• Title/Summary/Keyword: Gas insulation

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A Study on the Effect of Evaporation of Liquid Hydrogen Tank Related to Horizontal Sinewave (액화수소 저장탱크의 수평요동이 증발 특성에 미치는 영향에 대한 연구)

  • SEUNG JUN OH;JUN YEONG KWON;JEONG HWAN YOON
    • Transactions of the Korean hydrogen and new energy society
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    • v.34 no.2
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    • pp.155-161
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    • 2023
  • Recently, a study on alternative and renewable energy is being conducted due to energy depletion and environmental problems. In particular, a hydrogen has the advantage of converting and storing the remaining energy into water-electrolyzed hydrogen through renewable energy generation. In general, due to reasons such as insulation problems, a study on high-pressure hydrogen storage tanks and related parts has recently been conducted. However, in the case of liquid hydrogen, the volume can be reduced by about 800 times or more compared to high-pressure hydrogen gas, so the study on this is needed as a technology that can increase energy density. In this study, the evaporation characteristics were analyzed under fixed heat flux conditions for liquid hydrogen storage tanks and the change in thermal stratification according to sloshing was analyzed. The heat flux condition was fixed at 250 W/m2 and the horizontal resonance frequency of the primary mode was applied to the storage tank. As a result, it was confirmed that the thermal stratification phenomenon decreased compared to the case where the slashing was not present due to forced convection when the slashing was present.

Design and Fabrication of an LPVT Embedded in a GIS Spacer (GIS 스페이서 내장형 저전력 측정용 변압기의 설계 및 제작)

  • Seung-Gwan Park;Gyeong-Yeol Lee;Nam-Hoon Kim;Cheol-Hwan Kim;Gyung-Suk Kil
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.2
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    • pp.175-181
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    • 2024
  • In electrical power substations, bulky iron-core potential transformers (PTs) are installed in a tank of gas-insulated switchgear (GIS) to measure system voltages. This paper proposed a low-power voltage transformer (LPVT) that can replace the conventional iron-core PTs in response to the demand for the digitalization of substations. The prototype LPVT consists of a capacitive voltage divider (CVD) which is embedded in a spacer and an impedance matching circuit using passive components. The CVD was fabricated with a flexible PCB to acquire enough insulation performance and withstand vibration and shock during operation. The performance of the LPVT was evaluated at 80%, 100%, and 120% of the rated voltage (38.1 kV) according to IEC 61869-11. An accuracy correction algorithm based on LabVIEW was applied to correct the voltage ratio and phase error. The corrected voltage ratio and phase error were +0.134% and +0.079 min., respectively, which satisfies the accuracy CL 0.2. In addition, the voltage ratio of LPVT was analyzed in ranges of -40~+40℃, and a temperature correction coefficient was applied to maintain the accuracy CL 0.2. By applying the LPVT proposed in this paper to the same rating GIS, it can be reduced the length per GIS bay by 11%, and the amount of SF6 by 5~7%.

A Study on the Integrated Control and Safety Management System for 9% Ni Steel LNG Storage Tank (9% 니켈강재식 LNG 저장탱크용 통합제어안전관리시스템에 관한 연구)

  • Kim, Chung-Kyun
    • Journal of the Korean Institute of Gas
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    • v.14 no.5
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    • pp.13-18
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    • 2010
  • This paper presents the development of an integrated control and safety management system for 9% nickel steel LNG storage tank. The new system added the measuring equipment of pressure, displacement and force compared to the conventional measurement and control system. The measured data has simultaneously been processed by integrating and analyzing with new control equipments and safety management systems. The integrated control and safety management system, which may increase a safety and efficiency of a super-large full containment LNG storage tank, added additional pressure gauges and new displacement/force sensors at the outer side wall and a welding zone of a stiffener and top girder of an inner tank, and the inner side wall of a corner protection tank. The displacement and force sensors may provide failure clues of 9% nickel steel structures such as an inner tank and a corner protection, and a LNG leakage from the inner tank. The conventional leak sensor may not provide proper information on 9% nickel steel tank fracture even though LNG is leaked until the leak detector, which is placed at the insulation area between an inner tank and a corner protection tank, sends a warning signal. Thus, the new integrated control and safety management system is to collect and analyze the temperature, pressure, displacement, force, and LNG density, which are related to the tank system safety and leakage control from the inner tank. The digital data are also measured from control systems such as displacement and force of 9% nickel steel tank safety, LNG level and density, cool-down process, leakage, and pressure controls.

A Study on Integrated Control and Safety Management Systems for LNG Membrane Storage Tank (멤브레인식 LNG 저장탱크용 통합제어안전관리시스템에 대한 연구)

  • Kim, Chung-Kyun
    • Journal of the Korean Institute of Gas
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    • v.14 no.2
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    • pp.40-46
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    • 2010
  • In this study, the integrated control and safety management system for a super-large LNG membrane storage tank has been presented based on the investigation and analysis of measuring equipments and safety analysis system for a conventional LNG membrane storage tank. The integrated control and safety management system, which may increase a safety and efficiency of a super-large LNG membrane storage tank, added additional pressure gauges and new displacement/force sensors at the steel anchor between an inner tank and a prestressed concrete structure. The displacement and force sensors may provide clues of a membrane panel failure and a LNG leakage from the inner tank. The conventional leak sensor may not provide proper information on the membrane panel fracture even though LNG is leaked until the leak detector, which is placed at the insulation area behind an inner tank, send a warning signal. Thus, the new integrated control and safety management system is to collect and analyze the temperature, pressure, displacement, force and LNG density, which are related to the tank system safety and leakage control from the inner tank. The digital data are also measured from measurement systems such as displacement and force of a membrane panel safety, LNG level and density, cool-down process, leakage, and pressure controls.

Effect of Hydrogen(H2) Addition on Flame Shape and Combustion Products in Mixed Coflow Diffusion Flames of Methane(CH4), Ethane(C2H6) and Propane(C3H8) (동축류 메탄(CH4), 에탄(C2H6), 프로판(C3H8) 혼합 확산화염내의 수소(H2) 첨가가 화염 형상 및 연소 생성물에 미치는 영향)

  • Park, Ho-Yong;Yoon, Sung-Hwan;Rho, Beom-Seok;Lee, Won-Ju;Choi, Jae-Hyuk
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.6
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    • pp.780-787
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    • 2019
  • As a carbon-free, green growth alternative, internal and external interest in hydrogen energy and technology is growing. Hydrogen was added to co-axial methane, methane-propane, and methane-propane-ethane diffusion flames, which are the main ingredients of LNG, to evaluate its effect on flame formation and combustion products. The variation in combustion products produced by adding hydrogen gradually to diffusion pyrolysis at room temperature and normal pressure conditions was observed experimentally by using a gas analyzer, and the shape of diffusion pyrolysis was observed step by step using a digital camera. The experimental results showed that the production volume of nitrogen oxides tended to increase and became close to linear as hydrogen was added to the diffusion pyrotechnic. This is because the relatively high temperature of heat insulation and fast combustion speed of hydrogen facilitated the production of thermal NOx. On the other hand, CO2 production tended to decrease as hydrogen was added to reduce the overall carbon ratio contained in the mixed diffusion flame of methane, methane-propane, and methane-ethane-propane. This means that the mixed fuel use of LNG-hydrogen in ships may potentially reduce emissions of CO2, a greenhouse gas.

Effect of graphene oxide on mechanical characteristics of polyurethane foam (산화그래핀이 폴리우레탄 폼 기계적 강도에 미치는 영향)

  • Kim, Jong-Min;Kim, Jeong-Hyeon;Choe, Young-Rak;Park, Sung Kyun;Park, Kang Hyun;Lee, Jae-Myung
    • Journal of Advanced Marine Engineering and Technology
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    • v.40 no.6
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    • pp.493-498
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    • 2016
  • In the present study, graphene oxide based polyurethane foams were manufactured as a part of the development process of mechanically strengthened polyurethane foam insulation material. This material is used in a liquefied natural gas carrier cargo containment system. The temperature of the containment system is $-163^{\circ}C$. First, graphene oxide was synthesized using the Hummers' method, and it was supplemented into polyol-isocyanate reagent by considering a different amount of graphene oxide weight percent. Then, a bulk form of graphene-oxide-polyurethane foam was manufactured. In order to investigate the cell stability of the graphene-oxide-polyurethane foam, its microstructural morphology was observed, and the effect of graphene oxide on microstructure of the polyurethane foam was investigated. In addition, the compressive strength of graphene-oxide-polyurethane foam was measured at ambient and cryogenic temperatures. The cryogenic tests were conducted in a cryogenic chamber equipped with universal testing machine to investigate mechanical and failure characteristics of the graphene-oxide-polyurethane foam. The results revealed that the additions of graphene oxide enhanced the mechanical characteristics of polyurethane foam. However, cell stability and mechanical strength of graphene-oxide-polyurethane foam decreased as the weight percent of graphene oxide was increased.

Preparation of CeO$_2$ Thin Films as an Insulation Layer and Electrical Properties of Pt/$SrBi_2$$Ta_2$$O_9$/$CeO_24/Si MFISFET (절연층인 CeO$_2$박막의 제조 및 Pt/$SrBi_2$$Ta_2$$O_9$/$CeO_24/Si MFISFET 구조의 전기적 특성)

  • Park, Sang-Sik
    • Korean Journal of Materials Research
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    • v.10 no.12
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    • pp.807-811
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    • 2000
  • CeO$_2$ and SrBi$_2$Ta$_2$O$_{9}$ (SBT) thin films for MFISFET (Metal-ferroelectric-insulator-semiconductor-field effect transistor) were deposited by r.f. sputtering and pulsed laser ablation method, respectively. The effects of sputtering gas ratio(Ar:O$_2$) during deposition for CeO$_2$ films were investigated. The CeO$_2$ thin films deposited on Si(100) substrate at $600^{\circ}C$ exhibited (200) preferred orientation. The preferred orientation, Brain size and surface roughness of films decreased with increasing oxygen to argon gas ratio. The films deposited under the condition of Ar:O$_2$= 1 : 1 showed the best C- V characteristics. The leakage current of films showed the order of 10$^{-7}$ ~10$^{-8}$ A at 100kV/cm. The SBT thin films on CeO$_2$/Si substrate showed dense microstructure of polycrystalline phase. From the C-V characteristics of MFIS structure with SBT film annealed at 80$0^{\circ}C$, the memory window width was 0.9V at 5V The leakage current density of Pt/SBT/CeO$_2$/Si structure annealed at 80$0^{\circ}C$ was 4$\times$10$^{-7}$ /$\textrm{cm}^2$ at 5V.

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A Field Survey on the Odor Concentration in Piggery by the Change of the Season (돈사 내에서 계절별 악취 발생 농도 조사 연구)

  • Kam, D.H.;Jeong, J.W.;Choi, H.C.;Song, J.I.;Hong, J.T.;Lee, D.W.;Yoo, Y.H.
    • Journal of Animal Environmental Science
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    • v.13 no.3
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    • pp.187-194
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    • 2007
  • Six pig farms were surveyed to measure the odor concentrations and characteristics of ammonia and sulfide corollary compounds in piggery. They were depended on the scale of piggery, weather conditions such as temperature, humidity, wind speed and direction, scales and types of pig breeding, and manure treatment methods. The highest ammonia concentrations in piggery were measured during the winter, since the tight sealed insulation in piggery made less amount of generated ammonia discharged from piggery. The objective of this study was to measure concentrations of odor in the piggery by season and growing, and to measure concentrations of odor at boundary area. So, we investigated the raising managements, manure managements, and methods of reducing odor according to farm scale. We found that concentration of ammonia gas in the swine fattening piggery in winter was the highest. This result is consistent with the lower ventilation rate to maintain Indoor temperature. In this result, there was no connection between farm scale and ventilating system. Concentration of ammonia gas was 1.64 ppm at one boundary area in the middle scale. $H_2S$, $CH_3SH$, $(CH_3)_2S$, and $(CH_3)_2S_2$ were below the standard of protection odor policy.

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A Rigorous Examination of the Interplay Between Fire Resistance of 1-Hour Rated Fireproof Steel Walls and the Flexural Strength of Individual Panels (1시간 내화구조용 철강재 벽체의 내화성능과 단위 패널 휨강도의 관계 고찰)

  • Jeon, Soo-Min;Ok, Chi-Yeol;Kang, Sung-Hoon
    • Journal of the Korea Institute of Building Construction
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    • v.23 no.5
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    • pp.537-546
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    • 2023
  • For the purpose of fire delineation within buildings, steel walls in Korea are mandated to undergo rigorous certification as fire-resistant entities, substantiated via a series of qualitative assessments. Predominantly, these evaluations comprise the fire resistance test paired with supplementary examinations; specifically for steel walls, these encompass the gas hazard and panel bending strength tests. Given the prevalence of semi-noncombustible core materials, gas hazard tests are largely rendered superfluous, pivoting the focus solely onto the panel bending strength test during the certification trajectory. This particular test is designed to gauge the flexural robustness of individual wall panels. An enhanced bending strength is postulated to fortify both the structural integrity and thermal insulation of the wall by mitigating potential deformations. In this scholarly exploration, an analytical deep dive was undertaken into extant, valid certification test datasets. The endeavor aimed to ascertain the depth of correlation between the designated fire resistance metric and the bending strength, the latter being the sole supplementary assessment for steel walls. In distilling the findings, it was discerned that temperature elevations beyond baseline values exhibited no statistically salient linkage with the panel's bending strength.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.