Enhancing Cooling Uniformity in BTMS: Numerical Evaluation of Gradient-Width Mini-Channel Designs for Prismatic Batteries

The longevity, performance, and safety of lithium iron phosphate (LFP) batteries in electric vehicles (EVs) depend on the installation of an efficient battery thermal management system (BTMS). This study investigates a novel double serpentine gradient channel design (GCD) to enhance the thermal and hydraulic performance of a liquid-cooled BTMS. The evaluated cooling plates comprise four configurations: a conventional design, a basic gradient design, and two GCD variants, namely GCD-1 and GCD-2. A three-dimensional computational model based on the Reynolds-averaged Navier–Stokes (RANS) equations was established under laminar flow conditions with a tropical ambient temperature of 34° C. Performance was evaluated based on the maximum temperature $T_{{\max}}$, average temperature $T_{\text{ave }}$, and friction factor $\boldsymbol{f}$. Among the configurations evaluated, the GCD-2 design exhibited superior thermal performance, achieving reductions in $T_{{\max}}$ and $T_{\text{ave }}$ by 0.28° C and 0.18° C, respectively, relative to the baseline at a Reynolds number of 400, with good temperature uniformity. GCD-1 provided a slight thermal improvement and increased flow resistance. Although the conventional design had the lowest pressure drop, it delivered poorer cooling. Overall, the GCD-2 configuration provides a balanced improvement in cooling effectiveness with an acceptable pressure loss, making it a strong candidate for prismatic LFP batteries, particularly in hot climates.