Flow visualization and thermal resistance measurement of the LED heat sinks with a built-in piezoelectric fan and various flow-runner opens

Abstract

This work experimentally investigated the fluid flow and heat transfer characteristics of specified finned heat sinks with the built-in piezoelectric fan and different configurations of flow-runner opens. Total three kinds of flow-runner opens were employed: the symmetrically lateral rectangular opens (Model A), the symmetrical lateral slot opens (Model B), as well as the bottom rectangular open (Model C) with/without bottom curved panel. The smoke flow visualization results indicate that various configurations of flow-runner opens resulted in different smoke flow fields. The Model C reduced the total thermal resistance by 10.4-21.3%; it was the optimal one to enhance cooling performance herein. The relevant results can be the base in designing such LED finned heat sink with a built-in piezoelectric fan. flowed through the channel between two fins, the traverse motion of piezoelectric blade had transverse oscillation effect on the axial mainstream, which increased the overall heat transfer by 61%, and the increase in the blade oscillation frequency and amplitude could increase the heat transfer rate linearly. Abdullah et al. [5] observed the heat transfer enhancement effect of piezoelectric blade on the finned heat sink. Multiple piezoelectric blades were put between the fins of heat sink vertically or horizontally. The blades performed reciprocating oscillating motion horizontal to the fin surface. The vertical blade resulted in better heat transfer gain, the maximum heat transfer enhancement was 88% compared with natural convection. Ma et al.[6] designed a piezoelectric actuating system. Five blades could be oscillated synchronously by piezoelectric force and magnetic force. The five blades were put between the vertical plate fins in the axial direction of heat sink, performing oscillating motion normal to the fin surface. The results proved that the heat sink temperature was reduced by 17° only by consuming 0.03W. Shyu and Syu [7] designed a piezoelectric fan with four finger-like blades. The four blades could penetrate into the plate fin heat sink. The air flow generated by the oscillating motion of blades could enhance the overall heat transfer of heat sink effectively. Lin [8] indicated when the cylinder was put in forced convection; the surface heat transfer was very bad in the eddy zone of leeward. Therefore, he put a piezoelectric blade on the leeward side of cylinder; the cylinder surface heat transfer in the zone was enhanced by the oscillating air flow generated by the piezoelectric blade. The numerical and experimental results indicated that the quasi-jet flow generated by the piezoelectric blade interacted on the natural convection on cylinder heating surface and the vortices of mainstream, and the overall heat transfer was enhanced by at most 132%, the local heat transfer on the leeward side was enhanced by at most 214%. However, in the specification and position of the piezoelectric blade, if the mainstream Reynolds number exceeded 2200, the quasi-jet flow generated by the piezoelectric blade redu...

Design and Experimental Analysis of Charge Recovery for Piezoelectric Fan

“…Active strategies of heat transfer enhancement have been pursued such as mechanical aids [2], electrostatic fields [3], and fluid vibration [4]. Among them, the PE fan becomes a feasible solution for electronic cooling applications due to its low power consumption, simple structure, high reliability, and low noise emission [5][6][7][8][9].…”