Environmental issues such as air and water pollutions and climate change can be linked to the fossil fuels being still the main source for human activities and therefore, its intensive consumption. As a result, there is a clear need to utilise alternative and clean energy sources to address these environmental problems. Solar thermal energy has a potential to diminish the dependency on fossil fuels and reduce CO2 emissions in which solar radiation is converted to heat via a thermal fluid for power and heat generation. Medium and high-temperature solar thermal systems where concentrated collectors are employed have been utilised for power generation, whereas low-temperature solar systems where non-concentrated collectors such as flat plate are employed have been used for heat generation. A review of the literature indicates that by using an appropriate thermal fluid, the generation of power and heat is possible via low-temperature solar thermal systems. It can also be revealed from the literature that when selecting a thermo-fluid to be utilised in such systems it is important to consider thermophysical, environmental and safety aspects all together. This project is focused on the investigation of novel and environmentally friendly thermo-fluids that can be potentially utilised in low-temperature solar thermal systems for mechanical and heat energy generation. This was accomplished in three stages. Firstly, a low-temperature solar thermal system which consists of solar organic Rankine cycle and heat recovery units was designed, commissioned and tested experimentally. In the experiments, HFE 7000 refrigerant that has zero ozone depletion potential (ODP) and low global warming potential (GWP) was employed. The performance of the system was evaluated in terms of energy and exergy analyses. In the 2nd stage, the flat plate collector was mathematically modelled and simulated under various operating conditions. Then, the model was extended to the solar organic Rankine cycle to perform a simulation study where 24 organic compounds were examined according to their applicability in terms of the thermal performance of the cycle and environmental properties of the fluids such as flammability, toxicity and global warming potential. In the last stage, a numerical study of the laminar flow of HFE 7000 based nano-refrigerants at different Reynolds number and volume concentration ratio was conducted. The convective heat transfer coefficient, the pressure drop and the entropy generation of the each flow was investigated.

Gas turbines (GTs) are extensively used in many power generation applications. This project has close coupled advanced, economic diagnostics with the technology of prime movers using a Genetic Algorithm (GA) to optimise the economic performance of fleets of GTs for electricity production. The investigation has included comparative assessment of traditional and novel GT options, including the design and off-design performance of the engines. The originality of the work lies in the concurrent technical and economic optimisation of a fleet of GTs based on a GA using current and novel engine cycles in a wide range of climatic conditions. The project has developed an effective model for optimising operational strategies for off-design conditions capable of optimising the economic performance of existing fleets of GT engines to meet power requirement while minimising environmental impact. It has also developed an approach able to simulate engine operating conditions with attendant costs under different scenarios based on the Techno-Economic, Environmental, and Risk Analysis (TERA) philosophy which allows for a broad and multidimensional analysis of the problem. By integrating the TERA model with in-house performance simulation software (Turbomatch) it has been possible to simulate the engine performances at design point and off-design conditions and maximise total power output at minimum cost to aid equipment selection and plant operation strategies for new plant. This study simulated and accounted for the time value of money during the operational life of the power plant. The model includes a life cycle cost assessment including: capital cost, maintenance and operating costs, fuel cost and emission taxes. Using the Net Present Value (NPV) technique the model was able to make techno-economic comparisons between various modes of operation and variations in power demand. Peak load operation requires GTs to operate at high firing temperatures with consequent reduction in component’ useful life. The techno-economic analysis found the optimum condition between both operating condition and corresponding strategies and thus includes a comparative lifing model, which performs stress and thermal analyses, and estimates the component’s minimum creep life using the Larson Miller method. A fleet of GT engine operating in a warm coastal environment have been modelled and investigated in this study. The results showed that the combined effect of the operating environment and the power demand can have significant impact on the blade creep life. The ability to predict this impact will aid GT users in the decision making process associated with GT operation. The project has developed an emissions model which identifies the GT engine with smallest impact on global warming and lowest cost of ownership (including governmental taxation policies) and which will meet a variety of emission legislation.

The development of solid-state switches for pulsed power applications has been of considerable interest since high-power semiconductor devices became available. However, the use of solid-state devices in the pulsed power environment has usually been restricted by device limitations in either their voltage/current ratings or their switching speed. The stacking of fast medium-voltage devices, such as IGBTs, to improve the voltage rating, makes solid-state switches a potential substitute for conventional switches such as hard glass tubes, thyratrons and spark gaps. Previous studies into stacking IGBTs have been concerned with specific devices, designed or modified particularly for a specific application. The present study is concerned with stacking fast and commercially available IGBTs and their application to the generation of pulsed electric field and the switching of a high intensity Xenon flashlamp. The aim of the first section of the present study was to investigate different solid-state switching devices with a stacking capability and this led to the choice of the Insulated Gate Bipolar Transistor (IGBT). It was found that the collector-emitter voltage decreases in two stages in most of the available IGBTs. Experiments and simulation showed that a reason for this behaviour could be fast variations in device parasitic parameters particularly gate-collector capacitance. Choosing the proper IGBT, as well as dealing with problems such as unbalanced voltage and current sharing, are important aspects of stacking and these were reported in this study. Dynamic and steady state voltage imbalances caused by gate driver delay was controlled using an array of synchronised pulses, isolated with magnetic and optical coupling. The design procedure for pulse transformers, optical modules, the drive circuits required to minimise possible jitter and time delays, and over-voltage protection of IGBTmodules are also important aspects of stacking, and were reported in this study. The second purpose of this study was to investigate the switching performance of both magnetically coupled stacks, in pulse power applications such as Pulse Electric Field (PEF) inactivation of microrganisms and UV light inactivation of food-related pathogenic bacteria. The stack, consisting of 50 1.2 kV IGBTs with the voltage and current capabilities of 10 kV, 400 A, was incorporated into a coaxial cable Blumlein type pulse - generator and its performance was successfully tested with both magnetic and optical coupling. As a second application of the switch, a fully integrated solid-state Marx generator was designed and assembled to drive a UV flashlamp for the purpose of microbiological inactivation. The generator has an output voltage rating of 3 kV and a peak current rating of 2 kA, although the modular approach taken allows for a number of voltage and current ratings to be achieved. The performance of the switch was successfully tested over a period of more than 10⁶ pulses when it was applied to pulse a xenon flashlamp.

This thesis discusses the advantages, performance and design of permanent magnet motors with, claw type armatures when used to produce a brushless d.c. drive. The work in this thesis can conveniently be divided into two parts. The first part included chapters 2 to 5 inclusive is concerned with the fundamental differences between the claw and drum-wound type of armatures. A double rotor disc shaped version of the claw armature has been developed to reduce the. armature leakage inductance and experimental results show that the claw machine can be designed to produce a more flexible medium power drive with high output/volume and efficiency than a more conventional drum-wound type of armature. The second part is included in chapters 6 to 8 inclusive and describes the development of a linear form of the claw motor. A linear version of the claw machine has been developed and consideration is given' in chapter 8 to the machines performance including the thrust and acceleration for linear motor applications particularly as a passenger lift drive. The linear claw machine uses an active stator divided into sections and each section is on! y energised when it is overlapped by the moving member. Chapter 7 gives the design and construction of the power drive circuit which produces transient free commutation from one stator section to the next.

This thesis has focused on three different aspects. The first was improving of biophotovoltaic cells based on dye-sensitized sensitized solar cells (DSC) based mainly on using extract of spinach as natural and cheap dye instead of laboratory-synthesized dyes. The extraction was performed using four methods with solvents of acetone, petroleum ether, methanol and dioxane. The yield of extract was 0.16-0.31 mg from 200 g of spinach leaves. Then the extract was used to manufacture DSC devices. The factors that can affect the efficiency of the cells have been studied including the dyeing solvent, the temperature and time of sintering, the thickness of the Ti02 film, the treatment of photoelectrode films with acids and/or TiC4 solution, the type of Ti02 paste used, the electrolyte and the design of cell. The highest efficiency and short current (Jsc) reached were 0.71% and 1.77 mA.cm-2 , respectively by passive dyeing which increased using ultra-fast sensitization to 1.13% and 2.67 mA.cm-2, respectively. To our knowledge, this is a higher efficiency for a spinach extract than that published in the literature. Afterwards, the Mg2+ ion in chlorophyll was replaced by metal ions (either Zn2+ or Cu2l to prepare Zn-chlorophyll or Cu-chlorophyll, respectively which were then used in DSC devices that achieved efficiency of 0.93% and 0.30%, respectively. The extract of spinach was separated by two techniques, column chromatography or preparative TLC. The separated pigments which included chlorophyll-a, chlorophyll-b, carotene and xanthophylls were characterized by colour, TLC, DV -Vis spectroscopy and HPLC, and then were introduced to manufacture bio-photovoltaic cells that recorded 0.14,0.09,0.15 and 0.18%, respectively. Chlorophyll and N719 dye were used as co-sensitizing dyes to manufacture DSC cell. The efficiencies were 1.34% (3.38 mA.cm-2) and 4.31% (10.95 mA.cm-2) using 90/10 and 10/90 v/v of chlorophyl1lN719, respectively compared to 0.92% (2.29 mA.cm-2) and 4.04% (9.98 mA.cm-2) using chlorophyll and N719 dye respectively when DSC photoelectrodes were dyed individually. The second aspect was the development of a new procedure to manufacture Ti02 photoelectrodes at low temperature (300·C) by adding metal peroxides to P25 paste. The films were characterized by TGA, XRD, BET, UV-Vis spectroscopy and dye adsorption studies. A typical cell that used N719 dye and ZnOiP25 sintered at 300°C showed efficiency of 3.94% that increased to 4.57% after the sinteri.~g at 300°C followed by UV treatment compared to cell used P25 sintered at 450°C that showed efficiency of 3.23% or 3.63% after the sintering at 450°C followed by UV treatment. Zn021P25 films made using the same conditions (sintering at 300°C followed by DV treatment) were used to manufacture bio-photovoltaic cell with chlorophyll dye and achieving efficiency of 0.64%. The last aspect for this study focused on development of flexible solar cells. Photoelectrodes were prepared using ITO-plastic substrates instead of FTO glass substrates were prepared by UV treatment and with or without sintering at 120°C. The best efficiencies for these devices were 3.24% and 0.18% when using N719 or chlorophyll as sensitizers, respectively.

This thesis concentrates on the development and synthesis of new metal-containing phthalocyanine and metal-free organic dyes for dye-sensitized solar cells (DSC). In this thesis attempts have been made to cover a broad region of visible light through the synthesis of three different dye families. The N719 is the common dye was used as a sensitizer in DSC devices, which absorbs at 450-600 nm, while in this thesis were synthesized and developed three new types of dyes to work either side of N719 absorb light at (400-450) run for yellow and red single or di-linker dyes, cyanine and phthalocyanine dyes which absorb higher than 600 run. This thesis consists of six chapters. Chapter one includes a short history and introduction to dye-sensitized solar cells with a description of triarylamine, phthalocyanine and cyanine dyes, which are related to this thesis work.

Microbial fuel cells offer an efficient and environmentally-friendly method of producing electricity and as such are an attractive green energy source especially as they can potentially produce power whilst recycling waste. The first objective of this study was to test the possibility of generating electricity with Acidiphilium SJH bacteria operating at a low pH as biocatalysts, with the ferric ion as the electron shuttle and glucose as the electron donor in a two-compartment microbial fuel cell. This study is focused on a comparison between different microbial fuel cell designs that were constructed to test their energy performances. The resulting power densities ranged from 18.3 mW/m2 to 25 mW/m2 and the coulombic efficiency based on the contained substrates is in the range of 6 % to 7 %. Unfortunately the design of microbial fuel cells and scale-up is limited by the large cost of the platinum electrodes. Hence the electrode material used in the design is an important parameter when deciding the performance and cost effectiveness of microbial fuel cell. This work demonstrates a potentially large reduction in cost by utilising the catalytic activity of platinum nano-sized particles on a Ketjen Black cathode that is able to diffuse oxygen from the air, eliminating the need for an external oxygen supply. The low pH redox behaviour of the ferric ion has been paired with an iron-reducing Acidiphilium sp. to form an effective fuel cell. At room temperature a power output of 20.7 m W/m2 was achieved with nano particulate platinum loading of 150 μg Icm2 within a Ketjen Black cathode. The modified cathode retained an equivalent of 80 % efficiency when compared to a solid platinum electrode; which is significant considering that the mass of platinum used in the modified electrode was only 0.1 % of that in a solid platinum electrode. Platinum nanoparticles were electrodeposited on carbon felt from an aqueous electrolyte containing hydrogen hexachloroplatinate by a potential cycling method. The modified Pt/KB cathode achieved higher power density when compared with the platinum electrodeposition on the carbon felt cathode electrode.

This thesis involves studies of dye sensitization of dye-sensitized solar cell (DSC) devices using ultra-fast dyeing and ultra-fast desorption. The work includes studies of adsorption isotherms, uptake kinetics and the development of a new method for dye adsorption, desorption and re-dyeing. The development of a new method of adsorption, desorption and re-dyeing of devices using different desorption solutions with the aim of developing precise dye loading control for different sensitizers. Initially the adsorption of the Ru(II) complex (N719) and the organic dye (SQl) have been studied on Ti02 films and the data modelled using Langmuir and Freundlich isotherms. The adsorption data were best represented by the Langmuir model for N719 and by the Freundlich model for SQ1. A new method of ultra-fast dyeing, desorption and re-dyeing has been developed which enables much greater control over dye loading than is possible by passive dyeing. It has been shown that one device can be dyed, desorbed and re-dyed use more than ten times giving the similar performance to the first dyeing. Different alkaline solutions have been tested for desorbing N719 from Ti02 such as LiOH, NaOH, KOH, BU4NOH and tris( hydoxymethy)ethylamine prior to device re-dyeing. Ultra-fast desorption by BU4NOH and re-dyeing with the same dyes and also with different dyes has been successfully achieved. The method has been developed to control dye loading by partial dye removal using varying volumes or concentration of BU4NOH. A new procedure for the selective removal of dyes has also been developed; N719 by LiOH, SQl by dilute BU4NOH and D149 by concentrated BU4NOH followed by acetone and ethanol. This method has been used to change dyes on the surface and also to quantify dye adsorption in DSC devices. Ultra-fast co-sensitization of Ti02 with more than two dyes (N719 plus various organic dyes) using sequential or multiple dyeing on P25 and commercial DSL18NR-T Ti02 films have been also studied. Sequential ultra-fast co-sensitization with new yellow triphenylamine dye (YD) and N719 yielded η 7.5% which is higher than the individual dyes. Multiple dyeing from a mixed 6% SQ1:N719 solutions gave η 7.1 % which is also higher than for the corresponding individual dyes. The best ratio for mixing N719: D149 is 1:3 v/v which yielded η = 8.2%. Co-sensitization with three dyes and four dyes has been also studied and the devices show improved. efficiencies compared to the respective individual dyes. The rates of adsorption of dyes from mixed dye solutions were studied on Ti02 using the selective desorption methods developed in chapter three. The kinetics of the adsorption of yellow triphenylamine dye (YD) were studied using ultra-fast and passive dyeing. The results show that adsorption of YD by passive dyeing follows a pseudo second order kinetic model with a rate constant of 9.8 x 10-5 cm2.μg-l .min-1 with the Ti02 surface reaching saturation in ca. 350 min. However, ultra-fast dyed YD followed a pseudo-first order model with a rate constant of 11.16 x 10-2 min-l and the surface was reached saturation in 10 min. The experimental data for the ultra-fast co-adsorption of mixed YD: N719 solutions shows YD data can be modelled by both pseudo first order and pseudo second order models but that N719 best fitted with a pseudo first order model. The kinetics adsorption of mixed 5% SQl:N719 solutions also were studied and the results show both dyes followed both pseudo-first order and pseudo second order models. The effect of dyeing time on the IV device data have also been studied showing that efficiency and photo-current increased with increasing dye loading presumably reflecting higher electron injection into the Ti02 conduction band.

The aim of this Ph.D. is to develop and evaluate a compact 'fast response' hydrocarbon fuel processor with integrated control software and novel design concepts for use with both stationary and transportation applications using PEM fuel cells. A multi-function compact chemical reactor designed for hydrocarbon steam reforming was evaluated. The reactor design is based on diffusion bonded laminate micro-channel heat exchanger technology. The reactor consists of a combustor layer, which is sandwiched between two steam reforming layers. Between the two function layers, a temperature monitoring and control layer is placed, which is designed to locate the temperature sensors. The combustor layer has four individually controlled combustion zones each connected to a separate fuel supply. The reactor design offers the potential to accurately control the temperature distribution along the length of the reactor using closed loop temperature control. The experimental results show that the variance of temperature along the reactor is negligible. The conversion efficiency of the combustor layer is approximately 90 to 100%. The heat transfer efficiency from combustion layer to reforming layers is 65% to 85% at 600°C and 400°C, respectively. A sulphur tolerant catalyst, designed for use w1th LPG, was washcoated on to the reforming layers. The reformer was tested over a wide range of reactor temperatures, steam to carbon ratios and fuel flow rates. To increase the reformer performance a second nickel-based catalyst was added to the rear of the reformer. The multi-zoned combustor enabled the two catalysts to be operated at differing temperatures as required. The reformer was tested over a further range of operatmg temperatures, steam to carbon ratios and feed rates whilst using the fuels, LPG, C3Hs and CH4 The performance of the reformer whilst using C3Hs and LPG showed good agreement suggesting that the perfonnance of the reformer was not adversely affected by the presence of sulphur in the fuel. 98% conversion of C3H8 was achieved at a predicted fuel cell power output of 1.98kWe.

This thesis compares the performance of 5- and 3-phase PM generators connected to a diode bridge rectifier under normal and open-circuit failure conditions. Also it describes the design of 5- and 3-phase prototype PM generators with the same volume and rated speed. The permanent magnet generator has advantages such as: simple construction, no excitation field winding, low maintenance cost. The advantages of using diode bridge rectifiers are simplicity and cost. A simulation model is developed for 5- and 3-phase systems that includes the generator self- and mutual-inductance and phase resistance. The developed model demonstrates the effect that both self- and mutual-inductance have on the 5-phase system including an important reduction in the shaft torque ripple. The 5-phase system displays considerably lower peak-to-peak shaft torque ripple compared to three-phase system. Also it is shown that the five-phase system can use a lower value of capacitance for the same output voltage ripple. In addition, the 5-phase system requires diodes with lower current ratings compared to the 3-phase system. The operation and performance of the 5- and 3-phase systems under open-circuit phase failure is assessed and discussed. It is shown that in terms of shaft torque ripple the 5-phase system has a performance superior to the 3-phase system. With two open-circuit phase failures, the 5-phase system has adjacent and non-adjacent open-circuit failure modes. Non-adjacent failures are shown to produce a less extreme operating condition compared to adjacent phase failures in terms of torque ripple and dc output voltage ripple. The rms current in the dc link capacitor is discussed for the 5-phase and 3-phase systems under normal and failure conditions. If, under normal conditions, the capacitor is specified to give the same output voltage ripple in the 5- and 3-phase system, then during open-circuit failure, the 5-phase system displays a larger per-unit increase in rms current in the dc link capacitor compared to the 3-phase system. For systems making use of the fault tolerance of the 5-phase generator, the specification of the dc link capacitor becomes driven by the rms current during the fault. Simulation and FEA results are verified by experiments on practical 5- and 3-phase prototype generators. Good agreement is observed.