American Journal of Energy Research, 2013, Vol. 1, No. 1, 1-6 Available online at http://pubs.sciepub.com/ajer/1/1/1 © Science and Education Publishing DOI:10.12691/ajer-1-1-1 Experimental Analysis of the Performance of a Mechanical Geothermal Water Cooling Tower in South Tunisia M.T. Chaibi 1,* , K. Bourouni 2 , M.M. Bassem 3 1 Institut National de Recherche en Génie Rural EauxetForets, Ariana, Tunisia 2 EcoleNationaled‟Ingénieurs de Tunis, LeBelvédère, Tunisia 3 Centre de Recherche des Technologies de l‟Energie de Borj-Cedria, HammamLif, Tunisia *Corresponding author: chaibi.medthameur@iresa.agrinet.tn Received December 20, 2012; Revised February 01, 2013; Accepted February 26, 2013 Abstract The paper reports the results of pilot test on the cooling performance of a direct cross flow mechanical cooling tower located in the Kebili region in the southern part of Tunisia. In this study heat and mass transfer data are measured within the tower over a period of one year and compared with external weather data collected over the same period. The data enabled the influence of different weather conditions on the performance of the cooling tower to be analyzed. The results obtained show that ambient humidity has a greater influence on performance than external temperature. In fact, significantly better cooling performance of about 80% was obtained during the high temperature, low humidity summer months than during the winter period, less than 40%, with relatively low external temperature and high humidity. These results indicate the relative importance of evaporative cooling as compared to convective cooling. The effect of wind on cooling performance was found to be considerable but was confined to those periods when wind direction coincided with the orientation of the louvers of the tower. This was observed to occur only during the summer period when compared to winter period, thus attesting the benefits of the use of proper cooling tower design for improving efficiency and conserve energy. Keywords: mechanical cooling tower, cross flow, cooling efficiency, evaporative cooling, convective cooling, geothermal water, south Tunisia 1. Introduction 1.1. Background Geothermal water resources, in the continental Intercallaire CI, extend over an area of 600000km 2 in the region of Algeria, Libya and Tunisia. The small part localized in Tunisia is distinguished by an aquifer of more than 100m depth with high pressure of 10 bars and temperature reaching 70°C. The geothermal water resources have been estimated for 550Mm 3 with TDS from 2.5 to 5g/l [1]. The use of geothermal water in Tunisia goes back to ancient times. Originally used for therapeutic purposes, geothermal water is currently used for heating greenhouses and, in the absence of other sources of water, for general agricultural use. Direct application of geothermal water to crops generally results in extensive damage to foliage. The need to avoid crop damage in areas where high temperature geothermal water is the only practical source of irrigation water has led to the use of cooling towers to lower the temperature of the geothermal water to less than 30°C level where it can be applied safely directly onto crops. Construction of the first generation of cooling towers began in the 1960‟s with the first unit being built at El Kebayett in south-eastern Tunisia. During the 1980‟s improved thermal efficiency was achieved through the use of mechanical draft cooling and designs using this method were rapidly adopted (Figure 1). Many of the towers currently operating in the region use the cross flow induced draft system to cool the water. The main problem with the various types of mechanical draft cooling tower is the cost of the electricity needed to run the cooling process. In consequence, we see from the mid 1990‟s a new generation of cooling systems being constructed. This new generation seeks to improve energy efficiency by employing a range of different designs such as spiral, cascade, multiple ponds, etc. The factors affecting the performance of existing cooling towers have been identified on the basis of a number of empirical studies. However, the way in which these factors inter-act to determine the overall performance of the tower is not well understood. In the absence of an adequate model which can be used to represent the operation of a particular design, the performance characteristics of any tower can only be ascertained experimentally with the results being presented in form of correlations [2]. These correlations are function of the inlet and exit air wet bulb temperature and the inlet and exit water temperature. The system can