Visualization of Liquid Water Transport in a PEFC

Yang, Xiaoguang; Zhang, Fengyuan; Lubawy, A. L.; Wang, C. Y.

doi:10.1149/1.1803051

Cited by 392 publications

(271 citation statements)

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“…Visualization method is an effective way to observe the two-phase flow, which has been used for tube [15] or minichannel [16] recently. Researchers have studied the two-phase flow caused by liquid water inside PEMFCs by using the direct visualization method and transparent PEMFCs [17][18][19][20][21][22][23][24][25][26][27]. Yang et al [19] applied an optical PEMFC to study the mechanics of liquid water transport.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of two-phase flow in a proton exchange membrane fuel cell in short-term microgravity condition

Guo

Zhao

et al. 2014

Applied Energy

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h i g h l i g h t sTwo-phase flow in PEMFC cathode channels is observed in different gravity environments. The PEMFC shows different operating behavior in normal and microgravity conditions. Water tends can be removed in microgravity conditions at high water production regime. Liquid aggregation occurs in microgravity conditions at low water production regime. Effect of gravity on performance and two-phase flow at two operating regimes is studied. a r t i c l e i n f o t r a c tWater management is important for improving the performance and stability of proton exchange membrane fuel cells (PEMFCs) for space applications. An in situ visual observation was conducted on the gasliquid two-phase flow in the cathode channels of a PEMFC in short-term microgravity condition. The microgravity environment was supplied by a drop tower. A single serpentine flow channel with a depth of 2 mm and a width of 2 mm was applied as the cathode flow field. A membrane electrode assembly comprising of a Nafion 112 membrane sandwiched between gas diffusion layers was used. The anode and cathode were loaded with 1 mg cm À2 platinum. The PEMFC shows a distinct operating behavior in microgravity because of the effect of gravity on the two-phase flow. At a high water production regime, cell performance is enhanced by 4.6% and the accumulated liquid water in the flow channel tends can be removed in microgravity conditions to alleviate flooding. At a low water production regime, cell performance deteriorates by 6.6% and liquid aggregation occurs in the flow channel because of the coalescence of dispersed water droplets in microgravity conditions, thus squeezing the flow channel. The operating behavior of PEMFC in microgravity conditions is different from that in normal gravity conditions. Further studies are needed on PEMFC operating characteristics and liquid management for space applications.

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Section: Introductionmentioning

confidence: 99%

Experimental study of two-phase flow in a proton exchange membrane fuel cell in short-term microgravity condition

Guo

Zhao

et al. 2014

Applied Energy

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“…Theoretical one-dimensional models for liquid water transport in gas diffusion layers (GDLs), where liquid water is controlled by capillary forces depending on the structure and wettability of GDL, have been reported [1,2], and three-dimensional simulations using two-phase models have been developed [3,4]. For liquid water transport in gas flow channels, experimental investigations have been conducted using transparent fuel cells and it was demonstrated that the surface tension of water and the wettability of the GDL and gas flow channel play a dominant role in the liquid water transport [5,6]. Some numerical simulations of the dynamic behavior of condensed water, which would be strongly affected by the wettability of GDL and gas flow channel, have been reported.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of liquid water and gas flow in a channel and a simplified gas diffusion layer model of polymer electrolyte membrane fuel cells using the lattice Boltzmann method

Tabe

Lee

Chikahisa

et al. 2009

Journal of Power Sources

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Numerical simulations using the lattice Boltzmann method (LBM) are developed to elucidate the dynamic behavior of condensed water and gas flow in a polymer electrolyte membrane (PEM) fuel cell. Here, the calculation process of the LBM simulation is improved to extend the simulation to a porous medium like a gas diffusion layer (GDL), and a stable and reliable simulation of two-phase flow with large density differences in the porous medium is established. It is shown that dynamic capillary fingering can be simulated at low migration speeds of liquid water in a modified GDL, and the LBM simulation reported here, which considers the actual physical properties of the system, has significant advantages in evaluating phenomena affected by the interaction between liquid water and air flows. Two-phase flows with the interaction of the phases in the two-dimensional simulations are demonstrated. The simulation of water behavior in a gas flow channel with air flow and a simplified GDL shows that the wettability of the channel has a strong effect on the two-phase flow. The simulation of the porous separator also indicates the possibility of controlling two-phase distribution for better oxygen supply to the catalyst layer by gradient wettability design of the porous separator.Keywords: PEM fuel cell, Lattice Boltzmann method, Two-phase flow, Large density difference, Gas diffusion layer, Wettability

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“…porous media | capillarity | wettability | microfluidics | pattern formation M ultiphase flow in porous media is important in many natural and industrial processes, including geologic CO 2 sequestration (1), enhanced oil recovery (2), water infiltration into soil (3), and transport in polymer electrolyte fuel cells (4). Much of the research on multiphase flow in porous media has focused on the effect of fluid properties and flow conditions.…”

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confidence: 99%

Wettability control on multiphase flow in patterned microfluidics

Zhao

MacMinn

Juanes

2016

Proc. Natl. Acad. Sci. U.S.A.

491

480

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Multiphase flow in porous media is important in many natural and industrial processes, including geologic CO 2 sequestration, enhanced oil recovery, and water infiltration into soil. Although it is well known that the wetting properties of porous media can vary drastically depending on the type of media and pore fluids, the effect of wettability on multiphase flow continues to challenge our microscopic and macroscopic descriptions. Here, we study the impact of wettability on viscously unfavorable fluid-fluid displacement in disordered media by means of high-resolution imaging in microfluidic flow cells patterned with vertical posts. By systematically varying the wettability of the flow cell over a wide range of contact angles, we find that increasing the substrate's affinity to the invading fluid results in more efficient displacement of the defending fluid up to a critical wetting transition, beyond which the trend is reversed. We identify the pore-scale mechanisms-cooperative pore filling (increasing displacement efficiency) and corner flow (decreasing displacement efficiency)-responsible for this macroscale behavior, and show that they rely on the inherent 3D nature of interfacial flows, even in quasi-2D media. Our results demonstrate the powerful control of wettability on multiphase flow in porous media, and show that the markedly different invasion protocols that emerge-from pore filling to postbridging-are determined by physical mechanisms that are missing from current pore-scale and continuum-scale descriptions.porous media | capillarity | wettability | microfluidics | pattern formation M ultiphase flow in porous media is important in many natural and industrial processes, including geologic CO 2 sequestration (1), enhanced oil recovery (2), water infiltration into soil (3), and transport in polymer electrolyte fuel cells (4). Much of the research on multiphase flow in porous media has focused on the effect of fluid properties and flow conditions. Much less emphasis has been given to the fluids' affinity to the porous media (i.e., wettability), even though wettability has a profound influence on fluid-fluid interactions in the presence of a solid surface (5-7). Despite recent advances in our ability to accurately measure wettability under reservoir conditions (8, 9), and to engineer wettability in the subsurface (10-13), the complex physics of wetting continues to challenge our microscopic and macroscopic descriptions (14).Fluid-fluid displacement in the presence of a solid surface can be characterized as either drainage or imbibition, depending on the system's wettability. Drainage refers to the regime where the invading fluid is less wetting to the solid surface than the defending fluid. Imbibition refers to the opposite case, where the invading fluid is more wetting to the solid surface than the defending fluid. Drainage in porous media has been studied extensively through laboratory experiments and computer simulations (15-18), and we now have a fairly good understanding of the different displacement ...

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Visualization of Liquid Water Transport in a PEFC

Cited by 392 publications

References 5 publications

Experimental study of two-phase flow in a proton exchange membrane fuel cell in short-term microgravity condition

Experimental study of two-phase flow in a proton exchange membrane fuel cell in short-term microgravity condition

Numerical simulation of liquid water and gas flow in a channel and a simplified gas diffusion layer model of polymer electrolyte membrane fuel cells using the lattice Boltzmann method

Wettability control on multiphase flow in patterned microfluidics

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