Investigation, development and experimental analyses of a heat pipe based battery thermal management system

In this paper, the performance of a heat pipe based thermal management technique for batteries has been investigated experimentally. In this regard, a test rig was developed and used to demonstrate the effectiveness of flat heat pipe (heat mat) technology at controlling and maintaining the temperature of a prototype battery module, which consisted of sixteen prismatic lithium-titanate (LTO) cells. Test results were obtained which proved the ability of the technology to keep the battery cells at an optimal temperature, during cycling representative of real-world operation, from either a cold or hot start. The heat mat was shown to efficiently absorb the heat generated by the cells and transfer it effectively to an external cooling medium of either water or refrigerant. In conclusion, it was demonstrated that the maximum cell temperature is significantly reduced and the overall temperature uniformity of the module is greatly improved, when compared to a module with no thermal management. The maximum cell temperature was kept below 28 °C and the module temperature uniformity was maintained at +/−1 °C. By using test cycles that generated a quasi-steady-state heat load from the cells, it was shown that approximately 60% of the heat generated by the cells was removed by the heat mat. The results obtained from this work demonstrate that heat mat technology can improve battery performance and longevity by reducing the degradation and ageing process and cell imbalances, that result from high cell temperatures and module/pack-level temperature non-uniformity.