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이규정,Lee Kyu-Jung Korea Society of Computational Fluids Engineering 1998 한국전산유체공학회지 Vol.3 No.1
A numerical analysis of thermal stress over temperature variations near the crystal-melt interface is carried out for a floating-zone growth of Cadmium Telluride (CdTe). Thermocapillary convection determines crystal-melt interfacial shape and signature of temperature in the crystal. Large temperature gradients near the crystal-melt interface yield excessive thermal stresses in a crystal, which affect the dislocations of the crystal. Based on the assumption that the crystal is elastic and isotropic, thermal stresses in a crystal are computed and the effects of operating conditions are investigated. The results show that the extreme thermal stresses are concentrated near the interface of a crystal and the radial and the tangential stresses are the dominant ones. Concentrated heating profile increases the stresses within the crystal, otherwise, the pulling rate decreases the stresses.
이규정(Kyu-Jung Lee) 한국전산유체공학회 1998 한국전산유체공학회지 Vol.3 No.1
A numerical analysis of thermal stress over temperature variations near the crystal-melt interface is carried out for a floating~zone growth of Cadmium Telluride (CdTe), Thermocapillary convection determines crystal-melt interfacial shape and signature of temperature in the crystal. Large temperature gradients near the crystal-mel t interface yield excessive thermal stresses in a crystal, which affect the dislocations of the crystal. Based on the assumption that the crystal is elastic and isotropic, thermal stresses in a crystal are computed and the effects of operating conditions are investigated. The results show that the extreme thermal stresses are concentrated near the interface of a crystal and the radial and the tangential stresses are, the dominant ones, Concentrated heating profile increases the stresses within the crystal, otherwise, the pulling rate decreases the stresses.
단위전지 적층수 변화에 따른 연료전지 냉각판의 성능 특성에 대한 수치해석적 연구
김윤호(Yoon-Ho Kim),이규정(Kyu-Jung Lee),김용찬(Yongchan Kim),최종민(Jong Min Choi) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Fuel cell is one of the promising power generation devices to cope with the increasing of the energy consumption and the environmental pollution. Recently, PEM(Polymer electrolyte membrane) fuel cell has been developing vigorously as a small fuel cell system such as automobiles and portable devices. An appropriate temperature control of the PEMFC is very important to get higher performance and reliability. Therefore, the fuel cell stack is composed of MEA and cooling-plate. In this study, the performance of the cooling-plate with a serpentine channel for the fuel cell stack was analyzed according to the ratio of the number of unit cells to the cooling-plate, which was changed from 1 to 5. The cooling performance of the cooling-plate with the ratio of 1 to 1 was more enhanced than it of the others. But, it is also need to consider the compactness of the system in the actual systems.
오창묵(Chang-Mook Oh),이규정(Kyu-Jung Lee) 대한설비공학회 2008 대한설비공학회 학술발표대회논문집 Vol.2008 No.2
The effects of baffles in PEM fuel cell with parallel flow channel has been simulated by using conmmercial program. The simulation has been conducted through the channel and there are four different heights of baffles, No Baffle(Hb=0), Partially Blocked Baffle(0.25, 0.5, 0.75), Fully Blocked Baffle(1) conditions. The result shows that current density changes while placing a baffle at the various positions along the channel. Current density with a single baffle is higher than that without baffle and current density using Fully Blocked Baffle(FBB) is much higher than current density using Partially Blocked Baffle(PBB). When the baffle is closer to outlet of the channel, current density increases. It is found that pressure is related to current density. If the pressure is higher, the better performance will be expected.