Parametric Studies on a Two-Stage Evaporative Cooler During Tropical Climates in India

Abstract

This research study aims to work out the best possible performance parameters for a two-stage direct–indirect evaporative cooler (IDEC) when it is operated in Indian climatic conditions. A numerical simulation model has been developed to estimate temperature, relative humidity, cooling capacity, and saturation efficiency for a direct evaporative cooler (DEC), when it is operated during hot and humid and hot and less humid conditions in Chennai city. Simulation results have been corroborated with those obtained from experiments. Simulation techniques have also been extended for a fin and tube heat exchanger, which acts as IDEC. Both DEC and IDEC are combined and developed into a two-stage evaporative cooler in which performance studies have been carried out. Performance parameters are optimized for all three modes of evaporative cooling. These studies reveal that the DEC system with optimized parameters has a better approach to wet bulb temperature (WBT). Hence, cooling effectiveness of DEC depends on the ambient air WBT of Indian localities. IDEC systems perform better in places where ambient air WBT is less, either hot and less humid or hot and dry climates. Two-stage evaporative cooling is the preferred technique for Chennai weather when compared with direct and indirect cooling methods. In this cooler, spray water temperature approaches the WBT of IDEC cooled air, whereas it is reduced well below ambient air WBT and approaches ambient air dew point temperature. Also, when ambient air is cooled in this new cooler, dry bulb temperature (DBT) of IDEC cooled air can be reduced below ambient air WBT.