• Title, Summary, Keyword: combustion heat

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Ignitability and Combustion Characteristics of Lean Mixture by Multi-Point Ignition (희박혼합기에 대한 다점점화의 점화능력 및 연소특성)

  • ;;;Lee, Sang Joon;Han, Sung Bin;Lee, Jong Tai
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.10
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    • pp.2607-2616
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    • 1995
  • The influences of number of spark plug on ignitability, combustion characteristics and combustion promotion effect were examined to establish the design conception of spark ignition system for lean burn. Ignitability was increased remarkably by increasing of number of spark plug at combustion wall. Combustion duration was shortened and maximum combustion pressure was increased in accordance with increasing of spark plug number. Rate of overall combustion promotion considered of combustion duration and combustion pressure was 28% in two point ignition and 40% in four point ignition. It was verified that heat release, heat loss and combustion duration were affected by flame area, heat transfer area and maximum flame travel distance respectively.

A Study of Heat Flux on the Height of an Instantaneous Temperature Probe in a Constant Volume Combustion Chamber (정적 연소기에서 순간온도 프로브의 돌출높이에 따른 열유속에 관한 연구)

  • Lee, C.W.
    • Journal of the Korean Society for Heat Treatment
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    • v.16 no.4
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    • pp.216-223
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    • 2003
  • In the production of internal combustion engines, there have been trends to develop the high performance engines with improved fuel efficiency, lighter weights and smaller sizes. This trends help to answer problems related to thermal load and abnormal combustion, etc. in these engines. In order to investigate these problems, a thin film-type probe and its manufacturing method for instantaneously measuring surface-temperatures have been proposed in this study, Instantaneous surface temperature of a constant volume combustion chamber was measured by this probe and heat flux was obtained by Fourier analysis. In order to thoroughly understand the characteristics of combustion, the authors measured the wall temperature of the combustion chamber and computed heat flux through a cylinder wall while varying the protrusion height of the probe have been measured. To achieve the above goals, a instantaneous temperature probe was developed, thereby making possible the analysis of the instantaneous temperature of wall surface and the detection of unsteady heat flux in the constant volume combustion chamber.

Evaluation of Heat Loss by Means of Plasma Jet Ignition during Combustion Duration in the Constant Volume Vessel (정적연소실내에서의 플라즈마 제트 점화에 대한 연소기간중의 열손실산정)

  • 김문헌;문경태;박정서;김홍성
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.2
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    • pp.96-103
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    • 2003
  • In this paper, the heat loss to the constant volume vessel wall was investigated using instantaneous heat flux sensor, schlieren visualization, pressure rise curve. And the heat loss characteristics of plasma jet ignition were compared with conventional spark ignition. In case of plasma jet ignition, the flame kernel moves toward the center of combustion vessel in the initial period of combustion, and the flame surface spread out to the vessel wall. However, in case of conventional spark ignition, the flame surface contact with combustion vessel wall in the initial period of combustion. As a result, heat loss in the combustion duration for conventional spark ignition increase faster than that of plasma jet ignition. And the combustion enhancement rate of plasma jet ignition is higher than that of conventional spark ignition, and it was found that the heat loss rate is inversely proportional to the combustion enhancement rate.

The combustion characteristics of catalytic combustor with preheating heat exchanger (예열용 열 교환식 촉매연소기의 연소특성에 관한 실험)

  • Yu, Sang-Phil;Seo, Yong-Suk;Song, Kwang-Sup;Ryu, In-Su
    • 한국연소학회:학술대회논문집
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    • pp.79-84
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    • 2002
  • The catalytic heat exchanger was designed which employs the regenerative preheating system of combustion air. The characteristics of the catalytic heat exchanger have been experimentally studied at the various operating parameters. The results showed that the mixture velocity did not affect significantly the performance of catalytic combustor whereas the preheating temperature of combustion air affected significantly the conversion rate. The complete conversion was achieved in the catalyzed honeycomb at a preheating temperature of $370-390^{\circ}C$, a mixture velocity of 0.53 $^{\sim}$ 0.75 m/s and an equivalence ratio of 0.19 $^{\sim}$ 0.27. The heat exchange efficiency of the catalytic heat exchanger appeared to be about 75 % when the air of room temperature was used as a working fluid. The results showed that both the heat balance of the system and the mixture conditions determine its stable catalytic combustion.

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Effect of heat ring in the water cooled kerosene engine (수냉식 등유기관에 있어서 가열링의 효과)

  • 이성열;김홍남
    • Journal of the korean Society of Automotive Engineers
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    • v.6 no.2
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    • pp.64-75
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    • 1984
  • In the engine design, it will be able to higher compression ratio and decreasing the cylinder size, if improve the vaporization of fuel and increasing the mass burned fraction in the kerosene engine. Therefore, concave, convex and straight types of hear ring set up neighborhood intake valve into the combustion chamber. The vaporization effect of fuel satisfied by heat transfer from the heat ring, but have need of selection of the location and surface area of the heat ring. Also, combustion duration of the combustion chamber with concave heat ring shorter than combustion chamber with other two types of heat ring, and about 30percent decreases in combustion duration as compared with combustion chamber without heat ring.

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Heat transfer characteristics around a circular combustion chamber of kerosene fan heater (석유 팬 히터의 연소실 주변 열전달 특성)

  • Kim, Jang-Gwon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.4
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    • pp.551-561
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    • 1998
  • This paper was studied to understand the characteristics of heat transfer coefficients and surface temperature distributions around a circular combustion chamber within the heat-intercept duct of kerosene fan heater. The experiment was carried out in the heat-intercept duct of kerosene fan heater attached to the blow-down-type subsonic wind tunnel with a test section of 240 mm * 240 mm * 1200 mm. The purpose of this paper was to obtain the basic data related with normal combustion for new design from conventional kerosene fan heater, and to investigate the effect of surface temperature, local and mean heat transfer coefficients versus flow-rate of convection axial fan according to the variations of heat release conditions from kerosene fan heater during normal combustion. Consequently it was found that (i) the revolution of convection axial fan during combustion had a smaller value than that of non-combustion because of the thermal resistance due to the high temperature in the heat-intercept duct, (ii) the pressure ratio P$_{2}$/P$_{1}$ had a comparatively constant value of 0.844 according to the revolution increase of turbo fan and the heating performance of kerosene fan heater had a range of 1,494 ~ 3,852 kcal/hr, (iii) the local heat transfer coefficient around a circular combustion chamber had a comparatively larger scale in the range of 315 deg. < .theta. < 45 deg. than that in the range of 90 deg. < .theta. < 270 deg. as a result of heat transfer difference between front and back of a circular combustion chamber, and (iv) the mean heat transfer coefficient around a circular combustion chamber increased linearly like a H$_{m}$=95.196Q+104.019 in condition of high heat release according to the increase of flow-rate of axial fan.n.

Characteristics of High-Frequency Combustion Instabilities Occurring in Combustion Devices (연소장치에서 발생하는 고주파 연소 불안정 특성)

  • Seo, Seong-Hyeon
    • Journal of the Korean Society of Combustion
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    • v.17 no.1
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    • pp.30-36
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    • 2012
  • Dynamic characteristics of combustion occurring in various combustion devices have been extensively studied since most of high-performance combustion devices are susceptible to hazardous, unstable combustion that deteriorates combustor's lifetime. One of the most severe unstable combustion phenomena is high-frequency combustion instability in which heat release fluctuations from combustion are coupled to resonant modes of the combustor. Here in this study, characteristics of high-frequency combustion instabilities observed in three different combustion devices have been presented. Lean-premixed combustion instability occurs mainly due to equivalence ratio fluctuations which induce large heat release oscillations at lean conditions. Liquid-fueled combustion also shows high-frequency instability from energy coupling between pressure and heat release oscillations.

RISK EVALUATION OF CARBON MONOXIDE IN COMPARTMENT FIRE

  • Kim, Kwang Il
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • pp.66-76
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    • 1997
  • In order to investigate the generation of carbon monoxide and heat loss of incomplete combustion in compartment fires, an experiment was conducted in a small scale compartment by using methanol as a fuel. The concentration of carbon monoxide and the toxicity parameter showed high values when the mass air - to - fuel stoichiometric ratio is under 1.0. The constitution of the combustion gas was showed to estimate it from the . The heat loss due to incompleteness of combustion is about one third of heat of combustion in case of under 1.0.

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Study on the Heat Flux Using Instantaneous Temperature as Height of Probe in the Combustion Chamber (연손실 순간온도 측저에 있어서 돌출높이에 따른 실험적 연구)

  • 이치우;김지훈;김시범
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.2
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    • pp.395-402
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    • 2001
  • The gasoline engine tends to high performance, fuel economy, small-sized. Therefore, it is necessary to solve the problems on thermal load, abnormal combustion, etc, in the engine, Thine film instantaneous temperature measurement probe was made. And the manufactural method of probe was established. The instantaneous surface temperatures in the constant volume combustion chamber were measured by this probe and the heat flux was obtained by Fourier analysis. The authors measured the wall temperature of combustion chamber and computed the heat flux through the cylinder wall in order to understand the combustion characteristics depending on height of probe. For achieving this goal, the thin film instantaneous temperature probe was developed for analyzing the instantaneous surface wall temperature and unsteady heat flux on the constant volume combustion chamber.

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The Characteristics of NOx Emission for Premixed Combustion and Flame Rapid Cooling of MFB (메탈파이버 버너의 예혼합 연소 및 화염급냉에 따른 NOx 배출 특성)

  • Kim, Hyouck-Ju;Park, Byung-Sik;Kim, Jong-Jin;Jeong, Hae-Seung
    • 한국연소학회:학술대회논문집
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    • pp.172-179
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    • 2001
  • Experimental studies have been carried out to find out the characteristics of the heat transfer, combustion emission and noise in the boilers without any extra firing zone for complete combustion of fuel. For the experiments a burner of premixed type and some heat exchangers were designed and manufactured. Also test facilities including a data acquisition system and various measuring devices were set up in order to measure automatically the various temperatures and flow rates of water and combustion gas. Various experiments were performed to find out the heat transfer characteristics as well as combustion emission and noise. In general, the burner which has uniform holes in the burner nozzle plate generates big combustion noise . whistling. The noise reduction method is discussed in this study. Many experimental data such as noise level, the amount of pollutant emission and heat transfer rate for different combination of heat exchangers are given as comparison bases for numerical studies.

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