and legal situation
Stratospheric ozone depletion as well as at- than direct (CO 2-equivalent) emissions The so-called "TEWI" factor ( Total Equiva - mospheric greenhouse effect due to refriger - caused by HFC refrigerants, refrigerants lent Warming Impact) has been introduced. ant emissions have led to drastic changes in with high global warming potential (GWP) Meanwhile, another, more extensive the refrigeration and air conditioning tech- will in the future be subject to use restric - assessment method has been developed nology since the beginning of the 1990s. tions or bans. This will affect primarily considering "Eco-Efficiency". Hereby, both R404A and R507A, for which alternatives ecological (such as TEWI) and economical This is especially true for the area of com - with lower GWP are already being offered. criteria are taken into account (further mercial refrigeration and air conditioning However, in order to achieve the legal explanations see page 7). systems with their wide range of applica - objectives, substitutes for further refrigerants Therefore it is possible that the assessment tions. In former years the main refrigerants and increased use of naturally occurring of refrigerants with regard to the environment used for these systems were ozone deplet - substances (N H , C O , hydrocarbons) will 3 2 can differ according to the place of installa - ing types, namely R12, R22 and R502; for become necessary. special applications R114, R12B1, R13B1, tion and drive method. This requires comprehensive testing of R13 and R503 were used. Upon closer evaluation of substitutes for the these refrigerants, suitable oils and adjusted originally used CFC and HCFC as well as The use of these substances is no longer systems. Therefore a close co-operation for HFCs with higher GWP, the options with allowed in industrialised countries, but the exists with scientific institutions, the refriger - single-substance refrigerants are very limit - use of R22 has been extended through tran - ation and oil industries, component manu - ed. This includes e.g. R134a, which will be sitional periods. However, the European facturers as well as a number of innovative usable for quite some time based on its Union also commited to an early phase-out refrigeration and air conditioning companies. for R22, which was enforced in several comparatively low GWP. Similarly, the stages (see page 8). The main reason for A large number of development tasks have hydro-fluoro-olefins (HFO) R1234yf and this early ban of R22 contrary to the inter- been completed. Suitable compressors for R1234ze(E) with a GWP < 10, which are national agreement is the ozone depletion alternative refrigerants are available. also exempted from the F-Gas regulation. potential although it is only small. Besides the development projects, BITZER Direct alternatives (based on fluorinated Since 2010, phase-out regulations became actively supports legal regulations and self hydrocarbons) for almost all refrigerants of effective in other countries as well, for commitments concerning the responsible higher volumetric refrigerating capacity and instance in the USA. use of refrigerants as well as measures to pressure level than R134a can only be "for - This implies enormous consequences for increase system and components’ efficiency. mulated" as blends. However, taking into account thermodynamic properties, flamma - the whole refrigeration and air conditioning The following report deals with potential bility, toxicity and global warming potential, sector. BITZER therefore committed itself to measures of a short to medium-term change the list of potential candidates is very limit - taking a leading role in the research and towards technologies with reduced environ - ed. Blends of reduced GWP include in addi- development of environmentally friendly sys - mental impact in medium and large size tion to R134a, R1234yf and R1234ze(E) pri - tem designs. commercial refrigeration and air conditioning marily the refrigerants R32, R125 and systems. Furthermore, the experiences so After the chlorine-free (ODP = 0) HFC refriger - R152a. ants R134a, R404A, R407C, R507A and far and the resulting consequences for plant R410A have become widely established for technology are discussed. Besides halogenated refrigerants, Ammonia many years in commercial refrigeration, air (NH 3) and hydrocarbons are considered as substitutes as well. The use for commercial conditioning and heat pump systems, new ? ? ? challenges have come up. They concern pri - applications, however, is limited by strict marily the greenhouse effect: The aim is a safety requirements. Several studies confirm that vapour com - clear reduction of direct emissions caused Carbon dioxide (CO ) becomes more impor - pression refrigeration systems normally 2 by refrigerant losses and indirect emissions tant as an alternative refrigerant and sec - used commercially are far superior in effi - by particularly efficient system technology. ondary fluid, too. Due to its specific charac - ciency to all other processes down to a cold teristics, however, there are restrictions to a In this area, applicable legal regulations are space temperature of around -40°C. already in force, such as the EU F-Gas general application. The selection of an alternative refrigerant Regulation No. 517/2014 (BITZER brochure The following illustrations show a structural and the system design receives special sig - A-510) and a series of regulations already survey of the alternative refrigerants and a nificance, however. Besides the request for ratified or in preparation as part of the EU summary of the single or blended substance s substances without ozone depletion poten - Ecodesign Directive (BITZER brochure which are now available. After that the indi - tial (ODP = 0) especially the energy de- A-530). Similar regulations are also in vidual subjects are discussed. preparation or already implemented in Aus - mand of a system is seen as an essential tralia, Canada and the USA. On an inter- criterion due to its indirect contribution to For refrigerant properties, application national level, the so-called "Kigali Amend - the greenhouse effect. On top of that there ranges and lubricant specifications, see ment" was adopted in 2016 under the is the direct global warming potential (GWP) pages 41 to 44. due to refrigerant emission. Montreal Protocol, in which a step-by-step For reasons of clarity the less or only reduction of HFCs ("HFC phase-down") was Therefore a calculation method has been regionally known products are not specified agreed upon starting in 2019. developed for the qualified evaluation of a in this issue, which is not intended to imply Even though indirect emissions caused by system which enables an analysis of the any inferiority. energy production are considerably higher total influence on the greenhouse effect. 3 Alternative refrigerants – overview
Alternative Refrigerants
Transitional/Service Medium and Long Refrigerants* Term Refrigerants
HCFC/HFC HFC "Low GWP " Halogen free – partly chlorinated – – chlorine free – Refrigerants
Single Single Single Single Substances Blends Substances Blends Substances Blends Substances Blends
e.g.. R22 predominantly e.g. R134a e.g. R404A R1234yf R1234yf/ e.g. NH 3 e.g. R600a/ R123 R22 -Based R125 R507A R1234ze(E) R1234ze(E)/ R290 R290 R124 R32 R407-Serie HFKW R1270 R290/ R142b R143a R410A R600a R170 R152a R417A/B R170 R422 A/D R744 R723 R427A * Service refrigerants contain HCFC as blend component. They are therefore subject to the same legal regulations as R22 (see page 8). As a result of the continued refurbishment of older installations, the importance of these refrigerants is clearly on the decline. For some of them, production has already been discontinued. However, because of the development history of service blends, these refrigerants will continue to be covered in this Report. Fig. 1 Structural classification of refrigerants
HFC refrigerants 09.18
Former Alternatives Refrigerants
ASHRAE Trade name Composition Detailed Classification (with blends) Information R 1 2 R134a – R152a 1 pages (R500) 4 9...12, 16, 41...43 R437A ISCEON ® MO49 Plus Chemours 5 R125/134a/600/601 R404A various R143a/125/134a R22/R502 R507A various R143a/125 pages 17...19, 41...43 R422A ISCEON ® MO79 Chemours 5 R125/134a/600a R407A Mexichem, Arkema R32/125/134a R407C various R32/125/134a R407F Performax ® LT Honeywell R32/125/134a R407H – Daikin Chemical R32/125/134a R410A various R32/125 R22 pages R417A ISCEON ® MO59 Chemours 5 R125/134a/600 R417B – Daikin Chemical R125/134a/600 18...23, 41...43 R422D ISCEON ® MO29 Chemours 5 R125/134a/600a R427A Forane ® 427A Arkema R32/125/143a/134a R438A ISCEON ® MO99 Chemours 5 R32/125/134a/600/601a R114 R236fa – – pages R12B1 R227ea – – 37, 41...43 R13B1 R410A various R32/125 pages 38, 41...43 R23 – – R13 pages R508A KLEA ® 508A Mexichem R23/116 R503 39, 41...43 R508B Suva ® 95 Chemours 5 R23/116
Tab. 1 Substitutes for CFC and HCFC refrigerants (chlorine free HFCs) 4 Alternative refrigerants – overview
HFO and HFO/HFC Blends 09.18
Current Alternatives Refrigerants
ASHRAE Trade name Composition Detailed Classification (with blends) Information
R1234yf 1 various – R1234ze(E) 1 various – R450A Solstice ® N-13 Honeywell R1234ze(E)/134a pages 24…27, R 1 3 4 a R456A AC5X** Mexichem R32/1234ze(E)/134a Opteon TM 5 41…43 R513A XP10 Chemours R1234yf/134a R513A Daikin Chemical R516A ARM-42*** Arkema R1234yf/152a/134a
R448A Solstice ® N-40 Honeywell R32/125/1234yf/1234ze(E)/134a Opteon TM XP40 Chemours 5 R404A/R507A* R449A R32/125/1234yf/134a pages 24…27 Forane ® 449 Arkema , (R22/R407C*) R449C Opteon TM XP20 Chemours 5 R32/125/1234yf/134a 41…43 R460B LTR4X** Mexichem R32/1234ze(E)/134a
R32 1 various – Opteon TM XL55 Chemours 5 R452B 1 R32/125/1234yf R 4 1 0 A Solstice ® L-41y Honeywell pages 24…27, R454B 1 Opteon TM XL41 Chemours 5 R32/1234yf 41…43 R459A 1 ARM-71*** Arkema R32/1234yf/1234ze(E)
* Due to the large number of different HFO/HFC blends and the potential changes in development products, the above list contains as alternatives for R134a and R404A/R507A only non-flammable blends of GWP approx. 600 (R134a) and GWP < 1500 (R404A/R507A). HFO/HFC blends are extensively discussed on pages 24 to 27. Further alternatives are also dealt with. ** Development product *** Available 2018 .. 2020
Tab. 2 "Low GWP" refrigerants and blends
Halogen free refrigerants 09.18
Current Alternatives Refrigerants
ASHRAE Trade name Formula Detailed Classification Information
1 R290/600a – C3H8/C 4H10 pages R134a 1 3 R600a – C4H10 30, 41...43
1 2 R717 – NH 3 R404A 1 2 R723 – NH 3 + R-E170 pages R507A 1 R290 – C3H8 28...32, 41...43 R22 1 R1270 – C3H6
pages R124 R600a 1 – C H 4 1 0 37, 41...43
R 4 1 0 A no direct alternatives available
1 pages R23 R170 – C H 2 6 39, 41...43
pages Various R744 3 – CO 2 33...36, 41...43
Tab. 3 Alternatives for HCFC and HFC refrigerants (halogen free refrigerants)
Explanation of Tab. 1 to 3 1 Flammable 3 Large deviation in refrigerating capacity and 4 Service refrigerant 5 Company has emerged 2 Toxic pressures to the previous refrigerant with zero ODP from DuPont 5 Environmental aspects
Global Warming and Due to a deciding proportion of the total bal - TEWI values with various refrigerant TEWI Factor ance, there is not only a need for alternative charges, leakage losses and energy con- refrigerants with a favorable (thermodynam - sumptions. ic) energy balance, but an increase in de- This example is simplified based on an As already mentioned (see chapter Re- mand for highly efficient compressors overall leak rate as a percentage of the frigerant developments and legal situation, and associated equipment as well as opti - refrigerant charge. The actual values vary page 3), a method of calculation has been mised system components and system con - very strongly, so that the potential risk of developed to judge the influence upon the trol. global warming effect for the operation of individually constructed systems and exten - individual refrigeration plants (TEWI = Total When various compressor designs are com - sively branched plants is especially high. Equivalent Warming Impact). pared, the difference of indirect CO 2 emis - Great effort is taken worldwide to reduce sion (due to the energy requirement) can All halocarbon refrigerants (including the greenhouse gas emissions, and legal regu - have a larger influence upon the total effect non-chlorinated HFCs) belong to the cat- lations have partly been developed already. than the refrigerant losses. egory of greenhouse gases. An emission of Since 2007, the "Regulation on certain fluor- these substances contributes to the global A usual formula is shown in Fig. 2. The inated greenhouse gases" – which also warming effect. The influence is however TEWI factor can be calculated and the vari - defines stringent requirements for refriger- ation and air conditioning systems – has much greater in comparison to CO 2, which ous areas of influence are correspondingly is the main greenhouse gas in the atmo - separated. become valid for the EU. Meanwhile, the sphere (in addition to water vapour). Based revised Regulation No. 517/2014 entered on a time horizon of 100 years, the emis - An additional example is shown in Fig. 3 into force and has to be applied since Jan - sion from 1 kg R134a is for example rough - (medium temperature with R134a) shows uary 2015. ly equivalent to 1430 kg of CO 2 (GWP = 1430). 7(:, = 727$/(48,9$/(17:$50,1*,03$&7 Thus, the reduction of refrigerant losses 7(:, *:3[/[Q *:3[P>˞ @ Q[( [˟ must be one of the main tasks for the UHFRYHU\ DQQXDO future. /HDNDJH 5HFRYHU\ORVVHV (QHUJ\FRQVXPSWLRQ GLUHFWJOREDOZDUPLQJSRWHQWLDO LQGLUHFWJOREDO On the other hand, the major contributor to ZDUPLQJSRWHQWLDO a refrigeration plant’s global warming effect *:3 *OREDOZDUPLQJSRWHQWLDO >&2 UHODWHGDFFWR,3&&,9@ is the (indirect) CO 2 emission caused by energy generation. Based on the high per - / /HDNDJHUDWHSHU\HDU >NJ@ centage of fossil fuels used in power sta - Q 6\VWHPRSHUDWLQJWLPH >
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[ * 1 5 ( CAP 13.5 kW , ( < : * 5 ( 5 E 5 kW x 5000 h/a 7 < * RL = Impact of * < recovery b 0.45 kg CO 2/kWh < losses a 0.75 5/ 5/ 5/ 5/ LL = Impact of n 15 years // // leakage LL // losses GWP 1430 (CO 2 = 1) NJ NJ NJ NJ time horizon 100 years 5HIULJHUDQWFKDUJH>P] Fig. 3 Comparison of TEWI figures (example) 6 Environmental aspects
Eco-Efficiency With this evaluation approach, the entire life higher in the top right quadrant exhibits an cycle of a system is taken into account in increasingly better Eco-Efficiency – and terms of: conversely, it becomes less efficient in the An assessment based on the specific TEWI bottom left sector. value takes into account the effects of glob - o ecological performance in accordance al warming during the operating period of a with the concept of Life Cycle Assess - The diagonals plotted into the system of refrigeration, air conditioning or heat pump ment as per ISO 14040, coordinates represent lines of equal Eco- installation. However, not the entire ecologi- Efficiency. This means that systems or pro - o economic performance by means of a cal and economical aspects are considered. Life Cycle Cost Analysis. cesses with different life cycle costs and environmental impacts can quite possibly But apart from ecological aspects, economi - This means that the overall environmental result in the same Eco-Efficiency. cal aspects are highly significant when eval - impact (including direct and indirect emis - uating technologies and making investment sions), as well as the investment costs, decisions. With technical systems, the operating and disposal costs, and capital reduction of environmental impact frequent - costs are taken into account. ly involves high costs, whereas low costs often have increased ecological conse - The studies also confirm that an increase of quences. For most companies, the invest - Eco-Efficiency can be achieved by investing ment costs are decisive, whereas they are in optimized plant equipment (minimized often neglected during discussions about operating costs). Hereby, the choice of minimizing ecological problems. refrigerant and the associated system tech - nology play an important role. For the purpose of a more objective assess - ment, studies* were presented in 2005 and Eco-Efficiency can be illustrated in graphic * Study 2005: Compiled by Solvay Management Support GmbH and Solvay Fluor GmbH, Hannover, 2010, using the example of supermarket representation (Example, see Fig. 5). The together with the Information Centre on Heat Pumps refrigeration plants to describe a concept for results of the Eco-Efficiency evaluation are and Refrigeration (IZW), Hannover. evaluating Eco-Efficiency . It is based on shown on the x-axis in the system of coordi - Study 2010: Compiled by SKM ENVIROS, UK, commissioned by and in cooperation with EPEE the relationship between added value (a nates, whilst the results of the life cycle cost (European Partnership for Energy and Environment). product's economic value) and the resulting analysis are shown on the y-axis. This Both projects were supported by an advisory group environmental impact. shows clearly: A system that is situated of experts from the refrigeration industry.
Concept of Eco-Efficiency
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Fig. 4 Concept of Eco-Efficiency Fig. 5 Example of an Eco-Efficiency evaluation
7 HCFC refrigerants
R22 as transitional refrigerant refrigerant in new systems and for service Special measures have to be adopted purposes due to its ozone depletion poten- therefore, such as two stage compression, tial – although being low. controlled refrigerant injection, additional Although chlorine-free refrigerants, such as cooling, monitoring of discharge gas tem- With regard to components and system R134a and R404A/R507A (Fig. 1 and Tab. perature, limiting the suction gas superheat technology a number of particularities are to 1) have been widely used − but are already and particularly careful installation. follow as well. Refrigerant R22 has approxi - being replaced by alternatives with lower mately 55% higher refrigerating capacity and GWP in the EU for example − R22 is still pressure levels than R12**. The significantly used internationally in many areas, both for higher discharge gas temperature is also a new installations and for retrofitting existing critical factor compared to R12 (Fig. 6) and ones. R502**. Reasons are relatively low investment costs, Similar relationships in terms of thermal load especially compared with R134a systems, are found in the comparison with HFC refriger - * Not allowed for new equipment in Germany and but also its large application range, favour- Denmark since January 1st, 2000 and in Sweden ants R134a, R404A/R507A (pages 9 and 17). as of 1998. able thermodynamic properties and low Since January 1 st , 2001 restrictions apply to the energy requirement. Additionally, R22 and other member states of the EU as well. The meas- components are available world wide, which Resulting design criteria ures concerned are defined in the ODS Regulation 1005/2009 of the EU commision on ozone depleting is not guaranteed everywhere for the chlo - Particularly critical – due to the high dis - substances amended in 2009. This regulation also rine free alternatives. governs the use of R22 for service reasons within charge gas temperature – are low tempera - the entire EU. Despite of the generally favourable proper - ture plants especially concerning thermal Since 2010, phase-out regulations in other coun - ties R22 is already subject to various region - stability of oil and refrigerant, with the dan - tries, such as the USA, are valid. al restrictions* which control the use of this ger of acid formation and copper plating. ** Already banned in most countries.
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8 HFC refrigerants
R134a as substitute for There are also limitations in the application Lubricants for R134a and other HFCs R12 and R22 with low evaporating temperatures to be considered. The traditional mineral and synthetic oils are Comprehensive tests have demonstrated not miscible (soluble) with R134a and other R134a was the first chlorine free (ODP = 0) that the performance of R134a exceeds the - HFCs described in the following and are HFC refrigerant that was tested comprehen - oretical predictions over a wide range of therefore only insufficiently transported sively. It is now used world-wide in many compressor operating conditions. Tempera - around the refrigeration circuit. refrigeration and air conditioning units with ture levels (discharge gas, oil) are even Immiscible oil can settle out in the heat good results. As well as being used as a lower than with R12 and, therefore, sub - exchangers and prevent heat transfer to pure substance, R134a is also applied as a stantially lower than R22 values. There are such an extent that the plant can no longer component of a variety of blends (see also thus many potential applications in air con - be operated. “Refrigerant blends”, page 13). ditioning and medium temperature refriger- ation plants as well as in heat pumps. Good New lubricants were developed with the R134a has similar thermodynamic heat transfer characteristics in evaporators appropriate solubility and have been in use properties to R12: and condensers (unlike zeotropic blends) for many years. These lubricants are based favour an economical use. on Polyol Ester (POE) and Polyalkylene Refrigerating capacity, energy demand, Glycol (PAG). temperature properties and pressure levels R134a is also characterized by a compar- are comparable, at least in air conditioning ably low GWP (1430). Therefore, in view of For further explanations on lubricants see and medium temperature refrigeration future restrictions (for example EU F-Gas chapter “Lubricants for compressors”, page plants. This refrigerant can therefore be Regulation), the use of this refrigerant will 40. used as an alternative for most former R12 still be possible for quite some time. If applications. required, systems can later be converted relatively easily to non-flammable (A1) For some applications R134a is even pre - HFO/HFC alternatives with a GWP of ferred as a substitute for R22 , an impor - approx. 600 (pages 24/25). tant reason being the limitations to the use of R22 in new plants and for service. How - ever, the lower volumetric refrigerating capacity of R134a (Fig. 9) requires a larger compressor displacement than with R22.
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Resulting design and construction Converting existing R12 plants to containing chlorine is found often. These criteria R134a products are released by the influence of the highly polarized mixture of ester oil and Suitable compressors are required for At the beginning this subject was discussed R134a and find their way into the compres - R134a with a special oil charge and adapt - very controversially, several conversion sor and control devices. Conversion should ed system components. The normal metallic methods were recommended and applied. therefore be limited to systems which are in materials used in CFC plants have also Today there is a general agreement on a good condition. been proven with ester oils; elastomers technically and economically matching solu- must sometimes be matched to the chang - tions. Restrictions for R134a in mobile ing situation. This is especially valid for flex - The characteristics of ester oils are very air conditioning (MAC) systems ible hoses where the requirements call for a favourable here: Under certain conditions minimum residual moisture content and low they can be used with CFC refrigerants, An EU Directive on "Emissions from MAC permeability. they can be mixed with mineral oils and tol - systems" bans the use of R134a in new erate a proportion of chlorine up to a few The plants must be dehydrated with particu - systems. Various alternative technologies hundred ppm in an R134a system. lar care and the charging or changing of are already in use. For further explanation lubricant must also be done carefully. In The remaining moisture content has, how - see pages 11, 12, and 36. addition relatively large driers should be ever, an enormous influence. Very thorough provided, which have also to be matched to evacuation (removal of remaining chlorine the smaller molecule size of R134a. and dehydration) is therfore essential, as well as the installation of generously dimen - Meanwhile, many years of very positive sioned driers. There is doubtful experience experience with R134a and ester oils with systems where the chemical stability have been accumulated. For this refrig - was already insufficient with R12 operation erant, BITZER offers an unequalled e.g. with bad maintenance, small drier wide range of reciprocating, screw and capacity, high thermal loading. Increased scroll compressors. deposition of oil decomposition products
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3 concerning the use of R134a (see also http://www.bitzer.de) 5 o Technical Information KT-620 "HFC Refrigerant R134a" 5D o Technical Information KT-510 „Polyolester oils for reciprocating compressors“ o Special edition 7HPSHUDWXUH>r&@ „A new generation of compact screw Fig. 10 R134a/R12/R22 – comparison of pressure levels compressors optimised for R134a“ 10 HFC refrigerants
Alternatives to R134a R152a – an alternative "Low GWP" HFO refrigerant to R134a (?) R1234yf For mobile air conditioning systems (MAC) with open drive compressors and hose con - R152a is very similar to R134a with regard The ban on the use of R134a in mobile air nections in the refrigerant circuit, the risk of to volumetric refrigerating capacity (approx. conditioning systems within the EU has trig - leakages is considerably higher than with -5%), pressure levels (approx. -10%) and gered a series of research projects. In addi - stationary systems. An EU Directive energy efficiency. Mass flow, vapour density tion to CO 2 technology (see chapter CO 2 in (2006/40/EC) has been passed to reduce and thus also the pressure drop are even mobile air conditioning systems, page 36), direct emissions in this application area. more favourable (approx. -40%). refrigerants with very low GWP values and Within the scope of the Directive, and start- similar thermodynamic properties as R134a R152a has been used for many years as a ing 2011, type approvals for new vehicles have been developed. will only be granted if they use refrigerants component in blends, but not as a single with a global warming potential (GWP) of substance refrigerant till now. Especially In early 2006, two refrigerant mixtures were less than 150. Consequently, this excludes advantageous is the very low global warm- introduced under the names "Blend H" R134a (GWP = 1430) which has been used ing potential (GWP = 124). (Honeywell) and "DP-1" (DuPont). INEOS Fluor followed with another version under so far in these systems. R152a is flammable – due to its low fluorine the trade name AC-1. In the broadest content – and classified in safety group A2. Meanwhile, alternative refrigerants and new sense, all of these refrigerants were blends As a result, increased safety requirements technologies were developed and tested. of various fluorinated molecules. This also involved a closer examination of demand individual design solutions and the use of R152a. safety measures along with the correspond- During the development and test phase it ing risk analysis. became obvious that not all acceptance For quite some time the automotive industry criteria could be met, and thus further For this reason, the use of R152a in mobile has agreed on so-called "Low GWP" refriger- examinations with these blends were dis - air conditioning systems for passenger cars ants. The latter is dealt with as follows. continued. (MAC) has not been implemented yet. Consequently, DuPont (meanwhile CO 2 technology, favored for this application for quite some time, has not been widely Chemours) and Honeywell bundled their implemented for a variety of reasons (see research and development activities in a also pages 12 and 36). joint venture which focused on 2,3,3,3- tetrafluoropropene (CF 3CF=CH 2). This refrigerant, designated R1234yf, belongs to the group of hydro fluoro olefins (HFO). These refrigerants are unsaturated HFCs with a chemical double bond.
11 HFC refrigerants
The global warming potential is extremely Toxicity investigations have shown very With view to the relatively simple conver - low (GWP = 4). When released to the atmo - positive results, as well as compatibility sion of mobile air conditioning systems, this sphere, the molecule rapidly disintegrates tests of the plastic and elastomer materials technology prevailed up to now over the within a few days, resulting in a very low used in the refrigeration circuit. Some lubri - competing CO 2 systems. GWP. This raises certain concerns regard - cants show increased chemical reactivity However, as already explained before, due ing the long-term stability in refrigeration cir - which, however, can be suppressed by a to the flammability of R1234yf, investiga - cuits under real conditions. suitable formulation and/or addition of tions focus on other technical solutions. However, extensive testing has demonstrat - "stabilizers". This includes active fire-extinguishing de- ed the required stability for mobile air condi - Operating experiences gained from labora - vices (e.g. with argon), but also enhance - tioning systems. tory and field trials to date allow a positive ments of CO 2 systems. R1234yf has lower flammability as meas- assessment, particularly with regard to per - For detailed information on properties and ured by ASTM 681, but requires signifi- formance and efficiency behaviour. For the the application, see chapter "Low GWP" cantly more ignition energy than R152a, for usual range of mobile air conditioning oper - HFOs and HFO/HFC blends as alternatives instance. Due to its low burning velocity and ation, refrigerating capacity and coefficient to HFCs, page 24. the high ignition force, it received a classifi - of performance (COP) are within a range of cation of the new safety group "A2L" ac- 5% compared with that of R134a. There - cording to ISO 817. fore, it is expected that simple system mod - In extensive test series, it has been shown ifications will provide the same performance that a potentially increased risk of the refrig - and efficiency as with R134a. erant flammability in MAC systems can be The critical temperature and pressure lev - avoided by implementing suitable construc - els are also similar, while the vapour densi - tive measures. However, some investiga - ties and mass flows are approximately 20% tions (e.g. by Daimler) also show an in- higher. The discharge gas temperature with creased risk. This is why various manu- this application is up to 10 K lower. facturers have intensified again the devel - opment of alternative technologies.
12 Refrigerant blends
Refrigerant blends "azeotropes" (e.g. R502, R507A) with ther - BITZER has accumulated extensive modynamic properties similar to single sub - experience with refrigerant blends. stance refrigerants, and "zeotropes" with Laboratory and field testing was com - Refrigerant blends have been developed for "gliding" phase changes (also see next menced at an early stage so that basic existing as well as for new plants with pro - chapter). The original development of information was obtained for the opti - mizing of the mixing proportions and perties making them comparable alternatives "zeotropes" mainly concentrated on special for testing suitable lubricants. Based to the previously used substances. applications in low temperature and heat on this data, a large supermarket plant pump systems. Actual system construction, It is necessary to distinguish between three – with 4 BITZER semi-hermetics in par - however, remained the exception. categories: allel – could already be commissioned A somewhat more common earlier practice in 1991. The use of these blends in the 1. Transitional or service blends most varied systems has been state-of- was the mixing of R12 to R22 in order to which mostly contain HCFC R22 as the the-art for many years – generally with improve the oil return and to reduce the dis - main constituent. They are primarily good experiences. charge gas temperature with higher pres - intended as service refrigerants for sure ratios. It was also usual to add R22 to older plants with view on the use ban of General characteristics of zeotropic R12 systems for improved performance, or R12, R502 and other CFCs. Correspond - blends to add hydrocarbons in the extra low tem - ing products are offered by various manu - perature range for a better oil transport. As opposed to azeotropic blends (e.g. facturers, there is practical experience R502, R507A), which behave as single sub - covering the necessary steps of conver - This possibility of specific "formulation" of stance refrigerants with regard to evapora - sion procedure. certain characteristics was indeed the basis tion and condensing processes, the phase for the development of a new generation of However, the same legal requirements as change with zeotropic fluids occurs in a blends. for R22 apply to the use and phase-out of "gliding" form over a certain range of tem - these blends (see page 8). At the beginning of this Report (see chapter perature. Refrigerant developments and legal situa - 2. HFC blends This "temperature glide" can be more or tion, page 3) it was already explained that These are substitutes for the refrigerants less pronounced, it depends mainly on the no direct single-substance alternatives (on R502, R22, R13B1 and R503. Above all, boiling points and the percentage propor - the basis of fluorinated hydrocarbons) exist R404A, R507A, R407C and R410A, are tions of the individual components. Certain for the previously used and current refriger - being used to a great extent. supplementary definitions are also used, ants of higher volumetric refrigeration cap- One group of these HFC blends also con - depending on the effective values, such as acity than R134a. This is why they can only tains hydrocarbon additives. The latter "near-azeotrope" or "semiazeotrope" for be "formulated" as blends. However, taking exhibit an improved solubility with lubri - less than 1 K glide. into account thermodynamic properties, cants, and under certain conditions they flammability, toxicity and global warming Essentially, this results in a small tempera - allow the use of conventional oils. In many potential, the list of potential candidates is ture increase already in the evaporation cases, this permits the conversion of exist - strongly limited. phase and a reduction during condensing. ing (H)CFC plants to chlorine-free refriger - In other words: At a certain pressure level, ants (ODP = 0) without the need for an oil For the previously developed CFC and the resulting saturation temperatures differ change. HCFC substitutes, the range of substances in the liquid and vapour phases (Fig. 11). was still comparably large, due to the fact 3. HFO/HFC blends that substances of high GWP could also be To enable a comparison with single sub - as successor generation of HFC refriger - used. However, for formulating blends with stance refrigerants, the evaporating and ants. It concerns blends of new "Low significantly reduced GWP, in addition to condensing temperatures have been often GWP" refrigerants (e.g. R1234yf) with R134a, R1234yf and R1234ze(E), primarily defined as mean values. As a conse- HFCs. The fundamental target is an addi - refrigerants R32, R125 and R152a can be quence the measured subcooling and tional decrease of the global warming po- used. Most of them are flammable. They superheating conditions (based on mean tential (GWP) as compared to established also exhibit considerable differences with values) are unrealistic. The effective differ - halogenated substances (see page 24). respect to their boiling points, which is why ence – based on dew and bubble tempera - Blends of two and three components already all "Low GWP" blends of high volumetric ture – is less in each case. These factors have a long history in the refrigeration trade. refrigerating capacity have a substantial are very important when assessing the min - A difference is made between the so called temperature glide (see next chapter). imum superheat at the compressor inlet (usually 5 to 7 K) and the quality of the refrigerant after the liquid receiver.
13 Refrigerant blends
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With regard to a uniform and easily compre - the pure gas and liquid phases is mainly o The plant always has to be charged with hensible definition of the rated compressor non-critical. Leaks in the phase change liquid refrigerant. When vapour is taken capacity, the revised standards EN 12900 areas, e.g. after the expansion valve, within from the charging cylinder, concentration and AHRI540 are applied. Evaporating and the evaporator and condenser/receiver are shifts may occur. condensing temperatures refer to saturated considered more significant. It is therefore o Since all blends contain at least one conditions (dew points). recommended that soldered or welded flammable component, the entry of air joints should be used in these sections. o Evaporating temperature according to into the system must be avoided. If the point A (Fig. 11) Extended investigations have shown in the proportion of air is too high, a critical shift o Condensing temperature according to meantime that leakage leads to less serious of the ignition point can occur under high point B (Fig. 11) changes in concentration than initially pressure and while evacuating. thought. In any case it is certain that the fol - In this case the assessment of the effective lowing substances of safety group A1 (see o The use of blends with a significant tem - superheat and subcooling temperatures will page 41) which are dealt with here cannot perature glide is not recommended for be simplified. develop any flammable mixtures, either plants with flooded evaporators. A large concentration shift is to be expected in It must however be considered that the inside or outside the circuit. Essentially sim - this type of evaporator, and as a result actual refrigerating capacity of the system ilar operating conditions and temperatures also in the circulating refrigerant mass can be higher than the rated compressor as before can be obtained by supplemen - flow. capacity. This is partly due to an effectively tary charging with the original refrigerant in lower temperature at the evaporator inlet. the case of a small temperature glide. A further characteristic of zeotropic refriger - Further conditions/recommendations con - ants is the potential concentration shift cerning the practical handling of blends when leakage occurs. Refrigerant loss in must also be considered:
14 Service blends
Service blends with the basic as hydrocarbons have especially good solu - Resulting design criteria/ component R22* as substitutes bility characteristics. Converting existing R502 plants for R502 For these blends two variations are offered The compressor and the components which in each case. When optimizing the blend are matched to R502 can remain in the sys - As a result of the continued refurbishment variations with regard to identical refriger- tem in most cases. The limitations in the of older installations, the importance of ating capacity as for R502 the laboratory application range must however be consid - these refrigerants is clearly on the decline. measurements showed a significantly in- ered: Higher discharge gas temperature For some of them, production has already creased discharge gas temperature (Fig. 13), than R502 with R402B**, R403A** and been discontinued. However, because of which above all, with higher suction gas R408A** or higher pressure levels with the development history of service blends, superheat (e.g. supermarket use) leads to R402A** and R403B**. these refrigerants will continue to be cover- limitations in the application range. The good solubility characteristics of R22 ed in this Report. On the other hand a higher proportion of and R290 increase the risk that, after con - These refrigerants belong to the group of R125 or R218, which has the effect of re- version of the plant, possible deposits of oil "Service blends" and have been offered ducing the discharge gas temperature to the decomposition products containing chlorine under the designations R402A/R402B* level of R502, results in somewhat higher are dissolved and find their way into the (HP80/HP81 – DuPont), R403A/R403B* refrigerating capacity (Fig. 14). compressor and control devices. Systems (formerly ISCEON ® 69S/69L) and R408A* where chemical stability was already insuf- With regard to material compatibility the (“Forane ®” FX10 – Arkema). ficient with R502 operation (bad mainte - blends can be judged similarly to (H)CFC nance, low drier capacity, high thermal The basic component is in each case R22, refrigerants. The use of conventional re- loading) are particularly at risk. the high discharge gas temperature of frigeration oil (preferably semi or full syn- which is significantly reduced by the addi - thetic) is also possible due to the R22 and Thus, generously dimensioned suction gas tion of chlorine free substances with low R290 proportions. filters and liquid line driers should be in- isentropic compression exponent (e.g. stalled for cleaning before conversion, and Apart from the positive aspects there are R125, R143a, R218). A characteristic fea- an oil change should be made after approxi - also some disadvantages. These substan - ture of these additives is an extraordinarily mately 100 hours operation. Further checks ces are alternatives only for a limited time. high mass flow, which enables the mixture are recommended. The R22 proportion has (although low) an to achieve a great similarity to R502. ozone depletion potential. Furthermore, the R290 (Propane) is added as the third com - additional components R125, R143a and * When using blends containing R22 legal regula - ponent to R402A/B and R403A/B to im- R218 have a high global warming potential tions are to be observed, see page 8. prove miscibility with traditional lubricants (GWP). ** Classification according to ASHRAE nomenclature.
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The operating conditions with R502 (includ - A further service blend was offered under Resulting design criteria/ ing discharge gas temperature and suction the designation R413A (ISCEON ® 49 – Converting existing R12 plants gas superheat) should be noted so that a DuPont), but replaced by R437A by the end Compressors and components can mostly comparison can be made with the values of 2008. However, because of the develop - remain in the system. However, when using after conversion. Depending upon the ment history of service blends, R413A will R413A and R437A the suitability must be results, control devices should possibly be continue to be covered in this Report. The checked against HFC refrigerants. The reset and other additional measures should constituents of R413A consist of the chlor- actual "retrofit" measures are mainly re- be taken as required. ine free substances R134a, R218, and stricted to changing the refrigerant (possibly R600a. In spite of the high R134a content, oil) and a careful check of the superheat the use of conventional lubricants is pos- setting of the expansion valve. sible because of the relatively low polarity of R218 and the favourable solubility of A significant temperature glide is present R600a. due to the relatively large differences in the boiling points of the individual substances, Service blends as R437A is a blend of R125, R134a, R600 which requires an exact knowledge of the substitutes for R12 (R500) and R601 with similar performance and saturation conditions (can be found from properties as R413A. This refrigerant also vapour tables of refrigerant manufacturer has zero ODP. Although (as experience already shows) and in the BITZER Refrigerant App) in order R134a is also well suited for the conversion However, due to the limited miscibility of to assess the effective suction gas super - of existing R12 plants, the general use for R413A and R437A with mineral and alkyl - heat. such a "retrofit" procedure is not always benzene oils, oil migration may result in In addition the application range must also possible. Not all compressors which have systems with a high oil circulation rate be observed. Different refrigerant types are previously been installed are designed for and/or a large liquid volume in the receiver required for high and low evaporating tem - the application with R134a. In addition a – for example if no oil separator is installed. conversion to R134a requires the possibility peratures or distinct capacity differences to make an oil change, which is for example If insufficient oil return to the compressor is must be considered. This is due to the not the case with most hermetic type com - observed, the refrigerant manufacturer steeper capacity characteristic, compared to pressors. recommends replacing part of the original R12. oil charge with ester oil. But from the com - Due to the partially high proportion of R22 Economical considerations also arise, espe - pressor manufacturer's view, such a meas- especially with the low temperature blends, cially with older plants where the effort of ure requires a very careful examination of the discharge gas temperature with some converting to R134a is relatively high. The the lubrication conditions. For example, if refrigerants is significantly higher than with chemical stability of such plants is also increased foam formation in the compressor R12. The application limits of the compres - often insufficient and thus the chance of crankcase is observed, a complete change sor should therefore be checked before success is very questionable. to ester oil will be necessary. Moreover, converting. Therefore "Service blends" are also avail- under the influence of the highly polarized able for such plants as an alternative to R134a blend of ester oil and HFC, the admixture of The remaining application criteria are simi - and are offered under the designations or conversion to ester oil leads to increased lar to those for the substitute substances for R401A/R401B, R409A. The main compo - dissolving of decomposition products and R502 which have already been mentioned. nents are the HCFC refrigerants R22, R124 dirt in the pipework. Therefore, generously and/or R142b. Either HFC R152a or R600a dimensioned suction clean-up filters must (Isobutane) is used as the third component. be provided. For further details, see the Operation with traditional lubricants (prefer - refrigerant manufacturer's "Guidelines". ably semi or full synthetic) is also possible * By using R22 containing blends the legal require - ments are to be followed, see chapter R22 as tran - due to the major proportion of HCFC. sitional refrigerant, page 8.
16 Substitutes for R22 in refrigeration systems
R404A and R507A as R134a, the temperature glide with the ter - the TEWI value. Other improvements are substitutes for R22 and R502 nary blend R404A within the relevant appli - possible in this respect due to further de- cation range is less than one Kelvin. The veloped system control. characteristics within the heat exchangers Nevertheless, due to their high global warm- These blends are chlorine free substitutes are therefore not very different than with ing potential (GWP), the use of R404A and (ODP = 0) for R22 as well as for R502 in azeotropes. The results obtained from heat R507A will no longer be allowed in the EU medium and low temperature ranges. transfer measurements show favourable in new installations from 2020. This has conditions. A composition which was already launched been settled in the F-Gas Regulation No. at the beginning of 1992 is known under the R507A is a binary substance combination 517/2014 to be applied since 2015. How- trade name Suva ® HP62 (DuPont). Long which even gives an azeotropic characteri - ever, the current requirement of phase-down term use has shown good results. Further stic over a relatively wide range. The condi - in connection with a strict quota system will blends were traded as Forane ® FX70 tions therefore tend to be even better. lead to an earlier phase-out in many appli - (Arkema) and Genetron ® AZ50 (Allied Sig - cations. For more detailed information, The performance (Fig. 16) gives hardly any nal/ Honeywell) or Solkane ® 507 (Solvay). please refer to BITZER brochure A-510. difference between the various substances HP62 and FX70 have been listed in the and ist very similar to R502. This also In the USA, Canada and Australia there are ASHRAE nomenclature as R404A and explains the high market penetration of also requirements to phase-out R404A and AZ50 as R507A. these refrigerants. With regard to the ther - R507A. For an international phase-down The basic components belong to the HFC modynamic properties, they are particularly (starting in 2019) of HCFC and HFC refriger- group, where R143a belongs to the flam- suitable for commercial medium and low ants, the so-called Kigali Amendment was mable category. Due to the combination temperature systems. agreed upon in 2016 as part of the Montreal with a relatively high proportion of R125 Protocol. Typical metallic materials are compatible the flammability is effectively counteracted, with HFC refrigerants. Elastomers, however, Alternatives with lower GWP are the HFC even in the case of leakage. must be adapted to the changed character- blends explained in the following (from page A feature of all three ingredients is the very istics. Suitable lubricants are polyol esters 18), as well as HFO/HFC blends being de- low isenropic compression exponent which (see chapter Lubricants for compressors, veloped and evaluated (from page 24). results in a similar, with even a tendency to page 40). Halogen free refrigerants or cascade be lower, discharge gas temperature to The relatively high global warming potential systems using different refrigerants are R502 (Fig. 15). The efficient application of (GWP = 3922 .. 3985), which is mainly also an option for specific applications single stage compressors with low evaporat- determined by the R143a and R125, is (from page 28). ing temperatures is therefore guaranteed. something of a hitch. However, it is better Due to the similar boiling points for R143a than R502 and with regard to the favourable and R125, with a relatively low proportion of energy demand also leads to a reduction of @ . >
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Resulting design criteria R407A/407B/407F/407H as the isentropic compression exponent is substitutes for R22 and R502 even higher than with R22. Rather high pro - The system technology can be based on portions of R125 and R134a are necessary the experience with R22 and R502 over a to match the characteristics at the level of wide area. As an alternative to the earlier described R404A and R507A. The flammability of R32 substitutes, additional mixtures have been On the thermodynamic side, a heat ex- is thus effectively suppressed, but the large developed based on R32 which is chlorine changer between the suction and liquid differences in boiling points with a high pro - free (ODP = 0) and flammable like R143a. line is recommended as this will improve portion of R134a lead to a larger tempera- The refrigerant R32 is also of the HFC type the refrigerating capacity and COP. ture glide. and initially was regarded as a main candi - date for R22 alternatives (page 20). How- The main advantage of R32 is the extraordi - BITZER offers the whole program of ever, due to extent of blend variations com - narily low global warming potential (GWP = reciprocating, scroll and screw com - parable thermodynamic characteristics to 675), so that even in combination with R125 pressors for R404A and R507A. R404A/R507A can also be obtained. and R134a it is significantly lower than with the R143a based alternatives mentioned Supplementary BITZER information con - These kind of refrigerants were marketed at above (R407A: GWP = 2107, R407F: GWP ® cerning the use of HFC blends first under the trade name KLEA 60/61 = 1825, R407H: GWP = 1490). (see also http://www.bitzer.de) (ICI) and are listed as R407A/R407B* in the ASHRAE nomenclature. Thus, they also comply with the require - o Technical Information KT-651 ment of the new EU F-Gas Regulation „Retrofitting of R22 systems to Honeywell has developed another blend which from 2020 will only allow refrigerants alternative refrigerants” with the trade name Performax ® LT (R407F of GWP < 2500. o Technical Information KT-510 according to ASHRAE nomenclature) and „Polyolester oils for reciprocating introduced it into the market, similar Daikin Measurements made with R32 containing compressors“ Chemical with R407H. For both blends, the blends do show certain capacity reductions R32 proportion is higher than for R407A, compared to R404A and R507A, with low while the R125 proportion is lower. With evaporating temperatures. The COP how- R407H, this results in certain restrictions for ever shows less deviation and is even higher low temperature applications. in medium temperature applications (Fig. 18). However, the necessary conditions for alter - natives containing R32 are not quite as * Meanwhile, R407B is no longer available in the mar - favourable compared to the R143a based ket. Due to the historical development of HFC blends this refrigerant will, however, still be considered in substitutes discussed earlier. The boiling this Report. point of R32 is very low at -52°C, in addition
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18 Substitutes for R22 in refrigeration systems
Whether these favourable conditions are pipework. Therefore, generously dimen - The material compatibility is comparable to confirmed in real applications is subject to sioned suction clean-up filters must be pro - the blends mentioned previously, the same the system design. An important factor is vided. applies to the lubricants. On account of the the significant temperature glide, which can good solubility of R600a, conventional lubri - have a negative influence upon the capac- Conversion of existing R404A/R507A cants can also be used under favourable ity/temperature difference of the evaporator systems to R407A/407B/407F/407H circumstances. and condenser. Larger differences in thermodynamic prop - In particular, advantages result during the With regard to the material compatibility, erties (e.g. mass flow, discharge gas tem - conversion of existing R22 and R502 R32 blends can be assessed similarly to perature) and the temperature glide of systems as mentioned above. However, for R404A and R507A; the same applies to the R407A/F/H may require the replacement of plants with high oil circulation rates and/or lubricants. control components and if necessary large liquid charge in the receiver, oil migra - retrofitting of additional compressor cooling tion might occur – for example if no oil Despite the relatively high proportion of when existing systems are converted. separator is installed. R125 and R134a in the R32 blends, the dis - For newly built systems, a specific design charge gas temperature is higher than with If insufficient oil return to the compressor is of components and system is necessary. the R143a based alternatives (especially for observed, the refrigerant manufacturer R407F and even to a higher degree with recommends replacing part of the original BITZER offers a comprehensive program R407H). This results in certain limitations in oil charge with ester oil. But from the com - of reciprocating and screw compressors the application range as well as the require - pressor manufacturer's view, such a meas- for R407A und R407F. An individual ment for additional cooling of compressors ure requires a very careful examination of selection of compressors for R407H is when operating at high pressure ratios. the lubrication conditions. For example, if in- possible upon demand. creased foam formation in the compressor 2-stage compressors can be applied very crankcase is observed, a complete change efficiently where especially large lift condi - to ester oil* will be necessary. Under the tions are found. An important advantage in R422A as substitute influence of the highly polarized blend of this case is the use of a liquid subcooler. for R22 and R502 ester oil and HFC, the admixture of or con - version to ester oil leads to increased dis - Resulting design criteria Amongst other aims, R422A (ISCEON ® solving of decomposition products and dirt The experience with R404A/R507A and MO79 – Chemours) was developed in order in the pipework. Therefore, generously R22 can be used for plant technology in to obtain a chlorine-free refrigerant (ODP = 0) dimensioned suction clean-up filters must many respects, although the temperature for the simple conversion of existing me- be provided. For further details, see the glide as well as the difference in the ther - dium and low temperature refrigeration refrigerant manufacturer's "Guidelines". modynamic properties have to be consid - systems using R22 and R502. From a thermodynamic point of view, a heat ered. This especially concerns the design exchanger between suction and liquid line and construction of heat exchangers and For this, it was necessary to formulate a is recommended, improving the refrigerating expansion valves. refrigerant with comparable performance and energy efficiency to that of R404A, capacity and coefficient of performance. Be- R507A, and R22, which also permits the sides this the resulting increase in operat- Converting existing R22 plants to use of conventional lubricants. ing temperatures leads to more favourable R407A/407B/407F/407H lubricating conditions (lower solubility). R422A is a zeotropic blend of the basic Practical experiences show that qualified components R125 and R134a with a small Due to the high global warming potential conversions are possible. Compared to R22 addition of R600a. Due to its relatively high (GWP ≥ 2500), R422A will no longer be the volumetric refrigeration capacity is near - R134a percentage, the temperature glide allowed for new installations in the EU from ly similar while the refrigerant mass flow is (see chapter Refrigerant Properties, page 2020 onwards. The requirements and re- only slightly higher. These are relatively 42) lies higher than for R404A, but lower strictions are specified in the F-Gas Regula - favourable conditions for the conversion of than other refrigerants with the same com - tion 517/2014. medium and low temperature R22 systems. ponent blends – such as R417A and R422D * General proposal for screw compressors and liquid The main components can remain in the (see page 22). chillers when used with DX evaporators with internal - system provided that they are compatible ly structured heat exchanger tubes. Furthermore, an The adiabatic exponent, and therefore also with HFC refrigerants and ester oils. individual check regarding possible additional meas- the discharge gas and oil temperatures of the ures will be necessary. However, special requirements placed on compressor, are lower than for R404A and BITZER compressors are suitable for the heat exchanger with regard to the signif - R507A. At extremely low temperatures, this R422A. An individual selection is pos- icant temperature glide must be considered. can be advantageous. However, in cases of sible upon demand. A conversion to ester oil is also necessary, low pressure ratio and suction gas super- which leads to increased dissolving of de- heat, this can be a disadvantage due to in- composition products and dirt in the creased refrigerant solution if ester oil is used.
19 Substitutes for R22 in A/C and heat pumps
Substitutes for R22 in air condi - R407C as substitute Thus, R407C also complies with the re- tioning systems and heat pumps for R22 quirement of the new EU F-Gas Regula- tion which from 2020 onwards will only allow refrigerants with GWP < 2500. How - As the HCFC refrigerant R22 (ODP = 0.05) Mixtures of HFC refrigerants R32, R125 and ever, the quantity limitation through the is accepted only as a transitional solution, a R134a were considered to be the preferred "phase-down" will also lead to significantly number of chlorine-free (ODP = 0) alterna- candidates for short-term substitutes for restricted availability. tives have been developed and tested exten - R22 in the EU in view of the early ban of The high temperature glide is a disadvan - sively. They are being used for a large R22. Performance values and efficiency are tage for usual applications which requires range of applications. highly comparable (Fig. 19). At first two blends of the same composition have been appropriate system design and can have a Experience shows, however, that none of introduced under the trade names AC9000* negative influence on the efficiency of the these substitutes can replace the refrigerant (DuPont) and KLEA ® 66* (ICI). They are heat exchangers (see chapter General char - R22 in all respects. Amongst others there listed in the ASHRAE nomenclature as acteristics of zeotropic blends, page 13). are differences in the volumetric refrigerat- R407C. In the meantime there are also fur - Due to the properties mentioned, R407C is ing capacity, restrictions in possible appli- ther blend varieties (e.g. R407A/R407F/ preferably an R22 substitute for air condi - cations, special requirements in system R407H) with somewhat differing composi - tioning and heat pump systems and (within design and considerably differing pressure tions, whose properties have been optimized certain limitations) also for medium tem- levels. According to the specific operating for particular applications (see page 18). perature refrigeration. In low temperature conditions, various alternatives may be con - refrigeration, because of the high proportion sidered. Unlike the substitutes for R22 in refriger- ation systems with identical blend compo - of R134a, a significant drop in refrigerating Apart from the single-component HFC re- nents (pages 18 and 19), the substitutes for capacity and COP is to be expected. There frigerant R134a, these are mainly blends R22 in air conditioning systems and heat is also the danger of an increased R134a (different compositions) of the components pumps under consideration contain higher concentration in the blend in evaporators, R32, R125, R134a, R143a, and R600(a). proportions of R32 and R134a. A good cor - with reduced performance and malfunction - The following description mainly concerns respondence with the properties of R22 in ing of the expansion valve (e.g. insufficient the development and potential applications terms of pressure levels, mass flow, vapour suction gas superheat). of these. The halogen-free substitutes NH , 3 density and volumetric refrigerating capacity Material compatibility is similar to that of the propane and propylene as well as CO 2 is thus achieved. In addition, the global blends discussed previously; the same ap- should also be considered, however, spe- warming potential is relatively low (GWP = plies to lubricants. cific criteria must be applied for their use 1774), which is a good presupposition for (description from page 28). favourable TEWI values. * Previous trade names are not used any more. In addition, R32 and HFO/HFC blends can also be used as alternatives (see chapter R32 as substitute for R22, from page 23).
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Resulting design criteria R410A as substitute for R22 Because of the negligible temperature glide (< 0.2 K), the general usability is similar to With regard to system technology, previous that of a pure refrigerant. experience with R22 can only be utilized to In addition to R407C, the near-azeotropic a limited extent. mixture listed by ASHRAE as R410A is The material compatibility is comparable to available and widely used for medium-sized the previously discussed blends, the same The distinctive temperature glide requires a capacities in air conditioning and heat pump applies to the lubricants. However, the pres - particular design of the main system com - applications. sure levels and the higher specific loads on ponents, e.g. evaporator, condenser, ex- the system components need to be taken pansion valve. In this context it must be An essential feature indicates nearly 50% into account. considered that heat exchangers should higher volumetric refrigerating capacity (Fig. preferably be laid out for counterflow opera - 21) compared to R22, but with the conse - Resulting design criteria tion and with optimized refrigerant distribu - quence of a proportional rise in system tion. There are also special requirements pressures (Fig. 22). The fundamental criteria for HFC blends also apply to the system technology with with regard to the adjustment of control At high condensing temperatures, energy R410A. However, the high pressure levels devices and service handling. consumption/COP initially seems to be less have to be considered (43°C condensing Furthermore, the use in systems with flood - favourable than with R22. temperature already corresponds to 26 bar ed evaporators is not recommended as this This is mainly due to the thermodynamic abs.). would result in a severe concentration shift properties. On the other hand, very high Compressors and other system components and layer formation in the evaporator. isentropic efficiencies are achievable (with designed for R22 are not suitable for this reciprocating and scroll compressors), so refrigerant (or only to a limited extent). BITZER can supply a widespread range that the real differences are lower. of semi-hermetic reciprocating, screw Though, suitable compressors and system and scroll compressors for R407C. Another aspect are the high heat transfer components are available. coefficients in evaporators and condensers Converting existing R22 plants to R407C determined in numerous test series, result- When considering to cover usual R22 appli - ing in especially favourable operating con- cation ranges, the significant differences in Because of the above mentioned criteria, ditions. With an optimized design, it is quite the thermodynamic properties (e.g. pres - no general guidelines can be defined. Each possible for the system to achieve a better sure levels, mass and volume flow, vapour case must be examined individually. overall efficiency than with other refriger- density) must be taken into account. This ants. also requires considerable constructional
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Fig. 21 R410A/R22 – comparison of performance data of a semi-hermetic Fig. 22 R410A/R22 – comparison of pressure levels compressor 21 Substitutes for R22 in A/C and heat pumps changes to compressors, heat exchangers, hydrocarbon additive. It is offered under R427A as a substitute for R22 and controls, as well as measures of tuning trade name ISCEON ® MO29 (Chemours) vibrations. There are stricter safety require - and listed as R422D in the ASHRAE This refrigerant blend was introduced some ments, e.g. affecting the quality and dimen - nomenclature. years ago under the trade name Forane ® sions of piping and flexible tube elements Another refrigerant belonging to the catego - FX100 (Arkema) and is now listed in the (for condensing temperatures of approx. ry of HFC/HC blends was introduced in ASHRAE nomenclature as R427A. 60°C/40 bar). 2009 under the trade name ISCEON ® The R22 substitute is offered for the conver - Another criterion is the relatively low critical MO99 (Chemours) – ASHRAE classifi- sion of existing R22 systems for which a temperature of 73°C. Irrespective of the cation R438A. This formulation was de- "zero ODP" solution is requested. It is an design of components on the high pressure signed especially for a higher critical tem - HFC mixture with base components side, the condensing temperature is thus perature for applications in hot climate R32/R125/R143a/R134a. limited. areas. The base components are R32, R125, R134a, R600 and R601a. In spite of the blend composition based on R410A complies with the requirements of pure HFC refrigerants, the manufacturer the EU F-Gas Regulation, which will only Like R407C, all four substitute refrigerants states that a simplified conversion proced- allow refrigerants with GWP < 2500 from are zeotropic blends with a more or less ure is possible. 2020 onwards. However, the quantity limi- significant temperature glide. In this re- tation through the "phase-down" will also spect, the criteria described for R407C This is facilitated by the R143a proportion. lead to significantly restricted availability. also apply here. Accordingly, when converting from R22 to Due to the extremely high demand for R427A, all it takes is a replacement of the Apart from a similar refrigeration capacity, R410A, a timely switch to alternatives is original oil charge with ester oil. Additional there are fundamental differences in ther - needed in the EU. flushing sequences are not required, as modynamic properties and in oil transport proportions of up to 15% of mineral oil behaviour. The high proportion of R125 For R410A, BITZER offers a series of and/or alkyl benzene have no significant causes a higher mass flow with R417A/B semi-hermetic reciprocating compres - effect on oil circulation in the system. and R422D than with R407C, a lower dis - sors and scroll compressors. charge gas temperature and a relatively However, it must be taken into account that high superheating enthalpy. These proper - the highly polarized mixture of ester oil and ties indicate that there are differences in the HFC will lead to increased dissolving of optimization of system components, and a decomposition products and dirt in the pipe - R417A/417B/422D/438A heat exchanger between liquid and suction work. Therefore, generously dimensioned as substitutes for R22 lines is of advantage. suction clean-up filters must be provided. Despite the predominant proportion of HFC Regarding refrigerating capacity, pressure Similar to the development of R422A (page refrigerants, conventional lubricants can be levels, mass flow and vapor density, R427A 19), one aim of developing these blends used to some extent because of the good is relatively close to R22. During retrofit, was to provide chlorine-free refrigerants solubility of the hydrocarbon constituent. essential components such as expansion (ODP = 0) for the simple conversion of However, in systems with a high oil circula - valves can remain in the system. Due to the existing R22 plants. tion rate and/or a large volume of liquid in high proportion of blend components with R417A was introduced to the market years the receiver, oil migration may result. low adiabatic exponent, the discharge gas ago, and is also offered under the trade temperature is considerably lower than with In such cases, additional measures are name ISCEON ® MO59 (Chemours). This R22, which has a positive effect at high necessary. For further information on oil substitute for R22 contains the blend com - compression ratios. return and lubricants see chapter “R422A ponents R125/R134a/R600 and therefore as substitute for R22 and R502” (page 19). It must be taken into account that this is differs considerably from e.g. R407C with a also a zeotropic blend with a distinct tem- Due to the high global warming potential correspondingly high proportion of R32. perature glide. Therefore the criteria de- (GWP ≥ 2500), R417B and R422D will no Meanwhile, a further refrigerant based on scribed for R407C apply here as well. longer be allowed for new installations in identical components, but with a higher the EU from 2020. The requirements and R125 content, has been offered under the restrictions are specified in the F-Gas Reg - ASHRAE designation R417B. Due to its ulation 517/2014. However, the "phase- lower R134a content, its volumetric refriger - down" quantity limitation will also lead to ating capacity and pressure levels are high - significantly restricted availability of R417A er than for R417A. This results in different and R438A. performance parameters and a different focus within the application range. BITZER compressors are suitable for use The same applies to a further blend with the with R417A/417B/422D/438A. An individ - same main components, but R600a as ual selection is possible upon request.
22 Substitutes for R22 in A/C and heat pumps
R427A meets the requirement of the EU R32 as substitute for R22 the flame speed is low. Therefore, R32 F-Gas Regulation, which will only allow (like R1234yf and R1234ze) has been refrigerants with GWP < 2500 from 2020. placed in the new safety group A2L ac- As described earlier, R32 belongs to the However, the quantity limitation due to the cording to ISO 817. HFC refrigerants, but initially it was mainly "phase-down" will also lead to significantly used as a component of refrigerant blends The resulting safety requirements are spe - restricted availability. only. An essential barrier for the application cified in the revised EN 378 (amended ver - BITZER compressors are suitable for as a pure substance so far is the flammabil- sion 2016). ity. This requires adequate charge limita - R427A. An individual selection is pos - R32 is also considered an alternative for tions and/or additional safety measures, sible upon demand. systems with larger refrigerant charge, e.g. especially with installations inside buildings. liquid chillers for air conditioning and pro - In addition there are very high pressure Supplementary information concerning cess applications and heat pumps pre - levels and discharge gas temperatures the use of HFC blends viously operated with R410A. However, (compression exponent higher than with (see also http://www.bitzer.de) depending on the installation site of the R22 and R410A). o Technical information KT-651 system, appropriate refrigerant charge “Retrofitting R22 systems to alterna - On the other hand, R32 has favorable ther - limits must be observed. On the other tive refrigerants” modynamic properties, e.g. very high evap- hand, there are no such restrictions when orating enthalpy and volumetric refriger- installed outdoors (without access to un- ating capacity, low vapor density (low authorized persons) and in machine rooms pressure drop in pipelines), low mass flow, (for example, according to EN 378-3: and favorable power input for compression. 2016). It should be noted, however, that The global warming potential is relatively R32 precharged chillers may be subject to low (GWP = 675). special conditions during transport (accord- ing to the Pressure Equipment Directive, Looking at these favorable properties and R32 is classified under Fluid Group 1). taking into account the additional effort for emission reductions, R32 will increasingly BITZER scroll compressors of the ORBIT be used as a refrigerant in factory produced GSD6 and GSD8 series have been systems (A/C units and heat pumps) with approved and released for use with R32. low refrigerant charges. Depending on the product group, a It was proven in flammability tests that the special compressor version may be necessary ignition energy is very high and required.
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Aspects on the development of R1234ze(E) is sometimes referred to as a ment projects with “Low GWP” refrigerants, HFO and HFO/HFC refrigerants R134a substitute, but its volumetric refriger- page 26. ating capacity is more than 20% lower For R134a alternatives, the situation is than that of R134a or R1234yf. The boiling more favorable. Due to the already quite The decision to use the "low GWP" refriger - point (-19°C) also greatly restricts the appli - low GWP of R134a, a blend with R1234yf ant R1234yf in mobile air conditioning sys - cation at lower evaporation temperatures. and/or R1234ze(E) allows a formulation of tems for passenger cars (see pages 11/12) Its preferred use is therefore in liquid non-flammable refrigerants with a GWP of also led to the development of alternatives chillers and high temperature applications. approx. 600. for further mobile applications as well as For further information see chapter Refriger- Thus, primarily two directions for develop - stationary refrigeration, air conditioning and ants for special applications, page 37. heat pump systems. ment are pursued: The list of further potential HFO refriger - o Non-flammable HFC alternatives Primary objectives are the use of single- ants is relatively long. However, there are (blends) with GWP values according to component refrigerants and of mixtures only few substances that meet the require - the above mentioned limits – safety with significantly reduced GWP and similar ments in terms of thermodynamic proper - group A1. Regarding safety require - thermodynamic properties as the HFCs ties, flammability, toxicity, chemical stabili - ments, these refrigerants can then be currently used predominantly. ty, compatibility with materials and lubri- utilized similar to currently used HFCs. An essential basic component for this is cants. These include e.g. the non-flammable o Flammable HFC alternatives (blends) (safety group A1) low-pressure refrigerants with GWP values below the above men - R1234yf (CF 3CF=CH 2). This refrigerant belongs to the group of hydro-fluoro-olefins R1336mzz(Z), R1233zd(E) and R1224yd(Z). tioned possible limits – according to (HFO), i.e. unsaturated HFCs with molecu - These are primarily an option for liquid safety group A2L (for refrigerants of lar double bonds. This group of HFOs also chillers with large turbo-compressors, and lower flammability). they can be used with positive displace - includes another substance called This group of refrigerants is then subject to ment compressors in high-temperature R1234ze(E), which has been mainly used charge limitations according to future re- applications. R1233zd(E) and R1224yd(Z) as a propellant for PU foam and aerosol. quirements for A2L refrigerants. R1234ze(E) differs from R1234yf in its belong to the group of HCFO (hydro- molecular structure. chloro-fluoro-olefins); they have a (very) Meanwhile, there are development projects low ozone depletion potential (ODP). Upon using refrigerant components with a much Both substances are the preferred choice release into the atmosphere, however, the higher volumetric refrigerating capacity and in terms of their properties and are also molecule rapidly disintegrates. pressure than R1234yf and R1234ze(E). used as basic components in HFO/HFC These can then be used to "formulate" mix - On the other hand, there are currently no blends. The Global Warming Potential is tures with R32 as an alternative to R410A, candidates from the HFO family with similar very low − R1234yf with GWP 4 and which are optimised for certain properties. volumetric refrigerating capacity such as R1234ze(E) with GWP 7. However, these See additional information in chapter Fur - R22/R407C, R404A/R507A and R410A refrigerants are flammable (safety class ther development projects with “Low GWP” available for commercial use. Direct alter - A2L), meaning the refrigerant quantity in refrigerants, page 26. the system must be considered in light of natives for these refrigerants with signifi - the installation location. In addition, there cantly lower GWPs must therefore be “con - R134a alternatives remain open questions concerning the structed” as a mixture of R1234yf and/or long-term stability in stationary systems R1234ze(E) with HFC refrigerants, possibly In addition to the flammable HFO refriger - where long life cycles are common. Fur - also small proportions of hydrocarbons, ants R1234yf and R1234ze(E) already thermore the volumetric refrigerating CO 2 or other suitable molecules. described, non-flammable mixtures are capacity is relatively low; for R1234yf it is Though, due to the properties of the HFC now also available as R134a alternatives. close to the level of R134a, and more than refrigerants suitable as blend components, As previously mentioned, the initial situa - 20% lower for R1234ze(E). flammability and GWP are related diametri - tion is most favorable for these. There is also some uncertainty concerning cally to one another. In other words: Blends They achieve GWP values of approx. 600 − flammability. In safety data sheets, as alternatives to R22/R407C of GWP less than half of R134a (GWP = 1430). In R1234ze(E) is declared as non-flammable. < approx. 900 are flammable. This is also addition, this type of blends can have However, this only applies to its transport true with alternatives for R404A/R507A in azeotropic properties, so that they can be and storage. When used as a refrigerant, a blends of GWP < approx. 1300 and for used like pure refrigerants. higher reference temperature for flammabil - R410A in blends of GWP < approx. 2000. ity tests of 60°C applies. At this tempera - The reason for this is the high GWP of ture, R1234ze(E) is flammable and there - each of the required non-flammable com - fore classified in safety class A2L, like ponents. There are a few exceptions, which R1234yf. are discussed in chapter Further develop-
24 HFOs and HFO/HFC blends
For quite some time a blend has been Substitutes for R404A/R507A and from approx. 400 to 500 can be achieved. applied on a larger scale in real systems – R410A With a higher HFO proportion, the GWP this was developed by Chemours and is can be reduced even further, but at the Since the available HFO molecules called Opteon TM XP-10. Results available cost of a clearly reduced refrigerating capa - (R1234yf und R1234ze) show a consider - today are promising. city. ably smaller volumetric refrigerating capaci - This is also true for an R134a alternative ty than the above mentioned HFC refriger- All blend options described above with designated Solstice ® N-13 and offered by ants, relatively large HFC proportions with R1234yf and R1234ze(E) show a more or Honeywell which, however, differs regard - high volumetric refrigerating capacity must less distinct temperature glide due to boil- ing the blend composition. be added for the particular alternatives. ing point differences of the individual com - The potential list of candidates is rather ponents. The same criteria apply as de- The refrigerants are listed in the ASHRAE limited, one option is R32 with its relatively scribed in context with R407C. nomenclature under R513A (Chemours) low GWP of 675. and R450A (Honeywell). Beyond that, the discharge gas tempera- However, one disadvantage is its flamma- ture of most R404A/R507A alternatives is The same category also includes the re- bility (A2L), resulting also in a flammable considerably higher than for these HFC frigerant blends ARM-42 (ARKEMA) as well blend upon adding fairly large proportions blends. as R456A (Mexichem AC5X). in order to increase the volumetric refriger- In single stage low temperature systems All options show refrigerating capacity, ating capacity while maintaining a favor- this may lead to restrictions in the com - power input, and pressure levels similar to able GWP. pressor application range or require special R134a. Thus, components and system For a non-flammable blend, on the other measures for additional cooling. In trans - technology can be taken over, only minor hand, a fairly large proportion of refriger- port applications or in low temperature changes like superheat adjustment of the ants with high fluor content (e.g. R125) systems with smaller condensing units, the expansion valves are necessary. must be added. A drawback here is the compressors used can often not meet the Polyolester oils are suitable lubricants high GWP of more than approx. 900 for required operating ranges, due to the high which must meet special requirements, e.g. non-flammable R22/R407C alternatives discharge gas temperatures. This is why for the utilization of additives. and more than approx. 1300 with options refrigerant blends based on R32 and HFO for R404A/ R507A. Compared to R404A/ with a higher proportion of R125 have also Prospects are especially favorable for R507A, however, this means a reduction been developed. The GWP is slightly supermarket applications in the medium down to a third. above 2000, but below the limit of 2500 set temperature range in a cascade with CO 2 in the EU F-Gas Regulation from 2020. The for low temperature, just as in liquid chillers The future drastic "phase-down " of F-Gases, main advantage of such blends is their with higher refrigerant charges where the e.g. as part of the EU F-Gas Regulation, moderate discharge gas temperature, use of flammable or toxic refrigerants already leads to a demand for R404A/ which allows the operation within the typi - would require comprehensive safety meas- R507A substitutes with GWP values clearly cal application limits of R404A. ures. below 500. Although this is possible with an adequate composition of the blend (high Tab 4 shows the potential blend compo - A special case is the refrigerant R515B: an proportions of HFO, R152a, possibly also nents for the alternatives described above. azeotropic mixture of R1234ze(E) and hydrocarbons), the disadvantage will be its With some refrigerants the mixture compo - small amounts of R227ea. This combina - flammability (safety groups A2L or A2). In nents for R22/R407C and R404A/R507A tion, declared by the manufacturer Honey- this case, the application will have higher substitutes are identical, but their distri- well as an R134a alternative, is non- safety requirements and will need an ad- bution in percent is different. flammable (A1) despite the very low GWP equately adjusted system technology. of approx. 300. In the meantime, Chemours, Honeywell, R410A currently has no non-flammable Arkema, Mexichem and Daikin Chemical However, as with the previously described alternatives for commercial applications. have offered corresponding chemical vari - R1234ze(E), this can only be considered Either R32 (see page 23) as pure sub- ants for laboratory and field tests, and in an alternative under certain restrictions. stance or blends of R32 and HFO can be some cases already for commercial use. A The volumetric refrigerating capacity is also used. Due to its high volumetric refrigerating number of refrigerants are still declared as more than 20% lower than that of R134a or capacity, this requires a very high propor - being under development and are only R1234yf. tion of R32, which is why only GWP values made available for testing purposes under
25 HFOs and HFO/HFC blends special agreements. Until now, trade of the specific application and a special that, there are unanswered questions about names are often used although a larger agreement. the chemical long-term stability under the number of HFO/HFC blends are already special requirements of the refrigeration In the meantime, Honeywell has unveiled listed in the ASHRAE nomenclature. cycle. According to the safety data sheet, the new development of a non-flammable this substance is also subject to very strin - Tab. 5 lists a range of currently available (A1) R410A alternative under the trade gent safety requirements. refrigerants or refrigerants declared as name Solstice ® N-41 – listed by ASHRAE development products. Due to the large as R466A. A final assessment of these mixtures is number of different versions and the poten - therefore currently not possible. R466A is a mixture of R32, R125 and tial changes in development products, R13I1 (CF I − trifluoroiodomethane), an BITZER has so far tested only some of the 3 Comment from a compressor manufactur - iodine-methane derivative not previously new refrigerants. This is why in the tables er’s point of view: used in refrigeration. CF I is not flam- on pages 41/42 (Tab. 6/7) for the time 3 It should be an aim to limit the product mable, as is R125, which means that the being only refrigerant properties of non - variety currently becoming apparent and to refrigerant is not flammable (A1), even with flammable alternatives for R134a and reduce the future supply to a few "stan - the relatively high proportion of R32 (A2L). R404A/R507A (GWP < 1500) are listed dard refrigerants". It will not be possible for which have already received an ASHRAE Despite the noticeable proportion of R125 component and equipment manufacturers number and are commercially available. with a GWP of 3500 (AR4), the total GWP nor for installers and service companies to is 733 (AR4) and therefore in the range of deal in practice with a larger range of For testing the "Low GWP" refrigerants, R32, R447B and R452B, which are classi - alternatives. AHRI (USA) has initiated the "Alternative fied as A2L. Refrigerants Evaluation Program (AREP)". BITZER was involved early on in various It was established to investigate and evalu - From a thermodynamic point of view, the projects with HFO/HFC blends and was ate a series of the products including halo - differences between R410A and R466A are thus able to gain important insight into gen-free refrigerants. Some of these are relatively small. Volumetric refrigerating the use of these refrigerants. Semi-her - also listed in Tab 5. capacity, pressure levels and discharge metic reciprocating compressors of the temperature are slightly higher, the refriger- ECOLINE series as well as CS. and HS. Further development projects with "Low ant mass flow deviates slightly more screw compressors can already be used GWP" refrigerants (about 15 to 20% higher). The temperature with this new generation of refrigerants. glide is also very low. For specific applications, Chemours has Several of them have already been developed a non-flammable (A1) R410A Hence, R466A appears to be a promising qualified and approved, the respective alternative, which is marketed in selected substitute for R410A. However, due to the performance data is available on the countries and regions under the trade CF I share, there are still uncertainties 3 BITZER SOFTWARE. name Opteon TM XP41 – listed by ASHRAE regarding long-term chemical stability and as R463A. material compatibility under the special Scroll compressors of the ORBIT GSD6 requirements of the refrigeration cycle. and GSD8 series are approved and re- It is a mixture of R32, R125, R1234yf, leased for the use of the R32/HFO mixtu - R134a and CO with a GWP of 1494. Further investigation is required, so a final 2 res R452B and R454B. Depending on the Despite the high proportion of R32 and assessment of R466A is currently not pos - product group, a special compressor R1234yf, flammability is suppressed by sible. In any case, as matters stand, this version may be required. mixing with R125, R134a and CO 2. refrigerant cannot be used in state-of-the- art systems (retrofit). The supply of com - Regarding thermodynamics, the differences Further information on the application pressors for laboratory tests requires an to R410A are comparatively small. The of HFOs and HFO/HFC blends see bro - individual review of the specific application addition of CO , however, leads to a chure A-510, section 6 and brochure 2 as well as a special agreement. distinct temperature glide, which may No. 378 20 387. cause certain limitations for the application AGC Chemicals propagates R1123 and places particular demand on the (CF 2=CHF) mixed with R32, partially with design of the heat exchangers. addition of R134yf, as an alternative to R410A and pure R32. It is an HCFO with All mixture components and their properties very low ozone depletion potential (ODP). are well known, which means there are no R1123 has a significantly higher volumetric additional particularities regarding material refrigeration capacity than R1234yf or compatibility in comparison to the already R1234ze(E) and is advantageous in this known R410A alternatives. respect. However, the pressure level is The supply of compressors for laboratory even higher than of R32 and the critical or field tests requires an individual review temperature is only about 59°C. Apart from
26 HFOs and HFO/HFC blends
09.18 Current Alternatives Components / Mixture components "Low GWP" alternatives HFC-Refrigerants Safety GWP ④ R1234yf R1234ze(E) R32 R152a R134a R125 R13I1 ⑤ CO 2② R290 ② Group A2L A2L A2L A2 A1 A1 A1 A1 A3
GWP 4 7 675 124 1430 3500 <1 1 3
A1 ~ 600 R134a A2L < 150 GWP 1430 A2L < 10 A1 < 2500 ① A1 ~ 1400 R404A/R507A A2L < 250 GWP 3922/3985 A2L ③ < 150 A2 < 150 A1 900..1400 R22/R407C A2L < 250 GWP 1810/1774 A2L < 150 A2 < 150 A1 < 1500 R410A A1 < 750 GWP 2088 A2L < 750 A2L ~ 400..750
① Refrigerating capacity, mass flow, discharge gas temperature similar to R404A ② Only low percentage – due to temperature glide (CO 2) and flammability (R290) ③ R32/HFO blends show lower refrigerating capacity than reference refrigerant, the addtion of CO 2 leads to high temperature glide ④ Approx. values according to IPCC IV (AR4) ⑤ R13I1 (CF 3I − tri-fluoroiodomethane) is an iodine-methane derivative
Tab. 4 Potential mixture components for "Low GWP" alternatives (examples) 09.18 Current Low GWP" Alternatives for HFC refrigerant HFC-Refrigerants "
ASHRAE Trade Composition GWP ③ Safety Boiling tempe- Temperature Number Name (with blends) AR4 (AR5) group rature [°C] ④ glide [K] ⑤ R450A Solstice ® N-13 Honeywell R1234ze(E)/134a 604 (547) A1 -24 0.6 R456A AC5X ⑥ Mexichem R32/1234ze(E)/134a 687 (627) A1 -30 4.8 Opteon TM XP10 Chemours R 5 1 3 A R513A ⑧ Daikin Chemical R 1 2 3 4 y f / 1 3 4 a 6 3 1 ( 5 7 3 ) A 1 - 3 0 0 R134a R515B ② – Honeywell R1234ze(E)/227ea 293 (299) A1 -19 0 GWP 1430 ① R1234yf various _ 4 (< 1) A2L -30 0 R1234ze(E) ② various _ 7 (< 1) A2L -19 0 R444A AC5 ⑥ Mexichem R32/152a/1234ze(E) 92 (89) A2L -34 10 R516A ARM-42 ⑦ Arkema R1234yf/R152a/R134a 142 (131) A2L -29 0 R448A Solstice ® N-40 Honeywell R32/125/1234yf/1234ze(E)/134a 1387 (1273) A1 -46 6.2 Opteon TM XP40 Chemours R 4 4 9 A Forane ® 449 Arkema R 3 2 / 1 2 5 / 1 2 3 4 y f / 1 3 4 a 1 3 9 7 ( 1 2 8 2 ) A 1 - 4 6 5 .7 R460B LTR4X ⑥ Mexichem R32/125/1234ze(E)/134a 1352 (1242) A1 -45 8.2 R452A Opteon TM XP44 Chemours R32/125/1234yf 2140 (1945) A1 -47 3.8 R452C R452C ⑦ Arkema R32/125/1234yf 2220 (2019) A1 -48 3.4 R404A/R507A R460A LTR10 ⑥ Mexichem R32/125/1234ze(E)/134a 2103 (1911) A1 -45 7.4 GWP 3922/3985 Opteon TM XL40 Chemours R 4 5 4 A R454A ⑧ Daikin Chemical R 3 2 / 1 2 3 4 y f 2 3 9 ( 2 3 8 ) A 2 L - 4 8 5 .7 (R22/R407) – ARM-20b ⑦ Arkema R32/1234yf/152a 251 (251) A2L -47 6.1 R454C ② Opteon TM XL20 Chemours R32/1234yf 148 (146) A2L -46 7.8 ® R455A Solstice L-40X Honeywell R32/1234yf/CO 2 148 (146) A2L -52 12.8 R457A ② ARM-20a ⑦ Arkema R32/1234yf/152a 139 (139) A2L -43 7.2 R459B ② LTR1 ⑥ Mexichem R32/1234yf/1234ze(E) 144 (143) A2L -44 7.9 R465A ARM-25 ⑦⑨ Arkema R32/1234yf/290 145 (143) A2 -52 11.8 R 2 2 / R 4 0 7 C R449C Opteon TM XP20 Chemours R32/125/1234yf/134a 1251 (1146) A1 -44 6.1 GWP 1810/1774 R32 various – 675 (677) A2L -52 0 Opteon TM XL55 Chemours R 4 5 2 B Solstice ® L-41y Honeywell R 3 2 / 1 2 5 / 1 2 3 4 y f 6 9 8 ( 6 7 6 ) A 2 L - 5 1 0 .9 R 4 1 0 A R454B Opteon TM XL41 Chemours R32/1234yf 466 (467) A2L -51 1.0 G W P 2 0 8 8 R459A ARM-71a ⑦ Arkema R32/1234yf/1234ze(E) 460 (461) A2L -50 1.7 R463A Opteon TM XP41 ⑩ Chemours R32/125/1234yf/134a/CO 2 1494 (1377) A1 -59 12.2 ® R466A Solstice N-41 ⑧⑩ Honeywell R32/125/13I1(CF 3I) 733 (696) A1 -52 0.7 ① The relatively low GWP allows the use of R134a also on longer term. ⑥ Development product ② Lower volumetric refrigerating capacity than reference refrigerant ⑦ Available 2018 .. 2020 ③ AR4: according to IPCC IV // AR5: according to IPCC V – time horizon 100 years ⑧ Marketing presumably in 2019 ④ Rounded values ⑨ Preferably for commercial appliances ⑤ Total glide from bubble to dew line at 1 bar (abs.) ⑩ See information under chapter Further development projects with „Low GWP“ refrigerants. Tab. 5 Low GWP " alternatives for HFC refrigerants " 27 Halogen free (natural) refrigerants
NH 3 (Ammonia) as able for large plants, makes the control of These measures significantly increase the alternative refrigerant the refrigerant injection more difficult with expenditure for NH 3 plants, especially for small capacities. medium and smaller capacities. A further criteria to be considered is the cor - Efforts are therefore being made world-wide The refrigerant NH 3 has been used for more than a century in industrial and larger refriger- rosive action on copper containing materials; to develop simpler systems which can also ation plants. It has no ozone depletion po- pipe lines must therefore be made of steel. be used in the commercial area. The development of motor windings resist- tential and no direct global warming poten- A part of the research programs is dealing ant to NH is hindered, too. Another difficulty tial. The efficiency is at least as good as that 3 with part soluble lubricants, with the aim of arises from the electrical conductivity of the of R22, in some areas even more favour- improving oil circulation in the system. Sim - refrigerant with higher moisture content. able; the contribution to the indirect global plified methods for automatic return of non- warming effect is therefore small. In addition, Additional characteristics include toxicity and soluble oils are also being examined as an its price is exceptionally low. Is it therefore flammability, which require special safety alternative. an ideal refrigerant and an optimum substi - measures for the construction and operation tute for R22 or an alternative for HFCs!? of such plants. BITZER is strongly involved in these NH 3 has indeed very positive features, projects and has a large number of which can be exploited quite well in large operating compressors. The experi- refrigeration plants. Resulting design and ences up to now have revealed that construction criteria Unfortunately there are also negative as- systems with partly soluble oils are dif - pects, which restrict the wider use in the com- Based on the present "state of technology", ficult to manage. The moisture content mercial area or require costly and some- industrial NH 3 systems demand a complete - in the system has an important influ- times new technical developments. ly different plant technology, compared to ence on the chemical stability of the usual commercial systems. circuit and the wear of the compressor. A disadvantage with NH 3 is the high isen- Besides, high refrigerant solution in the tropic exponent (NH 3 = 1.31 / R22 = 1.19 / Due to the insolubility with the lubricating oil oil (wet operation, insufficient oil tem - R134a = 1.1), which results in a discharge and the specific characteristics of the re- perature) leads to strong wear on the temperature even significantly higher than frigerant, high efficiency oil separators and bearings and other moving parts. This that of R22. Single stage compression is flooded evaporators with gravity or pump is due to the enormous volume change therefore already subject to certain restric - circulation are usually employed. Because when NH 3 evaporates in the lubricated tions below an evaporating temperature of of the danger to the public and to the pro - areas. around -10°C. duct to be cooled, the evaporator often can - These research developments are not be installed directly at the cold space The question of suitable lubricants is also being continued, with focus also on and the heat must be transported by a sec- not satisfactorily solved for smaller plants in alternative solutions for non-soluble ondary refrigerant circuit. some kinds of applications. The most com - lubricants. monly used mineral oils and polyalpha-ole - Due to the unfavorable thermal behaviour, fins are not soluble with the refrigerant. They two stage compressors or screw compres - Various equipment manufacturers have must be separated with complex technology sors with generously sized oil coolers must developed special evaporators, allowing and seriously limit the use of "direct expan - be used even at medium pressure ratios. significantly reduced refrigerant charge. sion evaporators" due to the deterioration in There is a strong trend towards so-called Refrigerant lines, heat exchangers and fit - the heat transfer. "low charge" systems, i.a. with regard to tings must be made of steel; larger size safety requirements, which are also largely Special demands are made on the thermal pipe lines must be examined by a certified determined by the refrigerant charge. stability of the lubricants due to the high inspector. discharge gas temperatures. This is especi - In addition to this, there are developments Depending upon the size of the plant and ally valid when automatic operation is con- for the "sealing" of NH plants: compact the refrigerant charge, corresponding safety 3 sidered where the oil is supposed to remain liquid chillers (charge below 50 kg), in- measures and special machine rooms are in the circuit for years without losing any of stalled in a closed container and partly with required. its stability. an integrated water reservoir to absorb NH 3 NH 3 has an extraordinarily high enthalpy dif - The refrigeration compressor is usually of in case of a leak. This type of compact unit ference and thus a very small circulating "open" design, the drive motor is a separate can be installed in areas which were pre - mass flow (approximately 13 to 15% com- component. viously reserved for plants with refrigerants pared to R22). This feature, which is favour- of safety group A1 due to safety requirements.
28 Halogen free (natural) refrigerants
An assessment of NH 3 compact systems – Conversion of existing plants R723 (NH₃/DME) as instead of systems using HFC refrigerants The refrigerant NH 3 is not suitable for the an alternative to NH 3 and conventional technology – is only pos- conversion of existing (H)CFC or HFC sible on an individual basis, taking into plants; they must be constructed completely The previously described experiences with account the particular application. From a new with all components. merely technical viewpoint and presuppos- the use of NH 3 in commercial refrigeration plants with direct evaporation caused fur- ing an acceptable price level, a wider range Supplementary BITZER information ther experiments on the basis of NH 3 by of products will supposedly become avail- concerning the application of NH able in the foreseeable future. 3 adding an oil soluble refrigerant component. (see also http://www.bitzer.de) Main goals were improved oil transport and o Technical Information KT-640 heat transmission with conventional lubri - The product range from BITZER today “Application of Ammonia (NH 3) cants, along with a reduced discharge gas includes an extensive selection of opti - as an alternative refrigerant” temperature for the extended application mized NH 3 compressors for various range with single stage compressors. types of lubricants: The result of this research project is a re- o Single stage open reciprocating frigerant blend of NH (60%) and dimethyl compressors (displacement 19 to 3 ether "DME" (40%), It was developed by the 152 m 3/h with 1450 rpm) for air con - Institute of Air Handling and Refrigeration ditioning, medium temperature and (ILK) in Dresden, Germany, and has been booster applications applied in a series of real systems. As a o Open screw compressors (displace - largely inorganic refrigerant it received the ment 84 to 1015 m 3/h – with parallel designation R723 due to it its average mo- operation to 4060 m 3/h – with 2900 lecular weight of 23 kg/kmol in accordance rpm) for air conditioning, medium to the standard refrigerant nomenclature. and low temperature cooling. Options for low temperature cooling: – Single stage operation – Economiser operation – Booster operation
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29 Halogen free (natural) refrigerants
DME was selected as an additional compo - fore, the proportion of DME leads to im- R290 (Propane) as nent for its good solubility and high individ- proved oil solubility and a partial miscibility. alternative refrigerant ual stability. Its boiling point is -26°C, the Furthermore, the relatively low liquid density adiabatic exponent is relatively low, it is not and an increased DME concentration in the R290 (propane) can also be used as a sub - toxic and available in high purity. In the oil enhances oil circulation. PAG oils would stitute refrigerant. Being an organic com - abovementioned concentration NH and be fully or partly miscible with R723 for typi - 3 pound (hydrocarbon), it has no ozone DME form an azeotropic blend character- cal applications, but are not recommended depletion potential and a negligible direct ised by a slightly higher pressure level than because of the chemical stability and high global warming effect. To take into conside - pure NH . The boiling point lies at -36.5°C solubility in the compressor crankcase 3 ration however, is a certain contribution to (NH -33.4°C), 26 bar (abs.) of condensing (strong vapour development in the bear- 3 summer smog. pressure corresponds to 58.2°C (NH 3 ings). 59.7°C). Pressure levels and refrigerating capacity Tests have shown that the heat transfer are similar to R22, and its temperature The discharge gas temperature in air condi - coefficient at evaporation and high heat flux behaviour is as favourable as with R134a. tioning and medium temperature ranges is improved in systems with R723 and min- decreases by about 10 to 25 K (Fig. 24) eral oil compared to NH 3 with mineral oil. There are no particular problems with mate - and allows for an extended application rial. In contrast to NH , copper materials Further characteristics are toxicity and flam - 3 range to higher pressure ratios. Thermody - are also suitable, so that semi-hermetic and mability. The DME content lowers the igni - namic calculations conclude a single-digit hermetic compressors are possible. Com - tion point in air from 15 to 6%. However, the percent rise in refrigerating capacity com- mon mineral oils of HCFC systems can be azeotrope is ranked in safety group B2, but pared to NH . The coefficient of performance used here as a lubricant over a wide appli - 3 may receive a different classification in case is similar and is even more favourable at cation range. Polyol esters (POE) and poly - of a revised assessment. high pressure ratios, confirmed by experi - alpha-olefins (PAO) offer even more favor- ments. Due to the lower temperature level able properties. during compression, an improved volumetric Resulting layout criteria Refrigeration plants with R290 have been in and isentropic efficiency can be expected, Experiences with the NH compact systems operation world-wide for many years, mainly at least with reciprocating compressors in 3 described above can be used in plant tech - in the industrial area – it is a "proven" refriger- case of an increasing pressure ratio. nology. However, the component layout has ant. Due to the higher molecular weight of DME, to be adjusted considering the higher mass Meanwhile R290 is also used in smaller com- mass flow and vapour density increase by flow. By appropriate selection of the evapo - pact systems with low refrigerant charges nearly 50% compared to NH 3, although this rator and the expansion valve, a very stable like residential air-conditioning units and is of little importance to commercial plants, superheat control must be ensured. Due to heat pumps. Furthermore, a rising trend can especially in short circuits. In conventional be observed in its use with commercial re- the improved oil solubility, "wet operation” industrial refrigeration plants, however, this can have considerable negative results frigeration systems and chillers. is a substantial criterion with regard to pres - compared to NH systems with non-soluble 3 Propane is offered also as a mixture with sure drops and refrigerant circulation. oil. Isobutane (R600a) or Ethan (R170), in These considerations again show that the With regard to safety regulations, the same order to provide a similar performance to preferred application area of R723 is in criteria apply to installation and operation as halocarbon refrigerants. Pure Isobutane is commercial applications and especially in for NH plants. mostly intended as a substitute for R12 in liquid chillers. 3 small systems (preferably domestic refriger- Suitable compressors are special NH ver - Material compatibility is comparable to that 3 ators). sions which possibly have to be adapted to of NH . Although non-ferrous metals (e.g. 3 the mass flow and the continuous oil circu - The disadvantage of hydrocarbons is their CuNi alloys, bronze, hard solders) are lation. An oil separator is usually not neces - high flammability, therefore they are classi - potentially suitable, provided minimum sary with reciprocating compressors. fied as refrigerants of "Safety Group A3". water content in the system (< 1000 ppm), Based on the refrigerant charge quantities a system design similar to typical ammonia BITZER N H reciprocating compressors commonly used in commercial systems, the practise is recommended. 3 are suitable for R723 in principle. An system design and risk analysis must be in Mineral oils or (preferred) polyalpha olefin individual selection of specifically adapt- accordance with explosion protection regu - are suitable lubricants. As mentioned be- ed compressors is possible on demand. lations.
30 Halogen free (natural) refrigerants
Semi-hermetic compressors in so-called should be considered (approximately 55 to a specifically equipped compressor ver - "hermetically sealed" systems are in this 60% compared to R22). An advantage here sion is offered. Inquiries and orders case subject to regulations for hazardous is that the refrigerant charge can be greatly need a clear reference to R290. The zone 2 (only seldom and short term risk). reduced. From the thermodynamic point of handling of the order includes an individua l Safety demands include special devices to view, an internal heat exchanger between agreement between the contract part - protect against excess pressures and speci - the suction and liquid line is recommended ners. Open reciprocating compressors al arrangements for the electrical system. In as this will improve the refrigerating capaci - are also available for R290, together with addition, measures are required to ensure ty and COP. a comprehensive program of flame-proof hazard free ventilation to effectively prevent accessories which may be required. Owing to the particularly high solubility of a flammable gas mixture in case of refriger- R290 (and R1270) in common lubricants, ant leakage. Conversion of existing plants with R22 BITZER R290/R1270 compressors are or HFC Design requirements are defined by stan - charged with special oil of a high viscosity dards (e.g. EN378) and may vary in differ- index and particularly good tribological Due to the special safety measures when ent countries. For systems applied in the properties. using R290, a conversion of existing sys - EU, an assessment according to EC Direc- Again, an internal heat exchanger is of tems only seems possible in exceptional tive 94/9/EC (ATEX) may become necessary advantage as it leads to higher oil tempera - cases. They are limited to systems, which as well. With open compressors, this will tures, lower solubility and therefore im- can be modified to meet the corresponding possibly lead to a classification in zone 1 ‒ proved viscosity. safety regulations with an acceptable effort. which demands, however, electrical equip - Due to the very favourable temperature ment in special flame-proof design. Supplementary BITZER information behaviour (Fig. 25), single stage compres - concerning the use of R290 sors can be used down to approximately Resulting design criteria (see also http://www.bitzer.de) - 40°C evaporation temperature. R290 could Apart from the measures mentioned above, thus also be considered as an alternative o Technical Information KT-660 propane systems require practically no spe - for some of the HFC blends. “Application of Propane and Propylene cial features in the medium and low tempera - with semi-hermetic compressors” ture ranges compared to a usual (H)CFC A range of ECOLINE compressors and and HFC system. When sizing components, CS. compact screws is available for however, the relatively low mass flow R290. Due to the individual requirements
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Propylene (R1270) as an ever, tests by hydrocarbon manufacturers charge gas temperature of R1270, restrictions alternative to Propane and stability tests in real applications show are partly necessary at high pressure ratios. practically no reactivity in refrigeration sys - tems. Doubts have occasionally been A range of ECOLINE compressors and CS. For some time there has been increasing voiced in some literature regarding possible compact screws is available for R1270. interest in using propylene (propene) as a carcinogenic effects of propylene. These Due to the individual requirements a substitute for R22 or HFC. Due to its higher assumptions have been disproved by ap- specifically equipped compressor version volumetric refrigerating capacity and lower propriate studies. is offered. Inquiries and orders need a boiling temperature (compared to R290), clear reference to R1270. applications in medium and low temperature Resulting design criteria systems are of particular interest, e.g. liquid The handling of the order includes an indi - chillers for supermarkets. On the other With regard to system technology, experi - vidual agreement between the contract hand, higher pressure levels (> 20%) and ence gained from the use of propane can partners. Open reciprocating compressors discharge gas temperatures have to be widely be applied to propylene. However, are also available for R1270, together with taken into consideration, thus restricting the component dimensions have to be altered a comprehensive program of flame-proof possible application range. due to higher volumetric refrigerating capac - accessories which may be required. ity (Fig. 26). The compressor displacement Material compatibility is comparable to is correspondingly lower, as are the suction Supplementary BITZER information propane, as is the choice of lubricants. and high pressure volume flows. Because concerning the use of R1270 Propylene is also easily inflammable and of higher vapour density, the mass flow is (see also http://www.bitzer.de) belongs to the safety group A3. The same almost the same as for R290. As liquid den - o Technical Information KT-660 safety regulations are therefore to be sity is nearly identical, the same applies to “Application of Propane and Propylene observed as with propane (page 31). the liquid volume in circulation. with semi-hermetic compressors” Due to the chemical double bond, propylene As with R290, an internal heat exchanger reacts quite easily, risking polymerization at between suction and liquid lines is of high pressure and temperature levels. How - advantage. However, due to the higher dis -
32 Halogen free (natural) refrigerants
Carbon dioxide R744 (CO 2) were e.g. marine refrigeration systems. With long periods. It should further be noted that as an alternative refrigerant the introduction of the "(H)CFC Safety Re- the heat transfer coefficients of CO 2 are frigerants", CO 2 became less popular and considerably higher than of other refrige - and secondary fluid had nearly disappeared by the 1950’s. rants – with the potential of very low tempe - rature differences in evaporators, conden - The main reasons for that are its relatively CO 2 has had a long tradition in the refriger- sers, and gas coolers. Moreover, the ation technology reaching far into the 19th unfavourable thermodynamic characteristics necessary pipe dimensions are very small, century. It has no ozone depleting potential, for usual applications in refrigeration and air and the influence of the pressure drop is a negligible direct global warming potential conditioning. comparably low. In addition, when used as (GWP = 1), is chemically inactive, non-flam - a secondary fluid, the energy demand for The discharge pressure with CO 2 is ex- mable and not toxic in the classical sense. tremely high, and the critical temperature at circulation pumps is extremely low. Therefore, CO is not subjected to the strin - 2 31°C (74 bar) very low. Depending on the In the following section, a few examples of gent containment demands of HFCs (F-Gas heat sink temperature at the high pressure subcritical systems and resulting design cri - Regulation) and flammable or toxic re- side, transcritical operations with pressures teria are described. An additional section frigerants. However, compared to HFCs the beyond 100 bar are required. Under these provides details on transcritical applica- lower critical value in air has to be consid- conditions, energy efficiency is often lower tions. ered. For closed rooms, this may require than in the classic vapour compression pro - special safety and detection systems. cess (with condensation), therefore the indi - rect global warming effect is higher. CO 2 is also low in cost and there is no Subcritical CO 2 applications necessity for recovery and disposal. In addi - Nonetheless, there is a range of applica - From energy and pressure level points of tion, it has a very high volumetric refrigerat- tions in which CO can be used very eco- view, very beneficial applications can be ing capacity: depending on operating condi - 2 nomically and with favourable eco-efficiency. seen for industrial and larger commercial tions, approx. 5 to 8 times as high as R22 These include subcritical cascade plants, refrigeration plants. For this, CO can be and NH . 2 3 but also transcritical systems, in which the used as a secondary fluid in a cascade sys - Above all, the safety relevant characteristics temperature glide on the high pressure side tem and if required, in combination with a were an essential reason for the initial wide - can be used advantageously, or the system further booster stage for lower evaporating spread use. The main focus for applications conditions permit subcritical operation for temperatures (Fig. 30).
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33 Halogen free (natural) refrigerants
The operating conditions are always subcrit - often used with NH 3 plants. The essential with view to an even distribution of the ical which guarantees good efficiency lev - difference is the condensing of CO 2 in the injected CO 2. els. In the most favourable application cascade cooler, while the receiver tank In the case of a system breakdown where a range (approx. -10 to -50°C), pressures are (accumulator) only serves as a supply ves - high rise in pressure could occur, safety still on a level where already available com- sel. valves can vent the CO to the atmosphere ponents or items in development, e.g. for 2 The extremely high volumetric refrigerating with the necessary precautions. As an alter - R410A, can be matched with acceptable capacity of CO (latent heat through the native, additional cooling units for CO con - effort. 2 2 changing of phases) leads to very low mass densation are also used where longer shut- flow rates, allows for small cross sectional off periods can be bridged without a critical Resulting design criteria pipe and minimal energy needs for the circu- pressure increase. lating pumps. For the high temperature side of such a For systems in commercial applications, a cascade system, a compact cooling unit can There are different solutions for the combi - direct expansion version is possible as well. be used, whose evaporator serves on the nation with a further compression stage, e.g. Supermarket plants with their usually widely secondary side as the condenser for CO . for low temperatures. 2 branched pipe work offer an especially Chlorine-free refrigerants are suitable, e.g. Fig. 30 shows a variation with an additional good potential in this regard: The medium NH , HCs or HFCs, HFO and HFO/HFC 3 receiver, which one or more booster com - temperature system is carried out in a con - blends. pressors will bring down to the necessary ventional design or with a secondary circuit, With NH 3, the cascade heat exchanger evaporation pressure. Likewise, the dis - for low temperature application combined should be designed in a way that the dread - charge gas is fed into the cascade cooler, with a CO 2 cascade system (for subcritical ed build-up of ammonium carbonate in the condenses and is carried over to the receiv - operation). A system example is shown in case of leakage is prevented. This technol - er (MT). The feeding of the low pressure Fig. 31. ogy has been applied in breweries for a receiver (LT) is achieved by a level control For a general application, however, not all long time. device. Instead of conventional pump circu - requirements can be met at the moment. It lation the booster stage can also be built as A secondary circuit for larger plants with is worth considering that system technology a so-called LPR system. CO 2 could be constructed utilising, to a changes in many respects and specially ad- wide extent, the same principles for a low The circulation pump is thus not necessary, justed components are necessary to meet pressure pump circulating system, as is but the number of evaporators is then limited the demands.
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Fig. 30 Casacde system with CO 2 for industrial applications Fig. 31 Conventional refrigeration system combined with CO2 low temperature cascade
34 Halogen free (natural) refrigerants
The compressors, for example, must be an intermediate pressure receiver. Depend - fore still limited, but with an upward trend. properly designed because of the high ing on the temperature curve of the heat Apart from these specific applications, there vapour density and pressure levels (particu - sink, a system designed for transcritical is also a range of developments for the larly on the suction side). There are also operation can also be operated subcritically classical areas of refrigeration and air-con - specific requirements with regard to materi - ‒ with higher efficiency. In this case, the ditioning, e.g. supermarket refrigeration. als. Furthermore only highly dehydrated gas cooler becomes the condenser. Installations with parallel compounded com - CO must be used. pressors are in operation to a larger scale. 2 Another feature of transcritical operation is They are predominantly booster systems High demands are made on lubricants as the necessary control of the high pressure where medium and low temperature circuits well. Conventional oils are mostly not misci - to a defined level. This "optimum pressure" are connected (without heat exchanger). ble and therefore require costly measures is determined as a function of gas cooler The operating experience and the calculat - to return the oil from the system. On the outlet temperature by means of balancing ed energy costs show promising results. other hand, if miscible and highly soluble between the highest possible enthalpy dif - However, the investment costs are still POE are used, the viscosity is strongly ference and at once minimum compression higher than for conventional plants with reduced. Further information to lubricants work. It must be adapted to the relevant HFCs and direct expansion. see page 40 and Fig. 37, page 44. operating conditions using an intelligent modulating controller (see system example, On the one hand, the favourable energy For subcritical CO applications BITZER 2 Fig. 32). costs are due to the high degree of opti - offers two series of special compres - mized components and the system control, sors. As described before, under purely thermo - as well as the previously described advan - dynamic aspects, the transcritical operating tages regarding heat transfer and pressure Supplementary BITZER information con - mode appears to be unfavourable in terms drop. On the other hand, these installations cerning compressor selection for sub- of energy efficiency. In fact, this is true for are preferably used in climate zones permit - critical CO systems systems with a fairly high temperature level 2 ting very high running times in subcritical (see also http://www.bitzer.de) of the heat sink on the high pressure side. operation due to the annual ambient tem - However, additional measures can improve o Brochure KP-120 perature profile. Semi-hermetic reciprocating compres - efficiency, such as the use of parallel com - pression (economiser system) and/or ejec - For increasing the efficiency of CO super - sors for subcritical CO 2 applications 2 (LP/HP standstill pressures up to tors or expanders for recovering the throt- market systems and for using them in 30/53 bar) tling losses during expansion of the warmer climate zones, the technologies o Brochure KP-122 refrigerant. described above using parallel compres- sion and/or ejectors are increasingly used. Semi-hermetic reciprocating compres - Apart from that, there are application areas sors for subcritical CO 2 applications in which a transcritical process is advanta - Therefore, but also because of very (LP/HP standstill pressures up to geous in energy demand. These include demanding technology and requirements for 100 bar) heat pumps for sanitary water or drying pro - qualification of planners and service person - o Additional publications on request cesses. With the usually very high tempera- nel, CO 2 technology cannot be regarded as ture gradients between the discharge tem - a general replacement for plants using HFC perature at the gas cooler intake and the refrigerants. Transcritical CO 2 applications heat sink intake temperature, a very low gas temperature outlet is achievable. This is Transcritical processes are characterized in facilitated by the temperature glide curve Resulting design criteria that the heat rejection on the high pressure and the relatively high mean temperature side proceeds isobar but not isotherm. Detailed information on this topic would go difference between CO vapour and sec - Contrary to the condensation process dur - 2 beyond the scope of this publication. In any ondary fluid. The low gas outlet temperature ing subcritical operation, gas cooling (desu - case, the system and control techniques leads to a particularly high enthalpy differ - perheating) occurs, with corresponding are substantially different from conventional ence, and therefore to a high system COP. temperature glide. Therefore, the heat plants. Already when considering pressure exchanger is described as gas cooler. As Low-capacity sanitary water heat pumps are levels as well as volume and mass flow long as operation remains above the critical already manufactured and used in large ratios specially developed components, pressure (74 bar), only high-density vapour quantities. Plants for medium to higher controls, and safety devices as well as suit - will be transported. Condensation only capacities (e.g. hotels, swimming pools, ably dimensioned pipework must be pro- takes place after expansion to a lower pres- drying systems) must be planned and vided. sure level – e.g. by interstage expansion in realised individually. Their number is there -
35 Halogen free (natural) refrigerants
The compressor technology is particularly For transcritical CO 2 applications, typical ambient conditions appear to be demanding. The special requirements result BITZER offers a wide range of special unfavourable. But it must be considered in a completely independent approach. For compressors. Their use is aimed at spe - that present R134a systems are less effi - example, this involves design, materials cific applications, therefore individual cient than stationary plants of the same (bursting resistance), displacement, crank examination and assessment are capacity, because of specific installation gear, working valves, lubrication system, as required. conditions and high pressure losses in well as compressor and motor cooling. pipework and heat exchangers. With CO 2, Hereby, the high thermal load severely lim - Suplementary BITZER information con - pressure losses have significantly less influ - its the application for single-stage compres - cerning compressor selection for trans - ence. Moreover, system efficiency is further sion. Low temperature cooling requires critical CO 2 systems improved by the high heat transfer coeffi - 2-stage operation, whereby separate high and (see also http://www.bitzer.de) cients in the heat exchangers. low pressure compressors are particularly o Brochure KP-130 This is why optimized CO air conditioning advantageous with parallel compounded 2 Semi-hermetic reciprocating compres - systems are able to achieve efficiencies systems. sors for transcritical CO 2 applications comparable to those of R134a. Regarding Additional publications upon request The criteria mentioned above in connection o the usual leakage rates of such systems, a with subcritical systems apply to an even more favourable balance is obtained in higher degree for lubricants. For further terms of TEWI. information to lubricants see page 40 and CO in mobile 2 From today's viewpoint, it is not yet possible Fig. 37, page 44. air-conditioning systems to make a prediction as to whether CO 2 can Further development is necessary in vari - in the long run prevail in this application. It Within the scope of the long-discussed ous areas, and transcritical CO technology certainly also depends on the experience 2 measures for reducing direct refrigerant cannot in general be regarded as state-of- with "low GWP" refrigerants that have been emissions, and the ban on the use of the-art. introduced by the automotive industry (see R134a in MAC systems within the EU, the chapter "Low GWP" HFO refrigerants development of CO systems has been 2 R1234yf and R1234ze(E), page 11). Further pursued intensively since several years. aspects such as operating safety, costs, At first glance, efficiency and therefore indi - and global logistics will play an important rect emissions from CO 2 systems under role.
Simplified sketch
&2%RRVWHU6\VWHP
07 /7
Fig. 32 Example of a transcritical CO 2 Booster system
36 Refrigerants for special applications
R124 and R142b Chlorine free substitutes for are within reach. The volumetric refriger- as substitutes for special applications ating capacity is almost identical to R124. R114 and R12B1 The "Low GWP" refrigerant R1234ze(E) can Due to the limited market for systems with also be regarded as a potential candidate In place of R114 and R12B1 previously extra high and low temperature applica - for extra high temperature applications used in high-temperature heat pumps and tions, the development of alternative refrige - (page 24). Compared to R124, its refriger- crane air conditioning systems, HCFCs rants and system components for these has ating capacity is 10 to 20% higher, its pres - R124 and R142b can still be used as alter - been pursued less intensely. sure level about 25% higher. At identical natives in most regions outside of the EU. refrigerating capacities, the mass flow dif - In the meantime, a group of alternatives for fers only slightly. Its critical temperature is With these gases it is also possible to use the CFC R114 and Halon R12B1 (high tem - 107°C, which would enable an economical long proven lubricants, preferably mineral perature), R13B1, R13 and R503 (extra low operation up to a condensing temperature oils and alkyl benzenes with high viscosity. temperature) have been offered as replace - of about 90°C. Though, like R1234yf, Because of their ozone depleting potential, ments. On closer examination, however, the R1234ze(E) has low flammability and there - these refrigerants will only be an interim thermodynamic properties of the alterna- fore classified into the new safety group solution. In the EU member states, the tives differ considerably from the previously A2L. The corresponding safety regulations application of HCFCs is no longer allowed. used substances. This can cause costly must be observed. For R124 and R142b the same restrictions changes especially with the conversion of As no sufficient operating experience is are valid as for R22 (page 8). The flamma - existing systems. available so far, the suitability of this refrige - bility of R142b and the resulting safety rant for long-term use cannot be assessed implications should also be considered yet. (safety group A2). Alternatives for R114 For high temperature heat pumps in pro - Resulting design criteria/ and R12B1 cess technology and special applications at Converting existing plants high temperatures, Chemours has present - ed an HFO-based refrigerant called Opte - Compared to R114, the alternatives have R227ea and R236fa are considered suitable on TM MZ (R1336mzz(Z)). Its critical tem- lower boiling temperatures (approx. -10°C), substitutes even though they may no longer perature is 171°C, the boiling temperature which results in larger differences in the be used in new installations in the EU from 33.1°C. This enables an operation at con - pressure levels and volumetric refrigerating 2020, due to their high GWP. densing temperatures far above 100°C for capacities. This leads to stronger limitations R227ea cannot be seen as a full replace - which only purpose-built compressors and in the application range at high evaporating ment. Although tests and experience in real system components can be used. and condensing temperatures. plants show favorable results, a critical tem - R1336mzz(Z) has a GWP < 10 but is not Converting an existing installation will in perature of 102°C limits the condensing flammable according to tests. This means a most cases necessitate the exchange of the temperature to 85..90°C with conventional classification in safety group A1. compressor and control devices. Owing to plant technology. the lower volume flow (higher volumetric A more detailed evaluation is not yet possi - R236fa provides the more favourable condi - refrigerating capacity), adjustments to the ble with respect to the chemical stability of tions at least in this regard – the critical evaporator and the suction line may be the refrigerant and of the lubricants at the temperature is above 120°C. A disadvan- required. very high temperatures and the usually very tage, however, is the lower volumetric re- long operating cycles of such systems. The frigerating capacity. It is similar to R114 and Over the previous years BITZER com - special applications also include cogene- 40% below the performance of R124, which pressors have been found to be well ration systems – the so-called "Organic is widely used for extra high temperature suited with R124 and R142b in actual Rankine Cycle" (ORC ) – which become applications today. installations. Depending on the applica - increasingly important. In addition to tion range and compressor type modifi - R600a (Isobutane) will be an interesting R1336mzz(Z) as a potentially suitable op- cations are necessary, however. Perfor - alternative where safety regulations allow erating fluid, a series of other substances mance data including further design the use of hydrocarbons (safety group A3). are also possible, depending on the tem- instructions are available on request. With a critical temperature of 135°C, con - perature level of the heat source and the densing temperatures of 100°C and more heat sink.
37 Refrigerants for special applications
They include R245fa (GWP = 1050) having in their construction accordingly. For mass flow are relatively high, and dis - a critical temperature of 154°C, which like several years BITZER has been involved charge gas temperature is very low. Liquid R1336mzz(Z) is also suitable as refrigerant in various projects and has already subcooling is of particular advantage. for chillers with large centrifugal compres - gained important knowledge with this Both of the mentioned refrigerants have sors. technology and experience in design and fairly high pressure levels and are therefore application. limited to 40..45°C condensing tempera- Solvay offers further refrigerants for ORC A comprehensive description of ORC ture with the usually applied 2-stage com - applications, containing the base compo - systems would go beyond the scope of pressors. They also show less capacity nent R365mfc. A product with the trade this Refrigerant Report. Further informa - than R13B1 at evaporating temperatures ® name Solkatherm SES36 already pre- tion is available upon request. below -60°C. sented several years ago contains perfluoro- In addition to this, the steep fall of pressure polyether as a blend component. It is an limits the application at very low tempera - azeotropic blend with a critical temperature Alternatives for R13B1 tures and may require a change to a cas - of 178°C. Meanwhile two zeotropic blends cade system with e.g. R23, R508A/B or containing R365mfc and R227ea have been R170 (ethane) in the low temperature Besides R410A, ISCEON ® MO89 (DuPont) developed whose critical temperatures are stage. 177°C and 182°C, due to different mixing can be regarded as potential R13B1 substi - ratios. They are available under the trade tute. For R410A, a substantially higher dis - Lubrication and material compatibility are names Solkatherm ® SES24 and SES30. charge gas temperature than for R13B1 is similar to other HFC blends. to be considered, which restricts the appli - In ORC systems zeotropic behavior may be The EU F-Gas Regulation (Annex III) pro - cation range even in 2-stage compression advantageous. In the case of single-phase vides an exemption "for applications systems to a greater extent. heat sources and heat sinks, the tempera - designed to cool products below -50°C". ture difference at the so-called "pitch point" ISCEON ® MO89 has been used for many This means that even after 2020, refriger- can be raised by the gliding evaporation years, preferably in freeze-drying plants. ants with GWP > 2500 can be used in new and condensation. This leads to improved Meanwhile, production has ceased. Howev - plants. Due to the "phase-down" however, heat transmission due to the higher driving er, for historical reasons the refrigerant will quantities will be limited, resulting in a con - average temperature difference. continue to be included in this Report. It is a siderable increase in price and very limited mixture of R125 and R218 with a small pro - availability. As an expander for ORC systems screw portion of R290. Due to the properties of It is therefore imperative to develop alter - and scroll compressors can be adapted the two main components, density and native solutions for which, however, no overall recommendation is possible. Two- stage compressors may be operated e.g. with R448A/449A (safety group A1) or R1270 (A3) down to an evaporation tem - perature of -60..- 65°C. Although R404A/ R507A alternatives with GWP < approx. 250 (safety group A2L) are potentially pos - sible, so far only limited experience has been gained even for typical low tempera -
@ WR r&
. ture refrigeration. >
WF r& %
At evaporating temperatures of down to ΔW .
5 RK
R -50..-52°C, operation with CO is also W 2 H
F possible − either in a two-stage or a cas - Q H U
H cade system. I I L G
H Y
L However, each variant generally requires a W $ D O H specific design and laboratory tests. U ದ 5 H
U X W %DVLV5% D U H S P 2 H W 0 V 1 D J 2 ( H J & U 6 D ,
K F V L '
Fig. 33 R13B1/HFC alternatives – comparison of discharge gas temperatures of a 2-stage compressor 38 Refrigerants for special applications
Alternatives for R13 possible or would involve unjustifiable lubricants with a high resistance to oxida - and R503 expenses and high costs in the relevant tion which must also be suitable for the special applications. special requirements at low temperature conditions. Following these challenges, research pro - For these substances, the situation is still jects have been initiated, in which the use Investigations are ongoing. A final assess - quite favorable from a purely technical of N 2O (nitrous oxide) and mixtures of N 2O ment is not yet possible, which is why no point of view; they can be replaced by R23 and CO 2 are examined in more detail. guidelines can currently be drawn up for and R508A/R508B. R170 (ethane) is also Extensive examinations and tests at the the design and implementation of such suitable if the safety regulations allow a Karlsruhe University of Applied Sciences systems. flammable substance (safety group A3). and the Institute of Air Handling and Re- frigeration (ILK) in Dresden show revealing BITZER has carried out investigations Due to the partly steeper pressure curve of results. and also collected experiences with the alternative refrigerants and the higher several of the substitutes mentioned. discharge gas temperature of R23 com- N O (R744A) has similar thermodynamic 2 Performance data and instructions are pared to R13, differences in performance properties and pressures as CO , identical 2 available on request. Due to the indivi - and application ranges for the compressors molecular weight, a very low triple point dual system technology for these spe - must be considered. Heat exchangers and (-90.8°C) and a critical temperature of cial installations, consultation with controls have to be adapted individually. 36.4°C. The GWP is 298, which is a frac - BITZER is necessary. tion of the R23 and R508A/B values. In As lubricants for R23 and R508A/B, polyol sum, an ideal alternative for special appli - ester oils are suitable, but must be cations up to about -80°C evaporating tem - matched for the special requirements at perature? extreme low temperatures. At first glance, these are very positive fea - R170 is also well soluble with conventional tures. Unfortunately, there are also nega- oils, but an adaptation to the temperature tive aspects that virtually preclude the use will be necessary. of N 2O as a pure substance. Applications with these refrigerants are Pure N O as a refrigerant is a safety risk: It purely for cooling products below -50°C. 2 has a narcotic effect and promotes fire. Hence, the exemption described in the pre - N O can oxidize other substances. In addi - vious chapter in the EU F-Gas Regulation 2 tion, under specific conditions (pressure, applies in particular. temperature or ignition source), exothermic For R23 and R508A/B, however, the decomposition reactions can occur, which effects of "phase-down" are particularly fundamentally call into question the perma - serious. The GWP values range from nently safe operation of a refrigeration 13200 to 14800 (AR4). Even relatively system with pure N 2O. small quantities are therefore very much at By adding CO in higher percentages (over the expense of the available quotas. 2 approx. 15%), the triple point is slightly Apart from R170 (ethane) with the special shifted towards higher temperatures, but at safety precautions required for A3 refriger- the same time a positive effect ("phlegmati - ants, there are no directly comparable zation") on oxidation and chemical decom- alternatives for R23 and R508A/B within position is achieved. The safety risk is the group of HFOs or HFO/HFC mixtures reduced significantly, and material compati - (safety groups A1 or A2L). In many cases, bility is considerably improved. Neverthe - however, the use of A3 refrigerants is not less, there are special challenges i.a. for
39 Lubricants
Lubricants for compressors are therefore less suitable for semi-herme - (Ammonia) as alternative refrigerant (page tic and hermetic compressors. They are 28) and supplementary information (see primarily used in mobile air conditioning below). systems with open drive compressors, Positive displacement compressors ‒ as Further information see Fig. 37 “Overview where special requirements for lubrication are predominantly used in commercial and lubricants”, page 44 and explanations for and best solubility/miscibility are required industrial refrigeration, air conditioning and the particular refrigerants. because of a high oil circulation rate. To heat pump systems ‒ are commonly oil- avoid copper plating, non-ferrous metals lubricated. Despite appropriate construc- Supplementary BITZER information con - are used in these systems. tional measures and/or installation of an oil cerning lubricants separator, a small amount of oil is pumped The remaining refrigeration industry so far (see also http://www.bitzer.de) into the circuit together with the compress- prefers POE oils. The extensive experience o Technical Information KT-500 ed gas flow. To stabilise the oil balance, gained with them is positive if the water „Refrigeration oil for reciprocating suitable measures for continuous oil return content in the oil does not significantly compressors with (H)CFC or NH ” must be taken. Oils that are soluble and exceed 100 ppm. However, only oils speci - 3 o Technical Information KT-510 miscible with the refrigerant are advantage - fied by the compressor manufacturer may „Polyolester oils BSE32 and BSE55 for ous. The refrigerant dissolved in the oil sig - be used. Because of the increased reactivi - BITZER reciprocating compressors“ nificantly reduces the viscosity, improving ty of HFOs with oil, this is especially true o Technical Information KT-640 oil fluidity and minimising the negative for systems with these refrigerants. „Application of Ammonia (NH ) as an influence on heat transfer in heat exchan - 3 Compressors for factory-made air conditio - alternative refrigerant” – chapter: gers. ners and chillers are also increasingly "Lubricants and their influence on the In the past, so-called naphthenic mineral being charged with polyvinyl ether (PVE) system design" oils and synthetic alkylbenzenes were pre - oils. Although they are more hygroscopic o Technical Information KT-660 ferred. For systems with CFC and HCFC than POE, they are very resistant to hydro - „Use of propane (R290) and propene refrigerants (for example R22) and hydro - lysis, thermally and chemically stable, have (R1270) in semi-hermetic BITZER carbons, they are very favorable with good lubricating properties and high dielec - compressors” – chapter: "Lubricants" regard to solubility and miscibility. On the tric strength. In contrast to POE, they are o Operating Instructions KB-120 and other hand, owing to their low polarity, they less prone to the formation of metal soaps KB-130 are insufficiently miscible with the highly and thus offer more security against blok - „Semi-hermetic reciprocating com - polar HFC and HFO refrigerants and are kage of capillaries. pressors for CO 2 applications“ therefore not properly and sufficiently o Manuals for screw compressors Special requirements for the lubricants drawn into the refrigeration cycle. SH-100 to SH-500 – chapter: „Lubri - exist with CO systems. Specially formulat- 2 cants" Immiscible oils can accumulate in the heat ed POEs are also suitable for use in widely exchangers and hinder the heat transfer so ramified pipe networks due to their particu - Further information see Fig. 37 Lubricants much that operation of the system is no larly good solubility/miscibility. However, for compressors, page 44 and explanations longer possible. these properties have a negative effect on for the particular refrigerants. viscosity and lubricity (tribology) and there - Therefore, new lubricants with appropriate fore require compressors with an extremely solubility/miscibility have been developed robust and wear-resistant drive gear. At for systems with HFC and HFO refriger- very high loads, e.g. heat pumps, PAG oils ants. These are oils based on polyol ester specially developed for CO applications (POE) and polyalkylene glycol (PAG). 2 ensure even more favorable lubrication They have similar or better lubricating pro - conditions. perties than previously customary oils, but Due to the thermodynamic properties of are more or less hygroscopic, depending ammonia (NH ) and the resulting plant on the refrigerant solubility. This requires 3 engineering, non-soluble/miscible oils are special care in manufacturing (including advantageous. These include for example drying), transport, storage and charging, so mineral oils and polyalphaolefins (PAO). that chemical reactions in the plant – such However, they require a special technique as hydrolysis in POE – are avoided. for oil separation and oil recirculation. For PAG-based oils are particularly critical con - further explanation as well as additional cerning water absorption. In addition, they information on applications when using par - have a relatively low dielectric strength and tially soluble PAG oils see chapter NH 3
40 Refrigerant properties
09.168 5 6 Refrigerant Composition Substitute / Application ODP GWP (100a) Safety Practical type (Formula) Alternative range group 4 limit 3 5 for [R11=1,0] [CO 2=1,0] [kg/m ] AR4 (AR5) HCFC-Refrigerants 5 1 R22 CHClF 2 R502 (R12 ) 0.055 1810 (1760) A1 0.3 R124 CHClFCF 0.022 609 (527) A1 0.11 3 R114 1 , R12B1 R142b CCIF 2CH 3 0.065 2310 (1980) A2 0.049 HFC Single-component Refrigerants 1 R134a CF 3CH 2F R12 (R22 ) 1430 (1300) A1 0.25 R152a CHF 2CH 3 mainly used as 124 (138) A2 0.027 R125 CF 3CHF 2 part components 3500 (3170) A1 0.39 R143a CF 3CH 3 for blends see 4470 (4800) A2L 0.048 R32 CH 2F2 R410A (R22) page 43 0 675 (677) A2L 0.061 1 R227ea CF 3-CHF-CF 3 R12B1, R114 3220 (3350) A1 0.63 R236fa CF 3-CH 2-CF 3 R114 9810 (8060) A1 0.59
R23 CHF 3 R13 (R503) 14800 (12400) A1 0.68 HFC Blends R404A R143a/125/134a 3922 (3940) A1 0.52 R507A R143a/125 3985 (3990) A1 0.53 R407A R32/125/134a 2107 (1920) A1 0.33 R407F R32/125/134a R22 (R502) 1825 (1670) A1 0.32 R407H R32/125/134A 1490 (1380) A1 0.38 R422A R125/134a/600a 3143 (2850) A1 0.29 R437A R125/134a/600/601 R12 (R500) 1805 (1640) A1 0.081
R407C R32/125/134a see 1774 (1620) A1 0.31 R417A R125/134a/600 page 43 0 2346 (2130) A1 0.15 R417B R125/134a/600 2920 (2740) A1 0.069 R422D R125/134a/600a R22 2729 (2470) A1 0.26 R427A R32/125/143a/134a 2138 (2020) A1 0.29 R438A R32/125/134a/600/601a 2264 (2060) A1 0.079 R410A R32/125 R22 1 (R13B1 2 ) 2088 (1920) A1 0.44
R508A R23/116 R503 13210 (11600) A1 0.23 R508B R23/116 13400 (11700) A1 0.25 HFOs and HFO/HFC Blends – further blends and data see pages 24 to 27
R1234yf CF 3CF=CH 2 4 (< 1) A2L 0.058 R1234ze(E) CF CH=CHF 7 (< 1) A2L 0,061 3 R134a R513A (XP10) R1234yf/134a see 631 (573) A1 0,35 0 R450A (N-13) R1234ze(E)/134a page 43 605 (547) A1 0,319 R448A (N-40) R32/125/1234yf/1234ze(E)/134a 1387 (1270) A1 0,388 R404A, R507A R449A (XP40) R32/125/1234yf/134a 1397 (1280) A1 0,357 Halogen free Refrigerants
R717 NH 3 R404A (R22) 0 B2L 0.00035 R723 NH 3/R-E170 R404A (R22) 1 B2 N/A R600a C H R134a 1 3 0.011 3 4 10 A3 R290 C3H8 R404A (R22) see 3 A3 0.008 R1270 C3H6 R404A (R22) page 44 0 2 A3 0.008
R170 C2H6 R23 6 A3 0.008
R744 CO 2 Diverse 1 A1 0.07
Tab. 6 Refrigerant properties (continued on Tab. 7)
These data are valid subject to reservations; they are based on information published by various refrigerant manufacturers. 1 Alternative refrigerant has larger deviation in 3 Also used as a component in R290/ 6 AR4: according to IPCC IV – time horizon 100 years – refrigerating capacity and pressure 600a-Blends (direct alternative to R12) also basis for EU F-Gas Regulation 517/2014 AR5: according to IPCC V – time horizon 100 years 2 Alternative refrigerant has larger deviation 4 Classification according to EN 378-1 below -60°C evaporating temperature and ASHRAE 34 N/A Data not yet published.
5 According to EN 378:2016
41 Refrigerant properties
09.18 Refrigerant Boiling Temperature Critical Cond. temp. Refr. Discharge Lubricant type temperature glide temperature at 26 bar capacity gas temp. (compressor) [°C] 1 [K] 2 [°C] 1 (abs) [°C] 1 [%] 3 [K] 3
HCFC-Refrigerants R22 -41 0 96 63 80 (L) 4 +35 4 R124 -11 0 122 105 5 5 R142b -10 0 137 110 HFC Single-component Refrigerants R134a -26 0 101 80 97 (M) -8 R152a -24 0 113 85 N/A N/A R125 -48 0 66 51 N/A N/A R143a -48 0 73 56 N/A N/A R32 -52 0 78 42 5 5 R227ea -16 0 102 96 5 5 R236fa -1 0 >120 117
R23 -82 0 26 1 5 5 HFC Blends R404A -47 0.7 73 55 105 (M) -34 R507A -47 0 71 54 107 (M) -34 R407A -46 6.6 83 56 98 (M) -19 R407F -46 6.4 83 57 104 (M) -11 R407H -45 7.0 86 55 99 (M) -8 R422A -49 2.5 72 56 100 (M) -39 R437A -33 3.6 95 75 108 (M) -7 R407C -44 7.4 87 58 100 (H) -8 R417A -39 5.6 87 68 97 (H) -25 see R417B -45 3.4 75 58 95 (M) -37 page 44 R422D -45 4.5 81 62 90 (M) -36 R427A -43 7.1 87 64 90 (M) -20 R438A -42 6.6 80 63 88 (M) -27 R410A -51 <0.2 72 43 140 (H) -4 R508A -86 0 13 -3 5 5 R508B -88 0 14 -3 HFO and HFO/HFC Blends – further blends and data see pages 24 to 27 R1234yf -30 0 95 82 98 (M) -14 R1234ze(E) -19 0 110 92 5 5 R513A (XP10) -29 0 97 78 102 (M) -7 R450A (N-13) -24 0.6 105 86 88 (M) -6 R448A (N-40) -46 6.2 83 58 96 (M) +12 R449A (XP40) -46 4.5 82 58 96 (M) +12 Halogen free Refrigerants R717 -33 0 133 60 100 (M) +60 R723 -37 0 131 58 105 (M) +35 R600a -12 0 135 114 N/A N/A R290 -42 0 97 70 89 (M) -25 R1270 -48 0 92 61 112 (M) -20
R170 -89 0 32 3 5 5 R744 -57 6 0 31 -11 5 5
Tab. 7 Refrigerant properties
1 Rounded values 3 Reference refrigerant for these values 4 Valid for single stage compressors is stated in Tab. 6 under the nomina- 2 Total glide from bubble to dew line – tion "Substitute for " (column 3) 5 Data on request (operating conditions based on 1 bar (abs.) pressure. Letter within brackets indicates must be given) Real glide dependent on operating operating conditions 6 Triple point at 5.27 bar conditions. H High temp (+5/50°C) Approx. values in evaporator: M Medium temp (-10/45°C) Stated performance data are average values H/M 70%; L 60% of total glide L Low temp (-35/40°C) based on calorimeter tests.
42 Application ranges
HFC refrigerants
5D
5$
5$G 5$ VWDJH
5$G 5)G 5+ G 5% 5$G 5' G 5$ G 5$
5& G 5$
5$ VWDJH
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Fig. 34 Application ranges for HFC refrigerants (ODP = O)
"Low GWP" refrigerants (HFO, HFO/HFC blends, R32)
5]H ( G 5%
R1234yf G 5$ G 5$
5$ G 5 $ G 5$& G G 5$& 5$ 5$ VWDJH
5
5% G 5% G 5 $
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Fig. 35 Application ranges for "Low GWP" refrigerants (HFO, HFO/HFC blends, R32)
43 Application ranges
Halogen free refrigerants
VWDJH 1+ 5
VWDJH
5 G 5 VWDJH
5D
5 &$6&$'(
&2 VWDJH%RRVWHU
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Fig. 36 Application ranges for halogen free refrigerants
Overview lubricants
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Fig. 37 Lubricants for compressors 44 Notes
45 Notes
46 Notes
47 BITZER Kühlmaschinenbau GmbH Eschenbrünnlestraße 15 // 71065 Sindelfingen // Germany Tel +49 (0)70 31 932-0 // Fax +49 (0)70 31 932-147 [email protected] // www.bitzer.de
Subject to change // 80050205 // 09.2018