Liquid-Cooled Battery System Design Method for eVTOL Aircraft

This study develops a liquid-cooled battery system design method that accounts for the battery thermal management system and key constraints by synthesizing various analytical models. It includes models for the battery, coolant channels, and heat exchanger, which are integrated into a comprehensive design procedure. The method is applied to the sizing of a notional electric vertical takeoff and landing aircraft and, together with a previously developed air-cooled battery design method, enables a quantitative comparison of air‐ and liquid-cooled battery systems in terms of payload performance under various operating conditions. The key conclusions are that the proposed liquid-cooled design method yields a battery system with a specific energy of 125 Wh/kg under the baseline mission and aircraft configuration, representing a 40.5% reduction from the cell-level specific energy of 210 Wh/kg, and that, while the aircraft sizing outcomes can vary depending on the battery cooling method and operating conditions, the overall performance difference between the air‐ and liquid-cooled systems remains small, indicating that both approaches provide comparable results.