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루버 휜형 열 교환기의 유동특성에 대한 수치해석적 연구
이광훈(Gwang Hoon Rhee),박정아(Joung A Park),이대영(Dae-Young Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.4
본 연구에서 수치해석적으로 루버휜형 고밀도 열 교환기 내의 유동특성을 평가하였다. 루버휜의 3 차원 형상을 사용하였으며, 루버피치, 루버각, 휜 피치, 휜 두께를 변화시켜가며 해석을 수행하였다. 본 연구는 전산 해석을 통하여 열 교환기 유용도 압력강하, 휜 효율 등을 측정하여 루버휜의 최적화 모델을 제안하기 위함이다. Numerical analysis of fluid flow performance over louvered fins in compact heat exchangers is presented in this study. This study shows a three dimensional analysis with louvered fin. Simulations were performed for different geometries with varying louver pitch. louver angle. fin pitch and fin thickness in louvered fin. By calculating the heat transfer efficiency. pressure drop. fin effectiveness at various conditions. this study will suggest optimization design for louvered fin.
이광훈(Gwang Hoon Rhee),박진수(Jin Soo Park),김주식(Joo Sik Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In this paper, a computational fluid dynamics(CFD) model is presented for biomass in the gasifier using Star-ccm+ ver. 4.02. Chemical reactions are modeled and a three-dimensional model is presented. Gasification process is simulated by Eddy-breaks up model. The arrhenius equation is used to present reaction rate in each reactions. Effects of equivalence ratio(ER) is studied. Compositions of carbon dioxide, carbon monoxide, hydrogen and methane are gained for the result of numerical simulation.
난류 박리 및 재부착 유동의 해석을 위한 저레이놀즈수 4-방정식 난류 열전달 모형의 개발
이광훈(Gwang-Hoon Rhee),성형진(Hyung-Jin Sung) 한국전산유체공학회 1995 한국전산유체공학회 학술대회논문집 Vol.1995 No.-
In the present study, an improved version of 4-equation low-Reynolds-number 4-equation model is proposed. The equations of the temperature variance (k_θ) and its dissipation rate(ε_θ) are solved, in concert with the equations of the turbulent kinetic energy(k) and its dissipation rate(ε). In the present model, the near-wall effect and the non-equilibrium effect are fully taken into consideration. The validation of the model is then applied to the turbulent flow bebind a backward-facing step and the flow over a blunt body. The predicted results of the present model are compared and evaluated with the relevant experiments.
공기극 맥동 유동이 고분자 전해질 연료전지 성능에 미치는 영향
김윤호(Yun Ho Kim),한훈식(Hun Sik Han),김서영(Seo Young Kim),이광훈(Gwang Hoon Rhee) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
The effect of cathode flow pulsation on the performance enhancement of a 10-cell proton-exchange membrane fuel cell is investigated. In the case of cathode pulsating flow with mean flow, the fuel cell power output and the limiting current density dramatically increase as pulsating frequency increases at given pulsating amplitude, while the fuel cell efficiency slightly decreases. This performance enhancement by cathode pulsating flow is more distinct at low cathode mean flow rates. This result is contributed that the pulsating flow enhances the dispersion inside the cathode channels, and then improving the oxygen and temperature distributions. In the case of cathode pulsating flow without mean flow, the fuel cell stack is operated despite cathode mean flow is absent. The limiting current density is extended as the pulsating frequency and swept distance (amplitude) increase. When the pulsating frequency and swept distance are 2.38Hz and 13.65mm respectively, the fuel cell performance is equal to that the cathode mean flow rate is 1.29 lpm. Also, the case of pulsating flow is more stable at the concentration loss region than the case of non-pulsating flow for the same performance conditions.