Numerical investigation on the effects of non-gaussian random and regular textured rough surface on critical heat flux

Abstract

Modified surfaces with rough structure have been widely employed to enhance the critical heat flux (CHF) in the heat transfer engineering. Since any structure diagram in its intersecting surface can be treated as spectrum/signal in 2D dimensions, and any spectrum in time domain and in frequency domain can be transformed into sine transforms by the Fourier. Thus, in this article, the effects of the non-gaussian random rough surface and the ordered sine function structured surface were investigated on the CHF enhancement using the fast Fourier transform (FFT) method and the hybrid thermal lattice Boltzmann method (LBM). It finds out that for the non-gaussian random rough surface, CHF is enhanced with decreasing the skewness of the surface. The enhancement seems limited with further reduced the skewness. Besides, the CHF enhancement will be improved by increasing surface wettability. For regular textured surfaces, increasing either the amplitude or the periodicity of the surface structures initially increases the CHF and then the enhancement is impeded with further increase. It concludes that there exists an optimal design of the surface morphology with either non-gaussian random structure or the ordered sine function structure for the CHF enhancement in pool boiling.