Experimental Research On Terminal Performance Of Floor Cooling With Capillary Tubes In Hot-humid Area

As the increasing improvement of material life recent years, occupancy requirements to built environment are increasingly high as well. Air conditioning in summer needs to be changed to more comfortable and efficiency, floor cooling with capillary tubes were investigated and applied as comfortability and energy efficiency over the years. However, application in hot-humid area was limited, the indoor temperature was not ensured as condensation and lower cooling capacity. Field study was conducted to analyze the performance of this cooling system. A bedroom in Chongqing was chosen to detailed investigate the indoor thermal environment, floor cooling capacity, floor condensation characteristic, and overall thermal comfort. The field study experiment conditions were differ according to different inlet water temperature(20 ℃,18 ℃,16 ℃),different outside weather(sunny day, cloudy day, overcast sky), dehumidification or not.Firstly, analysis of indoor thermal environment. The max temperature of indoor standard level was 26.8 ℃, 27.6 ℃, 26.9 ℃ with 20 ℃, 18℃, 16℃ inlet water respectively. The max temperature difference between 0.1m and 1.7m was 2.8℃, which was less 3℃ and meets the thermal comfort need of ISO7730 and ASHRAEE55-92. The black bulb temperature was 24.3℃ to 26.8℃ during testing period, which was lower than dry temperature about 0.4℃ to 1℃ at the same level. Besides, floor temperature and inner fa?ade surface temperature were also investigated.Secondly, the floor cooling capacity. The mean cooling capacity were 20 W/m~2, 27 W/ m~2, 30 W/ m~2 with 20℃、18℃、16℃ inlet water respectively, which could afford 40%,60%,60% of the max room cooling load respectively. The time of cooling capacity dropped to bench level(10 W/ m~2) were 5.3h,5h,10 h with 20℃,18℃,16℃ inlet water respectively when the system was shut up. The max drop rate were 2.4 W/ m~2/h, 2.8 W/m~2/h, 4.9 W/ m~2/h.Thirdly, the condensation characteristic. Time of start condensation was between 10:30 and 14:50, of which 80% were between 11:00 and 13:00. The air eddy area had condensation phenomenon in all condensed conditions, and also were the earliest start condense floor area. Start condensation time of the rest of floor area were delayed or did not even have condensation phenomenon. The difference of floor temperature and indoor temperature was 2.3-4.8℃. The factors which influence condensation were outdoor temperature, inlet water temperature, air distribution, dehumidification, different floor surface material.And finally, the comprehensive assessment. During operating time, the max cooling capacity was 23 W/ m~2 and indoor temperature was 25 to 27℃ with 20℃inlet water, the earliest time to condense was11:40. The max cooling capacity was 33 W/ m~2 and indoor temperature was 24.4℃to 27.6℃ with 18℃inlet water, the earliest time to condense was10:30. The max cooling capacity was 33 W/ m~2 and indoor temperature was 25.1 to 26.9℃ with 16℃inlet water, the earliest time to condense was10:40. The time to ensure indoor temperature effectively were 2h, 1.5h, 2h with 20℃,18℃,16℃ inlet water respectively when the system shut up. The most disadvantage thermal comfort level were all above Ⅱlevel during operating time.