Effects of fiber bundle nonuniformity on dehumidification performance and energy efficiency of pressure-driven membrane modules

The physical permeation-based membrane dehumidification technology has excellent energy-saving capacity. The nonuniformity of fiber bundles affects largely the flow status in the shell side of pressure-driven membrane modules, and therefore the dehumidification performance and energy efficiency of the membrane system. To explore the effects of fibre bundles nonuniformity, three-dimensional membrane dehumidification models with different fiber arrangements and filling rates were developed. The friction coefficient, dehumidification rate and energy efficiency of the membrane system were discussed for the comprehensive evaluation of module performance. It is found that the dehumidification rate of regular configuration is slightly better than that of random configuration, but the advantage is gradually weakened with the increase in filling rate. The obtained inversely proportional fitting function of f = 58.81/Re can be used to predict the flow resistance in the fiber lumen. Under the same air parameters, operating conditions and fiber size, the fiber distribution has a negligible effect on the dehumidification COP. The dehumidification rate rises significantly with the filling rate, up to 94.88% at a 47% filling rate accompanied by the maximum flow resistance. The dimensionless analysis indicates that the membrane module with a filling rate of 21.5% similar to 23% would achieve optimal performance in terms of system energy efficiency and overall dehumidification capacity.