Problem statement: There are two types of global warming contributions through refrigeration and air conditioning systems. The first one is the Direct Global Warming Potential (DGWP) due to the emission of refrigerants and their interaction with heat radiation. The second one is the Indirect Global Warming Potential (IDGWP) due to the emission of Carbon Dioxide (CO₂) by consuming the energy that is generated through the combustion of fossil fuels. Most of refrigerants used in vapor Compression system were Chlorofluorocarbon (CFCs) and Hydro Chlorofluorocarbon (HCFCs) which contains chlorine and if any leakage in the system, these gases will go up and reach stratosphere. The chlorine atoms in the gases will act as a catalyst to destroy ozone layer and cause ozone depletion which causes health hazards, global warming, melting of polar ice caps and drought. Hence, it is necessary to minimize the Global warming and Ozone depletion. The refrigerant R22 widely used in the air-conditioners is a major Contributor of Chlorofluorocarbons (CFCs) which cause irreparable loss to the ozone layer and has to be replaced. Approach: To conserve the energy and minimize the global warming, the systems should be designed as more energy efficient and also to minimize Ozone depletion, the eco friendly refrigerants are to be selected and tested as alternative refrigerants to R22. Hence, a window air conditioner of 3.5 kW capacity fitted with Electronic Expansion Valve (EEV)) instead of capillary tube as an expansion device, was tested for its performance with the selected eco friendly refrigerants R407C and R290 as an alternative to R22 under fixed indoor and outdoor chamber temperatures in the experimental set up and varying the EEV opening. Results: It has been observed from the experimental studies that when the smaller capacity R22 window air conditioner with EEV is retrofitted with R407C and R290, compared to the performance given by R22, the Coefficient Of Performance (COP) given by R407C and R290 is improved in the range of 4.8-7.1 and 8.0-12.3% respectively and the Energy Efficiency Ratio (EER) is increased by 4.2-6.9% for R407C and 6.4-10.8% for R290. Conclusion: The performance of Electronic Expansion Valve (EEV) with eco friendly refrigerant R290 in the given air conditioner shows a positive effect in terms of COP and energy efficiency and enables the industry to favorably displace the R22 and other types of expansion devices

The objective of this study is to investigate the influence of Electronic Expansion Valve (EEV) on the performance of window air conditioner retrofitted with R407C and R290. The window air conditioner applying the EEV is tested by varying the compressor inlet superheat from 0?C to 20?C. The eco friendly refrigerant R407C has the similar thermodynamic properties as those of R22 with an exception of temperature gliding during the phase change at constant pressure. R290 is a hydrocarbon which also exhibits properties very close to R22 which enables this to be used as a potential alternative to R22.The EEV affords a precise, fast, and stable flow control for a wide range of flow rate due to its use of an electronic control method based on an advanced control algorithm.EEV controls the refrigerant flow through the evaporator by means monitoring pressure and temperature at the outlet of the evaporator and hence it shows good overall performances comparing the capillary tube system. The Coefficient of Performance (COP) of R290 is the maximum among the three refrigerants tested and also for all the three refrigerants, COP is low at higher degree of superheat.

a De part ment of Me chan i cal En gi neer ing, Gov ern ment Col lege of En gi neer ing, Sa lem, In dia b KSR Col lege of Tech nol ogy, Thiruchengode, In dia Orig i nal sci en tific pa per UDC: 697.97:66.045.1The per for mance of one ton of re frig er a tion win dow air con di tioner work ing with R-22 and retro fit ted with eco friendly al ter na tive re frig er ant R-407C is ex per i mentally in ves ti gated An in ter nal heat exchanger is also added to the same air con ditioner to pro vide liq uid over feed ing op er a tion. When retro fit ting the R-22 sys tem with R-407C, the co ef fi cient of per for mance is found to drop by 7.28%, how ever when in ter nal heat exchanger is in cluded the per for mance is im proved. It is observed that the in clu sion of in ter nal heat exchanger has in creased the co ef fi cient of per for mance by 5.86% when run ning on R-22 and 6.18% when run ning on R-407C, un der the given con di tions In tro duc tionGlobal con cern over ozone de ple tion and global warm ing have re sulted Mon treal and Kyota pro to cols, re spec tively, ac cord ing to which , the use and pro duc tion of chloro fluorocarbons (CFC) and hy dro chloro fluoro carbons (HCFC) have to be ceased in all over the world by the year 2010 and 2030, re spec tively. The en vi ron men tal prob lems caused by CFC and HCFC have been en cour ag ing en gi neers and re search ers to de velop new al ter na tive re frig er ants with highly ef fi cient ma chines which have the ca pa bil ity to re duce en ergy con sump tion [1]. It has been re ported that R-407C is a close match to R-22 with re spect to en ergy ef fi ciency and other per for mance pa ram e ters such as com pres sor dis charge tem per a ture and pres sure [2,3]. R-407C is the blend of R-32, R-125, and R-134a that has prop er ties sim i lar to R-22 (tab. 1). New sys tems built with R-407C must have polyolester (POE) lu bri cants, and retro fit ted R-22 sys tems would need the re sid ual oil flushed with POE. Yang et al. [4] have used re frig er ant mix tures whose per for mance is close to that of R-22. Jabaraj et al. [5] have re ported that HCFC 407C/HC blends are su pe rior to R-22. The ex per i men tal in ves ti ga tion, on the per for mance of R-407C un -

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