• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.343-350
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• 2004

LNGC suffers a great heat inflow during navigation and this heat inflow inevitably boils off the LNG. The boiled off gas(BOG) is normally consumed as a fuel for ship's engine. The boiled off LNG means a loss of cargo during transportation from the viewpoint of shipper. Therefore, a contract between shipper and ship operator is made on the limit of boiled off rate(BOR) under 0.15 ％／day based on laden voyage. This contract on BOR limit requires that ship's officer has a correct knowledge on BOR for his ship. But, in most cases ship is operated based on only officer's experiences. In this study, author presented a simple model to predict the boiled off gas(BOG) during navigation based on the existing precision heat exchange design technology about the heat distribution on the hull and heat inflow from outside through the hull. The BOG is calculated for ballast and laden voyage based on the actual weather conditions and verified by comparing with the measured BOG for the study ship. The study ship is a membrane type LNGC which is now servicing in Middle east route. Thus, the BOG prediction method which is presented in this study is expected to be used for an useful tool to manage the BOG in now servicing LNGC.

• Journal of Navigation and Port Research
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• v.28 no.5
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• pp.365-372
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• 2004

LNGC suffers a great heat inflow during navigation and this heat inflow inevitably boils off the LNG. The boiled off gas(BOG) is normally consumed as a fuel for ship's engine. The boiled off LNG means a loss of cargo during transportation in the viewpoint of shipper. Therefore, a contract between shipper and ship operator is made for the limitation of BOR under 0.15 ％/day based on laden voyage. This contract on BOR limit requires that ship's officer has a correct knowledge on BOR for his ship. nut, in most cases ship IS operated based on only officer's experiences. In this study, author presented a simple model to predict the BOG during navigation based on the existing precision heat exchange design technology about the heat distribution on the hull and heat inflow from outside through the hull. The BOG is calculated for ballast and laden voyage based on the actual weather conditions and verified by comparing with the measured BOG for the study ship. The study ship is a membrane type LNGC which is now servicing in Middle east route. Thus, the BOG prediction method which is presented in this study is expected to be used for an useful tool to manage the BOG in now servicing LNGC.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.193-200
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• 2011

A BOR(Boil-Off Rate) prediction model for the NO96 membrane-type LNG insulation containment filled with superlite powders during laden voyage is presented in this paper. Finite element model for the unsteady-state heat transfer analysis is constructed by considering the air and water conditions and by employing the homogenization method to simplify the complex insulation material composition. BOR is evaluated in terms of the total amount of heat invaded into LNGCC and its variation to the major variables is investigated by the parametric heat transfer analysis. Based upon the parametric results, a BOR prediction model which is in function of the LNG tank size, the insulation layer thickness and the powder thermal conductivity is derived. Through the verification experiment, the accuracy of the derived prediction model is justified such that the maximum relative difference is less than 1% when compared with the direct numerical estimation using the FEM analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.3
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• pp.393-400
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• 2003

Excessive generation of BOG during the LNG transportation not only causes the severe financial loss but also leads to the unexpected disaster. Therefore, the carrier cargo insulating interior LNG should be carefully designed based upon an accurate heat transfer analysis. However. it is not simple to analyze heat transfer of LNG cargo, because it is in a complex insulation structure and LNG carrier experiences a complicated heat transfer according to various kinds of voyage conditions. In this paper, we carried out the transient finite element heat transfer analysis for a cargo of Mark-111 membrane-type LNG carrier during laden voyage, and we compared heat transfer rates between considering natural convection and considering conduction. For this goal, we developed a PCL program incorporating with a commercial MSC/NASTRAN FEM code.