Effect of fluid channels on flow uniformity in complex geometry similar to lattice brick setting in tunnel kilns

Abstract

This paper reports the results of air flow in tunnel kilns using a 3D computational fluid dynamics (CFD) model. A mesh sensitivity analysis was performed, and the model was validated against experimental results. Three turbulence models that are available in general purpose commercial CFD tools, namely k–ω, standard k–ε, and RNG k–ε were tested, and the k–ω model provided results that were the closest to the experimental data. The numerical results demonstrated fluid flow malfunctions in tunnel kilns, using the size of fluid channels as for the experiment, including an intriguing phenomenon of long flow separation zone behind the brick setting. Homogenous flow was achieved by optimizing the dimensions of the side wall channels, the column channels, the ceiling channel, and the extension channels. The uniform flow, in tunnel kilns, is accomplished when the dimension of the column, wall, ceiling and extension channels was 0.5, 0.25, 0.2 and 0.36 of the column width of the brick setting. Although the pressure drop in the flow uniformity case is larger than that in the base case, the advantages of short baking time and enhanced quantity and quality of produced bricks far exceed the increase in pumping power.