in situ Measuring of Temperature and Humidity within the Membrane Electrode Assembly by Micro-Sensors

2007 ◽  
pp. 377-380
Author(s):  
C. Y. Lee ◽  
S. J. Lee ◽  
G. W. Wu
Keyword(s):  
Membrane Electrode Assembly ◽  
Membrane Electrode ◽  
Temperature And Humidity

Integration of Micro Array Sensors in the MEA on Diagnosis of Micro Fuel Cells

2007 ◽  
Vol 364-366 ◽  
pp. 855-860
Author(s):  
Chi Yuan Lee ◽  
Shuo Jen Lee ◽  
Guan Wei Wu
Keyword(s):  
Fuel Cells ◽  
High Sensitivity ◽  
Membrane Electrode Assembly ◽  
Membrane Electrode ◽  
Humidity Sensors ◽  
Micro Electro Mechanical Systems ◽  
Mems Fabrication ◽  
Temperature And Humidity ◽  
Micro Array

The temperature and humidity conditions of a membrane electrode assembly (MEA) determine the performance of fuel cells. The volume of traditional temperature and humidity sensors is too large to allow them to be used to measure the distribution of temperature and humidity in the MEA of fuel cells. Measurements cannot necessarily be made where required. They measure only the temperature and humidity distribution outside the fuel cells and yield results with errors that exceed those of measurements made in MEA. Therefore, in this study, micro-electro-mechanical-systems (MEMS) fabrication technology was employed to fabricate an array of micro sensors to monitor in situ the temperature and humidity distributions within the MEA of fuel cells. In this investigation, an array of micro temperature and humidity sensors was made from gold on the MEA. The advantages of array micro gold temperature and humidity sensors are their small volume, which enable them to be placed on MEA and their high sensitivity and accuracy. The dimensions of the temperature and humidity sensors are 180μm × 180μm and 180μm × 220μm, respectively. The experiment involves temperatures from 30 to 100 °C. The resistance varied from 23.084 to 28.196 /. The experimental results reveal that the temperature is almost linearly related to the resistance and the accuracy and sensitivity are less than 0.3 °C and 3.2×10-3/°C, respectively. The humidity sensor showed that the capacitance changed from 15.76 to 17.95 pF, the relative humidity from 20 to 95 %RH, and the accuracy and sensitivity were less than 0.25 %RH and 0.03 pF/%RH.

In-Situ Measurements of Water Transfer Due to Different Mechanisms in a PEM Fuel Cell

2007 ◽  
Author(s):  
Attila Husar ◽  
Andrew Higier ◽  
Hongtan Liu
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Pem Fuel Cell ◽  
Membrane Electrode Assembly ◽  
Pem Fuel Cells ◽  
Water Transfer ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Order Of Magnitude

Water management is of critical importance in a proton exchange membrane (PEM) fuel cell. Yet there are very limited studies of water transfer through the membrane and no data are available for water transfer due to individual mechanisms through the membrane electrode assembly (MEA) in an operational fuel cell. Thus it is the objective of this study to measure water transfer through the MEA due to different mechanisms through the membrane electrode assembly (MEA) of an operational PEM fuel cell. The three different mechanisms of water transfer, i.e., electro-osmotic drag, diffusion and hydraulic permeation were isolated by specially imposed boundary conditions. Therefore water transfer through the MEA due to each mechanism could be measured separately. In this study, all the data were collected in an actual assembled operational fuel cell, and some of the data were collected while the fuel cell was generating power. The measured results showed that water transfer due to hydraulic permeation, i.e. the pressure difference between the anode and cathode is at least an order of magnitude lower than those due to other two mechanisms. The data for water transfers due to electro-osmosis and diffusion through the MEA are in good agreement with some of the data and model predications in the literature for the membrane. The methodology used in this study is simple and can be easily adopted for in-situ water transfer measurement due to different mechanisms in actual PEM fuel cells without any cell modifications.

Discharge of a Segmented Polymer Electrolyte Membrane Fuel Cell

2004 ◽  
Vol 2 (2) ◽  
pp. 111-120 ◽  
Author(s):  
P. Berg ◽  
K. Promislow ◽  
J. Stumper ◽  
B. Wetton
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Water Distribution ◽  
Polymer Electrolyte Membrane ◽  
Parameter Tuning ◽  
Membrane Electrode Assembly ◽  
Membrane Electrode ◽  
Transient Model ◽  
Electrolyte Membrane

We present a transient model for an electrically segmented polymer electrolyte membrane (PEM) fuel cell which is run until extinction from a finite oxygen supply. The experimental cell is divided into 16 electrically isolated pucks which are fed oxygen from a small reserve and hydrogen from a conventional flow field. The experimental voltage and through-plane current in each puck, and puck-to-puck currents are recorded and compared to computed profiles. Seven qualitative characteristics of the current profiles during discharge are identified. These are used as targets for parameter tuning, from which puck-to-puck water distribution within the membrane electrode assembly (MEA) is inferred. The model is sensitive to system parameters, and holds promise as an in situ diagnostic tool for tracking this distribution by using MEA oxygen transport characteristics.

In-Situ Diagnostics of PEFCs

2009 ◽  
Author(s):  
Kaspar Andreas Friedrich ◽  
Norbert Wagner ◽  
Mathias Schulze
Keyword(s):  
Current Density ◽  
Measurement Techniques ◽  
Current Density Distribution ◽  
Electrical Energy ◽  
Membrane Electrode Assembly ◽  
Operating Conditions ◽  
Membrane Electrode ◽  
Mass Transport Effects ◽  
Electrical Energy Production

Polymer electrolyte fuel cells (PEFCs) are one of the most interesting alternatives for a pollution-free electrical energy production in many applications where a highly reliable source of electricity is needed. One of the major challenges in the development of PEFCs is to exploit the whole capacity that is inherent to a given membrane electrode assembly (MEA). In practice, certain obstacles remain to be overcome like local mass transport effects, non-uniformly manufactured MEAs, locally varying contact resistances, water management and temperature gradients. All these parameters lead to an inhomogeneous electrochemical activity over the electrode area. Consequently, a variation and a gradient of the current density over the cell area occurs which tends to result in inferior performance and low durability of a PEFC. For the determination of current density distribution different in-situ methods and measurement techniques are applied. Results can be used to improve cell components, to validate models and to detect inappropriate detrimental operating conditions of the fuel cell.

Development and Application of a Sample Holder for In Situ Gaseous TEM Studies of Membrane Electrode Assemblies for Polymer Electrolyte Fuel Cells

2017 ◽  
Vol 23 (5) ◽  
pp. 945-950 ◽  
Author(s):  
Takeo Kamino ◽  
Toshie Yaguchi ◽  
Takahiro Shimizu
Keyword(s):  
Fuel Cells ◽  
Polymer Electrolyte ◽  
Structural Changes ◽  
Membrane Electrode Assembly ◽  
Polymer Electrolyte Fuel Cells ◽  
Polymer Electrolyte Fuel Cell ◽  
Membrane Electrode ◽  
Sample Holder ◽  
Electrode Assemblies

AbstractPolymer electrolyte fuel cells hold great potential for stationary and mobile applications due to high power density and low operating temperature. However, the structural changes during electrochemical reactions are not well understood. In this article, we detail the development of the sample holder equipped with gas injectors and electric conductors and its application to a membrane electrode assembly of a polymer electrolyte fuel cell. Hydrogen and oxygen gases were simultaneously sprayed on the surfaces of the anode and cathode catalysts of the membrane electrode assembly sample, respectively, and observation of the structural changes in the catalysts were simultaneously carried out along with measurement of the generated voltages.

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