Energy consumption of mobile air-conditioning systems in electrified vehicles under different ambient temperatures

Abstract

In 2019, passenger car CO₂ emissions peaked at 3.2 billion metric tons globally. Despite efforts to curb vehicle CO₂ emissions and the ambitious targets adopted for greenhouse gas mitigation in the European Union (EU), emissions from road vehicles increased steadily over the past decade. Electrified vehicles have gained significant market share in the last years and are an essential technical option to reduce CO₂ emissions. Range anxiety and insufficient charging infrastructure limit electrified vehicles’ customer acceptance and market attractiveness. The use of auxiliary systems under certain circumstances may reduce vehicle range. In this regard, energy management improvements lead to better vehicle range results. As well-considered in numerous studies, the most consuming auxiliary system is the vehicle’s heating, ventilation and air-conditioning (HVAC) system, also known as Mobile Air-Conditioning (MAC). The present work explores the influence of different parameters on the energy consumption of the MAC system in plug-in hybrid vehicles (PHEV) and battery electric vehicles (BEV). For this purpose, one PHEV and one BEV were tested in laboratory conditions at different cell temperatures of −7°C (19.4°F), 22°C (71.6°F) and 35°C (95°F), over the Worldwide Harmonised Light vehicle Test Cycle (WLTC). Laboratory tests with the same conditions were repeated with MAC on and off for each temperature. For the reference 23°C (73.4°F) condition, additional factors affecting energy consumption were analysed, such as the impact of depleting/sustaining modes on the MAC performance in PHEV, or the effect of warm and cold start in PHEV and BEV. Results suggest that the electric energy required to heat the cabin at low temperature (−7°C) could be 4–10 times higher than the energy needed to cool down the cabin in hot conditions (35°C). Compared to the vehicle energy required at the wheels during a WLTC, the MAC impact at −7°C ranges from 35% to 45% while at 35°C goes from 15% to 18%.