Effect of Lewis number on ball-like lean limit flames

KAUST Repository

Zhou, Zhen

2017-10-13

The lean limit flames for three different fuel compositions premixed with air, representing three different mixture Lewis numbers, stabilized inside a tube in a downward flow are examined by experiments and numerical simulations. The CH* chemiluminescence distribution in CH4–air and CH4–H2–air flames and the OH* chemiluminescence distribution in H2–air flames are recorded in the experiments. Cell-like flames are observed for the CH4–air mixture for all tested equivalence ratios. However, for CH4–H2–air and H2–air flames, ball-like lean limit flames are observed. Flame temperature fields are measured using Rayleigh scattering. The experimentally observed lean limit flames are predicted qualitatively by numerical simulation with the mixture-averaged transport model and skeletal mechanism of CH4. The results of the simulations show that the entire lean limit flames of CH4–H2–air and H2–air mixtures are located inside a recirculation zone. However, for the lean limit CH4–air flame, only the leading edge is located inside the recirculation zone. A flame structure with negative flame displacement speed is observed for the leading edges of the predicted lean limit flames with all three different fuel compositions. As compared with 1D planar flames, the fuel transport caused by convection is less significant in the present 2D lean limit flames for the three different fuel compositions. For the trailing edges of the three predicted lean limit flames, a diffusion dominated flame structure is observed.

Combustion and emissions control in diesel-methane dual fuel engines: The effects of methane supply method combined with variable in-cylinder charge bulk motion

International Nuclear Information System (INIS)

Carlucci, Antonio P.; Laforgia, Domenico; Saracino, Roberto; Toto, Giuseppe

2011-01-01

Highlights: → We studied dual fuel combustion in diesel engines. → Bulk flow structure of in-cylinder charge and methane supply method were investigated. → Swirl charge motion is capable to enhance air-methane mixture oxidation at low loads. → Methane port injection is capable to reduce unburned hydrocarbons and nitric oxides. - Abstract: In this paper, the results of an extensive experimental campaign about dual fuel combustion development and the related pollutant emissions are reported, paying particular attention to the effect of both the in-cylinder charge bulk motion and methane supply method. A diesel common rail research engine was converted to operate in dual fuel mode and, by activating/deactivating the two different inlet valves of the engine (i.e. swirl and tumble), three different bulk flow structures of the charge were induced inside the cylinder. A methane port injection method was proposed, in which the gaseous fuel was injected into the inlet duct very close to the intake valves, in order to obtain a stratified-like air-fuel mixture up to the end of the compression stroke. For comparison purposes, a homogeneous-like air-fuel mixture was obtained injecting methane more upstream the intake line. Combining the different positions of the methane injector and the three possible bulk flow structures, seven different engine inlet setup were tested. In this way, it was possible to evaluate the effects on dual fuel combustion due to the interaction between methane injector position and charge bulk motion. In addition, methane injection pressure and diesel pilot injection parameters were varied setting the engine at two operating conditions. For some interesting low load tests, the combustion development was studied more in detail by means of direct observation of the process, using an in-cylinder endoscope and a digital CCD camera. Each combustion image was post-processed by a dedicated software, in order to extract only those portions with flame

Sensitivity, stability, and precision of quantitative Ns-LIBS-based fuel-air-ratio measurements for methane-air flames at 1-11 bar.

Science.gov (United States)

Hsu, Paul S; Gragston, Mark; Wu, Yue; Zhang, Zhili; Patnaik, Anil K; Kiefer, Johannes; Roy, Sukesh; Gord, James R

2016-10-01

Nanosecond laser-induced breakdown spectroscopy (ns-LIBS) is employed for quantitative local fuel-air (F/A) ratio (i.e., ratio of actual fuel-to-oxidizer mass over ratio of fuel-to-oxidizer mass at stoichiometry, measurements in well-characterized methane-air flames at pressures of 1-11 bar). We selected nitrogen and hydrogen atomic-emission lines at 568 nm and 656 nm, respectively, to establish a correlation between the line intensities and the F/A ratio. We have investigated the effects of laser-pulse energy, camera gate delay, and pressure on the sensitivity, stability, and precision of the quantitative ns-LIBS F/A ratio measurements. We determined the optimal laser energy and camera gate delay for each pressure condition and found that measurement stability and precision are degraded with an increase in pressure. We have identified primary limitations of the F/A ratio measurement employing ns-LIBS at elevated pressures as instabilities caused by the higher density laser-induced plasma and the presence of the higher level of soot. Potential improvements are suggested.

New optical method for heat flux measurements in stagnation point laminar methane/air flames and hydrogen/methane/air flames using thermographic phosphors

Energy Technology Data Exchange (ETDEWEB)

Elmnefi, Mohamed Salem

2010-11-24

In the present study, a new optical method was implemented to study the heat transfer from flat stagnation point flames which can be regarded as one-dimensional in the central part. Premixed methane-air flames and hydrogen-methane-air flames were investigated. The effects of burner-to-plate distance and the fresh gas mixture velocity on heat transfer were examined. Experiments were performed using light induced phosphorescence from thermographic phosphors to study the wall temperatures and heat fluxes of nearly one-dimensional flat premixed flames impinging upward normally on a horizontal water cooled circular flat plate. The investigated flames were stoichiometric, lean and rich laminar methane/air flames with different equivalence ratios of {phi} =1, {phi} = 0.75 and {phi} = 1.25 and stoichiometric laminar hydrogen/methane/air flames. Mixtures of air with 10, 25, 50 and 75 % hydrogen in methane (CH{sub 4}) as well as a pure hydrogen flames at ambient pressure were investigated. The central part of this plate was an alumina ceramic plate coated from both sides with chromium doped alumina (ruby) and excited with a Nd:YAG laser or a green light emitting diode (LED) array to measure the wall temperature from both sides and thus the heat flux rate from the flame. The outlet velocity of the gases was varied from 0.1 m/s to 1.2 m/s. The burner to plate distance ranged from 0.5 to 2 times the burner exit diameter (d = 30 mm).The accuracy of the method was evaluated. The measured heat flux indicate the change of the flame stabilization mechanism from a burner stabilized to a stagnation plate stabilized flame. The results were compared to modeling results of a one dimensional stagnation point flow, with a detailed reaction mechanism. In order to prove the model, also measured gas phase temperatures by OH LIF for a stoichiometric stagnation point flame were discussed. It turns out that the flame stabilization mechanism and with it the heat fluxes change from low to high

Development of air fuel ratio sensor; A/F sensor no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Sakawa, T; Hori, M [Denso Corp., Aichi (Japan); Nakamura, Y [Toyota Motor Corp., Aichi (Japan)

1997-10-01

The Air Fuel Ratio Sensor (A/F sensor), which is applied to a 1997 model year Low Emission Vehicle (LEV) was developed. This sensor enables the detection of the exhaust gas air fuel ratio, both lean and rich of stoichiometric. It has an effective air fuel ratio range from 12 to 18 as required for LEV regulation. It has the fast light off, - within 20 seconds - to minimize exhaust hydrocarbon content. Further, it has fast response time, less than 200 msec, to improve the air fuel ratio controllability. 3 refs., 7 figs.

Characterization of laser-induced ignition of biogas-air mixtures

International Nuclear Information System (INIS)

Forsich, Christian; Lackner, Maximilian; Winter, Franz; Kopecek, Herbert; Wintner, Ernst

2004-01-01

Fuel-rich to fuel-lean biogas-air mixtures were ignited by a Nd:YAG laser at initial pressures of up to 3 MPa and compared to the ignition of methane-air mixtures. The investigations were performed in a constant volume vessel heatable up to 473 K. An InGaAsSb/AlGaAsSb quantum well ridge diode laser operating at 2.55 μm was used to track the generation of water in the vicinity of the laser spark in a semi-quantitative manner. Additionally, the flame emissions during the ignition process were recorded and a gas inhomogeneity index was deduced. Laser-induced ignition and its accompanying effects could be characterized on a time scale spanning four orders of magnitude. The presence of CO 2 in the biogas reduces the burning velocity. The flame emissions result in a much higher intensity for methane than it was the case during biogas ignition. This knowledge concludes that engines fuelled with biogas ultimately affect the performance of the process in a different way than with methane. Methane-air mixtures can be utilized in internal combustion engines with a higher air-fuel ratio than biogas. Comparing failed laser-induced ignition of methane-air and biogas-air mixtures similar results were obtained. The three parameters water absorbance, flame emission and the gas inhomogeneity index constitute a suitable tool for judging the quality of laser-induced ignition of hydrocarbon-air mixtures at elevated pressures and temperatures as encountered in internal combustion engines

A Simulation of the Effects of Varying Repetition Rate and Pulse Width of Nanosecond Discharges on Premixed Lean Methane-Air Combustion

Directory of Open Access Journals (Sweden)

Moon Soo Bak

2012-01-01

Full Text Available Two-dimensional kinetic simulation has been carried out to investigate the effects of repetition rate and pulse width of nanosecond repetitively pulsed discharges on stabilizing premixed lean methane-air combustion. The repetition rate and pulse width are varied from 10 kHz to 50 kHz and from 9 ns to 2 ns while the total power is kept constant. The lower repetition rates provide larger amounts of radicals such as O, H, and OH. However, the effect on stabilization is found to be the same for all of the tested repetition rates. The shorter pulse width is found to favor the production of species in higher electronic states, but the varying effects on stabilization are also found to be small. Our results indicate that the total deposited power is the critical element that determines the extent of stabilization over this range of discharge properties studied.

Effect of pressure on the lean limit flames of H2-CH4-air mixture in tubes

KAUST Repository

Zhou, Zhen; Shoshin, Yuriy; Hernandez Perez, Francisco; van Oijen, Jeroen A.; de Goey, Laurentius P.H.

2017-01-01

The lean limit flames of H2-CH4-air mixtures stabilized inside tubes in a downward flow are experimentally and numerically investigated at elevated pressures ranging from 2 to 5 bar. For the shapes of lean limit flames, a change from ball-like flame to cap-like flame is experimentally observed with the increase of pressure. This experimentally observed phenomenon is qualitatively predicted by numerical simulations. The structure of ball-like and cap-like lean limit flames at all tested pressures is analysed in detail based on the numerical predictions. The results show that the lean limit flames are located inside a recirculation zone at all tested pressures. For the leading edges of the lean limit flames at all tested pressures, the fuel transport is controlled by both convection and diffusion. For the trailing edge of the ball-like lean limit flame at 2 bar, the fuel transport is dominated by diffusion. However, with increasing pressure, the transport contribution caused by convection in the trailing edges of the lean limit flames increases. Finally, the influence of transport and chemistry on the predicted ultra lean flames and lean flammability limit is analysed at elevated pressures.

Effect of pressure on the lean limit flames of H2-CH4-air mixture in tubes

KAUST Repository

Zhou, Zhen

2017-05-25

The lean limit flames of H2-CH4-air mixtures stabilized inside tubes in a downward flow are experimentally and numerically investigated at elevated pressures ranging from 2 to 5 bar. For the shapes of lean limit flames, a change from ball-like flame to cap-like flame is experimentally observed with the increase of pressure. This experimentally observed phenomenon is qualitatively predicted by numerical simulations. The structure of ball-like and cap-like lean limit flames at all tested pressures is analysed in detail based on the numerical predictions. The results show that the lean limit flames are located inside a recirculation zone at all tested pressures. For the leading edges of the lean limit flames at all tested pressures, the fuel transport is controlled by both convection and diffusion. For the trailing edge of the ball-like lean limit flame at 2 bar, the fuel transport is dominated by diffusion. However, with increasing pressure, the transport contribution caused by convection in the trailing edges of the lean limit flames increases. Finally, the influence of transport and chemistry on the predicted ultra lean flames and lean flammability limit is analysed at elevated pressures.

On the Experimental and Theoretical Investigations of Lean Partially Premixed Combustion, Burning Speed, Flame Instability and Plasma Formation of Alternative Fuels at High Temperatures and Pressures

Science.gov (United States)

Askari, Omid

This dissertation investigates the combustion and injection fundamental characteristics of different alternative fuels both experimentally and theoretically. The subjects such as lean partially premixed combustion of methane/hydrogen/air/diluent, methane high pressure direct-injection, thermal plasma formation, thermodynamic properties of hydrocarbon/air mixtures at high temperatures, laminar flames and flame morphology of synthetic gas (syngas) and Gas-to-Liquid (GTL) fuels were extensively studied in this work. These subjects will be summarized in three following paragraphs. The fundamentals of spray and partially premixed combustion characteristics of directly injected methane in a constant volume combustion chamber have been experimentally studied. The injected fuel jet generates turbulence in the vessel and forms a turbulent heterogeneous fuel-air mixture in the vessel, similar to that in a Compressed Natural Gas (CNG) Direct-Injection (DI) engines. The effect of different characteristics parameters such as spark delay time, stratification ratio, turbulence intensity, fuel injection pressure, chamber pressure, chamber temperature, Exhaust Gas recirculation (EGR) addition, hydrogen addition and equivalence ratio on flame propagation and emission concentrations were analyzed. As a part of this work and for the purpose of control and calibration of high pressure injector, spray development and characteristics including spray tip penetration, spray cone angle and overall equivalence ratio were evaluated under a wide range of fuel injection pressures of 30 to 90 atm and different chamber pressures of 1 to 5 atm. Thermodynamic properties of hydrocarbon/air plasma mixtures at ultra-high temperatures must be precisely calculated due to important influence on the flame kernel formation and propagation in combusting flows and spark discharge applications. A new algorithm based on the statistical thermodynamics was developed to calculate the ultra-high temperature plasma

Mensuration of the propagation speed of mixed flames of Methane-air and gas natural, Guajira - air using the method of the angle of the cone

International Nuclear Information System (INIS)

Benjumea Hernandez, Pedro Nel; Higuita Bedoya Carlos Mario; Cordoba Perez, Camilo Andres

2004-01-01

In this work, the burning velocity of premixed laminar flames of methane-air and Guajira natural gas-air mixtures was measured by the cone's angle method using a cylindrical Bunsen burner. In the development of the experiments, a fuel concentration in the fuel-air mixture ranging from 9% -11% was taken. The maximum value of the burning velocity was obtained for mixtures a little bit richer than the stoichiometric case. For methane, this flame velocity was 44.1 cm/s and for the Guajira natural gas was 43.1 cm/s. From the results, it was possible to see that the Guajira natural gas inert content led to a burning velocity value lesser than the methane's, in spite of the Guajira natural gas having a higher heavy hydrocarbon content. Methane burning velocity values following similar trends to those reported by the literature were obtained. The systematic error found in the results is mainly a consequence of inaccuracies in the method used to measure the fuel-gas mixture velocity at the burner exit

Methane-fueled vehicles: A promising market for coalbed methane

International Nuclear Information System (INIS)

Deul, M.

1993-01-01

The most acceptable alternative fuel for motor vehicles is compressed natural gas (CNG). An important potential source of such gas is coalbed methane, much of which is now being wasted. Although there are no technological impediments to the use of CNG it has not been adequately promoted for a variety of reasons: structural, institutional and for coalbed gas, legal. The benefits of using CNG fuel are manifold: clean burning, low cost, abundant, and usable in any internal combustion engine. Even though more than 30,000 CNG vehicles are now in use in the U.S.A., they are not readily available, fueling stations are not easily accessible, and there is general apathy on the part of the public because of negligence by such agencies as the Department of Energy, the Department of Transportation and the Environmental Protection Agency. The economic benefits of using methane are significant: 100,000 cubic feet of methane is equivalent to 800 gallons of gasoline. Considering the many millions of cubic feet methane wasted from coal mines conservation and use of this resource is a worthy national goal

Autoignited laminar lifted flames of methane/hydrogen mixtures in heated coflow air

KAUST Repository

Choi, Byungchul; Chung, Suk-Ho

2012-01-01

Autoignited lifted flame behavior in laminar jets of methane/hydrogen mixture fuels has been investigated experimentally in heated coflow air. Three regimes of autoignited lifted flames were identified depending on initial temperature and hydrogen

Lean Gasoline System Development for Fuel Efficient Small Cars

Energy Technology Data Exchange (ETDEWEB)

Smith, Stuart R. [General Motors LLC, Pontiac, MI (United States)

2013-11-25

The General Motors and DOE cooperative agreement program DE-EE0003379 is completed. The program has integrated and demonstrated a lean-stratified gasoline engine, a lean aftertreatment system, a 12V Stop/Start system and an Active Thermal Management system along with the necessary controls that significantly improves fuel efficiency for small cars. The fuel economy objective of an increase of 25% over a 2010 Chevrolet Malibu and the emission objective of EPA T2B2 compliance have been accomplished. A brief review of the program, summarized from the narrative is: The program accelerates development and synergistic integration of four cost competitive technologies to improve fuel economy of a light-duty vehicle by at least 25% while meeting Tier 2 Bin 2 emissions standards. These technologies can be broadly implemented across the U.S. light-duty vehicle product line between 2015 and 2025 and are compatible with future and renewable biofuels. The technologies in this program are: lean combustion, innovative passive selective catalyst reduction lean aftertreatment, 12V stop/start and active thermal management. The technologies will be calibrated in a 2010 Chevrolet Malibu mid-size sedan for final fuel economy demonstration.

Burning low volatile fuel in tangentially fired furnaces with fuel rich/lean burners

International Nuclear Information System (INIS)

Wei Xiaolin; Xu Tongmo; Hui Shien

2004-01-01

Pulverized coal combustion in tangentially fired furnaces with fuel rich/lean burners was investigated for three low volatile coals. The burners were operated under the conditions with varied value N d , which means the ratio of coal concentration of the fuel rich stream to that of the fuel lean stream. The wall temperature distributions in various positions were measured and analyzed. The carbon content in the char and NO x emission were detected under various conditions. The new burners with fuel rich/lean streams were utilized in a thermal power station to burn low volatile coal. The results show that the N d value has significant influences on the distributions of temperature and char burnout. There exists an optimal N d value under which the carbon content in the char and the NO x emission is relatively low. The coal ignition and NO x emission in the utilized power station are improved after retrofitting the burners

EFFECTS OF SIMPLIFIED CHEMICAL KINETIC MODEL ON THE MICRO-FLAME STRUCTURE AND TEMPERATURE OF THE LEAN PREMIXED METHANE-AIR MIXTURES

Directory of Open Access Journals (Sweden)

JUNJIE CHEN

2015-07-01

Full Text Available The effect of simplified chemical kinetic model on the micro-flame structure, central axis and wall temperatures were investigated with different one-step global chemical kinetic mechanisms following Mantel, Duterque and Fernández-Tarrazo models. Numerical investigations of the premixed methane-air flame in the micro-channel and lean conditions were carried out to compare and analyze the effect of the comprehensive chemical kinetic mechanisms. The results indicate that one-step global chemical kinetic mechanism affects both the micro-flame shape and the combustion temperature. Among three simulation models, Mantel model allows a stable micro-flame with a bamboo shoot form, which anchor at the inlet. Duterque model gives a stable elongated micro-flame with a considerable ignition delay, and a dead zone with fluid accumulation is observed at the entrance, which may explain the very high combustion temperature and the fast reaction rate obtained, despite the micro-flame development presents a very hot spot and causes a broadening of the combustion zone. Fernández-Tarrazo model results in a rapid extinction and doesn't seem to take all the kinetic behavior into account for the appropriate micro-combustion simulations.

Investigation of fuel lean reburning process in a 1.5 MW boiler

International Nuclear Information System (INIS)

Kim, Hak Young; Baek, Seung Wook; Kim, Se Won

2012-01-01

Highlights: → We examine a detailed study of fuel lean reburning process in a 1.5 MW gas-fired boiler. → Experimental and numerical researches are conducted. → We investigate change in the level of NO X and CO emission. → The recirculation flow is important in the fuel lean reburning process. -- Abstract: This paper examines a detailed study of fuel lean reburning process applied to a 1.5 MW gas-fired boiler. Experimental and numerical studies were carried out to investigate the effect of the fuel lean reburning process on the NO X reduction and CO emission. Natural gas (CH 4 ) was used as the reburn as well as the main fuel. The amount of the reburn fuel, injection location and thermal load of boiler were considered as experimental parameters. The flue gas data revealed that the fuel lean reburning process led to NO X reduction up to 43%, while CO emission was limited to less than 30 ppm for the 100% thermal load condition. The commercial computational fluid dynamics code FLUENT 6.3, which included turbulence, chemical reaction, radiation and NO modeling, was used to predict the fluid flow and heat transfer characteristics under various operational conditions in the boiler. Subsequently, predicted results were validated with available measured data such as gas temperature distributions and local mean NO X concentrations. The detailed numerical results showed that the recirculation flow developed inside the boiler was found to play an important role in improving the effectiveness of fuel lean reburning process.

Methane emissions and climate compatibility of fossil fuels

International Nuclear Information System (INIS)

Meier, B.

1992-01-01

Methane contributes directly and indirectly to the additional greenhouse effect caused by human activities. The vast majority of the anthropogenic methane release occurs worldwide in non-fossil sources such as rice cultivation, livestock operations, sanitary landfills and combustion of bio-mass. Methane emissions also occur during production, distribution and utilisation of fossil fuels. Also when considering the methane release and CO 2 -emissions of processes upstream of combustion, the ranking of environmental compatibility of natural gas, fuel oil and cool remains unchanged. Of all fossil fuels, natural gas contributes the least to the greenhouse effect. (orig.) [de

Enhanced Emission Performance and Fuel Efficiency for HD Methane Engines. Literature Study. Final Report

Energy Technology Data Exchange (ETDEWEB)

Broman, R.; Staalhammar, P.; Erlandsson, L.

2010-05-15

to change the combustion system from the Diesel-cycle to the Otto-cycle or to use the Diesel Dual Fuel (DDF) cycle which used a Diesel-like cycle. The Otto-cycle (spark ignited, SI) is the most common option when rebuilding a diesel engine to operate on methane. The Diesel dual fuelcycle can however offer some benefits since it uses Diesel injection for ignition of the methane/air mixture 'like a liquid' spark plug. Additionally, DDF systems can either use the original Diesel injectors together with injection of methane into the air intake, allowing use of methane and/or diesel for more flexibility, or employ a specially designed gas/Diesel injector, incorporating only a small range of Diesel injection which disable operating the engine on 100 % Diesel, but allows for more Diesel substitution by methane over the full operating range of the engine. The fuel used in methane fuelled engines is biomethane, compressed natural gas (CNG), liquefied natural gas (LNG) or liquefied biomethane (LBM). LNG/LBM is the preferred fuel for long haul trucks since it has significantly higher energy density implying smaller, but different gas cylinders on-board the vehicle. For vehicles operated in a local area, compressed methane gas might be the most suitable alternative. Other combinations of methane fuels could also be used as fuel within the transportation sector such as blends of fuels from fossil and renewable origin and hydrogen enriched natural gas, hythane (HCNG). A recent interest for Diesel dual fuel concepts has now appeared among stakeholders as an alternative or a complement to the conventional methane fuelled HD vehicles, underlined by the fact that differences in the actual mode of operation of vehicles will enhance advantages with various engine concepts. Compared to a SI methane fuelled engine a DDF concept could end up with better fuel efficiency using current engine technology. However, the potential for substitution of diesel with methane would be lower

Status and potential of bio-methane fuel

International Nuclear Information System (INIS)

2008-01-01

This document first indicates and describes the various bio-methane production processes which can be implemented on a short term (use of organic wastes or effluents), on a medium term (from energetic crops) and on a longer term (gasification). It discusses and assesses the potential production of bio-methane fuel from different sources and processes. It describes the steps of the production of bio-methane fuel from biogas, with notably biogas refinement to produce bio-methane through three processes (de-carbonation, desulfurization, dehydration). Cost productions are assessed. Expected technology advances are evoked. Finally, the authors outline the contribution of bio-methane in the limitation of greenhouse gas emissions in the transport sector

Impact of fuel composition on the recirculation zone structure and its role in lean premixed flame anchoring

KAUST Repository

Hong, Seunghyuck; Shanbhogue, Santosh J.; Ghoniem, Ahmed F.

2015-01-01

) and chemiluminescence measurements for C3H8/H2/air lean premixed flames stabilized in a backward-facing step combustor. Results show an intricate coupling between the flame anchoring and the RZ structure and length. For a fixed fuel composition, at relatively low

Utilizing methane from degassing as a fuel for furnaces of drying systems. [USSR

Energy Technology Data Exchange (ETDEWEB)

Matveev, V.I.; Telegin, A.K.

1984-10-01

The use is evaluated of methane from coal seam degassing in the Severnaya mine as a fuel for dryers in the Severnaya coal preparation plant in the USSR. Dryers used in the plant are equipped with PMZ-4TsR furnaces. Middlings (type Zh18 coal) with 30% ash content and 0.25 MJ/kg calorific value were used as a fuel. When dryers were fired with middlings moisture content in coal concentrate declined from 10.1% to 5.1%, system output amounted to 133 t/h. After plant modernization middlings were replaced with methane from coal seam degassing (methane content in the mixture with air ranged from 40 to 60%). Replacing middlings with methane increased dryer output from 133 to 203 t/h. Moisture content in dried coal was reduced from 11.8 to 4.8%. Repair cost decreased, environmental pollution caused by combustion also declined. Payback period amounted to 6 months.

Thermal Radiation Properties of Turbulent Lean Premixed Methane Air Flames

National Research Council Canada - National Science Library

Ji, Jun; Sivathanu, Y. R; Gore, J. P

2000-01-01

... of turbulent premixed flames. Reduced cooling airflows in lean premixed combustors, miniaturization of combustors, and the possible use of radiation sensors in combustion control schemes are some of the practical reasons...

Numerical study of laminar nonpremixed methane flames in coflow jets: Autoignited lifted flames with tribrachial edges and MILD combustion at elevated temperatures

KAUST Repository

M. Al-Noman, Saeed

2016-07-07

Autoignition characteristics of laminar nonpremixed methane jet flames in high-temperature coflow air are studied numerically. Several flame configurations are investigated by varying the initial temperature and fuel mole fraction. At a relatively low initial temperature, a non-autoignited nozzle-attached flame is simulated at relatively low jet velocity. When the initial temperature is higher than that required for autoignition, two regimes are investigated: an autoignited lifted flame with tribrachial edge structure and an autoignited lifted flame with Mild combustion. The autoignited lifted flame with tribrachial edge exhibited three branches: lean and rich premixed flame wings and a trailing diffusion flame. Characteristics of kinetic structure for autoignited lifted flames are discussed based on the kinetic structures of homogeneous autoignition and flame propagation of stoichiometric mixture. Results showed that a transition from autoignition to flame propagation modes occurs for reasonably stoichiometric mixtures. The autoignited lifted flame with Mild combustion occurs when methane fuel is highly diluted with nitrogen. The kinetic structure analysis shows that the characteristics of Mild combustion can be treated as an autoignited lean premixed lifted flame. Transition behavior from Mild combustion to nozzle-attached flame was investigated by increasing the fuel mole fraction. As the maximum flame temperature increases with decreasing liftoff height, the kinetic structure showed a transition behavior from autoignition to flame propagation of a lean premixed flame. © 2016 The Combustion Institute

Upward revision of global fossil fuel methane emissions based on isotope database.

Science.gov (United States)

Schwietzke, Stefan; Sherwood, Owen A; Bruhwiler, Lori M P; Miller, John B; Etiope, Giuseppe; Dlugokencky, Edward J; Michel, Sylvia Englund; Arling, Victoria A; Vaughn, Bruce H; White, James W C; Tans, Pieter P

2016-10-06

Methane has the second-largest global radiative forcing impact of anthropogenic greenhouse gases after carbon dioxide, but our understanding of the global atmospheric methane budget is incomplete. The global fossil fuel industry (production and usage of natural gas, oil and coal) is thought to contribute 15 to 22 per cent of methane emissions to the total atmospheric methane budget. However, questions remain regarding methane emission trends as a result of fossil fuel industrial activity and the contribution to total methane emissions of sources from the fossil fuel industry and from natural geological seepage, which are often co-located. Here we re-evaluate the global methane budget and the contribution of the fossil fuel industry to methane emissions based on long-term global methane and methane carbon isotope records. We compile the largest isotopic methane source signature database so far, including fossil fuel, microbial and biomass-burning methane emission sources. We find that total fossil fuel methane emissions (fossil fuel industry plus natural geological seepage) are not increasing over time, but are 60 to 110 per cent greater than current estimates owing to large revisions in isotope source signatures. We show that this is consistent with the observed global latitudinal methane gradient. After accounting for natural geological methane seepage, we find that methane emissions from natural gas, oil and coal production and their usage are 20 to 60 per cent greater than inventories. Our findings imply a greater potential for the fossil fuel industry to mitigate anthropogenic climate forcing, but we also find that methane emissions from natural gas as a fraction of production have declined from approximately 8 per cent to approximately 2 per cent over the past three decades.

Characterization of Lean Misfire Limits of Mixture Alternative Gaseous Fuels Used for Spark Ignition Engines

Directory of Open Access Journals (Sweden)

Miqdam Tariq Chaichan

2012-03-01

Full Text Available Increasing on gaseous fuels as clean, economical and abundant fuels encourages the search for optimum conditions of gas-fueled internal combustion engines. This paper presents the experimental results on the lean operational limits of Recardo E6 engine using gasoline, LPG, NG and hydrogen as fuels. The first appearance of almost motoring cycle was used to define the engine lean limit after the fuel flow was reduced gradually. The effects of compression ratio, engine speed and spark timing on the engine operational limits are presented and discussed in detailed. Increasing compression ratio (CR extend the lean limits, this appears obviously with hydrogen, which has a wide range of equivalence ratios, while for hydrocarbon fuel octane number affect gasoline, so it can' t work above CR=9:1, and for LPG it reaches CR=12:1, NG reaches CR=15:1 at lean limit operation. Movement from low speeds to medium speeds extended lean misfire limits, while moving from medium to high speeds contracted the lean misfiring limits. NOx, CO and UBHC concentrations increased with CR increase for all fuels, while CO2 concentrations reduced with this increment. NOx concentration increased for medium speeds and reduced for high speeds, but the resulted concentrations were inconcedrable for these lean limits. CO and CO2 increased with engine speed increase, while UBHC reduced with this increment. The hydrogen engine runs with zero CO, CO2 and UNHC concentrations, and altra low levels of NOx concentrations at studied lean misfire limits

Methanator fueled engines for pollution control

Science.gov (United States)

Cagliostro, D. E.; Winkler, E. L.

1973-01-01

A methanator fueled Otto-cycle engine is compared with other methods proposed to control pollution due to automobile exhaust emissions. The comparison is made with respect to state of development, emission factors, capital cost, operational and maintenance costs, performance, operational limitations, and impact on the automotive industries. The methanator fueled Otto-cycle engine is projected to meet 1975 emission standards and operate at a lower relative total cost compared to the catalytic muffler system and to have low impact. Additional study is required for system development.

A Comparison of Combustion Dynamics for Multiple 7-Point Lean Direct Injection Combustor Configurations

Science.gov (United States)

Tacina, K. M.; Hicks, Y. R.

2017-01-01

The combustion dynamics of multiple 7-point lean direct injection (LDI) combustor configurations are compared. LDI is a fuel-lean combustor concept for aero gas turbine engines in which multiple small fuel-air mixers replace one traditionally-sized fuel-air mixer. This 7-point LDI configuration has a circular cross section, with a center (pilot) fuel-air mixer surrounded by six outer (main) fuel-air mixers. Each fuel-air mixer consists of an axial air swirler followed by a converging-diverging venturi. A simplex fuel injector is inserted through the center of the air swirler, with the fuel injector tip located near the venturi throat. All 7 fuel-air mixers are identical except for the swirler blade angle, which varies with the configuration. Testing was done in a 5-atm flame tube with inlet air temperatures from 600 to 800 F and equivalence ratios from 0.4 to 0.7. Combustion dynamics were measured using a cooled PCB pressure transducer flush-mounted in the wall of the combustor test section.

Thermodynamic characteristics of a low concentration methane catalytic combustion gas turbine

International Nuclear Information System (INIS)

Yin, Juan; Su, Shi; Yu, Xin Xiang; Weng, Yiwu

2010-01-01

Low concentration methane, emitted from coal mines, landfill, animal waste, etc. into the atmosphere, is not only a greenhouse gas, but also a waste energy source if not utilised. Methane is 23 times more potent than CO 2 in terms of trapping heat in the atmosphere over a timeframe of 100 years. This paper studies a novel lean burn catalytic combustion gas turbine, which can be powered with about 1% methane (volume) in air. When this technology is successfully developed, it can be used not only to mitigate the methane for greenhouse gas reduction, but also to utilise such methane as a clean energy source. This paper presents our study results on the thermodynamic characteristics of this new lean burn catalytic combustion gas turbine system by conducting thermal performance analysis of the turbine cycle. The thermodynamic data including thermal efficiencies and exergy loss of main components of the turbine system are presented under different pressure ratios, turbine inlet temperatures and methane concentrations.

Rich-burn, flame-assisted fuel cell, quick-mix, lean-burn (RFQL) combustor and power generation

Science.gov (United States)

Milcarek, Ryan J.; Ahn, Jeongmin

2018-03-01

Micro-tubular flame-assisted fuel cells (mT-FFC) were recently proposed as a modified version of the direct flame fuel cell (DFFC) operating in a dual chamber configuration. In this work, a rich-burn, quick-mix, lean-burn (RQL) combustor is combined with a micro-tubular solid oxide fuel cell (mT-SOFC) stack to create a rich-burn, flame-assisted fuel cell, quick-mix, lean-burn (RFQL) combustor and power generation system. The system is tested for rapid startup and achieves peak power densities after only 35 min of testing. The mT-FFC power density and voltage are affected by changes in the fuel-lean and fuel-rich combustion equivalence ratio. Optimal mT-FFC performance favors high fuel-rich equivalence ratios and a fuel-lean combustion equivalence ratio around 0.80. The electrical efficiency increases by 150% by using an intermediate temperature cathode material and improving the insulation. The RFQL combustor and power generation system achieves rapid startup, a simplified balance of plant and may have applications for reduced NOx formation and combined heat and power.

Flame propagation and counterflow nonpremixed ignition of mixtures of methane and ethylene

Energy Technology Data Exchange (ETDEWEB)

Liu, W.; Kelley, A.P.; Law, C.K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

2010-05-15

The ignition temperature of nitrogen-diluted mixtures of methane and ethylene counterflowing against heated air was measured up to five atmospheres. In addition, the stretch-corrected laminar flame speeds of mixtures of air, methane and ethylene were determined from outwardly-propagating spherical flames up to 10 atmospheres, for extensive range of the lean-to-rich equivalence ratio. These experimental data, relevant to low- to moderately-high-temperature ignition chemistry and high-temperature flame chemistry, respectively, were subsequently compared with calculations using two detailed kinetic mechanisms. A chemical explosive mode analysis (CEMA) was then conducted to identify the dominant ignition chemistry and the role of ethylene addition in facilitating nonpremixed ignition. Furthermore, the hierarchical structure of the associated oxidation kinetics was examined by comparing the sizes and constituents of the skeletal mechanisms of the pure fuels and their mixtures, derived using the method of directed relation graph (DRG). The skeletal mechanism was further reduced by time-scale analysis, leading to a 24-species reduced mechanism from the detailed mechanism of USC Mech II, validated within the parameter space of the conducted experiments. (author)

Investigation of combustion characteristics of methane-hydrogen fuels

Science.gov (United States)

Vetkin, A. V.; Suris, A. L.; Litvinova, O. A.

2015-01-01

Numerical investigations of combustion characteristics of methane-hydrogen fuel used at present in tube furnaces of some petroleum refineries are carried out and possible problems related to change-over of existing furnaces from natural gas to methane-hydrogen fuel are analyzed. The effect of the composition of the blended fuel, associated temperature and emissivity of combustion products, temperature of combustion chamber walls, mean beam length, and heat release on variation in the radiation heat flux is investigated. The methane concentration varied from 0 to 100%. The investigations were carried out both at arbitrary given gas temperatures and at effective temperatures determined based on solving a set of equations at various heat-release rates of the combustion chamber and depended on the adiabatic combustion temperature and the temperature at the chamber output. The approximation dependence for estimation of the radiation heat exchange rate in the radiant chamber of the furnace at change-over to fuel with a greater hydrogen content is obtained. Hottel data were applied in the present work in connection with the impossibility to use approximated formulas recommended by the normative method for heat calculation of boilers to determine the gas emissivity, which are limited by the relationship of partial pressures of water steam and carbon dioxide in combustion products . The effect of the methane-hydrogen fuel on the equilibrium concentration of nitrogen oxides is also investigated.

Operating a locomotive on liquid methane fuel

International Nuclear Information System (INIS)

Stolz, J.L.

1992-01-01

This paper reports that several years ago, Burlington Northern Railroad looked into the feasibility of operating a diesel railroad locomotive to also run on compressed natural gas in a dual-fuel mode. Recognizing the large volume of on-board storage required and other limitations of CNG in the application, a program was begun to fuel a locomotive with liquefied natural gas. Because natural gas composition can vary with source and processing, it was considered desirable to use essentially pure liquid methane as the engine fuel. Initial testing results show the locomotive system achieved full diesel-rated power when operating on liquid methane and with equivalent fuel efficiency. Extended testing, including an American Association of Railroad 500-hour durability test, was undertaken to obtain information on engine life, wear rate and lubrication oil life

Transient combustion modeling of an oscillating lean premixed methane/air flam

NARCIS (Netherlands)

Withag, J.A.M.; Kok, Jacobus B.W.; Syed, Khawar

2009-01-01

The main objective of the present study is to demonstrate accurate low frequency transient turbulent combustion modeling. For accurate flame dynamics some improvements were made to the standard TFC combustion model for lean premixed combustion. With use of a 1D laminar flamelet code, predictions

Fuels Containing Methane of Natural Gas in Solution

Science.gov (United States)

Sullivan, Thomas A.

2004-01-01

While exploring ways of producing better fuels for propulsion of a spacecraft on the Mars sample return mission, a researcher at Johnson Space Center (JSC) devised a way of blending fuel by combining methane or natural gas with a second fuel to produce a fuel that can be maintained in liquid form at ambient temperature and under moderate pressure. The use of such a blended fuel would be a departure for both spacecraft engines and terrestrial internal combustion engines. For spacecraft, it would enable reduction of weights on long flights. For the automotive industry on Earth, such a fuel could be easily distributed and could be a less expensive, more efficient, and cleaner-burning alternative to conventional fossil fuels. The concept of blending fuels is not new: for example, the production of gasoline includes the addition of liquid octane enhancers. For the future, it has been commonly suggested to substitute methane or compressed natural gas for octane-enhanced gasoline as a fuel for internal-combustion engines. Unfortunately, methane or natural gas must be stored either as a compressed gas (if kept at ambient temperature) or as a cryogenic liquid. The ranges of automobiles would be reduced from their present values because of limitations on the capacities for storage of these fuels. Moreover, technical challenges are posed by the need to develop equipment to handle these fuels and, especially, to fill tanks acceptably rapidly. The JSC alternative to provide a blended fuel that can be maintained in liquid form at moderate pressure at ambient temperature has not been previously tried. A blended automotive fuel according to this approach would be made by dissolving natural gas in gasoline. The autogenous pressure of this fuel would eliminate the need for a vehicle fuel pump, but a pressure and/or flow regulator would be needed to moderate the effects of temperature and to respond to changing engine power demands. Because the fuel would flash as it entered engine

Vortex combustor for low NOX emissions when burning lean premixed high hydrogen content fuel

Science.gov (United States)

Steele, Robert C; Edmonds, Ryan G; Williams, Joseph T; Baldwin, Stephen P

2012-11-20

A trapped vortex combustor. The trapped vortex combustor is configured for receiving a lean premixed gaseous fuel and oxidant stream, where the fuel includes hydrogen gas. The trapped vortex combustor is configured to receive the lean premixed fuel and oxidant stream at a velocity which significantly exceeds combustion flame speed in a selected lean premixed fuel and oxidant mixture. The combustor is configured to operate at relatively high bulk fluid velocities while maintaining stable combustion, and low NOx emissions. The combustor is useful in gas turbines in a process of burning synfuels, as it offers the opportunity to avoid use of diluent gas to reduce combustion temperatures. The combustor also offers the possibility of avoiding the use of selected catalytic reaction units for removal of oxides of nitrogen from combustion gases exiting a gas turbine.

Effects of pressure and fuel dilution on coflow laminar methane-air diffusion flames: A computational and experimental study

Science.gov (United States)

Cao, Su; Ma, Bin; Giassi, Davide; Bennett, Beth Anne V.; Long, Marshall B.; Smooke, Mitchell D.

2018-03-01

In this study, the influence of pressure and fuel dilution on the structure and geometry of coflow laminar methane-air diffusion flames is examined. A series of methane-fuelled, nitrogen-diluted flames has been investigated both computationally and experimentally, with pressure ranging from 1.0 to 2.7 atm and CH4 mole fraction ranging from 0.50 to 0.65. Computationally, the MC-Smooth vorticity-velocity formulation was employed to describe the reactive gaseous mixture, and soot evolution was modelled by sectional aerosol equations. The governing equations and boundary conditions were discretised on a two-dimensional computational domain by finite differences, and the resulting set of fully coupled, strongly nonlinear equations was solved simultaneously at all points using a damped, modified Newton's method. Experimentally, chemiluminescence measurements of CH* were taken to determine its relative concentration profile and the structure of the flame front. A thin-filament ratio pyrometry method using a colour digital camera was employed to determine the temperature profiles of the non-sooty, atmospheric pressure flames, while soot volume fraction was quantified, after evaluation of soot temperature, through an absolute light calibration using a thermocouple. For a broad spectrum of flames in atmospheric and elevated pressures, the computed and measured flame quantities were examined to characterise the influence of pressure and fuel dilution, and the major conclusions were as follows: (1) maximum temperature increases with increasing pressure or CH4 concentration; (2) lift-off height decreases significantly with increasing pressure, modified flame length is roughly independent of pressure, and flame radius decreases with pressure approximately as P-1/2; and (3) pressure and fuel stream dilution significantly affect the spatial distribution and the peak value of the soot volume fraction.

Fully Premixed Low Emission, High Pressure Multi-Fuel Burner

Science.gov (United States)

Nguyen, Quang-Viet (Inventor)

2012-01-01

A low-emissions high-pressure multi-fuel burner includes a fuel inlet, for receiving a fuel, an oxidizer inlet, for receiving an oxidizer gas, an injector plate, having a plurality of nozzles that are aligned with premix face of the injector plate, the plurality of nozzles in communication with the fuel and oxidizer inlets and each nozzle providing flow for one of the fuel and the oxidizer gas and an impingement-cooled face, parallel to the premix face of the injector plate and forming a micro-premix chamber between the impingement-cooled face and the in injector face. The fuel and the oxidizer gas are mixed in the micro-premix chamber through impingement-enhanced mixing of flows of the fuel and the oxidizer gas. The burner can be used for low-emissions fuel-lean fully-premixed, or fuel-rich fully-premixed hydrogen-air combustion, or for combustion with other gases such as methane or other hydrocarbons, or even liquid fuels.

Computational simulation of reactive species production by methane-air DBD at high pressure and high temperature

Science.gov (United States)

Takana, H.; Tanaka, Y.; Nishiyama, H.

2012-01-01

Computational simulations of a single streamer in DBD in lean methane-air mixture at pressure of 1 and 3 atm and temperature of 300 and 500 K were conducted for plasma-enhanced chemical reactions in a closed system. The effects of surrounding pressure and temperature are characterized for reactive species production by a DBD discharge. The results show that the production characteristics of reactive species are strongly influenced by the total gas number density and the higher concentration of reactive species are produced at higher pressure and lower gas temperature for a given initial reduced electric field.

Lean mixture engine testing and evaluation program. [for automobile engine pollution and fuel performances

Science.gov (United States)

Dowdy, M. W.; Hoehn, F. W.; Griffin, D. C.

1975-01-01

Experimental results for fuel consumption and emissions are presented for a 350 CID (5.7 liter) Chevrolet V-8 engine modified for lean operation with gasoline. The lean burn engine achieved peak thermal efficiency at an equivalence ratio of 0.75 and a spark advance of 60 deg BTDC. At this condition the lean burn engine demonstrated a 10% reduction in brake specific fuel consumption compared with the stock engine; however, NOx and hydrocarbon emissions were higher. With the use of spark retard and/or slightly lower equivalence ratios, the NOx emissions performance of the stock engine was matched while showing a 6% reduction in brake specific fuel consumption. Hydrocarbon emissions exceeded the stock values in all cases. Diagnostic data indicate that lean performance in the engine configuration tested is limited by ignition delay, cycle-to-cycle pressure variations, and cylinder-to-cylinder distribution.

Thermal Modeling and Management of Solid Oxide Fuel Cells Operating with Internally Reformed Methane

Science.gov (United States)

Wu, Yiyang; Shi, Yixiang; Cai, Ningsheng; Ni, Meng

2018-06-01

A detailed three-dimensional mechanistic model of a large-scale solid oxide fuel cell (SOFC) unit running on partially pre-reformed methane is developed. The model considers the coupling effects of chemical and electrochemical reactions, mass transport, momentum and heat transfer in the SOFC unit. After model validation, parametric simulations are conducted to investigate how the methane pre-reforming ratio affects the transport and electrochemistry of the SOFC unit. It is found that the methane steam reforming reaction has a "smoothing effect", which can achieve more uniform distributions of gas compositions, current density and temperature among the cell plane. In the case of 1500 W/m2 power density output, adding 20% methane absorbs 50% of internal heat production inside the cell, reduces the maximum temperature difference inside the cell from 70 K to 22 K and reduces the cathode air supply by 75%, compared to the condition of completely pre-reforming of methane. Under specific operating conditions, the pre-reforming ratio of methane has an optimal range for obtaining a good temperature distribution and good cell performance.

Heat transfer comparison between methane and hydrogen in a spark ignited engine

Energy Technology Data Exchange (ETDEWEB)

Sierens, Roger; Demuynck, Joachim; Paepe, Michel de; Verhelst, Sebastian [Ghent Univ. (Belgium)

2010-07-01

Hydrogen is one of the alternative fuels which are being investigated at Ghent University. NO{sub x} emissions will occur at high engine loads and they are a constraint for power and efficiency optimization. The formation of NO{sub x} emissions is temperature dependent. Consequently, the heat transfer from the burning gases to the cylinder walls has to be accurately modelled if precise computer calculations of the emissions are wanted. Several engine heat transfer models exist but they have been cited to be inaccurate for hydrogen. We have measured the heat flux in a spark ignited engine with a commercially available heat flux sensor. This paper investigates the difference between the heat transfer of hydrogen and a fossil fuel, in this case methane. Measurements with the same indicated power output are compared and the effect of the heat loss on the indicated efficiency is investigated. The power output of hydrogen combustion is lowered by burning lean in contrast to using a throttle in the case of methane. Although the peak in the heat flux of hydrogen is 3 times higher compared to methane for a high engine power output, the indicated efficiency is only 3% lower. The heat loss for hydrogen at a low engine load is smaller than that of methane which results in a higher indicated efficiency. The richness of the hydrogen-air mixture has a great influence on the heat transfer process in contrast to the in-cylinder mass in the case of methane. (orig.)

Autoignited laminar lifted flames of methane/hydrogen mixtures in heated coflow air

KAUST Repository

Choi, Byungchul

2012-04-01

Autoignited lifted flame behavior in laminar jets of methane/hydrogen mixture fuels has been investigated experimentally in heated coflow air. Three regimes of autoignited lifted flames were identified depending on initial temperature and hydrogen to methane ratio. At relatively high initial temperature, addition of a small amount of hydrogen to methane improved ignition appreciably such that the liftoff height decreased significantly. In this hydrogen-assisted autoignition regime, the liftoff height increased with jet velocity, and the characteristic flow time - defined as the ratio of liftoff height to jet velocity - correlated well with the square of the adiabatic ignition delay time. At lower temperature, the autoignited lifted flame demonstrated a unique feature in that the liftoff height decreased with increasing jet velocity. Such behavior has never been observed in lifted laminar and turbulent jet flames. A transition regime existed between these two regimes at intermediate temperature. © 2011 The Combustion Institute.

Hydrogen generator, via catalytic partial oxidation of methane for fuel cells

Science.gov (United States)

Recupero, Vincenzo; Pino, Lidia; Di Leonardo, Raffaele; Lagana', Massimo; Maggio, Gaetano

It is well known that the most acknowledged process for generation of hydrogen for fuel cells is based upon the steam reforming of methane or natural gas. A valid alternative could be a process based on partial oxidation of methane, since the process is mildly exothermic and therefore not energy intensive. Consequently, great interest is expected from conversion of methane into syngas, if an autothermal, low energy intensive, compact and reliable process could be developed. This paper covers the activities, performed by the CNR Institute of Transformation and Storage of Energy (CNR-TAE), on theoretical and experimental studies for a compact hydrogen generator, via catalytic selective partial oxidation of methane, integrated with second generation fuel cells (EC-JOU2 contract). In particular, the project focuses the attention on methane partial oxidation via heterogeneous selective catalysts, in order to: demonstrate the basic catalytic selective partial oxidation of methane (CSPOM) technology in a subscale prototype, equivalent to a nominal output of 5 kWe; develop the CSPOM technology for its application in electric energy production by means of fuel cells; assess, by a balance of plant analysis, and a techno-economic evaluation, the potential benefits of the CSPOM for different categories of fuel cells.

Fundamental Study of a Single Point Lean Direct Injector. Part I: Effect of Air Swirler Angle and Injector Tip Location on Spray Characteristics

Science.gov (United States)

Tedder, Sarah A.; Hicks, Yolanda R.; Tacina, Kathleen M.; Anderson, Robert C.

2015-01-01

Lean direct injection (LDI) is a combustion concept to reduce oxides of nitrogen (NOx) for next generation aircraft gas turbine engines. These newer engines have cycles that increase fuel efficiency through increased operating pressures, which increase combustor inlet temperatures. NOx formation rates increase with higher temperatures; the LDI strategy avoids high temperature by staying fuel lean and away from stoichiometric burning. Thus, LDI relies on rapid and uniform fuel/air mixing. To understand this mixing process, a series of fundamental experiments are underway in the Combustion and Dynamics Facility at NASA Glenn Research Center. This first set of experiments examines cold flow (non-combusting) mixing using air and water. Using laser diagnostics, the effects of air swirler angle and injector tip location on the spray distribution, recirculation zone, and droplet size distribution are examined. Of the three swirler angles examined, 60 degrees is determined to have the most even spray distribution. The injector tip location primarily shifts the flow without changing the structure, unless the flow includes a recirculation zone. When a recirculation zone is present, minimum axial velocity decreases as the injector tip moves downstream towards the venturi exit; also the droplets become more uniform in size and angular distribution.

Experimental characterization of methane inverse diffusion flame

KAUST Repository

Elbaz, Ayman M.; Roberts, William L.

2014-01-01

This article presents 10-kHz images of OH-PLIF simultaneously with 2-D PIV measurements in an inverse methane diffusion flame. Under a constant fuel flow rate, the central air jet Re was varied, leading to air to fuel velocity ratio, Vr, to vary

Numerical simulation of fuel mixing with air in laminar buoyant vortex rings

International Nuclear Information System (INIS)

Prasad, M. Jogendra; Sundararajan, T.

2016-01-01

Highlights: • At large Reynolds number, small vortex ring is formed due to thin boundary layer. • At higher stroke to diameter ratio, larger vortex is formed which travels farther. • After formation, trailing stem transfers circulation and fuel to the ring by buoyancy. • Formation number of buoyant vortex ring is higher than that of non-buoyant ring. • Buoyant fuel puffs entrain more air than non-buoyant air-premixed fuel puffs. - Abstract: The formation and evolution of vortex rings consisting of methane-air mixtures have been numerically simulated for different stroke to diameter (L/D) ratios (1.5, 3.5 and 6), Reynolds numbers (1000 and 2000) and initial mixture compositions (fuel with 0%, 15% and 30% of stoichiometric air). The numerical simulations are first validated by comparing with the results of earlier computational studies and also with in-house data from smoke visualization studies. In pure methane case, buoyancy significantly aids the upward rise of the vortex ring. The increase of vortex core height with time is faster for larger L/D ratio, contributed mainly by the larger initial puff volume. The radial size of the vortex also increases rapidly with time during the formation stage; this is followed by a slight shrinkage when piston comes to a stop. Later, a slow radial growth of the ring occurs due to the entrainment of ambient air, except during vortex pinch-off. The boundary layer thickness δ_e at orifice exit decreases as Re"−"0"."5 at a fixed L/D ratio; this in turn, results in a vortex of smaller size and circulation level, at a relatively higher Reynolds number. For L/D values greater than the critical value, a trailing stem is formed behind the ring vortex which feeds circulation and fuel into the vortex ring in the later stages of vortex evolution. Mass fraction contours indicate that fuel-air mixing is more effective within the vortex than in the stem. Ambient air entrainment is larger at higher L/D ratio and lower Re, for the

Comparison and evaluation of methods for the determination of flammability limits, applied to methane/hydrogen/air mixtures

International Nuclear Information System (INIS)

Schoor, F. van den; Hermanns, R.T.E.; Oijen, J.A. van; Verplaetsen, F.; Goey, L.P.H. de

2008-01-01

Different methods, both experimental and numerical, to determine the flammability limits are compared and evaluated, exemplified by a determination of the flammability limits of methane/hydrogen/air mixtures for hydrogen fuel molar fractions of 0, 0.2, 0.4 and 0.6, at atmospheric pressure and ambient temperature. Two different experimental methods are used. The first method uses a glass tube with visual observation of the flame, whereas the second method uses a closed spherical vessel with a pressure rise criterion to determine whether flame propagation has occurred. In addition to these experiments, the flammability limits are determined numerically. Unsteady planar and spherically expanding flames are calculated with a one-dimensional flame code with the inclusion of radiation heat loss in the optically thin limit. Comparison of the experimental results with the results of the planar flame calculations shows large differences, especially for lean mixtures. These differences increase with increasing hydrogen content in the fuel. Better agreement with the experimental results is found for the spherically expanding flame calculations. A limiting burning velocity of 5 cm/s is found to predict the upper flammability limit determined with the tube method very well, whereas the limiting flame temperature approach was found to give poorer agreement. Further analysis indicates that the neglect of flame front instabilities is the probable cause of the large differences between experimental and numerical results at the lower flammability limit

Enhanced activity and stability of La-doped CeO2 monolithic catalysts for lean-oxygen methane combustion.

Science.gov (United States)

Zhu, Wenjun; Jin, Jianhui; Chen, Xiao; Li, Chuang; Wang, Tonghua; Tsang, Chi-Wing; Liang, Changhai

2018-02-01

Effective utilization of coal bed methane is very significant for energy utilization and environment protection. Catalytic combustion of methane is a promising way to eliminate trace amounts of oxygen in the coal bed methane and the key to this technology is the development of high-efficiency catalysts. Herein, we report a series of Ce 1-x La x O 2-δ (x = 0-0.8) monolithic catalysts for the catalytic combustion of methane, which are prepared by citric acid method. The structural characterization shows that the substitution of La enhance the oxygen vacancy concentration and reducibility of the supports and promote the migration of the surface oxygen, as a result improve the catalytic activity of CeO 2 . M-Ce 0.8 La 0.2 O 2-δ (monolithic catalyst, Ce 0.8 La 0.2 O 2-δ coated on cordierite honeycomb) exhibits outstanding activity for methane combustion, and the temperature for 10 and 90% methane conversion are 495 and 580 °C, respectively. Additionally, Ce 0.8 La 0.2 O 2-δ monolithic catalyst presents excellent stability at high temperature. These Ce 1-x La x O 2-δ monolithic materials with a small amount of La incorporation therefore show promises as highly efficient solid solution catalysts for lean-oxygen methane combustion. Graphical abstract ᅟ.

Direct numerical simulations of turbulent lean premixed combustion

International Nuclear Information System (INIS)

Sankaran, Ramanan; Hawkes, Evatt R; Chen, Jacqueline H; Lu Tianfeng; Law, Chung K

2006-01-01

In recent years, due to the advent of high-performance computers and advanced numerical algorithms, direct numerical simulation (DNS) of combustion has emerged as a valuable computational research tool, in concert with experimentation. The role of DNS in delivering new Scientific insight into turbulent combustion is illustrated using results from a recent 3D turbulent premixed flame simulation. To understand the influence of turbulence on the flame structure, a 3D fully-resolved DNS of a spatially-developing lean methane-air turbulent Bunsen flame was performed in the thin reaction zones regime. A reduced chemical model for methane-air chemistry consisting of 13 resolved species, 4 quasi-steady state species and 73 elementary reactions was developed specifically for the current simulation. The data is analyzed to study possible influences of turbulence on the flame thickness. The results show that the average flame thickness increases, in qualitative agreement with several experimental results

On-line monitoring of methane in sewer air.

Science.gov (United States)

Liu, Yiwen; Sharma, Keshab R; Murthy, Sudhir; Johnson, Ian; Evans, Ted; Yuan, Zhiguo

2014-10-16

Methane is a highly potent greenhouse gas and contributes significantly to climate change. Recent studies have shown significant methane production in sewers. The studies conducted so far have relied on manual sampling followed by off-line laboratory-based chromatography analysis. These methods are labor-intensive when measuring methane emissions from a large number of sewers, and do not capture the dynamic variations in methane production. In this study, we investigated the suitability of infrared spectroscopy-based on-line methane sensors for measuring methane in humid and condensing sewer air. Two such sensors were comprehensively tested in the laboratory. Both sensors displayed high linearity (R(2) > 0.999), with a detection limit of 0.023% and 0.110% by volume, respectively. Both sensors were robust against ambient temperature variations in the range of 5 to 35°C. While one sensor was robust against humidity variations, the other was found to be significantly affected by humidity. However, the problem was solved by equipping the sensor with a heating unit to increase the sensor surface temperature to 35°C. Field studies at three sites confirmed the performance and accuracy of the sensors when applied to actual sewer conditions, and revealed substantial and highly dynamic methane concentrations in sewer air.

Performance evaluation and comparison of fuel processors integrated with PEM fuel cell based on steam or autothermal reforming and on CO preferential oxidation or selective methanation

International Nuclear Information System (INIS)

Ercolino, Giuliana; Ashraf, Muhammad A.; Specchia, Vito; Specchia, Stefania

2015-01-01

Highlights: • Modeling of different fuel processors integrated with PEM fuel cell stack. • Steam or autothermal reforming + CO selective methanation or preferential oxidation. • Reforming of different hydrocarbons: gasoline, light diesel oil, natural gas. • 5 kW e net systems comparison via energy efficiency and primary fuel rate consumed. • Highest net efficiency: steam reformer + CO selective methanation based system. - Abstract: The performances of four different auxiliary power unit (APU) schemes, based on a 5 kW e net proton exchange membrane fuel cell (PEM-FC) stack, are evaluated and compared. The fuel processor section of each APU is characterized by a reformer (autothermal ATR or steam SR), a non-isothermal water gas shift (NI-WGS) reactor and a final syngas catalytic clean-up step: the CO preferential oxidation (PROX) reactor or the CO selective methanation (SMET) one. Furthermore, three hydrocarbon fuels, the most commonly found in service stations (gasoline, light diesel oil and natural gas) are considered as primary fuels. The comparison is carried out examining the results obtained by a series of steady-state system simulations in Aspen Plus® of the four different APU schemes by varying the fed fuel. From the calculated data, the performance of CO-PROX is not very different compared to that of the CO-SMET, but the performance of the SR based APUs is higher than the scheme of the ATR based APUs. The most promising APU scheme with respect to an overall performance target is the scheme fed with natural gas and characterized by a fuel processor chain consisting of SR, NI-WGS and CO-SMET reactors. This processing reactors scheme together with the fuel cell section, notwithstanding having practically the same energy efficiency of the scheme with SR, NI-WGS and CO-PROX reactors, ensures a less complex scheme, higher hydrogen concentration in the syngas, lower air mass rate consumption, the absence of nitrogen in the syngas and higher potential

SOFC direct fuelling with high-methane gases: Optimal strategies for fuel dilution and upgrade to avoid quick degradation

International Nuclear Information System (INIS)

Baldinelli, A.; Barelli, L.; Bidini, G.; Di Michele, A.; Vivani, R.

2016-01-01

Highlights: • SOFCs are operated on natural gas and biogas direct feeding. • Methane partial oxidation and dry reforming are compared. • The optimal oxygen-to-carbon stoichiometry to avoid degradation is determined for both natural gas and biogas. • NiYSZ anodes degradation mechanisms are investigated though SEM-EDX and XRD. - Abstract: In the outlook of the transition to the carbon-free society, low-carbon gases, such as natural gas or biogas, are very promising. The first is commonly used for stationary applications based on Solid Oxide Fuel Cells (SOFCs) equipped with external reformers. Similar installations are required when the SOFC is run on biogas. Yet, high SOFC operative temperature enables internal decomposition of light hydrocarbons, therefore allowing the suppression of external reforming. Evidently, this brings about benefits in terms of system complexity and cost reduction. Nonetheless, unlike reformate fuels, direct exposure to large amount of methane favours SOFC anodes degradation. Implementing a systematic experimental approach, this paper aims at determining a simple operative strategy to carry out direct feeding without meeting with quick degradation issues, producing interesting outcomes with regards to the management of SOFC-based systems. Particularly, the regulation of the oxygen-to-carbon (O/C) relative fraction of the fuel through air addition to natural gas and partial CO_2 separation from biogas is helpful in the prevention of those mechanisms. In this study, NiYSZ anode SOFCs are exposed to air-diluted natural gas and upgraded biogas, featuring O/C between 0.2 and 1.2. Tracing these cases, at 800 °C and 500 mA/cm"2 constant load, cell performances are measured over a time interval of 100 h. Finally, post-mortem analysis is performed on the specimens to investigate material morphological changes after the exposure to high-methane fuels. Results showed that O/C = 0.8 (+63% air) is the best case to employ air-diluted natural gas

Modeling of electrochemistry and steam-methane reforming performance for simulating pressurized solid oxide fuel cell stacks

Energy Technology Data Exchange (ETDEWEB)

Recknagle, Kurtis P.; Ryan, Emily M.; Koeppel, Brian J.; Mahoney, Lenna A.; Khaleel, Moe A. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

2010-10-01

This paper examines the electrochemical and direct internal steam-methane reforming performance of the solid oxide fuel cell when subjected to pressurization. Pressurized operation boosts the Nernst potential and decreases the activation polarization, both of which serve to increase cell voltage and power while lowering the heat load and operating temperature. A model considering the activation polarization in both the fuel and the air electrodes was adopted to address this effect on the electrochemical performance. The pressurized methane conversion kinetics and the increase in equilibrium methane concentration are considered in a new rate expression. The models were then applied in simulations to predict how the distributions of direct internal reforming rate, temperature, and current density are effected within stacks operating at elevated pressure. A generic 10 cm counter-flow stack model was created and used for the simulations of pressurized operation. The predictions showed improved thermal and electrical performance with increased operating pressure. The average and maximum cell temperatures decreased by 3% (20 C) while the cell voltage increased by 9% as the operating pressure was increased from 1 to 10 atm. (author)

Kinetic mechanism of molecular energy transfer and chemical reactions in low-temperature air-fuel plasmas.

Science.gov (United States)

Adamovich, Igor V; Li, Ting; Lempert, Walter R

2015-08-13

This work describes the kinetic mechanism of coupled molecular energy transfer and chemical reactions in low-temperature air, H2-air and hydrocarbon-air plasmas sustained by nanosecond pulse discharges (single-pulse or repetitive pulse burst). The model incorporates electron impact processes, state-specific N(2) vibrational energy transfer, reactions of excited electronic species of N(2), O(2), N and O, and 'conventional' chemical reactions (Konnov mechanism). Effects of diffusion and conduction heat transfer, energy coupled to the cathode layer and gasdynamic compression/expansion are incorporated as quasi-zero-dimensional corrections. The model is exercised using a combination of freeware (Bolsig+) and commercial software (ChemKin-Pro). The model predictions are validated using time-resolved measurements of temperature and N(2) vibrational level populations in nanosecond pulse discharges in air in plane-to-plane and sphere-to-sphere geometry; temperature and OH number density after nanosecond pulse burst discharges in lean H(2)-air, CH(4)-air and C(2)H(4)-air mixtures; and temperature after the nanosecond pulse discharge burst during plasma-assisted ignition of lean H2-mixtures, showing good agreement with the data. The model predictions for OH number density in lean C(3)H(8)-air mixtures differ from the experimental results, over-predicting its absolute value and failing to predict transient OH rise and decay after the discharge burst. The agreement with the data for C(3)H(8)-air is improved considerably if a different conventional hydrocarbon chemistry reaction set (LLNL methane-n-butane flame mechanism) is used. The results of mechanism validation demonstrate its applicability for analysis of plasma chemical oxidation and ignition of low-temperature H(2)-air, CH(4)-air and C(2)H(4)-air mixtures using nanosecond pulse discharges. Kinetic modelling of low-temperature plasma excited propane-air mixtures demonstrates the need for development of a more accurate

Indoor air pollution from solid biomass fuels combustion in rural agricultural area of Tibet, China.

Science.gov (United States)

Gao, X; Yu, Q; Gu, Q; Chen, Y; Ding, K; Zhu, J; Chen, L

2009-06-01

In this study, we are trying to investigate the indoor air pollution and to estimate the residents' pollution exposure reduction of energy altering in rural Tibet. Daily PM(2.5) monitoring was conducted in indoor microenvironments like kitchen, living-room, bedroom, and yard in rural Tibet from December 2006 to March 2007. For kitchen air pollution, impact of two fuel types, methane and solid biomass fuels (SBFs), were compared. Questionnaire survey on the domestic energy pattern and residents' daily activity pattern was performed in Zha-nang County. Daily average PM(2.5) concentrations in kitchen, living-room, bedroom, and yard were 134.91 microg/m(3) (mean, n = 45, 95%CI 84.02, 185.80), 103.61 microg/m(3) (mean, n = 21, 95%CI 85.77, 121.45), 76.13 microg/m(3) (mean, n = 18, 95%CI 57.22, 95.04), and 78.33 microg/m(3) (mean, n = 34, 95%CI 60.00, 96.65) respectively. Using SBFs in kitchen resulted in higher indoor pollution than using methane. PM(2.5) concentrations in kitchen with dung cake, fuel wood and methane use were 117.41 microg/m(3) (mean, n = 18, 95%CI 71.03, 163.79), 271.11 microg/m(3) (mean, n = 12, 95%CI 104.74, 437.48), and 46.96 microg/m(3) (mean, n = 15, 95%CI 28.10, 65.82) respectively. Family income has significant influence on cooking energy choice, while the lack of commercial energy supply affects the energy choice for heating more. The effects of two countermeasures to improve indoor air quality were estimated in this research. One is to replace SBFs by clean energy like methane, the other is to separate the cooking place from other rooms and by applying these countermeasures, residents' exposure to particulate matters would reduce by 25-50% (methane) or 20-30% (separation) compared to the present situation. Indoor air pollution caused by solid biomass fuels is one of the most important burdens of disease in the developing countries, which attracts the attention of environment and public health researchers, as well as policy makers. This paper

Buoyant Unstable Behavior of Initially Spherical Lean Hydrogen-Air Premixed Flames

Directory of Open Access Journals (Sweden)

Zuo-Yu Sun

2014-07-01

Full Text Available Buoyant unstable behavior in initially spherical lean hydrogen-air premixed flames within a center-ignited combustion vessel have been studied experimentally under a wide range of pressures (including reduced, normal, and elevated pressures. The experimental observations show that the flame front of lean hydrogen-air premixed flames will not give rise to the phenomenon of cellular instability when the equivalence ratio has been reduced to a certain value, which is totally different from the traditional understanding of the instability characteristics of lean hydrogen premixed flames. Accompanied by the smoothened flame front, the propagation mode of lean hydrogen premixed flames transitions from initially spherical outwardly towards upwardly when the flames expand to certain sizes. To quantitatively investigate such buoyant instability behaviors, two parameters, “float rate (ψ” and “critical flame radius (Rcr”, have been proposed in the present article. The quantitative results demonstrate that the influences of initial pressure (Pint on buoyant unstable behaviors are different. Based on the effects of variation of density difference and stretch rate on the flame front, the mechanism of such buoyant unstable behaviors has been explained by the competition between the stretch force and the results of gravity and buoyancy, and lean hydrogen premixed flames will display buoyant unstable behavior when the stretch effects on the flame front are weaker than the effects of gravity and buoyancy.

An afterburner-powered methane/steam reformer for a solid oxide fuel cells application

Science.gov (United States)

Mozdzierz, Marcin; Chalusiak, Maciej; Kimijima, Shinji; Szmyd, Janusz S.; Brus, Grzegorz

2018-04-01

Solid oxide fuel cell (SOFC) systems can be fueled by natural gas when the reforming reaction is conducted in a stack. Due to its maturity and safety, indirect internal reforming is usually used. A strong endothermic methane/steam reforming process needs a large amount of heat, and it is convenient to provide thermal energy by burning the remainders of fuel from a cell. In this work, the mathematical model of afterburner-powered methane/steam reformer is proposed. To analyze the effect of a fuel composition on SOFC performance, the zero-dimensional model of a fuel cell connected with a reformer is formulated. It is shown that the highest efficiency of a solid oxide fuel cell is achieved when the steam-to-methane ratio at the reforming reactor inlet is high.

Effect of hydrogen addition on autoignited methane lifted flames

KAUST Repository

Choin, Byung Chul; Chung, Suk-Ho

2012-01-01

Autoignited lifted flames in laminar jets with hydrogen-enriched methane fuels have been investigated experimentally in heated coflow air. The results showed that the autoignited lifted flame of the methane/hydrogen mixture, which had an initial

Intelligent Engine Systems: Alternate Fuels Evaluation

Science.gov (United States)

Ballal, Dilip

2008-01-01

The performance and gaseous emissions were measured for a well-stirred reactor operating under lean conditions for two fuels: JP8 and a synthetic Fisher-Tropsch fuel over a range of equivalence ratios from 0.6 down to the lean blowout. The lean blowout characteristics were determined in LBO experiments at loading parameter values from 0.7 to 1.4. The lean blowout characteristics were then explored under higher loading conditions by simulating higher altitude operation with the use of nitrogen as a dilution gas for the air stream. The experiments showed that: (1) The lean blowout characteristics for the two fuels were close under both low loading and high loading conditions. (2) The combustion temperatures and observed combustion efficiencies were similar for the two fuels. (3) The gaseous emissions were similar for the two fuels and the differences in the H2O and CO2 emissions appear to be directly relatable to the C/H ratio for the fuels.

One-step reduced kinetics for lean hydrogen-air deflagration

Energy Technology Data Exchange (ETDEWEB)

Fernandez-Galisteo, D.; Sanchez, A.L. [Area de Mecanica de Fluidos, Univ. Carlos III de Madrid, Leganes 28911 (Spain); Linan, A. [ETSI Aeronauticos, Pl. Cardenal Cisneros 3, Madrid 28040 (Spain); Williams, F.A. [Dept. of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093-0411 (United States)

2009-05-15

A short mechanism consisting of seven elementary reactions, of which only three are reversible, is shown to provide good predictions of hydrogen-air lean-flame burning velocities. This mechanism is further simplified by noting that over a range of conditions of practical interest, near the lean flammability limit all reaction intermediaries have small concentrations in the important thin reaction zone that controls the hydrogen-air laminar burning velocity and therefore follow a steady state approximation, while the main species react according to the global irreversible reaction 2H{sub 2} + O{sub 2} {yields} 2H{sub 2}O. An explicit expression for the non-Arrhenius rate of this one-step overall reaction for hydrogen oxidation is derived from the seven-step detailed mechanism, for application near the flammability limit. The one-step results are used to calculate flammability limits and burning velocities of planar deflagrations. Furthermore, implications concerning radical profiles in the deflagration and reasons for the success of the approximations are clarified. It is also demonstrated that adding only two irreversible direct recombination steps to the seven-step mechanism accurately reproduces burning velocities of the full detailed mechanism for all equivalence ratios at normal atmospheric conditions and that an eight-step detailed mechanism, constructed from the seven-step mechanism by adding to it the fourth reversible shuffle reaction, improves predictions of O and OH profiles. The new reduced-chemistry descriptions can be useful for both analytical and computational studies of lean hydrogen-air flames, decreasing required computation times. (author)

Ethanol and air quality: influence of fuel ethanol content on emissions and fuel economy of flexible fuel vehicles.

Science.gov (United States)

Hubbard, Carolyn P; Anderson, James E; Wallington, Timothy J

2014-01-01

Engine-out and tailpipe emissions of NOx, CO, nonmethane hydrocarbons (NMHC), nonmethane organic gases (NMOG), total hydrocarbons (THC), methane, ethene, acetaldehyde, formaldehyde, ethanol, N2O, and NH3 from a 2006 model year Mercury Grand Marquis flexible fuel vehicle (FFV) operating on E0, E10, E20, E30, E40, E55, and E80 on a chassis dynamometer are reported. With increasing ethanol content in the fuel, the tailpipe emissions of ethanol, acetaldehyde, formaldehyde, methane, and ammonia increased; NOx and NMHC decreased; while CO, ethene, and N2O emissions were not discernibly affected. NMOG and THC emissions displayed a pronounced minimum with midlevel (E20-E40) ethanol blends; 25-35% lower than for E0 or E80. Emissions of NOx decreased by approximately 50% as the ethanol content increased from E0 to E30-E40, with no further decrease seen with E55 or E80. We demonstrate that emission trends from FFVs are explained by fuel chemistry and engine calibration effects. Fuel chemistry effects are fundamental in nature; the same trend of increased ethanol, acetaldehyde, formaldehyde, and CH4 emissions and decreased NMHC and benzene emissions are expected for all FFVs. Engine calibration effects are manufacturer and model specific; emission trends for NOx, THC, and NMOG will not be the same for all FFVs. Implications for air quality are discussed.

Fuel rich and fuel lean catalytic combustion of the stabilized confined turbulent gaseous diffusion flames over noble metal disc burners

Directory of Open Access Journals (Sweden)

Amal S. Zakhary

2014-03-01

Full Text Available Catalytic combustion of stabilized confined turbulent gaseous diffusion flames using Pt/Al2O3 and Pd/Al2O3 disc burners situated in the combustion domain under both fuel-rich and fuel-lean conditions was experimentally studied. Commercial LPG fuel having an average composition of: 23% propane, 76% butane, and 1% pentane was used. The thermal structure of these catalytic flames developed over Pt/Al2O3 and Pd/Al2O3 burners were examined via measuring the mean temperature distribution in the radial direction at different axial locations along the flames. Under-fuel-rich condition the flames operated over Pt catalytic disc attained high temperature values in order to express the progress of combustion and were found to achieve higher activity as compared to the flames developed over Pd catalytic disc. These two types of catalytic flames demonstrated an increase in the reaction rate with the downstream axial distance and hence, an increase in the flame temperatures was associated with partial oxidation towards CO due to the lack of oxygen. However, under fuel-lean conditions the catalytic flame over Pd catalyst recorded comparatively higher temperatures within the flame core in the near region of the main reaction zone than over Pt disc burner. These two catalytic flames over Pt and Pd disc burners showed complete oxidation to CO2 since the catalytic surface is covered by more rich oxygen under the fuel-lean condition.

Numerical Simulation of Methane Slip in Dual Fuel Marine Engines

OpenAIRE

Han, Jaehyun; Jensen, Michael Vincent; Pang, Kar Mun; Walther, Jens Honore; Schramm, Jesper; Bae, Choongsik

2017-01-01

The methane slip is the problematic issue for the engines using natural gas(NG). Because methane is more powerful greenhouse gas (GHG) than CO2, understanding of the methane slip during gas exchange process of the engines is essential. In this study, the influence of the gas pipe geometry and the valve timings on the methane slip was investigated. MAN L28/32DF engine was modeled to simulate the gas exchange process of the four stroke NG-diesel dual fuel engines. The mesh size of the model was...

NREL Advancements in Methane Conversion Lead to Cleaner Air, Useful Products

Energy Technology Data Exchange (ETDEWEB)

2016-06-01

Researchers at NREL leveraged the recent on-site development of gas fermentation capabilities and novel genetic tools to directly convert methane to lactic acid using an engineered methanotrophic bacterium. The results provide proof-of-concept data for a gas-to-liquids bioprocess that concurrently produces fuels and chemicals from methane. NREL researchers developed genetic tools to express heterologous genes in methanotrophic organisms, which have historically been difficult to genetically engineer. Using these tools, researchers demonstrated microbial conversion of methane to lactate, a high-volume biochemical precursor predominantly utilized for the production of bioplastics. Methane biocatalysis offers a means to concurrently liquefy and upgrade natural gas and renewable biogas, enabling their utilization in conventional transportation and industrial manufacturing infrastructure. Producing chemicals and fuels from methane expands the suite of products currently generated from biorefineries, municipalities, and agricultural operations, with the potential to increase revenue and significantly reduce greenhouse gas emissions.

Transmission of an overdriven plane detonation in lean hydrogen-air mixtures

International Nuclear Information System (INIS)

Desbordes, D.; Lannoy, A.

1988-01-01

This paper deals with hydrogen-air explosions hazards in nuclear power plants, if PWR Loss Of Coolant Accident occurs. The main objective concerns the determination of the size of the critical diameter of transmission of a detonation propagating in a near stoechiometric H 2 -Air mixture. In such a situation the diffracting detonation is an overdriven wave. Laboratory scale simulations are described which emphasize the importance of a negative step of concentration of combustible in a mixture (stoechio to lean) on plane detonation characteristics of the lean mixture, especially the drastric reduction (i) of the size of its inrinsic tridimensional structure and (ii) correlatively that of the critical diameter of transmission of the mixture

A 25 kWe low concentration methane catalytic combustion gas turbine prototype unit

International Nuclear Information System (INIS)

Su, Shi; Yu, Xinxiang

2015-01-01

Low concentration methane, emitted from various industries e.g. coal mines and landfills into atmosphere, is not only an important greenhouse gas, but also a wasted energy resource if not utilized. In the past decade, we have been developing a novel VAMCAT (ventilation air methane catalytic combustion gas turbine) technology. This turbine technology can be used to mitigate methane emissions for greenhouse gas reduction, and also to utilize the low concentration methane as an energy source. This paper presents our latest research results on the development and demonstration of a 25 kWe lean burn catalytic combustion gas turbine prototype unit. Recent experimental results show that the unit can be operated with 0.8 vol% of methane in air, producing about 19–21 kWe of electricity output. - Highlights: • A novel low concentration methane catalytic turbine prototype unit was developed. • The 25 kWe unit can be operated with ∼0.8 vol.% CH 4 in air with 19–21 kWe output. • A new start-up method was developed for the prototype unit

Modeling of electron behaviors under microwave electric field in methane and air pre-mixture gas plasma assisted combustion

Science.gov (United States)

Akashi, Haruaki; Sasaki, K.; Yoshinaga, T.

2011-10-01

Recently, plasma-assisted combustion has been focused on for achieving more efficient combustion way of fossil fuels, reducing pollutants and so on. Shinohara et al has reported that the flame length of methane and air premixed burner shortened by irradiating microwave power without increase of gas temperature. This suggests that electrons heated by microwave electric field assist the combustion. They also measured emission from 2nd Positive Band System (2nd PBS) of nitrogen during the irradiation. To clarify this mechanism, electron behavior under microwave power should be examined. To obtain electron transport parameters, electron Monte Carlo simulations in methane and air mixture gas have been done. A simple model has been developed to simulate inside the flame. To make this model simple, some assumptions are made. The electrons diffuse from the combustion plasma region. And the electrons quickly reach their equilibrium state. And it is found that the simulated emission from 2nd PBS agrees with the experimental result. Recently, plasma-assisted combustion has been focused on for achieving more efficient combustion way of fossil fuels, reducing pollutants and so on. Shinohara et al has reported that the flame length of methane and air premixed burner shortened by irradiating microwave power without increase of gas temperature. This suggests that electrons heated by microwave electric field assist the combustion. They also measured emission from 2nd Positive Band System (2nd PBS) of nitrogen during the irradiation. To clarify this mechanism, electron behavior under microwave power should be examined. To obtain electron transport parameters, electron Monte Carlo simulations in methane and air mixture gas have been done. A simple model has been developed to simulate inside the flame. To make this model simple, some assumptions are made. The electrons diffuse from the combustion plasma region. And the electrons quickly reach their equilibrium state. And it is found

On the effect of injection timing on the ignition of lean PRF/air/EGR mixtures under direct dual fuel stratification conditions

KAUST Repository

Luong, Minh Bau; Sankaran, Ramanan; Yu, Gwang Hyeon; Chung, Suk-Ho; Yoo, Chun Sang

2017-01-01

The ignition characteristics of lean primary reference fuel (PRF)/air/exhaust gas recirculation (EGR) mixture under reactivity-controlled compression ignition (RCCI) and direct duel fuel stratification (DDFS) conditions are investigated by 2-D direct numerical simulations (DNSs) with a 116-species reduced chemistry of the PRF oxidation. The 2-D DNSs of the DDFS combustion are performed by varying the injection timing of iso-octane (i-C8H18) with a pseudo-iso-octane (PC8H18) model together with a novel compression heating model to account for the compression heating and expansion cooling effects of the piston motion in an engine cylinder. The PC8H18 model is newly developed to mimic the timing, duration, and cooling effects of the direct injection of i-C8H18 onto a premixed background charge of PRF/air/EGR mixture with composition inhomogeneities. It is found that the RCCI combustion exhibits a very high peak heat release rate (HRR) with a short combustion duration due to the predominance of the spontaneous ignition mode of combustion. However, the DDFS combustion has much lower peak HRR and longer combustion duration regardless of the fuel injection timing compared to those of the RCCI combustion, which is primarily attributed to the sequential injection of i-C8H18. It is also found that the ignition delay of the DDFS combustion features a non-monotonic behavior with increasing fuel-injection timing due to the different effect of fuel evaporation on the low-, intermediate-, and high-temperature chemistry of the PRF oxidation. The budget and Damköhler number analyses verify that although a mixed combustion mode of deflagration and spontaneous ignition exists during the early phase of the DDFS combustion, the spontaneous ignition becomes predominant during the main combustion, and hence, the spread-out of heat release rate in the DDFS combustion is mainly governed by the direct injection process of i-C8H18. Finally, a misfire is observed for the DDFS combustion when

On the effect of injection timing on the ignition of lean PRF/air/EGR mixtures under direct dual fuel stratification conditions

KAUST Repository

Luong, Minh Bau

2017-06-10

The ignition characteristics of lean primary reference fuel (PRF)/air/exhaust gas recirculation (EGR) mixture under reactivity-controlled compression ignition (RCCI) and direct duel fuel stratification (DDFS) conditions are investigated by 2-D direct numerical simulations (DNSs) with a 116-species reduced chemistry of the PRF oxidation. The 2-D DNSs of the DDFS combustion are performed by varying the injection timing of iso-octane (i-C8H18) with a pseudo-iso-octane (PC8H18) model together with a novel compression heating model to account for the compression heating and expansion cooling effects of the piston motion in an engine cylinder. The PC8H18 model is newly developed to mimic the timing, duration, and cooling effects of the direct injection of i-C8H18 onto a premixed background charge of PRF/air/EGR mixture with composition inhomogeneities. It is found that the RCCI combustion exhibits a very high peak heat release rate (HRR) with a short combustion duration due to the predominance of the spontaneous ignition mode of combustion. However, the DDFS combustion has much lower peak HRR and longer combustion duration regardless of the fuel injection timing compared to those of the RCCI combustion, which is primarily attributed to the sequential injection of i-C8H18. It is also found that the ignition delay of the DDFS combustion features a non-monotonic behavior with increasing fuel-injection timing due to the different effect of fuel evaporation on the low-, intermediate-, and high-temperature chemistry of the PRF oxidation. The budget and Damköhler number analyses verify that although a mixed combustion mode of deflagration and spontaneous ignition exists during the early phase of the DDFS combustion, the spontaneous ignition becomes predominant during the main combustion, and hence, the spread-out of heat release rate in the DDFS combustion is mainly governed by the direct injection process of i-C8H18. Finally, a misfire is observed for the DDFS combustion when

An experimental study of flame stability in a directly-fueled wall cavity with a supersonic free stream

Science.gov (United States)

Rasmussen, Chadwick Clifford

An extensive study of flame stability in a cavity-based fuel injector/flameholder has been performed. Flames were stabilized in cavities with two different aft wall configurations and length to depth ratios of 3 and 4. Fuel was injected directly into the cavity using two injector configurations. Fuel injected from the aft wall of the cavity entered directly into the recirculation zone and provided desirable performance near the lean blowout limit. At high fuel flowrates, the cavity became flooded with fuel and rich blowout occurred. When fuel was injected from the floor of the cavity, excess fuel was directed out of the cavity which allowed for flame stabilization at extremely high fuel flowrates; however, this phenomenon also resulted in suboptimal performance near the lean limit where the blowout point was less predictable. Images of planar laser-induced fluorescence (PLIF) of CH, OH, and formaldehyde give insight into the flameholding mechanisms. CH layers in the cavity are thin and continuous and show structure that is comparable to lifted jet flames, while broad CH zones are sometimes observed in the shear layer. OH PLIF images show that hot recirculated products are always present at the location of flame stabilization, whereas images of formaldehyde indicate that partial premixing takes place in the shear layer portion of the flame. Nonreacting measurements of the boundary layer and the free stream velocity profiles were obtained to provide necessary boundary conditions for computational modeling. Mean and instantaneous velocity profiles were determined for the nonreacting flow using particle image velocimetry (PIV). A correlation of the blowout points for a directly-fueled cavity in a supersonic flow was accomplished using a Damkohler number and an equivalence ratio based upon an effective air mass flowrate. The chemical time was formulated using a generic measure of the reaction rate, tauc ˜ alpha/ S2L , which was found to be adequate for correlating lean

Urban air quality improvement by using a CNG lean burn engine for city buses

NARCIS (Netherlands)

Merétei, T.; Ling, J.A.N. van; Havenith, C.

1998-01-01

The use of compressed natural gas (CNG)-fuelled lean-burn city bus engines has a significant potential for air quality improvement in urban areas. Particularly important is the reduction of NO, as well as particulate and non regulated HC-emissions. For this reason, a CNG-fuelled, lean-burn,

Removal of methane from compressed natural gas fueled vehicle exhaust

International Nuclear Information System (INIS)

Subramanian, S.; Kudla, R.J.; Chattha, M.S.

1992-01-01

The objective of this paper is to investigate the modes of methane (CH 4 ) removal from simulated compressed natural gas (CNG) fueled vehicle exhaust under net oxidizing, net reducing, and stoichiometric conditions. Model reaction studies were conducted. The results suggest that the oxidation of methane with oxygen contributes to the removal of methane under net oxidizing conditions. In contrast, the oxidation of methane with oxygen as well as nitric oxide contributes to its removal under net reducing conditions. The steam reforming reaction does not significantly contribute to the removal of methane. The methane conversions under net reducing conditions are higher than those observed under net oxidizing conditions. The study shows that the presence of carbon monoxide in the feed gas leads to a gradual decrease in the methane conversion with increasing redox ratio, under net oxidizing conditions. a minimum in methane conversion is observed at a redox ratio of 0. 8. The higher activity for the methane-oxygen reaction resulting from a lowering in the overall oxidation state of palladium and the contribution of the methane-nitric oxide reaction toward the removal of CH 4 appear to account for the higher CH 4 conversions observed under net reducing conditions

Cyclic variations of fuel-droplet distribution during the early intake stroke of a lean-burn stratified-charge spark-ignition engine

Energy Technology Data Exchange (ETDEWEB)

Aleiferis, P.G. [Imperial College London, Department of Mechanical Engineering, London (United Kingdom); University College London, Department of Mechanical Engineering, London (United Kingdom); Hardalupas, Y.; Taylor, A.M.K.P. [Imperial College London, Department of Mechanical Engineering, London (United Kingdom); Ishii, K. [Honda International Technical School, Saitama (Japan); Urata, Y. [Tochigi R and D Centre, Honda R and D Co., Ltd, Tochigi (Japan)

2005-11-01

Lean-burn spark-ignition engines exhibit higher efficiency and lower specific emissions in comparison with stoichiometrically charged engines. However, as the air-to-fuel (A/F) ratio of the mixture is made leaner than stoichiometric, cycle-by-cycle variations in the early stages of in-cylinder combustion, and subsequent indicated mean effective pressure (IMEP), become more pronounced and limit the range of lean-burn operation. Viable lean-burn engines promote charge stratification, the mixture near the spark plug being richer than the cylinder volume averaged value. Recent work has shown that cycle-by-cycle variations in the early stages of combustion in a stratified-charge engine can be associated with variations in both the local value of A/F ratio near the spark plug around ignition timing, as well as in the volume averaged value of the A/F ratio. The objective of the current work was to identify possible sources of such variability in A/F ratio by studying the in-cylinder field of fuel-droplet distribution during the early intake stroke. This field was visualised in an optical single-cylinder 4-valve pentroof-type spark-ignition engine by means of laser-sheet illumination in planes parallel to the cylinder head gasket 6 and 10 mm below the spark plug. The engine was run with port-injected isooctane at 1500 rpm with 30% volumetric efficiency and air-to-fuel ratio corresponding to both stoichiometric firing (A/F=15, {phi} =1.0) and mixture strength close to the lean limit of stable operation (A/F=22, {phi} =0.68). Images of Mie intensity scattered by the cloud of fuel droplets were acquired on a cycle-by-cycle basis. These were studied in order to establish possible correlations between the cyclic variations in size, location and scattered-light intensity of the cloud of droplets with the respective variations in IMEP. Because of the low level of Mie intensity scattered by the droplets and because of problems related to elastic scattering on the walls of the

Exhaust emissions from an indirect injection dual-fuel engine

International Nuclear Information System (INIS)

Abd Alla, G.H.; Badr, O.A.; Soliman, H.A.; Abd Rabbo, M.F.

2000-01-01

Diesel engines operating on gaseous fuels are commonly known as dual-fuel engines. In the present work, a single-cylinder, compression ignition, indirect injection research (Ricardo E6) engine has been installed at United Arab Emirates University for investigation of the exhaust emissions when the engine is operating as a dual-fuel engine. The influence of changes in major operating and design parameters, such as the concentration of gaseous fuel in the cylinder charge, pilot fuel quantity, injection timing and intake temperature, on the production of exhaust emissions was investigated. Diesel fuel was used as the pilot fuel, while methane or propane was used as the main fuel which was inducted in the intake manifold and mixed with the intake air. The experimental investigations showed that the poor emissions at light loads can be improved significantly by increasing the concentration of gaseous fuel (total equivalence ratio), employing a large pilot fuel quantity, advancing the injection timing of the pilot fuel and increasing the intake temperature. It is demonstrated that, in general, any measure that tends to increase the size of the combustion regions within the overly lean cylinder charge will reduce markedly the concentrations of unburned hydrocarbons and carbon monoxide in the exhaust gases. (Author)

Exhaust emissions from an indirect injection dual-fuel engine

Energy Technology Data Exchange (ETDEWEB)

Abd Alla, G.H.; Badr, O.A.; Soliman, H.A.; Abd Rabbo, M.F. [Zagazig Univ., Dept. of Mechanical Engineering, Cairo (Egypt)

2000-04-01

Diesel engines operating on gaseous fuels are commonly known as dual-fuel engines. In the present work, a single-cylinder, compression ignition, indirect injection research (Ricardo E6) engine has been installed at United Arab Emirates University for investigation of the exhaust emissions when the engine is operating as a dual-fuel engine. The influence of changes in major operating and design parameters, such as the concentration of gaseous fuel in the cylinder charge, pilot fuel quantity, injection timing and intake temperature, on the production of exhaust emissions was investigated. Diesel fuel was used as the pilot fuel, while methane or propane was used as the main fuel which was inducted in the intake manifold and mixed with the intake air. The experimental investigations showed that the poor emissions at light loads can be improved significantly by increasing the concentration of gaseous fuel (total equivalence ratio), employing a large pilot fuel quantity, advancing the injection timing of the pilot fuel and increasing the intake temperature. It is demonstrated that, in general, any measure that tends to increase the size of the combustion regions within the overly lean cylinder charge will reduce markedly the concentrations of unburned hydrocarbons and carbon monoxide in the exhaust gases. (Author)

Sector Tests of a Low-NO(sub x), Lean, Direct- Injection, Multipoint Integrated Module Combustor Concept Conducted

Science.gov (United States)

Tacina, Robert R.; Wey, Chang-Lie; Laing, Peter; Mansour, Adel

2002-01-01

The low-emissions combustor development described is directed toward advanced high pressure aircraft gas-turbine applications. The emphasis of this research is to reduce nitrogen oxides (NOx) at high-power conditions and to maintain carbon monoxide and unburned hydrocarbons at their current low levels at low power conditions. Low-NOx combustors can be classified into rich-burn and lean-burn concepts. Lean-burn combustors can be further classified into lean-premixed-prevaporized (LPP) and lean direct injection (LDI) concepts. In both concepts, all the combustor air, except for liner cooling flow, enters through the combustor dome so that the combustion occurs at the lowest possible flame temperature. The LPP concept has been shown to have the lowest NOx emissions, but for advanced high-pressure-ratio engines, the possibility of autoignition or flashback precludes its use. LDI differs from LPP in that the fuel is injected directly into the flame zone, and thus, it does not have the potential for autoignition or flashback and should have greater stability. However, since it is not premixed and prevaporized, good atomization is necessary and the fuel must be mixed quickly and uniformly so that flame temperatures are low and NOx formation levels are comparable to those of LPP. The LDI concept described is a multipoint fuel injection/multiburning zone concept. Each of the multiple fuel injectors has an air swirler associated with it to provide quick mixing and a small recirculation zone for burning. The multipoint fuel injection provides quick, uniform mixing and the small multiburning zones provide for reduced burning residence time, resulting in low NOx formation. An integrated-module approach was used for the construction where chemically etched laminates, diffusion bonded together, combine the fuel injectors, air swirlers, and fuel manifold into a single element. The multipoint concept combustor was demonstrated in a 15 sector test. The configuration tested had 36

Ignition of a lean PRF/air mixture under RCCI/SCCI conditions: A comparative DNS study

KAUST Repository

Luong, Minh Bau

2016-10-11

The ignition characteristics of a lean primary reference fuel (PRF)/air mixture under reactivity controlled compression ignition (RCCI) and stratified charge compression ignition (SCCI) conditions are investigated using 2-D direct numerical simulations (DNSs) with a 116-species reduced mechanism of PRF oxidation. For RCCI combustion, n-heptane and iso-octane are used as two different reactivity fuels and the corresponding global PRF number is PRF50 which is also used as a single fuel for SCCI combustion. The 2-D DNSs of RCCI/SCCI combustion are performed by varying degree of fuel stratification, r, and turbulence intensity, u\\', at different initial mean temperature, T , with negatively-correlated T-r fields. It is found that in the low- and intermediate-temperature regimes, the overall combustion of RCCI cases occurs earlier and its mean heat release rate (HRR) is more distributed over time than those of the corresponding SCCI cases. This is because PRF number stratification, PRF\\', plays a dominant role and T\\' has a negligible effect on the overall combustion within the negative temperature coefficient (NTC) regime. In the high-temperature regime, however, the difference between RCCI and SCCI combustion becomes marginal because the ignition of the PRF/air mixture is highly-sensitive to T\\' rather than PRF\\' and ϕ(symbol)\\'. The Damköhler number analysis verifies that the mean HRR is more distributed over time with increasing r because the portion of deflagration mode of combustion becomes larger with increasing fuel stratification. Finally, it is found that the overall combustion of both RCCI and SCCI cases becomes more like the 0-D ignition with increasing u\\' due to the homogenization of initial mixture by turbulent mixing.

Experimental Study of Hydrogen Addition Effects on a Swirl-Stabilized Methane-Air Flame

Directory of Open Access Journals (Sweden)

Mao Li

2017-11-01

Full Text Available The effects of H2 addition on a premixed methane-air flame was studied experimentally with a swirl-stabilized gas turbine model combustor. Experiments with 0%, 25%, and 50% H2 molar fraction in the fuel mixture were conducted under atmospheric pressure. The primary objectives are to study the impacts of H2 addition on flame lean blowout (LBO limits, flame shapes and anchored locations, flow field characteristics, precessing vortex core (PVC instability, as well as the CO emission performance. The flame LBO limits were identified by gradually reducing the equivalence ratio until the condition where the flame physically disappeared. The time-averaged CH chemiluminescence was used to reveal the characteristics of flame stabilization, e.g., flame structure and stabilized locations. In addition, the inverse Abel transform was applied to the time-averaged CH results so that the distribution of CH signal on the symmetric plane of the flame was obtained. The particle image velocimetry (PIV was used to detect the characteristics of the flow field with a frequency of 2 kHz. The snapshot method of POD (proper orthogonal decomposition and fast Fourier transform (FFT were adopted to capture the most prominent coherent structures in the turbulent flow field. CO emission was monitored with an exhaust probe that was installed close to the combustor exit. The experimental results indicated that the H2 addition extended the flame LBO limits and the operation range of low CO emission. The influence of H2 addition on the flame shape, location, and flow field was observed. With the assistance of POD and FFT, the combustion suppression impacts on PVC was found.

A Computational and Experimental Study of Coflow Laminar Methane/Air Diffusion Flames: Effects of Fuel Dilution, Inlet Velocity, and Gravity

Science.gov (United States)

Cao, S.; Ma, B.; Bennett, B. A. V.; Giassi, D.; Stocker, D. P.; Takahashi, F.; Long, M. B.; Smooke, M. D.

2014-01-01

The influences of fuel dilution, inlet velocity, and gravity on the shape and structure of laminar coflow CH4-air diffusion flames were investigated computationally and experimentally. A series of nitrogen-diluted flames measured in the Structure and Liftoff in Combustion Experiment (SLICE) on board the International Space Station was assessed numerically under microgravity (mu g) and normal gravity (1g) conditions with CH4 mole fraction ranging from 0.4 to 1.0 and average inlet velocity ranging from 23 to 90 cm/s. Computationally, the MC-Smooth vorticity-velocity formulation was employed to describe the reactive gaseous mixture, and soot evolution was modeled by sectional aerosol equations. The governing equations and boundary conditions were discretized on a two-dimensional computational domain by finite differences, and the resulting set of fully coupled, strongly nonlinear equations was solved simultaneously at all points using a damped, modified Newton's method. Experimentally, flame shape and soot temperature were determined by flame emission images recorded by a digital color camera. Very good agreement between computation and measurement was obtained, and the conclusions were as follows. (1) Buoyant and nonbuoyant luminous flame lengths are proportional to the mass flow rate of the fuel mixture; computed and measured nonbuoyant flames are noticeably longer than their 1g counterparts; the effect of fuel dilution on flame shape (i.e., flame length and flame radius) is negligible when the flame shape is normalized by the methane flow rate. (2) Buoyancy-induced reduction of the flame radius through radially inward convection near the flame front is demonstrated. (3) Buoyant and nonbuoyant flame structure is mainly controlled by the fuel mass flow rate, and the effects from fuel dilution and inlet velocity are secondary.

Cellular burning in lean premixed turbulent hydrogen-air flames: Coupling experimental and computational analysis at the laboratory scale

International Nuclear Information System (INIS)

Day, M S; Bell, J B; Beckner, V E; Lijewski, M J; Cheng, R K; Tachibana, S

2009-01-01

One strategy for reducing US dependence on petroleum is to develop new combustion technologies for burning the fuel-lean mixtures of hydrogen or hydrogen-rich syngas fuels obtained from the gasification of coal and biomass. Fuel-flexible combustion systems based on lean premixed combustion have the potential for dramatically reducing pollutant emissions in transportation systems, heat and stationary power generation. However, lean premixed flames are highly susceptible to fluid-dynamical combustion instabilities making robust and reliable systems difficult to design. Low swirl burners are emerging as an important technology for meeting design requirements in terms of both reliability and emissions for next generation combustion devices. In this paper, we present simulations of a lean, premixed hydrogen flame stabilized on a laboratory-scale low swirl burner. The simulations use detailed chemistry and transport without incorporating explicit models for turbulence or turbulence/chemistry interaction. Here we discuss the overall structure of the flame and compare with experimental data. We also use the simulation data to elucidate the characteristics of the turbulent flame interaction and how this impacts the analysis of experimental measurements.

Methane and carbon dioxide ratio in excreted air for quantification of the methane production from ruminants

DEFF Research Database (Denmark)

Madsen, Jørgen; Bjerg, Bjarne Schmidt; Hvelplund, Torben

2010-01-01

This technical note presents a simple, fast, reliable and cheap method to estimate the methane (CH4) production from animals by using the CH4 and carbon dioxide (CO2) concentrations in air near the animals combined with an estimation of the total CO2 production from information on intake of metab......This technical note presents a simple, fast, reliable and cheap method to estimate the methane (CH4) production from animals by using the CH4 and carbon dioxide (CO2) concentrations in air near the animals combined with an estimation of the total CO2 production from information on intake...

Thermo-economic analysis of proton exchange membrane fuel cell fuelled with methanol and methane

International Nuclear Information System (INIS)

Suleiman, B.; Abdulkareem, A.S.; Musa, U.; Mohammed, I.A.; Olutoye, M.A.; Abdullahi, Y.I.

2016-01-01

Highlights: • Modified proton exchange membrane fuel cell was reported. • Thermolib software was used for the simulation of PEM fuel cell configurations. • Optimal operating parameters at 50 kW output of each process were determined. • Thermo-economic analysis is the most efficient way of process selection. • Methane system configuration has been identified as the best preferred PEM fuel cell. - Abstract: Exergy and economic analysis is often used to find and identify the most efficient process configuration for proton exchange membrane fuel cell from the thermo-economic point of view. This work gives an explicit account of the synergetic effect of exergetic and economic analysis of proton exchange membrane fuel cell (PEMFC) using methanol and methane as fuel sources. This was carried out through computer simulation using Thermolib simulation toolbox. Data generated from the simulated model were subsequently used for the thermodynamic and economic analysis. Analysis of energy requirement for the two selected processes revealed that the methane fuelled system requires the lower amount of energy (4.578 kJ/s) in comparison to the methanol fuelled configuration which requires 180.719 J/s. Energy analysis of both configurations showed that the principle of energy conservation was satisfied while the result of the exergy analysis showed high exergetic efficiency around major equipment (heat exchangers, compressors and pumps) of methane fuelled configuration. Higher irreversibility rate were observed around the burner, stack, and steam reformer. These trends of exergetic efficiency and irreversibility rate were observed around equipment in the methanol fuelled system but with lower performance when compared with the methane fuelled process configuration. On the basis of overall exergetic efficiency and lost work, the methanol system was more efficient with lower irreversibility rate of 547.27 kJ/s and exergetic efficiency of 34.44% in comparison with the methane

Effect of carbon black nanoparticles on methane/air explosions: Influence at low initial turbulence

Science.gov (United States)

Torrado, David; Glaude, Pierre-Alexandre; Dufaud, Olivier

2017-06-01

Nanoparticles are widely used in industrial applications as additives to modify materials properties such as resistance, surface, rheology or UV-radiation. As a consequence, the quantification and characterization of nanoparticles have become almost compulsory, including the understanding of the risks associated to their use. Since a few years ago, several studies of dust explosion properties involving nano-sized powder have been published. During the production and industrial use of nanoparticles, simultaneous presence of gas / vapor / solvents and dispersed nanoparticles mixtures might be obtained, increasing the risk of a hybrid mixture explosion. The aim of this work is to study the severity of the explosion of carbon black nanoparticles/methane mixtures and understand the influence of adding nanopowders on the behavior of the gas explosions. These results are also useful to understand the influence of soot on the efficiency of the gas combustion. Two grades of carbon black nanoparticles (ranging from 20 to 300 nm average diameter) have been mixed with methane. Tests have been performed on these mixtures in a standard 20 L explosion sphere. Regarding the scale precision, the lowest concentration of carbon black nanoparticles was set at 0.5 g.m-3. Tests were also performed at 2.5 g.m-3, which is still far below 60 g.m-3, the minimum explosive concentration of such powders previously determined in our laboratory. The influence of carbon black particles on the severity of the explosions has been compared to that of pure gas. It appears that the use of carbon black nanoparticles increases the explosion overpressure for lean methane mixtures at low initial turbulences by c. 10%. Similar results were obtained for high initial turbulent systems. Therefore, it seems that carbon black nanoparticles have an impact on the severity of the explosion even for quiescent systems, as opposed to systems involving micro-sized powders that require dispersion at high turbulence

Numerical Study of Contaminant Effects on Combustion of Hydrogen, Ethane, and Methane in Air

Science.gov (United States)

Lai, H. T.; Thomas, S. R.

1995-01-01

A numerical study was performed to assess the effects of vitiated air on the chemical kinetics of hydrogen, ethane, and methane combustion with air. A series of calculations in static reacting systems was performed, where the initial temperature was specified and reactions occurred at constant pressure. Three different types of test flow contaminants were considered: NP, H2O, and a combustion of H2O and CO2. These contaminants are present in the test flows of facilities used for hypersonic propulsion testing. The results were computed using a detailed reaction mechanism and are presented in terms of ignition and reaction times. Calculations were made for a wide range of contaminant concentrations, temperatures and pressures. The results indicate a pronounced kinetic effect over a range of temperatures, especially with NO contamination and, to a lesser degree, with H2O contamination. In all cases studied, CO2 remained kinetically inert, but had a thermodynamic effect on results by acting as a third body. The largest effect is observed with combustion using hydrogen fuel, less effect is seen with combustion of ethane, and little effect of contaminants is shown with methane combustion.

Working group report: methane emissions from fuel combustion and industrial processes

International Nuclear Information System (INIS)

Berdowski, J.J.M.; Beck, L.; Piccot, S.; Olivier, J.G.J.; Veldt, C.

1993-01-01

This paper lists the source categories which are currently recognised as minor sources of methane. These fall into five broad groups: stationary fuel combustion (residential combustion of fuels, solid waste incineration at home sites, on-site agricultural waste burning, industrial and utility combustion of coal, wood, oil and gas, commercial and industrial waste incineration); mobile fuel combustion; non-combustion industrial processes (primary metals production, chemical manufacturing processes, petroleum refining, commercial charcoal manufacturing waste treatments); minor energy production sources (storage and distribution of automotive fuels, geothermal energy production; peat mining operations, oil shale mining operations); and miscellaneous sources. The paper also presents a preliminary estimate of global methane emissions from these minor sources and the results of the working group's discussion on recommendations for the IPCC/OECD methodology and specific research needs. A list of control options for emissions from minor sources is provided. 2 tabs

The Effect of Humidity on the Knock Behavior in a Medium BMEP Lean-Burn High-Speed Gas Engine

NARCIS (Netherlands)

van Essen, Vincent Martijn; Gersen, Sander; van Dijk, Gerco; Mundt, Torsten; Levinsky, Howard

2016-01-01

The effects of air humidity on the knock characteristics of fuels are investigated in a lean-burn, high-speed medium BMEP engine fueled with a CH4 + 4.7 mole% C3H8 gas mixture. Experiments are carried out with humidity ratios ranging from 4.3 to 11 g H2O/kg dry air. The measured pressure profiles at

Electrocatalytic oxidation of methane: investigations of new catalysts to be used in a solid polymer electrolyte methane fuel-cell; Oxydation electrocatalytique du methane: recherche de catalyseurs en vue d'une application a une pile au methane a electrolyte polymere solide

Energy Technology Data Exchange (ETDEWEB)

Berthelot, S

1998-07-01

This thesis evaluated the performances of many catalysts facing the methane oxidation which is a critical step in methane fuel cells development. In a first part the study of the methane electro-oxidation has been realized by classical electrochemical technics on many electrodes to determine the most active ones. In a second part the in situ reflection infra-red spectroscopy allowed to identify, during the methane oxidation, the adsorbed species on the electrode and the reaction products. These results also help the understanding of the part of the concerned materials mechanisms in the methane oxidation and then to optimize them for a whole oxidation of the methane in carbon dioxide. The final objective is the use of the methane in a PEMFC fuel cell type. A comparison with the methanol and C2 hydrocarbons behaviour, such as the ethane the ethylene and the acetylene, has been done to evaluate the performances. (A.L.B.)

Methane Emissions from Leak and Loss Audits of Natural Gas Compressor Stations and Storage Facilities.

Science.gov (United States)

Johnson, Derek R; Covington, April N; Clark, Nigel N

2015-07-07

As part of the Environmental Defense Fund's Barnett Coordinated Campaign, researchers completed leak and loss audits for methane emissions at three natural gas compressor stations and two natural gas storage facilities. Researchers employed microdilution high-volume sampling systems in conjunction with in situ methane analyzers, bag samples, and Fourier transform infrared analyzers for emissions rate quantification. All sites had a combined total methane emissions rate of 94.2 kg/h, yet only 12% of the emissions total resulted from leaks. Methane slip from exhausts represented 44% of the total emissions. Remaining methane emissions were attributed to losses from pneumatic actuators and controls, engine crankcases, compressor packing vents, wet seal vents, and slop tanks. Measured values were compared with those reported in literature. Exhaust methane emissions were lower than emissions factor estimates for engine exhausts, but when combined with crankcase emissions, measured values were 11.4% lower than predicted by AP-42 as applicable to emissions factors for four-stroke, lean-burn engines. Average measured wet seal emissions were 3.5 times higher than GRI values but 14 times lower than those reported by Allen et al. Reciprocating compressor packing vent emissions were 39 times higher than values reported by GRI, but about half of values reported by Allen et al. Though the data set was small, researchers have suggested a method to estimate site-wide emissions factors for those powered by four-stroke, lean-burn engines based on fuel consumption and site throughput.

methanization development and air quality. Bibliographical synthesis and working perspectives in Rhone-Alpes 2016

International Nuclear Information System (INIS)

2016-06-01

After a recall of a context which promotes the development of the methanization sector, and in order to address social acceptance issues related to methanization installations, this report aims at proposing a synthesis of existing documents related to methanization and its possible interactions with air quality. A first part briefly describes a methanization unit. The second part proposes an overview of the situation of projects in the Rhone-Alpes region. The third part proposes an overview of knowledge regarding potential impacts on air quality and greenhouse gas emissions

Experimental study of hydrogen as a fuel additive in internal combustion engines

Energy Technology Data Exchange (ETDEWEB)

Saanum, Inge

2008-07-01

. % hydrogen to the methane, but 5 vol. % hydrogen also resulted in a noticeable increase. The flame structure was also influenced by the hydrogen addition as the flame front had a higher tendency to become wrinkled or cellular. The effect is believed to mainly be caused by a reduction in the effective Lewis number of the mixture. In the gas engine experiments, the effect of adding 25 vol. % hydrogen to natural gas was investigated when the engine was run on lean air/fuel mixtures and on stoichiometric mixtures with exhaust gas recirculation. The hydrogen addition was found to extend the lean limit of stable combustion and hence caused lower NO{sub x} emissions. The brake thermal efficiency increased with the hydrogen addition, both for the fuel lean and the stoichiometric mixtures with exhaust gas recirculation. This is mainly because of shorter combustion durations when the hydrogen mixture was used, leading to thermodynamically improved cycles. Two types of experiments were performed in compression ignition engines. First, homogenous charge compression ignition (HCCI) experiments were performed in a single cylinder engine fueled with natural gas and diesel oil. As HCCI engines have high thermal efficiency and low NO{sub x} and PM emissions it may be more favorable to use natural gas in HCCI engines than in spark ignition engines. The mixture of natural gas, diesel oil and air was partly premixed before combustion. The natural gas/diesel ratio was used to control the ignition timing as the fuels have very different ignition properties. The natural gas was also replaced by a 20 vol. % hydrogen/natural gas mixture to study the effect of hydrogen on the ignition and combustion process. Also, rape seed methyl ester (RME) was tested instead of the diesel oil. The combustion phasing was found to mainly be controlled by the amount of liquid fuel injected. The last experiments with compression ignition were performed by using a standard Scania diesel engine where the possibilities

Effect of hydrogen addition on autoignited methane lifted flames

KAUST Repository

Choin, Byung Chul

2012-01-01

Autoignited lifted flames in laminar jets with hydrogen-enriched methane fuels have been investigated experimentally in heated coflow air. The results showed that the autoignited lifted flame of the methane/hydrogen mixture, which had an initial temperature over 920 K, the threshold temperature for autoignition in methane jets, exhibited features typical of either a tribrachial edge or mild combustion depending on fuel mole fraction and the liftoff height increased with jet velocity. The liftoff height in the hydrogen-assisted autoignition regime was dependent on the square of the adiabatic ignition delay time for the addition of small amounts of hydrogen, as was the case for pure methane jets. When the initial temperature was below 920 K, where the methane fuel did not show autoignition behavior, the flame was autoignited by the addition of hydrogen, which is an ignition improver. The liftoff height demonstrated a unique feature in that it decreased nonlinearly as the jet velocity increased. The differential diffusion of hydrogen is expected to play a crucial role in the decrease in the liftoff height with increasing jet velocity.

Pure rotational CARS thermometry studies of low-temperature oxidation kinetics in air and ethene-air nanosecond pulse discharge plasmas

International Nuclear Information System (INIS)

Zuzeek, Yvette; Choi, Inchul; Uddi, Mruthunjaya; Adamovich, Igor V; Lempert, Walter R

2010-01-01

Pure rotational CARS thermometry is used to study low-temperature plasma assisted fuel oxidation kinetics in a repetitive nanosecond pulse discharge in ethene-air at stoichiometric and fuel lean conditions at 40 Torr pressure. Air and fuel-air mixtures are excited by a burst of high-voltage nanosecond pulses (peak voltage, 20 kV; pulse duration, ∼ 25 ns) at a 40 kHz pulse repetition rate and a burst repetition rate of 10 Hz. The number of pulses in the burst is varied from a few pulses to a few hundred pulses. The results are compared with the previously developed hydrocarbon-air plasma chemistry model, modified to incorporate non-empirical scaling of the nanosecond discharge pulse energy coupled to the plasma with number density, as well as one-dimensional conduction heat transfer. Experimental time-resolved temperature, determined as a function of the number of pulses in the burst, is found to agree well with the model predictions. The results demonstrate that the heating rate in fuel-air plasmas is much faster compared with air plasmas, primarily due to energy release in exothermic reactions of fuel with O atoms generated by the plasma. It is found that the initial heating rate in fuel-air plasmas is controlled by the rate of radical (primarily O atoms) generation and is nearly independent of the equivalence ratio. At long burst durations, the heating rate in lean fuel air-mixtures is significantly reduced when all fuel is oxidized.

COMBUSTION SIMULATION IN A SPARK IGNITION ENGINE CYLINDER: EFFECTS OF AIR-FUEL RATIO ON THE COMBUSTION DURATION

Directory of Open Access Journals (Sweden)

Nureddin Dinler

2010-01-01

Full Text Available Combustion is an important subject of internal combustion engine studies. To reduce the air pollution from internal combustion engines and to increase the engine performance, it is required to increase combustion efficiency. In this study, effects of air/fuel ratio were investigated numerically. An axisymmetrical internal combustion engine was modeled in order to simulate in-cylinder engine flow and combustion. Two dimensional transient continuity, momentum, turbulence, energy, and combustion equations were solved. The k-e turbulence model was employed. The fuel mass fraction transport equation was used for modeling of the combustion. For this purpose a computational fluid dynamics code was developed by using the finite volume method with FORTRAN programming code. The moving mesh was utilized to simulate the piston motion. The developed code simulates four strokes of engine continuously. In the case of laminar flow combustion, Arrhenius type combustion equations were employed. In the case of turbulent flow combustion, eddy break-up model was employed. Results were given for rich, stoichiometric, and lean mixtures in contour graphs. Contour graphs showed that lean mixture (l = 1.1 has longer combustion duration.

High-pressure oxidation of methane

NARCIS (Netherlands)

Hashemi, Hamid; Christensen, Jakob M.; Gersen, Sander; Levinsky, Howard; Klippenstein, Stephen J.; Glarborg, Peter

2016-01-01

Methane oxidation at high pressures and intermediate temperatures was investigated in a laminar flow reactor and in a rapid compression machine (RCM). The flow-reactor experiments were conducted at 700–900 K and 100 bar for fuel-air equivalence ratios (Φ) ranging from 0.06 to 19.7, all highly

Flame Structure and Dynamics for an Array of Premixed Methane-Air Jets

Science.gov (United States)

Nigam, Siddharth P.; Lapointe, Caelan; Christopher, Jason D.; Wimer, Nicholas T.; Hayden, Torrey R. S.; Rieker, Gregory B.; Hamlington, Peter E.

2017-11-01

Premixed flames have been studied extensively, both experimentally and computationally, and their properties are reasonably well characterized for a range of conditions and configurations. However, the premixed combustion process is potentially much more difficult to predict when many such flames are arranged in a closely spaced array. These arrays must be better understood, in particular, for the design of industrial burners used in chemical and heat treatment processes. Here, the effects of geometric array parameters (e.g., angle and diameter of jet inlets, number of inlets and their respective orientation) and operating conditions (e.g., jet velocities, fuel-air ratio) on flame structure and dynamics are studied using large eddy simulations (LES). The simulations are performed in OpenFOAM using multi-step chemistry for a methane-air mixture, and temperature and chemical composition fields are characterized for a variety of configurations as functions of height above the array. Implications of these results for the design and operation of industrial burners are outlined.

Combustion of alternative fuels in vortex trapped combustor

International Nuclear Information System (INIS)

Ghenai, Chaouki; Zbeeb, Khaled; Janajreh, Isam

2013-01-01

Highlights: ► We model the combustion of alternative fuels in trapped vortex combustor (TVC). ► We test syngas and hydrogen/hydrocarbon mixture fuels. ► We examine the change in combustion performance and emissions of TVC combustor. ► Increasing the hydrogen content of the fuel will increase the temperature and NO x emissions. ► A high combustor efficiency is obtained for fuels with different compositions and LHV. - Abstract: Trapped vortex combustor represents an efficient and compact combustor for flame stability. Combustion stability is achieved through the use of cavities in which recirculation zones of hot products generated by the direct injection of fuel and air are created and acting as a continuous source of ignition for the incoming main fuel–air stream. Computational Fluid Dynamics analysis was performed in this study to test the combustion performance and emissions from the vortex trapped combustor when natural gas fuel (methane) is replaced with renewable and alternative fuels such as hydrogen and synthetic gas (syngas). The flame temperature, the flow field, and species concentrations inside the Vortex Trapped Combustor were obtained. The results show that hydrogen enriched hydrocarbon fuels combustion will result in more energy, higher temperature (14% increase when methane is replaced with hydrogen fuels) and NO x emissions, and lower CO 2 emissions (50% decrease when methane is replaced with methane/hydrogen mixture with 75% hydrogen fraction). The NO x emission increases when the fraction of hydrogen increases for methane/hydrogen fuel mixture. The results also show that the flame for methane combustion fuel is located in the primary vortex region but it is shifted to the secondary vortex region for hydrogen combustion.

Capturing energy from ventilation air methane a preliminary design for a new approach

International Nuclear Information System (INIS)

Cluff, D.L.; Kennedy, G.A.; Bennett, J.G.; Foster, P.J.

2015-01-01

Methane is a potent greenhouse gas (GHG), discharged to the atmosphere by coalmining, the natural gas industry and natural biological processes, second only to carbon dioxide; thus, any reduction in atmospheric methane would be globally beneficial. The capture or use of ventilation air methane (VAM) is challenging because it is a high volume low concentration methane source. This results in the routine discharge of methane into the atmosphere. A review of VAM mitigation technologies is provided and the main disadvantages of the existing technologies are discussed. In the proposed VamTurBurner © system, the heat from the combustion chamber is transferred to the preheating zone either by a heat exchanger or by redirecting the combustion products to mix with the ventilation air stream from a coalmine. Gas turbines (GT) are used to produce electricity with the exhaust gases directed to mix with the incoming ventilation airflow. The turbulence introduced by the GT exhaust assists with mixing of the incoming ventilation airflow and the return flow of combustion products from the combustion chamber. The combustion products are a source of heat, which increases the temperature of the incoming ventilation air to a value high enough for the methane to undergo flameless combustion upon encountering the igniters. The high temperature combustion products enter a multi-generation system. The multi-generation system is based on mature engineering technology such as heat exchangers and steam turbines. The residual heat provides additional heat based products such as industrial scale drying, chilling by an absorption chiller or simply hot water. The VamTurBurner © uses the energy from the GT, igniters and VAM to provide clean efficient energy while mitigating the atmospheric emissions of methane. The opportunity to collect carbon credits may improve the economics. Since the VAM is a free energy source, the output of the system is greater than the purchased energy. - Highlights: �

Study on Characteristics of Co-firing Ammonia/Methane Fuels under Oxygen Enriched Combustion Conditions

Science.gov (United States)

Xiao, Hua; Wang, Zhaolin; Valera-Medina, Agustin; Bowen, Philip J.

2018-06-01

Having a background of utilising ammonia as an alternative fuel for power generation, exploring the feasibility of co-firing ammonia with methane is proposed to use ammonia to substitute conventional natural gas. However, improvement of the combustion of such fuels can be achieved using conditions that enable an increase of oxygenation, thus fomenting the combustion process of a slower reactive molecule as ammonia. Therefore, the present study looks at oxygen enriched combustion technologies, a proposed concept to improve the performance of ammonia/methane combustion. To investigate the characteristics of ammonia/methane combustion under oxygen enriched conditions, adiabatic burning velocity and burner stabilized laminar flame emissions were studied. Simulation results show that the oxygen enriched method can help to significantly enhance the propagation of ammonia/methane combustion without changing the emission level, which would be quite promising for the design of systems using this fuel for practical applications. Furthermore, to produce low computational-cost flame chemistry for detailed numerical analyses for future combustion studies, three reduced combustion mechanisms of the well-known Konnov's mechanism were compared in ammonia/methane flame simulations under practical gas turbine combustor conditions. Results show that the reduced reaction mechanisms can provide good results for further analyses of oxygen enriched combustion of ammonia/methane. The results obtained in this study also allow gas turbine designers and modellers to choose the most suitable mechanism for further combustion studies and development.

A parametric study of microjet assisted methane/air turbulent flames

International Nuclear Information System (INIS)

Chouaieb, Sirine; Kriaa, Wassim; Mhiri, Hatem; Bournot, Philippe

2017-01-01

Highlights: • Microjet assisted methane/air turbulent flames are numerically investigated. • A parametric study concerning the microjet velocity and diameter is carried out. • Previous validation of temperature, mixture fraction and soot is enhanced. • Mixing and soot emission are controlled for higher velocities and lower diameters. • Soot production is reduced by 94% for a microjet velocity equal to 1 m/s. - Abstract: A parametric study of microjet assisted methane/air turbulent flames characteristics is numerically investigated. The Presumed Probability Density Function model and the Discrete Ordinates model are respectively considered for combustion and radiation modeling. The k-epsilon Standard model with Pope Correction is adopted as a turbulence closure model. The two step Tesner model is used to quantify the soot particle production in the flame configuration. Comparison with our previous work using the k-epsilon Realizable model shows that the k-epsilon Standard model with Pope Correction ensures better predictions. The microjet velocity and diameter effects on thermal field, mixing process and soot emission are then discussed. Numerical findings show that the microjet can be used as an efficient tool controlling methane/air turbulent flames. On the one hand, it is shown that the microjet creates an inner flame in the vicinity of the central nozzle exit but does not globally alter the methane/air flame shape. On the other hand, mixing process can be enhanced for high microjet Reynolds number either by increasing the microjet velocity or by decreasing its nozzle diameter for a constant microjet mass flow rate. Soot production can be consequently reduced for low microjet diameter and high velocity values.

Lean hydrous and anhydrous bioethanol combustion in spark ignition engine at idle

International Nuclear Information System (INIS)

Chuepeng, Sathaporn; Srisuwan, Sudecha; Tongroon, Manida

2016-01-01

Highlights: • Anhydrous ethanol burns fastest in uncalibrated engine at equal equivalence ratio. • The leaner hydrous ethanol combustion tends to elevate the COV in imep. • Hydrous ethanol consumption was 10% greater than anhydrous ethanol at ϕ = 0.67 limit. • Optimizing alternative fuel engine at idle for stability and emission is suggested. - Abstract: The applications of anhydrous bioethanol to substitute or replace gasoline fuel have shown to attain benefits in terms of engine thermal efficiency, power output and exhaust emissions from spark ignition engines. A hydrous bioethanol has also been gained more attention due to its energy and cost effectiveness. The main aim of this work is to minimize fuel quantity injected to the intake ports of a four-cylinder engine under idle condition. The engine running with hydrous ethanol undergoes within lean-burn condition as its combustion stability is analyzed using an engine indicating system. Coefficient of variation in indicated mean effective pressure is an indicator for combustion stability with hydrocarbon and carbon monoxide emission monitoring as a supplement. Anhydrous ethanol burns faster than hydrous ethanol and gasoline in the uncalibrated engine at the same fuel-to-air equivalence ratio under idle condition. The leaner hydrous ethanol combustion tends to elevate the coefficient of variation in indicated mean effective pressure. The experimental results have found that the engine consumes greater hydrous ethanol by 10% on mass basis compared with those of anhydrous ethanol at the lean limit of fuel-to-air equivalence ratio of 0.67. The results of exhaust gas analysis were compared with those predicted by chemical equilibrium analysis of the fuel-air combustion; the resemble trends were found. Calibrating the alternative fueled engine for fuel injection quantity should be accomplished at idle with combustion stability and emissions optimization.

Effect of pressure on high Karlovitz number lean turbulent premixed hydrogen-enriched methane-air flames using LES

Science.gov (United States)

Cicoria, David; Chan, C. K.

2017-07-01

Large eddy simulation (LES) is employed to investigate the effect of pressure on lean CH4-H2-air turbulent premixed flames at high Karlovitz number for mixtures up to 60% of hydrogen in volume. The subfilter combustion term representing the interaction between turbulence and chemistry is modelled using the PaSR model, along with complex chemistry using a skeletal mechanism based on GRI-MECH3.0. The influence of pressure at high turbulence levels is studied by means of the local flame structure, and the assessment of species formation inside the flame. Results show that the ratio of turbulent flame thickness to laminar flame thickness δt/δu increases faster with pressure, and increases with the fraction of hydrogen in the mixture, leading to higher ratio of turbulent to laminar flame speed. The flame displays smaller structures and higher degree of wrinkling at higher pressure. Final species of CO2 and H2O formation is almost independent of pressure. For intermediate species CO and OH, an increase in pressure at constant volume fraction of hydrogen β leads to a decrease of emission of these species.

Controlled auto-ignition characteristics of methane-air mixture in a rapid intake compression and expansion machine

Energy Technology Data Exchange (ETDEWEB)

Cho, Gyubaek; Jeong, Dongsoo [Engine Research Team, Eco-Machinery Research Division, Korea Institute of Machinery and Materials, 104 Sinseongno, Yuseong-gu, Daejeon 305-701 (Korea); Moon, Gunfeel [Department of Clean Environmental system, University of Science and Technology, 52 Eoeun-dong, Yuseong-gu, Daejeon (Korea); Bae, Choongsik [Engine Laboratory, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 373-1 GuSeong-Dong, Yuseong-Gu, Daejeon 305-701 (Korea)

2010-10-15

The characteristics of controlled auto-ignition (CAI) were investigated with a methane-air mixture and simulated residual gas, that represents internal exhaust gas recirculation (IEGR). Supply systems were additionally installed on the conventional rapid compression machine (RCM), and this modified machine - a rapid intake compression and expansion machine (RICEM) - was able to simulate an intake stroke for the evaluation of controlled auto-ignition with fuel-air mixture. The fuel-air mixture and the simulated residual gas were introduced separately into the combustion chamber through the spool valves. Various IEGR rates and temperatures of the IEGR gas were tested. The initial reaction and the development in controlled auto-ignition combustion were compared with spark-ignited combustion by visualization with a high-speed digital camera. Under the controlled auto-ignition operation, multi-point ignition and faster combustion were observed. With increasing the temperature of IEGR gas, the auto-ignition timing was advanced and burning duration was shortened. The higher rate of IEGR had the same effects on the combustion of the controlled auto-ignition. However, this trend was reversed with more than 47 per cent of IEGR. (author)

Trends for Methane Oxidation at Solid Oxide Fuel Cell Conditions

DEFF Research Database (Denmark)

Kleis, Jesper; Jones, Glenn; Abild-Pedersen, Frank

2009-01-01

First-principles calculations are used to predict a plausible reaction pathway for the methane oxidation reaction. In turn, this pathway is used to obtain trends in methane oxidation activity at solid oxide fuel cell (SOFC) anode materials. Reaction energetics and barriers for the elementary...... the Ni surfaces to other metals of interest. This allows the reactivity over the different metals to be understood in terms of two reactivity descriptors, namely, the carbon and oxygen adsorption energies. By combining a simple free-energy analysis with microkinetic modeling, activity landscapes of anode...

Methane flux across the air-water interface - Air velocity effects

Science.gov (United States)

Sebacher, D. I.; Harriss, R. C.; Bartlett, K. B.

1983-01-01

Methane loss to the atmosphere from flooded wetlands is influenced by the degree of supersaturation and wind stress at the water surface. Measurements in freshwater ponds in the St. Marks Wildlife Refuge, Florida, demonstrated that for the combined variability of CH4 concentrations in surface water and air velocity over the water surface, CH4 flux varied from 0.01 to 1.22 g/sq m/day. The liquid exchange coefficient for a two-layer model of the gas-liquid interface was calculated as 1.7 cm/h for CH4 at air velocity of zero and as 1.1 + 1.2 v to the 1.96th power cm/h for air velocities from 1.4 to 3.5 m/s and water temperatures of 20 C.

Reduced detonation kinetics and detonation structure in one- and multi-fuel gaseous mixtures

Science.gov (United States)

Fomin, P. A.; Trotsyuk, A. V.; Vasil'ev, A. A.

2017-10-01

Two-step approximate models of chemical kinetics of detonation combustion of (i) one-fuel (CH4/air) and (ii) multi-fuel gaseous mixtures (CH4/H2/air and CH4/CO/air) are developed for the first time. The models for multi-fuel mixtures are proposed for the first time. Owing to the simplicity and high accuracy, the models can be used in multi-dimensional numerical calculations of detonation waves in corresponding gaseous mixtures. The models are in consistent with the second law of thermodynamics and Le Chatelier’s principle. Constants of the models have a clear physical meaning. Advantages of the kinetic model for detonation combustion of methane has been demonstrated via numerical calculations of a two-dimensional structure of the detonation wave in a stoichiometric and fuel-rich methane-air mixtures and stoichiometric methane-oxygen mixture. The dominant size of the detonation cell, determines in calculations, is in good agreement with all known experimental data.

Spark ignition natural gas engines-A review

International Nuclear Information System (INIS)

Cho, Haeng Muk; He, Bang-Quan

2007-01-01

Natural gas is a promising alternative fuel to meet strict engine emission regulations in many countries. Natural gas engines can operate at lean burn and stoichiometric conditions with different combustion and emission characteristics. In this paper, the operating envelope, fuel economy, emissions, cycle-to-cycle variations in indicated mean effective pressure and strategies to achieve stable combustion of lean burn natural gas engines are highlighted. Stoichiometric natural gas engines are briefly reviewed. To keep the output power and torque of natural gas engines comparable to those of their gasoline or Diesel counterparts, high boost pressure should be used. High activity catalyst for methane oxidation and lean deNOx system or three way catalyst with precise air-fuel ratio control strategies should be developed to meet future stringent emission standards

Effect of pressure on the lean limit flames of H2-CH4-air mixture in tubes

NARCIS (Netherlands)

Zhou, Z.; Shoshyn, Y.; Hernandez Perez, F.E.; van Oijen, J.A.; de Goey, L.P.H.

2017-01-01

The lean limit flames of H2-CH4-air mixtures stabilized inside tubes in a downward flow are experimentally and numerically investigated at elevated pressures ranging from 2 to 5 bar. For the shapes of lean limit flames, a change from ball-like flame to cap-like flame is experimentally observed with

Application of Hydrogen Assisted Lean Operation to Natural Gas-Fueled Reciprocating Engines (HALO)

Energy Technology Data Exchange (ETDEWEB)

Chad Smutzer

2006-01-01

Two key challenges facing Natural Gas Engines used for cogeneration purposes are spark plug life and high NOx emissions. Using Hydrogen Assisted Lean Operation (HALO), these two keys issues are simultaneously addressed. HALO operation, as demonstrated in this project, allows stable engine operation to be achieved at ultra-lean (relative air/fuel ratios of 2) conditions, which virtually eliminates NOx production. NOx values of 10 ppm (0.07 g/bhp-hr NO) for 8% (LHV H2/LHV CH4) supplementation at an exhaust O2 level of 10% were demonstrated, which is a 98% NOx emissions reduction compared to the leanest unsupplemented operating condition. Spark ignition energy reduction (which will increase ignition system life) was carried out at an oxygen level of 9%, leading to a NOx emission level of 28 ppm (0.13 g/bhp-hr NO). The spark ignition energy reduction testing found that spark energy could be reduced 22% (from 151 mJ supplied to the coil) with 13% (LHV H2/LHV CH4) hydrogen supplementation, and even further reduced 27% with 17% hydrogen supplementation, with no reportable effect on NOx emissions for these conditions and with stable engine torque output. Another important result is that the combustion duration was shown to be only a function of hydrogen supplementation, not a function of ignition energy (until the ignitability limit was reached). The next logical step leading from these promising results is to see how much the spark energy reduction translates into increase in spark plug life, which may be accomplished by durability testing.

Fossil fuel usage and the environment

International Nuclear Information System (INIS)

Klass, D.L.

1991-01-01

The Greenhouse Effect and global warming, ozone formation in the troposphere, ozone destruction in the stratosphere, and acid rain are important environmental issues. The relationship of fossil fuel usage to some of these issues is discussed. Data on fossil fuel consumption and the sources and sinks of carbon dioxide, carbon monoxide, methane, nitrogen and sulfur oxides, and ozone indicate that natural gas provides lower emissions of carbon dioxide, carbon monoxide, and nitrogen and sulfur oxides than other fossil fuels. Global emissions of methane from the gas industry are significantly less than those from other anthropogenic activities and natural sources, and methane plays an important role along with carbon monoxide and nitric oxide in tropospheric ozone formation. Reductions in any or all of these air pollutants would reduce ozone in the lower atmosphere. Several remedial measures have been or are being implemented in certain countries to reduce fossil fuel emissions. These include removal of emissions from the atmosphere by new biomass growth, fuel substitution by use of cleaner burning fuels for stationary and mobile sources, and fossil fuel combustion at higher efficiencies. It is unlikely that concerted environmental action by all governments of the world will occur soon, but much progress has been made to achieve clean air

Methane-free biogas for direct feeding of solid oxide fuel cells

Science.gov (United States)

Leone, P.; Lanzini, A.; Santarelli, M.; Calì, M.; Sagnelli, F.; Boulanger, A.; Scaletta, A.; Zitella, P.

This paper deals with the experimental analysis of the performance and degradation issues of a Ni-based anode-supported solid oxide fuel cell fed by a methane-free biogas from dark-anaerobic digestion of wastes by pastry and fruit shops. The biogas is produced by means of an innovative process where the biomass is fermented with a pre-treated bacteria inoculum (Clostridia) able to completely inhibit the methanization step during the fermentation process and to produce a H 2/CO 2 mixture instead of conventional CH 4/CO 2 anaerobic digested gas (bio-methane). The proposed biogas production route leads to a biogas composition which avoids the need of introducing a reformer agent into or before the SOFC anode in order to reformate it. In order to analyse the complete behaviour of a SOFC with the bio-hydrogen fuel, an experimental session with several H 2/CO 2 synthetic mixtures was performed on an anode-supported solid oxide fuel cell with a Ni-based anode. It was found that side reactions occur with such mixtures in the typical thermodynamic conditions of SOFCs (650-800 °C), which have an effect especially at high currents, due to the shift to a mixture consisting of hydrogen, carbon monoxide, carbon dioxide and water. However, cells operated with acceptable performance and carbon deposits (typical of a traditional hydrocarbon-containing biogas) were avoided after 50 h of cell operation even at 650 °C. Experiments were also performed with traditional bio-methane from anaerobic digestion with 60/40 vol% of composition. It was found that the cell performance dropped after few hours of operation due to the formation of carbon deposits. A short-term test with the real as-produced biogas was also successfully performed. The cell showed an acceptable power output (at 800 °C, 0.35 W cm -2 with biogas, versus 0.55 W cm -2 with H 2) although a huge quantity of sulphur was present in the feeding fuel (hydrogen sulphide at 103 ppm and mercaptans up to 10 ppm). Therefore, it

Methane-free biogas for direct feeding of solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Leone, P.; Lanzini, A.; Santarelli, M.; Cali, M. [Dipartimento di Energetica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin (Italy); Sagnelli, F.; Boulanger, A.; Scaletta, A.; Zitella, P. [BioEnergy Lab, Environment Park S.p.A., Via Livorno 60, 10144 Turin (Italy)

2010-01-01

This paper deals with the experimental analysis of the performance and degradation issues of a Ni-based anode-supported solid oxide fuel cell fed by a methane-free biogas from dark-anaerobic digestion of wastes by pastry and fruit shops. The biogas is produced by means of an innovative process where the biomass is fermented with a pre-treated bacteria inoculum (Clostridia) able to completely inhibit the methanization step during the fermentation process and to produce a H{sub 2}/CO{sub 2} mixture instead of conventional CH{sub 4}/CO{sub 2} anaerobic digested gas (bio-methane). The proposed biogas production route leads to a biogas composition which avoids the need of introducing a reformer agent into or before the SOFC anode in order to reformate it. In order to analyse the complete behaviour of a SOFC with the bio-hydrogen fuel, an experimental session with several H{sub 2}/CO{sub 2} synthetic mixtures was performed on an anode-supported solid oxide fuel cell with a Ni-based anode. It was found that side reactions occur with such mixtures in the typical thermodynamic conditions of SOFCs (650-800 C), which have an effect especially at high currents, due to the shift to a mixture consisting of hydrogen, carbon monoxide, carbon dioxide and water. However, cells operated with acceptable performance and carbon deposits (typical of a traditional hydrocarbon-containing biogas) were avoided after 50 h of cell operation even at 650 C. Experiments were also performed with traditional bio-methane from anaerobic digestion with 60/40 vol% of composition. It was found that the cell performance dropped after few hours of operation due to the formation of carbon deposits. A short-term test with the real as-produced biogas was also successfully performed. The cell showed an acceptable power output (at 800 C, 0.35 W cm{sup -2} with biogas, versus 0.55 W cm{sup -2} with H{sub 2}) although a huge quantity of sulphur was present in the feeding fuel (hydrogen sulphide at 103 ppm and

Carbon fibre composite for ventilation air methane (VAM) capture

International Nuclear Information System (INIS)

Thiruvenkatachari, Ramesh; Su Shi; Yu Xinxiang

2009-01-01

Coal mine methane (CMM) is not only a hazardous greenhouse gas but is also a wasted energy resource, if not utilised. This paper evaluates a novel adsorbent material developed for capturing methane from ventilation air methane (VAM) gas in underground coal mines. The adsorbent material is a honeycomb monolithic carbon fibre composite (HMCFC) consisting of multiple parallel flow-through channels and the material exhibits unique features including low pressure drop, good mechanical properties, ability to handle dust-containing gas streams, good thermal and electrical conductivity and selective adsorption of gases. During this study, a series of HMCFC adsorbents (using different types of carbon fibres) were successfully fabricated. Experimental data demonstrated the proof-of-concept of using the HMCFC adsorbent to capture methane from VAM gas. The adsorption capacity of the HMCFC adsorbent was twice that of commercial activated carbon. Methane concentration of 0.56% in the inlet VAM gas stream is reduced to about 0.011% after it passes through the novel carbon fibre composite adsorbent material at ambient temperature and atmospheric pressure. This amounts to a maximum capture efficiency of 98%. These encouraging laboratory scale studies have prompted further large scale trials and economic assessment.

Synthesis and analysis of a closed cycle methane-fueled marine energy process

International Nuclear Information System (INIS)

Teich, C.I.

1983-01-01

A marine energy system has been synthesized from state-of-the-art technology to convert nuclear derived electricity into liquefied methane. In the first part of the process, the on-board process, liquid methane is burned in a combined gas turbine-steam turbine system to provide propulsion power and the carbon dioxide created during combustion recovered. In the second part of the process, the fuel regeneration process, the methane is regenerated in a centralized land-based facility by the reaction of the recovered carbon dioxide with hydrogen obtained from nuclear-powered electrolysis of water. The system was analyzed by combining thermodynamic available energy analysis and an approximate preliminary design. The available energy analysis of the combined system established the thermodynamic feasibility of the methane-carbon dioxide cycle and resulted in various process improvements because of the inefficiencies disclosed by the analysis. The more critical on-board process was analyzed and developed further by a capital cost optimization and ranking alternate process options by their available energy consumptions. The optimal on-board process, whose capital cost is 16% less than the preliminary design, has an effectiveness of 47% and the fuel regeneration process an effectiveness of 56%. It was also found that the process cost was proportional to the horsepower raised to the seven-tenths power

Final Report: Room Temperature Electrochemical Upgrading of Methane to Oxygenate Fuels

Energy Technology Data Exchange (ETDEWEB)

Mustain, William

2018-01-02

The overall objective of this project is to discover the nature of the electrochemically active sites and to uncover the mechanisms for the electrocatalytic transformation of small organic molecules to oxygenate products such as methanol, formaldehyde, carbon monoxide and acetylene. Among the feedstocks of interest in this study are: methane, carbon dioxide, and acetic acid. Methane is an incredibly attractive potential feedstock because of the recent discovery of large shale deposits; carbon dioxide is potentially a very available feedstock from carbon capture technologies; acetic acid (as well as CH4 and CO2 and ethanol) has potential as a bio-derived feedstock. This report summarizes the major results to date regarding the electrochemical transformation of CH4, CO2 and acetic acid to chemicals and fuels – with a primary focus on methane. Finer details are available in each of the projects annual reports. In addition to the primary objective, the work in this project has led to synergistic discoveries that are advantageous to other fields including: catalyst layer deposition, anion exchange membrane fuel cells, CO2 capture and li-ion batteries. Those are very briefly discussed as well.

Effect of burner geometry on swirl stabilized methane/air flames: A joint LES/OH-PLIF/PIV study

KAUST Repository

Liu, X.

2017-07-04

Large eddy simulation (LES) using a transported PDF model and OH-PLIF/PIV experiments were carried out to investigate the quarl effects on the structures of swirl stabilized methane/air flames. Two different quarls were investigated, one straight cylindrical quarl and one diverging conical quarl. The experiments show that the flames are significantly different with the two quarls. With the straight cylindrical quarl a compact blue flame is observed while with the diverging conical quarl the flame appears to be long and yellow indicating a sooty flame structure. The PIV results show the formation of a stronger flow recirculation inside the diverging conical quarl than that in the straight quarl. LES results reveal further details of the flow and mixing process inside the quarl. The results show that with the diverging quarl vortex breakdown occurs much earlier towards the upstream of the quarl. As a result the fuel is convected into the air flow tube and a diffusion flame is stabilized inside the air flow tube upstream the quarl. With the straight quarl, vortex breakdown occurs at a downstream location in the quarl. The scalar dissipation rate in the shear layer of the fuel jet is high, which prevents the stabilization of a diffusion flame in the proximity of the fuel nozzle; instead, a compact partially premixed flame with two distinct heat release layers is stablized in a downstream region in the quarl, which allows for the fuel and air to mix in the quarl before combustion and a lower formation rate of soot. The results showed that the Eulerian Stochastic Fields transported PDF method can well predict the details of the swirl flame dynamics.

Effect of burner geometry on swirl stabilized methane/air flames: A joint LES/OH-PLIF/PIV study

KAUST Repository

Liu, X.; Elbaz, Ayman M.; Gong, C.; Bai, X.S.; Zheng, H.T.; Roberts, William L.

2017-01-01

Large eddy simulation (LES) using a transported PDF model and OH-PLIF/PIV experiments were carried out to investigate the quarl effects on the structures of swirl stabilized methane/air flames. Two different quarls were investigated, one straight cylindrical quarl and one diverging conical quarl. The experiments show that the flames are significantly different with the two quarls. With the straight cylindrical quarl a compact blue flame is observed while with the diverging conical quarl the flame appears to be long and yellow indicating a sooty flame structure. The PIV results show the formation of a stronger flow recirculation inside the diverging conical quarl than that in the straight quarl. LES results reveal further details of the flow and mixing process inside the quarl. The results show that with the diverging quarl vortex breakdown occurs much earlier towards the upstream of the quarl. As a result the fuel is convected into the air flow tube and a diffusion flame is stabilized inside the air flow tube upstream the quarl. With the straight quarl, vortex breakdown occurs at a downstream location in the quarl. The scalar dissipation rate in the shear layer of the fuel jet is high, which prevents the stabilization of a diffusion flame in the proximity of the fuel nozzle; instead, a compact partially premixed flame with two distinct heat release layers is stablized in a downstream region in the quarl, which allows for the fuel and air to mix in the quarl before combustion and a lower formation rate of soot. The results showed that the Eulerian Stochastic Fields transported PDF method can well predict the details of the swirl flame dynamics.

Hydrogen Addition for Improved Lean Burn Capability on Natural Gas Engine

Energy Technology Data Exchange (ETDEWEB)

Andersson, Tobias [Lund Inst. of Technology (Sweden). Dept. of Heat and Power Engineering

2002-12-01

Lean burn spark ignition (SI) engines powered by natural gas is an attractive alternative to the Diesel engine, especially in urban traffic, where reduction of tailpipe emissions are of great importance. A major benefit is the large reduction in soot (PM). Lean burn spark ignition (SI) engines yield high fuel conversion efficiency and also relatively low NO{sub x} emissions at full load. In order to improve the engine operating characteristics at lower loads, the {lambda}-value is normally reduced to some degree, with increased NO{sub x} emissions and reduced efficiency as a result. This is a drawback for the lean burn engines, especially in urban applications such as in city buses and distribution trucks for urban use. So, it is desirable to find ways to extend the lean limit at low loads. One way to improve these part load properties is to add hydrogen to the natural gas in order to improve the combustion characteristics of the fuel. It is possible to extend the lean limit of a natural gas engine by addition of hydrogen to the primary fuel. This report presents measurements made on a single cylinder 1.6 liter natural gas engine. Two combustion chambers, one slow and one fast burning, were tested with various amounts of hydrogen (0 to 20 %-vol) added to natural gas. Three operating conditions were investigated for each combustion chamber and each hydrogen content level; idle, wide open throttle (WOT) and a high load condition (simulated turbo charging). For all three operating conditions, the air/fuel ratio was varied between stoichiometric and the lean limit. For each operating point, the ignition timing was swept in order to find maximum brake torque (MBT) timing. In some cases were the ignition timing limited by knock. Heat release rate calculations were made in order to assess the influence of hydrogen addition on burn rate. Addition of hydrogen showed an increase in burn rate for both combustion chambers, resulting in more stable combustion close to the lean

Behavioral Characteristics of the Non-Premixed Methane-Air Flame Oppositely Injected in a Narrow Channel

International Nuclear Information System (INIS)

Yun, Young Min; Lee, Min Jung; Cho, Sang Moon; Kim, Nam Il

2009-01-01

Characteristics of a counter flowing diffusion flame, which is formulated by an oppositely-injected methane-jet flow in a narrow channel of a uniform air flow. The location of the flame fronts and the flame lengths were compared by changing the flow rates of fuel. To distinguish the effects of the narrow channel on the diffusion flame, a numerical simulation for an ideal two-dimensional flame was conducted. Overall trends of the flame behavior were similar in both numerical and experimental results. With the increase of the ratio of jet velocity to air velocity flame front moved farther upstream. It is thought that the flow re-direction in the channel suppresses fuel momentum more significantly due to the higher temperature and increased viscosity of burned gas. Actual flames in a narrow channel suffer heat loss to the ambient and it has finite length of diffusion flame in contrast to the numerical results of infinite flame length. Thus a convective heat loss was additionally employed in numerical simulation and closer results were obtained. These results can be used as basic data in development of a small combustor of a nonpremixed flame

Behavioral Characteristics of the Non-Premixed Methane-Air Flame Oppositely Injected in a Narrow Channel

Energy Technology Data Exchange (ETDEWEB)

Yun, Young Min; Lee, Min Jung; Cho, Sang Moon; Kim, Nam Il [Chungang University, Seoul (Korea, Republic of)

2009-04-15

Characteristics of a counter flowing diffusion flame, which is formulated by an oppositely-injected methane-jet flow in a narrow channel of a uniform air flow. The location of the flame fronts and the flame lengths were compared by changing the flow rates of fuel. To distinguish the effects of the narrow channel on the diffusion flame, a numerical simulation for an ideal two-dimensional flame was conducted. Overall trends of the flame behavior were similar in both numerical and experimental results. With the increase of the ratio of jet velocity to air velocity flame front moved farther upstream. It is thought that the flow re-direction in the channel suppresses fuel momentum more significantly due to the higher temperature and increased viscosity of burned gas. Actual flames in a narrow channel suffer heat loss to the ambient and it has finite length of diffusion flame in contrast to the numerical results of infinite flame length. Thus a convective heat loss was additionally employed in numerical simulation and closer results were obtained. These results can be used as basic data in development of a small combustor of a nonpremixed flame.

Comparison of alternate fuels for aircraft. [liquid hydrogen, liquid methane, and synthetic aviation kerosene

Science.gov (United States)

Witcofski, R. D.

1979-01-01

Liquid hydrogen, liquid methane, and synthetic aviation kerosene were assessed as alternate fuels for aircraft in terms of cost, capital requirements, and energy resource utilization. Fuel transmission and airport storage and distribution facilities are considered. Environmental emissions and safety aspects of fuel selection are discussed and detailed descriptions of various fuel production and liquefaction processes are given. Technological deficiencies are identified.

Comparison of Fuel-Nox Formation Characteristics in Conventional Air and Oxy fuel Combustion Conditions

International Nuclear Information System (INIS)

Woo, Mino; Park, Kweon Ha; Choi, Byung Chul

2013-01-01

Nitric oxide (NO x ) formation characteristics in non-premixed diffusion flames of methane fuels have been investigated experimentally and numerically by adding 10% ammonia to the fuel stream, according to the variation of the oxygen ratio in the oxidizer with oxygen/carbon dioxide and oxygen/nitrogen mixtures. In an experiment of co flow jet flames, in the case of an oxidizer with oxygen/carbon dioxide, the NO x emission increased slightly as the oxygen ratio increased. On the other hand, in case of an oxygen/nitrogen oxidizer, the NO x emission was the maximum at an oxygen ratio of 0.7, and it exhibited non-monotonic behavior according to the oxygen ratio. Consequently, the NO x emission in the condition of oxy fuel combustion was overestimated as compared to that in the condition of conventional air combustion. To elucidate the characteristics of NO x formation for various oxidizer compositions, 1a and 2a numerical simulations have been conducted by adopting one kinetic mechanism. The result of 2 simulation for an oxidizer with oxygen/nitrogen well predicted the trend of experimentally measured NO x emissions

Simulation of lean premixed turbulent combustion

International Nuclear Information System (INIS)

Bell, J; Day, M; Almgren, A; Lijewski, M; Rendleman, C; Cheng, R; Shepherd, I

2006-01-01

There is considerable technological interest in developing new fuel-flexible combustion systems that can burn fuels such as hydrogen or syngas. Lean premixed systems have the potential to burn these types of fuels with high efficiency and low NOx emissions due to reduced burnt gas temperatures. Although traditional Scientific approaches based on theory and laboratory experiment have played essential roles in developing our current understanding of premixed combustion, they are unable to meet the challenges of designing fuel-flexible lean premixed combustion devices. Computation, with its ability to deal with complexity and its unlimited access to data, has the potential for addressing these challenges. Realizing this potential requires the ability to perform high fidelity simulations of turbulent lean premixed flames under realistic conditions. In this paper, we examine the specialized mathematical structure of these combustion problems and discuss simulation approaches that exploit this structure. Using these ideas we can dramatically reduce computational cost, making it possible to perform high-fidelity simulations of realistic flames. We illustrate this methodology by considering ultra-lean hydrogen flames and discuss how this type of simulation is changing the way researchers study combustion

Influence of the Steam Addition on Premixed Methane Air Combustion at Atmospheric Pressure

Directory of Open Access Journals (Sweden)

Mao Li

2017-07-01

Full Text Available Steam-diluted combustion in gas turbine systems is an effective approach to control pollutant emissions and improve the gas turbine efficiency. The primary purpose of the present research is to analyze the influence of steam dilution on the combustion stability, flame structures, and CO emissions of a swirl-stabilized gas turbine model combustor under atmospheric pressure conditions. The premixed methane/air/steam flame was investigated with three preheating temperatures (384 K/434 K/484 K and the equivalence ratio was varied from stoichiometric conditions to the flammability limits where the flame was physically blown out from the combustor. In order to represent the steam dilution intensity, the steam fraction Ω defined as the steam to air mass flow rate ratio was used in this work. Exhaust gases were sampled with a water-cooled emission probe which was mounted at the combustor exit. A 120 mm length quartz liner was used which enabled the flame visualization and optical measurement. Time-averaged CH chemiluminescence imaging was conducted to characterize the flame location and it was further analyzed with the inverse Abel transform method. Chemical kinetics calculation was conducted to support and analyze the experimental results. It was found that the LBO (lean blowout limits were increased with steam fraction. CH chemiluminescence imaging showed that with a high steam fraction, the flame length was elongated, but the flame structure was not altered. CO emissions were mapped as a function of the steam fraction, inlet air temperature, and equivalence ratios. Stable combustion with low CO emission can be achieved with an appropriate steam fraction operation range.

Alternate aircraft fuels: Prospects and operational implications

Science.gov (United States)

Witcofski, R. D.

1977-01-01

The potential use of coal-derived aviation fuels was assessed. The studies addressed the prices and thermal efficiencies associated with the production of coal-derived aviation kerosene, liquid methane and liquid hydrogen and the air terminal requirements and subsonic transport performance when utilizing liquid hydrogen. The fuel production studies indicated that liquid methane can be produced at a lower price and with a higher thermal efficiency than aviation kerosene or liquid hydrogen. Ground facilities of liquefaction, storage, distribution and refueling of liquid hydrogen fueled aircraft at airports appear technically feasibile. The aircraft studies indicate modest onboard energy savings for hydrogen compared to conventional fuels. Liquid hydrogen was found to be superior to both aviation kerosene and liquid methane from the standpoint of aircraft engine emissions.

Catalytic reduction of methane/unburned hydrocarbons in smoke from lean-burn gas engines

International Nuclear Information System (INIS)

Wit, Jan de.

1999-01-01

The aim of this project has been: To describe the flue gas conditions of typical stationary gas engines for cogeneration; To evaluate the predominant causes of deactivation of oxidation catalysts under realistic operation conditions; To develop improved long-term stable oxidation catalysts; To evaluate alternative catalyst-based methane reduction technologies. Most gas engines for stationary purposes are efficient lean-burn gas engines. Both the high efficiency and the very lean operation lead to low exhaust temperatures. However, there is now a tendency to design engines with un-cooled exhaust manifolds. This leads to higher shaft efficiency and increases the exhaust temperature. Exhaust gas composition and temperatures during continuous operation and start/stops are given in this report. Analyses have been made of catalyst samples to find predominant causes for oxidation catalyst deactivation. The analyses have shown that the presence of sulphur dioxide in the flue gas causes sulphur poisoning on the active catalyst surface. This effect is dependent on both the catalyst formulation and the catalyst support material composition. Neither sintering, nor other poisoning components than sulphur have been on the examined catalyst samples. The sulphur dioxide in the exhaust is a result of the sulphur in the odorisation additive used in the natural gas (approx. 10 mg/n 3 m THT) and of the sulphur present in combusted lubrication oil. These sources leads to a level of approx. 0.3 - 0.6 ppm (vol) SO 2 in the exhaust gas. Based on a large number of laboratory tests, a new oxidation catalyst formulation has been developed and successfully tested over 5000 hours of operation at a commercial cogeneration plant. This long-term testing has been additionally supplemented by short-term testings at test sites to see performance under other operation conditions. It has been shown that a rise in flue gas temperature (from e.g. 450 deg. C) will significantly reduce the necessary

Analytical investigation of high temperature 1 kW solid oxide fuel cell system feasibility in methane hydrate recovery and deep ocean power generation

International Nuclear Information System (INIS)

Azizi, Mohammad Ali; Brouwer, Jacob; Dunn-Rankin, Derek

2016-01-01

Highlights: • A dynamic Solid Oxide Fuel Cell (SOFC) model was developed. • Hydrate bed methane dissociation model was integrated with the SOFC model. • SOFC operated steadily for 120 days at high pressure deep ocean environment. • Burning some of the dissociated gas for SMR heat leads to more net methane produced. • Higher SOFC fuel utilization produces higher integrated system efficiency. - Abstract: Methane hydrates are potential valuable energy resources. However, finding an efficient method for methane gas recovery from hydrate sediments is still a challenge. New challenges arise from increasing environmental protection. This is due in part to the technical difficulties involved in the efficient dissociation of methane hydrates at high pressures. In this study, a new approach is proposed to produce valuable products of: 1. Net methane gas recovery from the methane hydrate sediment, and 2. Deep ocean power generation. We have taken the first steps toward utilization of a fuel cell system in methane gas recovery from deep ocean hydrate sediments. An integrated high pressure and high temperature solid oxide fuel cell (SOFC) and steam methane reformer (SMR) system is analyzed for this application and the recoverable amount of methane from deep ocean sediments is measured. System analysis is accomplished for two major cases regarding system performance: 1. Energy for SMR is provided by the burning part of the methane gas dissociated from the hydrate sediment. 2. Energy for SMR is provided through heat exchange with fuel cell effluent gases. We found that the total production of methane gas is higher in the first case compared to the second case. The net power generated by the fuel cell system is estimated for all cases. The primary goal of this study is to evaluate the feasibility of integrated electrochemical devices to accomplish energy efficient dissociation of methane hydrate gases in deep ocean sediments. Concepts for use of electrochemical devices

Microwave Hydrogen Production from Methane

Science.gov (United States)

2012-04-01

combustion NOx control of reciprocating engine exhaust and fuel cell application of biogas . Our target is to obtain the methane conversion efficiency...demonstration of MW technology removing and destroying hydrogen sulfide (H2S) and siloxanes from biogas produced by Sacramento Regional Wastewater...running on biogas and is currently conducting the field demonstration of the unit at Tollenaar Dairy in Elk Grove, CA. SMUD, California Air Resources

A numerical simulation study on active species production in dense methane-air plasma discharge

Science.gov (United States)

Gui, LI; Muyang, QIAN; Sanqiu, LIU; Huaying, CHEN; Chunsheng, REN; Dezhen, WANG

2018-01-01

Recently, low-temperature atmospheric pressure plasmas have been proposed as a potential type of ‘reaction carrier’ for the conversion of methane into value-added chemicals. In this paper, the multi-physics field coupling software of COMSOL is used to simulate the detailed discharge characteristics of atmospheric pressure methane-air plasma. A two-dimensional axisymmetric fluid model is constructed, in which 77 plasma chemical reactions and 32 different species are taken into account. The spatial density distributions of dominant charged ions and reactive radical species, such as {{{CH}}}4+, {{{CH}}}3+, {{{N}}}2+, {{{O}}}2+, H, O, CH3, and CH2, are presented, which is due to plasma chemical reactions of methane/air dissociation (or ionization) and reforming of small fragment radical species. The physicochemical mechanisms of methane dissociation and radical species recombination are also discussed and analyzed.

The production of hydrogen through the uncatalyzed partial oxidation of methane in an internal combustion engine

Energy Technology Data Exchange (ETDEWEB)

Karim, Ghazi A.; Wierzba, I. [Department of Mechanical and Manufacturing Engineering, Schulich School of Engineering, University of Calgary, Calgary (Canada)

2008-04-15

The thermodynamic and kinetic limitations of the uncatalyzed partial oxidation of methane for the production of synthesis gas, which is made up of mostly hydrogen and carbon monoxide in a variety of proportions, are reviewed. It is suggested that such processes can be made to proceed successfully in a conventional internal combustion engine when operated on excessively rich mixtures of methane and oxygenated air. This is achieved while simultaneously producing power and regenerative exhaust gas heating. Experimental results are described that show a dual fuel engine of the compression ignition type with pilot liquid fuel injection can be operated on excessively rich mixtures of methane and air supplemented with oxygen gas to produce hydrogen rich gas with high methane conversion rates. Similarly, a spark ignition engine was reported to be equally capable of such production and performance. It is shown that there are viable prospects for the simultaneous production of synthesis gas in engines with efficient useful mechanical power and exhaust gas regenerative heating. (author)

Wartsila 32DF, the dual-fuel engine

Energy Technology Data Exchange (ETDEWEB)

Anon.

1999-06-01

This paper gives details of the development of the Wartsila 32DF duel-fuel lean-burn engine that can burn liquid or gaseous fuels, and reports on the installation of four of the engines in Turkey. The combustion process, and the design of the gas admission, pilot fuel, cylinder control, air-fuel control, and engine control and monitoring systems are described. The advantages of the engine are discussed.

Investigation on the lean combustion performance of a hydrogen-enriched n-butanol engine

International Nuclear Information System (INIS)

Zhang, Bo; Ji, Changwei; Wang, Shuofeng

2017-01-01

Highlights: • H_2 addition avails improving thermal efficiency of n-butanol engines. • Lean burn limit of n-butanol engine is extended by H_2 addition. • H_2 addition shortens the n-butanol engine combustion duration. • HC and CO from the n-butanol engine are decreased by H_2 addition. - Abstract: n-Butanol is a feasible fuel candidate for spark-ignition engines. The current paper carried out an experiment to explore effects of hydrogen addition on further improving the performance of a n-butanol engine under the part load and lean conditions. Within the test, the engine intake pressure and speed were respectively kept at 61.5 kPa and 1400 rpm. The volumetric fractions of hydrogen in the total intake gas (hydrogen + air) were constrained at 0 and 3%, respectively. Under a certain hydrogen blending level, the global excess air ratio of in-cylinder charge which was changed from the stoichiometric to near the lean burn limit was adjusted by varying the n-butanol injection duration. The experimental results confirmed that the brake thermal efficiency was heightened and the lean burn limit was extended after the hydrogen addition. Besides, compared with the pure n-butanol combustion, the hydrogen enrichment enables the engine to gain dropped ignition delay and rapid combustion duration. Moreover, CO and HC from the pure n-butanol engine were reduced by the hydrogen addition. NOx were generally reduced when the excess air ratio was raised. This suggested that NOx from the hydrogen-enriched butanol engine could also be controlled by lean combustion.

Internal reforming of methane in a mono-block-layer build solid oxide fuel cell with an embedding porous pipe: Numerical analysis

International Nuclear Information System (INIS)

Ramírez-Minguela, J.J.; Mendoza-Miranda, J.M.; Muñoz-Carpio, V.D.; Rangel-Hernández, V.H.; Pérez-García, V.; Rodríguez-Muñoz, J.L.

2014-01-01

Highlights: • A MOLB-type SOFC with different biogas compositions is modeled. • Internal reforming of methane and water gas shift in the anode side are considered. • Changes in the SOFC according to the phenomena inside of them are assessed. • A new configuration for the MOLB-type geometry is proposed. • Temperature gradients effects in the new configuration are significant. - Abstract: A mono-block-layer build type (MOLB-type) geometry, composed with trapezoidal cross-section channels for fuel and air, of solid oxide fuel cell (SOFC), is modeled in this study using a three dimensional computational fluid dynamics (CFD). The model is used to obtain the performance of the SOFC considering internal reforming of methane in the anode side with different biogas compositions. From the results obtained, a new configuration for the MOLB-type geometry is proposed. The model takes into account the mass transfer, heat transfer, species transport, chemical and electrochemical reactions, detailed comparisons of species concentration, temperature and electric fields inside the cell analyzed in the present study. Results show that the biogas from local sludge has the lower temperature gradient and more homogeneous current density distributions along of the fuel cell, on the other hand, with the new configuration proposed for the MOLB-type geometry the temperature distribution inside of the fuel cell has lower temperature gradients

Ventilation air methane destruction - the new challenge to the underground coal mining industry

International Nuclear Information System (INIS)

Clarke, Michael; Seddon, Duncan

2012-01-01

With the advent of 'Carbon Taxes' the carbon footprint of coal has become an economic as well as an environmental issue and the emission of methane in mine out- bye air as ventilation air methane (VAM) is a pending liability. As well as being economic and environmental concerns, VAM and VAM management have safety, social licence and operational factors that must also be addressed. The need to mitigate (oxidise) methane to produce carbon dioxide and water vapour (VAM destruction) and thus lower the Greenhouse footprint is coming to be seen as a necessary mining activity. However, there are several key issues to be addressed with present technology using high temperature (1000°C) thermal oxidisers. Emerging technology may involve a catalytic approach. This technology aims to lower the oxidation temperature and produce a more efficient combustion process. Several systems (based on both precious metals and transition metals) have been shown to operate below 400°C. An ultimate solution would be oxidation at ambient temperature, which is clearly demonstrated by the enzyme methane mono-oxygenase (MMO) which oxidises methane to methanol. However, the rate of oxidation at ambient temperature is too low and the structure of the bio-reactors required would be very large. The challenge is to marry the natural oxidation with modern catalytic approaches and achieve high rates of methane oxidation, in compact equipment, well below the methane auto-ignition temperature.

Syngas Generation from Methane Using a Chemical-Looping Concept: A Review of Oxygen Carriers

Directory of Open Access Journals (Sweden)

Kongzhai Li

2013-01-01

Full Text Available Conversion of methane to syngas using a chemical-looping concept is a novel method for syngas generation. This process is based on the transfer of gaseous oxygen source to fuel (e.g., methane by means of a cycling process using solid oxides as oxygen carriers to avoid direct contact between fuel and gaseous oxygen. Syngas is produced through the gas-solid reaction between methane and solid oxides (oxygen carriers, and then the reduced oxygen carriers can be regenerated by a gaseous oxidant, such as air or water. The oxygen carrier is recycled between the two steps, and the syngas with a ratio of H2/CO = 2.0 can be obtained successively. Air is used instead of pure oxygen allowing considerable cost savings, and the separation of fuel from the gaseous oxidant avoids the risk of explosion and the dilution of product gas with nitrogen. The design and elaboration of suitable oxygen carriers is a key issue to optimize this method. As one of the most interesting oxygen storage materials, ceria-based and perovskite oxides were paid much attention for this process. This paper briefly introduced the recent research progresses on the oxygen carriers used in the chemical-looping selective oxidation of methane (CLSOM to syngas.

Experimental and modeling study on effects of N2 and CO2 on ignition characteristics of methane/air mixture

Directory of Open Access Journals (Sweden)

Wen Zeng

2015-03-01

Full Text Available The ignition delay times of methane/air mixture diluted by N2 and CO2 were experimentally measured in a chemical shock tube. The experiments were performed over the temperature range of 1300–2100 K, pressure range of 0.1–1.0 MPa, equivalence ratio range of 0.5–2.0 and for the dilution coefficients of 0%, 20% and 50%. The results suggest that a linear relationship exists between the reciprocal of temperature and the logarithm of the ignition delay times. Meanwhile, with ignition temperature and pressure increasing, the measured ignition delay times of methane/air mixture are decreasing. Furthermore, an increase in the dilution coefficient of N2 or CO2 results in increasing ignition delays and the inhibition effect of CO2 on methane/air mixture ignition is stronger than that of N2. Simulated ignition delays of methane/air mixture using three kinetic models were compared to the experimental data. Results show that GRI_3.0 mechanism gives the best prediction on ignition delays of methane/air mixture and it was selected to identify the effects of N2 and CO2 on ignition delays and the key elementary reactions in the ignition chemistry of methane/air mixture. Comparisons of the calculated ignition delays with the experimental data of methane/air mixture diluted by N2 and CO2 show excellent agreement, and sensitivity coefficients of chain branching reactions which promote mixture ignition decrease with increasing dilution coefficient of N2 or CO2.

Air-cooled, hydrogen-air fuel cell

Science.gov (United States)

Shelekhin, Alexander B. (Inventor); Bushnell, Calvin L. (Inventor); Pien, Michael S. (Inventor)

1999-01-01

An air-cooled, hydrogen-air solid polymer electrolyte (SPE) fuel cell with a membrane electrode assembly operatively associated with a fluid flow plate having at least one plate cooling channel extending through the plate and at least one air distribution hole extending from a surface of the cathode flow field into the plate cooling channel.

Alternate aircraft fuels prospects and operational implications

Science.gov (United States)

Witcofski, R. D.

1977-01-01

The paper discusses NASA studies of the potentials of coal-derived aviation fuels, specifically synthetic aviation kerosene, liquid methane, and liquid hydrogen. Topics include areas of fuel production, air terminal requirements for aircraft fueling (for liquid hydrogen only), and the performance characteristics of aircraft designed to utilize alternate fuels. Energy requirements associated with the production of each of the three selected fuels are determined, and fuel prices are estimated. Subsonic commercial air transports using liquid hydrogen fuel have been analyzed, and their performance and the performance of aircraft which use commercial aviation kerosene are compared. Environmental and safety issues are considered.

Investigation of Gas Heating by Nanosecond Repetitively Pulsed Glow Discharges Used for Actuation of a Laminar Methane-Air Flame

KAUST Repository

Lacoste, Deanna

2017-05-24

This paper reports on the quantification of the heating induced by nanosecond repetitively pulsed (NRP) glow discharges on a lean premixed methane-air flame. The flame, obtained at room temperature and atmospheric pressure, has an M-shape morphology. The equivalence ratio is 0.95 and the thermal power released by the flame is 113 W. The NRP glow discharges are produced by high voltage pulses of 10 ns duration, 7 kV amplitude, applied at a repetition frequency of 10 kHz. The average power of the plasma, determined from current and voltage measurements, is 1 W, i.e. about 0.9 % of the thermal power of the flame. Broadband vibrational coherent anti-Stokes Raman spectroscopy of nitrogen is used to determine the temperature of the flame with and without plasma enhancement. The temperature evolution in the flame area shows that the thermal impact of NRP glow discharges is in the uncertainty range of the technique, i.e., +/- 40 K.

Combustion of lean hydrogen-air mixtures in the connected compartments

International Nuclear Information System (INIS)

Fan Liu; Yoshio Yoshizawa; Akio Miyori; Kenya Kubota

1997-01-01

A study of combustion experiments with premixed lean hydrogen-air mixtures was conducted in a vessel consisting of two compartments connected by a diameter-variable vent. Effects of various parameters (hydrogen concentration, vent diameter and initial pressure) on mechanical loads of the combustion processes including mainly the peak pressures and the rates of pressure rise were investigated. Relation of flow and combustion was approached. Ignition-combustion processes were discussed, and the combustion types were classified into three patterns according to the pressure-time histories and the flow characteristics in main combustion compartment

14 CFR Appendix N to Part 25 - Fuel Tank Flammability Exposure and Reliability Analysis

Science.gov (United States)

2010-01-01

..., Definitions). A non-flammable ullage is one where the fuel-air vapor is too lean or too rich to burn or is... Office for approval the fuel tank flammability analysis, including the airplane-specific parameters...

Coal-packed methane biofilter for mitigation of green house gas emissions from coal mine ventilation air.

Science.gov (United States)

Limbri, Hendy; Gunawan, Cindy; Thomas, Torsten; Smith, Andrew; Scott, Jason; Rosche, Bettina

2014-01-01

Methane emitted by coal mine ventilation air (MVA) is a significant greenhouse gas. A mitigation strategy is the oxidation of methane to carbon dioxide, which is approximately twenty-one times less effective at global warming than methane on a mass-basis. The low non-combustible methane concentrations at high MVA flow rates call for a catalytic strategy of oxidation. A laboratory-scale coal-packed biofilter was designed and partially removed methane from humidified air at flow rates between 0.2 and 2.4 L min-1 at 30°C with nutrient solution added every three days. Methane oxidation was catalysed by a complex community of naturally-occurring microorganisms, with the most abundant member being identified by 16S rRNA gene sequence as belonging to the methanotrophic genus Methylocystis. Additional inoculation with a laboratory-grown culture of Methylosinus sporium, as investigated in a parallel run, only enhanced methane consumption during the initial 12 weeks. The greatest level of methane removal of 27.2±0.66 g methane m-3 empty bed h-1 was attained for the non-inoculated system, which was equivalent to removing 19.7±2.9% methane from an inlet concentration of 1% v/v at an inlet gas flow rate of 1.6 L min-1 (2.4 min empty bed residence time). These results show that low-cost coal packing holds promising potential as a suitable growth surface and contains methanotrophic microorganisms for the catalytic oxidative removal of methane.

Improvement of performance and reduction of pollutant emissions of a four-stroke spark ignition engine fuelled with a mixture of hydrogen and methane as a supplementary fuel to alcohol

Energy Technology Data Exchange (ETDEWEB)

Al-Bagdhadi, M.A.-R.S. [University of Babylon (Iraq). College of Engineering

2004-05-01

Owing to the energy crisis and pollution problems of today, investigations have concentrated on decreasing fuel consumption and on lowering the concentration of toxic components in combustion products by using non-petroleum, renewable, sustainable and non-polluting fuels. While conventional energy sources such as natural gas, oil and coal are non-renewable, hydrogen and alcohol can be coupled to renewable and sustainable energy sources. The usage of a mixture of hydrogen and methane as a supplementary fuel to an alcohol-air mixture for spark ignition engines results in a considerable improvement in engine performance and in the reduction of the toxic components in exhaust gases in comparison with the conventional spark ignition gasoline engine. In tests, the gas comprising 40 per cent H, and 60 per cent CH{sub 4} by volume was added to alcohol as 0, 2, 4, 6, 8, 10 and 12 per cent by mass. Operating test results for a range of compression ratio (CR) and equivalent ratio are presented. Gasoline fuel was used as a basis for comparison. The important improvement in methane addition reduced the specific fuel consumption (s.f.c.) and CO emission of alcohol engines. The performance of the engine is enhanced when relatively small amounts of hydrogen are present with methane. This improvement in performance, which is especially pronounced at operational equivalence ratios that are much leaner than the stoichiometric value, can be attributed largely to the faster and cleaner burning characteristics of hydrogen in comparison with methane or alcohol. Moreover, the addition of hydrogen decreases the s.f.c. of the engine. The possibility of an engine power quality adjustment has also been studied. (author)

Effects of diluent admissions and intake air temperature in exhaust gas recirculation on the emissions of an indirect injection dual fuel engine

Energy Technology Data Exchange (ETDEWEB)

Abd-Alla, G.H.; Soliman, H.A.; Badr, O.A.; Abd-Rabbo, M.F. [Zagazig University, Cairo (Egypt). Shoubra Faculty of Engineering

2001-05-01

The operation of Diesel engines on gaseous fuels, commonly known as dual fuel engines, uses Diesel fuel as the pilot fuel and gaseous fuel (methane and sometimes propane in the present work) as the main fuel. The gaseous fuel was inducted in the intake manifold to mix with the intake air. The investigation was conducted on a high speed indirect injection (Ricardo-E6) dual fuel engine and was concerned with the effects of exhaust gas recirculation (EGR) on the dual fuel engine combustion and emissions, in particular, the effects of intake air temperature and diluent admissions (N{sub 2} and CO{sub 2}) on combustion and emissions. The use of diluents to displace oxygen (O{sub 2}) in the intake air resulted in a reduction in the O{sub 2} supplied to the engine, increased the inlet charge thermal capacity (thermal effect) and, potentially, CO{sub 2} and N{sub 2} participated in the combustion process (chemical effect). In a separate series of tests, the temperature of the engine inlet charge was raised gradually in order to simulate the effect of mixing hot EGR with the engine inlet gaseous fuel air mixture. It was found that the admission of diluents resulted in reductions in the exhaust oxides of nitrogen (NO{sub x}). Higher inlet charge temperature increases the exhaust NO{sub x} but reduces the unburned hydrocarbon emissions. Finally, when carbon dioxide was added to the inlet gaseous fuel air charge, large reductions in NO{sub x} were observed. (author)

Thermodynamic analysis of direct internal reforming of methane and butane in proton and oxygen conducting fuel cells

NARCIS (Netherlands)

Biesheuvel, P.M.; Geerlings, J.J.C.

2008-01-01

We present results of a thermodynamic analysis of direct internal reforming fuel cells, based on either a proton conducting fuel cell (FC-H+) or an oxygen ion conducting fuel cell (FC-O2-). We analyze the option of methane as fuel as well as butane. The model self-consistently combines all chemical

Coal-Packed Methane Biofilter for Mitigation of Green House Gas Emissions from Coal Mine Ventilation Air

Science.gov (United States)

Limbri, Hendy; Gunawan, Cindy; Thomas, Torsten; Smith, Andrew; Scott, Jason; Rosche, Bettina

2014-01-01

Methane emitted by coal mine ventilation air (MVA) is a significant greenhouse gas. A mitigation strategy is the oxidation of methane to carbon dioxide, which is approximately twenty-one times less effective at global warming than methane on a mass-basis. The low non-combustible methane concentrations at high MVA flow rates call for a catalytic strategy of oxidation. A laboratory-scale coal-packed biofilter was designed and partially removed methane from humidified air at flow rates between 0.2 and 2.4 L min−1 at 30°C with nutrient solution added every three days. Methane oxidation was catalysed by a complex community of naturally-occurring microorganisms, with the most abundant member being identified by 16S rRNA gene sequence as belonging to the methanotrophic genus Methylocystis. Additional inoculation with a laboratory-grown culture of Methylosinus sporium, as investigated in a parallel run, only enhanced methane consumption during the initial 12 weeks. The greatest level of methane removal of 27.2±0.66 g methane m−3 empty bed h−1 was attained for the non-inoculated system, which was equivalent to removing 19.7±2.9% methane from an inlet concentration of 1% v/v at an inlet gas flow rate of 1.6 L min−1 (2.4 min empty bed residence time). These results show that low-cost coal packing holds promising potential as a suitable growth surface and contains methanotrophic microorganisms for the catalytic oxidative removal of methane. PMID:24743729

Control device of air-fuel ratio of alcohol-gasoline mixed fuel

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Kazuo

1987-08-19

Concerning alcohol-gasoline mixed fuel, even the same amount of the fuel shows different air-fuel ratio depending upon alcohol concentration in the fuel, accordingly it is required to know the alcohol concentration when it is intended to make the air-fuel ratio to be the same as the predetermined ratio. Although a sensor which can detect in quick response and exactly the alcohol concentration has not been developed, the alcohol concentration in gasoline can be detected by detecting the concentration of the water in exhaust gas and many hygrometers which can detect the concentration of the water with high precision are available. With regard to an internal combustion engine equipped with a fuel supply device in order to supply alcohol-gasoline mixed fuel into an engine suction passage, this invention offers an air-fuel ratio control device to control the amount of the fuel to be supplied from the fuel supply device by detecting the concentration of alcohol in the gasoline from among the output signals of the main hygrometer and the auxiliary hygrometer. The former hygrometer to detect the concentration of the water in the exhaust gas is set in the engine exhaust gas passage and the latter is installed to detect the concentration of the water in the air. (4 figs)

Extinction of corrugated hydrogen/air flames

International Nuclear Information System (INIS)

Mizomoto, M.; Asaka, Y.; Ikai, S.; Law, C.K.

1982-01-01

Recent studies on flammability limits reveal the importance of flow nonuniformity, flame curvature, and molecular and thermal diffusivities in determining the extinguishability and the associated limits of premixed fuel/air flames. In particular, it is found that conditions which favor extinction of a lean flame may cause intensification of a rich flame. In the present study the authors have experimentally determined the extinction characteristics and limits of highly curved hydrogen/air flames as represented by the opening of bunsen flame tips. Results show that the tip opens at a constant fuel equivalence ratio of phi = 1.15, regardless of the velocity and uniformity of the upstream flow. This critical mixture concentration, while being rich, is still on the lean side of that corresponding to the maximum burning velocity (phi = 1.8), implying that for highly diffusive systems, the relevant reference concentration is that for maximum burning velocity instead of stoichiometry

Climate impacts of air quality policy: switching to a natural gas-fueled public transportation system in New Delhi.

Science.gov (United States)

Reynolds, Conor C O; Kandlikar, Milind

2008-08-15

Between 2001 and 2003, public transport vehicles in New Delhi were required to switch their fuel to natural gas in an attemptto reduce their air pollution impacts. This study examines the climatic impacts of New Delhi's fuel switching policy, and outlines implications for such efforts in rapidly industrializing countries. Natural gas is mostly composed of methane, an important greenhouse gas. Emitted aerosols (black carbon, particulate organic carbon, and sulfate) also cause radiative forcing. We find that methane and black carbon emissions are critical contributors to the change in carbon dioxide equivalent [CO2(e)] emissions. In New Delhi, the switch to natural gas results in a 30% increase in CO2(e) when the impact of aerosols is not considered. However, when aerosol emissions are taken into account in our model, the net effect of the switch is estimated to be a 10% reduction in CO2(e), and there may be as much as a 30% reduction in CO2(e). There is significant potential for emissions reductions through the United Nations Framework Convention on Climate Change (UNFCCC) Clean Development Mechanism for such fuel switching projects.

An examination of the flame spread limits in a dual fuel engine

Energy Technology Data Exchange (ETDEWEB)

Badr, O.; Karim, G.A.; Liu, B. [Calgary Univ., Dept. of Mechanical Engineering, Calgary, AB (Canada)

1999-10-01

The performance of a gas-fuelled diesel engine (dual fuel) is examined at light load and an effective threshold limit to the combustion of the gaseous fuel through bulk flame spread is identified. The relationship of such a limit to some of the key operating parameters is then discussed. A comparison between the measured values of the limit with those corresponding to the lower flammability limits of the gaseous fuel when evaluated under the prevailing cylinder conditions during pilot diesel fuel ignition showed similar trends. It is suggested that such a similarity may form a basis for estimating the lean operation limits for duel a fuel combustion in engines. A simple approach for estimating the limiting equivalence ratio for the apparent bulk flame spread limit is described for a methane-fuelled dual fuel engine. (Author)

Ion measurements in premixed methane-oxygen flames

KAUST Repository

Alquaity, Awad; Hourani, Nadim; Chahine, May; Selim, Hatem; Sarathy, Mani; Farooq, Aamir

2014-01-01

Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry

Continuous measurements of ammonia, nitrous oxide and methane from air scrubbers at pig housing facilities.

Science.gov (United States)

Van der Heyden, C; Brusselman, E; Volcke, E I P; Demeyer, P

2016-10-01

Ammonia, largely emitted by agriculture, involves a great risk for eutrophication and acidification leading to biodiversity loss. Air scrubbers are widely applied to reduce ammonia emission from pig and poultry housing facilities, but it is not always clear whether their performance meets the requirements. Besides, there is a growing international concern for the livestock related greenhouse gases methane and nitrous oxide but hardly any data concerning their fate in air scrubbers are available. This contribution presents the results from measurement campaigns conducted at a chemical, a biological and a two-stage biological air scrubber installed at pig housing facilities in Flanders. Ammonia, nitrous oxide and methane at the inlet and outlet of the air scrubbers were monitored on-line during one week using a photoacoustic gas monitor, which allowed to investigate diurnal fluctuations in the removal performance of air scrubbers. Additionally, the homogeneity of the air scrubbers, normally checked by gas detection tubes, was investigated in more detail using the continuous data. The biological air scrubber with extra nitrification tank performed well in terms of ammonia removal (86 ± 6%), while the two-stage air scrubber suffered from nitrifying bacteria inhibition. In the chemical air scrubber the pH was not kept constant, lowering the ammonia removal efficiency. A lower ammonia removal efficiency was found during the day, when the ventilation rate was the highest. Nitrous oxide was produced inside the biological and two-stage scrubber, resulting in an increased outlet concentration of more than 200%. Methane could not be removed in the different air scrubbers because of its low water solubility. Copyright © 2016 Elsevier Ltd. All rights reserved.

Tuneable diode laser gas analyser for methane measurements on a large scale solid oxide fuel cell

Science.gov (United States)

Lengden, Michael; Cunningham, Robert; Johnstone, Walter

2011-10-01

A new in-line, real time gas analyser is described that uses tuneable diode laser spectroscopy (TDLS) for the measurement of methane in solid oxide fuel cells. The sensor has been tested on an operating solid oxide fuel cell (SOFC) in order to prove the fast response and accuracy of the technology as compared to a gas chromatograph. The advantages of using a TDLS system for process control in a large-scale, distributed power SOFC unit are described. In future work, the addition of new laser sources and wavelength modulation will allow the simultaneous measurement of methane, water vapour, carbon-dioxide and carbon-monoxide concentrations.

Air/fuel supply system for use in a gas turbine engine

Science.gov (United States)

Fox, Timothy A; Schilp, Reinhard; Gambacorta, Domenico

2014-06-17

A fuel injector for use in a gas turbine engine combustor assembly. The fuel injector includes a main body and a fuel supply structure. The main body has an inlet end and an outlet end and defines a longitudinal axis extending between the outlet and inlet ends. The main body comprises a plurality of air/fuel passages extending therethrough, each air/fuel passage including an inlet that receives air from a source of air and an outlet. The fuel supply structure communicates with and supplies fuel to the air/fuel passages for providing an air/fuel mixture within each air/fuel passage. The air/fuel mixtures exit the main body through respective air/fuel passage outlets.

NOx storage and reduction over a lean-burn automotive catalyst

NARCIS (Netherlands)

Scholz, C.M.L.

2007-01-01

Nowadays, there is an increased interest in lean-burn technologies, i.e. diesel and lean-burn gasoline engines, mainly due to their higher fuel efficiency compared to conventional gasoline engines. Lean-burn engines work under excess oxygen and consequently produce oxygen-rich exhaust. This

Performance of a methane-fueled single-cell SOFC stack at various levels of fuel utilization

International Nuclear Information System (INIS)

Ahmed, K.; Bolden, R.; Ramprakash and Foger, K.

1998-01-01

Fuel-gas mixtures representing 10 to 85% utilization of a methane-steam mixture at S/C=2 were fed to a single cell stack with a Ni-based anode at 875 deg C. Cell voltage and power output were recorded at current densities of 50 to 350 mA/cm 2 . The accompanying anode off-gas composition at some of these conditions were measured using on-line gas chromatograph and compared with the compositions predicted by a thermodynamic model based on the assumption of no carbon formation. Electrical losses were measured at a chosen current density at various levels of fuel utilization by the galvanostatic current-interruption technique. Cell voltage stability was monitored for up to 1000 h at two levels of fuel utilization. The stack performance was simulated using a mathematical model of the stack; the simulations were compared with the stack test data. Copyright (1998) Australasian Ceramic Society

Experimental Combustion Dynamics Behavior of a Multi-Element Lean Direct Injection (LDI) Gas Turbine Combustor

Science.gov (United States)

Acosta, Waldo A.; Chang, Clarence T.

2016-01-01

An experimental investigation of the combustion dynamic characteristics of a research multi-element lean direct injection (LDI) combustor under simulated gas turbine conditions was conducted. The objective was to gain a better understanding of the physical phenomena inside a pressurized flametube combustion chamber under acoustically isolated conditions. A nine-point swirl venturi lean direct injection (SV-LDI) geometry was evaluated at inlet pressures up to 2,413 kPa and non-vitiated air temperatures up to 867 K. The equivalence ratio was varied to obtain adiabatic flame temperatures between 1388 K and 1905 K. Dynamic pressure measurements were taken upstream of the SV-LDI, in the combustion zone and downstream of the exit nozzle. The measurements showed that combustion dynamics were fairly small when the fuel was distributed uniformly and mostly due to fluid dynamics effects. Dynamic pressure fluctuations larger than 40 kPa at low frequencies were measured at 653 K inlet temperature and 1117 kPa inlet pressure when fuel was shifted and the pilot fuel injector equivalence ratio was increased to 0.72.

Relation of Hydrogen and Methane to Carbon Monoxide in Exhaust Gases from Internal-Combustion Engines

Science.gov (United States)

Gerrish, Harold C; Tessmann, Arthur M

1935-01-01

The relation of hydrogen and methane to carbon monoxide in the exhaust gases from internal-combustion engines operating on standard-grade aviation gasoline, fighting-grade aviation gasoline, hydrogenated safety fuel, laboratory diesel fuel, and auto diesel fuel was determined by analysis of the exhaust gases. Two liquid-cooled single-cylinder spark-ignition, one 9-cylinder radial air-cooled spark-ignition, and two liquid-cooled single-cylinder compression-ignition engines were used.

Evaluation of an integrated methane autothermal reforming and high-temperature proton exchange membrane fuel cell system

International Nuclear Information System (INIS)

Authayanun, Suthida; Saebea, Dang; Patcharavorachot, Yaneeporn; Arpornwichanop, Amornchai

2015-01-01

The aim of this study was to investigate the performance and efficiency of an integrated autothermal reforming and HT-PEMFC (high-temperature proton exchange membrane fuel cell) system fueled by methane. Effect of the inclusion of a CO (carbon monoxide) removal process on the integrated HT-PEMFC system was considered. An increase in the S/C (steam-to-carbon) ratio and the reformer temperature can enhance the hydrogen fraction while the CO formation reduces with increasing S/C ratio. The fuel processor efficiency of the methane autothermal reformer with a WGS (water gas shift reactor) reactor, as the CO removal process, is higher than that without a WGS reactor. A higher fuel processor efficiency can be obtained when the feed of the autothermal reformer is preheated to the reformer temperature. Regarding the cell performance, the reformate gas from the methane reformer operated at T in  = T R and with a high S/C ratio is suitable for the HT-PEMFC system without a WGS reactor. When considering the HT-PEMFC system with a WGS reactor, the CO poisoning has less significant impact on the cell performance and the system can be operated over a broader range to minimize the required total active area. A WGS reactor is necessary for the methane autothermal reforming and HT-PEMFC integrated system with regard to the system efficiency. - Highlights: • An integrated autothermal reforming and HT-PEMFC system was studied. • The HT-PEMFC system with and without a CO removal process was considered. • Parametric analysis was performed to obtain a high system efficiency. • The HT-PEMFC system with the WGS reactor can be run over a broader range. • The efficiencies of the HT-PEMFC systems without and with a WGS reactor were reported

Aerated biofilters with multiple-level air injection configurations to enhance biological treatment of methane emissions.

Science.gov (United States)

Farrokhzadeh, Hasti; Hettiaratchi, J Patrick A; Jayasinghe, Poornima; Kumar, Sunil

2017-09-01

Aiming to improve conventional methane biofilter performance, a multiple-level aeration biofilter design is proposed. Laboratory flow-through column experiments were conducted to evaluate three actively-aerated methane biofilter configurations. Columns were aerated at one, two, and three levels of the bed depth, with air introduced at flow rates calculated from methane oxidation reaction stoichiometry. Inlet methane loading rates were increased in five stages between 6 and 18mL/min. The effects of methane feeding rate, levels of aeration, and residence time on methane oxidation rates were determined. Samples collected after completion of flow-through experiments were used to determine methane oxidation kinetic parameters, V max , K m , and methanotrophic community distribution across biofilter columns. Results obtained from mixed variances analysis and response surfaces, as well as methanotrophic activity data, suggested that, biofilter column with two aeration levels has the most even performance over time, maintaining 85.1% average oxidation efficiency over 95days of experiments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Large-eddy simulation of a turbulent piloted methane/air diffusion flame (Sandia flame D)

International Nuclear Information System (INIS)

Pitsch, H.; Steiner, H.

2000-01-01

The Lagrangian Flamelet Model is formulated as a combustion model for large-eddy simulations of turbulent jet diffusion flames. The model is applied in a large-eddy simulation of a piloted partially premixed methane/air diffusion flame (Sandia flame D). The results of the simulation are compared to experimental data of the mean and RMS of the axial velocity and the mixture fraction and the unconditional and conditional averages of temperature and various species mass fractions, including CO and NO. All quantities are in good agreement with the experiments. The results indicate in accordance with experimental findings that regions of high strain appear in layer like structures, which are directed inwards and tend to align with the reaction zone, where the turbulence is fully developed. The analysis of the conditional temperature and mass fractions reveals a strong influence of the partial premixing of the fuel. (c) 2000 American Institute of Physics

Kinetics of NO formation and decay in nanosecond pulse discharges in Air, H2-Air, and C2H4-Air mixtures

International Nuclear Information System (INIS)

Burnette, David; Shkurenkov, Ivan; Adamovich, Igor V; Lempert, Walter R

2016-01-01

Time-resolved, absolute NO and N atom number densities are measured by NO Laser Induced Fluorescence (LIF) and N Two-Photon Absorption LIF in a diffuse plasma filament, nanosecond pulse discharge in dry air, hydrogen-air, and ethylene-air mixtures at 40 Torr, over a wide range of equivalence ratios. The results are compared with kinetic modeling calculations incorporating pulsed discharge dynamics, kinetics of vibrationally and electronically excited states of nitrogen, plasma chemical reactions, and radial transport. The results show that in air afterglow, NO decay occurs primarily by the reaction with N atoms, NO  +  N  →  N 2   +  O. In the presence of hydrogen, this reaction is mitigated by reaction of N atoms with OH, N  +  OH  →  NO  +  H, resulting in significant reduction of N atom number density in the afterglow, additional NO production, and considerably higher NO number densities. In fuel-lean ethylene-air mixtures, a similar trend (i.e. N atom concentration reduction and NO number density increase) is observed, although [NO] increase on ms time scale is not as pronounced as in H 2 -air mixtures. In near-stoichiometric and fuel-lean ethylene-air mixtures, when N atom number density was below detection limit, NO concentration was measured to be lower than in air plasma. These results suggest that NO kinetics in hydrocarbon-air plasmas is more complex compared to air and hydrogen-air plasmas, additional NO reaction pathways may well be possible, and their analysis requires further kinetic modeling calculations. (paper)

Methane: Fuel or Exhaust at the Emergence of Life?

Science.gov (United States)

Russell, Michael J; Nitschke, Wolfgang

2017-10-01

As many of the methanogens first encountered at hydrothermal vents were thermophilic to hyperthermophilic and comprised one of the lower roots of the evolutionary tree, it has been assumed that methanogenesis was one of the earliest, if not the earliest, pathway to life. It being well known that hydrothermal springs associated with serpentinization also bore abiotic methane, it had been further assumed that emergent biochemistry merely adopted and quickened this supposed serpentinization reaction. Yet, recent hydrothermal experiments simulating serpentinization have failed to generate methane so far, thus casting doubt on this assumption. The idea that the inverse view is worthy of debate, that is, that methanotrophy was the earlier, is stymied by the "fact" that methanotrophy itself has been termed "reverse methanogenesis," so allotting the methanogens the founding pedigree. Thus, attempting to suggest instead that methanogenesis might be termed reverse methanotrophy would require "unlearning"-a challenge to the subconscious! Here we re-examine the "impossibility" of methanotrophy predating methanogenesis as in what we have termed the "denitrifying methanotrophic acetogenic pathway." Advantages offered by such thinking are that methane would not only be a fuel but also a ready source of reduced carbon to combine with formate or carbon monoxide-available in hydrothermal fluids-to generate acetate, a target molecule of the first autotrophs. And the nitrate/nitrite required for the putative oxidation of methane with activated NO would also be a ready source of fixed nitrogen for amination reactions. Theoretical conditions for such a putative pathway would be met in a hydrothermal green rust-bearing exhalative pile and associated chimneys subject to proton and electron counter gradients. This hypothesis could be put to test in a high-pressure hydrothermal reaction chamber in which a cool carbonate/nitrate/nitrite-bearing early acidulous ocean simulant is juxtaposed

Effect of Lewis number on ball-like lean limit flames

KAUST Repository

Zhou, Zhen; Shoshin, Yuriy; Hernandez Perez, Francisco; van Oijen, Jeroen A.; de Goey, Laurentius P.H.

2017-01-01

–air and H2–air flames, ball-like lean limit flames are observed. Flame temperature fields are measured using Rayleigh scattering. The experimentally observed lean limit flames are predicted qualitatively by numerical simulation with the mixture

PROBLEMY I PERSPEKTIVY ISPOL'ZOVANIYA SHAKHTNOGO METANA [PROBLEMS AND PROSPECTS OF COAL MINE METHANE

Directory of Open Access Journals (Sweden)

Mogileva Ye.M.

2017-09-01

Full Text Available The use of coal mine methane ensures the implementation of the principle of integrated development of the deposit. The urgency of the problem of coal mine methane is determined by the fact that the Presidential Decree of September 30, 2013 № 752 "On the reduction of greenhouse gas emissions" is to bring to the 2020 decrease in emissions. The article substantiates the necessity of cardinal growth of the volumes of utilization of mine methane, as well as the strengthening of the role of degassing methods. The main reasons for the low level of utilization in the Russian Federation are noted. The main directions of using coal mine methane at present are considered, among which are: heat generation (fuel in boilers and other heat generators; generation of electricity (fuel for diesel engines of alternators; fuel for motor vehicles; raw materials for the chemical industry. The analysis of the main methods of utilization of methane-air mixtures is presented. Three perspective technologies for recycling methane from the ventilation streams of coal mines to the atmosphere are singled out: a thermal reactor with reversible flows "VOCSIDIZER", developed by MEGTEC Systems; a thermal reactor with reversible flows "VAMOX", developed by the company "Biothermica Technologies Inc."; a catalytic reversible reactor developed by Canadian Mineral and Energy Technologies. International practice shows that the implementation of projects for the utilization of coal mine methane, as a rule, requires the economic stimulation of such works. The article gives the main incentives and identifies the main directions for solving the problem of coal mine methane utilization.

Design and preliminary results of a fuel flexible industrial gas turbine combustor

Science.gov (United States)

Novick, A. S.; Troth, D. L.; Yacobucci, H. G.

1981-01-01

The design characteristics are presented of a fuel tolerant variable geometry staged air combustor using regenerative/convective cooling. The rich/quench/lean variable geometry combustor is designed to achieve low NO(x) emission from fuels containing fuel bound nitrogen. The physical size of the combustor was calculated for a can-annular combustion system with associated operating conditions for the Allison 570-K engine. Preliminary test results indicate that the concept has the potential to meet emission requirements at maximum continuous power operation. However, airflow sealing and improved fuel/air mixing are necessary to meet Department of Energy program goals.

Alcohol Fuel in Passenger Car

Directory of Open Access Journals (Sweden)

Adam Polcar

2016-01-01

Full Text Available The present article studies the effects of combustion of high-percentage mixture of bioethanol and gasoline on the output parameters of a passenger car engine. The car engine has not been structurally modified for the combustion of fuels with higher ethanol content. The mixture used consisted of E85 summer blend and Natural 95 gasoline in a ratio of 50:50. The parameters monitored during the experiment included the air-fuel ratio in exhaust gasses, the power output and torque of the engine and also the specific energy consumption and efficiency of the engine. As is apparent from the results, E85+N95 (50:50 mixture combustion results in lean-burn (λ > 1 due to the presence of oxygen in bioethanol. The lean-burn led to a slight decrease in torque and power output of the engine. However, due to the positive physicochemical properties of bioethanol, the decrease has not been as significant as would normally be expected from the measured air-fuel ratio. These findings are further confirmed by the calculated energy required to produce 1 kWh of energy, and by the higher efficiency of the engine during the combustion of a 50% bioethanol mixture.

Study of fuel spray characteristics for premixed lean diesel combustion; Kihaku yokongo diesel kikan ni okeru nenryo funmu keisei ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

Sasaki, S.; Miyamoto, T.; Harada, A.; Akagawa, H.; Tsujimura, K. [New ACE Institute Co. Ltd., Tokyo (Japan)

1998-05-01

A study is being made on premixed lean diesel combustion (PREDIC) by means of early fuel injection in diesel engines. The PREDIC makes it possible to largely reduce NOx emission, but has such problems as ignition control and increase in THC and CO generation. In order to clarify the relationship between fuel spray characteristics in the PREDIC and properties of gas mixture and exhausts, the present study has investigated spread and internal structure of the spray by means of spray observation experiment using a pintle swirl nozzle. Based on the result therefrom, simulations were used to investigate effects of spatial dispersion characteristics of the spray on properties of the gas mixture and exhausts before ignition. The pintle swirl nozzle forms conical spray having an air layer inside the spray, where penetration is suppressed even under low atmospheric pressure. By forming hollow spray or solid spray in the conical spray, a possibility was indicated that equivalent ratio distribution of the gas mixture can be controlled and NO emission may be reduced. 8 refs., 12 figs., 1 tab.

Effect of air addition to methane on performance stability and coking over NiO-YSZ anodes of SOFC

NARCIS (Netherlands)

Aslannejad, Hamed; Barelli, L.; Babaie, A.; Bozorgmehri, S.

2016-01-01

The use of natural gas as fuel for solid oxide fuel cell is one of main potentials of this technology to be exploited as an efficient and profitable future power generation source. However, using direct methane (main component of natural gas) in conventional nickel-based fuel cells leads to carbon

Air conditioning with methane: Efficiency and economics optimization parameters

International Nuclear Information System (INIS)

Mastrullo, R.; Sasso, M.; Sibilio, S.; Vanoli, R.

1992-01-01

This paper presents an efficiency and economics evaluation method for methane fired cooling systems. Focus is on direct flame two staged absorption systems and alternative engine driven compressor sets. Comparisons are made with conventional vapour compression plants powered by electricity supplied by the national grid. A first and second law based thermodynamics analysis is made in which fuel use coefficients and exergy yields are determined. The economics analysis establishes annual energy savings, unit cooling energy production costs, payback periods and economics/efficiency optimization curves useful for preliminary feasibility studies

Pressurized solid oxide fuel cell integral air accumular containment

Science.gov (United States)

Gillett, James E.; Zafred, Paolo R.; Basel, Richard A.

2004-02-10

A fuel cell generator apparatus contains at least one fuel cell subassembly module in a module housing, where the housing is surrounded by a pressure vessel such that there is an air accumulator space, where the apparatus is associated with an air compressor of a turbine/generator/air compressor system, where pressurized air from the compressor passes into the space and occupies the space and then flows to the fuel cells in the subassembly module, where the air accumulation space provides an accumulator to control any unreacted fuel gas that might flow from the module.

INTERACTION OF AIR TRANSPORTATION AND FUEL-SUPPLY COMPANIES

Directory of Open Access Journals (Sweden)

I. P. Zheleznaya

2014-01-01

Full Text Available The article describes the role of aviation fuel in the life of air transport. Fueling industry worldwide solves two main tasks - ensuring the safety and economy of air traffic. In Russia, there is one more task of airlines fuel supply. The article deals with fuel pricing taking into consideration today's realities.

Autoignited laminar lifted flames of methane, ethylene, ethane, and n-butane jets in coflow air with elevated temperature

KAUST Repository

Choi, Byungchul

2010-12-01

The autoignition characteristics of laminar lifted flames of methane, ethylene, ethane, and n-butane fuels have been investigated experimentally in coflow air with elevated temperature over 800. K. The lifted flames were categorized into three regimes depending on the initial temperature and fuel mole fraction: (1) non-autoignited lifted flame, (2) autoignited lifted flame with tribrachial (or triple) edge, and (3) autoignited lifted flame with mild combustion. For the non-autoignited lifted flames at relatively low temperature, the existence of lifted flame depended on the Schmidt number of fuel, such that only the fuels with Sc > 1 exhibited stationary lifted flames. The balance mechanism between the propagation speed of tribrachial flame and local flow velocity stabilized the lifted flames. At relatively high initial temperatures, either autoignited lifted flames having tribrachial edge or autoignited lifted flames with mild combustion existed regardless of the Schmidt number of fuel. The adiabatic ignition delay time played a crucial role for the stabilization of autoignited flames. Especially, heat loss during the ignition process should be accounted for, such that the characteristic convection time, defined by the autoignition height divided by jet velocity was correlated well with the square of the adiabatic ignition delay time for the critical autoignition conditions. The liftoff height was also correlated well with the square of the adiabatic ignition delay time. © 2010 The Combustion Institute.

Chemical structures and theoretical models of lean premixed ...

African Journals Online (AJOL)

To better understand the chemistry involved in the lean-fuel combustion, the chemical structure of lean premixed propene-oxygen-nitrogen flames stabilized on a flat-flame burner at atmospheric pressure was determined experimentally. The species mole fraction profiles were also computed by the Premix code and three ...

Premixed combustion under electric field in a constant volume chamber

KAUST Repository

Cha, Min Suk

2012-12-01

The effects of electric fields on outwardly propagating premixed flames in a constant volume chamber were experimentally investigated. An electric plug, subjected to high electrical voltages, was used to generate electric fields inside the chamber. To minimize directional ionic wind effects, alternating current with frequency of 1 kHz was employed. Lean and rich fuel/air mixtures for both methane and propane were tested to investigate various preferential diffusion conditions. As a result, electrically induced instability showing cracked structure on the flame surface could be observed. This cracked structure enhanced flame propagation speed for the initial period of combustion and led to reduction in flame initiation and overall combustion duration times. However, by analyzing pressure data, it was found that overall burning rates are not much affected from the electric field for the pressurized combustion period. The reduction of overall combustion time is less sensitive to equivalence ratio for methane/air mixtures, whereas the results demonstrate pronounced effects on a lean mixture for propane. The improvement of combustion characteristics in lean mixtures will be beneficial to the design of lean burn engines. Two hypothetical mechanisms to explain the electrically induced instability were proposed: 1) ionic wind initiated hydrodynamic instability and 2) thermodiffusive instability through the modification of transport property such as mass diffusivity. © 2012 IEEE.

Premixed combustion under electric field in a constant volume chamber

KAUST Repository

Cha, Min; Lee, Yonggyu

2012-01-01

The effects of electric fields on outwardly propagating premixed flames in a constant volume chamber were experimentally investigated. An electric plug, subjected to high electrical voltages, was used to generate electric fields inside the chamber. To minimize directional ionic wind effects, alternating current with frequency of 1 kHz was employed. Lean and rich fuel/air mixtures for both methane and propane were tested to investigate various preferential diffusion conditions. As a result, electrically induced instability showing cracked structure on the flame surface could be observed. This cracked structure enhanced flame propagation speed for the initial period of combustion and led to reduction in flame initiation and overall combustion duration times. However, by analyzing pressure data, it was found that overall burning rates are not much affected from the electric field for the pressurized combustion period. The reduction of overall combustion time is less sensitive to equivalence ratio for methane/air mixtures, whereas the results demonstrate pronounced effects on a lean mixture for propane. The improvement of combustion characteristics in lean mixtures will be beneficial to the design of lean burn engines. Two hypothetical mechanisms to explain the electrically induced instability were proposed: 1) ionic wind initiated hydrodynamic instability and 2) thermodiffusive instability through the modification of transport property such as mass diffusivity. © 2012 IEEE.

Chemical looping combustion. Fuel conversion with inherent CO2 capture

Energy Technology Data Exchange (ETDEWEB)

Brandvoll, Oeyvind

2005-07-01

Chemical looping combustion (CLC) is a new concept for fuel energy conversion with CO2 capture. In CLC, fuel combustion is split into separate reduction and oxidation processes, in which a solid carrier is reduced and oxidized, respectively. The carrier is continuously recirculated between the two vessels, and hence direct contact between air and fuel is avoided. As a result, a stoichiometric amount of oxygen is transferred to the fuel by a regenerable solid intermediate, and CLC is thus a variant of oxy-fuel combustion. In principle, pure CO2 can be obtained from the reduction exhaust by condensation of the produced water vapour. The thermodynamic potential and feasibility of CLC has been studied by means of process simulations and experimental studies of oxygen carriers. Process simulations have focused on parameter sensitivity studies of CLC implemented in 3 power cycles; CLC-Combined Cycle, CLC-Humid Air Turbine and CLC-Integrated Steam Generation. Simulations indicate that overall fuel conversion ratio, oxidation temperature and operating pressure are among the most important process parameters in CLC. A promising thermodynamic potential of CLC has been found, with efficiencies comparable to, - or better than existing technologies for CO2 capture. The proposed oxygen carrier nickel oxide on nickel spinel (NiONiAl) has been studied in reduction with hydrogen, methane and methane/steam as well as oxidation with dry air. It has been found that at atmospheric pressure and temperatures above 600 deg C, solid reduction with dry methane occurs with overall fuel conversion of 92%. Steam methane reforming is observed along with methane cracking as side reactions, yielding an overall selectivity of 90% with regard to solid reduction. If steam is added to the reactant fuel, coking can be avoided. A methodology for long-term investigation of solid chemical activity in a batch reactor is proposed. The method is based on time variables for oxidation. The results for Ni

Development of a novel reactor concept for the partial oxidation of methane to syngas

NARCIS (Netherlands)

Smit, J.; van Sint Annaland, M.; Kuipers, J.A.M.

2004-01-01

The gas-to-liquid process, consisting of the partial oxidation of methane (POM) followed by the Fischer-Tropsch reaction, is a promising alternative to conventional oil processing for the production of liquid fuels. The cost of a conventional POM process is mainly determined by cryogenic air

A numerical study of the influence of ammonia addition on the auto-ignition limits of methane/air mixtures

International Nuclear Information System (INIS)

Van den Schoor, F.; Norman, F.; Vandebroek, L.; Verplaetsen, F.; Berghmans, J.

2009-01-01

In this study the auto-ignition limit of ammonia/methane/air mixtures is calculated based upon a perfectly stirred reactor model with convective heat transfer. The results of four different reaction mechanisms are compared with existing experimental data at an initial temperature of 723 K with ammonia concentrations of 0-20 mol.% and methane concentrations of 2.5-10 mol.%. It is found that the calculation of the auto-ignition limit pressure at constant temperature leads to larger relative deviations between calculated and experimental results than the calculation of the auto-ignition temperature at constant pressure. In addition to the calculations, a reaction path analysis is performed to explain the observed lowering of the auto-ignition limit of methane/air mixtures by ammonia addition. It is found that this decrease is caused by the formation of NO and NO 2 , which enhance the oxidation of methane at low temperatures.

Dual-fuel production from restaurant grease trap waste: bio-fuel oil extraction and anaerobic methane production from the post-extracted residue.

Science.gov (United States)

Kobayashi, Takuro; Kuramochi, Hidetoshi; Maeda, Kouji; Tsuji, Tomoya; Xu, Kaiqin

2014-10-01

An effective way for restaurant grease trap waste (GTW) treatment to generate fuel oil and methane by the combination of physiological and biological processes was investigated. The heat-driven extraction could provide a high purity oil equivalent to an A-grade fuel oil of Japanese industrial standard with 81-93 wt% of extraction efficiency. A post-extracted residue was treated as an anaerobic digestion feedstock, and however, an inhibitory effect of long chain fatty acid (LCFA) was still a barrier for high-rate digestion. From the semi-continuous experiment fed with the residual sludge as a single substrate, it can be concluded that the continuous addition of calcium into the reactor contributed to reducing LCFA inhibition, resulting in the long-term stable operation over one year. Furthermore, the anaerobic reactor performed well with 70-80% of COD reduction and methane productivity under an organic loading rate up to 5.3g-COD/L/d. Copyright © 2014 Elsevier Ltd. All rights reserved.

Impact of fuel composition on the recirculation zone structure and its role in lean premixed flame anchoring

KAUST Repository

Hong, Seunghyuck

2015-01-01

© 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved. We investigate the dependence of the recirculation zone (RZ) size and structure on the fuel composition using high-speed particle image velocimetry (PIV) and chemiluminescence measurements for C3H8/H2/air lean premixed flames stabilized in a backward-facing step combustor. Results show an intricate coupling between the flame anchoring and the RZ structure and length. For a fixed fuel composition, at relatively low equivalence ratios, the time-averaged RZ is comprised of two counter rotating eddies: a primary eddy (PE) between the shear layer and the bottom wall; and a secondary eddy (SE) between the vertical step wall and the PE. The flame stabilizes downstream of the saddle point of the dividing streamline between the two eddies. As equivalence ratio is raised, the flame moves upstream, pushing the saddle point with it and reducing the size of the SE. Higher temperature of the products reduces the velocity gradient in the shear layer and thus the reattachment length. As equivalence ratio approaches a critical value, the saddle point reaches the step and the SE collapses while the flame starts to exhibit periodic flapping motions, suggesting a correlation between the RZ structure and flame anchoring. The overall trend in the flow field is the same as we add hydrogen to the fuel at a fixed equivalence ratio, demonstrating the impact of fuel composition on the flow field. We show that the reattachment lengths (LR), which are shown to encapsulate the mean RZ structure, measured over a range of fuel composition and equivalence ratio collapse if plotted against the strained consumption speed (Sc). Results indicate that for the flame to remain anchored, the RZ structure should satisfy lR,isothermal/L R,reacting · S c/U ∞ ∼ 0.1. If this criterion cannot be met, the flame blows off, flashes back or becomes thermoacoustically unstable, suggesting a Damköhler-like criterion for

Low Emissions Burner Technology for Metal Processing Industry using Byproducts and Biomass Derived Liquid Fuels

Energy Technology Data Exchange (ETDEWEB)

Agrawal, Ajay; Taylor, Robert

2013-09-30

path forward to utilize both fossil and alternative liquid fuels in the same combustion system. In particular, experiments show that straight VO can be cleanly combusted without the need for chemical processing or preheating steps, which can result in significant economic and environmental benefits. Next, low-emission combustion of glycerol/methane was achieved by utilizing FB injector to yield fine droplets of highly viscous glycerol. Heat released from methane combustion further improves glycerol pre-vaporization and thus its clean combustion. Methane addition results in an intensified reaction zone with locally high temperatures near the injector exit. Reduction in methane flow rate elongates the reaction zone, which leads to higher CO emissions and lower NOx emissions. Similarly, higher air to liquid (ALR) mass ratio improves atomization and fuel pre-vaporization and shifts the flame closer to the injector exit. In spite of these internal variations, all fuel mixes of glycerol with methane produced similar CO and NOx emissions at the combustor exit. Results show that FB concept provides low emissions with the flexibility to utilize gaseous and highly viscous liquid fuels, straight VO and glycerol, without preheating or preprocessing the fuels. Following these initial experiments in quartz combustor, we demonstrated that glycerol combustion can be stably sustained in a metal combustor. Phase Doppler Particle Analyzer (PDPA) measurements in glycerol/methane flames resulted in flow-weighted Sauter Mean Diameter (SMD) of 35 to 40 μm, depending upon the methane percentage. This study verified that lab-scale dual-fuel burner using FB injector can successfully atomize and combust glycerol and presumably other highly viscous liquid fuels at relatively low HRR (<10 kW). For industrial applications, a scaled-up glycerol burner design thus seemed feasible.

Air-adapted Methanosarcina acetivorans shows high methane production and develops resistance against oxygen stress.

Directory of Open Access Journals (Sweden)

Ricardo Jasso-Chávez

Full Text Available Methanosarcina acetivorans, considered a strict anaerobic archaeon, was cultured in the presence of 0.4-1% O2 (atmospheric for at least 6 months to generate air-adapted cells; further, the biochemical mechanisms developed to deal with O2 were characterized. Methane production and protein content, as indicators of cell growth, did not change in air-adapted cells respect to cells cultured under anoxia (control cells. In contrast, growth and methane production significantly decreased in control cells exposed for the first time to O2. Production of reactive oxygen species was 50 times lower in air-adapted cells versus control cells, suggesting enhanced anti-oxidant mechanisms that attenuated the O2 toxicity. In this regard, (i the transcripts and activities of superoxide dismutase, catalase and peroxidase significantly increased; and (ii the thiol-molecules (cysteine + coenzyme M-SH + sulfide and polyphosphate contents were respectively 2 and 5 times higher in air-adapted cells versus anaerobic-control cells. Long-term cultures (18 days of air-adapted cells exposed to 2% O2 exhibited the ability to form biofilms. These data indicate that M. acetivorans develops multiple mechanisms to contend with O2 and the associated oxidative stress, as also suggested by genome analyses for some methanogens.

The Characteristics of Methane Combustion Suppression by Water Mist and Its Engineering Applications

Directory of Open Access Journals (Sweden)

Rongkun Pan

2017-10-01

Full Text Available To safely mine coal, engineers must prevent gas combustion and explosions, as well as seek feasible and reasonable techniques to control for these types of incidents. This paper analyzes the causes and characteristics of methane combustion and explosions. Water mist is proposed to prevent and control methane combustion in an underground confined space. We constructed an experiment platform to investigate the suppression of methane combustion using water mist for different conditions. The experimental results showed that water mist is highly effective for methane flame inhibition. The flame was extinguished with water mist endothermic cooling. However, the annular regions of water vapor around the fire played a vital role in flame extinction. Water from the evaporating mist replaces the oxygen available to the fuel. Additionally, the time required for fuel ignition is prolonged. For these reasons, the water particle action to flame surface is reinforced and the fuel’s reaction with air is delayed. As a result, flame stretching and disturbances occur, which serve to extinguish the flame. Engineering application tests were carried out in the goaf, drill hole and upper-corner to investigate the prevention and control of methane gas combustion, with the results showing a good application effect.

Lean maturity, lean sustainability

DEFF Research Database (Denmark)

Jørgensen, Frances; Matthiesen, Rikke; Nielsen, Jacob

2007-01-01

. A framework for describing levels of lean capability is presented, based on a brief review of the literature and experiences from 12 Danish companies currently implementing lean. Although still in its emerging phase, the framework contributes to both theory and practice by describing developmental stages......Although lean is rapidly growing in popularity, its implementation is far from problem free and companies may experience difficulties sustaining long term success. In this paper, it is suggested that sustainable lean requires attention to both performance improvement and capability development...... that support lean capability development and consequently, lean sustainability....

Model reduction of a lean NOx trap catalyst model

NARCIS (Netherlands)

Nauta, K.M.

2008-01-01

The desire to increase fuel efficiency and reduce carbon dioxide emissions of vehicles has led to an increased use of vehicles equipped with lean-burn engines, such as diesel and lean-burn gasoline engines. This type of engine uses excess oxygen when compared to the amount required to

Gas chromatographic determination of Di-n-butyl phosphate in radioactive lean organic solvent of FBTR carbide fuel reprocessing

International Nuclear Information System (INIS)

Velavendan, P.; Ganesh, S.; Pandey, N.K.; Kamachi Mudali, U.; Natarajan, R.

2011-01-01

In the present work Di-n- butyl phosphate (DBP) a degraded product of Tri-n-butyl phosphate (TBP) formed by acid hydrolysis and radiolysis in the PUREX process was analyzed. Lean organic streams of different fuel burn-up FBTR carbide fuel reprocessing solution was determined by standard Gas Chromatographic technique. The method involves the conversion of non-volatile Di-n-butyl phosphate into volatile and stable derivatives by the action of diazomethane and then determined by Gas Chromatograph (GC). A calibration graph was made for DBP concentration range of 200-2000 ppm with correlation coefficient of 0.99587 and RSD 1.2 %. (author)

Experimental and numerical study of cap-like lean limit flames in H 2 -CH 4 -air mixtures

KAUST Repository

Zhou, Zhen

2017-11-15

Lean limit flames of H2-CH4-air mixtures stabilized inside a tube with an inner diameter of 30 mm in a downward flow are studied experimentally and numerically. A transition from bubble-like flames, with a long decaying skirt, to cap-like flames with a sharp visible flame edge at the bottom is observed as the lean flammability limit is approached. This transition is accompanied by formation of a secondary weak flame front inside the cap-like flame. The CH* chemiluminescence distribution of the studied flames is recorded and the velocity field of the lean limit flames is measured using Particle Image Velocimetry (PIV). The flame temperature field is measured utilizing the Rayleigh scattering method. Numerical prediction with a mixture-averaged transport model and skeletal mechanism for CH4 qualitatively reproduces the above experimentally observed phenomena. The presence of negative flame displacement speed for the entire leading edge of the cap-like flames is numerically predicted and experimentally demonstrated. The secondary weak flame front is located in a region with reverse upward flow of the recirculation zone, which is found to support the propagation of the leading edge with a negative flame displacement speed. Furthermore, radiative heat loss has a significant influence on the lean flammability limit of the cap-like flames.

Nitric oxide density measurements in air and air/fuel nanosecond pulse discharges by laser induced fluorescence

International Nuclear Information System (INIS)

Uddi, M; Jiang, N; Adamovich, I V; Lempert, W R

2009-01-01

Laser induced fluorescence is used to measure absolute nitric oxide concentrations in air, methane-air and ethylene-air non-equilibrium plasmas, as a function of time after initiation of a single pulse, 20 kV peak voltage, 25 ns pulse duration discharge. A mixture of NO and nitrogen with known composition (4.18 ppm NO) is used for calibration. Peak NO density in air at 60 Torr, after a single pulse, is ∼8 x 10 12 cm -3 (∼4.14 ppm) occurring at ∼250 μs after the pulse, with decay time of ∼16.5 ms. Peak NO atom mole fraction in a methane-air mixture with equivalence ratio of ψ = 0.5 is found to be approximately equal to that in air, with approximately the same rise and decay rate. In an ethylene-air mixture (also with equivalence ratio of ψ = 0.5), the rise and decay times are comparable to air and methane-air, but the peak NO concentration is reduced by a factor of approximately 2.5. Spontaneous emission measurements show that excited electronic states N 2 (C 3 Π) and NO(A 2 Σ) in air at P = 60 Torr decay within ∼20 ns and ∼1 μs, respectively. Kinetic modelling calculations incorporating air plasma kinetics complemented with the GRI Mech 3.0 hydrocarbon oxidation mechanism are compared with the experimental data using three different NO production mechanisms. It is found that NO concentration rise after the discharge pulse is much faster than predicted by Zel'dovich mechanism reactions, by two orders of magnitude, but much slower compared with reactions of electronically excited nitrogen atoms and molecules, also by two orders of magnitude. It is concluded that processes involving long lifetime (∼100 μs) metastable states, such as N 2 (X 1 Σ,v) and O 2 (b 1 Σ), formed by quenching of the metastable N 2 (A 3 Σ) state by ground electronic state O 2 , may play a dominant role in NO formation. NO decay, in all cases, is found to be dominated by the reverse Zel'dovich reaction, NO + O → N + O 2 , as well as by conversion into NO 2 in a reaction

Nitric oxide density measurements in air and air/fuel nanosecond pulse discharges by laser induced fluorescence

Science.gov (United States)

Uddi, M.; Jiang, N.; Adamovich, I. V.; Lempert, W. R.

2009-04-01

Laser induced fluorescence is used to measure absolute nitric oxide concentrations in air, methane-air and ethylene-air non-equilibrium plasmas, as a function of time after initiation of a single pulse, 20 kV peak voltage, 25 ns pulse duration discharge. A mixture of NO and nitrogen with known composition (4.18 ppm NO) is used for calibration. Peak NO density in air at 60 Torr, after a single pulse, is ~8 × 1012 cm-3 (~4.14 ppm) occurring at ~250 µs after the pulse, with decay time of ~16.5 ms. Peak NO atom mole fraction in a methane-air mixture with equivalence ratio of phiv = 0.5 is found to be approximately equal to that in air, with approximately the same rise and decay rate. In an ethylene-air mixture (also with equivalence ratio of phiv = 0.5), the rise and decay times are comparable to air and methane-air, but the peak NO concentration is reduced by a factor of approximately 2.5. Spontaneous emission measurements show that excited electronic states N2(C 3Π) and NO(A 2Σ) in air at P = 60 Torr decay within ~20 ns and ~1 µs, respectively. Kinetic modelling calculations incorporating air plasma kinetics complemented with the GRI Mech 3.0 hydrocarbon oxidation mechanism are compared with the experimental data using three different NO production mechanisms. It is found that NO concentration rise after the discharge pulse is much faster than predicted by Zel'dovich mechanism reactions, by two orders of magnitude, but much slower compared with reactions of electronically excited nitrogen atoms and molecules, also by two orders of magnitude. It is concluded that processes involving long lifetime (~100 µs) metastable states, such as N2(X 1Σ,v) and O2(b 1Σ), formed by quenching of the metastable N2(A 3Σ) state by ground electronic state O2, may play a dominant role in NO formation. NO decay, in all cases, is found to be dominated by the reverse Zel'dovich reaction, NO + O → N + O2, as well as by conversion into NO2 in a reaction of NO with ozone.

Performance and Exhaust Emissions in a Natural-Gas Fueled Dual-Fuel Engine

Science.gov (United States)

Shioji, Masahiro; Ishiyama, Takuji; Ikegami, Makoto; Mitani, Shinichi; Shibata, Hiroaki

In order to establish the optimum fueling in a natural gas fueled dual fuel engine, experiments were done for some operational parameters on the engine performances and the exhaust emissions. The results show that the pilot fuel quantity should be increased and its injection timing should be advanced to suppress unburned hydrocarbon emission in the middle and low output range, while the quantity should be reduced and the timing retarded to avoid onset of knock at high loads. Unburned hydrocarbon emission and thermal efficiency are improved by avoiding too lean natural gas mixture by restricting intake charge air. However, the improvement is limited because the ignition of pilot fuel deteriorates with excessive throttling. It is concluded that an adequate combination of throttle control and equivalence ratio ensures low hydrocarbon emission and the thermal efficiency comparable to diesel operation.

Spontaneous ignition of methane-air mixtures in a wide range of pressures

NARCIS (Netherlands)

Zhukov, VP; Sechenov, VA; Starikovskii, AY

2003-01-01

The ignition delay in methane-air mixtures (phi = 0.5) within the range of temperatures of 1200-1700 K and pressures of 3-450 atm behind reflected shock waves in a shock tube is measured on the basis of emission of the electron-excited OH radical (transition A(2)Sigma(+) - X(2)Pi) at the wavelength

Singler-chamber SOFCs based on gadolinia doped ceria operated on methane and propane; Pilas de combustible de una sola camara, basadas en electrolitos de ceria dopada con gadolinia y operadas con metano y propano

Energy Technology Data Exchange (ETDEWEB)

Morales, M.; Roa, J. J.; Capdevila, X. G.; Segarra, M.; Pinol, S.

2010-07-01

The main advantages of single-chamber solid oxide fuel cells (SOFCs) respect to dual-chamber SOFCs, are to simplify the device design and to operate in mixtures of hydrocarbon (methane, propane...) and air, with no separation between fuel and oxidant. However, this design requires the use of selective electrodes for the fuel oxidation and the oxidant reduction. In this work, electrolyte-supported SOFCs were fabricated using gadolinia doped ceria (GDC) as the electrolyte, Ni + GDC as the anode and LSC(La{sub 0}.5Sr{sub 0}.5CoO{sub 3}-{delta})-GDC-Ag{sub 2}O as the cathode. The electrical properties of the cell were determined in mixtures of methane + air and propane + air. The influence of temperature, gas composition and total flow rate on the fuel cell performance was investigated. As a result, the power density was strongly increased with increasing temperature, total flow rate and hydrocarbon composition. Under optimized gas compositions and total flow conditions, power densities of 70 and 320 mW/cm{sup 2} operating on propane at a temperature of 600 degree centigrade and methane (795 degree centigrade) were obtained, respectively. (Author)

Swozzle based burner tube premixer including inlet air conditioner for low emissions combustion

Science.gov (United States)

Tuthill, Richard Sterling; Bechtel, II, William Theodore; Benoit, Jeffrey Arthur; Black, Stephen Hugh; Bland, Robert James; DeLeonardo, Guy Wayne; Meyer, Stefan Martin; Taura, Joseph Charles; Battaglioli, John Luigi

2002-01-01

A burner for use in a combustion system of a heavy-duty industrial gas turbine includes a fuel/air premixer having an air inlet, a fuel inlet, and an annular mixing passage. The fuel/air premixer mixes fuel and air into a uniform mixture for injection into a combustor reaction zone. The burner also includes an inlet flow conditioner disposed at the air inlet of the fuel/air premixer for controlling a radial and circumferential distribution of incoming air. The pattern of perforations in the inlet flow conditioner is designed such that a uniform air flow distribution is produced at the swirler inlet annulus in both the radial and circumference directions. The premixer includes a swozzle assembly having a series of preferably air foil shaped turning vanes that impart swirl to the airflow entering via the inlet flow conditioner. Each air foil contains internal fuel flow passages that introduce natural gas fuel into the air stream via fuel metering holes that pass through the walls of the air foil shaped turning vanes. By injecting fuel in this manner, an aerodynamically clean flow field is maintained throughout the premixer. By injecting fuel via two separate passages, the fuel/air mixture strength distribution can be controlled in the radial direction to obtain optimum radial concentration profiles for control of emissions, lean blow outs, and combustion driven dynamic pressure activity as machine and combustor load are varied.

Air/fuel ratio visualization in a diesel spray

Science.gov (United States)

Carabell, Kevin David

1993-01-01

To investigate some features of high pressure diesel spray ignition, we have applied a newly developed planar imaging system to a spray in an engine-fed combustion bomb. The bomb is designed to give flow characteristics similar to those in a direct injection diesel engine yet provide nearly unlimited optical access. A high pressure electronic unit injector system with on-line manually adjustable main and pilot injection features was used. The primary scalar of interest was the local air/fuel ratio, particularly near the spray plumes. To make this measurement quantitative, we have developed a calibration LIF technique. The development of this technique is the key contribution of this dissertation. The air/fuel ratio measurement was made using biacetyl as a seed in the air inlet to the engine. When probed by a tripled Nd:YAG laser the biacetyl fluoresces, with a signal proportional to the local biacetyl concentration. This feature of biacetyl enables the fluorescent signal to be used as as indicator of local fuel vapor concentration. The biacetyl partial pressure was carefully controlled, enabling estimates of the local concentration of air and the approximate local stoichiometry in the fuel spray. The results indicate that the image quality generated with this method is sufficient for generating air/fuel ratio contours. The processes during the ignition delay have a marked effect on ignition and the subsequent burn. These processes, vaporization and pre-flame kinetics, very much depend on the mixing of the air and fuel. This study has shown that poor mixing and over-mixing of the air and fuel will directly affect the type of ignition. An optimal mixing arrangement exists and depends on the swirl ratio in the engine, the number of holes in the fuel injector and the distribution of fuel into a pilot and main injection. If a short delay and a diffusion burn is desired, the best mixing parameters among those surveyed would be a high swirl ratio, a 4-hole nozzle and a

Modeling and parametric simulations of solid oxide fuel cells with methane carbon dioxide reforming

International Nuclear Information System (INIS)

Ni, Meng

2013-01-01

Highlights: ► A 2D model is developed for solid oxide fuel cells (SOFCs). ► CH 4 reforming by CO 2 (MCDR) is included. ► SOFC with MCDR shows comparable performance with methane steam reforming SOFC. ► Increasing CO electrochemical oxidation greatly enhances the SOFC performance. ► Effects of potential and temperature on SOFC performance are also discussed. - Abstract: A two-dimensional model is developed to simulate the performance of solid oxide fuel cells (SOFCs) fed with CO 2 and CH 4 mixture. The electrochemical oxidations of both CO and H 2 are included. Important chemical reactions are considered in the model, including methane carbon dioxide reforming (MCDR), reversible water gas shift reaction (WGSR), and methane steam reforming (MSR). It’s found that at a CH 4 /CO 2 molar ratio of 50/50, MCDR and reversible WGSR significantly influence the cell performance while MSR is negligibly small. The performance of SOFC fed with CO 2 /CH 4 mixture is comparable to SOFC running on CH 4 /H 2 O mixtures. The electric output of SOFC can be enhanced by operating the cell at a low operating potential or at a high temperature. In addition, the development of anode catalyst with high activity towards CO electrochemical oxidation is important for SOFC performance enhancement. The model can serve as a useful tool for optimization of the SOFC system running on CH 4 /CO 2 mixtures

Numerical study of laminar nonpremixed methane flames in coflow jets: Autoignited lifted flames with tribrachial edges and MILD combustion at elevated temperatures

KAUST Repository

M. Al-Noman, Saeed; Choi, Sang Kyu; Chung, Suk-Ho

2016-01-01

Autoignition characteristics of laminar nonpremixed methane jet flames in high-temperature coflow air are studied numerically. Several flame configurations are investigated by varying the initial temperature and fuel mole fraction. At a relatively

A 21st-century shift from fossil-fuel to biogenic methane emissions indicated by ¹³CH₄.

Science.gov (United States)

Schaefer, Hinrich; Mikaloff Fletcher, Sara E; Veidt, Cordelia; Lassey, Keith R; Brailsford, Gordon W; Bromley, Tony M; Dlugokencky, Edward J; Michel, Sylvia E; Miller, John B; Levin, Ingeborg; Lowe, Dave C; Martin, Ross J; Vaughn, Bruce H; White, James W C

2016-04-01

Between 1999 and 2006, a plateau interrupted the otherwise continuous increase of atmospheric methane concentration [CH4] since preindustrial times. Causes could be sink variability or a temporary reduction in industrial or climate-sensitive sources. We reconstructed the global history of [CH4] and its stable carbon isotopes from ice cores, archived air, and a global network of monitoring stations. A box-model analysis suggests that diminishing thermogenic emissions, probably from the fossil-fuel industry, and/or variations in the hydroxyl CH4 sink caused the [CH4] plateau. Thermogenic emissions did not resume to cause the renewed [CH4] rise after 2006, which contradicts emission inventories. Post-2006 source increases are predominantly biogenic, outside the Arctic, and arguably more consistent with agriculture than wetlands. If so, mitigating CH4 emissions must be balanced with the need for food production. Copyright © 2016, American Association for the Advancement of Science.

CryoFuel gas : capture and purification of methane at source

International Nuclear Information System (INIS)

Bailey, R.

2002-01-01

The mandate of CFS Alternative Fuels Incorporated, located in Victoria, British Columbia, which came into operation in 1995, is the installation and operation of gas purification and liquefaction systems using the patented small-scale cryogenic technologies which were designed by an affiliate, CryoFuel Systems Incorporated in Monroe, Washington. Liquefied Natural Gas (LNG) at 97 per cent is produced using gas processing systems from a variety of gases such as unutilized sources like stranded gas wells and coalbed methane. Waste gases like flares, landfills and bio-digesters, as well as pipeline natural gas are also used to produce LNG. The recovery of carbon dioxide at 99.8 per cent purity is possible from landfill and biogas streams. No new emissions are generated by the autonomous, modular, skid-mounted cryofuel plants. Additionally, no external utilities are required. Some of the applications of LNG are the replacement of conventional fuels in the transportation sector and in commercial and industrial applications. The technology's core design and process capabilities were verified in a one-year demonstration project. Firm orders for eight full-scale systems have been received as of April 2002

Methane as a Vehicle Fuel in Europe

International Nuclear Information System (INIS)

Maedge, M.

2014-01-01

NGVA Europe is aware of the importance of the promotion of Natural Gas and biomethane as an important vehicle fuels in Europe. The European Commission has recently adopted the Clean Power for Transport package including a Directive for deployment of alternative fuels infrastructure for CNG and LNG. Currently, the Member States have to report in their National Policy Frameworks, in a period of 24 months, their natural gas filling station development plans and fuel strategy in the nearest future. The European Union has a new transport infrastructure policy that connects the continent between East and West, North and South (TEN-T) and alternatives fuels will be taken into consideration for reducing the CO2 emissions, improve the air quality in urban areas, reduce the dependence with oil and enhance the competitiveness of the European industry. All of these researches have to be focus in the Horizon 2020, in which clean vehicles with CNG and LNG will be used to create 'smart cities and communities'. For achieving this idea, we are involved in the LNG Blue Corridor Project to demonstrate that the LNG is a real alternative for medium and long distance transport through the creation of new fuel stations in different countries such as Spain, France or Portugal. (author).

An Experimental Investigation of Self-Excited Combustion Dynamics in a Single Element Lean Direct Injection (LDI) Combustor

Science.gov (United States)

Gejji, Rohan M.

The management of combustion dynamics in gas turbine combustors has become more challenging as strict NOx/CO emission standards have led to engine operation in a narrow, lean regime. While premixed or partially premixed combustor configurations such as the Lean Premixed Pre-vaporized (LPP), Rich Quench Lean burn (RQL), and Lean Direct Injection (LDI) have shown a potential for reduced NOx emissions, they promote a coupling between acoustics, hydrodynamics and combustion that can lead to combustion instabilities. These couplings can be quite complex, and their detailed understanding is a pre-requisite to any engine development program and for the development of predictive capability for combustion instabilities through high-fidelity models. The overarching goal of this project is to assess the capability of high-fidelity simulation to predict combustion dynamics in low-emissions gas turbine combustors. A prototypical lean-direct-inject combustor was designed in a modular configuration so that a suitable geometry could be found by test. The combustor comprised a variable length air plenum and combustion chamber, air swirler, and fuel nozzle located inside a subsonic venturi. The venturi cross section and the fuel nozzle were consistent with previous studies. Test pressure was 1 MPa and variables included geometry and acoustic resonance, inlet temperatures, equivalence ratio, and type of liquid fuel. High-frequency pressure measurements in a well-instrumented metal chamber yielded frequencies and mode shapes as a function of inlet air temperature, equivalence ratio, fuel nozzle placement, and combustor acoustic resonances. The parametric survey was a significant effort, with over 105 tests on eight geometric configurations. A good dataset was obtained that could be used for both operating-point-dependent quantitative comparisons, and testing the ability of the simulation to predict more global trends. Results showed a very strong dependence of instability amplitude on

Methane Steam Reforming over an Ni-YSZ Solid Oxide Fuel Cell Anode in Stack Configuration

DEFF Research Database (Denmark)

Mogensen, David; Grunwaldt, Jan-Dierk; Hendriksen, Peter Vang

2014-01-01

The kinetics of catalytic steam reforming of methane over an Ni-YSZ anode of a solid oxide fuel cell (SOFC) have been investigated with the cell placed in a stack configuration. In order to decrease the degree of conversion, a single cell stack with reduced area was used. Measurements were...

Environmental impact of coal mine methane emissions and responding strategies in China

Energy Technology Data Exchange (ETDEWEB)

Cheng, Y.P.; Wang, L.; Zhang, X.L. [China University of Mining & Technology, Xuzhou (China)

2011-01-15

The impact on global climate change from coal mine methane emissions in China has been drawing attention as coal production has powered its economic development. Data on coal mine methane emissions from the State Administration of Coal Mine Safety of China has been analyzed. It is estimated that the methane emission from coal mining in China reached 20 billions of cubic meters in 2008, most of which comes from state-owned coal mines with high-gas content. China releases six times as much of methane from coal mines as compared to the United States. However, Chinese methane emission from coal production accounts for only a very small proportion on the environmental impact when compared to emissions of carbon dioxide from fossil fuel consumption. The Chinese government has shown environmental awareness and resolution on the mitigation and utilization of coal mine methane emissions. Measures have been taken to implement the programs of mitigation and utilization of coal mine methane, and at the same time, to ensure mining safety. Nearly 7.2 billions of cubic meters of methane were drained from the coal mines, and 32% of it was utilized in 2008. The slow advancement of technologies for the drainage and utilization of low-concentration methane from ventilation air hinders the progress of mitigation of atmospheric methane and the utilization of coal mine methane emissions.

Process analysis of an oxygen lean oxy-fuel power plant with co-production of synthesis gas

International Nuclear Information System (INIS)

Normann, Fredrik; Thunman, Henrik; Johnsson, Filip

2009-01-01

This paper investigates new possibilities and synergy effects for an oxy-fuel fired polygeneration scheme (transportation fuel and electricity) with carbon capture and co-firing of biomass. The proposed process has the potential to make the oxy-fuel process more effective through a sub-stoichiometric combustion in-between normal combustion and gasification, which lowers the need for oxygen within the process. The sub-stoichiometric combustion yields production of synthesis gas, which is utilised in an integrated synthesis to dimethyl ether (DME). The process is kept CO 2 neutral through co-combustion of biomass in the process. The proposed scheme is simulated with a computer model with a previous study of an oxy-fuel power plant as a reference process. The degree of sub-stoichiometric combustion, or amount of synthesis gas produced, is optimised with respect to the overall efficiency. The maximal efficiency was found at a stoichiometric ratio just below 0.6 with the efficiency for the electricity producing oxy-fuel process of 0.35 and a DME process efficiency of 0.63. It can be concluded that the proposed oxygen lean combustion process constitutes a way to improve the oxy-fuel carbon capture processes with an efficient production of DME in a polygeneration process

Magnesium carbide synthesis from methane and magnesium oxide - a potential methodology for natural gas conversion to premium fuels and chemicals

Energy Technology Data Exchange (ETDEWEB)

Diaz, A.F.; Modestino, A.J.; Howard, J.B. [Massachusetts Institute of Technology, Cambridge, MA (United States)] [and others

1995-12-31

Diversification of the raw materials base for manufacturing premium fuels and chemicals offers U.S. and international consumers economic and strategic benefits. Extensive reserves of natural gas in the world provide a valuable source of clean gaseous fuel and chemical feedstock. Assuming the availability of suitable conversion processes, natural gas offers the prospect of improving flexibility in liquid fuels and chemicals manufacture, and thus, the opportunity to complement, supplement, or displace petroleum-based production as economic and strategic considerations require. The composition of natural gas varies from reservoir to reservoir but the principal hydrocarbon constituent is always methane (CH{sub 4}). With its high hydrogen-to-carbon ratio, methane has the potential to produce hydrogen or hydrogen-rich products. However, methane is a very chemically stable molecule and, thus, is not readily transformed to other molecules or easily reformed to its elements (H{sub 2} and carbon). In many cases, further research is needed to augment selectivity to desired product(s), increase single-pass conversions, or improve economics (e.g. there have been estimates of $50/bbl or more for liquid products) before the full potential of these methodologies can be realized on a commercial scale. With the trade-off between gas conversion and product selectivity, a major challenge common to many of these technologies is to simultaneously achieve high methane single-pass conversions and high selectivity to desired products. Based on the results of the scoping runs, there appears to be strong indications that a breakthrough has finally been achieved in that synthesis of magnesium carbides from MgO and methane in the arc discharge reactor has been demonstrated.

Fuel density effect on near nozzle flow field in small laminar coflow diffusion flames

KAUST Repository

Xiong, Yuan

2015-01-01

Flow characteristics in small coflow diffusion flames were investigated with a particular focus on the near-nozzle region and on the buoyancy force exerted on fuels with densities lighter and heavier than air (methane, ethylene, propane, and n-butane). The flow-fields were visualized through the trajectories of seed particles. The particle image velocimetry technique was also adopted for quantitative velocity field measurements. The results showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle, emphasizing the importance of the relative density of the fuel to that of the air on the flow-field. Nozzle heating influenced the near-nozzle flow-field particularly among lighter fuels (methane and ethylene). Numerical simulations were also conducted, focusing specifically on the effect of specifying inlet boundary conditions for fuel. The results showed that a fuel inlet boundary with a fully developed velocity profile for cases with long tubes should be specified inside the fuel tube to permit satisfactory prediction of the flow-field. The calculated temperature fields also indicated the importance of the selection of the location of the inlet boundary, especially in testing various combustion models that include soot in small coflow diffusion flames. © 2014 The Combustion Institute.

NO formation in the burnout region of a partially premixed methane-air flame with upstream heat loss

Energy Technology Data Exchange (ETDEWEB)

Mokhov, A.V.; Levinsky, H.B.

1999-09-01

Measurements of temperature and NO concentration in laminar, partially premixed methane-air flames stabilized on a ceramic burner in coflow are reported. The NO concentration and temperature were determined by laser-induced fluorescence (LIF) and coherent anti-Stokes Raman scattering (CARS), respectively. Upstream heat loss to the burner was varied by changing the exit velocity of the fuel-air mixture at a constant equivalence ratio of 1,3; this alters the structure of the flame from an axisymmetric Bunsen-type to a strongly stabilized flat flame. To facilitate analysis of the results, a method is derived for separating the effects of dilution from those of chemical reaction based on the relation between the measured temperature and the local mixture fraction, including the effects of upstream heat loss. Using this method, the amount of NO formed during burnout of the hot, fuel-rich combustion products can be ascertained. In the Bunsen-type flame, it is seen that {approximately}40 ppm of NO are produced in this burnout region, at temperatures between {approximately}2,100 K and {approximately}1,900 K, probably via the Zeldovich mechanism. Reducing the exit velocity of 12 cm/s reduces the flame temperature substantially, and effectively eliminates this contribution. At velocities of 12 and 8 cm/s, {approximately}10 ppm of NO are formed in the burnout region, even though the gas temperatures are too low for Zeldovich NO to be significant. Although the mechanism responsible for these observations is as yet unclear, the results are consistent with the idea that the low temperatures in the fuel-rich gases caused by upstream heat loss retard the conversion of HCN (formed via the Fenimore mechanism) to NO, with this residual HCN then being converted to NO during burnout.

Effect of pilot fuel quantity on the performance of a dual fuel engine

Energy Technology Data Exchange (ETDEWEB)

Abd Alla, G.H.; Soliman, H.A.; Badr, O.A.; Abd Rabbo, M.F. [Zagazig University, Cairo (Egypt). Shoubra Faculty of Engineering

2000-04-01

It is well known that the operation of dual fuel engines at lower loads suffers from lower thermal efficiency and higher unburned percentages of fuel. To rectify this problem, tests have been conducted on a special single cylinder compression ignition research engine (Ricardo E6) to investigate the effect of pilot fuel quantity on the performance of an indirect injection diesel engine fuelled with gaseous fuel. Diesel fuel was used as the pilot fuel and methane or propane was used as the main fuel which was inducted into the intake manifold to mix with the intake air. Through experimental investigations, it is shown that, the low efficiency and excess emissions at light loads can be improved significantly by increasing the amount of pilot fuel, while increasing the amount of pilot fuel at high loads led to early knocking. (author)

Assessment of methane-related fuels for automotive fleet vehicles: technical, supply, and economic assessments

Energy Technology Data Exchange (ETDEWEB)

1982-02-01

The use of methane-related fuels, derived from a variety of sources, in highway vehicles is assessed. Methane, as used here, includes natural gas (NG) as well as synthetic natural gas (SNG). Methanol is included because it can be produced from NG or the same resources as SNG, and because it is a liquid fuel at normal ambient conditions. Technological, operational, efficiency, petroleum displacement, supply, safety, and economic issues are analyzed. In principle, both NG and methanol allow more efficient engine operation than gasoline. In practice, engines are at present rarely optimized for NG and methanol. On the basis of energy expended from resource extraction to end use, only optimized LNG vehicles are more efficient than their gasoline counterparts. By 1985, up to 16% of total petroleum-based highway vehicle fuel could be displaced by large fleets with central NG fueling depots. Excluding diesel vehicles, which need technology advances to use NG, savings of 8% are projected. Methanol use by large fleets could displace up to 8% of petroleum-based highway vehicle fuel from spark-ignition vehicles and another 9% from diesel vehicles with technology advances. The US NG supply appears adequate to accommodate fleet use. Supply projections, future price differential versus gasoline, and user economics are uncertain. In many cases, attractive paybacks can occur. Compressed NG now costs on average about $0.65 less than gasoline, per energy-equivalent gallon. Methanol supply projections, future prices, and user economics are even more uncertain. Current and projected near-term methanol supplies are far from adequate to support fleet use. Methanol presently costs more than gasoline on an equal-energy basis, but is projected to cost less if produced from coal instead of NG or petroleum.

Bio-methane via fast pyrolysis of biomass

International Nuclear Information System (INIS)

Görling, Martin; Larsson, Mårten; Alvfors, Per

2013-01-01

Highlights: ► Pyrolysis gases can efficiently be upgraded to bio-methane. ► The integration can increase energy efficiency and provide a renewable vehicle fuel. ► The biomass to bio-methane conversion efficiency is 83% (HHV). ► The efficiency is higher compared to bio-methane produced via gasification. ► Competitive alternative to other alternatives of bio-oil upgrading. - Abstract: Bio-methane, a renewable vehicle fuel, is today produced by anaerobic digestion and a 2nd generation production route via gasification is under development. This paper proposes a poly-generation plant that produces bio-methane, bio-char and heat via fast pyrolysis of biomass. The energy and material flows for the fuel synthesis are calculated by process simulation in Aspen Plus®. The production of bio-methane and bio-char amounts to 15.5 MW and 3.7 MW, when the total inputs are 23 MW raw biomass and 1.39 MW electricity respectively (HHV basis). The results indicate an overall efficiency of 84% including high-temperature heat and the biomass to bio-methane yield amounts to 83% after allocation of the biomass input to the final products (HHV basis). The overall energy efficiency is higher for the suggested plant than for the gasification production route and is therefore a competitive route for bio-methane production

Methane gas from cow dung

Energy Technology Data Exchange (ETDEWEB)

1974-01-01

The Khadi and Village Industries Commission offers a gobar gas (methane gas) production scheme. The gas plant, available in sizes of 60 to 3000 cu ft, requires only low maintenance expenditures. The cow dung, which is at present being wasted or burned as domestic fuel, can be used for manufacturing methane for fuel gas. The residue will be a good fertilizer for increasing food production. There are now about 4000 gobar gas plants in India.

The Application of a Jet Fan for the Control of Air and Methane Streams Mixing at the Excavations Cross - The Results of Numerical Simulation

Science.gov (United States)

Wrona, Paweł; Różański, Zenon; Pach, Grzegorz; Domagała, Lech

2016-09-01

The paper presents the results of numerical simulations into the distribution of methane concentration at the intersection of two excavations with a fan (turned on) giving the air stream to the area of the crossing. Assumed case represents emergency situation related to the unexpected flow of methane from an excavation and its mixing with fresh air. It is possible when sudden gas outburst takes place, methane leaks from methane drainage system or gas leaks out the pipelines of underground coal gasification devices. Three options were considered - corresponding to three different speeds of the jet fan. They represent three stages of fan work. First - low air speed is forced by a pneumatic fan, when electricity is cut off after high methane concentration detection. Medium speed can be forced by pneumatic-electric device when methane concentration allows to turn on the electricity. Third, the highest speed is for electric fans. Simulations were carried out in the Fire Dynamics Simulator (FDS) belongs to the group of programs Computational Fluid Dynamics (CFD). The governing equations are being solved in a numerical way. It was shown that proposed solution allows partial dilution of methane in every variant of speed what should allow escape of the miners from hazardous area.

Application of jatropha oil and biogas in a dual fuel engine for rural electrification

Energy Technology Data Exchange (ETDEWEB)

Kerkhof, E.

2008-06-15

In this thesis, the technical feasibility of using jatropha oil and biogas for dual fuel generators is investigated. This technology could be used for electricity generation in rural areas in developing countries. The use of jatropha oil and biogas is considered a sustainable energy supply, when both fuels are produced locally. The local production of fuel and generation of electricity could result in economic development and poverty reduction. In order to investigate the technical feasibility, a parameter study is performed, an experimental set-up is constructed and experiments are carried out. Three performance parameters are investigated: thermal efficiency, because it is a direct measure for fuel efficiency; volumetric efficiency, because it is a measure for power output; and air-excess ratio, because it influences particulate emissions and HC emissions. The parameter study is conducted, to predict the effect of dual fuel operation, by deriving expressions for the performance parameters. The experiments are carried out to assess the effect of dual fuel operation on performance and to find the operation limits (smoke limit and knock limit). Experiments are carried out on a 12 kW diesel generator set. The jatropha oil that is used is pure oil. Biogas mainly consists of methane and carbon dioxide. Simulated, bottled, biogas of different quality is used (i.e. CH4/CO2 ratios). Pure methane is also tested as gaseous fuel. Gas is added to the inlet air with a venturi. The design of the venturi limited the gas flow; consequently the maximum heat release fraction of methane was 80% for pure methane and approximately 70% for biogas. Tests were performed at 6, 8 and 10 kW load. The engine showed a thermal efficiency characteristic for pure jatropha oil operation, which is expected for a diesel generator. The characteristic for jatropha oil did not deviate from that of diesel. At full load, thermal efficiency is approximately 32%. Under dual fuel operation, with biogas, at

Radial lean direct injection burner

Science.gov (United States)

Khan, Abdul Rafey; Kraemer, Gilbert Otto; Stevenson, Christian Xavier

2012-09-04

A burner for use in a gas turbine engine includes a burner tube having an inlet end and an outlet end; a plurality of air passages extending axially in the burner tube configured to convey air flows from the inlet end to the outlet end; a plurality of fuel passages extending axially along the burner tube and spaced around the plurality of air passage configured to convey fuel from the inlet end to the outlet end; and a radial air swirler provided at the outlet end configured to direct the air flows radially toward the outlet end and impart swirl to the air flows. The radial air swirler includes a plurality of vanes to direct and swirl the air flows and an end plate. The end plate includes a plurality of fuel injection holes to inject the fuel radially into the swirling air flows. A method of mixing air and fuel in a burner of a gas turbine is also provided. The burner includes a burner tube including an inlet end, an outlet end, a plurality of axial air passages, and a plurality of axial fuel passages. The method includes introducing an air flow into the air passages at the inlet end; introducing a fuel into fuel passages; swirling the air flow at the outlet end; and radially injecting the fuel into the swirling air flow.

Study of gas (CNG) SI engine with pre-chamber. Improvement of the indicated thermal efficiency on lean mixture with EGR and supercharging; Fukushitsushiki hibana tenka asshuku tennen gas (CNG) engine ni kansuru kenkyu. Kakyu to EGR ni yoru kihakuiki no netsukoritsu kaizen

Energy Technology Data Exchange (ETDEWEB)

Yonetani, H.; Fukutani, I. [Polytechnic University, Kanagawa (Japan)

1998-10-15

As lean burn of compressed natural gas (CNG) is applied to conventional gasoline engines, a combustion period largely increases, resulting in large combustion fluctuation and low thermal efficiency. Heterogeneous spacial air/fuel ratios also have an effect on combustion in lean burn area. By preparing a pre-chamber for a combustion chamber of high- compression ratio CNG pre-mixing SI engines to utilize premixture turbulence, rapid flame propagation is obtained in lean burn area, resulting high combustion performance. Furthermore, study was made on improvement of combustion performance in lean burn area under various compression ratios, intake pressures, pre-chamber shapes and EGR ratios. As a result, lean burn operation at high intake pressure by supercharging showed possible improvement of a thermal efficiency and expansion of inflammable limits. Higher thermal efficiency in lean burn area was also obtained by using higher compression ratios considering heat loss. Although EGR was effective in controlling NOx formed in lean burn area, strict control of both air excess rate and EGR rate was required to prevent lower thermal efficiency. 2 refs., 8 figs., 1 tab.

Fuel flexible distributed combustion for efficient and clean gas turbine engines

International Nuclear Information System (INIS)

Khalil, Ahmed E.E.; Gupta, Ashwani K.

2013-01-01

Highlights: • Examined distributed combustion for gas turbines applications using HiTAC. • Gaseous, liquid, conventional and bio-fuels are examined with ultra-low emissions. • Novel design of fuel flexibility without any atomizer for liquid fuel sprays. • Demonstrated fuel flexibility with emissions x and CO, low noise, enhanced stability, higher efficiency and alleviation of combustion instability. Distributed reaction conditions were achieved using swirl for desirable controlled mixing between the injected air, fuel and hot reactive gases from within the combustor prior to mixture ignition. In this paper, distributed combustion is further investigated using a variety of fuels. Gaseous (methane, diluted methane, hydrogen enriched methane and propane) and liquid fuels, including both traditional (kerosene) and alternate fuels (ethanol) that cover a wide range of calorific values are investigated with emphasis on pollutants emission and combustor performance with each fuel. For liquid fuels, no atomization or spray device was used. Performance evaluation with the different fuels was established to outline the flexibility of the combustor using a wide range of fuels of different composition, phase and calorific value with specific focus on ultra-low pollutants emission. Results obtained on pollutants emission and OH * chemiluminescence for the specific fuels at various equivalence ratios are presented. Near distributed combustion conditions with less than 8 PPM of NO emission were demonstrated under novel premixed conditions for the various fuels tested at heat (energy) release intensity (HRI) of 27 MW/m 3 -atm. and a rather high equivalence ratio of 0.6. Higher equivalence ratios lacked favorable distributed combustion conditions. For the same conditions, CO emission varied for each fuel; less than 10 ppm were demonstrated for methane based fuels, while heavier liquid fuels provided less than 40 ppm CO emissions. Lower emissions of NO ( x can be possible by

Auto-ignitions of a methane/air mixture at high and intermediate temperatures

Science.gov (United States)

Leschevich, V. V.; Martynenko, V. V.; Penyazkov, O. G.; Sevrouk, K. L.; Shabunya, S. I.

2016-09-01

A rapid compression machine (RCM) and a shock tube (ST) have been employed to study ignition delay times of homogeneous methane/air mixtures at intermediate-to-high temperatures. Both facilities allow measurements to be made at temperatures of 900-2000 K, at pressures of 0.38-2.23 MPa, and at equivalence ratios of 0.5, 1.0, and 2.0. In ST experiments, nitrogen served as a diluent gas, whereas in RCM runs the diluent gas composition ranged from pure nitrogen to pure argon. Recording pressure, UV, and visible emissions identified the evolution of chemical reactions. Correlations of ignition delay time were generated from the data for each facility. At temperatures below 1300 K, a significant reduction of average activation energy from 53 to 15.3 kcal/mol was obtained. Moreover, the RCM data showed significant scatter that dramatically increased with decreasing temperature. An explanation for the abnormal scatter in the data was proposed based on the high-speed visualization of auto-ignition phenomena and experiments performed with oxygen-free and fuel-free mixtures. It is proposed that the main reason for such a significant reduction of average activation energy is attributable to the premature ignition of ultrafine particles in the reactive mixture.

Optical sensor system for time-resolved quantification of methane densities in CH4-fueled spark ignition engines.

Science.gov (United States)

Golibrzuch, Kai; Digulla, Finn-Erik; Bauke, Stephan; Wackerbarth, Hainer; Thiele, Olaf; Berg, Thomas

2017-08-01

We present the development and the first application of an optical sensor system that allows single-cycle determination of methane (CH 4 ) concentration inside internal combustion (IC) engines. We use non-dispersive infrared absorption spectroscopy to detect the CH 4 density with a time resolution up to 33 μs at acquisition rates of 30 kHz. The measurement scheme takes advantage of the strong temperature dependence of the absorption band applying two detection channels for CH 4 that detect different spectral regions of the ν 3 anti-symmetric C-H-stretch absorption. The strategy allows the simultaneous determination of fuel concentration as well as gas temperature. We show the proof-of-concept by validation of the measurement strategy in static pressure cell experiments as well as its application to a methane-fueled IC engine using a modified spark plug probe. Our results clearly demonstrate that it is crucial to determine the CH 4 temperature in the probe volume. Due to thermal influences of the sensor probe, the temperature needed to calculate the desired quantities (fuel density, fuel concentration) significantly differs from the gas phase temperature in the rest of the combustion chamber and estimations from standard thermodynamic models, e.g., polytropic compression, will fail.

Hydrogen as automotive fuel

International Nuclear Information System (INIS)

Ambrosini, G.; Ciancia, A.; Pede, G.; Brighigna, M.

1993-01-01

Hydrogen fueled vehicles may just be the answer to the air pollution problem in highly polluted urban environments where the innovative vehicle's air pollution abatement characteristics would justify its high operating costs as compared with those of conventional automotive alternatives. This paper examines the feasibility of hydrogen as an automotive fuel by analyzing the following aspects: the chemical-physical properties of hydrogen in relation to its use in internal combustion engines; the modifications necessary to adapt internal combustion engines to hydrogen use; hydrogen fuel injection systems; current production technologies and commercialization status of hydrogen automotive fuels; energy efficiency ratings; environmental impacts; in-vehicle storage systems - involving the use of hydrides, high pressure systems and liquid hydrogen storage systems; performance in terms of pay-load ratio; autonomous operation; and operating costs. With reference to recent trial results being obtained in the USA, an assessment is also made of the feasibility of the use of methane-hydrogen mixtures as automotive fuels. The paper concludes with a review of progress being made by ENEA (the Italian Agency for New Technology, Energy and the Environment) in the development of fuel storage and electronic fuel injection systems for hydrogen powered vehicles

Development and governance of renewable methane use in transport

Energy Technology Data Exchange (ETDEWEB)

Lampinen, Ari

2013-10-15

Renewable methane is promoted in many countries as a sustainable alternative to fossil fuels in all types of transport applications. This article examines development, governance and motives for the use of biogas, synthetic biogas, wind methane and other types of renewable methane in transport. Fossil methane fuels, such as natural gas, shale gas and synthetic natural gas, are included as a comparison. Compressed town gas played an important role in the adoption of methane for traffic use, so its history is also examined. Three waves of development in the use of traffic biogas are identified: the Second World War, the 1970s oil crises, and the present day quest for sustainability. While biogas has been used in transport since the 1930s, the other renewable methane fuels are now emerging in the commercial market with only a few years of history. The article looks at the use of renewable methane in a global perspective, although most of the examples are from Europe, as the majority of the technological and political advances have been European.

Improvement performance and emissions in a diesel engine dual-fueled with natural gas; Tennen gas dual fuel diesel kikan no seino haishutsu gas tokusei no kaizen

Energy Technology Data Exchange (ETDEWEB)

Nakayama, S; Okamoto, T; Kusaka, J; Daisho, Y; Kihara, R; Saito, T [Waseda University, Tokyo (Japan)

1997-10-01

This paper deals with a study on combustion and emission characteristics of a direct injection diesel engine dual-fueled with natural gas. Dual fueling systems tend to emit high unburned fuel especially at low load, resulting in a decreased thermal efficiency. This is because natural gas-air mixtures are too lean for flame to propagate under low load conditions. Intake charge heating and uncooled EGR are very useful to improve emissions and thermal efficiency at low load. Such favorable effects are supported by NO kinetic simulations. 2 refs., 13 figs.

Forecasting Air Traffic and corresponding Jet-Fuel Demand until 2025

International Nuclear Information System (INIS)

Cheze, Benoit; Gastineau, Pascal; Chevallier, Julien

2010-01-01

This paper provides i) air traffic and ii) Jet-Fuel demand projections at the worldwide level and for eight geographical zones until 2025. The general methodology may be summarized in two steps. First, air traffic forecasts are estimated using econometric methods. The modeling is performed for eight geographical zones, by using dynamic panel-data econometrics. Once estimated from historical data, the model is then used to generate air traffic forecasts. Second, the conversion of air traffic projections into quantities of Jet-Fuel is accomplished using the 'Traffic Efficiency' method developed previously by UK DTI to support the IPCC (IPCC (1999)). One of our major contribution consists in proposing an alternative methodology to obtain Energy Efficiency coefficients and energy efficiency improvements estimates based on modeling at the macro-level. These estimates are obtained by directly comparing the evolution of both Jet-Fuel consumption and air traffic time series from 1983 to 2006. According to our 'Business As Usual' scenario, air traffic should increase by about 100% between 2008 and 2025 at the world level, corresponding to a yearly average growth rate of about 4.7%. World Jet-Fuel demand is expected to increase by about 38% during the same period, corresponding to a yearly average growth rate of about 1, 9% per year. Air traffic energy efficiency improvements yield effectively to reduce the effect of air traffic rise on the Jet-Fuel demand increase, but do not annihilate it. Thus, Jet- Fuel demand is unlikely to diminish unless there is a radical technological shift, or air travel demand is restricted. (authors)

Evaluation of concepts for controlling exhaust emissions from minimally processed petroleum and synthetic fuels

Science.gov (United States)

Russell, P. L.; Beal, G. W.; Sederquist, R. A.; Shultz, D.

1981-01-01

Rich-lean combustor concepts designed to enhance rich combustion chemistry and increase combustor flexibility for NO(x) reduction with minimally processed fuels are examined. Processes such as rich product recirculation in the rich chamber, rich-lean annihilation, and graduated air addition or staged rich combustion to release bound nitrogen in steps of reduced equivalence ratio are discussed. Variations to the baseline rapid quench section are considered, and the effect of residence time in the rich zone is investigated. The feasibility of using uncooled non-metallic materials for the rich zone combustion construction is also addressed. The preliminary results indicate that rich primary zone staged combustion provides environmentally acceptable operation with residual and/or synthetic coal-derived liquid fuels

Combustion Characteristics for Turbulent Prevaporized Premixed Flame Using Commercial Light Diesel and Kerosene Fuels

Directory of Open Access Journals (Sweden)

Mohamed S. Shehata

2014-01-01

Full Text Available Experimental study has been carried out for investigating fuel type, fuel blends, equivalence ratio, Reynolds number, inlet mixture temperature, and holes diameter of perforated plate affecting combustion process for turbulent prevaporized premixed air flames for different operating conditions. CO2, CO, H2, N2, C3H8, C2H6, C2H4, flame temperature, and gas flow velocity are measured along flame axis for different operating conditions. Gas chromatographic (GC and CO/CO2 infrared gas analyzer are used for measuring different species. Temperature is measured using thermocouple technique. Gas flow velocity is measured using pitot tube technique. The effect of kerosene percentage on concentration, flame temperature, and gas flow velocity is not linearly dependent. Correlations for adiabatic flame temperature for diesel and kerosene-air flames are obtained as function of mixture strength, fuel type, and inlet mixture temperature. Effect of equivalence ratio on combustion process for light diesel-air flame is greater than for kerosene-air flame. Flame temperature increases with increased Reynolds number for different operating conditions. Effect of Reynolds number on combustion process for light diesel flame is greater than for kerosene flame and also for rich flame is greater than for lean flame. The present work contributes to design and development of lean prevaporized premixed (LPP gas turbine combustors.

Flame stability and heat transfer analysis of methane-air mixtures in catalytic micro-combustors

International Nuclear Information System (INIS)

Chen, Junjie; Song, Wenya; Xu, Deguang

2017-01-01

Highlights: • The mechanisms of heat and mass transfer for loss of stability were elucidated. • Stability diagrams were constructed and design recommendations were made. • Flame characteristics were examined to determine extinction and blowout limits. • Heat loss greatly affects extinction whereas wall materials greatly affect blowout. • Radiation causes the flame to shift downstream. - Abstract: The flame stability and heat transfer characteristics of methane-air mixtures in catalytic micro-combustors were studied, using a two-dimensional computational fluid dynamics (CFD) model with detailed chemistry and transport. The effects of wall thermal conductivity, surface emissivity, fuel, flow velocity, and equivalence ratio were explored to provide guidelines for optimal design. Furthermore, the underlying mechanisms of heat and mass transfer for loss of flame stability were elucidated. Finally, stability diagrams were constructed and design recommendations were made. It was found that the heat loss strongly affects extinction, whereas the wall thermal conductivity greatly affects blowout. The presence of homogeneous chemistry extends blowout limits, especially for inlet velocities higher than 6 m/s. Increasing transverse heat transfer rate reduces stability, whereas increasing transverse mass transfer rate improves stability. Surface radiation behaves similarly to the heat conduction within the walls, but opposite trends are observed. High emissivity causes the flame to shift downstream. Methane exhibits much broader blowout limits. For a combustor with gap size of 0.8 mm, a residence time higher than 3 ms is required to prevent breakthrough, and inlet velocities lower than 0.8 m/s are the most desirable operation regime. Further increase of the wall thermal conductivity beyond 80 W/(m·K) could not yield an additional increase in stability.

Large eddy simulation and experimental study on vented gasoline-air mixture explosions in a semi-confined obstructed pipe.

Science.gov (United States)

Li, Guoqing; Du, Yang; Wang, Shimao; Qi, Sheng; Zhang, Peili; Chen, Wenzhuo

2017-10-05

In this work, LES simulation coupled with a TFC sub-grid combustion model has been performed in a semi-confined pipe (L/D=10, V=10L) in the presence of four hollow-square obstacles (BR=49.8%) with circular hollow cross-section, in order to study the premixed gasoline-air mixture explosions. The comparisons between simulated results and experimental results have been conducted. It was found that the simulated results were in good agreement with experimental data in terms of flame structures, flame locations and overpressure time histories. Moreover, the interaction between flame propagation process and obstacles, overpressure dynamics were analyzed. In addition, the effects of initial gasoline vapor concentration (lean (ϕ=1.3%), stoichiometric (ϕ=1.7%) and rich (ϕ=2.1%)), and the number of obstacles (from 1 to 4) were also investigated by experiments. Some of the experimental results have been compared with the literature data. It is found that the explosion parameters of gasoline-air mixtures (e.g. the maximum overpressure peaks, average overpressure growth rates, etc.) are different from some other fuels such as hydrogen, methane and LPG, etc. Copyright © 2017. Published by Elsevier B.V.

Catalytic properties of new anode materials for solid oxide fuel cells operated under methane at intermediary temperature

Science.gov (United States)

Sauvet, A.-L.; Fouletier, J.

The recent trend in solid oxide fuel cell concerns the use of natural gas as fuel. Steam reforming of methane is a well-established process for producing hydrogen directly at the anode side. In order to develop new anode materials, the catalytic activities of several oxides for the steam reforming of methane were characterized by gas chromatography. We studied the catalytic activity as a function of steam/carbon ratios r. The methane and the steam content were varied between 5 and 30% and between 1.5 and 3.5%, respectively, corresponding to r-values between 0.07 and 0.7. Catalyst (ruthenium and vanadium)-doped lanthanum chromites substituted with strontium, gadolinium-doped ceria (Ce 0.9Gd 0.1O 2) referred as to CeGdO 2, praseodymium oxide, molybdenum oxide and copper oxide were tested. The working temperature was fixed at 850°C, except for 5% ruthenium-doped La 1- xSr xCrO 3 where the temperature was varied between 700 and 850°C. Two types of behavior were observed as a function of the activity of the catalyst. The higher steam reforming efficiency was observed with 5% of ruthenium above 750°C.

Methane emissions from the natural gas industry

International Nuclear Information System (INIS)

Harrison, M.R.; Cowgill, R.M.; Campbell, L.M.; Lott, R.A.

1993-01-01

The U.S. EPA and the United Nation's Intergovernmental Panel on Climate Change (IPCC) have suggested that global warming could be reduced if more energy was generated using natural gas rather than fuels such as coal. An increased use of natural gas instead of coal would decrease global warming since methane emits less carbon dioxide (CO 2 ) than any fossil fuel. However, methane is a more potent as a greenhouse gas than CO 2 , and leakage from the gas system could reduce or eliminate the inherent advantage of natural gas. For this reason, methane emissions must be quantified before a national policy on preferred fuels is developed. Therefore, GRI and EPA have developed this confunded program to quantify methane emissions from the U.S. gas industry. This paper presents, for general industry review, the approach and methodology that the project is using to determine the emissions. The study will measure or calculate all gas industry methane emissions - from production at the wellhead, through the system, to the customer's meter. When these data are combined with data from other studies, a definitive comparison of the relative environmental impact of using methane versus other fuels will be possible. The study will also provide data that can be used by the industry to identify cost-effective mitigation techniques to reduce losses. The methane emissions project is being conducted in three phases: the first two phases have identified and ranked all known potential methane-emitting sources and established methods for measuring, calculating, and extrapolating emissions from those sources. The third phase, which is currently in progress, will gather sufficient data to achieve the accuracy goal. This paper briefly summarizes the methodology being used for the completion of the third phase

Evaluation of a fuel cell polymer electrolyte with Pt-Sn anode operating with H2, H2-CO mixture, propane and methane

International Nuclear Information System (INIS)

Monsalve, Carlos; Hoyos, Bibian

2005-01-01

In this work it was tested a proton Exchange membrane fuel cell with a Pt-Sn anode (in a 90:10 ratio) fed with H 2 , a H 2 -CO mixture, propane and methane under a pressure of 10 psi and temperatures of 30, 50 y 70 Celsius degrade. It was found good catalyst tolerance to the CO presence in the hydrogen current, even with catalytic activity to the CO oxidation. For the pure CO, propane and methane cases, the catalytic activity was too low. This results show that the Pt-Sn catalyst it is not appropriated for those fuels.

Effect of Intake Air Filter Condition on Vehicle Fuel Economy

Energy Technology Data Exchange (ETDEWEB)

Norman, Kevin M [ORNL; Huff, Shean P [ORNL; West, Brian H [ORNL

2009-02-01

The U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy and the U.S. Environmental Protection Agency (EPA) jointly maintain a fuel economy website (www.fueleconomy.gov), which helps fulfill their responsibility under the Energy Policy Act of 1992 to provide accurate fuel economy information [in miles per gallon (mpg)] to consumers. The site provides information on EPA fuel economy ratings for passenger cars and light trucks from 1985 to the present and other relevant information related to energy use such as alternative fuels and driving and vehicle maintenance tips. In recent years, fluctuations in the price of crude oil and corresponding fluctuations in the price of gasoline and diesel fuels have renewed interest in vehicle fuel economy in the United States. (User sessions on the fuel economy website exceeded 20 million in 2008 compared to less than 5 million in 2004 and less than 1 million in 2001.) As a result of this renewed interest and the age of some of the references cited in the tips section of the website, DOE authorized the Oak Ridge National Laboratory (ORNL) Fuels, Engines, and Emissions Research Center (FEERC) to initiate studies to validate and improve these tips. This report documents a study aimed specifically at the effect of engine air filter condition on fuel economy. The goal of this study was to explore the effects of a clogged air filter on the fuel economy of vehicles operating over prescribed test cycles. Three newer vehicles (a 2007 Buick Lucerne, a 2006 Dodge Charger, and a 2003 Toyota Camry) and an older carbureted vehicle were tested. Results show that clogging the air filter has no significant effect on the fuel economy of the newer vehicles (all fuel injected with closed-loop control and one equipped with MDS). The engine control systems were able to maintain the desired AFR regardless of intake restrictions, and therefore fuel consumption was not increased. The carbureted engine did show a decrease in

Perspectives of Use of Alternative Energy Sources in Air Transport

Directory of Open Access Journals (Sweden)

Luboš Socha

2017-01-01

Full Text Available The problem of environmental load is also reflected in air transport. Usage of fossil fuels, which are dominant nowadays, has a negative impact on the environment and also its resources are limited. Therefore, the article focuses on the prospective of use of other energy sources in aviation, such as alternative fuels (synthetic fuels, biofuels, alcohol, methane, hydrogen, solar energy and the use of fuel cells. Also, the paper briefly summarizes the approach of aircraft manufacturers to the use alternative sources.

An experimental study on turbulent lifted flames of methane in coflow jets at elevated temperatures

KAUST Repository

Choi, Byungchul

2013-01-01

An experimental study was conducted on the effects of initial temperature variation on the stabilization characteristics of turbulent nonpremixed flames in coflow jets of methane fuel diluted by nitrogen. The typical behavior seen in the study showed that the liftoff height increased linearly with the jet velocity regardless of the initial temperature in the turbulent regime. Two models were investigated for predicting liftoff heights in the methane jets: the premixed flame model and the large-scale mixing model. For the premixed flame model, the liftoff heights in the methane jets were accurately predicted using the thermal diffusivity of the unburned gas temperature αst,0, instead of that of the burned gas temperature αst,b. For the large-scale mixing model, however, the prediction of liftoff heights differed slightly for the various fuel mole fractions. However, when considering the initial fuel mass fraction YF,0, the liftoff heights were successfully predicted. This result implies that the characteristics of the unburned fuel-air mixture play a crucial role for flame stabilization in coflow jets for a variety of initial conditions. In the turbulent regime, the blowout velocity and the liftoff height at blowout could be accurately predicted by the two models based on a consideration of the physical properties and the buoyancy effect of the initial temperature variation. © 2012 Elsevier Ltd. All rights reserved.

Performance of PEM Liquid-Feed Direct Methanol-Air Fuel Cells

Science.gov (United States)

Narayanan, S. R.

1995-01-01

A direct methanol-air fuel cell operating at near atmospheric pressure, low-flow rate air, and at temperatures close to 60oC would tremendously enlarge the scope of potential applications. While earlier studies have reported performance with oxygen, the present study focuses on characterizing the performance of a PEM liquid feed direct methanol-air cell consisting of components developed in house. These cells employ Pt-Ru catalyst in the anode, Pt at the cathode and Nafion 117 as the PEM. The effect of pressure, flow rate of air and temperature on cell performance has been studied. With air, the performance level is as high as 0.437 V at 300 mA/cm2 (90oC, 20 psig, and excess air flow) has been attained. Even more significant is the performance level at 60oC, 1 atm and low flow rates of air (3-5 times stoichiometric), which is 0.4 V at 150 mA/cm2. Individual electrode potentials for the methanol and air electrode have been separated and analyzed. Fuel crossover rates and the impact of fuel crossover on the performance of the air electrode have also been measured. The study identifies issues specific to the methanol-air fuel cell and provides a basis for improvement strategies.

Effects of Driving Frequency on Propagation Characteristics of Methane - Air Premixed Flame Influenced by Ultrasonic Standing Wave

Energy Technology Data Exchange (ETDEWEB)

Bae, Dae Seok; Kim, Jeong Soo [Pukyong National University, Busan (Korea, Republic of); Seo, Hang Seok [Hanwha Corporation, DaeJeon (Korea, Republic of)

2015-02-15

An experimental study was conducted to scrutinize the influence of the frequency of an ultrasonic standing wave on the variation in the behavior of a methane-air premixed flame. The evolutionary features of the propagating flame were captured by a high-speed camera, and the macroscopic flame behavior, including the flame structure and local velocities, was investigated in detail using a post-processing analysis of the high-speed images. It was found that a structural variation and propagation-velocity augmentation of the methane-air premixed flame were caused by the intervention of the ultrasonic standing wave, which enhanced the combustion reaction. Conclusive evidence for the dependency of the flame behaviors on the driving frequency of the ultrasonic standing wave and equivalence ratio of the reactants is presented.

Reduced chemical kinetic model of detonation combustion of one- and multi-fuel gaseous mixtures with air

Science.gov (United States)

Fomin, P. A.

2018-03-01

Two-step approximate models of chemical kinetics of detonation combustion of (i) one hydrocarbon fuel CnHm (for example, methane, propane, cyclohexane etc.) and (ii) multi-fuel gaseous mixtures (∑aiCniHmi) (for example, mixture of methane and propane, synthesis gas, benzene and kerosene) are presented for the first time. The models can be used for any stoichiometry, including fuel/fuels-rich mixtures, when reaction products contain molecules of carbon. Owing to the simplicity and high accuracy, the models can be used in multi-dimensional numerical calculations of detonation waves in corresponding gaseous mixtures. The models are in consistent with the second law of thermodynamics and Le Chatelier's principle. Constants of the models have a clear physical meaning. The models can be used for calculation thermodynamic parameters of the mixture in a state of chemical equilibrium.

The potential for methane hydrate formation in deep repositories of spent nuclear fuel in granitic rocks

International Nuclear Information System (INIS)

Tohidi, Bahman; Chapoy, Antonin; Smellie, John; Puigdomenech, Ignasi

2010-12-01

The main aim of this work was to establish whether the pertaining pressure and temperature conditions and dissolved gas concentration in groundwater is conducive to gas hydrate formation using a modelling approach. The hydrate stability pressure-temperature zone of dissolved methane in the presence of salt has been obtained through calculations which show that a decrease in the system pressure and/or an increase in salt concentration favours hydrate formation, as both factors reduce equilibrium gas solubility in the aqueous phase. This behaviour is unlike that of the system including a gas phase, where the water phase is always saturated with methane, and hence the methane solubility in water is not a limiting factor. The main conclusion is that hydrate formation is not possible at the reported methane concentrations and water salinities for the Forsmark and Laxemar sites in Sweden and Olkiluoto in Finland. At the highest salinities and methane concentrations encountered, namely ∼0.00073 mole fraction methane and ∼10 mass % NaCl at a depth of 1,000 m in Olkiluoto, Finland, hydrates could form if the system temperatures and pressures are below 2.5 deg C and 60 bar, respectively, i.e. values that are much lower than those prevailing at that depth (∼20 deg C and ∼100 bar, respectively). Furthermore, the calculated results provide the necessary data to estimate the effect of increase in dissolved methane concentration on potential hydrate formation, as well as two phase flow. The available depth dependency of methane concentration at the sites studied in Sweden and Finland was used in another study to estimate the diffusive flow of methane in the rock volumes. These diffusion rates, which are highest at Olkiluoto, indicate that even if the conditions were to become favourable to methane hydrate formation, then it would take several millions of years before a thin layer of hydrates could be formed, a condition which is outside the required period of satisfactory

The potential for methane hydrate formation in deep repositories of spent nuclear fuel in granitic rocks

Energy Technology Data Exchange (ETDEWEB)

Tohidi, Bahman; Chapoy, Antonin (Hydrafact Ltd, Inst. of Petroleum Engineering, Heriot-Watt Univ., Edinburgh (United Kingdom)); Smellie, John (Conterra AB, Uppsala (Sweden)); Puigdomenech, Ignasi (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden))

2010-12-15

The main aim of this work was to establish whether the pertaining pressure and temperature conditions and dissolved gas concentration in groundwater is conducive to gas hydrate formation using a modelling approach. The hydrate stability pressure-temperature zone of dissolved methane in the presence of salt has been obtained through calculations which show that a decrease in the system pressure and/or an increase in salt concentration favours hydrate formation, as both factors reduce equilibrium gas solubility in the aqueous phase. This behaviour is unlike that of the system including a gas phase, where the water phase is always saturated with methane, and hence the methane solubility in water is not a limiting factor. The main conclusion is that hydrate formation is not possible at the reported methane concentrations and water salinities for the Forsmark and Laxemar sites in Sweden and Olkiluoto in Finland. At the highest salinities and methane concentrations encountered, namely approx0.00073 mole fraction methane and approx10 mass % NaCl at a depth of 1,000 m in Olkiluoto, Finland, hydrates could form if the system temperatures and pressures are below 2.5 deg C and 60 bar, respectively, i.e. values that are much lower than those prevailing at that depth (approx20 deg C and approx100 bar, respectively). Furthermore, the calculated results provide the necessary data to estimate the effect of increase in dissolved methane concentration on potential hydrate formation, as well as two phase flow. The available depth dependency of methane concentration at the sites studied in Sweden and Finland was used in another study to estimate the diffusive flow of methane in the rock volumes. These diffusion rates, which are highest at Olkiluoto, indicate that even if the conditions were to become favourable to methane hydrate formation, then it would take several millions of years before a thin layer of hydrates could be formed, a condition which is outside the required period of

Comparison between Hydrogen and Methane Fuels in a 3-D Scramjet at Mach 8

Science.gov (United States)

2016-06-24

scramjet using a cavity based flame holder in the T4 shock tunnel at The University of Queensland, as well as a companion fundamental CFD study. The...shock tunnel. 15. SUBJECT TERMS Airbreathing Engines, Hypersonics , Propulsion, AOARD 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18...Report Comparison between hydrogen, methane and ethylene fuels in a 3-D Scramjet at Mach 8 Professor Michael K. Smart Chair of Hypersonic Propulsion

Thermodynamic analysis of carbon formation in solid oxide fuel cells with a direct internal reformer fueled by ethanol, methanol, and methane

International Nuclear Information System (INIS)

Laosiripojana, N.; Assabumrungrat, S.; Pavarajarn, V.; Sangtongkitcharoen, W.; Tangjitmatee, A.; Praserthdam, P.

2004-01-01

'Full text:' This paper concerns a detailed thermodynamic analysis of carbon formation for a Direct Internal Reformer (DIR) Solid Oxide Fuel Cells (SOFC). The modeling of DIR-SOFC fueled by ethanol, methanol, and methane were compared. Two types of fuel cell electrolytes, i.e. oxygen-conducting and hydrogen-conducting, are considered. Equilibrium calculations were performed to find the ranges of inlet steam/fuel ratio where carbon formation is thermodynamically unfavorable in the temperature range of 500-1200 K. It was found that the key parameters determining the boundary of carbon formation are temperature, type of solid electrolyte and extent of the electrochemical reaction of hydrogen. The minimum requirements of H2O/fuel ratio for each type of fuel in which the carbon formation is thermodynamically unfavored were compared. At the same operating conditions, DIR-SOFC fueled by ethanol required the lowest inlet H2O/fuel ratio in which the carbon formation is thermodynamically unfavored. The requirement decreased with increasing temperature for all three fuels. Comparison between two types of the electrolytes reveals that the hydrogen-conducting electrolyte is impractical for use, regarding to the tendency of carbon formation. This is due mainly to the water formed by the electrochemical reaction at the electrodes. (author)

Effect of oxygenated fuel on premixed lean diesel combustion; Kihaku yokongo diesel nensho ni oyobosu gansanso nenryo kongo keiyu no eikyo

Energy Technology Data Exchange (ETDEWEB)

Sasaki, S.; Miyamoto, T.; Harada, A.; Akagawa, H.; Tsujimura, K. [New ACE Institute Co. Ltd., Tokyo (Japan)

1998-05-01

Because injection timing in diesel engines is early in a premixed lean diesel combustion system using early fuel injection, ignition timing is determined by ignitability of the fuel used. The conventional diesel fuel, which has good ignitability, causes excessively early ignition, thus aggravating fuel consumption. In order to reduce cylinder temperature with an aim of delaying ignition timing to improve the fuel consumption, attempts are being made on using low cetane fuels to reduce CO2 gas supply or compression ratio, and to vary ignitability of the fuels. The present study investigated ignition timing control and properties of exhausts by mixing different types of oxygenated fuels into light oil. Mixing the oxygenated fuels into light oil proved that the ignition timing can be controlled, and mixing such low cetane fuels as ethanol and MTBE achieved improvement in fuel consumption. Trial use of the oxygenated fuels aggravated CO concentration, which is caused because the cylinder temperature was reduced. Numerical calculations suggest that use of fuels with faster evaporation speed and lower cetane number is effective in improving the fuel consumption and the exhausts. 12 refs., 9 figs., 2 tabs.

An investigation of turbulent catalytically stabilized channel flow combustion of lean hydrogen - air mixtures

Energy Technology Data Exchange (ETDEWEB)

Mantzaras, I; Benz, P; Schaeren, R; Bombach, R [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1999-08-01

The catalytically stabilised thermal combustion (CST) of lean hydrogen-air mixtures was investigated numerically in a turbulent channel flow configuration using a two-dimensional elliptic model with detailed heterogeneous and homogeneous chemical reactions. Comparison between turbulent and laminar cases having the same incoming mean properties shows that turbulence inhibits homogeneous ignition due to increased heat transport away from the near-wall layer. The peak root-mean-square temperature and species fluctuations are always located outside the extent of the homogeneous reaction zone indicating that thermochemical fluctuations have no significant influence on gaseous combustion. (author) 4 figs., 6 refs.

A biomimetic methane-oxidising catalyst

Energy Technology Data Exchange (ETDEWEB)

Dalton, H [Warwick Univ., Coventry (United Kingdom). Dept. of Biological Sciences

1997-12-31

The diminishing resources of petroleum oil has meant that there has been considerable efforts in recent years to find a suitable substitute for gasoline as a transportation fuel. Methanol has been identified as a suitable substitute since it is a readily combustible fuel which can be manufactured from a number of different sources. Methane is commonly used as a starting material for the production of synthesis gas (CO + H{sub 2}) and hence methanol. It is well known that the cleavage of the C-H bond of methane is extremely difficult (bond energy is around 104 kcal/mol) and that fairly drastic conditions are required to convert methane into methanol. Temperatures around 1200 deg C and pressures of up to 100 atmospheres over metal catalysts in a series of reactions are required to effect this process. Efforts have been made to reduce the temperature and the number of steps by using lanthanide ruthenium oxide catalyst but such reactions are still thermodynamically endothermic. An energetically more efficient reaction would be the direct conversion of methane to methanol using oxygen as the oxidant: CH{sub 4} + 1/2O{sub 2} -> CH{sub 3}OH {Delta}H deg = - 30.7 kcal/mol. Such a direct oxidation route is manifest in the bacterially-mediated oxidation of methane by methanotrophic bacteria. These organisms effect the direct oxidation of methane to methanol by the enzyme methane monooxygenase (MMO) as part of the reaction sequences to oxidize methane to carbon dioxide. (14 refs.)

A biomimetic methane-oxidising catalyst

Energy Technology Data Exchange (ETDEWEB)

Dalton, H. [Warwick Univ., Coventry (United Kingdom). Dept. of Biological Sciences

1996-12-31

The diminishing resources of petroleum oil has meant that there has been considerable efforts in recent years to find a suitable substitute for gasoline as a transportation fuel. Methanol has been identified as a suitable substitute since it is a readily combustible fuel which can be manufactured from a number of different sources. Methane is commonly used as a starting material for the production of synthesis gas (CO + H{sub 2}) and hence methanol. It is well known that the cleavage of the C-H bond of methane is extremely difficult (bond energy is around 104 kcal/mol) and that fairly drastic conditions are required to convert methane into methanol. Temperatures around 1200 deg C and pressures of up to 100 atmospheres over metal catalysts in a series of reactions are required to effect this process. Efforts have been made to reduce the temperature and the number of steps by using lanthanide ruthenium oxide catalyst but such reactions are still thermodynamically endothermic. An energetically more efficient reaction would be the direct conversion of methane to methanol using oxygen as the oxidant: CH{sub 4} + 1/2O{sub 2} -> CH{sub 3}OH {Delta}H deg = - 30.7 kcal/mol. Such a direct oxidation route is manifest in the bacterially-mediated oxidation of methane by methanotrophic bacteria. These organisms effect the direct oxidation of methane to methanol by the enzyme methane monooxygenase (MMO) as part of the reaction sequences to oxidize methane to carbon dioxide. (14 refs.)

Selective conversion of methane to synthetic fuels using dielectric barrier discharge contacting liquid film

Energy Technology Data Exchange (ETDEWEB)

Nozaki, Tomohiro; Goujard, Valentin; Yuzawa, Shuhei; Moriyama, Shota; Okazaki, Ken [Department of Mechanical and Control Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 1528552 (Japan); Agiral, Anil, E-mail: tnozaki@mech.titech.ac.jp [Mesoscale Chemical Systems, MESA Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, PO Box 217, 7500 AE, Enschede (Netherlands)

2011-07-13

This paper presents the reaction mechanism of single-step methane partial oxidation to methanol at room temperature using non-thermal plasma microreactor. Macroscopic quantities of hydrogen peroxide (H{sub 2}O{sub 2}) and methyl hydroperoxide (CH{sub 3}OOH) are produced when methane is partially oxidized at room temperature (about 5 {sup 0}C). CH{sub 3}OOH is known to be the principle intermediate of incomplete methane oxidation product such as CH{sub 3}OH and HCHO, but has not been demonstrated experimentally so far. H{sub 2}O{sub 2} promotes post-plasma oxidation of oxygenates in the condensed plasma-synthesized liquid. At an early stage of in-liquid oxidation, H{sub 2}O{sub 2} oxidizes HCHO into HCOOH preferentially; subsequently, HCOOH is fully oxidized to CO{sub 2} and H{sub 2}O. Depending upon the concentration of oxygenates and H{sub 2}O{sub 2}, electrical conductivity of the plasma solution dramatically increased, which detrimentally influences plasma properties. Methane partial oxidation with air was also investigated from a practical viewpoint. Generation of active nitrogen species (ANS) is the key to promoting overall methane conversion in the presence of oxygen; however, fragile oxygenates were also decomposed by ANS, thus selectivity for useful oxygenates was degraded in the presence of nitrogen. When oxygen is fully consumed, CH{sub 4} conversion is also terminated and water gas shift reaction (CO + H{sub 2}O = CO{sub 2} + H{sub 2}) becomes predominant.

A Cross-Wavelet Transform Aided Rule Based Approach for Early Prediction of Lean Blow-out in Swirl-Stabilized Dump Combustor

Directory of Open Access Journals (Sweden)

Debangshu Dey

2015-03-01

Full Text Available Lean or ultralean combustion is one of the popular strategies to achieve very low emission levels. However, it is extremely susceptible to lean blow-out (LBO. The present work explores a Cross-wavelet transform (XWT aided rule based scheme for early prediction of lean blowout. XWT can be considered as an advancement of wavelet analysis which gives correlation between two waveforms in time-frequency space. In the present scheme a swirl-stabilized dump combustor is used as a laboratory-scale model of a generic gas turbine combustor with LPG as fuel. Various time series data of CH chemiluminescence signal are recorded for different flame conditions by varying equivalence ratio, flow rate and level of air-fuel premixing. Some features are extracted from the cross-wavelet spectrum of the recorded waveforms and a reference wave. The extracted features are observed to classify the flame condition into three major classes: near LBO, moderate and healthy. Moreover, a Rough Set based technique is also applied on the extracted features to generate a rule base so that it can be fed to a real time controller or expert system to take necessary control action to prevent LBO. Results show that the proposed methodology performs with an acceptable degree of accuracy.

Electrode design for direct-methane micro-tubular solid oxide fuel cell (MT-SOFC)

Science.gov (United States)

Rabuni, Mohamad Fairus; Li, Tao; Punmeechao, Puvich; Li, Kang

2018-04-01

Herein, a micro-structured electrode design has been developed via a modified phase-inversion method. A thin electrolyte integrated with a highly porous anode scaffold has been fabricated in a single-step process and developed into a complete fuel cell for direct methane (CH4) utilisation. A continuous and well-dispersed layer of copper-ceria (Cu-CeO2) was incorporated inside the micro-channels of the anode scaffold. A complete cell was investigated for direct CH4 utilisation. The well-organised micro-channels and nano-structured Cu-CeO2 anode contributed to an increase in electrochemical reaction sites that promoted charge-transfer as well as facilitating gaseous fuel distribution, resulting in outstanding performances. Excellent electrochemical performances have been achieved in both hydrogen (H2) and CH4 operation. The power density of 0.16 Wcm-2 at 750 °C with dry CH4 as fuel is one of the highest ever reported values for similar anode materials.

The new generation of exhaust aftertreatment systems for lean fuel gasoline engines; Die neue Generation von Abgasnachbehandlungssystemen fuer magerlaufende Benzinmotoren

Energy Technology Data Exchange (ETDEWEB)

Eckhoff, Stephan; Hoyer, Ruediger; Adam, Frank; Lammarck, Christian; Mueller, Wilfried [Umicore AG und Co. KG, Hanau-Wolfgang (Germany)

2010-07-01

Stratified gasoline direct injection engines show a great potential for the reduction of CO{sub 2} emissions and therefore improved fuel economy. The next generation of stratified gasoline engines with turbo charger and more efficient combustion are expected to have even lower exhaust temperatures compared with current series vehicle with stratified combustion. For this reason exhaust gas aftertreatment systems are required which have low light off temperatures for HC and CO during lean combustion and a high NOx-storage efficiency at low temperatures. This study shows the great improvements made over the last years for the development of new TWC and NOx-storage catalysts for the aftertreatment for lean GDI. A precious metal related cost reduction of about 40% was achieved for the new generation of aftertreatment systems. (orig.)

Investigation of methane steam reforming in planar porous support of solid oxide fuel cell

International Nuclear Information System (INIS)

Yang Yongping; Du Xiaoze; Yang Lijun; Huang Yuan; Xian Haizhen

2009-01-01

Adopting the porous support in integrated-planar solid oxide fuel cell (IP-SOFC) can reduce the operating temperature by reducing thickness of electrolyte layer, and also, provide internal reforming environment for hydrogen-rich fuel gas. The distributions of reactant and product components, and temperature of methane steam reforming for IP-SOFC were investigated by the developed physical and mathematical model with thermodynamic analysis, in which eleven possible reaction mechanisms were considered by the source terms and Arrhenius relationship. Numerical simulation of the model revealed that the progress of reforming reaction and the distribution of the product, H 2 , were influenced by the operating conditions, included that of temperature, ratio of H 2 O and CH 4 , as well as by the porosity of the supporting material. The simulating results indicate that the methane conversion rate can reach its maximum value under the operating temperature of 800 deg. C and porosity of ε = 0.4, which rather approximate to the practical operating conditions of IP-SOFC. In addition, characteristics of carbon deposition on surface of catalyst were discussed under various operating conditions and configuration parameters of the porous support. The present works provided some theoretical explanations to the numerous experimental observations and engineered practices

Attempt of lean burn of a 4 cycle gasoline engine by the aid of low pressure air assisted in-cylinder injection; Tonai kuki nenryo funsha ni yoru lean burn no kokoromi

Energy Technology Data Exchange (ETDEWEB)

Hatakeyama, S; Kondo, M; Sekiya, Y; Murayama, T [Hokkaido Automotive Engineering College, Hokkaido (Japan)

1997-10-01

Comparable performance and exhaust emission with conventional carburetor was obtained by a low Pressure air assisted in-cylinder injection system. And lean burn of idling and light load operation till A/F=70 was realized by installing a spark Plug and a reed type injection nozzle in a divided combustion chambaer of a 4 cycle gasoline engine. 2 refs., 10 figs.

Advancing the Limits of Dual Fuel Combustion

Energy Technology Data Exchange (ETDEWEB)

Koenigsson, Fredrik

2012-07-01

There is a growing interest in alternative transport fuels. There are two underlying reasons for this interest; the desire to decrease the environmental impact of transports and the need to compensate for the declining availability of petroleum. In the light of both these factors the Diesel Dual Fuel, DDF, engine is an attractive concept. The primary fuel of the DDF engine is methane, which can be derived both from renewables and from fossil sources. Methane from organic waste; commonly referred to as biomethane, can provide a reduction in greenhouse gases unmatched by any other fuel. The DDF engine is from a combustion point of view a hybrid between the diesel and the otto engine and it shares characteristics with both. This work identifies the main challenges of DDF operation and suggests methods to overcome them. Injector tip temperature and pre-ignitions have been found to limit performance in addition to the restrictions known from literature such as knock and emissions of NO{sub x} and HC. HC emissions are especially challenging at light load where throttling is required to promote flame propagation. For this reason it is desired to increase the lean limit in the light load range in order to reduce pumping losses and increase efficiency. It is shown that the best results in this area are achieved by using early diesel injection to achieve HCCI/RCCI combustion where combustion phasing is controlled by the ratio between diesel and methane. However, even without committing to HCCI/RCCI combustion and the difficult control issues associated with it, substantial gains are accomplished by splitting the diesel injection into two and allocating most of the diesel fuel to the early injection. HCCI/RCCI and PPCI combustion can be used with great effect to reduce the emissions of unburned hydrocarbons at light load. At high load, the challenges that need to be overcome are mostly related to heat. Injector tip temperatures need to be observed since the cooling effect of

Effect of air preheat temperature on the MILD combustion of syngas

International Nuclear Information System (INIS)

Huang, Mingming; Zhang, Zhedian; Shao, Weiwei; Xiong, Yan; Liu, Yan; Lei, Fulin; Xiao, Yunhan

2014-01-01

Highlights: • MILD combustion is achieved with reaction zone covering the entire combustion chamber. • Critical equivalence ratio for the occurrence of MILD combustion is identified. • MILD regime can be established for syngas fuel under air preheating conditions. - Abstract: The effect of air preheat temperature on MILD (Moderate or Intense Low-oxygen Dilution) combustion of coal-derived syngas was examined in parallel jet forward flow combustor. The results were presented on flow field using numerical simulations and on global flame signatures, OH ∗ radicals distribution and exhaust emissions using experiments. The discrete and high speed air/fuel injections into the combustor is necessary for the establishment of MILD conditions, because they cause strong gas recirculation and form large mixing region between the air and fuel jets. The critical equivalence ratio above which MILD combustion occurred was identified. The MILD regime was established for syngas fuel under air preheating conditions with lean operational limit and suppressed NO x and CO emissions. In the MILD combustion regime, the air preheating resulted in higher NO x but lower CO emissions, while the increase of equivalence ratio led to the increase of NO x and the decrease of CO emissions

Interim results from UO2 fuel oxidation tests in air

International Nuclear Information System (INIS)

Campbell, T.K.; Gilbert, E.R.; Thornhill, C.K.; White, G.D.; Piepel, G.F.; Griffin, C.W.j.

1987-08-01

An experimental program is being conducted at Pacific Northwest Laboratory (PNL) to extend the characterization of spent fuel oxidation in air. To characterize oxidation behavior of irradiated UO 2 , fuel oxidation tests were performed on declad light-water reactor spent fuel and nonirradited UO 2 pellets in the temperature range of 135 to 250 0 C. These tests were designed to determine the important independent variables that might affect spent fuel oxidation behavior. The data from this program, when combined with the test results from other programs, will be used to develop recommended spent fuel dry-storage temperature limits in air. This report describes interim test results. The initial PNL investigations of nonirradiated and spent fuels identified the important testing variables as temperature, fuel burnup, radiolysis of the air, fuel microstructure, and moisture in the air. Based on these initial results, a more extensive statistically designed test matrix was developed to study the effects of temperature, burnup, and moisture on the oxidation behavior of spent fuel. Oxidation tests were initiated using both boiling-water reactor and pressurized-water reactor fuels from several different reactors with burnups from 8 to 34 GWd/MTU. A 10 5 R/h gamma field was applied to the test ovens to simulate dry storage cask conditions. Nonirradiated fuel was included as a control. This report describes experimental results from the initial tests on both the spent and nonirradiated fuels and results to date on the tests in a 10 5 R/h gamma field. 33 refs., 51 figs., 6 tabs

The influence of droplet evaporation on fuel-air mixing rate in a burner

Science.gov (United States)

Komiyama, K.; Flagan, R. C.; Heywood, J. B.

1977-01-01

Experiments involving combustion of a variety of hydrocarbon fuels in a simple atmospheric pressure burner were used to evaluate the role of droplet evaporation in the fuel/air mixing process in liquid fuel spray flames. Both air-assist atomization and pressure atomization processes were studied; fuel/air mixing rates were determined on the basis of cross-section average oxygen concentrations for stoichiometric overall operation. In general, it is concluded that droplets act as point sources of fuel vapor until evaporation, when the fuel jet length scale may become important in determining nonuniformities of the fuel vapor concentration. In addition, air-assist atomizers are found to have short droplet evaporation times with respect to the duration of the fuel/air mixing process, while for the pressure jet atomizer the characteristic evaporation and mixing times are similar.

Effect of aviation fuel type and fuel injection conditions on the spray characteristics of pressure swirl and hybrid air blast fuel injectors

Science.gov (United States)

Feddema, Rick

Feddema, Rick T. M.S.M.E., Purdue University, December 2013. Effect of Aviation Fuel Type and Fuel Injection Conditions on the Spray Characteristics of Pressure Swirl and Hybrid Air Blast Fuel Injectors. Major Professor: Dr. Paul E. Sojka, School of Mechanical Engineering Spray performance of pressure swirl and hybrid air blast fuel injectors are central to combustion stability, combustor heat management, and pollutant formation in aviation gas turbine engines. Next generation aviation gas turbine engines will optimize spray atomization characteristics of the fuel injector in order to achieve engine efficiency and emissions requirements. Fuel injector spray atomization performance is affected by the type of fuel injector, fuel liquid properties, fuel injection pressure, fuel injection temperature, and ambient pressure. Performance of pressure swirl atomizer and hybrid air blast nozzle type fuel injectors are compared in this study. Aviation jet fuels, JP-8, Jet A, JP-5, and JP-10 and their effect on fuel injector performance is investigated. Fuel injector set conditions involving fuel injector pressure, fuel temperature and ambient pressure are varied in order to compare each fuel type. One objective of this thesis is to contribute spray patternation measurements to the body of existing drop size data in the literature. Fuel droplet size tends to increase with decreasing fuel injection pressure, decreasing fuel injection temperature and increasing ambient injection pressure. The differences between fuel types at particular set conditions occur due to differences in liquid properties between fuels. Liquid viscosity and surface tension are identified to be fuel-specific properties that affect the drop size of the fuel. An open aspect of current research that this paper addresses is how much the type of aviation jet fuel affects spray atomization characteristics. Conventional aviation fuel specifications are becoming more important with new interest in alternative

Methane adsorption on activated carbon

NARCIS (Netherlands)

Perl, Andras; Koopman, Folkert; Jansen, Peter; de Rooij, Marietta; van Gemert, Wim

2014-01-01

Methane storage in adsorbed form is a promising way to effectively and safely store fuel for vehicular transportation or for any other potential application. In a solid adsorbent, nanometer wide pores can trap methane by van der Waals forces as high density fluid at low pressure and room

Dynamic Behavior of Reverse Flow Reactor for Lean Methane Combustion

OpenAIRE

Yogi W. Budhi; M. Effendy; Yazid Bindar; Subagjo

2014-01-01

The stability of reactor operation for catalytic oxidation of lean CH4 has been investigated through modeling and simulation, particularly the influence of switching time and heat extraction on reverse flow reactor (RFR) performance. A mathematical model of the RFR was developed, based on one-dimensional pseudo-homogeneous model for mass and heat balances, incorporating heat loss through the reactor wall. The configuration of the RFR consisted of inert-catalyst-inert, with or without heat ext...

MethaneSat: Detecting Methane Emissions in the Barnett Shale Region

Science.gov (United States)

Propp, A. M.; Benmergui, J. S.; Turner, A. J.; Wofsy, S. C.

2017-12-01

In this study, we investigate the new information that will be provided by MethaneSat, a proposed satellite that will measure the total column dry-air mole fraction of methane at 1x1 km or 2x2 km spatial resolution with 0.1-0.2% random error. We run an atmospheric model to simulate MethaneSat's ability to characterize methane emissions from the Barnett Shale, a natural gas province in Texas. For comparison, we perform observation system simulation experiments (OSSEs) for MethaneSat, the National Oceanic and Atmospheric administration (NOAA) surface and aircraft network, and Greenhouse Gases Observing Satellite (GOSAT). The results demonstrate the added benefit that MethaneSat would provide in our efforts to monitor and report methane emissions. We find that MethaneSat successfully quantifies total methane emissions in the region, as well as their spatial distribution and steep gradients. Under the same test conditions, both the NOAA network and GOSAT fail to capture this information. Furthermore, we find that the results for MethaneSat depend far less on the prior emission estimate than do those for the other observing systems, demonstrating the benefit of high sampling density. The results suggest that MethaneSat would be an incredibly useful tool for obtaining detailed methane emission information from oil and gas provinces around the world.

NOx reduction and NO2 emission characteristics in rich-lean combustion of hydrogen

OpenAIRE

Shudo, Toshio; Omori, Kento; Hiyama, Osamu

2008-01-01

Hydrogen is a clean alternative to conventional hydrocarbon fuels, but it is very important to reduce the nitrogen oxides (NOx) emissions generated by hydrogen combustion. The rich-lean combustion or staged combustion is known to reduce NOx emissions from continuous combustion burners such as gas turbines and boilers, and NOx reduction effects have been demonstrated for hydrocarbon fuels. The authors applied rich-lean combustion to a hydrogen gas turbine and showed its NOx reduction effect in...

Direct numerical simulations of ignition of a lean n-heptane/air mixture with temperature and composition inhomogeneities relevant to HCCI and SCCI combustion

KAUST Repository

Luong, Minh Bau; Yu, Gwang Hyeon; Lu, Tianfeng; Chung, Suk-Ho; Yoo, Chun Sang

2015-01-01

The effects of temperature and composition stratifications on the ignition of a lean n-heptane/air mixture at three initial mean temperatures under elevated pressure are investigated using direct numerical simulations (DNSs) with a 58-species

Air quality effects of alternative fuels. Final report

Energy Technology Data Exchange (ETDEWEB)

Guthrie, P.; Ligocki, M.; Looker, R.; Cohen, J.

1997-11-01

To support the Alternative Fuels Utilization Program, a comparison of potential air quality effects of alternative transportation fuels is being performed. This report presents the results of Phase 1 of this program, focusing on reformulated gasoline (RFG), methanol blended with 15 percent gasoline (M85), and compressed natural gas (CNG). The fuels are compared in terms of effects on simulated future concentrations of ozone and mobile source air toxics in a photochemical grid model. The fuel comparisons were carried out for the future year 2020 and assumed complete replacement of gasoline in the projected light-duty gasoline fleet by each of the candidate fuels. The model simulations were carried out for the areas surrounding Los Angeles and Baltimore/DC, and other (non-mobile) sources of atmospheric emissions were projected according to published estimates of economic and population growth, and planned emission control measures specific to each modeling domain. The future-year results are compared to a future-year run with all gasoline vehicle emissions removed. The results of the comparison indicate that the use of M85 is likely to produce similar ozone and air toxics levels as those projected from the use of RFG. Substitution of CNG is projected to produce significantly lower levels of ozone and the mobile source air toxics than those projected for RFG or M85. The relative benefits of CNG substitution are consistent in both modeling domains. The projection methodologies used for the comparison are subject to a large uncertainty, and modeled concentration distributions depend on meteorological conditions. The quantitative comparison of fuel effects is thus likely to be sensitive to alternative assumptions. The consistency of the results for two very different modeling domains, using very different base assumptions, lends credibility to the qualitative differentiation among these fuels. 32 refs., 42 figs., 47 tabs.

GOSAT-2014 methane spectral line list

International Nuclear Information System (INIS)

Nikitin, A.V.; Lyulin, O.M.; Mikhailenko, S.N.; Perevalov, V.I.; Filippov, N.N.; Grigoriev, I.M.; Morino, I.; Yoshida, Y.; Matsunaga, T.

2015-01-01

The updated methane spectral line list GOSAT-2014 for the 5550–6240 cm −1 region with the intensity cutoff of 5×10 –25 cm/molecule at 296 K is presented. The line list is based on the extensive measurements of the methane spectral line parameters performed at different temperatures and pressures of methane without and with buffer gases N 2 , O 2 and air. It contains the following spectral line parameters of about 12150 transitions: line position, line intensity, energy of lower state, air-induced and self-pressure-induced broadening and shift coefficients and temperature exponent of air-broadening coefficient. The accuracy of the line positions and intensities are considerably improved in comparison with the previous version GOSAT-2009. The improvement of the line list is done mainly due to the involving to the line position and intensity retrieval of six new spectra recorded with short path way (8.75 cm). The air-broadening and air-shift coefficients for the J-manifolds of the 2ν 3 (F 2 ) band are refitted using the new more precise values of the line positions and intensities. The line assignment is considerably extended. The lower state J-value was assigned to 6397 lines representing 94.4% of integrated intensity of the considering wavenumber region. The complete assignment was done for 2750 lines. - Highlights: • The upgrade of the GOSAT methane line list in the 5550–6240 cm −1 region is done. • 12,146 experimental methane line positions and intensities are retrieved. • 6376 lower energy levels for methane lines are determined

Properties of plasma flames sustained by microwaves and burning hydrocarbon fuels

International Nuclear Information System (INIS)

Hong, Yong Cheol; Uhm, Han Sup

2006-01-01

Plasma flames made of atmospheric microwave plasma and a fuel-burning flame were presented and their properties were investigated experimentally. The plasma flame generator consists of a fuel injector and a plasma flame exit connected in series to a microwave plasma torch. The plasma flames are sustained by injecting hydrocarbon fuels into a microwave plasma torch in air discharge. The microwave plasma torch in the plasma flame system can burn a hydrocarbon fuel by high-temperature plasma and high atomic oxygen density, decomposing the hydrogen and carbon containing fuel. We present the visual observations of the sustained plasma flames and measure the gas temperature using a thermocouple device in terms of the gas-fuel mixture and flow rate. The plasma flame volume of the hydrocarbon fuel burners was more than approximately 30-50 times that of the torch plasma. While the temperature of the torch plasma flame was only 868 K at a measurement point, that of the diesel microwave plasma flame with the addition of 0.019 lpm diesel and 30 lpm oxygen increased drastically to about 2280 K. Preliminary experiments for methane plasma flame were also carried out, measuring the temperature profiles of flames along the radial and axial directions. Finally, we investigated the influence of the microwave plasma on combustion flame by observing and comparing OH molecular spectra for the methane plasma flame and methane flame only

Porous fuel air mixing enhancing nozzle (PFAMEN)

NARCIS (Netherlands)

Reijnders, J.J.E.; Boot, M.D.; Luijten, C.C.M.; Frijters, P.J.M.; Goey, de L.P.H.

2009-01-01

One of the challenges with conventional diesel engines is the emission of soot. To reduce soot emission whilst maintaining fuel efficiency, an important pathway is to improve the fuel-air mixing process. This can be achieved by creating small droplets in order to enhance evaporation. Furthermore,

Photocatalytic conversion of methane to methanol

Energy Technology Data Exchange (ETDEWEB)

Taylor, C.E.; Noceti, R.P.; D`Este, J.R. [Pittsburgh Energy Technology Center, PA (United States)

1995-12-31

A long-term goal of our research group is the exploration of novel pathways for the direct oxidation of methane to liquid fuels, chemicals, and intermediates. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol is attractive. The products of reaction, methanol and hydrogen, are both commercially desirable, methanol being used as is or converted to a variety of other chemicals, and the hydrogen could be utilized in petroleum and/or chemical manufacturing. Methane is produced as a by-product of coal gasification. Depending upon reactor design and operating conditions, up to 18% of total gasifier product may be methane. In addition, there are vast proven reserves of geologic methane in the world. Unfortunately, a large fraction of these reserves are in regions where there is little local demand for methane and it is not economically feasible to transport it to a market. There is a global research effort under way in academia, industry, and government to find methods to convert methane to useful, more readily transportable and storable materials. Methanol, the initial product of methane oxidation, is a desirable product of conversion because it retains much of the original energy of the methane while satisfying transportation and storage requirements. Investigation of direct conversion of methane to transportation fuels has been an ongoing effort at PETC for over 10 years. One of the current areas of research is the conversion of methane to methanol, under mild conditions, using light, water, and a semiconductor photocatalyst. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol, is attractive. Research in the laboratory is directed toward applying the techniques developed for the photocatalytic splitting of the water and the photochemical conversion of methane.

Pollutant Formation during the Occurrence of Flame Instabilities under Very-Lean Combustion Conditions in a Liquid-Fuel Burner

Directory of Open Access Journals (Sweden)

Maria Grazia De Giorgi

2017-03-01

Full Text Available Recent advances in gas turbine combustor design are aimed at achieving low exhaust emissions, hence modern aircraft jet engines are designed with lean-burn combustion systems. In the present work, we report an experimental study on lean combustion in a liquid fuel burner, operated under a non-premixed (single point injection regime that mimics the combustion in a modern aircraft engine. The flame behavior was investigated in proximity of the blow-out limit by an intensified high rate Charge-Coupled Device (CCD camera equipped with different optical filters to selectively record single species chemiluminescence emissions (e.g., OH*, CH*. Analogous filters were also used in combination with photomultiplier (PMT tubes. Furthermore this work investigates well-mixed lean low NOx combustion where mixing is good and generation of solid carbon particulate emissions should be very low. An analysis of pollutants such as fine particles and gaseous emissions was also performed. Particle number concentrations and size distributions were measured at the exhaust of the combustion chamber by two different particle size measuring instruments: a scanning mobility particle sizer (SMPS and an Electrical Low Pressure Impactor (ELPI. NOx concentration measurements were performed by using a cross-flow modulation chemiluminescence detection system; CO concentration emissions were acquired with a Cross-flow modulation Non-dispersive infrared (NDIR absorption method. All the measurements were completed by diagnostics of the fundamental combustor parameters. The results herein presented show that at very-lean conditions the emissions of both particulate matter and CO was found to increase most likely due to the occurrence of flame instabilities while the NOx were observed to reduce.

Effects of hydrogen addition and nitrogen dilution on the laminar flame characteristics of premixed methane-air flames

Energy Technology Data Exchange (ETDEWEB)

Tahtouh, T.; Halter, F.; Mounaim-Rousselle, C. [Institut PRISME, Universite d' Orleans, 8 rue Leonard de Vinci-45072, Orleans Cedex 2 (France); Samson, E. [PSA Peugeot Citroen (France)

2009-10-15

The effect of hydrogen addition and nitrogen dilution on laminar flame characteristics was investigated. The spherical expanding flame technique, in a constant volume bomb, was employed to extract laminar flame characteristics. The mole fraction of hydrogen in the methane-hydrogen mixture was varied from 0 to 1 and the mole fraction of nitrogen in the total mixture (methane-hydrogen-air-diluent) from 0 to 0.35. Measurements were performed at an initial pressure of 0.1 MPa and an initial temperature of 300 K. The mixtures investigated were under stoichiometric conditions. Based on experimental measurements, a new correlation for calculating the laminar burning velocity of methane-hydrogen-air-nitrogen mixtures is proposed. The laminar burning velocity was found to increase linearly with hydrogen mass fraction for all dilution ratios while the burned gas Markstein length decreases with the increase in hydrogen amount in the mixture except for high hydrogen mole fractions (>0.6). Nitrogen dilution has a nonlinear reducing effect on the laminar burning velocity and an increasing effect on the burned gas Markstein length. The experimental results and the proposed correlation obtained are in good agreement with literature values. (author)

Storage of LWR spent fuel in air. Volume 3, Results from exposure of spent fuel to fluorine-contaminated air

Energy Technology Data Exchange (ETDEWEB)

Cunningham, M.E.; Thomas, L.E.

1995-06-01

The Behavior of Spent Fuel in Storage (BSFS) Project has conducted research to develop data on spent nuclear fuel (irradiated U0{sub 2}) that could be used to support design, licensing, and operation of dry storage installations. Test Series B conducted by the BSFS Project was designed as a long-term study of the oxidation of spent fuel exposed to air. It was discovered after the exposures were completed in September 1990 that the test specimens had been exposed to an atmosphere of bottled air contaminated with an unknown quantity of fluorine. This exposure resulted in the test specimens reacting with both the oxygen and the fluorine in the oven atmospheres. The apparent source of the fluorine was gamma radiation-induced chemical decomposition of the fluoro-elastomer gaskets used to seal the oven doors. This chemical decomposition apparently released hydrofluoric acid (HF) vapor into the oven atmospheres. Because the Test Series B specimens were exposed to a fluorine-contaminated oven atmosphere and reacted with the fluorine, it is recommended that the Test Series B data not be used to develop time-temperature limits for exposure of spent nuclear fuel to air. This report has been prepared to document Test Series B and present the collected data and observations.

Storage of LWR spent fuel in air. Volume 3, Results from exposure of spent fuel to fluorine-contaminated air

International Nuclear Information System (INIS)

Cunningham, M.E.; Thomas, L.E.

1995-06-01

The Behavior of Spent Fuel in Storage (BSFS) Project has conducted research to develop data on spent nuclear fuel (irradiated U0 2 ) that could be used to support design, licensing, and operation of dry storage installations. Test Series B conducted by the BSFS Project was designed as a long-term study of the oxidation of spent fuel exposed to air. It was discovered after the exposures were completed in September 1990 that the test specimens had been exposed to an atmosphere of bottled air contaminated with an unknown quantity of fluorine. This exposure resulted in the test specimens reacting with both the oxygen and the fluorine in the oven atmospheres. The apparent source of the fluorine was gamma radiation-induced chemical decomposition of the fluoro-elastomer gaskets used to seal the oven doors. This chemical decomposition apparently released hydrofluoric acid (HF) vapor into the oven atmospheres. Because the Test Series B specimens were exposed to a fluorine-contaminated oven atmosphere and reacted with the fluorine, it is recommended that the Test Series B data not be used to develop time-temperature limits for exposure of spent nuclear fuel to air. This report has been prepared to document Test Series B and present the collected data and observations

Methane Steam Reforming over an Ni-YSZ Solid Oxide Fuel Cell Anode in Stack Configuration

Directory of Open Access Journals (Sweden)

D. Mogensen

2014-01-01

Full Text Available The kinetics of catalytic steam reforming of methane over an Ni-YSZ anode of a solid oxide fuel cell (SOFC have been investigated with the cell placed in a stack configuration. In order to decrease the degree of conversion, a single cell stack with reduced area was used. Measurements were performed in the temperature range 600–800°C and the partial pressures of all reactants and products were varied. The obtained rates could be well fitted with a power law expression (r ∝PCH40.7. A simple model is presented which is capable of predicting the methane conversion in a stack configuration from intrinsic kinetics of the anode support material. The predictions are compared with the stack measurements presented here, and good agreement is observed.

A DFT study of Ru, Rh, Pd, Os, Ir, and Pt clusters as catalysts for methane dissociation in a direct methane fuel cell (DMHFC)

Energy Technology Data Exchange (ETDEWEB)

Psofogiannakisa, G. [Ottawa Univ., Ottawa, ON (Canada). Dept. of Chemical Engineering; Ottawa, Univ., Ottawa, ON (Canada). Centre for Catalysis Research and Innovation; St-Amant, A. [Ottawa Univ., Ottawa, ON (Canada). Dept. of Chemistry; Ternan, M. [Ottawa Univ., Ottawa, ON (Canada). Centre for Catalysis Research and Innovation; EnPross Inc., Ottawa, ON (Canada)

2008-07-01

The rate limiting step in a direct methane hydrocarbon fuel cell (DMHFC) is the dissociative chemisorption of methane. Quantum mechanical computations were used to examine the terrace, kink, and step sites on 6 different clusters of group 8 transition metals, notably Ru, Rh, Pd, Os, Ir, and Pt. The computations involved the anodic reaction of a DMHFC with a polymer electrolyte that operates at atmospheric pressure and temperatures higher than 120 degrees C. The interaction between molecular fragments and a surface (Pt) were described and density functional theory (DFT) calculations were performed using Guassian software. The geometries of 5 different platinum clusters were examined along with their electronic energy barriers. The biggest contribution to the stabilization energy came from the overlap between the sigma bond in methane and unoccupied sd hybrid orbitals in the Pt bonding atom. The study showed that when relaxation was allowed, the displacement of the bonding metal atom was 0.36 to 0.52 A. The electronic energy barrier often increased as d-orbital occupancy increased. For the kink surface sites, the energy barriers were considerably smaller for the 5d transition metals than for the 4d transition metals. 5 refs., 1 tab.

A comparison between EGR and lean-burn strategies employed in a natural gas SI engine using a two-zone combustion model

Energy Technology Data Exchange (ETDEWEB)

Ibrahim, Amr; Bari, Saiful [Sustainable Energy Centre, School of Advanced Manufacturing and Mechanical Engineering, Univ. of South Australia, Mawson Lakes SA 5095 (Australia)

2009-12-15

Exhaust gas recirculation (EGR) strategy has been recently employed in natural gas SI engines as an alternative to lean burn technique in order to satisfy the increasingly stringent emission standards. However, the effect of EGR on some of engine performance parameters compared to lean burn is not yet quite certain. In the current study, the effect of both EGR and lean burn on natural gas SI engine performance was compared at similar operating conditions. This was achieved numerically by developing a computer simulation of the four-stroke spark-ignition natural gas engine. A two-zone combustion model was developed to simulate the in-cylinder conditions during combustion. A kinetic model based on the extended Zeldovich mechanism was also developed in order to predict NO emission. The combustion model was validated using experimental data and a good agreement between the results was found. It was demonstrated that adding EGR to the stoichiometric inlet charge at constant inlet pressure of 130 kPa decreased power more rapidly than excess air; however, the power loss was recovered by increasing the inlet pressure from 130 kPa at zero dilution to 150 kPa at 20% EGR dilution. The engine fuel consumption increased by 10% when 20% EGR dilution was added at inlet pressure of 150 kPa compared to using 20% air dilution at 130 kPa. However, it was found that EGR dilution strategy is capable of producing extremely lower NO emission than lean burn technique. NO emission was reduced by about 70% when the inlet charge was diluted at a rate of 20% using EGR instead of excess air. (author)

A comparison between EGR and lean-burn strategies employed in a natural gas SI engine using a two-zone combustion model

International Nuclear Information System (INIS)

Ibrahim, Amr; Bari, Saiful

2009-01-01

Exhaust gas recirculation (EGR) strategy has been recently employed in natural gas SI engines as an alternative to lean burn technique in order to satisfy the increasingly stringent emission standards. However, the effect of EGR on some of engine performance parameters compared to lean burn is not yet quite certain. In the current study, the effect of both EGR and lean burn on natural gas SI engine performance was compared at similar operating conditions. This was achieved numerically by developing a computer simulation of the four-stroke spark-ignition natural gas engine. A two-zone combustion model was developed to simulate the in-cylinder conditions during combustion. A kinetic model based on the extended Zeldovich mechanism was also developed in order to predict NO emission. The combustion model was validated using experimental data and a good agreement between the results was found. It was demonstrated that adding EGR to the stoichiometric inlet charge at constant inlet pressure of 130 kPa decreased power more rapidly than excess air; however, the power loss was recovered by increasing the inlet pressure from 130 kPa at zero dilution to 150 kPa at 20% EGR dilution. The engine fuel consumption increased by 10% when 20% EGR dilution was added at inlet pressure of 150 kPa compared to using 20% air dilution at 130 kPa. However, it was found that EGR dilution strategy is capable of producing extremely lower NO emission than lean burn technique. NO emission was reduced by about 70% when the inlet charge was diluted at a rate of 20% using EGR instead of excess air.

Experimental and numerical study of the accuracy of flame-speed measurements for methane/air combustion in a slot burner

Energy Technology Data Exchange (ETDEWEB)

Selle, L.; Ferret, B. [Universite de Toulouse, INPT, UPS, IMFT, Institut de Mecanique des Fluides de Toulouse (France); CNRS, IMFT, Toulouse (France); Poinsot, T. [Universite de Toulouse, INPT, UPS, IMFT, Institut de Mecanique des Fluides de Toulouse (France); CNRS, IMFT, Toulouse (France); CERFACS, Toulouse (France)

2011-01-15

Measuring the velocities of premixed laminar flames with precision remains a controversial issue in the combustion community. This paper studies the accuracy of such measurements in two-dimensional slot burners and shows that while methane/air flame speeds can be measured with reasonable accuracy, the method may lack precision for other mixtures such as hydrogen/air. Curvature at the flame tip, strain on the flame sides and local quenching at the flame base can modify local flame speeds and require corrections which are studied using two-dimensional DNS. Numerical simulations also provide stretch, displacement and consumption flame speeds along the flame front. For methane/air flames, DNS show that the local stretch remains small so that the local consumption speed is very close to the unstretched premixed flame speed. The only correction needed to correctly predict flame speeds in this case is due to the finite aspect ratio of the slot used to inject the premixed gases which induces a flow acceleration in the measurement region (this correction can be evaluated from velocity measurement in the slot section or from an analytical solution). The method is applied to methane/air flames with and without water addition and results are compared to experimental data found in the literature. The paper then discusses the limitations of the slot-burner method to measure flame speeds for other mixtures and shows that it is not well adapted to mixtures with a Lewis number far from unity, such as hydrogen/air flames. (author)

Relations between Air-Fuel Ratio and Dynamic Performance of Small Race Cars

OpenAIRE

位田, 晴良; Ida, Haruyoshi; 漁, 佑一郎; Sunadori, Yuichiro; 牧田, 俊太郎; Makita, Syuntaro; 宮﨑, 真央; Miyazaki, Manaka; 磯松, 弥司; Isomatsu, Yatsuka

2017-01-01

'It goes without saying that engine output power characteristics greatly affect the dynamic performance of the race car. One of the methods of changing the output power of the engine is to adjust the set amount of fuel supply. This method changes the air-fuel ratio of the air fuel mixture supplied to the engine. In this study, a slalom test run of a small race car was used to examine dynamic performance with attention to the air-fuel ratio changed by adjusting the set amount of fuel supply. T...

Flame holding tolerant fuel and air premixer for a gas turbine combustor

Science.gov (United States)

York, William David; Johnson, Thomas Edward; Ziminsky, Willy Steve

2012-11-20

A fuel nozzle with active cooling is provided. It includes an outer peripheral wall, a nozzle center body concentrically disposed within the outer wall in a fuel and air pre-mixture. The fuel and air pre-mixture includes an air inlet, a fuel inlet and a premixing passage defined between the outer wall in the center body. A gas fuel flow passage is provided. A first cooling passage is included within the center body in a second cooling passage is defined between the center body and the outer wall.

Comparison between Hydrogen, Methane and Ethylene Fuels in a 3-D Scramjet at Mach 8

Science.gov (United States)

2016-06-24

scramjet using a cavity based flame holder in the T4 shock tunnel at The University of Queensland, as well as a companion fundamental CFD study. The...shock tunnel. 15. SUBJECT TERMS Airbreathing Engines, Hypersonics , Propulsion, AOARD 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18...Report Comparison between hydrogen, methane and ethylene fuels in a 3-D Scramjet at Mach 8 Professor Michael K. Smart Chair of Hypersonic Propulsion

Effect of pressure on the transfer functions of premixed methane and propane swirl flames

KAUST Repository

Di Sabatino, Francesco

2018-04-24

This paper reports on the effect of pressure on the response of methane–air and propane–air swirl flames to acoustic excitation of the flow. These effects are analyzed on the basis of the flame transfer function (FTF) formalism, experimentally determined from velocity and global OH* chemiluminescence measurements at pressures up to 5 bar. In parallel, phase-locked images of OH* chemiluminescence are collected and analyzed in order to determine the associated flame dynamics. Flame transfer functions and visual flame dynamics at atmospheric pressure are found to be similar to previous studies with comparable experimental conditions. Regardless of pressure, propane flames exhibit a much larger FTF gain than methane flames. For both fuels, the effect of pressure primarily is to modify the gain response at the local maximum of the FTF, at a Strouhal number around 0.5 (176 Hz). For methane flames, this gain maximum increases monotonically with pressure, while for propane flames it increases from 1 to 3 bar and decreases from 3 to 5 bar. At this frequency and regardless of pressure, the flame motion is driven by flame vortex roll-up, suggesting that pressure affects the FTF by modifying the interaction of the flame with the vortex detached from the injector rim during a forcing period. The complex heat transfer, fluid dynamics, and combustion coupling in this configuration does not allow keeping the vortex properties constant when pressure is increased. However, the different trends of the FTF gain observed for methane and propane fuels with increasing pressure imply that intrinsic flame properties and fuel chemistry, and their variation with pressure, play an important role in controlling the response of these flames to acoustic forcing.

Methane storage in porous activated carbons

NARCIS (Netherlands)

András Perl; prof. dr. Wim van Gemert

2014-01-01

Locally produced methane, - either as biomethane or power-to-gas product, has to be stored to provide a reliable gas source for the fluctuating demand of any local gas distribution network. Additionally, methane is a prominent transportation fuel but its suitability for vehicular application depends

Chemiluminescence-based multivariate sensing of local equivalence ratios in premixed atmospheric methane-air flames

Energy Technology Data Exchange (ETDEWEB)

Tripathi, Markandey M.; Krishnan, Sundar R.; Srinivasan, Kalyan K.; Yueh, Fang-Yu; Singh, Jagdish P.

2011-09-07

Chemiluminescence emissions from OH*, CH*, C2, and CO2 formed within the reaction zone of premixed flames depend upon the fuel-air equivalence ratio in the burning mixture. In the present paper, a new partial least square regression (PLS-R) based multivariate sensing methodology is investigated and compared with an OH*/CH* intensity ratio-based calibration model for sensing equivalence ratio in atmospheric methane-air premixed flames. Five replications of spectral data at nine different equivalence ratios ranging from 0.73 to 1.48 were used in the calibration of both models. During model development, the PLS-R model was initially validated with the calibration data set using the leave-one-out cross validation technique. Since the PLS-R model used the entire raw spectral intensities, it did not need the nonlinear background subtraction of CO2 emission that is required for typical OH*/CH* intensity ratio calibrations. An unbiased spectral data set (not used in the PLS-R model development), for 28 different equivalence ratio conditions ranging from 0.71 to 1.67, was used to predict equivalence ratios using the PLS-R and the intensity ratio calibration models. It was found that the equivalence ratios predicted with the PLS-R based multivariate calibration model matched the experimentally measured equivalence ratios within 7%; whereas, the OH*/CH* intensity ratio calibration grossly underpredicted equivalence ratios in comparison to measured equivalence ratios, especially under rich conditions ( > 1.2). The practical implications of the chemiluminescence-based multivariate equivalence ratio sensing methodology are also discussed.

Model predictive control of a lean-burn gasoline engine coupled with a passive selective catalytic reduction system

Energy Technology Data Exchange (ETDEWEB)

Chen, Pingen [Tennessee Technological University (TTU); Lin, Qinghua [Tennessee Technological University (TTU); Prikhodko, Vitaly Y. [ORNL

2017-10-01

Lean-burn gasoline engines have demonstrated 10–20% engine efficiency gain over stoichiometric engines and are widely considered as a promising technology for meeting the 54.5 miles-per-gallon (mpg) Corporate Average Fuel Economy standard by 2025. Nevertheless, NOx emissions control for lean-burn gasoline for meeting the stringent EPA Tier 3 emission standards has been one of the main challenges towards the commercialization of highly-efficient lean-burn gasoline engines in the United States. Passive selective catalytic reduction (SCR) systems, which consist of a three-way catalyst and SCR, have demonstrated great potentials of effectively reducing NOx emissions for lean gasoline engines but may cause significant fuel penalty due to ammonia generation via rich engine combustion. The purpose of this study is to develop a model-predictive control (MPC) scheme for a lean-burn gasoline engine coupled with a passive SCR system to minimize the fuel penalty associated with passive SCR operation while satisfying stringent NOx and NH3 emissions requirements. Simulation results demonstrate that the MPC-based control can reduce the fuel penalty by 47.7% in a simulated US06 cycle and 32.0% in a simulated UDDS cycle, compared to the baseline control, while achieving over 96% deNOx efficiency and less than 15 ppm tailpipe ammonia slip. The proposed MPC control can potentially enable high engine efficiency gain for highly-efficient lean-burn gasoline engine while meeting the stringent EPA Tier 3 emission standards.

A robust NiO-Sm0.2Ce0.8O1.9 anode for direct-methane solid oxide fuel cell

KAUST Repository

Tian, Dong

2015-07-02

In order to directly use methane without a reforming process, NiO-Sm0.2Ce0.8O1.9 (NiO-SDC) nanocomposite anode are successfully synthesized via a one-pot, surfactant-assisted co-assembly approach for direct-methane solid oxide fuel cells. Both NiO with cubic phase and SDC with fluorite phase are obtained at 550 °C. Both NiO nanoparticles and SDC nanoparticles are highly monodispersed in size with nearly spherical shapes. Based on the as-synthesized NiO-SDC, two kinds of single cells with different micro/macro-porous structure are successfully fabricated. As a result, the cell performance was improved by 40%-45% with the new double-pore NiO-SDC anode relative to the cell performance with the conventional NiO-SDC anode due to a wider triple-phase-boundary (TPB) area. In addition, no significant degradation of the cell performance was observed after 60 hours, which means an increasing of long term stability. Therefore, the as-synthesized NiO-SDC nanocomposite is a promising anode for direct-methane solid oxide fuel cells.

Ion measurements in premixed methane-oxygen flames

KAUST Repository

Alquaity, Awad

2014-07-25

Ions are formed as a result of chemi-ionization processes in combustion systems. Recently, there has been an increasing interest in understanding flame ion chemistry due to the possible application of external electric fields to reduce emissions and improve combustion efficiency by active control of combustion process. In order to predict the effect of external electric fields on combustion plasma, it is critical to gain a good understanding of the flame ion chemistry. In this work, a Molecular Beam Mass Spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane-oxygen-argon burner-stabilized flames. Lean, stoichiometric and rich flames at atmospheric pressure are used to study the dependence of ion chemistry on equivalence ratio of premixed flames. The relative ion concentration profiles are compared qualitatively with previous methane-oxygen studies and show good agreement. The relative ion concentration data obtained in the present study can be used to validate and improve ion chemistry models for methane-oxygen flames.

Modeling of the flame propagation in coal-dust- methane air mixture in an enclosed sphere volume

International Nuclear Information System (INIS)

Krainov, A Yu; Moiseeva, K M

2016-01-01

The results of the numerical simulation of the flame front propagation in coal-dust- methane-air mixture in an enclosed volume with the ignition source in the center of the volume are presented. The mathematical model is based on a dual-velocity two-phase model of the reacting gas-dispersion medium. The system of equations includes the mass-conversation equation, the impulse-conversation equation, the total energy-conversation equation of the gas and particles taking into account the thermal conductivity and chemical reactions in the gas and on the particle surface, mass-conversation equation of the mixture gas components considering the diffusion and the burn-out and the particle burn-out equation. The influence of the coal particle mass on the pressure in the volume after the mixture burn out and on the burn-out time has been investigated. It has been shown that the burning rate of the coal-dust methane air mixtures depends on the coal particle size. (paper)

Lean Manufacturing measurement: The relationships between Lean activities and Lean metrics

Directory of Open Access Journals (Sweden)

Diego Fernando Manotas Duque

2007-01-01

Full Text Available Medición en Lean Manufacturing: Relaciones entre Actividades Lean y Métricas Lean Lean Manufacturing fue desarrollada por Toyota para satisfacer sus necesidades específicas en un mercado restringido y en tiempos de estrechez económica. Estos conceptos han sido estudiados y se ha comprobado su aplicabilidad en una amplia variedad de industrias. El objetivo de este artículo es el de integrar un conjunto de métricas que han sido propuestas por diferentes autores, de tal manera que sean consistentes con las etapas y elementos de implementaciones de Lean Manufacturing. Para lograrlo se presentan dos marcos de referencia para implementaciones Lean y los principales factores de éxito se utilizan como base para proponer métricas que identifiquen el avance en estos factores. Posteriormente se propone una tabla que cruza el impacto de las “Actividades Lean” sobre las métricas, postulando que muchos de los supuestos a priori sobre estos impactos deberían ser precisos. Finalmente se proponen algunas ideas para proyectos de investigación hacia el futuro y posibles extensiones de las aplicaciones propuestas aquí.

Renewable methane from anaerobic digestion of biomass

International Nuclear Information System (INIS)

Chynoweth, D.P.; Owens, J.M.

2001-01-01

Production of methane via anaerobic digestion of energy crops and organic wastes would benefit society by providing a clean fuel from renewable feedstocks. This would replace fossil fuel-derived energy and reduce environmental impacts including global warming and acid rain. Although biomass energy is more costly than fossil fuel-derived energy, trends to limit carbon dioxide and other emissions through emission regulations, carbon taxes, and subsidies of biomass energy would make it cost competitive. Methane derived from anaerobic digestion is competitive in efficiencies and costs to other biomass energy forms including heat, synthesis gases, and ethanol. (author)

Methane leakage in natural gas operations

International Nuclear Information System (INIS)

Jennervik, A.

1992-01-01

The world gas industry is efficient in conservation of natural gas within its systems. As the influence of methane as an infra-red absorbent gas has been more widely recognized, the considerations of methane's greenhouse effect has become vitally important to gas companies around the world. The industry is universally environmentally conscious. natural gas transmission and distribution companies want to maintain their image as suppliers of clean fuel. Further reductions in methane leakage --- particularly in older distribution systems --- can, should and will be pursued. Unfortunately, there has been little exchange of views on methane leakages between commentators on environmental matters and gas companies and organizations. There is absolutely no need for the industry to avoid the issue of greenhouse gases. Without industry involvement, the environmental debate concerning fossil fuels could lead to selective interpretation of scientific views and available evidence. Companies and authorities would be presented with confusing, contradictory evidence on which to base policy approaches and regulations

Liftoff and blowoff of a diffusion flame between parallel streams of fuel and air

Energy Technology Data Exchange (ETDEWEB)

Fernandez-Tarrazo, Eduardo [I.N.T.A. Area de Propulsion-Edificio R02, Ctra. Ajalvir, km 4, 28850 Torrejon de Ardoz, Madrid (Spain); Vera, Marcos [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Linan, Amable [Departamento de Motopropulsion y Termofluidodinamica, Universidad Politecnica de Madrid, Pza. Cardenal Cisneros 3, 28040 Madrid (Spain)

2006-01-01

A numerical analysis is presented to describe the liftoff and blowoff of a diffusion flame in the mixing layer between two parallel streams of fuel (mainly methane diluted with nitrogen) and air emerging from porous walls. The analysis, which takes into account the effects of thermal expansion, assumes a one-step overall Arrhenius reaction, where the activation energy E is allowed to vary to reproduce the variations of the planar flame propagation velocity with the equivalence ratio. First, we describe the steady flame-front structure when stabilized close to the porous wall (attached flame regime). Then, we analyze the case where the flame front is located far away from the porous wall, at a distance x{sub f}' such that, upstream of the flame front, the mixing layer has a self-similar structure (lifted flame regime). For steady lifted flames, the results, given here in the case when the fuel and air streams are injected with the same velocity, relate U{sub f}'/S{sub L}, the front velocity (relative to the upstream flow) measured with the planar stoichiometric flame velocity, with the Damkohler number D{sub m}=({delta}{sub m}/{delta}{sub L}){sup 2}, based on the thickness, {delta}{sub m}, of the nonreacting mixing layer at the flame-front position and the laminar flame thickness, {delta}{sub L}. For large values of D{sub m}, the results, presented here for a wide range of dilutions of the fuel stream, provide values of the front propagation velocity that are in good agreement with previous experimental results, yielding well-defined conditions for blowoff. The calculated flame-front velocity can also be used to describe the transient flame-front dynamics after ignition by an external energy source.

Is methane a new therapeutic gas?

Directory of Open Access Journals (Sweden)

Liu Wenwu

2012-09-01

Full Text Available Abstract Background Methane is an attractive fuel. Biologically, methanogens in the colon can use carbon dioxide and hydrogen to produce methane as a by-product. It was previously considered that methane is not utilized by humans. However, in a recent study, results demonstrated that methane could exert anti-inflammatory effects in a dog small intestinal ischemia-reperfusion model. Point of view Actually, the bioactivity of methane has been investigated in gastrointestinal diseases, but the exact mechanism underlying the anti-inflammatory effects is required to be further elucidated. Methane can cross the membrane and is easy to collect due to its abundance in natural gas. Although methane is flammable, saline rich in methane can be prepared for clinical use. These seem to be good news in application of methane as a therapeutic gas. Conclusion Several problems should be resolved before its wide application in clinical practice.

Numerical Study on the Performance Characteristics of Hydrogen Fueled Port Injection Internal Combustion Engine

OpenAIRE

Rosli A. Bakar; Mohammed K. Mohammed; M. M. Rahman

2009-01-01

This study was focused on the engine performance of single cylinder hydrogen fueled port injection internal combustion engine. GT-Power was utilized to develop the model for port injection engine. One dimensional gas dynamics was represented the flow and heat transfer in the components of the engine model. The governing equations were introduced first, followed by the performance parameters and model description. Air-fuel ratio was varied from stoichiometric limit to a lean limit and the rota...

Multi-stage combustion using nitrogen-enriched air

Science.gov (United States)

Fischer, Larry E.; Anderson, Brian L.

2004-09-14

Multi-stage combustion technology combined with nitrogen-enriched air technology for controlling the combustion temperature and products to extend the maintenance and lifetime cycles of materials in contact with combustion products and to reduce pollutants while maintaining relatively high combustion and thermal cycle efficiencies. The first stage of combustion operates fuel rich where most of the heat of combustion is released by burning it with nitrogen-enriched air. Part of the energy in the combustion gases is used to perform work or to provide heat. The cooled combustion gases are reheated by additional stages of combustion until the last stage is at or near stoichiometric conditions. Additional energy is extracted from each stage to result in relatively high thermal cycle efficiency. The air is enriched with nitrogen using air separation technologies such as diffusion, permeable membrane, absorption, and cryogenics. The combustion method is applicable to many types of combustion equipment, including: boilers, burners, turbines, internal combustion engines, and many types of fuel including hydrogen and carbon-based fuels including methane and coal.

Storage of LWR spent fuel in air: Volume 1: Design and operation of a spent fuel oxidation test facility

International Nuclear Information System (INIS)

Thornhill, C.K.; Campbell, T.K.; Thornhill, R.E.

1988-12-01

This report describes the design and operation and technical accomplishments of a spent-fuel oxidation test facility at the Pacific Northwest Laboratory. The objective of the experiments conducted in this facility was to develop a data base for determining spent-fuel dry storage temperature limits by characterizing the oxidation behavior of light-water reactor (LWR) spent fuels in air. These data are needed to support licensing of dry storage in air as an alternative to spent-fuel storage in water pools. They are to be used to develop and validate predictive models of spent-fuel behavior during dry air storage in an Independent Spent Fuel Storage Installation (ISFSI). The present licensed alternative to pool storage of spent fuel is dry storage in an inert gas environment, which is called inerted dry storage (IDS). Licensed air storage, however, would not require monitoring for maintenance of an inert-gas environment (which IDS requires) but does require the development of allowable temperature limits below which UO 2 oxidation in breached fuel rods would not become a problem. Scoping tests at PNL with nonirradiated UO 2 pellets and spent-fuel fragment specimens identified the need for a statistically designed test matrix with test temperatures bounding anticipated maximum acceptable air-storage temperatures. This facility was designed and operated to satisfy that need. 7 refs

Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials.

Science.gov (United States)

Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Hoefman, Sven; De Vos, Paul; Boeckx, Pascal; Boon, Nico

2014-04-01

Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (~20 % (v/v)) and low (~100 ppmv) methane mixing ratios. Methylocystis parvus in autoclaved aerated concrete (AAC) exhibited the highest methane removal rate at high (28.5 ± 3.8 μg CH₄ g⁻¹ building material h⁻¹) and low (1.7 ± 0.4 μg CH₄ g⁻¹ building material h⁻¹) methane mixing ratio. Due to the higher volume of pores with diameter >5 μm compared to other materials tested, AAC was able to adsorb more bacteria which might explain for the higher methane removal observed. The total methane and carbon dioxide-carbon in the headspace was decreased for 65.2 ± 10.9 % when M. parvus in Ytong was incubated for 100 h. This study showed that immobilized MOB on building materials could be used to remove methane from the air and also act as carbon sink.

Air fuel ratio detector corrector for combustion engines using adaptive neurofuzzy networks

Directory of Open Access Journals (Sweden)

Nidhi Arora

2013-07-01

Full Text Available A perfect mix of the air and fuel in internal combustion engines is desirable for proper combustion of fuel with air. The vehicles running on road emit harmful gases due to improper combustion. This problem is severe in heavy vehicles like locomotive engines. To overcome this problem, generally an operator opens or closes the valve of fuel injection pump of locomotive engines to control amount of air going inside the combustion chamber, which requires constant monitoring. A model is proposed in this paper to alleviate combustion process. The method involves recording the time-varying flow of fuel components in combustion chamber. A Fuzzy Neural Network is trained for around 40 fuels to ascertain the required amount of air to form a standard mix to produce non-harmful gases and about 12 fuels are used for testing the network’s performance. The network then adaptively determines the additional/subtractive amount of air required for proper combustion. Mean square error calculation ensures the effectiveness of the network’s performance.

Analysis of energy efficiency of methane and hydrogen-methane blends in a PFI/DI SI research engine

International Nuclear Information System (INIS)

Catapano, F.; Di Iorio, S.; Sementa, P.; Vaglieco, B.M.

2016-01-01

In the last years, even more attention was paid to the alternative fuels that allow both reducing the fossil fuel consumption and the pollutant emissions. Gaseous fuels like methane and hydrogen are the most interesting in terms of engine application. This paper reports a comparison between methane and different methane/hydrogen mixtures in a single-cylinder Port Fuel/Direct Injection spark ignition (PFI/DI SI) engine operating under steady state conditions. It is representative of the gasoline engine for automotive application. Engine performance and exhaust emissions were evaluated. Moreover, 2D-digital cycle resolved imaging was performed with high spatial and temporal resolution in the combustion chamber. In particular, it allows characterizing the combustion by means of the flame propagation in terms of mean radius and velocity. Moreover, the interaction of turbulence with the local flame was evaluated. For both the engine configurations, it was observed that the addition of hydrogen results in a more efficient combustion, even though the engine configuration plays an important role. In PFI mode, the lower density of hydrogen causes a lower energy input. In DI mode, instead, the larger hydrogen diffusivity counteracts the charge stratification especially for larger hydrogen content. - Highlights: • The effect of hydrogen on methane combustion was investigated in an optical PFI/DI SI engine. • The effect of hydrogen addition for PFI and DI configurations was evaluated on the same engine. • The flame front propagation was characterized by means of 2-D digital imaging.

Industrial energy conservation by methane fermentation

Energy Technology Data Exchange (ETDEWEB)

Wise, D L

1981-11-01

An engineering study was conducted to evalutate the possibility of making an entire dairy cooperative self-sufficient by methane fermentation of the whey permeate from the cheese plant and the dairy cattle manure from the dairy farms to fuel gas. A cooperative consisting of 284 dairy farms and one central cheese plant producing 9.5 Gg of cheese annually was used as the basis for evaluation. The feasibility was evaluated at four practical levels of technology. Preliminary economic analysis revealed that the cost of methane was competitive with current prices for purchased fuel. (Refs. 29).

Measurements of acetylene in air extracted from polar ice cores

Science.gov (United States)

Nicewonger, M. R.; Aydin, M.; Montzka, S. A.; Saltzman, E. S.

2016-12-01

Acetylene (ethyne) is a non-methane hydrocarbon emitted during combustion of fossil fuels, biofuels, and biomass. The major atmospheric loss pathway of acetylene is oxidation by hydroxyl radical with a lifetime estimated at roughly two weeks. The mean annual acetylene levels over Greenland and Antarctica are 250 ppt and 20 ppt, respectively. Firn air measurements suggest atmospheric acetylene is preserved unaltered in polar snow and firn. Atmospheric reconstructions based on firn air measurements indicate acetylene levels rose significantly during the twentieth century, peaked near 1980, then declined to modern day levels. This historical trend is similar to that of other fossil fuel-derived non-methane hydrocarbons. In the preindustrial atmosphere, acetylene levels should primarily reflect emissions from biomass burning. In this study, we present the first measurements of acetylene in preindustrial air extracted from polar ice cores. Air from fluid and dry-drilled ice cores from Summit, Greenland and WAIS-Divide Antarctica is extracted using a wet-extraction technique. The ice core air is analyzed using gas chromatography and high-resolution mass spectrometry. Between 1400 to 1800 C.E., acetylene levels over Greenland and Antarctica varied between roughly 70-120 ppt and 10-30 ppt, respectively. The preindustrial Greenland acetylene levels are significantly lower than modern levels, reflecting the importance of northern hemisphere fossil fuel sources today. The preindustrial Antarctic acetylene levels are comparable to modern day levels, indicating similar emissions in the preindustrial atmosphere, likely from biomass burning. The implications of the preindustrial atmospheric acetylene records from both hemispheres will be discussed.

A phenomenological model of two-phase (air/fuel droplet developing and breakup

Directory of Open Access Journals (Sweden)

Pavlović Radomir R.

2013-01-01

Full Text Available Effervescent atomization namely the air-filled liquid atomization comprehends certain complex two-phase phenomenon that are difficult to be modeled. Just a few researchers have found the mathematical expressions for description of the complex atomization model of the two-phase mixture air/diesel fuel. In the following review, developing model of twophase (air/fuel droplet of Cummins spray pump-injector is shown. The assumption of the same diameters of the droplet and the opening of the atomizer is made, while the air/fuel mass ratio inside the droplet varies.

The Effect of Fuel Mass Fraction on the Combustion and Fluid Flow in a Sulfur Recovery Unit Thermal Reactor

Directory of Open Access Journals (Sweden)

Chun-Lang Yeh

2016-11-01

Full Text Available Sulfur recovery unit (SRU thermal reactors are negatively affected by high temperature operation. In this paper, the effect of the fuel mass fraction on the combustion and fluid flow in a SRU thermal reactor is investigated numerically. Practical operating conditions for a petrochemical corporation in Taiwan are used as the design conditions for the discussion. The simulation results show that the present design condition is a fuel-rich (or air-lean condition and gives acceptable sulfur recovery, hydrogen sulfide (H2S destruction, sulfur dioxide (SO2 emissions and thermal reactor temperature for an oxygen-normal operation. However, for an oxygen-rich operation, the local maximum temperature exceeds the suggested maximum service temperature, although the average temperature is acceptable. The high temperature region must be inspected very carefully during the annual maintenance period if there are oxygen-rich operations. If the fuel mass fraction to the zone ahead of the choke ring (zone 1 is 0.0625 or 0.125, the average temperature in the zone behind the choke ring (zone 2 is higher than the zone 1 average temperature, which can damage the downstream heat exchanger tubes. If the zone 1 fuel mass fraction is reduced to ensure a lower zone 1 temperature, the temperature in zone 2 and the heat exchanger section must be monitored closely and the zone 2 wall and heat exchanger tubes must be inspected very carefully during the annual maintenance period. To determine a suitable fuel mass fraction for operation, a detailed numerical simulation should be performed first to find the stoichiometric fuel mass fraction which produces the most complete combustion and the highest temperature. This stoichiometric fuel mass fraction should be avoided because the high temperature could damage the zone 1 corner or the choke ring. A higher fuel mass fraction (i.e., fuel-rich or air-lean condition is more suitable because it can avoid deteriorations of both zone 1

Vacuum Exhaust Process in Pilot-Scale Vacuum Pressure Swing Adsorption for Coal Mine Ventilation Air Methane Enrichment

Directory of Open Access Journals (Sweden)

Xiong Yang

2018-04-01

Full Text Available Recovery and treatment of methane from coal mine ventilation air methane (VAM with cost-effective technologies have been an ongoing challenge due to low methane concentrations. In this study, a type of coconut shell-based active carbon was employed to enrich VAM with a three-bed vacuum pressure swing adsorption unit. A new vacuum exhaust step for the VPSA process was introduced. The results show that the vacuum exhaust step can increase the methane concentration of the product without changing adsorption and desorption pressure. Under laboratory conditions, the concentration of product increased from 0.4% to 0.69% as the vacuum exhaust ratio increased from 0 to 3.1 when the feed gas concentration was 0.2%. A 500 m³/h pilot-scale test system for VAM enrichment was built rendering good correlation with the laboratory results in terms of the vacuum exhaust step. By using a two-stage three-bed separation unit, the VAM was enriched from 0.2% to over 1.2%.

Flame structure of methane inverse diffusion flame

KAUST Repository

Elbaz, Ayman M.

2014-07-01

This paper presents high speed images of OH-PLIF at 10. kHz simultaneously with 2D PIV (particle image velocimetry) measurements collected along the entire length of an inverse diffusion flame with circumferentially arranged methane fuel jets. For a fixed fuel flow rate, the central air jet Re was varied, leading to four air to fuel velocity ratios, namely Vr = 20.7, 29, 37.4 and 49.8. A double flame structure could be observed composed of a lower fuel entrainment region and an upper mixing and intense combustion region. The entrainment region was enveloped by an early OH layer, and then merged through a very thin OH neck to an annular OH layer located at the shear layer of the air jet. The two branches of this annular OH layer broaden as they moved downstream and eventfully merged together. Three types of events were observed common to all flames: breaks, closures and growing kernels. In upstream regions of the flames, the breaks were counterbalanced by flame closures. These breaks in OH signal were found to occur at locations where locally high velocity flows were impinging on the flame. As the Vr increased to 37.4, the OH layers became discontinuous over the downstream region of the flame, and these regions of low or no OH moved upstream. With further increases in Vr, these OH pockets act as flame kernels, growing as they moved downstream, and became the main mechanism for flame re-ignition. Along the flame length, the direction of the two dimensional principle compressive strain rate axis exhibited a preferred orientation of approximately 45° with respect to the flow direction. Moreover, the OH zones were associated with elongated regions of high vorticity. © 2013 Elsevier Inc.

The Measurement of Fuel-Air Ratio by Analysis for the Oxidized Exhaust Gas

Science.gov (United States)

Gerrish, Harold C.; Meem, J. Lawrence, Jr.

1943-01-01

An investigation was made to determine a method of measuring fuel-air ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-air ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of air and of fuel supplied and also by analysis of the oxidized exhaust gas and of the normal exhaust gas. Five fuels were used: gasoline that complied with Army-Navy fuel Specification No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene. The method of determining the fuel-air ratio described in this report involves the measurement of the carbon-dioxide content of the oxidized exhaust gas and the use of graphs for the presented equation. This method is considered useful in aircraft, in the field, or in the laboratory for a range of fuel-air ratios from 0.047 to 0.124.

The Measurement of Fuel-air Ratio by Analysis of the Oxidized Exhaust Gas

Science.gov (United States)

Memm, J. Lawrence, Jr.

1943-01-01

An investigation was made to determine a method of measuring fuel-air ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-air ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of air and of fuel supplied and also by analysis of the oxidized exhaust gas and of the normal exhaust gas. Five fuels were used: gasoline that complied with Army-Navy Fuel Specification, No. AN-VV-F-781 and four mixtures of this gasoline with toluene, benzene, and xylene. The method of determining the fuel-air ratio described in this report involves the measurement of the carbon-dioxide content of the oxidized exhaust gas and the use of graphs or the presented equation. This method is considered useful in aircraft, in the field, or in the laboratory for a range of fuel-air ratios from 0.047 to 0.124

30 CFR 75.323 - Actions for excessive methane.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Actions for excessive methane. 75.323 Section... excessive methane. (a) Location of tests. Tests for methane concentrations under this section shall be made.... (1) When 1.0 percent or more methane is present in a working place or an intake air course, including...

Spent fuel treatment to allow storage in air

International Nuclear Information System (INIS)

Williams, K.L.

1988-01-01

During Fiscal Year 1987 (FY-87), research began at the Idaho National Engineering Laboratory (INEL) to develop a treatment material and process to coat fuel rods in commercial spent fuel assemblies to allow the assemblies to be stored in hot (up to 380 0 C) air without oxidation of the fuel. This research was conducted under a research and development fund provided by the U.S. Department of Energy (DOE) and independently administered by EG and G Idaho, Inc., DOE's prime contractor at the INEL. The objectives of the research were to identify and evaluate possible treatment processes and materials, identify areas of uncertainty, and to recommend the most likely candidate to allow spent fuel dry storage in hot air. The results of the research are described: results were promising and several good candidates were identified, but further research is needed to examine the candidates to the point where comparison is possible

Pump-to-Wheels Methane Emissions from the Heavy-Duty Transportation Sector.

Science.gov (United States)

Clark, Nigel N; McKain, David L; Johnson, Derek R; Wayne, W Scott; Li, Hailin; Akkerman, Vyacheslav; Sandoval, Cesar; Covington, April N; Mongold, Ronald A; Hailer, John T; Ugarte, Orlando J

2017-01-17

Pump-to-wheels (PTW) methane emissions from the heavy-duty (HD) transportation sector, which have climate change implications, are poorly documented. In this study, methane emissions from HD natural gas fueled vehicles and the compressed natural gas (CNG) and liquefied natural gas (LNG) fueling stations that serve them were characterized. A novel measurement system was developed to quantify methane leaks and losses. Engine related emissions were characterized from twenty-two natural gas fueled transit buses, refuse trucks, and over-the-road (OTR) tractors. Losses from six LNG and eight CNG stations were characterized during compression, fuel delivery, storage, and from leaks. Cryogenic boil-off pressure rise and pressure control venting from LNG storage tanks were characterized using theoretical and empirical modeling. Field and laboratory observations of LNG storage tanks were used for model development and evaluation. PTW emissions were combined with a specific scenario to view emissions as a percent of throughput. Vehicle tailpipe and crankcase emissions were the highest sources of methane. Data from this research are being applied by the authors to develop models to forecast methane emissions from the future HD transportation sector.

Global health benefits of mitigating ozone pollution with methane emission controls.

Science.gov (United States)

West, J Jason; Fiore, Arlene M; Horowitz, Larry W; Mauzerall, Denise L

2006-03-14

Methane (CH(4)) contributes to the growing global background concentration of tropospheric ozone (O(3)), an air pollutant associated with premature mortality. Methane and ozone are also important greenhouse gases. Reducing methane emissions therefore decreases surface ozone everywhere while slowing climate warming, but although methane mitigation has been considered to address climate change, it has not for air quality. Here we show that global decreases in surface ozone concentrations, due to methane mitigation, result in substantial and widespread decreases in premature human mortality. Reducing global anthropogenic methane emissions by 20% beginning in 2010 would decrease the average daily maximum 8-h surface ozone by approximately 1 part per billion by volume globally. By using epidemiologic ozone-mortality relationships, this ozone reduction is estimated to prevent approximately 30,000 premature all-cause mortalities globally in 2030, and approximately 370,000 between 2010 and 2030. If only cardiovascular and respiratory mortalities are considered, approximately 17,000 global mortalities can be avoided in 2030. The marginal cost-effectiveness of this 20% methane reduction is estimated to be approximately 420,000 US dollars per avoided mortality. If avoided mortalities are valued at 1 US dollars million each, the benefit is approximately 240 US dollars per tone of CH(4) ( approximately 12 US dollars per tone of CO(2) equivalent), which exceeds the marginal cost of the methane reduction. These estimated air pollution ancillary benefits of climate-motivated methane emission reductions are comparable with those estimated previously for CO(2). Methane mitigation offers a unique opportunity to improve air quality globally and can be a cost-effective component of international ozone management, bringing multiple benefits for air quality, public health, agriculture, climate, and energy.

Toxic and hazardous air pollutants from co-firing biomass fuels, fossil fuels, MSW and RDF

International Nuclear Information System (INIS)

Junge, D.C.

1991-01-01

Toxic and hazardous pollutants are defined and then are considered from the perspective of pollutants which enter the combustion process with the fuel (principally the metals and metallic compounds) and pollutants which are formed as products of incomplete combustion. Control strategies are reviewed through the entire process including fuel preparation and storage, combustion control and the application of air pollution control devices. Measurement techniques for specific toxic and hazardous air pollutants are discussed

Methane emissions from natural wetlands

Energy Technology Data Exchange (ETDEWEB)

Meyer, J.L. [Georgia Univ., Athens, GA (United States); Burke, R.A. Jr. [Environmental Protection Agency, Athens, GA (United States). Environmental Research Lab.

1993-09-01

Analyses of air trapped in polar ice cores in conjunction with recent atmospheric measurements, indicate that the atmospheric methane concentration increased by about 250% during the past two or three hundred years (Rasmussen and Khalil, 1984). Because methane is a potent ``greenhouse`` gas, the increasing concentrations are expected to contribute to global warning (Dickinson and Cicerone, 1986). The timing of the methane increase suggests that it is related to the rapid growth of the human population and associated industrialization and agricultural development. The specific causes of the atmospheric methane concentration increase are not well known, but may relate to either increases in methane sources, decreases in the strengths of the sinks, or both.

Controlled deposition and utilization of carbon on Ni-YSZ anodes of SOFCs operating on dry methane

International Nuclear Information System (INIS)

Jiao, Yong; Zhang, Liqin; An, Wenting; Zhou, Wei; Sha, Yujing; Shao, Zongping; Bai, Jianping; Li, Si-Dian

2016-01-01

Solid oxide fuel cells (SOFCs) are promising power-generation systems to utilize methane or methane-based fuels with a high energy efficiency and low environmental impact. A successive multi-stage process is performed to explore the operation of cells using dry methane or the deposited carbon from methane decomposition as fuel. Stable operation can be maintained by optimizing the fuel supply and current density parameters. An electrochemical impedance analysis suggests that the partial oxidization of Ni can occur at anodes when the carbon fuel is consumed. The stability of cells operated on pure methane is investigated in three operating modes. The cell can run in a comparatively stable state with continuous power output in an intermittent methane supply mode, where the deposition and utilization of carbon is controlled by balancing the fuel supply and consumption. The increase in the polarization resistance of the cell might originate from the small amount of NiO and residual carbon at the anode, which can be removed via an oxidation-and-reduction maintenance process. Based on the above strategy, this work provides an alternative operating mode to improve the stability of direct methane SOFCs and demonstrates the feasibility of its application. - Highlights: • A new strategy to control the deposition and utilization of carbon was developed. • A stable fuel cell operation was obtained with an intermittent fuel supply mode. • Polarization resistance increased due to small amount of NiO and residual carbon.

Methanation of Carbon Dioxide

OpenAIRE

Goodman, Daniel Jacob

2013-01-01

The emission of greenhouse gases into the atmosphere has been linked to global warming. Carbon dioxide's (CO2) one of the most abundant greenhouse gases. Natural gas, mainly methane, is the cleanest fossil fuel for electricity production helping meet the United States ever growing energy needs. The methanation of CO2 has the potential to address both of these problems if a catalyst can be developed that meets the activity, economic and environmental requirements to industrialize the process. ...

Effect analysis of air introduced by pressurization on fuel rod performances

International Nuclear Information System (INIS)

Ren Qisen; Liu Tong; Sheng Guofu

2012-01-01

In the process of pressurization and seal welding, it is common practice to vacuumize before gas filling for the sake of preventing introducing air and other impurities, which would affect the gas composition inside of the fuel rod. However, vacuumization during pressurization is likely not being required sometimes in order to simplify the fabrication procedure. In the present work, based on the AFA3G fuel rod design with 2 MPa of filling gas, analyses on fuel rod performances were carried out under the condition of pressurization with and without vacuumization, respectively. Furthermore, the effect on hydrogen content in fuel rod was preliminarily discussed. Results indicate that the impacts of air composition introduced by pressurization on fuel rod thermal-mechanical performances, such as internal pressure and fuel center temperature, were extremely slight. The gap conductance varies to some extent as a result of the change of gas composition due to air introduced in fuel rod. The impact of humidity on water content in fuel rod is negligible at a low temperature of around 25℃. However, at higher temperature, it is essential to pay attention on the control of fabrication process, and prevent much moisture entering into the fuel rod and increasing the probability of hydriding failure. (authors)

Optical sensor system for time-resolved quantification of methane concentrations: Validation measurements in a rapid compression machine

Science.gov (United States)

Bauke, Stephan; Golibrzuch, Kai; Wackerbarth, Hainer; Fendt, Peter; Zigan, Lars; Seefeldt, Stefan; Thiele, Olaf; Berg, Thomas

2018-05-01

Lowering greenhouse gas emissions is one of the most challenging demands of today's society. Especially, the automotive industry struggles with the development of more efficient internal combustion (IC) engines. As an alternative to conventional fuels, methane has the potential for a significant emission reduction. In methane fuelled engines, the process of mixture formation, which determines the properties of combustion after ignition, differs significantly from gasoline and diesel engines and needs to be understood and controlled in order to develop engines with high efficiency. This work demonstrates the development of a gas sensing system that can serve as a diagnostic tool for measuring crank-angle resolved relative air-fuel ratios in methane-fuelled near-production IC engines. By application of non-dispersive infrared absorption spectroscopy at two distinct spectral regions in the ν3 absorption band of methane around 3.3 μm, the system is able to determine fuel density and temperature simultaneously. A modified spark plug probe allows for straightforward application at engine test stations. Here, the application of the detection system in a rapid compression machine is presented, which enables validation and characterization of the system on well-defined gas mixtures under engine-like dynamic conditions. In extension to a recent proof-of-principle study, a refined data analysis procedure is introduced that allows the correction of artefacts originating from mechanical distortions of the sensor probe. In addition, the measured temperatures are compared to data obtained with a commercially available system based on the spectrally resolved detection of water absorption in the near infrared.

An efficient mathematical model for air-breathing PEM fuel cells

International Nuclear Information System (INIS)

Ismail, M.S.; Ingham, D.B.; Hughes, K.J.; Ma, L.; Pourkashanian, M.

2014-01-01

Graphical abstract: The effects of the ambient humidity on the performance of air-breathing PEM fuel cells become more pronounced as the ambient temperature increases. The polarisation curves have been generated using the in-house developed MATLAB® application, Polarisation Curve Generator, which is available in the supplementary data. - Highlights: • An efficient mathematical model has been developed for an air-breathing PEM fuel cell. • The fuel cell performance is significantly over-predicted if the Joule and entropic heats are neglected. • The fuel cell performance is highly sensitive to the state of water at the thermodynamic equilibrium. • The cell potential dictates the favourable ambient conditions for the fuel cell. - Abstract: A simple and efficient mathematical model for air-breathing proton exchange membrane (PEM) fuel cells has been built. One of the major objectives of this study is to investigate the effects of the Joule and entropic heat sources, which are often neglected, on the performance of air-breathing PEM fuel cells. It is found that the fuel cell performance is significantly over-predicted if one or both of these heat sources is not incorporated into the model. Also, it is found that the performance of the fuel cell is highly sensitive to the state of the water at the thermodynamic equilibrium magnitude as both the entropic heat and the Nernst potential considerably increase if water is assumed to be produced in liquid form rather than in vapour form. Further, the heat of condensation is shown to be small and therefore, under single-phase modelling, has a negligible effect on the performance of the fuel cell. Finally, the favourable ambient conditions depend on the operating cell potential. At intermediate cell potentials, a mild ambient temperature and low humidity are favoured to maintain high membrane conductivity and mitigate water flooding. At low cell potentials, low ambient temperature and high humidity are favoured to

Catalytic removal of methane and NO{sub x} in lean-burn natural-gas engine exhaust; Elimination par catalyse du methane et des NO{sub x} dans les echappements de moteur au gaz naturel a basse combustion

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, H.; Satokawa, S.; Yahagi, M.; Yamaseki, K.; Hoshi, F.; Uchida, H.; Yokota, H. [Tokyo Gas Co., Ltd. (Japan)

2000-07-01

We have developed a new catalytic system to reduce the emissions of hydrocarbons, carbon monoxide (CO), and nitrogen oxides (NO{sub x}) contained in the exhaust gases from a lean-burn natural-gas engine. Catalytic oxidation of unburned hydrocarbons and CO in the exhaust has been studied for noble metals supported on alumina. (1) A low-loading catalyst comprising platinum supported on alumina (Pt/alumina) was efficient for the oxidation of CO and hydrocarbons without methane. The CO conversions were maintained at more than 98 % for 20,000 hours over the Pt/alumina. (2) A catalyst comprising platinum and palladium supported on alumina (Pt-Pd/alumina) exhibited higher levels of oxidation of hydrocarbons (including methane) than a catalyst comprising only palladium supported on alumina (Pd/alumina). Its oxidation also lasted longer. The combined effects of the platinum and palladium metals achieved high sulfur dioxide resistance. Increasing the palladium content in the Pt-Pd/alumina catalyst increased the level of oxidation and extended the lifetime of the catalyst. (3) A catalyst comprising silver supported on alumina (Ag/alumina) was effective at reducing the amount of NO{sub X} by using the unburned hydrocarbons in the exhaust gas. The NO{sub x} conversions over Ag/alumina were maintained at more than 30 % for 3,500 hours. We describe a total clean-up system consisting of a Ag/alumina catalyst and a Pt-Pd/alumina catalyst in series on the exhaust gas stream. (authors)

Designing and implementing science-based methane policies

Science.gov (United States)

George, F.

2017-12-01

The phenomenal growth in shale gas production across the U.S. has significantly improved the energy security and economic prospects of the country. Natural gas is a "versatile" fuel that has application in every major end-use sector of the economy, both as a fuel and a feedstock. Natural gas has also played a significant role in reducing CO2 emissions from the power sector by displacing more carbon intensive fossil fuels. However, emissions of natural gas (predominantly methane) from the wellhead to the burner tip can erode this environmental benefit. Preserving the many benefits of America's natural gas resources requires smart, science-based policies to optimize the energy delivery efficiency of the natural gas supply chain and ensure that natural gas remains a key pillar in our transition to a low-carbon economy. Southwestern Energy (SWN) is the third largest natural gas producer in the United States. Over the last several years, SWN has participated in a number of scientific studies with regulatory agencies, academia and non-governmental entities that have led to over a dozen peer-reviewed papers on methane emissions from oil and gas operations. This presentation will review how our participation in these studies has informed our internal policies and procedures, as well as our external programs, including the ONE Future coalition (ONE Future). In particular, the presentation will highlight the impact of such studies on our Leak Detection and Repair (LDAR) program, designing new methane research and on the ONE Future initiatives - all with the focus of improving the delivery efficiency of oil and gas operations. Our experience supports continued research in the detection and mitigation of methane emissions, with emphasis on longer duration characterization of methane emissions from oil and gas facilities and further development of cost-effective methane detection and mitigation techniques. We conclude from our scientific and operational experiences that a

The influence of air-fuel ratio on mixture parameters in port fuel injection engines

Directory of Open Access Journals (Sweden)

Adrian Irimescu

2008-10-01

Full Text Available Nowadays, research in the internal combustion engine field is focusing on detailed understanding of the processes that take place in certain parts of the aggregate, and can have a great influence on the engine’s performance and pollution levels. Such research is developed in this paper, in which using a numerical method based on the i-x air-fuel diagram, one can simulate a series of values for pressure, temperature and intake air humidity before and after mixture formation takes place in a spark ignition engine inlet port. The aim is to evaluate the final temperature of the air-fuel mixture near the inlet valve and evaluating the main factors of influence on the homogeneity of the mixture.

A Study of Pollutant Formation from the Lean Premixed Combustion of Gaseous Fuel Alternatives to Natural Gas

Science.gov (United States)

Fackler, Keith Boyd, Jr.

The goal of this research is to identify how nitrogen oxide (NO x) emissions and flame stability (blowout) are impacted by the use of fuels that are alternatives to typical pipeline natural gas. The research focuses on lean, premixed combustors that are typically used in state-of-the-art natural gas fueled systems. An idealized laboratory lean premixed combustor, specifically the jet-stirred reactor, is used for experimental data. A series of models, including those featuring detailed fluid dynamics and those focusing on detailed chemistry, are used to interpret the data and understand the underlying chemical kinetic reasons for differences in emissions between the various fuel blends. An ultimate goal is to use these data and interpretive tools to develop a way to predict the emission and stability impacts of changing fuels within practical combustors. All experimental results are obtained from a high intensity, single-jet stirred reactor (JSR). Five fuel categories are studied: (1) pure H 2, (2) process and refinery gas, including combinations of H2, CH4, C2H6, and C3H8, (3) oxygen blown gasified coal/petcoke composed of H2, CO, and CO2, (4) landfill and digester gas composed of CH4, CO2, and N2, and (5) liquified natural gas (LNG)/shale/associated gases composed of CH4, C2H6, and C3 H8. NOx measurements are taken at a nominal combustion temperature of 1800 K, atmospheric pressure, and a reactor residence time of 3 ms. This is done to focus the results on differences caused by fuel chemistry by comparing all fuels at a common temperature, pressure, and residence time. This is one of the few studies in the literature that attempts to remove these effects when studying fuels varying in composition. Additionally, the effects of changing temperature and residence time are investigated for selected fuels. At the nominal temperature and residence time, the experimental and modeling results show the following trends for NOx emissions as a function of fuel type: 1.) NOx

Impact of co-flow air on buoyant diffusion flames flicker

Energy Technology Data Exchange (ETDEWEB)

Gohari Darabkhani, H., E-mail: h.g.darabkhani@gmail.com [School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester M13 9PL (United Kingdom); Wang, Q.; Chen, L.; Zhang, Y. [Mechanical Engineering Department, University of Sheffield, Mapping Street, Sheffield S1 3JD (United Kingdom)

2011-08-15

Highlights: {yields} We present the co-flow effects on flickering behaviour of diffusion flames. {yields} Co-flow air is shown to fully suppress the buoyancy driven flame oscillations. {yields} Schlieren and PIV illustrate the shift of outer vortices beyond the flame zone. {yields} Stability controlling parameter as a ratio of air to fuel velocities is presented. {yields} Equation for linear increase in flickering frequency by co-flow air is presented. - Abstract: This paper describes experimental investigation of co-flow air velocity effects on the flickering behaviour of laminar non-lifted methane diffusion flames. Chemiluminescence, high-speed photography, schlieren and Particle Imaging Velocimetry (PIV), have been used to study the changes in the flame/vortex interactions as well as the flame flickering frequency and magnitude by the co-flow air. Four cases of methane flow rates at different co-flow air velocities are investigated. It has been observed that the flame dynamics and stability of co-flow diffusion flames are strongly affected by the co-flow air velocity. When the co-flow velocity has reached a certain value the buoyancy driven flame oscillation was completely suppressed. The schlieren and PIV imaging have revealed that the co-flow of air is able to push the initiation point of the outer toroidal vortices beyond the visible flame to create a very steady laminar flow region in the reaction zone. Then the buoyancy driven instability is only effective in the plume of hot gases above the visible flame. It is observed that a higher co-flow rate is needed in order to suppress the flame flickering at a higher fuel flow rate. Therefore the ratio of the air velocity to the fuel velocity, {gamma}, is a stability controlling parameter. The velocity ratio, {gamma}, was found to be 0.72 for the range of tested flow rates. The dominant flickering frequency was observed to increase linearly with the co-flow rate (a) as; f = 0.33a + 11. The frequency amplitudes

A new technology to overcome the limits of HCCI engine through fuel modification

International Nuclear Information System (INIS)

Bahng, GunWoong; Jang, Dongsoon; Kim, Youngtae; Shin, Misoo

2016-01-01

Highlights: • Problems of HCCI engine can be overcome by adopting fuel modification. • Gasoline vapor with HHO gas showed drastic improvement of fuel efficiency. • Performance of single cylinder engine shows fuel efficiency more than double. - Abstract: The energy efficiency of internal combustion engine reached to about 30% only recently. To increase the efficiency, homogeneous charge compression ignition (HCCI) has been proposed, however, there is no available commercial engine yet. The main problem lies in the delayed heating rate in spite of fast reaction of homogeneous charged state of HCCI with excess air. To overcome this difficulty, a modification of fuel by vaporization of liquid gasoline with water electrolysis gas and air was adopted in order to warrant the fast and high temperature rise. Experiments were carried out with single cylinder engines supplied from the four different manufacturers. Experimental results show that fuel consumption was decreased by more than 50% compared to the case of supplying liquid fuel. It is believed it was due to the combined effects of the high and fast heating potential of water electrolysis gas together with the efficient turbulence mixing effect of vaporized fuel with excess air. By this method, the drawbacks caused by lean burn in the HCCI engine such as small power range can be overcome.

Experimental validation of large-eddy simulation for swirling methane-air non-premixed combustion

Energy Technology Data Exchange (ETDEWEB)

Hu, L.Y.; Luo, Y.H.; Xu, C.S. [Shanghai Jiaotong Univ. (China). School of Mechanical Engineering; Zhou, L.X. [Tsinghua Univ., Beijing (China). Dept. of Engineering Mechanics

2013-07-01

Large-eddy simulation of swirling methane-air non-premixed combustion was carried out using a Smagorinsky-Lilly subgrid scale stress model and a presumed-PDF fast-chemistry combustion model. The LES statistical results are validated by PIV, temperature and species concentration measurements made by the present authors. The results indicate that in the present case the presumed-PDF fast-chemistry combustion model is a fairish one. The instantaneous vorticity and temperature maps show clearly the development and the interaction between coherent structures and combustion.

Nitric Oxide and Oxygen Air-Contamination Effects on Extinction Limits of Non-Premixed Hydrocarbon-Air Flames for a HIFiRE Scramjet

Science.gov (United States)

Pellett, Gerald L.; Dawson, Lucy C.; Vaden, Sarah N.; Wilson, Lloyd G.

2009-01-01

Unique nitric oxide (NO) and oxygen air-contamination effects on the extinction Flame Strength (FS) of non-premixed hydrocarbon (HC) vs. air flames are characterized for 7 gaseous HCs, using a new idealized 9.3 mm straight-tube Opposed Jet Burner (OJB) at 1 atm. FS represents a laminar strain-induced extinction limit based on cross-section-average air jet velocity, Uair, that sustains combustion of a counter jet of gaseous fuel just before extinction. Besides ethane, propane, butane, and propylene, the HCs include ethylene, methane, and a 64 mole-% ethylene / 36 % methane mixture, the writer s previously recommended gaseous surrogate fuel for HIFiRE scramjet tests. The HC vs. clean air part of the work is an extension of a May 2008 JANNAF paper that characterized surrogates for the HIFiRE project that should mimic the flameholding of reformed (thermally- or catalytically-cracked) endothermic JP-like fuels. The new FS data for 7 HCs vs. clean air are thus consolidated with the previously validated data, normalized to absolute (local) axial-input strain rates, and co-plotted on a dual kinetically dominated reactivity scale. Excellent agreement with the prior data is obtained for all 7 fuels. Detailed comparisons are also made with recently published (Univ. Va) numerical results for ethylene extinction. A 2009-revised ethylene kinetic model (Univ. Southern Cal) led to predicted limits within approx. 5 % (compared to 45 %, earlier) of this writer s 2008 (and present) ethylene FSs, and also with recent independent data (Univ. Va) obtained on a new OJB system. These +/- 5 % agreements, and a hoped-for "near-identically-performing" reduced kinetics model, would greatly enhance the capability for accurate numerical simulations of surrogate HC flameholding in scramjets. The measured air-contamination effects on normalized FS extinction limits are projected to assess ongoing Arc-Heater-induced "facility test effects" of NO production (e.g., 3 mole-%) and resultant oxygen

Performance of a hydrogen-enriched ethanol engine at unthrottled and lean conditions

International Nuclear Information System (INIS)

Zhang, Bo; Ji, Changwei; Wang, Shuofeng

2016-01-01

Highlights: • H_2 addition eased cyclic variation of ethanol engine at unthrottled condition. • H_2-blended ethanol engine gains better efficiency at lean conditions. • Bmep of H_2-blended ethanol engine could be controlled by lean burning. • H_2 addition results in reduced exhaust loss and HC emissions. - Abstract: Concerning the throttling loss under part load conditions, it is feasible to further improve the engine thermal efficiency through operating the engine under the unthrottled condition and controlling its load by changing the excess air ratio. However, the narrow flammability of ethanol may lead the ethanol engine to encounter high cyclic variations under unthrottled and lean conditions. The addition of hydrogen is potentially helpful for solving this problem. In this test, the engine was run under an speed of 1400 rpm and unthrottled conditions. The hydrogen volume fractions in the intake were respectively kept at 0% and 3%. For a given hydrogen blending level, the ethanol flow rate was reduced to enable the engine to run under lean conditions. The results showed that the engine efficiency was improved with the blending of hydrogen. The highest thermal efficiency was improved by 6.07% after blending 3% hydrogen to the intake air. The addition of hydrogen could increase the engine torque output at lean conditions. Both cooling and exhaust losses were decreased after the hydrogen enrichment while adopting the lean combustion strategy. The hydrogen addition contributed to the extended lean burn limit and decreased cyclic variation under lean conditions. HC and CO emissions were decreased whereas NOx emissions were increased after the blending of hydrogen.

Prediction of air-fuel and oxy-fuel combustion through a generic gas radiation property model

International Nuclear Information System (INIS)

Yin, Chungen

2017-01-01

Highlights: • A gas radiation model for general combustion CFD presented, programmed & verified. • Its general applicability/practical accuracy demonstrated in air-fuel and oxy-fuel. • Useful guidelines for air-fuel and oxy-fuel combustion CFD suggested. • Important to include the impact of CO in gas radiation for oxy-fuel combustion CFD. - Abstract: Thermal radiation plays an important role in heat transfer in combustion furnaces. The weighted-sum-of-gray-gases model (WSGGM), representing a good compromise between computational efficiency and accuracy, is commonly used in computational fluid dynamics (CFD) modeling of combustion processes for evaluating gaseous radiative properties. However, the WSGGMs still have some limitations in practical use, e.g., unable to naturally accommodate different combustion environments, difficult to accurately address the variations in species concentrations in a flame, and inconvenient to account for the impacts of participating species other than H_2O and CO_2. As a result, WSGGMs with different coefficients have been published for specific applications. In this paper, a reliable generic model for gaseous radiation property calculation, which is a computationally efficient exponential wide band model (E-EWBM) applicable to combustion CFD and able to naturally solve all the practical limitations of the WSGGMs, is presented, programmed and verified. The model is then implemented to CFD simulation of a 300 kW air-fuel and a 0.8 MW oxy-fuel combustion furnace, respectively, to demonstrate its computational applicability to general combustion CFD and its capability in producing reliable CFD results for different combustion environments. It is found that the usefulness of the WSGGMs in oxy-fuel combustion CFD is compromised if the important impacts of high levels of CO under oxy-fuel combustion cannot be accounted for. The E-EWBM that appropriately takes the impacts of H_2O, CO_2, CO and CH_4 into account is a good replacement

Analisa Lean Service Guna Mengurangi Waste Pada Perusahaan Daerah Air Minum Banyuwangi

Directory of Open Access Journals (Sweden)

Harliwantip

2014-04-01

Full Text Available Lean service digunakan sebagai pendekatan untuk membuat suatu sistem service internal yang efektif sehingga bisa dipastikan informasi-informasi penting bisa sampai ke konsumen dengan cepat dan dengan pelayanan yang efektif. Tingkat pelayanan pada PDAM Banyuwangi rendah dan tingkat kehilangan air (uncounted water yang tinggi. Oleh karena itu tujuan penelitian ini mengidentifikasi waste dan mengetahui waste kritis yang terjadi dalam proses jasa di PDAM. Metode yang digunakan dalam penelitian menggunakan Big Picture Mapping dan Root cause analysis dalam mencari penyebab waste. Adapun Waste yang terjadi yaitu 1Over Production, 2Defect, 3Unnecessary Inventory, 4 Inappropriate Processing, 5Excessive Transportation, 6Waiting, 7Unnecessary Motion. Sedangkan waste kritis yang terjadi pada proses layanan yaitu waiting dengan bobot 0,21. Waste waiting disebabkan karena delay tenaga mekanik, delay material perbaikan, delay perbaikan jalur pipa yang melewati ruang publik. Dengan mengetahui jenis waste dan waste kritis di PDAM diharapkan dapat mengurangi waste dan kepuasan konsumen terpenuhi.

Methane measurements manual; Handbok metanmaetningar

Energy Technology Data Exchange (ETDEWEB)

Holmgren, Magnus Andreas (SP Technical research institute of Sweden, Boraas (Sweden))

2011-02-15

Emissions to air in different parts of the system may arise in biogas plants, where there is biological treatment of organic matter by anaerobic degradation, and during upgrading of biogas to vehicle fuel. There are mainly four reasons why these emissions must be minimized. These are safety, greenhouse gas emissions, economy and smell. This manual gathers experience of several years of work with measurement of methane emissions from biogas and upgrading facilities. This work has been done mainly in the context of Swedish Waste Management's system of voluntary commitment. The purpose of this manual is to standardize methods and procedures when methane measurements are carried out so that the results are comparable between different providers. The main target group of the manual is measurement consultants performing such measurements. Calculation template in Excel is part of the manual, which further contributes to the measurements evaluated in a standardized way. The manual contains several examples which have been calculated in the accompanying Excel template. The handbook also contains a chapter mainly intended for facility staff, in which implementation of accurate leak detection is described, and where there are hints of a system of so-called intermediate inspections to detect leaks in time

Effects of alternative-fuel vehicles on air quality in Ontario, Canada

International Nuclear Information System (INIS)

Kantor, I.; Fowler, M.; Hajimiragha, A.; Canizares, C.; Elkamel, A.

2009-01-01

The economies of the developed world are increasingly including green technologies and processes that consider social, environmental and economic consequences. Hybrid electric vehicles and other fuel-efficient vehicle types can supply consumers with vehicles that decrease their ecological footprint and reduce the cost of fuel. However, one of the societal concerns often overlooked is the impact of alternative-fuel vehicle usage on the air quality in the urban environment. This paper presented a study that assessed the impact on air quality stemming from the operation of alternative fuel vehicles in urban environments. The study specifically focused on the province-wide emissions in Ontario and urban air pollution in the city of Toronto. The paper considered the life-cycle impacts of using alternative fuels for transportation purposes in terms of six major stressors for climate change, acidification and urban air quality. The two types of vehicles that were studied were plug-in hybrid electric vehicles (PHEVs) and fuel cell vehicles. Modeling of the penetration rates for both types of vehicles was completed based on the maximum capacity of the electrical grid including planned improvements. The scope of the study and discussion of health effects was first presented followed by data gathering and usage, methodology, results of supportable penetration and vehicle growth, and pollution abatement results. It was concluded that fuel cell vehicles have an advantage over, or near-equality with, PHEVs in almost every aspect of their emissions. 13 refs., 2 tabs., 10 figs

Biofiltration for Mitigation of Methane Emission from Animal Husbandry

NARCIS (Netherlands)

Melse, R.W.; Werf, van der A.W.

2005-01-01

Removal of methane from exhaust air of animal houses and manure storage has a large potential for the reduction of greenhouse gas emissions from animal husbandry. The aim of this study was to design a biofilter for methane removal at a full-scale livestock production facility. Air from the headspace

Performance and exhaust emissions in a natural-gas fueled dual-fuel engine; Tennen gas dual fuel kikan no seino oyobi haiki tokusei

Energy Technology Data Exchange (ETDEWEB)

Shioji, M.; Ishiyama, T.; Shibata, H. [Kyoto Univ., Kyoto (Japan). Inst. of Atomic Energy; Ikegami, M. [Fukui Institute of Technology, Fukui (Japan). Faculty of Engineering

2000-07-25

In order to establish the optimum fueling in a natural gas fueled dual fuel engine, tests were made for some operational parameters and their combination on the engine performances and the exhaust emissions. The results show that the gas oil quantity should be increased and gas oil injection timing should be advanced to suppress unburned hydrocarbon emission at middle and low output range, while the quantity should be reduced and the timing should be retarded to avoid onset of knock at high loads. The unburned hydrocarbon emission and the thermal efficiency are improved at the same load avoiding too lean natural gas premixture by restriction of intake charge air. However the improvement is limited because the ignition and initial combustion of pilot diesel fuel is deteriorated when the cylinder pressure is excessively lowered by throttling. The increase in pilot gas oil amount is effective for low-load operation and the adequate combination of throttle control and equivalence ratio ensures low hydrocarbon emission and the thermal efficiency comparable to diesel operation. (author)

Allowable spent LWR fuel storage temperatures in inert gases, nitrogen, and air

International Nuclear Information System (INIS)

Gilbert, E.R.; Cunningham, M.E.; Simonen, E.P.; Thomas, L.E.; Campbell, T.K.; Barnhart, D.M.

1990-01-01

Spent fuel in inert dry storage is now a reality in the US; recommended maximum temperature-time conditions are specified in an IBM PC-compatible code. However, spent fuel cannot yet be stored in air because the data and theory needed for predicting allowable temperatures are still being developed. Tests to determine the behavior of spent UO 2 fragments and breached rod specimens in air are providing data that will be used to determine the temperatures that can be allowed for fuel stored in air. 13 refs., 5 figs

An experimental and numerical investigation of the combustion characteristics of a dual fuel engine with a swirl chamber

Energy Technology Data Exchange (ETDEWEB)

Liu, C.; Karim, G.A.; Xiao, F.; Sohrabi, A. [Calgary Univ., AB (Canada). Schulich School of Engineering, Mechanical and Manufacturing Dept.

2007-07-01

The results of an experimental investigation of the performance of a small bore engine with a swirl chamber when operating as a dual fuel engine with commercial methane as the gaseous fuel were presented in this paper. The experiment involved using a 3-dimensional computational fluid dynamics model to predict the performance of the engine. A detailed chemical kinetics for the gaseous fuel component, consisting primarily of methane and a reduced detailed chemical kinetics for the diesel fuel while considering the turbulent combustion processes an associated performance of a dual fuel engine with a swirl chamber were incorporated in the simulation. The study experimentally and numerically investigated the effects of changes in the quantities of the liquid fuel pilot and gaseous fuels on the combustion processes, engine performance, cyclic variations, and emissions. The paper discussed the experimental approach and results. It also discussed the simulation of the dual fuel engine combustion process. It was concluded that dual fuel combustion was an effective method to burn a gaseous fuel-air mixture with a low energy density. 9 refs., 6 figs.

Numerical Simulation of Methane Slip in Dual Fuel Marine Engines

DEFF Research Database (Denmark)

Han, Jaehyun; Jensen, Michael Vincent; Pang, Kar Mun

2017-01-01

estimations. The simulations with various gas pipe geometries were conducted. It seemed that the effect of the change in injection direction is more dominant than the change in the gas hole configuration. The favorable injection direction for minimum amount of methane slip was discovered as the direction...... which helps developing the flow of methane far from the exhaust ports. The effects of various valve timing settings were also simulated. The advancement of the exhaust valve closing was more efficient than the retardation of the intake valve opening. A little retardation of the intake valve opening even......The methane slip is the problematic issue for the engines using natural gas(NG). Because methane is more powerful greenhouse gas (GHG) than CO2, understanding of the methane slip during gas exchange process of the engines is essential. In this study, the influence of the gas pipe geometry...

Flow structures in a lean-premixed swirl-stabilized combustor with microjet air injection

KAUST Repository

LaBry, Zachary A.

2011-01-01

The major challenge facing the development of low-emission combustors is combustion instability. By lowering flame temperatures, lean-premixed combustion has the potential to nearly eliminate emissions of thermally generated nitric oxides, but the chamber acoustics and heat release rate are highly susceptible to coupling in ways that lead to sustained, high-amplitude pressure oscillations, known as combustion instability. At different operating conditions, different modes of instability are observed, corresponding to particular flame shapes and resonant acoustic modes. Here we show that in a swirl-stabilized combustor, these instability modes also correspond to particular interactions between the flame and the inner recirculation zone. Two stable and two unstable modes are examined. At lean equivalence ratios, a stable conical flame anchors on the upstream edge of the inner recirculation zone and extends several diameters downstream along the wall. At higher equivalence ratios, with the injection of counter-swirling microjet air flow, another stable flame is observed. This flame is anchored along the upstream edge of a stronger recirculation zone, extending less than one diameter downstream along the wall. Without the microjets, a stationary instability coupled to the 1/4 wave mode of the combustor shows weak velocity oscillations and a stable configuration of the inner and outer recirculation zones. Another instability, coupled to the 3/4 wave mode of the combustor, exhibits periodic vortex breakdown in which the core flow alternates between a columnar mode and a vortex breakdown mode. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.

Effect of Soret diffusion on lean hydrogen/air flames at normal and elevated pressure and temperature

KAUST Repository

Zhou, Zhen; Hernandez Perez, Francisco; Shoshin, Yuriy; van Oijen, Jeroen A.; de Goey, Laurentius P.H.

2017-01-01

The influence of Soret diffusion on lean premixed flames propagating in hydrogen/air mixtures is numerically investigated with a detailed chemical and transport models at normal and elevated pressure and temperature. The Soret diffusion influence on the one-dimensional (1D) flame mass burning rate and two-dimensional (2D) flame propagating characteristics is analysed, revealing a strong dependency on flame stretch rate, pressure and temperature. For 1D flames, at normal pressure and temperature, with an increase of Karlovitz number from 0 to 0.4, the mass burning rate is first reduced and then enhanced by Soret diffusion of H2 while it is reduced by Soret diffusion of H. The influence of Soret diffusion of H2 is enhanced by pressure and reduced by temperature. On the contrary, the influence of Soret diffusion of H is reduced by pressure and enhanced by temperature. For 2D flames, at normal pressure and temperature, during the early phase of flame evolution, flames with Soret diffusion display more curved flame cells. Pressure enhances this effect, while temperature reduces it. The influence of Soret diffusion of H2 on the global consumption speed is enhanced at elevated pressure. The influence of Soret diffusion of H on the global consumption speed is enhanced at elevated temperature. The flame evolution is more affected by Soret diffusion in the early phase of propagation than in the long run due to the local enrichment of H2 caused by flame curvature effects. The present study provides new insights into the Soret diffusion effect on the characteristics of lean hydrogen/air flames at conditions that are relevant to practical applications, e.g. gas engines and turbines.

Effect of Soret diffusion on lean hydrogen/air flames at normal and elevated pressure and temperature

KAUST Repository

Zhou, Zhen

2017-04-12

The influence of Soret diffusion on lean premixed flames propagating in hydrogen/air mixtures is numerically investigated with a detailed chemical and transport models at normal and elevated pressure and temperature. The Soret diffusion influence on the one-dimensional (1D) flame mass burning rate and two-dimensional (2D) flame propagating characteristics is analysed, revealing a strong dependency on flame stretch rate, pressure and temperature. For 1D flames, at normal pressure and temperature, with an increase of Karlovitz number from 0 to 0.4, the mass burning rate is first reduced and then enhanced by Soret diffusion of H2 while it is reduced by Soret diffusion of H. The influence of Soret diffusion of H2 is enhanced by pressure and reduced by temperature. On the contrary, the influence of Soret diffusion of H is reduced by pressure and enhanced by temperature. For 2D flames, at normal pressure and temperature, during the early phase of flame evolution, flames with Soret diffusion display more curved flame cells. Pressure enhances this effect, while temperature reduces it. The influence of Soret diffusion of H2 on the global consumption speed is enhanced at elevated pressure. The influence of Soret diffusion of H on the global consumption speed is enhanced at elevated temperature. The flame evolution is more affected by Soret diffusion in the early phase of propagation than in the long run due to the local enrichment of H2 caused by flame curvature effects. The present study provides new insights into the Soret diffusion effect on the characteristics of lean hydrogen/air flames at conditions that are relevant to practical applications, e.g. gas engines and turbines.

Solid oxide fuel cells and hydrogen production

International Nuclear Information System (INIS)

Dogan, F.

2009-01-01

'Full text': A single-chamber solid oxide fuel cell (SC-SOFC), operating in a mixture of fuel and oxidant gases, provides several advantages over the conventional SOFC such as simplified cell structure (no sealing required). SC-SOFC allows using a variety of fuels without carbon deposition by selecting appropriate electrode materials and cell operating conditions. The operating conditions of single chamber SOFC was studied using hydrocarbon-air gas mixtures for a cell composed of NiO-YSZ / YSZ / LSCF-Ag. The cell performance and catalytic activity of the anode was measured at various gas flow rates. The results showed that the open-circuit voltage and the power density increased as the gas flow rate increased. Relatively high power densities up to 660 mW/cm 2 were obtained in a SC-SOFC using porous YSZ electrolytes instead of dense electrolytes required for operation of a double chamber SOFC. In addition to propane- or methane-air mixtures as a fuel source, the cells were also tested in a double chamber configuration using hydrogen-air mixtures by controlling the hydrogen/air ratio at the cathode and the anode. Simulation of single chamber conditions in double chamber configurations allows distinguishing and better understanding of the electrode reactions in the presence of mixed gases. Recent research efforts; the effect of hydrogen-air mixtures as a fuel source on the performance of anode and cathode materials in single-chamber and double-chamber SOFC configurations,will be presented. The presentation will address a review on hydrogen production by utilizing of reversible SOFC systems. (author)

Numerical simulation of fuel sprays and combustion in a premixed lean diesel engine; Kihaku yokongo diesel kikan ni okeru nenryo funmu to nensho no suchi simulation

Energy Technology Data Exchange (ETDEWEB)

Miyamoto, T; Harada, A; Sasaki, S; Shimazaki, N; Hashizume, T; Akagawa, H; Tsujimura, K

1997-10-01

Fuel sprays and combustion in a direct injection Premixed lean Diesel Combustion (PREDIC) engine, which can make smokeless combustion with little NOx emission, is studied numerically. Numerical simulation was carried out by means of KIVA II based computer code with a combustion submodel. The combustion submodel describes the formation of combustible fuel vapor by turbulent mixing and four-step chemical reaction which includes low temperature oxidation. Comparison between computation and experiment shows qualitatively good agreement in terms of heat release rate and NO emission. Computational results indicate that the combustion is significantly influenced by fuel spray characteristics and injection timing to vary NO emission. 10 refs., 8 figs., 1 tab.

Development of an instantaneous local fuel-concentration measurement probe: an engine application

Science.gov (United States)

Guibert, P.; Boutar, Z.; Lemoyne, L.

2003-11-01

This work presents a new tool which can deliver instantaneous local measurements of fuel concentration in an engine cylinder with a high temporal resolution, particularly during compression strokes. Fuel concentration is represented by means of equivalence fuel-air ratio, i.e. the real engine mass ratio of fuel to air divided by the same ratio in ideal stoichiometry conditions. Controlling the mixture configuration for any strategy in a spark ignition engine and for auto-ignition combustion has a dominant effect on the subsequent processes of ignition, flame propagation and auto-ignition combustion progression, pollutant formation under lean or even stoichiometric operating conditions. It is extremely difficult, under a transient operation, to control the equivalence air/fuel ratio precisely at a required value and at the right time. This requires the development of a highly accurate equivalence air/fuel ratio control system and a tool to measure using crank angle (CA) resolution. Although non-intrusive laser techniques have considerable advantages, they are most of the time inappropriate due to their optical inaccessibility or the complex experimental set-up involved. Therefore, as a response to the demand for a relatively simple fuel-concentration measurement system a probe is presented that replaces a spark plug and allows the engine to run completely normally. The probe is based on hot-wire like apparatus, but involves catalytic oxidation at the wire surface. The development, characteristics and calibration of the probe are presented followed by applications to in-cylinder engine measurements.

Formation of polycyclic aromatic hydrocarbons and soot in fuel-rich oxidation of methane in a laminar flow reactor

DEFF Research Database (Denmark)

Skjøth-Rasmussen, Martin Skov; Glarborg, Peter; Østberg, M.

2004-01-01

Conversion of methane to higher hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and soot was investigated under fuel-rich conditions in a laminar flow reactor. The effects of stoichiometry, dilution, and water vapor addition were studied at temperatures between 1073 and 1823 K. A chemical...... kinetic mechanism was established for methane oxidation, with emphasis on formation of higher hydrocarbons and PAH. A submodel for soot formation was adopted from the work of Frenklach and co-workers without changes. Modeling predictions showed good agreement with experimental results. Reactants, stable...... decrease with increasing addition of water vapor. The effect is described qualitatively by the reaction mechanism. The enhanced oxidation of acetylene is attributed to higher levels of hydroxyl radicals, formed from the reaction between the water vapor and hydrogen atoms....

The Regional Special Operations Headquarters: Franchising the NATO Model as a Hedge in Lean Times

Science.gov (United States)

2012-04-01

1 AIR FORCE FELLOWS AIR UNIVERSITY THE REGIONAL SPECIAL OPERATIONS HEADQUARTERS: FRANCHISING THE NATO MODEL AS A HEDGE IN LEAN...Headquarters: Franchising The NATO Model As A Hedge In Lean Times 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...it is not copyrighted, but is the property of the United States government. 3 The Regional Special Operations Headquarters: Franchising the

Validation of landfill methane measurements from an unmanned aerial system

DEFF Research Database (Denmark)

Allen, Grant; Williams, Paul; Ricketts, hugo

Landfill gas is made up of roughly equal amounts of methane and carbon dioxide. Modern UK landfills capture and use much of the methane gas as a fuel. But some methane escapes and is emitted to the atmosphere. Methane is an important greenhouse gas and controls on methane emissions are a part...... of international and national strategies to limit climate change. Better estimates of methane emissions from landfills and other similar sources would allow the UK to improve the quantification and control of greenhouse gas emissions. This project tested the accuracy of methane measurement using an unmanned aerial...

Internal reforming of methane in solid oxide fuel cell systems

Science.gov (United States)

Peters, R.; Dahl, R.; Klüttgen, U.; Palm, C.; Stolten, D.

Internal reforming is an attractive option offering a significant cost reduction, higher efficiencies and faster load response of a solid oxide fuel cell (SOFC) power plant. However, complete internal reforming may lead to several problems which can be avoided with partial pre-reforming of natural gas. In order to achieve high total plant efficiency associated with low energy consumption and low investment costs, a process concept has been developed based on all the components of the SOFC system. In the case of anode gas recycling an internal steam circuit exists. This has the advantage that there is no need for an external steam generator and the steam concentration in the anode gas is reduced. However, anode gas recycling has to be proven by experiments in a pre-reformer and for internal reforming. The addition of carbon dioxide clearly shows a decrease in catalyst activity, while for temperatures higher than 1000 K hydrogen leads to an increase of the measured methane conversion rates.

Sustainable passenger road transport scenarios to reduce fuel consumption, air pollutants and GHG (greenhouse gas) emissions in the Mexico City Metropolitan Area

International Nuclear Information System (INIS)

Chavez-Baeza, Carlos; Sheinbaum-Pardo, Claudia

2014-01-01

This paper presents passenger road transport scenarios that may assist the MCMA (Mexico City Metropolitan Area) in achieving lower emissions in both criteria air pollutants (CO, NO x , NMVOC (non-methane volatile organic compounds), and PM 10 ) and GHG (greenhouse gas) (CH 4 , N 2 O and CO 2 ), while also promoting better mobility and quality of life in this region. We developed a bottom-up model to estimate the historical trends of energy demand, criteria air pollutants and GHG emissions caused by passenger vehicles circulating in the Mexico City Metropolitan Area (MCMA) in order to construct a baseline scenario and two mitigation scenarios that project their impact to 2028. Mitigation scenario “eff” considers increasing fuel efficiencies and introducing new technologies for vehicle emission controls. Mitigation scenario “BRT” considers a modal shift from private car trips to a Bus Rapid Transport system. Our results show significant reductions in air pollutants and GHG emissions. Incentives and environmental regulations are needed to enable these scenarios. - Highlights: • More than 4.2 million passenger vehicles in the MCMA (Mexico City Metropolitan Area) that represent 61% of criteria pollutants and 44% of GHG (greenhouse gas) emissions. • Emissions of CO, NO x and NMVOC (non-methane volatile organic compounds) in baseline scenario decrease with respect to its 2008 value because emission standards. • Emissions of PM 10 and GHG increase in baseline scenario. • Emissions of PM 10 and GHG decrease in eff + BRT scenario from year 2020. • Additional reductions are possible with better standards for diesel vehicles and other technologies

77 FR 36423 - Labeling Requirements for Alternative Fuels and Alternative Fueled Vehicles

Science.gov (United States)

2012-06-19

... delivered to the following address: Federal Trade Commission, Office of the Secretary, Room H-113 (Annex N... cell, advanced lean burn, and hybrid motor vehicles) that were added to the definition of ``alternative... legislation (i.e., lean burn, hybrid, and fuel cell vehicles). No comments opposed this approach. Edison...

Comparative SIFT-MS, GC-MS and FTIR analysis of methane fuel produced in biogas stations and in artificial photosynthesis over acidic anatase TiO2 and montmorillonite

Science.gov (United States)

Knížek, Antonín; Dryahina, Ksenyia; Španěl, Patrik; Kubelík, Petr; Kavan, Ladislav; Zukalová, Markéta; Ferus, Martin; Civiš, Svatopluk

2018-06-01

The era of fossil fuels is slowly nearing its inevitable end and the urgency of alternative energy sources basic research, exploration and testing becomes ever more important. Storage and alternative production of energy from fuels, such as methane, represents one of the many alternative approaches. Natural gas containing methane represents a powerful source of energy producing large volume of greenhouse gases. However, methane can be also produced in closed, CO2-neutral cycles. In our study, we compare detailed chemical composition of CH4 fuel produced in two different processes: Classical production of biogas in a rendering station, industrial wastewater treatment station and landfill gas station together with novel approach of artificial photosynthesis from CO2 over acidic anatase TiO2 in experimental apparatus developed in our laboratory. The analysis of CH4 fuel produced in these processes is important. Trace gaseous traces can be for example corrosive or toxic, low quality of the mixture suppresses effectivity of energy production, etc. In this analysis, we present a combination of two methods: High resolution Fourier transform infrared spectroscopy (HR-FTIR) suitable for the main component analysis; and the complementary extremely sensitive method of Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) and gas chromatography (GC-MS), which are in turn best suited for trace analysis. The combination of these methods provides more information than any single of them would be able to and promises a new possible analytical approach to fuel and gaseous mixture analysis.

Higher fuel prices are associated with lower air pollution levels.

Science.gov (United States)

Barnett, Adrian G; Knibbs, Luke D

2014-05-01

Air pollution is a persistent problem in urban areas, and traffic emissions are a major cause of poor air quality. Policies to curb pollution levels often involve raising the price of using private vehicles, for example, congestion charges. We were interested in whether higher fuel prices were associated with decreased air pollution levels. We examined an association between diesel and petrol prices and four traffic-related pollutants in Brisbane from 2010 to 2013. We used a regression model and examined pollution levels up to 16 days after the price change. Higher diesel prices were associated with statistically significant short-term reductions in carbon monoxide and nitrogen oxides. Changes in petrol prices had no impact on air pollution. Raising diesel taxes in Australia could be justified as a public health measure. As raising taxes is politically unpopular, an alternative political approach would be to remove schemes that put a downward pressure on fuel prices, such as industry subsidies and shopping vouchers that give fuel discounts. Copyright © 2014 Elsevier Ltd. All rights reserved.

Top-down constraints on methane and non-methane hydrocarbon emissions in the US Four Corners

Science.gov (United States)

Petron, G.; Miller, B. R.; Vaughn, B. H.; Kofler, J.; Mielke-Maday, I.; Sherwood, O.; Schwietzke, S.; Conley, S.; Sweeney, C.; Dlugokencky, E. J.; White, A. B.; Tans, P. P.; Schnell, R. C.

2017-12-01

A NASA and NOAA supported field campaign took place in the US Four Corners in April 2015 to further investigate a regional "methane hotspot" detected from space. The Four Corners region is home to the fossil fuel rich San Juan Basin, which extends between SE Colorado and NE New Mexico. The area has been extracting coal, oil and natural gas for decades. Degassing from the Fruitland coal outcrop on the Colorado side has also been reported. Instrumented aircraft, vans and ground based wind profilers were deployed for the campaign with the goal to quantify and attribute methane and non-methane hydrocarbon emissions in the region. A new comprehensive analysis of the campaign data sets will be presented and top-down emission estimates for methane and ozone precursors will be compared with available bottom-up estimates.

Dynamic Data-Driven Prediction of Lean Blowout in a Swirl-Stabilized Combustor

Directory of Open Access Journals (Sweden)

Soumalya Sarkar

2015-09-01

Full Text Available This paper addresses dynamic data-driven prediction of lean blowout (LBO phenomena in confined combustion processes, which are prevalent in many physical applications (e.g., land-based and aircraft gas-turbine engines. The underlying concept is built upon pattern classification and is validated for LBO prediction with time series of chemiluminescence sensor data from a laboratory-scale swirl-stabilized dump combustor. The proposed method of LBO prediction makes use of the theory of symbolic dynamics, where (finite-length time series data are partitioned to produce symbol strings that, in turn, generate a special class of probabilistic finite state automata (PFSA. These PFSA, called D-Markov machines, have a deterministic algebraic structure and their states are represented by symbol blocks of length D or less, where D is a positive integer. The D-Markov machines are constructed in two steps: (i state splitting, i.e., the states are split based on their information contents, and (ii state merging, i.e., two or more states (of possibly different lengths are merged together to form a new state without any significant loss of the embedded information. The modeling complexity (e.g., number of states of a D-Markov machine model is observed to be drastically reduced as the combustor approaches LBO. An anomaly measure, based on Kullback-Leibler divergence, is constructed to predict the proximity of LBO. The problem of LBO prediction is posed in a pattern classification setting and the underlying algorithms have been tested on experimental data at different extents of fuel-air premixing and fuel/air ratio. It is shown that, over a wide range of fuel-air premixing, D-Markov machines with D > 1 perform better as predictors of LBO than those with D = 1.

A Novel Hybrid-Fuel Storage System of Compressed Air Energy for China

Directory of Open Access Journals (Sweden)

Wenyi Liu

2014-08-01

Full Text Available Compressed air energy storage (CAES is a large-scale technology that provides long-duration energy storage. It is promising for balancing the large-scale penetration of intermittent and dispersed sources of power, such as wind and solar power, into electric grids. The existing CAES plants utilize natural gas (NG as fuel. However, China is rich in coal but is deficient in NG; therefore, a hybrid-fuel CAES is proposed and analyzed in this study. Based on the existing CAES plants, the hybrid-fuel CAES incorporates an external combustion heater into the power generation subsystem to heat the air from the recuperator and the air from the high-pressure air turbine. Coal is the fuel for the external combustion heater. The overall efficiency and exergy efficiency of the hybrid-fuel CAES are 61.18% and 59.84%, respectively. Given the same parameters, the cost of electricity (COE of the hybrid-fuel CAES, which requires less NG, is $5.48/MW∙h less than that of the gas-fuel CAES. Although the proposed CAES requires a relatively high investment in the current electricity system in North China, the proposed CAES will be likely to become competitive in the market, provided that the energy supplies are improved and the large scale grid-connection of wind power is realized.

The lean-combustion gasoline engine. A concept with global application; Der magerbetriebene Ottomotor. Ein Konzept fuer den weltweiten Einsatz

Energy Technology Data Exchange (ETDEWEB)

Kemmler, Roland; Enderle, Christian; Waltner, Anton; Vent, Guido [Daimler AG, Stuttgart (Germany)

2013-08-01

After Mercedes-Benz launched the first lean-combustion gasoline engines with spray-guided combustion in 2006, it rolled out this technology on a broad level based on the engine model series featuring the BlueDIRECT combustion system. Although these engines raise the bar among competitors in terms of fuel consumption, they are currently available only in countries that offer sulfur-free fuel. This leads to the question of what technical measures or altered constraints would be necessary to allow this environmentally-friendly technology to enjoy more widespread use. The following paper discusses how the accessibility of the lean-combustion technology can be improved by focusing primarily on the USA and China as potential markets. Challenges are involved, of course, in particular with respect to fuel quality and emissions as well as the market-specific implications for on-board diagnostics. By working to further reduce fuel sulfur content, however, lean-combustion gasoline engines could also be offered in the aforementioned regions in the mid-term. (orig.)

Lean-burn stratified combustion at gasoline engines; Magere Schichtverbrennung beim Ottomotor

Energy Technology Data Exchange (ETDEWEB)

Breitbach, Hermann [Daimler AG, Stuttgart (Germany). Entwicklung Einspritzung und Betriebsstoffe; Waltner, Anton [Daimler AG, Stuttgart (Germany). Verbrennungsentwicklung Pkw-Ottomotoren; Landenfeld, Tilo [Robert Bosch GmbH, Schwieberdingen (Germany). Hochdruckeinspritzung Piezo; Porten, Guido [Robert Bosch GmbH, Schwieberdingen (Germany). Systementwicklung Benzindirekteinspritzung

2013-05-01

Spray-guided lean-burn combustion is an integral part of the Mercedes-Benz technology strategy for highly efficient and clean gasoline engines. With regard to the excellent fuel efficiency combined with outstanding specific power, a good combustion system robustness and the low particulate emissions, the concept offers a very good cost/benefit ratio especially for the Euro 6 emission legislation. Thus, Mercedes-Benz believes, that the sprayguided lean-burn combustion offers the by far highest future viability of gasoline engine combustion systems.

Nanostructured palladium-La{sub 0.75}Sr{sub 0.25}Cr{sub 0.5}Mn{sub 0.5}O{sub 3}/Y{sub 2}O{sub 3}-ZrO{sub 2} composite anodes for direct methane and ethanol solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Jiang, San Ping; Ye, Yinmei; He, Tianmin; Ho, See Boon [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2008-10-15

A palladium-impregnated La{sub 0.75}Sr{sub 0.25}Cr{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}}/yttria-stabilized zirconia (LSCM/YSZ) composite anode is investigated for the direct utilization of methane and ethanol fuels in solid oxide fuel cells (SOFCs). Impregnation of Pd nanoparticles significantly enhances the electrocatalytic activity of LSCM/YSZ composite anodes for the methane and ethanol electrooxidation reaction. At 800 C, the maximum power density is increased by two and eight times with methane and ethanol fuels, respectively, for a cell with the Pd-impregnated LSCM/YSZ composite anode, as compared with that using a pure LSCM/YSZ anode. No carbon deposition is observed during the reaction of methane and ethanol fuels on the Pd-impregnated LSCM/YSZ composite anode. The results show the promises of nanostructured Pd-impregnated LSCM/YSZ composites as effective anodes for direct methane and ethanol SOFCs. (author)

The Effect of Air Preheat at Atmospheric Pressure on the Formation of NO(x) in the Quick-Mix Sections of an Axially Staged Combustor

Science.gov (United States)

Vardakas, M. A.; Leong, M. Y.; Brouwer, J.; Samuelsen, G. S.; Holdeman, J. D.

1999-01-01

The Rich-burn/Quick-mix/Lean-burn (RQL) combustor concept has been proposed to minimize the formation of nitrogen oxides (NO(x)) in gas turbine systems. The success of this combustor strategy is dependent upon the efficiency of the mixing section bridging the fuel-rich and fuel-lean stages. Note that although these results were obtained from an experiment designed to study an RQL mixer, the link between mixing and NOx signatures is considerably broader than this application, in that the need to understand this link exists in most advanced combustors. The experiment reported herein was designed to study the effects of inlet air temperature on NO(x) formation in a mixing section. The results indicate that NO(x) emission is increased for all preheated cases compared to non-preheated cases. When comparing the various mixing modules, the affect of jet penetration is important, as this determines where NO(x) concentrations peak, and affects overall NO(x) production. Although jet air comprises 70 percent of the total airflow, the impact that jet air preheat has on overall NO(x) emissions is small compared to preheating both main and jet air flow.

New insights into methane-oxygen ion chemistry

KAUST Repository

Alquaity, Awad B.S.; Chen, Bingjie; Han, Jie; Selim, Hatem; Belhi, Memdouh; Karakaya, Yasin; Kasper, Tina; Sarathy, Mani; Bisetti, Fabrizio; Farooq, Aamir

2016-01-01

External electric fields may reduce emissions and improve combustion efficiency by active control of combustion processes. In-depth, quantitative understanding of ion chemistry in flames enables predictive models to describe the effect of external electric fields on combustion plasma. This study presents detailed cation profile measurements in low-pressure, burner-stabilized, methane/oxygen/argon flames. A quadrupole molecular beam mass spectrometer (MBMS) coupled to a low-pressure (P =30Torr) combustion chamber was utilized to measure ion signals as a function of height above the burner. Lean, stoichiometric and rich flames were examined to evaluate the dependence of ion chemistry on flame stoichiometry. Additionally, for the first time, cataloging of flame cations is performed using a high mass resolution time-of-flight mass spectrometer (TOF-MS) to distinguish ions with the same nominal mass. In the lean and stoichiometric flames, the dominant ions were HO, CHO , CHO, CHO and CHO, whereas large signals were measured for HO, CH and CHO in the rich flame. The spatial distribution of cations was compared with results from numerical simulations constrained by thermocouple-measured flame temperatures. Across all flames, the predicted HO decay rate was noticeably faster than observed experimentally. Sensitivity analysis showed that the mole fraction of HO is most sensitive to the rate of chemi-ionization CH+O↔CHO +E. To our knowledge, this work represents the first detailed measurements of positive ions in canonical low-pressure methane flames.

New insights into methane-oxygen ion chemistry

KAUST Repository

Alquaity, Awad B.S.

2016-06-15

External electric fields may reduce emissions and improve combustion efficiency by active control of combustion processes. In-depth, quantitative understanding of ion chemistry in flames enables predictive models to describe the effect of external electric fields on combustion plasma. This study presents detailed cation profile measurements in low-pressure, burner-stabilized, methane/oxygen/argon flames. A quadrupole molecular beam mass spectrometer (MBMS) coupled to a low-pressure (P =30Torr) combustion chamber was utilized to measure ion signals as a function of height above the burner. Lean, stoichiometric and rich flames were examined to evaluate the dependence of ion chemistry on flame stoichiometry. Additionally, for the first time, cataloging of flame cations is performed using a high mass resolution time-of-flight mass spectrometer (TOF-MS) to distinguish ions with the same nominal mass. In the lean and stoichiometric flames, the dominant ions were HO, CHO , CHO, CHO and CHO, whereas large signals were measured for HO, CH and CHO in the rich flame. The spatial distribution of cations was compared with results from numerical simulations constrained by thermocouple-measured flame temperatures. Across all flames, the predicted HO decay rate was noticeably faster than observed experimentally. Sensitivity analysis showed that the mole fraction of HO is most sensitive to the rate of chemi-ionization CH+O↔CHO +E. To our knowledge, this work represents the first detailed measurements of positive ions in canonical low-pressure methane flames.

Airborne methane remote measurements reveal heavy-tail flux distribution in Four Corners region.

Science.gov (United States)

Frankenberg, C.

2016-12-01

Methane (CH4) impacts climate as the second strongest anthropogenic greenhouse gas and air quality by influencing tropospheric ozone levels. Space-based observations have identified the Four Corners region in the Southwest United States as an area of large CH4 enhancements. We conducted an airborne campaign in Four Corners during April 2015 with the next-generation Airborne Visible/Infrared Imaging Spectrometer (near-infrared) and Hyperspectral Thermal Emission Spectrometer (thermal infrared) imaging spectrometers to better understand the source of methane by measuring methane plumes at 1- to 3-m spatial resolution. Our analysis detected more than 250 individual methane plumes from fossil fuel harvesting, processing, and distributing infrastructures, spanning an emission range from the detection limit ˜ 2 kg/h to 5 kg/h through ˜ 5,000 kg/h. Observed sources include gas processing facilities, storage tanks, pipeline leaks, natural seeps and well pads, as well as a coal mine venting shaft. Overall, plume enhancements and inferred fluxes follow a lognormal distribution, with the top 10% emitters contributing 49 to 66% to the inferred total point source flux of 0.23 Tg/y to 0.39 Tg/y. We will summarize the campaign results and provide an overview of how airborne remote sensing can be used to detect and infer methane fluxes over widespread geographic areas and how new instrumentation could be used to perform similar observations from space.

Methane flux to the atmosphere from the Deepwater Horizon oil disaster

Science.gov (United States)

Yvon-Lewis, Shari A.; Hu, Lei; Kessler, John

2011-01-01

The sea-to-air flux of methane from the blowout at the Deepwater Horizon was measured with substantial spatial and temporal resolution over the course of seven days in June 2010. Air and water concentrations were analyzed continuously from a flowing air line and a continuously flowing seawater equilibrator using cavity ring-down spectrometers (CRDS) and a gas chromatograph with a flame ionization detector (GC-FID). The results indicate a low flux of methane to the atmosphere (0.024 μmol m-2 d-1) with atmospheric and seawater equilibrium mixing ratios averaging 1.86 ppm and 2.85 ppm, respectively within the survey area. The oil leak, which was estimated to contain 30.2% methane by weight, was not a significant source of methane to the atmosphere during this study. Most of the methane emitted from the wellhead was dissolved in the deep ocean.

Methane flaring: an initiative in line with the greenhouse challenge

International Nuclear Information System (INIS)

Greenwood, D.

1999-01-01

Methane is a by-product of the coalification process. Once produced, it typically remains trapped within the coal seam and the surrounding strata. High quality black coals in Australia may contain up to 20 m 3 of methane per tonne of coal. In order to mine coal safely, this gas level must be reduced. Presence of gas at the coal face is a hazard as sparks created by coal extraction machine picks may ignite the gas/air mix. Concentrations of methane between approximately 5% and 15% in air create an explosive mixture. This represents a considerable potential safety risk for underground mining personnel. In Queensland, all underground mining personnel and equipment are protected by sensors that remove electrical power from machines should the ambient methane levels exceed 1.25%. While this assists in creating a safe working environment, it also halts coal production. Normal mine ventilation air removes a significant amount of methane, however in gassy mines the ventilation air flow required to maintain methane levels below the 1.25% limit can introduce other problems. These include excess airborne dust, which can lead to respiratory issues and poor visibility. A flare was installed at Central Colliery to achieve reduction of the greenhouse gas emissions. It would also be used to burn gas flow beyond that which can be effectively utilised by power generation

Sustainable application of reciprocating gas engines operating on coal mine methane

Energy Technology Data Exchange (ETDEWEB)

Lee, J.; Teo, T. [Caterpillar China Investment Co., Beijing (China); Tnay, C.H. [Westrac Inc., Beijing (China)

2008-07-01

According to the World Coal Institute, coal provides 25 per cent of worldwide primary energy needs and generates 40 per cent of the world's electricity. China produces the largest amount of hard coal. The anthropogenic release of methane (CH{sub 4}) into the environment is a byproduct of the coal mining process. The global warming potential of this methane continues to draw attention around the world. In particular, China's government has recognized the need for environmental responsibility in the pursuit of greater power production. The Kyoto Protocol requires developed countries to reduce their greenhouse gas emissions and targets must be met within a five-year time frame between 2008 and 2012. Sequestering coal mine methane (CMM) as an alternative fuel for reciprocating gas engine generator sets is a mature and proven technology for greenhouse gas mitigation. Prior to commissioning CMM-fueled power systems, the methane gas composition must be evaluated. An integrated systems approach can then be used to develop a CMM-fueled power project. This paper discussed the sustainable application of reciprocating gas engines operating on coal mine methane. It discussed the Kyoto Protocol, clean development mechanism, and CMM as compared to other fuel sources. It was concluded that there is considerable opportunity for growth in the Asia-Pacific region for electric power applications using CMM. 4 refs., 12 figs.

Oxygen-Methane Thruster, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Orion Propulsion, Inc. proposes to develop an Oxygen and Methane RCS Thruster to advance the technology of alternate fuels. A successful Oxygen/CH4 RCS Thruster will...

Effect of different fuel options on performance of high-temperature PEMFC (proton exchange membrane fuel cell) systems

International Nuclear Information System (INIS)

Authayanun, Suthida; Saebea, Dang; Patcharavorachot, Yaneeporn; Arpornwichanop, Amornchai

2014-01-01

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) have received substantial attention due to their high CO (carbon monoxide) tolerance and simplified water management. The hydrogen and CO fractions affect the HT-PEMFC performance and different fuel sources for hydrogen production result in different product gas compositions. Therefore, the aim of this study is to investigate the theoretical performance of HT-PEMFCs fueled by the reformate gas derived from various fuel options (i.e., methane, methanol, ethanol, and glycerol). Effects of fuel types and CO poisoning on the HT-PEMFC performance are analyzed. Furthermore, the necessity of a water-gas shift (WGS) reactor as a CO removal unit for pretreating the reformate gas is investigated for each fuel type. The methane steam reforming shows the highest possibility of CO formation, whereas the methanol steam reforming produces the lowest quantity of CO in the reformate gas. The methane fuel processing gives the maximum fraction of hydrogen (≈0.79) when the WGS reactor is included. The most suitable fuel is the one with the lowest CO poisoning effect and the maximum fuel cell performance. It is found that the HT-PEMFC system fueled by methanol without the WGS reactor and methane with WGS reactor shows the highest system efficiency (≈50%). - Highlights: • Performance of HT-PEMFC run on different fuel options is theoretically investigated. • Glycerol, methanol, ethanol and methane are hydrogen sources for the HT-PEMFC system. • Effect of CO poisoning on the HT-PEMFC performance is taken into account. • The suitable fuel for HT-PEMFC system is identified regarding the system efficiency

Methane storage in metal-organic frameworks.

Science.gov (United States)

He, Yabing; Zhou, Wei; Qian, Guodong; Chen, Banglin

2014-08-21

Natural gas (NG), whose main component is methane, is an attractive fuel for vehicular applications. Realization of safe, cheap and convenient means and materials for high-capacity methane storage can significantly facilitate the implementation of natural gas fuelled vehicles. The physisorption based process involving porous materials offers an efficient storage methodology and the emerging porous metal-organic frameworks have been explored as potential candidates because of their extraordinarily high porosities, tunable pore/cage sizes and easily immobilized functional sites. In this view, we provide an overview of the current status of metal-organic frameworks for methane storage.

Computer program for obtaining thermodynamic and transport properties of air and products of combustion of ASTM-A-1 fuel and air

Science.gov (United States)

Hippensteele, S. A.; Colladay, R. S.

1978-01-01

A computer program for determining desired thermodynamic and transport property values by means of a three-dimensional (pressure, fuel-air ratio, and either enthalpy or temperature) interpolation routine was developed. The program calculates temperature (or enthalpy), molecular weight, viscosity, specific heat at constant pressure, thermal conductivity, isentropic exponent (equal to the specific heat ratio at conditions where gases do not react), Prandtl number, and entropy for air and a combustion gas mixture of ASTM-A-1 fuel and air over fuel-air ratios from zero to stoichiometric, pressures from 1 to 40 atm, and temperatures from 250 to 2800 K.

An experimental study of a hydrogen-enriched ethanol fueled Wankel rotary engine at ultra lean and full load conditions

International Nuclear Information System (INIS)

Amrouche, F.; Erickson, P.A.; Varnhagen, S.; Park, J.W.

2016-01-01

Highlights: • H_2 was added at the intake of a single-rotor ethanol fueled Wankel engine. • The engine was operating at ultra-lean condition, WOT and 3000 rpm. • H_2 enrichment helps shortening the burn duration, enhance the thermal efficiency and reduce the BSEC. • H_2 addition helps to reduce HC, CO and CO_2 emissions. - Abstract: In this paper, the effect of hydrogen addition to ethanol in a monorotor Wankel engine at wide open throttle position and in an ultra-lean operating regime was experimentally investigated. For this aim, variation of hydrogen enrichment levels on the ethanol engine performance and emissions were considered. Experiments were carried out under a constant engine speed of 3000 rpm and fixed spark timing of 15 °BTDC. The test results showed that hydrogen enrichment improved the combustion process through shortening of the flame development and flame propagation periods and reducing the cyclic variation. Furthermore, the reduction of burn duration with the increase of hydrogen fraction enhances the thermal efficiency, reducing the brake-specific energy consumption, as well as reducing the unburned hydrocarbons emissions of the Wankel engine.

Determining the optimum conditions for modified diesel fuel combustion considering its emission, properties and engine performance

International Nuclear Information System (INIS)

Fayyazbakhsh, Ahmad; Pirouzfar, Vahid

2016-01-01

Highlights: • Gas emissions, fuel properties and performance engine modeling. • Optimization of new modified fuel prepared from n-Butanol and Nano particles. • Model accuracy analysis. - Abstract: This essay scrutinizes an experimental study conducted to appraise the influence of using n-Butanol with diesel fuel in 5% and 10% (volume) n-Butanol, 1% nitro methane (NM), injection timing and two Nano-particles (alumina and a type of silica powder) on the engine performance (brake specific fuel consumption and engine power), fuel properties (Cetane number and flash point) and exhaust emissions (soot, NO_x and CO) of an engine with 4-cylinder (with a system of common rail fuel injection), intercooling, cooled exhaust gas recirculation (EGR), and turbocharged. The tests are conducted by varying the engine load (25 and 75 nm) and changing engine speed (1500 and 2200 rpm). Normal Butanol presents better brake specific fuel consumption (BSFC) but this blend doesn’t reflect better engine power. All the percentages of n-Butanol in the fuel make Cetane number decrease but adding 1% of nitro methane makes Cetane number increase. For all the n-Butanol, the percentage flash makes the fuel decrease in comparison to pure diesel fuel. The current experimental study demonstrates that adding the n-Butanol and nitro methane to diesel fuel direct into diminishing soot emission. In contrast, this blend raises NO_x and CO emissions. Furthermore, this research indicates that the increase of engine speed dwindle air pollutants and enhances BSFC. It also remarks that power gets increased at low engine speed. However, power gets reducedat high speed. This article represents that the increasing of engine load leads to increasing all of air pollutant, increasing of power and decreasing of brake specific fuel consumption. Both the Cetane number and flash point are independent from engine speed and engine load. The present paper shows that the effect of silica with high percentage of n

Lean-burn engines UHC emission reduction

Energy Technology Data Exchange (ETDEWEB)

Karll, B.; Kristensen, P.G.; Nielsen, M.; Iskov, H. [Danish Gas Technology Centre a/s (Denmark); Broe Bendtsen, A.; Glarborg, P.; Dam-Johansen, K. [Technical University of Denmark. CHEC, Department of Chemical Engineering (Denmark)

1999-04-01

The effect of adding hydrogen to methane as a fuel for spark ignited engines has been extensively investigated. Both the possibility of adding a limited amount of hydrogen as well as equal amounts of hydrogen and carbon dioxide to natural gas has been investigated. A 10 vol% addition of hydrogen to the natural gas caused a reduction in UHC of approximately 40%, and an increase in efficiency of approximately three percentage points at the test engine. It is unknown if the gain is representative for large engines. Similar results for UHC reduction and efficiency were obtained for combined hydrogen and carbon dioxide addition. The carbon dioxide was added by exhaust gas recirculation. However, the price of hydrogen, makes this idea uneconomical even when carbon dioxide is readily available through recirculation of engine exhaust. Adiabatic prereforming may be used to convert natural gas into methane, hydrogen and carbon dioxide in order to generate hydrogen and at the same time increase the methane number. The process has been found to be competitive with adding of hydrogen but it is still not economical. The effect of NO/NO{sub 2} on methane oxidation has been studied both theoretically and experimentally. A detailed kinetic modelling study of the UHC conversion dependency of exhaust gas parameters is reported and the project has contributed to the theoretical understanding of the oxidation chemistry. Both NO and NH{sub 3} addition to the engine inlet was used to increase the NO{sub x} level, and the general trend was a decrease in UHC as the NO{sub x} level increased, both in cylinger, manifold and rector. From the data it is concluded that NO and NH{sub 3} addition have identical effects. The results show a 15-35% decrease in manifold UHC. However, the increased emissions of NO{sub x} and CO associated with this process must be realised. Field tests show a 28% UHC reduction without an increase in CO emission. The UHC oxidation in the exhaust reactor has been tested

Lean-burn engines UHC emission reduction

International Nuclear Information System (INIS)

Karll, B.; Kristensen, P.G.; Nielsen, M.; Iskov, H.; Broe Bendtsen, A.; Glarborg, P.; Dam-Johansen, K.

1999-01-01

The effect of adding hydrogen to methane as a fuel for spark ignited engines has been extensively investigated. Both the possibility of adding a limited amount of hydrogen as well as equal amounts of hydrogen and carbon dioxide to natural gas has been investigated. A 10 vol% addition of hydrogen to the natural gas caused a reduction in UHC of approximately 40%, and an increase in efficiency of approximately three percentage points at the test engine. It is unknown if the gain is representative for large engines. Similar results for UHC reduction and efficiency were obtained for combined hydrogen and carbon dioxide addition. The carbon dioxide was added by exhaust gas recirculation. However, the price of hydrogen, makes this idea uneconomical even when carbon dioxide is readily available through recirculation of engine exhaust. Adiabatic prereforming may be used to convert natural gas into methane, hydrogen and carbon dioxide in order to generate hydrogen and at the same time increase the methane number. The process has been found to be competitive with adding of hydrogen but it is still not economical. The effect of NO/NO 2 on methane oxidation has been studied both theoretically and experimentally. A detailed kinetic modelling study of the UHC conversion dependency of exhaust gas parameters is reported and the project has contributed to the theoretical understanding of the oxidation chemistry. Both NO and NH 3 addition to the engine inlet was used to increase the NO x level, and the general trend was a decrease in UHC as the NO x level increased, both in cylinger, manifold and rector. From the data it is concluded that NO and NH 3 addition have identical effects. The results show a 15-35% decrease in manifold UHC. However, the increased emissions of NO x and CO associated with this process must be realised. Field tests show a 28% UHC reduction without an increase in CO emission. The UHC oxidation in the exhaust reactor has been tested at increased NO x levels and

The option study of air shipment of DUPIC fuel elements to Canada

International Nuclear Information System (INIS)

Lee, H. H.; Park, J. J.; Shin, J. M.; Kim, J. H.; Yang, M. S.; Koo, J. H.

2003-01-01

KAERI developed a DUPIC nuclear fuel with the refabrication of spent PWR fuel discharged from domestic nuclear power plant by a dry process at M6 hot-cell in IMEF. To verify the performance of DUPIC nuclear fuel, irradiation test at operating conditions of commercially operating power plant is essential. Since the HANARO research reactor of KAERI does not have Fuel Test Loop(FTL) for irradiating nuclear fuel under high temperature and high pressure conditions, DUPIC fuel cannot be irradiated in the FTL of HANARO until about 2008. In the 13-th PRM among Korea, Canada, USA and IAEA, AECL proposed that KAERI fabricated DUPIC fuel can be irradiated in the FTL of the NRU research reactor without charge of neutrons. The transportation quantity of DUPIC fuel to Canada is 10 elements(about 6 kg). This transportation package is classified as the 7-th class according to 'recommendation on the transport of dangerous goods' made by the United Nations. Air shipment was investigated as a promising option because it is generally understood that air shipment is more appropriate than ship shipment for transportation of small quantity of nuclear materials from the perspectives of cost and transportation period. In case of air shipment, the IATA regulations have been more intensified since the July of 2001. To make matters worse, it becomes more difficult to get the ratification of corresponding authorities due to 9.11 terror. It was found that at present there is no proper air transportation cask for DUPIC fuel. So, air transportation is considered to be impossible. An alternative of using the exemption limit of fissile material was reviewed. Its results showed that in case of going via USA territory, approvals from US DOT should be needed. The approvals include shipping and cask approvals on technical cask testing. Furthermore, since passes through territories of Japan and Russia have to be done in case of using a regular air cargo from Korea to Canada, approvals from Russia and

Solar hydrogen production: renewable hydrogen production by dry fuel reforming

Science.gov (United States)

Bakos, Jamie; Miyamoto, Henry K.

2006-09-01

SHEC LABS - Solar Hydrogen Energy Corporation constructed a pilot-plant to demonstrate a Dry Fuel Reforming (DFR) system that is heated primarily by sunlight focusing-mirrors. The pilot-plant consists of: 1) a solar mirror array and solar concentrator and shutter system; and 2) two thermo-catalytic reactors to convert Methane, Carbon Dioxide, and Water into Hydrogen. Results from the pilot study show that solar Hydrogen generation is feasible and cost-competitive with traditional Hydrogen production. More than 95% of Hydrogen commercially produced today is by the Steam Methane Reformation (SMR) of natural gas, a process that liberates Carbon Dioxide to the atmosphere. The SMR process provides a net energy loss of 30 to 35% when converting from Methane to Hydrogen. Solar Hydrogen production provides a 14% net energy gain when converting Methane into Hydrogen since the energy used to drive the process is from the sun. The environmental benefits of generating Hydrogen using renewable energy include significant greenhouse gas and criteria air contaminant reductions.

Fiscal 1999 research cooperation project. Research cooperation on community-oriented practical photovoltaic power systems (Practical methane gas fermentation fuel cell power systems); 1999 nendo metan hakko gas nenryo denchi hatsuden system no jitsuyoka ni kansuru kenkyu kyoryoku

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-03-01

This report describes the research cooperation with developing countries on practical methane gas fermentation fuel cell power systems in 1999-2002. This research aims to construct the methane gas fermentation fuel cell power facility using livestock excreta which can supply power to the facility and peripheral areas. The facility controls various substance concentrations in waste water within environmental standards, and uses waste as compost. This project is very promising in use of environment-friendly energy, effective use of unused energy and power supply to unelectrified areas for China under serious conditions such as rapid increase in energy demand and various environment problems. There are such various issues to achieve this target as securing livestock (pig breeders) and excreta, and fermentation and recovery of suitable methane gas necessary for fuel cell power systems from excreta. This report is composed of 2 parts, (1) Current use of energy resources and use of unused energy in Guangdong province, and (2) Technical requirements for practical methane gas fermentation fuel cell power systems. (NEDO)

Cruising in afterburner: Air force fuel use and emerging energy policy

International Nuclear Information System (INIS)

Lucia, David J.

2011-01-01

Operational and mission efficiency were estimated for Air Force fighters, bombers and transports from fuel use data from 2001 through 2008 as reported in the Air Force Total Cost of Ownership (AFTOC) database. This analysis estimated efficiency in terms of the best performance theoretically possible for each platform based upon the energy available in the fuel expended. Operational efficiency considered aircraft operations in general, without regard for the type of mission. Mission efficiency only considered use of allocated fuel for combat (non-training) sorties. The cost associated with fuel inefficiency of the combined fighter, bomber and tanker force were estimated based on the fiscal year 2008 costs of fuel, fully burdened to include the cost of aerial refueling. The total cost of operational inefficiency was estimated at $5 billion per year. The fully burdened cost of mission inefficiency added an additional $3.6 billion for a total per year cost estimate of $8.6 billion. This represents 21.5% of the $40 billion portion of the 2009 budget dedicated to modernization. A business case for force-structure change is presented, which describes how these cost savings can be leveraged for modernization. - Highlights: → I assess how efficiently the United States Air Force uses fuel for aviation. → I estimate the cost associated with fuel inefficiency. → Improved technology can dramatically improve fuel efficiency. → There is potentially a large cost savings associated with improved fuel efficiency. → I present a business case to leverage this cost savings for modernization.

Effects of Fuel and Nozzle Characteristics on Micro Gas Turbine System: A Review

Science.gov (United States)

Akasha Hashim, Muhammad; Khalid, Amir; Salleh, Hamidon; Sunar, Norshuhaila Mohamed

2017-08-01

For many decades, gas turbines have been used widely in the internal combustion engine industry. Due to the deficiency of fossil fuel and the concern of global warming, the used of bio-gas have been recognized as one of most clean fuels in the application of engine to improve performance of lean combustion and minimize the production of NOX and PM. This review paper is to understand the combustion performance using dual-fuel nozzle for a micro gas turbine that was basically designed as a natural gas fuelled engine, the nozzle characteristics of the micro gas turbine has been modelled and the effect of multi-fuel used were investigated. The used of biogas (hydrogen) as substitute for liquid fuel (methane) at constant fuel injection velocity, the flame temperature is increased, but the fuel low rate reduced. Applying the blended fuel at constant fuel rate will increased the flame temperature as the hydrogen percentages increased. Micro gas turbines which shows the uniformity of the flow distribution that can be improved without the increase of the pressure drop by applying the variable nozzle diameters into the fuel supply nozzle design. It also identifies the combustion efficiency, better fuel mixing in combustion chamber using duel fuel nozzle with the largest potential for the future. This paper can also be used as a reference source that summarizes the research and development activities on micro gas turbines.

PARAMETERS OF AIR FIRED BOILER FED WITH DIFFERENT TYPES OF FUEL

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Katarzyna Joanna Gładyszewska-Fiedoruk

2016-09-01

Full Text Available The measurement and interpretation of indoor carbon dioxide CO2 concentration can provide information on building indoor air quality and ventilation. On the other hand, concentration of carbon monoxide CO can show as how combustion process run and if the boiler is safe. When there is not sufficient air available to complete the combustion process, some of the fuel is left unburned, resulting in inefficiency and undesirable emissions. An examination of the CO2 and CO concentration in boiler and interpretation results help to improve indoor air quality. The paper presents characteristics of concentration CO2 and CO depend on used fuel in tested boiler rooms. The concentration curves show how each fuel combustion affect the amount of CO2 and CO that is produced.

Air quality and use of natural gas fuels: Assessment of improvement

International Nuclear Information System (INIS)

Riva, A.; Andreetto, B.

1992-01-01

This paper describes the application of the ARICOM code in the evaluation of air pollution and air quality in the Italian district of Verona. The study compared the environmental effects resulting from the use of natural gas, diesel fuels and fuel oils in a variety of real and simulated consumption schemes involving different mixes of fuels for space heating, automobile operation and industrial processes. The Verona district was divided into one square kilometer sections and the exhaust emission data were utilized in a dispersion model to calculate ground level pollution concentration levels. Real condition scenario pollution concentration levels calculated with this code were validated by actual measurements taken with an air quality monitoring network. The results evidenced the reduction in sulfur oxide pollution levels which can be obtained with the increased use of natural gas

Ambient air/near-field measurements of methane and Volatile Organic Compounds (VOCs) from a natural gas facility in Northern Europe

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Baudic, Alexia; Gros, Valérie; Bonsang, Bernard; Baisnee, Dominique; Vogel, Félix; Yver Kwok, Camille; Ars, Sébastien; Finlayson, Andrew; Innocenti, Fabrizio; Robinson, Rod

2015-04-01

Since the 1970's, the natural gas consumption saw a rapid growth in large urban centers, thus becoming an important energy resource to meet continuous needs of factories and inhabitants. Nevertheless, it can be a substantial source of methane (CH4) and pollutants in urban areas. For instance, we have determined that about 20% of Volatile Organic Compounds (VOCs) in downtown Paris are originating from this emission source (Baudic, Gros et al., in preparation). Within the framework of the "Fugitive Methane Emissions" (FuME) project (Climate-KIC, EIT); 2-weeks gas measurements were conducted at a gas compressor station in Northern Europe. Continuous ambient air measurements of methane and VOCs concentrations were performed using a cavity ring-down spectrometer (model G2201, Picarro Inc., Santa Clara, USA) and two portable GC-FID (Chromatotec, Saint-Antoine, France), respectively. On-site near-field samplings were also carried out at the source of two pipelines using stainless steel flasks (later analyzed with a laboratory GC-FID). The objective of this study aims to use VOCs as additional tracers in order to better characterize the fugitive methane emissions in a complex environment, which can be affected by several urban sources (road-traffic, others industries, etc.). Moreover, these measurements have allowed determining the chemical composition of this specific source. Our results revealed that the variability of methane and some VOCs was (rather) well correlated, especially for alkanes (ethane, propane, etc.). An analysis of selected events with strong concentrations enhancement was performed using ambient air measurements; thus allowing the preliminary identification of different emission sources. In addition, some flasks were also sampled in Paris to determine the local natural gas composition. A comparison between both was then performed. Preliminary results from these experiments will be presented here.

Progress of air-breathing cathode in microbial fuel cells

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Wang, Zejie; Mahadevan, Gurumurthy Dummi; Wu, Yicheng; Zhao, Feng

2017-07-01

Microbial fuel cell (MFC) is an emerging technology to produce green energy and vanquish the effects of environmental contaminants. Cathodic reactions are vital for high electrical power density generated from MFCs. Recently tremendous attentions were paid towards developing high performance air-breathing cathodes. A typical air-breathing cathode comprises of electrode substrate, catalyst layer, and air-diffusion layer. Prior researches demonstrated that each component influenced the performance of air-breathing cathode MFCs. This review summarized the progress in development of the individual component and elaborated main factors to the performance of air-breathing cathode.

Indoor air pollution from unprocessed solid fuels in developing countries.

Science.gov (United States)

Kaplan, Charlotte

2010-01-01

Approximately half of the world's population relies on biomass (primarily wood and agricultural residues) or coal fuels (collectively termed solid fuels) for heating, lighting, and cooking. The incomplete combustion of such materials releases byproducts with well-known adverse health effects, hence increasing the risk of many diseases and death. Among these conditions are acute respiratory infections, chronic obstructive pulmonary disease, heart disease, stroke, lung cancer, cataracts and blindness, tuberculosis, asthma, and adverse pregnancy outcomes. The International Agency for Research on Cancer has classified the indoor combustion of coal emissions as Group 1, a known carcinogen to humans. Indoor air pollution exposure is greatest in individuals who live in rural developing countries. Interventions have been limited and show only mixed results. To reduce the morbidity and mortality from indoor air pollution, countermeasures have to be developed that are practical, efficient, sustainable, and economical with involvement from the government, the commercial sector, and individuals. This review focuses on the contribution of solid fuels to indoor air pollution.

Lean manufacturing measurement: the relationship between lean activities and lean metrics

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Manotas Duque Diego Fernando

2007-10-01

Full Text Available Lean Manufacturing was developed by Toyota Motor company to address their specific needs in a restricted market in times of economic trouble. These concepts have been studied and proven to be transferrable and applicable to a wide variety of industries. This paper aims to integrate a set of metrics that have been proposed by different authors in such a way that they are consistent with the different stages and elements of Lean Manufacturing implementations. To achieve this, two frameworks for Lean implementations are presented and then the main factors for success are used as the basis to propose metrics that measure the advance in these factors. A tabular display of the impact of “Lean activities” on the metrics is presented, proposing that many a priori assumptions about the benefits on many different levels of improvement should be accurate. Finally, some ideas for future research and extension of the applications proposed on this paper are presented as closing points.

Hydrogen generation from biogenic and fossil fuels by autothermal reforming

Science.gov (United States)

Rampe, Thomas; Heinzel, Angelika; Vogel, Bernhard

Hydrogen generation for fuel cell systems by reforming technologies from various fuels is one of the main fields of investigation of the Fraunhofer ISE. Suitable fuels are, on the one hand, gaseous hydrocarbons like methane, propane but also, on the other hand, liquid hydrocarbons like gasoline and alcohols, e.g., ethanol as biogenic fuel. The goal is to develop compact systems for generation of hydrogen from fuel being suitable for small-scale membrane fuel cells. The most recent work is related to reforming according to the autothermal principle — fuel, air and steam is supplied to the reactor. Possible applications of such small-scale autothermal reformers are mobile systems and also miniature fuel cell as co-generation plant for decentralised electricity and heat generation. For small stand-alone systems without a connection to the natural gas grid liquid gas, a mixture of propane and butane is an appropriate fuel.

Turbulent burning rates of methane and methane-hydrogen mixtures