Dynamic CFD modeling and evaluation of ash deposition behaviors during Zhundong coal combustion

A comprehensive CFD model is established to study the dynamic deposition behavior of ash particles during Zhundong coal combustion. The deposition behavior of ash particles is described by the normal collision adhesion and removal model based on the elastic-plastic deformation theory, the tangential critical collision model, and the rolling removal model. The morphology evolution processes of the deposited layer are predicted by the dynamic mesh method. An unequal-sized heating surface based on the characteristics of the elliptical tube is proposed. The effects of the relative transverse tube pitch ST/D and the internal pitch Si of each group tube on the deposition and heat transfer performance are investigated. The results show that when Si = 45 mm and ST/D = 3.33–3.58, the anti-deposition and thermal-hydraulic performance of the novel heating surface are better than those of the typical heating surface. The novel heating surface has practical application prospects and feasibility and it is helpful for the efficient utilization of waste heat from dust-laden flue gases.