Reversible heat pump HVAC system with regenerative heat exchanger for electric vehicles: Analysis of its impact on driving range

Abstract

Besides providing energy for traction, an electric vehicle battery operates on-board auxiliary systems, among which air conditioning features the highest energy consumption and reduces significantly the driving range. Furthermore, electric vehicles heating needs are typically fulfilled through high-consuming resistors. In this respect, heat pumps promise higher energy efficiency and an increase in all-electric range.This paper analyses a reversible heat pump HVAC system equipped with a regenerative heat exchanger for pre-conditioning and hygrometric comfort improvement, and assesses air-conditioning energy loads and their impact on driving range for a vehicle performing daily commutes in different Italian cities. The dynamic model was set up in a Modelica framework. The overall system integrates component models calibrated against experimental data.Results confirm that air conditioning, consuming up to 32% of the energy required for traction on a daily commute, highly impacts on the all-electric range, which can decrease to 72 km from a base value of 94 km. In heating mode, replacing a resistor with a heat pump reduces consumption by 17–52% depending on geographical context, which proves to be highly effective in particularly demanding summer conditions lessening the driving range decrease up to 6%.