• Title/Summary/Keyword: Cellular Convection

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A Study on the Hydraulic and Heat Transfer Characteristics for the Wire-woven Bulk Kagome(WBK) Composed of Aluminum Helix Wires (알루미늄 나선형 와이어로 직조된 다층 Kagome truss PCM의 유동 및 열전달 특성에 관한 연구)

  • Joo, Jai-Hwang;Kang, Bo-Seon;Kang, Ki-Ju
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2061-2066
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    • 2007
  • Recently, ultra-lightweight materials with open, periodic cell structures take much attention owing to its potential for multi-functionality such as load bearing, thermal dissipation, and actuation. This paper presents experimental results on the hydraulic and heat transfer characteristics for the Wire-woven Bulk Kagome(WBK) composed of aluminum 1100 wires. The overall pressure drop and heat transfer of the WBK specimen have been experimentally investigated under forced air convection condition. The pressure loss and heat transfer performance of the aluminum WBK are compared with other heat dissipation media. It was shown that heat transfer depended on relative density and surface area density. Comparison with metal foams and other heat dissipation media such as packed beds, lattice frame materials, louvered fins, and other materials suggests that the aluminum WBK competes favorably with the best available heat dissipation media in heat transfer performance.

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A Study on the Fluid Flow and Heat Transfer Characteristics for the Wire-woven Bulk Kagome(WBK) Composed of Aluminum Helix Wires (알루미늄 나선형 와이어로 직조된 다층 Kagome Truss PCM의 유동 및 열전달 특성에 관한 연구)

  • Joo, Jai-Hwang;Kang, Bo-Seon;Kang, Ki-Ju
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.1
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    • pp.15-22
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    • 2008
  • Recently, ultra-lightweight materials with open, periodic cell structures take much attention owing to its potential for multi-functionality such as load bearing, thermal dissipation, and actuation. This paper presents experimental results on the fluid flow and heat transfer characteristics for the Wire-woven Bulk Kagome (WBK) composed of aluminum 1100 wires. The overall pressure drop and heat transfer of the WBK specimen was experimentally investigated under forced air convection condition. The pressure loss and heat transfer performance of the aluminum WBK were compared with other heat dissipation media. It was shown that heat transfer characteristics depended on relative density and surface area density. Comparison with metal foams and other heat dissipation media such as packed beds, lattice frame materials, louvered fins, and others suggests that the aluminum WBK competes favorably with the best available heat dissipation media in heat transfer performance.

Thermal instability during the melting process in an isothermally heated horizontal cylinder (등온가열 수평원관내 융해과정동안의 열적 불안정성)

  • Jeong, Jae-Dong;Yu, Ho-Seon;Lee, Jun-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.6
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    • pp.2046-2056
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    • 1996
  • The constrained melting inside an isothermally heated horizontal cylinder has been repeatedly investigated in many studies only for the moderate Rayleigh numbers. This study extends the range of Rayleigh numbers to systematically investigate the transition during melting processes, especially focusing on the complex multi-cellular flow pattern and thermal instability. The enthalpy-porosity formulation, with appropriate source terms to account for the phase change, is employed. For low Rayleigh numbers, initially developed single-cell base flow keeps the flow stable. For moderate Rayleigh numbers, even small disturbances in balance between thermal buoyance force and viscous force result in branched flow structure. For high Rayleight numbers, Benard type convection is found to develop within a narrow gap between thee wall and the unmelted solid. The marginal Rayleigh number and the corresponding wave number are in excellent agreement with those from linear stability theory.