This study examines the heat transfer characteristics of PCMs in a three-dimensional Taylor–Couette system, which consists of two concentric cylinders: the inner cylinder rotates while being subjected to a constant heat flux, and the outer cylinder remains stationary. The numerical investigation is performed using the enthalpy–porosity method to simulate the transient melting process of PCM. The study focuses on how the rotational intensity, expressed by the Taylor number, and the annular radius ratio η=r_i/r_o affect the melting dynamics and heat-transfer performance of the PCM. The results show that, after a liquid PCM layer forms near the heated rotating wall, the rotation of the inner cylinder induces Taylor vortices within the molten PCM. These counter-rotating vortices enhance convective heat transfer, promote faster heat distribution, and accelerate the melting process. Increasing the Taylor number results in a significant reduction in wall temperature because of enhanced mixing and forced convection generated by the Taylor vortices. For example, for η=0.5, the average wall temperatures for Ta=0, 4.40×10^5, 6.87×10^5, and 9.89×10^5 are 371.58 K, 346.32 K, 340.40 K, and 334.38 K, respectively. Moreover, the radius ratio influences the flow and heat-transfer behavior. Lower values of η, corresponding to wider annular gaps and thicker PCM layers, improve thermal performance by extending the latent-heat-dominated period. The findings indicate that Taylor-vortex-assisted melting can improve heat transfer in rotating thermal systems, including electric motors and heat exchangers.
