Numerical investigation of the impact of on-demand ultrasonic field activation during cyclic thermal shock on PCM-based heat sinks

This study numerically investigates the performance of a PCM-based heat sink enhanced with ultrasonic transducers under cyclic thermal shock conditions. A total simulation time of 2000 s is considered, including a steady load of 30 W/cm 2 for 1000 s, followed by five shock events (100 s each) at heat fluxes of 45–90 W/cm 2 with 100 s recovery phases. A novel on-demand activation strategy is implemented, where ultrasonic transducers are switched on only during shocks and turned off otherwise, reducing energy use compared with continuous activation. Results indicate that, without ultrasound, the base temperature exceeds 398.15 K at the highest shock, whereas applying 60 W ultrasonics keeps it below 363.15 K. At lower shock levels (45 and 60 W/cm 2 ), transducer powers of 15 and 30 W are sufficient to maintain safe operation. Overall, the proposed strategy substantially enhances thermal management while reducing energy consumption by up to 75 %, representing an effective and practical approach for protecting electronic devices under severe thermal shocks.