Thermal comfort based resources consumption and economic analysis of a two-stage direct-indirect evaporative cooler with diverse water to electricity tariff conditions

Abstract

For many years, investigation of impacts of variation of effective parameters on the evaporative cooling systems performance has been limited to the thermodynamic or hydraulic analyses, while economic issues, consumption of all resources together and capability of the cooler to provide thermal comfort in the ranges of variation have not been considered. In order to cover all the three above-mentioned shortcomings and provide an applicable realistic point of view from the system operation, this research is done. For a two-stage direct-indirect evaporative cooler, the impacts of variation of effective parameters on different performance criteria of the system, including each stage outlet air conditions, cooling capacity, resource consumption and their ratios, operating and initial costs are investigated while for smart selection of the variation range of the effective parameters, a novel approach based on employing thermal comfort indices is proposed. In addition, the economic analysis is done for diverse existing water to electricity tariff conditions all around the world. It is found that there is a trade-off between performance criteria when the working to inlet air ratio of the second-stage increases, so it has an optimum value. In addition, using pads with higher specific contact areas is recommended as one of the most economical strategies to enhance the system. The results also show that the best values for inlet air velocity and pad thickness area are minimum possible magnitudes. These values for this study are 0.4 m s−1 and 5 cm, respectively.