Papers by Keyword: PEMFC

Abstract: This paper summarizes the performance of PEMFC catalyst layer. The main materials used as catalyst in PEMFC are presented as well as the typical structure of MEA. Functions of catalyst during the operation of PEMFC are discussed in detail. Catalyst plays a key role in accelerating the rate of electrochemical reaction, especially that of reduction with oxygen in cathode. But its high cost and low tolerance for has resulted in a severe fact that essentially all the longevity of PEMFC which adopts precious metal-platinum or platinum alloys as catalysts is relatively short. A sputter deposited method is presented to enhance the efficiency of catalyst in PEMFC, while whether this method would bring about a striking effect or not remains worth further researches.

Abstract: In this article, it takes the small power mechanical exoskeleton with fuel cells as the main application target. Based on different two hydrogen supply methods, high-pressure hydrogen cylinders and portable metal hydride hydrogen cylinders, the box structure and shape design of small power PEMFC is made. It cannot only provide power as a independent component using high-pressure hydrogen cylinders supply gas equipment, but also as transportation power or portable equipment by installing rapidly metal hydride hydrogen storage cylinders, which realized the use of reliability, flexibility and convenience for mechanical exoskeleton.

Abstract: The mode experiment is respectively done under condition of different amount of gas supply, different shape of gas admission room, different cross-section shape of flow channel. Results show that pressure descend of U shape cross-section slot is smaller than the rectangle cross-section slot in the equal fault stream section situation, so flow distribution characteristic of U shape cross-section slot is better. The experiment results are consistent with numerical simulation results. In addition, numerical simulation results also indicate that the mass of gas diffusing from U shape cross-section slot to the diffusion layer is over greater, and U shape cross-section flow channel has a higher gas utilization ratio.

Abstract: Hydrogen energy fuel cell is one of the clean/green energy solutions for the environmental pollution, global warming, and petroleum energy shortage. This study investigates the dynamic characteristic of the green hydrogen energy fuel cell: Proton Exchange Membrane Fuel Cell (PEMFC). PEMFC has been adopted to be the power supplier of the vehicle, small train, etc. A lot of researchers aim on pure electrical property analysis. However, to put PEMFC power system on the road, some mechanical properties of the system should also been examined. In this paper, the dynamic characteristic of a single PEMFC is studied. A single PEMFC (L112×W82×D6 mm) is set up and measured for the time and frequency response. Several fundamental modes are found experimentally which should be avoid during operation period of PEMFC especially in a moving vehicle.

Abstract: Polymer electrolyte membrane fuel cell (PEFMC) or also known as proton exchange membrane fuel cell is a chemical conversion device that converts hydrogen and oxygen into electrical energy, heat, and water. One of the most important components of PEMFC is bipolar plate, in which it allows for electrons to flow from the anode to the cathode. The objective of this study was to analyze the effect of the addition of multi walled carbon nanotubes (MWCNT) to increase the mechanical and electrical properties of bipolar plate carbon polymer composite. We utilized graphite waste product from electric arc smelting as reinforcementand carbon black made from coconut husk by pyrolysis process as a filler. Bipolar plates were made by compression moulding method at a pressure of 55 MPa and a temperature of 100 o C for 4 hours. Characterization in this study includes density testing, porosity testing, flexural testing, electrical conductivity testing, and observation of the flexural fracture morphology using FESEM. Based on this study, it showed that the addition of 5 %wt MWCNT yielded optimal properties of the bipolar plate (the density was 1.51 g/cm3, the value of porosity was 1.94 %, the flexural strength was 63.31 MPa, and the electrical conductivity was 2.30 S/cm). In conclusion, adding MWCNT as reinforcement in PEMC bipolar plates could reduce the density and the porosity. Thus, it could improve the electrical conductivity and flexural strength of the bipolar plate carbon polymer composites.

Abstract: The performance of a proton exchange membrane fuel cell (PEMFC) under the fuel control system was investigated experimentally using dry hydrogen and oxygen gas. In this study, experiments have been carried out on the unit cell with the active area of 25cm2. Both sides of outflow lines were closed by valves. This investigation focuses on the low-power system which has a fuel flow control unit. The change of internal pressure in fuel cell and the checked system load were used as the control conditions for the solenoid valve. As the system loads were changed unexpectedly, the on/off control of fuel line was proposed as the way to supply hydrogen gas efficiently into the fuel cell. As a result, it was shown that the proposed procedures can display the load variation and increase the power request. Furthermore, this study could be beneficial for the fuel saving and the safety of fuel cell system.

Abstract: In order to increase the corrosion resistant and reduce the interfacial contact resistance of the stainless steel, the duplex treatment technology of electroplating Cr and plasma-assisted nitriding process for AISI 304SS is exploited. X-ray diffraction (XRD), scanning electron microscopy (SEM) and the electrochemical tests such as potentiodynamic and potentiostatic polarization in the simulation PEMFC environments are measured. XRD showed that the surface layer of the 540 ° C and 550 ° C were Cr and Cr2N; the 580 °C was the CrN and Cr₂N. The nitride sample of the 550 °C could see the closure process of the mesh crack. Compared with the simulated PEMFC anode environment, higher corrosion resistance was showed in the simulated PEMFC cathode environment. The current density of the 540°C, 550°C and 580°C samples were negative at the operating potential -0.1V, which would provide cathodic protection to the metallic bipolar plates. In the simulated cathode environment, the current densities of the three samples were quickly stabilized, the surface quickly formed a stable passive film.

Abstract: A computer simulation program is presented for simulating the characteristic parameters of proton exchange membrane fuel cells (PEMFC) by using the MATLAB/SIMULINK and Visual Basic (VB). The simulation program is developed based on the empirical models for PEMFC. The simulation results show that the developed simulation program can be used as a useful tool for simulating the characteristic parameters of PEMFC.

Abstract: Sulfonated poly (ethersulfone) s (S-PDHTPEs) were prepared from 4,4-(2,2-diphenylethenylidene) bisphenol (DHTPE), 4,4-sulfonyldiphenol, 4-fluorophenylsulfone using potassium carbonate, and followed sulfonation reaction with conc. sulfuric acid. DHTPE is a conjugated structure, which enables to form planar conformation between aromatic rings, and selectively sufonated on phenyl rings of polymer side chain. Composite membranes were prepared with copolymers and SiO₂ nanoparticles (20 nm, 4~10%wt). The composite membranes were cast from DMSO. A series of composite membranes structures and characteristic were evaluated by the ¹H-NMR spectroscopy, and thermal stabilities. The membranes were performed by ion exchange capacity (IEC), water uptake and proton conductivity as a function of degree of sulfonation.

Abstract: The dynamic model of the air supply system for a proton exchange membrane fuel cell (PEMFC) stack is developed in this paper. The PEMFC cathode/anode, and air supply system including a compressor, a motor, and a supply manifold(SM) are modeled; the compressor performance map is identified based on a fuzzy neural network (FNN). The PEMFC air supply system is simulated by using Matlab environment. The simulation results show that the proposed models can effectively represent the dynamic characteristics of the system components, and lay the foundation for the control strategy design of the PEMFC air supply flow.