Description

The present problem simulates the performance of phase change materials (PCM) in a storage tank by ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

These PCMs are a set of spherical shapes inside the interior of a vertical cylindrical storage tank. The function of these PCMs is that the water flow from the inlet pipe located at the top of the tank enters the internal space with a velocity of 0.1 m/s and a temperature of 343 K.

Then, the water flow comes out of the upper part of the tank. Because the nature of the PCM of the present model is based on the phase change between the two solid and liquid phases, we use the Solidification and Melting model for simulation.

Because the simulation process is transient over time, the simulation time is in the range of 100 s and with a time step size of 1s.

This simulation has been done in several different modes; Thus, two types of PCM of paraffin and sat-g have been performed in spheres with a radius of 4 cm and 5 cm and at two different melting temperatures of 333.15 K and 332 K, respectively.

The present study aimed to investigate the fluid and thermal behavior of the PCMs and to change the ratio of the liquid mass fraction based on the physical dimensions of the phase change materials (radii of the spheres), melting point temperature and material.

This model's geometry is three-dimensional and designed using ِ Design Modeler software. We use the ANSYS Meshing software to mesh the present model. The mesh type is unstructured, and the element number equals 757886.

PCM Methodology

Since the present problem is related to the simulation of solid-liquid type phase change materials, this model, which is specific to the phase change process between solid and liquid states, has been used.

In the present problem, two different materials have been used paraffin and sat-g. Therefore, these materials are defined by their specific thermophysical properties for Fluent software.

PCM Conclusion

After the solution, we obtain two-dimensional and three-dimensional contours of pressure, temperature, velocity, and liquid and solid mass fractions. These contours are related to the final second of the process. Also, we obtain the graph of the change in the mass fraction of the PCM overtime during the simulation process.

The diagram shows that the longer it takes to dissolve, the more PCM material melts. Up to this point, some PCM material has melted, in return for which the tank temperature has risen. In areas where the temperature is higher, the pressure is lower.