This thesis investigates enhanced methods for analysing non-linear effects in propagating laminar flames, enabling more accurate evaluation of laminar flame characteristics such as Markstein length and unstretched flame speed whilst proposing a new method for evaluating extinction stretch rate. Furthermore, a new cloud-combustor is developed and commissioned enabling laminar flame characteristics through droplet fuel mists to be explored again utilising advanced non-linear analysis. Re-analysis of previous low-ignition energy methane-water flames reveals the analytical non-linear characteristic. The analysis also demonstrates the need for a larger chamber to avoid pressurised effects during the latter stages of propagation, potentially reducing the accuracy of the adopted methodology. Non-linear analysis shows interesting trends concerning Markstein length at higher water loading in particular when it increase to 15% (by volume), and laminar burning rate decreased. The non-linear analysis technique is deployed to analyse four hydrocarbon fuels, two traditional paraffinic fuels in methane and propane, and two alternative alcohol fuels namely ethanol and methanol. It is shown that overdriven flame data can be used to predict flame extinction stretch rate, as long as a sufficient time period is disregarded to allow the effects of the early ignition-affected period to subside. The new technique proposed for evaluated critical extinction stretch rate shows good agreement with the traditional counter-flowing flame technique. Results for the four fuels reveal a common profile for extinction stretch-rate as a function of equivalence ratio, which was anticipated due to the similar fundamental combustion characteristics of the chosen fuels. Based on the non-linear analysis, it is shown analytically that this common profile may be represented by a combination of the iv unstretched laminar burning velocity, the Markstein length and the expansion ratio of the fuel. Ethanol in air is used to benchmark Cardiff University’s new, large 35Litre ‘Cloud Combustor’ for an investigation of flame propagation through fuel mists across a wide range of equivalence ratios. Non-intrusive, in-situ droplet sizing with concurrent flame propagation is achieved for the first time. The fuel mist flame data was subsequently compared to that for pure vapour mixtures at nominally identical ambient conditions in order to study the reported enhancement in flame speed exhibited in previous studies, and to compare qualitatively against conflicting published views reported in literature. It was found that with the onset of instabilities at certain droplet size an enhancement in flame speed could be shown for rich mist flames compared to those of analogous vapour flames. Based on mechanisms detailed elsewhere that provide a possible explanation for this enhancement full discussion and correlations that help to understand the nature of flame speed through droplet mists are presented.

Energy from Waste (EfW) technologies are beneficial for both energy generation and as a waste management option. However they face significant challenges due to the heterogeneous nature of municipal solid waste. The overall aim of the research reported in this thesis was therefore to explore some of the problems which hinder the development of commercial scale EfW technologies. A laboratory scale pyrolysis reaction rig has been developed to investigate the effect of temperature, residence time and fuel type on the pyrolysis products. Investigations were also undertaken to establish the composition of gas produced from the pyrolysis of typical waste feedstocks in two commercial scale pyrolysis rigs. An empirical model has been developed to predict the pyrolysis behaviours on a larger scale and comparisons have been made with data from the commercial scale rigs. The research findings showed that the majority of the reduction of mass during pyrolysis occurred within the first 5-10 minutes with a loss of up to 70 % at 550 °C and up to 77 % at 700 °C for paper, newspaper and cardboard. Paper, newspaper and cardboard behaved similarly with solid, liquid and gaseous fractions of approximately 33 %, 53 % and 13 % respectively. Products from the plastics components varied significantly; PET produced the highest gaseous products (42 %) and HDPE produced the highest solid products (45 %). An increase in pyrolysis temperature increased the gaseous products from paper to 34 % to the detriment of liquid and solid yields. The main gases produced from the pyrolysis were found to be CO2, CO and H2, except for the pyrolysis of PVC where the main gases produced, from the high content of hydrochloride, were not identified in this study. An increase in pyrolysis temperature was found to increase the production of CO and H2. The gas produced from commercial rig 1 mostly consisted of CO2 due to the low temperature and the addition of air to the pyrolysis chamber. The gas produced from commercial rig 2 consisted of high volumes of CO and H2 suggesting the rig was operating at a temperature above 550 °C. An empirical model was developed based on laboratory data to allow prediction the effect of a change in MSW composition on the pyrolysis gas. It was found that the addition of newspaper to a waste mix led to a higher production of CO and therefore a higher HHV. In general, the results of this study suggest that the laboratory scale pyrolysis rig used in this study and the empirical models developed, can be employed to predict the behaviour of larger scale commercial pyrolysis systems. However, further experimental investigation on the pyrolysis behaviours of mixed waste samples, especially plastic fractions, is hereby proposed.

This project arose out of a need to improve the accuracy with which the pressure drop along pneumatic conveying pipelines in process plant could be predicted. The methods previously available for making this prediction are examined and critically assessed. The need for a different method is shown, and a new approach is developed and tested. The new approach involves testing of the product to be conveyed, in a test pipeline at the smaller end of the industrial scale, with measurements being made of the pressure drop caused by bends and of the pressure gradients in straight lengths; the data is fed into a storage and retrieval system then extracted and used to predict the pressure drop in a plant pipeline conveying the same product. The method has been developed to the point where it is in current use for the design of pneumatic conveying systems for industrial applications. The development of a suitable test rig, the data storage and retrieval systems, and the method for predicting the pressure drop in a plant pipeline, are examined in detail. The method is tested against data from pipeline loops and found to give good results. A quantitative comparison is made against the work of other authors in the field; the results of this show good agreement although the scope of the current work is much wider than anything comparable. An assessment is also made of the areas requiring further work. A major advantage of the method lies in its use to predict the pressure drop along pipelines having steps up in bore size along their length, which were not amenable to treatment by previous methods. The advantages of such systems and the consequent value of the method are examined in detail.

This thesis describes a programme of work which has been undertaken with the objective of investigating means of using a laboratory erosion tester to predict the life of a bend in a pneumatic conveyor. Providing a link between a laboratory erosion tester and erosion tests on a pneumatic conveyor would lead to the development of an inexpensive way of predicting the life of a pipe bend operating under any given set of conveying conditions. An extensive literature review was carried out. From this it was concluded that very little work of an experimental corroborative nature had been out to substantiate whether erosion test results from a laboratory tester could be used to predict the life of a pneumatic conveyor bend. Two test facilities were constructed to carry out tests under accurately controlled conditions. The first of these was a laboratory 'rotating disc accelerator' erosion tester, and the second an industrially scaled pneumatic conveying test facility. Both test facilities yielded results that followed previously reported trends but also illustrated some trends that have been unreported in earlier work. It was found that the 'rotating disc accelerator' simulated erosion with minimal interference from inter-particulate collisions. For the pneumatic conveyor test bend used it was found that puncture of the bend wall occurred in the region where secondary particle impacts occurred, rather than in the region of primary impacts as reported in earlier work. Explanations for both these observations are given. An optically based construction for a cylindrical mirror was used to predict the location of the puncture point in the bend, and the intensification of particle impacts in the region of the pipe bend due to the geometry of the bend. When this was combined with an empirical erosion model derived from results obtained from the rotating disc accelerator, an accurate estimate of the life of the bend could be made. Further development of this model is discussed.

The object of this work was to investigate the interaction between rotary valves and pneumatic conveying pipelines and the effect which this can have on overall system performance. A review of previous work and current industrial practice revealed that very little work has been published on this subject, although it was evident that some manufacturers of pneumatic conveying systems do have preferred entrainment configurations. Consequently, a preliminary experimental investigation was undertaken with a transparent model of a rotary valve and drop-out box in order to observe the air and solid flow patterns inside the drop-out box. This provided the most important outcome of this work, that is, the discovery that two distinctly different modes of flow can exist in the chamber of a conventional drop-out box. The first of these is a turbulent swirling motion caused by the conveying airstream and is the most desirable operating condition because it results in the most effective entrainment of material into the conveying line. The second is a situation where the drop-out box is effectively 'choked' with product. Models to explain these two conditions have been developed and subsequently tested against data obtained from a full size positive pressure conveying system specifically constructed for this purpose. An extensive experimental programme has been carried out in which the performance of this system was examined with a selection of different entrainment configurations and different test materials. The principal variables investigated were the height and volume of the drop-out box, the orientation of the rotary valve with respect to the pipeline and the conveying air velocity. As a result of this work guidelines have been produced for interfacing rotary valves with pneumatic conveying pipelines. These have been presented as a simple list of eight points and it is anticipated that they will enable systems to be designed with more confidence than has been possible previously.

Pipelines are extensively used engineering structures for conveying of fluid from one place to another. Most of the time, pipelines are placed underground, surcharged by soil weight and traffic loads. Corrosion of pipe material is the most common form of pipeline deterioration and should be considered in both the strength and serviceability analysis of pipes. The study in this research focuses on two different types of buried pipes including concrete pipes in sewage systems (concrete sewers) and cast iron water pipes used in water distribution systems. This research firstly investigates how to involve the effect of corrosion as a time dependent process of deterioration in the structural and failure analysis of these two types of pipes. Then two probabilistic time dependent reliability analysis methods including first passage probability theory and the gamma distributed degradation model are developed and applied for service life prediction of the pipes. The obtained results are verified by using Monte Carlo simulation technique. Sensitivity analysis is also performed to identify the most important parameters that affect pipe failure. For each type of the pipelines both individual failure mode and multi failure mode assessment are considered. The factors that affect and control the process of deterioration and their effects on the remaining service life are studied in a quantitative manner. The reliability analysis methods which have been developed in this research, contribute as rational tools for decision makers with regard to strengthening and rehabilitation of existing pipelines. The results can be used to obtain a cost-effective strategy for the management of the pipeline system. The output of this research is a methodology that will help infrastructure managers and design professionals to predict service life of pipeline systems and to optimize materials selection and design parameters for designing pipelines with longer service life.

This thesis addresses a remote grid fed by a weak transmission line and a local source of renewable generation. Energy Storage System (ESS) is installed at the remote grid. The thesis investigates the use of the Energy Storage System in improving the overall system efficiency and increasing the power system stability for the transmission line and remote grid system. The Energy Storage System reduces transmission line losses and hence can improve the overall efficiency of the system. The key parameters that are significant to improving the overall system efficiency are derived and a simple mathematical analysis is undertaken to show the criteria for increased system efficiency. A PSCAD/EMTDC simulation is undertaken which is shown to be consistent with analysis both for simple and real wind profiles. For the case of stability investigation, a large Constant Power Load (CPL) is connected at the remote grid. This thesis performs the mathematical modelling and stability analysis of the combined CPL, grid, wind farm and energy storage. It is shown that CPLs fed by active PWM rectifiers are fundamentally stable if operated below the transmission line load-ability limit, and those fed by diode bridge rectifier can be unstable depending on filter values. It is revealed that the instability can be improved by control of auxiliary units such as an energy storage units. In order to reduce the simulation time required, a simplified model of a wind farm feeding a DFIG connected to a remote grid is proposed and compared with a detailed model using the PSCAD/EMTDC software.

Fibre laser cutting of mild steel using oxygen and nitrogen is widely used in industries throughout the world. An IPG YLR-2000 Ytterbium fibre machine with a maximum power of 2 kW and a wavelength of 1.06 µm is used throughout this research. The effects of oxygen and nitrogen as assist gases on the feature of laser cutting process are different in terms of kerf width, surface roughness, heat affected zone and striation pattern. The kerf width in oxygen laser cutting is wider than that for nitrogen. The striation pattern on oxygen cut edge is smoother than that for the nitrogen cut edge. When using oxygen, the cut edge is covered by a fragile oxide layer while this feature is not seen on the nitrogen cut edge. After laser cutting with oxygen, the cut edge is dross free whilst nitrogen cut edge is drossy. Laser piercing is used to generate a starting point for laser cutting. The pierced hole is normally larger than the kerf width, which means that it cannot lie on the cutline. An experimental programme investigating the piercing process as a function of laser and assist gas parameters is presented. Oxygen and nitrogen were used as assist gases, with pressures ranging from 0.3 to 12 bar. The sizes, geometries and piercing time of the holes produced have been analysed. The pierced hole size decreases with increasing gas pressure and increasing laser power. Oxygen assist gas produced larger diameter holes than nitrogen. A new technique is presented which produces pierced holes no larger than the kerf with and would allow the pierced hole to lie on the cut line of the finished product – allowing better material usage. This uses an inclined jet of nitrogen when piercing prior to oxygen assisted cutting. Specific point energy (SPE) is a concept that has been successfully used in laser welding where SPE and power density determine penetration depth. This analysis allows welding carried out by different laser systems to be directly compared. This work investigates if the SPE concept can be applied to laser cutting. Laser cutting of various thicknesses of mild steel, two different optical set ups and three different delivery fibres with a range of powers and translation speeds is done to gain results for numerous different parameter combinations. It is found that the SPE concept is applicable to laser cutting and the following effects noted: for given material thickness and any given value of SPE, cost is decreased by using a larger beam diameter; for given cut sheet thickness, cutting efficiency increases with SPE; for given value of SPE, cutting efficiency increases as material thickness decreases.

A reduction in greenhouse gas emissions by the energy sector is required to decelerate global warming. With the domestic sector being the biggest energy consumer, a great amount of saving potential is available in the operation of dwellings. This thesis is proposing to improve domestic energy efficiency by combining energy saving control measures designed to be made by occupants and automation systems, called Combined Occupant and Automation Control (COAC). It highlights that the occupant’s position is necessary to effectively integrate both of those conservation methods. Three unobtrusive domestic occupant detection technologies were identified and compared for this purpose. Device-free Localisation (DfL), an emerging technology, which was found to be the most suited for a COAC system, was then investigated further by the means of a series of technical experiments. A questionnaire, investigating user perception of DfL and of COAC systems, was conducted. Furthermore, case studies were undertaken, during which three dwellings with real occupants received prototypes of a COAC system, consisting of automated washing appliances and a smart pricing scheme. As part of these case studies, semi-structured interviews were conducted. User preferences with regards to the COAC system’s interface and operation were established. Also, behavioural changes, induced by occupant control methods, were observed. The different studies furthermore found that financial gain was the main incentive to save energy. Automation system’s support in conserving energy was demonstrated to be distinctly appreciated and although security and privacy concerns were prevalent, DfL’s support was also permitted. Furthermore, guidance was developed for DfL setup and operation, especially with regards to using an automation system’s infrastructure for this purpose. In conclusion, this research suggests that the novel concept of integrating DfL and COAC meets the technical and practical requirements for general adoption, and hence provides another tool in the race against global warming.

The UK government determined that 30% of the total electricity and 15% of the total energy should be generated from renewable sources by 2020 according to the Low Carbon Transition Plan. However, most renewable energy technologies are intermittent because they depend on weather conditions and they do not offer matching capability. Energy storage is attracting intensive attention as a technology which converts renewable energy technologies into a dispatchable product which meets variable demand loads. There is increasing interest for energy storage located very close to consumers which is able to augment the amount of local renewable generation consumed on site, provides demand side flexibility and helps to decarbonise the heating sector. This thesis optimises community energy storage (CES) for end user applications including battery, hydrogen and thermal storage performing PV energy time-shift, load shifting and the combination of them. The optimisation method obtains the economic benefits of CES by quantifying the levelised cost, levelised value and internal rate of return. The method follows a community approach and the optimum CES system was calculated as a function of the size of the community, from a single home to a 100-home community. A complimentary methodology was developed including three reference years (2012, 2020 and zero carbon year) to show the evolution of the economic benefits during the low carbon transition. Additionally, a sensitivity analysis including the key parameters which affect the performance and the economic benefits was developed. The community approach reduced the levelised cost down to 0.30 £/kWh and 0.14 £/kWh for PV energy time shift and load shifting respectively when projected to the year 2020. These values meant a cost reduction by 37% and 55% regarding a single home. A cost of the storage medium of 275 £/kWh for Li-ion batteries (equivalent to a 10% subsidy over the assumed cost, 310 £/kWh) is the break-even point for Li-ion batteries by 2020 for an electricity price equal to 16.3 p/kWh (R^2=0.6). Secondly, this thesis presents a new community hydrogen storage system integrated in a low carbon community and the experimental results when performing PV energy time-shift, load shifting and the combination of them. Long term ES was demonstrated when the community storage hydrogen system performed load shifting and the capacity factor of the electrolyser increased by 116% when PV energy time-shift was performed in addition to load shifting. This system was designed in collaboration with industrial partners and the key findings obtained during the construction and testing phases are shared.