Heat transfer enhancement through extended surfaces is crucial in modern engineering applications such as microelectromechanical systems and electronic components. Conduction heat transfer is the only way to achieve this objective when the mixing augmentation is not possible. This paper investigates the effects of non-Fourier thermal conduction in convective straight fins with arbitrary constant cross section under periodic boundary conditions by introducing the exact analytical solution for the dual-phase-lag heat conduction. The corresponding analytical approach is developed through the Laplace transform method and inversion theorem. To help advance the understanding of fin thermophysical behavior, a generalized model of conduction heat transfer equation is used for studying all of the interpretations to Fourier-based model, namely, parabolic thermal diffusion, hyperbolic thermal wave, and dual-phase-lag models. Heat flux and temperature gradient relaxation times are the characteristics of the dual-phase-lag model, and the simulation results are strictly a function of these two parameters. Therefore, fin temperature distributions are presented for flux precedence and gradient precedence heat flow regimes. Calculations are performed to investigate the influence of temperature gradient relaxation time on the hyperbolic heat conduction characteristics of non-Fourier fins.
Nomenclature
A= fin cross section, m 2 C = thermal wave speed, m · s −1 C 1 -C 4 = constant coefficients c = specific heat of fin, J · kg −1 · K −1 dA s = peripheral surface of fin element, m 2 H = dimensionless convective heat transfer coefficient h = convective heat transfer coefficient, W · m −2 · K −1 k = fin thermal conductivity, W · m −1 · K −1 L = fin length, m n = nonnegative integer number p = perimeter of fin element, m q = heat transfer rate, W · m −2 r = nonnegative integer number s = Laplace domain parameter T = fin temperature,°C T b = fin base temperature,°C T b;m = average of fin base temperature,°C T 0 = initial temperature of fin,°C T ∞ = ambient temperature,°C t = time, s x = coordinate variable, m α = fin thermal diffusivity, m 2 · s −1 Γ = dimensionless temperature gradient relaxation time η = dimensionless coordinate parameter θ = dimensionless fin temperature θ ∞ = dimensionless ambient temperature Λ = dimensionless heat flux relaxation time λ n = 2n 1π∕2, eigenvalues ξ = dimensionless time ρ = fin material density, kg · m −3 τ q = heat flux relaxation time, s τ T = temperature gradient relaxation time, s φ = amplitude of periodic base temperature Ω = dimensionless base temperature frequency ω = base temperature frequency, s −1