"微小溫度差를 測定하기 위한 裝置에 관한 硏究"

芮龍澤 慶北工業專門大學 1983 論文集 Vol.20 No.-

The hydraulic bridge is an instrument for accurate measurement of small static temperature differences of the order of several thousandths of a degree, such as those occurring in flowing fluid systems. It is extremely simple to make and to use. In this paper the bridge's basic principles are outlined and its main features described; also results of proving tests are shown.

垂直 等溫 얼음 平面에서 固體-液體 界面의 移動速度가 自然對流에 미치는 影響

芮龍澤 慶一大學校 1986 論文集 Vol.2 No.1

When an isothermal solid flat plate is in contact with a surrounding pure water which is at a temperature different from that of the wall, it is well known that fluid motion occurs in the vicinity of the wall. This motion is induced by the existence of a density distribution within the fluid as a result of the temperature difference between the wall and the fluid far from the wall. An analytical study has been performed on influence of melting velocity of a vertical ice surface in natural convection immersed in pure cold water. The governing equation with boundary conditions are solved numerically by using code BOUNDS and FDN. The results are as follows; first, in the calculation of the velocity components, u and v of parallel and vertical derection to ice surface, FDM( ?? ≠0) agree with the results of FDM( ?? =0) than similarity. Second, in the mean Nusselt number FDM( ?? ≠0) agree with the results of FDM( ?? =0) than similarity for ?? .

低溫의 소금물 속에 잠겨있는 傾斜진 等溫 얼음 平面의 밑面에 依한 自然對流

芮龍澤 慶一大學校 1991 論文集 Vol.7 No.1

The laminar natural convection flow adjacent to an inclined downward-facing ice plate studied numerically. The numerical results of heat transfer are presented for ambient saline water temperature from 1℃ to 15℃ and inclination angle from 0。 to 60。. They include streamlines, velocity profiles, temperature profiles, local heat transfer coefficients and average Nusselt numbers for the entire flow fields.

벽과 고립된 장애물을 갖는 사각형 밀폐공간내의 자연대류

芮龍澤 慶一大學校 1995 論文集 Vol.11 No.1

The effect of a centered, heat-conducting body on natural convection in a square enclosure was investigated experimentally for an air. Different temperatures were imposed on the opposing vertical walls The fluid flow and hepat transfer processes in the enclosure were govemed by the Rayleigh numbers, the dimensionless body size, and the ratio of the thermal conductivity of the body to that of the fluid Photographs of flow visualization were presented to show the flow field withing the enclosure. And the Nusselt numbers were calculated by the measured temperature nearby the wall surfaces.

最大密度點을 갖는 水平의 물層에 있어서 自然對流의 始作

芮龍澤 慶一大學校 1988 論文集 Vol.4 No.1

An numerical analysis has been performed on onset of natural convection from a horizontal isothermal surface which is immersed in water near its density extremum with rigid-free surface condition. The governing equation for onset of natural constitutes an value problem,as well as a two point boundary value problem. Solutions satiafying the boundary conditions were found using a predictor- corrector method for numerical integration along with the “shooting method”and auterval subdivising. The minimum critical Rayleigh number obtained by numerical calculation was 362.6 for-3≤R≤0.3.

휜의 탑재여부에 따른 혼합 및 복합열전달 영향

예용택 경일대학교 산업기술연구소 1999 産業技術硏究所 論文集 Vol.6 No.-

This paper reports an experimental study of heat transfer from a 3-D module(31×31×7㎣) mounted on the floor of a parrel-plate channel(20mm high, 400mm wide, and 650mm long) to mixed convective air flow(0.3~0.9m/s). The module has two kinds of the finned module and finless module. The base wall is made acrylic plate. The channel width was varied in a range of 62~400mm and the input power to the module 1~8W. Particular attention is directed on the heat transfer from the floor which is under the fluid mechanical and thermal influences from the module. Liquid-crystal thermography showed the effects of flow development from the module and dispersion of thermal wake near the module. Certain key features of the data set obtained by this investigation may serve as a benchmark for thermal design codes based on CFD.

低溫의 물 속에 잠겨있는 傾斜 等溫 얼음 平面의 밑 面에 대한 局所熱傳達係數

芮龍澤 慶一大學校 1987 論文集 Vol.3 No.1

A steady state two dimensional finite difference analysis is presented for the heat, mass, and momentum transfer resulting from the downward-facing inclined ice plate melting into pure water by natural convection. Results of the analysis are presented for free stream temperature from 1.0℃ to 15℃ and inclination angle from 0°to 60°. They include temperature profiles, local heat transfer coefficients, thermal boundary layer thickness for plate length of 0.232m. As inclination angle increase, local heat transfer coefficients decrease, but thermal boundary layer thickness increase. When free stream temperature range of 1.0℃≤T∞≤3℃ and T∞≥5.8℃, local heat transfer coefficients increase but thermal boundary layer thickness decrease with increasing temperature.

低溫의 물 속에 잠겨있는 水平 平面에 의하여 惹起되는 自然對流

芮龍澤 慶一大學校 1992 論文集 Vol.8 No.1

The natural convection from upward and downward facing horizontal isothermal plate immersed in cold water is studied numerically. The temperature of the plate is from 0.0℃ to 8.0℃ and the ambient water temperature is from 1.0℃ to 10.0℃. Numerical results are presented for the velocity profiles, temperature profiles, local heat transfer coefficient, and average Nusselt numbers over the entire flow fields. For the upward facing surface there are upflow and unsteady flow. And the ranges of the ambient water temperatures which give rise to the upflow are more extensive as the temperatures of the isothermal surfsce become more distant from the density extremum temperature. For the downward facing surface, only the downflow region is shown. For the upward facing horizontal isothermal surface, the average Nusselt number is 28.86(Ra)??. And for the downward facing surface, the average Nusselt number is C?(Ra)>??.

열원을 가진 표면으로부터의 복합열전달

김병하,예용택 경일대학교 산업기술연구소 1999 産業技術硏究所 論文集 Vol.6 No.-

본 연구의 목적은 강제대류 공기냉각 방법으로 평판의 표면에 부착한 열원을 효과적인 열분산기로서 사용하는 가능성을 조사하는 것이다. 실험을 수행하기 위하여 31×31×7㎣ 크기의 열발생 모듈을 두평행평판 사이의 바닥에 설치하였다. 바닥면은 아크릴판과 구리판으로 제작하였다. 두 평판 사이에서 공기의 평균 속도는 레이놀드수 2400에서 16600에 해당하는 0.57㎧에서 9.31㎧의 범위 내에서 시험을 수행하였으며, 이때 두평판 사이의 거리는 15~35㎜로 유지하였다. 실험을 통하여 모듈 설치방법, 바닥 물질 두께 및 두 평판 사이의 거리변화, 모듈로부터 공기로의 직접열전달을 통한 열저항 및 바닥을 통한 복합적 열전달에 따른 열저항 등의 변화에 대한 결과들을 조사하였다.

구형용기내의 접촉융해 및 자연대류 복합융해의 연구

文鍾勳,芮龍澤 慶一大學校 1995 論文集 Vol.12 No.2

The combined melting processes of the phase change material(PCM)in spherical capsules were investigated experimentally under various ambient temperature conditions. The spherical capsules filled with the solid n-oc-tadecane initially at its melting temperature were instantaneously submerged into a constant-temperature bath. The density of the solid exceeds that of the liguid, which allows the solid bulk continually to drop toward the bottom of the capsule as melting progresses. It was shown that molten mass fraction can be represented as a function of a dimensionless parameter(t* ste??Ar??), with t* being the Fourier number, Ste the STefan number, and Ar the Ar-chimedes number. The melting shape and the complete melting time for various Stefan numbers has been studied. Further, the effect of ambient pressure was also clarified by the experiment. For the capsule with small diameter, it was found that heat conduction is a dominant heat transfer mode. The combined natural convection and close-contact melting effects should be considered under large diameter and high Stefan number cases. The present experimental data will be compared with the analytical results by other researchers.