Effect of Nanofluid Flows on Heat Transfer Intensification of Corrugated Channels with an Oscillating Blade

Abstract

Heat transfer characteristics of Al2O3-water nanofluid inside a corrugated channel with a flat blade were investigated. In total, 380 simulations were performed to study the simultaneous effects of the blade's status (stationary or oscillating) and the channel wall's geometry (straight or corrugated) on thermal-hydraulic performance at different Reynolds numbers (25-500), nanoparticle volume fractions (0-4%) and diameters (25-100 nm). The results indicated that, at high Reynolds numbers, using a stationary/oscillating blade could significantly enhance thermal performance of the corrugated channel compared to the straight one. In both straight and corrugated channels with/without stationary/oscillating blade, the overall Nusselt number increased with increasing the volume fraction and decreasing the nanoparticle diameter. Examining thermal-hydraulic performance index (PI) showed a critical Reynolds number could be detected in the presence of stationary and oscillating blades, at which PI was the maximum and minimum, respectively. Accordingly, activating the oscillating blade at high Reynolds numbers and inactivating the blade at low Reynolds numbers could significantly improve PI. Moreover, PI of both channels, with/without stationary/oscillating blades, was improved with decreasing the volume fraction and increasing the nanoparticle diameter. Although PI had lower sensitivity to the nanoparticle diameter than the volume fraction, increasing the volume fraction increased this sensitivity.