• Title/Summary/Keyword: Secondary injection system

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System Performance Variation for Relative Location of Pre-swirl Nozzles and Receiver Holes in Radial On-Board Injection Type Pre-swirl System (반경방향 분사방식 프리스월 시스템의 프리스월 노즐과 리시버 홀의 상대적 위치에 따른 시스템 성능변화)

  • Lee, Jonggeon;Lee, Hyungyu;Cho, Geonhwan;Cho, Jinsoo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.1
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    • pp.43-53
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    • 2020
  • The effect of the relative location between pre-swirl nozzle and receiver hole on the performance of radial on-board injection type pre-swirl system was analyzed. In this study, tendency of the change of discharge coefficient and temperature drop efficiency were analyzed for 20 design points through the combination of 5 pre-swirl nozzle location and 4 receiver hole location. Discharge coefficient of system tended to be similar to the pressure ratio of the pre-swirl nozzle. System performance variation occurred as the flow structure in the cavity was affected by the surface, and the influence of the stationary surface is greater than that of the rotating surface. Discharge coefficient of system changed -1.39% to 1.25% and temperature drop efficiency changed -5.41% to 2.94% refer to reference design point.

Experimental Study of Transition to Secondary Acoustic Instability at Downward-Propagating Premixed Flame in a Tube (튜브 내 하향 전파하는 예혼합 화염의 이차 열음향 불안정성 천이에 관한 실험적 연구)

  • Park, Juwon;Kim, Daehae;Park, Dae Geun;Yoon, Sung Hwan
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.26 no.7
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    • pp.915-921
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    • 2020
  • Thermoacoustic instability caused by air conditioning in a combustion chamber has emerged as a problem that must be solved to establish a stable combustion system. Thermoacoustic instability is largely divided into primary and secondary acoustic instability. In this study, an experimental study of the effects of heat losses was conducted to investigate the mechanism of secondary acoustic instability. To generate the secondary acoustic instability, a quarter-wavelength resonator with one open end and one closed end was used, and the inside of the resonator was filled with premixed gases. Subsequently, secondary acoustic instability with downward-propagating flames could be realized via thermal expansion on the burnt side. To control heat losses qualitatively, an additional co-axial tube was installed in the resonator with air or nitrogen supply. Therefore, additional diffusion flames can be formed at the top of the resonator depending on the injection of the oxidizer into the co-axial tube when rich premixed flames are used. Consequently, secondary acoustic instability could not be achieved by increasing heat losses to the ambient when the additional diffusion flame was not formed, and the opposite result was obtained with the additional diffusion flame.

Wall Impingement Phenomena of a Fuel Spray Injected by an EFI Injector (EFI 인젝터에 의한 연료분무의 벽면충돌 특성)

  • Kim, Y.I.;ARAI, M.
    • Journal of ILASS-Korea
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    • v.9 no.1
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    • pp.37-42
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    • 2004
  • In a port fuel injection system of engine, a large part of fuel injected into an intake port adheres on its wall and inlet valve. Consequently, the wall impinging spray interaction might occur the generation of several harmful phenomena. There are uncontrollable mixture formation, an accidental backfire and unburned hydrocarbons. Therefore, it is important to analyze the fuel behavior during the spray-wall interaction. In this study, splash characteristics of impingement and reflecting or scattering behavior of droplets of fuel injected from EFI nozzle were studied experimentally. A test fuel used is LAWS and its physical characteristics are similar to the conventional gasoline except for the ignition point. Since the liquid film formed immediately after impinging on an impingement plate is unstable, it is easy to cause secondary disintegration. In addition, when the intermittently impingement on the impingement plate with LAWS, the splash ratio is around 0.6. If an injection period becomes longer, liquid film will become thick and the splash ratio will fall bout 10 percent. On the other hand, when the injection period of an intermittent spray is long, the same time lapse as a continuous spray is shown.

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Development of an Ejector System for Operation of Chemical Lasers (II) - Optimal Design of the Second-Throat Type Annular Supersonic Ejector - (화학레이저 구동용 이젝터 시스템 개발 (II) - 이차목 형태의 환형 초음속 이젝터 최적 설계 -)

  • Kim Sehoon;Jin Jungkun;Kwon Sejin
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.10
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    • pp.1231-1237
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    • 2004
  • Determination of geometric design parameters of a second-throat type annual supersonic ejector is described. Tested geometric parameters were primary nozzle area ratio, cross-sectional area of second-throat, L/D ratio of second-throat and primary flow injection angle. Varying these four geometric parameters, we build a test matrix made of 81 test conditions, and experimental apparatus was fabricated to accommodate them. For each test condition, the stagnation pressure of primary flow and the static pressure of the secondary flow were measured simultaneously along with their transition to steady operation and finally to unstarting condition. Comparing the performance curve of every case focused on starting pressure, the unstarting pressure and the minimum secondary pressure, we could derive correlations that the parameters have on the performance of the ejector and presented the optimal design method of the ejector. Additional experiments were carried out to find effects of temperature and mass flow rate of the secondary flow.

Effect of Fuel Injection Timing on Nitrous Oxide Emission from Diesel Engine (디젤엔진에서 연료 분사시기가 아산화질소에 미치는 영향)

  • Yoo, Dong-Hoon
    • Journal of Power System Engineering
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    • v.18 no.6
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    • pp.106-112
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    • 2014
  • The diesel engine, which has high compression ratio than other heat engines, has been using as the main power source of marine transport. Especially, since marine diesel engines offer better specific fuel consumption (SFC), it is environment-friendly compared to those used in other industries. However, attentio should be focused on emissions such as nitrous oxide ($N_2O$) which is generated from combustion of low-grade fuels. Because $N_2O$ in the atmosphere is very stable, the global warming potential (GWP) of $N_2O$ is 310 times as large as that of $CO_2$, and it becomes a source of secondary contamination after photo-degradation in the stratosphere. It has been hitherto noted on the $N_2O$ exhaust characteristics from stationary power plants and land transportations, but reports on $N_2O$ emission from the marine diesel engine are very limited. In this experimental study, a author investigated $N_2O$ emission characteristics by using changed diesel fuel components of nitrogen and sulfur concentration, assessed on the factors which affect $N_2O$ generation in combustion. The experimental results showed that $N_2O$ emission exhibited increasement with increasing of sulfur concentration in fuel. However, all kinds of nitrogen component additives used in experiment could not change $N_2O$ emission.

Part-Load Performance Test of a Screw Chiller with Economizer using R22 and R407C (이코노마이저를 채용한 스크류 냉동기에서 R22와 R407C의 부분부하 성능실험)

  • 장영수;이용철;김영일
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.11
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    • pp.902-909
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    • 2003
  • Screw compressor type chillers are widely used in refrigeration for capacity over 30 RT. In general, chillers operate under part-load conditions. Therefore, information on characteristics at part-load is very important in view of chiller performance and energy economy. In this study, performance tests of part-load and economizer system using R22 and R407C have been performed for various secondary fluid temperatures. Adoption of an economizer system increased the cooling capacity and improved COP except for lower part-load condition when injection volume ratio is 1.01. For the same cooling capacity condition at part-load, COP of both non-economizer and economizer system showed similar values.

Numerical Study on the Injector Shape and Location of Urea-SCR System of Heavy-duty Diesel Engine for Preventing $NH_3$ Slip (대형 디젤엔진용 SCR 시스템의 암모니아 슬립 억제를 위한 인젝터의 형상 및 위치에 관한 수치적 연구)

  • Jeong Soo-Jin;Lee Sang Jin;Kim Woo-Seung;Lee Chun Beom
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.1
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    • pp.68-78
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    • 2006
  • In the past few years, considerable efforts have been directed towards the further development of Urea-SCR(selective catalytic reduction) technique for diesel-driven vehicle. Although urea possesses considerable advantages over Ammonia$(NH_3)$ in terms of toxicity and handling, its necessary decomposition into Ammonia and carbon dioxide complicates the DeNOx process. Moreover, a mobile SCR system has only a short distance between engine exhaust and the catalyst entrance. Hence, this leads to not enough residence times of urea, and therefore evaporation and thermolysis cannot be completed at the catalyst entrance. This may cause high secondary emissions of Ammonia and isocyanic acid from the reducing agent and also leads to the fact that a considerable section of the catalyst may be misused for the purely thermal steps of water evaporation and thermolysis of urea. Hence the key factor to implementation of SCR technology on automobile is fast thermolysis, good mixing of Ammonia and gas, and reducing Ammonia slip. In this context, this study performs three-dimensional numerical simulation of urea injection of heavy-duty diesel engine under various injection pressure, injector locations and number of injector hole. This study employs Eulerian-Lagrangian approach to consider break-up, evaporation and heat and mass-transfer between droplet and exhaust gas with considering thermolysis and the turbulence dispersion effect of droplet. The SCR-monolith brick has been treated as porous medium. The effect of location and number of hole of urea injector on the uniformity of Ammonia concentration distribution and the amount of water at the entrance of SCR-monolith has been examined in detail under various injection pressures. The present results show useful guidelines for the optimum design of urea injector for reducing Ammonia slip and improving DeNOx performance.

Preliminary Study on Alluvial Soil Characteristics for Clogging Possibility in Groundwater Artificial Recharge Area (인공함양 지역 클로깅 가능성 평가를 위한 충적층 토양 특성에 관한 예비 연구)

  • Hwang, Jeong;Choi, Myoung-Rak;Kim, Gyoo-Bum
    • Journal of the Korean Geotechnical Society
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    • v.40 no.1
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    • pp.39-46
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    • 2024
  • Artificial recharge systems have been employed to solve drought problems due to global climate change. Despite the increased usage, the applications of artificial recharge systems are limited by clogging problems, which reduce recharge rates. In this study, the soil texture and mineral characteristics of alluvial soil in a planned artificial recharge system area were investigated to evaluate the possibility of chemical clogging during the injection of stream water. The primary minerals contained in the clastic particles are quartz, K-feldspar, plagioclase, and biotite, and the secondary minerals filling the pore space are illite, kaolinite and Fe-oxide. The fact that carbonate and sulfate are observed as secondary minerals in the pore space suggests that chemical clogging has not occurred by the interaction between the groundwater and surface water in the study area. Thus, monitoring soil properties, e.g., the formation and growth of secondary minerals in the pore space, is required to investigate the possibility of chemical clogging in artificial recharge systems.

Flow Analysis of Building Pressurization System for Smoke Control (건물의 가압방연시스템 설계를 위한 유동해석에 관한 연구)

  • 김명배;한용식
    • Fire Science and Engineering
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    • v.14 no.2
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    • pp.14-20
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    • 2000
  • Many pressurization systems are designed and built with the goal of providing a smoke-free escape route in the event of a building fire. A secondary objective is to provide a smoke-free staging area for fire fighters. In the present study, a computer program is developed to calculate pressure loss and flow rate at several building elements such as a room, a ]tabby a staircase and an air supply shaft. By the program as the dosing tool for the pressurization system, the capacity of the injection fan is calculated, and the design method is proposed for the optimization of the fan capacity.

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A Study on the Mixture Formation in a Fuel Injection System (연료분사장치의 혼합기 형성에 관한 연구)

  • ;;;Lee, K. H.;Seo, Y. H.
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.10
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    • pp.2690-2698
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    • 1995
  • Fuel atomization and mixture formation in an gasoline engine has influence on the engine performance and pollutant emission. The throttle valve installed in an intake system plays a greater role in control of mixture quantity in accordance with engine drive condition. In this study, the characteristics of secondary atomization developed at the downstream of the valves were observed using an image processing method. Two major kinds of valves, solid and perforated ones, are chosen in order to compare the valve performance with the experimental parameters of air flow rate, valve opening angle, and valve shapes. For the perforated valve, we can obtain the relatively small sized droplets, and nearly uniformed and dense distributed sprays with low loss coefficient than for the solid valve.