Numerical study and optimization of battery thermal management systems (BTMS) Based on Fin-Phase change material (PCM) in variable gravity environments

Abstract

Phase change materials (PCMs) are widely employed in electronic thermal control systems for spacecraft because of their substantial energy storage competencies. Hence, the impact of gravitational acceleration (GA) on PCM thermal performance holds particular significance. Moreover, given considerations for spacecraft center of gravity, attitude control, and structural design, choosing an optimal battery placement orientation becomes pivotal for maximizing available space utilization. This study employs the enthalpy-porosity method to simulate and assess the heat transfer efficiency of PCM and the thermal behavior of cooling battery thermal management system (BTMS) under different gravity environments (0.05 g, 0.1 g, 1 g, 10 g, and 20 g) and different inclination angles (θ = 90°, 45°, 0°). The research findings indicate that when θ = 90°, as gravity increases from 0.05g to 20g, the complete melting time of PCM at GA = 20g is shortened by 95.05 s (15.00 %) compared to GA = 0.05g. Particularly, when GA = 10 g, increasing θ from 45° to 90° reduces PCM melting time by 59.05 s (9.66 % reduction) compared to θ = 45°, while at θ = 0°, it decreases by 65.75 s (10.75 % reduction). Notably, at θ = 45°, some unmelted solid PCM accumulates in the lower right corner of the enclosure hindering the BTMS heat transfer. Based on PCM melting characteristics, three optimization structures for different θ are proposed. At t = 240 s, PCM melting significantly improves with fins. Comparing Convective Heat Transfer Coefficients (CHTC) curves before and after optimization reveals reduced accumulated effects. However, more fins aren't always better due to BTMS weight considerations. Investigating enhanced CHTC, fin mass, and volume ratio(γ), the optimized model impacts BTMS weight differently for θ values. θ = 45°, a combination of annular and straight fins, is determined optimal using entropy-weighted TOPSIS. This paper innovatively studies PCM melting in BTMS under varied gravitational environments and θ, proposing an enhanced heat transfer scheme for aerospace BTMS design.