A coupled model and thermo-electrical performance analysis for flat heat pipe-based battery thermal management system

Power battery is one of the key components of the electric vehicles, and an efficient battery thermal management system (BTMS) is significant for improving power battery performance. Flat heat pipe (FHP) has lightweight structure and high thermal conductivity, receiving much more focuses in the field of BTMS. In this paper, an FHP-based BTMS configuration is proposed. A coupled model of FHP and batteries was established considering the vapor flow effect of the FHP working medium, which can calculate the battery electrochemical parameters, battery heat generation rate, FHP heat transfer capacity in real time. The coupled model was verified by experiment. Then, the battery thermo-electrical performance at different discharging conditions is simulated and analyzed, and the relationship between battery electrochemical parameters and discharge rate is reflected. Under 3C discharge rate, the battery maximum temperature can be limited under 50 °C, while the maximum temperature difference can be kept below 2.26 °C. Finally, the influence mechanism of different FHP structural parameters including vapor chamber thickness, FHP total thickness, FHP total length on battery thermo-electrical characteristics is investigated. The results show that the decrease of FHP vapor cavity thickness or FHP total thickness will not only increase the vapor thermal resistance, but also aggravate the uneven distribution of FHP heat transfer capability, worsening the battery thermal performance on this occasion. The uneven battery module temperature distribution will further lead to non-uniformity of battery electrical performance. The change of FHP total length will result in the change of the total FHP heat transfer thermal resistance and affect the battery overall performance.