Presets
Playback
Material and boundaries
Charging melts the material from the hot side; discharging freezes it from the cold side. The plateau at the melting point stores latent heat.
Mode
Model checks
The science
What is modelled
A 18 cm x 12 cm slab of phase-change material (paraffin-like) is heated through its left face and cooled through its right face. The solver tracks enthalpy per cell, so the temperature stays near the melting point while latent heat is absorbed, and the melt front appears as the contour where the temperature crosses the melting point. The module is the same file as on the 3D page.
Equations
- Enthalpy:
H(T) = c T + L f(T)with a mushy zone of width Δ; explicit finite volumes with a stable step. - Conduction
q = -k ∇Tinside; convectionq = h (Ts - T)at the plates and the ambient. - Quasi-steady Stefan estimate:
t = ρ L* (s²/(2k) + s/h) / ΔT, L* = L + c ΔT/2.
Checks run in the page
- Enthalpy and temperature are exact inverses; half melted at the melting point.
- Energy conservation: stored enthalpy equals the time integral of the boundary fluxes.
- A separate 1-D run reproduces the Stefan melt-front time within 12 %.
Simplified: no natural convection in the melt, constant properties, a fixed mushy width.
What to try
- Raise the conductivity (graphite foam preset) and watch the front move faster and the plate power rise.
- Switch to Auto cycle to see charge and discharge alternate when the slab is 90 % melted or 10 % melted.
- Increase heat loss to ambient and compare the stored energy with the energy taken from the plate.