scholarly journals Interfacial Water Transport Effects in Proton-Exchange Membranes

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Brian Kientiz ◽  
Haruhiko Yamada ◽  
Nobuaki Nonoyama ◽  
Adam Z. Weber
Keyword(s):  
Experimental Data ◽  
Fuel Cell ◽  
Water Transport ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Polymer Electrolyte Fuel Cell ◽  
Interfacial Resistance ◽  
Fuel Cell Performance ◽  
Membrane Interfaces

It is well known that the proton-exchange membrane is perhaps the most critical component of a polymer-electrolyte fuel cell. Typical membranes, such as Nafion®, require hydration to conduct efficiently and are instrumental in cell water management. Recently, evidence has been shown that these membranes might have different interfacial morphology and transport properties than in bulk. In this paper, experimental data combined with theoretical simulations that explore the existence and impact of interfacial resistance on water transport for Nafion®21x membranes will be presented. A mass-transfer coefficient for the interfacial resistance is calculated from experimental data using different permeation cells. This coefficient is shown to depend exponentially on relative humidity or water activity. The interfacial resistance does not seem to exist for liquid/membrane or membrane/membrane interfaces. The effect of the interfacial resistance is to flatten the water content profiles within the membrane during operation. Under typical operating conditions, the resistance is on par with the water transport resistance of the bulk membrane. Thus, the interfacial resistance can be dominant especially in thin, dry membranes and can affect overall fuel cell performance.

Visualization Study of Cathode Flooding With Different Operating Conditions in a PEM Unit Fuel Cell

2005 ◽  
Author(s):  
Han-Sang Kim ◽  
Tae-Hun Ha ◽  
Sung-Jin Park ◽  
Kyoungdoug Min ◽  
Minsoo Kim
Keyword(s):  
Fuel Cell ◽  
Water Transport ◽  
Proton Exchange Membrane ◽  
Ccd Camera ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Cathode Side ◽  
Two Phase ◽  
Fuel Cell Performance ◽  
Study Results

Visualization technique was used to better understand the water build-up phenomena on the cathode side of a proton exchange membrane (PEM) unit fuel cell. In this study, a transparent PEM unit fuel cell with an active area of 25 cm2 was designed and fabricated to allow for the visualization of cathode channel with fuel cell performance characteristics. Two-phase flow due to the electrochemical reaction of fuel cell was experimentally investigated. The images photographed by CCD camera with various cell temperatures (30–50°C) and different inlet humidification levels were presented in this study. Results indicated that the flooding on the cathode side first occurs near the exit of cathode flow channel. As the fuel cell operating temperature increases, it was found that water droplets tend to evaporate easily because of increased saturation vapor pressure and it can have an influence on lowering the flooding level. The approaches of this study can effectively contribute to the detailed researches on water transport phenomena including modeling water transport of an operating PEM fuel cell.

Numerical Analysis of Water Transport in PEM Fuel Cell Membranes Using a Phenomenological Model

2004 ◽  
Author(s):  
P. C. Sui ◽  
N. Djilali
Keyword(s):  
Fuel Cell ◽  
Water Content ◽  
Water Transport ◽  
Phenomenological Model ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Design Parameters ◽  
Exchange Membrane ◽  
And Diffusion

A numerical investigation on the water transport across the membrane of a proton exchange membrane fuel cell is carried out to gain insight into water management issues, which are crucial to the efficient operation of such fuel cells. The transport equation of water content based on a phenomenological model, which includes an electro-osmotic drag term and a diffusion term, is solved using the finite volume method for a 1-D configuration with the assumption of a uniform temperature distribution. Transport properties including the drag coefficient and diffusion coefficient of water in the membrane and the ionic conductivity of the membrane are expressed as functions of water content and temperature. The effects on the water flux across the membrane and on overall membrane protonic conductivity due to variations of these properties are studied. The numerical results show that water transport in the membrane is mainly determined by the relative strength of electro-osmotic drag and diffusion, which are affected by operating conditions such as current density and relative humidity at the membrane surface, and design parameters such as membrane thickness and membrane material. Computed water fluxes for different humidity boundary conditions indicate that for a thick membrane, e.g. Nafion 117, electro-osmotic drag dominates transport over a wide range of operating conditions, whereas for a thin membrane, e.g. Nafion 112, diffusion of water becomes equally important under certain conditions. Implications of the one-dimensional investigation on comprehensive CFD based modelling of proton exchange membrane fuel cell are also discussed.

Validation and Calibration of a Proton Exchange Membrane Fuel Cell Model Against Dynamic Partial Pressure Data

2010 ◽  
Author(s):  
Arnab Roy ◽  
Ugur Pasaogullari ◽  
Michael W. Renfro ◽  
Baki M. Cetegen
Keyword(s):  
Experimental Data ◽  
Fuel Cell ◽  
Partial Pressure ◽  
Water Transport ◽  
Proton Exchange Membrane ◽  
Cell Model ◽  
Proton Exchange ◽  
Pressure Profiles ◽  
Model Predictions ◽  
Exchange Membrane

Transient experimental validation and investigation of the effect of diffusivity of porous layers on the dynamic water vapor partial pressure profiles of a proton exchange membrane fuel cell (PEMFC) during load change is presented. A three dimensional, isothermal, transient, single-phase computational fluid dynamics based model is developed to validate with the water partial pressure profiles experimentally measured during start-up conditions earlier in a 50 cm2 PEMFC having a single serpentine flow path in counter-flow configuration. The fluid flow within the serpentine channel geometry is simulated using a straight channel fuel cell model with total channel length equivalent to the stretched length of the entire serpentine path incorporating the same amount of pressure drop from inlet to outlet. The model equations are solved using a multi-domain approach incorporating water transport through membrane and multi-component species transport through porous diffusion layer. The transient model predictions of water partial pressure profiles of anode and cathode channels are found to be in good agreement within the error bounds of the experimental results. This validation is also indicative of the two different time scales i.e. initial anode dip due to electro-osmotic drag and recovery due to back diffusion from cathode to anode. Steady state model predictions are compared to check for accuracy simultaneously. The model also delineates the significance of effective diffusivity of porous Gas Diffusion Layers (GDL) and Catalyst Layers (CL) on transient characteristics. In order to come up with best parameters to validate with experimental data, a sensitivity analysis with parametric variations of effective porosity of GDL and CL is performed with a single experimental data set and then applied to the remaining sets. Results show that the CL diffusivity has a more pronounced effect on water accumulation as well as on temporal water transport than GDL diffusivity. The numerical simulation thus provides a validated set of quantitative model parameters along with an insight to the underlying physics of water transport phenomena in a PEMFC.

Computational Modeling of PEM Fuel Cells With PBI Membranes

2006 ◽  
Author(s):  
Denver F. Cheddie ◽  
Norman D. H. Munroe
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Catalyst Activity ◽  
Three Dimensional ◽  
Oxygen Depletion ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Fuel Cell Performance ◽  
Parametric Analyses

A parametric model of a proton exchange membrane fuel cell (PEMFC) operating with a polybenzimidazole (PBI) membrane is presented. The model is three dimensional and applicable for PEMFCs operating at intermediate temperatures (120–150 °C). It accounts for all transport and polarization phenomena, and the results compare well with published experimental data for equivalent operating conditions. Results for oxygen concentration and temperature variations are presented. The model predicts the oxygen depletion, which occurs in the catalyst area under the ribs, and which gives an indication of the catalyst utilization. Results also predict that for an output power density of 1 kW m−2, a cell temperature rise of up to 30 K can be expected for typical laboratory operating conditions. Parametric analyses indicate that significant gain in fuel cell performance can be expected by increasing the conductivity of the PBI membrane. Further, results demonstrate that when the catalyst region is well utilized, increasing the catalyst activity results in only a small improvement in performance.

A Study of Water Transport of Hollow Fiber Membranes Over Various Operating Conditions

2018 ◽  
Author(s):  
Jongmin Chae ◽  
Sangseok Yu
Keyword(s):  
Fuel Cell ◽  
Water Transport ◽  
Hollow Fiber ◽  
Proton Exchange Membrane ◽  
Hollow Fiber Membrane ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Fuel Cell Vehicle ◽  
Fiber Membrane ◽  
Fuel Cell Stack

A membrane humidifier is a device to provide water vapor into the proton exchange membrane fuel cell stack that is used for transportation application due to global warming. Since inadequate humidification severely affects the performance and durability of a fuel cell stack, it is necessary to equip the humidifier for delivery humidification into the fuel cell vehicle. In this study, the performance of humidification in hollow fiber membrane is investigated. While the test section is exposed to external humidity condition, dry air is provided through hollow fiber membrane so that the water transport is facilitated. Since various parameters can change the performance, the performance investigation has to be carried out with parameters. In this study the water transport of hollow fiber membrane is investigated in terms of principle operating conditions such as temperature, pressure, and flow rate.

scholarly journals Analysis of Membranless Formic Acid Fuel Cell using E-Shaped Microfluidic Channel

2019 ◽  
Vol 31 (11) ◽  
pp. 2497-2502
Author(s):  
M. Elumalai ◽  
M. Raja ◽  
A. Rajasekaran ◽  
B. Chinnaraja
Keyword(s):  
Fuel Cell ◽  
Formic Acid ◽  
Proton Exchange Membrane ◽  
Microfluidic Channel ◽  
Cell System ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Alkaline Media ◽  
Fuel Cell Performance ◽  
Membraneless Fuel Cell

A microfluidic fuel cell has been fabricated using formic acid in an alkaline media as the fuel and sodium percarbonate in acidic media as the oxidant. Various operating conditions and different cell dimensions were applied to evaluate the fuel cell performance. The laminar flow-based membraneless fuel cell was found to reach a maximum power density of 23.60 mW cm-2 using 1.50 M HCOOH in 3 M NaOH solution as the fuel and 0.15 M percarbonate in 1.50 M H2SO4 solution as the oxidant at room temperature. The fuel cell system has no proton exchange membrane. This simple membraneless fuel cell with a planar structure has a high design flexibility, which enables its easy integration into actual microfluidic systems and miniature power applications.

scholarly journals Technical and Commercial Challenges of Proton-Exchange Membrane (PEM) Fuel Cells

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 144
Author(s):  
Abed Alaswad ◽  
Abdelnasir Omran ◽  
Jose Ricardo Sodre ◽  
Tabbi Wilberforce ◽  
Gianmichelle Pignatelli ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
High Efficiency ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Future Research ◽  
Fuel Cell Performance ◽  
Research Activities

This review critically evaluates the latest trends in fuel cell development for portable and stationary fuel cell applications and their integration into the automotive industry. Fast start-up, high efficiency, no toxic emissions into the atmosphere and good modularity are the key advantages of fuel cell applications. Despite the merits associated with fuel cells, the high cost of the technology remains a key factor impeding its widespread commercialization. Therefore, this review presents detailed information into the best operating conditions that yield maximum fuel cell performance. The paper recommends future research geared towards robust fuel cell geometry designs, as this determines the cell losses, and material characterization of the various cell components. When this is done properly, it will support a total reduction in the cost of the cell which in effect will reduce the total cost of the system. Despite the strides made by the fuel cell research community, there is a need for public sensitization as some people have reservations regarding the safety of the technology. This hurdle can be overcome if there is a well-documented risk assessment, which also needs to be considered in future research activities.

Highly proton conductive membranes based on carboxylated cellulose nanofibres and their performance in proton exchange membrane fuel cells

2019 ◽  
Author(s):  
Valentina Guccini ◽  
Annika Carlson ◽  
Shun Yu ◽  
Göran Lindbergh ◽  
Rakel Wreland Lindström ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Surface Charge ◽  
Proton Exchange Membrane ◽  
Membrane Surface ◽  
Proton Exchange ◽  
Membrane Thickness ◽  
Fuel Cell Performance ◽  
Cellulose Nanofibres ◽  
Exchange Membrane

The performance of thin carboxylated cellulose nanofiber-based (CNF) membranes as proton exchange membranes in fuel cells has been measured in-situ as a function of CNF surface charge density (600 and 1550 µmol g<sup>-1</sup>), counterion (H<sup>+</sup>or Na<sup>+</sup>), membrane thickness and fuel cell relative humidity (RH 55 to 95 %). The structural evolution of the membranes as a function of RH as measured by Small Angle X-ray scattering shows that water channels are formed only above 75 % RH. The amount of absorbed water was shown to depend on the membrane surface charge and counter ions (Na<sup>+</sup>or H<sup>+</sup>). The high affinity of CNF for water and the high aspect ratio of the nanofibers, together with a well-defined and homogenous membrane structure, ensures a proton conductivity exceeding 1 mS cm<sup>-1</sup>at 30 °C between 65 and 95 % RH. This is two orders of magnitude larger than previously reported values for cellulose materials and only one order of magnitude lower than Nafion 212. Moreover, the CNF membranes are characterized by a lower hydrogen crossover than Nafion, despite being ≈ 30 % thinner. Thanks to their environmental compatibility and promising fuel cell performance the CNF membranes should be considered for new generation proton exchange membrane fuel cells.<br>

scholarly journals Modelling of Humidity Dynamics for Open-Cathode Proton Exchange Membrane Fuel Cell

2021 ◽  
Vol 12 (3) ◽  
pp. 106
Author(s):  
Fengxiang Chen ◽  
Liming Zhang ◽  
Jieran Jiao
Keyword(s):  
Fuel Cell ◽  
Mass Flow ◽  
Proton Exchange Membrane ◽  
Flow Model ◽  
Transport Theory ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Output Performance ◽  
Exchange Membrane

The durability and output performance of a fuel cell is highly influenced by the internal humidity, while in most developed models of open-cathode proton exchange membrane fuel cells (OC-PEMFC) the internal water content is viewed as a fixed value. Based on mass and energy conservation law, mass transport theory and electrochemistry principles, the model of humidity dynamics for OC-PEMFC is established in Simulink® environment, including the electrochemical model, mass flow model and thermal model. In the mass flow model, the water retention property and oxygen transfer characteristics of the gas diffusion layer is modelled. The simulation indicates that the internal humidity of OC-PEMFC varies with stack temperature and operating conditions, which has a significant influence on stack efficiency and output performance. In order to maintain a good internal humidity state during operation, this model can be used to determine the optimal stack temperature and for the design of a proper control strategy.

Sign in / Sign up

Export Citation Format

Share Document