Experimental investigation of energy and exergy performance of a direct evaporative cooler using a new pad type

Abstract

In this paper a comprehensive experimental parametric study on the performance of a new evaporative cooling pad type made of cellulose papers in bee-hive structure is presented. Four different pad sizes of face area 0.335 × 0.390 m2 and thicknesses 35, 70, 105, and 140 mm are examined. The tests are carried out in a wind tunnel adapted with the evaporative cooling system. Experiments are conducted to evaluate the cooling pad performance parameters: air temperature drop, air humidity ratio raise, cooling capacity, water evaporation rate, saturation efficiency, pressure drop, energy efficiency, energy efficiency ratio, exergy efficiency and overall exergy efficiency. The effects of the cooling pad thickness and the operating conditions including air velocity, inlet air temperature, water flow rate, water temperature and cooling pad thickness on the performance parameters are investigated. The results show that, the saturation efficiency, exergy efficiency and overall exergy efficiency of the proposed pad enhance with increasing the pad thickness and water flow rate and their highest obtained values are 84%, 92% and 74%, respectively. The maximum pressure drop, temperature drop and cooling capacity obtained for this pad are 46 Pa, 18 °C and 6.26 kW, respectively. Moreover, the highest energy efficiency ratio is 281 obtained at 2 m/s air velocity. Finally, new dimensionless experimental correlations for predicting the system performance parameters in terms of various operating conditions and system size are presented.