Experimental study of cold storage packed domestic refrigerator with solar powered variable speed compressor

Abstract

A domestic chest type freezer powered by photovoltaic solar panels studied experimentally. Phase change materials (PCM) were incorporated as thermal energy storage instead of traditional batteries for power backup freezer operation under absence/low solar irradiance levels. The test rig consists of three sided freezer divided into two insulated compartments each have its own PCM storage tank. A eutectic potassium chloride (19.4% with -10°C freezing temperature) and sodium chloride (8% with -5°C freezing temperature) aqueous solutions were used as thermal energy storage in each part of cabin. A comparison between different PCMs was made. The results showed a %54 reduction in compressor running time for the PCM packed evaporator. 4Kg of 8% NaCl solution at full load gave higher thermal mass. Also, freezer temperature maintained between -3.5 to -1 ºC for 46% of holdover periods without power supply. 8% NaCl solution performance was superior to 14% NaCl. As the mass of PCM increases the freezer performance improves as well. Finally, two compartments freezer showed that 2kg of 19.5% KCl has successfully kept load temperature at (2°C).