Engineering Commons^™

Improved Hydrogen Storage Properties Of Mgh2 Doped With Chlorides Of Transition Metals Hf And Fe, M Ismail Ismail, Yue Zhao, Xuebin Yu, S X. Dou

Shi Xue Dou

The effects of HfCl4 and FeCl3 addition on the de/rehydrogenation properties of MgH2 were investigated. Both HfCl4 and FeCl3-doped MgH2 samples started to released hydrogen at about 270 °C, a decreased of about 70 °C and about 140 °C compared to as-milled and as-received MgH2, respectively. In terms of the desorption kinetics, the HfCl4-doped MgH2 sample showed significant improvement, with 6.0 wt.% hydrogen released within 10 min at 300 °C, while the FeCl3-doped MgH2 and undoped MgH2 samples released 3.5 and 0.2 wt.% hydrogen, respectively, under the same conditions. In terms of the absorption kinetics, 5.5 wt.% hydrogen was charged …

Computational Study Of Sodium Magnesium Hydride For Hydrogen Storage Applications, Fernando Antonio Soto Valle

Doctoral Dissertations

Hydrogen offers considerable potential benefits as an energy carrier. However, safe and convenient storage of hydrogen is one of the biggest challenges to be resolved in the near future. Sodium magnesium hydride (NaMgH 3) has attracted attention as a hydrogen storage material due to its light weight and high volumetric hydrogen density of 88 kg/m3. Despite the advantages, hydrogen release in this material occurs at approximately 670 K, which is well above the operable range for on-board hydrogen storage applications. In this regard, hydrogen release may be facilitated by substitution doping of transition-metals. This dissertation describes first-principles computational methods that …

An Analysis Of Fuel Cell Vehicle Models By Major Automakers, Florida Solar Energy Center, Nan Qin

FSEC Energy Research Center®

Fuel cell electric vehicles (FCEVs) use hydrogen as fuel and exhaust only water. They provide driving ranges and fueling times comparable to gasoline vehicles. Despite the advantages, FCEVs have been in and out of spot light of the auto industry for the past several decades. The information on the development of fuel cell vehicles by major automakers is disparate. This report systematically examined the technical developments of FCEVs since the introduction of the first lab-based fuel cell vehicle in 1966. It included an overview of 117 FCEV models from 31 automakers. It should help the stakeholders to gain an insight …

Reductive Depolymerization Of Kraft Lignin For Chemicals And Fuels Using Formic Acid As A In-Situ Hydrogen Source, Shanhua Huang

Electronic Thesis and Dissertation Repository

In this thesis work, formic acid (FA) proved to be an effective in-situ hydrogen donor for the reductive de-polymerization of kraft lignin (KL). At the optimum conditions without catalysts, i.e., 300 ^oC, 1 h, 18.6 wt.% substrate concentration, 50/50 (v/v) water-ethanol medium at a FA-to-lignin mass ratio of 0.7, KL (M_w ~10,000 g/mol) was effectively de-polymerized, producing de-polymerized lignin (DL, M_w 1, 270 g/mol) at a yield of ~90 wt.% and wt.% yield of solid residue (SR). The effects of heterogeneous catalysts on KL reductive de-polymerization in 50/50 (v/v) water-ethanol medium were also investigated. At all conditions, …

In Situ Infrared Study Of No Reduction Over Pd/Al2o3 And Ag-Pd/Al2o3 Catalysts Under H2 Rich And Lean-Burn Conditions, Duane Miller, Steven Chuang

Steven S.C. Chuang

Catalytic reduction of NO under H2-rich and lean-burn conditions over Pd/Al2O3 and Ag-Pd/Al2O3 has been studied by temperature programmed reaction (TPR) coupled with in situ infrared (IR) and mass spectrometry (MS) techniques. Under H2-rich conditions, Pd/Al2O3 produces, Pd-NCO, Pd+-NO, Pd0-NO, and adsorbed nitrate at temperatures below 398 K. N2 and adsorbed NH3 are produced at temperatures above 400 K. Addition of Ag to Pd/Al2O3 suppresses the Pd+-NO formation and lowers the formation temperature of NH3 species to 373 K. Under lean-burn conditions, Pd/Al2O3 produces Pd-NCO, Pd+-NO, Pd0-NO, and adsorbed nitrate at temperatures below 373 K, while the addition of Ag …

Solar And Visible Light Driven Photocatalysis For Sacrificial Hydrogen Generation And Water Detoxification With Chemically Modified Ti02, Pankaj Chowdhury

PC

Photocatalysis is a recognized approach where light energy is employed to excite the semiconductor material producing electron/hole pair which eventually involves in the detoxification of pollutants and/or water splitting producing hydrogen. Existing photocatalysts suffer from poor activity or no activity in visible light irradiation which restricts them from solar light utilization. This work is focused on two key applications of photocatalysis (i) sacrificial hydrogen generation, and (ii) phenol degradation in visible and/or solar light. Platinum was loaded on TiO2 photocatalyst by solar photo-deposition method. Eosin Y dye was used as a sensitizer for sensitization of platinum loaded TiO2 photocatalyst. The …

Design And Analysis Of Hydrogen Powered Actuator Integrating Metal Hydride Storage System, Md Mainul Hossain Bhuiya

UNLV Theses, Dissertations, Professional Papers, and Capstones

The multi-fold purposes of this dissertation consists of construction, simulation and validation of a model describing hydrogen sorption kinetics in metal hydride. The project involves a comprehensive review of engineering applications involving metal hydrides and furthermore, design and investigation of a thermo-kinetically driven actuation system integrating metal hydrides for compact and soft robotic actuation. This will also shed some light on the feasibility of designing a damping system integrating metal hydride. Firstly, a mathematical model along with comprehensive simulation strategy of hydrogen absorption and desorption processes in porous metal hydride compacts was developed. A two dimensional axisymmetric model was built …

Hydrogen Fueling Stations Infrastructure, Florida Solar Energy Center, Nan Qin

FSEC Energy Research Center®

Fuel Cell Electric Vehicles (FCEVs) can provide customers with the benefits of low to zero greenhouse gas emissions, high performance, and comfort without compromising range and refill time. With three major automakers (Honda, Hyundai, and Toyota) planning to introduce consumer FCEVs by the end of 2015, FCEVs will play an increasingly important role in the electric vehicle arena. Building hydrogen fueling infrastructure has been identified as a major obstacle in FCEV commercialization. This report is part of an ongoing effort within an Electric Vehicle Transportation Center (EVTC) project: "Fuel Cell Vehicle Technologies, Infrastructure and Requirements." This report is based on …

Hierarchical Porous Li 2 Mg(Nh)2@C Nanowires With Long Cycle Life Towards Stable Hydrogen Storage, Guanglin Xia, Yingbin Tan, Dan Li, Zaiping Guo, Hua-Kun Liu, Zongwen Liu, Xuebin Yu

Australian Institute for Innovative Materials - Papers

The hierarchical porous Li₂Mg(NH)₂@C nanowires full of micropores, mesopores, and macropores are successfully fabricated via a single-nozzle electrospinning technique combined with in-situ reaction between the precursors, i.e., MgCl₂ and LiN₃, under physical restriction upon thermal annealing. The explosive decomposition of LiN₃ well dispersed in the electrospun nanowires during carbothermal treatment induces a highly porous structure, which provides a favourable way for H₂ delivering in and out of Li₂Mg(NH)₂ nanoparticles simultaneously realized by the space-confinement of the porous carbon coating. As a result, the thus-fabricated Li₂Mg(NH)_{2 …}

Effects Of Tungsten On The Hydrogen Embrittlement Behaviour Of Microalloyed Steels, Jingwei Zhao, Zhengyi Jiang, Chong Soo Lee

Faculty of Engineering and Information Sciences - Papers: Part A

The effects of tungsten (W) additions (0, 0.1, 0.5 and 1 wt.%) on the hydrogen embrittlement behaviour of microalloyed steels were systematically investigated by means of slow strain rate tests on circumferentially notched cylindrical specimens, and the mechanism of hydrogen-induced embrittlement was discussed. W addition is found to increase the activation energy of hydrogen desorption. Microstructural features affect the hydrogen embrittlement behaviour and fracture modes of microalloyed steels. It is suggested that the hydrogen-induced embrittlement in the studied microalloyed steels with different W additions is caused by the combined effects of decohesion and internal pressure in the presence of hydrogen.

Computational Fluid Dynamics Simulation Of United Launch Alliance Delta Iv Hydrogen Plume Mitigation Strategies, Stephen Guimond

Electronic Theses and Dissertations

During the launch sequence of the United Launch Alliance Delta IV launch vehicle, large amounts of pure hydrogen are introduced into the launch table and ignited by Radial-Outward-Firing-Igniters (ROFIs). This ignition results in a significant flame, or plume, that rises upwards out of the launch table due to buoyancy. The presence of the plume causes increased and unwanted heat loads on the surface of the vehicle. A proposed solution is to add a series of fans and structures to the existing launch table configuration that are designed to inject ambient air in the immediate vicinity of the launch vehicle's nozzles …

Computational Design And Characterization Of Silicene Nanostructures For Electrical And Thermal Transport Applications, Tim H. Osborn

Browse all Theses and Dissertations

Novel silicene-based nanomaterials are designed and characterized by first principle computer simulations to assess the effects of adsorptions and defects on stability, electronic, and thermal properties. To explore quantum thermal transport in nanostructures a general purpose code based on Green's function formalism is developed.

Specifically, we explore the energetics, temperature dependent dynamics, phonon frequencies, and electronic structure associated with lithium chemisorption on silicene. Our results predict the stability of completely lithiated silicene sheets (silicel) in which lithium atoms adsorb on the atom-down sites on both sides of the silicene sheet. Upon complete lithiation, the band structure of silicene is transformed …

Role Of Microstructure In Susceptibility To Hydrogen Embrittlement Of X70 Microalloyed Steel, Daniel Hejazi, Ahmed Saleh, Ayesha Haq, Druce Dunne, Andrzej Calka, Azdiar A. Gazder, Elena V. Pereloma

Faculty of Engineering and Information Sciences - Papers: Part A

The effect of phases and steel processing on hydrogen uptake (diffusible and residual), surface and internal damage were evaluated using optical and scanning electron microscopy. The results have shown the fastest formation of blisters in ferrite-pearlite microstructure of strip, followed by equaixed ferrite-pearlite microstructure in normalised condition, then by ferrite-bainite microstructure. No blistering was observed in heat affected zone samples for up to 24 hrs charging. Analysis of hydrogen-induced cracking using electron back scattering diffraction has revealed that crack propagation has predominantly intragranular character without a clear preference on {001}, {110}, {112} and {123} planes and is independent of the …

Effects Of Hydrogen On The Critical Conditions For Dynamic Recrystallization Of Titanium Alloy During Hot Deformation, Jingwei Zhao, Hua Ding, Zhengyi Jiang, Dongbin Wei, Kezhi Linghu

Faculty of Engineering and Information Sciences - Papers: Part A

Hot deformation tests were performed to study the flow behavior and microstructural evolution of a Ti600 titanium alloy with different hydrogen contents. The effects of hydrogen on the critical conditions for the initiation of dynamic recrystallization (DRX) were investigated. The DRX kinetics models of hydrogenated Ti600 alloy were developed, and the DRX volume fractions were quantified under different deformation conditions. The results indicate that the addition of proper hydrogen (no greater than 0.3 pct) benefits the decrease of both the critical stress and critical strain for the initiation of DRX. The critical stress and critical strain are dependent linearly on …