This study proposes modeling techniques for predicting distillate flux in a double-unit air gap
membrane distillation (DUAGMD) module. The prediction is validated by experimental results
by inserting S-ribs carbon-fiber spacers acting as an eddy promoter. A more compact double-unit
device implementing S-ribs carbon-fiber spacers could increase the membrane stability to prevent
flow-induced vibration and also enhance the production rate by suppressing temperature
polarization on the membrane surface. The new design achieves a considerable pure water
productivity by inserting S-ribs carbon-fiber spacers in the saline feed channel compared to
an empty channel and the single unit module. The formulated Nusselt numbers are regressed
with experimental data to predict the heat transfer coefficient of the DUAGMD module for both
S-ribs carbon-fiber filled and empty channels. This study contributes to summarizing the effects
of volumetric flow rate, saline feed temperature, and S-ribs types on the permeate flux. Besides
analyzing the permeate flux enhancement, this study compares the energy consumption increment
caused by the S-ribs carbon-fiber filled design with the permeate flux increment. A nice
consistency between the experimental results and theoretical predictions has shown that the
proposed model could predict AGMD system’s design and optimize the operation parameters.
