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다공성 매질과 비투과성 벽면 사이의 경계면에 대한 열적 경계 조건
김덕종,김성진,Kim, Deok-Jong,Kim, Seong-Jin 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.12
The present work investigates a heat transfer phenomenon at the interface between a porous medium and an impermeable wall. In an effort to appropriately describe the heat transfer phenomenon at the interface, the heat transfer at the interface between the microchannel heat sink, which is an ideally organized porous medium, and the finite-thickness substrate is examined. From the examination, it is clarified that the he heat flux distribution at the interface is not uniform for the impermeable wall with finite thickness. On the other hand, the first approach, based on the energy balance for the representative elementary volume in the porous medium, is physically reason able. When the first approach is applied to the thermal boundary condition, and additional boundary condition based on the local thermal equilibrium assumption at the interface is used. This additional boundary condition is applicable except for the very th in impermeable wall. Hence, for practical situations, the first approach in combination with the local thermal equilibrium assumption at the interface is suggested as an appropriate thermal boundary condition. In order to confirm our suggestion, convective flows both in a microchannel heat sink and in a sintered porous channel subject to a constant heat flux condition are analyzed. The analytically obtained thermal resistance of the microchannel heat sink and the numerically obtained overall Nusselt number for the sintered porous channel are shown to be in close agreement with available experimental results when our suggestion for the thermal boundary conditions is applied.
김덕종,김재윤,박상진,허필우,윤의수,Kim, Deok-Jong,Kim, Jae-Yun,Park, Sang-Jin,Heo, Pil-U,Yun, Ui-Su 한국기계연구원 2003 硏究論文集 Vol.33 No.-
In this work, thermal design of a PCR chip for LOC is systematically conducted. From the numerical simulation of a PCR chip based on the finite volume method, how to control the average temperature of a PCR chip and the temperature difference between the denaturation zone and the annealing zone is presented. The average temperature is shown to be controlled by adjusting heat input and a cooler as well as a heater is shown to be necessary to obtain three individual temperature zones for polymerase chain reaction. To reduce the time required, a heat sink for the cooler is not included in the calculation domain for the PCR chip and heat sink design is conducted separately by using a compact modeling method, the porous medium approach.
김영(Young Kim),윤석호(Seok Ho Yoon),최준석(Jun Seok Choi),김덕종(Deok Jong Kim) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
The systematic operation and design of a multi-stream heat exchanger should be preceded by developing a mathematical model. A mixed integer nonlinear model is proposed for a multi-stream heat exchanger on the basis of heat balances and enthalpy changes in the multi-stream heat exchanger. The hypothetical splits of a cold stream is suggested to identify the separate amounts of heat it exchanges with multiple hot streams. The proposed model is illustrated with a three-stream heat exchanger. It will contribute to facilitating efficient operation and control as well as to systematic design of multi-stream heat exchangers.
허필우(Pil-Woo Heo),김덕종(Deok-Jong Kim),김재윤(Jae-Yun Kim),박상진(Sang-Jin Park),윤의수(Eui-Soo Yun),고광식(Kwang-Sik Koh) 한국유체기계학회 2003 유체기계 연구개발 발표회 논문집 Vol.- No.-
Micromixer plays an important role in Bio-MEMS or μ-TAS. Mixing is generally generated by turbulence and interdiffusion of two fluids. Because of low Reynolds number(Re << 2000) in μ-channel, it is difficult to generate turbulence, so mixing mainly depends on interdiffusion. Thus long channel distance is required to mix two different fluids. To reduce the channel length required for mixing, we propose the a new active μ-mixer that two fluids are effectively mixed in μ-channel by the ultrasonic wave which is generated by PZT. The ultrasonic wave is radiated into a chamber in the cross-section directional direction to interface with the two fluids. The two fluids are positioned one on top of the other. Mixing state is measured by the changing of color due to the reaction of NaOH and phenolphtalein.