The object of the work was to attempt to propose an improvement in the process of vapour-liquid contacting with particular reference to commercial distillation. The literature was reviewed by considering both the overall performance data of the methods and devices used for contacting and the more fundamental studies of the mechanisms and effects taking place in them. It was concluded that the cross-flow Sieve tray with a high free area and many small holes would offer the best performance. This solution, however, is not commercially viable as the cost of producing a device to these specifications by conventional means would be excessive. To overcome this economic restraint and to retain the improved performance, a cheaper method of tray floor construction was proposed in which the material used was inherently porous. Many materials satisfy the requirements for use as a tray floor, for example, open cloths, meshes and gauzes and open cell foam and sintered materials. Sorting tests were, therefore, performed on a small scale, using an air-water system, to eliminate those materials which gave unsatisfactory hydraulic performance. A 68" x 14" column, also using an air-water system, was employed to test the feasibility and the hydraulic performance of the proposed tray floors on a large scale. The same apparatus was then used to determine the liquid mixing characteristics of the most promising material. To discover the performance of the new trays under actual vapour-liquid conditions, a 12" diameter, three tray distillation column was built and used experimentally. The separation efficiencies and tray pressure drops were evaluated for total reflux conditions at various vapour rates and outlet weir heights using the systems toluene n-heptane and toluene methyl-cyclo-hexane. The results for the new glass cloth trays showed that better performance could be obtained than conventional trays, particularly with regard to the flexibility. Various interesting phenomena manifested themselves in marked differences between the results obtained for the same material using the air-water and the hydrocarbon systems. The factors and their effects which produce these phenomena were, therefore, studied using various systems and glass cloths in a 3" diameter column.

The objective of this research was to investigate adhesion of different fouling deposits with different contact surfaces using atomic force microscopy (AFM). In this thesis, AFM has been employed to measure: (i) The adhesive interactions between a colloidal silica microparticle and stainless steel, PTFE-coated stainless steel, glass and ceramic surfaces, in the presence of a number of solutions and suspensions of ingredients found in commercially available toothpaste. (ii) To compare the measurements from the AFM and micromanipulation to see the differences and similarities. The micromanipulation technique was developed to measure the adhesive strength of different deposits. The method uses a T-shaped probe made of stainless steel chip, dimension 30 x 6 x 1 mm connected to the output aperture of a transducer (Model BG-1000, Kulite Semiconductor, Leonia, NJ. USA) which was itself mounted on a three dimensional micromanipulator (MicroInstruments, Oxon, UK). The two measurement methods are capable of giving quantitative results for the strength of the forces involved in adhesion; fast moving consumer goods (FMCG) deposits, toothpaste and confectionary stimulant deposits have been studied, and their interactions with stainless steel, glass and PTFE surfaces measured. (iii) Further investigation of AFM adhesion measurements, with caramel, whey protein and sweet condensed milk (SCM) deposits after heating at 30ºC, 50ºC, 70ºC, and 90ºC. The two selected spherical microparticles used were stainless steel and PTFE, which were attached to the end of an AFM tip. The data shows that, for removal in all cases using micromanipulation, the pulling energy increases with increasing height above the surface and the slope of the lines of pulling energy versus thickness is similar. Stainless steel shows the highest pulling energy with slightly higher energies than glass and PTFE, whilst PTFE show the lowest interaction. For the AFM data, PTFE again gives much lower adhesion forces. This is due to the different molecular interactions between different surfaces and caramel. There is thus partial agreement between the two methods. The micromanipulation method measures a range of parameters – such as the deformation and flow of the deposits, and so it might not be expected that there would be complete agreement. Here stainless steel and glass show very similar behaviour, as opposed to the differences seen using AFM; the different surface roughness of the two materials might also be expected to have an effect. At different temperatures the results from the different contact positions on the deposits; with an approach speed to the deposits for all experiments was 3μm/s, then a 5 second pause on the deposit and then the rate of retract was 0.25μm/s. Significant (more than an order of magnitude) differences are seen between forces for the same and different deposits, and between different surfaces for the same deposits. Lower forces are seen at 90ºC in all cases; at the higher temperature, the force between surface and deposit is less. To design systems to resist fouling, these results suggest that measurements at different process temperatures are needed; data at room temperature has overpredicted the interactions. The results suggest that the AFM force curve measurement technique could be used to study a variety of food deposits that have undergone different processing conditions. The method can help in optimising removal of food deposits in terms of food cleaning protocols. AFM could be a valuable technique in measuring surface properties, and in relating behaviour to surfaces. The capability of the AFM to provide better understanding of materials structure, surface characteristics and the interactive forces at the meso- and nanoscale level. The AFM will enhance the understanding of large-scale engineering processes, especially as materials are increasingly being designed down to the submicrometre level.

The potential to improve the performance of polymer composites cost-effectively has been researched across various aspects of development and manufacture. Each endeavour fell broadly into one of three categories; the principal ingredients and their required properties, the methods with which they were transformed into products and the means by which they were observed. It was determined that the ingredients with the highest potential as defined, each shared simplicity and abundance as material traits. The use of bespoke functionalised ingredients proved costly to implement, providing only modest property benefits compared to a standard formulation comprising polypropylene, 10 – 30 % w/w of 2 μm calcium carbonate with 0.5 – 1.0 % w/w stearic acid surface treatment. It was found that an apparent deterioration in impact resistance that was encountered on reducing the filler particle size was in each case observed, attributable to a coarsening of these fine particles that resulted from the mixing process. Finer particles could not be implemented more cost-effectively than standard formulations; an effect which was attributed to the tendency of the finest particles to form aggregates that could not be decomposed by mixing under high shear. However, the favourability of particle dispersion in standard formulations was used to implement a production method of polymer composites that required significantly less energy across the entire production stage and held other significant advantages. Concentrates comprising minerals in wax were produced and made to successfully re-disperse from loadings approaching those allowed by their theoretical packing maxima, in some cases up to 90 % w/w. Furthermore, a single injection moulding cycle with minimal back-mixing was used to combine concentrates and neat polymers to make commercially-competitive composite specimens, at final concentrations as low as 10 % w/w. A principal method to obtain in situ visual particle data from thin composite films was developed along with several derivative analyses. The techniques allowed rapid and representative data collection for high particle proportions at resolutions of 6 – 8 μm, accounting for particles most relevant to impact-resistance in standard formulations. As a whole, significant and realistic saving opportunities were identified in the expenditure of unnecessary resources, such as; processing energy, capital investment, transportation, labour and time. These findings were supported by experimental data.

The aim of this work is to better understand the structuring processes in low fat dairy emulsions. Model sodium caseinate-galactomannan aqueous two-phase systems (NaCAS-GM ATPS) differing in GM-type (locust bean gum (LBG), tara gum (TG), guar gum (GG), fenugreek gum (FG)) and added sugar (trehalose, sucrose, glucose and fructose) were studied by the phase-volume ratio method, rheooptics, and droplet retraction method on phase equilibria, flow behaviour and interfacial properties, respectively, at pH 5.8 and 20°C. The results revealed that the presence of sugar in concentrations 5-40 wt% resulted in an increase in cosolubility of the phases and a decrease in interfacial tension (σ). Sugar concentrations > 40 wt% decreased cosolubility. Based on the mannose:galactose ratio of GM and type of sugar (added in concentration 15 wt%) the best cosolubility and corresponding smallest σ was attributed to FG and trehalose, respectively. The flow of ATPS depended on quiescent microstructure, the shear and physical properties of the phases. In polysaccharide-continuous ATPS, the occurrence of a shear-induced phase inversion event was observed for 0- 20 wt% sugar. A further increase in sugar concentration >20 wt% was found to suppress this phenomenon due decreased viscosity ratio and formation of thread like structures in flow.

The tablet is the preferred route of delivery for pharmaceutical products to its relative ease of manufacture and high patient compliance. However, complex tablet formulations can present a number of process challenges, necessitating careful design of both the formulation and the process. This thesis sets out to investigate some of the issues involved with the lubrication of roller compaction formulations in order to gain a greater understanding of the role of lubrications. A systematic study on the effect of magnesium stearate during feeding and compaction in a horizontally fed roller compactor has been conducted. The feasibility of a novel external lubrication was investigated as an engineering solution to prevent adhesion to roll surfaces in the absence of magnesium stearate from the formulation. Alternative formulation strategies and lubricants have been investigated to find suitable materials that provide similar lubricating properties to magnesium stearate whilst exhibiting less detrimental effects on the tablet strength and tablet dissolution. The feasibility of using surrogate APIs as an aid to facilitate process and formulation design of investigational drug products was tested using a statistical analysis of the response data obtained from an experimental design.

The focus of this thesis is the role of the solvent and scale-up upon rate and selectivity in heterogeneous catalysed hydrogenations, which are ubiquitous in the production of fine chemicals and pharmaceuticals. A kinetic method has been developed based on rigorous statistical methods and sensitivity analysis for the catalytic hydrogenation of 4-phenyl-2- butanone in stirred tank reactors at two different scales using Pt/TiO2 and Pt/SiO2 catalysts. In this thesis, modelling carried out for a 100 mL scale reactor was validated against experimental data supplied by Queens University Belfast (QUB). Experimental measurements of rate and selectivity and model validation at a larger 3000 mL scale were both carried out as part of this study. The models were evaluated over a wide range of operational conditions at both scales for Pt/TiO2 catalyst, and by using a systematic kinetic methodology it was possible to identify the dominant reaction route, derive physiochemically meaningful kinetic data and a reduced kinetic model that was applicable to the scale-up. Comprehensive kinetic analysis made it possible to gain some insight into the shift in reaction mechanism upon scale-up. Kinetic investigation of solvent effects was also carried out at the 100 mL scale for a range of solvents (protic, aprotic polar, apolar, ethers, and halogens) and both catalysts, again tested against experimental data supplied by QUB. The dominant effects of solvent on rate and selectivity of the chosen reaction system were identified as the degree of active site availability imposed by competitive adsorption of solvent on catalyst and the extent of which the solvents assist the product desorption from catalyst surface. The solvent effects upon scale-up give the remarkable result of a significant shift in the selectivity of the catalyst towards phenyl ring and ketone hydrogenation groups of 4-phenyl-2-butanone.

Efforts have been devoted over the last decades towards modelling phase change kinetics of fats in chocolate. The fats in chocolate have a number of crystal forms and manufacturers must deliver a product with the right polymorph to the consumer. In this work a simplifed mathematical model was developed that clusters six polymorphs into two, namely stable and unstable, depending on their Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD) characteristics. This simplification allowed the phase change kinetics to be estimated from a set of DSC experiments conducted at different cooling and heating rates. The phase change reactions were coupled with the heat transfer equation and used to model temperature profiles and concentration of polymorphs in a model geometry. The model was able to predict both the temperature profiles measured by thermocouples (\(\pm\)2\(^\circ\)C ) and the fat crystals concentration as measured using XRD (\(\pm\)10%) at various locations in a chocolate slab. The model was applied to the recently developed processes using very high cooling rates such as the FrozenCone process, to explain their capabilities to produce "good" chocolate in spite of the high cooling rates used. Such modelling was not possible with existing models, which usually deal with either heat transfer or isothermal crystallisation kinetics. The main outcomes of this work are (i) the coupling of the reactions kinetics with heat transfer which can be expanded to other processes, (ii) the novel XRD method and (iii) the application to fast cooling processes and their explanation.

Fuel cells could substantially decarbonise domestic energy production, but at what cost? It is known that these micro-CHP systems are expensive but actual price data has been elusive. Economic realities constrain individuals’ decisions to purchase and national policies on climate change, so this lack of understanding has delayed commercialisation and government support. Models were therefore developed to simulate the economic and environmental benefits from operating fuel cell micro-CHP systems in UK homes, and to project current purchase prices into the near future. These models were supplied with economic and performance data from an extensive meta-review of academic and commercial demonstrations; showing for example that fuel cell efficiencies are a third lower when operated in people’s homes rather than in the laboratory. These data inputs were combined with energy consumption data from 259 houses to give a broad definition of operating conditions in the UK. The techno-economic fuel cell simulation model was validated against results from literature and Japanese field trials, and then used to estimate the changes in home energy consumption from operating the four leading fuel cell technologies in the UK. Fuel cells are shown to offer negligible financial benefits in the UK at present. Energy bills would increase in 30-60% of homes, due in part to the low value of exported electricity. Savings are higher in houses with larger energy bills, but significant variation between similar properties confirms that simple trends cannot be used to identify ideal houses for fuel cell micro-CHP. The feed-in tariff proposed by the UK government would radically improve economic outcomes; as 10p paid per kWh of electricity generation would reward fuel cell owners with £600-750 annually. It is estimated that today’s fuel cells produce 360-450g of CO\(_2\) per kWh of electricity generated due to reforming natural gas into hydrogen on-site. Their carbon intensity is therefore 30-45% lower than the UK grid, enabling average annual emissions reductions of 1-2.2 tonnes per home. These reductions depend strongly on the displaced electricity generation method, and could therefore range from around zero when displacing high efficiency gas turbines up to 5.5 tonnes if displacing coal. From learning-by-doing, the price of Japanese 1kW PEMFC systems is shown to have fallen by 19.1-21.4% for each doubling of production volume. Prices are therefore projected to fall from £15,000 today to £6,000 within 10±5 years, determined primarily by the speed and scale of deployment world-wide. A commercially viable price of around £3,000 is however expected to be two decades away, and widely held targets of under £1,000 per kW are argued to be unobtainable with current technologies due to the requirement for extensive balance of plant and auxiliary systems. Combining all these findings, the payback period of PEMFC systems would be 25-45 years with the proposed 10p/kWh feed-in tariff. This could fall to within current system lifetimes after 5-10 years of cost reductions; however, without this level of government support the savings from operation will be unable to give payback without major improvements in technology performance or more favourable energy prices. The carbon cost of current PEMFC systems is estimated at £750-950 per tonne of CO\(_2\) mitigated. This figure is highly sensitive to the carbon intensity of displaced generation, and would reduce to £175/T if generation from coal plants is avoided. Fuel cells are therefore not among the ‘low hanging fruit’ of carbon abatement technologies, although the carbon costs will halve over the next ten years in line with system price reductions. Investment in this technology must therefore be considered a long term strategy for low-carbon energy production.

The object of this work was to study some of the biochemical effects of various oxygen-transfer conditions in submerged cultures of a facultative anaerobe, \(Klebsiella\) \(aerogenes\) N.C.I.B. 418. A well-mixed laboratory fermenter with extensive instrumentation was used to reproduce and monitor some possible effects of 'cyclic aeration', a phenomenon experienced by microorganisms in most industrial fermentations. Batch and continuous cultures were carried out both aerobically and anaerobically, using a synthetic glycerol-salts medium. 'Cyclic aeration' was simulated by 'intermittent aeration', air and nitrogen being supplied alternately to the fermenter over a five-minute cycle. The aerobic enzymes (glycerol kinase and glycerol-3-phosphate dehydrogenase) and anaerobic enzymes (glycerol dehydrogenase and dihydroxyacetone kinase) involved in the conversion of glycerol to dihydroxyacetone phosphate were assayed in each culture sample. An aerobic→anaerobic transition, indicated most noticeably by a marked reduction of cell density, was found to take place rather sharply as the aeration time per cycle was progressively reduced. The transition point and the sharpness of the transition were dependent on oxygen-transfer efficiency during the aeration period, as well as on the aeration time per cycle, and resulted in reductions in the levels of the aerobic enzymes and increases in the levels of the anaerobic enzymes. Specific carbon dioxide production increased as 'aeration condition' was reduced to the point of fully anaerobic growth; its measurement was used, together with that of culture dissolved oxygen tension, to follow the progress of the transition. It is suggested that the determination of the complement of these enzymes could be used to assess the effectiveness of oxygen distribution in industrial fermenters.

Probiotics are live microorganisms including yeast and bacteria used as food supplements to offer health benefits. Currently available forms of yeast probiotic products include powder and gelatine capsules. A new yeast probiotic product in tablet dosage form has been developed in order to prolong product shelf life and improve product stability. The aim of the present work was to study the physiological states of yeast cells in various formulation and conditions, and to develop a rigid tablet which contains the adequate number of active yeast cells. Yeast cells became injured and had lower culturability when they were exposed to a high shear force of homogenization and compaction pressure. Tablets containing freeze dried yeast resulted in low tensile strength and could not withstand handling. Encapsulation of yeast cells with pectin demonstrated better survival and showed desirable water activity. Furthermore, the material properties of calcium pectinate beads have been investigated. A compaction of CaP beads into tablets at 90 MPa created rigid tablets with the adequate number of viable cells. Overall, encapsulated cells in CaP beads were protected more from damage during compaction and show more resistance to stress during storage. The use of flow cytometry together with fluorescent dyes for the monitoring of cell physiological states has also been demonstrated.