Numerical Analysis of Fin Length Effect on Phase Change Materials Melting in a Triangular Geometry

ABSTRACT The present study numerically investigates the effect of copper fin length on the melting behavior of RT42 paraffin wax within a triangular enclosure. A two‐dimensional transient model was developed using ANSYS Fluent 16, and the enthalpy–porosity method was employed to simulate the solid–liquid phase change process under a constant wall temperature of 57°C. Four configurations were considered, including a finless enclosure and copper fins with lengths of 5, 10, and 15 mm. The novelty of this work lies in examining the influence of fin length in a triangular PCM enclosure, a geometry that has received considerably less attention than conventional rectangular and cylindrical latent heat storage configurations. The effects of fin length on melting evolution, temperature distribution, liquid fraction development, and natural convection behavior were systematically analyzed. The results demonstrate that increasing fin length substantially enhances thermal performance by improving conductive heat transfer and strengthening buoyancy‐driven flow. The 15 mm fin configuration exhibited the fastest melting process, the most uniform temperature distribution, and the strongest natural convection currents, with maximum velocities reaching approximately 0.0007 m/s, compared with about 0.00015 m/s for the 5 mm fin case. Furthermore, longer fins promoted more effective thermal penetration into the PCM and significantly reduced thermal resistance within the enclosure. The findings confirm that extending copper fin length is an effective approach for accelerating PCM melting and improving the overall performance of compact latent heat thermal energy storage systems.