Thermal Stratification (Banana effect)

What is?

Thermal stratification or banana effect occurs mainly in fluids whose density varies as a function of temperature. This is a multitude of processes, including the petrochemical industry and solar thermal plants.

Although it occurs mainly in horizontal pipes, it can occur in vertical lines as a result of the wind or the sun.

Temperature distribution in a pipe with thermal stratification
Thermal stratification at an elbow

When it occurs?

Thermal stratification occurs when heating is neither slow nor uniform, and as a consequence flow channels of different temperatures are generated. The warmer and less dense currents travel through the top of the tube, which expands considerably more than the bottom.

This is how the pipe bends on itself (like a banana, hence its name) generating stresses that must be considered in the calculation, and also high forces and moments that can misalign a rotating equipment.

Example: Thermosolar Plant

EIn solar thermal generation, thermal oil can undergo variations of 0.65 to 1.05 times the density of water. In LNG plant cooling, the gas or nitrogen can be in the liquid phase during filling and rapidly cool the bottom of the pipe without cooling the top.

The HTF can stratify in the horizontal pipe at the discharge of the pumps, where the flow meter is located, when the pump is out of service and the small recirculation flow is not enought to keep all the HTP hot.

Distribución de temperaturas en una tubería con estratificación térmica
Aplique la estratificación térmica en un solo diálogo

AutoPIPE allows you to select the lines to which the thermal stratification will be applied, which allows modeling the heating or cooling in stages of a plant.

Quickly analyze the thermal stratification scenario. Decide on which lines you want to apply them or apply them on the entire set with one click.