Enhancing energy and exergy performance of a cascaded refrigeration cycle: Optimization and comparative analysis

Abstract

This study delves into the realm of energy and exergy analysis, aiming to optimize the performance of a refrigeration cycle by utilizing cycle Coefficients of Performance (COPs). The conventional heat pump cycle is replaced by a cascaded cycle, and this novel configuration is scrutinized through the lenses of the first and second laws of thermodynamics. The analysis is conducted within the EES software environment, encompassing the components of the cycle governed by these laws. The refrigerant employed is R407C. Through comprehensive energy and exergy analyses, significant insights emerge. Assuming a consistent refrigeration capacity, the study unveils the potential for a remarkable 21% increase in the coefficient of performance and a substantial 32% enhancement in the efficiency of the second law of thermodynamics within the cycle. Subsequently, a deeper exploration ensues, involving the selection of cascaded cycle refrigerants—R290, R134a, and R500. The impact of pivotal parameters such as inlet pressure, outlet temperature difference of the intermediate heat exchanger, evaporator inlet temperature, and condenser outlet on cycle performance and efficiency is meticulously compared for each refrigerant. Of particular interest is refrigerant R500, which, under specific conditions, drives the cycle and system COPs up by 7% and 2%, respectively, relative to R407C. Furthermore, the study reaches the pinnacle of exergy efficiency. A staggering increase of up to 8% in cascaded cycle exergy efficiency and 3% in the overall R500 refrigerant system exergy efficiency is achieved under consistent temperatures. This multifaceted research demonstrates the potential for significant enhancements in the performance and efficiency of refrigeration cycles through judicious optimization and strategic selection of refrigerants.