A CFD study of particle deposition in three-dimensional heat exchange channel based on an improved deposition model

Abstract

Airborne particle deposition in the heat exchange channel will cause serious heat transfer efficiency reduction. Better understanding of deposition characteristics is of significance for energy and thermal engineering application. In this study, particle deposition in three-dimensional heat exchange channel with surface ribs was conducted by Reynolds stress model and discrete phase model. An improved deposition model based on turbulent fluctuation correction and particle rebound was developed by user-defined function (UDF). After grid independence study and numerical verification, the flow structures, the secondary flow in the channel corners, particle deposition patterns and deposition efficiency on each wall were investigated and analyzed. The influences of several important parameters, such as particle diameter, the ratio of rib spacing to rib height p/e, and air flow velocity on the turbulent flow and deposition characteristics were investigated. The results showed that turbulent flow structures induced by the ribs, the secondary flow, the interception of rib windward surface, particle rebound and gravitational settling are the main mechanisms for particle deposition in ribbed channel. The main deposition locations are the windward surface of ribs and the cavity walls in front of the ribs, due to the interception of the ribs, particle rebound and flow eddies in the cavities. Moreover, the deposition efficiency of each wall is significantly affected by the influencing parameters.