Design and Simulation of eVTOL Aircraft Thermal Management System

This paper focused on designing a thermal management system (TMS) for a parallel hybrid electric (PHE) XV-15 tiltrotor aircraft used in urban air mobility (UAM) applications. The TMS is integrated into the aircraft system to assess its impact at aircraft and mission levels. Both liquid cooling and air-cooling TMS, along with using phase change materials (PCMs) for heat storage, were designed and assessed. Two liquid-cooling configurations, series and parallel, were evaluated, with the series configuration proving more effective in the considered test cases. The study compared hover and cruise conditions to determine optimal design point for the liquid-cooling TMS. Designing for hover resulted in about fourfold increase in the TMS penalty in fuel burn during cruise. Designing for cruise, on the other hand, proved infeasible to comply with the thermal management requirements during hover. Two approaches were explored to address this: Approach A involves adding PCMs as a heat storage system and approach B entailed redesigning the TMS with the heat load at off-design conditions for the inverter and motor. Both approaches resulted in a 24% and 46% increase in the TMS penalty in fuel burn compared to the design that solely considering cruise condition, respectively. The assessment of the designed aircraft systems, integrating the TMS for the considered test cases, revealed that the liquid-cooling TMS designed at cruise condition with Approach B emerged as the optimal design, showcasing a 42% improvement in fuel burnt per payload compared to the air-cooling TMS at the mission level.