Computational fluid dynamics investigation on indirect contact freeze desalination

Abstract

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 35g/L concentration in a container. A freezing temperature of 260K was applied at the container base using a Peltier device for 30min. 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 ±0.495K. 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.