Numerical Investigation of Hybrid Thermal Management Systems Combining Phase Change Material and Liquid Cooling for Battery Modules in Regional Electric Aircraft During Nominal Operation and Thermal Runaway

Kurzfassung

Lithium-Ion batteries serve as a promising energy carrier to achieve climate-neutral aviation. However, the battery thermal management system contributes significantly to the total module mass, which reduces the total specific energy of the battery system. Hence, four hybrid thermal management concepts for a battery module are investigated, aiming to balance thermal performance with gravimetric power density. The investigated module consists of cylindrical Lithium-Ion batteries (LIB) and employs phase change material (PCM) for passive cooling as well as active liquid cooling. The scope of the investigation encompasses two different active cooling systems: a cooling plate design, featuring a bottom cooling plate with intercellular PCM, and a thermal conductive structure (TCS) design incorporating a bottom-side PCM layer and intercellular TCS. For each design, a robustness-focused and a mass-minimizing version is investigated. While all designs effectively maintain optimal thermal homogeneity during standard missions, the TCS-based design shows superior thermal reserves at the cost of increased mass and manufacturing complexity, while the cooling-plate-based design demonstrated superior thermal homogeneity. The study quantifies the trade-off between gravimetric efficiency and thermal performance, identifying the mass-optimized version of the cooling plate design as the optimal trade-off for further investigation in a defined worst-case-scenario. Under this extreme thermal runaway scenario, the system is designed to prevent propagation to adjacent modules during a mandated ignition profile of 20 % of cells within 60 seconds, which is successfully demonstrated by the verified numerical results. Thus, this work provides a decision-making framework for designing inherently safe, lightweight energy storage in electric aviation.