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The increasing demands placed on conventional methods of liquid atomization, in terms of spray quality, now mean that there is a need for a new, disruptive, liquid atomization technology which can rapidly improve spray performance to meet the growing sophistication required of modern liquid spray systems. This thesis details an investigation into the mode of action of a liquid atomization system (pMISTe) which shows promise to be able to provide this disruptive new spray technology. Influenced by the defence mechanism of the bombardier beetle, this atomization method produces a large amount of volumetric shear in a body of liquid, by inducing a flash evaporation of a proportion of the total liquid mass in an enclosed chamber. The flash evaporation is created firstly by heating the liquid far above its saturation temperature at an ambient external pressure - in a chamber cavity sealed by an electronically controlled ejection valve. This valve is released very rapidly, causing the liquid in the chamber to suddenly `see' the ambient external pressure. It is this sudden exposure of a superheated liquid to the low external ambient pressure that drives the flash evaporation and the atomisation. The atomization system was investigated using a staged experimental method, including a mixture of Taguchi Design of Experiment (DoE) and full factorial techniques. From these investigations the main characteristics of the mode of action of the system were identified. These were that, in general, increases in chamber liquid temperature caused decreasing average droplet size, and that increases in refill flow rate caused increasing droplet size; due to the primary flash evaporation mechanism. In addition more complex secondary behaviours, attributed to the fluid dynamic properties of the system, were discovered. The performance of the system is also discussed with reference to its suitability for a range of spray applications

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With the inevitable exhaustion of supplies of oil and other fossil fuels looming on the horizon, coupled with the increasing concern regarding the environmental impact of using these resources, governments worldwide are under pressure to invest in the development of renewable replacements for fuel, as well as natural alternatives to oil based materials such as plastics. One of the main sources of interest is lignocelluloses, comprised of three main components - lignin, cellulose and hemicellulose each of which can be a valuable raw material for fuel or polymer production. The problem however is that the three components are bound together chemically, and efficient separation requires a combination of physical and chemical treatments. It is the aim of this project, therefore, to develop novel processing for the hydrolysis of lignocellulose. The process will involve the use of Ionic Liquids, essentially salts which are liquid below 100°C. While these chemicals have been known of for decades, it is only in the last twenty years or so that research into their potential as solvents, catalysts, reaction media, etc. has accelerated and interest has increased in their use in biorefining. This project is concerned specifically with novel methods incorporating an acidic, hydrophobic ionic liquid in the hydrolysis of lignocellulose with the aim being to produce nanocellulosic fibres and examine their performance as composite fillers. This began with the analysis of novel ionic liquids based on phosphonium and choline cations in the hydrolysis of wheat straw. From this the most promising medium was evaluated in its ability to refine cellulose and compared with a traditional hydrolysis method using dilute sulphuric acid. Furthermore novel lignocellulosic feedstocks, anaerobic digestate and spent mushroom compost, were analysed to determine their suitability as sources for nanocellulosic fibres which would represent an innovative use of these waste materials.

Multi phase catalytic reactions such as hydrogenations, oxidations etc. are frequently encountered in the pharma and fine chemical industries. Multiphase reactor systems generally used in such processes were targeted for improvement in this research. This research project begins by analysing the benefits of process intensification by scaling down of conventional reactor systems. A brief survey on different microreactor technologies were carried out in the first chapter, which was then followed by chapter 2, describing different experimental methods adopted in this research. In the first part of the research, multi phase microreactor in the form of a micro-trick1e bed was designed. The reactor was heated from inside out by coupling it with the phenomenon of non-contact induction heating. Such reactor design was further extended in the second part of the research to create dual isothermal temperature zones inside a single reactor, where two different catalyst beds were placed in a cascade configuration. This led to the realization of a novel catalyst and temperature compartmentalized reactor system. Cascade catalytic reaction of citronellal to menthol was chosen as a model reaction. The high heat transfer rates obtained in the radio-frequency heated micro trickle bed reactor was further exploited in generating periodic temperature oscillations of the catalyst bed and this led to the design of a transient reactor system. It was observed that selectivity toward the semi-hydrogenated product increases around 10 to 12% for periodic temperature oscillation of the reactor bed when compared with the reactor maintained at a steady temperature. Finally the existing design of the micro-trickle bed reactor (MTBR) was scaled-up to a six times scale up factor. The selective hydrogenation of acetylene alcohol was chosen as a model reaction for testing the reactor performance. A conceptual design of a pilot plant, involving such scaled-up MTBRs for a target production of 1 kg/day was also proposed.

This study uses a number of laboratory testing and ageing methods in order to investigate how effectively they correlate to catalyst ageing on a vehicle. The activity testing of full size catalyst bricks was successfully conducted using the Catagen Labcat test system, and correlation with the light-off activity of cored catalyst samples in the Horiba SIGU 2000 examined using the QUB global catalyst model. Static ageing was conducted in the laboratory, using the BAT equation to calculate ageing times for ageing temperatures relating to a RAT-A cycle. The thermal reactivity coefficients for static ageing in different ageing atmospheres were calculated and compared to those recommended by the EPA for dynamic ageing. Finally, using the results achieved from these raboratory ageing methods, recommendations were made as to how ageing models reviewed in the literature could be improved. From experimental results alone, it was seen that no correlation existed between the light-off performance of cored catalyst samples and full size bricks. However, the QUB global catalyst model was able to consider variations in precious metal dispersion between samples, differences between inlet temperature and gas concentrations, and heat transfer characteristics of the two reactors. The simulations performed were able to show good correlation between the test methods. However, the two tests methods showed differently the activity rank of the samples, indicating the variation in precious metal loading and dispersion throughout each full size brick. In other results, static ageing of palladium loaded catalyst samples was found to show no ageing effects due to time for ageing temperatures below 1000 C. Static ageing methods were also shown to cause deactivation at a slower rate than dynamic methods. It was shown that the Toyota ageing expression would better predict catalyst deactivation if it incorporated an oxygen factor, to describe ageing when no oxygen is present.

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