Environmental pollutants pose great risks and adverse effects to humans and therefore arouse global environmental concern. Bacterial sensors capable of assessing the bioavailability and toxicity of pollutants show great advantages in environmental sensing. This project aims at developing a bioluminescent bacteria-based microfluidic sensor for online monitoring of environmental contaminants and toxicity. Microfluidic devices immobilised with Acinetobacter sp. ADP1_lux cells as a model strain have been developed for quantitative bioassays. Three microfluidic devices were developed and tested in order to trap and culture a monolayer of bacterial cells. The terrace device is capable of trapping a monolayer of cells in a chamber for tracking single-cell growth and response. This device utilises a barrier channel lower than the cell diameter. Two flow channels can be used to load bacterial cells, deliver fresh media and inducers and wash away overgrown cells. The device was used to measure the bioluminescence induction of ADP1_lux cells and its capability to track individual cell growth was demonstrated with E.coli cells. Since bioluminescence signals from a monolayer of ADP1_lux cells were too weak to be detected after 2 h induction by 200 µM salicylate, a microwell device was developed to concentrate cells in individual microwells for population-based analysis. Cell loading procedures, dimensions of wells, carbon sources and on-chip cultures that affect bioluminescence light intensities were investigated. This device succeeded in detecting 200 µM salicylate within 1 h. However, long-term cell culture revealed that ADP1_lux cells tend to form biofilms. Cell populations in individual wells varied greatly, making quantification impossible. Therefore, this device is only suitable for rapid detection of high concentrations of contaminants if biofilm forming bacteria cells are used as biosensors. In contrast, in the case of non-adherent cells such as E.coli, a uniform population distribution in each well was achieved after 2-day culture, suggesting this method is applicable to perform long term, quantitative bioassays using suitable, non-adherent cells. To be able to detect low concentrations of contaminants and overcome potential biofilm formation, a new population array device was developed as a proof of concept to control and isolate cell populations. It consists of a network of microfluidic channels and an array of microchambers. The device was characterised with fluorescent dyes and its capability to perform quantitative bioluminescence assays was evaluated by detecting a range of concentrations of salicylate solutions (from 10 µM to 50 µM salicylate) using ADP1_lux cells. A linear correlation between bioluminescence intensities and salicylate concentrations was successfully established within 90 min induction. It is worth noting that the population array device is the first demonstration of bioluminescence detection at the length scale of microns. Therefore, it has potential to perform multiplex detection within a small footprint where different types of whole cell biosensors can be employed simultaneously. To this end, a logarithmic serial dilution device was also developed to enable quantitative, multiplex bioassays to be conducted in the same device. This integrated dilution and population device provides a powerful tool for rapid quantification of multiple contaminants simultaneously in a sample.

Recently, the ability to characterise a formulated product during its manufacture has become very desirable due to the importance of maintaining control over its structure and electro-mechanical properties. The fields of process tomography and spectroscopy are set to play an important role in new technologies yielding in-situ characterisation of a product during chemical processing. This study has investigated such techniques with the aim to apply these tools to a relevant Johnson Matthey manufacturing line. Water, being a high di-electric, can be detected at very low concentrations using Electrical Capacitance Tomography (ECT). This relationship has been exploited to monitor drying and phase boundaries of a packed bed in both two and three dimensions. A comparison with MRI has yielded similar results for the drying profile of a similar packed bed demonstrating technique robustness. Electrical Resistance Tomography (ERT) has been used to discriminate gas and solid phases within a three phase system. The measured conductivity of the multi-phase system at 300 Hz is different than at 9600 Hz and allows for the identification of conductive particles from air bubbles. The application of wideband impedance spectroscopy to ceramic suspensions has shown that electrical and structural properties are inter-related. This work has driven forward the research and improved the range of applications of electrical process analytics.

Ceramic cores are utilised during turbine blade manufacture to develop cooling channels within the finished component. These cores, fabricated by ceramic injection moulding, must possess an array of properties to ensure minimal defect development during casting. The carrier system, powder interactions and component forming, critical in ceramic injection moulding, have been investigated within this project. The binder systems were developed using paraffin wax, ethylene vinyl acetate and polyethylene with stearic acid incorporated as a surfactant. Binder system development illustrated that a wide range of melting, rheological and mechanical properties could be produced by binder blending. The moulding success was improved by feedstock optimisation, with optimal surfactant levels determined between five and ten ‘layers’ upon the powder surface. Optimisation maximised the achievable ceramic solids loading, measured and estimated by density and rheological methods. Binder systems illustrating a good resistance to fracture with adequate flow characteristics have been shown to successfully form complex cores to high yields. Success in component forming was limited by feedstock fluidity, final components were more prone to crack development when the binder system had reduced crack resistance and success of the wicking process was limited in some systems by formulation with proposed mechanisms explained.

The mixing of complex fluids in stirred reactors is widly used in many industries. Mechanically agitated vessels are widely used in these industries such as wastewater treatment, pharmaceuticals, nuclear and food processing. Complex fluids are frequently encountered in these industries. There is growing interest in developing and studying these fluids, especially for those of shear thickening (ST) behaviour, due to the importance of their industrial applications such as flexible body armor and force damping applications which can protect a person from danger or risk and ultimately saveone’s life. Little work has been done to understand how to mix complex fluids effectively, mainly because of their opaque nature. In this thesis, new ST fluids formulations were developed and these fluids were used as a model fluid for mixing studies. The flow field in an opaque ST fluid was determined experimentally using the positron emission particle tracking (PEPT). In addition, the performance of axial, radial and mixed flow impellers in mixing complex fluids have been also studied using different experimental techniques and the computational fluid dynamics (CFD) simulations. Moreover, for the first time, PEPT has been used to investigate the flow field of floating particles in a stirred vessel. PEPT was used to investigate the two-phase flow field inside a stirred vessel of polypropylene particles in different types of rheological fluids, at the just drawdown speed for a wide range of solid concentrations from 1.8 vol% up to 46 vol%. The outcomes of this thesis are beneficial to many chemical processes, such as e.g. formulation processes in the pharmaceutical industry, whereby an essential step in the product development involving powder mixing is the ability to drawdown the floating solids. In addition, the outcome of this thesis can also be beneficial in identifying the ideal configuration of stirred vessels used in chemical processes where mixing is the central feature, for example, in the food and rubber industries. Moreover, the newly developed complex fluids (shear thickening fluids) can be used in many industrial and commercial applications such as in the defence industry (as liquid body armor) and also as part of the protective devices designed to minimise head and neck injuries that occur in some sports accidents such as in car racing, football, ice hockey etc.

A formulation process for CaCO3 spheres (D50 of 5.1 μm) for use as a functional filler in decorative paints was optimised. This increased the yield of CaCO3 spheres 20-fold and made the process less hazardous, with organic oils, namely rapeseed oil, being used successfully as a replacement for toluene. The CaCO3 spheres contained a multitude of < 250 nm nanovoids, with some spheres containing a core void > 800 nm. These pores formed because the crystals nucleated at the interface of emulsion droplets, resulting in CaCO3 spheres (2.42 g cm-3; 2,420 kg m-3) composed of calcite and vaterite, with a density lower than either mineral (2.71 g cm-3 (2,710 kg m-3) and 2.65 g cm-3 (2,650 kg m-3), respectively). The characterisation and performance of CaCO3 spheres in paint formulations were compared against commercially available products, namely Microdoll H600 (5 μm dolomite). There was no opacity benefit, however a 4-fold scrub resistance benefit was observed. Different oils can be used in the emulsification step in CaCO3 spheres production whilst others cannot, most likely because of the ratio of mono- to poly-unsaturated fatty acids. A technique for improving scrub resistance of other mineral extenders was developed, with AkzoNobel continuing the research into this area.

This thesis considers the role fluids play in improving the efficiency and reducing the environmental impact of modern gas turbines. This includes gas turbines used in aviation, marine propulsion and power generation applications. There are two discrete means of lowering the environmental impact of gas turbines. Improving the thermal efficiency of the gas turbine is one possible route which works by reducing the required fuel consumption. Another route which is indirectly related to engine technology is the use of renewable fuels (biofuels) which have reduced lifecycle carbon dioxide emissions when compared to crude oil derived fuels. As such this thesis examines both the potential of renewable fuels for use in gas turbines and also the impact of increased efficiency on the fluids contained within a gas turbine.

The handling properties of dough were assessed by subjecting a wide variety of dough types to compression. The parameters varied included our variety, mixing time and addition of ingredients such as enzymes, to give doughs with a range of softness and stickiness behaviour. Approximately spherical dough samples were compressed at a constant speed, between lubricated and non-lubricated plates, to a set strain, with contact area assessed using image analysis. Various parameters from the test were compared to baker's assessments of softness and stickiness. A stickiness ratio based on the ratio of adhesive to cohesive components was investigated. Farinograph values were considered but found not to relate to dough behaviour. Compression energy per unit area gave strong correlations with baker's assessments, with softness giving the strongest correlations. Compression was found to give better results than pull-off. Level of water addition had the greatest influence on results. This compression method was assessed against a Quantitative Dough Handling Assessment (QDHA) developed in this work. The energy per unit area correlated well with the QDHA suggesting the potential for the compression method to be used to predict dough handleability. This supports the hypothesis that rheology is key to dough stickiness.

This work investigates the laminar mixing performance of viscoelastic fluids in laboratory-scale batch stirred tanks agitated by “butterfly” impellers and in-line Kenics KM static mixers. Constant-viscosity viscoelastic (Boger) fluids were formulated to investigate viscous and elastic effects separately; multiphase viscoelastic suspensions were formulated from 40-50 volume% glass spheres in glycerol. Particle Image Velocimetry in stirred tanks agitated by high impeller-to-tank diameter ratio butterfly impellers (D/T=0.98) showed that secondary flows in Boger fluid increased solid body rotation and reduced local shear rates (≤16 s-1) compared to equivalent viscosity Newtonian fluids, though the effect was non-monotonic. Mixing times obtained from Planar Laser Induced Fluorescence (PLIF) increased by ≤23%. Positron Emission Particle Tracking in multiphase suspensions showed increased axial mixing due to more dominant secondary flows. In static mixers, Boger fluid striation patterns at the mixer outlet obtained from PLIF showed time dependence and flow instability due to reduced local shear rates. Energy consumption in all geometries displayed an increase of ≤200% with viscoelastic fluids. Using a generalised Reynolds number Reg enabled viscoelastic power draw prediction, previously only possible through empirical relationships. Overall, viscoelasticity generally increases energy consumption whilst reducing blending performance though the link between elasticity and mixing quality is highly non-linear.

The power draw and emulsification performance of in-line rotor-stator mixers were investigated experimentally and theoretically, to predict droplet size as a function of process and formulation variables and to establish scale-up rules. The effect of process conditions, three mixer scales and thirteen rotor-stator geometry configurations on emulsification performance were investigated. Emulsions of a wide range of silicone oil viscosities of varying phase volumes, dispersed in aqueous surfactant and non-surfactant solutions were studied. For lab to factory scale in-line rotor-stator mixers, the most appropriate scaling parameter for mean drop size was tip speed at constant residence time for single and multiple passes. At a single scale, the stator open area was the rotor-stator geometry parameter which had the greatest effect on power draw and emulsification in turbulent flow. Mean drop size was a strong function of the rotor speed, dispersed phase viscosity, interfacial tension, and less dependent upon the mixer flow rate, continuous phase viscosity and dispersed phase volume fraction (for surfactant systems). Correlation of mean drop size with energy dissipation rate indicated that droplet break-up mainly depends on turbulent inertial stresses. Energy dissipation rate profiles were calculated theoretically using numerical simulations to calculate power draw and to solve population balance model equations. This is the first study in open literature where power consumption and drop size distributions in three scales of in-line rotor-stator mixer are reported.

A novel extrusion binder system was developed to enable the manufacture of tungsten carbide drill blanks greater than I 4 mm in sintered cross-sectional diameter at Sandvik Hard Materials Coventry. The binder system comprised primarily of methyl cellulose and water, which was capable of being removed from the extrudate with no adverse effects on extrudate quality or increases in drying and de-binding times. The tungsten carbide feedstock was prepared by z-blade mixing on laboratory, pilot and production plant scales. Extrudates were manufactured either as solid cylindrical rods or as rods formed with internal coolant channels following a helical rotation up to 20 mm sintered diameter. Extrusion tooling was modified to aid the forming process and maintain the desired tolerances of internal properties of the drill blanks. Such properties included coolant hole diameter, coolant hole relative concentricity and the distance between the coolant hole centres (pitch circle diameter). Controlled stress rheometry and oscillatory rheometry techniques were used in the selection of the methyl cellulose and water based binder for further analysis. Contro lled stress and oscillatory rheological techniques were a lso used to determine how modifications to the binder systems could be used to improve the extrus ion feedstock behaviour.