Thermo-economic and environmental analysis of a Dish-Stirling/Stirling thermal solar refrigerator for cold production

The Stirling chiller presents multiple brilliant applications, especially with its low power consumption, rapid cooling, high reliability, lightweight, high efficiency; it is capable of running on solar energy. In this work, a Dish-Stirling/Stirling refrigerator system is studied to obtain cold. This system is more efficient than existing solar refrigeration systems, and environmentally friendly due to its non-toxic working fluid. Moreover, its Dish-Stirling solar collector is capable of operating in warmer regions compared to other solar collectors. The system consists of a solar collector to transform solar energy into heat, a Stirling engine to convert mechanical thermal energy, a gear system to couple the refrigerator and Stirling engine, and a refrigerator Stirling for cold production. The system is modeled on the basis of finite-time thermodynamics. Then the equations are solved analytically. The simulations are performed with MATLAB software. In addition, the thermal losses of the solar collector, Stirling engine and refrigerator are taken into account in this model. The equality of cycle time and power was considered constraints of the system. Besides, the effects of operational and design parameters on system performance are studied. The results show that the Dish-Stirling/Stirling refrigerator presents a low COP and high cooling capacity, unlike the photovoltaic/Stirling refrigerator. In addition, the optimal solar thermal COP is 33.3 % for the optimum absorber temperature of 800K. The maximum cooling rate is 1720W at Th′=268K. The optimum engine power is 4061.9W at Tl=300K, the ecological coefficient of performance is 47.31 at Tl′=255K, the optimal thermo-economic function is 0.157 at k=1. The COP0 of the Stirling refrigerator is 50.005 % at Th=500K. This system can be used to preserve medicines in pharmacies.