유용성의 측면에서 기하학적, 열적 비대칭 사다리꼴 휜의 최적화

강형석,Kang, Hyung-Suk 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.5

Optimum fin effectiveness of geometrically and thermally asymmetric trapezoidal fins is represented as a function of the ratio of the fin bottom to top Biot numbers, the ratio of the fin tip to top Biot numbers and fin shape factor. Optimum fin effectiveness is taken as 98% of the maximum fin effectiveness by comparing the increasing rate of fin effectiveness with that of dimensionless fin length. For this analysis, two dimensional separation of variables method is used. Also, the value of the slope of upper surface of the fin and fin efficiency corresponding to optimum effectiveness are presented.

충돌제트를 갖는 회전원판 위 3차원 경계층의 난류특성 (I) - 평균유동장 -

강형석,유정열,최해천,Kang, Hyung Suk,Yoo, Jung Yul,Choi, Haecheon 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.9

The objective of the present study is to investigate experimentally the mean flow characteristics of the three-dimensional turbulent boundary layer over a rotating disk with an impinging jet at the center of the disk, which may be regarded as one of the simplest models for the flow in turbomachinery. A relatively strong radial outflow (crossflow) generated from the impinging jet is added to the radial outflow (crossflow) induced by the centrifugal force in order to create the three-dimensional boundary layer. A new calibration technique has been introduced to determine the velocity direction and magnitude using an I-wire probe, where the uncertainties are ${\pm}1.5^{\circ}$ and ${\pm}0.35\;m/s$, respectively, in the laminar boundary layer region, compared with the known exact solutions. The flow in the tangential direction is of similar type to that associated with a favorable pressure gradient, considering that no wake region appears in wall coordinate velocity profiles and the Clauser shape factor is between 4.0 and 5.3. The flow angle is significantly changed by the crossflow generated by the impinging jet.

진공관형 태양열 집열기를 이용한 건조장치의 열교환기 해석

강형석(Kang, Hyung-Suk),한영민(Han, Young-Min),이귀현(Lee, Gwi-Hyun),이성주(Lee, Sung-Joo),윤세창(Yoon, Sae-Chang) 한국신재생에너지학회 2006 신재생에너지 Vol.2 No.1

The performance enhancement of heat exchanger in the drying system using solar collector with evacuated tubes is analyzed. First, for this analysis, the heat loss from a reversed trapezoidal fin attached at the pipe is calculated as a function of convection characteristic number ratio, fin base length and fin tip length. Also, the optimum heat loss and fin tip length of the fin under certain conditions are presented. The overall surface effectiveness of the cylinder with reversed trapezoidal fins in the heat exchanger are shown as a function of half fin base height, fin lateral slope and fin tip length.

핀 바닥 두께가 변화하는 역 사다리꼴 핀의 최적 설계

강형석(Hyung Suk Kang) 대한설비공학회 2008 설비공학 논문집 Vol.20 No.7

A reversed trapezoidal fin with variable fin base thickness is optimized using a two-dimensional analytical method. For the fin base boundary condition, instead of a constant temperature, heat transfer from the inside fluid to the fin base is considered. Heat loss from the fin tip is not ignored. The maximum heat loss, corresponding optimum fin effectiveness, fin length and base height are presented as a function of the fin base thickness, shape factor and volume.

최대 열손실에 대한 열손실 비에 기준한 Pin 핀의 최적화

강형석(Hyung Suk Kang) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.11

A pin fin with variable fin base thickness is optimized based on the ratio of heat loss to the maximum heat loss using a two-dimensional analytic method. The temperature profile along the normalized radius position in the fin is presented. For fixed fin outer radius, the optimum heat loss, fin length and efficiency as a function of fin base thickness, outer radius, convection characteristic numbers ratio and ambient convection characteristic number are presented. One of the results shows that the effect of fin outer radius and ambient convection characteristic number on the optimum fin length is remarkable.

사각 환형 핀에 대한 1차원과 2차원 해석의 열전달 비교

강형석(Hyung Suk Kang) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-

Heat loss from a convective rectangular profile annular fin with variable inside fluid heat transfer coefficient and fin height is calculated by using both the one dimensional analytic method and two dimensional variables separation method. Heat loss from the two dimensional method and the relative error of heat loss between the one dimensional method and two dimensional method are presented as a function of the fin length, ambient convection characteristic number and fin height. One of the results shows that the relative error of heat loss between one dimensional method and two dimensional method is within 0.7% in the range of given parameters in this study.

비대칭 사다리꼴 핀의 온도분포와 열손실 해석

강형석(Hyung Suk Kang),송년주(Nyeon Joo Song) 대한기계학회 2012 大韓機械學會論文集B Vol.36 No.4

변화되는 위 측면 기울기를 가진 비대칭 사다리꼴 핀의 온도분포가 2차원 해석적 방법을 사용하여 조사되어 진다. 이 비대칭 핀을 위해, 내부유체로부터 내벽까지의 대류, 내벽으로부터 핀 바닥까지의 전도, 그리고 핀 바닥을 통한 전도가 동시에 고려된다. 무차원 핀 길이와 높이좌표 변화에 따른 온도 형상이 보여진다. 또한 핀 아래 끝에서 온도 변화가 핀 형상계수의 함수로 나타내어진다. 핀 길이의 변화에 따라 핀 바닥을 통한 열손실과 각 면으로부터의 열손실들이 비교된다. 결과들 중 하나는 핀 형상계수가 증가함에 따라 핀 아래 끝에서 온도는 선형적으로 감소함을 보여준다. The temperature distribution of an asymmetric trapezoidal fin with various upper lateral surface slopes is investigated by using the two-dimensional analytic method. For this asymmetric fin, convection from the inner fluid to the inner wall, conduction from the inner wall to the fin base and conduction through the fin base are considered simultaneously. The temperature profile with the variation of dimensionless fin length and height coordinates is shown. Also, the temperature variation at the bottom tip of the fin is presented as a function of the fin shape factor. Heat losses through the fin base and from each side are compared for variations in fin length. One of the results shows that temperature at the fin bottom tip decreases linearly as the fin shape factor increases.

고정된 휜 체적에 기준한 원관 내부반경이 변하는 환형 휜의 최적화

강형석(Hyung Suk Kang) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.3

원관 내부반경이 변하는 사각형상 환형 훤의 최적 값들이 변수 분리법에 의하여 제시된다. 최적의 열손실이 존재할 수 있는 주위 대류특성계수의 범위가 나열된다. 최적 열손실, 그와 관련된 최적의 훤 유용성, 훤 길이 그리고 훤 높이가 원관 내부반경, 내부유체 대류특성계수, 훤 체적, 그리고 주위 대류특성계수의 함수로 표현된다. 결과 중 하나는 훤 체적과 훤 바닥반경이 고정되었을 때 최적 열손실, 유용성 그리고 훤 길이는 원관 내부반경의 증가에 따라 선형적으로 증가함을 보여준다. Optimum values of fin performance and dimensions for an annular fin with a rectangular profile and a pipe with variable inner radius are determined by using a variable separation method. The range of ambient convection characteristic number that results in optimum heat loss is listed. The optimum heat loss, corresponding optimum fin effectiveness, fin length, and fin height are presented as a function of the inner radius of the pipe, inner fluid convection characteristic number, fin volume, and ambient convection characteristic number. One of the results shows that the optimum heat loss, fin effectiveness and fin length increase linearly with the inner radius of the pipe when both the fin volume and fin-base radius are fixed.

삼각 핀의 해석과 고정된 핀 바닥 높이에 기준한 최적화

강형석(Kang, Hyung-Suk) 한국신재생에너지학회 2007 신재생에너지 Vol.3 No.1

A triangular fin with variable fin base thickness and base height is analyzed and optimized for the fixed fin base height using a two-dimensional analytical method. At the middle of the fin length, the variation of the temperature along the fin height is listed. The influences of the fin length, base thickness and base height on the heat loss and fin efficiency are analyzed, The optimum heat loss, corresponding optimum efficiency and optimum fin length as a function of the fin base thickness are presented. The optimum heat loss and optimum fin tip length as a function of the convection characteristic number are represented.

핀 바닥두께가 변하는 pin 핀의 해석

강형석(Kang, Hyung-Suk) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.05

A pin fin with variable fin base thickness is analysed by using the one dimensional analytic method. Heat loss and fin thermal resistance are presented as a function of the fin base thickness, pin fin outer radius and convection characteristic numbers ratio. The relationship between the fin outer radius and fin base thickness for the same amount of heat loss is shown. One of the results indicates the fin thermal resistance decreases as the fin outer radius and/or convection characteristic numbers ratio increase whereas the fin thermal resistance is independent on the variation of fin base thickness.