Solidification & Melting: PCM in Glass-Coated Circular Chamber

Phase Change Material in a Glass-Coated Circular Chamber — ANSYS Fluent CFD Simulation Tutorial

This project simulates the thermal behavior of a phase change material (PCM) contained within a glass-coated circular chamber using ANSYS Fluent. PCMs are organic or inorganic substances capable of storing and releasing large amounts of latent thermal energy during phase transitions. As a PCM melts from solid to liquid, it absorbs heat from its surroundings; when it solidifies back from liquid to solid, it releases that stored heat back into the environment. Since different PCMs have different melting and freezing points, they are widely used in heating and cooling applications—for example, absorbing ambient heat during the day as latent heat through melting, then releasing it back at night as the material cools and resolidifies.

In this model, the PCM is evenly distributed inside the chamber, which is surrounded by a glass coating held at a constant temperature of 338.15 K, providing the heat input to the PCM.

Geometry and Mesh

The 2-D geometry was created in Design Modeler, representing a circular chamber with an outer radius of 0.0335 m and an inner radius of 0.032 m. The model was meshed in ANSYS Meshing using an unstructured mesh, totaling 4,797 elements.

Methodology

Since the PCM undergoes a solid-liquid phase transition, the Solidification and Melting model is used to capture this behavior, with the PCM initialized at 332.15 K. This model requires defining the solidus temperature (the upper limit at which the material remains fully solid), the liquidus temperature (the lower limit at which the material becomes fully liquid), and the latent heat of fusion of the pure substance. The simulation is run as a transient case over a total duration of 250 minutes (15,000 s), using a time step of 600 s.

Results

Contours of liquid mass fraction and temperature were extracted at 40-minute intervals throughout the simulation. A plot of liquid mass fraction versus time was also generated, showing that the liquid fraction increases progressively over time as the corresponding solid fraction decreases.