Thermophysical properties and convective transport in metal foams and finned metal foam heat sinks

The main objective of this thesis is investigation of convective transport in high porosity metal foams.; An analysis for estimating the effective thermal conductivity ( k_e) of high porosity fibrous metal foams shows that k_e depends strongly on the porosity and the ratio of the cross-sections of the fiber and the intersection.; Fluid flow experiments were conducted on a number of metal foam samples covering a wide range of porosities and pore densities in our in-house wind tunnel in order to determine the permeability (K) and inertial coefficient (f) of these high porosity metal foams. The results show that the permeability, K, increases with pore diameter and porosity of the medium. The inertial coefficient, f, on the other hand, depends only on porosity.; Experiments on buoyancy induced convection in metal foams in horizontal and vertical orientations show that heat transfer is considerably enhanced (by as much as a factor of 20) when metal foam is placed on an isothermal surface.; The vertical orientation results in higher heat transfer rates compared to the horizontal orientation for a given heat sink.; The second part of our proposed research deals with convective transport in finned metal foam heat sinks. Results in forced convection show that these heat sinks can enhance the heat transfer coefficient by a factor of 1.25–1.75 compared to a normal metal foam heat sink while minimally increasing the pressure drop in forced convection.; In buoyancy induced convection, experimental studies were conducted oil finned metal foam heat sinks in both horizontal and vertical orientations. Similar to forced convection, the heat transfer rate was found to increase with increase in number of fins but the relative increase in h progressively decreased with addition of fins. The heat transfer rates obtained in the vertical orientation are higher than those for the horizontal orientation for the same heat sink.; A systematic investigation of the leading and trading edge effects on the thermal performance finned metal foam heat sinks in buoyancy-induced convection was conducted and compared to those for longitudinal heat sinks. The results show that clearances at the leading edges of the heat sink has a dominant effect on the overall thermal performance of the finned metal foam heat sink. The heat transfer coefficient increases considerably with increase in the clearance space (C_L) available at the bottom. The relative enhancement however goes down progressively as C _L is increased. The same effects are also observed in longitudinal finned heat sinks but at a much lower scale. (Abstract shortened by UMI.)...