Performance assessment of a range-extended electric vehicle under real driving conditions using novel PCM-based HVAC system

Abstract

In this research paper, a novel Heating, Ventilation, and Air Conditioning (HVAC) system is proposed to mitigate the unfavorable effects of conventional HVAC systems on the Electric Vehicle (EV) range. The HVAC system is composed of a heat pump (HP) system with an additional phase change material (PCM) heat exchanger, which is a shell and tube heat exchanger and is parallel to the external heat exchanger of the heat pump cycle. This heat exchanger is designed to function as both condenser and evaporator in the cycle temporarily. The n-hexadecane is selected as the PCM in the shell, and R134a is the refrigerant in the tubes. The specific melting point of PCM in the comfort zone range leads to diminishing the compressor's power consumption and consequently the whole system. A copper foam is used to enhance the low thermal conductivity of the PCM. The enthalpy-porosity technique with the Volume Averaged Method (VAM) for modeling of the PCM-copper foam is applied for Computational Fluid Dynamics (CFD) analysis of the PCM's melting and solidification cycles in ANSYS Fluent software, and the results are obtained for modeling the heat exchanger in the heat pump cycle. A comprehensive thermal model is developed for the vehicle's cabin to improve the accuracy of the results. Nissan Leaf is modeled as the selected EV at different weather temperatures in the range of −5 °C to 50 °C with the Urban Dynamometer Driving Schedule (UDDS) driving cycle in Simcenter Amesim software. The results show that the proposed system increases the vehicle range by 19% and 11% compared with the conventional heat pump systems at the weather temperatures of 10 °C and 0 °C, respectively. Moreover, the energy consumption of various components in the cold start and hot start are compared and the results are interpreted.