Application of CFD to closed-wet cooling towers G. Gan, S.B. Riat*, L. Shao, P. Doherty Institute of Building Technology, School of the Built Environment, University of Nottingham, Nottingham NG7 2RD, UK Received 18 November 1999; accepted 16 March 2000 Abstract Computational ¯uid dynamics (CFD) is applied to predicting the performance of closed-wet cooling towers (CWCTs) for chilled ceilings according to the cooling capacity and pressure loss. The prediction involves the two-phase ¯ow of gas and water droplets. The predicted thermal performance is compared with experimental measurement for a large industrial CWCT and a small prototype cooling tower. CFD is then applied to the design of a new cooling tower for ®eld testing. The accuracy of CFD modelling of the pressure loss for ¯uid ¯ow over the heat exchanger is assessed for a range of ¯ow velocities applied in CWCTs. The predicted pressure loss for single-phase ¯ow of air over the heat exchanger is in good agreement with the empirical equation for tube bundles. CFD can be used to assess the eect of ¯ow interference on the ¯uid distribution and pressure loss of single- and multi-phase ¯ow over the heat exchanger. 7 2000 Elsevier Science Ltd. All rights reserved. Keywords: Cooling tower; Heat exchanger; Multi-phase ¯ow; Pressure loss; Computational ¯uid dynamics 1. Introduction A closed-wet cooling tower (CWCT) is an indirect-contact cooling tower for evaporative and convective cooling of the ¯uid inside the tubes of a heat exchanger. Chilled ceilings are increasingly used for cooling oces where internal heat gains are often high and so cooling may be needed even when the outdoor air is moderate, say, at 208C. In a chilled ceiling system, cooling is accomplished by both radiation and convection to provide thermal comfort. The Applied Thermal Engineering 21 (2001) 79±92 1359-4311/01/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S1359-4311(00)00048-X www.elsevier.com/locate/apthermeng * Corresponding author. Tel.: +44-0115-951-3158; fax: +44-0115-951-3159. E-mail address: Saa.Riat@nottingham.ac.uk (S.B. Riat).