Numerical modelling and flow visualization of mixing of stratified layers and rollover in LNG

Shi, Ji‐Quan; Beduz, C.; Scurlock, R.G.

doi:10.1016/0011-2275(93)90004-8

Cited by 40 publications

(19 citation statements)

References 2 publications

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“…However, this type of modelling approach can also fail if the assumptions on which it is built break down as well. To the best of our knowledge, the only computational studies which investigate the fidelity of the modelling assumptions of the lumped parameter family of models are by Ramsay 7 and Shi et al 8 Shi et al developed a finite volume code which was only used to simulate sidewall heating with an adiabatic base with a single value of the Rayleigh number. Although Ramsay developed a hydrodynamics, heat and mass transport model of double diffusion in stably stratified flows, he used his Chebyshev spectral method-based computational model to focus on the mechanism of instabilities in the stratified waveguide with variation of basal and sidewall heating.…”

Section: Introductionmentioning

confidence: 99%

Rollover instability due to double diffusion in a stably stratified cylindrical tank

Zimmerman

Rees

2007

Physics of Fluids

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Double diffusion of a viscous fluid is simulated for heat leakage driven by buoyant convection under cryogenic storage conditions in a cylindrical tank with laminar flow. If the tank is stably stratified, there is a potential instability due to the inability of the fluid in the lower layer to release heat to the top vapor space, whereas the upper liquid layer can exchange heat and mass through sensible heat transfer and evaporation with the vapor space. Eventually, the lower layer becomes less dense due to thermal expansion and is no longer constrained in the stratification. The rapid rise and overturning of the fluid is termed rollover, and can be accompanied by a potentially explosive release of vapor. In this paper, hydrodynamics and heat and mass transport are used to study the stability characteristics of rollover. The transient state is used as a base state for a linear stability analysis which shows the transition from a "corner eddy" mode spinning down to spinning up is the driver for the rollover instability. Four different vapor-liquid interfacial boundary conditions are tested, with similar results for the time to rollover. Surprisingly, the long time prerollover state is dominated in the laminar flow regime by heat conduction and diffusion, as the expected double roll structure is suppressed and advection plays a small roll in the majority of the prerollover period. Scalings are suggested for controlling dimensionless groups on this prerollover basis that can be used as a guideline to determine the regime of double diffusion-a single roll or a double roll stratification, as well as the severity of the eventual rollover event. An energy analysis demonstrates the switch from practically advection free to free convection regimes.

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Section: Introductionmentioning

confidence: 99%

Rollover instability due to double diffusion in a stably stratified cylindrical tank

Zimmerman

Rees

2007

Physics of Fluids

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“…3,4), which leads to the stratification of liquid in the reservoir. When a temperature difference of altitude of more than 0.1 degrees high probability of spontaneous revolution of different density layers, caused by temperature difference (the phenomenon of "rollover" [4][5][6][7]). The most intensive circulation flows in the liquefied natural gas appear in the wide low reservoirs.…”

Section: Resultsmentioning

confidence: 99%

“…For the low-temperature storage LNG are used the constructions with different geometric and insulating characteristics [3,4]. The analysis of the influence of such characteristics on the formation of the convective flows of liquefied natural gas in the storage tanks is one of important for their design and operation [4][5][6][7]. Accordingly, it is of interest for numerical study of unsteady convective heat transfer in a rectangular LNG storage and analysis of the impact as the geometric dimensions and the influx of heat from the outer limits of the reservoir.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Influence of Heat Insulation on the Thermal Regime of Storage Tanks with Liquefied Natural Gas

Maksimov

Nagornova

Glazyrin

et al. 2016

EPJ Web of Conferences

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Abstract. Is numerically investigated the process of convective heat transfer in the reservoirs of liquefied natural gas (LNG). The regimes of natural convection in a closed rectangular region with different intensity of heat exchange at the external borders are investigated. Is solved the time-dependent system of energy and Navier-Stokes equations in the dimensionless variables "vorticity -the stream function". Are obtained distributions of the hydrodynamic parameters and temperatures, that characterize basic regularities of the processes. The special features of the formation of circulation flows are isolated and the analysis of the temperature distribution in the solution region is carried out. Is shown the influence of geometric characteristics and intensity of heat exchange on the outer boundaries of reservoir on the temperature field in the LNG storage.

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“…The increase in production of liquefied natural gas leads to an increase in the volume of tanks for storage. The intensity of the heat flow through the walls of LNG storage may be quite varied in different range, both depending on the climatic conditions, and depending on the insulating shells in the event of emergencies, such as fire or depressurization of vacuum insulation repository [4][5]. Uneven heat flow at the external borders of the low-temperature storage tank could lead to a global change in the thermal regime in it (for example, the phenomenon -Rollover) [4][5][6][7] and cause major technological accident.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Simulation of Convective Heat Transfer in the Low-Temperature Storage of Liquefied Natural Gas

Shestakov

Dolgova

Maksimov

2015

MATEC Web of Conferences

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Abstract. The article shows the results of mathematical modeling of convective heat transfer in the low-temperature storage of liquefied natural gas. Regime of natural convection in an enclosure with different intensity of the heat flux at the external borders are investigated. Was examined two-dimensional nonstationary problem within the model of Navier-Stokes in dimensionless variables "vorticity -stream function -temperature". Distributions of hydrodynamic parameters and temperatures that characterize the basic regularities of the processes are obtained. Circulating flows are determined and carried out the analysis of vortices formation mechanism and the temperature distribution in solution at conditions of natural convection when the Grashof number (Gr = 10 6 ). A significant influence of heat transfer rate on solutions boundary on flow structure and temperature field in LNG storage tanks.

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Numerical modelling and flow visualization of mixing of stratified layers and rollover in LNG

Cited by 40 publications

References 2 publications

Rollover instability due to double diffusion in a stably stratified cylindrical tank

Rollover instability due to double diffusion in a stably stratified cylindrical tank

Analysis of Influence of Heat Insulation on the Thermal Regime of Storage Tanks with Liquefied Natural Gas

Mathematical Simulation of Convective Heat Transfer in the Low-Temperature Storage of Liquefied Natural Gas

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