Parametric study of the energy efficiency of the HDH desalination unit integrated with nanofluid-based solar collector

Abstract

Humidification–dehumidification desalination (HDH) systems have been found to be ideal for treating seawater at a smaller scale. It requires thermal energy to drive the processes inside the HDH system which can be supplied by a renewable source of energy (such as solar energy). For this purpose, a nanofluid-based direct absorption solar collector (DASC) can be used which has a relatively higher thermal efficiency, as compared to the conventional surface absorption-based solar thermal collector. In this study, these two sub-systems—HDH and DASC, are coupled through a heat exchanger. In this paper, a numerical model has been prepared for DASC-based HDH system which aims to evaluate the energy efficiency of this combined system by calculating gained output ratio as a function of various parameters, related to the DASC, such as particle volume fraction (fv), height (H) and length (L) of the collector, mass flow rate of nanofluid inside the collector ðm_ nfÞ and amount of solar energy incident (q) on the collector. The performance of the combined or integrated system has also been verified against the various parameters related to HDH system such as ratio of mass flow rate of the saline water to the dry air ðm_ w=m_ daÞ, effectiveness of the humidifier (eH) and dehumidifier (eD) and the bottom temperature ðTw1 Þ. Also the results of the numerical model prepared in this study have been compared with those available in the literature. Finally, the applicability and benefits of using nanofluids in various thermal desalination techniques have been presented.