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Development of a hydrogen economy as part of the response to the challenges especially of climate change and energy security will depend upon the solution not only of technical problems, but also of legal and regulatory problems. Whereas these are most obviously related to health and safety, this paper focuses on the fact that support for hydrogen is increasingly contingent upon the method of its production and specifically upon the level of greenhouse gas emissions involved. The paper examines emerging arrangements in Australia and the EU as examples of likely future key hydrogen exporters and importers, respectively. [ABSTRACT FROM AUTHOR]

Large eddy simulations (LES) with flamelet and presumed filtered density function closure are used to simulate turbulent premixed and partially premixed hydrogen flames. Different approaches to model differential diffusion are investigated and compared. In particular, two existing models are extended to the LES framework to correct the resolved diffusive flux of the controlling variables due to differential diffusion. A lean premixed turbulent hydrogen flame in a slotted burner configuration is simulated first to compare the capability of the considered models in capturing local mixture fraction redistribution, super-adiabatic temperatures and thermo-diffusive instabilities. Results show that both models describe the formation of cellular burning structures. Next, a partially premixed lifted hydrogen flame in vitiated hot coflow is simulated to gain insight on the relevance of differential diffusion modelling at a higher turbulence level, a different combustion mode and in the presence of a complex stabilisation mechanism. Good predictions of the turbulent mixing and temperature fields are observed. Moreover, results show that the flame lift-off height has an appreciable sensitivity to the differential diffusion model. When differential diffusion is included only in the thermochemistry database, only mild effects on the predicted temperature fields, mixing and flame height are observed. On the contrary, a considerable shift of the flame base is observed when corrections are applied in the LES at the resolved level, depending on what controlling variables are considered. Further analyses reveal how the corrections of diffusive fluxes in the thermochemistry and at the LES level affect differently the flame burning mode, whose details are given throughout the paper. [ABSTRACT FROM AUTHOR]

The diffusion behaviour of hydrogen, carbon monoxide, carbon dioxide, methane, acetylene, ethylene and ethane in oil and paper medium was examined using molecular dynamics to reveal the diffusion mechanism of gas molecules in transformer oil–paper insulation system at the microscopic level. These compounds are commonly used in the dissolved gas analysis of power transformers and produced during the ageing process of oil–paper composite insulating material. Two groups of models were constructed using molecular dynamics simulation software to simulate the diffusion behaviour of the aforementioned seven types of small gas molecules in oil and paper. The diffusion coefficients, displacement features, free volume characteristics and interaction energies of the gas molecules were investigated. In particular, the diffusion micro-mechanism of the gas molecules was observed. The differences in diffusion features among the gas molecules were discussed, and the factors influencing the diffusion of the gas molecules were compared. Simulation results indicate that the diffusion coefficients of gas molecules in cellulose is an order of magnitude lower than that in oil, and the diffusion coefficients of these gas molecules in the two types of insulation media have different orders. Free volume of gas molecules is the main factor that influences the diffusion behaviour in oil, whereas intermolecular interaction is the main influencing factor of diffusion behaviour in cellulose. [ABSTRACT FROM PUBLISHER]

Various pyrometallurgical processes to produce TiO2 slag have been reviewed, focusing on the solid-state reduction aspects of ilmenite. Most of the upgradation processes from ilmenite to titania slag involve direct smelting of ilmenite and, therefore, are generally considered energy-intensive and not environmentally friendly. On the other hand, the pre-reduction of ilmenite, followed by the smelting processes, is advantageous because of its low energy consumption, furnace stability, and negligible slag foaming. In this paper, the impact of different reducing agents on the ilmenite reduction kinetics has been reviewed. The gas-based reduction techniques, primarily with hydrogen or hydrogen-enriched syngas as reductants, show better reaction kinetics and are more environment-friendly than the carbon-based reduction of ilmenite. Hence, the titania slag production from ilmenite can be made efficient and sustainable by incorporating the pre-reduction concept and gas-based reduction for the pre-reduction step. Numerous ways of improving ilmenite pre-reduction have been investigated intensively, featuring pre-oxidation, additives, mechanical activation, and microwave-assisted reduction. Since ilmenite is a good microwave absorber and the microwave-assisted reduction process provides faster kinetics, the method is also very promising for large-scale applications. [ABSTRACT FROM AUTHOR]

With the climate change and urbanization, the area of cultivated land is decreasing, and crops are also subjected to various biological and abiotic stresses. How to improve crop yield and stress resistance has become an urgent agricultural production problem that must be solved. Hydrogen has the characteristics of being green and clean, which has great advantages and is significant for the development of modern agriculture and sustainable agriculture. This paper reviews the effects of hydrogen on plant growth and development, stress resistance, and postharvest preservation, which has not been systematically reviewed. And the regulatory network for hydrogen to exert plant effects, involving miRNA, DNA expression, hormone changes, protein modification regulation, reactive oxygen species, and various gas signal molecules. As a simple and safe treatment method, hydrogen rich water (HRW) has a certain application prospect in agriculture. Finally, the development and practice of hydrogen agriculture are prospected. [ABSTRACT FROM AUTHOR]

In light of resource depletion, energy scarcity, and toxic waste management, gasification is regarded as a viable waste-to-energy conversion method. Moreover, the Gasifier-Engine-Genest combo provides a suitable alternative for distributed electric power, waste conversion, and alleviating electricity scarcity. Despite an abundance of research report, it is not usually acknowledged as a viable alternative to traditional energy sources. Thus, to promote Gasification, efficient technology is required to maximize the yield of syngas with clean and improved calorific value. Furthermore, there is a void in the prior study that summarises the various types of biomasses and their pre-treatment, as well as the progression of conventional gasification to advanced gasification for the improvement of syngas quality and respective critical applications. Moreover, this is necessary in order to organise the conditions and biomass for gasification, which are many and frequently scattered in the literature. Hence, this study summarises the detailed review of recent novel concepts development over conventional techniques of biomass gasification. Recent reports on feed material properties of diverse biomass, as well as pre-treatment employing biomass torrefaction for gasification, are presented in this paper in order to evaluate their potential. In addition, a literature review of the various categories of gasification, the gasification processes, and the impact of technology on the quality of syngas, power generation and distribution were reported. In conclusion, it is proposed that enhanced gasification technology be employed to implement sustainable development in order to reduce the existing reliance on non-renewable energy sources. [ABSTRACT FROM AUTHOR]

To understand the dispersion of hydrogen (H2) leaked in a partially open space practically, which can be considered as a basic model for all processes of transfer, treatment, storage, and disposal of radioactive materials containing fuel debris in the decommissioning of nuclear facilities after a severe accident, this paper uses a computational fluid dynamics code to study analytically the effects of vent size and outer wind on H2 dispersion. The paper adopts the experimental Hallway model, which has a H2 release hole on the ceiling, one vent on the roof (Roof vent), and one vent on the side (Door vent). Air flows in the model (room) from the Door vent while H2 is discharged outside from the Roof vent. The discharged (outflow) amount of H2 increases in conjunction with the air inflow when the size of the Roof and/or Door vents is increased, and then vice versa. The effect of wind depends on the direction to the Door vent: Wind from the same direction as the Door vent promotes H2 discharge while wind from the opposite direction suppresses it. The dispersion behavior characteristics of indoor leaked H2 are clarified for comparing model tests with the same Froude number and different scales. It is found from the analysis results of comparing model tests with the same Froude number and different scales that when H2 leaks into the room and diffuses to the air, the flow generated by the buoyancy of mixed gas creates the stack effect, which causes natural ventilation by drawing in air from the outside through the vent. In addition, it is speculated that the H2 concentration decreases after its leak by quickly mixing with air that flows in from the vents and reaches the floor due to the Coanda effect, which is the effect of the free jet being drawn to a nearby wall. [ABSTRACT FROM AUTHOR]

The paper demonstrates the prospects of using an approach for calculating adsorption isotherms of gases on micropore industrial zeolites based on the example of H2, CO2, CO, CH4, N2 adsorption on 13X and 5A zeolites using the Dubinin–Radushkevich–Astakhov (DRA) equation. Experimental adsorption isotherms of H2, CO2, CO, CH4, N2 gases on 13X and 5A zeolites of various manufacturers have been obtained, as well as ranges of the limiting adsorption volume and characteristic adsorption energy have been established. It made it possible to correctly calculate isotherms using the DRA equation in the temperature range 293–323 K and pressure range 0–30 atm. The paper proposes and solves the optimization problem of determining affinity coefficients, which allows the calculation of gas adsorption isotherms on zeolites using only one experimental isotherm of standard gas N2. The mismatch between the experimental isotherms and those calculated by the DRA equation is 14.69% for H2 (maximum) and 1.81% for CO2 (minimum). This approach makes it possible to significantly reduce the number of necessary expensive experiments in comparison with the traditional approach (using the Langmuir equations or equations derived from it), at the same time providing acceptable accuracy for practice. [ABSTRACT FROM AUTHOR]

During a loss-of-coolant accident in a pressurized water reactor (PWR), steam of varying quality is released from the primary circuit into the equipment compartments of the containment, followed by the release of a hydrogen-steam mixture during the core degradation phase. In the case of long-lasting accidents, findings of detailed code analyses indicate an enrichment of hydrogen in lower peripheral containment compartments in the reference PWR plant under investigation. During the late accident phase with ex-vessel molten core–concrete interaction, even in the case of an operating passive autocatalytic recombiner system, this poses a threat for local hydrogen combustion later on. Such hydrogen phenomena are not expected and have not been widely studied up to now. Therefore, corresponding experiments have been performed at the THAI test facility operated by Becker Technologies. One of these tests had been precalculated with the COntainment COde SYStem (COCOSYS) as part of the Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) code system AC2 and has been used to validate the code. The 60-m3 THAI test vessel has been divided into an inner compartment that has been connected to the surrounding vessel, simulating the upper and peripheral containment part, by very small flow openings at the bottom representing the clearance between door frames and door leaves and one opening at the top representing typical openings by burst disks. The paper discusses both the experimental findings of a test series on the potential enrichment of hydrogen in lower containment compartments and the COCOSYS calculations demonstrating the applicability of the code under complex flow conditions including stratification phenomena. [ABSTRACT FROM AUTHOR]

This paper examines the satisfaction of the principle of corresponding states (PCS) on thepressure–density–temperature relation and the binary diffusion coefficient of hydrogen/oxygen mixture modelled as binary Lennard–Jones (LJ) fluid especially in a supercritical region. The hydrogen/oxygen mixture properties were computed by molecular dynamics simulation and compared with simulation results for a nitrogen/oxygen mixture as well as while using the Peng–Robinson (PR) equation of state (EOS) for both mixture types and a mono-component LJ-EOS. The Fuller–Schettler–Giddings model with the PR-EOS and Takahashi's EOS were used for binary diffusion coefficient comparison. The pseudocritical point concept of a fluid mixture was applied for PCS reduction and PCS satisfaction was conducted over a wide temperature range above the pseudocritical pressure with changing hydrogen molar fraction. PCS satisfaction for hydrogen/oxygen mixture properties was confirmed at reduced temperature of 1.5 or above. At reduced temperature of 1.0 or below, the hydrogen/oxygen mixture properties disagree with those of the comparison mixture because phase separation occurs. We conclude that the properties of hydrogen/oxygen mixtures can be estimated using the pseudocritical point concept and the investigated EOSs based on the PCS in the supercritical region at reduced temperature of1.5 or above. [ABSTRACT FROM AUTHOR]

The experiments on microwave pyrolysis of soybean straw are studied to produce hydrogen-rich gas under CO2 atmosphere in this paper. The microwave power has an important effect on the temperature. The final temperature increases and the time to obtain the highest temperature is shortened with the power increasing. The gas yield, H2 yield and potential H2 yield increase rapidly with the power increasing, and the gaseous yield at CO2 atmosphere is up to 55.70% at 1000 W, and it is higher than N2 atmosphere. The main components of microwave pyrolysis gas product are H2 and CO, the content of syngas (H2+ CO) at CO2 atmosphere is 84.19% at 1000 W, which is more than N2 atmosphere. However, H2/CO ratio is about 0.80 at CO2 atmosphere, which is lower than N2 atmosphere, and H2/CO ratio at CO2 atmosphere is not suitable for the requirements of chemical synthesis. If it is used to synthesize liquid fuels, H2/CO ratio must be adjusted. [ABSTRACT FROM AUTHOR]

Preferential diffusion is very important in simulations of hydrogen flames. Flame stretch and curvature induce strong preferential diffusion effects in laminar premixed hydrogen flames, causing strong local deviations from the unburnt mixture fraction in the reaction zone. In tabulated chemistry methods, this necessitates the use of a partially premixed model even if the inlet mixture is purely premixed. Furthermore, in realistic combustion problems heat losses often play a dominant role. In this paper we derive a preferential diffusion model for constant but non-unity species Lewis numbers using three controlling variables, namely mixture fraction, progress variable and enthalpy. The model has been implemented in the Flamelet Generated Manifold (FGM) approach and validated by comparing with detailed chemistry simulations. As a test case we investigate a 2D laminar premixed hydrogen flame stabilised on an isothermal slit burner. Additionally, the model was compared with the standard treatment of preferential diffusion in FGM to show the increase in accuracy of the new model presented in this paper. The new model shows a significant improvement compared to the previous model, which can be attributed to the inclusion of cross-diffusion. The importance of the additional diffusion terms and its variation in mixture fraction for initially purely premixed hydrogen flames is highlighted. [ABSTRACT FROM AUTHOR]

In December 2020, Canada released its national strengthened climate change plan with focus on cutting energy waste, cutting pollution, and build clean industrial advantage. Two weeks later, the national hydrogen strategy was announced urging all involved stakeholders to delve into the deployment of large-scale clean energy technologies. Ontario, Canada's largest economy and leading manufacturing province, it releases its provincial hydrogen strategy and roadmap later this year. represents a viable solution for reducing CO2 emissions from large industry pollutants by integrating our innovative copper chlorine (Cu-Cl) thermochemical water splitting cycle with the energy intensive and polluting industry of cement manufacturing. The paper highlights the nexus between the production process of two valuable commodities, namely cement and Hydrogen, and the role their integration introduces for increased energy efficiency and reduction of greenhouse gas emissions. In addition, as most of the thermal energy demand in cement manufacturing is utilized during the kiln processes, the paper proposes several energy mix scenarios involving the use of hydrogen to partially meet the kiln's heat demand. The results from these scenarios show the possibility of achieving over 15% to 19.6% reduction in CO2 emissions compared to coal-based kiln production, along with reduced recurring cost for operating the kiln. On-site large-scale hydrogen production, mixed with natural gas, was found to be financially viable and environmentally advantageous alternative to power the kilns. [ABSTRACT FROM AUTHOR]

This paper first measures the level of environmental efficiency (EE) in 72 countries between 2001 and 2019 by adopting the Global Malmquist-Luenberger productivity index in the framework of the super slack-basedmeasure model. Then, by using the instrument variable-generalized method of moments (IV-GMM) approach, we examine the role of hydrogen development in increasing EE. We also pay attention to the asymmetric effect, the moderating effect, and the mediating effect in the hydrogen development-EE nexus. Several findings are highlighted as follows: (1) Hydrogen development can significantly increase EE. (2) The marginal impact of hydrogen development on EE is significantly positive in countries with a high level of EE, while it is insignificant in countries with a low level of EE, which shows the asymmetric EE enhancement effect of hydrogen development. (3) Foreign direct investment is a key moderating variable in the nexus between hydrogen development and EE, which can strengthen this positive nexus. And (4) mediating effect analysis documents that technological progress is an effective mediating variable through which hydrogen development affects EE. According to these results, we propose several policy implications for the acceleration of hydrogen development and EE. [ABSTRACT FROM AUTHOR]

By a historical overview, we show the importance of a laconic paper by Kolos and Wolniewicz dating to 1962 [Phys. Lett. 5(2), 222–223 (1962)], in which they applied the variational method for the hydrogen molecule. In the first part of this perspective (say till 1996), the experiments on electron molecule scattering (including hydrogen) developed a vast range of techniques, even if the results were far from being congruent [Riv. Nuovo Cimento 19/3, 1996]. In turn, in the last years, we have observed the quickly rising applicability of theoretical methods, like convergent-close coupling [Zammit et al. Phys. Rev. Lett. 116, 233201 (2016)] and R-matrix [Meltzer & Tennyson, J. Phys. Phys. B 53, 245203 (2020)]. The mutual agreement between theories and experiments allows defining recommended cross-sections for electron and positron scattering from zero to sub-relativistic energies. This, in turn, enables to check the dispersion relation, i.e. the interdependence between the zero-energy integral elastic, the high-energy elastic differential at zero angle, and the integral of the total cross-section from zero to infinity. Such a relation holds, within the experimental uncertainties, for positrons. For electrons, a big discrepancy points to the importance of the exchange effects in the e − − H 2 scattering. [ABSTRACT FROM AUTHOR]

Calculating the underlying quantum behaviour of dense hydrogen has proven to be difficult due to subtle electronic effects and also the lightness of the proton leading to large quantum motion. The analytical form of the contribution from the nuclear and electronic degrees of freedom (DOF) is integrated out of the Schödinger equation by way of the generated pseudo pair potential in this paper. This is accomplished through the adiabatically linear response approximation of an electron gas-jellium model to the perturbations induced by discrete hydrogen ions in the absence of an external field. This pair potential for the hydrogen ions can then be fitted to generate first-principles data. From these pair potentials, computational time can be drastically reduced for larger systems of dense hydrogen to determine their various properties. [ABSTRACT FROM AUTHOR]

Adding a certain proportion of hydrogen into the natural gas pipeline network is an effective way to solve the economical transportation problem of hydrogen. However, due to the special physical and chemical properties of hydrogen, there will be great potential safety hazards in the process of hydrogen transportation in the pipe network. In this paper, we studied the effect of adding hydrogen into T-tube on the explosion characteristics of methane hydrogen air premixed gas through experiments and numerical simulation. The results showed that hydrogen addition has an obvious effect on the explosion characteristics of the mixed gas. When the volume content of hydrogen exceeds 10%, the strengthening effect of the T-shaped bifurcation structure on the explosion reaction was more significant. The explosion characteristics in the upstream of the T-shaped bifurcation structure pipeline are consistent with those in the straight pipe, but it has a great impact on the downstream of the T-shaped bifurcation structure. When the flame passed through the bifurcation, the turbulence intensity in the pipe increased rapidly, which resulted the flame propagation velocity and explosion overpressure rising rapidly and exceeding the level before the bifurcation. The dynamic strain occurred on the thin wall of the pipe under the dynamic impact of gas cloud explosion, and the response of thin-wall strain had a good consistency with the explosion overpressure. In the experiment, the maximum strain at the bifurcation structure reached 1.02719 × 10 − 5 when the volume fraction of hydrogen was 20%. [ABSTRACT FROM AUTHOR]

This paper presents the glycerol dry reforming (GDR) reaction using rhenium (Re) promoted on Ni-based catalyst supported on Santa Barbara Amorphous 15 (SBA-15) for the production of hydrogen. In this study, the non-promoted (15%Ni/SBA-15) and promoted (3%Re-15%Ni/SBA-15) catalysts were first synthesized using wet impregnation method and their physicochemical characteristics were analyzed with Brunauer–Emmet–Teller (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric (TGA) analyses. Their performances were evaluated in GDR reaction and it was found that 3%Re-15%Ni/SBA-15 exhibited higher glycerol conversion (57%) and hydrogen yield (55%) than 15%Ni/SBA-15 (i.e., 20% glycerol conversion and 18% hydrogen yield). From the GDR study, the highest glycerol conversion (57%) and hydrogen yield (55%) for 3%Re-15%Ni/SBA-15 were obtained at 0.2 g catalyst, 700°C of reaction temperature, and CO2 to glycerol ratio (CGR) of 1:1. The small crystallite size and BET surface area of 3%Re-15%Ni/SBA-15 had successfully reduced the carbon deposition and indirectly contributed to high glycerol conversion and product yield. [ABSTRACT FROM AUTHOR]

In this paper, the influence of hydrogen volume fraction, pore size and layer number of foam copper on the explosion characteristics of hydrogen/methane premixed gas is discussed with the help of a self-built premixed gas explosion experimental platform. The volume fraction of hydrogen in the fuel is delineated as 0, 20%, 40%, 60%, and 80%. The pore diameters (Pd) of copper foam are Pd≈2.0 mm, Pd≈1.0 mm, and Pd≈0.5 mm, respectively, with three layers of foam copper for each pore diameter and a total of 45 sets of experiments are conducted. The experimental results show that the copper foam material has a significant hindering effect on the propagation of premixed hydrocarbon flame. As the hydrogen volume fraction gradually increases, the hindering effect of copper foam on the premixed flame gradually attenuates and can even promote flame development. The pore diameters of copper foam play a dominant role in the stability of flame behavior. The flame that can be halted during the propagation process is also mainly determined by the copper foam pore diameters. The number of copper foam layers does not determine the propagation state of the flame but only produces a greater degree of suppression or promotion of the flame once the propagation state has changed. [ABSTRACT FROM AUTHOR]

Synthesis of catalysts with high activity for hydrogen evolution reaction (HER) has been a hot topic in electrocatalysis. In this paper, using MIL-88A(Fe) metal-organic complex, polyoxometalate (POM) and H2PtCl6 as starting materials, hierarchic and low Pt0-loading micro-rods (denoted as Pt-POMFe, i.e. Pt-PW12Fe or Pt-PMo12Fe) have been synthesized, in which the Pt0 nanoparticles can be stabilized by POM. The Pt-PW12Fe micro-rod containing [PW12O40]3- polyoxoanion component (0.30% Pt0-loading) which retains the spindle structure of its parent MIL-88A(Fe) exhibits a low overpotential of 28 mV at current density of 10 mA·cm−2 for HER that is close to the electrocatalytic effect of commercial Pt/C (ca. 20% Pt0-loading). Such high electrocatalytic reactivity is mainly caused by the synergistic effect of the three components of POM, Pt0, and Fe3O4@C. The structure effectively increases the active sites of the catalyst and improves its conductivity and stability. The Pt-POMFe catalyst extends a new family of MOF-POM functional materials and provides a new concept to the design and synthesis of highly-efficient and low-cost electrocatalyst for hydrogen production. [ABSTRACT FROM AUTHOR]

This paper presents CFD modelling of hydrogen-air deflagrations. The proposed mathematical models are validated with the experiments provided to SARNET2 (Severe Accident Research NETwork of Excellence 2) project [A. Bentaib, A. Bleyer, N. Chaumeix, B. Schramm, P. Kostka, M. Movahed, H.S. Kang and M. Povilaitis, Final results of the SARNET Hydrogen deflagration Benchmark Effect of turbulence on flame acceleration. (2012), pp. 1–15; A. Bentaib, A. Bleyer, N. Meynet, N. Chaumeix, B. Schramm, M. Höhne, P. Kostka, M. Movahed, S. Worapittayaporn, T. Brähler, H. Seok-Kang, M. Povilaitis, I. Kljenak and P. Sathiah, SARNET hydrogen deflagration benchmarks: Main outcomes and conclusions. Ann. Nucl. Energy 74 (2014), pp. 143–152. doi:]. The goal of SARNET2 project was to investigate the effect of blockage ratio on flame propagation and pressure evolution during deflagration of a lean mixture of hydrogen and air. Three blockage ratios were tested: BR = 0, 0.33 and 0.63. The experiments were carried out in the ENACCEF facility. The proposed mathematical models test the effect of turbulence models and radiative heat losses on flame front position and absolute pressure in the testing facility. A good agreement between the calculated and experimental results for the three BRs is found for the SST k-ω model alone and in combination with the γ transition model when radiative heat losses are accounted for in the modelling. In addition, an unstable tulip flame is evidenced in our CFD simulations what corroborates previous reports on premixed combustion in a closed tube. [ABSTRACT FROM AUTHOR]

This paper aims at studying, the effects of biodiesel-diesel, biodiesel-hydrogen, and diesel-hydrogen fuel blends on engine performance, emissions, and combustion characteristics were investigated in a modified 4-cylinder, turbocharged, common rail direct injection, and compression ignition (CI) engine. Biodiesel was produced from through transesterification of Cynara cardunculus seed oil according to EN 14214 standards with a short-chain alcohol in the presence of a catalyst. The addition of hydrogen as a combustion enhancer used to counteract the increase in emissions and further improve engine performance. Hydrogen was injected in small quantities in the air intake manifold, while diesel-biodiesel blends were injected directly inside the cylinder. Diesel (D), biodiesel (B100), and biodiesel-diesel-hydrogen (B7+H2.5), biodiesel-hydrogen (B100+H2.5), and diesel-hydrogen (D+H2.5) fuel blends were used. Experimental results showed that while maximum engine power and maximum engine torque were obtained with B7+H2.5, the highest thermal efficiency was achieved with B100+H2.5. The lowest specific fuel consumption was obtained as 217 g/kWh at 2000 rpm with diesel. Maximum cylinder pressure and heat release rates were measured as 100.48 bar and 576.12 kJ/m3 deg with diesel fuel at 3000 rpm. The minimum CO emissions were obtained as 0.04% with B100 and B100+H2.5 fuels. CO2 and HC emissions reduced significantly whereas NOx increased, compared to diesel fuel. [ABSTRACT FROM AUTHOR]

In this paper optimal designing of two hybrid photovoltaic/wind turbine (PV/WT) systems with different storage include battery and hydrogen is presented with objective of minimising cost of energy generation (COEG) and considering reliability constraint as deficit power probability of the system using improved salp swarm optimisation algorithm (ISSOA) for commercial centre area, for Iran country. Different hybrid systems are compared in view of cost and reliability and the optimal size is determined. The results show that the PV/WT with battery storage has lower COEG than PV/WT with hydrogen storage to supply the commercial centre and also its reliability is better than the system integrated with hydrogen. The average cost of per kW of load supply for the PV/WT system with battery and hydrogen storage is 0.216$ and 0.610$, respectively. Superiority of ISSOA is confirmed in comparison with conventional SSOA and particle swarm optimisation in hybrid systems designing. [ABSTRACT FROM AUTHOR]

New options are needed to reduce the impact of motor vehicles on climate change and declining fossil fuel resources. Cars which are fueled by hydrogen could be a sustainable method of transportation if suitable technologies can be devised to produce hydrogen in an environmentally benign manner along with the provision of the necessary fueling infrastructure. This paper assesses size, space, and cost requirements of bioreactors as a decentralized option to supply hydrogen powered cars with biohydrogen produced from algae or cyanobacteria on a theoretical basis. Decentralized supply of biohydrogen could help to reduce the problems that hydrogen cars face regarding market penetration. A feasibility study for decentralized biohydrogen production is conducted, taking the quantity of hydrogen which is needed to fuel current hydrogen cars into account. While this technology is, in theory, feasible, sizes, and costs of such reactors are currently too high for widespread adoption. Thus, more R&D is needed to close the gap and to approach marketability. [ABSTRACT FROM AUTHOR]

This paper introduces a user-oriented software tool for simulation of a solar energy-based hydrogen production system. The developed tool goes beyond the realm of electric load and includes a hydrogen cooking load facility, as an efficient means of utilising the hydrogen produced. A model rural household in Nigeria has been used to evaluate the tool. It was found that a 2.42 kW solar photovoltaic module, 0.6 kW electrolyser and 3.7 kWh battery would be enough to provide steady 24-h power for a modest daily energy demand of 2.2 kWh. In the results, the excess energy realised was used in a H2-cooker to partly meet the estimated 1.9 kWh/day cooking demand of the household over a simulated year period. [ABSTRACT FROM AUTHOR]

This paper studies the effect of a plastic shear on the tetrahedral vs. octahedral site stability for hydrogen, in aluminium. Based on Density Functional Theory calculations, it is shown that the tetrahedral site remains the most stable site. It transforms into the octahedral site of the local hexagonal compact structure of the intrinsic stacking fault. The imperfect stacking is slightly attractive with respect to a regular lattice site. It is also shown that the shearing process involves a significant decrease of the energetic barrier for hydrogen jumps, at half the value of the Shockley partial Burgers vector, but not in the intrinsic stacking fault. These jumps involve a displacement component perpendicular to the shearing direction which favours an enhancement of hydrogen diffusion along edge dislocation cores (pipe diffusion). The magnitude of the boost in the jump rate in the direction of the dislocation line, according to Transition State Theory and taking into account the zero point energy correction, is of the order of a factor 50, at room temperature. First Passage Time Analysis is used to evaluate the effect on diffusion which is significant, by only at the nanoscale. Indeed, the common dislocation densities are too small for these effects (trapping, or pipe diffusion) to have a signature at the macroscopic level. The observed drop of the effective diffusion coefficient could therefore be attributed to the production of debris during plastic straining, as proposed in the literature. [ABSTRACT FROM AUTHOR]

Steam-gasification is a promising technology for hydrogen-rich syngas production with low tar content. In this work, an Artificial Neural Network (ANN) modeling of steam-gasification of residual oil was developed. The aim of this paper was to study the effect of steam flow rate (SFR) and reaction temperature on gas yield (GSY) and hydrogen yield (HDY). Results showed that GSY and HDY increased from 27.3 Nm3/kg to 37.1 Nm3/kg and 0.27 mol/kg to 0.39 mol/kg as the reaction temperature increased from 850 °C to 1000 °C. It was also found that with increase of SFR from 0.08 to 0.32, HDY increased from 7.5 mol/kg to 27.3 mol/kg. [ABSTRACT FROM AUTHOR]

Timely evolution of radioactive airborne aerosols, the mass of particles deposited on structures or transported with condensing water into the sump, and any influence of safety systems on the aerosol distribution will have a crucial influence on the potential aerosol source term into the environment. Different phenomena affect the main aerosol processes, and important ones besides gravimetrical and diffusive settling require experimental investigations to improve and validate modeling assumptions. Experimental investigations in the THAI (Thermal-hydraulics, Hydrogen, Aerosol, Iodine) test facility have been performed to investigate (a) insoluble silver aerosol wash-down behavior from vertical steel and horizontal decontamination paint-coated surfaces by condensing steam (test AW-3, supported by a laboratory-scale wash-down test series), and (b) the depletion of the airborne aerosol concentration by wash-out due to the use of a nuclear power plant typical water spray system (test AW-4). The paper discusses experimental findings of both tests supported by analytical analyses using the containment code system COCOSYS developed by Gesellschaft für Anlagen- und Reaktorsicherheit (GRS). To validate and further improve the new model Abwaschmodell für unlösliche Aerosole (AULA) in COCOSYS, used for the wash-down of insoluble aerosols from containment typical structures, the AW-3 laboratory tests related to the AW-3 test were used. Building upon these results, the AW-3 wash-down test is simulated. The results of the calculation for the AW-3 test show that the wash-down of insoluble silver particles at least qualitatively resembles the experimental results, though generally the washed-down aerosol mass is lower compared to the experiment. In test AW-4, it was in question if the modeling of aerosol wash-out with spray systems is adequately treated by assuming monodisperse spray droplets or if a droplet distribution has to be applied. Posttest calculation of AW-4 indicates that the wash-out of CsI aerosols by spray systems can be captured qualitatively. However, it is also shown that the calculated wash-out rate is too large and the depletion of the CsI aerosols during the dry phase is underestimated. [ABSTRACT FROM AUTHOR]

The installation of passive autocatalytic recombiners (PARs) in the containment of operating nuclear power plants (NPPs) is increasingly based on three-dimensional studies of severe accidents that accurately predict the hydrogen pathways and local accumulation regions in containment and examine the mitigation effects of the PARs on the hydrogen risk. The GOTHIC (Generation Of Thermal-Hydraulic Information for Containments) code is applied in this paper to study the effectiveness of the PARs installed in the Gösgen NPP in Switzerland. A fast release of a mixture of hydrogen and steam from the hot leg during a total station blackout is chosen as the limiting scenario. The PAR modeling approach is qualified simulating two experiments performed in the frame of the OECD/NEA (Organisation for Economic Co-operation and Development/Nuclear Energy Agency) THAI (Thermal-hydraulics, Hydrogen, Aerosols and Iodine) project. The results of the plant analyses show that the recombiners cannot prevent the formation of a stratified cloud of hydrogen (10% molar concentration), but they can mitigate the hydrogen accumulation once formed. In the case of the analyzed fast release scenario, which is characterized by increasing loads with large initial flow rate and high hydrogen concentration values, it is shown that, when a large number of recombiners are installed, the global outcome in relation to the combustion risk does not depend on the details of the single PAR behavior. The hydrogen ignition risk can be fully mitigated in a timeframe ranging from 15 to 30 min after the fast release, according to the dependence of the PAR efficiency model on the adopted parameters. [ABSTRACT FROM AUTHOR]

In this paper, essential statistics demonstrating the increasing role of renewable energy generation are firstly discussed. A state of the art review section covers fundamentals of wind turbines and PV systems. Included are schematic diagrams illustrating the main components and system topologies and the fundamental and increasing role of power electronics as an enabler for renewable energy integration, and for the future power system and smart grid. Recent examples of research and development, including new devices and system installations for utility power plants, as well for as residential and commercial applications are provided. Fuel cells, solar thermal, wave generators, and energy storage systems are also briefly presented and illustrated. Challenges and future trends for 2025 are summarized in a table for on-shore and off-shore wind energy, solar power, including photovoltaic and concentering, wave energy, fuel cells, and storage with batteries and hydrogen, respectively. Recommended further readings on topics of electric power engineering for renewable energy are included in a final section. This paper also represents an editorial introduction for two special issues of the Electric Power Component and Systems Journal, 43(8–10) and 43(12), respectively. [ABSTRACT FROM PUBLISHER]

This paper presents the results of comparative analysis of three run cycles of platinum catalyst for higher paraffins C9-C14 dehydrogenation process, performed using mathematical model. The results of model calculations were compared with the experimental data obtained at the industrial unit. It was established that deactivation of the platinum dehydrogenation catalyst is influenced by the technological modes of its operation, such as temperature, pressure, hydrogen/feedstock molar ratio and water supply. In the process of higher paraffins dehydrogenation, the phenomenon of platinum catalyst self-regeneration is observed. This occurs due to the action of feedstock components, in particular water and hydrogen involved in oxidation and hydrogenation of intermediate condensation products (coke structures). Model calculations showed that with a decrease in the hydrogen/feedstock molar ratio and simultaneous increase in water supply, depending on the temperature and composition of feedstock, it is possible to slow down deactivation process and increase the catalyst service life. This fact was experimentally confirmed at industrial unit. [ABSTRACT FROM AUTHOR]

This paper attempts to evaluate potential reductions in climate damage following the introduction of hydrogen fuel cell vehicles in Malaysia over the period 2015-2030. The simulation produced interesting results. While gross climate damage under the BAU scenario increased to RM7.1 billion in 2030, the commensurate damage under the slow, moderate and high hydrogen adaptation fell to MYR2.0 billion, MYR1.7 billion and MYR1.2 billion, respectively. CO2 emissions will fall from 214MT under the BAU scenario to 203MT, 176MT and 122MT, respectively, under the slow, moderate and high scenarios, respectively. Although real GDP is expected to stagnate over the period 2015-2030 under all three adaptation scenarios, the welfare benefits are expected to expand from the greening environment. While the high adaptation scenarios offer the best quantitative results, the choice of the intensity of adaptation will depend on the regulatory framework and the extent to which consumers can adapt. [ABSTRACT FROM AUTHOR]

The role of non-metallic inclusions in hydrogen-induced failure of structural materials has been a controversial topic for many years. In this paper, hydrogen trapping and its relation to the crack initiation at the inclusion-matrix interfaces are studied by considering the interfacial structure and the interaction between the dissolved hydrogen atoms and the elastic strains produced by lattice matching and misfit dislocations. A model is proposed to analyse the change of interfacial structure with inclusion size and its relation to hydrogen trapping. Hydrogen accumulation at the interfaces is quantitatively analysed. The obtained results are in good agreement with the experimental observations. The multiple factors, such as interfacial structure, chemical composition, elastic properties of matrix and inclusions, crystallographic relationship between inclusions and matrix, inclusion morphology and size, simultaneously control hydrogen trapping. In addition, the mechanism of hydrogen-induced crack initiation at the interface is investigated. A criterion is proposed to determine critical conditions for crack initiation. For the first time, the inherent relationship between hydrogen trapping and hydrogen-induced cracking at the interface is clarified. This work paves a way for an in-depth understanding of the effects of inclusions on hydrogen-induced degradation of mechanical properties. [ABSTRACT FROM AUTHOR]

We present and evaluate an efficient method for simulating Raman spectra from molecular dynamics calculationswithoutdefining normal modes. We apply the method to high pressure hydrogen in the high-temperature “Phase IV”: a plastic crystal in which the conventional picture of fixed phonon eigenmodes breaks down. Projecting trajectories onto in-phase molecular stretches is shown to be many orders of magnitude faster than polarisability calculations, allowing statistical averaging at high-temperature. The simulations are extended into metastable regimes and identify several regimes associated with symmetry-breaking on different timescales, which are shown to exhibit features in the Raman spectra at the current experimental limit of resolvability. In this paper we have concentrated on the methodology, a fuller description of the structure of Phase IV hydrogen is given in a previous paper [Magdau IB, Ackland GJ. Identification of high-pressure phases III and IV in hydrogen: simulating Raman spectra using molecular dynamics. Phys Rev B. 2013;87:174110]. [ABSTRACT FROM PUBLISHER]

This paper deals with the constitutive modelling of the ‘featureless’ region located on the Nickel side of a AISI8630/IN625 dissimilar weld interface. Fractography of failed weld interfaces show that cracks propagate in this carbides ()-rich region in the presence of hydrogen. In this paper, TEM images of the carbide-rich region are converted into a finite element mesh through an image-based mesh generation scheme. Simulations of the response of these structures show that in areas where the hydrogen content is high the matrix surrounding the carbides softens and plastic flow is localized. Moreover, the presence of hydrogen lowers the cohesive strength, giving rise to microcrack formation at the carbide-matrix interface. The amount of deformation then increases in a localized region adjacent to the region where (a) hydrogen content is high and (b) the carbide/matrix interface has debonded. As deformation proceeds the microcracks grow and link to form macrocracks, which generates the failure surface. [ABSTRACT FROM PUBLISHER]

The polymerization of 1-decene catalyzed by rac-Me2Si(1-indenyl)2ZrCl2/AliBu3/[C6H5NH(CH3)2][B(C6F5)4] system with hydrogen has been carried out in the paper. The influence of reaction conditions on catalytic activity and polymer properties was investigated. High activity (17.2 × 106g molZr−1h−1) was observed under the optimized reaction conditions. The introduction of hydrogen enhances the catalytic activity of the metallocene system. The1H NMR spectra revealed the polymerization mechanism with the presence of hydrogen. The13C NMR spectra of poly(1-decene) indicated that the polymer has a very tactic side chain structure, showing potential application of the system in the commercial production of lubricant base oil. [ABSTRACT FROM PUBLISHER]

Static compression is a well-known method to achieve very high pressures in ‘cold’ (degenerate) condensed matter. Because dynamic compression is adiabatic, it achieves both high pressures and temperatures, which are tunable by choice of pressure-pulse shape. Dynamic compression uses supersonic hydrodynamic variables, which are straight forward to measure, to achieve a wide range of extreme thermodynamic states in degenerate condensed matter. Because dynamic compression developed primarily in national laboratories, it is relatively unknown to a significant portion of the high pressure community. This paper is a brief review of (i) dynamic compression itself, (ii) its application to making metallic fluid H (MFH) and (iii) implications of data generated at extreme conditions with dynamic compression for understanding the unusual magnetic fields of Uranus and Neptune, which are made primarily by convection of semiconducting and MFH. Metallic hydrogen made under dynamic and static compression is compared. [ABSTRACT FROM PUBLISHER]

The liquid fuel gasification to obtain a clean flue gas for power generation and produce chemicals such as methanol is a most promising attempt to reduce the greenhouse gas emissions and air pollutants. In this paper, an equilibrium model of liquid fuel gasification was developed by the method of Gibbs free energy minimization. Two kinds of catalysts: Ni/CeO2/Al2O3and Ni/Al2O3were used to explore the influence of catalysts and operating conditions on hydrogen yield and char conversion. Over the ranges of operating conditions studied, the maximum hydrogen yield reached 52.47 vol%, whereas the char conversion varied between 45.2% and 98.5%. The results indicated that an appropriate reaction temperature is favorable for higher hydrogen production and char conversion. The model was validated with experimental data obtained from a fluidized bed gasifier. [ABSTRACT FROM PUBLISHER]

This paper deals with the modeling and simulation of air–steam gasification of coal using Aspen Plus process simulator. The model is able to predict the gas products, tar concentration, and char yield where the prediction accuracy of the presented model has been validated against the experimental measurements and found to be in a good agreement. The effect of coal particle size and minimum fluidization velocity (Umin) in air–steam gasification is explored through key operating parameters such as reaction temperature, equivalence ratio, and steam/coal ratio. Maximum hydrogen yield of 50.5 g/kg coal was obtained at a temperature of 650°C and steam/coal ratio of 0.7. Results were also showed that the particle size plays a key role in the process; smaller particles favor higher hydrogen yield. [ABSTRACT FROM PUBLISHER]

This paper has investigated the characteristics of structure and discharge for the MgO thin films grown by the ion plating process by varying the oxygen (O2) and hydrogen (H2) flow rates. The structural characteristics of the MgO film are measured by scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). The discharge characteristics are examined based on the firing voltage, secondary electron emission, sustain delay, and address delay. By increasing the O2flow rates during ion plating process, the grain sizes of the MgO thin films are decreased and the firing voltages are decreased, which would be due to the improvement of secondary electron emission characteristics. In addition, as the O2gas flow rates are increased in the range from 200 to 260 sccm, the sustain delay times are reduced, on the contrary, the address delay times are increased. Whereas, by increasing the H2flow rates, the grain sizes of the MgO thin films are increased. In particular, the lower firing voltages are measured at a H2flow rate of 40 sccm, which also would be due to an enhancement of secondary electron emission characteristics. When H2flow rates are increased from 0 to 40 sccm, the address delay times are greatly reduced. Whereas, when H2flow rates are beyond 40 sccm, the address delay times are slightly increased. However, the sustain delay times are slightly increased as the H2flow rates are increased from 0 to 60 sccm. Accordingly, the optimal control of both O2and H2 flow rates during the MgO film deposition using ion plating method can contribute to enhancing the discharge characteristics in ac plasma display panels (ac-PDPs). [ABSTRACT FROM PUBLISHER]

It has been demonstrated that hydrogen can selectively reduce hydroxyl and peroxynitrite in vitro. Since most of the ionizing radiation-induced cellular damage is caused by hydroxyl radicals, this study was designed to test the hypothesis that hydrogen may be an effective radioprotective agent. This paper demonstrates that treating cells with hydrogen before irradiation could significantly inhibit ionizing irradiation(IR)-induced Human Lymphocyte AHH-1 cells apoptosis and increase cells viability in vitro. This paper also shows that hydrogen can protect gastrointestinal endothelia from radiation-induced injury, decrease plasma malondialdehyde (MDA) intestinal 8-hydroxydeoxyguanosine (8-OHDG) levels and increase plasma endogenous antioxidants in vivo. It is suggested that hydrogen has a potential as an effective and safe radioprotective agent. [ABSTRACT FROM AUTHOR]

This paper reports an approach to the analysis of the local anharmonic states of motion and tunnelling of hydrogen illustrated with the molecule malonaldehyde. A potential energy function is used accurately to fit the local potential energy surface. The basis fitting functions in the potential resemble the Morse basis function, [image omitted], but are intrinsically Gaussian: [image omitted]. After rearrangement to isolate the Gaussian operators, the new form of the potential allows the direct use of mathematically friendly (Gaussian) manipulations that are needed to carry out the quantum mechanical analysis of the anharmonic features, namely tunnelling. The quantal analysis uses Cartesian harmonic oscillator basis functions together with the Talmi-Moshinsky-Smirnov methods to evaluate matrix elements of the potential energy operator. The longer term objective of this kind of work is to develop practical methods of hybrid analysis with which to treat the local atom dynamics associated with a reactive species while the rest of the dynamics are modelled as simple harmonic oscillators. The goal is eventually to have a computational theory of proton/hydrogen or small molecular group transfer reactions in condensed-phase systems. This paper addresses only the detailed local dynamical analysis. [ABSTRACT FROM AUTHOR]

The present paper considers a new approach to the case of an atom in an overdamped cavity. The dissipation is modelled via a bath of harmonic oscillators coupled to the cavity mode, which is assumed to be in a coherent state when the atom enters the cavity. The path integral over both the cavity mode and the bath is taken to derive the optically active electron's influence functional, which can be used further in the study of the time asymptotic dynamics of the internal states of any atom coupled with the cavity mode by using Monte Carlo methods. More specifically the present paper considers the dynamics of the ground state of hydrogen. Oscillations are observed in the survival probability of its ground state, which for asymptotic results is always smaller than one. [ABSTRACT FROM AUTHOR]

Fe-Ni alloy electrodeposition in a vacuum was carried out in this paper, and Fe-Ni alloy deposits was prepared on the stainless substrate based on the vacuum environment which could isolate oxygen, remove hydrogen and make the electrolyte boiling. The effects of the current density on the Fe content, the phase, the preferred orientation and the micro-hardness of the Fe-Ni alloy deposits prepared in the vacuum were analyzed by comparison with the traditional electrodepositing process. The results showed that the vacuum electrodeposition technique can significantly increase the Fe content and diffraction peak intensity of the alloy deposits. Simultaneously the vacuum electrodeposition can usually improve the micro-hardness of the electrodeposited Fe-Ni alloy. It has been proved that the microstructure and property of the deposit mentioned above were all influenced by the current density. [ABSTRACT FROM AUTHOR]

Crack networks and residual tensile stresses are general characteristics of electrodeposited hard chromium coatings. In this paper, crack-free hard chromium coatings with compressive stresses have been obtained by an electrodeposition process assisted by abrasive polishing. The deposited coatings had mirror-like smooth surfaces, values of hardness in the range 800–1000 HV and compressive stresses between 1000 and 1600 MPa. A model involving hydrogen disentanglement from the lattice is proposed to explain the effects of abrasive polishing on the complete elimination of cracks and the generation of a compressive stress. This explanation is discussed in terms of the variations in properties of the coating with the rotation speed of the cathode. [ABSTRACT FROM PUBLISHER]

Ultrasonic processing is known to be an efficient means of aluminium melt degassing with additional benefits of being economical and environment friendly. This paper describes the performance of ultrasonic degassing in preparing melt for low pressure die casting (LPDC). Efficiency of ultrasonic degassing is compared with conventional Ar rotary degassing by direct measurements of hydrogen concentration in the melt with a Foseco Alspek-H probe and by reduced pressure test in different stages of the casting process. Significant reduction in dross formation along with similar efficiency of hydrogen degassing was shown for ultrasonic degassing as compared with conventional Ar rotary degassing. Mechanical properties, microstructure and porosity level of the components produced by LPDC after both degassing techniques are determined. Results show that the components produced after ultrasonic degassing treatment have similar hardness, tensile properties, porosity level and microstructure as the components degassed with conventional Ar rotary degassing. [ABSTRACT FROM AUTHOR]

This paper presents an optimisation model for polymer electrolyte membrane fuel cell system based on simultaneous power maximisation and cost minimisation. The results show that, by employing appropriate relation between the objectives, the innovative design could be proposed. Genetic algorithm is applied to solve the optimisation problem. Power maximisation results reveal that at maximum amount of power (1.95 kW), unit cost of energy is $0.64. In contrast, minimisation of cost decreases unit cost of energy to $0.33. In this condition, output power is reduced approximately to 0.93 kW. To consider both optimisation problems concurrently, weighting method and Pareto set are employed. Our outcomes proposed that applying Pareto set to any optimisation problem leads to realistic decision-making. Eventually, sensitivity analysis is done on Pareto set, based on different Nafion membrane types and hydrogen cost variation. [ABSTRACT FROM AUTHOR]

In this study, experimental and numerical studies for the parameters optimising of the protective gas electroslag remelting in a three-phase electroslag furnace using the double electrode series technique have been carried out. The influence of the water vapour pressure in the atmosphere on the hydrogen content in metal molten pool was studied by the experiments, and a mathematical model was set up for the behaviour of hydrogen pick-up during electroslag remelting process. The realisable k − ε turbulence model, transport model and discrete ordinance (DO) radiation model were used to calculate the flow of gases in the furnace. The influence of argon gas flux on the air mole fraction in the furnace has been studied. Based on the experiment and numerical simulation, the inlet layout of shroud is optimised, to control the hydrogen content of ingots below 2 × 10−6 at the condition in this paper, the argon gas flux required should remain above 0·07 kg s−1. [ABSTRACT FROM AUTHOR]

Due to the surface diffusion movement of Si atom in hydrogen annealing process, the sharply formed corners of waveguides will be rounded and its sidewall profile could be reformed. In this paper, the performances of microring sensors based on three different gradual annealed structures, strip with large/small round corners and cylinder waveguide, are investigated theoretically. Characteristic parameters of sensors based on cylinder waveguide, sensitivity, Q factor, and measuring range are analyzed and compared with that of sensors based on the widely-used strip and slot waveguides. Simulation results demonstrate that the sensitivity of microring is significantly increased after annealing with comparable Q factor and measuring range. The hydrogen annealing process promises a feasible and effective method to improve the performance of biosensors in the future. [ABSTRACT FROM PUBLISHER]

In this paper, a numerical study of coupled heat and hydrogen transfer characteristics in an annular cylindrical hydrogen storage reactor filled with Mg2Ni is presented. An unsteady, two-dimensional (2-D) mathematical model of a metal hydride reaction bed of cylindrical configuration is developed for predicting the hydrogen storage capacity. The effect of volumetric radiation is accounted in the thermal model. Effects of hydride bed thickness, initial absorption temperature, hydride bed thermal conductivity, and hydrogen supply pressure on the hydrogen storage capacity are studied. A thinner hydride bed is found to enhance the hydriding rate, accomplishing a rapid reaction. At an operating condition of 20 bar supply pressure and 573 K initial absorption temperature, Mg2Ni stores about 36.7 g hydrogen per kg alloy. For a given bed thickness and an overall heat transfer coefficient, there exists an optimum value of hydride bed thermal conductivity. The present numerical results are compared with the experimental data reported in the literature, and good agreement was observed. [ABSTRACT FROM PUBLISHER]