Hydrogen Combustion Systems Research Articles

Nitrogen oxides removal from hydrogen flue gas using corona discharge in marine boilers: Application perspective

This paper focuses on the combustion of hydrogen in boilers, as it appears to be a more effective method than using fuel cells for heating purposes due to higher boiler efficiency. One of the main disadvantages of hydrogen combustion in air is NOx formation. Therefore, the authors decided to introduce corona discharge as an innovative technique to clean hydrogen flue gas by effectively reducing NOx levels. The method involves generating positive plasma at atmospheric pressure by applying up to a 23 kV voltage difference between rod and ring-shaped electrodes. Experimental studies have shown that corona discharge can significantly lower the concentrations of NO and NOx in exhaust gases. The maximum DeNOx level was found to be 32.3%, while the plasma generator uses 17.5% of the power contained in burned hydrogen. The findings suggest that this technology holds potential for application in industrial hydrogen combustion systems, offering an environmentally friendly alternative to conventional NOx reduction methods.

Hydrogen as a fuel for spark ignition combustion engines – state of knowledge and concept

Accelerating process of the transport and energy sectors increases the interest in fuels derived from renewable sources. The predicted three-fold increase in hydrogen production by 2050, driven by its falling production costs, justifies the direction of research aimed at its popularisation as a fuel for internal combustion engines (H2ICE). Presented article provides an overview of the state of knowledge on hydrogen combustion systems, which are currently the most attractive development path, mainly due to the well-developed production technology and relatively low recycling cost compared with fuel cells. The paper contains a comprehensive analysis of currently available solutions covering issues related to the production, storage, and transmission of hydrogen, with particular emphasis on the Polish market, which is one of the largest in Europe in terms of its production. The authors also propose their own concept of a hydrogen combustion system for application in an internal combustion engine. The presented solution is based on the idea of prechamber introduction in order to improve combustion process parameters and hence overall engine efficiency.

Community analysis of bifurcation maps of diluted hydrogen combustion in well stirred reactors

This article focuses on applying an automatic procedure for inspecting detailed kinetic mechanisms to predict key species/reactions playing a dominant role in the dynamic behaviour of regime transitions of combustion systems. We adopted a novel analysis method of kinetic mechanisms built by coupling the bifurcation analysis, which identifies the different regimes occurring with a change of the parameters, with algorithms typical of Artificial Intelligence, specifically the Community Analysis, which identifies within a large set of individuals (the chemical species) common behaviour patterns. Then we showed that this method is capable of automatically extracting meaningful information to identify the key species responsible for the dynamic behaviour and change of regimes observed in the solution maps of a combustion system. Application to a diluted hydrogen combustion system is illustrated as a first validation bench. It reveals that the recognition of state change is effective when based on proper indexes. On the full range of the parameter investigated, the inlet mixture temperature, when adopting an index correlated to the heat release rate, different community partitions were identified for each of the three regions with different dynamic behaviour. The most complex community partitions, with three communities, arise in the first two regions of lower temperature. The partition simplifies in the region of the higher parameter values where the system shows steady solutions without oscillations. The change in the link of atomic hydrogen, OH, and H2O2 with the remaining species is identified in the regime transitions.

A numerical investigation of deflagration propagation and transition to detonation in a microchannel with detailed chemistry: Effects of thermal boundary conditions and vitiation

We numerically investigate the premixed flame acceleration (FA) and the subsequent deflagration to detonation transition (DDT) of pure and vitiated fuel/oxidizer mixtures in a microchannel under two extreme wall thermal conditions—an adiabatic wall and a hot, preheated isothermal wall. The numerical simulations are conducted using AMReX-Combustion PeleC, an exascale compressible reacting flow solver that leverages load-balanced block-structured adaptive mesh refinement to enable high-fidelity direct numerical simulation. We perform these simulations for a hydrogen combustion system. While it is widely known that adiabatic walls strongly promote the occurrence of DDT via FA, such a mechanism of DDT is found to be strongly limited by the flame speeds of the unreacted mixture and hence is intrinsically tied to the mixture composition. We demonstrate that the addition of water (i.e., vitiation) to the unreacted mixture leads to a significant reduction in the flame speed, thereby slowing down the FA process and subsequent DDT. With isothermal preheated walls, the pure fuel cases preferentially propagate along the wall after an auto-ignition event, leading to the formation of a “secondary” finger-flame. This secondary front subsequently undergoes transverse expansion, following which deceleration of the flame is observed. The vitiated fuel cases also exhibit a similar behavior, nonetheless exhibit much longer time-scales of auto-ignition and propagation, in addition to stronger deceleration. In summary, this study presents one of the very few simulations in the FA and DDT literature that employ detailed chemical kinetics for both adiabatic and isothermal walls.

Compact and fast-response 150 kW hydrogen-oxygen steam generator

Burning of hydrogen produces high-grade heat, which can be used for zero-carbon power generation and/or heating and in heat-intensive industries. In combination with water electrolysis, hydrogen combustion provides efficient energy storage method for variable renewables. Hydrogen combustion systems are compact, powerful and highly maneuverable in comparison with fuel cells. We present experimental results of fire tests of a water-cooled hydrogen-oxygen steam generator (HOSG). This fast-response device has start-up time less than 15 s to thermal capacity of 147 kW. Temperature of generated steam is within 1173–1273 K, parameters of steam and energy conversion efficiency can be adjusted the water-to-hydrogen ratio. The maximum efficiency of conversion of chemical energy of hydrogen into enthalpy of steam is 98.7%.

Possible applications of prechambers in hydrogen internal combustion engines

The use of hydrogen as a fuel for an internal combustion engines has caused many problems for years, the most significant of which seems to be the excessive emission of nitrogen oxides and the tendency to knock combustion. In order to ensure better control of the combustion process in a internal combustion engine powered by hydrogen, it has been proposed to use a split combustion chamber solution. Following paper contains a description of a hydrogen combustion system that includes an analysis of possible technical solutions. The considerations take into account the issues of the dual nature of hydrogen knocking and the problem of burning a stratified charge of a hydrogen-air mixture in a cylinder.

Benchmarking the Performance of the ReaxFF Reactive Force Field on Hydrogen Combustion Systems.

A thorough understanding of the kinetics and dynamics of combusting mixtures is of considerable interest, especially in regimes beyond the reach of current experimental validation. The ReaxFF reactive force field method has provided a way to simulate large-scale systems of hydrogen combustion via a parametrized potential that can simulate bond breaking. This modeling approach has been applied to hydrogen combustion, as well as myriad other reactive chemical systems. In this work, we benchmark the performance of several common parametrizations of this potential against higher-level quantum mechanical (QM) approaches. We demonstrate instances where these parametrizations of the ReaxFF potential fail both quantitatively and qualitatively to describe reactive events relevant for hydrogen combustion systems.

HYDROGEN-OXYGEN STEAM GENERATOR FOR A CLOSED HYDROGEN COMBUSTION CYCLE

The paper analyzes the problems of combustion hydrogen in an oxygen medium for produce high-temperature steam that can be used to produce electricity at various power plants. For example, at the nuclear power plants, the use of a H2-O2 steam generator as part of a hydrogen energy complex makes it possible to increase its power and efficiency in the operational mode due to steam-hydrogen overheating of the main working fluid of a steam-turbine plant. In addition, the use of the hydrogen energy complex makes it possible to adapt the nuclear power plants to variable electric load schedules in conditions of increasing the share of nuclear power plants and to develop environmentally friendly technologies for the production of electricity. The paper considers a new solution of the problem of effective and safe use of hydrogen energy at NPPs with a hydrogen energy complex.Technical solutions for the combustion of hydrogen in the oxygen medium using direct injection of cooling water or steam in the combustion products have a significant drawback – the effect of “quenching” when injecting water or water vapor which leads to a decrease in the efficiency of recombination during cooling of combustion products that is expressed in an increase fraction of non-condensable gases. In this case, the supply of such a mixture to the steam cycle is unsafe, because this can lead to a dangerous increase in the concentration of unburned hydrogen in the flowing part of the steam turbine plant. In order to solve this problem, the authors have proposed a closed hydrogen cycle and a hydrogen vapor overheating system based on it, and carried out a study of a closed hydrogen combustion system which completely eliminates hydrogen from entering the working fluid of the steam cycle and ensures its complete oxidation due to some excess of circulating oxygen.The paper considers two types of hydrogen-oxygen combustion chambers for the system of safe generating of superheated steam using hydrogen in nuclear power plant cycle by using a closed system for burning hydrogen in an oxygen medium. As a result of mathematical modeling of combustion processes and heat and mass transfer, we have determined the required parameters of a hydrogen-oxygen steam generator taking into account the temperature regime of its operation, and a power range of hydrogen-oxygen steam generators with the proposed combustion chamber design.

N-dimensional switch function for energy conservation in multiprocess reaction dynamics.

The MReaDy program was designed for studying Multiprocess Reactive Dynamic systems, that is, complex chemical systems involving different and concurrent reactions. It builds a global potential energy surface integrating a variety of potential energy surfaces, each one of them representing an elementary reaction expected to play a role in the chemical process. For each elementary reaction, energy continuity problems may happen in the transition between potential energy surfaces due to differences in the functional form for each of the fragments, especially if built by different authors. A N-dimensional switch function is introduced in MReaDy in order to overcome such a problem. As an example, results of a collision trajectory calculation for H2 + OH → H3 O are presented, showing smooth transition in the potential energy, leading to conservation in the total energy. Calculations for a hydrogen combustion system from 1000 K up to 4000 K shows a variation of 0.012% when compared to the total energy of the system. © 2016 Wiley Periodicals, Inc.

Development and Testing of a Low NOx Hydrogen Combustion System for Heavy-Duty Gas Turbines

Interest in hydrogen as a primary fuel stream in heavy-duty gas turbine engines has increased as precombustion carbon capture and sequestration (CCS) has become a viable option for integrated gasification combined cycle (IGCC) power plants. The U.S. Department of Energy has funded the Advanced IGCC/Hydrogen Gas Turbine Program since 2005 with an aggressive plant-level NOx target of 2 ppm at 15% O2 for an advanced gas turbine cycle. Approaching this NOx level with highly reactive hydrogen fuel at the conditions required is a formidable challenge that requires novel combustion technology. This study begins by measuring entitlement NOx emissions from perfectly premixed combustion of the high-hydrogen fuels of interest. A new premixing fuel injector for high-hydrogen fuels was designed to balance reliable flashback-free operation, reasonable pressure drop, and low emissions. The concept relies on small-scale jet-in-crossflow mixing that is a departure from traditional swirl-based premixing concepts. Single nozzle rig experiments were conducted at pressures of 10 atm and 17 atm, with air preheat temperatures of about 650 K. With nitrogen-diluted hydrogen fuel, characteristic of carbon-free syngas, stable operation without flashback was conducted up to flame temperatures of approximately 1850 K. In addition to the effects of pressure, the impacts of nitrogen dilution levels and amounts of minor constituents in the fuel—carbon monoxide, carbon dioxide, and methane—on flame holding in the premixer are presented. The new fuel injector concept has been incorporated into a full-scale, multinozzle combustor can with an energy conversion rate of more than 10 MW at F-class conditions. The full-can testing was conducted at full gas turbine conditions and various fuel compositions of hydrogen, natural gas, and nitrogen. This combustion system has accumulated over 100 h of fired testing at full load with hydrogen comprising over 90% of the reactants by volume. NOx emissions (ppm) have been measured in the single digits with hydrogen-nitrogen fuel at target gas turbine pressure and temperatures. Results of the testing show that small-scale fuel-air mixing can deliver a reliable, low-NOx solution to hydrogen combustion in advanced gas turbines.

Study of the H + O + M reaction forming OH ∗: Kinetics of OH ∗ chemiluminescence in hydrogen combustion systems

The temporal variation of OH ∗ (A 2Σ +) chemiluminescence in hydrogen oxidation chemistry has been studied in a shock tube behind reflected shock waves at temperatures of 1400–3300 K and at a pressure of 1 bar. The aim of the present work is to obtain a validated reaction scheme to describe OH ∗ formation in the H 2/O 2 system. Temporal OH ∗ emission profiles and ignition delay times for lean and stoichiometric H 2/O 2 mixtures diluted in 97–98% argon were obtained from the shock-tube experiments. Based on a literature review for the hydrogen combustion system, the key reaction considered was H + O + M = OH ∗ + M (R1). The temperature dependence of the measured peak OH ∗ emission from the shock tube and the peak OH ∗ concentration from a homogeneous closed reactor model are compared. Based on these results a reaction rate coefficient of k 1 = (1.5 ± 0.4) × 10 13 exp(−25 kJ mol −1/ RT) cm 6 mol −2 s −1 was found for the forward reaction (R1) which is slightly higher than the rate coefficient suggested by Hidaka et al. (1982). The comparison of measured and simulated absolute concentrations shows good agreement. Additionally, a one-dimensional laminar premixed low-pressure flame calculation was performed for where absolute OH ∗ concentration measurements have been reported by Smith et al. (2005). The absolute peak OH ∗ concentration is fairly well reproduced if the above mentioned rate coefficient is used in the simulation.

309 化学動力学を用いた水素自着火反応の計算(OS-1 着火・燃焼解析,噴流解析,研究発表講演)

For finding the optimal design and operating condition in the hydrogen combustion system, it is necessary to consider the spontaneous-ignition characteristics. In this study, detailed chemical kinetics were applied to calculate the ignition processes of the stoichiometric hydrogen mixture, Explosion limits were well predicted under consideration of the adequate heat-loss. Based on the results, the ignition mechanism and the effect of heating rate on the ignition temperature were discussed.

Investigation of the correlation of sensitivity vectors of hydrogen combustion models

AbstractA well‐established method for the analysis of large reaction mechanisms is the calculation and interpretation of the sensitivity of the kinetic model output Yi to parameter changes. Comparison of the sensitivity vectors si = {∂ Yi/∂p} belonging to different model outputs is a new tool for kinetic analysis. The relationship of the sensitivity vectors was investigated in homogeneous explosions, freely propagating and burner‐stabilized laminar flames of hydrogen–air mixtures, using either calculated adiabatic or constrained temperature profiles, for fuel‐to‐air ratios φ = 0.5–4.0. Sensitivity vectors are called locally similar, if the relationship si = λijsj is valid, where λij is a scalar. In many systems, only approximate local similarity of the sensitivity vectors exists and the extent of it can be quantified by using an appropriate correlation function. In the cases of adiabatic explosions and burner‐stabilized flames, accurate local similarity was present in wide ranges of the independent variable (time or distance), and the correlation function indicated that the local similarity was not valid near the concentration extremes of the corresponding species. The regions of poor similarity were studied further by cobweb plots. The correlation relationships found could be interpreted by the various kinetic processes in the hydrogen combustion systems. The sensitivity vector of the laminar flame velocity is usually considered to be characteristic for the whole combustion process. Our investigations showed that the flame velocity sensitivity vector has good correlation with the H and H2O concentration sensitivities at the front of the adiabatic flames, but there is poor correlation with the sensitivity vectors of all concentrations in homogeneous explosions. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 238–252 2004

Theoretical performance evaluation of hydrogen flames

Theoretical performance evaluations of hydrogen-oxygen and hydrogen-air flames under general conditions were performed in this paper, based on the method of minimization of Gibbs free energy. Some important factors influencing the flame performance were investigated and a set of characteristic curves was presented. Several conclusion were drawn. The results obtained may be useful for the primary evaluation and performance prediction of some practical hydrogen combustion systems.

Hydrogen energy systems technology study

The National Aeronautics and Space Administration (NASA) Office of Energy Programs initiated the Hydrogen Energy Systems Technology (HEST) Study in the autumn of 1974. The Caltech Jet Propulsion Laboratory (JPL) was made responsible for conducting the study and reporting the results, with active support from several NASA Centres through a Working Panel. Objectives of the study were defined to be the assessment of national needs for hydrogen, based on current uses and visible trends, and determination of the critical research and technology activities required to meet these needs, with attention to economic, social, and environmental considerations, providing a basis for the planning of a hydrogen research and technology program. The HEST Study found current U.S. hydrogen utilization to be dominated by chemical-industry and petroleum-processing applications, and to represent 3% of total energy consumption. The study's projections of hydrogen uses show growth the remainder of this century by at least a factor of five, and perhaps a factor of twenty. New applications in the manufacture of synthetic fuels from coal and directly as an energy storage medium and fuel are expected to emerge later this century. Of these new uses, electric utility energy storage for peak-shaving, supplements to the natural gas supply and special purpose transportation fuel such as aircraft, show promise. The Study concludes that the development and implementation of new means of supplying hydrogen, replacing the use of natural gas and petroleum feedstocks, are imperative. New production technology is essential to support even the lowest growth estimate. Methods based on alternative fossil feedstocks, such as coal and heavy oils, which are less expensive and nearer to technical maturity than non-fossil production systems, should be made operational while these feedstocks are abundant. Concurrently, the long-term tasks of advancing electrolysis technology, researching other water-splitting techniques, and integrating these with developing nuclear and emerging solar primary-energy systems, must be carried on, together with work on hydrogen combustion systems and research in materials and safety engineering. Systems studies and assessments of the economic, social and environmental impacts of hydrogen technology are also called for.