A research on the performance and heat mass transfer of an unitary direct water cooled air-conditioner

• Main Authors: Jian-Wen Chen, 陳建文
• Other Authors: Yew-Khoy Chuah
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/6e388r

碩士 === 國立臺北科技大學 === 能源與冷凍空調工程系 === 106 === This thesis attempts to develop an air-conditioner which integrates a water cooled condenser in the equipment. The helical coil condenser immersed and dissipates heat in a water tank that is part of the air-conditioner. A water pump circulates water from the water tank to a water spray above the tank to maintain the water temperature. The water drops are cooled by counter direction airflow. The circulation in the tank effectively enhances the heat transfer, with convective transfer coefficient at the coil surface measured up to 1000W/m^2℃. Experimental tests were carried out for fixed water flow rate and fixed air flow rate, but with variable water to air ratio (L/G) so to investigate the effect on condenser heat dissipation. It has been found that for fixed water rate when L/G decreases from 1.5 to 0.5, spray part heat transfer increases to 4.38 times, packing part decrease by 5%, and the rain part decreases by 44.9%. Moreover COP increases with lower L/G. For fixed air flowrate when L/G decreases from 1.2 to 0.8, the spray part heat transfer increases to 2.3 times, packing part decreases by 20.9% and the rain part decreases by 31%. Moreover COP decreases with lower L/G ratio. It has been that when air flowrate is fixed but decrease the L/G ratio, the resulting lower water circulation will smaller water spray coverage consequently reduce the heat transfer in the packing part. As a result COP will be lower. At water flowrate at 13.5LPM and L/G at 0.5 COP as high as 5.33 can be obtained. Experimental data show that when the condensed water from the evaporator is used as part of the makeup water, water conservation of more than 28% can be reached.