Self-regulated thermal comfort control for wearable heating device

In this study, a thermal comfort control model based on heat flux regulation was developed to ensure the thermal comfort in human-clothing-environment system. Compared to traditional temperature control methods, the heat flux control method in this study provided a more stable control for both temperature and heat flux, and clearly quantified human thermal sensation under cold stress. First, a heat transfer model was derived to quantitatively describe the heat transfer of an electrically heating device between two fabric layers. By using three temperature sensors, the mathematical description of derived heat exchange equation was validated and applied to a wearable heating device. The scenarios of a person in cold environments and under various activity levels were also simulated by using an environmental chamber. A control strategy based on the mathematical model was developed to optimize the applied voltage of the electric heater. The skin temperature and sensible heat loss can be stably controlled within standard thermal comfort range (Predicted Mean Vote ~ 0). Finally, an example of human wearing an electrically heated jacket in the freezer room was used to demonstrate the reliability and practicality of the heat flux control system.