Dissertations / Theses on the topic 'Hydrogen storage tank'

Here we present the development of an aluminium alloy based hydrogen storage tank, charged with Ti-doped sodium aluminium hexahydride Na3AlH6. This hydride has a theoretical hydrogen storage capacity of 3 mass-% and can be operated at lower pressure compared to sodium alanate NaAlH4. The tank was made of aluminium alloy EN AW 6082 T6. The heat transfer was realised through an oil flow in a bayonet heat exchanger, manufactured by extrusion moulding from aluminium alloy EN AW 6060 T6. Na3AlH6 is prepared from 4 mol-% TiCl3 doped sodium aluminium tetrahydride NaAlH4 by addition of two moles of sodium hydride NaH in ball milling process. The hydrogen storage tank was filled with 213 g of doped Na3AlH6 in dehydrogenated state. Maximum of 3.6 g (1.7 mass-% of the hydride mass) of hydrogen was released from the hydride at approximately 450 K and the same hydrogen mass was consumed at 2.5 MPa hydrogenation pressure. 45 cycle tests (rehydrogenation and dehydrogenation) were carried out without any failure of the tank or its components. Operation of the tank under real conditions indicated the possibility for applications with stationary HT-PEM fuel cell systems.

A widespread rollout of alternative fuels is desirable to mitigate the issue of global warming. Hydrogen is widely considered one of the most promising solutions to reduce the environmental impact of the transport sector. This thesis work, performed in collaboration with the Norwegian University of Science and Technology NTNU, is based on the numerical study of the boil-off rate (BOR) of liquid hydrogen. The BOF represents the amount of liquid hydrogen that evaporates and that must be vented, through a pressure relief valve, in order to avoid the overpressurization of the tank. The case study considered is a cryogenic tank with a maximum capacity of 900 kg used as storage system in a liquid hydrogen refueling station. Two different insulation systems were considered: the high-vacuum multilayer (MLI) and the polyurethane foam insulation. The numerical computation was performed with OpenFoam , a computational fluid dynamics (CFD) open-source software. In order to accurately simulate the evaporation process that takes place inside the tank the Lee evaporation model and the kinetic gas evaporation model were used and critically compared. The results obtained show a great difference in terms of BOR between these two insulation systems. A layer of 15 mm of MLI makes it possible to obtain a BOR value an order of magnitude lower than that obtained with 1 meter of polyurethane foam.

As the world is moving towards a more sustainable energy perspective, construction equipment sees the requirement to change its current way of operation with fossil fuels to reduce its environmental impact. In order to pursue the electrification of construction equipment a dense power source is essential, where hydrogen powered fuel cells have the potential to be a sufficient energy source. This thesis work is carried out in order to find the least CO2 emissive pathway for hydrogen to various construction sites. This is done by collecting state of the art data for production, processing and storage technologies. With the assembled data an optimization model was developed using mixed integer linear programming. The technologies found that showed promising adaptability for construction equipment in the state of art regarding production were steam methane reforming (SMR), proton exchange membrane electrolyser (PEMEC) and alkaline electrolyser. They showed promising characteristics due to their high level of maturity and possibility for reducing the environmental impact compared to the current operation. To investigate the hydrogen pathway and its possibilities, four scenarios were created for four types of construction sites. The scenarios have different settings for distance, grid connection and share of renewables, where the operations have various energy profiles that is to be satisfied. The optimal hydrogen pathway to reduce the CO2 emissions according to the model, were either PEMEC on-site or gaseous delivery of SMR CCS produced hydrogen. The share of renewables in the energy mix showed to be an important factor to determine which of the hydrogen pathways that were chosen for the different scenarios. Moreover, in the long run PEMEC was considered to be a more sustainable solution due to SMR using natural gas as feedstock. It was therefore concluded that for a high share of renewables PEMEC was the optimal solution, where for a low share of renewables SMR CCS produced hydrogen was optimal as the energy mix would result in a more emissive operation when using PEMEC.

It is known that Sweden is categorised by being one of the regions that experience low solar radiation because it is located in the northern hemisphere that has a low potential of solar radiation during the colder seasons. The government of Sweden aim to promote a more sustainable future by applying more renewable initiative in the energy sector. One of the initiatives is by applying more renewable energy where PV panels will play a greater role in our society and in the energy sector. However, the produced energy from the PV panels is unpredictable due to changes in radiation throughout the day. One great way to tackle this issue is by combining PV panels with different energy storage system. This thesis evaluates an off-grid rowhouse in Eskilstuna Sweden where the PV panels are combined with a heat pump, thermal storage tank, including batteries and hydrogen system. The yearly electrical demand is met by utilizing PV panels, battery system for short term usage and hydrogen system for long-term usage during the colder seasons. The yearly thermal demand is met by the thermal storage tank. The thermal storage tank is charged by heat losses from the hydrogen system and thermal energy from heat pump.The calculations were simulated in Excel and MATLAB where OPTI-CE is composed with different components in the energy system. Furthermore, the off-grid household was evaluated from an economic outlook with respect to today’s market including the potential price decrease in 2030.The results indicated that the selected household is technically practicable to produce enough energy. The PV panels produces 13 560 kWh annually where the total electrical demand reaches 6 125 kWh yearly (including required electricity for the heat pump). The annual energy demand in terms of electricity and thermal heat reaches 12 500 kWh which is covered by the simulated energy system. The overproduction is stored in the batteries and hydrogen storage for later use. The back-up diesel generator does not need to operate, indicating that energy system supplies enough energy for the off-grid household. The thermal storage tank stores enough thermal energy regarding to the thermal load and stores most of the heat during the summer when there are high heat losses due to the charge of the hydrogen system. The simulated energy system has a life cycle cost reaching approximately k$318 with a total lifetime of 25 years. A similar off-grid system has the potential to reduce the life cycle cost to k$195 if the energy system is built in 2030 with a similar lifespan. The reduction occurs due to the potential price reduction for different components utilized in the energy system.

The main topic of this thesis is a design of VUT 001 airplane fuel transformation by means of fuel cells and storage batteries. A list of components available on the market was drawn up, their building in the airplane and the engineering design for mounting the electric motor into the structure. The thesis also includes the mass and centering analysis of flight performance and stability control.

L'objectif de la thèse était d'étudier la faisabilité d'un couplage thermique entre un réservoir d'hydrure métallique et une source externe de chaleur. L'évolution des propriétés de composites à base d'hydrure de magnésium (MgH2) a été étudiée en fonction du nombre de cycles d'hydruration. On observe une très bonne stabilité de la capacité massique d'absorption sur le long terme (600 cycles réalisés). Les premiers cycles sont néanmoins marqués par une évolution importante de la microstructure qui dépend de la proportion et/ou de la nature de l'additif utilisé lors de la mécano-synthèse des poudre d'hydrure. Cette évolution est associée à une augmentation de la conductivité thermique, mais également à une légère dégradation des cinétiques intrinsèques de réaction ainsi qu'à une expansion volumique des composites. Nos mesures montrent que l'amplitude des contraintes mécaniques engendrées sur les parois d'un réservoir se stabilisent après une cinquantaine de cycles. Un réservoir contenant 10 kg de MgH2, et capable de stocker 6500 Nl d'hydrogène en 35 minutes a ensuite été développé au laboratoire. L'énergie des réactions d'absorption et de désorption est échangée avec une source externe de chaleur via un fluide caloporteur. Ce système permet de représenter l'intégration thermique d'un réservoir d'hydrure dans un système de cogénération. Un modèle numérique a été développé afin de mieux appréhender le comportement de ce réservoir. Des essais de couplage entre un réservoir de taille plus modeste et une pile à combustible haute température (SOFC) développant une puissance électrique de 1 kW ont également été réalisés au Politecnico di Torino.

L'objectif de la thèse était d'étudier la faisabilité du stockage solide de l'hydrogène sous forme d'hydrure de magnésium (MgH2). Dans un premier temps la poudre de MgH2 activé a été caractérisée d'un point de vue cinétique, thermodynamique, et thermique. Les cinétiques d'absorption / désorption de l'hydrogène s'avèrent très sensibles à une exposition des poudres à l'air. La réaction d'hydruration, très exothermique, nécessite d'évacuer très rapidement la chaleur pour charger un réservoir dans un temps raisonnable. Afin d'augmenter la conductivité thermique, un procédé de mise en forme du matériau avec ajout de graphite naturel expansé (GNE) a été développé. Cette mise en forme permet d'obtenir des disques solides et usinables d'MgH2 activé de porosité réduite, présentant une densité volumique de stockage deux fois plus élevée que la poudre libre, et dont la manipulation est plus facile et sûre. L'analyse du comportement thermique et des flux gazeux a d'abord été menée avec un réservoir de faible capacité (90 Nl d'H2) mais permettant de s'adapter à des configurations expérimentales variées. Un second réservoir a été conçu pour répondre aux spécificités des composites "MgH2 + GNE". Ce réservoir permet d'absorber 1200 Nl (105 g d'H. ) en 45 minutes, avec une densité volumique système équivalente à celle d'une bouteille d'hydrogène comprimé à 480 bars. Simultanément, un modèle numérique du comportement des réservoirs de MgH2 a été développé à l'aide du logiciel Fluent®. Les simulations numériques des chargements et des déchargements concordent avec l'expérience et expliquent le comportement réactionnel du matériau
The target of this thesis was to study the feasibility of solid hydrogen storage in magnesium hydride (MgH2). At first, kinetic, thermodynamic and thermal properties of activated MgH2 powder have been investigated. Powders sorption kinetics are very sensitive to air exposure. The heat released by the very exothermic absorption reaction needs to be removed to load a tank with hydrogen in a reasonable time. In order to increase the thermal conductivity, a compression process of the material with expanded natural graphite (ENG) has been developed. Owing to that process, tough and drillable disks of MgH2 can be obtained with a reduced porosity and twice the volumetric storage capacity of the free powder bed. Handling those disks is easier and safer. Heat and mass transfer analysis has been carried out with a first small capacity tank (90 Nl), which is adapted to different experimental configurations. A second tank has been designed to fit disks of "MgH2 + ENG". This tank can absorbe 1200 Nl (105 g H. ) in 45 minutes, with a volumetric storage density equivalent to 480 bar compressed hydrogen. At the same time, a numerical modeling of MgH2 tanks has been achieved with Fluent® software. Numerical simulations of sorption process fit experiments and can be used for a better understanding of the storage material thermal and chemical behavior

Hydrogen is a potential future energy carrier, but reliable storage of the hydrogen is required for widespread use. Metal-hydrides (MH) are suitable materials for safe, stable and long-term hydrogen storage applications such as off-grid and hybrid solar systems due to the ability to store hydrogen at moderate pressure and temperature. However, poor thermal properties of MH beds coupled with the need for managing the significant amount of heat generated during the absorption and desorption reactions, is a serious barrier for fast hydrogen uptake and release unless an efficient design for the MH tank and the heat exchange system is used. Appropriate design of the tank and thermal management systems as well as a suitable choice of material can improve the performance of the MH systems and make them more suitable for commercial use. It is not usually practicable to build and test different MH tanks for large scale applications and explore the impact of different design and process parameters on the performance of the tanks. In contrast, mathematical models can be employed for examining various parameters, scenarios and used to predict the effect on the MH system without the cost of materials and manufacturing time. These models, however, must be accurate in order to reliably design large scale MH tanks and components and this accuracy can be achieved by refinement of the model’s parameters and equations based on practical systems. In turn, the accuracy of the model also needs to be validated through experimental data obtained from operating tank systems under different conditions.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Natural Sciences
Science, Environment, Engineering and Technology
Full Text

The doctoral study closes a number of knowledge gaps in hydrogen safety engineering related to the safety of hydrogen storage cylinders. The main targets of the work were achieved by applying analytical and contemporary numerical methods, including computational fluid dynamics (eFD). The models developed within the scope of the study were compared with experiments and allow for prediction of fire resistance rating (FRR) of high-pressure gas storage tanks and prediction of one of the dangerous effects from tank rupture in a fire, i.e. blast wave decay. The numerical model for prediction of the FRR of a high-pressure hydrogen storage tank in a fire was developed and compared with experiments with good agreement. The numerical pretest studies performed revealed the effect of HRR variation which significantly influenced the FRR of the hydrogen storage cylinder that were implemented into the experimental programme and were further proved in experiments. A theory for the prediction of blast wave decay from gas vessel rupture in a fire was developed and validated against experiments with stand-alone and under-vehicle (on-board) tank rupture experiments. It included a novel analytical model for the prediction of blast wave decay which accounted for effects of a real gas and effects from hydrogen combustion. Engineering tools (nomograms) for first responders and hydrogen safety engineers were developed. The engineering tools allow for prediction of hazard distances for humans and buildings from a blast. The suggestions for amendments of the Global Technical Regulation No. 13 and safety strategies were formulated.

Le développement des sources d'énergie alternatives devient très important en raison de l'effet du changement climatique et de l'épuisement des combustibles fossiles. L’hydrogène est prometteur grâce à sa ressource illimité, sa densité énergétique élevée, sa grande flexibilité technologique et sa nature respectueuse de l’environnement. Avec un potentiel élevé en matière de sécurité et de fiabilité, le stockage d'hydrogène avec des hydrures métalliques (MH) est considéré comme la meilleure méthode. Cette thèse contribue à l'étude des performances des systèmes de stockage de l’hydrogène MH embouqué, plus particulièrement l’état de charge, la modélisation dynamique et la gestion thermique la pile à combustible.Tout d'abord, des modèles sont proposés pour l'analyse dynamique des performances et le calcul de l'état de charge (SOC). Le processus d'estimation SOC en ligne est ensuite réalisé en combinant un classifieur d'états multi-joint. Le modèle dynamique du réservoir prenant en compte la conversion de masse et d'énergie est proposé à l'aide de paramètres optimisés identifiés par un algorithme d'optimisation d'essaim partiel. De plus, le comportement dynamique du système de pile à combustible intégrant la pile à combustible à membrane échangeuse de protons (PEMFC) et le réservoir de stockage d'hydrogène MH est simulé à l'aide d'un modèle mathématique défini et validé à l'aide d'une base de données provenant des véhicules réels. Une stratégie de gestion thermique avec contrôleur PID est proposée pour réduire la dégradation et prolonger la durée de vie de la PEMFC. Enfin, d’essai est conçu en laboratoire et des expériences sont menées pour valider les modèles et stratégies proposés
Nowadays, the development of alternative energy sources becoming particularly important due to the effect of climate change and fossil fuels depletion. Hydrogen holds great promise thanks to its unlimited resources, high energy density, large technological flexibility and the environmentally friendly nature. With high potential of safety, storing hydrogen with metal hydrides (MH) is considered to be the optimal on-board hydrogen storage method for the future hydrogen vehicle. This thesis therefore contributes to analyzing the performance and proprieties of embedded MH hydrogen storage systems, including the characteristic estimation, dynamic modeling and thermal management coupling with fuel cells.Firstly, statistical models are proposed for dynamic performance analysis and state of charge (SOC) calculation. The online SOC estimation process is then realized combining a multi-joint state classifier. The dynamic model of the embedded MH tank considering mass and energy conversion is proposed using optimized parameters identified through particle swarm optimization (PSO) algorithm. Moreover, the dynamic behavior of the fuel cell system integrating proton-exchange-membrane fuel cell (PEMFC) and MH hydrogen storage tank is simulated with a mathematical model set and validated using a database from the real operation vehicles. A thermal management strategy with PID controller is proposed to reduce the degradation and extend the lifespan of PEMFC. Finally, a test bench is designed in laboratory and experiments are carried out to validate the proposed models and strategies

碩士
中華大學
機械工程學系碩士班
97
A study of the hydrogen storage using metal hydride is presented. We use the energy equation to analyze the associated heat transfer problem based on assuming that thermal equilibrium has been reached between the metal hydride and hydrogen gas. The mass balance between the hydrogen gas and metal hydride is described in terms of the continuity equation. The Forchheimer-Brinkman equation is used to describe the gas flow within the porous medium . The mathematical model developed was solved using a finite volume method, FLUENT6.3 (Fluent, Inc. USA). The effect of bulk diffusion is considered for mass transfer in the solid phase. Temporal and spatial variations of temperature and concentration in hydride bed are plotted. Emphasis is given to monitor the motion of hydrogen within the bed and to the influence of the L/D ratio and porosity. It is observed that a concentration variation in the bed is the driving force for hydrogen flow in hydride beds. The gas movement is observed to be from saturated cooler peripheral region towards the unsaturated hotter core region of the bed.

碩士
國立中央大學
能源工程研究所
96
A study of the hydrogen storage and usage using LaNi5 metal hydride is presented. The metal hydride tank is considered to consist of a porous medium (hydride bed) and an expansion volume (gaseous phase). For this storage structure a mathematical model including both hydriding and dehydriding processes is developed. When metal hydrides absorb hydrogen, they release heat. Conversely, when they absorb heat, the alloys release hydrogen. Therefore we use the energy equation to analyze the associated heat transfer problem based on assuming that thermal equilibrium has been reached between the metal hydride and hydrogen gas. The mass balance between the hydrogen gas and metal hydride is described in terms of the continuous equation. The Forchheimer-Brinkman and Navier-Stokes equations are used to describe the gas flow within the porous medium and expansion volumes respectively. The mathematical model developed was solved using a finite element code, COMSOL Multiphysics 3.2 (COMSOL Inc., Sweden). Results show during the process of either absorbing or releasing hydrogen, the inside flow influenced by the fact that the temperature profile is not uniform in the tank has a major impact on the changes of the gas density. Hydride absorption or desorption both take place faster neat the tank wall because there is better heat exchange near the wall. Using the simulation model, we also study how the hydrogen reaction rates change with the parametric values. Result show changing the external cooling/heating temperature or the inlet/outlet gas pressure has profound influences on the hydriding and dehydriding speeds. In contrast, the inlet diameter and expansion height have virtually nothing to do with the hydriding and dehydriding rates.

Hydrogen has been shown to be a promising replacement for fossil fuels for use in light duty vehicles because it is a clean, renewable and plentiful resource with a high gravimetric energy density. However, in order to obtain an acceptable volumetric energy density, densification of the hydrogen is required. Adsorptive materials have been shown in the literature to increase volumetric and gravimetric storage densities. A major issue with adsorptive storage is that the adsorption process generates heat and optimal storage conditions are at temperatures below 100 K at pressures up to 50 atm. There is a need to develop heat exchanging architecture that enables adsorbents to be a viable method for hydrogen storage by managing the thermal environment of the storage tank. Based on previous modeling efforts to determine an acceptable bed module height for removal of heat via microchannel cooling plates, a thermal management system has been designed and tested capable of removing the heat of adsorption within adsorbent-filled hydrogen storage tanks. The system uses liquid nitrogen cooling to maintain tank temperatures of below 80 K at 50 atm. System studies show that the microchannel architecture offers a high cooling capacity with about a 6% displacement volume. Simulations and experiments have been conducted to evaluate the design for the cooling capacity, pressure drop, and flow distribution between and across the cooling plates, stress due to the pressurized environment, and thermal stress. Cost models have been developed to demonstrate that the system can be manufactured for a reasonable cost at high production volumes. Experimental results show that the modular system offers an acceptable cooling capacity and pressure drop with good flow distribution while adequately managing thermal stresses during operation.
Graduation date: 2013