This thesis describes a theoretical and experimental investigation of the ejector re-compression lithium bromide absorption refrigeration cycle. In this novel cycle, a steam ejector is used to enhance the concentration process by compressing the vapour to a state that it can be used to re-heat the solution from where it was evolved. Since this cycle recovers the heat otherwise wasted in a conventional absorption cycle, the energy performance of the cycle is improved. The theoretical study shows that the improvement of the efficiency is proportional to the performance of the steam ejector. A COP of 1.013 was achieved from the experiment in this investigation. The novel cycle does not only improve the energy efficiency but also avoids the corrosion that will happen when high temperature heat sources are used to drive a lithium bromide absorption refrigerator. The steam ejector in the novel cycle acts as an efficient temperature converter in acceptance of different temperature heat sources, which reduces the energy loss when the temperature difference between the solution and the heat source is big. Therefore, the solution temperature can be set to a low level while the heat source temperature is high. This is significant to avoid the corrosion of lithium bromide solution at high temperature. Furthermore, the construction of the machine based on the novel cycle is simpler than that based on the conventional double-effect cycle. This refrigerator will be more reliable and have a lower initial capital cost. The cycle was investigated comprehensively in this thesis. In the theoretical study, a mathematical model for this novel cycle was established. The theoretical study reveals the operation characteristics and the factors that affect the energy efficiency of the cycle as well as how to design a refrigerator based on the novel cycle. In the experimental study, a concept-approved refrigerator was manufactured and tested. The part-load performance of the novel cycle was investigated from the experiment. The theoretical results had a good agreement with the experimental ones. NB. This ethesis has been created by scanning the typescript original and contains some inaccuracies. In case of difficulty, please refer to the original text.

This thesis reports data on blends of carrageenan (0.3%w/w) and locust bean gum (0.3%w/w) in the presence of biopolymers, particularly gelatin of varying concentration. Particular attention is given to their behaviour on autoclaving since this is relevant to one of the most important applications of these materials as gelling agents in canned meat products. It was shown there is such 3% gelatin could be found in the gelling system as a result of from collagen in the meat. Gelatin at this level generally reduced the strength of non-autoclaved carrageenan and LBG gels but enhanced autoclaved gels. Studies of turbidity and rheology suggested that the effect was due to phase separation. Investigation of viscosity after autoclaving produced evidence to support the hypothesis that gelatin protected LBG from thermal degradation. For industrial LBG this was not, however, observed by direct molecular weight measurement, although such effects were seen for pure LBG. Interesting differences between the gel strength response between low and high ionic strength buffers were found. It was concluded that textural performance in real products was sensitive to a range of factors (salt, impurities, presence of gelatin) and would be interpreted by a combination of degradation and phase separation theory. Implications for the industry are discussed.

In recent years interest has grown in the use of composite components within the automotive industry. Fibre reinforced plastic (FRP) components are of particular interest to the industry, since lower tooling costs and part consolidation can be utilised, whilst lighter, stiffer components can be produced. Several methods are available to produce FRP components at high volumes, including compression moulding (using dough and sheet moulding compounds), reinforced reaction injection moulding (RRIM) and liquid moulding processes (resin transfer moulding (RTM) and structural reaction injection moulding (SRIM)). RTM is a closed mould process, which is widely used to produce components economically in low volumes using matched moulds to produce two good surfaces. The absence of a high volume manufacturing technology, however, has impeded the acceptance and advance of RTM within the automotive industry. A research programme was established at the University of Nottingham to address the problems associated with the use of RTM for high volume manufacture. This programme has considered the topics of process technology, processing characteristics of polyester resin systems and fibre preforms, fibre wet-out and interfacial bonding, mould design, microwave pre-heating of reactive resin systems and process modelling. This thesis concerns the research which was undertaken to identify the causes of void formation during the impregnation and polymerisation stages of RTM, and methods of reducing the final void content within the component. The impregnation phase of the RTM process was identified as being the stage where the majority of voids were formed. A study of oil impregnation (having a similar viscosity to that of resin) into reinforcement was undertaken to determine the reasons for uneven flow and air entrapment. The dry reinforcements were studied to assess the microstructure of the preforms in order to determine reasons for obstruction of the resin flow. Fabric stitching, thermoplastic binder and size deposits were identified as potential causes of flow impediment. Fibre orientation and preform stacking were also assumed to assist in the development of uneven flow, leading to air entrapment. A major factor determining the formation of microvoids within fibre bundles was identified as the transverse impregnation of resin into high Tex fibre bundles. The major moulding process variables of injection pressure, vent pressure, fibre volume fraction, mould temperature and resin pre-heating have been assessed, to determine their effect on the void content within unidirectional and CFRM reinforced polyester laminates. It was observed that vacuum assistance during impregnation reduced void formation, although higher exotherm pressures and the possibility of monomer boiling arise from its use. A simple impregnation model was developed to assess the microscopic impregnation rates between fibre bundles, in the capillary between fibres and transversely into fibre bundles. The results from this model were compared with actual moulding histories. The findings of the overall work are discussed and suggestions proposed for the reduction of void content in RTM automotive components.

The aim of this project was to examine the application of fracture mechanics to static and fatigue failure in GRP. The performance of two materials commonly used in-shipbuilding was compared, and the stress intensity factor approach was chosen as being most useful in the design of GRP structures. The literature survey showed that the conditions for its valid application to fracture toughness measurement were not established. Fracture toughness tests were carried out to examine the effect on critical stress intensity factor, Kc of prolonged water immersion, specimen geometry and size. For the latter, a machine was designed and developed to apply static and pulsating loads to sheets of GRP up to one metre square. The material reinforced with woven roving fabric (WRF/PR) had a much higher fracture toughness than the material reinforced with chopped strand mat (CSM/PR), and was found to be virtually notch insensitive, implying that the Kc approach is not applicable. Large specimens of CSM/PR failed at very low stresses compared with small specimens. This material is notch sensitive and some of the conditions for the valid fracture toughness testing of notch sensitive GRP were established. The critical stress intensity factor of both materials was little affected by water immersion. Fatigue crack propagation tests were carried out to establish crack growth laws and examine the effect on growth rate of prolonged water immersion. Growth laws were found that were applicable to dry and wet CSM/PR, but water immersion greatly increased the rate of fatigue crack growth. The resistance to fatigue cracking of WRF/PR is superior to CSM/PR, because crack growth is blocked by rovings running normal to the crack, so that a growth law could not be found. Prolonged water immersion was found to destroy this blocking mechanism greatly reducing the resistance to fatigue crack growth, and a growth law could be determined. The material is still superior to CSM/PR in the wet condition. The finite element method was used to determine the stress intensity factors of fracture toughness specimens, and compliance-crack length relations in fatigue crack propagation specimens.

Falling film reactors are a very effective geometry in which to carry out fast exothermic gas-liquid reactions, because they allow easy removal of the heat produced. To optimise and improve falling film reactors, soundly based physical models are required. Existing models assume a flat liquid film combined with empirically-determined mass transfer coefficients, but there is growing evidence that this is unsatisfactory, since the interface is dominated by ripples and larger disturbance waves which have a significant effect on the mass and heat transfer rates through and into the film. The main objective of this study was the better understanding through experimental study of the interfacial characteristics of liquid falling films in the presence of a co-current down flow of air, with emphasis on the physical and hydrodynamic conditions encountered in current falling film reactor technology, so that the information obtained can be implemented in the enhancement of falling film reactor modelling. The liquids chosen were water, for validation of the measurement techniques through comparison with the literature, and two common falling film sulphonation reactor feedstocks; dodecylbenzene and ethoxylated alcohol. The experimental study consisted of film thickness and disturbance wave celerity measurements in a purpose built flow facility with a flat plate flow surface. A novel spatial film thickness measurement technique, the Light Absorption Imaging Technique (LAIT), was developed to give unparalleled spatial information on the interfacial characteristics of liquid films. A computer algorithm-based technique has been developed for categorisation of the spatial film data obtained by LAIT into substrate and disturbance wave regions, from which globally averaged characteristics of the interfacial structure have been obtained. Disturbance wave celerity measurements were obtained utilising the cross-correlated output signal from two light sources and a manual time-of-flight measurement technique using the images from a high-speed video camera. The study has provided a comprehensive set of data on the hydrodynamic structure of the interface, with and without the influence of a co-current down flow of air, for both water and actual sulphonation feed stocks as the liquid phase. The dramatic influence of both flow conditions and physical properties on interfacial characteristics has been demonstrated In particular, a transition has been observed of the disturbance wave structures in falling films due to the influence of a co- current airflow. Differences in the disturbance wave structure have been identified between the organic and water films after this transition.

Ultrasonic spectrometry has potential for monitoring chemical processes on line; an important application is the detection of the suspended particle size distribution (PSD) in emulsions. Measured ultrasonic wave attenuation as a function of frequency is compared to the predictions of an adaptive wave propagation model to obtain an estimate of the PSD. Current models are based either on scattering physics, heat transfer, or hydrodynamics, or on a combination of these. Most models give good prediction of attenuation for dilute and semi-dilute systems, but they are known to break down at high dispersed phase concentrations and for very small (10s of nm) particles. The limits of applicability are not known in a formal sense. The principal aim and contribution to knowledge of this research is to formally determine the limits of existing theory and to set out which model or models are appropriate for use with emulsions with large or very small particles (nano-emulsion), and at small and large concentrations of dispersed phase. The second aim is to answer the same question for the case of encapsulated emulsions in which the droplets are encapsulated in a thin polymer shell. The project combines computational methods based on analytic theories of wave propagation with a comprehensive experimental programme.

Previous work has shown that following the inclusion of alginate high in mannuronic acid there is a reduction in the viscosity of soya melt during extrusion, this work attempts to identify the mechanism for this effect. The effect of water content and hydrocolloid inclusion on the denaturation behaviour and water binding properties of soya protein has been investigated, mainly by the use of differential scanning calorimetry. Of a range of parameters investigated, transition onset temperature and enthalpy, change in specific heat function and coopertivity of the transition all show a dependence on initial moisture content. These parameters are all changed if soya is heated in the presence of a high mannuronic acid alginate. With the exception of changes in enthalpy these effects are not seen to the same extent with other added hydrocolloids. These changes have been attributed to the production of water during heating. Measurements of freezable water and sorption isotherms suggest that alginate addition increases the water binding ability of soya isolate after denaturation. When heated at high temperatures only soya and gluten (out of 7 proteins tested) produced measurable quantities of additional water. In the presence of 2% Manucol DM the formation of water was markedly increased in the soya and gluten samples but not in the other proteins. Production of increased amounts of water after alginate addition was demonstrated to be dependent on the quantity of mannuronic acid in the alginate. The dependence of this effect on water activity suggests that it is the result of browning or condensation reactions. Glutamic acid was implicated with the specific reaction between soya and alginate, though in heated soya both loss of lysine and serine were found. Differential rates of degradation were found between a high mannuronic acid alginate and a high guluronic acid alginate after heat treatment. The alginate high in mannuronic acid was shown to depolymerise to a far greater extent. Various estimates for the molecular weight of the heat treated samples were obtained and no correlation could be found between increased reducing capability of the sample and extent of depolymerisation. Furthermore the production of volatiles that may be expected from sugar ring degradation were not found. Increased brown colour formation and water production and concomittant decreased glutamic acid content were found in soya samples extruded in the presence of 1% Manucol DM. It was concluded that the chemical reactivity of glutamic acid with alginates rich in mannuronic acid explains the well established effect of this type of polysaccharide in extrusion processing.

The chemical engineering industry often requires people to work in hazardous environments and to operate complicated equipment which often limits the type of training that be carried out on site. The daily job of chemical plant operators is becoming more demanding due to the increasing plant complexity together with increasing requirements on plant safety, production capacity, product quality and cost effectiveness. The importance of designing systems and environments that are as safe as possible to educate and train personnel is vital for the chemical process industries. Virtual reality offers the potential to expose personnel to hazardous situations in a safe, highly visual and interactive manner. Virtual reality has been proposed as a technological breakthrough that holds the power to facilitate learning. The ability to visualise complex and dynamic systems involving personnel, equipment and layouts during any real operation is a potential advantage of such an approach. Virtual reality and multimedia training is commonly used in many industries, aiding understanding and memory retention and creating a more interactive learning experience. Four desktop virtual reality training environments were developed for this research which highlighted issues related to chemical process dynamic simulation and plant safety. The pump training system is a virtual reality environment, which was built using the SAFE-VR virtual engine, to train personnel to operate two centrifugal pumps. The virtual hazard spotting exercise focuses on improving the users' safety awareness of electrical and occupational hygiene hazards. The virtual boiler plant is a complicated and high detailed virtual training environment, which is characterised by its flexibility and by a real time dynamic simulation of the steam generation chemical process. The virtual flooding and gas absorption experiment was based on an undergraduate laboratory experiment for the Chemical Engineering degree course at the University of Nottingham, focusing primarily on training and safety issues of students using the equipment. The dynamic features of the virtual absorption column simulation give high level of realism in the virtual environment.

This thesis describes the work undertaken developing techniques for the design and manufacture of continuous fibre preforms for liquid composite moulding. A prototype tow placement facility based on the roller placement of up to 5 tows onto a flat bed was developed. This was used to prepare preforms for 4 industrially based demonstrator components which were subsequently successfully moulded. In tests vibrational performance of parts so manufactured showed slight improvements in mechanical performance compared with those manufactured from conventional reinforcement. The facility was also used to lay down preforms, the fibre structure of which had been generated by undraping a 3 dimensional model of the finished component. In this manner the performance of the composite, of both mechanical strength and permeability during injection could be optimised. The lay down machine was also used to generate performs with a well defined built in waviness to the fibre structure. This material was used to generate information regarding the degradation in performance when waviness is introduced and also the effect on permeability during the injection phase.

Fibre reinforced plastics (FRP) are of considerable interest to the automotive industry. Intelligent application of these materials could reduce vehicle weight for higher operating efficiency, at a reduced manufacturing cost. The principal use of FRP in high volume (greater than 100,000 parts per annum) has been restricted to non-structural body panels made from short fibre reinforcement. Long fibre reinforced composites are ideal for load bearing structures resulting from a high specific strength. However, a high volume technique to produce these components at a moderate cost has not been realised. One long fibre reinforcement process with the potential to meet the high volume demands of the automotive industry is resin transfer moulding (RTM). Prolonged cycle times are an obstacle to high volume RTM. Cycle time is dictated by thermal quench near the injection gate from cold resin entering the hot mould. Heat recovery by the mould, and coincident heating of the resin to initiate cure is necessary to complete the cycle. Microwave preheating of the resin before injection reduces thermal quench. Since microwave heating is volumetric, low conductivity resins can be heated uniformly and efficiently. In-line resin preheating has been developed for its compatibility with high volume RTM. The use of an in-line microwave resin preheating system to reduce cycle time was investigated. This system was incorporated into the automatic RTM cycle. The resin temperature could be held constant or profiled during injection using a proportional-integral-derivative (PID) power controller. Both injection techniques reduced cycle time, although temperature profiling enabled coincident resin cure across the mould for a maximum cycle time reduction. Resin preheating had no adverse affects on the RTM process or laminates. This suggested that the microwave resin preheating system could be retrofitted within an existing RTM facility to reduce the component cycle time without damaging the mould or degrading component quality.