Enhanced indirect liquid cooling for cylindrical Lithium-ion battery module using microtubes and housing system

Effective thermal management is essential for ensuring the safety and performance of lithium-ion batteries (LIBs) in electric vehicles (EVs). This study introduces an innovative liquid-cooled battery thermal management system (BTMS) for 18650-type cylindrical batteries, featuring microtubes (MCTs) embedded in a heat conduction block (HCB) combined with an aluminum housing structure. Through comprehensive numerical analysis, the effects of MCT quantity (2–16), housing thickness (0.5–2.5 mm), coolant mass flow rate (2.8 × 10^-4 to 1.4 × 10^-3 kg/s), and tube diameter (0.75–1.75 mm) on thermal performance are investigated. The system demonstrates exceptional cooling capability, maintaining the maximum temperature in the module ($T_{\max }$) below 35°C at 3C discharge with just four MCTs and a low flow rate of 2.8 × 10^-4 kg/s. The optimal configuration (10 MCTs, 0.5 mm housing) achieves a $T_{\max }$ of 30.37°C and a remarkably low maximum temperature difference between different batteries ($\Delta T$) of 2.72°C; a 55.1% improvement over non-housed designs. Furthermore, increasing the tube diameter from 1 mm to 1.75 mm reduces pressure drop by 96 % while maintaining compactness. This BTMS design outperforms conventional approaches by simultaneously optimizing thermal uniformity, energy efficiency, and manufacturability, offering a practical solution for next-generation EVs.