Heat-Transfer for Fins with Two-Port Theory

1996 ◽  
Vol 24 (1) ◽  
pp. 61-72 ◽  
Author(s):  
C. Lombard
Keyword(s):  
Heat Transfer ◽  
Heat Conduction Equation ◽  
Conduction Equation ◽  
Flow Structures ◽  
One Dimensional ◽  
Various Boundary Conditions ◽  
The Matrix ◽  
The Subject ◽  
Complicated Geometry ◽  
The One

Fin heat transfer is an essential part of the education of mechanical engineers. It represents the simplest application of the heat conduction equation: the one-dimensional, steady, case. The usual presentation of the subject involves solving the conduction equation for various boundary conditions. In this paper, two-port techniques are applied to fin heat transfer. This concept is more suitable for the training of engineers because it emphasizes the importance of the boundaries rather than the internal conduction. Besides this important conceptual aid, the matrix is a powerful aid in computations; making it much easier to solve arrangements with complicated geometry. In fact, the two-port representation makes it possible to use graph theory for the automatic solution of complicated heat-flow structures.

scholarly journals Transition from Diffusion to Wave Propagation in Fractional Jeffreys-Type Heat Conduction Equation

2020 ◽  
Vol 4 (3) ◽  
pp. 32
Author(s):  
Emilia Bazhlekova ◽  
Ivan Bazhlekov
Keyword(s):  
Heat Conduction ◽  
Fundamental Solution ◽  
Heat Conduction Equation ◽  
Constitutive Law ◽  
Conduction Equation ◽  
Diffusion Regime ◽  
One Dimensional ◽  
Different Types ◽  
Propagation Regime ◽  
The One

The heat conduction equation with a fractional Jeffreys-type constitutive law is studied. Depending on the value of a characteristic parameter, two fundamentally different types of behavior are established: diffusion regime and propagation regime. In the first case, the considered equation is a generalized diffusion equation, while in the second it is a generalized wave equation. The corresponding memory kernels are expressed in both cases in terms of Mittag–Leffler functions. Explicit representations for the one-dimensional fundamental solution and the mean squared displacement are provided and analyzed analytically and numerically. The one-dimensional fundamental solution is shown to be a spatial probability density function evolving in time, which is unimodal in the diffusion regime and bimodal in the propagation regime. The multi-dimensional fundamental solutions are probability densities only in the diffusion case, while in the propagation case they can have negative values. In addition, two different types of subordination principles are formulated for the two regimes. The Bernstein functions technique is extensively employed in the theoretical proofs.

Research on the Issue of LED’s Cooling Based on Heat Conduction Equations

2012 ◽  
Vol 507 ◽  
pp. 137-141
Author(s):  
Zhi Qin Huang ◽  
Pei Ying Quan ◽  
Yong Qing Pan
Keyword(s):  
Heat Conduction ◽  
Steady State ◽  
Heat Conduction Equation ◽  
Rapid Development ◽  
Three Dimensional ◽  
Conduction Equation ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
One Dimensional ◽  
The One

With the rapid development of power type LED, the issue of the cooling of LED has been prominent. How to make the heat generated by LED chip go out quickly in order to cool the LED chip has become an urgent problem. The form of heat goes through the substrate has been widely used and has become the best way to solve the heat problem. There are three types of LED substrate. They are metal substrate, ceramic substrate and composite substrate. At first, In this paper I analyze the theoretical of three-dimensional non-steady state and steady state heat conduction equation, then the three-dimensional model is simplified as one-dimensional model and I get the results of heat conduction equation under the one-dimensional stationary and non-steady state.

Sign in / Sign up

Export Citation Format

Share Document