Research On Combined Cooling And Heating Characteristics Of Radiant Floor And Fan Coil

The most active area of China’s economy is hot in summer and cold in winter.Its climate is characterized by humid and hot summer and humid and cold in winter.With the continuous development of economy and the improvement of people’s quality of life,the demand for comfort and energy consumption of the area has become a hot topic.The combined cooling(heating)system with radiation and convection end is widely recognized as a comfortable,energy-saving and environmental protection air conditioning system widely used in residential buildings in the area,but the research on energy consumption and thermal comfort of radiation and convection combined cooling(heating)system is relatively few.According to the actual needs of hot summer and cold winter areas,this paper built an experimental system of radiant floor and fan coil,and studied the change of thermal environment,the dynamic change of system energy consumption with climate,and the change of thermal comfort of school-age children and adults in this environment.Firstly,under the condition of continuous cooling in summer,the indoor thermal and humid environment state of floor radiant heating and fan coil unit with water supply temperature of7 ℃,11℃,15℃ and single fan coil unit with water supply temperature of 11℃ were studied,the variation of water temperature of each subsystem with climate,the measured thermal comfort,energy consumption and energy efficiency of the system were studied.The results show that the changes of PMV under the four cases tend to be consistent with the changes of operating temperature,and the measured PMV is linearly correlated with the changes of indoor operating temperature.The proportion of thermal sensing scale between-1 and + 1 is 79.3%,88.6%,100% and 100% respectively under the condition of double end of radiant floor and fan coil under the condition of 7 ℃,11 ℃ and 15 ℃ and single end of fan coil under the condition of 11 ℃.The results show that the overall thermal comfort can meet the class II standard under the operating conditions of double terminal with water supply temperature of 15 ℃ and single terminal with water supply temperature of 11℃.Compared with the single terminal with water supply temperature of 11 ℃.The double terminal with water supply temperature of 15℃ has more "cool" indoor thermal sensation evaluation because of floor assisted cooling.At the same time,the higher the water supply temperature is,the lower the energy consumption is.When the water supply temperature is15 ℃,the energy consumption is 18.2% lower than that when the water supply temperature is 7 ℃.And 8.8% lower than that when the water supply temperature is 11℃.When the water supply temperature is 11 ℃,the energy consumption is 9.1% lower than that when the water supply temperature is 11 ℃.At the same time,the fan coil bears part of the sensible heat load and all the latent heat load.While the floor radiation bears part of the sensible heat load,and the cooling capacity of the fan coil is more than 60%.Secondly,under the condition of continuous heating in winter,the operation characteristics of the floor radiation system under the dual climate compensation technology are explored.The results show that the average hourly heating performance ratio of the system with dual climate compensation technology is 2.9,and the dual climate compensation technology has no significant effect on the heating performance of the system.The heat output of the system can be adjusted according to the outdoor temperature to reduce the impact of outdoor temperature fluctuation on the indoor thermal environment and improve the thermal comfort of the indoor environment.Finally,a questionnaire survey was conducted among 16 adults and preschool children,and the difference analysis method was used to analyze the thermal response of the subjects.The air temperature,relative humidity and distance from the west window were(1)21.39℃,38.3%,1.2m(2)22.6℃,38.3%,3.6m(3)22.6℃,40.6%,1.2m(4)23.9 ℃,40.6%,3.6m respectively.The results showed that there was no significant difference in the local thermal sensation voting between the two groups(P>0.05).The overall hot feeling of preschool children is higher than that of adults.There was significant difference in local thermal comfort of forehead and back of upper body(P<0.05),but there was no significant difference in local thermal comfort of abdomen,arm,back of hand and leg(P>0.05).There were significant differences in overall thermal comfort,blowing sensation and humidity sensation among the subjects(P<0.05).The results showed that there was a linear correlation between the overall thermal voting of the two subjects.At the same time,there was a linear correlation between the overall thermal voting of the two subjects and the indoor operating temperature.The overall thermal comfort voting of adults did not change with the TSV of the overall thermal voting.There was a large deviation in preschool children’s thermal evaluation standard based on PMV model,and the measured PMV-PPD model was not suitable for preschool children.