Dynamic performance of an evaporative cooling pad investigated in a wind tunnel for application in hot and arid climate

Evaporative cooling pad are widely used in poultry production houses in hot and arid climate to provide an appropriate indoor thermal conditions for animals. Currently, the main challenge of this system is to maintain the indoor thermal conditions stable so that the productivity is ensured. This study used wind tunnel measurements to investigate the dynamic performance of evaporative cooling pad under different control strategies including altering water supply duration which was defined as pump-on time (ranging from 3 s to 120 s) and control time cycle (3, 4 and 5 min), which was defined as the sum of pump-on and pump-off time in a cycle. A cross-fluted design of impregnated cellulose pad with dimensions of 1.8 m × 0.6 m × 0.15 m (height × length × thickness) was used and constant water flowrate of 7.5 l min−1 is applied. The results indicated that periodic pattern of temperature and cooling efficiency was observed due to the setting of pump-on time. Larger variation in air temperature difference between inlet and outlet of evaporative cooling pad occurred when the control time cycle was longer and face air speed was bigger. Supplying water to the pad caused higher resistance to the air travelling through the pad. A relationship was presented between cooling efficiency and a ratio defined by pump-on time, water flow rate, control time cycle and air flow rate. The ratio of water to air can be implemented by the controller.