Experimental study on liquid-gas phase separation driven by pressure gradient in transport membrane condenser

Flue gas moisture recovery from coal-fired power plants has always been an important topic in the fields of energy and building and gas dehumidification. Moisture and waste heat recovery in a transport membrane condenser (TMC) involves heat transfer, mass transfer and intermolecular interactions. This study, an experiment was designed based on TMC, which revealed the process of vapor condensation on the membrane surface and mass transfer across the membrane, and clarified the driving mechanism of mass transfer. It is found that the main driving force affecting the mass transfer is related to the recovery mechanism and the flowing working fluid. The main driving force influencing mass transfer on the flue gas side is the pressure gradient caused by the vapor pressure difference, whereas on the condensation side, mass transfer is influenced through the heat transfer gradient. Furthermore, high vacuum levels on the permeate side may enhance gas cross-membrane transport, but do not improve mass transfer performance. Compared with a longitudinal spacing of 30 mm, the condensation mass transfer rate of TMC with a longitudinal spacing of 80 mm increased by 107%-174%. The research results have an important role in promoting the realization of resource recovery and energy efficiency.