Heat transfer simulation of electric heating fabric system and parametric design: Towards human thermal comfort and energy efficiency

A 3D heat transfer model was developed to optimize the design of electric heating garments (EHGs) towards human thermal comfort and energy efficiency. The model deals with the thermal interaction between human skin, a three-layer electrical heating fabric system, and cold environments, allowing analysis of the heating process and resultant skin temperature. Three heat transfer mechanisms, namely conduction, convection and radiation, were considered. The real-time and final skin temperatures from simulation and measurement exhibited a difference below 4%, demonstrating the efficiency of the model. A steady-state parametric study was conducted using the validated numerical model. Five parameters, such as heating temperature, thermal resistance of the inner and outer fabrics, wind speed, and environmental air temperature, were involved. The results indicate that the heating temperature and thermal resistance of the inner fabric have a more noticeable effect on the temperature of the skin surface below the heated area compared to the other three factors. Apart from the heating temperature, the other four factors have a greater impact on the skin temperature of non-heated regions than that of the heated region. Multiple linear regression analysis was performed to establish a relationship between skin temperature and the five factors. Based on this analysis, a prediction model for skin temperature was developed and subsequently used to determine relevant parameters for EHGs. A method for optimizing the design of electrically heated clothing is proposed, which can achieve the dual goals of human thermal comfort and energy efficiency.