Exergy analysis of two indirect evaporative cooling experimental prototypes

This paper deals with the exergy analysis of two experimental prototypes consisting of indirect evaporative cooling systems with different constructive characteristics. Both prototypes have been designed and manufactured in the Thermal Engineering Laboratory of the University of Valladolid. They are made of polycarbonate hollow panels of different cross section and connected into a heat recovery cycle. Each prototype has been tested at 4 levels of outdoor air volume flow (from 125 to 400 m3·h−1) and 4 levels of dry bulb temperature (from 25 to 40 °C). For each of the 16 different operating conditions the exergy destructed by each prototype has been calculated. Results show that the higher the dry bulb temperature at the primary air inlet, the higher the exergy destruction and the exergy losses. The exergy destruction increases when the wet bulb depression temperature of the secondary air inlet decreases, leading to more inefficient configurations. The value of the exergetic efficiency is in the order of 2–12 %. The optimum combination of operating conditions at any inlet temperature of the primary air can be proposed as: 300 m3h−1 and 200 m3h−1. for the wide and narrow plates prototype, respectively.