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Effect of Insulations on Cop in Vapor Compression Refrigeration System

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Effect of Insulations on Cop in Vapor Compression Refrigeration System International Journal of Mechanical Engineering and Technology (IJMET) Volume 10, Issue 01, January 2019, pp. 1201-1208, Article ID: IJMET_10_01_122 Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType= 01 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 © IAEME Publication Scopus Indexed EFFECT OF INSULATIONS ON COP IN VAPOR COMPRESSION REFRIGERATION SYSTEM Anusha Peyyala Assistant Professor P V P Siddhartha Institute of Technology, Research Scholar, Acharya Nagarjuna University, India. Dr N V V S Sudheer Associate Professor, R V R & J C College of Engineering, Guntur India ABSTRACT In this project, experimentation is done on Vapour Compression Refrigeration System [VCRS] as the COP is high for this system and it is the present trend of the HVAC in the domestic industry. This study presents investigation of best suited refrigerant and insulation combination for gas pipeline and liquid pipeline of a split air conditioning system. Analysis are performed for R22-Chlorodiflouromethane, a HydroChloroFlouro Carbon refrigerant, which has been using in the present world that cause both global warming and ozone layer depletion and R410a, mixture of di- flouromethane and pentaflouroethane, a Hydroflouro carbon refrigerant, which is future of HVAC which reduces the effect of ozone layer depletion [ODP] and Global Warming Potential [GWP].For these two refrigerants, we had found out the best insulation suitable as insulation also affects the COP of air conditioner, which has been observed from the literature. Minimizing the temperature of refrigerant in suction line helps condensing unit work more effectively intern the system performance increases. This reduces the overall power required for working of air conditioner, thereby reducing the maintenance cost of system. Also, it helps the manufacturer to provide best type of insulation for the system at reduced cost thereby reducing overall cost of VCRS.To perform the experimental comparison, 16 tests were carried out for 5 times with each refrigerant Insulation combination. From analysis it is observed that, COPA for NRF+AF gives highest value for R22 and R410awhen compared to various insulation materials. Power required for VCRS is greater while using R410a than R22. So In t his work the m ain energy parameters s uch as COP and work required for compressor are analysed and discussed. Key w ords: G as P ipeline Insulation; L iquid pi peline I nsulation; R 22; R 410a; ODP; GWP; VCRS Cite this Article: Anusha Peyyala and Dr N V V S Sudheer, Effect of Insulations on Cop in Vapor Compression Refrigeration System, International Journal of Mechanical Engineering and Technology, 10(01), 2019, pp.1201– 1208 http://iaeme.com/Home/issue/IJMET?Volume=10&Issue=1 http://iaeme.com/Home/journal/IJMET 1201 [email protected] Anusha Peyyala and Dr N V V S Sudheer 1. INTRODUCTION As we all know that Refrigeration is the science of producing and maintaining temperatures below that of the surrounding atmosphere. This means removing of heat from a substance to be cooled. Heat always passes downhill, from a warm body to a cooler one, until both bodies are at same temperature. In simple, refrigeration is cooling or removal of heat from a system. Ahmet Z sahin et al [1], explained about Optimum insulation thickness of a circular duct subjected to external radioactive heat transfer and is studied for a given amount of insulation material. They also explained about an analytical solution which is obtained for the insulation thickness variation over a pipe to maintain a uniform outer surface temperature. A high temperature fluid is considered to be flowing through the pipe. The amount of the insulation material is assumed to be limited. Heat transfer from the outer surface of the pipe is through convection and radiation. The solution of the insulation thickness is found to be independent from the outer surface convective and radiative heat transfer coefficients. Alireza Bahadori et al [2], explained about selection and determination of optimum thickness of i nsulation w hich is of pr ime i nterest f or m any e ngineering applications. I n this study, a simple method is developed to estimate the thickness of thermal insulation required to arrive at a desired heat flow or surface temperature for flat surfaces, ducts and pipes. Abdullah Yildiz et al [3], in their study explained the investigation into optimum insulation thickness of installed inside building pipe network of VRF (variable r efrigerant f low) systems. Optimum insulation thickness, energy savings over a lifetime of 10 years and payback periods are determined for high pressure gas pipelines, low pressure gas pipelines and low-pressure liquid pipelines under the heating-only and cooling-only modes of the three-pipe VRF system using R-410A as refrigerant. Mustafa Ali Ersoz et al [4], performed investigations on optimum insulation thickness, cost savings and payback periods for gas pipeline and liquid pipeline under the heating operation of 1500 hours and cooling operation of 1500 hours of a split air conditioning system that used flexible insulation foam as insulation material. Analyses are performed for four different refrigerants indicated as R-22, R-134a, R-407C and R-410A. Man- Hoe Kim et ala [5], did an experimental investigation for evaporating heat transfer in 9.52 mm O.D. horizontal copper tubes was conducted. The refrigerants tested were R22 and the near-azeotropic mixture, R410A. J H Wu et al [6], in their work, an original R22 wall room air conditioner with a cooling capacity of 2.4 kW and energy efficiency ratio (EER) of 3.2 is retro fitted with a compressor of a 20% larger displacement to charge R290 and R1270 for performance experiments. A.Cavallini et al [7], in their work presented reports on experimental heat transfer coefficients and pressure drops measured during condensation inside a smooth tube when operating with pure HFC refrigerants (R134a, R125, R236a, R32) and the nearly azeotropic HFC refrigerant blend R410A. M.Goto et al [8], in their work heat transfer coefficients were measured for the condensation of R410A and R22 inside internally grooved horizontal tubes. R L Llopis et al [9] presented a theoretical and experimental analysis of the performance of R22, R422A, R417B, R404A in a two stage VCRS. Their results showed that when usi ng a ny of t he s ubstitute f luids t here i s a n i mportant i ncremental di fference i n the refrigerant mass flow rate through the palnt and sometimes necessary to readjust the expansion valve of the system. 2. EXPERIMENTATION Experimentation is done on SAC system of 5.25 KW designed for R22 & R410a were selected for performance evaluation. It was tested as per the Indian Standard 1391 (1992) Part I, for unitary air conditioners. The performance of SAC with R410a is compared with the baseline performance. A ll m aterials t hat a re di scussed i n t he l iterature a re not f easible f or split air conditioner. Because, few materials are higher in cost, few are obsolete, and few cannot be used http://iaeme.com/Home/journal/IJMET 1202 [email protected] Effect of Insulations on Cop in Vapor Compression Refrigeration System for split air conditioner. For these reasons, we had chosen few insulation materials and few combinations of m aterials.Materials a nd their c ombinations s elected f or experimentation are EPF, NRF, PFS, NYR NRF+AF,NRF+NYR , PFS+NYR .Along with these materials, we also conducted experimentation for Bare pipe (BP) (no insulation) so that variation in performance can be observed with respect to it. Experimentation has been done, using these materials as insulation in a SAC system using R22 and R410a as refrigerants. During this experimentation, temperatures a t various points a re t aken by using di gital thermometer until s teady s tate is achieved. Values have been taken for R22 at Suction pressure = 4.48 bar Discharge pressure = 17.23 bar. Values have been taken for R410a at Suction pressure = 7.58 bar Discharge pressure = 31.71 bar. Temperature values are taken at various points TR, TE−LRI, TE−ttRO, TC−ttRI, TC−ttRO, TCO−ttRI, TCO−LRO, TEV −LRI, TEV −LRO Formulae Used, (1) (2) (3) (4) in Kw (5) All the thermo physical properties were considered from REFPROP 9 [10] for the considered refrigerants. The above equations 1 to 5 are used for calculating different values. The data were recorded for 5 times at an interval of 1 hour with different considered refrigerant insulation combinations to obtain an average value after confirming the steady running state of an air conditioner. 3. RESULTS AND DISCUSSIONS By O bserving t he below F ig.1, i t can underst ood t hat NRF+AF i nsulation is showing the maximum COP value and Minimum Wc value when the considered VCR system is working with R22 as the working Substance. R22 Values 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 BP EPF NRF PFS PFS+NYR NYR NRF+NYR NRF+AF COPA WC (KW) Figure. 1: Variation of R22 refrigerant Properties with the Type of Insulation. http://iaeme.com/Home/journal/IJMET 1203 [email protected] Anusha Peyyala and Dr N V V S Sudheer R410a Values 4.00 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 BP EPF NRF PFS PFS+NYR NYR NRF+NYR NRF+AF COPA WC (KW) Figure. 2: Variation of R410a refrigerant Properties with the Type of Insulation By Observing the above Fig.2, it can understood that NRF+AF insulation is showing the maximum COP value and Minimum Wc value when the considered VCR system is working with R 410a a s t he w orking S ubstance.
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