Dynamic performance analysis of an R744/R290 cascade heat pump system for electric vehicles
A R744/R290 cascade heat pump system is proposed as an alternative to conventional single-stage systems using synthetic refrigerants. A dynamic simulation model based on finite-volume discretization was developed to analyze system behavior in heating mode under varying operating conditions. The effects of R744 refrigerant charge and compressor speed on system performance were investigated, and the results were compared with those of a single-stage R744 heat pump at the same heating capacity. The proposed cascade system exhibited a significantly higher coefficient of performance (COP), demonstrating its effectiveness in improving heating efficiency. The results confirm the feasibility of the R744/R290 cascade heat pump as a promising heating solution for electric vehicles (EVs).