Thermoelectric cooling systems for eVTOL batteries operating on hot days

Abstract

Fast advancements in high-energy and -power density batteries, have recently enabled fully battery-powered advanced air mobility (AAM) aircraft development. Given the thermal-sensitive characteristics of lithium-ion batteries (LiB), those electric aircraft require a lightweight and highly-efficient battery thermal management system (BTMS) to dissipate waste heat, particularly for power-hungry flight phases or at high ambient temperature. To date, the relevant investigations, specifically for electric aircraft, are missing; therefore, as the first attempt, we introduce a thermoelectric heat exchanger into a previously developed liquid-cooling-based BTMS for a tilt-wing electric vertical take-off and landing (eVTOL) aircraft to mitigate aforementioned aerothermal concerns. We first compare a BTMS with and without the thermoelectric cooler (TEC) based on a hover-free flight mission to demonstrate its effectiveness and weight-and-power penalty. We then simulate and compare BTMS performance for four different hover durations (1, 3, 5, and 7 min). Our results show that, as the hover duration increases, the TEC-based BTMS works well for ambient temperature up to 45 °C at the expense of a reduced number of flights and additional weight. On the contrary, a TEC-free BTMS can only manage battery temperatures and health for ambient temperatures below 20 °C.