Experimental Investigation Of Heat Transfer Characteristics Research Articles

Experimental investigation of heat-transfer characteristics of centrifugal and tangential disk fans

Experimental investigation of heat-transfer characteristics of centrifugal and tangential disk fans

05/01854 Experimental investigation of heat-transfer characteristics of aluminum-foam heat sinks: Hsieh, W. H. et al. International Journal of Heat and Mass Transfer, 2004, 47, (23), 5149–5157

This paper presents the results of an experimental study of the fatigue mechanisms of Duocel® open cell aluminum foams and the effects of heat treatment on foam fatigue behaviour. The macro-/micro-mechanisms of fatigue were studied for the foams in the as-fabricated (F), annealed (O) and T6-strengthened (T6) conditions. The effects of annealing and T6-strengthening on the stress–strain behavior and plastic collapse strengths of foams were introduced before presenting the results of compression–compression fatigue experiments. The formation of localized deformation bands were investigated using an in-situ digital camera. Scanning electron microscopy (SEM) revealed clear evidence of the surface crack nucleation in the individual struts, prior to the abrupt strain jumps. Fractographic analysis of the failed struts also revealed fatigue striations and surface crack nucleation mechanisms in the struts. Finally, a simple compression–compression fatigue mechanism is proposed to link the observed macro- and micro-scale fatigue mechanisms in open cell aluminum foams.

Experimental investigation of heat-transfer characteristics of aluminum-foam heat sinks

The demand of high speed and miniaturization of electronic components results in increased power dissipation requirement for thermal management. In this work, the effects of porosity ( ε), pore density (PPI) and air velocity on the heat-transfer characteristics of aluminum-foam heat sinks are investigated experimentally. The phenomenon of non-local thermal equilibrium (NLTE) is also observed and reported. Results show that the Nu increases as the pore density increases, due to the fact that aluminum foam with a larger pore density has a larger heat-transfer area. The Nusselt number also increases with the increase of porosity due to the same reason. It is noted that temperatures of the solid and gas phases of the aluminum foam decrease as Reynolds number increases, caused by the increased convective heat-transfer rate at higher Reynolds number. The deduced temperature difference between the solid and gas phases clearly indicates the existence of non-local thermal equilibrium condition within the aluminum-foam heat sink. The increase of the porosity and the pore density enhances the phenomenon of non-local thermal equilibrium. The temperature difference increases with the decrease of Reynolds number and the distance away from the heat source.