Studies on the Effects of NH3 in H2 and Air on the Performance of PEMFC

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6556
Author(s):  
Kefeng Hu ◽  
Daijun Yang
Keyword(s):  
High Purity ◽  
Voltage Drop ◽  
Cell Voltage ◽  
Polarization Test ◽  
Clean Air ◽  
Drop Rate

The effect of NH3 in H2 and in air was investigated at various concentrations ranging from 1.0 ppm to 100 ppm in air and ranging from 0.25 ppm to 10 ppm in fuel. The effect of NH3 on cathode caused an instantaneous decrease in cell voltage which dropped from 0.734 V to 0.712 V in 30 h and drop rates was 0.73 mV/h for 1 ppm; however, the cell voltage dropped to 0.415 V in 1 h for 100 ppm of NH3. The voltage could not be recovered after the polarization test (V-I test) but could be recovered to 84.4% after operation with neat air for 1.5 h and 98.4% after cycle voltammogram (CV). It was found that the voltage drop was obvious, and the drop rate increased with the NH3 concentration in H2. The voltage drop rates at 500 mA/cm2 were 0.54 mV/h for 0.5 ppm of NH3, 0.8 mV/h for 1 ppm, and 2 mV/h for 10 ppm. The voltage could be recovered from 70.6% to 77.3% after discharged with high purity H2 for 24 h, to 92.8% after being purged with clean air for 10 h and to 98.4% after CV scan. The tolerance concentration of NH3 in H2 for 1000 h was 40 ppb, for 2000 h was 20 ppb, and for 5000 h was 9 ppb.

Degradation of Solid Oxide Fuel Cell Cathodes Accelerated at a High Water Vapor Concentration

2010 ◽  
Vol 7 (2) ◽  
Author(s):  
S. H. Kim ◽  
K. B. Shim ◽  
C. S. Kim ◽  
J. T. Chou ◽  
T. Oshima ◽  
...  
Keyword(s):  
Water Vapor ◽  
Voltage Drop ◽  
Cell Voltage ◽  
High Water ◽  
Solid Oxide ◽  
Constant Current ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Oxide Fuel ◽  
Constant Current Density

The influence of water vapor in air on power generation characteristic of solid oxide fuel cells was analyzed by measuring cell voltage at a constant current density, as a function of water vapor concentration at 800°C and 1000°C. Cell voltage change was negligible at 1000°C, while considerable voltage drop was observed at 800°C accelerated at high water vapor concentrations of 20 wt % and 40 wt %. It is considered that La2O3 formed on the (La0.8Sr0.2)0.98MnO3 surface, which is assumed to be the reason for a large voltage drop.

The Design and Development of an Evaluation System for Redox Characteristics of Anode Supported SOFCs Using In-Situ Acoustic Emission and Electrochemical Technique

2012 ◽  
Author(s):  
S. Hashimoto ◽  
H. Watanabe ◽  
T. Sakamoto ◽  
T. Kawada ◽  
K. Yashiro ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Evaluation System ◽  
Voltage Drop ◽  
Cell Voltage ◽  
Test System ◽  
Electrochemical Technique ◽  
Gas Concentration ◽  
Ae Signal ◽  
Cell Test

In this study, a redox evaluation system for anode supported SOFCs using in-situ acoustic emission (AE) and electrochemical technique has been developed. The system consists of a gas blending unit, moisture controlling unit, AE cell evaluation probe, gas cooling exhaust, electrochemical cell test system and AE signal measurement system. The anode supported coin cells, which have the same thickness dimension as practical SOFCs have, can be evaluated under temperature and atmosphere controlled conditions. The oxygen partial pressure in the anodic atmospheres can be gradually controlled from air to reducing atmosphere using the gas blending unit which is connected to 6 gas cylinders. Humidity in the anodic atmospheres can be controlled by moisture controlling unit which consists of 2 bubblers form 0.86% (5°C saturation) up to 80% (94°C saturation). Redox process of the anode can be simulated in this system by controlled three oxidation modes, i.e. O2 gas oxidation, steam oxidation and electrochemical oxidation, which correspond to actual troubles, i.e. gas leakage, degradation of downstream and fuel depletion, respectively. An AE transducer can monitor the cell condition via an inner tube for a guide of exhaust from the cathode. Redox cell test for the anode supported coin cell has been examined at 770°C using this system. After the reduction of the anode substrate in moist H2, current 0.5Acm−2 loaded to the cell. And then H2 gas concentration had been reduced by stages. The cell voltage was down to below −6V after H2 gas concentration was reduced to pH2 = 2%. This drastic cell voltage drop and AE signal generation occurred at the same time. It is considered that Ni re-oxidation with fracture started at this time. Local delamination between anode and electrolyte, and also cracks at the electrolyte and cathode were observed after redox test. It was confirmed that AE sensing is effective for redox evaluation.

Measurement of Liquid Water Accumulation in a Proton Exchange Membrane Fuel Cell With Dead-Ended Anode

2008 ◽  
Author(s):  
Jason B. Siegel ◽  
Denise A. McKay ◽  
Anna G. Stefanopoulou
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Voltage Drop ◽  
Cell Voltage ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Neutron Imaging ◽  
Water Dynamics ◽  
Water Flooding ◽  
Carbon Cloth

The operation and accumulation of liquid water within the cell structure of a polymer electrolyte membrane fuel cell (PEMFC) with a dead-ended anode is observed using neutron imaging. The measurements are performed on a single cell with 53 square centimeter active area, Nafion 111-IP membrane and carbon cloth Gas Diffusion Layer (GDL). Even though dry hydrogen is supplied to the anode via pressure regulation, accumulation of liquid water in the anode gas distribution channels was observed for all current densities up to 566 mA cm−2 and 100% cathode humidification. The accumulation of liquid water in the anode channels is followed by a significant voltage drop even if there is no buildup of water in the cathode channels. Anode purges and cathode surges are also used as a diagnostic tool for differentiating between anode and cathode water flooding. The rate of accumulation of anode liquid water, and its impact on the rate of cell voltage drop is shown for a range of temperature, current density, cathode relative humidity and air stoichiometric conditions. Neutron imaging of the water while operating the fuel cell under dead-ended anode conditions offers the opportunity to observe water dynamics and measured cell voltage during large and repreatable transients.

Dubal Cell Voltage Drop Initiatives Towards Low Energy High Amperage Cells

2014 ◽  
pp. 451-455 ◽  
Author(s):  
Marwan Bastaki ◽  
Abdulla Zarouni ◽  
Bernard Jonqua ◽  
Nadia Ahli ◽  
Lalit Mishra ◽  
...  
Keyword(s):  
Voltage Drop ◽  
Cell Voltage ◽  
Low Energy

Modeling and Simulation of a Photosynthetic Solar Cell

2019 ◽  
Vol 62 (2) ◽  
pp. 475-483
Author(s):  
Sachin A. Bhide ◽  
Jonathan Maisonneuve
Keyword(s):  
Solar Cell ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Voltage Drop ◽  
Plant Cells ◽  
Cell Voltage ◽  
Cell System ◽  
Proton Exchange ◽  
Anode Chamber ◽  
Exchange Membrane

Abstract. Solar energy’s potential as a clean, abundant, and economical energy source can be effectively exploited if it is converted to electricity. Photosynthetic solar cells (PSCs) convert sunlight to electricity by using plant cells via photosynthesis and respiration. These processes can be interrupted to provide a path of lesser resistance for the transfer of protons and electrons in a proton exchange membrane fuel cell system. PSCs require no organic fuel, no active feeding system, and produce carbon-neutral power both day and night. In this article, the mechanisms of photosynthesis that generate electrons and protons in the anode chamber are described and modeled. In addition, the concentrations of various species in the anode and cathode chambers, including plant cells, sugars, reducing agents, and catalysts, are modeled as a function of time and used to simulate the electric potential across the fuel cell. The resulting flow of electrons through the external circuit is described. The influence of non-ideal effects is described and modeled, such as the resistance to the motion of protons, reactants, and products through the electrolyte, which contributes to a voltage drop across the cell. The activation energy required for the chemical reactions also contributes to voltage drop. These dynamics are modeled using differential equations for each species. This model can be used to predict the dynamics of a PSC system under various conditions. Keywords: Cell power, Cell voltage, Microbial fuel cell, Modeling, Photosynthetic solar cell, Solar energy.

The Key to the Problem of Reversible Chemical Hydrogen Storage and Reversible Energy Storage Alike is 12 kJ (mol H2)-1

2019 ◽  
Author(s):  
Roland Hermann Pawelke
Keyword(s):  
Energy Storage ◽  
Hydrogen Storage ◽  
Voltage Drop ◽  
Reaction Pathway ◽  
Cell Voltage ◽  
Ideal Gas ◽  
Battery Cell ◽  
Ideal Gas Law ◽  
Starting Point ◽  
Probable Reaction

<div>This article outlines a potent theoretical formalism illuminating the boundaries to reversible solid hydrogen storage based on the ideal gas law and classic equilibrium thermodynamics. A global picture of chemical reversible hydrogen sorption is unveiled including a thermodynamic explanation of partial reversibility. This is utilized to elucidate a multitude of issues from metal hydride chemistry (as ESI): Highlights are explanations why the substitution of a mere 4 mol % Na by K in Ti-doped NaAlH<sub>4</sub> raises the reversible storage capacity by 42 % and elaboration of the utmost probable reaction pathway in (Rb/K)H-doped Mg(NH<sub>2</sub>)<sub>2</sub>/2LiH. The ESI further contains a demonstration of relevance to electrochemistry by means of the NAS-battery cell, concisely predicting the starting point of the cell voltage drop where experiment shows it to be. The findings of this work allow for a change of paradigm towards the understanding of reversible chemical energy storage and provide a hitherto sorely missing tool of tremendous analytic and predictive power, complementary to experiment.</div>

DUBAL Cell Voltage Drop Initiatives Towards Low Energy High Amperage Cells

2014 ◽  
pp. 451-455 ◽  
Author(s):  
Marwan Bastaki ◽  
Abdulla Zarouni ◽  
Bernard Jonqua ◽  
Nadia Ahli ◽  
Lalit Mishra ◽  
...  
Keyword(s):  
Voltage Drop ◽  
Cell Voltage ◽  
Low Energy

The Master Key to the Problem of Reversible Chemical Hydrogen Storage and Reversible Energy Storage Alike is 12 kJ (mol H2)-1

2019 ◽  
Author(s):  
Roland Hermann Pawelke
Keyword(s):  
Energy Storage ◽  
Hydrogen Storage ◽  
Voltage Drop ◽  
Reaction Pathway ◽  
Cell Voltage ◽  
Ideal Gas ◽  
Battery Cell ◽  
Ideal Gas Law ◽  
Starting Point ◽  
Probable Reaction

<div>This article outlines a potent theoretical formalism illuminating the boundaries to reversible solid hydrogen storage based on the ideal gas law and classic equilibrium thermodynamics. A global picture of chemical reversible hydrogen sorption is unveiled including a thermodynamic explanation of partial reversibility. This is utilized to elucidate a multitude of issues from metal hydride chemistry (as ESI): Highlights are explanations why the substitution of a mere 4 mol % Na by K in Ti-doped NaAlH<sub>4</sub> raises the reversible storage capacity by 42 % and elaboration of the utmost probable reaction pathway in (Rb/K)H-doped Mg(NH<sub>2</sub>)<sub>2</sub>/2LiH. The ESI further contains a demonstration of relevance to electrochemistry by means of the NAS-battery cell, concisely predicting the starting point of the cell voltage drop where experiment shows it to be. The findings of this work allow for a change of paradigm towards the understanding of reversible chemical energy storage and provide a hitherto sorely missing tool of tremendous analytic and predictive power, complementary to experiment.</div>

Observations oh Nucleation and Growth of Voids in Nickel

1970 ◽  
Vol 28 ◽  
pp. 414-415
Author(s):  
J. L. Brimhall ◽  
H. E. Kissinger ◽  
B. Mastel
Keyword(s):  
High Purity ◽  
Growth Stage ◽  
Elevated Temperatures ◽  
Early Growth ◽  
Nucleation And Growth ◽  
Pure Nickel ◽  
Different Temperatures ◽  
Total Fluence ◽  
Neutron Exposure ◽  
Growth Of Voids

Some information on the size and density of voids that develop in several high purity metals and alloys during irradiation with neutrons at elevated temperatures has been reported as a function of irradiation parameters. An area of particular interest is the nucleation and early growth stage of voids. It is the purpose of this paper to describe the microstructure in high purity nickel after irradiation to a very low but constant neutron exposure at three different temperatures.Annealed specimens of 99-997% pure nickel in the form of foils 75μ thick were irradiated in a capsule to a total fluence of 2.2 × 1019 n/cm2 (E > 1.0 MeV). The capsule consisted of three temperature zones maintained by heaters and monitored by thermocouples at 350, 400, and 450°C, respectively. The temperature was automatically dropped to 60°C while the reactor was down.

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