• Title/Summary/Keyword: Excess air flow

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The Effect of Feeding Characteristics on the Temperature Distribution of Rotary Kiln (로타리 킬른의 장입 특성이 온도분포에 미치는 영향)

  • Park, Jong-Seok;Chun, Chul-Kyun
    • Journal of the Korean Society of Combustion
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    • v.12 no.3
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    • pp.24-32
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    • 2007
  • A theoretical model was developed for rotary kiln and computational study was conducted to find the effect of feeding characteristics. One dimensional model with the variations of heating distribution, length of heating zone, excess air ratio and revolution was considered. The comparison of parallel-flow rotary kiln with that of counter-flow was conducted. For parallel-flow type, it is found that the variation of temperature of solid is not great for the zone that is following flame-heating zone. This zone is good to take the special treatment because thermal deviation is small and contacting time is enough for another treatment. Increase of excess air ratio have the effect of decreasing solid temperature. But this effect of decreasing solid temperature goes small for the great excess air ratio. The heating is efficient for the flame which has the maximum heating at the central region of the full length.

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A Study on The Flame Stability of Pellet Combustor Using Swirling Flow (선회유동을 이용한 펠릿연소기의 화염안정화 연구)

  • Lee, Do-Hyung;Yun, Bong-Seok;Wang, Zhen-Wei
    • Journal of Power System Engineering
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    • v.18 no.5
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    • pp.35-41
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    • 2014
  • The wood pellet, which is one of the woody biomass energy, has very high economic efficiency and combustion efficiency during their combustion. The existing pellet burner have many problems such as low combustion efficiency, flame stabilization, ash problem and ignition time etc. We developed cyclonic wood pellet burner aim to 20,000kcal/hr boiler and measured temperature profiles and exhaust gases in order to investigate the flame stability and optimum combustion condition at any air flow conditions. As results, we confirmed the reappearance and the isotropy of the experimental results in the burner. At the first air flow inlet condition of excess air ratio ${\alpha}=0.02$, second air flow $490{\ell}/min$ had the best combustion condition when pellet supplied 30g. This result means that we need much air supply only for the swirling of second air flow. So we tested various second air flux at first air excess air ratio ${\alpha}=0.7$ condition. At this condition, we could find out that we don't need much second air and total air flux compared to the former condition. We will continuously test this work of air flow distribution, and swirl effect of first air flow, and ash elimination.

Combustion Characteristics of Methane-Air Mixture in a Constant Volume Combustion Chamber(1): Homogeneous Charge (정적연소기에서의 메탄-공기 혼합기의 연소특성(1) : 균질급기)

  • 최승환;전충환;장연준
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.3
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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.

Study on the control of fuel-air ratio ofgas swirl burner (가스 스월버너의 공연비 제어에 관한 연구)

  • Kim, I.K.;Kim, Y.S.;Kim, Y.H.;Kim, K.S.;Kim, J.W.
    • 한국연소학회:학술대회논문집
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    • 1999.10a
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    • pp.129-138
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    • 1999
  • In this paper, our main issue is that establishing the control procedure of continuous gas flow rate according to combustion fan RPM. For this, first, we decide the optimum operating condition of gas swirl burner through analysis of combustion characteristics - thermal efficiency, combustion efficiency and exhaust gases such as CO, $CO_{2}$, $O_{2}$, $NO_{x}$ and THC. Second, fuel gas flow rate of gas valve is decided with considering excess air ratio and combustion fan RPM is decided by the target of combustion air flow rate. Finally, experimental operating equation is acquired by regression for gas valve and combustion fan. This equation is the control equation of continuous gas flow rate and always gas flow rate is decided by combustion fan operating RPM.

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Performance of Local Exhaust Ventilation Systems of Degreasing and Plating Workplaces (일부 탈지세척 및 도금공정 국소배기장치의 성능점검과 개선방안)

  • Han, Don-Hee
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.8 no.2
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    • pp.178-185
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    • 1998
  • In order to evaluate and improve the performance of local exhaust ventilation systems for two TCE degreasing (A, B) and two electroplating (C, E) and one acid dipping & plating (D) operations located in Kimhae, the performance test was conducted with trace gases and a thermal anemometer (Kanomax 24-6111, Japan). For the inadequately designed systems, the improvement and redesigns in compliance with recommendation by ACGIH was suggested. The results of performance test for each system are as follows; 1. System of Workplace A was generally well-designed. Actual exhaust air flow rate was in excess of 68% above the recommended standard exhaust air flow rate. 2. System of Workplace B was very well-designed and completely enclosed. 3. All systems of Workplace C including hoods were poorly-designed and actual exhaust air flow rates were insufficient for open tanks. All systems should be upgraded according to ACGIH recommendations. 4. Supply and exhaust air flow rate of push-pull exhaust systems in Workplace D should be greatly increased. The width of flange of dipping tank hood should be increased with the value suggested. 5. System of Workplace E was well-designed. Actual exhaust air flow rate was in excess of 54% above the required.

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A Study on the Combustion Flow Characteristic and NOx Reduction of the Exhaust Gas Recurculation Burner using Coanda Nozzles (코안다 노즐을 이용한 배기가스 재순환 버너의 연소 유동 특성 및 NOx 저감에 관한 연구)

  • Ha, Ji Soo
    • Journal of the Korean Institute of Gas
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    • v.21 no.3
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    • pp.53-60
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    • 2017
  • Various researches have been conducted for the reduction of NOx at the combustion furnace and exhaust gas recirculation method is commonly used technology for NOx reduction. The present research adopted coanda nozzles at the outside pipes of furnace to entrain the exhaust gas for the exhaust gas recirculation and the mixed gas was ejected to the tangential direction to cause the swirl flow in the furnace. The combustion flow characteristics in the exhaust gas recirculation burner with coanda nozzle has been elucidated by analyzing the swirl flow streamlines, temepraure and reaction rate distribution in the furnace. The exhaust gas entrained flow rate has been investigated by changing the excess air factor and coanda nozzle gap and the exhaust gas entrained flow rate increased with the increase of excess air factor and it decreased with the increase of coanda nozzle gap. The mean temperature at the exit plane of exhaust gas decreased with the excess air factor and it was little affected by the increase of coanda nozzle gap. The NOx mass fraction at the exhaust gas exit plane remarkably decreased with the excess air factor and it was also little affected by the increase of coanda nozzle gap.

COMBUSTION CHARACTERISTICS OF INHOMOGENEOUS METHANE-AIR MIXTURE IN A CONSTANT VOLUME COMBUSTION CHAMBER

  • Choi, S.H.;Jeon, C.H.;Chang, Y.J.
    • 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.

Combustion Characteristics Analysis of Methane-Air Homogeneous Mixture in a Constant Volume Combustion Chamber (정적연소기에서의 메탄-공기 균질혼합기의 연소특성 분석)

  • Lee, Suk-Young;Kim, Sang-Jin;Jeon, Chung-Hwan
    • Journal of the Korean Society of Combustion
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    • v.13 no.3
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    • pp.9-16
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    • 2008
  • In this study, a cylindrical constant volume combustion chamber is used to investigate the flow and combustion characteristics of methane-air homogeneous mixture under various initial charge pressure, excess air ratios and ignition times. The flame and burning speed, mean gas speed are calculated by numerical analysis to analyze the combustion characteristics. It is found that the mean gas velocity during combustion has the maximum value around 300 ms and then decreased gradually on the condition of 10000 ms, and that the combustion duration is shorten and flame speed and burning velocity have the highest value under the conditions of an excess air ratio 1.1, an initial charge pressure of 0.2 MPa and an ignition time of 300 ms in the present study. And, the initial pressure and burning speed are in inverse proportion, so that it is in agreement with Strehlow who presented that the initial pressure and burning speed are in inverse proportion when the burning speed is under 50cm/s.

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COMBUSTION CHARACTERISTICS OF HOMOGENEOUS CHARGED METHANE-AIR MIXTURE IN A CONSTANT VOLUME COMBUSTION CHAMBER

  • CHOI S. H.;CHO S. W.;JEONG D. S.;JEON C. H.;CHANG Y. J.
    • International Journal of Automotive Technology
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    • v.6 no.4
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    • pp.323-332
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    • 2005
  • A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at the spark electrode gap and the combustion characteristics of a homogeneous charged methane-air mixture under various overall charge pressures, excess air ratios and ignition times. The flow characteristics, including the mean velocity and turbulence intensity, were analyzed with a hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer, a flame propagation image acquired by ICCD camera and exhaust emissions measured by 2-valve gas chromatography were used to investigate effects of initial pressures, excess air ratios and ignition times on the combustion characteristics. It was found that the mean velocity and turbulence intensity had the maximum value around 200-300 ms and then decreased gradually to a near-zero value after 3000 ms and that the combustion duration was shorten and the flame speed and laminar burning velocity had the highest value under the condition of an excess air ratio of 1.1, an overall charge pressure of 0.15 MPa and an ignition time of 300 ms in the present study. The $CO_2$ concentration was proportional to the ignition time and overall charge pressure, the $CO_2$ concentration was proportional to the excess air ratio, and the UHC concentration was inversely proportional to the ignition time and overall charge pressure.

Combustion Characteristics Using a S.I. Optically Acessible Engine with SCV (SCV를 장착학 가솔린 가시화엔진에서의 연소특성)

  • 정구섭;김형준;전충환;장영준
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.1
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    • pp.115-123
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    • 2001
  • This study describes the combustion characteristics under various condition of air excess ratio and ignition timing in a 2-valve gasoline optically accessible engine with swirl control valve(SCV). It adapted three different types of SCA(open ration 72.5%, 78%, 89%) to strengthen a swirl flow. Pressure data were acquired using pressure sensor to investigate the effect of swirl flow on combustion, and from these pressure data, IMEP(indicated mean effective pressure) and MFB(mass fraction burnt)were calculated to explain burn rate and flame speed. From acquired flame images, inspected the flame propagation direction, flame area, and flame centroid, Flame propagation direction was shown different tendency between with/without SCV, and flame area with SCV was faster and larger than that of conventional engine. Finally, the representative flame image at each crank angle were acquired by PDF method to verify flame growth process. It is found that strengthened swirl flow is more beneficial for faster and stable combustion.

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