Abstract: Vapor Compression Refrigeration (VCR) systems are commonly used for Air Conditioning (AC) purposes in residential, commercial, and industrial applications in both dry and wet climatic conditions. Most of these applications are achieved with the conventional single-stage Vapor Compression Refrigeration systems; however, the systems possess lower cooling capacity and coefficient of performance at low evaporator temperatures and higher-pressure ratios, and this situation worsens in the tropics. This study compares the performances of single and two-stage Vapor Compression Refrigeration systems using sustainable refrigerants in a climate region. Performance of single-stage and two-stage Vapor Compression Refrigeration (VCR) systems containing the new generation refrigerants of R-600a (isobutane), R-600 (n-butane), R-717 (ammonia), and R-290 (propane) was studied theoretically via performance simulation. Results were discussed, changing evaporator temperature, condenser temperature, degree of superheat, subcooling, and mass flow rate of refrigerant. Thermodynamic analysis of VCR systems, including all refrigerants, was conducted using the Engineering Equation Solver (EES) software. A comparative performance study was conducted between a two-stage vapor compression refrigeration (VCR) system and a corresponding single-stage vapor compression refrigeration system. The performance of the two-stage V.C.R. system is higher than that of the single-stage system and maximum at low evaporating temperature. Maximum COP of 7.636 was obtained with R-717 in a two-stage VCR system at evaporating temperature of 0 °C. Minimum COP of 0.948 was obtained with R-290 in a single-stage VCR system at a condensing temperature of 80 °C. The performance of the two-stage system is better, and R-717 is found to be the best refrigerant among the refrigerants studied in this research. The findings of this study will provide an experimental basis for future investigations of new systems and designs. This would enable design engineers to assess and determine improvements to air conditioning and refrigeration systems, and refrigerants appear to be economically worthwhile.

Keywords: Vapour compression refrigeration, Single-stage system, Two-stage system, Coefficient of performance, Eco-friendly refrigerants, Ammonia

Pages: 1-11

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