Solidification and Melting of PCM on a Corrugated Tube

Solidification and Melting of PCM around a Corrugated Tube, CFD Simulation Training by ANSYS Fluent

This simulation is about the solidification and melting of PCM around a corrugated tube via ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

The present problem investigates the solidification and melting of a phase change material (PCM) inside a tube with a wavy inner surface. In general, phase change materials are materials with organic compounds that can absorb and store large amounts of latent thermal energy.

Thermal energy storage in these materials is achieved during the phase change process (solid phase to liquid or vice versa); So that when changing phase from solid to liquid, it absorbs heat from its surroundings (causes cooling of surrounding space) and when changing phase from liquid to solid, returns heat to its surroundings (causes surrounding space heating).

The phase change material studied in this simulation is paraffin. It has a density equal to 150 kg/m³, a specific heat capacity equal to 2000 j/kg.K, a thermal conductivity equal to 0.2 W/m.K, and a viscosity equal to 0.03499 kg/m.s.

The geometry of the present model is drawn by Design Modeler software. The model is then meshed by ANSYS Meshing software. The model mesh is structured, and 115362 cells have been created.

CFD Method

In this simulation, the solidification and melting model is used to define PCM.

To define paraffin as a phase change agent, the maximum temperature at which the solid phase temperature is (solidus temperature) is 350.15 K, and the minimum temperature at which the liquid phase temperature is (liquidus temperature) is 358.15 K. And the pure solvent melting heat is defined as 176000 j/kg.

The transient solver performs the simulation with a time step equal to 1s.

Solidification and Melting Conclusion

After simulation, the contours of temperature, temperature gradient, pressure, and liquid fraction are obtained. Since the simulation is performed unsteadily, the present results are related to the 7000s of the simulation process.

The results correctly show that the behavior of PCM corresponds to its temperature. The PCM’s temperature increases by receiving the heat of the inner tube; as a result, it undergoes a phase change by releasing its latent heat. In the zones of increased temperature, PCM changes from solid to liquid.