Feasibility study of a new two-stage low temperature desalination process

This paper presents the preliminary field test data of a two-stage low temperature phase-change desalination process. The process under development operates at low temperatures and low pressures generated by local barometric head. A two-stage configuration of this process was developed and tested at a field site in the Puget Sound bay area of the State of Washington. The field test results proved that the two-stage desalination process has potential for standalone small to large scale applications in water and energy scarce rural areas with specific energy consumption of 1500 kJ/kg of freshwater. Economical analysis conducted on the desalination system results in desalination costs around $3/m3 using a cheap waste heat source purchased at $0.5/GJ. Since, most small scale domestic desalination systems are designed in combination with a renewable energy source; when this desalination system is powered by a low grade flat plate solar collector heat source, the desalination costs are less than $7/m3 which falls in acceptable range for small scale desalination systems of similar capacity.

► Feasibility of a new 2-stage low temperature desalination process was investigated.
► Low temperature evaporation was caused by natural vacuum generation in the process.
► Technical performance and energy recovery options of the process were presented.
► Economic analysis shows that the freshwater from this process costs around $3–7/m3.
► The process saves mechanical energy and competitive to other desalination processes.