DSpace Repository :: Browsing by Subject "PRODUCCION DE HIDROGENO"

Browsing by Subject "PRODUCCION DE HIDROGENO"

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Advances in alkaline water electrolyzers: a review
(2019-06) David, Martín Rafael; Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo
"The renewed concern for the care of the environment has led to lower emissions of greenhouse gases without sacrificing modern comforts. Widespread proposal focuses on energy produced from renewable sources and its subsequent storage and transportation based on hydrogen. Currently, this gas applies to the chemical industry and its production is based on fossil fuels. The introduction of this energy vector requires the development of environmental-friendly methods for obtaining it. In this paper, existing techniques are just presented and the main focus is made on electrolysis, a mature procedure. In turn, some developed proposals as previous steps to the hydrogen economy are presented. Finally, some lines of research to improve alkaline electrolysis technology are commented."
Applicability of a state-of-the-art engineering toolkit in the risk analysis of a prototypical Hydrogen refueling station
(2020) Ordóñez, Marco; Jordan, Thomas
En el desarrollo actual de los vehículos de celdas de combustible, las estaciones de servicio de hidrógeno desempeñan un papel importante como fuente directa de combustible. Uno de los principales aspectos que deben considerarse durante la instalación y el funcionamiento de una estación de servicio de hidrógeno es la seguridad tanto de la infraestructura como del personal que trabaja en ella. Sin embargo, la falta de herramientas de cálculo ampliamente aceptadas hace que las evaluaciones de riesgos sean difíciles de reproducir de una estación a otra. En el presente trabajo se estudia el potencial de aplicabilidad y se identifican las limitaciones de un software de cálculo ingenieril de código abierto para evaluación de riesgos, denominado HyRAM, para un proceso de evaluación de riesgos de una estación de servicio de hidrógeno prototípica basada en un caso real. Para ello, este trabajo inicia con una investigación de marco teórico sobre la metodología de evaluación de riesgos, el funcionamiento de una estación de servicio de hidrógeno y los peligros más relevantes presentes en este tipo de instalaciones. Para el análisis de consecuencias y probabilidades, luego se describen los principales modelos de cálculo de HyRAM y se seleccionan los escenarios de fallo a ser simulados con estos modelos. Se detallan las principales características de la estación prototipo de abastecimiento de hidrógeno. Se analizan dos conjuntos de escenarios de fugas de hidrógeno en la conexión roscada a la salida de la zona del compresor (donde interesan la gravedad de las consecuencias y la frecuencia de ocurrencia) mediante la radiación de la llama de jet para una ignición inmediata, y la sobrepresión para una combustión retardada. Para concluir la evaluación de riesgos, los resultados se convierten en una ponderación global de riesgos. Las principales conclusiones de este trabajo muestran como más importante que HyRAM es adecuada para un número acotado de escenarios, y que necesita incluir condiciones de borde adicionales para satisfacer el análisis de un caso real prototípico. En particular para el modelo de llama de jet, se observa la falta de un perfil de radiación de la llama que evolucione en el tiempo y facilite un cálculo preciso de la dosis térmica. Para el modelo de sobrepresión, el principal aspecto identificado es la falta de fiabilidad para describir los complejos fenómenos durante la evolución inicial de la mezcla aire-hidrógeno.
Development and programming of an engineering tool regarding the heat radiation of Hydrogen vertical jet flames
(2020) Redosado León, Kevin Arturo; Jedicke, Olaf
Esta tesis tiene como objetivo entender, programar y desarrollar una herramienta de ingeniería sobre la radiación de las llamas de chorros verticales de hidrógeno. El lenguaje de programación de Python 3.7 es utilizado para programar la herramienta electronica. El trabajo actual estudia las propiedades termodinámicas del hidrógeno mientras se somete a un purgado. El análisis utiliza la ecuación de estado de Abel-Noble (EOS) para modelar el hidrógeno como un gas real. Con estas propiedades, diferentes parámetros sobre la llama de hidrógeno son hallados empleando diferentes correlaciones para determinar parámetros como la fracción de calor radiado (𝐹), la longitud de la llama (𝐿𝑓) y el flujo de calor de la radiación térmica (𝑄𝑟). Los resultados calculados se comparan con los datos experimentales para determinar su validez. El algoritmo utilizado para programar la herramienta electronica se muestra en este trabajo. Además, el procedimiento para resolver problemas como el refinamiento del pasos del tiempo y la resolución espacial se dan en este trabajo.
Dynamic modelling of alkaline self-pressurized electrolyzers: a phenomenological-based semiphysical approach
(2020-09) David, Martín Rafael; Álvarez, Hernán; Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo
"This paper proposes a phenomenological based semiphysical model (PBSM) for a self-pressurized alkaline electrolyzer. The model, based on mass and energy balances, represents the dynamic behaviour of hydrogen and oxygen production using electrolysis. The model allows to anticipate operational variables as dynamic responses in the concentrations of the electrolytic cell, and variations in both, level and pressure, at the gas separation chambers due to the change in electric current. The model parameters have been adjusted based on experimental measurements taken from an available prototype and through a suitable identification process. Simulation results replicate the current dynamic response of the experimental self-pressurized electrolyzer assembly. This model proves to be useful in the improvement of the control of gas production rate in this kind of assemblies, both as a validated simulation platform and as a source of reduced order models for model-based control design."
Feasibility study of hydrogen fueled internal combustion hybrid bus operating under real traffic urban conditions in Buenos Aires, Argentina
(2018-12-18) Britz, Sven; Orbaiz, Pedro
"This thesis evaluates the technical, economic and environmental performance of a hydrogen fueled hybrid bus, which uses an internal combustion engine as a power unit. Results are compared to those of a conventional diesel bus and to those of two commercially available hydrogen fuel cell buses. The performance of the different vehicles, under real driving conditions, is evaluated using validated models of these on the Autonomie simulation platform. On the other hand, the life-cycle GHG emissions of the buses are estimated with hydrogen being produced from different primary sources. Whilst the first scenario assumes that hydrogen is produced from natural gas via steam methane reforming, the other three assumes electrolytic production using different electricity production mixes. Finally the total cost of ownership of each hybrid bus is calculated and compared to that of the conventional bus. Results show that all hydrogen buses have a considerable lower energy consumption than that of the conventional vehicle. This is manly due to the use of the hybrid powertrain architecture. When comparing the different hydrogen buses, as expected, the fuel cell vehicles result in a higher efficiency than the internal combustion engine vehicles, but in a considerable higher cost, making the use of internal combustion engines a more cost effective way to reduce GHG emissions. The life cycle emission analysis shows that the environmental performance of all hydrogen vehicles is highly dependent on the carbon intensity of the hydrogen production. Overall, whilst fuel cells are more efficient than ICEs, the considerable lower cost of ICEs makes the H2ICE hybrid bus a more cost effective way of reducing GHG emissions."
Mathematical modelling and advanced control design applied to high-pressure electrolyzers for hydrogen production
(2021-09) David, Martín Rafael; Sánchez-Peña, Ricardo; Ocampo-Martínez, Carlos
"This thesis is mainly dedicated to the study of high pressure alkaline electrolysis. Alkaline electrolysis is a well established technology and is commercially available. However, the operation at high pressure for dispensing compressors was not fully investigated. Moreover, there is a lack of dynamic models and publications related to control strategies. Therefore, this thesis contributes especially in the modelling and control of high pressure alkaline electrolyzers in order to improve purity of produced gases."
Model-based control design for H2 purity regulation in high-pressure alkaline electrolyzers
(2021-05) David, Martín Rafael; Bianchi, Fernando D.; Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo
"This paper proposes two control strategies that mitigate the cross contamination of H2 and O2 in a high-pressure alkaline electrolyzer, which consequently increases the supplied gases purity: one based on a decoupled PI scheme and the other based on optimal control tools. In order to reduce the diffusion of gases through the membrane, the controllers establish the opening of two outlet valves based on the pressure of the system and the difference in liquid level between both separation chambers. Therefore, two multiple input - multiple output controllers are designed here. For this purpose, a high-fidelity model previously developed was simplified in order to obtain a control-oriented model. The proposed controllers were evaluated in simulation using the high-fidelity nonlinear model in a wide operating range, which resulted in less than 1% impurity of gases."
Phenomenological based model of hydrogen production using an alkaline self-pressurized electrolyzer
(2019-08) David, Martín Rafael; Álvarez, Hernán; Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo
"The aim of this work is to develop the phenomenological based modeling of a self-pressurized alkaline electrolyser with the objective of predicting the cross-contamination of the gases produced. A proposed model, built in Matlab ® , represents the dynamical evolution in real electrolysers, and anticipates operational variables: level, pressure and all concentrations. Dynamic responses in the concentrations of the electrolytic cell, and variations in both level and pressure at the chamber due to the change in current and diffusivity, are reported. The equations by which the variables can be computed are also presented. The proposed model is ready for the corresponding adjustment of parameters based on experimental measurements taken from an available prototype and through a suitable identification process."
Use of energy surplus from local renewable sources, to produce electrolytic hydrogen for electricity generation at isolated places in Argentina
(2018-09-17) Oettinger, Sebastián Federico; De Bernardez, Leopoldo
"The aim of this project is to study the use of energy surplus from local renewable sources at isolated places in Argentina, to produce electrolytical hydrogen as clean fuel for electricity generation. Furthermore, the hydrogen production is seen as a storage technology to attenuate intermittent power supplies to microgrids. Significant knowledge, concerning Hydrogen production, storage and combustión, is available in Argentina at lab-prototype stage. Although experimental research is still required, this work is an approach to the utilization of the existing technology. Mostly, micro-grids depend on expensive energy generation, as gas turbines or diesel engines that have to work out of their optimal operating point. As case study, it is considered the city of Río Grande, placed at the province of Tierra del Fuego in Argentina, because it is not connected to the national grid and shows excellent wind conditions. Together with Río Grande, there are other micro-grids in the region, which could benefit from the incorporation of energy storage technologies and rely on renewable energy. The analysis of Río Grande’s energy situation, as well as the potential use of wind energy and Hydrogen storage, have shown synergies to reduce energy costs and emissions. Although a general solution was not reached, a scenario is shown in which the hydrogen production and the storage capacity are optimal to offer insight into the problematic and serve as reference for further investigations."

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