Identification and development of embedded computational fluid dynamic models for densely packed passive bypass pneumatic conveying systems

by Ying Wang

Institution: University of Newcastle
Degree: PhD
Year: 2013
Keywords: bypass pneumtic conveying; Computational Fluid Dynamic; pressure drop; dense phase
Record ID: 1041456
Full text PDF: http://hdl.handle.net/1959.13/1040458


Research Doctorate - Doctor of Philosophy (PhD) Bypass pneumatic conveying systems are a more reliable and efficient method for transporting fragile and erosive bulk solids which are not suitable to be transported by conventional dense phase pneumatic conveying systems. This thesis is mainly focused on developing novel particle resistance models to conduct Computational Fluid Dynamic (CFD) numerical simulations of a passive bypass pneumatic conveying system with three types of material: flyash, alumina and sand. CFD based simulations still pose significant challenges to ensure that the physical nature of gas-solid flow can be effectively presented by numerical simulation for bypass pneumatic conveying systems. In this thesis, an experimental program was planned which defined the particle properties and conveying experiments were conducted within a bypass pneumatic conveying pipeline. Based on the parameters utilised in the experiment, the CFD based numerical investigation of pressure drop was initially conducted by applying kinetic theory and conventional frictional-kinetic model. By comparing simulation results with experimental results and analysing images captured by high speed camera for selected cases, resistance models which better represented sustained particle contact for dense flows were investigated. Based on the review of previous research, this thesis proposed a modified frictional-kinetic model which better reflected the physical nature of gas-solid flow behaviour in bypass pneumatic conveying system for alumina and sand. Unfortunately, no improvement was found for the flyash flow prediction. The sensitivity analysis of empirical constants in the modified frictional-kinetic model was conducted and the most appropriate values were determined. The pressure drop was then predicted using the modified frictional-kinetic model, and the prediction results were compared with results from kinetic theory and conventional frictional-kinetic model. Combined with mode of flow charts, some guidance was provided which related the frictional resistance model type to the particle flow type in a bypass system.