Numerical And Experimental Study On Physiological Responses In Hot Environments Based On Human-Clothing-Environment System

Thermal protection of human is an important research direction in the field of public safety.In case of fire emergency rescue,firefighters are always exposed to hot environments and wear thick protective clothing with intensive physical activity,which may cause heat strain.Hence,it is really significant to assess heat exchange of the human-clothing-environment system and human thermal responses under hot environments to ensure the safety of firefighters.In this paper,studies on human thermal response were conducted through subject tests,human thermal model,thermal manikin,and CFD simulation.The results obtained can be used to predict the human thermal responses,assess the thermal comfort and heat strain,guide the emergency rescue,and test and design of personal protective clothing.The main works and research results are as follows:Subject tests were conducted in normal(29 oC)and hot environments(45 oC)which was controlled by climate chamber.Shorts and two type of personal protective clothing were selected in this study.Core temperatures and skin temperatures at different body segments were measured continually when participants wear different clothing under normal and hot environments,respectively.The effects of ambient temperature and clothing type on human thermal responses were analyzed.The measured core and skin temperatures were then used to validate the thermal model,manikin system,and CFD simulation.Based on the normal thermal models,a multi-node thermal model suitable for the prediction of human physiological responses in hot environments was developed by considering the effects of high temperature on blood flow,metabolism,and heat transfer coefficients.The thermal model contained three parts: passive system was used to calculate the heat exchange within the human body and that between human body and environment;active system was used to model the thermoregulation of human body;clothing system was used to analyze the heat and mass transfer through clothing layer.Core and skin temperaturs from subject tests and those from model simulations were used to validate the proposed human thermal model.A coupling system was established by use of the developed human thermal model as the control system of sweating manikin,which could make the manikin “wisdom” and respond dynamically to the thermal environments as human body.The coupling system combined the advantages of both the sweating manikin and thermal model.The heat flux among human-clothing-environment could be obtained by the manikin and the model could estimate human thermoregulation system more accurately.The measured core and skin temperatures from subject tests were used to validate the coupling system under normal and hot environments.The comparisons between the measured data and simulated results from coupling system showed that it can not only predict the core and skin temperatures well under hot environments,but also can be used to test the performances of heat and moisture insulation of protective clothing.The current thermal model was coupled with CFD simulation system.The use of laser scanning technology was to develop computational themal manikin,and virtual climate chamber was established by ICEM software to set environmental conditions.The CFD coupling system was used to calculate the heat fulx,heat transfer coefficients,and skin temperatures under normal and hot environments.Results showed that the CFD simulations agreed well with the experimental data and simulation results from lieteratures.The CFD coupling system was capable of calculating thermal responses and heat exchange between human body and environment under hot environments.