PCM: Solidification and Melting in a Fuel Tank

Description

One of the drawbacks of gasoline fuel is that its temperature drops during cold seasons or in cold locations. As the gasoline cools, sediments and gummy deposits form first; then, as the temperature continues to fall, the heavier hydrocarbon molecules begin to freeze and solidify. To prevent gasoline from freezing, the fuel temperature in the storage tank must be raised. One effective way to do this is to circulate a hot fluid through pipes inside the tank. Helical (spiral) tubes are particularly attractive in space-constrained situations, since they provide greater heat transfer within a given volume.

The 3D geometry was created in Design Modeler. The model consists of two main parts: the fuel tank and an internal spiral tube carrying the hot water flow. Meshing was performed in ANSYS Meshing using an unstructured grid, with a total of 511,821 cells.

Methodology

This project simulates a gasoline fuel tank containing a single-pass spiral tube that runs through the tank. The inner tube carries water at a temperature higher than that of the gasoline, transferring heat to the fuel and thereby raising its temperature to prevent freezing inside the tank. To capture the phase change of the gasoline, the Solidification and Melting module is used to model the phase change material (PCM). The simulation is transient.

Conclusion

The greatest degree of melting occurs in the region immediately surrounding the helical tube, where the hot water delivers the most heat. As the heating process continues, the liquid mass fraction steadily increases throughout the tank. The study was conducted over a limited time period, and the results presented here correspond to the end of the simulation.