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서정세,Suh, J.S. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.4
A numerical study is made on the melting process of an unconstrained ice inside an isothermal ice-ball capsule. The unmelted ice core is continuously ascending on account of buoyancy forces. Such a buoyancy-assisted melting is commonly characterized by the existence of a thin liquid film above the ice core. The present study is motivated to present a full-equation-based analysis of the influences of the initial subcooling and the natural convection on the fluid flow associated with the buoyancy-assisted melting. In the light of the solution strategy, the present study is substantially distinguished from the existing works in that the complete set of governing equations in both the melted and unmelted regions are resolved in one domain. Numerical results are obtained by varying the wall temperature and initial temperature. The present results reported the transition of the flow pattern in a spherical capsule, as the wall temperature was increased over the density inversion point. In addition, time wise variation of the shapes for the liquid film and the lower ice surface, the time rate of change in the melt volume fraction and the melting distance at symmetric line is analyzed and is presented.
스크린 메쉬형 가변전열 히트파이프에서 NCG양에 따른 작동특성 변화
서정세(J.S. Suh),박영식(Y.S. Park),강창호(C.H. Kang),정경택(K.T. Chung),박기호(K.H. Park),이기우(K.W. Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
Experimental study is performed to investigate the effect of heat load and operating temperature on the thermal performance of a heat pipe with screen mesh wick. The heat pipe was designed in 200 screen meshes, 500㎜ length and 12.7㎜ O.D tube of copper, water as working fluid(4.8g) and nitrogen as non-condensible gas(NCG). The heat pipe used in this study has evaporator, condenser and adiabatic section, respectively. Experimental data of axial wall temperature distribution is presented for heat transport capacity, the temperature of cooling water of condenser, inclination angle, and operating temperature. For the results from this study, it is found that, for the same charging mass of working fluid, the initial operating temperature and the overall wall temperatures of heat pipe are higher for NCG charging mass of 5.0×10??㎏ and 3.4×10??㎏, than that of 1.0×10??㎏.
홍정규(J.K. Hong),서정세(J.S. Suh),변길성(G.S. Byon) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
In this study, analysis is made for the effects of groove shape on the thermal performance of a axial groove heat pipe. The mathematical models of two-phase flow in grooved heat pipe are presented for the capillary limitation in steady state. Generally, the heat pipe performance depends on the capillary pressure and liquid flow. The friction force of liquid flow through the groove increases with the groove width decreased, and then the capillary pressure is improved in the gas-liquid interface of groove. Therefore, the optimal groove width shaper exists for the maximum thermal performance of heat pipe. In this paper, the optimal groove shape and scale are presented by considering both capillary pressure and liquid flow.
태양열 집열용 써모사이폰의 Geyser boiling에 대한 실험적 연구
홍정규(J.K. Hong),배찬효(C.H. Bae),정경택(K.T. Chung),서정세(J.S. Suh) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
This study has been carried out to investigate thermosyphon's geyser boiling phenomenon used to solar collector. evaporator section of thermosyphon used to solar collector is very much longer than that of condenser section. From the results from this study, Geyser boiling's cycle depends on cooling water, tilt angle and the applied heat load at the evaporator. In this study, according to heat load, the geyser boiling frequency is lower, but the amplitude higher. For the high tilt angle of heat pipe, the frequency and amplitude are lower and higher in the evaporator region, respectively. Whereas, these phenomena is in contrast in the condenser region.
권영수(Y. S. Kwon),서정세(J. S. Suh) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
The main reason to analyze heat transfer in boiler inside through the performance test in fossil power plant is to increase plant high efficiency and energy saving movement ill the government. This study intends to have trend and analyze the boiler heat transfer through the performance test, so it may give us the heat distribution in boiler inside in super-critical and sub-critical pressure type power plant.