La energía se ha convertido en una necesidad vital para garantizar el desarrollo de las sociedades modernas. Entre las diferentes posibles alternativas para producir energía, el hidrogeno presenta varias características que lo convierten en un atractivo vector energético: primero, se trata de una tecnología más eficiente para transformar la energía química en electricidad -por ejemplo, utilizando pilas de-combustible, las cuales también reducen de manera significativa los niveles de emisión de CO2 -; en segundo lugar, el hidrogeno puede ser producido a partir de una amplia variedad de materias primas, incluyendo recursos renovables y no renovables. Sin embargo, las tecnologías para producir hidrogeno para applicaciones con pilas de combustible aun requieren de un esfuerzo en investigación y desarrollo.El objetivo principal de esta tesis fue de evaluar técnicamente las opciones para preparar y utilizar catalizadores en placas insertados en un reactor de pared catalítica para producir hidrogeno mediante el reformado por vapor de etanol bajo condiciones de alta eficiencia térmica. Para completar el objetivo general y los objetivos específicos, se diseño un plan experimental sistemático, compuesto de tres partes: documentación, experimentación y simulación numérica. La información utilizada se puede clasificar en tres ramas: primero, una revisión detallada de las características generales que presentan las técnicas de reformado, seguido por una revisión descriptiva del reformado por vapor de etanol, enfocado en los principales aspectos de la preparación de catalizadores y la realización de la reacción química. A continuación en segundo lugar, se presenta una descripción acerca de reactores estructurados y los métodos para preparar catalizadores. Por último, en tercer lugar, se expone una explicación centrada en los materiales, equipos y métodos empleados para explorar el rendimiento de los catalizadores. Esta parte incluye la descripción de: algunas de las técnicas analíticas más comunes para caracterizar y evaluar tanto catalizadores como compuestos químicos y la descripción de las herramientas utilizadas en la simulación numérica.El primer bloque de simulación numérica tiene como fin evaluar las posibles restricciones termodinámicas por medio de análisis específicos basados en el equilibrio termodinámico, tanto del reactor como del proceso integrado. Luego, se ejecuta un mapeo del conjunto de condiciones operacionales, compuesto por cuatro variables principales: (temperatura, relación vapor carbón, presión y factor de recobro de hidrogeno en el separador de membrana). Ello con el fin de garantizar una operación auto-térmica del procesador de combustible. Se compara la habilidad y la ventaja entre los diferentes tipos de catalizadores publicados en trabajos previos en base a las condiciones termodinámicas ideales determinadas en el análisis termodinámico.Para los catalizadores en polvo, se realizo experimentos de caracterización y reacción mediante el empleo de un reactor de lecho fijo. Se ha efectuado un estudio sistematico para comparar la actividad y la selectividad de dos tipos de catalizadores, bajo condiciones moderadas de temperatura y relación vapor carbón. Los catalizadores basados en níquel (Ni/La2O3-Al2O3) y cobalto (Co-Fe/ZnO y Co-Mn/ZnO) han sido preparados y probados a las siguientes condiciones: temperatura en el rango de 400-500°C, relación vapor carbono entre 2 y 4, tiempo de contacto desde 4.3 hasta 1100 min·gcat molEtOH-1, cubriendo un rango de conversión de etanol desde 20 hasta 100%. Se ha efectuado un diseño de análisis multifactorial para establecer la influencia de las variables (temperatura, relación vapor carbón, tiempo de contacto y formulación del catalizador) en términos de la conversión de etanol y la selectividad hacia los diferentes productos.Por último, se ha efectuado la caracterización, simulación y experimentación utilizando una configuración de reactor de pared catalítica. Primero, se emplea un modelo en 2D para analizar las características principales del reactor de pared catalítica diseñado y construido para realizar la reacción sobre las placas con catalizador previamente preparadas. En segundo lugar, se expone de manera detallada el método seguido para preparar dos tipos diferentes de placas catalíticas. Estas placas con catalizador son caracterizadas de manera similar al método empleado con los catalizadores en polvo. Luego, se ha realizado un estudio sistemático para comparar la actividad y la selectividad de los dos tipos de placas catalíticas. Por último, mediante un modelo 1D se revelan aspectos fundamentales de la configuración del reactor de pared catalítica utilizando una configuración con dos canales paralelos, en los cuales se ejecutan una reacción endotérmica y otra exotérmica respectivamente.La principal conclusión de este trabajo es que el reformado por vapor de etanol puede ser realizado bajo condiciones de alta eficiencia térmica si se emplea un diseño basado en un reactor de pared catalítica con recobro de calor integrado a una unidad de separación para la purificación del hidrogeno. Las placas catalíticas han demostrado ser un elemento fundamental en este tipo de reactor porque incrementan de manera significativa el transporte de calor que se requiere para sostener las reacciones endotérmicas. / Energy has become a fundamental necessity to guarantee modern society development. Among different alternatives possible to produce energy, hydrogen presents several characteristics which make it an attractive energy vector: first, more efficient processes to transform chemical energy into electricity -such as Fuel Cells that, in addition, will help to reduce significantly CO2 emission levels-; and second, hydrogen can be produced from a large variety of feed stocks, including fossil and renewable resources. However, as hydrogen production technologies for Fuel Cell applications are not available commercially yet, it still requires additional R&D efforts.The principal objective of this thesis was to evaluate technical feasibility for preparing and using catalytic plates in a Catalytic Wall Reactor configuration to produce hydrogen by Steam Reforming of Ethanol under conditions of high thermal efficiency. To fulfill the overall and specific objectives, a systematic experimental plan was designed and executed. It was composed of three main parts: documentation, experimentation and numerical simulation. Background information is divided into three branches, first a detailed overview of technical features for reforming technology, followed by a descriptive review of Steam Reforming of Ethanol key aspects for catalysts preparation and reaction performance. Third is presented a comprehensive examination on structured reactor and catalyst preparation methods. In this part is exposed a detailed explanation of materials, equipments, and methods employed for screening catalyst and evaluating catalytic reactor performance. Also, is presented employed techniques for catalyst characterization and fluid analysis. Finally are described tools for numerical simulation.First component of numerical simulations evaluates possible thermodynamic constrains through specific analyses based on thermodynamic equilibrium of reactor and integrated fuel processor. Then, is performed a mapping for the set of four operational variables (temperature, steam to carbon ratio, pressure, and hydrogen recovery in the membrane separator), that allow an auto-thermal operation of the fuel processor. The suitability and advantages of the different catalysts preparations that are known from recent publications are discussed on the basis of the operation conditions determined on the thermodynamic analysis.Experimental work is performed for powder catalyst characterization and catalytic experimentation using a Packed Bed Reactor (PBR). It has conducted a systematic study to compare the activity and selectivity of two types of catalyst at moderate temperature and steam to carbon (SC) ratios. Nickel-based catalysts (Ni/La2O3-Al2O3) and novel Co-based catalysts (Co-Fe/ZnO and Co-Mn/ZnO) have been prepared and tested at temperatures of 400 and 500 °C, Steam to Carbon (SC) molar ratios of 2 and 4, and contact times from 4.3 to 1100 min·gcat molEtOH-1, covering a range of ethanol conversion from 20 to 100%. A multifactorial design analysis has been conducted to establish the significance of temperature, SC ratio, contact time and catalyst formulation on ethanol conversion and selectivity towards the different reaction products.At last, it is carried out the catalytic plate characterization, simulation and experimentation using a Catalytic Wall Reactor configuration. First, is used a 2D modeling to analyze main characteristics of the Catalytic Wall Reactor designed and constructed to perform reactions on the prepared catalytic plates. Prepared catalytic plates are characterize in a similar way to that employed for the powder catalysts. After that, it was conducted a systematic study to compare the activity and selectivity of two types of catalytic plates. 1D model reveals main aspects on thermal performance for a theoretical Catalytic Wall Reactor using two co-current channels with endothermic and exothermic reactions respectively.Main conclusion from this work is that Steam Reforming of Ethanol can be performed at high thermal efficiency if the design of the fuel processor is based on structured catalytic wall reactors with integrated heat recovery coupled to a separation unit for hydrogen purification. Catalytic plates have proven to be a key component on CWR because improves significantly the heat transfer which is required to sustain endothermic reactions.

The conversion of ethanol to hydrogen or syngas can be achieved by reacting ethanol with water via steam reforming, CH3CH2OH + (1-x)H2O = (4-x)H2 + (2-x)CO + xCO2 (R.1) CH3CH2OH + H2O = 4H2 + 2CO (R.2) CO + H2O = H2 + CO2 (R.3) Ideally, the ethanol steam reforming reaction can achieve a hydrogen yield of 6 moles of hydrogen per mole of ethanol when the value of x in (R.1) equals 2. High theoretical H2 yield makes ethanol steam reforming a very attractive route for H2 production. Thermodynamic equilibrium studies have shown that ethanol steam reforming produces mixtures of H2, CO, CO2, and CH4 below 950 K, while above 950 K the ethanol steam reforming reaction (R.1) adequately describes the product composition In this study a series of 10wt% Ni loaded Mg-Al mixed oxide supported catalysts were evaluated for the production of hydrogen via the steam reforming of ethanol. Mg-Al mixed oxide supported nickel catalysts were found to give superior activity, steam reforming product selectivity (H2 and COx), and improved catalyst stability than the pure oxide supported nickel catalyst at both temperatures investigated. Activity, product selectivity, and catalyst stability were dependent upon the Al and Mg content of the support. At 923 K, the Mg-Al mixed oxide supported nickel catalysts were the best performing catalysts exhibiting the highest steam reforming product yield and were highly stable, showing no signs of deactivation after 20 h of operation. The improved performance of the Mg-Al mixed oxide supported catalysts was related to the incorporation of the pure oxides, MgO and Al2O3, into MgAl2O4. The formation of MgAl2O4 reduced nickel incorporation with the support material since MgAl2O4 does not react with Ni; therefore, nickel was retained in its active form. In addition, incorporation of Mg and Al in to MgAl2O4, a slight basic material, modified the acid-base properties resulting in a catalyst that exhibited moderate acidic and basic site strength and density compared to the pure oxide supported catalysts. Moderation of the acid-base properties improved the activity, selectivity, and stability of the catalysts by reducing activity for by-product reactions producing ethylene and acetaldehyde. At lower reaction temperatures, below 823 K, Mg-Al mixed oxide supported nickel catalysts experienced substantial deactivation resulting in reduced ethanol conversion but interestingly, the H2 and CO2 yields increased, exceeding equilibrium expectations with time on stream while CH4 yield decreased far below equilibrium expectations, suggesting a direct ethanol steam reforming reaction pathway. Over stabilized Mg-Al mixed oxide supported nickel catalysts, direct ethanol steam reforming was activated by a reduction in the catalyst’s activity for the production and desorption of CH4 from the surface. The effect of pressure on the direct ethanol steam reforming reaction pathway over stabilized Mg-Al mixed oxide supported nickel catalysts was investigated at 673 and 823 K. At 823 K, increasing the total pressure resulted in a product distribution that closely matched the thermodynamic expectations. However, at 673 K, the product distribution deviated from thermodynamic expectations, giving substantially greater yields for the steam reforming products, H2, CO, and CO2, while CH4 yield was consistently less than equilibrium expectations. The identification of an alternative direct ethanol steam reforming reaction pathway at relatively low temperatures (below 823 K) that could be operated at elevated pressures will result in an energy efficient process for the production of hydrogen from bio-ethanol.

The conversion of ethanol to hydrogen or syngas can be achieved by reacting ethanol with water via steam reforming, CH3CH2OH + (1-x)H2O = (4-x)H2 + (2-x)CO + xCO2 (R.1) CH3CH2OH + H2O = 4H2 + 2CO (R.2) CO + H2O = H2 + CO2 (R.3) Ideally, the ethanol steam reforming reaction can achieve a hydrogen yield of 6 moles of hydrogen per mole of ethanol when the value of x in (R.1) equals 2. High theoretical H2 yield makes ethanol steam reforming a very attractive route for H2 production. Thermodynamic equilibrium studies have shown that ethanol steam reforming produces mixtures of H2, CO, CO2, and CH4 below 950 K, while above 950 K the ethanol steam reforming reaction (R.1) adequately describes the product composition In this study a series of 10wt% Ni loaded Mg-Al mixed oxide supported catalysts were evaluated for the production of hydrogen via the steam reforming of ethanol. Mg-Al mixed oxide supported nickel catalysts were found to give superior activity, steam reforming product selectivity (H2 and COx), and improved catalyst stability than the pure oxide supported nickel catalyst at both temperatures investigated. Activity, product selectivity, and catalyst stability were dependent upon the Al and Mg content of the support. At 923 K, the Mg-Al mixed oxide supported nickel catalysts were the best performing catalysts exhibiting the highest steam reforming product yield and were highly stable, showing no signs of deactivation after 20 h of operation. The improved performance of the Mg-Al mixed oxide supported catalysts was related to the incorporation of the pure oxides, MgO and Al2O3, into MgAl2O4. The formation of MgAl2O4 reduced nickel incorporation with the support material since MgAl2O4 does not react with Ni; therefore, nickel was retained in its active form. In addition, incorporation of Mg and Al in to MgAl2O4, a slight basic material, modified the acid-base properties resulting in a catalyst that exhibited moderate acidic and basic site strength and density compared to the pure oxide supported catalysts. Moderation of the acid-base properties improved the activity, selectivity, and stability of the catalysts by reducing activity for by-product reactions producing ethylene and acetaldehyde. At lower reaction temperatures, below 823 K, Mg-Al mixed oxide supported nickel catalysts experienced substantial deactivation resulting in reduced ethanol conversion but interestingly, the H2 and CO2 yields increased, exceeding equilibrium expectations with time on stream while CH4 yield decreased far below equilibrium expectations, suggesting a direct ethanol steam reforming reaction pathway. Over stabilized Mg-Al mixed oxide supported nickel catalysts, direct ethanol steam reforming was activated by a reduction in the catalyst’s activity for the production and desorption of CH4 from the surface. The effect of pressure on the direct ethanol steam reforming reaction pathway over stabilized Mg-Al mixed oxide supported nickel catalysts was investigated at 673 and 823 K. At 823 K, increasing the total pressure resulted in a product distribution that closely matched the thermodynamic expectations. However, at 673 K, the product distribution deviated from thermodynamic expectations, giving substantially greater yields for the steam reforming products, H2, CO, and CO2, while CH4 yield was consistently less than equilibrium expectations. The identification of an alternative direct ethanol steam reforming reaction pathway at relatively low temperatures (below 823 K) that could be operated at elevated pressures will result in an energy efficient process for the production of hydrogen from bio-ethanol.

<p>Biomass derived oil (BDO) reforming with CO2 was carried out at 800oC under atmospheric pressure in a tubular fixed bed vertical reactor packed with quartz particles. The feed gas was a mixture of CO2 and N2 at various compositions with a flow rate of 30 to 60 cm3/min. The BDO flow rate was 5 g/h. The product gas consisted mostly of H2, CO, CO2, CH4 and C2H4.</p><p>The maximum production of synthesis gas (~76 mol%) was observed at a total carrier gas flow rate of 60 cm3/min and a mole fraction of CO2 in carrier gas of 0.1. Maximum hydrogen (42 mol%) and H2 to CO molar ratio (1.44) were obtained while using only N2 as the carrier gas at a flow rate of 50 cm3/min. In the range of residence time considered, CO2 was not consumed in BDO gasification at 800oC but helped to increase gas production at the expense of the char.</p><p>Pyrolysis of lard was performed to produce a diesel-like liquid and a high heating value gaseous fuel. Lard was fed into the reactor at 5 g/h using N2 (10-70 cm3/min) as carrier gas. Two particle size ranges of quartz particles (0.7-1.4 and 1.7-2.4 mm) were used as reactor packing material. The liquid product essentially consisted of linear and cyclic alkanes and alkenes, aromatics, ketones, aldehydes and carboxylic acids. The maximum yield for diesel-like liquid product (37g/100g lard) was obtained at 600oC, residence time of 1.5 s and packing particle size of 1.7- 2.4 mm. The liquid product obtained at 600oC, carrier gas flow rate of 50 cm3/min and quartz packing particle size of 0.7-1.4 mm has a cetane index of 46, specific gravity of 0.86, a heating value of 40 MJ/kg and cloud and pour points of 10 and -18 respectively. The heating value of the product gas ranged between 68 and 165 MJ/m3. This study shows that there is a potential for producing diesel-like liquid from pyrolysis of lard. It also identifies the pyrolysis of animal fats as a source of high heating value gaseous fuel.</p><p>Steam reforming of lard was performed at 500, 550, 600 and 800oC and at steam to lard mass ratios of 0.5 to 2.0. The maximum diesel-like liquid yield from the steam reforming process (39 g/100g of lard) was obtained at a steam to lard ratio of 1.5 and a temperature of 600oC. Higher cetane index (52) and lower viscosity (4.0 mPa.s at 40oC) were obtained by addition of steam. The net energy recovered from pyrolysis and steam reforming processes were 21.7and 21.9 kJ/g of lard respectively. Thus, the processes are energy efficient.</p><p>In comparison, lard is a better feedstock for the production of hydrogen, char, high heating value gas and high H2/CO ratio than BDO. On the other hand, BDO is the preferred feedstock for the production of synthesis gas with H2/CO in the vicinity of 1.</p>

Steam has been widely used as the source of heating in commercial buildings and industries throughout the twentieth century. Even though contemporary designers have moved to hot water as the primary choice for heating, a large number of facilities still use steam for heating. Medical campuses with on-site steam generation and extensive distribution systems often serve a number of buildings designed prior to the mid-1980s. The steam is typically used for preheat as its high thermal content helps in heating the air faster and prevents coils from freezing in locations with extreme weather conditions during winter. The present work provides a comprehensive description of the various types of steam heating systems, steam coils, and valves to facilitate the engineer's understanding of these steam systems. A large percentage of the steam coils used in buildings are provided with medium pressure steam. Veterans Integrated Service Network and Army Medical Command Medical Facilities are examples which use medium pressure steam for heating. The current design manual for these medical facilities recommends steam at 30psig be provided to these coils. In certain cases although the steam heating coil is designed for a 5psig steam pressure, it is observed that higher pressure steam is supplied at the coil. A higher steam pressure may lead to excessive heating, system inefficiency due to increased heat loss, simultaneous heating and cooling, and increased maintenance cost. Field experiments were conducted to evaluate the effect of lowering steam pressure on the system performance. A 16% reduction in temperature rise across the coil was found when the steam pressure in the coil was reduced from 15psig to 5psig. The rise in temperature with lower pressure steam was sufficient to prevent coil freeze-up even in the most severe weather conditions. Additional benefits of reduced steam pressure are reduced flash steam losses (flash steam is vapor or secondary steam formed when hot condensate from the coil is discharged into a lower pressure area, i.e., the condensate return line) and radiation losses, increased flow of air through the coil thereby reducing air stratification and reduced energy losses in the event of actuator failure. The work also involved evaluating the existing control strategies for the steam heating system. New control strategies were developed and tested to address the short comings of existing sequences. Improved temperature control and occupant comfort; elimination of valve hunting and reduced energy consumption were benefits realized by implementing these measures.

A novel method to enhance oil production during cyclic steam injection has been developed. In the Top-Injection and Bottom-Production (TINBOP) method, the well contains two strings separated by two packers (a dual and a single packer): the short string (SS) is completed in the top quarter of the reservoir, while the long string (LS) is completed in the bottom quarter of the reservoir. The method requires an initial warm-up stage where steam is injected into both strings for 21 days; then the LS is opened to production while the SS continues to inject steam for 14 days. After the initial warm-up, the following schedule is repeated: the LS is closed and steam is injected in the SS for 21 days; then steam injection is stopped and the LS is opened to production for 180 days. There is no soak period. Simulations to compare the performance of the TINBOP method against that of a conventional cyclic steam injector (perforated across the whole reservoir) have been made. Three reservoir types were simulated using 2-D radial, black oil models: Hamaca (9°API), San Ardo (12°API) and the SPE fourth comparative solution project (14°API). For the first two types, a 20x1x20 10-acre model was used that incorporated typical rock and fluid properties for these fields. Simulation results indicate oil recovery after 10 years was 5.7-27% OIIP with TINBOP, that is 57-93% higher than conventional cyclic steam injection (3.3-14% OIIP). Steam-oil ratios were also decreased with TINBOP (0.8-3.1%) compared to conventional (1.2-5.3%), resulting from the improved reservoir heating efficiency.

Simulation study has shown oil production is accelerated when propane is used as an additive during steam injection. To better understand this phenomenon, distillation experiments were performed using San Ardo crude oil (12oAPI). For comparison purposes, three distillation processes were investigated: dry-, steam-, and steam-propanedistillation, the latter at the propane-to-steam mass ratio of 0.05 at steam injection rate 0.5 g/min. Two sets of the distillation experiments were carried out. In the first set of experiments, the distillation temperatures ranged from 115ºC to 300ºC. Distillation pressures ranged from 0 psig to 998 psig for steam- and steam-propane distillation. The temperature-pressure combination used represented 15ºC superheated steam conditions. In the second set of experiments, the distillation temperatures ranged from 220oC to 300oC at 260 psig. The temperature pressure combination used represented field conditions for crude oil. For both conditions, the cell was kept at each temperature plateau (cut) until no increase occurs in distillation yields. Distillation yields were collected at each cut, and the volume and weight of water and hydrocarbon measured. Based on these experiments, a thermodynamic modeling framework was developed that describes distillation effect and oil production for steam distillation experiments. The model is based on composition of crude oil, molecular weight of heavy fraction. The analytical model results are compared against the experimental data for synthetic crude and crude oil to verify the validity of the model. Main results of the study may be summarized as follows. The yields for steam distillation for saturated conditions of Tsat+15 o C and Psat is 10 % and with addition of 5% of propane to steam no significant increase occurs in distillation yields. The yields for steam distillation for field conditions of 260 psig and temperature range (220 ~300oC) is 18 % and with addition of 5% of propane to steam no significant increase in distillation yields. The results indicate that propane has minimal distillation effect on the heavy oil. This occurs possibly because of lesser amount of light fractions in the heavy oil that enhance the separation of components in the oil caused by the concentration gradient.

Thesis--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references (p.59-62).

Thesis (M.S.)--Mississippi State University. Department of Mechanical Engineering. / Title from title screen. Includes bibliographical references.

Computer Science fields have a difficult time engaging underrepresented populations such as African Americans and women. EarSketch is an approach to engage these student through authentic STEAM learning involving computational music remixing. EarSketch has been used in several pilot studies. In this study, students from one pilot study participated in a focus group to understand the effectiveness of EarSketch in engaging underrepresented minorities. Qualitative analysis shows a variety of contributing factors in engagement such as motivation, confidence, identity, conceptualization, and creativity.