Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Investigation of flow characteristics for internal fluid in cryogenic LNG hoses based on structure feature
Miaoer Liu Fangqiu Li Xiaoguang Mi Hao Cheng Xiaohui Zhang Yue Li
CNOOC Gas &Power Group
Beijing，China

ABSTRACT .
Cryogenic LNG hoses is mainly used for LNG unloadinginterconnection between transport ships, in the process of LNG canquickly continuously the effective transmission. The FLNG transmission
performance of cryogenic LNG hoses is vital role for the economy andsafety of marine oil and gas development. Therefore, the detailed
investigation and analysis characteristics for internal flow in cryogenic
LNG hoses has important guiding significance for practical engineering
design. In the work, computational fluid dynamics (CFD) is employed tobuild the numerical model of the internal flow field with corrugatedstructure inside LNG hose. Structural and process parametric studies areperformed to investigate the effects of the pressure, velocity, temperatureand heat transfer coefficient of the internal flow, and also the results fromthis model is verified against the existing experimental results. Moreover,the dimensionless correction coefficient of heat transfer and pressuredrop are obtained for the internal flow characteristics in cryogenic LNG
hose. The results of this research provide a helpful support to the designof cryogenic LNG hose, and also provide some useful reference to thedesign of FLNG unloading process.

KEY WORDS:characteristics; CFD.

Cryogenic LNG hoses; structure feature; flow

INTRODUCTION
The rapid economic development and the urgent need of environmental
protection promote the growing demand for this kind of clean energy-LNG. To bring the gas from the deep sea to land, connections are madebetween LNG producers and carriers or onshore. FLNG transmission
device has been developed and applied in LNG transmission in recentyears due to its low cost, environmental friendliness and excellent
flexibility. With the wider application of floating LNG transmission
devices, the existing LNG transmission technology will be moredemanding. At present, the investigation of the design, manufacture andinstallation of LNG cryogenic transmission pipelines is a hot researcharea all around the world.

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At present, there are two modes of LNG transportation for offshore
application: rigid loading arm transportation and hose transportation.
Although the unloading mode of rigid loading arm can also realize theLNG transportation, its technical conditions and some shortcomings inengineering operation cannot adapt to the extreme and complex
operation conditions of LNG transportation. However, the cryogenic
LNG hoses transmission technology can well meet the safety technicalrequirements and adapt to a variety of special operating conditions. Thisconnection method also greatly improves the loading and unloading
distance of LNG transmission, and the technical performance of a varietyof cryogenic LNG hoses can be complementary (Jin et.al, 2020).
Therefore, cryogenic LNG hoses has great application prospect in thefield of deep-sea LNG exploitation and transportation.
In the FLNG unloading system, the cryogenic LNG hose needs tocomplete the basic function of efficient and safe transmission of LNG.
The flow characteristics for internal fluid of the cryogenic LNG hose will
directly influence the design and operation of the hose duringtransmission. Under the complex ocean engineering conditions, theinternal flow of hose will generate water hammer effect, slug flow,
multiphase flow, and even to produce the problem such as vibration andfatigue, these flow problems would cause great damage to the cryogenic
LNG hose structure and the unloading transmission process. Therefore,
in the design process of cryogenic LNG hose, not only the mechanicalproperties should be considered, but also the internal flow characteristics(Liang et.al, 2019), including pressure drop, flow resistance, heat transfer
performance, gasification capacity, flow control and so on.
Jaiman et. al (2010) established a CFD numerical model for triangularbellows during LNG transmission. The accuracy of the bellows model
established by CFD was verified in this research, which provided
reference and experience for the future application of bellows structure
design and full-scale experimental verification. Wang and Chen (2002)
and Mahmud (2003) analyzed and studied the heat transfer and resistance
performance of fluid inside two sinusoidal corrugated models
respectively, and explained the influence of structural design parameters
and Reynolds number on heat transfer and flow resistance. Vicente (2004)
not only carried out numerical simulation calculation of heat transfer
coefficient and flow resistance performance of bellows model, but also
obtained the specific influence rule of flow and heat transfer performance