Simulation of combined conductive, convective and radiative heat transfer in moving irregular porous fins by spectral element method

Abstract

A spectral element method (SEM) is developed to solve coupled conductive, convective and radiative heat transfer in moving porous fins of trapezoidal, convex parabolic and concave parabolic profiles. In these irregular porous fins, non-uniform heat generation, heat transfer coefficient and surface emissivity vary with temperature. In the SEM model, the solution domain is decomposed into non-overlapping elements by mesh tools of finite element method, and Chebyshev polynomials are used to establish basis functions on each element. A case of nonlinear heat transfer in the irregular porous fin is taken as an example to verify the performance of SEM. Compared with available data in the literature, SEM can provide a good accuracy. The h and p convergence characteristics of SEM are also studied. The p convergence rate is faster than the h convergence rate and approximately follows an exponential law. In addition, a volume adjusted fin efficiency is developed to evaluate the thermal performance of irregular porous fin. The effects of porous materials, irregular profiles and other thermo-physical parameters, such as Peclet number, surface emissivity coefficient, power index of heat transfer coefficient, convective-conductive parameter, radiative-conductive parameter, non-dimensional heat generation at ambient temperature, heat generation parameters, porosity and non-dimensional ambient temperature on non-dimensional temperature and fin efficiency are also studied.