Towards the technological maturity of membrane distillation: the MD module performance curve

Membrane distillation (MD) is constantly acknowledged in the research literature as a promising technology for the future of desalination, with an increasing number of studies reported year after year. However, real MD applications still lag behind with only a few pilot-plant tests worldwide. The lack of technology transfer from academia to industry is caused by important gaps between its fundamental basis and the process design. Herein, we explore critical disconnections by conducting coupled mass and heat transfer modeling and MD simulations; we use well-known MD mass and heat transfer equations to model and simulate flux over a typical MD membrane for different geometries, areas, and operational conditions in direct contact configuration. From the analysis of the results, we propose research guidelines and process development strategies, and construct an MD module performance curve. From this graph, permeate flow rate, thermal energy consumption and outlet temperatures can be determined for given feed inlet conditions (temperature and concentration). Comprehensive tools such as this MD module curve and good communication between membrane developers and process engineers are required to accelerate the process of bringing the MD technology from a still-emerging status to a maturity level.