Experimental and numerical investigation of constructal vascular channels for self-cooling: Parallel channels, tree-shaped and hybrid designs

Abstract

a b s t r a c tIn this paper, we show experimentally and numerically how a plate which is subjected to a constant heat load can be kept under an allowable temperature limit. Vascular channels in which coolant fluid flows have been embedded in the plate. Three types of vascular channel designs were compared: parallel channels, tree-shaped and their hybrid. The effects of channel design on the thermal performance for different volume fractions (the fluid volume over the solid volume) are documented. In addition, the effects of the number of channels on cooling performance have been documented. Changing the design from parallel channels to tree-shaped designs decreases the order of pressure drop. Hence increase in the order of the convective heat transfer coefficient is achieved. However, tree-shaped designs do not bathe the entire domain, which increases the conductive resistances. Therefore, additional channels were inserted at the uncooled regions in the tree-shaped design (hybrid design). The best features of both parallel channels and tree-shaped designs are combined in the hybrid of them: the flow resistances to the fluid and heat flow become almost as low as the tree-shaped and parallel channels designs, respectively. The effect of design on the maximum temperature shows that there should be an optimum design for a distinct set of boundary conditions, and this design should be varied as the boundary conditions change. This result is in accord with the constructal law, i.e. the shape should be varied in order to minimize resistances to the flows.

The Effect of Cooling on Mechanical and Thermal Stresses in Vascular Structures

“…Furthermore, the results of Figures 3a and 3b are in accord with the results of Ref. [15]. This shows the deformations (exists in this study which is not included in Ref.…”

“…This shows the deformations (exists in this study which is not included in Ref. [15]) have negligibly small effect on the resistances to the heat and fluid flow.…”

“…Parallel cooling channels are placed in between the tree-shaped channels because of the hot spot occurrence in between the channels which was discussed in Ref. [15].…”

“…Future technologies require miniature structures which are capable of cooling itself under deterministic and random cooling loads. This requirement can be satisfied with self-cooling structures [10][11][12][13][14][15][16][17]. However, they should also be capable of supporting themselves under the applied mechanical load and/or their weight.…”

“…This paper uncovers how the novel hybrid and parallel vascular structures discussed in the literature [15] performs under applied mechanical load and thermal expansion. The effect of cross-section of the vascular channels on the thermal performance and mechanical strength is also uncovered simultaneously with the consideration of thermal stresses.…”