The impact of the mushy zone parameter ($A_{mushy}$) and the chosen numerical model during the solidification of a commercial paraffin-type phase change material (PCM) in a vertical cylinder under T-history conditions was examined through numerical simulations. The cooling process was modeled using three methods implemented in the CFD software ANSYS Fluent 2020 R2: the enthalpy–porosity method, the apparent heat capacity (AHC) method, and a new model proposed by the authors which incorporates heat capacity directly into ANSYS Fluent. To accurately define the boundary conditions, radiative heat transfer between surfaces was taken into account. Furthermore, the influence of the mushy zone parameter on the simulation accuracy and solidification rate was investigated, with the parameter being treated as a function of the liquid fraction. The results indicate that the proposed model aligns closely with experimental data regarding cooling temperature, offering better predictions compared to the other models. It was observed that temperature varies with time but not with position, suggesting that this model more effectively satisfies the lumped system condition—an essential characteristic of the T-history experiment—compared to the other methods. Additionally, the analysis showed that a higher mushy zone parameter enhances the accuracy of simulations and predicts a shorter solidification time; approximately 11% for the E-p and 7% for the AHC model. Using a variable mushy zone parameter based on the liquid fraction also produced similar results, resulting in an increased solidification rate.

The impact of the mushy zone parameter (Amushy) and the numerical model during the solidification of a commercial paraffin-type PCM in a vertical cylinder under T-history conditions was examined numerically. The cooling process was simulated using three methods implemented in the CFD code ANSYS Fluent 2020 R2: the enthalpy–porosity method, the AHC method, and a new model proposed by the authors, in which heat capacity is directly introduced into ANSYS Fluent. To determine the precise boundary conditions, radiative heat transfer between surfaces is considered. Moreover, the effect of the mushy zone parameter on simulation accuracy and solidification rate has been investigated, with a variable Amushyintroduced as a function of the liquid fraction. The results indicate that the proposed model demonstrates excellent agreement with experimental data for cooling temperature, providing a more accurate prediction than the other models. Additionally, it shows that temperature varies with time but not with position, suggesting that this model more effectively meets the lumped system condition—a key characteristic of the T-history experiment—compared to the other models. The effect of Amushyy indicates that simulations with a high mushy zone parameter are more accurate and predict a shorter solidification time. Additionally, using a variable mushy zone parameter based on liquid fraction yields similar results, leading to an increased solidification rate.