Fluid Flow and Mixing in Bioprocesses
Dr Martina Micheletti
Three-hour examination (80%)
Coursework/ lab practical (20%)
To provide students with an introduction to the basic transport phenomena required to analyse and design processes handling labile biological materials. Focus is on the development of a physical understanding of the underlying momentum transport phenomena and upon the ability to apply transport analysis to practical bioprocess-oriented problems. The physical interpretation of the problem will be emphasised via the understanding of the problem’s mathematical solution.
Following completion of the course, students will have an understanding of:
- how to mathematically analyse and interpret given experimental data on a simple flow-related problem and provide a physical explanation of the results obtained.
- how to design a generic flow system by verification of the assumptions made and quantify the pump requirements.
- how to analyse and design a complete chromatography system based on fluid flow.
- calculating the power input required for agitation in a stirred-tank fermenter under a range of operating conditions.
- defining conditions for the successful scale-up or scale-down of a fermentation process.
Lectures and case studies: 30h
- Introduction and rheology: Definition of transport processes. Basic and derived units and nomenclature. Dimensionless numbers. Physics and maths revision. General aspects of rheology. Newton’s Law. Non-Newtonian fluids and rheology of fermentation broths. Viscosity measurement. Case study: cup and bob and viscometer.
- Fluid flow in pipes: Predicting flow characteristics in pipe systems. Laminar flow and Hagen-Poiseuille equation. Calculating heads in a pipework system. Bernoulli equation. Case study: Bernoulli design problem. Pumping of Liquids (pumps classification, NPSH, cavitation, characteristic curve). Fluid flow and pressure measurement.
- Fluid flow in packed columns: Flow through porous media. Darcy’s Law and Carman-Kozeny equation. Determining column porosity. Estimating pressure drops in packed beds.Effect of particle shape. Concept of wall support and effects of compressible media. Concept of critical velocity. Case study: Pumping and flow in chromatography columns.
- Bioreactor mixing and scale-up/down: Mixing equipment, flow pattern and quantification of mixing phenomena in stirred tanks (power curve). Elements of fluid kinematics and turbulent flow scales. Case Studies: Design of batch sterilisation vessel, small aerated pilot fermenter, scale-up/down of fermenters.