Research On The Thermal Comfort Of The Capillary Radiant Heating

With the rapid development of economy and technology,people's living standard has been greatly improved.Improving the indoor environment of the Yangtze River Basin is urgent.The climate in this area is special.The summer is hot but cold in winter and the temperature difference of the day is small.The annual rainfall and sunlight is low but the humidity throughout the year is high.Unlike the north of China which provides central heating,the indoor environment of this place in winter is bad.Suitable heating equipment is needed to meet the requirement of indoor thermal comfort.To study the thermal comfort of radiant heating,three capillary radiation ends are studied,including ceiling radiation,wall radiation and floor radiation.The air temperature of the experiment are16?18 and 20 degrees centigrade.16 healthy college students(half males and half females)participated in this experiment and filled in the the subjective questionnaire once in a while.At the same time,the environmental parameters and the skin temperature of the subjects were measured.The clothing insulation of the garment was 1.2clo and the metabolic level was 1.1met.Through the experiment,we found that the air temperature increases with the height,and vertical temperature difference meets the requirement of A level comfortable standard in ISO 7730.Besides,the difference between the surface temperature of the ceiling and the surface temperature of the floor does not meet the evaluation index of the radiation asymmetry.The vertical temperature gradient of the floor radiation is the minimum and the temperature distribution is the most uniform.From the horizontal temperature field,the radiant effect of the ceiling radiation is similar to that of the floor radiation,which are better than that of the wall radiation.Secondly,through the comprehensive analysis of the objective physiological response and the thermal response,we found that the average skin temperature and the local skin temperature with three radiation terminals are not significantly different when the indoor temperature was 20 degrees centigrade.But when the indoor temperature is 18 and 16,the result is the opposite.Average skin temperature of floor radiation is maximum and that of wall radiation is minimum.Local skin temperature of three radiation terminals has significant differences.Chest temperature is highest and the longer the distance between the chest,the temperature difference between this two part is bigger.Besides,the higher the indoor temperature,the smaller the temperature difference between the all parts of the body.When provided floor radiantion,the temperature of foot increases significantly,but due to the different sensitivity of different subject,there was significant difference in the foot temperature.Through researching participants' subjective thermal reaction,we find that the vote difference decreases as the thermal level of body increase.When the indoor environment is 20 degrees centigrade,there are no differences in overall thermal sensation,but when the indoor environment temperature is 18 and 16 degrees centigrade,the overall thermal sensation with the floor radiant heat is highest.The local thermal sensation of the human body in different conditions is obviously different relative to the overall thermal sensation.The humidity sensation were slightly dry,connected with relative humidity changing from 45% to 60%,20% to 40% subjects expect the rise of humidity,which indicates that the staff had to adapt to high humidity.From the humidity expectation percentage,about 50% of the participants expected humidity to be constant,which proved that indoor humidity could be improved effectively under the condition of radiant heating during the winter outdoor high humidity environment in this area.From the analysis of air flu,it can be seen that under the radiation condition,the subjects think that the air flu in the room is smaller,and the higher the indoor temperature is,the smaller the indoor air flu is,the more the indoor air flow is expected.Then,using the regression analysis method of comfort analysis,the results show that in the acceptable environment,the average skin temperature of 32.18 to 33.44 degrees centigrade;the thermal neutral temperature of floor radiation,wall radiation and ceiling radiation were 17.92 degrees centigrade,18.41 degrees centigrade and 18.30 degrees centigrade respectively,the acceptive operation temperature of floor radiation was 15.98 to 19.88 degrees centigrade,the acceptive operation temperature of wall radiation was 16.19 to 20.62 degrees centigrade,the acceptive operation temperature of ceiling radiation was 16.05 to 20.54 degrees centigrade;from the comparative analysis of thermal sensation vote PMV and the actual thermal sensation vote of TSV can be seen,PMV and TSV deviation was between 0.25 to 0.75.Finally,through the single factor correlation analysis and canonical correlation analysis,we found that indoor air temperature and the average radiation temperature showed a good linear relationship with the thermal sensation vote and thermal comfort vote,the correlation coefficient was the highest,followed by the vertical temperature difference and relative humidity and the correlation coefficient of horizontal temperature difference is minimum.Vertical temperature difference is negatively correlated with thermal sensation and comfort,while the rest of the index was positively correlated.