Numerical model of evaporative cooling processes in a new type of cooling tower A.S. Kaiser a, * , M. Lucas b , A. Viedma a , B. Zamora a a Dpto. de Ingenierı ´a Te ´rmica y de Fluidos, Universidad Polite ´cnica de Cartagena, Dr Fleming s/n, 30202 Cartagena, Spain b Dpto. de Ingenierı ´a de Sistemas Industriales, Universidad Miguel Herna ´ndez, Av. de la Universidad, s/n, Edificio Torreblanca, 03202 Elche, Spain Received 2 June 2004 Available online 8 December 2004 Abstract A numerical model for studying the evaporative cooling processes that take place in a new type of cooling tower has been developed. In contrast to conventional cooling towers, this new device called Hydrosolar Roof presents lower droplet fall and uses renewable energy instead of fans to generate the air mass flow within the tower. The numerical model developed to analyse its performance is based on computational flow dynamics for the two-phase flow of humid airandwaterdroplets.TheEulerianapproachisusedforthegasflowphaseandtheLagrangianapproachforthewater dropletflowphase,withtwo-waycouplingbetweenbothphases.Experimentalresultsfromafull-scaleprototypeinreal conditions have been used for validation. The main results of this study show the strong influence of the average water drop size on efficiency of the system and reveal the effect of other variables like wet bulb temperature, water mass flow toairmassflowratioandtemperaturegapbetweenwaterinlettemperatureandwetbulbtemperature.Nondimensional numerical correlation of efficiency as a function of these significant parameters has been calculated. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Drop size; Air-conditioning; Solar chimney; Cooling tower; Solar energy 1. Introduction Air-conditioning systems of buildings and other industrial facilities commonly use water as a heat ‘‘drain’’ to remove heat from refrigerant condensers. Classical solutions to reduce the temperature of this ser- vice water are usually mechanical draught-cooling tow- ers. In general, the height of these systems ranges between 2 and 12m. They are basically composed of shell, water distribution system, water collecting pond, fan to create the artificial draught and, in many cases, the filling. Careful and accurate analyses of cooling towers are desirable to ensure a precise determination of their per- formance. The fundamentals of the physical phenomena that take place in these systems are described by Merkel [1] and subsequently by Nottage [2]. Other authors, like Mohiuddin and Kant [3] have contributed with studies about the cooling tower systematic design. Fisenko etal. [4] presentanewmathematicalmodelofamechan- ical draught cooling tower performance. Benton and Waldrop [5] develop a numerical simulation of transport 0017-9310/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijheatmasstransfer.2004.09.047 * Corresponding author. Fax: +34 968 325 999. E-mail address: antonio.kaiser@upct.es (A.S. Kaiser). International Journal of Heat and Mass Transfer 48 (2005) 986–999 www.elsevier.com/locate/ijhmt