Effect of non-woven net spacer on a direct contact membrane distillation performance: Experimental and theoretical studies

Abstract
This study provides a comprehensive and systematic overview of the fundamental characteristics of heat and mass transfer in the direct contact membrane distillation (DCMD) process that employs different types of spacers on one or both surfaces of the membrane. Detailed theoretical investigations were carried out to demonstrate the effects of spacers adjacent to the membrane surface on heat and mass transfer enhancement in the DCMD with a PTFE/PP composite membrane, complemented with experimental data for model validation. Thus, this work aimed to propose and demonstrate the heat transfer correlation for spacer-filled channels to reliably predict the heat and mass transfer improvement by non-woven net spacers in the DCMD process. The results showed that the permeate flux enhancement by the spacers ranged between 7% and 19% only for the spacer-filled permeate channels and between 21% and 33% only for the spacer-filled feed channels even at higher flow rates, thus indicating lower flux enhancements in the spacer-filled permeate channels. This was because the influence of spacers on flux improvement became more evident at higher temperatures owing to higher temperature polarization. In this study, the maximum flux enhancement of approximately 43% over the empty channels was achieved using the thinnest and densest spacer with a hydrodynamic angle of 90°, adjacent to both membrane surfaces.

Citation
Kim Y-D, Francis L, Lee J-G, Ham M-G, Ghaffour N (2018) Effect of non-woven net spacer on a direct contact membrane distillation performance: Experimental and theoretical studies. Journal of Membrane Science 564: 193–203. Available: http://dx.doi.org/10.1016/j.memsci.2018.07.019.

Acknowledgements
This study was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2017R1D1A1B03035821) and by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) funded by the Ministry of Trade, Industry and Energy (MOTIE) of the Republic of Korea (No. 20174010201310).

Publisher
Elsevier BV

Journal
Journal of Membrane Science

DOI
10.1016/j.memsci.2018.07.019

Additional Links
https://www.sciencedirect.com/science/article/pii/S0376738818313449

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