Convective Heat Transfer Coefficients of Multifaceted Longitudinal and Transversal Bricks of Lattice Setting in Tunnel Kilns

This paper reports the local multifaceted and area-averaged convective heat transfer coefficients (CHTCs) of longitudinal and transverse bricks arranged in lattice brick setting in tunnel kilns, using a three-dimensional (3D) computational fluid dynamics (CFD) model. A mesh sensitivity analysis was performed and the model was validated against reported experimental data in tunnel kilns. Three turbulence models were tested: the standard k–ε, re-normalization group (RNG) k–ε, and k–ω. The k–ω model provided the closest results to the experimental data. The CHTCs from the front, back, left, and right faces of the longitudinal and transverse bricks were calculated under various conditions. Area-averaged CHTCs for bricks were determined from the multifaceted CHTCs. Effects of rows, layers, and walls on faces and area-averaged CHTCs were investigated. A sensitivity analysis was performed to explore the effect of flow channels on the CHTCs. The numerical results showed that the CHTCs are enhanced by 17% for the longitudinal bricks and 27% for the transverse bricks when a uniform flow is reached in the tunnel kilns. Also, similar area-averaged CHTCs for the longitudinal and transverse bricks were obtained as a result of the uniform flow. Therefore, the specific energy consumption, quality, and quantity of brick production could be enhanced.