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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Comparison of different types of Zeolites used as Solid Acid Catalysts in the Transesterification reaction of Jatropha-type oil for Biodiesel production

Lemoine, Gaetan 24 April 2013 (has links)
Sustainable energy management has become a high priority for many countries. A great majority of our energy stocks comes from non-renewable fossil fuels, which are currently dwindling. Biofuels are one of the most promising solutions being researched to address this urgent problem. In particular, using transesterified Jatropha curcas L. oil appears to be a promising method of producing biofuels due to several properties of the plant, such as the high oil yield of its seeds and the fact that it does not compete with food crops. The literature mentions many attempts of using zeolites as solid acid catalysts in transesterification reactions of vegetable oils with high free fatty acid (FFA) content. The acid catalysis prevents soap formation and emulsification, which can be observed in the basic process. The use of a solid catalyst makes the separation and purification of the final products steps easier to implement in comparison to catalysis in homogeneous conditions. However, the efficiency of the zeolite in the heterogeneous transesterification reaction of vegetable oil is not well-known yet and varies on the structure of the catalyst used. This project aims at better understanding the relationship between the type of zeolite used and the yield of this particular reaction using reconstituted Jatropha oil from Sesame seed oil, which has a similar composition. Five different types of zeolites were compared: Y, X, Beta, Mordenite & ZSM-5. Non-catalyzed reactions as well as homogeneously catalyzed - with H2SO4 - reactions were also implemented. Since we take advantage of the catalytic properties of different zeolites, the one that were not already in hydrogen form were ion-exchanged and the ion-exchanged species were then analyzed by Energy-Dispersive X-Ray spectroscopy (EDX). Three alcohol-to-oil ratios were tested at atmospheric pressure and at T=115°C for each catalyst in order to determine the influence of this ratio. All experiments were conducted in an airtight autoclave with butan-1-ol in order to obtain a biofuel whose cetane index is higher than regular petroleum-based diesels.
2

Engineering for sustainable development for bio-diesel production

Narayanan, Divya 15 May 2009 (has links)
Engineering for Sustainable Development (ESD) is an integrated systems approach, which aims at developing a balance between the requirements of the current stakeholders without compromising the ability of the future generations to meet their needs. This is a multi-criteria decision-making process that involves the identification of the most optimal sustainable process, which satisfies economic, ecological and social criteria as well as safety and health requirements. Certain difficulties are encountered when ESD is applied, such as ill-defined criteria, scarcity of information, lack of process-specific data, metrics, and the need to satisfy multiple decision makers. To overcome these difficulties, ESD can be broken down into three major steps, starting with the Life Cycle Assessment (LCA) of the process, followed by generation of non-dominating alternatives, and finally selecting the most sustainable process by employing an analytic hierarchical selection process. This methodology starts with the prioritization of the sustainability metrics (health and safety, economic, ecological and social components). The alternatives are then subjected to a pair-wise comparison with respect to each Sustainable Development (SD) indicator and prioritized depending on their performance. The SD indicator priority score and each individual alternative’s performance score together are used to determine the most sustainable alternative. The proposed methodology for ESD is applied for bio-diesel production in this thesis. The results obtained for bio-diesel production using the proposed methodology are similar to the alternatives that are considered to be economically and environmentally favorable by both researchers and commercial manufacturers; hence the proposed methodology can be considered to be accurate. The proposed methodology will also find wide range of application as it is flexible and can be used for the sustainable development of a number of systems similar to the bio-diesel production system; it is also user friendly and can be customized with ease. Due to these benefits, the proposed methodology can be considered to be a useful tool for decision making for sustainable development of chemical processes.
3

Análise espermática e histopatologia testicular de touros Nelore suplementados com caroço de algodão e glicerina

Tsuneda, Pedro Paulo 26 February 2015 (has links)
Submitted by Jordan (jordanbiblio@gmail.com) on 2017-03-02T17:03:16Z No. of bitstreams: 1 DISS_2015_Pedro Paulo Tsuneda.pdf: 1132820 bytes, checksum: d9120ff845d0a7e5ce5a679c7a376de2 (MD5) / Approved for entry into archive by Jordan (jordanbiblio@gmail.com) on 2017-03-03T11:50:05Z (GMT) No. of bitstreams: 1 DISS_2015_Pedro Paulo Tsuneda.pdf: 1132820 bytes, checksum: d9120ff845d0a7e5ce5a679c7a376de2 (MD5) / Made available in DSpace on 2017-03-03T11:50:05Z (GMT). No. of bitstreams: 1 DISS_2015_Pedro Paulo Tsuneda.pdf: 1132820 bytes, checksum: d9120ff845d0a7e5ce5a679c7a376de2 (MD5) Previous issue date: 2015-02-26 / CAPES / Os coprodutos agroindustriais, antes considerados um problema para a natureza, ressurgem demonstrando seus potenciais, devido ao seu poder em substituir alimentos tradicionais, reduzindo o custo com a alimentação. Durante o processo de produção do biodiesel, também se origina a glicerina, com teor de glicerol que pode variar de 80 a 90%, com potencial para utilização em dietas de ruminantes, em substituição de grãos energéticos, por exemplo, o milho. Porém, existem suspeitas que o glicerol utilizado na dieta possa interferir nos parâmetros espermáticos de reprodutores. Outro coproduto agroindustrial a ser explorado por vantagens de custo e da funcionalidade é o caroço de algodão, que não compete a alimento humano e sua composição é rica em energia e proteína. Porém em todas as estruturas da planta do algodoeiro existe uma toxina denominada gossipol. Trabalhos descrevem que o gossipol promove redução na concentração, inibição da motilidade e aumento da mortalidade de espermatozoides. O objetivo principal do trabalho foi avaliar se o caroço de algodão e glicerina bruta como ingredientes em suplementos múltiplos para bovinos Nelore em fase de terminação no período das águas interferiu nos parâmetros seminais e histopatologia testicular. Utilizou-se 40 bovinos Nelore com peso inicial de 472±23,23 kg e idade média de 30 meses. Os animais receberam dietas com dois níveis de caroço de algodão (0 e 25%) e dois níveis de glicerina bruta (0 e 15%) em suplementos múltiplos, sendo os tratamentos: SP (Concentrado sem adição de co-produtos, contendo 0% de glicerol e 0g Gossipol), CA (Concentrado com inclusão de 25% de caroço-de-algodão, contendo 0% de glicerol e 50g Gossipol/dia), GLIC (Concentrado com inclusão de 15% de glicerina, contendo 15% glicerol/MS e 0g Gossipol) e CAGLIC ( Concentrado com inclusão de 25% de caroço de algodão e 15% de glicerina, contendo 15% glicerol/MS e 50g Gossipol/dia), fornecendo-se 4 kg/animal/dia dos suplementos. As variáveis de parâmetros seminais analisadas foram: volume, motilidade, vigor, concentração, integridade de membrana plasmática integridade de membrana acrossomal, porcentagens de anormalidades menores, maiores e totais. Paralelamente às análises de parâmetros seminais avaliaram-se possíveis alterações histológicas dos parênquimas testiculares. A integridade de membrana plasmática sofreu interferência negativa (P<0,05) pelo tratamento, CAGLIC (23,062 ± 14,63) se comparado ao grupo GLIC e CA , ( 49,784 ± 17,60) e ( 48,039 ± 13,02), respectivamente. Nas variáveis: volume, motilidade, vigor, concentração, integridade de membrana acrossomal, porcentagens de anormalidades totais, anormalidades menores e maiores não houve influência dos tratamentos (P>0,05). Não houve diferença entre os tratamentos referente à histologia testicular. A glicerina e o caroço de algodão nos níveis utilizados na substituição energética do milho e proteica do farelo de soja em dietas de touros não interferiram na qualidade espermática e na histologia testicular dos reprodutores. / The agro-industrial byproducts, once considered a problem for nature, resurface demonstrating its potential, due to its power to replace traditional foods, reducing the cost of food. In the biodiesel production process also leads to glycerin, glycerol content which can vary from 80 to 90%, with a potential for use in ruminant diets, replacing energy grains such as corn. However, there are suspicions that the glycerol in the diet can interfere with sperm breeding parameters. Another byproduct agribusiness to be explored by cost advantages and functionality is the cotton seed, that it is not for human food and its composition is rich in energy and protein. But in all cotton plant structures there is a toxin called gossypol. Papers state that gossypol promotes reduction in the concentration, inhibition of motility and increased sperm mortality. The main objective was to assess whether the cottonseed and crude glycerin as ingredients in multiple supplements for Nellore finishing phase during the wet season interfered in semen parameters and testicular histopathology. We used 40 Nellore with initial weight of 472 ± 23.23 kg and mean age of 30 months. The animals were fed diets with two cottonseed levels (0 and 25%) and two crude glycerin levels (0 and 15%) in multiple supplements, with the treatments: SP (concentrate with no added co-products containing 0% 0g glycerol and gossypol), CA (concentrate 25% with the inclusion of seed cotton-containing 0% glycerol and Gossypol 50g / day), GLIC (Concentrate with inclusion of 15% glycerol containing 15% glycerol / MS and 0g Gossypol) and CAGLIC (concentrate 25% with the inclusion of cottonseed and 15% glycerol containing 15% glycerol / MS and Gossypol 50g / day), providing up 4 kg / animal / day supplements. The variables of seminal parameters analyzed were: volume, motility, vigor, concentration, plasma membrane integrity integrity of acrosome membrane, percentages of minors, major and total abnormalities. Together with evaluation of semen parameters were evaluated possible histological changes of testicular parenchyma. The plasma membrane integrity suffered negative interference (P <0.05) by treatment CAGLIC (23.062 ± 14.63) compared to the GLIC and AC group (49.784 ± 17.60) and (13.02 ± 48.039) respectively. In the variables: volume, motility, vigor, concentration, acrosome membrane integrity, percentages of total abnormalities, minor abnormalities and higher there was no influence of the treatments (P> 0.05). There was no difference between treatments on the testicular histology. Glycerin and the cotton seed in the levels used in the energy substitution of corn and protein soybean meal in diets bulls did not affect the sperm quality and testicular histology of players.
4

Modelování, analýza a počítačové simulace heterogenní katalýzy v mikroreaktorech / Modeling, Analysis and Computation of heterogeneous catalysis in microchannels

Orava, Vít January 2013 (has links)
We investigate a nonlinear reaction-diffusion system coupled with convection- diffusion system. This combined system corresponds to physical description of heteroge- neous catalysis when the flow of bulk-constituents is driven by a given stationary velocity field; diverse mechanisms between bulk- and surface-parts of the model-domain are de- scribed by Langmuir-Hinshelwood absorption kinetics; and the irreversible reactions on the catalytic walls meets the law of mass action with quadratic rate. The first part of the thesis is focused on analytical results; in Chapter 2 we prove existence and unique- ness of a mild solution for so-called near-by problem using nonlinear semigroup theory; in Chapter 3 we investigate the weak formulation of the problem. We prove an existence of a weak solution for little modified problem which, under an assumption, coincides with the original problem. In the second part of the thesis (Chapter 4) we numerically investigate the evolution of the bio-diesel microreactor. We compute numerical solutions using several methods and we test the results by analytical and physical conditions; with the aim to find the most efficient way to compute precise and physically correct solution. Keywords: heterogeneous catalysis, coupled reaction-diffusion/convection-diffusion system, nonlinear...
5

Identifying Bio-Diesel Production Facility Locations for Home Heating Fuel Applications Within the Midwest Region of the United States

Schafer, Guy M. 20 May 2011 (has links)
No description available.
6

A study of controlled auto ignition (CAI) combustion in internal combustion engines

Milovanović, Nebojša January 2003 (has links)
Controlled Auto Ignition (CAI) combustion is a new combustion principle in internal combustion engines which has in recent years attracted increased attention. In CAI combustion, which combines features of spark ignition (SI) and compression ignition (CI) principles, air/fuel mixture is premixed, as in SI combustion and auto-ignited by piston compression as in CI combustion. Ignition is provided in multiple points, and thus the charge gives a simultaneous energy release. This results in uniform and simultaneous auto-ignition and chemical reaction throughout the whole charge without flame propagation. CAI combustion is controlled by the chemical kinetics of air/fuel mixture with no influence of turbulence. The CAI engine offers benefits in comparison to spark ignited and compression ignited engines in higher efficiency due to elimination of throttling losses at part and idle loads. There is a possibility to use high compression ratios since it is not knock limited, and in significant lower NOx emission (≈90%) and particle matter emission (≈50%), due to much lower combustion temperature and elimination of fuel rich zones. However, there are several disadvantages of the CAI engine that limits its practical application, such as high level of hydrocarbon and carbon monoxide emissions, high peak pressures, high rates of heat release, reduced power per displacement and difficulties in starting and controlling the engine. Controlling the operation over a wide range of loads and speeds is probably the major difficulty facing CAI engines. Controlling is actually two-components as it consists of auto-ignition phasing and controlling the rates of heat release. As CAI combustion is controlled by chemical kinetics of air/fuel mixture, the auto-ignition timing and heat release rate are determined by the charge properties such as temperature, composition and pressure. Therefore, changes in engine operational parameters or in types of fuel, results in changing of the charge properties. Hence, the auto-ignition timing and the rate of heat release. The Thesis investigates a controlled auto-ignition (CAI) combustion in internal combustion engines suitable for transport applications. The CAI engine environment is simulated by using a single-zone, homogeneous reactor model with a time variable volume according to the slider-crank relationship. The model uses detailed chemical kinetics and distributed heat transfer losses according to Woschini's correlation [1]. The fundamentals of chemical kinetics, and their relationship with combustion related problems are presented. The phenomenology and principles of auto-ignition process itself and its characteristics in CAI combustion are explained. The simulation model for representing CAI engine environment is established and calibrated with respect to the experimental data. The influences of fuel composition on the auto-ignition timing and the rate of heat release in a CAI engine are investigated. The effects of engine parameters on CAI combustion in different engine concepts fuelled with various fuels are analysed. The effects of internal gas recirculation (IEGR) in controlling the auto-ignition timing and the heat release rate in a CAI engine fuelled with different fuels are investigated. The effects of variable valve timings strategy on gas exchange process in CAI engine fuelled with commercial gasoline (95RON) are analysed.
7

臺灣生質燃料產業發展策略之研究 / Development Strategies in Biofuel Industry:Taiwan’s Experience

張宗顯, Chang,Tsung Hsien Unknown Date (has links)
石化能源逐漸耗竭引人關注,再加上「京都議定書」對溫室氣體排放之全球性管制,促使世界各國重視各種新能源與替代性能源,並積極投入應用與研究開發。生質燃料已成為全球許多國家的戰略性資源,其發展除可開發自產綠色能源,提高能源自主比例,並能結合能源、農業、環保、產業等共同發展。面對全球生質燃料產業急速成長,台灣自不能自外於節能減碳的永續發展趨勢。 為驗證政府推動生質燃料政策的環境條件及業界投入狀況,本研究以次級資料分析方法進行國內、外之發展現況及趨勢分析;透過學者、專家、政府業務執行主管及業者之深度訪談,藉由訪談之資料歸納國內發展情形,對照現有生質燃料政策推動目標之發展模式,並以五力分析架構及SWOT評估方法評估生質燃料產業發展之競爭力。 本研究的主要發現包括:1.影響我國生質燃料的發展,最主要的關鍵要素是料源成本、價格補貼及市場保證;2.在推廣生質燃料的策略作法上,絕大多數主張應依政府政策規劃目標循序漸進推動;3.業者在發展生質燃料過程中,面臨最大的困難在於政策的不確定及原料的掌握不足;4.產業發展初期仍應以國內產製優先,不足部分再開放進口;5.生質柴油料源中,目前以廢食用油最具價格競爭力,麻瘋果油次之,藻類則是長期看好的料源。生質酒精部分,依國內廠商最可行技術而言,以甘蔗酒精較具價格競爭力,狼尾草居次,纖維素作物則是長期看好者。6.現階段的政策目標,在生質柴油部分的推廣比例仍以B2為佳,生質酒精則以E3為國產料原的最大量。長期來看,生質燃料產業的擴展,一定要以非糧食作物為優先,關鍵環節在於纖維酒精技術及藻類開發技術有突破,推廣比例及市場規模才有再擴張的空間。 就研究分析所得,提供下述政策建議:1、政府需訂定明確的政策目標;2.成立再生能源國家型計畫,加速推動生質燃料發展;3.政府率先投資第二代生質燃料產業;4.需建構生質燃料永續發展的制度性設計;5.確立以本國產製為優先之政策宣示;6.強化節能減碳教育宣導,讓消費者建立信心並接受。在業界策略上建議:1.必須提升料源掌握度與開發多元料源,並降低生產成本;2.業者須加強與通路商籌組供油策略聯盟;3.生質酒精業者可採合資或合作生產方式切入市場,取得先占地位;4.積極參與第二代生質燃料的研發與技術銜接。 / Petrochemical energy shortage is an issue that has been gradually gaining attention. Global regulation of greenhouse gases emission set by the Kyoto Protocol has also called attention to new and alternative energy sources, as well as the active involvement of individual countries in new energy application and research development. Biofuel has now become a strategic resource in many countries. Additional development of alternative energy can not only help increase the amount of domestic green energy and its ratio to traditional energy, synergy is also created causing the equal development of energy, agriculture, environmental production, and industrial growth. In face of the rapid growth of the biofuel industry worldwide, Taiwan must not exclude itself from the trend of sustainable development in energy conservation and CO2 reduction. To access the conditions of government policy in biofuel promotion and industry involvement, this study used secondary data analysis methods to analyze the current trend and status of national and international development. Through information gathered from in-depth interviews with academics, experts, government executives, and industry members, current domestic developments are compared to existing models of biofuel policy, promotion, and objectives. The competitiveness of biofuel industry development is further evaluated using SWOT assessment and Five Power Analysis. The main findings of this study include the following: 1) The key elements affecting national biofuel development are raw material costs, price subsidies, and market guarantees. 2) In biofuel promotion strategies, a vast majority should be made gradually and according to government policy planning objectives. 3) In biofuel development, the biggest challenges the industry faces are policy uncertainties and the lack of raw materials. 4) In initial industry development, domestic production should be a priority, allowing imports only when in demand. 5) In raw materials for bio-diesel, recycled oils are currently the most competitive in value, followed by Jatropha oil, while algae is seen as having long-term potential. According to the most viable technology offered by domestic manufacturers, sugarcane ethanol is the most competitive in value for bio-ethanol, followed by Chinese Pennisetum, while agricultural waste is seen as having long-term potential. 6) In the current stage of policy objectives, B2 is still more adequate in the promotion of bio-diesel, and E3 is the main domestic raw material for bio-ethanol. In the expansion of biofuel industry in the long run, priority must be given to non staple crops, while the key lies in cellulosic ethanol and algae oil development technology. Only then can there be room for further expansion in promotional proportion and market scale. The following policy recommendations are provided based on analysis of the study: 1) Clear policy goals must be set by the government. 2) Establish nation-wide plans for renewable energy, and accelerate the promotion of biofuel development. 3) Government must take initiatives in second-generation feedstock investments. 4) A systematic design must be built for the sustainable development of biofuel. 5) Policy declarations must be made to ensure the priority of domestic production. 6) Strengthen education in energy conservation and CO2 reduction, and build consumer confidence and acceptance. Recommendations for industry strategies: 1) It is essential to increase control of raw materials, develop multi-source materials, and lower production costs. 2) The industry must strengthen its strategic alliances with distributor in oil supply. 3) The biofuel industry may partake in joint ventures or cooperative efforts to get a head start when entering the market. 4) Actively participate in the research and development and technology adaptation of second-generation feedstock.

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