The novel use of phase change materials in refrigeration plant. Part 1: Experimental investigation

Phase change materials (PCMs) have found considerable applications in large air conditioning schemes. PCMs were primarily used to introduce capacitance within a system, which enabled them to take into account the fluctuations in the daily cooling load. However, this technology has been developed recently and integrated into the refrigeration system directly to save energy and for better control. This has been achieved through lowering the temperature of the sub-cooled refrigerant and stabilizing the superheat. A prototype demonstrating this novel use of PCMs in refrigeration systems has been developed and tested. Results show that by lowering the temperature of the sub-cooled refrigerant, up to 8% energy savings can be achieved in the UK climate conditions. By using the PCM heat exchanger as a pre-condenser in a refrigeration system, the system’s COP can be improved by 6%. The benefit achieved by reducing the superheat is somewhat offset by its extra pressure drop, although simulation work has showed elsewhere [F. Wang, The passive use of phase change materials in refrigeration system, Ph.D. thesis, London South Bank University, 2003] that the COP can be improved by 4% using a low pressure drop PCM heat exchanger in any climate zone.