Investigating the prospects of water desalination using a thermal water pump coupled with reverse osmosis membrane

This paper presents the design and experimental analysis of a thermal water pump coupled with a reverse osmosis desalination membrane. The operation, thermodynamic cycle and design of the proposed system are explained with the aid of system schematics and thermodynamic process diagrams, while the experimental performance of the thermal water pump in combination with a reverse osmosis membrane is presented and discussed. It is shown that for feed water at a salt concentration of 1184 ppm and a heat source temperature of 86 °C, the proposed system is shown to be able to produce fresh water at a rate of 1.27 L/h with a specific energy consumption of 165 MJ/m3. The recovery ratio obtained under these conditions is shown to be 26%. The performance and characteristics of the proposed system are contrasted with data for existing multi-stage thermal desalination systems as well as Rankine cycle-reverse osmosis desalination systems and it is shown to compare favourably to both for low salinity applications.