Thermal energy storage for increasing heating performance and efficiency in electric vehicles

Abstract

Battery electric vehicles suffer from significant range reduction in extreme cold weather conditions, largely due to the requirement of cabin heating and reduced battery performance. Since heating can require as much energy as the powertrain itself, improving the vehicle thermal energy management can have a substantial impact on range in cold driving conditions. In this paper, sensible and latent thermal energy storage (TES) methods are analyzed in order to improve heating performance and vehicle range in mild to cold weather conditions. To investigate the benefits of TES in electric vehicles, a model was developed in AMESim to simulate cabin heating and its transient interaction with the vehicle's energy systems during a given drive cycle. A thermal energy storage system was developed in the powertrain coolant loop which was integrated with an electric heater and a heat exchanger used for cabin ventilation. In addition to sensible storage, latent thermal storage was also investigated due to its ability to store energy at near constant temperatures. According to the simulation results, a thermal storage can increase the range close to 25%. This benefit is heavily dependent on the storage volume, storage initial temperature, and ambient temperature.