Effect of nanoparticles on the evaporation of a salt water film

Abstract

The need for freshwater supply in different parts of the world has given great interest to the study of seawater desalination which has led to the development of various innovative techniques in this field. The present numerical study contributes to the improvement of the evaporative desalination operation by introducing nanoparticles into the base fluid. The desalination technique considered in this study consists of a saltwater film falling along the inner wall of a vertical channel heated uniformly by a constant heat flux. The equations governing the flow and the heat and mass transfer associated with the boundary and interface conditions are solved numerically using the finite difference method. We considered two values of salinity, 10 g.kg-1 and 39 g.kg-1 which correspond respectively to brackish water and sea water with different types and volume fractions of nanoparticles in order to study the effect of the combination of these parameters on the enhancement of desalination by evaporation. The results showed that the evaporation process by injecting nanoparticles into salt water improves due to its positive effect on thermophysical properties. In addition, Al2O3 is significantly better for evaporative desalination than TiO2 and copper. Moreover, we can achieve the same heat and mass transfer performance by using 2% alumina instead of 4% TiO2.

A Two-Phase Sharp-Interface Numerical Model of Falling Film Thermal Desalination in a Vertical Channel

“…They also stated that the results would be more accurate if the salt concentration equation was computationally solved in the liquid phase. Nait Alla et al [23] used a finite difference method and parabolic governing equations to study the impacts of nanoparticles on the desalination process for a falling liquid film inside a vertical channel. They concluded that adding the nanoparticles into the liquid film increased the evaporation rate due to the change in thermophysical properties.…”