Two-evaporator refrigeration system integrated with expander-compressor booster

Abstract

Two-evaporator refrigeration systems are commonly used in many practical applications where two different temperatures are required. Improving the performance of these systems can contribute to energy efficiency. Expansion recovery has been extensively utilized in order to maintain higher performance and the most commonly used method is adopting an ejector instead of expansion valve. In this work, different from the previous studies, an expander-compressor booster is introduced to the system instead of an expansion device to improve coefficient of performance (COP) and second law efficiency of the two evaporator refrigeration system. Parametric studies are conducted for different mass flow rate ratios, condensing, evaporating, superheating temperatures on COP and relative increment in COP (COP*) values are plotted. An internal heat exchanger (IHX) is also added to evaluate whether it helps or worsens the system performance. Moreover, the impact of different refrigerants (R134a, R1234yf, R290, R717, R32 and R410A) on the results is discussed. The results for R1234yf showed that the expander-compressor booster increases the performance of the system and second law efficiency by 38% when mass flow rate ratios are identical. This increment can be increased at lower mass flow rate ratios. Addition of the IHX contributes the COP*. It has also been observed that the refrigerant type has a significant impact on the results.