Main Article Content

Fu Wing YU Kwok Tai YANG Jia YANG Rachel Kam Yung SIT


Mist is increasingly applied to precool outdoor air in heat rejection. This study investigates how the coefficient of performance (COP) of an air-cooled chiller varies with a mist precooler at different levels of cooling effectiveness. A multivariate regression model was developed to simulate the operating variables of an air-cooled chiller with mist precooling. The model was validated with typical performance data of an air-cooled centrifugal chiller. The COP would increase by up to 30%, depending on the cooling effectiveness and the wet bulb depression— the difference between the dry bulb and wet bulb temperatures of outdoor air. At a large wet bulb depression, the percentage increase of COP tended to correlate linearly with the chiller capacity. Yet at a small wet bulb depression, the dynamic control of condensing temperature resulted in a non-linear relationship between the percentage change of COP and the cooling effectiveness. Further experimental work is required to optimize cooling effectiveness for the maximum COP. Keywords: air-cooled chiller; coefficient of performance; mist precooling

Article Details

How to Cite
YU, Fu Wing et al. COOLING EFFECTIVENESS OF MIST PRECOOLER FOR IMPROVING ENERGY PERFORMANCE OF AIR-COOLED CHILLER. Thermal Science, [S.l.], mar. 2017. ISSN 2334-7163. Available at: <>. Date accessed: 24 jan. 2018. doi:
Received 2017-03-06
Accepted 2017-03-13
Published 2017-03-13


[1] Wong, N.H., Chong, A.Z.M., Performance evaluation of misting fans in hot and humid climate, Building and Environment, 45 (2010), pp. 2666-2678
[2] Hamlin, S., Hunt, R., Tassou, S.A., Enhancing the performance of evaporative spray cooling in air cycle refrigeration and air conditioning technology, Applied Thermal Engineering, 18 (1998), pp. 1139-1148
[3] Sawan, R., Ghali, K., Al-Hindi, M., Use of condensate drain to pre-cool the inlet air to the condensers: A technique to improve the performance of split air-conditioning units, HVAC&R Research, 18 (2012), 3, pp. 417-431
[4] Vakiloroaya, V., Samali, B., Fakhar, A., Pishghadam, K., A review of different strategies for HVAC energy saving, Energy Conversion and Management, 77 (2014), pp. 738-754
[5] Hajidavalloo, E., Eghtedari, H., Performance improvement of air-cooled refrigeration system by using evaporatively cooled air condenser, International Journal of Refrigeration, 33 (2010), pp. 982-988
[6] Chowdhury A.A., Rasul, M.G., Khan, M.M.K., Modelling and analysis of air-cooled reciprocating chiller and demand energy savings using passive cooling, Applied Thermal Engineering, 29 (2009), pp. 1825-1830
[7] RaŠkoviĆ, P.O., VuĈkoviĆ G.D., VukiĆ M.V., Improving eco-sustainable characteristics and energy efficiency of evaporative fluid cooler via experimental and numerical study, Thermal Science, 12 (2008), pp. 89-103
[8] Hao, X.L., Zhu, C.Z., Lin, T.L., Wang, H.Q., Zhang, G.Q., Chen, Y.M., Optimizing the pad thickness of evaporative air-cooled chiller for maximum energy saving, Energy and Buildings, 61 (2013), pp. 146-152
[9] Yu, F.W., Chan, K.T., Yang, J., Sit, R.K.Y., Evaporative cooling technologies for air-cooled chillers for building energy performance improvement, Advances in Building Energy Research, (2015), DOI:10.1080/17512549.2015.1040070
[10] Yu, F.W., Chan, K.T., Modelling of improved energy performance of air-cooled chillers with mist pre-cooling, International Journal of Thermal Sciences, 48 (2009), pp. 825-836
[11] Yang, J., Chan, K.T., Wu, X.S., Yang, X.F., Zhang, H.Y., Performance enhancement of air- cooled chillers with water mist: Experimental and analytical investigation, Applied Thermal Engineering, 40 (2012), pp. 114-120
[12] Yu, F.W., Chan, K.T., Sit, R.K.Y., Yang, J., Energy simulation of sustainable air-cooled chiller system for commercial buildings under climate change, Energy and Buildings, 64 (2013), pp. 162-171
[13] Yu, F.W., Chan, K.T., Simulation and electricity savings estimation of air-cooled centrifugal chiller system with mist pre-cooling, Applied Energy, 87 (2010), pp.1198-1206
[14] Yu, F.W., Chan, K.T., Improved energy performance of air-cooled chiller system with mist pre-cooling, Applied Thermal Engineering, 31 (2011), pp. 537-544
[15] Tissot, J., Boulet, P., Trinquet, F., Fournaison, L., Lejeune, M., Liaudet, F., Improved energy performance of a refrigerating machine using water spray upstream of the condenser, International Journal of Refrigeration, 38 (2014), pp. 93-105
[16] Tissot, J., Boulet, P., Trinquet, F., Fournaison, L., Macchi-Tejeda, H., Air cooling by evaporating droplets in the upward flow of a condenser, International Journal of Thermal Sciences, 50 (2011) 2122–2131
[17] Liao, Y.D., Sun, Y.J., Huang, G.S., Robustness analysis of chiller sequencing control, Energy Conversion and Management, 103 (2015), pp. 180-190
[18] Air-Conditioning, Heating, and Refrigeration Institute (AHRI), AHRI Standard 550/590- 2003—2011 Standard for performance rating of water-chilling packages using the vapor compression cycle, Author press, Arlington, VA
[19] Crawley, D.B., Lawrie, L.K., Winkelmann, F.C., Buhl, W.F., Huang, Y.J., Pedersen, C.O., Strand, R.K., Liesen, R.J., Fisher, D.E., Witte, M.J., Glazer, J., EnergyPlus: creating a new- generation building energy simulation program, Energy and Buildings, 33 (2001), pp. 319-331