Development of a filtered reaction rate model for reactive gas-solid flows based on fine-grid simulations

The filtered reaction rate for the coarse-grid simulations of reactive gas-solid flows can be obtained via a correction to its microscopic reaction rate. The correction term is defined as the mesoscale effectiveness factor eta(Delta), which is the ratio of the reaction rate obtained from the fine-grid simulations to that obtained from the coarse-grid simulations. The considered reaction is an isothermal, solid-catalyzed surface reaction with a power law reaction rate model. The simulation results show that the mean eta(Delta) is almost invariant with the reaction orders at the same Damkohler number. A closure correlation for the mean eta(Delta) is formulated. However, the standard deviation of eta(Delta) is found to be quite large. A presumed probability density function model is proposed to capture the fluctuating properties of eta(Delta). The predictability of the closure correlations are evaluated via performing the filtered two fluid model simulations in circulating fluidized beds of ozone decomposition.

Automated summary

The study obtains the filtered reaction rate for coarse-grid simulations of reactive gas-solid flows through correcting its microscopic reaction rate, finding that the mean eta(Delta) is almost independent of reaction orders at the same Damkohler number. A closure correlation for the mean eta(Delta) is proposed, while a large standard deviation is observed. A presumed probability density function model is suggested to capture the fluctuating properties of eta(Delta), and the predictability of the closure correlations is evaluated through simulations in circulating fluidized beds of ozone decomposition.