Numerical investigation on heat dissipation of Al₂O₃ nanofluid based on dual synthetic jets

In the present paper, the enhancement of heat transfer based on dual synthetic jets actuator (DSJA) in a channel with Al₂O₃ nanofluid is numerically studied, and the effects of nanofluid volume fraction on the cooling performance is analyzed. The reciprocating vibration of the actuator’s diaphragm produces alternately inhaled and ejected jets impacting the substrate at the jet port, improving the cooling performance of the device significantly. Meanwhile, nanoparticles increase the thermal conductivity of the fluid, thereby improving the heat transfer performance, but the pressure drops at the inlet and outlet are increased. It is found that the figure of merit (FOM) and degree of thermal enhancement (DTE) values increase with the nanofluid volume fraction, indicating the improvement of the cooling performance to a certain extent by using nanofluids. Moreover, this paper also analyzes the influence of the frequency and equivalent amplitude of the actuator on heat dissipation. The results show that the frequency barely affects the overall heat dissipation performance of the device. By comparison, as the equivalent amplitude increases, the magnitude of the jet velocity increases, the chip temperature decreases, and the cooling performance of the device is better. The working actuator also affects the distribution of nanoparticles in the channel, manifested by the temporally varying distributions of nanoparticles. Those nanoparticles gathered at the substrate bottom will enhance the heat transfer, an essential factor affecting the heat dissipation of the device.