Study On The Effect Of Isothermal Blowing On Human Thermal Response In Sitting State

A comfortable environment in a building is crucial to the environmental satisfaction,health,and work efficiency of occupants.Air flow near the human body can effectively improve the discomfort of occupants in warm environments,thereby moderately increasing the set temperature of the summer air-conditioning system and reducing building energy consumption.Therefore,as a method to improve the comfort of indoor thermal environment,individual hair dryer equipment has been greatly welcomed.In a deviated thermal neutral environment,personal thermal comfort is effectively improved through personal control."If we can objectively and timely obtain the thermal comfort status of the human body and adjust the parameters of the blowing airflow in real time,it will better meet the personalized needs.Therefore,it is necessary to further explore the thermal response of the human body under the action of the blowing equipment and the relationship between objective physiological indicators and subjective parameters.In this study,the experimental study of the thermal response of the human body under the action of isothermal air flow was carried out by setting two relative ambient humidity levels and four wind speed levels in the summer hot indoor environment.On the basis of analyzing the variation of relevant physiological parameters with wind speed conditions,the correlation between different parameters is explored,and objective indicators of human thermal comfort in the blowing environment are proposed.The differences of subjective voting and objective physiological parameters such as thermal sensation voting(TSV),thermal comfort voting(TCV),sweating sensation and objective physiological parameters such as skin temperature,skin conductance level(SCL),skin convective heat loss,heart rate variability frequency domain index(LF/HF),and heart rate(HR)under different blowing conditions were analyzed.The results showed that when the direct wind speed was 0.69m/s,the human body felt the closest to the thermal neutral 0,and the thermal comfort vote was the highest,and when the wind speed reached 1.20m/s,the subjects would feel cold wind,and the air flow satisfaction was relatively reduced.The decrease in skin temperature on the forehead is most pronounced;Convective heat transfer: v=1.20m/s>v=0.69m/s>v=0.64m/s(swing)>v=0m/s;The SCL was the lowest in the static wind state,and the SCL was the lowest when the direct blowing wind speed was 0.69m/s and the highest when it was 1.20m/s in the blowing state.In both low humidity and high humidity environments,the convective heat transfer in the low humidity environment is higher than that in the high humidity environment.The SCL change after blowing in a low humidity environment is more significant than in the static wind state.The correlation between subjective and objective parameters was analyzed,and it was found that forehead skin temperature had a strong correlation with overall thermal sensation,which was an important physiological parameter indicating thermal sensation in a wind-blowing environment.Under the hot working conditions of this experiment,thermal comfort was negatively correlated with sweating,thermal sensation was negatively correlated with convective heat transfer,and SCL was positively correlated with convective heat transfer.SCL is positively correlated with airflow perception,so SCL is affected by airflow stimulation.In a quiet wind environment,SCL is positively correlated with thermal sensation voting,which can be used as an important parameter to indicate thermal sensation in the human body.In a blowing environment,SCL is negatively correlated with thermal comfort voting.The results showed that SCL had the possibility of evaluating the thermal comfort of the human body in the blowing environment.Based on the differences in subjective voting,this article also explored the differences in subjective voting and physiological parameters of different gender subjects under different blowing conditions.The results showed that in hot environments,men had a higher sweating sensation than women,and their average skin temperature was lower than women’s.The SCL of women in calm wind state is significantly lower than that of men.This article focuses on the impact of blowing airflow on human thermal sensation and comfort in a hot environment,analyzes the relationship between the thermal response and subjective and objective parameters of the human body under the action of airflow during sitting,and further explores reliable physiological indicators that indicate the thermal comfort state of the human body under different blowing environments.The research findings can provide a reference for the objective evaluation of human thermal comfort in a blowing environment and the control of individual air supply devices.