Experimental study of a portable PV direct-driven variable-speed refrigerator

A portable PV direct-driven variable-speed refrigerator is proposed in this study. The compressor rotation speed of this system was controlled according to the solar irradiation allowing the utilisation efficiency of solar energy could be optimised and the frequently on-off of the compressor caused by the variation of solar irradiation could be avoided. The influence of the control strategy of the compressor speed, the ambient temperature and the internal fan were studied respectively. Compared to the constant-speed refrigerator, the variable-speed refrigerator was able to raise the daily average PV utilisation efficiency by 48.1%, raise the ice production by 99.6% and raise the final net refrigeration quantity by 22.8%. When ambient temperature rose from 20℃ to 30℃, the ice production reduced by 23.9% and the final net refrigeration quantity reduced by 10.5%. The application of the internal fan could shorten the time needed for cooling water to 5℃ by 39.3%.