Effect Of Local Heating Air Supply On Thermal Comfort In Cold Environment

With the increase of building energy consumption and the grow in number of sick building syndrome,personalized ventilation is emerging as a new type of air conditioning,and is widely used in the office environment because of its advantages of health and individualized adjustment.But at present,there are many studies on the personalized ventilation in summer,the research of winter is relatively small and the personalized ventilation device is basically idle in winter.Combined with the existing office environment personalized ventilation device,to explore whether the personalized ventilation can meet the needs of human thermal comfort under the cold environment,and realize the "the integration of terminal device in winter and summer" in the form of air conditioning.The previous study found that the local heating was required by most of the office workers,and the warm air fan experiment in the office proved that the local heating could improve the comfort of the human body under the cold environment.Therefore,this article will focus on the wind supply parts,air supply temperature and their impact on human comfort in winter.Under the background of 16? /60% and 18? /60%,18 healthy college students were recruited,the winter clothing was carried out with a hot air supply of the foot and foot,at the same time,a contrast experiment with no personalized ventilation was set.During the period,the subjects' comfort changes were collected through a subjective questionnaire,and test the skin temperature of the subjects at the same time.The results show that there is positive correlation between the thermal sensation and the temperature of the air supply and the thermal sensation increases with the increase of the air temperature,and the pleasure of the blow will rise with the increase of the wind temperature,and the pleasure of the foot delivery is higher than that of the face;the perceived air quality decreases with the increase of the enthalpy difference of the air supply,and gives the face delivery at 16? and 18?,the enthalpy range of the air is-8~18kJ/kg and-19~46kJ/kg.In non-homogeneous environments,the PMV model can not be used directly for the prediction of human thermal sensation,and the weights of local thermal sensation should be taken into account.The foot heating air supply experiment shows that the background temperature affects the weight of the local thermal sensation on the overall thermal sensation,and the weight of the influence weight of the head,chest,back,upper arm,lower arm,hand,thigh,leg and foot are divided into 0.10,0.07,0.06,0.08,0.14,0.15,0.13.The results of human comfort test show that background temperature is the main factor affecting the change of skin temperature.There is a significant difference between the skin temperatures in different parts of the same background temperature.Under the condition of different background temperature,the correlation between the air temperature difference and the average skin temperature is not significant.Under a uniform partial cooling condition,the skin temperature range of 32.29?~32.61? is characterized.At the same time,the experimental results show that the local hot air supply does not affect the body's humid sensation,humid comfort,and the perceived air quality,although it will cause a certain sense of draft but within the acceptable range.Finally,the overall thermal sensation is regressed,and the range of air temperature difference in different parts is given according to the requirements of ASHRAE thermal sensation in the-0.5~0.5 range: the proposed face air supply temperature difference at 18? is 8?~11?,the foot is 8? ~17?;and the face air supply temperature difference of 16? is 10?~15?,the foot is 16? ~21?.It is recommended to use foot hot air supply at the same temperature difference level,to provide reference for personalized ventilation design under cold environment.