Three-Dimensional Simulation of Water Droplet Movement in PEM Fuel Cell Flow Channels with Fluid-Mechanics Properties and Different Deformations of GDL

2012 ◽  
Vol 625 ◽  
pp. 53-56 ◽  
Author(s):  
Ning Bao ◽  
Qing Du ◽  
Yan Yin
Keyword(s):  
Water Management ◽  
Fuel Cell ◽  
Liquid Water ◽  
Water Droplet ◽  
Three Dimensional ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Cathode Side ◽  
Gas Channel ◽  
Flow Channels

Water management plays a significant role in enhancing performance of proton exchange membrane fuel cell (PEMFC). Successful water management requires effective removal of liquid water produced by electrochemical reactions. Therefore, it is a critical challenge to understand liquid water movements in flow channels. In the present study, a three-dimensional unsteady two-phase model for the cathode side of PEMFC consisting of gas channel (GC), gas diffusion layer (GDL) and catalyst layer (CL) is developed using FLUENT software with a volume-of-fluid (VOF) method and user-defined-function (UDF). When fuel cells are assembled, the cross sections of gas channel change, resulting in different water droplet movements. The effects of GDL deformations on water droplet movements are discussed.

Model Based Investigation of Liquid Water Injection Strategies for Evaporatively Cooled PEM Fuel Cells

2015 ◽  
Author(s):  
Ashley Fly ◽  
Rob H. Thring
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Water Injection ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Operating Pressure ◽  
Isothermal Model ◽  
Flow Channels ◽  
Injection Strategies

Evaporative cooling through liquid water injection directly into the fuel cell flow channels removes the requirement for external humidification and liquid cooling channels within the stack. However, the amount of liquid water injected must be accurately controlled, to prevent on one hand membrane drying due to lack of water vapor and on the other hand flooding due to excessive liquid water. In this paper a one-dimensional, non-isothermal model of an evaporatively cooled proton exchange membrane fuel cell (PEMFC) is produced. The model accounts for changes in relative humidity and temperature along the anode and cathode flow channels, water transfer through the membrane and liquid accumulation within the gas diffusion layers. The model was used to study liquid water injection strategies at both cell and localized level. The influence of current density, operating pressure and inlet humidity were investigated. Results show that provided high humidity is maintained throughout the cell, exhaust gas temperature increase from low to high current densities (0.4–1.4A/cm2) is less than 4.0°C, without the need for active temperature control. Furthermore both temperature regulation and good membrane hydration can be managed by uniform injection of liquid water throughout the cell to maintain a target cathode exhaust humidity.

Numerical Simulation of Liquid Water Behavior in Microchannel With a 90° Bend

2013 ◽  
Author(s):  
Mosab Alrahmani ◽  
Rui Chen ◽  
Salah Ibrahim
Keyword(s):  
Water Management ◽  
Numerical Simulation ◽  
Fuel Cell ◽  
Dynamic Behavior ◽  
Liquid Water ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Bottom Surface ◽  
Water Behavior ◽  
Wall Wettability

Water management is an effective way of improving Proton Exchange Membrane (PEM) fuel cell performance and durability. Changing the wettability of gas channel walls and gas diffusion layer (GDL) is one way of controlling the water management in a fuel cell for its influence on the liquid water dynamic behavior. The objective of this study is to investigate liquid water dynamic behavior in a microchannel with a 90° bend and different surface wettability combinations through 3D numerical simulation. Volume-of-fluid (VOF) method was employed to track the fluid-fluid interface in the multiphase flow. The simulated microchannel has a square cross-section with a dimension of 0.25 mm and a total length of 1.5 mm. Water is introduced to the channel via two pores in the bottom surface representing a GDL while air flows from one end to another. The air and water velocities used are in the order of magnitude of a high current density fuel cell. Nine different combinations of wall/GDL wettability are investigated. The results show that liquid water takes less time to leave the channel in a hydrophilic GDL compared to moderate and hydrophobic GDL regardless of wall wettability. Furthermore, the GDL wettability shows more significant impact on liquid water behavior compared to the wall wettability; however, wall wettability has a slight but considerable impact.

Experimental Observation of Liquid Water Formation in Cathode Side Gas Channel of a Transparent PEM Fuel Cell

2006 ◽  
Author(s):  
Mingfei Gan ◽  
Lea Der Chen ◽  
P. C. Sui
Keyword(s):  
Fuel Cell ◽  
Experimental Observation ◽  
Liquid Water ◽  
Liquid Droplet ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Cathode Side ◽  
Two Phase ◽  
Gas Channel ◽  
Water Formation

This paper reports on an experimental observation of water formation in a proton exchange membrane fuel cell (PEMFC). A fuel cell assembly with transparent end plates showing the gas channels is used. The study shows that liquid water can be present inside the gas channel of the fuel cell at a relatively low current density condition. The presence of liquid water could be in the form of mist-flow, suspended droplets, and sporadic liquid-gas two-phase flows, depending on operating conditions of the fuel cell. The voltage of the transparent fuel cell degraded over time, which is thought to be a result due to contamination from the fabrication of the gas channel plates of the transparent fuel cell. Onsets of the liquid droplet formation in gas channels are compared to the qualitative descriptions of homogeneous and heterogeneous nucleation theories.

A Critical Review of Water Transport Models in Gas Diffusion Media of PEM Fuel Cell

2008 ◽  
Author(s):  
Jacob LaManna ◽  
Satish G. Kandlikar
Keyword(s):  
Water Management ◽  
Fuel Cell ◽  
Water Transport ◽  
Combustion Engine ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Cathode Side ◽  
Small Scale

Proton Exchange Membrane (PEM) fuel cells are gaining popularity as a replacement to the internal combustion engine in automobiles. This application will demand high levels of performance from the fuel cell making it critical that proper water management is maintained. One of the areas of interest in water management is the transport of water through the Gas Diffusion Medium (GDM) on the cathode side of the cell. Research is currently being conducted to understand how water moves through the porous structure of the GDM. Due to the small scale of the GDM, most work done is analytical modeling. This paper will focus on reviewing current models for water transport within the GDM of a PEM fuel cell to address state of the art and provide recommendations for future work to extend current models.

Three Dimensional Analysis of a PEM Fuel Cell With the Shape of a Fermat Spiral for the Flow Channel Configuration

2008 ◽  
Author(s):  
D. Jua´rez-Robles ◽  
A. Herna´ndez-Guerrero ◽  
C. E. Damia´n-Ascencio ◽  
C. Rubio-Arana
Keyword(s):  
Fuel Cell ◽  
Current Density ◽  
Three Dimensional ◽  
Pem Fuel Cell ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Flow Channels ◽  
Channel Configuration

This work presents the analysis of a non-isothermal three-dimensional model in single phase of a PEM fuel cell with an innovative flow field path in the form of the Fermat spiral, i.e. two concentric spirals. The model is used to predict the current density contours and the water content in all of the zones of the fuel cell. The three-dimensional model includes: the gas flow channels with the shape of the new geometry proposed, the current collectors, gas diffusion layers, catalyst layers on both sides of the model, anode and cathode, and a proton exchange membrane in between. The model solves the energy equation, mass conservation, and species transport equations, including the source terms due the electrochemical effects occurring in the cell. The results show a higher average current density than the fuel cells with conventional flow paths, showing also that the current density attained is more uniform from the inlet to the outlet of the flow channels.

Predicting Liquid Water Saturation Through Differently Structured Cathode Gas Diffusion Media of a Proton Exchange Membrane Fuel Cell

2012 ◽  
Vol 9 (2) ◽  
Author(s):  
N. Akhtar ◽  
P. J. A. M. Kerkhof
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Proton Exchange Membrane ◽  
Water Saturation ◽  
Catalyst Layer ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Diffusion Media ◽  
Exchange Membrane

The role of gas diffusion media with differently structured properties have been examined with emphasis on the liquid water saturation within the cathode of a proton exchange membrane fuel cell (PEMFC). The cathode electrode consists of a gas diffusion layer (GDL), a micro-porous layer and a catalyst layer (CL). The liquid water saturation profiles have been calculated for varying structural and physical properties, i.e., porosity, permeability, thickness and contact angle for each of these layers. It has been observed that each layer has its own role in determining the liquid water saturation within the CL. Among all the layers, the GDL is the most influential layer that governs the transport phenomena within the PEMFC cathode. Besides, the thickness of the CL also affects the liquid water saturation and it should be carefully controlled.

Investigation of Thermal Influence on the Assembly of Polymer Electrolyte Membrane Fuel Cell Stacks

2012 ◽  
Vol 512-515 ◽  
pp. 1509-1514
Author(s):  
Lin Fa Peng ◽  
Dian Kai Qiu ◽  
Pei Yun Yi ◽  
Xin Min Lai
Keyword(s):  
Thermal Expansion ◽  
Fuel Cell ◽  
Contact Pressure ◽  
Proton Exchange Membrane ◽  
Three Dimensional ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Fe Model ◽  
Assembly Process

The assembly force in a proton exchange membrane fuel cell (PEMFC) stack affects the characteristics of the porosity and electrical conductivity. Generally, the stack is assembled at room temperature while it’s operated at about 80 °Cor even higher. As a result, the assembly pressure can’t keep constant due to thermal expansion. This paper focuses on the contact pressure between membrane electrode assembly (MEA) and bipolar plates in real operations. A three-dimensional finite element (FE) model for the assembly process is established with coupled thermal-mechanical effects. The discipline of contact pressure under thermal-mechanical effect is investigated. A single cell stack is fabricated in house for the analysis of contact pressures on gas diffusion layer at different temperatures. The results show that as the temperature increases, contact pressure increases due to thermal expansion. It indicates that the influence of thermal expansion due to temperature variation should be taken into consideration for the design of the stack assembly process.

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