Reader in Chemical Engineering
|Qualifications/honours||BA, MEng, Chemical Engineering, University of Cambridge, 1989
PhD, Chemical Engineering, University of British Columbia, 1994
Visiting Academic, Technical University of Braunschweig, 2008-
FIChemE, CEng, CSci
|Address|| Department of Chemical Engineering and Biotechnology
University of Cambridge
New Museums Site
CB2 3RA, UK
|Telephone||+44 (0)1223 (3)34791|
|Themes||Modelling, Measurement, Microstructure Engineering, Processes|
Our interests lie in the study of soft solids and surfaces with particular applications in the food and chemicals industries.
We are interested in studying the formation and processing behaviour of structured semi-solid materials. The main area of interest is in solid-liquid pastes or doughs, composed of particulate solids surrounded by continuous liquid phase(s), but we also work on bubbly liquids. These are common in the food, detergent, agro-chemicals, pharmaceutical and catalysis industries, and are frequently formed into particular shapes by extrusion. The underlying physics is complex and we use aspects of plasticity theory, fluid rheology and soil mechanics to describe these systems. This work is part of the Paste, Powder and Polymer Processing Group activity, in association with Sarah Rough, Bart Hallmark and David Scott. Our activities are focused around
- Fundamental studies : investigations of phenomena, such as wall slip, iquid phase migration, agglomeration or fracture;
- Process modelling : developing models of paste forming processes, such as rolling/calendering or screen extrusion;
- Product design : relating function, processing and formulation to deliver particular product properties.
- Rheology: using modern devices and theory to describe how soft solids deform and flow, and respond to formulation and processing
Ongoing projects include the extrusion and drying of tungsten carbide pastes (with Sarah Rough) to understand monitor micro-structural development and defect formation, the rheology of bubbly liquids (aka cake batters, with Geoff Moggridge), and screen extrusion of pharmaceutical materials (with Sarah Rough). We have also been working on novel processing routes to generate structured materials, particularly involving thermal processing.
Fouling and Cleaning Mechanisms
A whole class of unwanted micro-structured materials can be found as fouling deposits on heat transfer surfaces, in distribution systems and other equipment. Fouling is a common (and expensive) operating problem in many processes, particularly the food industry, where the deposits formed can act as harbours for other problem species (e.g. bacteria ). This work relates to long-standing efforts in heat transfer and approaches the problem at three related scales:
- Fundamental studies of deposit formation and removal, with particular focus on deposit structure and modelling;
- Design, control and operation of individual heat exchanger units, both in production and during cleaning (e.g. for aspectic processing);
- Design and operation of large heat transfer networks, such as are used in energy intensive processes.
Recent work has focused on retrofit and design for crude oil fouling (in refinery pre-heat trains) and novel, non-disruptive, in-situ methods for studying the growth or removal of soft layers in conjunction with Bill Paterson and John Chew (now at Bath). These soft layers include biofilms and protein matrices undergoing swelling for controlled release.
We have recently brought the strands of soft-solids and fouling together in a unified framework for managing fouling and cleaning cycles, where deposit ageing (converting deposit from a soft solid to a hard material) is a key factor.
Research keywordspaste, powder, food, fouling, cleaning
Wilson, D.I. and Rough (2012) ‘Paste engineering: Multi-phase materials and multi-phase flows’, Canadian J. Chemical Engineering, 90 (2), 277-289.
Salley, B., Gordon, P.W., McCormick, A.J., Fisher, A.C. and Wilson, D.I (2012) ‘Characterising the structure of photosynthetic biofilms using fluid dynamic gauging’, Biofouling., 28 (2), 159-173 .
Ferstl, H., Barbist, R., Rough, S.L. and Wilson, D.I. (2012) 'Influence of visco-elastic binder properties on ram extrusion of a hardmetal paste', J. Materials Sci, 47(19), 6835-6848.
Wang, T, Davidson, J.F. and Wilson, D.I. (2013) 'Effect of surfactant on flow patterns and draining films created by a horizontal liquid jet impinging on a vertical surface', Chem Eng. Sci., 88, 79-94.
Torres M.D., Gadala-Maria F. and Wilson, D. I (2013) 'Comparison of the rheology of bubbly liquids prepared by whisking air in a viscous (honey) and a shear-thinning liquid (guar gum solutions)', J. Food Eng., 118(2), 213–228
For a full list of publications, see http://www.ceb.cam.ac.uk/publications/DIWilson.html