Thermodynamic View on the Loss Mechanisms in PEM-Fuel Cells

2005 ◽  
Author(s):  
S. Kabelac ◽  
M. Siemer
Keyword(s):  
Fuel Cell ◽  
Entropy Production ◽  
High Efficiency ◽  
Driving Forces ◽  
Pem Fuel Cells ◽  
Production Rates ◽  
Starting Point ◽  
Model Equations ◽  
Conversion Efficiencies ◽  
Loss Mechanisms

The fuel cell, which is a highly promising candidate for high efficiency energy conversion, is not reaching expected conversion efficiencies of η > 0,5 yet. Parallel to standard explanations of loss mechanisms by means of overvoltages, a thermodynamic view of addressing irreversibilities by calculating local entropy production rates is helpful. Entropy production rates are calculated by multiplying local transport fluxes with appropriate driving forces, i.e., gradients of temperature, chemical potentials and electric potentials. These gradients have to be calculated by solving the set of constitutive balance equations. Before this tedious task is done, simplified model equations have to be used. The reversible fuel cell is the starting point of analysis. Results for a one-dimensional PEMFC are shown.

Effect of Channel Geometry on Two-Phase Flow Structure in Fuel Cell Gas Channels

2011 ◽  
Author(s):  
Cody D. Rath ◽  
Satish G. Kandlikar
Keyword(s):  
Water Management ◽  
Fuel Cell ◽  
High Efficiency ◽  
Polymer Electrolyte Membrane ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Ex Situ ◽  
Two Phase ◽  
Electrolyte Membrane ◽  
Excess Water

Water management issues continue to be a major concern for the performance of polymer electrolyte membrane (PEM) fuel cells. Maintaining the optimal amount of hydration can ensure that the cell is operating properly and with high efficiency. There are several components that can affect water management, however one area that has received increased attention is the interface between the gas diffusion layer (GDL) and the gas reactant channels where excess water has a tendency to build up and block reactant gasses. One key parameter that can affect this build up is the geometry of the microchannels. The work presented here proposes an optimal trapezoidal geometry which will aid in the removal of excess water in the gas channels. The Concus-Finn condition is applied to the channel surfaces and GDL to ensure the water will be drawn away from GDL surface and wicked to the top corner of the channel. An ex situ setup is designed to establish the validity of the Concus-Finn application. Once validated, this condition is then used to design optimal channel geometries for water removal in a PEM fuel cell gas channel.

scholarly journals The identification of optimal operating parameters under high energy efficiency conditions for a single polymer electrolyte membrane (PEM) fuel cell

2022 ◽  
Vol 960 (1) ◽  
pp. 012002
Author(s):  
I G Bratu ◽  
R F Ene ◽  
M Vulpe ◽  
F Uleanu ◽  
D Giosanu
Keyword(s):  
Fuel Cell ◽  
Gas Flow ◽  
High Efficiency ◽  
Power Level ◽  
Polymer Electrolyte Membrane ◽  
Pem Fuel Cell ◽  
High Energy ◽  
Pem Fuel Cells ◽  
Internal Resistance ◽  
Polymeric Membrane

Abstract The performance of PEM fuel cells is influenced by several factors such as: the operating temperature of the cell, the reactant gas flow, work pressures, the reaction gas humidity. In the present work we aimed to identify the optimal values of these parameters for operation of a PEM cell to achieve maximum power in conditions of high efficiency; the technological possibilities of its use in a portable energy application have been evaluated. Experimental measurements regarding the integrating polymeric membrane in three different fuel cell construction designed were performed. The influence of the mechanical compression of the GDL diffusion layer on the total internal resistance of the cell was achieved by comparative analysis of the polarization curves. It was found that as the deformation level of the MEA increases, the power generated by the battery increases progressively. The resulting experimental data subsequently allowed the design and implementation of a PEM fuel cell assembly, fully functional at power level, corresponding to the number of constituent elements.

Effects of CO on Performance of HT-PEM Fuel Cells

2013 ◽  
Vol 724-725 ◽  
pp. 723-728
Author(s):  
Xue Nan Zhao ◽  
Hong Sun ◽  
Zhi Jie Li
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Large Scale ◽  
Proton Exchange Membrane ◽  
High Efficiency ◽  
Electrochemical Reaction ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Proton Exchange ◽  
Fuel Cell Performance

High temperature proton exchange membrane (HT-PEM) fuel cell is considered as one of the most probable fuel cells to be large-scale applied due to characteristics of high efficiency, friendly to environment, low fuel requirement, ease water and heat management, and so on. However, carbon monoxide (CO) content in fuel plays an important role in the performance of HT-PEM fuel cells. Volt-ampere characteristics and AC impedance of HT-PEM fuel cell are tested experimentally in this paper, and effects of CO in fuel on its performance are analyzed. The experimental results show that CO in fuel increases remarkably the Faraday resistance of HT-PEM fuel cell and decreases the electrochemical reaction at anode; the more CO content in fuel is, the less HT-PEM fuel cell performance is; with the increasing cell temperature, the electrochemical reaction on the surface of catalyst at anode is improved and the poisonous effects on the HT-PEM fuel cell are alleviated.

scholarly journals Design and Optimization of a Radial Inflow Turbine for Use with a Low Temperature ORC

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8526
Author(s):  
Richard Symes ◽  
Tchable-Nan Djaname ◽  
Michael Deligant ◽  
Emilie Sauret
Keyword(s):  
Fuel Cell ◽  
Low Temperature ◽  
High Efficiency ◽  
Waste Heat ◽  
Fluid Dynamic ◽  
Organic Rankine Cycle ◽  
Pem Fuel Cells ◽  
Small Scale ◽  
Heat Sources ◽  
Radial Inflow Turbine

This study aims to design and optimize an organic Rankine cycle (ORC) and radial inflow turbine to recover waste heat from a polymer exchange membrane (PEM) fuel cell. ORCs can take advantage of low-quality waste heat sources. Developments in this area have seen previously unusable, small waste heat sources become available for exploitation. Hydrogen PEM fuel cells operate at low temperatures (70 °C) and are in used in a range of applications, for example, as a balancing or backup power source in renewable hydrogen plants. The efficiency of an ORC is significantly affected by the source temperature and the efficiency of the expander. In this case, a radial inflow turbine was selected due to the high efficiency in ORCs with high density fluids. Small scale radial inflow turbines are of particular interest for improving the efficiency of small-scale low temperature cycles. Turbines generally have higher efficiency than positive displacement expanders, which are typically used. In this study, the turbine design from the mean-line analysis is also validated against the computational fluid dynamic (CFD) simulations conducted on the optimized machine. For the fuel cell investigated in this study, with a 5 kW electrical output, a potential additional 0.7 kW could be generated through the use of the ORC. The ORC’s output represents a possible 14% increase in performance over the fuel cell without waste heat recovery (WHR).

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.

scholarly journals A Review of Hydrogen Purification Technologies for Fuel Cell Vehicles

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 393
Author(s):  
Zhemin Du ◽  
Congmin Liu ◽  
Junxiang Zhai ◽  
Xiuying Guo ◽  
Yalin Xiong ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Carbon Emission ◽  
High Efficiency ◽  
Impurity Content ◽  
Fuel Cell Vehicle ◽  
Research Progress ◽  
Hydrogen Purification ◽  
Fuel Cell Vehicles ◽  
Low Carbon

Nowadays, we face a series of global challenges, including the growing depletion of fossil energy, environmental pollution, and global warming. The replacement of coal, petroleum, and natural gas by secondary energy resources is vital for sustainable development. Hydrogen (H2) energy is considered the ultimate energy in the 21st century because of its diverse sources, cleanliness, low carbon emission, flexibility, and high efficiency. H2 fuel cell vehicles are commonly the end-point application of H2 energy. Owing to their zero carbon emission, they are gradually replacing traditional vehicles powered by fossil fuel. As the H2 fuel cell vehicle industry rapidly develops, H2 fuel supply, especially H2 quality, attracts increasing attention. Compared with H2 for industrial use, the H2 purity requirements for fuel cells are not high. Still, the impurity content is strictly controlled since even a low amount of some impurities may irreversibly damage fuel cells’ performance and running life. This paper reviews different versions of current standards concerning H2 for fuel cell vehicles in China and abroad. Furthermore, we analyze the causes and developing trends for the changes in these standards in detail. On the other hand, according to characteristics of H2 for fuel cell vehicles, standard H2 purification technologies, such as pressure swing adsorption (PSA), membrane separation and metal hydride separation, were analyzed, and the latest research progress was reviewed.

PVD Coated Bipolar Plates for PEM Fuel Cells

2005 ◽  
Vol 2 (4) ◽  
pp. 290-294 ◽  
Author(s):  
Shuo-Jen Lee ◽  
Ching-Han Huang ◽  
Yu-Pang Chen ◽  
Chen-Te Hsu
Keyword(s):  
Corrosion Resistance ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Physical Vapor Deposition ◽  
Corrosion Current ◽  
Pem Fuel Cells ◽  
Bipolar Plates ◽  
Coating Materials ◽  
Pvd Coating ◽  
Simulated Fuel

Aluminum was considered a good candidate material for bipolar plates of the polymer electrolyte membrane (PEM) fuel cells due to its low cost, light weight, high strength and good manufacturability. But there were problems of both chemical and electrochemical corrosions in the PEM fuel cell operating environment. The major goals of this research are to find proper physical vapor deposition (PVD) coating materials which would enhance surface properties by making significant improvements on corrosion resistance and electrical conductivity at a reasonable cost. Several coating materials had been studied to analyze their corrosion resistance improvement. The corrosion rates of all materials were tested in a simulated fuel cell environment. The linear polarization curve of electrochemical method measured by potentiostat instrument was employed to determine the corrosion current. Results of the corrosion tests indicated that all of the coating materials had good corrosion resistance and were stable in the simulated fuel cell environment. The conductivities of the coated layers were better and the resistances changed very little after the corrosion test. At last, single fuel cells were made by each PVD coating material. Fuel cell tests were conducted to determine their performance w.r.t. that was made of graphite. The results of fuel cell tests indicated that metallic bipolar plates with PVD coating could be used in PEM fuel cells.

scholarly journals Monte Carlo Modeling and Design of Photon Energy Attenuation Layers for >10× Quantum Yield Enhancement in Si-Based Hard X-ray Detectors

Instruments ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 17
Author(s):  
Eldred Lee ◽  
Kaitlin M. Anagnost ◽  
Zhehui Wang ◽  
Michael R. James ◽  
Eric R. Fossum ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Quantum Yield ◽  
Photon Energy ◽  
High Efficiency ◽  
High Energy ◽  
Yield Enhancement ◽  
X Ray ◽  
Simulation Results ◽  
Conversion Efficiencies

High-energy (>20 keV) X-ray photon detection at high quantum yield, high spatial resolution, and short response time has long been an important area of study in physics. Scintillation is a prevalent method but limited in various ways. Directly detecting high-energy X-ray photons has been a challenge to this day, mainly due to low photon-to-photoelectron conversion efficiencies. Commercially available state-of-the-art Si direct detection products such as the Si charge-coupled device (CCD) are inefficient for >10 keV photons. Here, we present Monte Carlo simulation results and analyses to introduce a highly effective yet simple high-energy X-ray detection concept with significantly enhanced photon-to-electron conversion efficiencies composed of two layers: a top high-Z photon energy attenuation layer (PAL) and a bottom Si detector. We use the principle of photon energy down conversion, where high-energy X-ray photon energies are attenuated down to ≤10 keV via inelastic scattering suitable for efficient photoelectric absorption by Si. Our Monte Carlo simulation results demonstrate that a 10–30× increase in quantum yield can be achieved using PbTe PAL on Si, potentially advancing high-resolution, high-efficiency X-ray detection using PAL-enhanced Si CMOS image sensors.

Hybrid direct carbon fuel cell-thermoradiative systems for high-efficiency waste-heat recovery

2019 ◽  
Vol 198 ◽  
pp. 111842
Author(s):  
Xin Zhang ◽  
Jianying Du ◽  
Yee Sin Ang ◽  
Jincan Chen ◽  
Lay Kee Ang
Keyword(s):  
Fuel Cell ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
High Efficiency ◽  
Waste Heat ◽  
Direct Carbon Fuel Cell
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