Vascular materials cooled with grids and radial channels

Vascularized materials are a new generation of smart-material concepts that offer novel volumetric functionalities such as self-cooling, self-healing, renewal, cleansing, and designed transport properties (permeability, effective thermal conductivity). In this paper, we evaluate the volumetric cooling performance of slabs with embedded flow architectures consisting of grids (G) and radial channels (R). Both flow directions are considered: inlet (1) and outlet (0) in the center of the slab. In total, four configurations (GI, RI, GO, RO) compete for high performance in three directions: (i) low peak of overheating, or low global thermal resistance. (ii) small volume fractions (a) occupied by high temperatures, and (iii) small pumping power. The results show that grids have lower global flow resistance than radial designs while local junction losses are important. The designs with inlet in the center are attractive in having lower global flow resistance than those with outlet in the center. When objective (i) is considered, designs with outlet in the center are recommended, and the gains in performance are significant if junction losses are negligible and Reynolds numbers are small. For objective (ii), RO is attractive if Sv is greater than 10 or Be is smaller than 10(9). When the three objectives (i)-(iii) are considered at the same time, the configurations with the outlet in the center (GO, RO) are superior when the flow system operates at low pumping power, and that GI and RI are attractive at high pumping power. (C) 2008 Elsevier Ltd. All rights reserved.