Design and Testing of a Unitized Regenerative Fuel Cell

2009 ◽  
Vol 6 (3) ◽  
Author(s):  
Jeremy Fall ◽  
Drew Humphreys ◽  
S. M. Guo
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Platinum Catalyst ◽  
Oxygen Electrode ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Hydrogen Electrode ◽  
Iridium Catalysts ◽  
Regenerative Fuel Cell

A unitized regenerative fuel cell (URFC) is designed and tested for energy conversion and storage under the support of a NASA funded student design project. The URFC is of the proton exchange membrane type with an active cell area of 25cm2. In the URFC design, liquid water is stored internally to the fuel cell within graphite bipolar plates while hydrogen and oxygen gases, electrolyzed from water, are stored in containers external to the fuel cell. A spraying technique is used to produce a functional membrane electrode assembly. Catalyst ink is prepared using E-TEK Inc. platinum and iridium catalysts loaded on Vulcan XC-72. Platinum catalyst is used for the hydrogen electrode. 50wt% platinum∕50wt% iridium catalyst is used for the oxygen electrode. The metal weight on carbon is 30% for both the platinum and iridium catalysts. Water management within the fuel cell is handled by treatment of the gas diffusion layer with a Teflon emulsion to create the proper balance of hydrophobic and hydrophilic pores. The single cell unit is tested in either fuel cell mode or electrolysis mode for different catalyst loadings. Polarization curves for the URFC are generated to evaluate system performance.

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.

scholarly journals Modifying the Catalyst Layer Using Polyvinyl Alcohol for the Performance Improvement of Proton Exchange Membrane Fuel Cells under Low Humidity Operations

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1865 ◽  
Author(s):  
Prathak Jienkulsawad ◽  
Yong-Song Chen ◽  
Amornchai Arpornwichanop
Keyword(s):  
Fuel Cell ◽  
Polyvinyl Alcohol ◽  
Proton Exchange Membrane ◽  
Catalyst Layer ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Power Sources ◽  
Low Humidity ◽  
Exchange Membrane

A proton exchange membrane fuel cell (PEMFC) system for the application of unmanned aerial vehicles is equipped without humidifiers and the cathode channels of the stack are open to the environment due to limited weight available for power sources. As a result, the PEMFC is operated under low humidity conditions, causing membrane dehydration, low performance, and degradation. To keep the generated water within the fuel cell to humidify the membrane, in this study, polyvinyl alcohol (PVA) is employed in the fabrication of membrane electrode assemblies (MEAs). The effect of PVA content, either sprayed on the gas diffusion layer (GDL) or mixed in the catalyst layer (CL), on the MEA performance is compared under various humidity conditions. The results show that MEA performance is increased with the addition of PVA either on the GDL or in the CL, especially for non-humidified anode conditions. The result suggested that 0.03% PVA in the anode CL and 0.1% PVA on the GDL can improve the MEA performance by approximately 30%, under conditions of a non-humidified anode and a room-temperature-humidified cathode. However, MEAs with PVA in the anode CL show better durability than those with PVA on the GDL according to measurement with electrochemical impedance spectroscopy.

scholarly journals Exergetic Performance of a PEM Fuel Cell with Laser-Induced Graphene as the Microporous Layer

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6232
Author(s):  
Viorel Ionescu ◽  
Adriana Elena Balan ◽  
Alexandra Maria Isabel Trefilov ◽  
Ioan Stamatin
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Pyrolytic Carbon ◽  
Membrane Electrode Assembly ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Membrane Electrode ◽  
Ohmic Loss ◽  
Microporous Layer

The microporous layer (MPL) constitutes a critical component of the gas diffusion layer within the membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEM FC). The MPL plays a fundamental role in various processes during FC operation: control of membrane humidification, heat distribution throughout the MEA, excess water removal from the cathode, and transportation of fuel to the reaction sites. Previously, we investigated the performance of a fuel cell unit employing an MPL based on laser-induced graphene (LIG) produced by the laser pyrolysis of polymeric (polyimide) substrates. The prototype LIG-based unit was tested over the typical range of relative humidity and temperature conditions. The polarization curves observed in that study displayed broad ohmic loss regions and high stability along the concentration loss regions, an interesting electrical behavior that justified developing the present voltage-current density study for the same FC prototype compared to one bearing a commercial pyrolytic carbon black MPL. The same operating conditions as in the first study were applied, in order to properly compare the performance efficiencies between the two systems; these are evaluated by considering the thermodynamic losses influence on the exergy efficiency, to exceed any limitations inherent in the classical energy efficiency analysis.

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.

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