Porous condenser for thermally driven membrane processes: Gravity-independent operation

• Porous condenser for thermally driven membrane processes was proposed.
• Gravity-independent operation of membrane module with porous condenser was proven.
• The concept was demonstrated for two applications: water desalination and removal of butanol from its solution in water.

New thermally driven processes configuration based on the porous condenser (instead of non-porous cooling plate) and using permeate as a coolant was suggested and successfully proven for two processes: (i) membrane distillation with porous condenser (MD-PC) tested for the desalination of model NaCl solutions of 5–40 g/l and (ii) thermopervaporation with porous condenser (TPV-PC) tested for the removal of n-butanol from its 1 wt.% aqueous solution. In both cases, the experiments were carried out at different orientations of the membrane module. No noticeable difference for MD-PC and TPV-PC performance, including the worst case scenario for conventional AGMD when the membrane was located horizontally under the air gap, was observed. In addition, in contrast to the conventional AGMD, stable MD-PC, and TPV-PC performance was demonstrated at extremely low air gap width of 0.1–1 mm. The water fluxes up to 21 kg/m2 h and salt rejection higher than 99% were attained for MD-PC, and the total flux of 1 kg/m2 h for TPV-PC separation of 1 wt.% butanol-water mixture was obtained which is comparable with the conventional vacuum PV. Potential applications for the new thermally driven processes such as space and marine can be identified.