Novel designs for improving the performance of hollow fiber membrane distillation modules
Fane, Anthony Gordon
Date of Issue2011
School of Civil and Environmental Engineering
Singapore Membrane Technology Centre
Five types of novel hollow ﬁber module conﬁgurations with structured-straight ﬁbers, curly ﬁbers, central-tubing for feeding, spacer-wrapped and spacer-knitted ﬁbers, have been designed and constructed for the direct contact membrane distillation (DCMD) process. Their module performances were evaluated based on permeation ﬂux experiments, ﬂuid dynamics studies, and tracer-response tests for ﬂow distribution as well as process heat transfer analysis. The novel designs showed ﬂux enhancement from 53% to 92% compared to the conventional module, and the spacer-knitted module had the best performance. The ﬂuxes of all the modiﬁed conﬁgurations, except the structured-straight module, were independent of the feed ﬂow velocity, and the modules with undulating membrane surfaces (curly and spacer-knitted ﬁbers) were able to achieve more than 300% ﬂux improvement in the laminar ﬂow regime. The improved performance was attributed to the improved ﬁber geometries or arrangements that can provide effective boundary layer surface renewal and more uniform ﬂow distribution, conﬁrmed by the sodium chloride tracer response measurements. The heat transfer analysis underscores the advantage of the module with curly ﬁbers with the least temperature polarization effect (temperature polarization coefﬁcient = 0.81–0.65 at Tm= 303–333 K), which is favorable for enhancing permeation ﬂux.
DRNTU::Engineering::Environmental engineering::Water treatment
Journal of membrane science
© 2011 Elsevier. This is the author created version of a work that has been peer reviewed and accepted for publication by Journal of Membrane Science, Elsevier B.V. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [DOI: http://dx.doi.org/10.1016/j.memsci.2011.09.007].