Comprehensive simulation of flat-sheet membrane element performance in steady state desalination

Abstract This study is a step towards the development of a comprehensive computational tool, simulating in detail the performance of Spiral Wound Membrane modules, presently unavailable. The development of a detailed two-dimensional model is reported herein, for flat-sheet membrane modules, by incorporating small length-scale CFD results at the retentate side and accounting for permeate compartment variables. By considering the interacting (through the semi-permeable membrane) flow fields at these two compartments, the model simulates the steady-state desalination under constant space-averaged permeate recovery. Aided by analysis of the mechanisms involved and by appropriate non-dimensionalization of the governing equations, efficient numerical techniques are adapted, leading to the development of a general purpose computational tool. The distribution of all key process parameters (at both flow compartments, throughout the membrane envelop) can be predicted, as a function of the membrane sheet and the spacers geometrical characteristics; thus the new simulator is most appropriate for module design optimization, parametric studies and other applications. The new algorithm is very efficient from the computational point of view. The features and capabilities of this advanced simulator are demonstrated by presenting several detailed results of operating parameters, focusing on the two-dimensional aspects of the problem.