Effect of combined natural convection and non-gray gas radiation on entropy generation through a cylindrical annulus

Abstract

The present work is focused on the interaction between natural convection and thermal radiation in a participating medium through a cylindrical annulus. The Ray Tracing method through the quadrature T10 has been adopted in association with the Statistical Narrow Band correlated-k (SNBCK) model to solve the radiative part of the problem. Special attention is given to entropy generation and its dependency on the various governing parameters including the inner cylinder temperature, the outer cylinder radius, emissivities of the annulus walls, and the gas pressure. The results show that radiation remarkably affects the structure of the fluid flow and the temperature distribution, enhancing heat exchanges in the annulus. Moreover, it is found that the volumetric entropy generation due to radiative processes of medium should not be neglected and is comparable to the volumetric entropy generation due to heat conduction. It is also shown that increasing the emissivities of the cylinders intensifies entropy generation due to radiation through walls, but on the other hand doesn’t affect the volumetric entropy generation.