• Title/Summary/Keyword: inlet profiles

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Modeling for a Coke Dry Quenching Process Using a Theory of a Porous Material (다공질 물질의 냉각현상 연구를 통한 코크스냉각공정의 모델링)

  • Kim, Joo-Han;Lee, Yong-Ju;Kim, Ki-Seok
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.21 no.5
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    • pp.697-701
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    • 2012
  • Numerical modeling for a coke dry quenching process was developed and evaluated. The cokes had similar characteristics to a porous material, therefore, its quenching analysis was simplified as a cooling process of porous blocks. A uniform inlet temperature and constant properties of materials in the oven were also assumed. With given operating conditions, temperature profiles in the cokes were calculated and compared to the actual values. The calculated temperature gradient was high at the upper part of the coke flow and the cooling rate decreased as cokes came down to the exit port. The exit port temperature of cokes was similar to the measured value, however, temperature-dependent material properties and operating conditions must be considered to predict the temperature precisely. The calculated results could be applied to design a coke oven to produce high quality cokes.

Three-Dimensional Numerical Simulation within a Circular-to-Rectangular Transition Duct (Circular-to-Rectangular Transition Duct 내부의 3차원 유동장에 관한 연구)

  • Jo, Su-Yong;Jeong, Hui-Taek;Son, Ho-Jae
    • Journal of computational fluids engineering
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    • v.3 no.2
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    • pp.9-16
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    • 1998
  • Predictive behaviors by the extended k-${\varepsilon}$ turbulence model and the standard k-${\varepsilon}$ turbulence model are compared. Grid dependency is tested with the H-type grid as well as the O-type grid. Computations have been performed on a circular-to-rectangular transition duct. The Reynolds number is 390,000 based on the bulk velocity at the inlet. The computed axial velocity contours, transverse velocity profiles, static pressure contours, peripheral skin friction coefficient, peripheral wall static pressure distributions and turbulence kinetic energy have been compared with experimental results. The computed results than those obtained with the standard k-${\varepsilon}$ turbulence model. Comparing to the computed results obtained with the H-type grid and O-type grid, those with H-type grid seem to agree well with experimental results.

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Assessment of RNG Turbulence Model and the Effect of Inlet Pressure on Scavenging Flow (유니프로우 소기식 두상밸브형엔진에서 RNG 난류모델의 평가와 과급압력변화가 소기유동에 미치는 영향)

  • 조상무;허선철;박권하
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2000.11a
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    • pp.68-81
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    • 2000
  • Many studies for improving a scavenging efficiency have been executed by using simulative manner. This paper addresses to a scavenging process in a uniflow two stroke cycle engine. The Processes are simulated for scavenging pressure variation, after the assessment of turbulent models. The results have shown that employing RNG k-$\varepsilon$ model gave more accurate velocity profiles near the cylinder wall compared with the standard k-$\varepsilon$ model and the charged fresh air has increased with the scavenging pressure increase.

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Numerical Study on Simultaneous Heat and Mass Transfer in a Falling Film of Water-Cooled Vertical Plate Absorber (수냉식 수직평판 흡수기의 액막 열 및 물질전달에 관한 수치적 연구)

  • Thanh-Tong Phan
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.4
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    • pp.593-602
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    • 2004
  • This paper is a study on the model of simultaneous heat and mass transfer process in the absorption of refrigerant vapor into a lithium bromide solution of water-cooled vertical plate absorber. The model can predict temperature and concentration profiles as well as the effect of Reynolds number on them. Also. the variations of the absorption heat and mass fluxes. and the heat and mass transfer coefficients have been investigated. The numerical result shows that the interface temperature and concentration decrease as film Reynolds number does. The absorption heat and mass fluxes, and the heat and mass transfer coefficients get their maximum values adjacent to the inlet solution. Analyses on a constant wall temperature condition have been also carried out to exam the reliability of the present numerical method by comparing to previous investigations.

The Numerical Simulation of Ultrafine $SiO_2$ Particle Fabrication and Deposition by Using the Tube Furnace Reactor (튜브형 가열로 반응기를 이용한 초미립 $SiO_2$ 입자의 제조 및 증착에 대한 수치모사)

  • 김교선;현봉수
    • Journal of the Korean Ceramic Society
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    • v.32 no.11
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    • pp.1246-1254
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    • 1995
  • A numerical model for fabrication and deposition of ultrafine SiO2 particles were proposed in the simplified horizontal MCVD apparatus using tube furnace reactor. The model equations such as energy and mass balance equations and the 0th, 1st and 2nd moment balance equations of aerosols were considered in the reactor. The phenomena of SiCl4 chemical reaction, SiO2 particle formation and coagulation, diffusion and thermophoresis of SiO2 particles were included in the aerosol dynamic equation. The profiles of gas temperature, SiCl4 concentration and SiO2 particle volume were calculated for standard conditions. The concentrations, sizes and deposition efficiencies of SiO2 particles were calculated, changing the process conditions such as tube furnace setting temperature, total gas flow rate and inlet SiCl4 concentration.

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A Numerical Study on In-cylinder Flow Fields of an Axisymmetric Engine (축대칭 엔진 실린더내의 유동장에 관한 수치적 연구)

  • 최재성
    • Journal of Advanced Marine Engineering and Technology
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    • v.23 no.5
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    • pp.662-670
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    • 1999
  • A numerical prediction was performed to clarify the air motion in the cylinder of an axisymmet-ric four-stroke reciprocating engine at its intake and compression stage. A scheme of finite volume method is used for the calculation. Modified $k-{\varepsilon}$ turbulence model is adopted and wall function is applied to the grids near the wall. The predicted mean velocity and rms velocity profiles showed a reasonable agreement with an available experimental data at its intake and compression stage. The predicted in-cylinder flow fields show that a strong turbulent twin vortex structure is pro-duced during induction but it commences to decay rapidly around inlet valve closure. The mean velocity continues to fall to a low level during compression but the turbulence intensity attains an approximate constant level.

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Effect of Incidence Angle on the Turbulence Structure in the Wake of a Turbine Rotor Blade (입사각이 터빈 동익 후류의 난류구조에 미치는 영향)

  • Chang, Sung-Il;Lee, Sang-Woo
    • 유체기계공업학회:학술대회논문집
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    • 2003.12a
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    • pp.55-62
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    • 2003
  • This paper describes the effect of the incidence angle on the turbulence structure in the wake of a turbine rotor blade at the low inlet free-stream turbulence level. For three incidence angles of -5, 0 and 5 degrees, mid-span energy spectrum as well as mid-span profiles of mean velocity magnitude and turbulence intensity are reported at three downstream locations in the wake. Vortex shedding frequencies are obtained from the energy spectrum. The result shows that as the incidence angle changes from-5 to 5 degrees, the boundary layer on the suction surface tends to be thickened, which results in widening of the wake. Strouhal numbers based on the shedding frequencies have a nearly constant value of 0.3, independent of tested incidence angles.

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Flow Analysis Of Cardio Vascular Assist By Laser Doppler Velocimeter Measure munt (L.D.V 계측에 의한 보조장기의 유동해석)

  • Park, G.M.;Park, S.B.;Kamm, R.D.
    • Proceedings of the KOSOMBE Conference
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    • v.1996 no.05
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    • pp.195-198
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    • 1996
  • This paper is studid the flow analysis of cardio vascular assist device. The experimental study is carried out to measure velocity profiles, Shear stress distributions and Velocity Vector for the flowrare of 4l/min, the frequency of 0.5Hz, the stroke volume of 60ml, the inlet and outlet pressure of 100mmHg by the L.D.V and P.I.V system. These results are agreed with the numerical simulations.

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Surface Texturing in Hydraulic Machine Components for Friction Reduction (Surface Texturing에 의한 유압부품의 마찰저감)

  • Park, Tae Jo;Kim, Min Gyu
    • Journal of Drive and Control
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    • v.13 no.1
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    • pp.27-33
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    • 2016
  • In hydraulic machinery, the hydraulic fluid acts primarily as working fluid and secondarily as a lubricant. Hence, the viscous friction force acting on the sliding components should be reduced to improve the mechanical efficiency. It is now well known that the surface texturing is a useful method for friction reduction. In this study, using a commercial computational fluid dynamics (CFD) code, FLUENT, the lubrication characteristics of a surface textured slider bearing under high boundary pressure difference is studied. The streamlines, velocity profiles, pressure distributions, load capacity, friction force and leakage flowrate are highly affected by the film thickness ratio and the textured region. Partial texturing at the inlet region of the inclined slider bearing can reduce both friction force and leakage flowrate than in the untextured case. The present results can be used to improve the lubrication characteristics of hydraulic machinery.

EFFECT OF INLET LOADING RATE ON THE ELIMINATION OF HYDROGEN SULFIDE AND AMMONIA IN IMMOBILIZED CELL BIOFILTERS

  • Kim, Jung-Hoon;Rene, Eldon R.;Park, Seung-Han;Park, Hung-Suck
    • Environmental Engineering Research
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    • v.11 no.5
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    • pp.285-291
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    • 2006
  • Biofiltration is a simple, effective, economically viable and the most widely used gas treatment technique for treating malodors at low concentrations and high flow rates. This paper reports the performance of two lab scale immobilized cell biofilters operated in continuous mode for hydrogen sulfide ($H_2S$) and ammonia ($NH_3$) removal. The removal efficiency (RE, %) and the elimination capacity (EC, $g/m^3{\cdot}hr$) profiles were monitored by subjecting the biofilters to different loading rates of $H_2S$ (0.3 to $8\;g/m^3{\cdot}hr$) and $NH_3$ (0.3 to $4.5\;g/m^3{\cdot}hr$). The removal efficiencies were greater than 99% when inlet loading rate to the biofilters were upto $6\;gH_2S/m^3{\cdot}hr$ and $4\;gNH_3/m^3{\cdot}hr$ respectively. The performance of the biofilters were also ascertained by conducting shock loading studies at a loading rate of $10\;gH_2S/m^3{\cdot}hr$ and $6\;gNH_3/m^3{\cdot}hr$. The results from this study show high removal efficiency, good recuperating potential and stability of the immobilized microbial consortia to transient shock loads.