Thermo-Hydraulic Performance of Partially Blocked Metal-Foam Channels

Exponential growth of heat flux densities in commercial and industrial electronics, and compact heat exchangers demand surfaces and heat sinks with high dissipation rate capabilities. Among different technologies proposed to meet these demands, high-porosity metal foams have attracted the attention of many investigators due to their higher surface area densities as well as higher thermal performance due to the turbulence and tortuosity generated in the flow due to their structure. One of the disadvantages of such metal foams, however, is the attendant higher pressure drop or pumping power penalty. This thesis was undertaken to investigate whether channels partially filled with metal foams can reduce the required pumping power with a minimal loss in thermal performance. The thermo-hydraulic (T-H) performance factor J/F1/3, where J is the Colburn-J factor and F is the friction factor, was used to compare the relative performance of foams for various values of blocking fractions (B), where B is defined as the ratio of the height of the foam to the height of the channel. The metal foam samples considered were 10 PPI (pores per inch) 6101-T6 Aluminum, with porosity of ∼ 94 − 96%, and B of 1/6, 1/3, 2/3, 5/6, and 1. Each of these samples was attached to an aluminum slab embedded in one of the walls, which had a patch heater that acted as a heat source. A modification was made to all B < 1 configurations by attaching an aluminum plate on top, which then separated the foam-free and the foam-filled flows completely. These configurations are denoted by a 'P' in their names (e.g. B = 1/3P is the plated modification of B = 1/3). Experiments were conducted in an in-house designed wind tunnel, with a test section of 45" in length and a cross-section of 3"X3". Reynolds number (based on channel hydraulic diameter and inlet velocity) was varied from 1,000 to 15,000 to capture the flow domains from laminar to turbulent. The data obtained for the three scenarios namely - 1. Contr