The Impact of Rib/Channel, Water and Heat Transport on Limiting Current Density

2008 ◽  
Author(s):  
Yuichiro Tabuchi ◽  
Norio Kubo
Keyword(s):  
Heat Transport ◽  
Water Transport ◽  
Current Density ◽  
Liquid Water ◽  
Proton Exchange ◽  
Cell Performance ◽  
Limiting Current ◽  
Promising Alternative ◽  
Limiting Current Density ◽  
The Impact

Proton exchange membrane fuel cells (PEMFCs) are regarded as a promising alternative clean power source for automotive applications. Key to the acceptance of PEMFCs for automobiles are cost reduction and power density for compactness. In order to meet these requirements, further improvement of cell performance is required. In particular, under higher current density operation, water and heat transport in PEMFC have strong effects on cell performance. In this study, the impact of Rib/Channel dimensions, heat and water transport on cell performance under high current density is investigated using the multiphase mixture model (M2 model), and the limiting current density is evaluated using a uniform test cell with 10cm2 active area and 24 straight channels. Limiting current densities were measured under different oxygen concentrations at 70°C and 70% relative humidity at both sides. In order to neglect the effect of liquid water in channels and the distribution of oxygen and hydrogen concentrations along the flow channel, large flow rates were introduced at both sides. Experimental results show a nonlinear relation between oxygen concentration in the channel and limiting current density. Numerically it is found that this nonlinear trend is caused by liquid water in the Rib region. In addition, it is also found that not only liquid water, but also heat transport and water transport through the membrane significantly affect the limiting current density. Finally, it is concluded that the combination analysis using limiting current experiments of uniform cell system and M2 model is very useful for fundamental understanding and for fuel cell design optimization.

RIB/Channel Effect on Cell Performance Under High Current Density Operation

2010 ◽  
Author(s):  
Yuichiro Tabuchi ◽  
Takeshi Shiomi ◽  
Osamu Aoki ◽  
Norio Kubo ◽  
Kazuhiko Shinohara
Keyword(s):  
Water Transport ◽  
Current Density ◽  
Liquid Water ◽  
Water Distribution ◽  
Numerical Study ◽  
High Current Density ◽  
Cell Performance ◽  
High Current ◽  
Numerical Validation ◽  
The Impact

Heat and water transport in polymer electrolyte membrane fuel cell (PEMFC) has considerable impacts on cell performance under high current density which is desired in PEMFC for automobiles. In this study, the impact of rib/channel, heat and water transport on cell performance under high current density was investigated by experimental evaluation of liquid water distribution and numerical validation. Liquid water distribution between rib and channel is evaluated by Neutron Radiography. In order to neglect the effect of liquid water in channel and the distribution of oxygen and hydrogen concentration distribution along with channel length, the differential cell was used in this study. Experimental results show that liquid water under channel was dramatically changed with Rib/Channel width. From numerical study, it is found that the change of liquid water distribution was strongly affected by temperature distribution between rib and channel. In addition, not only heat transport but also water transport through membrane also significantly affected cell performance under high current density operation. From numerical validation, it is concluded that this effect on cell performance under high current density could be due to the enhancement of back-diffusion of water through membrane.

scholarly journals An Investigation of Direct Hydrocarbon (Propane) Fuel Cell Performance Using Mathematical Modeling

2018 ◽  
Vol 2018 ◽  
pp. 1-18
Author(s):  
Bhavana Parackal ◽  
Hamidreza Khakdaman ◽  
Yves Bourgault ◽  
Marten Ternan
Keyword(s):  
Fuel Cells ◽  
Current Density ◽  
Reaction Rate ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Polarization Curves ◽  
Limiting Current ◽  
Fuel Cell Performance ◽  
Limiting Current Density ◽  
Current Densities

An improved mathematical model was used to extend polarization curves for direct propane fuel cells (DPFCs) to larger current densities than could be obtained with any of the previous models. DPFC performance was then evaluated using eleven different variables. The variables related to transport phenomena had little effect on DPFC polarization curves. The variables that had the greatest influence on DPFC polarization curves were all related to reaction rate phenomena. Reaction rate phenomena were dominant over the entire DPFC polarization curve up to 100 mA/cm2, which is a value that approaches the limiting current densities of DPFCs. Previously it was known that DPFCs are much different than hydrogen proton exchange membrane fuel cells (PEMFCs). This is the first work to show the reason for that difference. Reaction rate phenomena are dominant in DPFCs up to the limiting current density. In contrast the dominant phenomenon in hydrogen PEMFCs changes from reaction rate phenomena to proton migration through the electrolyte and to gas diffusion at the cathode as the current density increases up to the limiting current density.

Performance Enhancement in Proton-Exchange Membrane Fuel Cell for Cathode Pulsating Flow

2010 ◽  
Author(s):  
Yun Ho Kim ◽  
Hun Sik Han ◽  
Seo Young Kim ◽  
Gwang Hoon Rhee
Keyword(s):  
Fuel Cell ◽  
Current Density ◽  
Proton Exchange Membrane ◽  
Performance Enhancement ◽  
Proton Exchange ◽  
Pulsating Flow ◽  
Limiting Current ◽  
Mean Flow ◽  
Limiting Current Density ◽  
Exchange Membrane

The effect of cathode flow pulsation on the performance enhancement of a 10-cell proton-exchange membrane fuel cell is investigated. We perform the experiment using two pulsation devices. One pulsation device, i.e., acoustic woofer, generates a pulsating flow, which is added to a unidirectional flow supplied from a compressed air tank. The other pulsation device is a crankshaft system that produces a pure oscillatory flow without mean flow. In the case of cathode pulsating flow with mean flow, the fuel cell power output and the limiting current density dramatically increase as pulsating frequency increases at given pulsating amplitude, while the fuel cell efficiency slightly decreases. This result is contributed that the pulsating flow enhances the dispersion inside the cathode channels, and then improving the oxygen and temperature distributions. This performance enhancement by cathode pulsating flow is more distinct at low cathode mean flow rates. In the case of cathode pulsating flow without mean flow, the fuel cell stack is operated despite cathode mean flow is absent. The limiting current density is extended as the pulsating frequency and swept distance (amplitude) increase. When the pulsating frequency and swept distance are 2.38Hz and 13.65mm respectively, the fuel cell performance is equal to that the cathode mean flow rate is 1.29 lpm. Also, the case of pulsating flow is more stable at the concentration loss region than the case of non-pulsating flow for the same performance conditions.

Capillarity, Wettability and Interfacial Dynamics in Polymer Electrolyte Fuel Cells

2009 ◽  
Author(s):  
Partha P. Mukherjee
Keyword(s):  
Polymer Electrolyte ◽  
Water Transport ◽  
Liquid Water ◽  
Gas Diffusion ◽  
Interfacial Dynamics ◽  
Modeling Framework ◽  
Promising Alternative ◽  
Phase Dynamics ◽  
Liquid Water Transport ◽  
The Impact

In the present scenario of a global initiative toward a sustainable energy future, the polymer electrolyte fuel cell (PEFC) has emerged as one of the most promising alternative energy conversion devices for different applications. Despite tremendous progress in recent years, a pivotal performance/durability limitation in the PEFC arises from liquid water transport, perceived as the Holy Grail in PEFC operation. The porous catalyst layer (CL), fibrous gas diffusion layer (GDL) and flow channels play a crucial role in the overall PEFC performance due to the transport limitation in the presence of liquid water and flooding phenomena. Although significant research, both theoretical and experimental, has been performed, there is serious paucity of fundamental understanding regarding the underlying structure-transport-performance interplay in the PEFC. The inherent complex morphologies, micro-scale transport physics involving coupled multiphase, multicomponent, electrochemically reactive phenomena and interfacial interactions in the constituent components pose a formidable challenge. In this paper, the impact of capillary transport, wetting characteristics and interfacial dynamics on liquid water transport is presented based on a comprehensive mesoscopic modeling framework with the objective to gain insight into the underlying electrodics, two-phase dynamics and the intricate structure-transport-interface interactions in the PEFC.

scholarly journals Limiting Current Density of Oxygen Reduction under Ultrathin Electrolyte Layers: From the Micrometer Range to Monolayers

2021 ◽  
Vol 8 (4) ◽  
pp. 712-718
Author(s):  
Xiankang Zhong ◽  
Matthias Schulz (née Uebel) ◽  
Chun‐Hung Wu ◽  
Martin Rabe ◽  
Andreas Erbe ◽  
...  
Keyword(s):  
Oxygen Reduction ◽  
Current Density ◽  
Limiting Current ◽  
Limiting Current Density

Effect of Vibration on the Liquid Water Transport of PEM Fuel Cells

2009 ◽  
Author(s):  
Luis Breziner ◽  
Peter Strahs ◽  
Parsaoran Hutapea
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Water Transport ◽  
Liquid Water ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Cell Performance ◽  
Sinusoidal Vibration ◽  
Fuel Cell Performance ◽  
Liquid Water Transport

The objective of this research is to analyze the effects of vibration on the performance of hydrogen PEM fuel cells. It has been reported that if the liquid water transport across the gas diffusion layer (GDL) changes, so does the overall cell performance. Since many fuel cells operate under a vibrating environment –as in the case of automotive applications, this may influence the liquid water concentration across the GDL at different current densities, affecting the overall fuel cell performance. The problem was developed in two main steps. First, the basis for an analytical model was established using current models for water transport in porous media. Then, a series of experiments were carried, monitoring the performance of the fuel cell for different parameters of oscillation. For sinusoidal vibration at 10, 20 and 50Hz (2 g of magnitude), a decrease in the fuel cell performance by 2.2%, 1.1% and 1.3% was recorded when compared to operation at no vibration respectively. For 5 g of magnitude, the fuel cell reported a drop of 5.8% at 50 Hz, whereas at 20 Hz the performance increased by 1.3%. Although more extensive experimentation is needed to identify a relationship between magnitude and frequency of vibration affecting the performance of the fuel cell as well as a throughout examination of the liquid water formation in the cathode, this study shows that sinusoidal vibration, overall, affects the performance of PEM fuel cells.

scholarly journals Demineralization of Rehydrated Cheese Whey by Electrodialysis. Effects of deashing rates and solid concentration on limiting current density.

1991 ◽  
Vol 17 (5) ◽  
pp. 1006-1011 ◽  
Author(s):  
Yasunobu Hiraoka ◽  
Akira Tomizawa ◽  
Tatsuki Oguchi ◽  
Etsuko Suzuki ◽  
Masanobu Koutake
Keyword(s):  
Current Density ◽  
Cheese Whey ◽  
Limiting Current ◽  
Solid Concentration ◽  
Limiting Current Density

Polarization Characteristics to Wear Ratio of Anti-Fouling Paint

2015 ◽  
Vol 1110 ◽  
pp. 179-184
Author(s):  
Kyung Man Moon ◽  
Dong Hyun Park ◽  
Yun Hae Kim ◽  
Tae Sil Baek
Keyword(s):  
Current Density ◽  
Corrosion Potential ◽  
Wear Test ◽  
Life Time ◽  
Point Of View ◽  
Limiting Current ◽  
Limiting Current Density ◽  
Wear Ratio ◽  
Polarization Characteristics ◽  
Lower Variation

Recently, anti-fouling paints which does not include the poison components such as tin (Sn) free, copper (Cu) free have been increasingly developed in order to decrease the contamination of marine environment. Moreover, the wear ratios of these anti-fouling paints are very important problem to prolong their life time in economical and environmental point of view. In this study, four types of anti-fouling paints as self-polishing type were investigated on the relationship between their polarization characteristics and wear ratios. Relationship between wear ratio and variation ratio of polarization resistance measured in corrosion potential was not well matched with each other. However, there was a good agreement between the wear ratio and variation ratio of diffusion limiting current density, for example, the higher or the lower variation ratio of diffusion limiting current density, wear ratio also increased or decreased respectively. Consequently, it is suggested that we can qualitatively expect the life time and wear degree of anti-fouling paint by only measuring the polarization characteristics before the wear test is practically performed in the field.Keywords: Anti-fouling paint, Self-polishing type, Polarization characteristics, Wear ratio, Diffusion limiting current density, Corrosion Potential

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