in the figure attached the desalination system does not operate on a continuous basis, but a force is applied to the diaphragm to induce pressure on the saline water.
i want to know the minimum force (pressure) to produce fresh water, i know that it depends on the membrane, so select a type and till me a number.
thanks
Dear Ibrahim, the concept that you mention resembles to that of reverse osmosis. Thus, the required pressure depends on the osmotic pressure of your saline solution which in turn depends on the molarities of the dissolved solutes (salts) (check literature for such calculations or use the online osmotic pressure calculator by LENNTECH: http://www.lenntech.com/calculators/osmotic/osmotic-pressure.htm). It is understood that the osmotic pressure gives you only an indication about the operational pressure of a reverse osmosis system. Normally the applied pressure is much higher than the osmotic pressure, depending on the membrane used and the required permeate flux.
Dear Ibrahim,
Referring to water desalination by membrane reverse osmosis, as said before, the operating pressure should be larger than he osmotic value.
For sea water the osmotic pressure is ca. 25 bar and the required prssure to treat this stream could be of ca. 50 bar.
but here, there is no osotic pressure aas there no fresh water touching the membrane on the lower side.
suppose that the fresh water droplets are collected in a pan.
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