Abstract
Problem statement: There are two types of global warming contribution s through refrigeration and air conditioning systems. The fir st one is the Direct Global Warming Potential (DGWP) due to the emission of refrigerants and thei r interaction with heat radiation. The second one i s the Indirect Global Warming Potential (IDGWP) due to the emission of Carbon Dioxide (CO 2) by consuming the energy that is generated through the combustion of fossil fuels. Most of refrigerants us ed in vapor Compression system were Chlorofluorocarbon (CFCs) and Hydro Chlorofluorocarbon (HCFCs) which contains chlorine and if any leakage in the s ystem, these gases will go up and reach stratospher e. 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 p olar ice caps and drought. Hence, it is necessary t o minimize the Global warming and Ozone depletion. The refrigerant R22 widely used in the air- conditioners is a major Contributor of Chlorofluoro carbons (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, w as tested for its performance with the selected eco friendly refrigerants R407C and R290 as an alterna tive 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 di splace the R22 and other types of expansion devices .
Highlights
Worldwide attempts are being made to phase out the production and consumption of Hydro ChloroFluorocarbon (HCFCs) and Chlorofluorocarbon CFCs), as these chemicals are responsible for depletion of stratospheric ozone layer
EEVs in air conditioners enables an appreciable energy saving with respect to the same installations equipped with traditional Thermostatic Expansion Valves (TEVs) was proved and this is due to the fact that EEVs allow a lower condensation pressure in systems equipped with air cooled condensers, which is adjusted to variations in outside air temperature (Lazzarin and Noro, 2008)
The mass flow rate of R22, R407C and R290 are increasing with the increase in EEV opening from15% (416 steps) to 20% (546 steps) opening and decreasing for the EEV opening of 25% (676 steps)
Summary
Worldwide attempts are being made to phase out the production and consumption of Hydro ChloroFluorocarbon (HCFCs) and Chlorofluorocarbon CFCs), as these chemicals are responsible for depletion of stratospheric ozone layer. With the above objectives in mind a detailed through a micro processor based control (electronic literature survey has been carried out and the possibility of adopting Electronic Expansion Valve (EEV) instead of capillary tube as an expansion device in lower capacity window air conditioners with eco friendly refrigerant R407C and R 290 as alternative refrigerant to R22 to improve the energy efficiency of the system is tested. Air-conditioning and Refrigeration Institute ARI, 1997, Arlington, VA, USA, in the year 1997 suggested that the refrigerants R407C and R290 are the potential replacements for HCFC-22 Among these two, R290 is a byproduct of natural gas that can serve as a replacement of CFCs and HCFCs. Its liquid pressure is higher than that of HCFC22 and the performance increases significantly. EEVs in air conditioners enables an appreciable energy saving with respect to the same installations equipped with traditional Thermostatic Expansion Valves (TEVs) was proved and this is due to the fact that EEVs allow a lower condensation pressure in systems equipped with air cooled condensers, which is adjusted to variations in outside air temperature (Lazzarin and Noro, 2008). Shanwei et al (2005) have developed a correlation on the basis of the experimental data of EEV to predict the mass flow rate for R22 and its alternatives, R407C and R410A
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