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<p>A method of exhaust heat recovery from a spark-ignition internal combustion engine was explored, utilizing a steam reforming thermochemical reactor to produce a hydrogen-rich effluent, which was then consumed in the engine. The effects of hydrogen in the combustion process have been studied extensively, and it has been shown that an extension of the lean stability limit is possible through hydrogen enrichment. The system efficiency and the extension of the operational range of an internal combustion engine were explored through the use of a methane fueled naturally aspirated single cylinder engine co-fueled with syngas produced with an on board methane steam reformer. It was demonstrated that an extension of the lean stability limit is possible using this system.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6426. Advisers: Paul J.A. Kenis; Andrzej Wieckowski. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Wood is an interesting alternative to fossil fuels. It is CO2-neutral and widely available. However it is a difficult fuel to handle which features a low energy content. Thus technologies for wood thermal conversion need to be improved. This work concerns the development of a comprehensive two-dimensional mathematical model describing the pyrolysis of large wood particles and its implementation in a Fortran program. The model has been continuously tested and improved by experimental results obtained in a reactor for single particle pyrolysis (SPAR) at the Division of Physical Chemistry at Göteborg University. The first part of the thesis (Paper I) presents a kinetic study of the pyrolysis of large wood particles, based on experiments carried out in the SPAR. Three pyrolysis kinetic schemes were selected for later inclusion in a model featuring heat and mass transfer. Paper II concerns the addition of a sub-model for heat and mass transfer to the three kinetic schemes. The resulting model for large wood particles has been tested against experiments in the SPAR. A scheme based on two competing reactions developed from experiments at low temperature pyrolysis in the SPAR was found to perform well but its empirical nature limits its validity to the experimental conditions of the SPAR. A scheme from the literature based on TGA experiments appeared promising, especially when planning to enhance it with secondary reactions. Paper III deals with the development of shrinkage models for 2D cylindrical particles. The predicted mass loss, size variation and surface temperature were tested against experiments carried out in the SPAR. The shrinkage does not a?ect the pyrolysis rate or the surface temperature in the conditions prevailing in the SPAR. Paper IV investigates the influence of different shrinkage models and the geometry on the heating rate of a shrinking particle. Shrinkage influences the heating rate positively by increasing the conductive heat flow and negatively by decreasing the surface area of the particle. Therefore the net effect of shrinkage on the heating rate depends on the particle geometry and the location of shrinkage. Paper V studies three di?erent models for wood drying under pyrolysis conditions. The predicted surface temperature and global drying rate were compared with experimental results from pyrolysis experiments of wet particles in the SPAR. A model based on a first order kinetic evaporation rate was found to be the most interesting because of the quality of the prediction of the drying rate and the ease of implementation. / QC 20100624

<p>Abstract</p><p>This thesis is studying the heatsinks new designs for copper heatsinks which utilizes modelling and simulation by CFD, construction of prototypes and experimental works. Challenges and complications in manufacturing of copper heatsinks are expressed and finding the solutions to these hindrances involve in this work. Numerical efforts supported by fluent are made to promote investigation and approaching the goal in which serves the new opportunities for wider application of copper material in heat sinks.</p><p>However the thermal conductivity of copper is about double as aluminium but still aluminium heatsinks are commonly used for heat dissipation in computers.</p><p>Comparing of heat performance of two analogous heatsink of different materials, aluminium and copper, is conducted by numerical analysis in the CFD environment.</p><p>In addition to larger surface area and airflow velocity another solution for enhancement of heat dissipation is suggested.</p><p>Manufacturing solutions of copper heatsinks are proposed which will facilitate fabrication of more high performance copper heatsinks than the current heavy and expensive models.</p><p>Our first copper heat sink model is designed exclusively based on the technical observations and analyses of numerical simulation of two identical copper and aluminium heatsinks by CFD and as well as manufacturability concerns.</p><p>This heat sink is fabricated mechanically and is tested by a number of heat sources and high sensitive devices such as adhesive K type thermocouple, data acquisition 34970A in associated with HP Bench Link program.</p><p>An extent experimental work on aluminium heatsinks, integrated with forced convection, is performed in order to measure their thermal capacities.</p><p>Comparison of the heat performance of a typical aluminium heatsink, which was the best among the all aluminium heat sinks and proposed copper heatsink under identical experimental conditions, is performed.</p><p>Also in some numerical efforts, optimizing and predicting of the thermal characterization of the proposed heatsink with inclined free fins is developed. The model is scaled up in the fluent environment to predict its application in the cooling of larger heat generated electronic devices.</p><p>Impingement air-cooling mode of force-convection is adopted for heat dissipation from high power electronic devices in associated with the proposed inclined fin model.</p><p>Components of airflow velocity in the hollow spaces of the heatsink are discussed. Pressure drop and other thermal variables are analyzed analytical and by CFD code.</p><p>Another mechanical manufactured copper heat sink is investigated. A new design of the base and fins is optimized.</p><p>A three-dimensional finite volume method is developed to determine the performance of the proposed heatsink.</p><p>Thermal and hydraulic characterization of the heat sink under air-forced convection cooling condition is studied. The flow behavior around the fins and some other parts of the heat sink is analyzed by utilizing CFD code.</p><p>The hydraulic parameters including velocity profiles, distribution of static pressure, dynamic pressure, boundary layer and fluid temperature between the fins and in the passageway at the middle of the heat sink are analyzed and presented schematically.</p><p>Furthermore the thermal characteristic of the proposed heatsink is studied by contouring the three dimensional temperature distributions through the fins and temperature of the heat source by CFD code.</p>

Abstract This thesis is studying the heatsinks new designs for copper heatsinks which utilizes modelling and simulation by CFD, construction of prototypes and experimental works. Challenges and complications in manufacturing of copper heatsinks are expressed and finding the solutions to these hindrances involve in this work. Numerical efforts supported by fluent are made to promote investigation and approaching the goal in which serves the new opportunities for wider application of copper material in heat sinks. However the thermal conductivity of copper is about double as aluminium but still aluminium heatsinks are commonly used for heat dissipation in computers. Comparing of heat performance of two analogous heatsink of different materials, aluminium and copper, is conducted by numerical analysis in the CFD environment. In addition to larger surface area and airflow velocity another solution for enhancement of heat dissipation is suggested. Manufacturing solutions of copper heatsinks are proposed which will facilitate fabrication of more high performance copper heatsinks than the current heavy and expensive models. Our first copper heat sink model is designed exclusively based on the technical observations and analyses of numerical simulation of two identical copper and aluminium heatsinks by CFD and as well as manufacturability concerns. This heat sink is fabricated mechanically and is tested by a number of heat sources and high sensitive devices such as adhesive K type thermocouple, data acquisition 34970A in associated with HP Bench Link program. An extent experimental work on aluminium heatsinks, integrated with forced convection, is performed in order to measure their thermal capacities. Comparison of the heat performance of a typical aluminium heatsink, which was the best among the all aluminium heat sinks and proposed copper heatsink under identical experimental conditions, is performed. Also in some numerical efforts, optimizing and predicting of the thermal characterization of the proposed heatsink with inclined free fins is developed. The model is scaled up in the fluent environment to predict its application in the cooling of larger heat generated electronic devices. Impingement air-cooling mode of force-convection is adopted for heat dissipation from high power electronic devices in associated with the proposed inclined fin model. Components of airflow velocity in the hollow spaces of the heatsink are discussed. Pressure drop and other thermal variables are analyzed analytical and by CFD code. Another mechanical manufactured copper heat sink is investigated. A new design of the base and fins is optimized. A three-dimensional finite volume method is developed to determine the performance of the proposed heatsink. Thermal and hydraulic characterization of the heat sink under air-forced convection cooling condition is studied. The flow behavior around the fins and some other parts of the heat sink is analyzed by utilizing CFD code. The hydraulic parameters including velocity profiles, distribution of static pressure, dynamic pressure, boundary layer and fluid temperature between the fins and in the passageway at the middle of the heat sink are analyzed and presented schematically. Furthermore the thermal characteristic of the proposed heatsink is studied by contouring the three dimensional temperature distributions through the fins and temperature of the heat source by CFD code.

A molten carbonate fuel cell (MCFC) is an electro-chemical energy conversion technology that runs on natural gas and employs a molten salt electrolyte. In order to keep the electrolyte in this state, the cell must be kept at a temperature above 500 C, eliminating the need for precious metals as the catalyst. There has been only a limited amount of research on modelling the transport processes inside this device, mainly due to its limited ability for mobile applications. In this thesis, three one-dimensional models of a MCFC are presented based on different types of diffusion and convection. Comparisons between models are performed so as to assess their validity. Regarding ion transport, it is shown that there exists a limiting case for ion migration across the cathode that depends on the conductivity for the liquid potential. Finally, an optimization of the diffusivity across the cathode is carried out in an attempt to increase the cell performance and its longevity. / UOIT

Neste trabalho foi realizado um estudo para verificar as melhores condições de vazão das atuais lanças supersônicas utilizadas no forno elétrico a arco 3 da Siderúrgica Riograndense. Também foi realizado um teste comparativo entre o modelo de lança supersônica atual e um novo modelo de injetor proposto. Para determinar as melhores condições de vazão das injetoras atuais, avaliou-se parâmetros como o consumo de oxigênio, energia elétrica, teor de FeO da escória, condições de desgaste do refratário e erosão dos bicos injetores. Para os testes comparativos com o novo modelo de injetores, foram usinados dois bicos de cobre com menor diâmetro de garganta. As novas pressões e vazões de oxigênio, tanto para o trabalho no modo alta vazão como para o modo purga, foram estabelecidas com base em estudos das características dos bicos utilizados atualmente. Os testes foram realizados em caráter comparativo no próprio forno 3. Nos atuais modelos de injetores utilizados, verificou-se que a pressão no modo purga deve variar entre 0,9 e 1,1 kgf/cm2 na rede de oxigênio. Assim, a vazão de O2 varia entre 65 e 75 Nm3/h, intervalo no qual foi observada a melhor eficiência na operação, considerando principalmente o controle do FeO da escória e a ocorrência de entupimento dos bicos supersônicos. Na alta vazão foram definidas pressões entre 9,0 e 9,5 kgf/cm2, onde as vazões variam entre 350 e 375 Nm3/h por bico. Estes valores foram definidos avaliando-se principalmente o controle do consumo de refratário na região do injetor e o desgaste dos bicos causado por jato subacelerado. Os injetores com diâmetro de garganta menor possibilitaram a operação com vazões de O2 menores na purga em relação ao modelo atual. Assim, foi possível operar com vazão em torno de 50 Nm3/h a uma pressão de 0,9 kgf/cm2, sem a ocorrência de entupimentos. Porém no modo alta vazão, para garantir a vazão mínima de 350 Nm3/h, a pressão no bico foi elevada para 12,5 kgf/cm2. Com este novo modelo de injetor, os consumos médios de oxigênio e de energia elétrica reduziram 0,8 Nm3/t e 12,9 kWh/t, respectivamente, em relação ao injetor atual, e verificou-se o aumento de 0,92% no rendimento metálico. / In this work, a study to verify the best conditions of oxygen flow to operate the supersonic injectors currently used in the Electric Arc Furnace 3 (EAF 3) of Siderúrgica Riograndense was carried out. Also, a comparative study between the supersonic injector model currently used and a new proposed model was made. To determine the best flow conditions of current injectors, parameters such as oxygen and electricity consumption, and slag FeO content were evaluated. Moreover, refractory wear conditions and copper lance tips erosion were analyzed. For the comparative tests with the new model, two copper lance tips have been machined, with a smaller throat diameter. The new oxygen pressure and oxygen flow (high and low flow operating modes) were established based on studies of features of the currently used lance tips. The tests were carried out comparatively in the same EAF 3. For the currently used injector models, it was verified that the pressure in the low flow mode must be kept between 0.9 and 1.1kgf/cm2 in the oxygen system. Thus, the O2 flow varies between 65 and 75 Nm3/h, interval in which the best efficiency in the operation was observed, considering mainly the control of FeO of the slag, and the occurrence of clogging of the supersonic lance tips. High flow pressures were defined between 9.0 and 9.5 kgf/cm2, where the flow varies between 350 and 375 Nm3/h per lance tip. These values were defined evaluating mainly the control of the refractory wear in the region of the injector, and the erosion of the lance tips caused by under-blown jet. The new lance tips with smaller throat diameter made it possible to operate with smaller O2 flow, 50 Nm3/h with pressure of 0.9 kgf/cm2, without clogging in low flow steps. However, in the high flow, to guarantee the minimum flow of 350 Nm3/h, the pressure in the lance tips was raised to 12.5 kgf/cm2. With this new model of injector, the average consumption of oxygen was lowered by 0.8 Nm3/h compared to the current injector and an increase of 0.92% was verified in the metallic yield. Furthermore, there was a reduction of 12.9 kWh/t in the consumption of electric energy.

Neste trabalho foi realizado um estudo para verificar as melhores condições de vazão das atuais lanças supersônicas utilizadas no forno elétrico a arco 3 da Siderúrgica Riograndense. Também foi realizado um teste comparativo entre o modelo de lança supersônica atual e um novo modelo de injetor proposto. Para determinar as melhores condições de vazão das injetoras atuais, avaliou-se parâmetros como o consumo de oxigênio, energia elétrica, teor de FeO da escória, condições de desgaste do refratário e erosão dos bicos injetores. Para os testes comparativos com o novo modelo de injetores, foram usinados dois bicos de cobre com menor diâmetro de garganta. As novas pressões e vazões de oxigênio, tanto para o trabalho no modo alta vazão como para o modo purga, foram estabelecidas com base em estudos das características dos bicos utilizados atualmente. Os testes foram realizados em caráter comparativo no próprio forno 3. Nos atuais modelos de injetores utilizados, verificou-se que a pressão no modo purga deve variar entre 0,9 e 1,1 kgf/cm2 na rede de oxigênio. Assim, a vazão de O2 varia entre 65 e 75 Nm3/h, intervalo no qual foi observada a melhor eficiência na operação, considerando principalmente o controle do FeO da escória e a ocorrência de entupimento dos bicos supersônicos. Na alta vazão foram definidas pressões entre 9,0 e 9,5 kgf/cm2, onde as vazões variam entre 350 e 375 Nm3/h por bico. Estes valores foram definidos avaliando-se principalmente o controle do consumo de refratário na região do injetor e o desgaste dos bicos causado por jato subacelerado. Os injetores com diâmetro de garganta menor possibilitaram a operação com vazões de O2 menores na purga em relação ao modelo atual. Assim, foi possível operar com vazão em torno de 50 Nm3/h a uma pressão de 0,9 kgf/cm2, sem a ocorrência de entupimentos. Porém no modo alta vazão, para garantir a vazão mínima de 350 Nm3/h, a pressão no bico foi elevada para 12,5 kgf/cm2. Com este novo modelo de injetor, os consumos médios de oxigênio e de energia elétrica reduziram 0,8 Nm3/t e 12,9 kWh/t, respectivamente, em relação ao injetor atual, e verificou-se o aumento de 0,92% no rendimento metálico. / In this work, a study to verify the best conditions of oxygen flow to operate the supersonic injectors currently used in the Electric Arc Furnace 3 (EAF 3) of Siderúrgica Riograndense was carried out. Also, a comparative study between the supersonic injector model currently used and a new proposed model was made. To determine the best flow conditions of current injectors, parameters such as oxygen and electricity consumption, and slag FeO content were evaluated. Moreover, refractory wear conditions and copper lance tips erosion were analyzed. For the comparative tests with the new model, two copper lance tips have been machined, with a smaller throat diameter. The new oxygen pressure and oxygen flow (high and low flow operating modes) were established based on studies of features of the currently used lance tips. The tests were carried out comparatively in the same EAF 3. For the currently used injector models, it was verified that the pressure in the low flow mode must be kept between 0.9 and 1.1kgf/cm2 in the oxygen system. Thus, the O2 flow varies between 65 and 75 Nm3/h, interval in which the best efficiency in the operation was observed, considering mainly the control of FeO of the slag, and the occurrence of clogging of the supersonic lance tips. High flow pressures were defined between 9.0 and 9.5 kgf/cm2, where the flow varies between 350 and 375 Nm3/h per lance tip. These values were defined evaluating mainly the control of the refractory wear in the region of the injector, and the erosion of the lance tips caused by under-blown jet. The new lance tips with smaller throat diameter made it possible to operate with smaller O2 flow, 50 Nm3/h with pressure of 0.9 kgf/cm2, without clogging in low flow steps. However, in the high flow, to guarantee the minimum flow of 350 Nm3/h, the pressure in the lance tips was raised to 12.5 kgf/cm2. With this new model of injector, the average consumption of oxygen was lowered by 0.8 Nm3/h compared to the current injector and an increase of 0.92% was verified in the metallic yield. Furthermore, there was a reduction of 12.9 kWh/t in the consumption of electric energy.

Neste trabalho foi realizado um estudo para verificar as melhores condições de vazão das atuais lanças supersônicas utilizadas no forno elétrico a arco 3 da Siderúrgica Riograndense. Também foi realizado um teste comparativo entre o modelo de lança supersônica atual e um novo modelo de injetor proposto. Para determinar as melhores condições de vazão das injetoras atuais, avaliou-se parâmetros como o consumo de oxigênio, energia elétrica, teor de FeO da escória, condições de desgaste do refratário e erosão dos bicos injetores. Para os testes comparativos com o novo modelo de injetores, foram usinados dois bicos de cobre com menor diâmetro de garganta. As novas pressões e vazões de oxigênio, tanto para o trabalho no modo alta vazão como para o modo purga, foram estabelecidas com base em estudos das características dos bicos utilizados atualmente. Os testes foram realizados em caráter comparativo no próprio forno 3. Nos atuais modelos de injetores utilizados, verificou-se que a pressão no modo purga deve variar entre 0,9 e 1,1 kgf/cm2 na rede de oxigênio. Assim, a vazão de O2 varia entre 65 e 75 Nm3/h, intervalo no qual foi observada a melhor eficiência na operação, considerando principalmente o controle do FeO da escória e a ocorrência de entupimento dos bicos supersônicos. Na alta vazão foram definidas pressões entre 9,0 e 9,5 kgf/cm2, onde as vazões variam entre 350 e 375 Nm3/h por bico. Estes valores foram definidos avaliando-se principalmente o controle do consumo de refratário na região do injetor e o desgaste dos bicos causado por jato subacelerado. Os injetores com diâmetro de garganta menor possibilitaram a operação com vazões de O2 menores na purga em relação ao modelo atual. Assim, foi possível operar com vazão em torno de 50 Nm3/h a uma pressão de 0,9 kgf/cm2, sem a ocorrência de entupimentos. Porém no modo alta vazão, para garantir a vazão mínima de 350 Nm3/h, a pressão no bico foi elevada para 12,5 kgf/cm2. Com este novo modelo de injetor, os consumos médios de oxigênio e de energia elétrica reduziram 0,8 Nm3/t e 12,9 kWh/t, respectivamente, em relação ao injetor atual, e verificou-se o aumento de 0,92% no rendimento metálico. / In this work, a study to verify the best conditions of oxygen flow to operate the supersonic injectors currently used in the Electric Arc Furnace 3 (EAF 3) of Siderúrgica Riograndense was carried out. Also, a comparative study between the supersonic injector model currently used and a new proposed model was made. To determine the best flow conditions of current injectors, parameters such as oxygen and electricity consumption, and slag FeO content were evaluated. Moreover, refractory wear conditions and copper lance tips erosion were analyzed. For the comparative tests with the new model, two copper lance tips have been machined, with a smaller throat diameter. The new oxygen pressure and oxygen flow (high and low flow operating modes) were established based on studies of features of the currently used lance tips. The tests were carried out comparatively in the same EAF 3. For the currently used injector models, it was verified that the pressure in the low flow mode must be kept between 0.9 and 1.1kgf/cm2 in the oxygen system. Thus, the O2 flow varies between 65 and 75 Nm3/h, interval in which the best efficiency in the operation was observed, considering mainly the control of FeO of the slag, and the occurrence of clogging of the supersonic lance tips. High flow pressures were defined between 9.0 and 9.5 kgf/cm2, where the flow varies between 350 and 375 Nm3/h per lance tip. These values were defined evaluating mainly the control of the refractory wear in the region of the injector, and the erosion of the lance tips caused by under-blown jet. The new lance tips with smaller throat diameter made it possible to operate with smaller O2 flow, 50 Nm3/h with pressure of 0.9 kgf/cm2, without clogging in low flow steps. However, in the high flow, to guarantee the minimum flow of 350 Nm3/h, the pressure in the lance tips was raised to 12.5 kgf/cm2. With this new model of injector, the average consumption of oxygen was lowered by 0.8 Nm3/h compared to the current injector and an increase of 0.92% was verified in the metallic yield. Furthermore, there was a reduction of 12.9 kWh/t in the consumption of electric energy.