Effect of Cabin Insulation on the Heating Performance in EVs at Low Temperatures

Electric vehicles are considered one of the most promising solutions in the transport sector to curb greenhouse gas emissions and combat the effects of climate change. However, their performance in cold climates is adversely affected due to battery and cabin climatization resulting in reduced driving range. This study investigates the effect of heat transfer to the thermal masses on the cabin temperature in a passenger car, and the influence of insulation on different surfaces while climatizing under low ambient temperatures. A conjugate heat transfer model of the cabin was systematically developed, along with a framework to perform transient cabin heat-up simulations. The scenario considered was a vehicle driving at 50 km/h at -7°C for 40 minutes. Six configurations with insulation on different surfaces, including a fully insulated cabin, and four thermal resistance magnitudes were studied. For the same heating load, the fully insulated configuration exhibited about 5.6°C, and the seat insulated configuration recorded 2.3°C higher mean cabin temperatures than the non-insulated configuration. The rate of increase in the average cabin temperature of the insulated configurations was higher than the non-insulation configuration, and thus the cabin can reach the desired temperatures faster with sufficient insulation. An asymptotic increase in the mean cabin temperature was noted with increase in insulation resistance for the fully insulated configuration, with about 9°C higher mean temperature than the non-insulated configuration at a thermal resistance of 4 m²K/W. The results from the numerical model agreed well with the experiments performed in a climatic wind tunnel for both the baseline and the fully insulated configurations.