Optimizing a Functionally Graded Metal-Matrix Heat Sink Through Growth of a Constructal Tree of Convective Fins

2013 ◽  
Author(s):  
Jacob Kephart ◽  
G. F. Jones
Keyword(s):  
Porous Media ◽  
Heat Exchanger ◽  
Metal Matrix ◽  
Metal Foam ◽  
Functionally Graded ◽  
Constructal Theory ◽  
Fixed Amount ◽  
Surface Areas ◽  
Optimal Material ◽  
Matrix Heat

This work focuses on an analytical approach to understand optimal material utilization in metal matrix heat exchangers. An objective of this work is to develop a bridge between a fully defined and discrete structure to that of a functionally graded porous media. A porous media heat exchanger is a structure which uses porous material, such as a metal foam, to achieve large convective surface areas in a small volume while also using the media as a conductive path from the heat source or sink. Therefore, a functionally graded porous media heat exchanger has a porosity that is specified as a function of position. Constructal theory is used here to develop increasingly complex convective fin structures, optimized at each level of complexity, which have a resulting characteristic of 2-D functional grading. The approach described here is developed from first principles by using Fourier’s law to develop analytical solutions and seeks to yield an optimized heat exchanger configuration that maximizes total heat transfer subject to a fixed amount conductive material, total volume, and flow condition.

Optimizing a Functionally Graded Metal-Matrix Heat Sink Through Growth of a Constructal Tree of Convective Fins

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Jacob Kephart ◽  
G. F. Jones
Keyword(s):  
Heat Sink ◽  
Metal Matrix ◽  
Heated Surface ◽  
Electronics Cooling ◽  
Functionally Graded ◽  
Aspect Ratios ◽  
Volume Porosity ◽  
Convective Fin ◽  
Matrix Heat ◽  
Fin Shape

Optimal material utilization in metal-matrix heat sink is investigated using constructal design (CD) in combination with fin theory to develop a constructal tree of optimally shaped convective fins. The structure is developed through systematic growth of constructs, consisting initially of a single convective fin enveloped in a convective medium. Increasingly complex convective fin structures are created and optimized at each level of complexity to determine optimal fin shapes, aspect ratios, and fin-base thickness ratios. One result of the optimized structures is a functional grading of porosity. The porosity increases as a function of distance from the heated surface in a manner ranging from linear to a power function of distance with exponent of about 2. The degree of nonlinearity in this distribution varies depending on the volume of the heat sink and average packing density and approaches a parabolic shape for large volume. For small volume, porosity approaches a linear function of distance. Thus, a parabolic (or least-material) fin shape at each construct level would not necessarily be optimal. Significant improvements in total heat transfer, up to 55% for the cases considered in this work, were observed when the fin shape is part of the optimization in a constructal tree of convective fins. The results of this work will lead to better understanding of the role played by the porosity distribution in a metal-matrix heat sink and may be applied to the analysis, optimization, and design of more effective heat sinks for electronics cooling and related areas.

scholarly journals Numerical Investigation of the Deformable Porous Media Treated by the Intermittent Microwave

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 757
Author(s):  
Tianyi Su ◽  
Wenqing Zhang ◽  
Zhijun Zhang ◽  
Xiaowei Wang ◽  
Shiwei Zhang
Keyword(s):  
Porous Media ◽  
Heat Transport ◽  
Liquid Water ◽  
Von Mises Stress ◽  
Temperature Deformation ◽  
Local Maxima ◽  
Whole Process ◽  
Surface Areas ◽  
Pulse Ratio ◽  
Von Mises

A 2D axi-symmetric theoretical model of dielectric porous media in intermittent microwave (IMW) thermal process was developed, and the electromagnetic energy, multiphase transport, phase change, large deformation, and glass transition were taken into consideration. From the simulation results, the mass was mainly carried by the liquid water, and the heat was mainly carried by liquid water and solid. The diffusion was the dominant mechanism of the mass transport during the whole process, whereas for the heat transport, the convection dominated the heat transport near the surface areas during the heating stage. The von Mises stress reached local maxima at different locations at different stages, and all were lower than the fracture stress. A material treated by a longer intermittent cycle length with the same pulse ratio (PR) tended to trigger the phenomena of overheat and fracture due to the more intense fluctuation of moisture content, temperature, deformation, and von Mises stress. The model can be extended to simulate the intermittent radio frequency (IRF) process on the basis of which one can select a suitable energy source for a specific process.

scholarly journals Effect of viscous shearing stresses on optimal material designs for flow of fluids through porous media

2021 ◽  
Vol 33 (6) ◽  
pp. 063109
Author(s):  
Tejasree Phatak ◽  
Kalyana B. Nakshatrala
Keyword(s):  
Porous Media ◽  
Optimal Material

scholarly journals Discharge of a composite metal foam/phase change material to air heat exchanger for a domestic thermal storage unit

2020 ◽  
Vol 148 ◽  
pp. 987-1001 ◽  
Author(s):  
Pouyan Talebizadeh Sardari ◽  
Donald Giddings ◽  
David Grant ◽  
Mark Gillott ◽  
Gavin S. Walker
Keyword(s):  
Heat Exchanger ◽  
Phase Change ◽  
Phase Change Material ◽  
Metal Foam ◽  
Thermal Storage ◽  
Storage Unit ◽  
Change Material
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