A Finite Element Based Transient Three-Dimensional Model Of The Human Thermal System Evaluated From Smith Model

With the energy shortage problem is more and more prominent, it is emergency to reduce the building energy consumption, which are one third of the social commercial energy consumption. It is a good idea to introduce computerized human thermal model into heating, ventilating and air conditioning field. The model is an efficient tool for researches of indoor air distribution theories, thermal comfort theories, and an predicting tool for air conditioning related projects. This paper will focus on developing a new computerized human thermal model, which will be the first computerized human thermal model of China and will specialize at fulfilling various customized requirements of HVAC researches.The physiological model is developed at this paper based on abundant researches about human physiological phenomenon. Sub-mathematical-models such as controlling model, passive model, hematological system model are developed based on Smith model, which is a famous finite-element 3D model developed at 1991, but with significant improvements. The modified mode has 16 segments, which including 66 layers and a center blood element. Conclusions can be made as followings,Firstly, The disadvantage of the blood tree model and current blood system model are analyzed. New skin and inside three layers blood perfusion models are developed at this paper. Conclusion can be made that the AVA phenomenon is properly solved and a significant improvement of the accuracy is available at this model.Secondly, A new heat and moisture model between skin surface and clothes and environment is introduced here, which considers all of the heat and moisture exchange to be Neumann (or second-type) boundary condition. Great benefits will be available for the various requirement of the clothing model.Thirdly, The effects of various sweating factors on average skin temperature is quantitative analyzed. Shitzer model is introduced here to improve Smith model. The disadvantage of the Smith metabolic rate model is figured out. The Fiala metabolic rate which is good at describing dynamic metabolic rate is employed here.Forthly, The comparisons of the parameters of different models have been made. It is found that most of the differences are as many as 30%. With the parameter sensibility analysis, conclusions can be made that the blood skin perfusion plays an important role at the thermal-regulation functions, the physical dimension effects average skin temperature largely, the whole blood perfusion and emissivity is not a big deal at the range of 10%.What's more, A completed human model has been built at this paper. Some case studies are made between our model and other famous models. The results are also compared with international experiences data. Comparing with Shengwei Zhu model, it shows this model has solved the problem of AVA phenomena at Smith model. Conclusions can be made that our human model can predict the skin temperature at the non-uniform and dynamic environment correctly.