Browse Topic: Methane

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Optimization of Biogas Combustion in SI Engines Applied to the Pre-Chamber Ignition System2025-36-020912/18/2025
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Siqueira, Caio Henrique Moreira, Ázara, Luiz Eduardo Martins, Ribeiro, José Vitor Puttini, Soares, Gabriel Faria, Silva, Fábio Moreira, Alvarez, Carlos Eduardo Castilla
Review of the Potential for Utilizing Organic Waste for Biogas Production in Latin American Countries2025-36-008312/18/2025
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Rodrigues, Jônatas Soares, Moreira, Thiago Augusto Araújo, Souza Pereira, Felipe Augusto de, Castro, Daniel Enrique
Visualization Study on Combustion Characteristics of Ammonia/Methane/Air Mixtures Ignited by Diesel Pilot in Rapid Compression and Expansion Machine2025-32-005411/03/2025
The application of ammonia fuel in engines can significantly reduce carbon emissions, serving as a crucial method for achieving carbon neutrality. However, its potential is hindered by the challenges of ammonia's difficulty in ignition and slow combustion rate. An effective solution to these drawbacks is to blend methane into ammonia mixtures and use a small amount of diesel for ignition. This study investigates the effects of mixture equivalence ratio and gas composition on the combustion characteristics of diesel-ignited NH3/CH4/Air mixtures. Pressure measurements and visual observations were conducted using a rapid compression expansion machine (RCEM). Experimental results reveal that the combustion process exhibits two distinct stages: initial intense diesel combustion followed by mixture combustion. Higher equivalence ratios prolong ignition delay while accelerate secondary combustion. Pure ammonia mixtures show incomplete lean combustion, while richer mixtures achieve more
Yin, Shuo, Dai, Zhizhuo, Zhou, Qingxing, Cui, Zechuan, Zhang, Xiaolei, Ye, Mingyuan, Ren, Yifang, Wang, Zhanpeng, Nishida, Keiya
Experimental and Kinetic Study of Methane Blending on The Laminar Combustion and Emission Characteristics of Ammonia Under Various Oxygen Contents at High Temperature and Pressure2025-32-006011/03/2025
As a carbon-free fuel, ammonia is one of the alternatives to traditional fossil fuels, but its combustion characteristics are poor, and it is usually optimized by blending methane and increasing oxygen content. However, there are few relevant studies under different conditions. In this study, the laminar burning velocities (LBV) and flame instability of NH3/CH4/O2/N2 mixture at high initial temperature (T), high initial pressure (p), various oxygen contents (Ω) and methane energy ratios (α) are analyzed using a constant volume combustion chamber (CVCC). Through numerical simulation, how various oxygen contents and methane energy ratios affect the combustion characteristics of NH3/CH4/O2/N2 mixture and NO emission is analyzed. The results show that LBV is positively correlated with T, α and Ω, and negatively correlated with p. Markstein length (Lb) does not change significantly with T, but increases with α and decreases with p and Ω. Both oxygen enrichment and methane blending
YU, Yuantao, Dai, Zhizhuo, Hou, Chunlei, Ye, Mingyuan, Zhang, Xiaolei, Cui, Zechuan, Yin, Shuo, Nishida, Keiya
Experimental Study on Hydrogen-Methane Co-Combustion in Small Gas Engines2025-32-005511/03/2025
Hydrogen fuel has garnered significant attention as a key method for adapting internal combustion engines to a carbon-neutral society. Hydrogen is a carbon-free fuel that does not produce CO2 emissions during combustion. However, its wide flammability range and extremely low ignition energy present technical challenges when applied to internal combustion engines, such as the frequent occurrence of abnormal combustion phenomena like pre-ignition and knocking. Furthermore, the low energy density of hydrogen makes it difficult to achieve high power output. Additionally, hydrogen’s high adiabatic flame temperature and short quenching distance result in increased NOx emissions and cooling loss, which are further obstacles to its use. To address these issues, this study focuses on methane blending as a remedial approach. Experiments were conducted using a naturally aspirated engine with a premixed intake method to investigate the effects of methane-hydrogen blending. The following key
Tanaka, Kenta, Tani, Toshihiro, Sako, Takahiro
Effect of Flow Speed and Turbulence on Methane Combustion in a Rapid Compression Machine2025-01-039310/07/2025
Recent experimental work from the authors’ laboratory demonstrated that applying a boosted current ignition strategy under intensified flow conditions can significantly reduce combustion duration in a rapid compression machine (RCM). However, that study relied on spark anemometry, which provided only localized flow speed estimates and lacked full spatial resolution of velocity and turbulence near the spark gap. Additionally, the influence of turbulence on combustion behavior and performance across varying flow speeds and excess air ratios using a conventional transistor-controlled ignition (TCI) system was not thoroughly analyzed. In this study, non-reactive CFD simulations were used to estimate local flow and turbulent velocities near the spark gap for piston speeds ranging from 1.2 to 9.7 m/s. Simulated local velocities ranged from 0.7 to 96 m/s and were used to interpret experimentally observed combustion behavior under three excess air ratios (λ = 1.0, 1.4, and 1.6). Combustion was
Haider, Muhammad.Shaheer, Jin, Long, Yu, Xiao, Reader, Graham, Zheng, Ming
Combined Biological and Electrochemical Process to Produce Ammonia Fuel from High-Strength Blackwater2025-01-048309/16/2025
This study develops a biological-electrochemical process for ammonia fuel production from high-strength blackwater, integrating enhanced ammonification, anaerobic digestion (AD), and electrodialysis (ED). The system achieved 90% COD removal, with Bacillus subtilis increasing NH3-N concentrations by 113%, enhancing nitrogen recovery. AD reduced volatile solids by 60%, producing 200 mL/day of biogas with 70% methane content, and increased NH3-N from 215 to 308 mg/L in the effluent. ED concentrated ammonia to 3 g NH3-N/L with an energy consumption of 1.8 Wh/L, while diluted effluent contained <30 mg NH3-N/L. The system generated a net energy output of 20.48 kWh-e/day, transforming wastewater from an energy sink into an energy-positive process. This approach enables high-efficiency nitrogen recovery, converting waste into ammonia fuel for reformation efforts, while supporting decentralized sanitation solutions.
Thomas, Benjamin, Emerson, Emilia, Smerigan, Blake, Monson, Carter, Liu, Yan, Boltersdorf, Jonathan, Hill, Caroline, Dillon, Robert J., Baker, David R., Dusenbury, James, Liao, Wei
Optical Diagnostic Analysis of Methane Combustion Performance and Emissions While Incorporating Ammonia and Multiple Flames In A Spark-Ignition Engine2025-24-002309/07/2025
The utilization of methane–ammonia fuel blends in spark-ignition engines represents a viable strategy for reducing carbon emissions while capitalizing on the high hydrogen content and carbon-free nature of ammonia. Methane, characterized by its high octane number and low carbon content, offers improved thermal efficiency, higher compression ratios, and reduced pollutant emissions relative to conventional gasoline fuels. Ammonia, despite its advantageous energy density and zero carbon content, suffers from low flame speed and high ignition temperature, which pose challenges for stable combustion. Blending ammonia with methane addresses these limitations by enhancing ignition characteristics and flame stability while simultaneously reducing carbon-based emissions. This study examines the combustion and emission behavior of methane–ammonia blends in a single-cylinder, four-stroke engine under varying spark ignition configurations. Experiments were conducted across a range of ammonia
Uddeen, Kalim, Tang, Qinglong, Shi, Hao, Turner, James
Enhancing Ammonia Combustion in Heavy-Duty SI Engines: A 3D-CFD Study on Pre-Chamber Ignition, Methane Addition, and Spark Timing Optimization2025-24-000609/07/2025
Ammonia is a promising fuel for achieving zero-carbon emissions in internal combustion engines. However, its low flame speed and heat of combustion pose significant challenges for efficient combustion. The pre-chamber (PC) spark-ignition (SI) system offers a viable solution by generating multiple ignition points in the main chamber (MC), enhancing combustion efficiency and enabling at the same time lean-burn operation. This study investigates the combustion characteristics and emissions of an active PC spark-ignition heavy-duty engine fueled with ammonia and ammonia-methane mixtures through numerical 3D-CFD simulations performed using the CONVERGE software. These simulations provide an accurate representation of the complex chemical and physical phenomena occurring within the combustion chamber. The study starts from a fully methane-fueled case, validated against experimental data, and subsequently explores different ammonia-methane mixtures. Then, a detailed spark timing (ST) analysis
Palomba, Marco, Salahi, Mohammad Mahdi, Cameretti, Maria Cristina, Mahmoudzadeh Andwari, Amin
Life Cycle Assessment of Hydrogen Generation through Steam Methane Reforming: A Focus on Co-Product Allocation between Steam and Electricity2025-01-018106/16/2025
This research presents a numerical analysis of the environmental impacts associated with using hot steam as a co-product in hydrogen production through Steam Methane Reforming (SMR) of renewable gas sources. As hydrogen production technology advances rapidly, reducing emissions and addressing environmental concerns, particularly greenhouse gas (GHG) emissions, have become essential. This study examines the SMR process with a focus on the environmental effects of utilizing hot steam as a co-product for electricity generation or facility heating. The analysis evaluates renewable feedstocks, including landfill gas, animal waste, food waste, and wastewater sludge, to determine their viability for sustainable hydrogen production. Key pollutants, such as carbon monoxide and nitrogen oxides, along with GHGs, are assessed to identify the most environmentally advantageous feedstock options. This work aims to provide insights to promote sustainable hydrogen production practices.
Rosyadi, Ahmad Adib, Lim, Ocktaeck
Heat Transfer Characteristics of Lean Methane Flame in the Region near the Wall Boundary Layer2024-32-012004/18/2025
Since proportion of wall heat loss takes as high as 20-30% of the total engine heat loss, the reduction of wall heat loss is considered as an effective way to improve the engine thermal efficiency. The heat transfer near the wall boundary layer plays a significant role on the exploration about the mechanism of wall heat transfer which contributes to figuring out the approach to the reduction of wall heat loss. However, the near wall characteristics of heat transfer are still unclear. In this study, the premixed lean methane flame propagation was captured by the high-speed schlieren and the flame behavior in the near-wall region was investigated by the micro CH* chemiluminescence. The temporal histories of the wall temperature and the heat flux are measured by the co-axial thermocouple. The factors including the convective heat transfer coefficient and non-dimensionless numbers, Nusselt number and Reynolds number, were used to characterize the near wall characteristics. Also, the
Xuefeng, Xue, Run, Chen, Tie, Li
The Numerical Study of Methane Flame Characteristics in the Ammonia/Air Environment at Sub-Atmospheric Pressure2025-01-845004/01/2025
The low emission of carbon and minimum level of soot formation in combustion engines and turbines strategy is adopted by many countries to counteract global warming and climate change. The use of ammonia with hydrocarbon fuels can limit the formation of soot and carbon emissions due to non-carbon atoms. The current study explores the use of ammonia with air at coflow flame conditions, which was not tested before. It may give the choice for diesel cycle engines to use the ammonia either with air or fuel. The combustion and emission characteristics of methane coflow flame were studied at low pressure and air polluted by ammonia conditions. The results showed that a significant decline in carbon formation was observed when ammonia was boosted, 5-10%. The impact of sub-atmospheric pressure, 90-70 KPa, on COx development was higher than that of NH3 addition, 0-5%, thanks to the lower formation of hydroxymethylium, formaldehyde, and aldehyde radical. In the environment of lower pressure, the
Hina, Anam, Akram, M Zuhaib, Shafa, Amna, Akram, M Waqar
Operating the Tour Split-Cycle Engine on Hydrogen/Methane Fuel Blends to Achieve High Efficiency and Reduction of Both GHG and NOx Emissions2025-01-842204/01/2025
Decarbonized or low carbon fuels, such as hydrogen/methane blends, can be used in internal combustion engines to support ambitious greenhouse gas (GHG) emission reduction goals worldwide, including achieving carbon neutrality by 2045. However, as the volumetric concentration of H2 in these fuel blends surpasses 30%, the in-cylinder flame propagation and combustion rates increase significantly, causing an unacceptable increase in nitrogen oxides (NOx) emissions, which is known to have substantial negative effects on human health and the environment. This rise in engine-out NOx emissions is a major concern, limiting the use of H2 fuels as a means to reduce GHG emissions from both mobile and stationary power generation engines. In this study, an experimental investigation of the combustion performance and emissions characteristics of a 4th generation Tour split-cycle engine was undertaken while operating on 100% methane and various hydrogen/methane fuel blends (30%, 40%, and 50% by volume
Bhanage, Pratik, Cho, Kukwon, Anderson, Bradley, Kemmet, Ryan, Tour, Gilad, Atkinson, Chris, Tour, Hugo, Tour, Oded
Cryogenic Flux CapacitorTBMG-5247702/01/2025
NASA's Cryogenic Flux Capacitor (CFC) capitalizes on the energy storage capacity of liquefied gases. By exploiting a unique attribute of nano-porous materials, aerogel in this case, fluid commodities such as oxygen, hydrogen, methane, etc. can be stored in a molecular surface-adsorbed state. This cryogenic fluid can be stored at low to moderate pressure densities, on par with liquid, and then quickly converted to a gas, when the need arises. This solution reduces both safety-related logistics issues and the limitations of complex storage systems.
Experimental Investigation of Hydrogen or Methane Injection in Active Pre-Chamber on a Lean Combustion Gasoline Engine2025-01-710601/31/2025
With the global promotion of carbon neutrality policies, internal combustion engine (ICE) of traditional fossil fuel is gradually transitioning to carbon neutral fuel ICE, and hybrid dedicated engines are gradually replacing traditional internal combustion engines in the passenger car market. Ultra-lean combustion supported by active pre-chamber is one of the key technologies for achieving high thermal efficient over 45% BTE. However, there are still issues like cold start and PN emissions caused by impingement of liquid fuel injection in pre-chamber, and there is still room for improvement in thermal efficiency by less energy of pilot ignition fuel. Gaseous fuel such as hydrogen or methane have no wetting issues, and can be more easily controlled in terms of the injection amount in pre-chamber, thereby using a less amount of gaseous fuel as the pilot ignition fuel could be a solution. Due to the above situation, this article conducted experiments on a lean burn gasoline engine by
Liu, Yaodong, Liu, Mingli, He, Zhentao, Li, Xian, Zhao, Chuan, Qian, Dingchao, Qu, Hanshi, Li, Jincheng
Effect of Gasification Temperature on Biohydrogen Derived from Waste Agro Products for Alternative Fuel Application2024-01-526001/28/2025
Hydrogen fuel is becoming a popular choice in many energy applications because of its innovative green technology, which produces zero carbon emissions. It also offers better efficiency than fossil fuels. Current research focuses on obtaining hydrogen energy from agricultural waste using a gasification process. This process involves heating the waste at gasification temperatures 300, 400, 500, 600, and 700°C, maintaining a residence time of 60 minutes, and applying a gasification pressure of 20 bar. The effects of gasification temperature on the effectiveness of hydrogen production are examined. At a high gasification temperature of 700°C and a residence time of 60 minutes, the processed agro feedstock showed impressive results. It achieved a molar fraction of 12% carbon dioxide (CO2), 31% methane (CH4), and 55% hydrogen (H2), leading to an improved hydrogen yield of 15.2 mol/kg. Additionally, it demonstrated better hydrogen selectivity at 8.1 and a higher gasification efficiency of 61
Venkatesh, R., De Poures, Melvin Victor, Raguraman, B., Marimuthu, S., Devanathan, C., Baranitharan, Balakrishnan, Madhu, S., Kaliyaperumal, Gopal, Manickaraj, Pethuraj
Fuel Design Concept to Improve Both Combustion Stability and Antiknocking Property Focusing on Ethane2024-01-427611/05/2024
For realizing a super-leanburn SI engine with a very-high compression ratio, it is necessary to design a new fuel which could have low ignitability at a low temperature for antiknocking, but high ignitability at a high temperature for some contribution to stable combustion. C2H6 has a very-long ignition delay time at a low temperature, close to that of CH4, but a short ignition delay time at a high temperature, close to that of gasoline. C2H6 also has a laminar burning velocity about 1.2 times higher than that of gasoline. C2H6 addition to gasoline could be a good example of fuel design to improve both combustion stability and antiknocking property. In the present study, the antiknocking effect of adding CH4, C2H6, or C3H8 with the RON of 120, 115, or 112, respectively, to a regular-gasoline surrogate fuel with the RON of 90.8 has been investigated in an SI engine with a stoichiometric mixture. With the energy fraction of the gaseous fuel of less than 0.35, knocking limit CA50 is
Kuwahara, Kazunari, Shimizu, Taisei, Okada, Atsuki
A Hydrogen-Powered Airship Sets Course for Greener Aerial InspectionsTBMG-5184110/16/2024
Pipeline inspection is a crucial aspect of maintaining the integrity, safety, and reliability of the planet’s energy infrastructure. However, due to cost and scale challenges, infrastructure operators struggle to conduct accurate, large-scale inspections. A French startup, HyLight, offers a solution to precisely detect issues on the infrastructure, such as methane leaks on pipelines and defects on power lines at an industrial scale, without emitting greenhouse gases.
Numerical Study of Catalytic Methanation Reactions Using a Kinetic Model2024-24-002209/18/2024
Even if huge efforts are made to push alternative mobility concepts, such as, electric cars (BEV) and fuel cell powered cars, the importance and use of liquid fuels is anticipated to stay high during the 2030s. The biomethane and synthetic natural gas (SNG) might play a major role in this context as they are raw material for chemical industry, easy to be stored via existing infrastructure, easy to distribute via existing infrastructure, and versatile energy carrier for power generation and mobile applications. Hence, biomethane and synthetic natural gas might play a major role as they are suitable for power generation as well as for mobile applications and can replace natural gas without any infrastructure changes. In this paper, we aim to understand the direct production of synthetic natural gas from CO2 and H2 in a Sabatier process based on a thermodynamic analysis as well as a multi-step kinetic approach. For this purpose, we thoroughly discuss CO2 methanation to control emission in
Mauss, Fabian
Mimicking 'Plant Power' Through Artificial PhotosynthesisTBMG-5121408/01/2024
Solar panels are an increasingly popular way to generate electricity from the sun’s energy. Although humans are still figuring out how to reliably turn that energy into fuel, plants have been doing it for eons through photosynthesis. Now, a team reporting in ACS Engineering Au has mimicked the process to produce methane, an energy-dense fuel, from carbon dioxide, water and sunlight. Their prototype system could help pave the way toward replacing nonrenewable fossil fuels.
Effect of Dithering on Post-Catalyst Exhaust Gas Composition and on Short Time Regeneration of Deactivated PdO/Al 2 O 3 Catalysts under Real Engine Conditions2024-37-000206/12/2024
Fossil fuels such as natural gas used in engines still play an important role worldwide which however is also exacerbating climate change as a result of carbon dioxide emissions. Although natural gas engines show an overall low pollutant emissions level, methane slip due to incomplete combustion occurs, causing methane emissions with a more than 20 times higher global warming potential than CO2. Additionally, further tightening of emissions legislation is to be expected bringing methane emissions even more into focus making exhaust gas aftertreatment issues remain relevant. For lean gas applications, (Pd)-based catalysts turned out to convert CH4 most efficiently usually being supported by metal oxides such as aluminium oxide (Al2O3). Water (H2O) contained in the exhaust gas causes strong inhibition on Pd catalysts. In real exhaust gases, not only water vapour but also pollutants and sulphur-containing compounds such as hydrogen sulphide (H2S) or sulphur oxides (SOx) are poisoning the
Tomin, Sebastian, Wagner, Uwe, Koch, Thomas
Dimethyl Ether Biogas Reactivity-Controlled Compression Ignition for Sustainable Power Generation with Low Nitrogen Oxide Emissions03-17-07-005404/22/2024
Biogas (60% methane–40% CO2 approximately) can be used in the reactivity-controlled compression ignition (RCCI) mode along with a high-reactivity fuel (HRF). In this work dimethyl ether (DME) that can also be produced from renewable sources was used as the HRF as a move toward sustainable power generation. The two-cylinder turbocharged diesel engine modified to work in the DME–biogas RCCI (DMB-RCCI) mode was studied under different proportions of methane (45–95%) in biogas since the quality of this fuel can vary depending on the feedstock and production method. Only a narrow range of biogas to DME ratios could be tolerated in this mode at each output without misfire or knock. Detailed experiments were conducted at brake mean effective pressures (BMEPs) of 3 and 5 bar at a speed of 1500 rpm and comparisons were made with the diesel–biogas dual-fuel and diesel–biogas RCCI modes under similar methane flow rates while the proportion of CO2 was varied. The DMB-RCCI mode exhibited superior
Gopa Kumar, S., Mohan, Aneesh, Ramesh, A.
Sulfur Impact on Methane Steam Reforming over the Stoichiometric Natural Gas Three-Way Catalyst2024-01-263304/09/2024
The steam reforming of CH4 plays a crucial role in the high-temperature activity of natural gas three-way catalysts. Despite existing reports on sulfur inhibition in CH4 steam reforming, there is a limited understanding of sulfur storage and removal dynamics under various lambda conditions. In this study, we utilize a 4-Mode sulfur testing approach to elucidate the dynamics of sulfur storage and removal and their impact on three-way catalyst performance. We also investigate the influence of sulfur on CH4 steam reforming by analyzing CH4 conversions under dithering, rich, and lean reactor conditions. In the 4-Mode sulfur test, saturating the TWC with sulfur at low temperatures emerges as the primary cause of significant three-way catalyst performance degradation. After undergoing a deSOx treatment at 600 °C, NOx conversions were fully restored, while CH4 conversions did not fully recover. Experimental data under fixed lambda conditions reveal that sulfur stored on the catalyst leads to
Kim, Mi-Young, Dadi, Karthik Venkata, Gong, Jian, Kamasamudram, Krishna
Modeling and Analysis of the Hydrogen Production via Steam Reforming of Ethanol, Methanol, and Methane Fuels2024-01-217904/09/2024
The global transition to alternative power sources, particularly fuel cells, hinges on the cost-effective production and distribution of hydrogen fuel. While green hydrogen produced through water electrolysis using renewable energy sources holds immense promise, it currently falls short of meeting the burgeoning demand for hydrogen. To address this challenge, alternative methods, such as steam reforming and partial oxidation of hydrocarbon fuels with integrated carbon capture, are poised to bridge the gap between supply and demand in the near to midterm. Steam reforming of methane is a well-established technology with a proven track record in the chemical industry, serving as a dependable source of hydrogen feedstock for decades. However, to meet the demand for efficient hydrogen storage, handling, and onboard reforming, researchers are increasingly exploring liquid hydrocarbon fuels at room temperature, such as methanol and ethanol. In this work, we have developed reformer models for
Hariharan, Deivanayagam, Chhatija, Harish, Brown, Jonathan, Gundlapally, Santhosh
Add-On Device Makes Home Furnaces Cleaner and SaferTBMG-4981901/01/2024
Natural gas furnaces not only heat your home, they also produce a lot of pollution. Even modern high-efficiency condensing furnaces produce significant amounts of corrosive acidic condensation and unhealthy levels of nitrogen oxides, carbon monoxide, hydrocarbons, and methane. These emissions are typically vented into the atmosphere and end up polluting our soil, water, and air.
Coil-On-Plug Igniter for Reliable Engine StartsTBMG-4959812/01/2023
Innovators at NASA Johnson Space Center have developed a coil-on-plug ignition system for integrated liquid oxygen (LOX)/liquid methane (LCH4) thermal-vacuum environment propulsion systems operating in a thermal vacuum environment. The innovation will help quell corona discharge issues and reduce overall mass.
Experimental Investigation on Biogas Operated Electric Vehicle Charging Station2023-28-017811/10/2023
Biogas is developing as a possible replacement for fossil fuels as the globe shifts to sustainable energy sources. Organic waste, including food waste, agricultural waste, and sewage, decomposes to produce biogas. Biogas is a fuel that can be used to create electricity, heat homes, and power vehicles. The popularity of electric cars (EVs) is rising as a result of their zero emissions. EVs and biogas can work together to create a sustainable transportation option. The viability of EV charging stations powered by biogas is the main topic of this techno-economic inquiry. The study involves the evaluation of the technical and economic elements of the proposed system. The technical aspects cover power generation, the EV charging system, the biogas storage system, the biogas production process, and the biogas purification process. The capital cost, operating cost, and revenue from the charging station are all considered economic factors. The collection and processing of organic waste is a
Deepan Kumar, Sadhasivam, PC, Murugan, S, Jayakrishnan, Arun, M U, L, Naveen, R, Poomani
Efficiency Enhancement and Lean Combustion Performance Improvement by Argon Power Cycle in a Methane Direct Injection Engine2023-01-161810/31/2023
Argon Power Cycle (APC) is an innovative future potential power system for high efficiency and zero emissions, which employs an Ar-O2 mixture rather than air as the working substance. However, APC hydrogen engines face the challenge of knock suppression. Compared to hydrogen, methane has a better anti-knock capacity and thus is an excellent potential fuel for APC engines. In previous studies, the methane is injected into the intake port. Nevertheless, for lean combustion, the stratified in-cylinder mixture formed by methane direct injection has superior combustion performances. Therefore, based on a methane direct injection engine at compression ratio = 9.6 and 1000 r/min, this study experimentally investigates the effects of replacing air by an Ar-O2 mixture (79%Ar+21%O2) on thermal efficiencies, loads, and other combustion characteristics under different excess oxygen ratios. Meanwhile, the influences of varying the methane injection timing are studied. Results indicate that by
Wang, Chenxu, Deng, Jun, Su, Xiang, Cui, Wenyi, Tang, Yongjian, Li, Liguang
Impact of Hydrogen Energy Fractions on Cycle-to-Cycle Variations in Biogas-Fueled Spark Ignition Engine2023-01-507510/25/2023
The limitations related to the cost-effectiveness and technological feasibility of upgrading biogas to bio-methane for rural power generation applications have prompted researchers to explore alternative approaches for improving the quality of biogas fuel. This study focuses on evaluating the effect of hydrogen enrichment on combustion characteristics and cycle-to-cycle combustion variations in a single-cylinder spark ignition engine fueled with biogas (60% CH4 and 40% CO2). The engine was run at a constant operating load of 6 Nm, with a compression ratio of 10:1 and an engine speed of 1500 rpm. To establish a baseline for comparison, engine characteristics were initially assessed using pure methane fuel. Subsequently, the share of hydrogen in the biogas fuel mixture was incrementally increased on the volumetric basis from 0% to 30% and experiments were performed to study the effects of these variations on combustion behavior. The statistical approach was adopted for analyzing cycle-to
Sagar, Abhinandan, Kurien, Caneon, Mittal, Mayank
Study on Knocking Intensity and Autoignitive Propagation Velocity with the Same Methane Number Mixtures of Methane/Ethane and Methane/ n -Butane2023-01-180310/24/2023
Although methane number is widely used to predict knocking occurrence and its intensity, it does not determine a fuel composition uniquely, that means, the knocking intensity by the different composition fuel must show difference even if the same methane number fuels are employed. To establish a novel index, the knocking intensity and the autoignitive propagation velocity, as consequence of spontaneous ignition process, are investigated both experimentally and numerically by using the different composition gaseous fuels with same methane number. Methane/ethane/air and methane/n-butane/air mixtures with the same methane number of 70 and the equivalence ratio of 0.5 were employed. They are rapidly compressed and ignited spontaneously by a Rapid Compression Machine. Ignition delay times, autoignitive propagation velocities, and knocking intensity were measured by acquired pressure histories and high-speed imaging. To survey detail, zero-dimensional and quasi-one-dimensional numerical
Saito, Masanori, Kato, Ryo, Komatsu, Yuma, Takagi, Keigo, Otani, Masaki, Tanabe, Mitsuaki
The Effect of Methane Addition on the Low-Temperature Oxidation Preparation and the Thermal Ignition Preparation of Dimethyl Ether Under Representative Engine In-Cylinder Thermal Conditions2023-32-015009/29/2023
Dimethyl ether (DME) is a highly reactive diesel substitute that can be used as a pilot fuel to ignite low- reactivity methane (CH4) in heavy-duty engines. To optimize the efficiency and emissions of CH4/DME dual-fuel engines, it is crucial to study the fundamental combustion characteristics of DME mixed with methane. This study focuses on the influence of CH4 addition on the low-temperature oxidation (LTO) preparation stage and the thermal ignition (TI) preparation stage of DME in the two-stage ignition process, as these two stages respectively control the ignition delay of the first and second stages. The comparison is made between pure DME and a 50% CH4 and 50% DME blended fuel, operating under thermodynamic conditions representing the engine in- cylinder environment at 30 atm pressure, 650K temperature, and a stoichiometric equivalence ratio. The results show that the addition of methane hardly affects the control mechanism of the two-stage ignition of DME. Specifically, the LTO
Ou, Juan, Yang, Ruomiao, Yan, Yuchao, Liu, Zhentao, Liu, Jinlong
Study on Influences of Hydrogen addition and Turbulence on Ignition Characteristics of Hydrocarbon Mixtures2023-32-014709/29/2023
This study is performed to experimentally examine the effects of hydrogen addition and turbulence on the ignition and the flame-kernel development characteristics in isotropic and homogeneous turbulence for methane or propane mixtures. First, in order to investigate the ignition and flame-kernel development in quiescence, the minimum ignition energy MIE and the relationship between the flame radius and the burning velocity of meso-scale laminar flames are examined by using sequential schlieren photography in a constant volume vessel. Then, the properties of MIE are examined for three turbulence level. Additionally, the transition region of MIE could be summarized by using the proposed turbulent Karlovitz number based on the burning velocity of the meso-scale flame in quiescence.
Nakahara, Masaya, Matsushita, Yuki, Kishiura, Kensuke, Abe, Fumiaki, Tokunaga, Kenichi
CFD Analysis of Different Biogas Upgrading Levels for Dual-Fuel Operation in Diesel Engines2023-24-005508/28/2023
As the transportation sector continues to increase its energy demand and present stricter environmental regulations, the use of biofuels has been gaining more attention. Among them, one of the most promising options is biomethane - a methane-rich fuel produced from biogas upgrading. Despite presenting excellent combustion properties and composition comparable to natural gas, this green fuel requires a proper biogas processing technology that may lead to a high final cost. On the other hand, the direct use of unprocessed biogas may cause operational issues in the engine, since it may present corrosive contaminants and a high CO2 concentration that affects the combustion and decrease storage efficiency. Therefore, a balance between upgrading level and good engine operation could lead a reliable engine performance without the need of high processing costs. In this sense, the present study aims to discuss the effect of different biogas upgrading levels over engine performance and pollutant
Zucareli de Souza, Túlio Augusto, Frez, Gustavo V., Pinto, Gabriel, Costa, Roberto, Roque, Luis Filipe A., Coronado, Christian J. R., Vidigal, Luís Pedro V.
Fuel Stratification to Improve the Lean Limit in a Methane-Fueled Heavy-Duty Spark-Ignition Optical Engine2023-24-004508/28/2023
Natural gas is an attractive fuel for heavy-duty internal combustion engines as it has the potential to reduce CO2, particulate, and NOx emissions. This study reports optical investigations on the effect of methane stratification at lean combustion conditions in a heavy-duty optical diesel engine converted to spark-ignition operation. The combination of the direct injector (DI) and port-fuel injectors (PFI) fueling allows different levels of in-cylinder fuel stratification. The engine was operated in skip-firing mode, and high-speed natural combustion luminosity color images were recorded using a high-speed color camera from the bottom view, along with in-cylinder pressure measurements. The results from methane combustion based on port-fuel injections indicate the lean burn limit at λ = 1.4. To improve the lean limit of methane combustion, fuel stratification is introduced into the mixture using direct injections. Two different volume fractions of direct injections (20% and 40% by
Panthi, Niraj, Sharma, Priybrat, Magnotti, Gaetano
Effects of Engine Speed on Prechamber-Assisted Combustion2023-24-002008/28/2023
Lean combustion technologies show promise for improving engine efficiency and reducing emissions. Among these technologies, prechamber-assisted combustion (PCC) is established as a reliable option for achieving lean or ultra-lean combustion. In this study, the effect of engine speed on PCC was investigated in a naturally aspirated heavy-duty optical engine: a comparison has been made between analytical performances and optical flame behavior. Bottom view natural flame luminosity (NFL) imaging was used to observe the combustion process. The prechamber was fueled with methane, while the main chamber was fueled with methanol. The engine speed was varied at 1000, 1100, and 1200 revolutions per minute (rpm). The combustion in the prechamber is not affected by changes in engine speed. However, the heat release rate (HRR) in the main chamber changed from two distinct stages with a faster first stage to more gradual and merged stages as the engine speed increased. NFL imaging revealed that
Palombi, Lucia, Sharma, Priybrat, Cenker, Emre, Magnotti, Gaetano
Repetitive Multi-pulses Enabling Lean CH 4 -Air Combustion Using Surface Discharges03-16-08-006106/20/2023
The development of efficient and reliable ignition systems for lean fuel-air mixtures is of great interest for applications associated with the use of combustion in transportation, electricity production, and other heavy industries. In this study, we report the use of repetitive nanosecond pulsed surface discharges for the ignition of lean methane (CH4)-air mixtures at pressures above 1 bar. Powered by ten 10-ns voltage pulses at 10 kHz, a commercially available non-resistive spark plug was used to generate surface discharges, which were able to ignite CH4-air mixtures at 1.5 bar and with equivalence ratios (ϕ) ranging from 1.0 to 0.5. At the leanest conditions, e.g., ϕ ≤ 0.6, nitric oxide (NO) and nitrogen dioxide (NO2) emission were reduced to <10% of their values at ϕ = 1.0, demonstrating the advantage of lean burn in emission reduction. Consistent ignition was obtained under extremely lean conditions (e.g., ϕ = 0.5) with a minimum of five pulses and a minimum Coulomb transfer of 82
Umstattd, Ryan J., Jiang, Chunqi
Ignition Characteristics of Dielectric Barrier Discharge Ignition System under Elevated Pressure and Temperature in Rapid Compression and Expansion Machine03-16-08-006006/15/2023
A rapid compression and expansion machine (RCEM) was used to experimentally investigate the ignition phenomena of dielectric-barrier discharge (DBD) in engine conditions. The effect of elevated pressure and temperature on ignition phenomena of a methane/air premixed mixture was investigated using a DBD igniter. The equivalence ratio was changed to elucidate the impact of DBD on flame kernel development. High-speed imaging of natural light and OH* chemiluminescence enabled visualization of discharges and flame kernel. According to experimental findings, the discharges become concentrated and the intensity increases as the pressure and temperature rise. Under different equivalence ratios, the spark ignition (SI) system has a shorter flame development time (FDT) as compared with the DBD ignition system.
Agrawal, Saurabh, Yamamoto, Shuya, Horibe, Naoto, Hayashi, Jun, Kawanabe, Hiroshi
Active Plasma Probing for Lean Burn Flame Detection2023-01-029304/11/2023
Combustion diagnostics of highly diluted mixtures are essential for the estimation of the combustion quality, and control of combustion timing in advanced combustion systems. In this paper, a novel fast response flame detection technique based on active plasma is introduced and investigated. Different from the conventional ion current sensing used in internal combustion engines, a separate electrode gap is used in the detecting probing. Further, the detecting voltage across the electrode gap is modulated actively using a multi-coil system to be slightly below the breakdown threshold before flame arrival. Once the flame front arrives at the probe, the ions on the flame front tend to decrease the breakdown voltage threshold and trigger a breakdown event. Simultaneous electrical and optical measurements are employed to investigate the flame detecting efficacy via active plasma probing under both quiescent and flow conditions. The RT-FPGA system provides flexible, prompt, and precise
Wang, Linyan, Yu, Xiao, Cong, Binghao, Li, Liguang, Chen, Guangyun, Zheng, Ming
Performance and Emission Characteristics of Direct Injection DME Combustion under Low NOx Emissions2023-01-032704/11/2023
Compression ignition internal combustion engines provide unmatched power density levels, making them suitable for numerous applications including heavy-duty freight trucks, marine shipping, and off-road construction vehicles. Fossil-derived diesel fuel has dominated the energy source for CI engines over the last century. To mitigate the dependency on fossil fuels and lessen anthropogenic carbon released into the atmosphere within the transportation sector, it is critical to establish a fuel source which is produced from renewable energy sources, all the while matching the high-power density demands of various applications. Dimethyl ether (DME) has been used in non-combustion applications for several decades and is an attractive fuel for CI engines because of its high reactivity, superior volatility to diesel, and low soot tendency. A range of feedstock sources can produce DME via the catalysis of syngas. In this work, DME is applied in a direct injection compression ignition combustion
Leblanc, Simon, M, Murugesa Pandian, Han, Xiaoye, Tjong, Jimi, Zheng, Ming
Experimental and Modeling Study on the Thermal Aging Impact on the Performance of the Natural Gas Three-Way Catalyst2023-01-037504/11/2023
The prediction accuracy of a three-way catalyst (TWC) model is highly associated with the ability of the model to incorporate the reaction kinetics of the emission process as a lambda function. In this study, we investigated the O2 and H2 concentration profiles of TWC reactions and used them as critical inputs for the development of a global TWC model. We presented the experimental data and global kinetic model showing the impact of thermal degradation on the performance of the TWC. The performance metrics investigated in this study included CH4, NOx, and CO conversions under lean, rich, and dithering light-off conditions to determine the kinetics of oxidation reactions and reduction/reforming/water-gas shift reactions as a function of thermal aging. The O2 and H2 concentrations were measured using mass spectrometry to track the change in the oxidation state of the catalyst and to determine the mechanism of the reactions under these light-off conditions. The experimental data indicate
Kim, Mi-Young, Dadi, Rama Krishna, Gong, Jian, Kamasamudram, Krishna
Investigation of Premixed Fuel Composition and Pilot Reactivity Impact on Diesel Pilot Ignition in a Single-Cylinder Compression Ignition Engine2023-01-028204/11/2023
This work experimentally investigates the impact of premixed fuel composition (methane/ethane, methane/propane, and methane/hydrogen mixtures having equivalent chemical energy) and pilot reactivity (cetane number) on diesel-pilot injection (DPI) combustion performance and emissions, with an emphasis on the pilot ignition delay (ID). To support the experimental pilot ignition delay trends, an analysis technique known as Mixing Line Concept (MLC) was adopted, where the cold diesel surrogate and hot premixed charge are envisioned to mix in a 0-D constant volume reactor to account for DPI mixture stratification. The results show that the dominant effect on pilot ignition is the pilot fuel cetane number, and that the premixed fuel composition plays a minor role. There is some indication of a physical effect on ignition for cases containing premixed hydrogen. The results also show that the HC and CO emissions for the methane/ethane and methane/propane mixtures decrease despite an increase in
Tyrewala, Daanish, Rothamer, David, Ghandhi, J.
Effective Ignition of Lean Methane/Hydrogen Mixture in a Rapid Compression Machine2023-01-025504/11/2023
The use of renewable natural gas and green hydrogen can significantly reduce the carbon footprint of engines. For future spark ignition engines, lean burn strategy and high compression ratio need to be adopted to further improve thermal efficiency, reducing energy consumption. The efficacy of the ignition system is essential to initiate self-sustainable flame under those extreme conditions. In this work, a rapid compression machine is employed to compress air-fuel mixture to engine-like boundary conditions before the spark event to experimentally investigate the ignition and combustion characteristics of the methane-air mixtures under extreme lean conditions. Hydrogen is also added to support the ignition process and enhance flame propagation speed. Lean methane-air mixtures with excess air ratio up to 2.8 are used, with 10 vol% hydrogen addition into the methane fuel. The ignition criteria under various ignition strategies are explored. Both in-cylinder pressure and high-speed direct
Yu, Xiao, Jin, Long, Reader, Graham, Wang, Meiping, Zheng, Ming
AI Super-Resolution-Based Subfilter Modeling for Finite-Rate-Chemistry Flows: A Jet Flow Case Study2023-01-020004/11/2023
Large-eddy simulation (LES) can be a very important tool to support and accelerate the energy transition to green technologies and thus play a significant role in the fight against climate change. However, especially LES of reactive flows is still challenging, e.g., with respect to emission prediction, and perfect subfilter models do not yet exist. Recently, new subfilter models based on physics-informed generative adversarial networks (GANs), called physics-informed enhanced super-resolution GANs (PIESRGANs), have been developed and successfully applied to a wide range of flows, including decaying turbulence, sprays, and finite-rate-chemistry flows. This technique, based on AI super-resolution, allows for the systematic derivation of accurate subfilter models from direct numerical simulation (DNS) data, which is critical, e.g., for the development of efficient energy devices based on advanced fuels. This paper describes a case study demonstrating PIESRGANA for a finite-rate chemical
Bode, Mathis
Analysis of Combustion Cycle-to-Cycle Variation in an Optical Single Cylinder Dual-Fuel Engine2023-01-027904/11/2023
This study aims to improve the dual fuel combustion for low/zero carbon fuels. Seven cases were tested in a single cylinder optical engine and their ignition and combustion characteristics are compared. The baseline case is the conventional diesel combustion. Four cases are diesel-gas (compressed natural gas) dual-fuel combustion operations, and two cases are diesel-hythane combustion. The diesel fuel injection process was visualized by a high-speed copper vapour laser. The combustion processes were recorded with a high-speed camera at 10000 Hz with an engine speed of 1200 rpm. The high-speed recordings for each case included 22 engine cycles and were postprocessed to create one spatial overlapped average combustion image. The average combustion cycle images were then further thresholded and these images were then used in a new method to analyze the cycle-to-cycle variation in a dimensionless, for all cases comparable value. Furthermore, the ignition delay and heat release profile of
Lauterkorn, Alexander Michael, Wang, Xinyan, Zhao, Hua
Operation of a Natural Gas Direct Injection Compression Ignition Single Cylinder Research Engine2023-01-026004/11/2023
The medium and heavy-duty powertrain industry trend is to reduce reliance on diesel fuel and is aligned with continued efforts of achieving ultra-low emissions and high brake efficiencies. Compression Ignition (CI) of late cycle Directly Injected (DI) Natural Gas (NG) shows the potential to match diesel performance in terms of brake efficiency and power density, with the benefit of utilizing a lower carbon content fuel. A primary challenge is to achieve stable ignition of directly injected NG over a wide engine speed and load range without the need for a separate ignition source. This project aims to demonstrate the CI of DI NG through experimental studies with a Single Cylinder Research Engine (SCRE), leading to the development of a mono-fueled NG engine with equivalent performance to that of current diesel technology, 25% lower CO2 emissions, and low engine out methane emissions. The SCRE has a single cylinder displacement of 2.5L and utilizes a high-pressure direct-injection gaseous
White, Tyler, Eggart, Brian, Naber, Jeffrey, Turcios, Marco, Singh, Ashish, Munshi, Sandeep
Enhanced Combustion by Photo Ignition of Carbon Nanotubes in a Constant Volume Chamber2023-01-040604/11/2023
Using ammonia as fuel in retrofitted large marine vessels or heavy-duty vehicles has the potential to reduce CO2 emissions. However, ammonia is hard to burn in an internal combustion engine (ICE) due to its poor combustion properties, i.e. having high autoignition temperatures and low flame speeds. This results in the need for a highly reactive secondary fuel or an improved ignition system for achieving complete and stable combustion. This study investigates a radical technology for the ignition of a fuel-air mixture using carbon nanotubes. The technology consists of injecting a mixture of multi-walled carbon nanotubes and ferrocene (CNT-Fe) into a fuel-air mixture and subjecting the particles to a bright flash of light. Due to the photochemical properties of CNT-Fe particles, the absorbed light initiates ignition. The burning particles thereby ignite the gas mixture at multiple points in the chamber, resulting in a flame front propagating faster compared to when using conventional
Bjorgen, Karl Oskar Pires, Saanum, Inge, Bratsberg, Stian, Jørgensen, Patrick, Lovas, Terese, Emberson, David
Jet Characteristics of a Narrow Throat Pre-Chamber and Influence on the Main-Chamber Combustion2022-01-100608/30/2022
Lean combustion is one of the most applied methods to increase engine efficiency and maintain a good trade-off with engine emissions. The pre-chamber combustion (PCC) is one of the most promising combustion concepts to extend the lean operating limits of the engine. The Narrow throat pre-chamber has shown better lean limit extension compared to other ignition sources. The pre-chamber jets and the main-chamber combustion were studied in a Heavy-Duty optical engine using methane fuel. The tested conditions covered global excess air ratios (λ), between 1.9 to 2.3. The combustion process was recorded using three collection systems: (a) Natural Flame Luminosity (NFL) with a temporal resolution of 0.1 CAD; (b) OH* Chemiluminescence, and (c) CH* Chemiluminescence with a temporal resolution of 0.2 CAD for both. The propagating velocity of the reacting jets was studied using Combustion Image Velocimetry (CIV) based on bottom view images of the main chamber. After the pre-chamber jets ignite the
Echeverri Marquez, Manuel, Sharma, Priybrat, Hlaing, Ponnya, Cenker, Emre, Magnotti, Gaetano, Turner, James
Knock Resistance Evaluation of Methane-Based Two-Component Gases by Combustion Visualization and Analysis using RCEM2022-01-106008/30/2022
Gaseous fuel originated from natural gas (NG) has been affected by industrial fields thanks to its low emission feature. The excellent knock resistance of methane, a major component of NG, is another advantage in engine applications, but the composition of NG varies depending on the production region. Methane number (MN) has been widely used to evaluate the knock resistance of certain NG. However, the selection of a reliable knock-resisting index has not been settled because of several definitions of MN, and a new index called the propane knock index was recently proposed. Moreover, the proper index could change with types of gas engines. In this study, a rapid compression-and-expansion machine (RCEM) was prepared to reproduce in-cylinder conditions and combustion processes of a pre-chamber type medium-speed gas engine, and the knocking-like combustion was intentionally generated by setting compression pressure, ignition timing, and fuel density in the mixture to the proper level. The
Wakasugi, Takuya, Tashima, Hiroshi, Tsuru, Daisuke
CFD Analysis of Different Methane/Hydrogen Blends in a CI Engine Operating in Dual Fuel Mode2022-01-105608/30/2022
Nowadays, the stricter regulations in terms of emissions have limited the use of diesel engines on urban roads. On the contrary, for marine and off-road applications the diesel engine still represents the most feasible solution for work production. In the last decades, dual fuel operation with methane supply has been widely investigated. Starting from previous studies on a research engine, where diesel-methane dual fuel combustion has been deepened both experimentally and numerically with the aid of a CFD code, the authors implemented and tested a kinetic mechanism. It is obtained from the combination of the well-established GRIMECH 3.0 and a detailed scheme for a diesel surrogate oxidation. Moreover, the Autoignition-Induced Flame Propagation model, included in the ANSYS Forte® software, is applied because it can be considered the most appropriate model to describe dual fuel combustion. However, the higher emissions of unburned hydrocarbons have pushed researchers to move towards a
De Robbio, Roberta, Cameretti, Maria Cristina, Mancaruso, Ezio, Tuccillo, Raffaele, Vaglieco, Bianca Maria
Comparing Unburned Fuel Emission from a Pre-chamber Engine Operating on Alcohol Fuels using FID and FTIR Analyzers2022-01-109408/30/2022
Typical automotive emission testing systems usually employ Flame Ionization Detection (FID) analyzers to measure unburned fuel species in the exhaust, but the technique is not suitable for engines operating on alcohol fuels. The FID method is not sensitive to measuring unburned alcohol fuels due to the presence of oxygen bonds in the fuel molecule. Other techniques, such as Fourier Transform Infrared (FTIR), can provide accurate unburned fuel measurements with alcohol fuel. However, these techniques are expensive and are less accessible compared to FID analyzers. In this study, the unburned fuel emissions from the engine exhaust were measured simultaneously with FID and FTIR analyzers, with the engine operating on pure alcohols, which are methanol, ethanol, and n-butanol. While most previous work focuses on stoichiometric air-fuel mixtures, a wide range of lean operating conditions between global-λ 1.6 to 2.8 will be tested in this study. Such ultra-lean operation was achievable thanks
Hlaing, Ponnya, Said, Ahmed, Cenker, Emre, Im, Hong G., Turner, James
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