Energy analysis of a stepped cascade solar still connected to photovoltaic thermal collector

Abstract

In this paper, the performance evaluation of a stepped cascade solar still connected to photovoltaic thermal (PV/T) collector was carried out. The governing equations of problem was a set of initial value ordinary differential equations which were obtained by
writing energy balance for the various components of solar still system (i.e. glass cover, brackish water, absorber plate, and PV/T collector). The numerical model of problem was solved by the 4th-order Runge-Kutta method under real climatic conditions sample. The validation of numerical model was carried out by the experimental data of previous literature. Parametric studies showed that the energy efficiency of stepped cascade solar still maximised in the desired brackish water flow of 0.03 kg/min and the PV/T collector
area of 1.3 m². The daily energy efficiency and accumulated freshwater were about 26% and 5.71 kg/(m².day), respectively. An increase of about 20% was obtained in freshwater productivity by the connection of PV/T collector to the stepped cascade solar still. Also,
PV/T collector, in addition to providing pumping power, can supply electrical power of about 0.918 kW/day for other uses. In order to produce freshwater during the night time, the usage of the phase change materials below the absorber plate was suggested.