Revealing flow structures in horizontal pipe and biomass combustor using computational fluid dynamics simulation

Computational fluid dynamics (CFD) is a powerful tool to provide information on detailed turbulent flow in unit processes. For that reason, this study intends to reveal the flow structures in the horizontal pipe and biomass combustor. The simulation was aided by ANSYS Fluent employing standard k$$ k $$-epsilon$$ \upvarepsilon $$ model. The results show that a greater Reynolds number generates more turbulence. The pressure drop inside the pipe is also found steeper for small pipe diameters following Fanning's correlation. The fully developed flow for the laminar regime is found in locations where the ratio of entrance length to pipe diameter complies with Hagen-Poiseuille's rule. The sucking phenomenon in jet flow is also similar to the working principle of ejector. For the biomass combustor, the average combustion temperature is 356-696 degrees C, and the maximum flame temperature is 1587-1697 degrees C. Subsequently, air initially flows through the burner area and then moves to the outlet when enters the combustor chamber. Not so for particle flow, the particle experiences sedimentation in the burner area and then falls as it enters the combustor chamber. This study also convinces that secondary air supply can produce more circulating effects in the combustor.