Energy-exergy-economic-environmental (4E) analysis and multi-objective optimization of a cascade refrigeration system

Abstract

The present work focusses on 4E analysis of a 50 kW cooling capacity cascade refrigeration cycle covering the aspects of energy, exergy, economic and environment analysis. The numerical investigation and the multi-objective optimization is carried out for the system using the refrigerant pair R170-R600a and R41-R600a. The refrigerant pair is selected based on the environmental implications in terms of GWP and ODP. Multi-objective optimization of the objective functions is carried out using a heat transfer search optimization algorithm to evaluate the optimal performance of the system. The effect of evaporator temperature, condenser temperature, LTC condenser temperature and LTC condenser temperature difference on the exergy efficiency and total cost of the system is studied. A set of multiple optimal solutions is presented using the Pareto optimal curve and TOPSIS criteria is employed to select the optimal operating condition. Compared to the refrigerant pair R170-R600a, the system with R41-R600a operates at better exergy efficiency and lower total cost. At the TOPSIS selected optimal condition, exergy efficiency and the total cost of the CRS is 63.5 % and 65,228 $/year for the refrigerant pair R41-R600a and 62.6 % and 67,690 $/year for R170-R600a, respectively. The distribution of variables shows that the effect of the evaporation temperature, condensation temperature and the LTC condenser temperature is profound in obtaining the optimal solution.