Theoretical and experimental study of direct contact membrane distillation

Isam Janajreh, Dana Suwwan, Raed Hashaikeh

Research output: Contribution to journalArticlepeer-review

Abstract

Direct contact membrane distillation (DCMD) is characterized as a low-thermal energy process, involving evaporation and a phase change driven by the pressure difference between two fluid channels separated by a hydrophobic membrane. The temperature difference creates a driving pressure between the hot channel (feed) and the cold channel (permeate). This paper demonstrates the performance of the DCMD through high fidelity simulation and experimental observation to reveal a fundamental and qualitative understanding of the spatial distribution of the temperature, mass flux, and heat flux as well as the temperature polarization. The flow model is governed by the Navier–Stokes equations of non-isothermal fluid coupled with the energy equation for the two adjacent channel flow and the middle hydrophobic and porous membrane. The experimental study involved the development of a transparent acrylic DCMD unit operated by two peristaltic pumps where each cycles the feed and the permeate from the corresponding reservoir through the DCMD chambers that are separated by the PVDF–HFP membrane. The hot feed reservoir temperature is maintained at 40°C (4% salinity), whereas the permeate reservoir temperature is kept at 25°C (0% salinity). The system is tested using membranes of prescribed thickness, porosity, and conductivity. The model and experimental results were compared in counterflow configurations and a good agreement between the model and experimental was obtained for temperature distributions, mass flux, and temperature polarization coefficient (TPC). The system metrics were obtained for the DCMD showing a suitable TPC working range (0.3–0.55), a relatively low mass flux yield (5 kg/h m2) and a very low thermal efficiency (1.5%). These results suggest there is still a large potential in DCMD to enhance its overall yield in order to speed up their large-scale commercialization.

Original languageEnglish (US)
Pages (from-to)15660-15675
Number of pages16
JournalDesalination and Water Treatment
Volume57
Issue number33
DOIs
StatePublished - Jul 14 2016

Keywords

  • Heat transfer
  • Hydrophobic
  • Mass transfer
  • Temperature polarization coefficient (TPC)

ASJC Scopus subject areas

  • Water Science and Technology
  • Ocean Engineering
  • Pollution

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