Proton exchange membrane fuels cells (PEMFCs) are one of the primary alternatives to internal combustion engines. The key component is the proton exchange membrane, or PEM, which should meet a number of requirements, including good proton conductivity under partially humidified conditions. A number of alternative PEMs have been synthesized by copolymerizing various aromatic comonomers, but the smaller ion channels prohibit rapid proton transport under partially hydrated conditions. One solution has been to synthesize multiblock copolymers from hydrophilic and hydrophobic oligomers to ensure sufficient ion channel size. Four multiblock systems were synthesized from hydrophobic and hydrophilic oligomers and were characterized in this thesis. The first multiblock system incorporated a partially fluorinated monomer into the hydrophobic block, to improve phase separation and performance under partially humidified conditions. The second study was focused on phase separation and structure-property relationships as a function of casting conditions of a biphenol-based multiblock series. The third study featured a novel hydroquinone-based hydrophilic oligomer in the multiblock copolymer, which showed the promise of a higher ionic density, degree of phase separation and proton conductivity values. The fourth study in this thesis entailed the comparison of a block copolymer produced with two distinct synthetic routes: the multiblock synthesis from separate oligomers as previously published in the literature, and a segmented route seeking to achieve comparable structure-property relationships with the same monomers, but using a simpler synthetic route. The two block copolymer series were found to be comparable in their structure-property relationships. / Master of Science

京都大学 / 新制・課程博士 / 博士(工学) / 甲第25278号 / 工博第5237号 / 新制||工||1998(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 黒瀬 良一, 教授 長田 孝二, 教授 岩井 裕 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Made available in DSpace on 2014-10-09T12:27:00Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:30Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:27:00Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:30Z (GMT). No. of bitstreams: 0 / Neste trabalho foram selecionadas, estabelecidas e estimadas possíveis fontes de produção de hidrogênio para a geração de energia elétrica de forma distribuída, com a utilização de célula a combustível. Estudaram-se três fontes de geração de energia renovável no Brasil: a biomassa, a energia solar fotovoltaica e a energia eólica. Para o estabelecimento dos valores numéricos foram avaliadas as principais culturas agrícolas de cada estado pertencente à respectiva região e a quantidade de biomassa, na forma de rejeito agrícola, capaz de ser gerada para futura utilização na produção de hidrogênio. Da mesma maneira foi investigada e avaliada numericamente a capacidade de produção de hidrogênio através das energias eólica e solar fotovoltaica para cada região do Brasil, tomando-se como base o processo de eletrólise. Mediante os resultados obtidos é possível demonstrar as potencialidades do Brasil para a geração de energia elétrica de maneira distribuída e com a substituição de combustíveis fósseis e por conseqüência, com a melhoria do meio ambiente. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Direct membrane deposition was used to produce record platinum catalyst utilization efficiency polymer electrolyte membrane fuel cells. The novel membrane fabrication technique was applied to gas diffusion electrodes with low Pt-loadings of 0.102 and 0.029 mg/cm2. Under oxygen atmosphere and 300 kPaabs total pressure, 88 kW/gPt cathodic catalyst utilization efficiency with a symmetrical Pt-loading of 0.029 mg/cm2 on the anode and cathode side was achieved. This is 2.3 times higher than the Pt-utilization efficiency of a reference fuel cell prepared using a commercial Nafion N-211 membrane and identical catalyst layers, emphasizing that the improvement is purely attributable to the novel membrane fabrication technique. This value represents the highest Pt-utilization efficiency reported in literature. The results strongly motivate the application of employing direct membrane deposition techniques to prepare low resistance polymer electrolyte thin films in order to compensate for kinetic losses introduced when using low catalyst loadings.

The subject of this graduation thesis is low-cost alkaline power cells and especially electrodes with alternative catalyst made of MnOx + dopant. The thesis expands the bachelor´s thesis [1] and previous research [4] [12] [13] [14]. Volt-ampere characteristics and power characteristics of the katodes for AFC, subsidized with various dopants, are the outcome of this project. The project presents the optimalisation of preparation process of AFC electrodes. The aim is to prepair several electrodes with identical construction, which varies only with the type of the dopant.

Multi-component coatings and high entropy alloys have in recent years attracted great interest for research, since they have shown to exhibit properties greater than the com- ponents of their parts. Today’s climate challenges requires transitioning from fossil fuels to renewable energy sources which demands use of new technology and new innovations. The hydrogen fuel cell is a technology which produces no carbon emissions, and the drive for innovation has led researchers to apply multi-component (high entropy alloys) coatings to invent the next generation hydrogen fuel cells and help the transition to renewable energy sources. This thesis has investigated the process-structure-property relationships of four deposi- tion growth parameters: target current (Itarget), argon pressure (PAr). substrate bias (Vsubstrate) and deposition time (tdeposition) on TiNbZrTa-coatings, grown by magnetron sputtering using an industrial deposition system. The range of the parameters have been: Itarget from 2.5 to 6 A, PAr from 1 to 17 mTorr, Vsubstrate from 30 to 200 V and tdeposition from 3.6 to 12 minutes (depending on Itarget). Coatings have been grown on Si (001) and stainless steel 304 and 316L substrates. The coating microstructure was analyzed by X-ray diffraction and electron microscopy. The results have yielded that all coatings are equimolar and that the coatings exhibit three different morphologies, two different topologies and two different corresponding structures. The different morphologies are wave, coarse columnar and fine columnar morphology. The two topologies are nodular and dune surface topology. The two different structures are a solid solution BCC (110) phase and an amorphous or nanocrystalline phase. The results indicate that parameters affecting the temperature of the substrate (Tsubstrate) is the prime decider for the final morphology of the coatings. High Itarget and Vsubstrate, low PAr and long tdeposition all increases Tsubstrate and results in a coating which exhibits a fine columnar morphology, dune topology and a solid solution BCC phase. These types of coatings have also proven to have improved corrosion resistance compared to the other type of coatings seen in this thesis. The other kind of coating is grown with low Itarget and Vsubstrate, high PAr and short tdeposition, which causes minimal increase of Tsubstrate. These growth parameters result in a coating with coarse columnar morphology, nodular topology and amorphous or nanocrystalline phase, with less corrosion resistance. / FunMat II

Orientadores: Ênnio Peres da Silva, Kamal Abdel Radi Ismail / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T22:35:26Z (GMT). No. of bitstreams: 1 Lopes_DanielGabriel_M.pdf: 3136066 bytes, checksum: c47f35afd0cbcdaa10bf8e97d99f8270 (MD5) Previous issue date: 2010 / Resumo: Ao avaliar a evolução do uso da energia pelo homem, percebe-se uma tendência à utilização de combustíveis com menos carbono e mais hidrogênio. Atualmente, observa-se um empenho pela utilização de combustíveis gasosos, como o gás natural, que possui uma relação de 4 átomos de hidrogênio para 1 átomo de carbono. Esta evolução permite estimar a utilização do hidrogênio gasoso para o futuro. Por se tratar de um vetor energético e não de uma fonte de energia, o hidrogênio precisa ser extraído de algum composto para ser utilizado. Examinando-se a literatura pertinente dos últimos anos, verifica-se que há em todo o mundo um grande esforço e uma grande expectativa quanto ao uso energético do hidrogênio em células a combustível, já que a eficiência destes equipamentos é superior à eficiência dos dispositivos tradicionais que utilizam à combustão. Sua aplicação se dá em diversos sistemas energéticos, estacionários ou móveis. Devido á exigência de elevada pureza para o hidrogênio utilizado em células a combustível do tipo PEM, a produção de hidrogênio a partir do processo de reforma de gás natural e o sistema de purificação deste hidrogênio tem sido estudado pelos principais centros de pesquisa nacionais. Por se tratar de umas das formas mais baratas para obtenção de hidrogênio para aplicação em células a combustível, o conhecimento desta tecnologia poderá conduzir à competitividade do uso energético do hidrogênio com um menor custo num menor prazo, o que a torna uma tecnologia estratégica. O objetivo geral desta dissertação é apresentar os principais processos de purificação do gás de síntese proveniente da reforma do gás natural para o fornecimento de hidrogênio com pureza suficiente para uso em células a combustível do tipo PEM e apresentar as considerações teóricas e experimentais sobre o funcionamento do sistema de purificação construído pelo Laboratório de Hidrogênio da Unicamp para desenvolvimento desta dissertação / Abstract: Evaluating the evolution of energy use by humanity it is observed a tendency to use fuels with lower carbon content and more hydrogen. Currently, there is a commitment to use fuels such as natural gas that has a ratio of 4 hydrogen atoms to 1 carbon atom. That evolution allows the estimation of gaseous hydrogen use for the future. Hydrogen is an energy vector, not an energy source, and then it must be extracted from a compound to feed fuel cells. The literature of recent years shows that there is a great effort and a huge expectation for the use of fuel cells which achieve higher efficiencies than traditional combustion devices. Fuel cells can be used in stationary, automotive or portable energy systems and its manufacturing technology has left laboratories and research centers is now being developed by companies with large investments. Since PEM fuel cells require high purity hydrogen, the hydrogen production from natural gas reforming process and the hydrogen purification systems have been studied by Brazilian research centers. Because this process is one of the cheapest methods to obtain hydrogen for use in fuel cells, the knowledge of this technology could lead to the competitive use of hydrogen energy at a lower cost in a shorter term, making it a strategic technology. The general objective of this dissertation is to present the main processes for the purification of synthesis gas from the reforming of natural gas to supply hydrogen with sufficient purity for its use in PEM fuel cells and present the theoretical and experimental considerations about the purification system built by the Hydrogen Laboratory at Unicamp for the development of this dissertation / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

<p>In recent years lithium-ion battery electric vehicles and stored hydrogen electric vehicles have been developed to address the ever-present threat of climate change and global warming. These technologies have failed to achieve profitability at costs consumers are willing to bear when purchasing a vehicle. IFBattery, Inc. has developed a unique primary battery chemistry which simultaneously produces both electricity and hydrogen-on-demand while being both low cost and without carbon emissions. In order to determine the feasibility of the IFBattery chemistry for mobile applications, a prototype golf cart was constructed as the first public application of IFBattery technology. The legacy lead acid batteries of the prototype golf cart were replaced with an IFBattery chemistry tuned to primarily produce hydrogen-on-demand with supplemental electricity. Hydrogen produced by the IFBattery was purified and then fed into a hydrogen fuel cell where electricity was produced to power the vehicle. Electricity from the IFBattery was converted to the common voltage of the golf cart and also used to power the vehicle. Validation testing of the IFBattery powered golf cart demonstrated favorable results as an alternative to both lithium-ion battery and stored hydrogen technologies, and displayed potential for future applications.</p>

The subject of diploma thesis is to gather knowledge in the production and use of hydrogen. This work is devoted to a comparison of the previously existing processes for producing hydrogen, where the vast majority is filled of fossil fuel. Another section is devoted to new materials for the study based on a number of selected patents and the experiment promising new method for decomposition of water. Based on available data will be carried out energy balance and consequently will be drafted energy system using hydrogen as fuel. In conclusion will be future possibilities evaluated in the field of hydrogen energy.