Numerical investigation of the effect of the mushy zone parameter and
the thermal properties of paraffin-based PCMs on solidification modeling
under T-history conditions.
Abstract
The impact of the mushy zone parameter ( A mushy ) and thermal
properties during the solidification of a commercial paraffin-type PCM
in a vertical cylinder under T-history conditions was examined
numerically. First, the thermal properties of the paraffin-type PCM and
its temperature profile during solidification under T-history conditions
were experimentally obtained. The solidification process is simulated by
using a numerical model and it was conducted via the commercial CFD code
ANSYS FLUENT 2022. R2. The enthalpy‒porosity model was employed by the
ANSYS FLUENT for solidification and melting. The accuracy of a
simulation is highly sensitive to the software inputs and assumptions.
Therefore, selecting the correct values for thermal properties and the
mushy constant is essential for achieving precise simulation results. To
determine the precise boundary conditions, radiative heat transfer
between surfaces is considered. The results indicate that, between the
four thermal properties, although increasing the thermal conductivity
accelerates the solidification rate, the opposite effect is observed
with increasing latent heat, density, and specific heat, as higher
values of these properties lead to slower cooling. Moreover, the results
highlight that choosing the correct mushy zone parameter is crucial for
accurate solidification modeling. Although the impact of A mush on
solidification is generally less pronounced because conductive heat
transfer dominates compared with the melting process, for paraffin-type
PCMs, a higher A mush value yields results that better align with
experimental data, unlike other PCM materials. Furthermore, the shape
and progression of the solidification is influenced by the mushy zone
parameter and as A mushy increases, solidification in the bottom layers
decreases, with the process becoming more concentrated in the layers
closer to the cold wall.