Ultra-High Sensitivity Thin Film Heat Flux Sensor for Battery Thermal Runaway Monitoring

Abstract

Thin-film heat flux sensor (HFS) can be widely used in the field of battery safety monitoring of new energy vehicles. In order to improve the accuracy of traditional engineering experience in the design of thin-film heat flux sensor and reduce the number of iterations, a finite element analysis model of thin-film heat flux sensor based on finite element simulation method is proposed in this paper. The model analyzes the effects of heat flux density and thermal resistance layer thickness on the temperature gradient of cold junction. At a heat flux density of 100 kW/m ² , the temperature difference is only 0.17 K, while at 1500 kW/m ² , it reaches 2.53 K. The temperature difference on the lower surface of HFS membrane is positively related to the heat flux. When the thickness of the thermal resistance layer increases from 2 μm to 15 μm, the corresponding temperature difference also increased from 0.034 K to 0.251 K. In addition, there is a good linear relationship between the temperature difference and the thickness of the thermal resistance layer (R ² = 0.99996), which shows that the performance of the thin film heat flux sensors is further optimised with the change of the thickness of the thermal resistance layer. This study provides a solid foundation for heat flux sensor and its application field of battery safety monitoring in new energy vehicles.