||Modeling equations for predicting distillate flow in the Water Gap Membrane Distillation (WGMD) module are theoretically and experimentally established. In this module, the thickness of the water gap is added to the design, the metal mesh with different hole sizes is added to the water gap, and the flux change when placed in different positions is discussed. Compared with AGMD, adding water gap can effectively improve the heat transfer efficiency. Compared with DCMD, the flux efficiency is weaker due to the difference between forced convection and natural convection.
Through the calculation of Nusselt and Rayleigh number, it can be confirmed that the main heat conduction effect of the water gap distillation system(WGMD) is mainly natural convection and conduction in the gap.