Flow and Heat Transfer of a Rotary Regenerative Thermal Oxidizer

Abstract

Thermal storage combustion technology is one of the most efficient methods for treating volatile organic compounds (VOCs), with the rotary regenerative thermal oxidizer (R-RTO) representing the latest generation. However, research on R-RTOs remains scarce and rarely considers the impact of rotation on the flow dynamics and heat transfer. This study employed simulations using the standard k-ε model with enhanced wall function, porous media model, species transport model, Finite-Rate/Eddy-Dissipation combustion model, and the Sliding Mesh method. After validating the simulation accuracy, the velocity and temperature distributions and heat transfer patterns within the channels of the regenerator were investigated. The following conclusions were drawn: The gas flow was uniform within the regenerative chamber but became nonuniform in the lower section of the chamber and within the oxidation chamber owing to the structural and flow directions. This nonuniformity also affected the uniformity of the temperature distribution. A small portion of the gas within the combustion chamber exhibited a short residence time. During rotary valve rotation, inlet gas flow short-circuiting occurred, causing severe fluctuations in the inlet/outlet pressure difference and flow rate, and reducing the VOC removal efficiency. An analysis of the thermal storage media channels revealed that the channel length and inlet air velocity significantly affected the heat transfer coefficient. However, the impacts of these two parameters (length and velocity) and the switching time on thermal efficiency were minor. Furthermore, the switching time had little impact on the heat transfer coefficient.