- Title
- Observations and modelling of flow parameters: reflected insights into the flow mechanisms of horizontal granular dense phase pneumatic conveying
- Creator
- Orozovic, Ognjen
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2017
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Compared to high velocity dilute phase, low velocity dense phase conveying offers additional benefits of reduced wear and higher material throughputs; while maintaining all the benefits pneumatic conveying has to offer including enclosed conveying, flexible routing and low maintenance. The complexity of the flow; however, is the major limiting factor when it comes to widespread implementation of dense phase systems. The still unknown mechanisms responsible for the flow have resulted in universally unreliable design procedures resulting in reluctance from industry in employing this profitable flow type. The work presented in this thesis aims to shed light on the unknown mechanisms, specifically within horizontal slug flow, through an experimental and theoretical analysis of the key parameters of the flow. Experimentally the relationship between the key slug properties was investigated at two pipe locations allowing the evolution of the parameters to be tracked and correlated for individual slugs. The ‘Ergun porosity’ approach was expanded as well as a physical and theoretical review of the method resulting in a modified form of the Ergun equation for slug flow. Further investigations on the slug porosity resulted in a simple model developed along with a tuning procedure for the model constant to account for the effects of air supply. The gas dynamics were considered as a function of time and an unsteady model was developed for the interstitial gas velocity. Preliminary examinations suggest that dynamic changes in slug porosity and pressure only impact the magnitude of the interstitial velocity and not the trend. Future work should involve experimental porosity data and more robust numerical approaches to further examine these findings. Lastly, an investigation on the layer fraction resulted in the development of a new predictive model that addresses the drawbacks of the readily applied model of Konrad. Three sets of experimental data were utilised to validate and compare to the model of Konrad while also investigating the layer fraction as a function of air supply, pipe location and bulk material. Overall three models; for the porosity, interstitial gas velocity and the layer fraction were developed as well as a modification to an existing Ergun inspired approach. When combined, the developed models enable prediction of the porosity, interstitial gas velocity and slug velocity profiles in time, as well as the layer fraction deposited at the rear of the slug; all with only a pressure drop/gradient input.
- Subject
- pneumatic conveying; slug flow; dense phase
- Identifier
- http://hdl.handle.net/1959.13/1350046
- Identifier
- uon:30479
- Rights
- Copyright 2017 Ognjen Orozovic
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 11 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 201 KB | Adobe Acrobat PDF | View Details Download |