Numerical investigation of a multi-stage solar still under Batna climatic conditions: Effect of radiation term on mass and heat energy balances

Design using SOLIDWORKS software followed by numerical investigations and economic analysis are carried out to examine a detailed description of a multi-stage distillation system, known by its significant ability to distil saline water. The aim is to weight the feasibility and opportunity of such device in our semi-arid region (Batna city), in order to promote an academic prototype and hence launch production project as startup linked to our laboratory. Therefore, the geometrical configuration involved in this work is conceived on the basis of literature survey especially experimental researches. Furthermore, an analysis has been performed to reach a well zero dimensional (0D) adapted mathematical model based on mass and energy balance as a first step, before launching tridimensional (3D) CFD study under ANSYS-FLUENT software. In this situation, a computer code in FORTRAN language has been elaborated to treat both the explicit effect of thermal radiation term σAsε(Ts4−Tc4) on temperature and distillate mass productivity, and then the performance of such system in Batna climate conditions (a graphical interface was created to plot and to analysis all quantity especially solar radiation). After a thorough assessment, it is shown that the order of magnitude of the radiation term is 3.23% in the hot stage, which represents a low contribution in energy balance equations. On other hand, the curves tendencies of the main fields and the amount of the day mass production are encouraging and show a good agreement with available literature.