Performance and energy implications of a reconfigurable multi-mode dehumidification and reheating heat pump for electric vehicles

Abstract

The performance of heat pump air-conditioning systems is crucial for electric vehicles (EVs), particularly under cold and humid conditions, where maintaining cabin comfort while minimizing energy consumption is a significant challenge. However, existing systems often suffer from an energy trade-off between dehumidification and reheating, leading to high energy consumption and reduced driving range in such environmental conditions. In this study, a multi-mode heat pump dehumidification and reheating system for EVs was developed, integrating four operational modes—Parallel Evaporator Dehumidification Mode (PEDM), Parallel Condenser Dehumidification Mode (PCDM), Whole Series Dehumidification Mode (WSDM), and Partial Series Dehumidification Mode (PSDM)—controlled by dynamic refrigerant flow regulation through solenoid valves and electronic expansion valves. A high-fidelity model was developed in AMESim and validated across a wide temperature range from −10 °C to 25 °C, coupled with a vehicle-level energy flow model for evaluating the effects on HVAC and overall vehicle energy consumption under the Worldwide harmonized Light-duty Test Cycle (WLTC).The results indicate that PEDM achieves the highest dehumidification coefficient of performance (DHCOP) and the lowest HVAC energy consumption (20.4 Wh/km), improving driving range by 11% compared to conventional single-mode systems. PCDM, while offering the highest moisture extraction rate (MER), incurs significantly higher energy consumption (45.5 Wh/km). WSDM strikes a balance between energy efficiency and performance (22.6 Wh/km), while PSDM operates stably but with lower efficiency. The study provides valuable insights into the coupling mechanism between dehumidification performance and vehicle energy flow, laying a foundation for designing adaptive, energy-efficient heat pump systems for EVs in cold and humid environments.