Modelling and performance analysis of directly coupled vapor compression solar refrigeration system

This paper proposes a method for the analysis and simulation of solar energy driven vapor compression refrigeration system with variable speed compressor under the real weather condition using the data sheets (of the PV panel and compressor) available from the manufacturers. The solar refrigeration system considered in this research study includes a non-tracking PV power source directly-coupled with a variable speed DC compressor. The operating point of the compressor of the considered solar refrigeration system is determined on the current versus voltage (I-V) plane, by intersecting the I-V curve of the PV panel with the I-V curve of the compressor. The operating speed of the compressor is determined to model the hourly variation of the performance of the refrigeration system. The analysis and simulation result show that the COP of the refrigeration cycle for the selected days is around 2.25 when the compressor runs at low speed, and the COP drops to its lowest value of 1.85 when the compressor operates at the highest speed. Furthermore, the simulation results indicated that an estimated radiation intensity 315 W/m² is required to be received on the tilted panel to run the considered compressor at its minimum rotational speed of 1800 rpm. To drive the compressor at its maximum rotational speed (4200 rpm), an estimated radiation intensity of 700 W/m² is required to fall on the PV panel. Finally, the proposed method can be used to estimate the performance of a directly coupled solar PV refrigeration system with variable speed compressor under specific weather condition.