scholarly journals The Mass and Heat Transfer Characteristics Study of the Natural Convection Evaporation of an LNG Droplet in BOG

2021 ◽  
Vol 2076 (1) ◽  
pp. 012042
Author(s):  
Zhengyang Fei ◽  
Jiajia Deng ◽  
Jinshu Lu ◽  
Bin Wang ◽  
Dawen Xue
Keyword(s):  
Boundary Layer ◽  
Natural Convection ◽  
Droplet Size ◽  
Droplet Surface ◽  
Cfd Model ◽  
Heat Transfer Characteristics ◽  
Temperature Boundary Layer ◽  
Temperature Boundary ◽  
Mass And Heat Transfer ◽  
Lng Tank

Abstract The evaporation process of LNG droplets in BOG is closely related to the cooling down process of the LNG tank, but there isn’t an available droplet evaporation model at present. Been prepared based on the conservation of mass, momentum, and energy, a CFD model of natural convection evaporation of a single LNG saturated droplet in the BOG was developed and applied. The results show that:①There are two distinguished zones around the droplet surface, where the local temperature boundary layer of the droplet gradually thickens and rapidly thickens with the increase of the angle of inflow from 0 ° to 90 ° and from 90 ° to 180 °, respectively; ② With the increase of droplet size, the average thickness of temperature boundary layer increases gradually, which leads to the decrease of relative evaporation rate;③“blowing effect” remains almost unchanged with the increase of droplet size.

Natural Convection from a Horizontal Cylinder—Laminar Regime

1981 ◽  
Vol 103 (3) ◽  
pp. 522-527 ◽  
Author(s):  
B. Farouk ◽  
S. I˙. Gu¨c¸eri
Keyword(s):  
Natural Convection ◽  
Horizontal Cylinder ◽  
Heat Transfer Characteristics ◽  
Convective Flows ◽  
Finite Difference Numerical Method ◽  
Temperature Boundary ◽  
Recirculation Zones ◽  
Boussinesq Fluid ◽  
Temperature Boundary Condition ◽  
Good Agreement

A finite-difference numerical method has been adopted to generate flow patterns and heat transfer characteristics for laminar, steady-state, two-dimensional natural convection around a circular cylinder submerged in an unbounded Boussinesq fluid. The approach allows the use of nonuniform as well as uniform specified temperature and heat flux distributions over the cylindrical surface. Part of the results are generated for reverse convective flows with recirculation zones which occur when part of the cylinder is below the ambient temperature while the remaining part is above. The results for uniform temperature boundary condition are in good agreement with the experimental data and other solutions available in literature.

Characteristics of Heat Transfer During Cooling Down Process in a Single Cargo Tank of LNG Carrier

2020 ◽  
Vol 162 (A3) ◽  
Author(s):  
J J Deng ◽  
L Y Song ◽  
J Xu ◽  
B Liu ◽  
J S Lu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Deep Understanding ◽  
Liquefied Natural Gas ◽  
Cfd Model ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Computational Fluid Dynamics Cfd ◽  
Heat Transfer Simulation ◽  
Lng Tank

A deep understanding of heat transfer characteristics is essential in evaluating risk and putting forward any option for the Liquefied Natural Gas (LNG) tank cooling down process. A novel Computational Fluid Dynamics (CFD) model was built to perform the flow and heat transfer simulation of the process. The predicted results agreed well with the test data from a prototype LNG tank. Then the heat transfer characteristics of the process were analysed. It was found that the vapour temperature and density were linearly varying and became stable after 2.3 hours. A sudden pressure drop risk was identified during the process, which will cause the inwards collapse risk of the invar membrane. Then the proposals to prevent the risks of the inwards collapsing membrane are presented. The heat transfer characteristics of the vapour and different membrane layers were analysed in detail, and if the suggested option was to be implemented this could save about 39% of LNG consumed.

scholarly journals Experimental Study of a Boundary Layer on a Heated Flat Plate

2019 ◽  
Vol 213 ◽  
pp. 02002
Author(s):  
Pavel Antoš ◽  
Sergei Kuznetsov
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Heat Flux ◽  
Flat Plate ◽  
Hot Wire ◽  
Velocity Boundary Layer ◽  
Temperature Boundary Layer ◽  
Temperature Boundary ◽  
Measurement Experiment ◽  
Set Up

Boundary layer on a uniformly heated flat plate was studied experimentally. Both, the velocity boundary layer and the temperature boundary layer, was investigated by means of hot-wire anemometry. A probe with parallel wires was used for velocity-temperature measurement. Experiment was performed in the closed-circuit wind tunnel with several levels of heat flux at the wall. The wall temperature was set up in the interval from 20 ºC to 200 ºC.

On the dynamics of the molecular temperature boundary layer above the sea

1978 ◽  
Vol 15 (3) ◽  
pp. 289-300 ◽  
Author(s):  
Th. Foken ◽  
S. A. Kitajgorodskij ◽  
O. A. Kuznecov
Keyword(s):  
Boundary Layer ◽  
Temperature Boundary Layer ◽  
Temperature Boundary

Investigation of Heat Transfer Efficiency of Improved Intermig Impellers in a Stirred Tank Equipped with Vertical Tubes

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Leizhi Wang ◽  
Yongjun Zhou ◽  
Zhaobo Chen
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Nusselt Number ◽  
Heat Exchange ◽  
Convective Heat Transfer Coefficient ◽  
Simulation Software ◽  
Related Factors ◽  
Temperature Boundary Layer ◽  
Temperature Boundary ◽  
Vertical Tubes

AbstractThe heat transfer of a reactor with improved Intermig impellers was numerically investigated by the finite element method (FEM) simulation software Fluent (V.19). A turbulence model utilized the standard k-ε model, and the turbulent flows in two large vortexes between vertical tubes were collided to form a strong convection. The influence of heat and mass transfer developing from the impeller diameters, the distance between the two impellers (C1), the rotational speed and the installation height of the bottom impeller (C2) were studied. The reactor was equipped with special structure vertical tubes to increase the heat exchange areas. The rate of heat transfer, including criteria such as the convective heat transfer coefficient, the Nusselt number of outside vertical tubes, and the temperature boundary layer thickness, assured the accurate control of the heat exchange mixing state. The experimental testing platform was designed to validate the simulated results, which revealed the influence order of related factors. The Nusselt number Nu was affected by various related factors, resulting in the rotation and diameter of impellers extending far beyond the distance between the two impellers (C1) and the installation height of the impeller (C2). The average temperature boundary layer thicknesses of the symmetrical and middle sections were 3.24 mm and 3.48 mm, respectively. Adjusting the appropriate parameters can accurately control the heat exchange process in such a reactor, and the conclusions provide a significant reference for engineering applications.

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