• Title/Summary/Keyword: Horizontal Particle Spacing

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Combustion Characteristics of Coal Particle Array (미분탄 입자들의 배열에 따른 연소특성)

  • Cho, Chong-Pyo;Kim, Ho-Young;Chung, Jin-Taek
    • 한국연소학회:학술대회논문집
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    • 2004.11a
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    • pp.117-123
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    • 2004
  • The burning characteristics of interacting coal particles in a convective flow are numerically investigated at various Reynolds numbers. The transient combustion of 2-dimensionally arranged particles, both the fixed particle distances of 5 radii to 20 radii horizontally and 3 radii to 24 radii vertically, is studied. The results obtained from the present numerical analysis reveal that the transient flame configuration and retardation of particle temperature augmentation with the horizontal or vertical particle spacing substantially influence devolatilization process and carbon conversion ratio of interacting particles. Volatile release and carbon conversion ratio of the second particle with decreasing horizontal and vertical particle spacing decrease gradually, whereas those of the first particle with decreasing vertical particle spacing increases due to flow acceleration. When the vertical particle spacing is smaller than $6R_{o}$, volatile release and carbon conversion ratio of the second particle decrease greatly due to reduction of flame penetration depth.

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Effects of Coal Particle Array on Coal Combustion (미분탄 입자들의 배열이 미분탄 연소에 미치는 영향)

  • Cho, Chong-Pyo;Kim, Ho-Young;Chung, Jin-Taek
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.12 s.243
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    • pp.1321-1328
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    • 2005
  • The burning characteristics of interacting coal particles in a convective flow are numerically investigated at various Reynolds numbers. The transient combustion of 2-dimensionally arranged particles, both the fixed particle distances of 5 radii to 20 radii horizontally and 4 radii to 24 radii vertically, is studied. The results obtained from the present numerical analysis indicate that the transient flame configuration and retardation of particle temperature augmentation with the horizontal or vertical particle spacing substantially influence devolatilization process and carbon conversion ratio of interacting particles. Volatile release and carbon conversion ratio of the second particle with decreasing horizontal and vertical particle spacing decrease gradually, whereas those of the first particle with decreasing vertical particle spacing increase due to flow acceleration. When the vertical particle spacing is smaller than $6R_0$, volatile release and carbon conversion ratio of the second particle decrease due to reduction of flame penetration depth and interference of oxygen diffusion by the first particle.

The Effects of Droplets Arrangement and Size Difference on the Vaporization and Combustion Characteristics of Liquid Fuel Droplets (액체 연료 액적들의 배열 및 크기차이가 증발 및 연소특성에 미치는 영향)

  • Lee, Dong-Jo;Kim, Ho-Young;Cho, Chong-Pyo;Yoon, Suk-Goo
    • 한국연소학회:학술대회논문집
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    • 2007.05a
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    • pp.107-113
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    • 2007
  • The burning characteristics of interacting droplets with internal circulation in a convective flow are numerically investigated at various particle arrangement and size difference. In this simulation some conditions are fixed, surround gas temperature is 1250K, pressure is 10 atm and drolet's initial temperature is 300K. The transient combustion of arranged droplets, the fixed droplet distances of 4 radii to 20 radii horizontally, is studied. And the range of size of droplet is 75${\mu}m$ to 100${\mu}m$. The results obtained from the present numerical analysis reveal that the transient flame configuration and retardation of droplet internal motion with the horizontal spacing substantially influence lifetime of interacting droplets. At a Reynolds number 10, lifetime of the three droplets with decreasing horizontal droplet spacing increases monotonically. But when droplet spacing decreases further to 4radii, Lifetime of interacting droplets are increase. So Lifetime of interacting droplets exhibits a strong dependence on the horizontal droplet spacing and size difference. It can be investigated well with these conditions to that of single burning droplet.

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The Effect of Coal Particle Arrangement and Size Difference on Combustion Characteristics (미분탄 입자의 크기 차이와 배열이 연소특성에 미치는 영향)

  • Kim, Ki-Duck;Kim, Ho-Young;Cho, Chong-Pyo;Yoon, Suk-Goo
    • 한국연소학회:학술대회논문집
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    • 2007.05a
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    • pp.47-53
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    • 2007
  • The laminar combustion characteristics of interacting coal particles in a convective flow are numerically investigated at particle arrangement and size difference. The numerical simulations, which use the two-step global reaction model to account for the surrounding gas effect, show the detailed interaction among the inter-space particles, undergoing devolatilization and subsequent char burning. Several parametric studies, which include the effect of the gas temperature (1700 K), high pressure(10 atm) and variation in geometrical arrangement of the particle diameter on the volatile release rate and the char combustion rate, have been carried out. The comparison indicates that the shift to the multiple particle arrangement resulted in the substantial change of the combustion characteristics and that the volatile release rate of the interacting coal particles exhibits a strong dependency on the particle spacing and size difference.

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Pullout Behavior of Mechanically Stabilized Earth Wall Abutment by Steel Reinforcement and Backfill Properties (금속 보강재와 채움재 특성에 따른 보강토교대의 인발거동 분석 연구)

  • Kim, Taesu;Lee, Soo-Yang;Nam, Moon S.;Han, Heuisoo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.11
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    • pp.750-757
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    • 2018
  • The mechanically stabilized earth wall abutment is an earth structure using a mechanically stabilized earth wall and it uses in-extensional steel reinforcements having excellent friction performance. In order to analyze the pullout behavior of in-extensional steel reinforcements usually applied on the mechanically stabilized earth wall abutment, effects of stiffness and particle-size distributions of backfills and also horizontal spacings were considered in this study. As a result of parametric analyses, the highest pulling force acted on the uppermost reinforcement, and the stiffness and the particle-size distributions of the backfill significantly affected the pulling resistance of the reinforced soils. The internal friction angle of backfills should be at least 25 degrees, the coefficient uniformity factor should be at least 4, and the horizontal spacing of the uppermost steel reinforcement should be less than 25cm. Therefore, in order to secure the pullout resistance of the reinforced soil, it is necessary a properly spacing of reinforcement and more strict quality control for the backfill.