Application Of Human Body Exergy Analysis Method In Building Dynamic Thermal Environment Assessment

At present,there are mainly three kinds of methods are used to research human body thermal comfort condition,respectively.The predicted mean vote(PMV-PPD),adaptive comfort model and human exergy analysis.The PMV-PPD index method is based on the human body energy balance equation and combined with experimental measurements.The relationship between indoor thermal environmental parameters and human thermal sensation was obtained,which is mainly used for the evaluation of thermal comfort in steady-state air-conditioned buildings;the adaptive model is based on field survey of natural ventilation buildings,which establishes a linear relationship between human comfort temperature and outdoor monthly average temperature.It is mainly used for thermal comfort evaluation in naturally ventilated buildings.The human body exergy analysis method takes into account the influence of indoor and outdoor thermal environment parameters,and combines the first and second laws of thermodynamics to analyze the exergy consumption caused by irreversible factors in the human body energy transfer process,which can be used for evaluation thermal comfort of occupant in natural ventilation and air-conditioning buildings.In view of the high air speed,it will affect the clothing thermal insulation and vapor resistance.Which is considered in the calculation of human body temperature and human body exergy consumption rate in this paper,modified the calculation method of human body temperature,a human body exergy model suitable for analyzing under steady state and transient environments is proposed.Based on fully verifying the model in this paper,quantitative analysis the effects of different relative humidity and air speed on human body exergy consumption rate varies with temperature,and obtain human body comfortable temperature under indoor air speed is 0.1 m/s,0.3 m/s,0.5 m/s and 0.8 m/s in summer.The results show that when the indoor temperature is lower and higher,the air speed has a greater impact on the human body exergy consumption rate,and with the increase of relative humidity,the effect of air speed on human body exergy consumption rate is reduced.In addition,it is found that the appropriately increased air speed and relative humidity can reduce human body exergy consumption rate.Furthermore,this paper also quantitatively analyzes the variation law of human body exergy consumption rate under single factor mutation condition of indoor thermal parameters,and of different populations under unsteady-state environment.It is found that in addition to the metabolic rate step condition,the single factor of other parameters step conditions occur "overshot phenomenon" of human body exergy consumption rate,and the greater the parameter step amplitude,the more obvious the "overshot phenomenon" of the human body exergy consumption rate.The orthogonal experimental design was also used to investigate the influence of the abruptly change of thermal environment parameters on the change range of the steady value of human body exergy consumption rate when occupant entered the air-conditioned room from outdoor.When indoor environmental parameters were to be certain,the magnitude of the abruptly change in temperature,relative humidity and metabolic rate is main factor affecting the magnitude of the change in human body exergy consumption rate.Finally,taking the Xi'an area as an example,comparing and analyzing the variation law of human body exergy consumption rate when people enter natural ventilation building and air-conditioned building during the hottest period in summer and heating room during coldest period in winter from outdoor.The results indicate that the wet exergy rate of skin layer is one of the main parts of various human body exergy consumption rates,and wet exergy rate of skin layer in the air-conditioned room are larger than those in the naturally ventilated room.In winter,human body exergy consumption rate during outdoor is greater than that in summer,and the change range of the human body exergy consumption rate before and after entering the air-conditioned heating room in winter is also significantly greater than that when occupant entering air-conditioned room in summer.