0011-9164/09/$– See front matter © 2008 Elsevier B.V. All rights reserved Desalination 238 (2009) 281–289 Effect of a cooling tower on a solar desalination system Hichem Marmouch a* , Jamel Orfi a,b , Sassi Ben Nasrallah a LESTE, Ecole Nationale d’Ingénieurs de Monastir, 5000 Monastir, Tunisie Fax: +216 (73) 500-278; email: hichem_marmouch@lycos.com b Mechanical Engineering Department, King Saud University, PO Box 800, Riyadh 11421, KSA Received 2 August 2007; Accepted 29 February 2008 Abstract A theoretical study was made on the effect of a cooling tower on a solar desalination system. A prototype unit was designed using the humidification–dehumidification principle. It had the following independent components: a humidifier, a condenser, two solar collectors of air and of water, and a cooling tower. The present unit was designed to work at low temperatures (60–100°C) of brackish water or using geothermal energy. A mathematical model based on the conservation equations of mass and energy was developed to present the temperature in every component. This system can operate with several configurations according to the use of the cooling tower and the multiple effects. Finally we looked for the optimal configuration for maximum fresh water production. Keywords: Cooling tower; Humidification–dehumidification; Multiple effects; Desalination 1. Introduction Solar desalination with humidification– dehumidification (HD) processes seems to be a promising method for supplying small com- munities in remote and sunny regions with water. The HD technique is especially suited for sea- water desalination when the demand for water is decentralized. Several advantages of this tech- nique can be presented which include flexibility in capacity, moderate installation and operating costs, simplicity, and possibility of using low- *Corresponding author. grade thermal energy (solar, geothermal, re- covered energy or cogeneration). Chaibi et al. [1] carried out a performance study of a solar multi-effect humidification unit installed in the south of Tunisia for potable water production and irrigation. Several tests on stor- age, evaporation, and condensation were carried out, and an estimation of the cost of fresh water production was also given. The study showed that the plant, which was intended to produce 12 l/m 2 /d of fresh water, did not reach its goal. The highest production was about 6 l/m 2 /d, which is only marginally higher than that of an efficient single-basin still. doi:10.1016/j.desal.2008.02.019 .