The novel use of phase change materials in refrigeration plant. Part 3: PCM for control and energy savings

Phase change materials (PCMs) have been recognized as energy storage tanks since the 1980s. The ‘tank’ has been introduced into the refrigeration system to enable its capacitance to take account of fluctuations in the daily cooling load. However, this part of the paper will present a novel control purpose of using PCM in refrigeration systems. The novel application of PCMs in refrigeration systems at different positions in the refrigeration cycle circuit with a shell and tube structure has been investigated extensively by the novel mathematical model presented in part 2 of the paper. The results show that for energy savings, PCMs at different positions give coefficient of performances (COPs) up to 8% through lowering the sub-cooling. PCMs also improve the system COPs up to 4% and 7% for the thermostatic expansion valve (TEV) and orifice systems, respectively, by minimizing the superheat. Further benefits such as system stabilization were also observed in this investigation.