Two-dimensional numerical model for predicting fouling shape growth based on immersed boundary method and lattice Boltzmann method

Abstract

Fouling and ash deposition are important problems for the heat exchangers. The numerical models are efficient ways to understand the fouling processes and guide the design of heat exchangers. Because the shape of the fouling layer can influence the flow and heat transfer, modeling the shape change of the fouling layer is essential for the numerical models. In this work, a new numerical model based on the immersed boundary method is proposed for 2D fouling processes. The flow is modeled by a multiblock lattice Boltzmann method with a fixed Eulerian mesh, and the fouling layer is represented by an immersed boundary with Lagrangian points. The shape change of the fouling layer can be carried out by deforming the immersed boundary, while keeping the mesh of flow simulation unchanged. The particle motion, deposition models and a time ratio for fouling time scale are also included in the model. The particle depositions on a single row of tube and tube bundles with different tube shapes are simulated by the proposed model as examples. The influences of particle size and flow velocity on the particle deposition on windward and leeward sides of a circular tube are analyzed. As for the tube bundles, the elliptical tube can reduce the fouling rate. The evolution of the shape of the fouling layer can be obtained by the proposed model.