Exploration Of Thermal Comfort Of Building Environments Based On Exergy Analysis On Human Body

Due to the vast land and varieties of climate in China,Chinese have formed different living habits,which leads to different thermal comfort adaptive behavior of people in different areas.The development of heating and air conditioning technologies provide a comfortable indoor thermal environment for occupants.The predicted mean vote(PMV)approach,the adaptive comfort model or human body exergy analysis method have been used to predict indoor thermal conditions.The PMV model has established the relationship between indoor environmental parameters and human thermal comfort sensation and PMV method has been widely used to evaluate thermal comfort conditions of active buildings.The adaptive model which links the monthly average temperature of outdoor environment with thermal comfort of human body is mainly used to evaluate thermal comfort conditions of passive buildings.In view of the limitations of the former two methods,it is meaningful to explore the human body exergy analysis method developed on the basis of the first and second law of thermodynamics,a new method suitable for evaluations on both active and passive buildings.Moreover,exergy analysis method can direct proper operate regulation of HVAC system on account of the transformation of human thermal sensation.The paper will establish a human body exergy analysis model to explore building environmental parameters which satisfying thermal comfort of human body.A more feasible method to calculate human body metabolic exergy rate was proposed and a new human body exergy analysis model was established based on the related theories of metabolism and two-node model.And then,the model was validated by the data from ASHRAE thermal comfort database and Caliskan’s result.Then,the effects of indoor air temperature,indoor radiation temperature,indoor relative humidity,indoor air velocity,outdoor air temperature,outdoor relative humidity,atmospheric pressure,basic metabolic rate and clothing heat resistance on human body exergy consumption rate were determined by orthogonal experiment.After that,the relationship among human body exergy consumption,human body exergy exchange rate,indoor andoutdoor air parameters and thermal comfort index PMV were analysis.Finally,the model was used to explore Chinese people thermal comfort based the Chinese people’s physical parameters and climate zones in China.The results indicate that human body exergy analysis can be carried out more accurately if the metabolic exergy rates is calculated in terms of clearly understanding of energy metabolism;Outdoor air temperature has the most remarkable impact on human body exergy consumption rate,followed by indoor air radiation temperature and indoor air temperature;The proportion of exergy exchange rate to metabolic rate is smaller than that of exergy consumption rate;When the indoor operative temperature is 11℃,18℃ or 25℃,the convection and radiation exergy rate are the main components of the exchange rate,while for 32 ℃,the respiration and evaporation exergy rate are the main parts of the exchange rate;The extreme value of exergy consumption rate occurs under the conditions of lower or higher indoor operative temperature,therefore it can not be used as an evaluation index of indoor thermal environment;Combining exergy consumption rate and exergy exchange rate can evaluate indoor thermal comfort conditions more properly;When the indoor parameters remain constant,the minimum exergy consumption rate and the minimum exergy exchange rate appears under the outdoor condition with high temperature and low relative humidity;The effect of outdoor air relative humidity on exergy consumption and exergy exchange rate is not as significant as that of outdoor temperature;For different region of China,indoor design temperature of HVAC system should take occupant’s average age and gender into account;For various free running buildings distributing in China,human body exergy consumption rates increase as buildings altitude rising;For a given outdoor environmental parameter,human body in a passive building at a lower altitude is more comfortable than the corresponding human body in higher altitudes;The human body thermal comfort evaluation system of free running buildings in different region of our country should take building’s altitude and outdoor air parameters into account.