Comparisons of the systems with three different condensers were made at a constant condensing temperature of 40 C°. This is the temperature at which three systems can operate at moderate pressures and offer a broad range of comparable results. Constant condensing temperature was maintained by adjustment of either water or airflow rates and varying the evaporator heat input to the desired value. During the experiments, dry bulb and wet bulb temperatures of the air at the inlet of the cooling tower, the evaporative condenser and the air-cooled condenser were kept at 22.5±0.3C° and 19.5±0.3C°, respectively. Steady-state conditions were assumed to reach when changes in temperature and pressure at the key points of the unit had ceased. It was accepted that when temperature deviations at the points considered were lower than 0.3C° for 10 minutes, the steady state was achieved. The units were usually brought to steady state within 20 min after input conditions were changed. As soon as stabilized conditions were occurred, data were collected to analyse the performance of the unit tested.