Desalination Project

Written by Vijay K. Dhir

There is a worldwide scarcity of potable water. Desalination of abundantly available seawater especially in coastal areas offers a viable option for conversion of seawater into fresh water. As such a number of schemes for desalination of water have been developed over the last several decades. However, most of these processes are energy intensive that increases the cost of production of potable water. Thermal processes based on flash evaporation of water to create water vapor that is eventually condensed to produce potable water are attractive as they can employ solar energy, geothermal energy and waste heat. 

Here we propose a novel method that is dynamic and that combines both evaporation and phase separation for subsequent condensation of vapor to produce potable water. In this approach heated water, for example, from a solar pond or another source flows through injection passages and is discharged into a larger tube with tangential injection. During flow through the injector passages liquid pressure drops, liquid becomes superheated and flashes with formation of vapor bubbles in the bulk and on the walls of injectore passages. Tangential motion of the exiting two phase mixture into a large tube creates centrifugal force that pushes liquid to the outside whereas vapor moves to the middle to form a vapor core (see Fig. 1). Vapor is removed from the vapor core and goes to a condenser to produce potable water. The separated water goes back to the solar pond to be reheated.

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