STUDY OF WATER MIST SYSTEM FOR PRE COOLING THE ENTERING AIR OF AN AIR COOLED CHILLER CONDENSER
ARTICLE INFORMATION ABSTRACT Original Research Paper Received 27 February 2016 Accepted 10 June 2016 Available Online 20 July 2016 A practical method for improving the COP of an air cooled chiller is pre cooling the air entering its condenser via a water mist system. This article studies a water mist system with hollow cone spray nozzles and investigates the effects of water flow rate, water droplet diameter and the number of spray nozzles on system performance. Simulations were run by FLUENT software, applying EulerianLagrangian method. Solution grid independency was obtained and was validated with experimental data. According to the results, in a constant air flow rate of 8.3 (kg/s) with increasing the water flow rate from 0.05 to 0.4 (kg/s) percent increase of COP increases from 3 to about 14, but the percentage of evaporated water decreases from 12.13 to 7.62 (however the value of evaporated water increases) Besides, decreasing the water droplets diameter from 200 to 50 micrometer, results in percent increase of COP from 4 to 24. Due to less water evaporation in higher flow rates, the number of spray nozzles was raised in a constant total flow rate which, according to the results, increasing the number of nozzles improves the system performance. Also, with other simulations it was observed that increasing the number of nozzles is more effective in higher flow rates and less drop diameters. Finally, the case study demonstrated that using sufficient number of nozzles, it is possible to achieve higher COPs in lower flow rates and therefore in addition to energy consumption, the water consumption could be reduced.