Silicon Spaced Wafer Stack Thermoacoustic Refrigerator Design and Testing

2002 ◽  
Author(s):  
D. G. Holmberg ◽  
S. Y. Tsai ◽  
A. M. Wo
Keyword(s):  
Heat Conduction ◽  
Acoustic Propagation ◽  
Small Scale ◽  
Acoustic Source ◽  
Test Platform ◽  
Anisotropic Heat Conduction ◽  
Design And Testing ◽  
Good Heat ◽  
Si Wafer ◽  
Thermoacoustic Refrigerator

The design of a new, small-scale thermoacoustic refrigerator stack and heat exchanger test platform is presented. A special silicon (Si) stack is fabricated to encourage anisotropic heat conduction — good heat conduction along the plane of the Si wafer (normal to the direction of acoustic propagation) and poor conduction across it (along the direction of acoustic propagation). This is accomplished by separating two wafer pieces with an insulator in between. The aim of this paper is to quantify the performance of this stack arrangement. The apparatus utilizes a modified piston engine with a motor running the piston (max 300 Hz) as an acoustic source. Comparison of results show that the a slight performance degradation for the Si stack compared with that of the ceramic stack. It is believed that advantages gain by suppressing heat conduction along the stack is offset by increased losses due to viscous effect and flow streaming within the Si stack.

scholarly journals FORMULATION OF THE HEAT CONDUCTION EQUATION FOR HETEROGENEOUS MEDIA WITH MULTIPLE SPATIAL SCALES USING REITERATED HOMOGENIZATION

2016 ◽  
Vol 15 (1) ◽  
pp. 96
Author(s):  
E. Iglesias-Rodríguez ◽  
M. E. Cruz ◽  
J. Bravo-Castillero ◽  
R. Guinovart-Díaz ◽  
R. Rodríguez-Ramos ◽  
...  
Keyword(s):  
Heat Conduction ◽  
Small Parameter ◽  
Heat Conduction Equation ◽  
Heterogeneous Media ◽  
Spatial Scales ◽  
Conduction Equation ◽  
Small Scale ◽  
Multiple Spatial Scales ◽  
Effective Coefficients ◽  
Reiterated Homogenization

Heterogeneous media with multiple spatial scales are finding increased importance in engineering. An example might be a large scale, otherwise homogeneous medium filled with dispersed small-scale particles that form aggregate structures at an intermediate scale. The objective in this paper is to formulate the strong-form Fourier heat conduction equation for such media using the method of reiterated homogenization. The phases are assumed to have a perfect thermal contact at the interface. The ratio of two successive length scales of the medium is a constant small parameter ε. The method is an up-scaling procedure that writes the temperature field as an asymptotic multiple-scale expansion in powers of the small parameter ε . The technique leads to two pairs of local and homogenized equations, linked by effective coefficients. In this manner the medium behavior at the smallest scales is seen to affect the macroscale behavior, which is the main interest in engineering. To facilitate the physical understanding of the formulation, an analytical solution is obtained for the heat conduction equation in a functionally graded material (FGM). The approach presented here may serve as a basis for future efforts to numerically compute effective properties of heterogeneous media with multiple spatial scales.

scholarly journals Three-Dimensional MHD Simulations of a Subcluster Plasma Moving in Turbulent ICM

2006 ◽  
Vol 2 (S235) ◽  
pp. 189-189
Author(s):  
N. Asai ◽  
N. Fukuda ◽  
R. Matsumoto
Keyword(s):  
Heat Conduction ◽  
Magnetic Fields ◽  
Three Dimensional ◽  
Cold Fronts ◽  
Mhd Simulations ◽  
Anisotropic Heat Conduction ◽  
Magnetohydrodynamic Simulations

AbstractWe carried out 3D magnetohydrodynamic simulations of a subcluster moving in turbulent ICM by including anisotropic heat conduction. Since magnetic fields stretched along the subcluster surface suppress the heat conduction across the front, cold fronts are formed and sustained.

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