The problems of excessive consumption of fossil resources, oil shortages and greenhouse gas emissions are becoming increasingly severe. Research and development work on new methods of thermal energy storage are imminently required. To effectively store seasonal renewable energy, a novel high capacity heat storage system has been designed and evaluated/validated through laboratory experiments and numerical simulations in this research. The system is driven by direct flow evacuated tube solar collector with enhanced PCM tank and intends to be applied in residential and commercial buildings. Theoretical and experimental approaches and numerical analysis have been employed in this study. Firstly, phase change materials (PCM) with specific heat density, melting point, melting and solidifying time have been investigated. This type of PCMs can maintain a considerable high internal temperature of environment chamber in a frozen ambient temperature. Numerical modelling has been conducted on a passive house (Nottingham H.O.U.S.E) to study whether proposed thermochemical materials can cover relative heating load and be power by solar panel in terms of roof size. Meanwhile, PCMs have been used to give a long duration for temperature-controlled chamber in laboratory, and thermochemical materials have been utilized in closed pumping pipe system for cooling and heating purpose. Secondly, characteristic experiments have been conducted on a modified solar collector working with an enhanced PCM tank that is integrated with a fan coil heat exchanger. The results show that light radiation of tungsten lamps (as a solar simulator) has approximately 70% efficiency to equate to solar radiation under the same Pyranometer reading value. At the same time, the solar system can supply over 50°C heating energy and the PCM tank within it can supply higher output temperature with longer duration than water tank. The efficiency of the whole solar collector heating system is over 50% as a heat absorption chamber in sunny days, while only approximately 10% under mostly cloudy weather. Lastly, proposed thermochemical materials (silica gel, calcium chloride, zeolite 13x, vermiculite and activated carbon) have been evaluated on designed thermochemical absorption chamber to supply fresh high temperature air for space heating. The results show that zeolite holds the highest reacted temperature (over 58°C) and vermiculite has really fast absorbing hydration duration, less than half hour. Silica gel possesses the biggest water absorbing capacity and vermiculite has a worse result. A comparison between experimental and numerical modelling results has been revealed. Considering the complexity of processes in cooling and heating system, the agreement of simulation and experimentation is satisfactory, thus the lumped numerical model is acceptable and significant for investigation of this scaled seasonal high capacity heat storage system. A full size seasonal heat storage system with a nominal heating capacity of 3kW has been proposed and illustrated in economic and environmental issues section. The results from net present value (NPV) and internal rate of return (IRR) sensitivity analysis both shows it is greatly attractive to develop this novel system for application in both household and commercial buildings in consideration of its about 9 years payback period, 20 years life span and zero gas (C02) emissions. An intelligent transpired solar collector system is also introduced and illustrated as future work.

Shading louvres on buildings must serve to allow maximum window insolation in winter, while have the prime function of intercepting unwanted direct solar radiation in summer; which could cause excessive solar heat gain, especially in glazed offices and commercial spaces. Studies of the effect of solar protection on heating and cooling loads show that shading strategies are climate dependent. And it is accepted today that solar protection does reduce energy use for cooling, and tends to increase heating loads. The balance between the benefits in cooling and the losses in heating is only achievable by good designs. The main focus of this research work has been in harnessing the thermal energy available within the incident solar radiation intercepted by the shading louvres; hence benefiting, from shading in terms of energy savings, as well as from the collected energy. In achieving this aim, both theoretical and experimental techniques have been utilized, as design analysis tools, in order to select a design that satisfies both the efficiency and cost criteria. A suitable collector design has, then, been identified, its thermal performance characterised, and its prototype manufactured and built. The prototype of the chosen design has been field-tested in Nottingham-England and Porto-Portugal. Finally, the characteristics of the design have been incorporated into a computer simulation scenario, in which a real office building in Winterthur-Switzerland has been analysed for its total (cooling and heating) annual energy consumption. Findings of this research work indicate that these louvres, despite certain geometrical limitations, could act as solar collectors with good energy collection characteristics. And they could contribute with substantial reductions in the overall annual energy consumption resulting from the combined effect of shading and collecting energy. This was found particularly to be the case when the collected energy is made to part-fuel, an adsorption chiller for the purpose of air-conditioning the same building.

X-ray Emission from Low Mass Binary Systems X-ray time-series and spectra of two LMXRBs are presented. The data are from the the well-known X-ray burster MXB1636-536 and the dipping source 4U1624-49. In the case of MXB1636-536, a simultaneous optical observation is also presented. The 2-20 keV persistent X-ray emission from MXB1636-536 is found to show both positive and negative hardness-flux correlations and to vary by a factor of &sim; 2 on timescales of hours. The persistent spectrum is best described by a power law with high energy cut-off, indicative that Comptonization dominates the spectral formation in the inner accretion disk. The temperature, optical depth and Compton y parameter of the Comptonizing plasma are derived; the Compton y parameter shows that the spectrum is consistent with unsaturated Comptonization. The negative hardness-flux correlation is explained in terms of the Compton cooling of a hot neutron star corona as a result of an increase in accretion rate. It is notable that a negative hardness-flux correlation and a power law spectrum is in direct conflict with previous observations of this source. Thirteen X-ray bursts, exhibiting a wide variety of profile, were also observed from MXB1636-536. The peak burst flux and burst fluence varied by a factor of 6 and 5 respectively. The burst sample may be divided into two distinct classes: those with fast rise and high peak intensity (strong) and those with slow rise and low peak intensity (weak). Moreover, the strong bursts are 'super-Eddington' and one of the weak bursts is unusual in that it is double-peaked in both the X-ray and bolometric burst profiles. The observed burst properties are discussed within the framework of the current thermonuclear flash models and other physical scenarios. One of the bursts, observed simultaneously in both the X-ray and optical wavebands, is used to determine the possible locality of the reprocessing region in the accretion disk. 4U1624-49 reveals a pattern of dips in the 1-10 keV X-ray light-curve which repeat with a period of ~21 hours. This is almost certainly the binary period of the system, making it one of the longest binary periods amongst LMXRBs. The &sim;25% residual flux can be associated with a physically extended emission component whereas the dips are associated with the intermittent obscuration of a compact component by material in the line-of-sight. The spectral changes occuring within the dips are complex and indicate energy-independent reductions in flux and substantial increases in absorption. The dips cannot be explained by a bulge at the outer disk edge (at the point of impact with the incoming stream) obscuring the central X-ray source. Assuming the primary of 4U1624-49 is a 1.4M? neutron star, the companion is likely to be an evolved star with a mass < 3M? and radius < 2.75R?. The orbital inclination is found to be within the range predicted by the FKL model for 'pure dippers' i.e. 60° < I < 75°.

Renewable energies are a critical element for reducing greenhouse gases emissions and achieving a sustainable development. Until recently, building integration of renewable sources was focused on solar technologies. Nevertheless,building integrated wind turbines can and must be part of the solution to the global energy challenge. This research investigated the potential of integrating small vertical wind turbines between medium-rise buildings. Wind velocities were measured around 7 fifteenstorey towers. The measurements were carried out for nine different configurations,using a boundary layer wind tunnel and computational fluid dynamics (CFD) simulations. Computed and measured results showed reasonable agreement. The differences were more apparent at ground level. It was established that building orientation and the separation between buildings defines to a great extent the wind environment around buildings. It was found that a distance between buildings of 15 metres and an orientation of θ=260˚ produced the higher augmentation factors. This configuration produced up to 17,812kWh in a typical Nottingham UK year, using six vertical wind turbines of 2.5kW each. Results suggested that the use of CFD as a visualisation tool is extremely useful at design stages in projects involving the integration of wind turbines. Nevertheless, the results of CFD simulations are highly dependent on the type of roughness modification applied to the wall functions, the choice of the turbulence model and the modelling of the inlet wind velocity profile. Because servicing buildings accounts for around half of the UK’s total energy consumption, the need to reduce the consumption of fossil fuels is central to good building design. That is why the architectural practice must respond professionally by delivering buildings that successfully integrate wind energy technologies, which can only be achieved if the designer actively engages with the environmental design principles and improves his understanding of building physics.

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Conventionally the power network operators were obliged to buy all the wind energy generated by wind farms. However, as the penetration of wind energy (or generally any other sort of renewable source) in a power system is increased, the ability of other generators to balance the demand becomes limited. This will necessitate the control of wind turbines in order to generate a given demand power rather than extracting the maximum wind power. This control approach is termed “Power Demand Control” in this thesis. In contrast to Power Demand Control, “Power Smoothing Control” utilizes energy storage systems in order to absorb high frequency wind fluctuations, hence, delivering a smoother version of wind power into the grid/load. The drawback of the Power Smoothing approach is that the average power into the grid/load is still determined by the available wind power rather than the system operator. The Power Demand Control approach, which has received little attention in literatures, is the main focus of this thesis. This research proposes control schemes with and without external energy storage for the Power Demand Control strategy. This thesis studies different possible methods of applying Power Demand Control, in particular the droop control method. It is shown that a droop-controlled wind farm does not need a central “Supervisory wind Farm Control” unit to determine the power demanded from each DFIG. Moreover, a droop-controlled wind farm has the advantage of controlling the local grid voltage and frequency. This means that no external voltage and frequency source is required which makes a droop-controlled wind farm a more suitable option for integration of wind energy at distribution level. The classical droop control is modified in order to make the DFIGs share the demand power not only according to their ratings but also to their associated available wind power. The applications of the control paradigm are discussed, including: integration into microgrids, AC grids and HVDC connection feeders. This work mainly concentrates on microgrid applications. An Energy Management System is proposed in order to keep the energy level of the energy storage (or the DFIG’s shaft speed) within its limits using an Auxiliary Generator and a Dispatchable Load. Different possible system configurations are introduced and their advantages and drawbacks are discussed. It is illustrated through simulation that the proposed control scheme can inherently ride-through a grid fault with no need for communication. Furthermore, it is shown that the control scheme can operate if the wind speed drops to zero. The simulations are carried out using the PSCAD/EMTDC software.