Evaluation of energy-saving potential and cabin thermal comfort for automobile CO2 heat pump

Abstract

Currently, the heat pump air conditioning system is extensively used in Electric Vehicle (EV). However, most previous simulation studies focused on one-dimensional (1D) system performance rather than three-dimensional (3D) cabin thermal comfort. This study proposed a novel control strategy for the operation of a one- and three-dimensional coupling transcritical CO2 heat pump air conditioning system based on the weighted Predicted Mean Vote (PMV) model. The mathematical characterizations of the multiple thermodynamic systems were achieved by one-dimensional calculation and the cabin thermal environment was described by three-dimensional simulation. The weighted predicted mean vote value was calculated by real-time interactive three-dimensional cabin thermal environment parameters while providing control signals for the one-dimensional refrigeration system. The simulation comparison revealed the influence of the weighted Predicted Mean Vote control strategy on the system’s thermodynamic parameters and energy-saving potential. Results showed that the compressor power consumption of the Predicted Mean Vote control strategy was reduced by 9.1%-33.7%, compared with the method of presetting specific temperatures. The proposed one- and three-dimensional coupling method of cabin thermal management establishes the structured correlation between heat pump air conditioning system and cabin thermal environment. The weighted Predicted Mean Vote control strategy reduces the system power consumption within the thermal comfort range of the passengers, and it provides a novel idea for cabin thermal management during practical engineering.