High-density Hydrogen Storage Research Articles

Study on the impact of hydrogen storage temperature on iron-based thermochemical hydrogen storage technology

Thermochemical hydrogen storage technology based on iron-based materials has received significant attention owing to its low cost, safety features, and high volumetric hydrogen storage density. However, no consensus has been established on the optimal temperature range for hydrogen storage. This study investigated the impact of hydrogen storage temperature on hydrogen consumption capacity, hydrogen release capacity, and hydrogen storage energy consumption. The hydrogen storage temperature was optimized with the objectives of low energy consumption and high hydrogen storage density. The experiments were conducted using thermogravimetric analyzer and gram-scale packed-bed reactor setups, accompanied by thermodynamic and kinetic calculations. The research indicated that at 550 °C, the optimal hydrogen storage temperature, the lowest relative energy demand was 32.30 %, with the hydrogen consumption capacity reaching the theoretical maximum value of 4.8 %, and the hydrogen release capacity reaching 4.04 %. Furthermore, achieving the theoretical maximum value of hydrogen consumption capacity became exceedingly difficult when the hydrogen storage temperature exceeded 570 °C. Microstructural characterization and kinetic calculations revealed that this phenomenon was attributed to the formation of a dense iron layer on the particle surface, which impeded the solid-state diffusion of oxygen atoms. The formation of the intermediate phase wüstite was identified as the cause of the formation of the dense iron layer. Overall, this study provided theoretical support for iron-based thermochemical hydrogen storage processes and offered a perspective into the reaction behavior of the reduction of magnetite with hydrogen.

Optimal design and simulation investigation for high-density hydrogen storage tanks filled with rare earth-based (RE-Ca)(Ni-Co)5 optimized alloy

The slow kinetic rate due to strong thermal effect limits the practical application of metal hydride tanks in high-density hydrogen storage. In this work, we concentrate on a comprehensive experimental and numerical investigation of metal hydride beds with rare earth-based (RE-Ca)(Ni-Co)5 optimized alloy to explore faster reaction rates. Two different cylindrical tanks were manufactured to reflect de-/hydrogenation characteristics. A study on the temperature evolution in the loose powder bed was performed first, followed by five other different bed configurations: alternated powder layers with Al fiber layers, powder mixed with Al fibers, compacted discs (mixture of powder, resin and graphite), alternated compacts with Al fins and alternated Al foil-wrapped compacts with Al fins. Among them, the compacts provide good heat transfer capacity, with additional Al foils and fins for optimum thermal diffusion, reducing the reaction time by almost 50 %. Stress concentrations caused by powder accumulation can also be avoided thanks to the stable structure. Finally, the numerical model was adapted to simulate the de-/hydrogenation processes of the optimized bed and the experimental data matched well with the computational results, confirming the reliability of the model. It lays the foundation for the design and operation optimization of high-density hydrogen storage in the future.

Study on hydrogen storage properties of Ti–V–Fe–Mn alloys by modifying Ti/V ratio

The high stability of hydride phase has limited the improvement for the hydrogen storage properties of Ti–V based alloy at room temperatures. In this work, the stability of hydride was reduced by designing a low-price Ti–V–Fe–Mn alloy, and the effect of Ti/V ratio on the crystal structure and hydrogen storage properties was systematically investigated. The Ti40-xV40+xFe15Mn5 (x = 0, 2, 4, 6, 8) alloys were synthesized using arc melting, and the as-prepared alloys are all composed of single BCC phase. The lattice constant and cell volume decrease linearly with a lessening in Ti/V ratio. The reduction of cell volume makes it difficult for hydrogen atoms to diffuse, resulting in a sluggish hydrogen absorption rate. The dehydrogenation plateau in PCI curve rises and corresponding thermodynamics is optimized with a decrease in the lattice constant, and the hydrogen atoms are more readily to release, especially for Ti32V48Fe15Mn5 alloy with the dehydrogenation capacity of 1.83 wt% at 373 K. The result indicates the thermodynamic properties can be optimized by adjusting the lattice constant of Ti–V–Fe–Mn alloys, and hydrogen storage capacity is improved effectively. This study provides a reference for composition design of Ti–V–Fe–Mn alloys for high-density hydrogen storage.

Ultrafine Pt particles on hollow hierarchical porous β zeolites for selective hydrogenation of naphthalene

It is crucial to develop effective heterogeneous catalysts for the production of decalin as a high-density liquid hydrogen storage material from naphthalene hydrogenation. In this work, hollow hierarchical Pt/Hβ catalysts with ultrafine Pt particles were successfully synthesized successfully. The construction of hollow cavity optimized the metal-support interaction and reduced the resistance of mass diffusion. The ultrafine Pt species could expose more active sites for effective hydrogenation of naphthalene. The optimized Pt/Hβ-2 with hollow structure catalyst displayed the remarkable catalytic performance with the naphthalene conversion of 94.2 % and the decalin yield of 81.4 % at 220 °C, which was superior to the reaction performance of the catalysts reported in the literature under similar reaction condition. Besides, Pt/Hβ-2 presents higher turnover frequency (25.4 h−1) and reaction rate constant (9.9 × 10-3 min−1), which is because of the relatively low activation energy (30.86 kJ mol−1) for the naphthalene hydrogenation.

Single-Atom Ni Supported on TiO2 for Catalyzing Hydrogen Storage in MgH2.

As an efficient and clean energy carrier, hydrogen is expected to play a key role in future energy systems. However, hydrogen-storage technology must be safe with a high hydrogen-storage density, which is difficult to achieve. MgH2 is a promising solid-state hydrogen-storage material owing to its large hydrogen-storage capacity (7.6 wt %) and excellent reversibility, but its large-scale utilization is restricted by slow hydrogen-desorption kinetics. Although catalysts can improve the hydrogen-storage kinetics of MgH2, they reduce the hydrogen-storage capacity. Single-atom catalysts maximize the atom utilization ratio and the number of interfacial sites to boost the catalytic activity, while easy aggregation at high temperatures limits further application. Herein, we designed a single-atom Ni-loaded TiO2 catalyst with superior thermal stability and catalytic activity. The optimized 15wt%-Ni0.034@TiO2 catalyst reduced the onset dehydrogenation temperature of MgH2 to 200 °C. At 300 °C, the H2 released and absorbed 4.6 wt % within 5 min and 6.53 wt % within 10 s, respectively. The apparent activation energies of MgH2 dehydrogenation and hydrogenation were reduced to 64.35 and 35.17 kJ/mol of H2, respectively. Even after 100 cycles of hydrogenation and dehydrogenation, there was still a capacity retention rate of 97.26%. The superior catalytic effect is attributed to the highly synergistic catalytic activity of single-atom Ni, numerous oxygen vacancies, and multivalent Tix+ in the TiO2 support, in which the single-atom Ni plays the dominant role, accelerating electron transfer between Mg2+ and H- and weakening the Mg-H bonds. This work paves the way for superior hydrogen-storage materials for practical unitization and also extends the application of single-atom catalysis in high-temperature solid-state reactions.

Investigation of hydrolysis properties of MgH2 in different anionic/cationic salt solutions

MgH2 is a promising metal hydride for high-density hydrogen storage, offering advantages such as operational safety, high hydrogen yield, and cost-effectiveness in hydrolysis-based hydrogen generation. However, challenges persist in this field, including reaction interruption caused by the formation of passivating layers and sluggish kinetics. In this study, MgH2 hydrolysis experiments were conducted, utilizing various solutions including 1 M AlCl3, Al2(SO4)3, Al(NO3)3, NiCl2, NiSO4, Ni(NO3)2, FeCl3, Fe2(SO4)3, and Fe(NO3)3 at different temperatures. The resulting hydrolysis products were analyzed using X-ray diffraction and scanning electron microscopy to examine their phases and morphology. Through comprehensive analysis of the hydrolysis mechanism and kinetics, chloride ion solutions were identified as highly efficient, demonstrating excellent rates and yields. Notably, AlCl3, NiCl2, and FeCl3 outperformed other solutions, exhibiting kinetic performance with hydrolysis activation energies of 17.3 ± 1.7, 24.2 ± 1.3, and 14.7 ± 1.7 kJ/mol, respectively. Furthermore, we extended our investigation to compare the hydrolysis effects of different cations, incorporating MnCl2, CoCl2, and CuCl2. Mechanistic analysis pinpointed Al3+ and Fe3+ as catalysts with exceptional hydrolysis performance and remarkable kinetic properties. The aforementioned remarkable MgH2 hydrolysis properties are of significant interest for investigating the corresponding Mg-based alloy hydrides, which are worthwhile to consider.

A computational analysis of cryogenic hydrogen release under various conditions

Cryogenic liquid hydrogen offers a promising solution for achieving high-density hydrogen storage and efficient on-site distribution. However, the potential hazards associated with hydrogen leakages necessitate thorough investigations. This research aims to model cryogenic hydrogen release from circular and high aspect ratio (HAR) nozzles tested by Sandia. The test conditions cover reservoir pressures and temperatures corresponding to cryogenic hydrogen storage. The study conducts computational simulations using OpenFOAM to examine hydrogen concentration, temperature fields, mass fraction, and temperature distributions, achieving good agreement with the experimental data. To further explore, the study of velocity variations shows a consistent decay rate with room-temperature jets. The numerical data reveals comparable inverse centreline hydrogen mass fractions (0.254 for HAR and 0.26 for circular) and normalised centreline temperature decay rates (0.031 for HAR and 0.032 for circular). The present computational model holds the potential for further analysis of cryogenic hydrogen in large-scale facilities.

Design and optimization of high-density cryogenic supercritical hydrogen storage systems integrating with dual mixed refrigerant cycles

To address the low density of high-pressure gaseous hydrogen and evaporation issues associated with liquid hydrogen storage, cryogenic supercritical hydrogen storage method is presented in this paper. Based on a dual parallel mixed refrigerant cycle (DPMR) and a dual cascade mixed refrigerant cycle (DCMR), the density of supercritical hydrogen product is 70.74 kg/m3, closely approaching liquid hydrogen. The processes are simulated in Aspen HYSYS, optimized by genetic algorithm for lower specific energy consumption (SEC). Thermodynamic analysis is conducted to compare with hydrogen liquefaction processes, demonstrating the feasibility and superiority of proposed process. The results show that the DPMR process has an SEC of 6.422 kWh/kgH2 and exergy efficiency of 52.66%, while DCMR is 6.872 kWh/kgH2 and 49.24%. Additionally, the inclusion of ortho-para convertors in DPMR process is investigated to further analyze the impact of heat release for ortho-para conversion. Furthermore, a techno-economic analysis is conducted on three processes, validating the economic feasibility. The study indicates that cryogenic supercritical hydrogen storage system is of great significance to the development of high-density hydrogen storage technology. The DPMR and DCMR presented in this paper can significantly improve the energy efficiency and provide valuable information for the design of high-density hydrogen storage system.

Preliminary analysis of refilling cold-adsorbed hydrogen tanks

The effective storage of hydrogen is a critical challenge that needs to be overcome for it to become a widely used and clean energy source. Various methods exist for storing hydrogen, including compression at high pressures, liquefaction through extreme cooling (i.e. -253 °C), and storage with chemical compounds. Each method has its own advantages and disadvantages. MAST3RBoost (Maturing the Production Standards of Ultraporous Structures for High Density Hydrogen Storage Bank Operating on Swinging Temperatures and Low Compression) is a European funded Project aiming to establish a reliable benchmark for cold-adsorbed H2 storage (CAH2) at low compression levels (100 bar or below). This is achieved through the development of advanced ultraporous materials suitable for mobility applications, such as hydrogen-powered vehicles used in road, railway, air, and water transportation. The MAST3RBoost Project utilizes cutting-edge materials, including Activated Carbons (ACs) and high-density MOFs (Metal-organic Frameworks), which are enhanced by Machine Learning techniques. By harnessing these materials, the project seeks to create a groundbreaking path towards meeting industry goals. The project aims to develop the world’s first adsorption-based demonstrator at a significant kg-scale. To support the design of the storage tank, the project employs Computational Fluid Dynamics (CFD) software, which allows for numerical investigations. In this paper, a preliminary analysis of the tank refilling process is presented, with a focus on the impact of the effect of the tank and hydrogen temperatures on quantity of hydrogen adsorbed.

Ni-based catalyst assisted by MnO to boost the hydrogen storage performance of magnesium hydride

Magnesium hydride (MgH2) stands out as a promising solid-state material for high-density hydrogen storage, offering enormous potential for applications in hydrogen transportation and storage. However, the stable thermodynamics and sluggish kinetics of dehydrogenation/hydrogenation of MgH2 impede its practical use in on-board hydrogen storage. In this study, the nanocomposite of nickel/manganese oxide (Ni/MnO) was successfully synthesized through the hydrogenation of nickel-manganese two-dimensional layered double hydroxide (NiMn-LDH) and then introduced into MgH2 by ball milling to form BM-MgH2-Ni/MnO composite. Notably, BM-MgH2-Ni/MnO-10 displayed excellent hydrogen absorption/dehydrogenation properties. For example, its onset hydrogen release temperature was remarkably reduced to 175.6 °C, 84 °C lower than that of BM-MgH2. At a temperature of 250 °C, it could desorb about 6.2 wt% of H2 within 60 min. The fully dehydrogenated product could absorb 5.5 wt% of H2 within 10 min at 150 °C. Moreover, BM-MgH2-Ni/MnO-10 exhibited excellent cycling performance. Throughout the cycling process, the in-situ formation of Mg2Ni/Mg2NiH4 and metal Mn was detected, leading to a synergistic effect that significantly enhanced the hydrogen storage capability of MgH2. This study presents innovative concepts for designing active catalysts to enhance the kinetics of de-/hydrogenation reactions of MgH2.

Facile dehydrogenation of MgH2 enabled by γ-graphyne based single-atom catalyst

Solid-state hydrogen storage is a promising roadmap for the safe and efficient utilization of hydrogen energy due to its moderate operating environment and high hydrogen storage density. However, as a representative solid-state hydrogen storage material, magnesium hydride (MgH2) is significantly limited in the commercial application due to its sluggish kinetics in the dehydrogenation process. Single-atom catalysts are a promising solution to this dilemma. However, the promising graphene-based single-atom catalysts are not yet sufficient to meet the dehydrogenation needs in engineering. To further address this dilemma, we designed a novel γ-graphyne based single-atom catalysts including eight 3d transition metals for promoting the dehydrogenation process of MgH2. Through using spin-polarized density functional theory calculations, we found that the energy barrier for MgH2 dehydrogenation has been significantly reduced even to 0.70 eV, which is far lower than the current graphene-based single-atom catalyst. In detail, the migration trajectory of hydrogen atom in the dehydrogenation process has been observed and confirmed using the ab initio molecular dynamics simulations. To investigate the intrinsic origin for its high catalytic activity of single-atom catalyst, we analyze the HMg bond activation mechanism through the electron localization function, charge density difference and crystal orbital Hamiltonian population. Finally, we found the relationship between energy barrier with electronic structure of single-atom catalyst, such as electrostatic potential and system electronegativity. This work can not only provide new ideas for the optimize of dehydrogenation catalyst, but also lay a theoretical foundation for the design of novel energy storage material.

Optimization design of solid-state hydrogen storage device for fuel cell forklift

Solid-state hydrogen storage device using metal hydride have enormous advantages for fuel cell forklifts. In addition to high volume hydrogen storage density, the solid-state hydrogen storage device can also be used as a counterweight for the forklift. At the same time, the solid-state storage device has low hydrogen storage pressure and safety, and the fuel (H2) refueling is convenient and low-cost. In this paper, a two-dimensional heat and mass transfer numerical model has been developed to predicting the performance of the metal hydride tank filled with Ti0.9Zr0.1Cr0.35Mn1.4V0.2Fe0.05 alloy. The validity of this numerical model was tested by comparison with the experimental data of the metal hydride hydrogen storage tank with a hydrogen capacity of 1 kg, achieving a good agreement between all the data. And a solid-state hydrogen storage device with an effective hydrogen capacity of 1.5 kg is optimally designed for 3.5 T fuel cell forklift. The completion rate of hydrogen refueling in the solid-state hydrogen storage device will reach 97.6 % within 30 min, and continuously discharging over 1.5 kg H2 under flow rates of 150 SL/min and 250 SL/min. The optimized solid-state hydrogen storage device was integrated in a power module for 3.5 T fuel cell forklift which allows uninterrupted operation for at least 6 h 8 min under rated operation.

Optimizing reactor structure to increase MgH2 dispersion and improve hydrolysis performance

Hydrogen has attracted wide attention due to its high calorific value, good combustion performance, non-toxic, and green characteristics. MgH2 has obvious advantages in hydrogen storage due to its high hydrogen storage density, mild hydrolysis conditions, rich raw materials, etc. However, poor hydrolysis kinetics limits its application in hydrogen storage. Different from research on MgH2 material modification, the physical method was employed to increase the MgH2 dispersion and improve the hydrolysis kinetics. Furthermore, hydrolysis reactors, including tubular, flaky and finned units, were designed and optimized. The results indicate that enhancing the dispersion of magnesium hydride can significantly improve the hydrolysis kinetics. The use of hydrolysis reactors with highly dispersed MgH2 can effectively enhance the controllability and continuity during the hydrolysis process. This can be attributed to the reduction in the surface coating of unreacted magnesium hydride by the generated magnesium hydroxide, as well as the improved transfer performance between the fresh hydrolysis solution and solid magnesium hydride. The findings of this study can further expand the range of reactor types for magnesium hydride hydrolysis and provide new insights for designing controllable and continuous hydrolysis reactors.

Development of Fuel Cell System Using Metal Hydride and Hydrogen Peroxide in Low-Oxygen Environments

Hydrogen energy is attracting attention as a promising power system due to high energy storage density and environmentally friendly features. For these reasons, fuel cell system using hydrogen energy in unmanned underwater vehicles have been studied. However, in low-oxygen environment, fuel cell system requires an oxygen storage as well as a hydrogen storage. In this study, a fuel cell system using a metal hydride and hydrogen peroxide was designed. The metal hydride can charge and discharge hydrogen at a lower pressure than a high-pressure hydrogen tank and has a high hydrogen storage density. In this system, AB2 type metal hydride is used to store hydrogen. Hydrogen desorption reaction of the metal hydride is an endothermic reaction, and heat supply is required to maintain the temperature of the metal hydride in order to stably supply hydrogen. Therefore, in this system, hydrogen peroxide was used as an oxygen source. Hydrogen peroxide reacts with a metal catalyst to generate oxygen and water. The decomposition reaction of hydrogen peroxide is an exothermic reaction and can supply heat required for the metal hydride. In this system, hydrogen peroxide is decomposed into water and oxygen through a catalytic reaction, and the generated heat is supplied to the metal hydride. Finally, hydrogen and oxygen are supplied to the PEMFC stack to generate power. For system design, in this study, PCT characteristics of AB2 type metal hydride, thermal management method, and hydrogen peroxide decomposition catalyst were studied, and an operation strategy for non-humidified PEMFC operation was proposed. This system generated a power output of about 290 W for 97 hours, and the hydrogen utilization rate of the fuel cell was confirmed to be 92.3%.

Design and optimization of a high-density cryogenic supercritical hydrogen storage system based on helium expansion cycle

Cryogenic supercritical hydrogen storage technology is a high-density physical hydrogen storage method, which is a highly promising hydrogen storage approach. However, existing research has mainly focused on the development of storage devices for cryogenic supercritical hydrogen, with limited research on the cooling process of supercritical hydrogen. Therefore, a novel cooling process for cryogenic supercritical hydrogen production based on helium expansion cycle with liquid nitrogen (LN2) pre-cooling is proposed in this paper. In this process, after being compressed and cooled in multiple stages, the feed hydrogen is pre-cooled by LN2. Then, cryogenic supercritical hydrogen (10 MPa, −235.15 °C, 63.36 g/L) is obtained by helium multi-stage expansion refrigeration. The process is simulated by Aspen HYSYS and optimized by genetic algorithm (GA) to obtain lower specific energy consumption (SEC). Thermodynamic analyses are conducted to evaluate the process. And compared with the conventional hydrogen liquefaction process, the results show that the proposed process is reasonable and superior. The SEC0, figure of merit (FOM), and the total exergy loss of the system are 5.432 kWh/kgH2, 43.88%, and 289.69 kW respectively. This study indicates that the proposed process has significant implications for the hydrogen industry and provides valuable information for cryogenic supercritical hydrogen storage systems.

Review of the Hydrogen Permeation Test of the Polymer Liner Material of Type IV On-Board Hydrogen Storage Cylinders.

Type IV hydrogen storage cylinders comprise a polymer liner and offer advantages such as lightweight construction, high hydrogen storage density, and good fatigue performance. However, they are also characterized by higher hydrogen permeability. Consequently, it is crucial for the polymer liner material to exhibit excellent resistance to hydrogen permeation. International organizations have established relevant standards mandating hydrogen permeation tests for the liner material of type IV on-board hydrogen storage cylinders. This paper provides a comprehensive review of existing research on hydrogen permeability and the hydrogen permeation test methods for the polymer liner material of type IV on-board hydrogen storage cylinders. By delving into the hydrogen permeation mechanism, a better understanding can be gained, offering valuable references for subsequent researchers in this field. This paper starts by thoroughly discussing the hydrogen permeation mechanism of the liner material. It then proceeds to compare and analyze the hydrogen permeation test methods specified by various standards. These comparisons encompass sample preparation, sample pretreatment, test device, test temperature and pressure, and qualification indicators. Then, this study offers recommendations aimed at enhancing the hydrogen permeation test method for the liner material. Additionally, the influence of test temperature, test pressure, and polymer material properties on the hydrogen permeability of the liner material is discussed. Finally, the influences of the test temperature, test pressure, and polymer material properties on the hydrogen permeability of the liner material are discussed. Future research direction on the hydrogen permeability and hydrogen permeation test method of the liner material of the type IV hydrogen storage cylinder has been prospected.

Enhancing the efficiency of sodium borohydride hydrolysis with a novel CoB-Triton catalyst

Hydrogen is increasingly recognized as the most significant alternative solution for reducing global greenhouse gas emissions in maritime transportation. In particular, solid-state sodium borohydride (NaBH4) with its high hydrogen storage density stands out as the preferred choice due to its higher efficiency and improved safety. In present study, a surfactant-stabilized CoB catalyst was used in order to improve the hydrolysis performance of NaBH4. For this reason, the effects of Triton X-100, used as a surfactant in different quantities, on the hydrogen generation rate were tested. To characterize the prepared samples, several analytical techniques were employed, including field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), Mastersizer analysis, X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. According to findings, 40.2% faster hydrogen generation rate is obtained with CoB-Triton 150 contrary to CoB catalyst. The optimum concentrations are found as 5% NaOH and 5% NaBH4 and activation energy is 44.21 kj/mol for developed CoB-Triton 150 catalyst. Last of all, fuel cell performances show that the produced hydrogen from hydrolysis reaction through CoB-Triton 150 catalyst has nearly same fuel cell performance compared to industrial pure hydrogen. Consequently, Triton X-100 is a good candidate to improve the hydrolysis performance of NaBH4 and needs further research.

Advancements in Metal Hydride Materials for Hydrogen Storage

Hydrogen energy is attracting the attention of scientists because of its high energy density and low environmental pollution in the world trend of clean energy use. In addition, the basis for the use of hydrogen energy is its secure, cost-effective, and efficient storage. After decades of devotions by experts, many high-performance hydrogen storage materials have been created. The poor hydrogen storage capacity, challenging hydrogen storage circumstances, slow hydrogen storage speed, and potential safety concerns remain, nonetheless, with the present hydrogen storage materials. Metal hydride materials, which have a high hydrogen storage density and safe reactions, have so steadily been a research focus in recent years. In this paper, magnesium-based materials and titanium-based materials are selected as the representatives of metal hydride materials, and their hydrogen storage mechanisms, common modification methods, and the advanced research progress of these methods are reviewed. Through the analysis of data, the hydrogen storage properties and the respective characteristics of each modified hydrogen storage material are rigorously presented. The key technical limitations and possible improvement directions of these materials are summarized, and the future application prospects and development trends of hydrogen storage materials are predicted at the end.

Modeling of cryogenic compressed hydrogen jet flames

Hydrogen will likely be stored and transported at high densities to have sufficient hydrogen on-site for efficient distribution. Cryogenic compressed hydrogen (CcH2) is a high-density hydrogen storage method combining cryogenic temperatures and high pressures. Hydrogen releases from such high-density sources will result in high-momentum jets and jet flames if the jets ignite. This study modelled CcH2 jet flames for stagnation pressures of 2∼5 bar and stagnation temperatures of 55∼150 K. The numerical models were validated by experimental data from the literature. The results show that the flame length increases with increasing pressure but decreases with increasing temperature. The CcH2 jet flames are longer than their room-temperature counterparts with the same mass flow rate. Then, the CcH2 jet flame lengths were correlated with the mass flow rate and stagnation temperature. Correlations were also developed for predicting trajectory temperatures and the radial temperature distributions in the CcH2 jet flames. The present study provides a scientific basis for developing cryogenic hydrogen safety codes and standards and quantitative risk assessment models.

Interface and body engineering via aluminum hydride enabling Ti-V-Cr-Mn alloy with enhanced hydrogen storage performance

The theoretical hydrogen storage capacity of V-based solid solution materials can reach 3.8 wt%, but the hydrogen in VH hydride is difficult to release at ambient temperature and pressure, so addressing the issue of hydrogen release under mild conditions is essential. While AlH3 has high weight hydrogen storage density (10.1 wt%) and relatively mild hydrogen desorption temperature (≤150 °C). Therefore, using V-based solid solution as the main body, two kinds of hydrogen storage materials are synthesized into a new composite, which can obviously display enhanced hydrogen storage performance. In this work, the structural stability, kinetic and thermodynamic properties of TiV1.1Cr0.3Mn0.6 + x AlH3 (x = 0, 1, 3, 5, wt.%) composites are studied by means of density functional theory (DFT) calculation and experiment. The results show that the AlH3-doped composites have Al phase existed in the material via the way of embedding, which improves the hydrogen storage performance and activation property of V-base solid solution. With increasing AlH3 content, the activation energies (Ea) gradually decrease. The corresponding relationship between the theoreticalcalculation and the experimental results can provide reference for the subsequent screening of appropriate hydrogen storage materials with application prospect.