Experimental study of enhanced PCM exchangers applied in a thermal energy storage system for personal cooling

Abstract

The personal cooling device investigated is based on the vapor compression cycle and has a condenser integrated with the phase change material (PCM), in order to increase building thermostat setpoint and provide high-level human comfort. Since the PCM thermal conductivity is low, the objective of this study is to investigate five PCM exchanger designs with different heat transfer enhancement methods including increasing heat transfer area, embedding conductive structures, and using uniform refrigerant distribution among condenser branches. In the proposed system, PCM exchanger capacity was approximately constant, which is different from most of the previous works. Various refrigerant heat transfer coefficient along condenser length, refrigerant flow maldistribution and PCM natural convection could result in the uneven PCM melting, leading to higher condensing temperature. The graphite matrix exchanger with uniform refrigerant distribution performs the best with 5.5 times higher overall heat transfer coefficient and 49% increased coefficient of performance.