Water management is the key for PEMFC to operate efficiently. To maintain a suitable hydrated state for PEM but without flooding in the porous medium polarity is an ideal case which is difficult to achieve. PEMFC is a...
详细信息
Water management is the key for PEMFC to operate efficiently. To maintain a suitable hydrated state for PEM but without flooding in the porous medium polarity is an ideal case which is difficult to achieve. PEMFC is a complex system with the characteristics of multi-phases, multi-dimensions, multi-physics fields and dynamics. The flow, heat and mass transfer, phase change, multi-phase flow and electrochemical process inside PEMFC have influences on each other, the mechanism is sophisticated and hard to measure or observe directly. This paper summaries the achievement in respects of water transfer mechanism, humidification methods, measurement and diagnostic of liquid water in PEMFC, methods of discharge liquid water and modeling of the water behaviors inside PEMFC. The water management, heat management, gas management and electricity management are associated each other, therefore the flow, heat and mass transfer, phase change, multi-phase flow and electrochemical process inside PEMFC should be considered systematically, relevant researches are to be carried out continuously.
In this research, we developed a three-dimensional finite-difference-time-domain algorithm that incorporated the Lorentz-Drude model through the use of Z-transform technique. This algorithm was used to compute the spe...
详细信息
In this research, we developed a three-dimensional finite-difference-time-domain algorithm that incorporated the Lorentz-Drude model through the use of Z-transform technique. This algorithm was used to compute the spectral response of infrared bandpass filters which consisted of the openings of cross-shaped structures in a thin gold film. In creating structures, a graphical user interface was built using Matlab development environment. The created structures were then simulated by running the simulation code written in Fortran. It was observed that cross-shaped structures with large center-broadening effect yielded the highest transmission intensity among the structures that were simulated with a transmittance of approximately 80% at the wavelength of 1.2 μm.
Water management is critical for high performance of proton exchanges membrane fuel cell (PEMFC). The liquid water transport model for gradient structure gas diffusion layer of PEMFC was established based on the capil...
详细信息
Water management is critical for high performance of proton exchanges membrane fuel cell (PEMFC). The liquid water transport model for gradient structure gas diffusion layer of PEMFC was established based on the capillary pressure theory, and then the liquid water flux through GDL was calculated based on the assumption that a fixed liquid saturation difference exists between the interfaces of catalyst layer/GDL and GDL/gas channel, the results were analyzed. Results showed that under steady condition the liquid water flux through GDL increasing with the increasing of porosity, GDL with gradient porosity was more favorable for liquid water to be discharged from MEA to gas channel;the larger the gradient was, the more easily the liquid water was to be discharged out.
This research is that cellulose/poly-silicate hybrid material was prepared with viscose and poly-silicate by sol-gel method. The influence of aluminum salt and poly-silicate on hybrid material thermal property was stu...
详细信息
This research is that cellulose/poly-silicate hybrid material was prepared with viscose and poly-silicate by sol-gel method. The influence of aluminum salt and poly-silicate on hybrid material thermal property was studied. Based on the analysis of the DSC and TG curve of hybrid material, we have found that the hybrid material has splendid heat-resistance and fire retardancy.
TiB_2 ceramics powder was synthesized from B_2O_3-TiO_2-Mg system. The effects of TiB_2 addition as diluent on the combustion synthesis process were investigated. The results of thermodynamic calculation and experimen...
详细信息
TiB_2 ceramics powder was synthesized from B_2O_3-TiO_2-Mg system. The effects of TiB_2 addition as diluent on the combustion synthesis process were investigated. The results of thermodynamic calculation and experiments show that the increase of TiB_2 content ranging from 0 to 20wt% can reduce the adiabatic temperature T_(ad) from 3100 K to 2896 K and combustion temperature T_c from 2139 K to 1621 K respectively. The particle size and half width of the particle distribution are also increased with the addition of TiB_2 increasing from 0 to 20wt%. The combustion product is a mixture of TiB_2, MgO, and other intermediate phases. The leached product contains mainly TiB_2, TiO_2 and TiN, and its oxygen content is 7.77wt%.
Patterned ZnO nanorods have been first grown on patterned silicon nanocrystallite (SiNC) films that were fabricated on (100) orientation p-type boron-doped silicon wafer by hydrogen ion implantation technique and the ...
详细信息
Patterned ZnO nanorods have been first grown on patterned silicon nanocrystallite (SiNC) films that were fabricated on (100) orientation p-type boron-doped silicon wafer by hydrogen ion implantation technique and the anodic etching method, and their field emission properties were obtained. Field emission measurements demonstrated that the synthesized ZnO nanorods have excellent field emission properties, namely low turn-on field, low threshold field, and high emission spot density. The patterned ZnO nanorods have great potential in the application of flat panel displays.
In order to unclose the dynamics of SPS densification, a special sintering sample (Cu/Ti wires compact) was designed. Characters of the shrinkage rates during sintering process and microstructures of products fabricat...
详细信息
In order to unclose the dynamics of SPS densification, a special sintering sample (Cu/Ti wires compact) was designed. Characters of the shrinkage rates during sintering process and microstructures of products fabricated by the spark plasma sintering(SPS) and hot-press sintering were investigated. The experimental results reveal that a higher temperature field is formed at the connected area and conductive net of the compact. These high-temperature parts deformed more easily than other parts, which is believed to be the main cause of SPS fast densification, according to a hard-core and soft-hell material model.
Polymer-protected monodisperse nickel nanoparticles were synthesized by a modified polyol reduction method in the presence of poly（N-vinyl-2-Pyrrolidone）.These nanoparticles were characterized by transmission electr...
详细信息
Polymer-protected monodisperse nickel nanoparticles were synthesized by a modified polyol reduction method in the presence of poly（N-vinyl-2-Pyrrolidone）.These nanoparticles were characterized by transmission electron microscopy（TEM）,X-ray diffraction（XRD）,selected area electron diffraction（SAED）,as well as vibrating sample magnetometer（VSM）.The experimental results show that the addition of PVP and the concentration of NaOh have strong influences on the *** and uniformity of *** the presence of PVP and NaoH with low *** nickel nanoparticles with average diameters about 42 nm were obtained and characterized to the pure nickel crystalline with foc *** structures such as *** strings resulted from magnetic interactions between particles were *** chemical interaction between the PVP and nickel nanoparticles was found by *** saturation magnetization（Ms）.remanent magnetization（Mr）and coercivity（Hc）of these nickel nanoparticles are lower than those of bulk nickel.
ZrB2 ceramics were prepared by self-propagating high-temperature synthesis（SHS） and were sintered by hot pressing（HP）.The effects of the granularities and doses of raw materials in Zr-B2O3-Mgon SHS process and pro...
详细信息
ZrB2 ceramics were prepared by self-propagating high-temperature synthesis（SHS） and were sintered by hot pressing（HP）.The effects of the granularities and doses of raw materials in Zr-B2O3-Mgon SHS process and product were *** and combustion temperature curves prove that the ideal SHS reactants of Zr-B2O3-Mg are 50μm Zr powder,75μm B2O3 powder and 400μm Mg powder with 45% *** particle sizes of SHS product,acid-leached product,sintered product are 2-5μm,0.5-2μm,2-10μm *** analysis indicates that the acid-leached product consists of ZrB2（94.59%）,ZrO2（3.87%）,and H3BO3（1.54%）,The sintered product has a relative density of 95.4%.
The flow field is very important for the proton exchange membrane fuel cell (PEMFC). In this paper the PEMFC with different kind of section channels is modeled and optimized design by the PEM module of the Fluent soft...
详细信息
The flow field is very important for the proton exchange membrane fuel cell (PEMFC). In this paper the PEMFC with different kind of section channels is modeled and optimized design by the PEM module of the Fluent software. And the result shows that the performance of the PEMFC with rectangle, semicircle, triangle or trapezoid section is not too much difference, but the performance of the PEMFC with changing section channel is much better than that of the above mentioned ones.
暂无评论