Hydrogen Injection Research Articles

Numerical Investigation of flow and combustion process in a hydrogen direction injection rotary engine

The high power-to-weight ratio and zero carbon emission hydrogen rotary engine (HRE) is an attractive development direction of hydrogen-powered systems, which is of great significance in expanding the hydrogen energy diversified utilization and promoting greenhouse gas (GHG) emission reduction. In this paper, a direct injection HRE simulation model coupling chemical reaction kinetics is constructed. The flow and combustion processes are visually presented using computational fluid dynamics (CFD) means, and the effect of the air intake method and hydrogen injection timing on the mixture formation and combustion performance are analyzed. Research finds that the combustion pressure, peak pressure, indicated work and indicated power of the HRE are larger when using methods of the compound or side intake or delaying hydrogen injection strategy. Due to the forward flame propagation characteristics, the combustion process mainly occurs in the front part of the combustion chamber, and the mixture distribution in this area and aggregation near the ignition chamber are more favorable to improving the combustion performance. More gas fuel gathered in the leading or end regions of the chamber will affect the burn rate in the later combustion stage. The preferred scheme is compound AIM with HIT at the early compression stage (CAIM-190), and its peak pressure, indicated work and indicated power improve by 30.9%, 25.5% and 26.6% respectively while combustion duration shortens by 15.3% when comparing to the scheme of minimum peak pressure (PAIM-286). This study can offers basic data to promote the HRE achieving efficient combustion and zero carbon emissions.

Effects of cushion gas pressure and operating parameters on the capacity of hydrogen storage in lined rock caverns (LRC)

Hydrogen storage in lined rock cavern (LRC) provides versatile site selection, safety, and stability, making it a crucial option. In this study, a thermodynamic mathematical model was established to describe hydrogen storage in LRC. This model is based on the principles of mass, momentum, and energy conservation while accounting for the authentic compressibility of hydrogen. The thermodynamic fluctuations throughout the seasonal cycle in LRC were computed using the COMSOL Multiphysics software. The results indicate that when the hydrogen storage reaches the operating pressure, the lower the cushion gas pressure, the greater the hydrogen injection amount, and the higher the utilization rate of storage capacity. With a cushion gas pressure of 3 MPa, the storage capacity utilization rate exceeds that at 15 MPa by 41 %. The injection rate of 0.5 kg/s results in a temperature increase of 12 °C compared to 0.27 kg/s, indicating twice the temperature rise at the 0.27 kg/s injection rate. An increase in injection temperature corresponds to higher temperature within the hydrogen storage cavern upon completion of gas injection, thereby reducing the time needed for gas injection to reach maximum operating pressure. A lower initial cavern temperature results in a longer time for hydrogen storage to reach maximum operating pressure.

Analysis of Leakage and Diffusion Characteristics and Hazard Range Determination of Buried Hydrogen-Blended Natural Gas Pipeline Based on CFD.

Injecting hydrogen into natural gas pipelines is an economical and efficient method of hydrogen transportation. However, the addition of hydrogen leads to significant hydrogen corrosion and embrittlement in the pipelines, especially in harsh and concealed underground conditions, where leak accidents are frequent and difficult to detect. This Article uses Le Chatelier's Principle to determine the hazardous range of hydrogen-blended natural gas (HBNG) by employing numerical simulation, it examines the gas leakage and diffusion characteristics before and after hydrogen injection as well as under different hydrogen blending ratio (HBR). Additionally, considering the density of the mixed gas, a prediction model for the diffusion hazard range of hydrogen-mixed natural gas is established based on multivariate regression theory. The results show that after a leakage occurs in HBNG the diffusion range in soil is wider compared to methane, with higher corresponding pressure and velocity values. Moreover, as the HBR increases, the farthest danger range (FDR) of the HBNG also increases. When the leakage of the buried HBNG pipeline occurs for 1 min, the difference in FDR between HBR 25% and HBR 5% is 0.005 m. After 30 min, this difference increases to 0.019 m, indicating that with longer leakage duration, the potential explosion risk resulting from increased HBR becomes greater. Factors such as pipeline pressure increase, larger leak hole size, and decreased burial depth all contribute to an increase in FDR, with pipeline pressure change having the greatest impact and burial depth change having the smallest impact. The maximum error of the predicted model for the diffusion hazard range of hydrogen-mixed natural gas is 9.385%, and the average error is 2.376%, demonstrating the accuracy of the prediction results. This study provides guidance for monitoring underground hydrogen-blended natural gas pipeline leaks, offers a basis for determining the repair range of pipelines, and ensures the safe transportation of hydrogen-mixed natural gas pipelines.

Optimal planning of integrated electricity-natural gas distribution systems with hydrogen enriched compressed natural gas operation

In future integrated electricity-natural gas distribution systems (IEGDS), hydrogen and methane converted from excessive renewable generation will be mixed with natural gas to form hydrogen enriched compressed natural gas (HCNG) for fewer carbon emissions. Consequently, optimal planning of the HCNG-integrated IEGDS plays an essential role in increasing the economy and technical benefits. However, integrating HCNG operation into the planning of IEGDS still has many challenges, such as unrealistic modeling, nonlinear constraints, and the potential risk of voltage violations. The purpose of this paper is to develop a tractable optimization model for planning and operation of the HCNG-integrated IEGDS, aiming to minimize the investment and operating cost, reduce the voltage violation, and improve the renewable power penetration rate. To achieve this, a bilevel optimization model is developed for optimal planning of wind turbines and soft open points (SOPs) in the IEGDS considering comprehensive HCNG operation, in which both hydrogen and methane injection are considered and optimized for different system operation scenarios. Furthermore, the proposed nonlinear model is reformulated to a tractable bilevel mixed-integer second-order cone model using several reformulation techniques and solved by the reformulation and decomposition algorithm. Case studies, performed using the publicly available datasets, are conducted to demonstrate the economic and technical improvement by implementing the proposed planning model. The annual planning results show that incorporating the coordination between SOPs and methane injection results in a 6.77% reduction in investment cost, a 22.64% reduction in operating cost, a 62.69% decrease in voltage violation, and a 23.58% increase in the wind power penetration rate. Moreover, SOPs are more applicable to the safe operation of the IEGDS under high energy load conditions.

Soret effect on the mixing of H2 and CO2 cushion gas: Implication for underground hydrogen storage

For underground hydrogen storage (UHS), hydrogen (H2) injection and withdrawal will create a temperature difference between the wellbore and the reservoir. The thermal diffusion driven by the temperature gradient (Soret effect) may enhance the mixing between H2 and cushion gas and affects the purity of the produced H2. In this work, the thermal diffusion process of H2 and CO2 under reservoir conditions is quantitatively observed for the first time. Results show that the Soret effect drives H2 accumulation in the high-temperature region, and is influenced by temperature, pressure, and concentration. There is significant concentration difference between the high- and low-temperature sections when minor quantities of gas are injected. From experimental observations, we obtain the Soret coefficients across different physical conditions and propose a correlation for their prediction. Additionally, while thermal diffusion slows down in porous reservoirs, the concentration difference established along the temperature gradient remains unchanged at steady state.

Reduction Degradation of Lump, Sinter, and Pellets in Blast Furnace with Hydrogen Injection

Reduction Degradation of Lump, Sinter, and Pellets in Blast Furnace with Hydrogen Injection

AI-assisted optimal energy conversion for cost-effective and sustainable power production from biomass-fueled SOFC equipped with hydrogen production/injection

This study introduces a novel energy conversion and management framework to reduce carbon emissions in the energy sector and expedite the global shift towards sustainable practices. The system is driven by biomass-based solid oxide fuel cells for efficient power generation. Central to this approach lies the integration of additional hydrogen injection provided by a thermally-driven vanadium chloride cycle, aiming to enhance the quality of the syngas entering the fuel cells. The system is also combined with a super-critical CO2 cycle that generates power by passively enhancing performance through flue gas condensation. The proposed model's feasibility is evaluated in depth, techno-economically, considering thermodynamics and specific cost theories. As part of artificial intelligence, a neural network model is coupled with the genetic algorithm to determine the best operating status while minimizing computation time. According to the results, the suggested new integration results in higher efficiency and lower cost than a similar system without hydrogen injection. The results further show that the triple-objective optimization achieves output power, second-law efficiency, and overall system cost of 3425 kW, 48.5 %, and 2.3 M$/year, respectively. Eventually, the gasifier is the main contributor to the highest level of exergy destruction, and fuel utilization and current density are the most important parameters in modeling.

A comparative study on the premixed ammonia/hydrogen/air combustion with spark ignition and turbulent jet ignition

Turbulent jet ignition (TJI) is an advanced ignition mode that can enhance ignition and combustion performance, and it is a potential ignition strategy for ammonia/hydrogen internal combustion engines. This study aims to investigate the ignition and combustion characteristics of lean ammonia/hydrogen/air ignited by TJI, and the different ignition modes were compared. The results indicate that active TJI with auxiliary hydrogen injection in the pre-chamber improves the ignition and combustion performance of ammonia/hydrogen/air, and the appropriate shift of the pre-chamber equivalence ratio towards the rich side is considered optimal. As the ammonia fraction increases, the ignition mechanism in the main chamber changes from flame ignition to jet ignition. The advantage of TJI is mainly shown in high ammonia fraction mixtures, which is reflected in significantly lower ignition delay and combustion duration. In addition, TJI reduces the sensitivity of combustion to ammonia fraction compared to SI, due to the high ignition energy, initial flame area and turbulence provided by the hot jet. In TJI mode, the increase in jet velocity seems to be detrimental to the radial development of flames near the orifice, which may result in an increase in the duration of the final stage of combustion.

Thermodynamic and kinetic considerations of the link between underground hydrogen storage and reductive carbonate dissolution and methane production. Are limestone reservoirs unsuitable for UHS?

Storing hydrogen underground for cyclic injection/retrieval may help move the world towards a decarbonised economy. In search of suitable long-term reservoirs, the potential reactivity of the matrix with hydrogen plays a major role. This is especially poignant for carbonate minerals, due to their abundance, ubiquity, and much faster dissolution kinetics compared to silicates. Geochemical modelling studies invariably find hydrogen-induced reductive carbonate dissolution and methane production (HIRCDAMP) whereas experimental studies, for the most part, do not support this view. To answer the question of how far injected hydrogen may oxidise, protonate and cause reductive dissolution of carbonates, a thermodynamic approach based on standard redox and overall cell potentials, as well as Gibbs free energies, was chosen. Together with observations on kinetic constraints, a consistent picture emerges in which purely inorganically driven reduction of (bi)carbonate to methane by hydrogen oxidation is not likely to occur. Rather, the formation of intermediate carbon species (e.g., formate) could be a kinetically and thermodynamically more favourable pathway than that to methane. It follows that geochemical models that question the long-term viability of hydrogen injection into carbonate-bearing reservoirs need to be revised, toning down any alleged, yet by experimental studies not substantiated, hydrogen reactivity in the absence of any catalyst and/or microbial activity.

Combustion characteristics analysis and performance evaluation of a hydrogen engine under direct injection plus lean burn mode

Direct injection plus lean burn technology can effectively control combustion processes and reduce carbon emissions of hydrogen engines. Hence, hydrogen direct injection strategy optimization is a key means to improve engine performance and achieve low emissions. Thus, a three-dimensional transient calculation model coupled chemical reaction mechanism is established, and its reliability and accuracy are systematically evaluated using experimental data. Then, the effects of hydrogen direct injection strategies on the hydrogen-air mixing and combustion process are investigated. The results indicate that the ideal mixture stratification law is that the gas fuel concentration is gradually stratified from the ignition center to the periphery region. The maximum indicated work is obtained for the B-60° scheme which its injection position is near the intake side and 7.5 mm from the cylinder center on the X-axis. The optimal hydrogen injection angles vary with different injection positions by evaluating engine performance, specifically, 60° is optimal for injection position B, while 30° is best for injection position C which is between intake and exhaust and 40 mm from the cylinder center on the Y-axis. Finally, the achieved maximum thermal efficiencies of 41% and indicated power of 4.29 kW for the B-60° scheme, and its nitric oxide can meet the Europe V emission standards (7.5 g/kWh). This research can offer theoretical guidance for designing and optimizing fuel injection strategies for hydrogen energy engines, and it is relevant for promoting carbon neutrality and cleaner production.

Study on the influence of hydrogen injector flow rate in hydrogen-oxygen engine thrust chamber

Study on the influence of hydrogen injector flow rate in hydrogen-oxygen engine thrust chamber

Low-carbon operation of integrated electricity–gas system with hydrogen injection considering hydrogen mixed gas turbine and laddered carbon trading

Green hydrogen produced by the power-to-gas facilities can be blended into the natural gas system, which is a promising way toward a low-carbon energy system. This paper proposes a laddered carbon trading-based operation model for integrated electricity–gas system with hydrogen injection considering the complex combustion properties of hydrogen mixed gas turbine (HMGT). The power-to-hydrogen, hydrogen methanation, and carbon emission processes are combined with the methane reactor and the flexible carbon capture, utilization and storage facility. Then, a HMGT combustion model based on the system thermodynamics and chemical reaction kinetics is introduced. The piecewise linearization technique is adopted to describe the varying hydrogen production efficiency of electrolysis system. Moreover, an energy balance based quasi-steady-state model to deal with the calorific value problem of the gas mixture is proposed and solved by an advanced sequential cone programming algorithm. Case studies are carried on a 30-bus-20-node system and a 197-bus-171-node practical system in Northwest China to illustrate the effectiveness of the proposed model.

An investigation on the H2O, unburned H2 and NO emission characteristics from a direct injection hydrogen engine

Hydrogen engines show great potential as a power source with good combustion performance, zero carbon emissions, and diverse sources. However, the exhaust emission characteristics with high water vapor (H2O) content have not yet been clarified. This study presents the exhaust emissions of a heavy-duty direct-injection hydrogen engine under various operational parameters, with a focus on the H2O content. The results reveal important exhaust emissions characteristics of the hydrogen engine, including lower exhaust temperature (200 °C–400 °C), higher unburned H2 emissions (up to 17100 ppm), less nitrogen oxide (NO) generation (<1000 ppm), and higher H2O content (6%–40%). Additionally, unburned H2 rises, and NO and H2O decrease as the excess air ratio (λ) increases. When λ is greater than 3, NO levels fall sharply to below 100 ppm. Optimal emissions performance is achieved with a 5 °CA BTDC ignition timing where low levels of H2, H2O, and NO are maintained. Increasing hydrogen injection pressure decreases H2 but raises exhaust temperature, H2O, and NO emissions. Excessively delaying hydrogen injection timing adversely affects the concentration gradient in the cylinder, increasing unburned H2 emissions. The best emissions performance is observed at a hydrogen injection timing of 110 °CA BTDC.

Using green hydrogen as the supplementary fuel for a scheme of power/fresh water production: An application of AI for optimal energy management and emission reduction

The primary objective of the current research is to speed up the shift towards a carbon-neutral economy and reduce our reliance on fossil fuels by developing a novel, highly efficient, environmentally friendly, and economically feasible multi-generation system based on solar-biomass hybridization. The essential element of this concept involves the introduction of green hydrogen into the combustion chamber, aiming to enhance the quality of the incineration products and facilitate the implementation of a waste-to-power Rankine cycle. The practicality of the suggested model is compared with a system that does not incorporate hydrogen injection. As a part of artificial intelligence, a neural network model integrated with the grey wolf optimizer is applied to ascertain the most optimal energy conversion/management condition with reduced computational time. The results show that the injection of additional hydrogen exhibits superior performance compared to the base system from all facets. The optimization achieves higher exergy efficiency and drinkable water production of 8.7 % and 27.9 kg/s while reducing the total cost and emission index of 13.7 $/h and 410.7 kg/GWh. The results indicate that the combustion chamber and steam generator are the poorest parts in terms of exergy under ideal conditions. Potential future directions of this work are to explore alternate techniques for generating hydrogen and perform regional evaluations to comprehend the accessibility and fluctuation of biomass and solar resources in various geographical areas.

The effect of activated water on lentil seed germination utilizing several plasma reactors and a hydrogen injection system

As a threat to meeting the global demand for food created by the continued growth of population, different methods are being applied to enhance seed germination and plant growth. This study investigates the effect of hydrogen-rich water (HRW) and different plasma-activated waters (PAW) and their combinations including HRW, PAW1, PAW2, HPAW1, and HPAW2 on the seed germination of lentils. Different arc discharge reactors are generated under atmospheric pressure in the air. Optical emission spectroscopy was used to detect the radiative species formed in the plasma zone. Raman spectra and physicochemical properties of different waters were investigated. The results demonstrated significant differences in the properties of different activated waters compared to control water. On day 3 after treatment, the fraction and length of germinated seeds were evaluated. During germination, treated water significantly increased germination parameters such as final germination percentage, mean germination time, germination index, and coefficient of germination velocity. HPAW2 exhibited the highest germination index (GI), which combines germination percentage and speed. The plasma systems also effectively reduced the pH of PAW1 and PAW2, with a greater decrease observed in HPAW1 and HPAW1. Analysis of nitrite and nitrate levels revealed that HPAW2 had the highest concentrations, indicating more reactive processes in the presence of hydrogen. Based on our results, it can be concluded that lentil seed germination can be increased using PAW and hydrogenated PAW combined.

Numerical Simulation on Combustion Characteristics of Methane Air Premixed Flame Impacted by Hydrogen jet

Abstract Low-concentration coalbed methane is an efficient and clean unconventional natural gas with abundant reserves. It can greatly lessen the problem of energy scarcity when used to produce combustion power. Nevertheless, the engine finds it challenging to burn the CH4 directly due to its low and fluctuating concentration. This study suggests using a hydrogen jet to ignite low-concentration coalbed methane. The simulation method is used in this paper. To investigate the effects of various ignition injection strategies on the combustion characteristics of low concentration coalbed methane ignited by a hydrogen jet, a constant volume bomb model was developed. The results show that when the ignition and hydrogen injection interval is 2.0 ms, the cold jet of hydrogen does not burn immediately when it reaches the premixed flame, and there is a transition process from the premixed flame to the jet flame. The larger the interval between ignition and hydrogen injection, the more waste gas is produced after the premixed flame combustion, which has a certain inhibition effect on the formation of the jet flame. With the decrease in the interval between ignition and hydrogen injection, the combustion duration is obviously shortened. Therefore, the earlier hydrogen is involved in the ignition, the faster the combustion speed.

Phenomenal study of microbial impact on hydrogen storage in aquifers: A coupled multiphysics modelling

Underground hydrogen storage (UHS) has been considered as an integral part of energy transition from fossil fuels to renewable sources. Porous aquifers can serve as typical sites for this purpose due to their worldwide distribution and huge storage capacity. However, the diverse microbial species that inhabit the aquifers are known to be able to catalyze in-situ biochemical reactions within the hosting rock. These reactions can normally lead to microbial consumption of hydrogen, microbial clogging of pore space and thus affect hydrogen injection and withdrawal rates as reported in the literature. So far, these phenomena have been widely reported but rarely quantified. In this study, we build a coupled hydrological-mechanical-chemical-biological (HMCB) multiphysics model to simulate these microbe-related processes during UHS in aquifers. The model consists of a complete set of partial differential equations to describe: (1) rock deformation; (2) water-hydrogen two-phase flow; (3) microbes and dissolved hydrogen transport; (4) mineral dissolution/precipitation; and (5) microbial activities involving adsorption/desorption and growth/decay. All these processes are linked together through the porosity/permeability models which consider the joint impacts of microbial clogging, mineral dissolution/precipitation and effective stress. This multiphysics model is verified against laboratory biochemical reaction data and microbial transport data. Then, the verified model is used to investigate the impacts of iron-reduction bacteria (IRB) activities on UHS in aquifers. Based on the simulation results, it can be concluded that (1) hydrogen saturation at the top surface of the aquifer is the greatest while microbial activities surrounding the injection well is stimulated the most; (2) microbial activities influence the initial few cycles of hydrogen injection and withdrawal but the impacts gradually diminish with the dissolution of Fe2O3; (3) hydrogen recovery efficiency is degraded due to the combined effects of hydrogen consumption, water production and microbial clogging with the microbial clogging impact being the most significant; and (4) effective stress impacts aquifer permeability throughout UHS operations while microbial clogging influences it in the initial few cycles. For mineral dissolution/precipitation, the impact can be neglected.

Composition tracking of natural gas–hydrogen mixtures in pipeline flow using high-resolution schemes

A transient pipeline flow model with gas composition tracking is solved for studying the operation of a natural gas pipeline under nonisothermal flow conditions in a hydrogen injection scenario. Two approaches to high-resolution pipeline flow modeling based on the WENO scheme are presented and compared with the implicit finite difference method. The high-resolution models are capable of capturing fast fluid transients and tracking the step changes in the composition of the transported mixture. The implicit method assumes the decoupling of the flow model components in order to enhance calculation efficiency. The validation of the composition tracking results against actual gas transmission pipeline indicates that both models exhibit good prediction performance, with normalized root mean square errors of 0.406% and 1.48%, respectively. Under nonisothermal flow conditions, the prediction response of the reduced model against a high-resolution flow model, with respect to the mass and energy linepack, is at most 3.20%.

KHz Rate Fs/Ps-CARS Thermometry For Supersonic H_2/Air Combustion Studies

Accurate flow field measurements are essential to probe the phenomena involved in aeronautical engines undergoing high temperature and high turbulences. Indeed, reliable experimental datasets are needed to compare and validate numerical models. Among other laser diagnostics, Coherent Anti-stokes Raman Scattering (CARS) is a well-established non-linear spectroscopic technique used to probe harsh environments, since it provides non-intrusive local point measurements of chemical composition and temperature. We report here hybrid fs/ps Coherent Anti-Stokes Raman Scattering (fs/ps-CARS) thermometry campaign performed on N 2 in a supersonic H2 /air combustion. We used a mobile and compact laser architecture that shapes, synchronize and generates the laser beams necessary for CARS spectroscopy. The instrument was moved to a large-scale facility representative of a scramjet combustor (ONERA LAERTE/LAPCAT-II bench). H2 /air was injected during several burst at 0,12 and 0,15 equivalent ratios. Using kHz single-shot measurements combined with motorized translation stages, spatial and temporal resolution were obtained to probe the flow and the combustion at various positions upstream and downstream the hydrogen injectors. At these positions, horizontal and vertical temperature profiles were retrieved and compared with a numerical unsteady fluid dynamic simulation using delayed detached eddy simulations (DDES) developed at ONERA (CEDRE). The position of the combustion inside the combustion chamber could be identified through several horizontal and vertical profile temperature measurements. The signal-to-noise ratio of the detection was optimized by empirically adjusting the number of averaged laser shots based on the level of flow turbulence. For instance, far downstream the H2 injection, averaging over 10 to 100 pulses was possible as the heated air flow was steady. This was confirmed by the good agreement with numerical simulations although some distortion could still be observed and will be used to adjust the numerical simulation algorithm. However, averaging was no longer possible close to the injectors, where a highly turbulent H2 /air combustion was observed. Nevertheless, taking advantages of the high rate single-shot capacity of the spectroscopic technique, temperature could still be retrieved inside this area. These measurements provided a valuable experimental database for comparing and refining computational fluid dynamics modeling.

Numerical simulation of hydrogen co-firing distribution on combustion characteristics and NOx release in a 660 MW power plant boiler

The article discussed the influence on furnace temperature distributions, combustion characteristics, and NOx release when hydrogen, coal, and sludge co-firing in a 660 MW power plant boiler by CFD. Non-premixed combustion model was chosen as the gas combustion model. As the height of the hydrogen injection position rises, the temperature difference in the main combustion region decreases from 297.22 K to 94.72 K. The co-combustion of hydrogen inhibits solid fuels' combustion. As hydrogen nozzles' height decreases, the NOx mass at the furnace outlet increases from 98.41 % to 160.38 %. When the excess air coefficient changes from 1.15 to 1.35, the temperature in the main combustion region significantly increases, while the temperature in the upper furnace decreases, and the heat flux of the main combustion region increases by 11.10 %, the heat flux of the total furnace decreases by 1.39 %, the NOx mass at the furnace outlet increases by 31.67 %. The optimum co-combustion method is injecting the hydrogen from the top hydrogen nozzles and the excess air coefficient is 1.15, the overall impact on the furnace is minimal in this way. The fundamental reason hydrogen affects co-combustion is the fuel characteristics’ difference between hydrogen and solid fuels.