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최훈기,김철환,유근종 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-
The performance prediction is important to reduce the consumption of time and cost in a design step of the plate heat exchanger(PHE). A numerical analysis is performed to study about it in the PHE. This study used a standard k-ε turbulence model for the numerical analysis. Results of the numerical analysis art verified against experimental data in references. Comparison of fanning friction factor and Nusselt number shows a good agreement with the experimental data when the shape information of a plate is exact.
최훈기,유근종,박태봉,은재정,장남영 국립7개대학공동논문집간행위원회 2003 공업기술연구 Vol.3 No.-
Numerical analysis is performed for magnetic and MHD flow fields in Electro-Magnetic(EM) pump. A finite volume method is applied to solve magnetic field governing equations and the Navier-Stokes equations. Vector and scalar potential methods are adopted to obtain the electric and magnetic fields and the resulting Lorentz force in solving Maxwell equations. The magnetic field and velocity distributions are found to be influenced by the magnitude of the Reynolds number and the phase of applied electric current. Computational results indicate that the magnetic flux distribution with changing phase of electric current is characterized by a pair of counter-rotating closed loops. The velocity distribution of the flow field is influenced on the intensity of Lorentz force.
동심환형 곡관의 혼합대류 열전달 현상에 관한 수치적 연구
최훈기,유근종 한국에너지학회 2002 에너지공학 Vol.11 No.4
동심환형 곡관의 내벽면에서 일정한 열전달이 있는 경우에 대하여 혼합대류의 유동장 및 열전달계수를 수치적으로 구하였다. 유동장은 주흐름방향으로의 압력과 온도구배가 일정한 완전발달흐름으로 가정하였다. 유동장의 특성을 나타내는 물리적 변수인 반경비는 0.2, 0.5, Grashof수는 8000, 80000 그리고 Dean수는 0-900범위에서 계산을 실시하였다. 반경비, Grashof수, Dean수를 변화시키며 2차유동, 열유속, 마찰비, 열전달계수에 대한 수치해를 구하였다. 마찰비와 Nusselt수는 Dear수의 제곱근에 비례하게 증가됨을 볼 수 있다. Numerical calculations have been carried out for the mixed convection flow in a concentric curved annulus with constant heat flux boundary condition at inner wall. The flow is assumed to be fully developed so as to maintain a constant streamwise pressure and temperature gradient. Computations have been performed for flows of radius ratio 0.2 and 0.5 with the Dean number lying in the range 0<k<900, and Grashof numbers of 8000 and 80000. The second flow patterns and heat flux profiles are presented. The friction ratio and heat transfer properties for curved annular duct flows are explained in comparison with those for straight annular duct flows. It is found that the friction ratio and the Nusselt number ratio are proportional to $K^{1/2}$ for the wide range of the Dean number considered here.
최훈기,김인호,유근종 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-
A numerical analysis is performed to predict performance of a plate heat exchanger (PHE) and to deduce design factors, The entrance area of the air, channel height, and corrugation number were changed for the analysis. And the results of the numerical analysis were evaluated pressure drop and heat transfer rate with Reynolds number. The results showed that the effect by the change of entrance area is small, but the effect of the change of channel height and corrugation number are large in the performance of PHE.
열교환기의 슬릿-웨이브 핀 성능에 대한 수치해석적 연구
최훈기,조성원,박용갑 대한기계학회 2022 大韓機械學會論文集B Vol.46 No.7
In this study, a numerical simulation was performed on the heat transfer and flow characteristics of a slit-wavy fin-and-tube heat exchanger. ANSYS FLUENT 2020 R1 was used to analyze. This study was conducted on different Reynolds numbers (66, 133, 332, 532, 665) and slit-wavy fin angles (0°, 5°, 10°, 15°, 20°). The results were visually represented using the dimensionless temperature contour and streamline. Finally, the heat transfer and flow characteristics according to the variation Reynolds number and slit-wavy fin angles was investigated using the j and f factors. When the Reynolds number was 66, the j and f factors of slit-wavy fins with an angle of 20° increased by 41% and 85%, respectively, compared to the plain fin. When the Reynolds number was 665, the j and f factors of slit-wavy fins with an angle of 20° increased by 83% and 145%, respectively, compared to the plain fin. 본 연구에서는 슬릿-웨이브 핀 튜브 열교환기의 열전달 및 유동 특성에 대한 수치해석을 수행하였다. 해석에는 ANSYS FLUENT 2020 R1을 이용하였다. Reynolds 수(66, 133, 332, 532, 665)와 슬릿-웨이브 핀의 각도(0°, 5°, 10°, 15°, 20°)의 변화에 대하여 해석을 수행하였다. 무차원 온도장과 유선을 사용하여 결과를 시각적으로 나타내었다. 최종적으로 Reynolds 수와 슬릿-웨이브 핀의 각도 변화에 따른 열전달 및 유동 특성을 무차원수 j factor와 f factor로 나타내었다. 평판 핀과 비교하여 슬릿-웨이브 핀의 각도가 20°인 경우, Reynolds 수가 66에서 j factor와 f factor는 각각 41%와 85% 증가하였고 Reynolds 수가 665에서는 각각 83%와 145% 증가하였다.
법랑코팅 열교환기에서 고온 소성공정에 따른 열전달 및 열응력에 관한 연구
최훈기,임윤승,이종욱 중소기업융합학회 2020 융합정보논문지 Vol.10 No.2
The purpose of this study is to obtain basic data on the optimization of firing process conditions for enamel coating in chemical heat exchanger. The method of increasing the firing temperature in order to apply enamel coating to shell & tube type heat exchanger was examined. The temperature distribution of the heat exchanger in the firing kiln was numerically calculated using a commercial CFD program. The structural safety of the heat exchanger was confirmed by thermal stress analysis using the FSI method. Numerical analysis and experimental results show that there is a problem of safety due to temperature difference when the heat exchanger at room temperature is directly put into a firing kiln at 860℃. Therefore, a preheating process is need to reduce the temperature difference. As in Case2 with fewer firing steps, the first stage preheating temperature of 445℃ and the second stage firing temperature of 860 ℃ are considered to be most suitable. 본 연구는 화공용 열교환기에서 법랑코팅 적용을 위한 고온의 소성 공정조건 최적화에 대한 기초자료를 얻고자 하는데 그 목적이 있다. Shell & Tube 형태인 열교환기에 법랑코팅 적용을 위해 소성온도를 순차적으로 높이는 방안에 대해 검토하였다. 소성로 내부에서 열교환기의 온도분포에 대해 CFD 상용 프로그램으로 수치계산 하여 구한 온도를 하중조건으로 열응력 해석을 수행하는 연성 해석(FSI) 방식을 이용하여 열교환기의 구조 안전성에 미치는 영향을 확인하였다. 수치해석 및 실험결과 상온의 열교환기를 바로 860℃도의 소성로에 넣으면 열교환기의 국부적 온도차로 인한 구조 안전성에 문제가 발생하므로 온도차를 줄이기 위한 예열 과정이 필요하다. 소성공정 단계가 적은 Case2와 같이 1단계 예열온도 445℃, 2단계 소성온도 860℃가 가장 적합한 것으로 판단된다.