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.

Fabrication and Performance Evaluation of Miniaturized Proton Exchange Membrane (PEM) Fuel Cells

2003 ◽  
Author(s):  
Tao Zhang ◽  
Pei-Wen Li ◽  
Qing-Ming Wang ◽  
Laura Schaefer ◽  
Minking K. Chyu
Keyword(s):  
Mass Transfer ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Free Convection ◽  
Current Density ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Cathode Side ◽  
Ohmic Loss ◽  
Fuel Cell Performance

Two types of miniaturized PEM fuel cells are designed and characterized in comparison with a compact commercial fuel cell device in this paper. One has Nafion® membrane electrolyte sandwiched by two brass bipolar plates with micromachined meander-like gas channels. The cross-sectional area of the gas flow channel is approximately 250 by 250 (μm). The other uses the same Nafion® membrane and anode structure, but in stead of the brass plate, a thin stainless steel plate with perforated round holes is used at cathode side. The new cathode structure is expected to allow oxygen (air) being supplied by free-convection mass transfer. The characteristic curves of the fuel cell devices are measured. The activation loss and ohmic loss of the fuel cells have been estimated using empirical equations. Critical issues such as flow arrangement, water removing and air feeding modes concerning the fuel cell performance are investigated in this research. The experimental results demonstrate that the miniaturized fuel cell with free air convection mode is a simple and reliable way for fuel cell operation that could be employed in potential applications although the maximum achievable current density is less favorable due to limited mass transfer of oxygen (air). The relation between the fuel cell dimensions and the maximum achievable current density is also discussed with respect to free-convection mode of air feeding.

Current density and polarization curves for radial flow field patterns applied to PEMFCs (Proton Exchange Membrane Fuel Cells)

Energy ◽  
2010 ◽  
Vol 35 (2) ◽  
pp. 920-927 ◽  
Author(s):  
S. Cano-Andrade ◽  
A. Hernandez-Guerrero ◽  
M.R. von Spakovsky ◽  
C.E. Damian-Ascencio ◽  
J.C. Rubio-Arana
Keyword(s):  
Fuel Cells ◽  
Flow Field ◽  
Current Density ◽  
Proton Exchange Membrane ◽  
Radial Flow ◽  
Proton Exchange ◽  
Polarization Curves ◽  
Field Patterns ◽  
Exchange Membrane

Separate Measurement of Current Density Under the Channel and the Shoulder in PEM Fuel Cells

2007 ◽  
Author(s):  
Lin Wang ◽  
Hongtan Liu
Keyword(s):  
Fuel Cells ◽  
Diffusion Layer ◽  
Current Density ◽  
Electrical Resistance ◽  
High Current Density ◽  
Gas Diffusion Layer ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Experimental Results

In a proton exchange membrane (PEM) fuel cell current density under the shoulder can be very different from that under the gas channel and the knowledge of where the current density is higher is critical in flow field designs in order to optimize cell performance. Yet, up to date this issue has not been resolved. In this study, a novel yet simple approach was adopted to directly measure the current densities under the channel and the shoulder in PEM fuel cells separately. In this approach, the cathode catalyst layer was so designed that either the area under the shoulder or the area under the channel was loaded with catalyst. Such a design guaranteed the currents generated under the shoulder and the channel could be measured separately. Experimental results showed that the current density produced under the channel was lower than that under the shoulder except in the high current density region. To determine whether the lateral electrical resistance of the gas diffusion layer (GDL) was the causes for lower current density under the channel, an additional set of experiments were conducted. In this set of experiments, a silver mesh was added on the top of the gas diffusion layer (GDL) and the experimental results showed that GDL lateral electrical resistance was not the cause and it had a negligible effect on lateral current density distribution.

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.

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.

Determination of Activation Losses in Proton Exchange Membrane Fuel Cells

2014 ◽  
Author(s):  
Seyed Mohammad Rezaei Niya ◽  
Mina Hoorfar
Keyword(s):  
Fuel Cells ◽  
Entire Range ◽  
Proton Exchange Membrane ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Fuel Cell Performance ◽  
Current Densities ◽  
Exchange Membrane ◽  
Total Activation

Activation overpotentials, due to the reaction kinetics at the surface of the electrodes are the dominant losses in low current densities in proton exchange membrane (PEM) fuel cells. Although the Butler-Volmer equation can be employed to model the reactions at the anode and cathode, there are still ambiguities regarding the estimation and modeling of the activation losses. In this paper, the Butler-Volmer equation for both the anode and cathode is simplified. It is shown that the anode activation overpotential can be modeled using the linearized Butler-Volmer equation. The cathode activation overpotential is determined using Tafel equation. The both equations are discussed to be very accurate in the entire range of fuel cell performance. The total activation overpotential is then determined.

scholarly journals Theoretical Approach to the Physics of Fuel Cells

2013 ◽  
Vol 2 ◽  
pp. 15-27 ◽  
Author(s):  
K.A.I.L. Wijewardena Gamalath ◽  
B.M.P. Peiris
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Partial Pressure ◽  
Current Density ◽  
Direct Methanol Fuel Cells ◽  
Maximum Power ◽  
Limiting Current ◽  
Limiting Current Density ◽  
Direct Methanol ◽  
Power Curves

Ion transport rate of PAFC, AFC, PEMFC, DMFC and SOFC fuel cells under the influence of an electric field and concentration gradient were evaluated for static electrolytes. AFC are the best fuel cells for higher current applications while direct methanol fuel cells DMFC are the best for lower current applications at lower temperatures. An equation for voltage output of a general fuel cell was obtained in terms of temperature and partial pressure reactants. Performance a 2D fuel cell was analyzed by simulating polarization and power curves for a fuel cell operating at 60 °C with a limiting current density of with a limiting current density of 1.5 A·cm -2. The maximum power for this fuel cell was 8.454 W delivering 82% of maximum loading current density. When the temperature was increased by one third of its original value, the maximum power increased by 6.75 % and at 60 °C for a 10 times increment of partial pressure reactants, the maximum power increased by 2.43 %.The simulated power curves of the fuel cells were best described by cubic fits.

Sign in / Sign up

Export Citation Format

Share Document