Modeling the Relative Contribution of Mass Transfer Limitation on Performance in Enzyme Fuel Cells

2005 ◽  
Keyword(s):  
Mass Transfer ◽  
Fuel Cells ◽  
Mass Transfer Limitation ◽  
Relative Contribution

A Three-Dimensional Transient Model of Two-Phase Mass Transfer in Anode Side of Passive Direct Methanol Fuel Cells

2011 ◽  
Vol 233-235 ◽  
pp. 2615-2618 ◽  
Author(s):  
Yue Ping Chen ◽  
Hang Guo ◽  
Fang Ye ◽  
Chong Fang Ma
Keyword(s):  
Mass Transfer ◽  
Fuel Cells ◽  
Direct Methanol Fuel Cells ◽  
Three Dimensional ◽  
Anode Side ◽  
Two Phase ◽  
Mass Transfer Limitation ◽  
Drift Flux Model ◽  
Direct Methanol ◽  
Methanol Fuel Cells

A three-dimensional, two-phase, multiple-component, unsteady model for the anode side of passive direct methanol fuel cells is presented in this work. The model is formed by a drift-flux model and can capture in-plane distributions of species along different directions in the cell. After grid independency test, this model is used to investigate numerically transport behaviors in the anode of liquid feed direct methanol fuel cells. The results illustrate the feasibility of the passively delivering methanol to the electrochemical reaction site, and characterize the relevant transport phenomena. Moreover, the evolution of species concentration, velocities along different directions in the cell and the mass transfer limitation were also presented. The three-dimensional model is valuable for understanding and predicting mass transfer in passive direct methanol fuel cells.

scholarly journals Heat and Mass Transfer and Two Phase Flow in Hydrogen Proton Exchange Membrane Fuel Cells and Direct Methanol Fuel Cells

2003 ◽  
Author(s):  
Hang Guo ◽  
Chong Fang Ma ◽  
Mao Hai Wang ◽  
Jian Yu ◽  
Xuan Liu ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Direct Methanol Fuel Cells ◽  
Proton Exchange ◽  
Phase Flow ◽  
Two Phase ◽  
Direct Methanol ◽  
Methanol Fuel Cells ◽  
Exchange Membrane

Fuel cells are related to a number of scientific and engineering disciplines, which include electrochemistry, catalysis, membrane science and engineering, heat and mass transfer, thermodynamics and so on. Several thermophysical phenomena such as heat transfer, multicomponent transport and two phase flow play significant roles in hydrogen proton exchange membrane fuel cells and direct methanol fuel cells based on solid polymer electrolyte membrane. Some coupled thermophysical issues are bottleneck in process of scale-up of direct methanol fuel cells and hydrogen proton exchange membrane fuel cells. In present paper, experimental results of visualization of condensed water in fuel cell cathode microchannels are presented. The equivalent diameter of the rectangular channel is 0.8mm. Water droplets from the order of 0.08mm to 0.8mm were observed from several different locations in the channels. Several important problems, such as generation and change characteristics of water droplet and gas bubble, two phase flow under chemical reaction conditions, mass transfer enhancement of oxygen in the cathode porous media layer, heat transfer enhancement and high efficiency cooling system of proton exchange membrane fuel cells stack, etc., are discussed.

scholarly journals Jet aeration as alternative to overcome mass transfer limitation of stirred bioreactors

2018 ◽  
Vol 18 (4) ◽  
pp. 244-253 ◽  
Author(s):  
Sebastian Weber ◽  
Sebastian Schaepe ◽  
Stephan Freyer ◽  
Michael-Helmut Kopf ◽  
Christian Dietzsch
Keyword(s):  
Mass Transfer ◽  
Mass Transfer Limitation ◽  
Stirred Bioreactors

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.

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