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Hydrogen, Volume 3, Issue 3 (September 2022) – 6 articles

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18 pages, 751 KiB

Open AccessArticle

Investigation of the Hydrogen Absorption by the LaNi₅ and LaNi_4.75Pb_0.25 Alloys Using a Statistical Physics Model

by Michał Żurek and Wojciech Zając

Hydrogen 2022, 3(3), 361-378; https://doi.org/10.3390/hydrogen3030022 - 15 Sep 2022

Cited by 4 | Viewed by 2005

Abstract

A theoretical model was selected among three potentially applicable models and then used to analyze the absorption isotherms of the hydrogen storage alloys LaNi₅ and LaNi_4.75Pb_0.25 at three different temperatures (T = 303 K, 313 K, 323 K). The theoretical expressions of the model were based on the statistical physics formalism and simplifying hypotheses. The model selected was the one with the highest correlation with the experimental data. The model had six adjustable parameters: the number of hydrogen atoms per site

n_{α}

n_{β}

, the receptor site densities

N_{α}

N_{β}

and the energy parameters

P_{α}

P_{β}

. The fitted parameters obtained for the Pb-doped and nondoped alloys were compared and discussed in relationship to the absorption isotherms. Finally, the fitted parameters or the model were further applied to calculate thermodynamic functions, such as entropy, Gibbs free energy and internal energy, which govern the absorption mechanism. Full article

(This article belongs to the Topic Metal Hydrides: Fundamentals and Applications)

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13 pages, 5195 KiB

Open AccessArticle

Spontaneous Ignition of Cryo-Compressed Hydrogen in a T-Shaped Channel System

by Donatella Cirrone, Dmitriy Makarov and Vladimir Molkov

Hydrogen 2022, 3(3), 348-360; https://doi.org/10.3390/hydrogen3030021 - 20 Aug 2022

Cited by 2 | Viewed by 2424

Abstract

Sudden releases of pressurised hydrogen may spontaneously ignite by the so-called “diffusion ignition” mechanism. Several experimental and numerical studies have been performed on spontaneous ignition for compressed hydrogen at ambient temperature. However, there is no knowledge of the phenomenon for compressed hydrogen at cryogenic temperatures. The study aims to close this knowledge gap by performing numerical experiments using a computational fluid dynamics model, validated previously against experiments at atmospheric temperatures, to assess the effect of temperature decrease from ambient 300 K to cryogenic 80 K. The ignition dynamics is analysed for a T-shaped channel system. The cryo-compressed hydrogen is initially separated from the air in the T-shaped channel system by a burst disk (diaphragm). The inertia of the burst disk is accounted for in the simulations. The numerical experiments were carried out to determine the hydrogen storage pressure limit leading to spontaneous ignition in the configuration under investigation. It is found that the pressure limit for spontaneous ignition of the cryo-compressed hydrogen at temperature 80 K is 9.4 MPa. This is more than 3 times larger than pressure limit for spontaneous ignition of 2.9 MPa in the same setup at ambient temperature of 300 K. Full article

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15 pages, 4432 KiB

Open AccessArticle

Decomposition of Saccharides and Alcohols in Solution Plasma for Hydrogen Production

by Eiji Minami, Takaki Miyamoto and Haruo Kawamoto

Hydrogen 2022, 3(3), 333-347; https://doi.org/10.3390/hydrogen3030020 - 18 Aug 2022

Cited by 3 | Viewed by 1963

Abstract

Solution plasma or in-liquid plasma, which is generated by gas-phase discharge within bubbles in a solution, is an exciting reaction field for biomass conversion. However, it is not fully elucidated how the solution plasma works to degrade biomass or how biomass is degraded in it. In this study, various saccharides and alcohols, mainly sucrose, were treated in solution plasma using a high-voltage pulse power supply to study the degradation mechanisms. Hydrolysis and gasification were observed in the solution-plasma treatment of sucrose. The former was mainly influenced by the water temperature, and the latter was mainly influenced by the discharge power. Therefore, it was inferred that hydrolysis occurred in the hot-compressed water region around the plasma, and gasification occurred at the interface between the plasma and water. Gasification of saccharides and alcohols produced H₂-rich gases, but gasification was faster for high-volatility alcohols and slower for non-volatile saccharides. The formation of H₂-rich gas can be attributed to H₂ formation by the water–gas shift reaction of CO and direct H₂ formation from water, in addition to H₂ from the sample. Full article

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21 pages, 4708 KiB

Open AccessArticle

Hybrid Renewable Hydrogen Energy Solution for Remote Cold-Climate Open-Pit Mines

by Hosein Kalantari and Seyed Ali Ghoreishi-Madiseh

Hydrogen 2022, 3(3), 312-332; https://doi.org/10.3390/hydrogen3030019 - 12 Aug 2022

Cited by 1 | Viewed by 2506

Abstract

Contemporary off-grid mining operations rely on diesel fuel for the provision of their total energy including electricity, heat, and haulage. Given the high cost of diesel and its imposed greenhouse gas emissions, mining companies are looking for more affordable and cleaner sources of energy for their operations. Although renewable energy systems, such as solar photovoltaic and wind provide efficient solutions to address this challenge, full decarbonization has shown to be very challenging, mainly due to the high cost of battery storage along with the inability to meet total site energy demand. Integrating hydrogen and thermal storage with battery banks can facilitate a full transitioning off diesel. In this sense, the present study intends to offer an innovative decarbonized solution by integrating wind turbines with a multi-storage system (battery, hydrogen, and thermal storage) to supply the total energy (electricity, heat, and haulage) for remote open-pit mines. Among the different proposed fully decarbonized configurations in this study, it is shown that a renewable system with a hydrogen-powered fleet and hybridized battery/hydrogen storage configuration can present the most economically viable case for open-pit mines with a considerably less life-of-mine cost. Full article

(This article belongs to the Special Issue Feature Papers in Hydrogen)

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9 pages, 2768 KiB

Open AccessArticle

Methods to Improve the First Hydrogenation of the Vanadium-Rich BCC Alloy Ti₁₆V₆₀Cr₂₄

by Francia Ravalison, Eugen Rabkin and Jacques Huot

Hydrogen 2022, 3(3), 303-311; https://doi.org/10.3390/hydrogen3030018 - 22 Jul 2022

Cited by 3 | Viewed by 2248

Abstract

In this paper we report the effect of three different preparation methods on the first hydrogenation of the vanadium-rich BCC alloy Ti₁₆V₆₀Cr₂₄: one-time cold rolling, 5 min ball milling and addition of 4 wt.% of Zr. All samples were synthesized by arc melting. Without Zr addition the alloy was single phase, but when 4 wt.% Zr was added, a secondary zirconium-rich phase was present. However, X-ray diffraction patterns only showed a single-body-centred cubic phase before hydrogenation for all samples. The crystal structure of the fully hydrogenated samples was body-centred tetragonal. The highest hydrogen capacity (3.8 wt.%) was measured for the Zr-doped alloy. The ball-milled alloy also exhibited a high storage capacity and fast kinetics. However, the maximum hydrogen storage capacity slightly decreased after cold rolling. It was found that air exposure increases incubation time for the first hydrogenation. The incubation time was shortened by cold rolling which, however, reduced the hydrogen storage capacity. The Pressure-Composition isotherms of Ti₁₆V₆₀Cr₂₄ + 4 wt.% Zr at 297, 303 and 323 K were determined. The determined enthalpy and entropy of hydrides formation were −41 ± 5 kJ/mol and −134 ± 14 J/mol/K, respectively. Full article

(This article belongs to the Special Issue Feature Papers in Hydrogen)

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18 pages, 4009 KiB

Open AccessReview

Hydrogen Diffusion on, into and in Magnesium Probed by DFT: A Review

by Marina G. Shelyapina

Hydrogen 2022, 3(3), 285-302; https://doi.org/10.3390/hydrogen3030017 - 5 Jul 2022

Cited by 10 | Viewed by 4700

Abstract

Hydrogen is an energy carrier that can be a sustainable solution for alternative energy with zero greenhouse gas emissions. Hydrogen storage is a key point for hydrogen energy. Metals provide an access for safe, controlled and reversible hydrogen storage and release. Magnesium, due to its outstanding hydrogen storage capacity, high natural abundance, low cost and non-toxicity is one of the most attractive materials for hydrogen storage. The economic efficiency of Mg as a hydrogen accumulator is limited by its sluggish hydrogen sorption kinetics and high stability of its hydride MgH₂. Many attempts have been made to overcome these shortcomings. On a microscopic level, hydrogen absorption by metal is a complex multistep process that is impossible to survey experimentally. Theoretical studies help to elucidate this process and focus experimental efforts on the design of new effective Mg-based materials for hydrogen storage. This review reports on the results obtained within a density functional theory approach to studying hydrogen interactions with magnesium surfaces, diffusion on Mg surfaces, into and in bulk Mg, as well as hydrogen induced phase transformations in MgH_x and hydrogen desorption from MgH₂ surfaces. Full article

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