Energy Performance Assessment of R134a/LPG Blend as Replacement of R134a in Vapor Compression Refrigeration System
In this study, a theoreticalperformance analysis of vapor compression refrigeration system using R134a and R134a/LPG blends (in the ratio of 18:82,28:72, 38:62,48:52 by weight) as a refrigerantwas carried out using the coefficient of performance (COP), as the main performance parameter. The theoretical analysis of refrigerants has been executed by varying the evaporator temperatures from -30°C to 0°C and at three different condensation temperatures, particularly 40°C, 50°C and 60°C.The theoretical results obtained with R134a are taken as the baseline for comparison. The optimum composition of R134a/LPG blend was selected based on the theoretical performance results, such that system yield highest coefficient of performance over wide range operating conditions.In addition to this, other performance parameters like the mass flow rate, the compressor power consumption,the compressor discharge temperature and total equivalent global warming impact (TEGWI) of R134a/LPG blend (optimum composition) are compared with R134a.The results revealed that vapor pressure characteristics of R134/LPG (28:72)blend was found to be closer to R134a over a broad range of evaporator temperatures so without any modifications R134a compressor can be used for R134/LPG (28:72)blend. The COP of R134/LPG (28:72) blend was also found to be highest and it is higher than that of R134a by about 15.6–27.8%. The compressor powerrequirement and TEGWI of R134/LPG (28:72) blend were found to be lower than that of R134a by about 24.5–49.6% and 36.34% lower respectively at all operating temperatures. The compressor discharge temperature of R134a/LPG (28:72) blendis also foundlower than that of R134a over a wide range of evaporator temperature due to which compressor better life may be expected.The outcomes confirmed that R134a/LPG (28:72) blend is an energy efficient and environment-friendly substitutefor R134a in VCRS.
Keywords - R134a, R134a/LPG, Domestic refrigerator, volumetric cooling capacity, Total equivalent global warming impact.