Numerical Simulation Study on the Mass and Heat Transfer in the Self-Heating Membrane Distillation Process

The self-heating membrane distillation (SHMD) process can achieve highly efficient membrane distillation due to local heating. However, limited by the observation methods, there are fewer research studies on the heat and mass transfer process in the SHMD. In this work, a two-dimensional (2D) computational fluid dynamic model coupling flow, thermal transfer, and vapor transport was developed. It revealed that the difference between the photothermal and Joule-heating membrane distillation (MD) was due to the different heat source positions. The water productivity first increased and then decreased in the feed linear velocity range of 1.25 × 10^-6to 1.25 × 10^-1m s^-1, which resulted from the comprehensive influence of temperature and salt concentration. In addition, the thermal efficiency was improved with increasing the input power due to the thermal concentration enhancement and the nonlinear relationship between the vapor and temperature. This work revealed the influence of temperature and salt concentration polarization in the SHMD, which can help to further improve the design of this process.