Experimental Study On Human Thermal Reaction In Radiant Cooling Environment

As a kind of green energy-saving technology,radiant air-conditioning system has received extensive attention and application in recent years.Compared with the traditional convection air conditioning system,the indoor thermal environment created by the radiant air conditioner has a significant difference,which in turn has a certain impact on the physiological and psychological aspects of the human body.In this paper,theoretical and experimental research on the thermal reaction mechanism of human body under radiant cooling environment is carried out,and the human thermal sensation evaluation model under radiation cooling environment is obtained.In this paper,the experiments have a total of two types of radiation: floor radiant cooling and roof radiant cooling.Under the radiant cooling of the roof,experiments were carried out in a sitting position and a lying posture.Under the radiation and cooling of the floor,only the experiment of the sitting posture of the human body was carried out.A total of 25 eligible college students were recruited to conduct 214 experiments.The environmental and physiological parameters(skin temperature and heart rate and blood pressure)were measured under different conditions.Subjective questionnaires(overall thermal sensation,overall thermal comfort and local thermal sensation vote)were also conducted.The main research work and conclusions of this paper are as follows:(1)The regularity of the physiological parameters and subjective evaluation values of the subjects with the working conditions was studied.By analyzing the variance of skin temperature,overall thermal sensation voting and thermal comfort voting,the degree of influence of changes in working conditions on these parameters is clarified.The results showed that the average skin temperature and calf skin temperature of the siting posture human in roof radiant cooling,the average skin temperature of the siting posture human in the floor radiant cooling,the skin temperature of the calf and thigh,the average skin temperature of the lying posture human in the roof radiant cooling,the skin temperature of the lower arm and thigh were most obviously affected by the working conditions,and there were significant differences among the working conditions of the overall thermal sensation voting under each condition.There are significant differences.In addition,the heart rate increases with the increase of ambient temperature,but the change of blood pressure with environmental conditions is not obvious.(2)The relationship between the subjective evaluation of the thermal reaction and the operating temperature and mean skin temperature was analyzed.The results showed that the overall thermal feeling vote and thermal comfort vote were significantly correlated with operation temperature and average skin temperature under different conditions.When the same overall thermal feeling and thermal comfort were achieved,the operating temperature required by floor radiation was larger than that of roof radiation,while the roof radiation position was prone.The operating temperature required below is higher than that required in sitting posture.When the overall thermal sensation and thermal comfort are the same,the average skin temperature of the corresponding human body in the floor radiant cooling environment is higher than the roof radiant cooling environment,and the lying posture is higher than that in the sitting posture.(3)The relationship between local thermal sensation and overall thermal sensation was discussed.It was found that the overall thermal sensation was close to the lowest value of local thermal sensation in all cases.The head,chest and arms did not respond significantly in the cold environment and neutral environment.The end of limbs responded significantly to the changes of thermal environment.When the overall thermal sensation exceeded the neutral thermal sensation,the overall thermal sensation would approach the upper limb thermal sensation.(4)Based on the analysis of the relationship between skin temperature and overall thermal sensation voting,an evaluation model of human thermal sensation under radiation cooling environment was established and validated.