Solar Heater of Water Tank with PCM CFD Simulation

Solar Heater of a Water Tank and the Effect of PCM, ANSYS Fluent CFD Simulation Training

This simulation is about the solar heater of a water tank and the effect of PCM via ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

Phase change materials can change phase (from solid to liquid and vice versa) over an almost constant temperature range. The phase change process in such materials is usually accompanied by the exchange of a large volume of energy, referred to as latent phase change heat.

This high volume of heat is exchanged in harmony with nature and automatically and intelligently through ambient temperature changes. These materials have become one of the special energy storage capacities in various uses, like solar heaters.

Due to the increasing need for energy and the limitation of fossil fuels, which are a depleting source and polluting the environment, the need to use new energy sources is felt more than ever. One of the most widely used energies is solar energy.

PCM phase-changing materials with high latent heat are suitable for storing thermal energy, especially solar energy, which has been very popular recently. Meanwhile, phase change materials in the water tank related to solar water heaters are a new method recently being considered.

In this project, using PCM encapsulated in a water tank solar heater has been investigated with different considerations, including the effect of melting and freezing temperature of PCM material, the effect of PCM material volume, and a comparison with no PCM material.

The PCM space’s inner wall is considered a wall with a temperature condition of 603.3 K and a thickness of 0.0015 m. The wall boundary condition with the Adiabatic condition is used for the outer wall of this space.

The geometry of the present model is drawn by Design Modeler software. This geometry is related to a chamber that is a space between two coaxial tubes, and we fill the space between these two coaxial tubes with PCM. The model is then meshed by ANSYS Meshing software. The model mesh is unstructured, and 5803 cells have been created.

Method

The energy equation is activated in this simulation to obtain temperature distribution inside the computational domain.

The solidification and Melting model has been used to analyze the phase change of PCM material from solid to liquid and vice versa due to temperature changes inside the water storage area. We should apply the Boussinesq model to determine the density changes in proportion to temperature.

Also, when we use the solidification and melting model, we should define solidus temperature, liquidus temperature, and latent heat of melting of the pure solvent melting.

Conclusion

After simulation, the contours of temperature, velocity, pressure, and liquid volume fraction are obtained. The results completely confirm that the temperature and liquid fraction are consistent.

As the temperature of the PCM increases under the influence of the inner wall’s thermal boundary condition, the PCM’s liquid fraction also decreases. Because with decreasing temperature, the phase change from liquid to solid occurs, and the solidifying process occurs.