Experimental evaluation of bulk charcoal pad configuration on evaporative cooling effectiveness

Abstract

The purpose of the study was to evaluate the performance of bulk charcoal pad configuration, experimentally. For this, a number of experiments have been conducted in a wind tunnel in order to evaluate the pressure drop, cooling efficiency and specific water consumption as a function of air velocity, water flow rate and pad configuration. The test were carried out at six levels of air velocity (0.12, 0.51, 0.82, 1.05, 1.10 and 1.14 m s^-1), three water flow rates (2.2, 3.2 and 5.2 l min^-1) and three pad configurations: single layer pad (SLP), double layer pad (DLP) and triple layer pad (TLP) made out of small and large size charcoal particle of equivalent diameter 30 mm and 50 mm respectively. It was found that pressure drop range of small size charcoal pads is 2.67 to 240.00 Pa while that of pads made out of large size charcoal are much lower with the range of 2.00 to 173.33 Pa, depending on the pad configuration, air velocity and water flow rate. The cooling efficiencies of the small size charcoal pads vary from 56.71 to 96.10% while the cooling efficiencies of large size charcoal pads are 45.41 to 90.06%, depending on the pad configuration, air velocity and the water flow rate. Generally, DLP and TLP configuration with larger wet surface area provide high cooling efficiencies and high pressure drops, though it obviously leads to increase in water consumption.  DLP and TLP configurations at low air velocity is therefore recommended for practical applications.