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为研究相对湿度对车用燃料电池电压衰减的影响,提出了电池阳极相对湿度(anode relative humidity,ARH)模型。建立了燃料电池计算模型和网格,将ARH模型移植到计算流体动力学软件(FLUENT)中,用于计算电池堆中电压衰减最快的单电池。针对C10(距离进气口最远的电池)在不同相对湿度时的FLUENT原模型、ARH模型和实验数值进行了对比分析。结果表明:ARH模型能较准确地计算C10的性能,在相对湿度为100%时,ARH模型比FLUENT原模型精确度提高了10%。为进一步优化燃料电池堆的水管理系统提供了新的思路。 相似文献
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利用改性硅溶胶包覆液对气雾化Fe-6.5%Si软磁合金粉末进行表面绝缘处理并制备磁粉芯,考察了不同包覆液用量对铁硅磁粉芯性能的影响。结果表明,经包覆处理的合金粉末表面存在均匀的氧化物绝缘层;磁粉芯样品在测试频率范围具有良好的恒磁导率和高频特性;随着包覆液用量的增加,磁粉芯样品的磁导率相应减小、直流叠加性能明显提高,损耗则表现出先减小再增大的趋势。当包覆液用量为1.0 wt%时,样品的恒定磁导率为78,50k Hz、50m T条件下的功耗为170 m W/cm3,直流叠加场为10m T时磁导率百分比为55%,表明适当的粉末表面包覆层有利于获得高性能的铁硅磁粉芯。 相似文献
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反应气相对湿度影响电池内部水的输运和质子膜的质子传导率,合适的反应气湿度可改善电池性能.利用三维数值模型分析反应气相对湿度对直通流道和交叉流道质子交换膜燃料电池性能的影响.模拟结果表明,当阳极反应气相对湿度为100%时,低操作电压条件下,降低阴极反应气相对湿度有利于电池性能提高,然而在高操作电压条件下,电池性能随阴极相对湿度的增加而提高;当阴极反应气相对湿度为100%时,低操作电压条件下,降低阳极反应气相对湿度,电池性能提升,高操作电压条件下,电池性能不依赖于阳极反应气相对湿度.通过对电池内部局部传递特性的分析,从质子交换膜湿润性及阴极传质限制两方面分析探讨了反应气相对湿度对电池性能影响的原因. 相似文献
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Trigwell S. Grable N. Yurteri C.U. Sharma R. Mazumder M.K. 《Industry Applications, IEEE Transactions on》2003,39(1):79-86
Experiments performed on different powders of different size distributions tribocharged with stainless-steel (SS) beads showed the charge acquired by the powder could be correlated with the actual work function difference between the powder and SS. Ultraviolet and X-ray photoelectron spectroscopy were performed on various materials involved, and showed the work function increased with surface contamination and oxidation, and the difference narrowed for metals and polymers. Such a small difference in work function may contribute to bipolar charging. Experiment data showed that while charge acquired increased with particle size, the charge distribution was generally bipolar. Both surface analysis and charge distribution studies suggest that for tribocharging, minimization of oxidation and surface contamination are needed. It also appears that the relative humidity must also be controlled to obtain reliable tribocharging. Semiempirical molecular modeling calculations of the work function of several polymers showed good agreement with experiment. Surface plasma treatment is presented as a viable method for modifying the work function. 相似文献
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将不同球磨时间的FeSiAl合金粉经高温氮化处理后,冷压成型、873K退火1h制得磁粉芯。分别用扫描电子显微镜、X射线衍射仪、能谱仪、振动样品磁强计观测粉末的形貌、晶体结构、成分和饱和磁化强度,利用动态磁滞回线测试装置测试磁粉芯的功率损耗。结果表明,延长球磨时间磁粉芯的损耗降低,随着氮化时间延长,磁粉的饱和磁化强度降低,磁粉芯的损耗先降低,后维持不变。球磨60 h氮化90 min粉末的饱和磁化强度达77.53 A·m2/kg,所制备的磁粉芯在100k Hz/300m T测试条件下功率损耗为58.18 W/kg。 相似文献
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High-density polyethylene films 50 μm thick were exposed to the downstream plasma flow of RF glow discharges in argon, hydrogen, or oxygen. It was found that many transvinylene and unreacted radicals remain after the argon or hydrogen plasma treatment, and that carbonyl groups are formed in the oxygen plasma treatment. The conduction current was smaller in the hydrogen-plasma treated samples and the samples exposed to oxygen or ozone after hydrogen-plasma treatment than in the untreated samples. Thermal pulse current measurements indicate that the treated surface layer traps electrons or holes and reduces the field strength at the electrode surface, thus suppressing further injection of electrons or holes. 相似文献
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采用不同表面化学状态的纳米SiO2,制备了聚环氧乙烷[Poly(ethyleneoxide),PEO]基复合聚合物电解质(Compositepolymerelectrolytes,CPE),通过DSC技术和FTIR光谱研究了纳米填料对聚合物体系体相成分的影响,并对其离子电导率、锂离子迁移数、电化学稳定性等电化学性质进行了表征。结果表明,纳米填料的表面化学状态对CPE的影响很大,亲水性的SiO2对CPE的相组成几乎没有改变效果,但疏水性的SiO2明显降低了聚合物体系的晶相成分。电化学测试结果显示,采用表面烷基化的SiO2制备成的CPE比采用亲水性SiO2的CPE显出更高的离子电导率、锂离子迁移数和更宽的电化学稳定窗口,揭示了体系的相组成和PEO/SiO2相界层是影响CPE内离子传输的两个重要因素。 相似文献
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N. M. Zhuravleva S. P. Zhuravlev A. V. Maslyakova 《Russian Electrical Engineering》2007,78(3):133-137
It is shown that the electric strength and resistance to thermal ageing of an electric insulating paper may be improved by modifying the cellulose base with a chitosan biopolymer. The effects of the morphological features of the polymer foil on the electrophysical properties of the impregnated dielectrics and the interaction between an impregnating liquid and a polymer are presented. 相似文献
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采用聚乙二醇二甲醚(PEGDME)、聚乙烯吡咯烷酮(PVP)、聚氧化乙烯(PEO)作为聚合物电解液添加剂,通过充放电测试研究了这些添加剂对锂硫电池电化学性能的影响。研究结果表明,添加2%(质量分数)电解液添加剂PVP能有效提高锂硫电池的循环性能和库仑效率,在电流密度为200 m A/g下,前50次的电池放电容量保持率由42.8%提高到50.8%,首次循环库仑效率由60.2%提高到95.3%。 相似文献
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MacAlpine J.M.K. Zhang C.H. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2003,10(3):506-513
AC corona pulses have been measured using a computer-based commercial partial discharge detector. The pulse height distribution was measured in air as a function of phase angle and pulse height for a range of voltages using a point/cup electrode system. An earlier paper discussed the effect of space charge on the onset voltages for both positive and negative half-cycles and on the patterns obtained. In the work reported in this paper, the humidity was varied, and large changes were found in the patterns observed in both half-cycles. At high humidities the negative half-cycle corona largely ceased but a second positive corona onset appeared in the second quarter of the cycle. An explanation for these phenomena is proposed in terms of the effect of the production of negatively charged water molecule clusters. Their production results in a lower effective ionization coefficient and thus higher critical field, and their lower mobility results in a more effective negative space charge. The former reduces the positive space charge in the positive half-cycle thus allowing avalanches and streamers to develop during the second quarter of the cycle. The latter results in a stronger negative space charge during the negative half-cycle which suppresses the corona during that half-cycle. 相似文献
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采用湿法滚动球磨工艺对FeSiAl磁粉进行扁平化处理,通过绝缘包覆工艺对粉末进行改性制备成浆料,并经过涂布和层压工艺制备成吸波片样品。研究球磨时间对粉末粒度、形貌和物相的影响,进而对所制备的吸波片的电磁参数和吸波性能进行分析评价。研究结果表明,FeSiAl磁粉经搅拌球磨5~10h后,D50由45μm增大到53μm,片厚由4μm减小到2μm,有较好的扁平化效果,且扁平化充分的磁粉有较好的电磁波吸收特性。XRD分析表明球磨工艺没有改变FeSiAl粉末的相结构。随着球磨时间延长,大长径比的磁粉所占比重增加,磁导率实部和虚部均增大,当球磨10h时,-200~+270目磁粉在13.56MHz磁导率实部达到69,虚部达到18。 相似文献
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The results of experimental studies of the influence of the plasmodynamic deposition conditions of a copper coating on an aluminum contact surface on the contact resistance of an aluminum-copper high-current contact pair with a copper coating are presented. A significant decrease in contact resistance relative to an ordinary contact between aluminum and copper is observed as a result of optimization of the phase composition and structure of the transition layer. 相似文献