The choice of an appropriate flow field distributor is crucial to circumvent mass and charge transfer resistance-related issues in proton exchange membrane fuel cells (PEMFCs). In this work, incorporating all the anisotropic nature of the gas diffusion layers (GDLs), a three-dimensional, multiphase CFD model is built to perform a comparative study of several types of cathode flow field designs. Three conventional (i.e. parallel, serpentine and interdigitated) and two recently-introduced (i.e. parallel with blocks and the metal foam) flow field designs were considered for the cathode side. The results showed that the best fuel cell performance is obtained with the metal foam flow field as it induces the lowest water saturation, the lowest values and more uniform distribution of current density and temperature as well as relatively medium pressure drop. Compared with the parallel flow field case, the peak power density increases by about 50% when using the metal foam flow field and by about 10% when using the other three investigated flow fields (i.e. serpentine, interdigitated and parallel with blocks). The parametric analysis reveals that the metal foam outperforms other designs at intermediate and high humidity conditions whereas the interdigitated flow field design outperforms other designs at low humidity conditions.

No abstract

No abstract

The emergence of biomimetic materials developed using nature's inspiration and biological domains can drive a paradigm shift in the design and operation of future‐generation materials in separation applications. In recent years, biomimetic membranes have drawn interest of many researchers for water treatment applications. Among the biomimetic membranes, protein‐based membranes, specifically those synthesized by aquaporin, have received much attention in recent years due to their high osmotic water permeability and excellent ability to remove small molecules, thereby overcoming the trade‐off between the water flux and the contaminant's rejection. The separation efficiency and fouling properties are significantly improved by taking advantage of the strategies evolved in nature. This review provides a comprehensive overview of the state‐of‐the‐art aquaporin‐based biomimetic membranes (ABMs), mainly focusing on their synthesis, characterization, and performance as selective layer in composite membranes for reverse osmosis, nanofiltration, and forward osmosis for water desalination. Fabrication methods and characterization techniques of ABMs and their performance in water desalination are also reviewed, while the main obstacles for their successful commercial viability in wastewater treatment are provided. The applications of ABMs in various separation processes other than water desalination and their potential market are presented to inspire future researchers in this versatile area.

Mesh independence analysis is one of the most crucial steps in any CFD problem. The aim of this study was to investigate the most commonly used variables employed for grid independency studies in a typical PEMFC and to find possibly the most effective variables that may be decisive in a PEMFC grid independence test. Herein, a three-dimensional (3-D), steady state, non-isothermal computational fluid dynamics (CFD) model of a serpentine channel proton exchange membrane fuel cell (PEMFC) was developed. The present model includes various conservation equations that are dominant in a typical PEMFC: the mass, momentum, species, charge, and energy equations, which are coupled with the electrochemical model. The numerical results indicate that much more care should be taken while obtaining a mesh independence solution for CFD studies in PEMFC systems. Based on our findings in this study, it was demonstrated that employment of merely the polarization curve (current-voltage), especially only in a given specific point, was not sufficient to carry out the mesh independence tests for CFD studies in PEMFCs. In addition, it was observed that the average volumetric hydrogen concentration inside the catalyst layer on the anode side has a more significant role to check the grid independency tests.

No abstract

No abstract

No abstract