Evaluation of Heat Transfer Enhancement from an Oscillation Heat Sink Under Free Convection Heat Transfer

Abstract

A heat sink is a device used to dissipate heat generated by electrical and electronic devices; it is classified as an active or passive heat sink according to the cooling process. The present study aims to evaluate the effect of forced vibration on heat sink thermal performance. For this purpose, a heat sink with rectangular longitudinal fins with regular aluminum sections has been selected. The heat sink has nine fins, each measuring 100 × 130 mm and having a thickness of 2 mm. These fins are firmly attached to a 100 × 100 × 10 mm aluminum base that contains a 140 W electric heater. It was installed at the middle height of a 75 × 14× 12 cm vertical duct. It was connected to a system that generated vibrations and the electrical power supply. A test rig contains various measurement devices, including a temperature data logger, an anemometer, and voltage and current meters. The tests were done with three different heat flux amounts: 150, 230, and 360 W/m². The frequency range of the vibrations was 0–50 Hz, and the amplitude ranged from 0.07 to 6.99 mm using free convection. The analysis showed a linear relationship between the heat transfer coefficient and the modified Rayleigh number. This was at a frequency of 0 Hz and a heat flux ranging from 5 to 12 W/m². Throughout the free-convective heat transfer range, even though vibration increased the heat transfer coefficient, it was found that the maximum heat transfer coefficient for overall heat fluxes was reached at 50 Hz. Regarding 150, 230, and 360 W/m², respectively, this coefficient increased by 160, 59.5, and 55.2% compared to 0 Hz. Moreover, vibration has contributed to increased air mass flow at 50 Hz (8.8, 12.7, and 25%) compared to 0 Hz. Also, the results showed that the fin's efficiency decreased due to vibration by 9.8, 9.8, and 11.8% for 150, 230, and 360 W/m², respectively.