• Journal of the Korean Society of Industry Convergence
• /
• v.21 no.5
• /
• pp.191-195
• /
• 2018

By using an ANSYS product suite (CFX, Ansys Multiphysics), which is a powerful tool for multiphysics analysis of complicated physical phenomena, we performed a structural stress analysis based on fluid flow and heat transfer phenomena within a quick connect/disconnect (QC/DC) bellows system. Considering the extremely low temperatures in the QC/DC environment, an approach to the problem based on complex multi-physics phenomena, where different phenomena interact with each other, is crucial. Therefore, we use a numerical analysis technique where fluid-thermal-structural interactions are combined. In conclusion, when low temperature fluids flow inside bellows, the expected service life is conspicuously reduced due to the thermal stress caused by heat transfer. Therefore, in future research, a structure with considerably reduced thermal stress by robust design optimization will be derived.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.7 no.4
• /
• pp.76-81
• /
• 2008

A cryogenic butterfly valve is used to transfer the liquefied natural gas (LNG) which temperature is $-162^{\circ}C$. This valve is core part in the piping system using LNG. This paper performed coupling analysis using FEM to evaluate safety of cryogenic butterfly valve. Flow analysis is calculated numerically the CAE and CFD methods are useful to predict the thermal matter and the inner flow field of the valve. Thermal analysis and structural analysis used ANSYS Workbench.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2005.06a
• /
• pp.22-30
• /
• 2005

Sloshing loads, produced by the violent liquid free-surface motions inside the cargo tank have become an important design parameter in ship building industry since there have been demands for the increased sizes of the cargo containment system of LNG carriers. In this study, sloshing impact pressure acting on the shell of the spherical cargo tank of an LNG carrier as well as dynamic pressure and flow behavior around the pump tower located at the center of the tank have been calculated. Comparative numerical sloshing simulations for a spherical LNG tank using 2-D LR.FLUIDS which is based on the finite difference method and 3-D MSC.DYTRAN which is capable of calculating nonlinear fluid-structure interaction have been carried out. A method of calculating sloshing-induced dynamic loads and the subsequent structural strength analysis for pump tower of a spherical LNG carrier using MSC. DYTRAN and MSC.NASTRAN have been presented.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.7
• /
• pp.1-7
• /
• 2021

Restrictions on the emissions of nitrogen oxides, sulfur oxides, carbon dioxide, and particulate matter from marine engines are being tightened. Each of these emissions requires different reduction technologies, which are costly and require many pieces of equipment to meet the requirements. Liquefied natural gas (LNG) fuel has a great advantage in reducing harmful emissions emitted from ships. Therefore, the marine engine application of LNG fuel is significantly increasing in new ship buildings. Accordingly, this study analyzed the internal support structure, insulation type, and fuel supply piping system of a 35 m3 International Maritime Organization C type pressurized storage tank of an LNG-fueled ship. Analysis of the heat transfer characteristics revealed that A304L stainless steel has a lower heat flux than A553 nickel steel, but the effect is not significant. The heat flux of pearlite insulation is much lower than that of vacuum insulation. Moreover, the analysis results of the constraint method of the support ring showed no significant difference. A553 steel containing 9% nickel has a higher strength and lower coefficient of thermal expansion than A304L, making it a suitable material for cryogenic containers.

• Progress in Superconductivity and Cryogenics
• /
• v.25 no.4
• /
• pp.65-69
• /
• 2023

Hydrogen is an eco-friendly energy source and is being actively researched in various fields around the world, including mobility and aerospace. In order to effectively utilize hydrogen energy, it should be used in a liquid state with high energy storage density, but when hydrogen is stored in a liquid state, BOG (boil-off gas) is generated due to the temperature difference with the atmosphere. This should be re-condensed when considering storage efficiency and economy. In particular, large-capacity liquid hydrogen storage tank is required a gaseous helium circulation cooling system that cools by circulating cryogenic refrigerant due to the increase in heat intrusion from external air as the heat transfer area increases and the wide distribution of the gas layer inside the tank. In order to effectively apply the system, thermo-hydraulic analysis through process analysis is required. In this study, the condenser design and system characteristics of a gaseous helium circulation cooling system for BOG recondensation of a liquefied hydrogen storage tank were compared.

• Korean Chemical Engineering Research
• /
• v.59 no.2
• /
• pp.209-218
• /
• 2021

First principle-based modeling studies have been performed to improve the heat exchange efficiency of ORV and optimize operation, but the heat transfer coefficient of ORV is an irregular system according to time and location, and it undergoes a complex modeling process. In this study, FNN, LSTM, and AutoML-based modeling were performed to confirm the effectiveness of data-based modeling for complex systems. The prediction accuracy indicated high performance in the order of LSTM > AutoML > FNN in MSE. The performance of AutoML, an automatic design method for machine learning models, was superior to developed FNN, and the total time required for model development was 1/15 compared to LSTM, showing the possibility of using AutoML. The prediction of NG and seawater discharged temperatures using LSTM and AutoML showed an error of less than 0.5K. Using the predictive model, real-time optimization of the amount of LNG vaporized that can be processed using ORV in winter is performed, confirming that up to 23.5% of LNG can be additionally processed, and an ORV optimal operation guideline based on the developed dynamic prediction model was presented.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.2211-2216
• /
• 2007

Liquefied gas vaporizer means machine to vaporize the liquefied gas as liquid nitrogen($LN_2$), liquefied natural gas(LNG), liquid oxygen($LO_2$) etc. In the air type vaporizer, the frozen dew is also created by temperature drop (below 273 K) on vaporizer surface. This problem increases as the time progresses and humidity increases. In addition, the frozen dew gradually becomes frost deposit consequently, heat transfer through vaporizer decreases because frost deposit form adiabatic sheet. Because of this reason, recent vaporizer system is installed as parallel type, this vaporizer system needs more expensive installation costs and more space. This paper was investigated on the heat transfer characteristics of liquefied gas vaporizer with super low temperature and this paper was carried out the numerical about air heating vaporizer with super low temperature. The numerical analysis on the heat transfer was studied on the effect of geometric parameters of the vaporizer, which are length 1000 mm of 4fin75le type vaporizer. 4fin75le means number of fin is 4 and height of fin is 75 mm.

• 한국전산유체공학회:학술대회논문집
• /
• 2010.05a
• /
• pp.252-257
• /
• 2010

The availability of the thermal energy has been deeply recognized recently to encourage the cascade usage of thermal energy from combustion. Within the frame work, a 1 kW class Stirling engine based cogeneration system has been proposed for a unit of a distributed energy system. The capacity has been designed to be adequate for the domestic usage, which requires high compactness as well as low emission and noised. To develop a highly efficient system with satisfying these requirements, a premixed slot flame burner has been proposed and a series of numerical simulation has been performed to establish a design tool for the combustion chamber. The thermal radiation model has been found to highly affect the computational results and a proper resolution to analyze the heat transfer characteristics of the high temperature heat exchanger. Finally, the combustion characteristics of the premixed flame with the metal fiber type burner has been studied.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.2
• /
• pp.187-192
• /
• 2019

Hybrid power storage system with emergency power function for demand management and power outage minimizes the investment cost in the building of buildings and factories requiring emergency power generation facilities, We propose a new business model by developing technology that can secure economical efficiency by reducing power cost at all times. Normally, system power is supplied to load through STS (Static Transfer Switch), and PCS is connected to system in parallel to perform demand management. In order to efficiently operate the electric power through demand forecasting, the EMS issues a charge / discharge command to the ESS as a PMS (Power Management System), and the PMS transmits the command to the PCS controller to operate the system. During the power outage, the STS is rapidly disengaged from the system, and the PCS becomes an independent power supply and can supply constant voltage / constant frequency power to the load side. Therefore, it is possible to secure reliability through verification of actual system linkage and independent operation performance of hybrid ESS, By enabling low-carbon green growth technology to operate in conjunction with an efficient grid, it is possible to improve irregular power quality and contribute to peak load by generating renewable energy through ESS linkage. In addition, the ESS is replacing the frequency follow-up reserve, which is currently under the charge of coal-fired power generation, and thus it is anticipated that the operation cost of the LNG generator with high fuel cost can be reduced.

• Journal of Embryo Transfer
• /
• v.11 no.2
• /
• pp.111-124
• /
• 1996

The present study was carried out to investigate the effects of co-culture cells and growth factors on in vitro culture of Korean native cattle(KNC) embryos fertilized in vitro. Two-eight cell embryos were cultured in vitro using 4 types of co-culture cells and 3 growth factors singly or in combination. The results were as follows, In the co-culture of 2~8 cell embryos with bovine oviductal epithelial cell(BOEC), granulosa cell(BGC), uterine epithelial cell(BUEC) and mouse embryonic fibroblast (MEF) monolayers, the developing rate to blastocysts was significantly(P<0.05) higher with BUEC(32.1%) than with MEF(15.3%), BGC(13.2%) and non co-culture control(11.6%). When the morula co-cultured with BOEC for 5 days following in vitro fertilization were co-cultured with BOEC continuously or with BUEC, respectively, the developing rate to blastocysts was higher with BUEC(73.9%) than with BOEC(56.0%). To examine the effects of growth factors on in vitro development of 2~8 cell embryos, epidermal growth factor(EGF), transforming growth factor-$\beta$l(TGF-$\beta$l) and insulin-like growth factor-1(IGF-1) were added singly or in combination to TCM 199 maturation medium with respective concentration. In a addition of each 10, 30 and SOng /rnl EGF, the developing rate to blastocysts was the highest in lOng /ml EGF(25.3%). In addition of each 1, 2 and Sng /mi TGF-$\beta$1, the developing rate to blastocysts was the highest in lng /ml TGF-$\beta$1(28.8%). In addition of each 50, 100ng/ml JGF-l, the developing rate to blastocysts was higher in 100ng/ml IGF-l(16.5%) than in SOng/mi IGF-1(12.9%). When lOng /ml EGF and lng /ml TGF-$\beta$l was added singly or in combination, the developing rate to blastocysts was similar in groups added singly or in combination with EGF and TGF-$\beta$l (23.l~24.6%), although higher than in control(16.7%). In the co-culture of 2~8 cell embryos Wth BOEC + each 10, 30 and 5Ong /rnl EGF, the developing rate to blastocysts was significantly(p<0.05) higher in BOEC + long /ml EGF(32.3%) than in BOEC + 3Ong /ml EGF(18.9%) and BOEC + song /ml EGF(9.7%). In the co-culture of 2~8 cell embryos with BOEC + each 1, 2, Sng /ml TGF-$\beta$l the developing rate to blastocysts was higher in BOEC + Sng/rnl TGF-$\beta$l(28.2%) than in BOEC + lng /ml TGF-$\beta$l(21.7%) and BOEC + 2ng/ml TGF-$\beta$l(21.4%). In summary, higher developing rate to blastocysts were obtained with co-culture of BUEC for co-culture system, with addition of lOng /ml EGF or lng /ml TGF-$\beta$l for growth factor culture system, and with co-culture of BOEC + lOng /ml EGF or BOEC + Sng /ml TGF-$\beta$l for co-culture + growth factor culture system.