Subcooling, but Correctly!"

Technical Article

Influence of refrigerant subcooling on the refrigerating plant efficiency "Subcooling, but correctly!"

Main topics:

 The theoretical basics and the different concepts of subcooling

 Overall planning of the refrigerating plant

 Influence of subcooling on the component design and the interaction of refrigerating and control components

 Practical and economic evaluation of different possibilities for subcooling

 Energetic benefits and efficiency improvement

 Physical and refrigerating plant related limits of subcooling

Güntner AG & Co. KG Hans-Güntner-Straße 2 - 6 82256 Fürstenfeldbruck First published: 2010 GERMANY Güntner Technical Article: The influence of refrigerant subcooling on system efficiency "Subcooling, but correctly!"

This article shall give a comprehensive overview of the up to now published articles on the subject. The focus will be set on the following:

 the theoretic principles  the different concepts of subcooling  the overall planning of a refrigerating plant  the influence of subcooling on the component design  the interaction of the components and the control devices  the practical and economic evaluation of the different possibilities  the energetic benefit and consequently the efficiency enhancement  and the physical and plant-inherent technical boundaries of subcooling.

Figure 1: Subcooling in log p, h diagram (detail) After outlining the theoretic technical background, we will describe the state of the refrigerant on the high-pressure side of a classical refrigerating plant and the refrigerant's passage through the circuit’s components. The refrigerant flows from the condenser through the liquid receiver, the expansion valve and the evaporator and ends in the intake socket of the compressor.

For simplification, the refrigerant circuit of a single-phase cold-vapour compression installation will be described here. Detailed conditions are explained in the corresponding examples or in the comparative descriptions.

The commercial refrigerating plants that will be described in detail in this article are to be considered as unique specimen. This means that for an optimally operating refrigerating plant, the following three points have to form a symbiosis:

 planning skills and expertise (planning)  professional implementation in practice (implementation)  operators trained in the use of the system technology (operation)

Subcooling of liquid refrigerant in compression refrigeration system is a MUST for ensuring operational reliability!

How subcooling is achieved and for which refrigerant subcooling makes more or less sense will be explained in detail in the following.

The reasons for the above-mentioned requirements are known to specialists and are briefly summarized here:

 Main target: To ensure bubble-free refrigerant upstream of the expansion valve!

1/17 © Güntner AG & Co. KG Güntner Technical Article: The influence of refrigerant subcooling on system efficiency "Subcooling, but correctly!"

… this has to be guaranteed also after surmounting pressure drops in the liquid line caused by fittings or piping and by differences in geodetic height (in case of refrigerant's flow direction streaming horizontally upwards)!  To guarantee valve performance given in the technical documentation (for an expansion valve mostly at 4 K subcooling)  To prevent cavitation at the valve seat  To increase the utilisable evaporation enthalpy = performance increase of the entire refrigeration plant (see figure 2)  For the use of an IHE (internal heat exchanger) an additional compressor protection is given for special conditions

So this not about saying "YES" or "NO" to subcooling, but rather "WHERE does it come from?" and "HOW MUCH?"

On the following pages, you will be informed about what is possible in practice without generating high additional costs for the specific refrigeration installation with the corresponding boundary conditions and if this will make sense.

∆ Q0 = m · ∆h

∆ Q0 = increase of refrigerating capacity [kW], m = refrigerant mass flow [kg/s], ∆h = enthalpy increase caused by subcooling [kJ/kg]

Figure 2: Enthalpy increase caused by subcooling

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Possible types of subcooling

- Uncontrolled, without additional heat exchanger -

…in an air-cooled condenser without further components for subcooling 1 Advantages: - No additional costs - No additional components necessary

Disadvantages: - Achievable subcooling up to 1 K with standard condensers - No control of subcooling degree possible - Thermodynamically inefficient, because the heat transfer is bad with equal routing of piping (low liquid velocity)

Figure 3: Creating subcooling in an air-cooled condenser without further components for subcooling

…in an air-cooled condenser with rising pipe downstream of the condenser 2 Advantages: - Higher subcooling values can be achieved than in type 1 - No additional costs - No additional components necessary

Disadvantages: - No control of subcooling degree possible - Pressure drop depends on the geodetic height and thus the energy efficiency decreases - Thermodynamically inefficient, because the heat transfer is bad with equal routing of piping (low liquid velocity) - No certainty concerning the degree of subcooling - Reduction of utilisable condenser surface - Rising pipe leads to additional pressure drops (see table 3)

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Figure 4: Creating subcooling in an air-cooled condenser with rising pipe downstream of the condenser

…in an air-cooled condenser by refrigerant accumulation, e.g. with accumulation regulator for winter conditions

3 Advantages: - Higher subcooling values can be achieved than in type 1 - No additional costs - No additional components necessary

Disadvantages:

- No control of subcooling degree possible - Pressure drop caused by components and thus decrease of energy efficiency - Thermodynamically inefficient, because the heat transfer is bad with equal routing of piping (low liquid velocity) - No certainty concerning the degree of subcooling - Reduction of utilisable condenser surface

Figure 5: Creating subcooling in an air-cooled condenser by refrigerant accumulation, e.g. with accumulation regulator for winter conditions (secondary effect)

…in a water-cooled condenser 4 Advantages: - Hardly any extra costs - Utilization as heat recovery - Almost identical subcooling degrees at constant water temperatures

Disadvantages: - Mostly higher operating costs - Cooling water with suitable temperature has to be available

Figure 6: Creating subcooling in a water-cooled condenser

4/17 © Güntner AG & Co. KG Güntner Technical Article: The influence of refrigerant subcooling on system efficiency "Subcooling, but correctly!"

…in (vertical) receiver

5 Advantages: - No additional costs

Disadvantages: - No control of subcooling degree possible - The degree of subcooling largely depends on the ambient temperature - Subcooling can mostly only be achieved with vertical receivers with higher liquid seal (more refrigerant = inferior TEWI value!)

Figure 7: Creating subcooling in a vertical receiver

…in the liquid line and/or the tube fittings

6 Advantages: - No additional costs - Increase of subcooling with horizontal or falling piping (trefrigerant > tamb)

Disadvantages: - No control of degree of subcooling possible - Subcooling already must have taken place before the first pressure drop in the liquid line – otherwise so-called flash gas and possibly subsequently following condensation can form in the line!

Figure 8: Creating subcooling in the liquid line and pipe fittings

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- Uncontrolled, with additional heat exchanger -

…in an air-cooled condenser with separate subcooler coil (sequence of components: condenser->receiver->subcooler coil of condenser)

7 Advantages: - Higher subcooling values can be achieved than in type 1 - ∆t = tc – tL1 e.g. ∆t = 12 K -> ∆tu = 10 K - Subcooling values up to approx. 10 K can be achieved

Disadvantages: - Increased installation effort - Higher costs for condenser caused by second circuit - At low ambient temperatures, strong, not intended subcooling can occur (especially with horizontal condensers caused by thermal), this can be annihilated by leading the tubes through warm rooms (possibly formation of condensate - > provide insulation!)

Figure 9: Creating subcooling in an air-cooled condenser with separate subcooling coil

… in an internal heat exchanger, short: IHE Advantages: 8 - The IHE combines subcooling of the refrigerant and additional superheating of suction gas - Low additional costs - Additional protection for compressor Disadvantages: - No control of degree of subcooling possible - Uncertainty concerning the degree of subcooling, but the degree can be calculated for a specific operating point - Slightly higher effort for installation - Not suitable for refrigerants with an isentropic exponent high above 1 (e.g. R717) - For these refrigerants, the risk of oil coking is given at high superheating - Additional pressure drop especially significant with low temperature plants on suction side

Figure 10: Creating subcooling in the internal heat exchanger (IHE)

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- Controlled-

9 … in separate air-cooled subcooler

Advantages: - Targeted subcooling control is possible in the defined boundaries - Relatively independent of ambient temperatures - Almost constant operating conditions are created for the components in the liquid line - Subcooling values of up to approx. 10 K can be achieved

Disadvantages: - Additional costs for components and controller - Limit at approx. 2 K above ambient temperature

Figure 11: Creating subcooling in a separate air-cooled subcooler

… in separate water-cooled condenser 10 Advantages: - Targeted subcooling control is possible in the defined boundaries - Depends only of cold water state - Ambient temperature has almost no influence on subcooling - If required: additional utilisation for heat recovery

Disadvantages: - Sufficient amount of industrial water has to be available at required temperature - Additional heat exchanger and/or pipe routing

Figure 12: Creating subcooling a separate water-cooled condenser

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Subcooling and the optimal refrigerant selection:

Figure 13: Comparison: Influence of subcooling with different refrigerants

Refrigerant Isentropic Evaporation Compressor Suitability for subcooling exponent enthalpy discharge temperature see type 7 see type 8 K* R* / kJ/kg t0** / °C

R404A / R507 1.02 168.3 ≈ 70 ++ ++ R134a 1.06 198.8 ≈ 77 + – R407C 1.09 214.0 ≈ 85 + – R410A 1.10 222.5 ≈ 90 + – R22 1.14 202.2 ≈100 + – R290 (Propane) 1.07 374.5 ≈ 75 + –

R717 (NH3) 1.29 1262.2 ≈165 - –

R723 (NH3/DME) … 913.4 ≈140 + –

* at t = 0 °C ** at t0 / tC / t0h = -10 / +40 / +5 ++ well suited Data acc. to Solvay Fluor GmbH Open piston compressor + less well suited Compressor head uncooled – not suitable (see figure 13) Table 1: Comparison of refrigerants with their thermophysical properties

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Subcooling and air-cooled condensers

Thesis:

“In air-cooled condensers, a sufficient degree of subcooling can be achieved.”

This is only correct to a certain extent. In the specialist literature, the three phases of energy transport in the condenser are described absolutely correctly.

1. Dissipation of hot gas heat 2. Condensation of refrigerant 3. Subcooling of liquid refrigerant

Figure 14: Representation of the three phases of a condenser in a log p, h diagram

The degree of final subcooling is, however, relatively low for a standard condenser. As widely known, for subcooling the refrigerant has to be in a completely liquid state without gas cushion. If the refrigerant does not accumulate at the condenser outlet (e.g. back pressure controller, etc.), the degree of subcooling is quite low. In practice, less than approx. 1 K is achieved. A larger, maybe even over-dimensioned condenser does not necessarily lead to a higher degree of subcooling, it rather reduces the condensation pressure; this is one of the most effective solutions for energy reduction, but is not directly linked to subcooling.

The main task of a condenser is to condense the refrigerant. For this purpose, at first the superheat has to be dissipated.

This area represents, depending on the condensation temperature and the design, approx. 5 % (R134a, tc=25 °C) to

approx.15 % (R404a, tc=50 °C), with ammonia even 20 % of the available heat exchanger surface.

The remaining surface is mainly used for condensation, this surface changes, but contra-directionally, depending on the

condensation temperature. Thus approx. 93 % (R134a, tc=25 °C) to 82 % (R404a, tc=50 °C) are used for condensation.

The effective subcooling ratio in the condenser is thus quite low and provides the remaining percentage to cover 100 %.

This represents only 1.5 % (R134a, tc = 25 °C) to approx. 3.5 % (R404a, tc = 50 °C). With ammonia the percentage is significantly below 1 %!

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The diagram shows this correlation in the example of R404A/R507 and R134a:

Figure 15: Percentage of superheating energy to condensation heat

Figure 16: Heat ratio distribution in an air-cooled condenser (Refrigerant: R404A at tc ~ 40 °C)

With a standard design of an air-cooled condenser and an additional air-cooled subcooler maximum subcooling values of

approx. 10 K can be achieved, if one emanates from a temperature difference ∆t=tc-tle of max. 12 K.

Additionally the thermodynamic aspect plays a role, i.e. the heat transfer values, at equal routing of pipes, in the liquid phase in the condenser diminish significantly. The reasons for this are among others the low flow velocity and the lower turbulences (laminar flow) than during condensation. Thus the heat transfer coefficient is not as good.

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Subcooling from the condenser to the refrigerant receiver outlet

Thesis: “Subcooling that is achieved with difficulty in the condenser can be completely annihilated by the gas cushion in the receiver!”

This is also theory! If this statement were correct, this would mean that many refrigeration installations would operate in practice very unsatisfactorily, i.e. with flash gas. But it is, however, correct that it is not possible to subcool a refrigerant in a closed container (e.g. a refrigerant bottle = static), except if it is filled to 100 %, a fact that shall only be considered theoretically here. Let us presume the following situation: A refrigerant that has just been subcooled by 1 K leaving the condenser. The passage in the condensate line is often difficult for the refrigerant. Due to too small tube cross sections and changes in the load characteristics of the plant (for a short time there is more refrigerant in the receiver than required by the cooling points) the refrigerant flow is disturbed by the gas flowing back to the condenser. In practice, this phenomenon can be seen in larger installations through the sight-glass in the receiver. The condenser pumps the refrigerant into the receiver. Now the slightly subcooled refrigerant has reached the receiver. The larger volume of the receiver leads to a minimum pressure drop, and the refrigerant, that is slightly colder than the gas in the receiver, now reaches the liquid surface of the receiver. During the refrigerant’s passage through the saturated refrigerant gas, a small portion condensates into the slightly subcooled liquid. During this passage, the achieved subcooling is almost reversed. An important factor is the construction type of the receiver (horizontal = large liquid surface, usually not the ideal design), (vertical = long passage to the liquid in part load operation, but also an advantage due to utilization of liquid column). This liquid column appeases turbulences in the refrigerant and leads to a pressure increase that converts to subcooling at constant temperature. On the surface, subcooling is definitively 0 K; in physical theory. But because we have a dynamic situation in a refrigeration installation (everything is in motion), a part of the already low subcooling can reach the lower part of the - optimally vertical - receiver without completely consuming the attained subcooling. Additionally the liquid seal in the receiver, low ambient temperatures provided, is further cooled down below the saturation temperature, so that the refrigerant can leave the receiver in a slightly subcooled state. This can be observed with well filled large receivers: The temperature in the lower part of the receiver is sensibly cooler (thermal layering). But one should not rely on this, because mostly first pressure drops occur in the lines downstream of the receiver; and this explains why many installations operate smoothly without separate subcooling downstream of the receiver.

Figure 17: Simplified diagram of thermodynamic processes in a refrigerant receiver

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For a smooth operation of the refrigeration installation, the correct integration of the receiver downstream of the condenser is important.

Subcooling from the receiver to the expansion valve

Thesis: "Subcooling caused by heat dissipation of the liquid into the ambience can eliminate the existing pressure drops in the liquid line and thus no flash gas can form!"

This is playing with your luck! In practice, many refrigeration installations are in operation, that only have this opportunity to create subcooling to avoid the formation of flash gas.

The ambient temperature around liquid lines is in general below the liquid temperature and thus influences the refrigerant subcooling positively.

Figure 18: Relation of pressure drops and subcooling on the refrigerant’s passage from the receiver outlet to the expansion valve

As the diagram shows, on its way from the receiver to the expansion valve, the refrigerant achieves a kind of balance that is formed between subcooling (i.e. heat dissipation into the ambience from the liquid line (see table 2) and its components) and the surmounting of existing pressure drops in piping, components and difference in geodetic height (see table 3).

Tube length

Outer diameter of tube 5 m 10 m 15 m 20 m

12 mm 0.4 K 0.8 K 1.2 K 1.5 K

16 mm 0.3 K 0.5 K 0.8 K 1.0 K

18 mm 0.2 K 0.4 K 0.7 K 0.9 K

22 mm 0.1 K 0.3 K 0.6 K 0.8 K

Table 2: Subcooling of refrigerant in liquid line at ∆t = 20 K difference to ambient temperature (no strong air flow, no tube insulation, no pressure drops, Cu tube, flow velocity approx. 0.7 m/s) (Source: Armacell Calculation Program)

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Length 10 m Falling pipe horizontal Rising pipe Difference in height -10 m -5 m +/- 0 m +5 m +10 m Subcooling gain (+) or loss (-) in K for +1.8 K +0.9 K -0.1 K -1.1 K -2.1 K R404A

R407C +2.1 K +1.0 K -0.1 K -1.2 K -2.3 K

R134a +4.3 K +2.2 K -0.2 K -2.5 K -5.2 K

R717 +1.5 K +0.8 K -0.2 K -0.7 K -1.5 K

Table 3: Pressure drop in liquid line caused by changes in height for a liquid line ø 15 mm at Qo= 10 kW refrigerating capacity (approximated values) (Source: DANVEN program)

Limits for pipe components

Extreme subcooling values combined with starting/stopping of an installation and one cooling point can lead to accelerated liquid with the known resulting problems. In these cases, by opening the magnetic valves (= temporary pressure drop) in the liquid line, no refrigerant gas cushion will slow down the liquid flow. The liquid is thus (not slowed down, because subcooled to such a large extent) accelerated and reaches the expansion valve where is it stopped abruptly. The liquid now contains kinetic energy that is perceivable as hydraulic shocks in the piping. Torn off piping or ripped refrigerant dryers can be mentioned as damages that occurred in the past. Pressure surge in liquid lines of over 75 bar (high frequency) have been measured.

Subcooling and the expansion valve

Thesis: "If the degree of subcooling rises, the valve capacity increases also!"

At constant boundary conditions such as load, superheating, evaporating temperature and pressure difference upstream of the valve a constant opening diameter or refrigerant mass flow through the valve is assumed. Due to subcooling, the inlet enthalpy and the overall evaporation enthalpy increase. As described in the formula: ∆Q0 = m × ∆h This leads to a refrigerating capacity increased by ∆Q0 at a constant opening diameter and constant valve opening compared to operation without subcooling.

At an increased subcooling degree, the specific volume decreases during expansion [m3/kg]. At a constant opening diameter of the valve, even a larger refrigerant mass flow, m [kg/s], would be achieved and thus the above-mentioned capacity would increase additionally!

Subcooling upstream of 4 K catalogue 0.1 K 10 K 15 K 20 K expansion valve data

Nominal refrigerating 10.0 kW 10.7 kW 11.7 kW 12.5 kW 13.2 kW capacity

Change in 93 % 100 % 109 % 116 % 123 % performance

Table 4: Change in performance of expansion valves caused by influence of subcooling -10 °C / +40 °C (Source: DANVEN program)

By approximation one can say that, per changed Kelvin, subcooling changes the performance of the expansion valve by approx. 1 %.

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Another important point concerning expansion valves is the state of too low subcooling. What are consequences?

As already explained, missing or too low degrees of subcooling downstream of the receiver (!) caused by existing pressure drops in the liquid line lead in the worst case to pre-evaporation (flash gas). These gas cushions have to pass the valve seat during operation of the refrigeration installation and have a much larger volume than the same mass in liquid state. Thus the really injected refrigerant amount is at first reduced. The sensing element at the evaporator outlet reacts to this (superheating increases). Higher superheating in the evaporator leads to a pressure increase in the sensing element. Consequently the valve will enlarge the opening diameter. If the state upstream of the valve changes (temporarily no gas cushion anymore), more refrigerant is injected in the evaporator (density change in liquid). This is also registered by the sensing element and leads to closing of the valve. Superheating can thus not be compensated steadily anymore and the system “evaporator - expansion valve” oscillates. These phenomena are often to be observed if the condenser fans are turned off completely (pressostatic step control).

Limits for the expansion valve

The described vapour content after and during expansion leads to speed reduction of refrigerant flow in the valve and is intended. The different expansion valve manufacturers give limit values of x > 20 % vapour content (x > 0.2). In this diagram, the subcooling limit existing for the expansion valve can be shown independently of the refrigerant used.

Figure 19: Diagram for determining the maximum possible subcooling for the expansion valve (vapour content in the valve at 20 %)

In theory, it is possible to create such high subcooling values with an external subcooler that the expansion in the expansion valve does not yet lead to the formation of evaporated refrigerant (still left of the boiling curve). This proceeding can, however, not be recommended. On the one hand, it could happen that the expanded refrigerant at first has to be heated to evaporation temperature before it can evaporate, and the heat transfer values are rather bad with a low vapour percentage. On the other hand, this could lead to subsequent damage in the valve caused by missing cushioning and thus to increased frictional wear of the valve. Furthermore, the liquid line has to be insulated against condensation water.

Cavitation at the valve seat caused by missing subcooling in the expansion valve

The gas cushion upstream of the expansion valve can, however, also lead to destruction of the valve seat. This is called cavitation and is known from ship propellers.

The gas cushion accumulating upstream of the expansion valve (flash gas) will implode if the pressure falls and occurs in the valve nozzle. This leads to ripping off of very small metal parts from the nozzle surface, and, in consequence, the valve can not close correctly anymore after longer operation. Thus it can happen that the compressor transports liquid refrigerant at small part loads!

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Subcooling and the evaporator

As described in the beginning, a performance increase by increasing the subcooling degree at the evaporator is not perceivable. On the contrary! The heat transfer of the refrigerant is relatively bad with very low vapour content after expansion without special measures. This effect is caused by the missing turbulences in the refrigerant. These turbulences increase with augmentation of the vapour content and consequently the heat transfer also increases.

Figure 20: Schematic diagram of heat transfer coefficient depending on the vapour content of the refrigerant

This diagram shows that with increasing vapour content during evaporation the heat transfer coefficient increases too.

Subcooling in liquid suction heat exchanger, short IHE

An effective use of an IHE is strongly influenced by the used refrigerant. Refrigerants with an isentropic exponent close to 1 are ideal for the use with IHE (see chart page 6).

In the table, you can see, for example, that the refrigerants R404a/R507 have very low isentropic exponents and that R717 (ammonia) has a considerably higher isentropic exponent.

When using an IHE several positive effects are combined. The liquid shall be subcooled - before the pressure drops have to be surmounted. This means that the optimal installation position for the IHE in the circuit is the position downstream of the refrigerant receiver. In the counter-flow (double tube principle) the suction gas absorbs heat from the liquid refrigerant and is additionally superheated. See diagram:

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Figure 10: Creating subcooling in the internal heat exchanger (IHE)

This additional superheating has, in simplified way a good and a bad side.

It is positive that the compressor can be protected additionally against not evaporated refrigerant. The refrigerant drops can reach the compressor by:

 not optimally operating injection valves,  sudden load variations,  wrong positioning of sensor (or loose-fitting sensors),  so-called "hunting" at part load of the expansion valves,  change in operation conditions after hot gas defrost …etc.

The not evaporated refrigerant would evaporate at the latest in the suction line, in the compressor casing, at the winding (suction gas cooled compressor) or in the suction chamber.

This would lead to capacity losses, to considerable strain on the windings, to increased oil foaming at start of operation, to oil dilution and to additional strain for the compressor up to so-called slugging.

The negative side is that such an IHE constitutes in any case an additional pressure drop (differently strong, depending on the construction type of the IHE). This is – especially for low temperature applications – a disadvantage in terms of energy efficiency. Uncontrolled additional superheating leads to – even though only low – volume increase of the suction gas, that at constant piston capacity and constant speed leads to a lower coefficient of performance. These alleged disadvantages can be considered as marginal compared to the advantages, so that an effective benefit is created. The efficiency depends strongly on the selected refrigerant. One can approximately emanate from a ratio of 1:2 (in K) for the additional subcooling (value 1) and the additional superheating (value 2) downstream of the IHE.

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Figure 21: Example of heat transport in an IHE; 1 K subcooling is equal to approx. 2 K superheating

The use of plate heat exchangers is also possible for this purpose, however, the plate heat exchanger has to be dimensioned very precisely. For supermarket applications, an installation position close to the cooling point is sometimes chosen. The aim is, in addition to the intended subcooling and the subsequent capacity augmentation, to decrease the inefficient heat introduction into the (insulated) suction line. The thus warmer suction line will then absorb less energy from the ambient air. For all applications, the corresponding superheating limits defined by the compressor manufacturer have to be observed (suction socket temperature)!

Summary

Subcooling of a refrigerant is, one the one hand, necessary in technical terms, to ensure secure operation of the refrigeration installation. On the other hand, subcooling can improve to a certain extent the overall efficiency of the refrigerating machine.

Subcooling can be achieved in different ways. Generally speaking, refrigerant subcooling is only effective if it is achieved downstream of the receiver.

The highest increase in energy efficiency can be achieved with refrigerant subcooling by using the refrigerants R404A and R507A, as shown in figure 13.

Besides increasing the energy efficiency, refrigerant subcooling is a necessary condition for a reliable plant operation. Fittings, filters, sight glasses and control devices as well as higher positioned evaporators cause pressure drops in the liquid line that can lead to flash gas.

In general, refrigerant subcooling occurs in the liquid line, because there the ambient temperature is lower. The positioning of the liquid line can increase the effect of subcooling considerably (falling or horizontal piping), but rising pipes can also decrease this effect. During planning, the positioning of the liquid line plays an important role.

With a plant design with integrated subcooler in the condenser, the degree of refrigerant subcooling cannot be controlled. Consequently, a plant design with separate subcooler downstream of the receiver should be preferred. The fan of the separate subcooler can be controlled continuously without any problem. Due to the innovative condenser series GVX based on microchannel technology and developed by Güntner AG & Co. KG, condensers with separate subcooler can be provided – with the corresponding control system.

For further information relating to the new condenser series GVX, please consult our Info Brochure GVX.

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