Mixture Of Hydrogen Research Articles

Prospects of membrane catalysis in hydrogen energetics. Mini review

Hydrogen energetics is undoubtedly highly relevant today as it not only allows solving the issue of energy production from a renewable water source but can also prevent the formation of greenhouse gases. They say that any new idea is a well forgotten old one. The paper is dedicated to an excellent but still unimplemented work of Sainte-Claire Deville who managed to obtain hydrogen from water vapor using membrane technology. He used a clay pipe as a membrane which selectively permeated hydrogen. This process occurred with heating up to 950 °C. Sainte-Claire Deville managed to obtain only a mixture of hydrogen and oxygen in a ratio of 4:1 and then to clean the product from oxygen using chemical reactions. Modern membrane catalysts based on palladium or its alloys are selectively permeable only for hydrogen. This means that the membrane catalysis method with palladium membranes could allow to realize of hermal water disassociation more effectively and solve the issues of hydrogen energetics using only renewable raw materials. The history of hydrogen discovery and methods of its production was also studied in this review. Different methods of energy production were analyzed, including mineral resources, wind turbines, solar panels, hydroenergetics, electrolysis, and nuclear power, and a forecast was presented based on them. The review should be considered as an invitation to further discussions regarding this highly relevant and important topic

SRS conversion efficiency assessment of a single cell Raman gas mixture for DIAL ozone lidar.

A single Raman cell configuration useful for DIAL ozone lidar is designed and optimized. The conversion efficiency and flexibility of using a single Raman cell filled with a mixture of high pressure Raman active gases hydrogen (H 2) and methane (C H 4) have been examined and reported. The stimulated Raman scattering (SRS) conversion efficiency of Raman active gases with different total cell pressures and the volume mixing ratio excited with a focused, frequency quadrupled Nd:YAG laser with a maximum pulse energy of 25mJ and a pulse duration of 10ns at 100Hz repetition rate are examined in detail. The gas combination of H 2:C H 4 emits a coaxial beam of two wavelengths, 288.4nm (C H 4) and 299.1nm (H 2), with a maximum total conversion efficiency of about 45%. The optimum volume mixing ratio for generating the required wavelength pair with almost equal energies is found to be 2:1 (H 2:C H 4) at a total cell pressure of 18bar. The contribution of cascade Raman scattering (CRS) and four-wave mixing (FWM) to the higher order Stokes lines is examined. The laser attenuation due to soot formation under various mixing ratios in the cell is also presented.

Quantitative assessment of small-bore gasoline direct injection engine for homogenous stoichiometric lean condition with hydrogen addition in dual fuel mode

The global hunt for the sustainable fuel for the energy and transportation has reached the newer dimensions. The advancement in the engine technology makes the viable solution to fit the hydrogen as the working fuel for both CI and SI engines. The physio-chemical chemical properties of hydrogen have the apt fitment for the SI engine. With the advancement in the automotive electronics and precision control of the fuel handling system makes hydrogen a workable option for the replacement for the conventional fuels. In this research hydrogen was inducted into the intake manifold and Gasoline is injected directly into the cylinder of the small-bore Gasoline Direct Injection (GDI) Engine at wide open throttle condition. The intake manifold is slightly modified to accommodate the hydrogen induction system (0–8 Litres Per Minute), where premixed mixture of hydrogen and air is formed in the intake manifold; the equivalence ratio of 1.0, 1.02 and 1.08 was set for the given hydrogen induction. The engine conditions were set as 3000 rpm with five hydrogen addition fractions of 0 %, 1.5 %, 2.8 %, 4.2 % and 5.8 % respectively. The hydrogen induction improves the combustion rate and mean effective pressure; shorten the flame propagation, maximize the heat release rate and peak pressure attainment. Maximum of 16 % increase in the peak pressure is attained for the λ = 1 for the 5.8 % hydrogen addition fraction. On the emission side, consistent decrease in CO and HC emission; and increase of NO emission, since the mean gas temperature has increased.

Ammonia combustion using hydrogen jet ignition (AHJI) in internal combustion engines

The application of ammonia and hydrogen in internal combustion engines (ICE) is a promising zero-carbon technology. This paper investigates ammonia combustion in ICE using hydrogen multiple-injection jet-ignition (MIJI). The experiment was conducted on a single-cylinder heavy-duty engine with a compression ratio of 17 and a cylinder bore of 123 mm. In the passive jet ignition mode, the minimum hydrogen energy ratio for stable operation of the ammonia-hydrogen engine was 15 %. Using H2 active jet ignition could improve the combustion stability significantly. It was found that engine performance was gradually improved by H2 injection strategy in order of single-injection, double-injection to triple-injection. The triple-injection strategy could achieve a more ideal distribution of ammonia-hydrogen mixture: the first injection forms a homogeneous mixture to increase fuel reactivity; the second injection creates a stratified hydrogen mixture, facilitating rapid flame propagation; the third injection forms a relatively rich mixture in the jet chamber conducive to spark ignition. Through the optimization of the hydrogen injection strategy and spark timing, stable combustion (COV = 1 %) and high thermal efficiency (ITE = 42.5 %) in ammonia-hydrogen engines were achieved, with a minimum hydrogen energy ratio less than 3 %.

Tar Formation in Gasification Systems: A Holistic Review of Remediation Approaches and Removal Methods.

Gasification is an advanced thermochemical process that converts carbonaceous feedstock into syngas, a mixture of hydrogen, carbon monoxide, and other gases. However, the presence of tar in syngas, which is composed of higher molecular weight aromatic hydrocarbons, poses significant challenges for the downstream utilization of syngas. This Review offers a comprehensive overview of tar from gasification, encompassing gasifier chemistry and configuration that notably impact tar formation during gasification. It explores the concentration and composition of tar in the syngas and the purity of syngas required for the applications. Various tar removal methods are discussed, including mechanical, chemical/catalytic, and plasma technologies. The Review provides insights into the strengths, limitations, and challenges associated with each tar removal method. It also highlights the importance of integrating multiple techniques to enhance the tar removal efficiency and syngas quality. The selection of an appropriate tar removal strategy depends on factors such as tar composition, gasifier operating and design factors, economic considerations, and the extent of purity required at the downstream application. Future research should focus on developing cleaning strategies that consume less energy and cause a smaller environmental impact.

Mixture of hydrogen and methane under planetary interior conditions.

We employ first-principles molecular dynamics simulations to provide equation-of-state data, pair distribution functions (PDFs), diffusion coefficients, and band gaps of a mixture of hydrogen and methane under planetary interior conditions as relevant for Uranus, Neptune, and similar icy exoplanets. We test the linear mixing approximation, which is fulfilled within a few percent for the chosen P-T conditions. Evaluation of the PDFs reveals that methane molecules dissociate into carbon clusters and free hydrogen atoms at temperatures greater than 3000 K. At high temperatures, the clusters are found to be short-lived. Furthermore, we calculate the electrical conductivity from which we derive the non-metal-to-metal transition region of the mixture. We also calculate the electrical conductivity along the P-T profile of Uranus [N. Nettelmann et al., Planet. Space Sci., 2013, 77, 143-151] and observe the transition of the mixture from a molecular to an atomic fluid as a function of the radius of the planet. The density and temperature ranges chosen in our study can be achieved using dynamic shock compression experiments and seek to aid such future experiments. Our work also provides a relevant data set for a better understanding of the interior, evolution, luminosity, and magnetic field of the ice giants in our solar system and beyond.

Highlighting cross section library effects on absorption rates and flux for natural elements in a thermal spectrum using TRIPOLI-5

This work presents an investigation of cross section library effects with the new TRIPOLI-5 Monte Carlo code, a joint project between CEA, IRSN and EDF in France. Cross section library effects on the absorption rate and the flux spectrum were highlighted for natural elements subjected to a thermal neutron flux. The numerical benchmark that is presented here is a sphere with a radius of 30 cm filled with 10−2 atoms·(barn·cm)−1 of a single element according to its natural isotopic abundances. For the thermal flux case, a smaller sphere with a radius of 1 cm is placed at the center of the main sphere to obtain a thermal-like flux from a pointwise Maxwellian source using a mixture of hydrogen and boron-10. A total of 12 cross sections libraries have been compared.

Source of High-Efficiency Radiation in the Lyman and Werner Bands of a Pulse Discharge in Mixtures of Hydrogen and Helium

Source of High-Efficiency Radiation in the Lyman and Werner Bands of a Pulse Discharge in Mixtures of Hydrogen and Helium

Recent advances in bifunctional synthesis gas conversion to chemicals and fuels with a comparison to monofunctional processes.

In order to meet the climate goals of the Paris Agreement and limit the potentially catastrophic consequences of climate change, we must move away from the use of fossil feedstocks for the production of chemicals and fuels. The conversion of synthesis gas (a mixture of hydrogen, carbon monoxide and/or carbon dioxide) can contribute to this. Several reactions allow to convert synthesis gas to oxygenates (such as methanol), olefins or waxes. In a consecutive step, these products can be further converted into chemicals, such as dimethyl ether, short olefins, or aromatics. Alternatively, fuels like gasoline, diesel, or kerosene can be produced. These two different steps can be combined using bifunctional catalysis for direct conversion of synthesis gas to chemicals and fuels. The synergistic effects of combining two different catalysts are discussed in terms of activity and selectivity and compared to processes based on consecutive reaction with single conversion steps. We found that bifunctional catalysis can be a strong tool for the highly selective production of dimethyl ether and gasoline with high octane numbers. In terms of selectivity bifunctional catalysis for short olefins or aromatics struggles to compete with processes consisting of single catalytic conversion steps.

Highly diverse-Low abundance methanogenic communities in hypersaline microbial mats of Guerrero Negro B.C.S., assessed through microcosm experiments.

Methanogenic communities of hypersaline microbial mats of Guerrero Negro, Baja California Sur, Mexico, have been recognized to be dominated by methylotrophic methanogens. However, recent studies of environmental samples have evidenced the presence of hydrogenotrophic and methyl-reducing methanogenic members, although at low relative abundances. Physical and geochemical conditions that stimulate the development of these groups in hypersaline environments, remains elusive. Thus, in this study the taxonomic diversity of methanogenic archaea of two sites of Exportadora de Sal S.A was assessed by mcrA gene high throughput sequencing from microcosm experiments with different substrates (both competitive and non-competitive). Results confirmed the dominance of the order Methanosarcinales in all treatments, but an increase in the abundance of Methanomassiliiccocales was also observed, mainly in the treatment without substrate addition. Moreover, incubations supplemented with hydrogen and carbon dioxide, as well as the mixture of hydrogen, carbon dioxide and trimethylamine, managed to stimulate the richness and abundance of other than Methanosarcinales methanogenic archaea. Several OTUs that were not assigned to known methanogens resulted phylogenetically distributed into at least nine orders. Environmental samples revealed a wide diversity of methanogenic archaea of low relative abundance that had not been previously reported for this environment, suggesting that the importance and diversity of methanogens in hypersaline ecosystems may have been overlooked. This work also provided insights into how different taxonomic groups responded to the evaluated incubation conditions.

Virtual experiments about hydrogen explosions with linear propagation

The dangers associated with hydrogen mainly come from its wide flammability range, it’s extremely fast burning rate (having much more aggressive explosive properties than methane gas) and the considerable amount of energy released when it burns or explode. The development of new applications that use hydrogen as clean energy is constantly increasing, thus, hydrogen can be used on a large scale. This paper presents the use of computational fluid dynamics techniques, regarding the linear propagation of the explosion of air and hydrogen mixture in closed spaces, the main purpose being the determination of the overpressures to which a test stand of this processes is subjected.

Measurement of Laminar Burning Speed of Methane/Hydrogen/Air Mixtures at High Pressures and Temperatures

Abstract Green hydrogen which could be produced from renewable sources by solar water splitting or photovoltaic electrolysis will play an important role in achieving net-zero in the near future. One possible approach will be to mix hydrogen with natural gas for power generation in gas turbine systems. It is necessary to know the physical properties of burning speed of the mixture of natural gas and hydrogen. Since natural gas is mainly made up of methane, the burning speed of mixtures of methane and hydrogen has been measured and reported in this paper. Adding hydrogen gas during the combustion of methane enhances flame stability, expands the lean flammability range, decreases pollutant emissions, and boosts the burning speed. Burning speed measurement is performed in a cylindrical and spherical chamber. The pressure rise due to combustion was measured by a pressure transducer on the top of cylindrical and spherical chambers. The Z-shaped Schlieren system, equipped with a high-speed complementary metal oxide semiconductor (CMOS) camera, obtains pictures of flame propagation. Laminar burning speed is measured exclusively for flames that have a smooth and spherical shape. In addition, burning speed is only measured for large flame radii with low stretch rates. Burning speed is calculated by a thermodynamic model with the pressure rise data as an input. Measurements cover a wide range of operating conditions. The hydrogen mole fraction is 0%, 20%, and 40%, with temperatures of 298–400 K, pressures between 0.5 and 5.5 atmospheres and equivalence ratios of 0.8, 1, and 1.2.

Charging/Refueling Navigation Strategies for Plug-in Hybrid Hydrogen and Electric Vehicles With Irrationalities and Energy Substitution

Electric vehicles (EVs) are believed to be effective in reducing the use of fossil fuels. However, the increasing penetration of EVs can lead to challenges in managing EV charging/refueling. Typically, when EVs simultaneously gather at the stations, long queueing lengths and waiting times might occur, which might result in EV disutility. Thus, in this paper, novel decision-making strategies considering the irrational behaviors of EVs are formulated to ensure the utility of EVs. Three types of EVs are investigated, i.e., plug-in electric vehicles (PEVs), fuel cell electric vehicles (FCEVs), and plug-in hybrid hydrogen and electric vehicles (PH2EVs). First, three typical types of irrationalities are modeled based on prospect theory and irrational herding theory, including risk attitude irrationality, probability distortion, and irrational herding behaviors. Second, decision-making strategies, including station selection, navigation, and energy purchasing, are modeled based on EV irrationalities. Additionally, when making the station selection decision, the selection ranking index is proposed to balance energy price and waiting time. Third, the energy substitution of PH2EV is investigated to determine the optimal energy-purchasing mixture of electricity and hydrogen. Simulation results show that the average waiting time and charging/refueling time of EV users of the proposed model are reduced compared with the other two cases where EV users are assumed to be rational. In addition, the overall utility of EV users is enhanced.

Features of ignition of mixtures of hydrogen with hydrocarbons (C2, C3 and C5) over rhodium and palladium at pressures of 1–2 atm

It was found that the reactivity of a hydrocarbon during oxidation catalyzed by a noble metal begins to play a significant role with an increase in the number of carbon atoms in its molecule. Thus, the process of hydrocarbon mass transfer to (or on) the catalyst surface determines the oxidation rate.

Energy, Exergy & Environmental Analysis of a Combined Cycle with Pre-combustion CO2 Capture and N2 Injected into the Compressor of the Gas Turbine

Power plants are a major source of CO2 emissions in the environment, which cause global warming; due to this issue, CO2 capture from hydrocarbon fuels is one of the key technology options to reduce greenhouse gases. Pre-combustion capture of CO2 in the combined gas and steam turbine cycle has been investigated in this paper. The first step in the pre-combustion method is to react the fuel with oxygen, which comes from the air separation unit and produces a mixture of hydrogen and carbon monoxide. The CO is converted to CO2 in a water-shift reactor, and a physical absorbent removes the CO2; a hydrogen-rich fuel is produced, which can be burnt in a gas turbine with minimal CO2 emissions. This paper presents a thermodynamic cycle analysis, where pre-combustion CO2 capture is applied in a combined cycle where the main goal is to reduce the CO2 emission into the atmosphere. The main parameters are varied to examine the influence on cycle performance. The cycle performance results for the combined cycle with CH4 as fuel are presented and compared to the combined cycle with precombustion CO2 capture, both with and without Nitrogen injection into the compressor. An exergy analysis is carried out to determine which case has more exergy destruction. The results indicate that at 45 oC the combined cycle efficiency is raised by around 3 % when the pre-combustion CO2 capture without Nitrogen injection into the compressor is used, and the power output has been increased by 29 %. The performance of combined cycle with CO2 capture can be further enhanced by the N2 acquired from the air separation process and injected into the compressor’s middle stage. The results demonstrate a good improvement in the performance; the power output increases by 48 % and efficiency by 4.2 %. However, exergy destruction is increased when the CO2 capture, both with and without N2 injection into the compressor is used. Nevertheless, pre-combustion capture requires large monetary investment for a new-build plant where also the CO2 emission is reduced by 100 %.

Non-noble metal catalysts for dry reforming of methane: Challenges, opportunities, and future directions

The utilization of non-noble metal catalysts for the dry reforming of methane (DRM) has gained significant attention in recent years due to the increasing demand for clean and sustainable energy sources. DRM involves the conversion of methane (CH4) and carbon (IV) oxide (CO2) into synthesis gas (syngas), a valuable mixture of hydrogen (H2) and carbon monoxide (CO). Commercialization of non-noble metal catalysts for this reaction presents several challenges that must be addressed to achieve practical implementation. This short review discusses the challenges, opportunities, and future directions of non-noble metal catalysts for DRM. First, the limitations associated with the intrinsic activity and stability of non-noble metals, such as nickel, cobalt, and iron, are explored. Enhancing catalyst performance through compositional modifications, the incorporation of promoters and supports, are ways to overcome these challenges. Directions that hold promise for advancing non-noble metal catalysts in DRM, including the advanced exploration of bimetallic catalysts for synergistic effects, and the integration of non-noble metals into novel catalytic systems, were among the future proposals, while non-noble metal catalysts have the potential to revolutionize the production of syngas and contribute significantly to the transition towards sustainable energy solutions.

Issues and challenges of Fischer-Tropsch synthesis catalysts.

Depletion of oil and gas resources is a major concern for researchers and the global community. Researchers are trying to develop a way to overcome these issues using the Fischer-Tropsch synthesis (FTS) process. The FTS reaction converts a mixture of hydrogen and carbon monoxide gases into a liquid fuel. The reactions are performed in the reactor and in the presence of a catalyst. A series of catalysts, such as iron, cobalt, nickel, and ruthenium, have been used for the FTS process. In iron-based catalysts, the Fe5C phase is the active phase that produces C5+ hydrocarbons. At higher conversion rates, the presence of water in the products is a problem for cobalt catalysts because it can trigger catalyst deactivation mechanisms. Ni-based catalysts play key roles as base catalysts, promoters, and photothermal catalysts in FTS reactions to produce different useful hydrocarbons. Ruthenium catalysts offer not only high activity but also selectivity toward long-chain hydrocarbons. Moreover, depending on the Ru particle size and interaction with the oxide support, the catalyst properties can be tuned to enhance the catalytic activity during FTS. The detailed reaction pathways based on catalyst properties are explained in this article. This review article describes the issues and challenges associated with catalysts used for the FTS process.

Numerical study on the reinitiation mechanism of detonation propagating through double slits in a planar channel

In this study, numerical simulations were performed to investigate the reinitiation of diffracted detonation waves through a double-slit-plate. A planar detonation wave was set to propagate through a channel of a height of 50 mm filled with the stoichiometric mixture of hydrogen and oxygen at 20 kPa. Several slit-plates with different slit widths and slit spacing were considered to explore the effects of slit geometry on reinitiation and its underlying mechanisms. For this, two-dimensional multi-species reactive Navier–Stokes equations were solved using a finite volume solver. The results revealed that upon diffraction, the detonation waves become decoupled and subsequently exhibit one of three distinct phenomena depending on the specific slit geometry. These phenomena include reinitiation by shock–shock interaction (RSSI), reinitiation by shock-wall interaction (RSWI), and complete suppression. It was found that a residual transverse wave is crucial in generating a detonation kernel. In cases where this residual transverse wave is absent, the detonation kernel fails to develop. As a result, only complete suppression of the detonation wave was observed. The narrow slit widths effectively suppress residual transverse waves through the steep expansion that occurs as the detonation front passes through the slit. Moreover, larger slit spacing resulted in further expansion of the shock front before the collision, due to the increased time delay for the shock waves to intersect. As a result, it was found that a larger slit spacing is unfavorable for the formation of a detonation kernel. Yet, in this regard, it is important to note that the onset of RSSI was not guaranteed even with a detonation kernel. Rather, the onset of RSSI was highly dependent on the curvature of the main detonation trajectory. RSSI was inhibited in cases where the forward propagating detonation wave experienced significant expansion due to the large curvature of the main detonation wave trajectory. Smaller slit spacing was found to be particularly unfavorable for RSSI as they exhibit more divergent curves. Overall, this study illustrates that the reinitiation mechanisms of detonation show two different pathways in the transition to detonation from decoupled shock waves and reaction fronts upon diffraction propagating through double slit configurations, and enhances understanding of RSSI by providing insights into the complex interplay between slit geometry, detonation kernel formation, and curvature of detonation wave based on highly-resolved numerical simulations using detailed chemistry. The findings from this study have implications towards the design and optimization of systems involving detonation propagation and suppression.Novelty and significanceThis study focuses on the reinitiation mechanism of detonation propagating through double slits in a planar channel. Specifically, this numerical study aims to understand the critical behaviors that occur when the slit width and the cell width of the detonation are comparable, based on the previously reported experiment. Reinitiation by shock–shock interaction which had previously been limited in understanding was explained in detail and the effects of slit geometry were examined. It is worth noting that there is a lack of in-depth explanations in the literature regarding the double slit configuration with various dimensions of slit-plates. Moreover, this investigation deals with smaller scales of slit width compared to the well-known critical length scale of a planar channel which is about ten times of cell width. As a result, the findings of this study offer further insights for optimizing the design of detonation arrestors.

Roles of hydrogen in shielding gas for compensate heat input on dissimilar joints of stainless steel series 200 between AISI 201LN and 214 by GTAW

Austenitic stainless steel type 200 series was developed for indoor work due to being inexpensive. It is useful for reducing production costs. In this present work, the roles of hydrogen in shielding gas for compensate heat input on dissimilar joints of stainless steel series 200 between AISI 201LN and 214 by GTAW process was investigated. The technique used in this study applied an hydrogen mixture in argon shielding gas to compensate for the depleted heat input when increasing welding speed at an acceptable maximum of 5% H + 95% Ar at a welding speed of 6 mm/sec. The results of this study are evaluated for the following aspects: weld bead shape completely melted together without filler metal and non-defect. Microstructure combine between the delta-ferrite and austenite matrix under FA solidification mode which delta-ferrite decreasing trend when increase welding speed paired with add hydrogen in argon. In addition, it was discovered that the chemical composition of base metal high move to low concentrated. While the micro-hardness has an upward according to the amount of increase hydrogen same as the tensile strength properties and percentage elongation. While the micro-hardness has an upward according to the amount of increase hydrogen same as the tensile strength properties and percentage elongation. The fracture of tensile occur adjacent to side 201LN. The pitting corrosion resistance depend on volume of delta-ferrite phase and initial pitted between delta-ferrite and austenite.

Study of soot microscopic characteristics in hydrogen/methane/ethylene co-flow diffusion flame

Hydrogen (H2) has been regarded as a highly competitive alternative fuel that does not produce CO2 and soot during combustion. However, the effect of hydrogen addition on soot formation and emission is questionable. The purpose of this paper is to study the influence of hydrogen/methane on the morphology of soot and the evolution of nanoparticle structure in laminar flame of ethylene. In this study, the soot morphology and nanostructure in H2/CH4/C2H4 laminar co-flow diffusion flames were investigated with thermophoretic sampling and high-resolution transmission electron microscopy (HRTEM). The results showed that the average primary particle diameters (Dp) of pure ethylene flame gradually decreased along the flame height direction, showing the competition between soot surface growth and soot oxidation. When the hydrogen is added into the fuel flow of ethylene, the Dp decrease at most sample points. Methane affects the inhibitory effect of hydrogen doping on soot, and with the increase of methane mixing ratio, the change trend of Dp of each hydrogen mixture with flame height is becoming more and more consistent. The nanostructure analysis showed that hydrogen doping made soot particles shorter, more tortuous and denser fringes. There is a synergistic effect to promote the growth of primary soot particles at low methane ratio, but it disappears after mixing 20 % hydrogen. The fringe length and tortuosity of soot particles gradually increase with the methane ratio.