Energy, exergy, economic and ecological analyses of a diurnal radiative water cooler

Abstract

The increase in energy demand for water cooling in nearby future encourages the use of metamaterial-based passive radiative water cooler, which has application potential in a highly-populated country like India. However, an energy-exergy-economic feasibility study with the best tube design is essential before implementation due to climatic diversity, but not yet been studied. Hence, this paper deals with the analysis of the passive radiative water cooler and the study of its performance with respect to the variable water mass flow rate and water tube geometry. The research presents the monthly variation of cooling performance, cooler efficiency and COP concerning Indian cities of different climatic conditions. The study also carries out exergy, economic and ecological analyses and proposes a new exergy model. Results reveal that the cooling performance is low for humid climate as compared to arid climate. For a total cooling panel area of 10.75 m2 and water flow rate of 0.03 kg/s, a maximum water temperature drop of 3.63 °C with an associated cooling capacity of 42.46 W/m2 is obtained at Jaisalmer in October (arid climate). The least performance is obtained at Chennai in May (humid climate). Results also reveal that the semicircular channel increases temperature drop and cooling capacity by 15.8% and 14.8%, respectively, over the circular channel. Exergy analysis shows very high entropy generation and hence very low exergy efficiency for radiative cooling. The use of the radiative cooler over the electric cooler produces a maximum annual operational cost saving of 19.25% and carbon dioxide mitigation of 1.987 kg.