Thermal analysis and performance prediction on ultrasonic-assisted phase change thermal management device

Solid-liquid phase change materials (PCMs) have obvious advantages in thermal management for temperature-sensitive electronic devices benefiting from their high latent heat storage density and excellent properties of absorbing heat at stable temperatures. Ultrasonic assistance is an available means to enhance heat transfer efficiency of PCMs. In present study, a numerical model for predicting thermal performance of ultrasonic-assisted PCM thermal management unit (TMU) was proposed and validated by experimental results. The influence mechanisms of different ultrasonic loading strategies, including different powers and frequencies, on thermal characteristics of heat sources and PCMs domains were studied through qualitative and quantitative comparisons, including melting, velocity and temperature characteristics. Dimensionless numbers of ultrasonic were defined. Data-driven dimensionless correlation formulas for certain and different heat fluxes were proposed for rapid prediction of steady-state and transient thermal characteristics in thermal management applications of ultrasonic-assisted PCM TMUs. Results indicated that the higher ultrasonic power led to lower and more uniform temperature of heat source. The increase in ultrasonic frequency resulted in two opposing effects. Compared with the non-ultrasonic case, the preferred ultrasonic loading strategy (Pu = 120 W and fu = 100 kHz) could achieve a 50.99 % decrease in average temperatures of heat sources, a 237.39 % increase in average velocities of PCMs domains, and a 75.92 % reduction in temperature nonuniformities of heat sources. The deviation between predicted and actual values of the performance prediction model was mostly less than 10 %, which was of great engineering application significance for design and operational control of ultrasonic-assisted PCMs in the thermal management of temperature-sensitive equipment.