Russian Federation
Deflagration-to-detonation Transition in Highly Reactive Combustible Mixtures
Sep 2011
Publication
High resolution numerical simulations used to study the mechanism of deflagration-to-detonation transition (DDT). The computations solved two-dimensional time-dependent reactive Navier-Stokes equations including the effects of compressibility molecular diffusion thermal conduction viscosity and detailed chemical kinetics for the reactive species with subsequent chain branching production of radicals and energy release. It is shown that from the beginning the flame accelerates exponentially producing shock waves far ahead. On the next stage the flame acceleration decreases and the shocks are formed close ahead of the flame front. The final stage is the actual transition to detonation. During the second stage a compressed unreacted mixture of increased density enters the flame producing a high pressure pulse which enhances reaction rate and the heat release in the reaction zone with a positive feedback coupling between the pressure pulse and the reaction rate. As a result the peak of the pressure pulse grows exponentially steepens into a strong shock which is coupled with the reaction zone forming the overdriven detonation. This new mechanism of DDT is different from the Zel’dovich’s gradient mechanism. The temperature gradients which appear in the form of hot spots and the like are not suitable to initiate detonation.
Experimental and Numerical Investigation of Hydrogen Gas Auto-ignition
Sep 2007
Publication
This paper describes hydrogen self-ignition as a result of the formation of a shock wave in front of a high-pressure hydrogen gas propagating in the tube and the semi-confined space for which the numerical and experimental investigation was done. An increase in the temperature behind the shock wave leads to the ignition on the contact surface of the mixture of combustible gas with air. The required condition of combustible self-ignition is to maintain the high temperature in the mixture for a time long enough for inflammation to take place. Experimental technique was based on a high-pressure chamber inflating with hydrogen burst disk failure and pressurized hydrogen discharge into tube of round or rectangular cross section filled with air. A physicochemical model involving the gas dynamic transport of a viscous gas the detailed kinetics of hydrogen oxidation k-ω differential turbulence model and the heat exchange was used for calculations of the self-ignition of high-pressure hydrogen. The results of our experiments and model calculations show that self-ignition in the emitted jet takes place. The stable development of self-ignition naturally depends on the orifice size and the pressure in the vessel a decrease in which leads to the collapse of the ignition process. The critical conditions are obtained.
Hydrogen-induced Failure of TiNi Based Alloy with Coarse-grained and Ultrafine-grained Structure
Jul 2016
Publication
The objective of this work is to investigate the effect of hydrogen-induced fracture of TiNi-based alloy. In this report we performed the first studies comparing inelastic properties and fracture of the specimens of the binary alloy of TiNi wire under the action of hydrogen with coarse-grained (CG) and ultrafine-grained (UFG) microstructure. It is shown that hydrogen embrittlement (HE) occurs irrespective of the grain size in the studied specimens at approximately equal strain values. However compared to the specimens with CG structure those with UFG structure accumulate two to three times more hydrogen for the same hydrogenation time. It is found that hydrogen has a much smaller effect on the inelastic properties of specimens with UFG structure as compared to those with CG structure.
Vacuum vs Argon Technology for Hydrogen Measurement
Dec 2018
Publication
Within the framework of this paper we review the development of the problem of hydrogen diagnostic for metals. Metal sample enrichment techniques based on hydrogen vacuum extraction method used for a long time. Development of the industrial control technologies has led to the almost complete replacement of vacuum techniques with “atmospheric” ones. As a result systematic errors have occurred. These errors lead to multiple differences between certified and measured hydrogen concentration values for standard samples.<br/>In this paper we analyze reasons of systematic errors genesis observed for hydrogen measurements while applying the thermal conductivity cell technique. As a result we demonstrated that measurements resulting from samples heating and melting in the inert gas flow depend on its heat capacity and surface temperature of the melting pot. Due to this reason one can obtain multiple errors and even negative values for measurements of a low hydrogen concentration."
Mechanical Properties of Gas Main Steels after Long-Term Operation and Peculiarities of Their Fracture Surface Morphology
Feb 2019
Publication
Regularities of steel structure degradation of the “Novopskov-Aksay-Mozdok” gas main pipelines (Nevinnomysskaya CS) as well as the “Gorky-Center” pipelines (Gavrilovskaya CS) were studied. The revealed peculiarities of their degradation after long-term operation are suggested to be treated as a particular case of the damage accumulation classification (scheme) proposed by prof. H.M. Nykyforchyn. It is shown that the fracture surface consists of sections of ductile separation and localized zones of micro-spalling. The presence of the latter testifies to the hydrogen-induced embrittlement effect. However the steels under investigation possess sufficiently high levels of the mechanical properties required for their further safe exploitation both in terms of durability and cracking resistance.
Kinetics of Brittle Fracture in Metals Under the Influence of Hydrogen
Jan 2020
Publication
Some aspects of damage accumulation modelling and brittle fracture processes mechanisms under the combined effect of mechanical loading and hydrogen has been discussed in the article. New mechanism of brittle fracture for metallic materials based on dislocation and phonon structure fingerprints and lattice hydrogen content under the static and dynamic loading at low temperature condition has been proposed. The mechanism based on theoretical research and experimental and numerical studies. The experiments include the energy spectrum of internal friction determination and impact toughness testing for low-temperature brittle-ductile transition revealing. The numerical study based on damage accumulation modeling under the influence of up-hill diffusion in the elastic-plastic problem of solid state by finite element method. A new simple activation model of low temperature and hydrogen influence on damage accumulation process has been proposed. The model shows the rate of damage strong dependence of stress level and hydrogen content and test temperature. The combination of low temperature and high hydrogen content is most dangerous so the weld structures in extreme environment such as the Arctic and Subarctic regions have a high risk of breakage. So it is possible to estimate the energy and phonon spectrum of crystal lattice and predict the properties of microcrystalline and nanostructured materials with the high cold-short threshold on the base of such the approach. There are the recommendations propose to improve the cold resistance of steels and alloys by controlling the characteristics of the dislocation structure of new materials with polycrystalline and ultrafine-grained structure.
Magnesium Based Materials for Hydrogen Based Energy Storage: Past, Present and Future
Jan 2019
Publication
Volodymyr A. Yartys,
Mykhaylo V. Lototskyy,
Etsuo Akiba,
Rene Albert,
V. E. Antonov,
Jose-Ramón Ares,
Marcello Baricco,
Natacha Bourgeois,
Craig Buckley,
José Bellosta von Colbe,
Jean-Claude Crivello,
Fermin Cuevas,
Roman V. Denys,
Martin Dornheim,
Michael Felderhoff,
David M. Grant,
Bjørn Christian Hauback,
Terry D. Humphries,
Isaac Jacob,
Petra E. de Jongh,
Jean-Marc Joubert,
Mikhail A. Kuzovnikov,
Michel Latroche,
Mark Paskevicius,
Luca Pasquini,
L. Popilevsky,
Vladimir M. Skripnyuk,
Eugene I. Rabkin,
M. Veronica Sofianos,
Alastair D. Stuart,
Gavin Walker,
Hui Wang,
Colin Webb,
Min Zhu and
Torben R. Jensen
Magnesium hydride owns the largest share of publications on solid materials for hydrogen storage. The “Magnesium group” of international experts contributing to IEA Task 32 “Hydrogen Based Energy Storage” recently published two review papers presenting the activities of the group focused on magnesium hydride based materials and on Mg based compounds for hydrogen and energy storage. This review article not only overviews the latest activities on both fundamental aspects of Mg-based hydrides and their applications but also presents a historic overview on the topic and outlines projected future developments. Particular attention is paid to the theoretical and experimental studies of Mg-H system at extreme pressures kinetics and thermodynamics of the systems based on MgH2 nanostructuring new Mg-based compounds and novel composites and catalysis in the Mg based H storage systems. Finally thermal energy storage and upscaled H storage systems accommodating MgH2 are presented.
An Experimental Study of the Possibility of In Situ Hydrogen Generation within Gas Reservoirs
Aug 2021
Publication
Hydrogen can be generated in situ within reservoirs containing hydrocarbons through chemical reactions. This technology could be a possible solution for low-emission hydrogen production due to of simultaneous CO2 storage. In gas fields it is possible to carry out the catalytic methane conversion (CMC) if sufficient amounts of steam catalyst and heat are ensured in the reservoir. There is no confirmation of the CMC’s feasibility at relatively low temperatures in the presence of core (reservoir rock) material. This study introduces the experimental results of the first part of the research on in situ hydrogen generation in the Promyslovskoye gas field. A set of static experiments in the autoclave reactor were performed to study the possibility of hydrogen generation under reservoir conditions. It was shown that CMC can be realized in the presence of core and ex situ prepared Ni-based catalyst under high pressure up to 207 atm but at temperatures not lower than 450 ◦C. It can be concluded that the crushed core model improves the catalytic effect but releases carbon dioxide and light hydrocarbons which interfere with the hydrogen generation. The maximum methane conversion rate to hydrogen achieved at 450 ◦C is 5.8%
On Flame Ball-to-Deflagration Transition in Hydrogen-air Mixtures
Sep 2021
Publication
Ultra-lean hydrogen-air combustion is characterized by two phenomena: the difference in upward and downward flame propagation concentration limits and the incomplete combustion. The clear answers on the two basic questions are still absent: What is a reason and what is a mechanism for their manifestation? Problem statement and the principal research topics of the Flame Ball to Deflagration Transition (FBDT) phenomenon in gaseous hydrogen-air mixtures are presented. The non-empirical concept of the fundamental concentration limits discriminates two basic low-speed laminar combustion patterns - self-propagating locally planar deflagration fronts and drifting locally spherical flame balls. To understand - at what critical conditions and how the baric deflagrations are transforming into iso- baric flame balls? - the photographic studies of the quasi-2-dim flames freely propagating outward radially via thin horizontal channel were performed. For gradual increase of initial hydrogen concentration from 3 to 12 vol.% the three representative morphological types of combustion (star-like dendrite-like and quasi-homogeneous) and two characteristic processes of reaction front bifurcation were revealed. Key elements of the FBDT mechanism both for 2-dim and 3-dim combustion are the following. Locally spherical ""leading centres"" (drifting flame balls) are the ""elementary building blocks"" of all ultra-lean flames. System of the drifting flame balls is formed due to primary bifurcation of the pre-flame kernel just after ignition. Subsequent mutual dynamics and overall morphology of the ultra-lean flames are governed by competitive non-local interactions of the individual drifting flame balls and their secondary/tertiary/etc. bifurcations defined by initial stoichiometry."
Hydrogen Production through Autothermal Reforming of Ethanol: Enhancement of Ni Catalyst Performance via Promotion
Aug 2021
Publication
Autothermal reforming of bioethanol (ATR of C2H5OH) over promoted Ni/Ce0.8La0.2O1.9 catalysts was studied to develop carbon-neutral technologies for hydrogen production. The regulation of the functional properties of the catalysts was attained by adjusting their nanostructure and reducibility by introducing various types and content of M promoters (M = Pt Pd Rh Re; molar ratio M/Ni = 0.003–0.012). The composition–characteristics–activity correlation was determined using catalyst testing in ATR of C2H5OH thermal analysis N2 adsorption X-ray diffraction transmission electron microscopy and EDX analysis. It was shown that the type and content of the promoter as well as the preparation mode (combined or sequential impregnation methods) determine the redox properties of catalysts and influence the textural and structural characteristics of the samples. The reducibility of catalysts improves in the following sequence of promoters: Re < Rh < Pd < Pt with an increase in their content and when using the co-impregnation method. It was found that in ATR of C2H5OH over bimetallic Ni-M/Ce0.8La0.2O1.9 catalysts at 600 ◦C the hydrogen yield increased in the following row of promoters: Pt < Rh < Pd < Re at 100% conversion of ethanol. The introduction of M leads to the formation of a NiM alloy under reaction conditions and affects the resistance of the catalyst to oxidation sintering and coking. It was found that for enhancing Ni catalyst performance in H2 production through ATR of C2H5OH the most effective promotion is with Re: at 600 ◦C over the optimum 10Ni-0.4Re/Ce0.8La0.2O1.9 catalyst the highest hydrogen yield 65% was observed.
A Critical Review of Renewable Hydrogen Production Methods: Factors Affecting Their Scale-Up and Its Role in Future Energy Generation
Feb 2022
Publication
An increase in human activities and population growth have significantly increased the world’s energy demands. The major source of energy for the world today is from fossil fuels which are polluting and degrading the environment due to the emission of greenhouse gases. Hydrogen is an identified efficient energy carrier and can be obtained through renewable and non-renewable sources. An overview of renewable sources of hydrogen production which focuses on water splitting (electrolysis thermolysis and photolysis) and biomass (biological and thermochemical) mechanisms is presented in this study. The limitations associated with these mechanisms are discussed. The study also looks at some critical factors that hinders the scaling up of the hydrogen economy globally. Key among these factors are issues relating to the absence of a value chain for clean hydrogen storage and transportation of hydrogen high cost of production lack of international standards and risks in investment. The study ends with some future research recommendations for researchers to help enhance the technical efficiencies of some production mechanisms and policy direction to governments to reduce investment risks in the sector to scale the hydrogen economy up.
Hydrogen Accumulation and Distribution in Pipeline Steel in Intensified Corrosion Conditions
Apr 2019
Publication
Hydrogen accumulation and distribution in pipeline steel under conditions of enhanced corrosion has been studied. The XRD analysis optical spectrometry and uniaxial tension tests reveal that the corrosion environment affects the parameters of the inner and outer surface of the steel pipeline as well as the steel pipeline bulk. The steel surface becomes saturated with hydrogen released as a reaction product during insignificant methane dissociation. Measurements of the adsorbed hydrogen concentration throughout the steel pipe bulk were carried out. The pendulum impact testing of Charpy specimens was performed at room temperature in compliance with national standards. The mechanical properties of the steel specimens were found to be considerably lower and analogous to the properties values caused by hydrogen embrittlement.
Effect of Vanadium-alloying on Hydrogen Embrittlement of Austenitic High-nitrogen Steels
Dec 2018
Publication
The effect of hydrogen on tensile behavior and fracture mechanisms of V-alloying and V-free high-nitrogen austenitic steels was evaluated. Two steels with the chemical compositions of Fe-23Cr–17Mn–0.1C–0.6N (0V-HNS) and Fe-19Cr–22Mn–1.5V–0.3C–0.9N (1.5V-HNS) were electrochemically hydrogen-charged in NaCl water-solution for 100 hours. According to X-ray diffraction analysis and TEM researches V-alloying promotes particle strengthening of the 1.5V-HNS. Despite differences in chemical compositions namely carbon and nitrogen concentrations a solid solution hardening is similar for both steels because of precipitate-assisted depletion of austenite by interstitial atoms (carbon and nitrogen) in 1.5V-HNS. For hydrogen-free state the values of the yield stress and the tensile strength are higher for particle-strengthened 1.5V-HNS as compared to 0V-HNS. Hydrogen-charging increases both the yield stress and the tensile strength of the steels but hydrogen-assisted fracture micromechanisms are different for 0V-HNS and 1.5V-HNS. Hydrogen-charging drastically reduces a total elongation in 0V-HNS but provides insufficient embrittlement in 1.5V-HNS. Hydrogen-assisted brittle layers form on lateral surfaces of the specimens and the widths and fracture micromechanisms in them are different for two steels. For 0V-HNS surface layers of 84 μm in width possess transgranular brittle fracture mechanism (quasi-cleavage mode). For 1.5V-HNS the brittle surface layers (31 μm width) destroy in intergranular brittle fracture mode. The central parts of steel specimens show dimple fracture similar to hydrogen-free steels. The possible reasons for different hydrogen-induced effects in 0V-HNS and 1.5V-HNS are discussed.
Investigation of Structure of AlN Thin Films Using Fourier-transform Infrared Spectroscopy
Feb 2020
Publication
This study focuses on structural imperfections caused by hydrogen impurities in AlN thin films obtained using atomic layer deposition method (ALD). Currently there is a severe lack of studies regarding the presence of hydrogen in the bulk of AlN films. Fourier-transform infrared spectroscopy (FTIR) is one of the few methods that allow detection bonds of light elements in particular - hydrogen. Hydrogen is known to be a frequent contaminant in AlN films grown by ALD method it may form different bonds with nitrogen e.g. amino (–NH2) or imide (–NH) groups which impair the quality of the resulting film. Which is why it is important to investigate the phenomenon of hydrogen as well as to search for the suitable methods to eliminate or at least reduce its quantity. In this work several samples have been prepared using different precursors substrates and deposition parameters and characterized using FTIR and additional techniques such as AFM XPS and EDS to provide a comparative and comprehensive analysis of topography morphology and chemical composition of AlN thin films.
Mathematical Description of Energy Transition Scenarios Based on the Latest Technologies and Trends
Dec 2021
Publication
This work dedicated to a mathematical description of energy transition scenarios consists of three main parts. The first part describes modern trends and problems of the energy sector. A large number of charts reflecting the latest updates in energy are provided. The COVID-2019 pandemic’s impacts on the energy sector are also included. The second part of the paper is dedicated to the analysis of energy consumption and the structure of the world fuel and energy balance. Furthermore a detailed description of energy-efficient technologies is given. Being important and low-carbon hydrogen is discussed including its advantages and disadvantages. The last part of the work describes the mathematical tool developed by the authors. The high availability of statistical data made it possible to identify parameters used in the algorithm with the least squares method and verify the tool. Performing several not complicated steps of the algorithm the tool allows calculating the deviation of the average global temperature of the surface atmosphere from preindustrial levels in the 21st century under different scenarios. Using the suggested mathematical description the optimal scenario that makes it possible to keep global warming at a level below 1.7 ◦C was found.
Hydrogen Subsonic Upward Release and Dispersion Experiments in Closed Cylindrical Vessel
Sep 2007
Publication
Report presents the preliminary experimental results on hydrogen subsonic leakage in a closed vessel under the well-controlled boundary/initial conditions. Formation of hydrogen-air gas mixture cloud was studied for a transient (10 min) upward hydrogen leakage which was followed by subsequent evolution (15 min) of explosive cloud. Low-intensity ( 0.46⋅10−3 m3/sec) hydrogen release was performed via circular (diameter 0.014 m) orifice located in the bottom part of a horizontal cylindrical vessel ( ≈4 m3). A spatially distributed net of the 24 hydrogen sensors and 24 temperature sensors was used to permanently track the time dependence of the hydrogen concentration and temperature fields in vessel. Analysis of the simultaneous experimental records for the different spatial points permits to delineate the basic flow patterns and stages of hydrogen subsonic release in closed vessel in contrast to hydrogen jet release in open environment. The quantitative data were obtained for the averaged speeds of explosive cloud envelop (50% fraction of the Lower Flammability Limit (LFL)) propagation in the vertical and horizontal directions. The obtained data will be used as an experimental basis for development of the guidelines for an indoors allocation of the hydrogen sensors. Data can be also used as a new benchmark case for the reactive Computational Fluid Dynamics codes validation.
Explosion Hazard of Hydrogen-Air Mixtures in the Large Volumes
Sep 2007
Publication
The report deals with the investigation of non-stationary combustion of hydrogen-air mixtures extremely relevant to the issues of safety. Considered are the conditions of its formation and development in the tubes in the conic element and in the spherical 12-m diameter chamber. The report shows that at the formation of non-stationary combustion in the conic element in its top the pressure can develop exceeding 1000 atmospheres. It is also shown that in large closed volumes non-stationary combustion can develop from a small energy source in contrast to detonation for whose stimulation in large volumes significant power influences are required. Simultaneously in the volume a pressure can be formed by far exceeding the Chapman-Jouguet pressure in the front of stationary detonation.
Development of Hydrogen Sensors and Recombiners
Sep 2005
Publication
Hydrogen energy is very promising as it ensures a high efficiency and ecological cleanliness of energy conversion. The goal of the present work is to provide the analysis of hydrogen safety aspects and to prescribe methods of safety operation with hydrogen. The authors conducted a hazard analysis of hydrogen operation and storage in comparison with other fuels. Good ventilation is the main hydrogen operation requirement. Besides an effective way of protection against propagation of hazards (for instance leaks) is neutralization of dangerous hydrogen-air mixtures by a method of controlled catalytic combustion inside special devices so-called recombiners [1-3]. The basis of these devices is a high porosity cell material (HPCM) activated by platinum deposition. Apart from recombiners HPCM was also applied for development of hydrogen detectors intended for measurement and analysis of hydrogen concentration for hydrogen-driven transport and objects of hydrogen infrastructure (including vapor-air media at high pressure and temperatures). A system of hydrogen safety based on hydrogen detectors and hydrogen catalytic recombiners was developed. Experimental and theoretical studies of hydrogen combustion processes heat- and mass transfer and also gas flows in catalytic-activated HPCM allowed for a design optimization of recombiners and their location. Pilot hydrogen detectors and hydrogen catalytic recombiners were fabricated and their laboratory tests were successfully performed. Thus it was indicated that on condition of following the appropriate passive and active safety measures hydrogen is just as safe as the other fuels. This conclusion represents another incentive for a transition to the hydrogen energy.
Cell Failure Mechanisms in PEM Water Electrolyzers
Sep 2011
Publication
PEM water electrolysis offers an efficient and flexible way to produce “green-hydrogen” from renewable (intermittent) energy sources. Most research papers published in the open literature on the subject are addressing performances issues and to date very few information is available concerning the mechanisms of performance degradation and the associated consequences. Results reported in this communication have been used to analyze the failure mechanisms of PEM water electrolysis cells which can ultimately lead to the destruction of the electrolyzer. A two-step process involving firstly the local perforation of the solid polymer electrolyte followed secondly by the catalytic recombination of hydrogen and oxygen stored in the electrolysis compartments has been evidenced. The conditions leading to the onset of such mechanism are discussed and some preventive measures are proposed to avoid accidents.
Prospects and Obstacles for Green Hydrogen Production in Russia
Jan 2021
Publication
Renewable energy is considered the one of the most promising solutions to meet sustainable development goals in terms of climate change mitigation. Today we face the problem of further scaling up renewable energy infrastructure which requires the creation of reliable energy storages environmentally friendly carriers like hydrogen and competitive international markets. These issues provoke the involvement of resource-based countries in the energy transition which is questionable in terms of economic efficiency compared to conventional hydrocarbon resources. To shed a light on the possible efficiency of green hydrogen production in such countries this study is aimed at: (1) comparing key Russian trends of green hydrogen development with global trends (2) presenting strategic scenarios for the Russian energy sector development (3) presenting a case study of Russian hydrogen energy project «Dyakov Ust-Srednekanskaya HPP» in Magadan region. We argue that without significant changes in strategic planning and without focus on sustainable solutions support the further development of Russian power industry will be halted in a conservative scenario with the limited presence of innovative solutions in renewable energy industries. Our case study showed that despite the closeness to Japan hydrogen market economic efficiency is on the edge of zero with payback period around 17 years. The decrease in project capacity below 543.6 MW will immediately lead to a negative NPV. The key reason for that is the low average market price of hydrogen ($14/kg) which is only a bit higher than its production cost ($12.5/kg) while transportation requires about $0.96/kg more. Despite the discouraging results it should be taken into account that such strategic projects are at the edge of energy development. We see them as an opportunity to lead transnational energy trade of green hydrogen which could be competitive in the medium term especially with state support.
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