• Journal of Hydrogen and New Energy
• /
• v.32 no.4
• /
• pp.205-211
• /
• 2021

Recently, it is necessary for study on renewable energy due to environmental pollution and fossil fuel depletion. Therefore, in this study, the filling temperature according to the nozzle geometry was evaluated based on the limit temperature specified in SAEJ2601 for charging hydrogen, a new energy. There are three types of nozzles, normal, angle and round, fixed the average pressure ramp rate at 52.5 MPa/min, and the injection temperature was set at 293.4 K. As a result, the lowest temperature distribution was found in the round type, although the final temperature did not differ significantly in the three types of nozzles. In addition, Pearson's coefficient was calculated to correlate the mass flow rate with the heat transfer rate at the inner liner wall, which resulted in a strong linear relationship of 0.98 or higher.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2004.05a
• /
• pp.325-325
• /
• 2004

• Journal of the Korean Vacuum Society
• /
• v.7 no.4
• /
• pp.285-292
• /
• 1998

The vacuum vessel of the KSTAR tokamak has a so large poloidal cross- section that workers can enter into the inside the vessel. To produce a clean plasma with low impurity concentrations it is planned that the whole vessel including plasma facing components will be baked out at $350^{\circ}C$ and the base pressure of the vessel will be kept in the range of ultra high vacuum. Large thermal stresses are expected during bake-outs to a three-dimensionally complex structure of the vessel, consequent ununiformity of the temperature distribution and support systems to resist forces acting on the vessel. In this report variations of the thermal stress according to temperature gradients on the vessel and constraint conditions of supporting structures are studied and some possible counterplans are discussed.

• Journal of the Korean Society of Mechanical Technology
• /
• v.13 no.2
• /
• pp.137-143
• /
• 2011

Fuel Test Loop(FTL) is a facility which could conduct a fuel irradiation test at HANARO(High-flux Advanced Neutron Application Reactor). FTL simulates commercial NPP's operating conditions such as the pressure, temperature and neutron flux levels to conduct the irradiation and thermo-hydraulic tests. The In-Pile Test Section(IPS) installed in HANARO FTL is designed as a pressure vessel design conditions of $350^{\circ}C$, 17.5MPa. The instrumentation MI-cables for thermocouples, SPND and LVDT are passed through the sealing plug, which is in the pressure boundary region and is a part of instrumentation feedthrough of MI-cable. In this study, the brazing method and performance test results are introduced to the sealing plug with BNi-2 filler metal, which is selected with consideration of the compatibility for the coolant. The performance was verified through the insulation resistance test, hydrostatic test, and helium leak test.

• 유체기계공업학회:학술대회논문집
• /
• 2005.12a
• /
• pp.566-572
• /
• 2005

The most crucial factor in membrane LNG ships to ensure sage operations, is how to effectively control tank pressure at the time of excessive generation of boil off gas (BOG). When the ships carry out tank cool down with her retaining heel prior to arrival at loading port, the vessel encounters the critical situation of excessive BOG and high tank pressure that can lead to high degree of risk. This is to provide one of the best ways to secure safe and effective LNG ship operations focusing on the detailed methods of tank cool down to achieve ATR(Arrival Temperature requirement) without building up high tank pressure and excessive BOG and calculating the appropriate heel quantity to be unutilized for tank cool down and fuel during ballast voyage.

• Nuclear Engineering and Technology
• /
• v.47 no.3
• /
• pp.351-361
• /
• 2015

External reactor vessel cooling (ERVC) for in-vessel retention (IVR) has been considered one of the most useful strategies to mitigate severe accidents. However, reliability of this common idea is weakened because many studies were focused on critical heat flux whereas there were diverse uncertainties in structural behaviors as well as thermal-hydraulic phenomena. In the present study, several key factors related to molten corium behaviors and thermal characteristics were examined under multi-layered corium formation conditions. Thereafter, systematic finite element analyses and subsequent damage evaluation with varying parameters were performed on a representative reactor pressure vessel (RPV) to figure out the possibility of high temperature induced failures. From the sensitivity analyses, it was proven that the reactor cavity should be flooded up to the top of the metal layer at least for successful accomplishment of the IVR-ERVC strategy. The thermal flux due to corium formation and the relocation time were also identified as crucial parameters. Moreover, three-layered corium formation conditions led to higher maximum von Mises stress values and consequently shorter creep rupture times as well as higher damage factors of the RPV than those obtained from two-layered conditions.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1581-1584
• /
• 2007

The safety valve is the important equipment used to protect the pressure vessel and pressure facilities from overpressure by discharging the operation medium when the pressure of system is reaching the design pressure of the system. Some materials for a safety valve disk are studied in this paper. A studied safety valve has to resist sulfurous acid and nitric acid. etc. Furthermore teflon which is a general material of the valve easily sticks to a disk and a sliding part of the valve by thermal expansion. Therefore both teflon and stainless-steel are used to improve these problems. The analysis of the thermal expansion is conducted with commercial FEM software to improve the problems. Boundary conditions were temperature and load in this study. From the analysis, the thermal expansion of by teflon/stainless steel-made valve is lower than that of teflon-made valve under high temperature. Thus, teflon/stainless steel-made valve is safe and no malfunction by thermal expansion.

• Journal of Power System Engineering
• /
• v.9 no.4
• /
• pp.214-219
• /
• 2005

The effects of change in injection pressure on spray structure in high temperature and pressure field have been investigated. The analysis of liquid and vapor phases of injected fuel is important for emissions control of diesel engines. Therefore, this work examines the evaporating spray structure using a constant volume vessel. The injection pressure is selected as the experimental parameter, is changed from 72MPa to 112MPa by using a common rail injection system(ECD-U2). The images of liquid and vapor phase in the evaporating free diesel spray are simultaneously taken by exciplex fluorescence method. As a result, it can be confirmed that the distribution of vapor concentration is more uniform in the case of the high injection than in that of the low injection pressure.

• Journal of ILASS-Korea
• /
• v.7 no.3
• /
• pp.18-23
• /
• 2002

An evaporating diesel spray of a common rail lnjector was visualized by LIEF technique. This technique makes it possible to separate the vapor and liquid phase images. The experiment was conducted in a constant volume vessel to make a high temperature and high pressure condition. Three images(vapor and liquid phase images from LIEF and a liquid phase image from Mie scattering) were taken simultaneously in one spray event. The major experimental parameters are the injection pressure and the ambient gas pressure. Also, a relative SMD distribution in a liquid phase was obtained by the ratio of the intensities of the fluorescence and the Mie scattering. The results show that the injection pressure and the ambient gas pressure have a close relation with the spray development and air-fuel muting process.

• Journal of the Korean Vacuum Society
• /
• v.8 no.4A
• /
• pp.397-402
• /
• 1999

The base pressure of the vacuum vessel of KSTAR tokamak is to be ultra high vacuum, $10^{-6}\sim10^{-7}Pa$, to produce a clean plasma with low impurity concentrations. For this purpose, vessel and plasma facing components need to be baked up to $250^{\circ}C$, $350^{\circ}C$ respectively to remove impurities from the plasma-material interaction surfaces. Here the required heating power to be supplied for baking has been calculated according to pre-assumed different temperature profiles (baking scenario and proper baking plan for KSTAR tokamak has been proposed. Mass flow rate and temperature of nitrogen gas for baking has also been calculated.