An Experimental Investigation into the Deployment of 3D, Finned Wing and Shape Memory Alloy Vortex Generators in a Forced Air Convection Heat Pipe Fin Stack

Forced air convection heat pipe cooling systems play an essential role in the thermal management of electronic and power electronic devices such as microprocessors and IGBT’s. With increasing heat dissipation from these devices, novel methods of improving the thermal performance of fin stacks attached to the heat pipe condenser section are required. The current work investigates the use a wing type surface protrusions in the form of 3-D delta wing tabs adhered to the fin surface, thin wings punched out of the fin material and TiNi shape memory alloy delta wings which changed their angles of attack based on the fin surface temperature. The longitudinal vortices generated from the wing designs induce secondary mixing of the cooler free stream air entering the fin stack with the warmer fluid close to the fin surfaces. The change in angle of the attack of the active delta wings provide heat transfer enhancement while managing flow pressure losses across the fin stack. A heat transfer enhancement of 37% compared to a plain fin stack was obtained from the 3-D tabs in a staggered arrangement. The punched-out delta wings in the staggered and in-line arrangements provided enhancements of 30% and 26% respectively. Enhancements from the active delta wings were lower (16%) but these devices were able to manage an increase of approximately 19% in flow pressure losses between their de-activated and activated angles of attack. CFD analysis was also carried out to assess the local heat transfer enhancement effects. The CFD results corresponded well with previously published reports and were consistent with the experimental findings.