• Title/Summary/Keyword: 선체온도분포

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A Study on the Computation of Hull Temperature Distribution and Boil off Ratio of MRV Type LNG Carrier (MRV형 LNG선의 선체온도분포 및 증발률 산정에 관한 연구)

  • 천병일;김용모;김경근
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.4
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    • pp.986-996
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    • 1994
  • Insulation system of LNG carrier has made important roles such as maintaining a proper Boil off Ratio(BOR) for the cargo and avoiding the excessive low temperature of the adjacent inner hull beyond the permissible limit. At the same time, safety and economy of the LNG transportation by the ship are connected with the performance of the insulation system. Also, thermal insulation system of LNG carrier is one of the most advanced technique with the structure analysis of tank, welding and assembling. In this study a computer program is developed to calculate the hull temperature distribution and BOR, which are important factors in thermal design for the Moss Rosenberg Verft spherical tank type LNG carrier. Detailed results for hhull temperature distribution close to LNG tank, BOR and the thickness effect of insulation material are reported in this paper in the range of standare design sea condition.

Health Monitoring Technology using Optic Fibre Sensors for Ships and Marine Equipment (광섬유센서를 이용한 선박 및 해양기자재의 안전진단 기술)

  • Lee, Sei-Chang;Kim, Jong-Ho;Kim, Jung-Yul;Kim, Yoo-Sung
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2006.06a
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    • pp.275-276
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    • 2006
  • 선박 및 해양기자재의 안전 진단을 위한 기존의 기술은 접 센서(point sensor)를 이용한 변형률 측정 기술이 대부분이라 할 수 있다. 본 논문은 기존의 기술보다 효율적으로 응용될 수 있는 광섬유 센서를 이용한 분포 개념의 온도 및 변형률 측정(DTSS: Distributed Temperature & Strain Sensing) 기술에 대해 소개하고 있다. 이 기술은 선체 응력 모니터링, 해양 구조물 안전진단, subsea flowline 모니터링, platform의 riser 안정성, umbilical 모니터링 등에 활용될 수 있다.

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A Study on Unsteady Temperature Distribution Analysis of Moss Type LNG Carrier by Insulation System (MOSS형 LNG선의 방열구조에 의한 비정상 온도분포해석에 관한 연구)

  • Kim, Jin-Goo;Kim, Yong-Mo;Kim, Chun-Sik
    • Journal of Ocean Engineering and Technology
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    • v.11 no.4
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    • pp.159-168
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    • 1997
  • 본 연구는 Moss형 LNG선박의 방열구조에서 LNG탱크에 침입하는 열량과 선체의 온도분포를 예측하고, 운항 중 LNG탱크를 Cooling down(예냉)하는 경우 발생하는 비정상상태에서 LNG탱크에 발생하는 국부적인 열응력을 검토할 수 있는 비정상 온도분포해석과 LNG증발량을 검토하였다. 특히 운항 중인 선박을 대상으로 일반적인 수치계산시에 필요한 각종 입력절차를 간소화 하고 경계조건 선정시에 비 전문가도 쉽게 이용할 수 있는 전산프로그램을 개발하였다. Moss형 LNG탱크의 예냉작업에 필요한 최적의 냉매량과 예냉조건을 비정상상태에서 해석한 것은 설계자 및 선박 운항자에게 유용하게 이용될 것이다.

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A Study on the Thermal Design of the Cryogenic LNG Carrier (초저온 LNG선의 열설계에 관한 연구)

  • 김용모;고상철;천병일;김경근
    • Journal of Advanced Marine Engineering and Technology
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    • v.17 no.4
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    • pp.1-10
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    • 1993
  • This paper introduces the outline of hull structure to the sorts of LNG carrier briefly. Especially, explains in detail for the insulation system of Moss Rosenberg Verft spherical tank type LNG carrier. It is not easy task to calculate exactly the temperature distribution of hull because of very complicated structure of hull. Therefore, in this paper by the adequate modeling of the Moss Rosengerg spherical tank type LNG carrier, a program is developed which calculate the temperature distribution of every hull and estimate the heat influx from every hull and output the BOR according to the variation of atmospheric conditions on boyage.

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Structural Safety Assessment of Independent Spherical LNG Tank(3rd report) - Safety assessment of tank system against crygenic temperature - (독립구형 LNG 탱크의 구조안전성 평가(제3보) - 탱크시스템의 저온 안전성 검토 -)

  • Yong-Yun Nam;In-Sik Nho;Ho-Sup Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.30 no.4
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    • pp.83-92
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    • 1993
  • This paper describes structural safety assessment techniques against crygenic temperature to design MRV type B LNG tank system. The following items are detail with in detail. (1) Leakage estimation of LNG through the propagating clacks at tank plate was performed and design of the range of catch basin(2ndary barrier) was followed to ensure the safety of ship structures against leaked LNG. (2) Temperature distribution analysis for cargo hold and skirt system was carried out using the steady state heat transfer analysis model for spherical LNG tank system. (3) Thermal stress distribution of skirt and tank system was calculated, where very stiff thermal variation was shwn through item(2) analysis.

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A Study on the Prediction and Control of Welding Deformations of Ship Hull Blocks (선체 블록의 용접변형 예측 및 제어를 위한 연구)

  • C.D. Jang;C.H. Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.37 no.2
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    • pp.127-136
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    • 2000
  • Welding deformations reduce the accuracy of ship hull blocks and decrease the productivity due to correction work. Preparing an error-minimizing guide at the design stage will lead to a high quality as well as high productivity. And a precise method to predict the weld deformation is an essential part of it. This paper proposes an efficient method to predict complicated weld deformations based on the inherent strain theory combined with the finite element method. The inherent strain is determined by the highest temperature and the degree of restraint. In order to calculate the inherent strain exactly, it is considered that the degree of restraint becomes different according to the fabrication stages in real structures. A simulation of a stiffened plate shows the applicability of this method to simple ship hull blocks.

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A Study on the Thermal Analysis of Spray Cooling for the Membrane Type LNGC During the Cool-Down Period (급냉각기간에서 멤브레인형 LNGC의 분무냉각 열해석에 관한 연구)

  • Lee, Jung-Hye;Kim, Kyung-Kue;Ro, Sung-Tack;Chung, Han-Shik;Kim, Seong-Gyu
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.1
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    • pp.125-134
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    • 2003
  • The present paper is concerned to the thermal analysis during the cool-down period of 138,000 m$^3$class GTT MARK-III membrane type LNG carrier servicing with LNG from the Middle East to Korea. It is the cool-down period that cools the insulation wall and the gas in LNG tank to avoid the thermal shock as the start of loading of -162$^{\circ}C$ LNG. For six hours of the standard cool-down period, the temperature of NG falls down from -4$0^{\circ}C$ to -13$0^{\circ}C$ and especially the mean temperature of the 1st barrier in the top side insulation wall falls down from -38.38$^{\circ}C$ to -122.42$^{\circ}C$ in case of IMO design condition. By the 3-D numerical calculation about the cargo tank and the cofferdam, the temperature variation in hulls and insulations is precisely predicted in this paper. And the mean temperature variation of gas is calculated as the function of the spraying rate by the heat balance model during the cool-down period.

Thermal Analysis Comparison of IMO with USCG Design Condition for the INGC During the Cool-down Period (급냉각기간에서 IMO설계조건과 USCG 설계조건에 대한 LMGC 화물탱크의 열해석 비교)

  • Lee, Jung-Hye
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.11
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    • pp.1390-1397
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    • 2004
  • This study is concerned with the thermal analysis during the cool-down period of 135,000㎥ class GT-96 membrane type LNG carrier under IMO and USCG design condition. During the cool-down period, the spraying rate for the NG cooling decreases as the temperature of NG falls down from -4$0^{\circ}C$ to -l3$0^{\circ}C$, and the spraying rate for the cooling of the insulation wall increases as the temperature gradient of the insulation wall is large. It was confirmed that there existed the largest temperature decrease at the first barrier and the first insulation, which are among the insulation wall, especially in the top side of the insulation wall under IMO and USCG design condition. Also, as the NG temperature distribution is fixed, the outer temperature condition under the design condition has influence on the temperature variation at the insulation. By the 3-D numerical calculation about the cargo tank and the cofferdam during the cool-down period, the temperature variation in hulls and insulations is precisely predicted under IMO and USCG design condition. From the comparison between two conditions; IMO design condition shows more severe temperature gradient than USCG design condition, therefore, it provides the conservative estimation of the BOG.

Thermal Analysis for the GT-96 Membrane Type LNGC during the Cool-down Period (GT-96 멤브레인형 LNGC의 급냉기간에서의 열해석)

  • Lee, Jung-Hye;Choi, Hyun-Kue;Choi, Soon-Ho;Oh, Cheol;Kim, Myoung-Hwan;Kim, Kyung-Kun
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1346-1351
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    • 2004
  • This study is concerned with the thermal analysis during the cool-down period of 135,000 $m^3$ class GT-96 membrane type LNG carrier under IMO design condition. The cool-down is performed to cool the insulation wall and the natural gas in cargo tank for six hours to avoid the thermal shock at the start of loading of $-163^{\circ}C$ LNG. During the cool-down period, the spraying rate for the NG cooling decreases as the temperature of NG falls clown from $-40^{\circ}C$ to $-130^{\circ}C$ and the spraying rate for the insulation wall cooling increases as the temperature gradient of the insulation wall is large. It was confirmed that there existed the largest temperature decrease at the 1 st barrier and 1st insulation, which are among the insulation wall, especially in the top side of the insulation wall. By the 3-D numerical calculation about the cargo tank and the cofferdam during the cool-down period, the temperature variation in hulls and insulations is precisely predicted.

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A Study on Thermal Characteristics of Stratospheric Airship Influenced by Solar Radiation (태양복사에너지에 의한 성층권 비행선의 열특성에 관한 연구)

  • Kim Min-Jung;Lee Dae-Won;Roh Tae-Seong;Choi Dong-Whan
    • Journal of the Korean Society of Propulsion Engineers
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    • v.9 no.2
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    • pp.89-96
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    • 2005
  • This study has been performed on the mechanism of heat transfer between stratospheric airship and its surroundings while the airship is staying in the air at the altitude of 20km. The computational grid of airship has been generated and the results influenced by the number and the shape of grids have been compared. The temperature distributions have been obtained through this thermal analysis considering three modes of heat transfer - conduction, convection and radiation - in stratospheric conditions. Based on the airship's surface and inner temperature variations, the influence of temperature distributions on the helium envelope and the payload has been predicted.