Distillate flux enhancement of the concentric circular direct contact membrane distillation module with spiral wired flow channel

The modeling equations for predicting distillate flux in the direct contact membrane distillation (DCMD) module with embedded spiral wire of various spiral wire pitches in concentric circular module were developed theoretically and verified experimentally. The temperature distributions, distillate flux and energy consumption of both concurrent- and countercurrent-flow operations were presented with the volumetric flow rate, inlet saline temperature, the spiral wire as parameters, and the experimental data was incorporated into the modeling equations to validate the theoretical predictions. A description of the average Nusselt number was made to evolve a correlating equation of heat transfer coefficients incorporating distillate flux and Reynolds numbers with the use of experimental data. The effects of operating and design parameters such as flow rate, inlet saline temperature and spiral wire pitch on the pure water productivity and power consumption under both concurrent- and countercurrent-flow operations were also analyzed. © 2017 Taiwan Institute of Chemical Engineers