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간접냉각이 이용된 지중송전케이블의 적정냉각조건에 관한 연구
박만흥,최규식,서정윤,김재근,이재헌,Park, M.H,Che, G.S.,Seo, J.Y.,Kim, J.G.,Lee, Jae-Heon 대한설비공학회 1992 설비공학 논문집 Vol.4 No.4
The transmission current in a power cable is determined under the condition of separate pipe cooling. To this end, the thermal analysis is conducted with the standard condition of separate pipe cooling system, which constitutes one of the underground power transmission system. The changes of transmission current in a power cable with respect to the variation of temperatures and flow rates of inlet cooling water as well as the cooling spans are also determined. As a consequnce, the corresponding transmission current is shown to vary within allowable limit, resulting in the linear variation of the current for most of the cable routes. The abrupt changes of current, however, for the given flow rate of inlet cooling water in some cooling span lead to the adverse effects on the smooth current transmission within the underground power transmission system. In practice, it is expected that the desinging of the separate pipe cooling system in conjunction with the evaluation of system capacity should take into account the effects of design condition on the inlet cooling flow rate.
박만흥,김재근,이재헌,Park, M.H.,Kim, J.K.,Lee, J.H. 대한설비공학회 1993 설비공학 논문집 Vol.5 No.4
Recently, underground transmission system is growing continuously according to the electric power demand increase in the downtown area. Even if domestic cable makers are manufacturing 154kV oil filled cable and joint, the design technology of cable-joint has not been fully self-reliance. This study is aimed at the detail heat transfer analysis of 154kV cable-joint. So, that is cut into the five sections in order to analyze a conjugate natural convection in two dimensional $r-{\theta}$ coordinate. The streamline and temperature distributions are obtained for each sections. Also the changes of those are analyzed with respect to the variation of transmission currents and cable-joint surface heat transfer coefficients. The same analyses are also shown in view point of the maximum temperature of conductor and local equivalent conductivity.
밸브누설이 존재하는 안전주입계통배관에서의 열성층 유동해석
박만흥(M.H.Park),김광추(K.K.Kim),김태룡(T.Y.Kim),이선기(S.K Lee),김경훈(K.Y. Kim) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
A numerical analysis has been performed to estimate the effect of thermal stratification in the safety<br/> injection system piping lines. This phenomenon of thermal stratification is usually observed in the piping<br/> lines of the safety injection system that is connected high pressure and high temperature system as well<br/> as this system is isolated by isolation valve normally.<br/> This piping lines may be identified as the source of fatigue in the piping system due to the thermal<br/> stress loading which are associated with plant operating modes. The turbulent penetration length,<br/> generally, reaches to 1^st isolation valve in safety injection system piping from reactor coolant system at<br/> normal power operation when a high temperature coolant does not leak out through 1^st isolation valve. At<br/> that time, therefore, the thermal stratification does not appear in the piping between RCS piping and 1^st<br/> isolation valve of safety injection system piping.<br/> When a high temperature coolant leak out through the 1^st isolation valve by any damage of isolation<br/> valve, however, the thermal stratification can occur in the safety injection system piping. At that top and<br/> bottom leakage, the maximum temperature difference of fluid between top and bottom in the piping is,<br/> respectively, estimated about 20 and 27℃. But the thermal load and potential for branch pipes is<br/> considered insignificant, since the maximum temperature difference is less than 27.8℃(maximum<br/> potential temperature difference). Therefore, it is considered that this will be ignored the effect of thermal<br/> stratification in safety injection system piping with valve leakage.
서정일,임장순,이재헌,박만흥,Seoh J. I.,Yim J. S,Lee J. H.,Park M. H. 대한설비공학회 1982 설비저널 Vol.11 No.3
The heat transfer process with boiling on a fin cannot be treated in a conventional manner of assuming a constant heat transfer coefficient. This report proposes a simplified method for determining fin performance. The heat transfer coefficients in boiling region is approximated by n ty power function of superheat. The results yield the temperature gradient as a function of superheat, fin width, and thermal conductivity of the fin. Computed results for water boiling on fin compare favorably with those obtained from a small-increment numerical solution.
김광추(K. C. Kim),박만흥(M. H. Park),염학기(H. K. Youm),김태룡(T. Y. Kim),이선기(S. K. Lee) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Numerical study is carried out for thermal stratification on residual heat removal piping connected with<br/> RCS piping of NPP. The turbulent penetration length reaches to 1^st isolation valve. Thermal stratification<br/> mainly occurs in the horizontal piping connected with elbow. The maximum temperature difference occurs in<br/> the location where horizontal piping starts passing elbow. The temperature difference between upper and<br/> lower of horizontal piping changes with valve leak, curve radius of elbow, pipe thick and connection of hotleg<br/> injection line. Thermal stratification effect in the backward of 1^st valve is small when piping thick is not<br/> considered and when valve is isolated, but is large when piping thick is considered or when valve leaks.
원전 안전주입 배관에서의 In-Leakage 에 의한 열성층 현상에 관한 연구
김광추(K. C. Kim),박만흥(M. H. Park),염학기(H. K. Youm),김태룡(T. Y. Kim),이선기(S. K. Lee) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
In case that in-leakage through the valve disk occurs, a numerical study is performed to estimate on<br/> thermal stratification phenomenon in the Safety Injection piping connected with the Reactor Coolant System<br/> piping of Nuclear Power Plant. As the leakage flow rate increases, the temperature difference between top and<br/> bottom of horizontal piping has the inflection point. In the connection point of valve and piping, the<br/> maximum temperature difference between top and bottom was 185K and occurred in the condition of 10<br/> times of standard leakage flow rate. In the connection point of elbow and horizontal piping, the maximum<br/> temperature difference was 145K and occurred in the condition of 15 times of standard leakage flow rate. In<br/> the vertical piping of Safety Injection piping, the near of connection point between elbow and vertical piping<br/> showed the outstanding thermal stratification phenomenon in comparison with another region because of<br/> turbulent penetration from Reactor Coolant System piping. In order to prevent damage of piping due to the<br/> thermal stratification when in-leakage through the valve disk occurs, the connection points between valve and<br/> piping, and the connection points between elbow and piping need to be inspected continually.
정일석,김유,염학기,박만흥,Jung, I,S,,Kim, Y.,Youm, H.K.,Park, M.H. 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.4
In this paper, the unsteady two dimensional model for the thermal stratification in the pressurizer surge line of PWR plant has been proposed to numerically investigate the heat transfer and flow characteristics. The dimensionless governing equations are solved by using the Control Volume Formulation and SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm. The temperature profile of fluids and pipe wall with time are shown when the thermal stratification occurs in the horizontal pipe. The numerical result shows that the maximum dimensionless temperature difference is about O.514 between hot and cold section of pipe wall at dimensionless time 1,632.