This paper modeled a single cell with active area of nearly 50 cm2 by the CFD software of Fluent and discussed the influence of cooling water on the temperature distribution of membrane. The results show that most of ...
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This paper modeled a single cell with active area of nearly 50 cm2 by the CFD software of Fluent and discussed the influence of cooling water on the temperature distribution of membrane. The results show that most of the cooling water's temperature is low, the effect of heat exchange is bad;At the high current density, cooling water with the same flow direction of reactant gas has better effect on improving temperature distribution in the fuel cell. Increasing overall flow velocity and depressing the inlet temperature of cooling water has little effect on improving temperature distribution.
High alumina cement/graphite conductive composites were prepared by mold pressing at room temperature. Electrical conductivity was measured and the composite morphology was investigated by scanning electron microscope...
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High alumina cement/graphite conductive composites were prepared by mold pressing at room temperature. Electrical conductivity was measured and the composite morphology was investigated by scanning electron microscope (SEM). The heat stability and water content of conductive composites were also studied under proton exchange membrane fuel cell (PEMFC) operating temperature. The test results show that the percolation phenomenon is exist in the composite bipolar plate, the threshold value is 8%-10%;moreover, the composite bipolar plate has excellent heat stability and self- humidification.
Metal-N-H is considered as one of the most-potential hydrogen storage materials as on-board applications for its high gravimetric hydrogen content at relatively gentle condition. The research development of conversion...
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Metal-N-H is considered as one of the most-potential hydrogen storage materials as on-board applications for its high gravimetric hydrogen content at relatively gentle condition. The research development of conversion from Li-N-H to Mg-N-H is presented, two types of possible reaction mechanisms are discussed and three amide-synthesizing methods are introduced. The unsolved problems of development and application of the Metal-N-H system are also generalized.
Different humidification of proton exchange membrane fuel cells were investigated using PEM module of fluent software. Influence of different humidification degrees on performance of PEM fuel cell was studied, especia...
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Different humidification of proton exchange membrane fuel cells were investigated using PEM module of fluent software. Influence of different humidification degrees on performance of PEM fuel cell was studied, especially influence of Concentration polarization on PEM fuel cell performance was discussed in the high current density. 0%, 50% and 100% humidification of 80°C cathode gas were contrasted. The results showed that 100% humidification was better at low current density, while at high current density, 50% humidification was better. The relation between the performance of fuel cell and the distribution of O2 and H2O mol concentration on the interface between cathode diffusion layer and catalyst layer were analyzed. The results showed only partial regions of catalyst layer exist concentration polarization. Taking properly humidification can obtain higher performance in different current density.
The α-Fe fibers were prepared successfully by the method of electrodepositing in porous alumina template. The results indicated that the diameter of the fibers was 300 nm and the length of them increased along with t...
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The α-Fe fibers were prepared successfully by the method of electrodepositing in porous alumina template. The results indicated that the diameter of the fibers was 300 nm and the length of them increased along with the electrodepositing time increasing. The saturation magnetization per m2 of the iron fibers increased with the increasing of the length/diameter ratio, but the coercive field decreased.
Microstructures of highly compact IrO2 films, deposited on Si (100) substrates by pulsed laser deposition of Ir target at different oxygen partial pressures, were characterized with X-ray diffraction (XRD), Raman spec...
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Microstructures of highly compact IrO2 films, deposited on Si (100) substrates by pulsed laser deposition of Ir target at different oxygen partial pressures, were characterized with X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM).The results show that the films, grown at an oxygen partial pressure of 20 Pa and at a substrate temperature in the range of 250°-500°C, are polycrystalline and that as the substrate temperature rises, IrO2 surface becomes rougher with bigger grains.
The relations between composition, structure, chemical bond and property of TiC, FeAl, Fe3Al and composites of TiC/Fe-Al series were studied by using density function theory and discrete variation method (DFT-DVM). Th...
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The relations between composition, structure, chemical bond and property of TiC, FeAl, Fe3Al and composites of TiC/Fe-Al series were studied by using density function theory and discrete variation method (DFT-DVM). There were strong ionic and covalent interacts among the interfaces of TiC/FeAl and TiC/Fe3Al composites. The ionic bonds became weak, and the covalent was strong gradually from the single phase of TIC, FeAl or Fe3Al, to composite TiC/FeAl or TiC/Fe3Al. The interaction of the orbitals and the covalent bond of TiC/Fe3Al were stronger than those of TiC/FeAl. The results were consistent with the experiment of bending strength when the content of Al increases in the TiC/Fe-Al system.
Sodium niobate (NaNbO3) nanometer-size particles having antiferroelectric property were successfully prepared via a hydrothermal process. When NaOH, about 8~10 times as much as Nb2O5(3~4 mol/L NaOH), reacted with Nb2O...
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Sodium niobate (NaNbO3) nanometer-size particles having antiferroelectric property were successfully prepared via a hydrothermal process. When NaOH, about 8~10 times as much as Nb2O5(3~4 mol/L NaOH), reacted with Nb2O5 particles at 160~180°C under hydrothermal conditions, pure orthorhombic phase NaNbO3 characterized by using X-ray powder diffraction was obtained. The unit cell parameters were a = 9.5597, α = β = γ = 90°, c = 5.7873. The hydrothermal reaction significantly lowered the temperature required for synthesizing NaNbO3 and the size of NaNbO3 particles. And TEM analysis showed the size of NaNbO3 particles was about 0.02~0.05 μm.
The effects of fuel cell structures and operating condition on the performance of proton exchange membrane fuel cells are discussed. The results show: there are optimal ranges about the contents of PTFE and Nafion in ...
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The effects of fuel cell structures and operating condition on the performance of proton exchange membrane fuel cells are discussed. The results show: there are optimal ranges about the contents of PTFE and Nafion in catalyst layers. Fine fuel cell structures and scales are benefit to the uniform distribution of reaction gas, the discharging of production, the reduction of fuel cell internal resistances. Increasing the porosity and aperture of diffusion layers can increase the limiting current density of fuel cells. Decreasing the thickness of the membrane will decrease the internal resistances of fuel cell. Raising temperature and pressure will improve electrochemical reaction and reduce transport resistances. The humidification temperature and velocity of the reaction gas should vary with the current density.
The relations among composition, structure, chemical bond and property of composites of TiC/Al2O3 ceramic and doped series are studied by using density function and discrete variation method (DFT-DVM). There are stron...
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The relations among composition, structure, chemical bond and property of composites of TiC/Al2O3 ceramic and doped series are studied by using density function and discrete variation method (DFT-DVM). There are strong ionic and covalent interactions between two phases of TiC/Al2O3, the interaction becomes stronger when doping Ni into TiC/Al2O3, and the interaction of doping Mo into TiC/Al2O3 is stronger than that of doping Ni. The results are consistent with the experiment that doping can improve the combination of the phases in TiC/Al2O3, enhance hardness and et al, and the improvement of doping Mo is more obvious than that of doping Ni.
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