• 한국분무공학회지
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• 제7권3호
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• pp.7-11
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• 2002

Comparison of the combustion characteristics of methane-air and gasoline-air mixtures has been conducted experimentally by a spherical bomb technique. The results indicate 1) the burning velocity of gasoline is slightly higher than that of methane, but their basic behavior of combustion characteristics, positive dependence on temperature and negative one on pressure, are the same, and 2) 20 vol.% addition of hydrogen to methane enhances the burning velocity by about 30%, but does not come to reverse the tendency of pressure dependence to that of pure hydrogen.

• 한국안전학회지
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• 제28권1호
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• pp.29-34
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• 2013

When flammable gases are mixed with air or oxygen in the explosion concentration range and are ignited by sufficiently large electrostatic discharge energy, they may explode causing severe disaster in workplace. The minimum ignition energy(MIE) of single gas-air mixtures has been already investigated by many research, but the MIE of mixtures of more than ternary gas mixture is not examined yet. The purpose of this study is to investigate the MIE of a ternary gas(methane, ethylene, hydrogen, propane) mixtures experimentally. The results of our experiment show that the ignition of a methane-ethylene-air, methane-hydrogen-air, methane-propane-air, ethylene-hydrogen-air, ethylene-propane-air and hydrogen-propane-air mixture due to electrostatic discharge energy primarily depends on that the mixture: the MIE decreases gradually with the increase of having the lower MIE than other mixture ratio in the normal atmospheric pressure.

• 한국토양비료학회지
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• 제28권3호
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• pp.266-269
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• 1995

볏짚을 사용한 구(볏짚 5톤+NPK:110-70-80kg/ha)와 볏짚을 사용하지 아니한 구(NPK : 110-70-80kg/ha)에서 벼의 출수기에 2시간 간격으로 메탄 배출량을 24시간 측정하고 지온(地溫)과 기온(氣溫)의 변화(變化)에 따른 상관관계(相關關係)를 고찰하였다. 1. 볏짚을 사용하지 아니한 삼요소구(三要素區)에서는 메탄배출은 지온(地溫)의 변화와 상응하게 변화하나 기온 상승이 급격한 오전 11시부터 오후 5시까지는 메탄배출량이 기온상승에 부응하는 증가경향을 보이지 않았다. 2. 볏짚을 시용한 삼요소구(三要素區)에서는 메탄 배출의 일 변화 양상이 지온의 변화와는 상관이 적고 기온이 상승하는 오전 11시~오후 5시에 매탄배출량이 급격히 증가하여 기온의 변화와 상관이 깊어 보였다. 3. 메탄 배출에는 지온(地溫) 외에도 기온(氣溫)과 메탄생성의 기질(基質)이 되는 유기물(有機物)의 존재(存在)가 중요함이 인정되었다.

• 한국자동차공학회논문집
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• 제17권5호
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• pp.46-52
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• 2009

In this study the predictions of NOx in methane-air lean premixed combustion in PSR were carried out with GRI 3.0 methane-air combustion mechanism and Zeldovich, nitrous oxide, prompt, and NNH NO formation mechanism by using CHEMKIN code. The results are compared to the JSR experimental data of Rutar for the validation of the model. This study concerns about the importance of the chemical pathways. The chemical pathway most likely to form the NO in methane-air lean-premixed combustion was investigated. The results obtained with the 4 different NO mechanisms for residence time(0.5-1.6ms) and pressure(3, 4.7, 6.5 atm) are compared and discussed.

• 한국자동차공학회논문집
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• 제3권3호
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• pp.129-139
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• 1995

This study investigates the combustion characteristics of methane-hydrogen-air premixture in a constant volume combustion chamber. Primary factors of the combustion characteristics of methane- hydrogen-air premixture are the equivalence ratio and hydrogen supplement rate. In the case of $\phi$= 1.1, maximum combustion pressure and heat release rate have peaks, and they increase as the initial pressure and hydrogen supplement rate increase. The total burning time is also the shortest at the $\phi$= 1.1, it shorten by lowering the initial pressure and by increasing the hydrogen supplement rate. The maximum flame temperature is shown at the $\phi$= 1.0, and increasing the initial pressure and hydrogen supplement rate, it increases. The concentration of NO reveals the highest value at the $\phi$= 0.9, and it increases by increasing the initial pressure and hydrogen supplement rate. It is also found that the limit of lean inflammability of methane-hydrogen-air premixture is greatly widened by increasing the hydrogen supplement rate.

• Advances in Energy Research
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• 제4권3호
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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.

• 한국수소및신에너지학회논문집
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• 제18권2호
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• pp.171-181
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• 2007

Blending effects of hydrogen and water vapor on flame structure and NOx emission behavior are numerically studied with detailed chemistry in methane-air counterflow diffusion flames. The composition of fuel is systematically changed from pure methane and pure hydrogen to the blending fuels of methane-hydrogen-water vapor through the molar addition of $H_2O$. Flame structure is changed considerably for hydrogen-blending methane flames and hydrogen-blending methane flames diluted with water vapor in comparison to pure methane flame. These complicated changes of flame structures also affect NOx emission behavior considerably. The changes of thermal NO and Fenimore NO are analyzed for various combinations of the fuel composition. Importantly contributing reaction steps to thermal NO and Fenimore NO are addressed in pure methane, hydrogen-blending methane flames, and hydrogen-blending methane flames diluted with water vapor.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.48-57
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• 2003

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at spark plug and the combustion characteristics of homogeneous charge methane-air mixture under various initial pressure, excess air ratio and ignition times in quiescent mixture. The flow characteristics such as mean velocity and turbulence intensity was analyzed by hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer and flame propagation acquired by ICCD camera were used to investigate the effect of initial pressure, excess air ratio and ignition times on pressure, combustion duration, flame speed and burning velocity. Mean velocity and turbulence intensity had the maximum value at 200 or 300ms and then decreased to near 0 value gradually after 3 seconds. Combustion duration, flame speed and burning velocity were observed to be promoted with excess air ratio of 1.1, lower initial pressure and ignition time of 300ms.

• 한국분무공학회지
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• 제2권4호
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• pp.7-14
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• 1997

Laser Raman scattering method has been applied to measure equivalence ratio of methane/air mixture in injected spray. We used high power KrF excimer laser$(\lambda=248nm)$ and a high gain ICCD camera to capture low intensity signal. Raman shifts and Raman scattering cross -sections of $H_2,\;O_2,\;N_2,\;CO_2,\;CH_4\;and\;C_3H_8$ are measured precisely. Our results show an excellent agreement with those of other groups. Mole fraction measurement of $O_2\;and\;N_2$ from air shows that $O_2:N_2=0.206:0.794$. We used gas injector which was operated at 1 bar. Methane is used as a fuel. Spray region is $10mm\times37mm$ and this region is divided into 80 points. In Raman signals are obtained and ensemble averaged for each point. 3-d and contour plot of distribution of equuivalence ratio is presented. Our measured results show that the equivalence ratio of methane/air mixture in methane-rich region is reasonable. However, more study is necessary for methane-lean region because background noise level is almost same as Raman intensity of methane.

• Journal of Advanced Marine Engineering and Technology
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• 제23권1호
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• pp.88-95
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• 1999

This study investigates the effects of different kind fuels on the flame structure by using the numerical simulation in triple flame made by a co-flowing fuels-air stream based on the elementary chemical reaction mechanism. Methane and Hydrogen were used as fuel for this study. In order to interpret the result of the study on numerical simulation Skeletal chemistry is employe as the elementary chemical reaction mechanism for methane Gutheil's as an offset ele-mentary chemical reaction mechanism for hydrogen. The result of this study is as follows. In com-parison between the apparent burning velocity change of triple flame and the one-dimensional pre-mixed flame hydrogen fuel flame is higher than methane fuel flame. The flame thrusts out for-ward in the down stream of the boundary between air-fuel mixture and air stream and a part of the flow is bent and forks out in this protruding flame so that a triple flame is originated.