FRACTAL STUDY ON THE HEAT TRANSFER CHARACTERISTICS IN THE ROUGH MICROCHANNELS

In this paper, considering the structure of the shape factor and the rough element, combined with fractal geometry theory, the shape factor, the relative increase in the heat transfer between the rough surface and the smooth surface in a fractal unit, and the fractal analytical expression of the dimensionless equivalent thermal conductivity caused by convection thermal conductivity are derived. In addition, the relationship between the microstructure parameters of the rough surface and the shape factor, the relative increase in convective heat transfer and the dimensionless equivalent thermal conductivity are studied. It is found that the relative increment of the convective heat transfer and the shape factor are proportional to the ratio of the minimum height and maximum height of the rough element and the fractal dimension, and the dimensionless equivalent thermal conductivity model deduced in this paper is compared with the existing experimental data to verify the validity of the model.