Thermal management performance enhancement of cylindrical power battery modules via cooling strips with reflux microchannel structure

Without timely removal of the heat produced by vehicle lithium-ion batteries during discharge, thermal runaway will occur and pose a threat to the safety of vehicle occupants. As lithium-ion batteries are subject to requirements regarding their operating temperature (ranging from 20 to 40 °C), they also have a maximum tolerable temperature difference of 5 °C, efficient thermal management guarantees their safety and lifespan. This study focuses on a cylindrical power battery module, proposes a cooling strip with reflux microchannel structure (CS-RMS), and examines how cooling strip layout forms and structural parameters influence the thermal management performance of the battery. It is noted that the quantity of reflux-type cooling strips exerts a notable effect on the heat dissipation capability of the battery. Both an excessively large and an unduly small quantity of cooling strips are detrimental to the thermal management system. The Scheme- 3, consisting of three cooling strips, exhibits a low maximum value of temperature (Tmax) and maximum value of temperature difference (ΔTmax) comparable to those of Scheme- 2 (single cooling strip), while its pressure drop (ΔP) is significantly lower. The Nusselt number (Nu) and performance factor (pf) also indicate that Scheme- 3 possesses more excellent thermal-hydraulic performance. Moreover, the influence of the height of the forward channels of the cooling strips on heat dissipation system performance was taken into account, and it was revealed that a more uniform arrangement of forward and reflux channels is more conducive to improving the performance of the Battery Thermal Management System (BTMS). Finally, the BTMS underwent optimization through orthogonal trial, and the optimum set of parameters was determined as H3F2T1 with excellent heat dissipation performance with Tmax of 301.50 K and ΔTmax of 4.98 K and low pressure drop with ΔP of 557.84 Pa.