Simplified model for indirect-contact evaporative cooling-tower behaviour Pascal Stabat*, Dominique Marchio Ecole des Mines de Paris, Centre d’e ´nerge ´tique, 60, Boulevard Saint Michel, F 75272 Paris cedex 06, France Received 15 July 2003; received in revised form 21 August 2003; accepted 6 September 2003 Abstract A simplified model for indirect cooling towers behaviour is presented. The model is devoted to building simulation tools and fulfils several criteria such as simplicity of parameterisation, accuracy, possibility to model the equipment under various operation conditions and short computation time. On the basis of Merkel’s theory, the model is described by using the Effectiveness-NTU method. The model introduces only two parameters, air-side and water- side heat-transfer coefficients which can be identified from only two rating points, data easily available in manufacturers’ catalogues. Thus, the model allows one to estimate energy and water consumptions under different operating conditions such as variable wet-bulb tempera- tures or variable airflow rates. # 2003 Elsevier Ltd. All rights reserved. Keywords: Closed cooling tower; Heat and mass transfer; Modelling; Air conditioning; Variable air-flow rate; Water consumption 1. Introduction Indirect cooling towers are commonly used in industrial processes and in air- conditioning systems to reject heat to the atmosphere. An indirect cooling tower is a device which uses heat and mass transfer to cool water from a process. The hot water goes through serpentine tubes arranged in rows, whereas the air passes on the external side of this coil. An additional circuit sprays water to cool further the coil by evaporation (Fig. 1). The main advantage of this system compared with an open cooling-tower is that the contamination risks with airborne dusts and corrosion are Applied Energy 78 (2004) 433–451 www.elsevier.com/locate/apenergy 0306-2619/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.apenergy.2003.09.004 * Corresponding author. Tel.: +33-1-40-51-94-19/91-80; fax: +33-1-46-34-24-91. E-mail addresses: pascal.stabat@ensmp.fr (P. Stabat), dominique.marchio@ensmp.fr (D. Marchio).