• Title/Summary/Keyword: Additional Combustion

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MODELING OF DIRECT INJECTION DIESEL ENGINE EMISSIONS FOR A QUASI-DIMENSIONAL MULTI-ZONE SPRAY MODEL

  • Jung, D.;Assanis, D.N.
    • International Journal of Automotive Technology
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    • v.5 no.3
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    • pp.165-172
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    • 2004
  • Phenomenological models for direct injection diesel engine emissions including NO, soot, and HC were implemented into a full engine cycle simulation and validated with experimental data obtained from representative heavy-duty DI diesel engines. The cycle simulation developed earlier by Jung and Assanis (2001) features a quasi-dimensional, multi-zone, spray combustion model to account for transient spray evolution, fuel-air mixing, ignition and combustion. In this study, additional models for HC emissions were newly implemented and the models for NO, soot, and HC emissions were validated against experimental data. It is shown that the models can predict the emissions with reasonable accuracy. However, additional effort may be required to enhance the fidelity of models across a wide range of operating conditions and engine types.

Introduction to Pressure Gain Combustors for the Game-Changing SFC Improvement in Propulsion Systems (추진기관 혁신적 연비향상을 위한 승압연소기 개요 및 연구동향)

  • Choi, Jeong-Yeol
    • 한국연소학회:학술대회논문집
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    • 2012.11a
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    • pp.301-302
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    • 2012
  • During a last decade, detonative combustion is promising combustion mechanism of high-speed propulsion systems, but is more rigorously considered in these days as a game-changer for the improvement of thermodynamic efficiency of propulsion and power generation systems. Regardless of the skepticism about the pressure loss associated with the strong shock waves, it is shown that the additional compression by the strong shock wave exhibits increased thermodynamics efficiency that is not achievable by conventional compression systems. Present talk will give an introduction to the concepts and the recent activities on the pressure gain combustors (PGC) researches based on detonation phenomena.

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Thermal Characteristics of Hybrid Solar Receiver using a Solar and Combustion heating (태양열과 가스 연소열을 적용한 복합 태양열 흡수기의 열특성 연구)

  • Kang, Myeong-Cheol;Kim, Jin-Soo;Kang, Yong-Heack;Yoon, Hwan-Ki;Yu, Chang-Kyun;Lee, Sang-Nam
    • New & Renewable Energy
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    • v.2 no.4 s.8
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    • pp.33-38
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    • 2006
  • The Dish/Stirling system with the Stirling engine is currently used to convert solar energy directly to electrical energy. Successful operation of dish/Stirling system is supported by hybrid system, which will allow continuous operation driven by solar and combustion heating. The hybrid Receiver has to be provided with an additional combustion system. The heat pipe receiver and conbustion system were manufactured and tested for thermal characteristics of receiver. Maximum temperature difference along the heat pipe surface is $200^{\circ}C$. Emission measurements showed low NOx values of 28 to 46 ppm and very high CO values of 18 to 201 ppm.

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Fuel Droplet Entrainment and Low Frequency Instability in Hybrid Rocket Combustion (하이브리드 로켓 연소에서 연료액적의 발생과 저주파수 연소불안정)

  • Kim, Jina;Lee, Changjin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.7
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    • pp.573-580
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    • 2021
  • Paraffin wax is attracting many attentions for promising solid fuel of hybrid rocket because of its higher regression than other fuels. However, even with paraffin fuel combustion, unsteady low-frequency oscillation of combustion pressure is still observed. And, this is related to the formation of liquid layer and the entrainment of fuel droplets entering the axial combustion gas flow. This study investigates the effect of additional combustion of fuel droplets on the occurrence of low-frequency combustion instability. On the other hand, the formation of fuel droplets depends on Weber Number (the ratio of the inertial force to the surface tension of the liquid) and Reynolds Number of the oxidizer flow. Therefore, a laboratory-scale hybrid rocket was used to monitor the occurrence of combustion instability while changing We number. A series of combustion tests were conducted to control We number by changing the oxidizer flow rate or adding LDPE (low density polyethylene) to base fuel. In the results, it was confirmed that there is a critical We number above which the low-frequency combustion instability occurs.

Experimental Investigation on Flame Structure and Emission Characteristics in a Lean Premixed Model Gas Turbine Combustor (희박 예혼합 모형 가스터빈 연소기의 화염구조와 배기특성에 관한 실험적 연구)

  • Lee, Jong-Ho;Kim, Dae-Hyun;Jeon, Hung-Hwan;Chang, Young-June
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.4
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    • pp.425-432
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    • 2004
  • The objective of this study is a qualitative comparison between line-integrated OH chemiluminescence(OH$\^$*/) image and its Abel inverted image to investigate the flame structure at different phase of the oscillating pressure field. PIV(Particle Image Velocimetry) measurements were conducted under non-reacting conditions to see the global flow structure and NOx emission was measured to investigate the effect of fuel-air premixing on combustion instability and emission characteristics. Experiments were carried out in an atmospheric pressure, laboratory-scale dump combustor operating on natural gas. Combustion instabilities in present study exhibited a longitudinal mode with a dominant frequency of ∼341.8㎐, which corresponded to a quarter wave mode of combustor. Heat release and pressure waves were in-phase when instability occurred. Results gave an insight about the location where the strong coherence of pressure and heat release existed. Also an additional information on active control to suppress the combustion instabilities was obtained. For lean premixed combustion, strong correlation between OH$\^$*/ and NOx emissions was expected largely due to the exponential dependence of thermal NOx mechanism on flame temperature.

A Study on Reductive Furnace for Copper Annealing Using Catalytic Combustion (촉매연소를 이용한 동 열처리용 환원로에 관한 연구)

  • Jeong, Nam-Jo;Kang, Sung-Kyu;Song, Kwang-Sup;Cho, Sung-June;Yu, Sang-Phil;Ryou, In-Su
    • 한국연소학회:학술대회논문집
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    • 2001.11a
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    • pp.83-89
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    • 2001
  • Most technologies of reduction process used in the heat treatment of existent metal products are related to metals applied to bolts and parts of automobiles, and nonmetal such as copper. Heating conditions and reduction gases produced in above processes depend on types of products to be treated thermally but heating systems employ electricity commonly and the reduction gases are separated into additional production equipment and a gas dryer and inefficiently provided into the system. Electrical heating system has the advantage of convenient temperature-control but is not economical because of disadvantages of high electricity-running cost and extra installation cost of a transformer. Accordingly, development of the system which has economical heating mode in which provision of reduction gas and heating conditions are unified is necessary for improvement of economy and efficiency in current reduction processes. This study aimed to develop a new advanced heat treatment furnace using catalytic combustion. thereby minimizing the cost during heating, supplying heat and reductive gas at the same time and controlling operating condition freely by changing electrical heating system to heating system by the gas combustion and regeneration of wasted heat.

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Experimental Investigation on Flame Structure and Emission Characteristics in a Lean Premixed Model Gas Turbine Combustor (희박 예혼합 모형 가스터빈 연소기의 화염구조와 배기특성에 관한 실험적 연구)

  • Moon, Gun-Feel;Lee, Jong-Ho;Jeon, Chung-Hwan;Chang, Young-June
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.356-361
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    • 2003
  • The objective of this study is a qualitative comparison between line-integrated OH chemiluminescence ($OH{\ast}$) image and its Abel inversion image at different phase of the oscillating pressure field. PIV(Particle Image Velocimetry) measurements were conducted under non-reacting conditions to see the global flow structure. Also NOx emission was measured to investigate the effect of fuel-air premixing on combustion instability and emission characteristics. Experiments were carried out in an atmospheric pressure, laboratory-scale dump combustor operating on natural gas. Combustion instabilities in present study exhibited a longitudinal mode with a dominant frequency of ${\sim}341.8$ Hz, which corresponded to a quarter wave mode of combustor. Heat release and pressure waves were in-phase when instability occurred. Results gave an insight about the location where the strong coherence of pressure and heat release existed. Also an additional information on active control to suppress the combustion instabilities was obtained. For lean premixed combustion, strong correlation between $OH{\ast}$ and NOx emissions was expected largely due to the exponential dependence of thermal NOx mechanism on flame temperature.

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Numerical Study of Regular Start and Unstart Process of Superdetonative Speed Ram Accelerator (초폭굉속도 램 가속기의 정상발진 및 불발과정의 수치적 연구)

  • Moon, G.W.;Jeung, I.S.;Choi, J.Y.
    • Journal of the Korean Society of Combustion
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    • v.5 no.1
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    • pp.31-41
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    • 2000
  • A numerical study was conducted to investigate the combustion phenomena of regular start and unstart processes based on ISL#s RAMAC 30 experiments with different diluent amounts in a ram accelerator. The initial projectile launching speed was 1800m/s which corresponded to the superdetonative speed of the stoichiometric $H_2/O_2$ mixture diluted with $5CO_2\;or\;4CO_2$. In this study, it was found that neither shock nor viscous heating was sufficient to ignite the mixture at a low speed of 1800m/s, as was found in the experiments using a steel-covered projectile. However, we could succeed in igniting the mixtures by imposing a minimal amount of additional heat to the combustor section and simulate the regular start and unstart processes found in the experiments with an aluminum-covered projectile. The numerical results matched almost exactly to the experimental results. As a result, it was found that the regular start and unstart processes depended on the strength of gas mixture, development of shock-induced combustion wave stabilized by the first separation bubble, and its size and location.

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A Discussion on the Radiation Efficiency Measurement of Porous Surface Flames (다공성 표면 화염의 복사열효율측정에 관한 논의)

  • Jeong, Hwanghui;Sim, Keunseon;Lee, Keeman
    • 한국연소학회:학술대회논문집
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    • 2014.11a
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    • pp.157-159
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    • 2014
  • This article describes an investigation of basic combustion characteristics of radiant burner with various firing rate and equivalence ratios in porous metal. As a main experimental condition, firing rates and equivalence ratios each were adjusted from 204 to $408kW/m^2$ and 0.6 to 1.3. The purpose of this study is to investigate radiation efficiency using two experiment methods. The first way is to calculate the radiation efficiency by measuring the temperature of the burner surface, and the second is to compute the radiation efficiency by measuring the radiation intensity of the burner surface with a radio meter. The value of the radiation efficiency did not exactly match in the two cases. But we figured out that in accordance with increasing heat power, radiation efficiency was decreased. And additional complementary experiment on the relationship between these values is needed.

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Thermal Characteristics of a Solar and Gas-fired Receiver (태양열과 가스 연소열을 복합 적용한 흡수기의 열특성 연구)

  • Kang, Myeong-Cheol;Kim, Jin-Soo;Kang, Yong-Heack;Yoon, Hwan-Ki;Yu, Chang-Kyun;Lee, Sang-Nam
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.11a
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    • pp.157-160
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    • 2006
  • The Dish/Stirling system with the Stirling engine is currently used to convert solar energy directly to electrical energy successful operation of dish/Stirling system is supported by hybrid system, which will allow continuous operation driven by solar and combustion heat ins. The hybrid Receiver has to be provided with an additional combustion system. The heat pipe receiver and conbustion system were manufactured and tested for thermal characteristics of receiver. Maximum temperature difference along the heat pipe surface is $200^{\circ}C$. Emission measurements showed low NOx values of 28 to 46 ppm and very high CO values of 18 to 201 ppm.

  • PDF