Application Research Of A Novel Combined Dew Point Indirect Evaporative Air Conditioning Unit In Residential Building

with the rapid development of our national economy and the accelerate of new countryside building, China still has a huge market for household air conditioner. At present, owing to high supply air humidity and limited temperature drop, the use of direct evaporative cooling equipment of evaporative air cooler and evaporative air conditioner are limited. Traditional mechanical compression air conditioning has problems of power consumption and environmental pollution. Combined with dew point indirect evaporative cooling air conditioning technology, a novel combined dew point indirect evaporative air conditioning unit(short for air conditioning unit) is developed. It is a kind of indirect-direct evaporative cooling, supply air temperature is under wet bulb temperature and close to the dew point temperature. Because of the existence of indirect evaporative cooling section, supply air humidity get certain control.Under moderate humidity and high humidity condition, the performance parameters of air conditioning unit are tested. The results show that the best secondary to primary air ratio is 0.95 among the four values of 0.67, 0.73, 0.82 and 0.95, corresponding to the wet bulb efficiency for 103%. The most reasonable water drenching is 200 L/h, the average temperature difference is 9 ℃ and supply air relative humidity is 93.7%. Under the optimum conditions, the volume of supply air is 867m3/h and exhaust air is 823m3/h, corresponding water consumption is 1.2L/h for 10 minutes. The test results show that the optimum secondary to primary air ratio is0.72, the corresponding efficiency of wet bulb is 115% and water drenching is 450 L/h under drying conditions. Under the same load and influence of outdoor environment, the actual use effect of air conditioning and traditional air conditioning are tested in Xi’an. The comparative analysis show that air conditioning unit corresponds to the average temperature is higher 1~2 ℃ than traditional mechanical compression air conditioner,relative humidity is high about 10~30%. When the wet bulb temperature is higher than23 ℃, the indoor relative humidity begins to grew for air conditioning unit. In the paper, the optimum proposal of secondary to primary air ratio, core structure, direct and indirect segment size and segment water distribution is put forward.In the psychrometric chart, the applicability of air conditioning unit is partitioned based on indoor air state point N and supply air state point O. As in Urumqi, in order tomaintain indoor temperature of 28 ℃, rated supply air can meet the construction area of66.3 ~ 99.5 ㎡. On the other hand, required to maintain 20 ㎡ room of temperature 28℃and air conditioning requirements for eight hours a day, it is need for 400~600m3/h of product air and 32.9~49.4L of water consumption under the running mode of fresh air.China building thermal environment analysis of meteorological data of 6~9month total 2930 h hourly wet bulb temperature is selected, in view of our country Urumqi, Lanzhou, Xining, Yinchuan, Kunming, Lhasa, Hohhot, Beijing,Tianjin, S hijiazhuang, Taiyuan, Harbin, Hangzhou, Ji’nan, Zhengzhou,Guangzhou, Changsha, Nanni ng, Guilin, Chongqing, Chengdu, Xi’an, Shanghai, Shenyang, Changchun, Nanjing and Fuzhou City. The hours and represent of outdoor wet bulb temperature ts ≤23℃,23℃ <ts < 28 ℃ and ts≥28℃ are calculated Respectively, the hourly supply air temperature tg2 and moisture content dg2 are calculated, then the time and proportion of air conditioning unit in cooling season. Combination the unit with PV/wind hybrid system is put forward in the paper.