Experimental study of the effects of ultrasound on the heat transfer enhancement in a 3D-printed minichannel heat sink

The aim of this study was to experimentally investigate the effects of an applied ultrasonic field (5 and 13.5 W) with low frequency (31.5 kHz) on both heat transfer characteristics and pressure drop in a circular minichannel heat sink (MCHS). The circular MCHS heat sink with overall dimensions of 50 mm × 50 mm × 5 mm was 3D-printed via the Selective Laser Melting (SLM) technique. The MCHS was made of 316 L stainless steel powder with 12 circular flow channels, each having a hydraulic diameter of 2 mm. The experiment was performed using tap water as the working fluid under a laminar flow regime (106 ≤ Re ≤ 805) with corresponding flow rates of 0.126 to 0.96 lpm. The experimental results showed a 13.5% enhancement in the average heat transfer coefficient under ultrasound for Re = 106. Based on the experimental data, the enhancement of heat transfer is a linear function of the applied ultrasonic power. Furthermore, it was observed that the effects of the ultrasonic field on heat transfer enhancement decreased under the same conditions as the Reynolds number increased. It was found that the ultrasound had only a small effect on the pressure drop. The findings of this study provide evidence that ultrasound is an effective technique for enhancing heat transfer in laminar flow in MCHS.