Computational fluid dynamics investigation on indirect contact freeze desalination

With the global increasing demand for fresh water, desalination of sea water is regarded as a potential solution to provide for potable water shortages. Freeze desalination offers the advantage of lower energy consumption, since the latent heat of fusion is approximately one-seventh that of the latent heat of vaporisation. CFD is a powerful technique that enables the effective analysis and investigation of thermodynamic processes. ANSYS Fluent software was used to develop a 3D CFD model of the freeze desalination process using species transport, solidification/melting and energy modules. This CFD model was then validated by conducting experiments using salt water of 35 g/L concentration in a container. A freezing temperature of 260 K was applied at the container base using a Peltier device for 30 min. The measured ice salinities from the experimental work and those predicted from CFD simulations were compared showing a percentage deviation of 2.10. The salt water temperatures were also compared from the experimental work and CFD simulations, giving an average deviation of 0.495 K. The developed CFD model has been used to carry out parametric analysis to predict the effects of freezing temperature, solution salinity and the direction of freezing; on the freezing time, ice production and its salinity.