Simulation on thermal stratification and de-stratification in liquefied gas tanks

The phenomena of thermal stratification and de-stratification in liquefied gas tanks with heat leak through the side wall were researched numerically. The calculating model developed on ANSYS FLUENT 12.0 was verified through the experimental results from literature. The flow behaviors of the liquid and the temperature distributions at stratification and de-stratification stages were illustrated and the interaction between them was analyzed. When the liquid is stratified, the flow field presents a semi-circulation near the liquid surface with a plume-like flow under it and there exists a cold core under the surface which resisting the warmer circulating flow. The de-stratification of the stratified liquid begins when the circulating loops close with the resistance reduced because of the disappearance of the cold core, and once the circulation forms, it extends down to make the thermal stratifications disappear layer by layer from up to down.

► A numerical model is established to predict the thermal response of liquefied gases. ► The thermal stratification and de-stratification phenomena are calculated accurately. ► We illustrate the interaction between the temperature distribution and flow behavior. ► There is a semi-circulation and a cold core near the liquid surface when stratified. ► The de-stratification begins with the cold core dying away and the loops closing.