Performance comparison of low GWP refrigerants for a miniature vapor compression system integrated with enhanced phase change material

An innovative personal cooling system (PCS) called the Roving Comforter (RoCo) uses an R134a-based vapor compression cycle (VCC) to provide cooling. To reduce environmental impact, it is necessary to evaluate RoCo performance with low GWP refrigerant alternatives. The condenser heat of the VCC is stored in a phase change material (PCM)-based latent thermal storage, while a serpentine micro-channel heat exchanger (MCHX) is used as the evaporator in the system. This article discusses the development of dynamic models for both PCM-condenser and MCHX-evaporator. A system model is then developed and validated for RoCo using Modelica. The validated model is used to compare the system performance for RoCo with R32, R1234yf, R1234ze(E) and R290 so that they provide the same amount of cooling. Compared to R134a, the change in COP is +8%, -12%, -3% and -5% with R32, R1234yf, R1234ze (E) and R290, respectively. The reduction in system charge with R32, R1234yf, R1234ze (E) and R290 is 1%, 11%, 30% and 52%, respectively. The compressor RPMs for R134a, R32, R1234yf, R1234ze (E) and R290 are 2100, 900, 2400, 2900 and 1700 respectively.