Thermal Performance of Cylindrical Lithium-ion Battery Modules: A Multi-objective Cfd Investigation of Air-zone Geometries

Abstract The thermal behavior of cylindrical lithium-ion battery modules is strongly shaped by how air is routed around the cell array. This paper presents a multi-objective CFD investigation of six air-zone geometries: Rectangular, U, Z, J, T, and X to evaluated under a fixed module envelope and equal mass-flow constraint. A verified model (benchmarked against Yang et al.) is employed to resolve transient cell temperatures over the depth-of-discharge (DOD) trajectory. To enable a broad geometry sweep, we use a 2D reduction focused on the air zone and cell array and assess two thermal objectives: the peak module temperature T max and the temperature non-uniformity ΔT. Results show a consistent ranking driven by manifold-induced flow distribution: X-type and T-type deliver the lowest T max and smallest ΔT; J-type and Z-type are intermediate; Rectangular and U-type are least favorable. The trends persist across operating stages, with worst thermal performance near mid-DOD where heat generation peaks. Within the study scope, modest operating variations primarily scale absolute temperatures without altering the geometry ordering. Limitations are noted: the 2D model omits spacer/tube 3D details and does not report hydraulic losses or fan power.