• Title/Summary/Keyword: Additional Combustion

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4-stroke 디젤엔진의 성능예측에 관한 연구

  • 오태식;오세종;양재신
    • Journal of the korean Society of Automotive Engineers
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    • v.4 no.2
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    • pp.58-68
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    • 1982
  • It is well known to diesel engineers that the heat release pattern is one of the most important factors affecting engine performance. Thorough research in heat release pattern has materially helped the progress in high-speed diesel engine development . This paper is based on the research conducted at KAIST and Daewoo Heavy Industry last year. The purpose of this paper is to determine the heat release pattern in combustion chamber of MAN M type, the famous low-noise engine. Thermodynamic cycle simulation was performed using Whitehous-Way's heat release pattern with modified coefficients and Annand's heat transfer model. Instantaneous temperature and pressure of gas in cylinder could be determined by the numerical solution of simultaneous equation of mass conservation, equation of energy conservation, and state equation of ideal gas. Calculated results were compared with measured values in some details emphasizing upon the factors affecting rate of heat release. The agreement was fairly good and revealed why M type should have lower burning velocity at the early part of combustion in spite of high injection rate. Additional results by parametric studies were given in relation to fuel injection conditions for further application to engine development.

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A Study on Thermal Characteristics of Hybrid Solar Receiver for Dish Concentrating System (고온용 태양열 복합 흡수기의 열특성 분석 연구)

  • Kang, Myeong-Cheol;Kim, Jin-Soo;Kang, Yong-Heack;Kim, Nack-Joo;Yoo, Seong-Yeon
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.06a
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    • pp.571-575
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    • 2006
  • To improve economic of solar power generation, stirling engine is required continuous operation and the receiver has to be provided with an additional combustion system. The hybrid receiver with a specially adapted combustion system is possible to 24 hr/day operation by solar and gas-fired. The inner cavity and external wall serve as absorber surfaces using collected irradiation and heat transfer surfaces for the gas heat flow, respectively. The hybrid receiver was designed and fabricated for the dish/stirling system. The analytical method for pridicting natural convective heat loss from receiver is used. The Koenig and Marvin model is used to estimate convection heat loss and heat transfer coefficiency.

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Novel Ramjet Propulsion System using Liquid Bipropellant Rocket for Launch Stage

  • Park, Geun-Hong;Kwon, Se-Jin;Lim, Ha-Young
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.506-510
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    • 2008
  • Ramjets are capable of much higher specific impulse than liquid rocket engines for high speed flight in the atmosphere. Ramjets, however, cannot generate thrust at low flight speed. Therefore, an additional propulsion device to accelerate the ramjet vehicle to a supersonic speed is required. In this study, we propose a novel ramjet propulsion system with a $H_2O_2$/Kerosene rocket as the accelerator for initial stage. In order to test the feasibility of this concept, consecutive reactors was built; one for the decomposition of $H_2O_2$ and the other for kerosene combustion. Decomposed $H_2O_2$ jet was injected to combustor through converging nozzle from gas generator and over this hot oxygen jet, kerosene was injected by spay injector. Through the various test cases, hypergolic ignition test was carried out and steady combustion was achieved.

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A Study on Operational Concept of Solar Powered HALE UAV Using Directed-Energy (지향성 에너지를 이용한 고고도 장기체공 태양광 무인항공기 운용 개념 연구)

  • Ahn, Hyo-Jung
    • New & Renewable Energy
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    • v.7 no.3
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    • pp.59-66
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    • 2011
  • Recently, an UAV using green energy for propulsion has been developed due to exhaustion of fossil fuel. This aircraft runs on electric motors rather than internal combustion engines, with electricity coming from fuel cells, solar cells, ultracapacitors, and/or batteries. Especially solar cells are installed in HALE UAV and flight tests are performed in the stratosphere. Although the solar powered UAV has the advantage of zero emission, its energy conversion efficiency is low and operation time is limited. Therefore, the solar powered UAV has been designed to operate with the secondary battery obtaining flexibility of energy management. In this study, we suggest the new operational concept of the solar powered UAV using directed-energy rayed from the surface of earth to UAV. An UAV is able to secure additional power through attaching solar cell to the lower surface of elevator. As a result, the additional energy supplied by directed-energy can improve the energy management and operational flexibility of the solar powered UAV.

Torsional Vibration Stress Analysis for Shafting in Reciprocating Machine by Transfer Stiffness Coefficient Method (전달강성계수법에 의한 왕복 기계 축계의 비틀림진동 응력해석)

  • 최명수
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.8
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    • pp.749-756
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    • 2004
  • While designing shafting in reciprocating machines with internal combustion engines which derive generators, pumps, and vehicles, it is very important to calculate the additional stress of shafting by torsional vibration. In this paper, the transfer stiffness coefficient method which is based on the successive transfer of stiffness coefficient was applied to the calculation of the additional stress of shafting in reciprocating machine by torsional vibration. In order to confirm the effectiveness of the present method, a propulsion shafting with a diesel engine in a vessel was considered as the computational example of shafting in reciprocating machine. The results calculated by the present method were compared with those of the modal analysis method, the mechanical impedance method, and free vibration analysis.

Prediction of NOx Formation Characteristics in Turbulent Nonpremixed Hydrogen-Air Jet Flames (비예혼합 수소-공기 난류제트화염내의 NOx 생성특성 예측)

  • Kim, S.K.;Kim, Y.M.;Ahn, K.Y.;Oh, K.S.
    • 한국연소학회:학술대회논문집
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    • 1998.10a
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    • pp.165-170
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    • 1998
  • Turbulent nonpremixed $H_2$-air jet flames are numerically investigated using the joint PDF model. The reaction progress variable is derived by assuming the radicals 0, H, and OH to be in partial equilibrium and additional species $HO_2$ and $H_2O_2$ in steady state. The model is extended to npnadiabatic flame by introducing additional variable for the transport of enthalpy and radiative source term is calculated using a local, geometry independent model. In terms of flame structure and NO formation, the predicted results are favorably agreed with experimental data. The effects of nonequilibrium chemistry and radiative heat loss on the thermal NO formation are discussed in detail.

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Characterization of fine organic aerosols from biomass burning emissions using FTIR method (분광학적 방법을 이용한 바이오매스 연소 배출 유기 입자의 화학적 특성)

  • Son, Se-Chang;Park, Tae-Eon;Park, Seungshik
    • Particle and aerosol research
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    • v.17 no.4
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    • pp.125-132
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    • 2021
  • Fresh PM2.5 smokes emitted from combustion of four biomass materials (pellet, palm fruit fiber (PFF), PKS, and sawdust) in a laboratory-controlled environment were characterized using an attenuated total reflectance-fourier transform infrared (ATR-FTIR) technique. In smoke samples emitted from combustion of pellets, PFF and PKS, which is being used as boiler fuels for greenhouses in rural areas, the organic carbon/elemental carbon (OC/EC) ratios in PM2.5 were very high (14.0-35.5), whereas in sawdust smoke samples they were significantly low (<4.0) due to the combustion method close to flaming combustion. ATR-FTIR analysis showed that OH(3400-3250 cm-1), CH3(2958-2840 cm-1), CH2(2910 cm-1 and 2850 cm-1), ketone(1726-1697 cm-1), C=C(1607-1606 cm-1 and 1515-1514 cm-1), lignin (1463-1462 cm-1 and 1430-1428 cm-1) and -NO2(1360-1370 cm-1) peaks were identified in all biomass burning (BB) smoke samples. However, additional peaks appeared depending on the type of biomass. Among the four types of biomass materials, an additional peak of the methylene group CH3(2872-2870 cm-1) appeared only in PFF and PKS smoke samples, and a peak of C=O(1685 cm-1) was also confirmed. And in the case of PKS smoke samples, a peak of aromatic C=C(1593 cm-1 and 1476 cm-1) that did not appear in other BB samples was also observed. This indicates that the molecular structure of organic compounds emitted during BB differs depending on the type of biomass materials. The results of this study are expected to provide valuable information to more specifically reveal the effect of BB on PM2.5 collected in the atmospheric environment.

Simplified 1-Dimensional Model of Gas-Solid Reactor : Adapting to Coal Reduction Rotary Kiln (1차원 기체-고체 반응기 모델의 로터리킬른 환원로 적용)

  • Hahn, Taekjin;Choi, Sangmin
    • 한국연소학회:학술대회논문집
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    • 2012.11a
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    • pp.75-78
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    • 2012
  • Rotary kiln furnace is one of the most widely used reactors in industrial field. In this paper, 0-dimensional heat and mass balance for direct coal flame rotary kiln was performed preferentially, then a simplified 1-dimensional model was developed based on 0-dimensional analysis data to proceed additional thermal analysis. Compared the results with the currently operating rotary kiln data to validate 1-dimensional model. Through this procedure, it can help to derive fundamental idea for design and operation of rotary kiln.

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Effect of Additional Hydrogen Fuel on IDI Diesel Engines (수소첨가에 따른 직분식 디젤기관에서의 연소 및 스모크특성에 관한 연구)

  • Choi, Gyeung-Ho
    • Transactions of the Korean hydrogen and new energy society
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    • v.8 no.1
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    • pp.23-29
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    • 1997
  • The combustion and smoke emission of an indirect injection diesel engine Were investigated running the engine on Hydrogen/diesel fuels. Hydrogen fuel supplied to the intake pipe was varied 0 to 10 percent of DF2' s heating value. The most inportant finding was that the smoke emission is not decreased with increase of hydrogen fuel supplement. Also, the ignition delay is almost negligible over 10 percent hydrogen fuel mixture.

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Study on the performance improvement of a Main Oxidizer shut-off Valve (CC 산화제 개폐밸브 성능향상에 관한 연구)

  • Bae, Young-Woo;Kim, Do-Hyung;Hong, Moon-Geun;Lee, Soo-Yong;Jang, Ki-Won
    • Aerospace Engineering and Technology
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    • v.9 no.2
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    • pp.63-72
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    • 2010
  • MOV(Main Oxidizer shut-off Valves) control the combustion of launch vehicle systems by the supply and the isolation of liquid oxygen to a main combustion chamber in launch vehicle systems. Moreover, the MOV should secure a constant flow rate of liquid oxygen for combustion instability in the steady operational state. Although it has been showed that a EM(Engineering Model) with a high discharge coefficient value compared with the TM(Technology Model) fills the overall performance requirements, additional design modifications in some critical parts of the EM were conducted to improve the performance. The configurations of the pressure-control body, the middle flange, and the rips of the inlet body of the EM were modified and the performance tests have been performed with test models. Consequently, the intended improvements have been verified by the performance tests.