<p style="margin: 0cm 0cm 8pt">A liquefied gas is the liquid form of a substance which, at ambient temperature and at atmospheric pressure, would be a gas. Gases are always liquefied for transportation in bulk simply because more cargo can be fitted in a given volume. LNG carriers are vessels used to store and transport liquefied natural gas. LNG, in its liquid form has the temperature of minus 163 degrees Celsius. Therefore, the types of steel used to build the hull structure must withstand the impact of low temperatures. Cargo Containment System (CCS) is used to reduce the transfer of heat from the outside environment into the cargo tank and to keep the LNG in liquid state. Currently, the most popular types of CCS are designed by GTT (Gaztransport &amp; Technigaz). However, Korean shipyards, KOGAS (Korea Gas Corporation) and many other companies around the world have already developed their own CCS systems. As the LNG tank contains cryogenic liquid, realistic thermal analysis are of a primary importance for a successful design. The safety of the hull structure can’t be ensured without a reasonable thermal analysis. However, the heat transfer analysis for the selection of hull steel grade is generally performed by the CCS developer and each CCS developer company has their own method of temperature calculation, but, each of their procedure and assumption are different from each other. KR has recently developed a guideline for temperature calculation of Membrane type LNG carrier’s hull. This study is a part of the guidelines and focuses on numerical and analytical solution procedures for accurate calculation of hull temperature of LNG carrier. The temperature calculation is performed by analytical method and numerical method using FEM. Both method applies conduction, convection and radiation heat transfer process in the temperature calculation. The first method is easily available and can give a first-hand estimate. The second one allows for the assessment of the structure’s complex geometries. 2D FEM heat transfer analysis is performed to calculate the temperature along the transverse direction of the hull, and 3D FEM is performed to calculate temperature in the cofferdams. For verification and accuracy of these methods, temperature calculation of a Membrane type LNG carrier hull is carried out. Both methods, thoroughly analyzed in this study, could be applied in the design of membrane type LNG carrier hulls.</p>

Development of Methods for Temperature Calculation of Lng Carrier Hull

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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