Chapter 1
Introduction
This chapter introduces various flow regimes and properties of gas-solid fluidised
beds, and the state-of-the-art approaches to model these systems. The promising techniques to enhance fluidisation and intensify gas-solid fluidised systems are reviewed.
Moreover, it reviews the works investigating granular patterns in both mechanically vibrated and periodically pulsed systems. In the end, it summarises the main
objectives and presents an outline of this thesis.
The chapter is adapted from the published articles :
Wu, K., Francia, V., & Coppens, M.-O. (2020). Dynamic viscoplastic granular flows:
A persistent challenge in gas-solid fluidization. Powder Technology, 365, 172–185.
Francia, V., Wu, K., & Coppens, M.-O. (2021). Dynamically structured fluidization: Oscillating the gas flow and other opportunities to intensify gas-solid fluidized
bed operation. Chemical Engineering and Processing-Process Intensification,
159, 108143.
1.1 Granular Flow and Fluidisation
Granules are a common type of matter composed of discrete particles that act as a
collective assembly. Examples can be found in a wide range of natural substances,
such as sand, coal, grain as well as artificial substances that include medicine pills,
chemical catalysts and sawdust. From common practice, it is well-known that granular matter can manifest the properties reminiscent of gases and liquids, forming
granular flows when subjected to different environments. Nevertheless, the rheology
and physics of granular flows are far less well understood than that of fluids. Because
of the inelastic interparticle collisions and the emergence of mesoscopic structures,
granules exhibit more complex dynamic behaviour than ordinary fluids. The application of a shear force onto a collection of rapid flowing particles induces the momentum
transport and a proportional shear rate, whereas stress can be transmitted through
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
K. Wu, Dynamically Structured Flow in Pulsed Fluidised Beds, Springer Theses,
https://doi.org/10.1007/978-3-030-68752-6_1
1
Introduction
This chapter introduces various flow regimes and properties of gas-solid fluidised
beds, and the state-of-the-art approaches to model these systems. The promising techniques to enhance fluidisation and intensify gas-solid fluidised systems are reviewed.
Moreover, it reviews the works investigating granular patterns in both mechanically vibrated and periodically pulsed systems. In the end, it summarises the main
objectives and presents an outline of this thesis.
The chapter is adapted from the published articles :
Wu, K., Francia, V., & Coppens, M.-O. (2020). Dynamic viscoplastic granular flows:
A persistent challenge in gas-solid fluidization. Powder Technology, 365, 172–185.
Francia, V., Wu, K., & Coppens, M.-O. (2021). Dynamically structured fluidization: Oscillating the gas flow and other opportunities to intensify gas-solid fluidized
bed operation. Chemical Engineering and Processing-Process Intensification,
159, 108143.
1.1 Granular Flow and Fluidisation
Granules are a common type of matter composed of discrete particles that act as a
collective assembly. Examples can be found in a wide range of natural substances,
such as sand, coal, grain as well as artificial substances that include medicine pills,
chemical catalysts and sawdust. From common practice, it is well-known that granular matter can manifest the properties reminiscent of gases and liquids, forming
granular flows when subjected to different environments. Nevertheless, the rheology
and physics of granular flows are far less well understood than that of fluids. Because
of the inelastic interparticle collisions and the emergence of mesoscopic structures,
granules exhibit more complex dynamic behaviour than ordinary fluids. The application of a shear force onto a collection of rapid flowing particles induces the momentum
transport and a proportional shear rate, whereas stress can be transmitted through
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
K. Wu, Dynamically Structured Flow in Pulsed Fluidised Beds, Springer Theses,
https://doi.org/10.1007/978-3-030-68752-6_1
1