Performance evaluation of two stage indirect/direct evaporative cooler with alternative shapes and cooling media in direct stage

Two stage indirect/direct evaporative cooler with wet surface plate heat exchanger type indirect stage and different shapes and cooling media in direct stage is fabricated and tested. Rectangular, semicylindrical and semihexagonal shaped cooling pads made up of wood wool, rigid cellulose and aspen fiber are used as cooling media in direct stage. The performance was tested in direct cooling mode and combined cooling mode for constant secondary air flow rate of about 1 kg/s and primary air flow rate varying between 0.078 and to 1.011 kg/s. Average inlet dry bulb temperature was varying between 39°C and 43°C and relative humidity between 37% and 46%.The results show that saturation efficiency of direct evaporative cooler varies in the range of 98.3% to 71.9%. Overall efficiency of the unit varies in the range of 119.5% to 74.3% and outlet temperature of air between 27.3°C and 32.4°C. The cooling capacities in direct cooling mode range between 3240 and 45427 kJ/h and that for combined mode range between 4679 and 43771 kJ/h for different combinations. Such a cooler would be beneficial than standalone direct or indirect systems.