• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.878-883
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• 1998

The methane combustion reaction was conducted over Pb-ZSM-5 catalysts. ZSM-5 synthesized at low temperature and atomospheric pressure was used as a support. The change of methane conversion with $SiO_2/Al_2O_3$ molar ratio was tested. The methane conversions of the synthesized Pb-ZSM-5 catalyst was compared with those of a commercial Pd-ZSM-5(PQ Co.) and $PdO/{\gamma}-Al_2O_3$. The methane conversion increased with the decrease in $SiO_2/Al_2O_3$ molar ratio. The combustion rate of methane also increased with the decrease in $SiO_2/Al_2O_3$ molar ratio. The synthesized Pb-ZSM-5 showed better methane conversion than that of the commercial one. It is found that a crucial factor in methane combustion reaction is oxygen adsorption strength on the catalysts.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.3
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• pp.156-167
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• 1996

The present work is a continuation of our previous study to investigate the effects of parameters such as equivalence ratio, hydrogen supplement rate and initial pressure on combustion characteristics in a disk-shaped constant volume combustion chamber. The main results obtained from the study can be summarized as follows. The flames in near stoichiometric mixture of methane-air are propagated with a spherical shape, but in excess rich or lean mixtures are propagated with a elliptical shape. And, they are changed to an unstable elliptical shape flame with very regular cells by increasing the hydrogen supplement rate. Also, flame is sluggishly propagated at increased initial pressure in combustion chamber. Volume fraction of burned gas and flame radius as the combustion characteristics are increased by increasing the hydrogen supplement rate, especially at the combustion middle period, but then are slowly increased by increasing the initial pressure.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.2
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• pp.95-102
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• 2000

Methane combustion over perovskite-type oxides prepared using the malic acid method was investigated. To enhance the catalytic activity, the perovskite oxides were modified by the substitution of metal into their A or B site. In addition, the reaction conditions, such as the temperature, space velocity, and partial pressure of the methane were varied to understand their effect on the catalytic performance. With the LaCoO3-type catalyst, the partial substitution of Sr or Ba into site A enhanced the catalytic activity in the methane combustion. With the LaBO3(B=Co, Fe, Mn, Cu)-type catalyst, the catalytic activities were exhibited in the order of Co>Fe Mn>Cu. Futhermore, the partial substitution of Co into site B enhanced the catalytic activity, whereas an excess amount of Co decreased the activity. The surface area and catalytic activity of the perovskite catalysts prepared using the malic acid method showed higher values than those prepared using the solid reaction method. The catalytic activity was enhanced with decreased methane concentration and with a decrease in the space velocity.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.625-630
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• 2005

This study was focused on the catalytic activity for the combustion of low-concentration methane using various commerical catalysts (six transition metal catalysts in Russia and one rare earth metal (Honeycomb) catalyst in Korea). Catalytic activity was strongly influenced by the type and loading content of metal supported in catalyst. Catalytic performance showed the highest activity in Honeycomb catalyst including rare earth metal, which was the most expensive catalyst, while the next was the catalyst supported Cu with high content (AOK-78-52) and also that supported Cr and Co (AOK-78-56). However, both AOK-78-52 and AOK-78-56 catalysts that were very cheap had lower activation energy than Honeycomb catalyst. In the economical field, both AOK-78-52 and AOK-78-56 catalysts with transition metals showed a good alternative catalyst on the combustion of methane.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.29-31
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• 2012

The effects of combustion parameters on the characteristics of a steam-methane reformer. The reformer system was numerically simulated using a simplified two-dimensional axisymmetric model domain with an appropriate user-defined function. The fuel ratio, defined as the ratio of methane flow rate in the combustor to that in the reactor, was varied from 20 to 80%. The equivalence ratio was changed from 0.5 to 1.0. The results indicated that as the fuel ratio increased, the production rates of hydrogen and carbon monoxide increased, although their rates of increase diminished. In fact, at the highest heat supply rates, hydrogen production was actually slightly decreased. Simulations showed that equivalence ratio of 0.7 yielded the highest steam-methane mixture temperature despite a 43% higher air flow rate than the stoichiometric flow rate. This means that the production of hydrogen and carbon monoxide can be increased by adjusting the equivalence ratio, especially when the heat supply is insufficient.

• International Journal of Automotive Technology
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• v.5 no.3
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• pp.181-188
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• 2004

A cylindrical constant-volume combustion chamber was used to investigate the flow characteristics at the spark electrode gap and the combustion characteristics of an inhomogeneous charge methane-air mixture under several parameters such as stratified pattern, initial charge pressure, ignition time and the excess air ratio of the initial charge mixture. Flow characteristics including mean velocity and turbulence intensity were analyzed by a hot-wire anemometer. The combustion pressure development, measured by a piezo-electric pressure transducer, was used to investigate the effect of initial charge pressure, excess air ratio and ignition times on combustion pressure and combustion duration. It was found that the mean velocity and turbulence intensity had the maximum value around 200-300 ms and then decreased gradually to near-zero value at 3000 ms. For the stratified patterns, the combustion rate under the rich injection (RI) condition was the fastest. Under the initial charge conditions, the second mixture was accompanied by an increase in the combustion rate, and that the higher the mass which is added in the second stage injection, the faster the combustion rate.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.3
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• pp.89-100
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• 2021

This paper deals with the construction of a combustion test facility and preliminary tests for hot-firing tests of a methane engine. First, the combustion test facility for a 1 kN-class thrust chamber using liquid oxygen/gas methane as propellants was designed and built. Before hot-firing tests, the cold-flow tests of each propellant line and the ignition tests of torch igniter/afterburner were performed to verify propellant supply stability of the combustion test facility, operation of the control and measurement system, and successful ignition. Finally, a preliminary hot-firing test was conducted to measure the combustion efficiency, heat flux, and combustion stability of a thrust chamber prototype. The constructed combustion test facility will be helpfully used for basic research and development of methane engine thrust chambers.

• Advances in Energy Research
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• v.4 no.3
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• pp.213-221
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• 2016

The main purpose of this work is to test the validation of use of a four step reaction mechanism to simulate the laminar speed of hydrogen enriched methane flame. The laminar velocities of hydrogen-methane-air mixtures are very important in designing and predicting the progress of combustion and performance of combustion systems where hydrogen is used as fuel. In this work, laminar flame velocities of different composition of hydrogen-methane-air mixtures (from 0% to 40% hydrogen) have been calculated for variable equivalence ratios (from 0.5 to 1.5) using the flame propagation module (FSC) of the chemical kinetics software Chemkin 4.02. Our results were tested against an extended database of laminar flame speed measurements from the literature and good agreements were obtained especially for fuel lean and stoichiometric mixtures for the whole range of hydrogen blends. However, in the case of fuel rich mixtures, a slight overprediction (about 10%) is observed. Note that this overprediction decreases significantly with increasing hydrogen content. This research demonstrates that reduced chemical kinetics mechanisms can well reproduce the laminar burning velocity of methane-hydrogen-air mixtures at lean and stoichiometric mixture flame for hydrogen content in the fuel up to 40%. The use of such reduced mechanisms in complex combustion device can reduce the available computational resources and cost because the number of species is reduced.

• International Journal of Automotive Technology
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• v.2 no.3
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• pp.85-91
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• 2001

Characteristics of methane direct-injection spark-ignition stratified combustion in lean hydrogen mixture were analyzed both in a single cylinder engine and in a constant volume combustion chamber. Combustion pressure and Instantaneous combustion chamber wall temperature during the combustion process were measured with a thin-film thermocouple and used in analyses of combustion and cooling loss. Results in this research show that the premixed hydrogen increases cooling loss to combustion chamber wall while achieving combustion promotion, and the combustion system is effective especially in lean mixture conditions. Analysis of flame propagation was also done with Schlieren photography in the constant volume combustion chamber.

• Journal of the Korean Society of Combustion
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• v.11 no.2
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• pp.28-36
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• 2006

A constant volume combustion chamber was used to investigate the combustion characteristics. of homogeneous charge of methane-air mixture under various initial pressure, equivalence ratio and ignition times. The constant volume combustion chamber(CVCC) mostly has been studied by the experiments of visualization until now. So it is needed the numerical analysis of fluid and combustion characteristics in chamber by the more detail simulation. In this paper, the numerical analysis is tried to approach basically the homogeneous charge combustion phenomena under the various conditions, and the combustion phenomena in chamber is numerically analyzed by the commercial FIRE code. As a results, the combustion phenomena which were mean temperature, OH radical and reaction rate in chamber were investigated and it showed that the smallest flame growth occurs for the lean state and the increase of initial charged pressure condition due to the reduced OH radical.