This thesis highlights the benefits to occupants and owners of buildings who utilise daylight effectively. Many cases of absence are related to depression or Seasonal Adjustment Disorder(SAD) which results from inadequate exposure to daylight in the work place. The use of artificial lights has been linked to minor as well as more serious ailments such as cancer and increases in cases of miscarriage. The use of daylight in buildings from economic and environmental perspectives is the main concern of the thesis. The work and analysis of this thesis have produced two new illuminance models. In addition detailed illuminance and irradiance data for Central Scotland were recorded which has previously not been available. A comprehensive study of luminous efficacy research was undertaken in Chapter 3 which evaluated a complete range of models. Furthermore the luminous efficacy of various UK and international sites were compared to examine climatic differences. The development of a new slope illuminance model which more accurately predicts external illuminance for all sky conditions was shown to perform consistently better than previous models. This was due to the new model's treatment of the sky background diffuse component utilising an anisotropic form as opposed to the traditional assumption of an isotropic sky background diffuse component. The availability of sky luminance distribution data from introduction of sky scanners enabled innovative daylight illuminance factors to be developed. These factors model the distribution of the sky's hemisphere under all levels of cloud cover and calculate the internal illuminance taking into account window size, glazing type, orientation and time of the day. The development of the daylight illuminance factors has been shown to significantly improve the energy efficient design of buildings in comparison to the current practice of employing the sky factor method. The daylight illuminance factors were used in a modelled building design scenario to assess their performance and to examine energy efficient design. Lighting controls and various glazing types were analysed to study their impact on a buildings energy consumption. This study also incorporated an embodied energy analysis which considered the energy consumption of windows in manufacture and operation.

The last few years have seen a rapid growth in the number of cars equipped with air-conditioning systems. The space available to fit the system is limited and the under bonnet environment is hostile. Moreover, the depletion of the stratospheric ozone has led to legislation on the phasing out of the chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs ). These substances are used as refrigerants in most refrigeration, heat pump and air-conditioning systems in service today. The aim of this research project was to study existing air-conditioning systems used in automotive applications to develop a model that simulates the components of these systems. This provides a better understanding of the effect of using different refrigerants in the system and its performance. Experimental studies of the performance of the different heat exchanger geometries used provided inputs to the model developed. Automotive air-conditioning condensers and evaporators simulation models were developed and used to compare the performance of these heat exchangers using CFC and HCFC refrigerants and the non-ozone depleting replacements. Thermodynamic properties of the new refrigerants were derived from the equation of state. The evaporator was simulated taking into consideration the mass transfe r associated with the heat transfer in humid conditions. Two types of compact heat exchangers were modelled, round tube with plane fin and plate tube with corrugated fin. These cover most automotive, domestic and industrial applications. The basic performance data of various geometries were determined experimentally. An existing thermal wind tunnel was re-instrumented and modified to improve accuracy at the low air velocities was used in this study. A new data logger linked to a personal computer was used with newly written software to collect and analyse the test data. The results for all geometries tested were correlated and presented in non-dimensional form. The test data were used to determine the effect of various geometrical parameters on the performance for an optimisation of condenser and evaporator designs. The model developed is being used by industrial collaborators for the design of heat exchangers in automotive air-conditioning systems.

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Working fluids for thermal heat pump cycles have been studied. Methanol in conjunction with a mixture of inorganic bromides has been identified as being suitable for transforming heat from temperatures below zero centigrade. A computer programme was written in order to calculate the performance of such a combination, and its accuracy was verified by comparing its predictions with the actual performance of existing (commercial) heat pumps and chillers using combinations other than the above. Transport and other properties of the mixture have been measured, including vapour pressure, specific heat, viscosity, relative density, solubility, thermal conductivity, surface tension, heat of absorption, absorption coefficient, and hence mass diffusivity. An intermittent absorption heat pump was constructed and its performance measured. The tests demonstrated that it was capable of pumping heat from -10 °C up to 74 °C.

The refrigeration energy load in a modern day supermarket makes up a large proportion of the total energy bill. Better design of refrigerated display cases would reduce this load and also have a corresponding effect on the running costs of the refrigeration plant. Further enhancements such as the reduction of air overspill from the case would also influence the aisle temperatures and therefore the comfort levels in the store. This research project uses the technique of computational fluid dynamics (CFD) to investigate the contemporary design of a vertical multideck refrigerated display case. From a two dimensional computational model conclusions were drawn as to the principles of operation of the case. During the course of the project, a custom designed experimental facility was constructed, capable of testing the display case according to the relevant test standards. Using this facility, experimental validation was carried on a number of the design modifications to assess the actual refrigeration load against that predicted by the CFD model. The success of this validation allowed further work into the feasibility of certain design changes by making modifications to the CFD model. The work presented in this thesis makes a contribution to the global effort towards the reduction of the energy consumption by retail refrigeration systems. It does this by showing that possibilities do exist for an improvement in the energy efficiency of multideck refrigerated display cases and that CFD provides a useful tool towards this goal. It also demonstrates the design modifications which proved to yield a saving in energy. These were a reduction in the mass flow rate of air around the case, the inclusion of a honeycomb section on the air curtain outlet of the case the addition of a front upstand and the introduction of a second air curtain thus applying a velocity gradient across the curtain.

Carbon-bonded silicon carbide and clay-bonded graphite crucibles are used in non-ferrous induction melting furnaces. Silicon carbide crucibles especially have encountered premature failure when used at high power densities and operating frequencies. This is thought to be related to their non-uniform properties. To gain a more thorough understanding of the problem, an equivalent circuit analysis has been applied to the composite load of crucible and metal charge.

Buildings represent more than 40% of final global energy consumption, among which 50%-60% of energy consumption is attributed to Heating, Ventilation and Air Conditioning (HVAC) systems. The application of phase change material emulsions (PCMEs) in air conditioning systems is considered to be a potential way of saving energy because with their relatively higher energy storage capacity, they are able to reduce flow rate whilst delivering the same amount of cooling energy. PCMEs can also simultaneously act as cold energy storage to shift peak-load to off-peak time and improve coefficient of performance of systems. However, one of the main barriers affecting the application of PCME is the difficulty in maintaining stability in the emulsions without experiencing any temperature stratification during phase change process. To this end, an innovative energy efficient phase change emulsion has been developed and evaluated. The emulsion (PCE-10) which consists of an organic PCM (RT10) and water has a phase change temperature range of 4-12°C with heat capacity of twice as much as that of water thus making it a good candidate for cooling applications. Particular attention was also paid to the selection of the surfactant blends of Tween60 and Brij52 since they are capable of minimizing the effect of sub-cooling as well as ensuring stability of the emulsion. For the purpose of testing the performance of developed PCE-10 in fin-and-tube heat exchangers, series of theoretical and experimental studies have been carried out to understand the rheological behaviour and heat transfer characteristics of the developed PCE-10 in a fin-and-tube heat exchanger. Both experimental and theoretical results were fairly close and showed that the PCE-10 did enhance the overall heat transfer rate of the heat exchanger. In order to evaluate the potential of the integrated system, whole building energy simulation was carried out with a building simulation code TRNSYS. It was found out that the required volumetric flow rate of PCE-10 was 50% less than that of water which is equivalent to 7% reduction in total energy consumption when providing the same amount of cooling power. Despite its potential in cooling systems, the viscosity of the developed sample was found to be much higher than water which could contribute to high pressure drop in a pumping system. Its thermal conductivity was also found to be about 30% lower than the value for water which could influence heat transfer process. There is therefore the need to enhance these thermophysical properties in any future investigations.

During the summer, buildings in hot dry climates have the inevitable problem of cooling. These climates are characterized by hot summer days with cold nights, a high degree of solar radiation, low humidity and with a nearly fixed seasonal and daily pattern of wind. These natural phenomena could be exploited by nocturnal ventilation to cool the building fabric, thus saving energy during the day and providing comfort at night. The procedures to evaluate thermal performance of buildings with special reference to nocturnal ventilation are studied. Various approaches to building thermal response are first reviewed. Dynamic thermal simulation computer models are developed to predict hourly 'internal temperatures'. These are used to study the various constituents of models. They are based on: -the Admittance Method (as suggested by the CIBSE Guide); -a similar procedure but with higher harmonics; -the Response Factor Method (suggested by ASHRAE); -and the Finite Difference Method. A room surrounded by similar rooms in a multi-storey building, having only one external wall, was simulated in the laboratory. It was subjected to typical variations of a hot climate. Predictions of the computer simulations are compared with laboratory results and it is shown that -the closest agreement was obtained with the Response Factor and Finite Difference methods which are equally good; -for higher rates of ventilation, representation of a room by a simple three nodes model thermal network will give sufficiently accurate results; while for lower rates of ventilation a more detailed model gives more accurate results; -the standard Admittance Method gives adequate results, especially with higher rates of ventilation. It could also be used for hourly temperature-, calculations and variable ventilation without loosing significant accuracy; -a fuller treatment in the Admittance Method of time-lag and time-lead, associated with the dynamic thermal factors, will not greatly improve the results. An increase in the number of harmonics in the procedure did not also result in significant improvements, especially with a high rate of ventilation. Natural ventilation into rooms through open windows in these climates is theoretically investigated. It is shown that the rate of natural air flow obtained may be sufficient to meet the requirements of passive cooling by nocturnal ventilation. A computer program is developed to calculate the rate of air flow in multi-zone buildings, and a new relationship is suggested, which will reduce the complexity of natural air flow calculations in multi-zone buildings subjected to cross ventilation.

The alleviation of heating (in winter), cooling (in summer), artificial lighting and electricity use in office facilities is defined as a bioclimatic trend that offers sustainable building practice through a semi-transparent building integrated photovoltaic thermal envelope as a photovoltaic airflow window system. This thesis aims to produce synthesised design and strategies for the use of a proposed airflow window unit in office building in any given location and to maximise use of the renewable energy. Computational Fluid Dynamics (CFD), namely ANSYS Fluent 14.0, and ECOTECT have been employed to model the mechanical and natural ventilation of an office building integrated with a semi-transparent photovoltaic airflow window and the daylighting impact of various PV transparent degrees (15, 20, 25, 30 and 35 per cent) on the interior space, respectively, for winter and summer conditions. The use of such software has urged to establish a validation analysis a priori in order to ascertain the applicability of the tools to the targeted examination. The validation process involved a comparison of the results of CFD turbulence models, first, against benchmark and, second, against results of literature for identical component. The results of ECOTECT, in terms of daylight factor and illuminance level, were also compared against the results of Daysim/radiance, Troplux and BC/LC found in the literature. Excellent agreement was attained from the comparison of the results with errors less than 10 per cent. The study presents results of modelling of the airflow window system integrated into an office room for energy efficiency and adequate level of thermal and visual comfort. Results have revealed that the combination of mechanical and buoyancy induced flow spreads the heat internally warming the space to be thermally acceptable during the heating season whilst the mechanical convection is a main force for the cooling season. The thermal and visual comfort was compared for different PV airflow window transparent levels to determine the optimum PV transparency for the office space. Moreover, time-dependant and steady state conditions were imposed to predict the thermal and air behaviour for more elaborate investigation. The transient analysis was carried out, in sequential and individual base, according to the solar irradiance of each minute of working period, 8am-4pm (winter) and 5am-7pm (summer). The results obtained from transient and steady state, for both seasons, were compared and revealed negligible impact of transient effect. The PV electricity output was calculated from each transparency level under each condition, summer and winter (transient and steady). The predicted flow patterns, temperature distribution and the daylight factors in the room have been used to determine the most appropriate opening locations, sizes and system specifications for maintaining a comfortable indoor environment. The simulation investigation show that, for the proposed window model, optimum thermal and visual performance can be achieved from the PV transparency level of 20 per cent, during the heating season, and from the PV transmittance of 15 per cent, during the cooling season, where the PV output is highest. However the PV transparencies of 25, 30 and 35% can be reliable under altered conditions of operation.

The focus of this Engineering Doctorate Thesis is the investigation into how the radiant tubes installed in the Continuous Annealing Process Line (CAPL) at Port Talbot steel works were failing and what measures could be taken to improve tube life. Radiant tube replacement and associated maintenance costs were one of CAPL’s biggest annual expenditures, with on average 33 tubes changed every year. Tube longevity was as low as 4 years in the hotter furnace zones, while in comparison, the cooler regions of the furnace had all original tubes still in operation after 12 years of service. A benchmarking process identified that most annealing furnaces were replacing on average 10% of total furnace tubes per year, while tube designs varied according to furnace manufacturer and tube supplier. Segal Galvanising line in Belgium, replaced the least amount at approximately 8.5%, through increasing material grades and subtle design changes Temperature analysis of the furnace at CAPL, highlighted that tube temperatures reached above 1000ºC with differentials of up to 75ºC across tube length in normal operation. Analysis of failed material identified that the tubes had been subjected to excessively high temperatures, which affected the microstructure and properties of the material, resulting in cracking failures at the end of the firing leg. Stress analysis showed that tube life was in the region of 4 years with current designs and maximum temperatures of 1000ºC. Installation of expansion bellows and increasing material grade resulted in longevity of the tube to increase by over double. Improvements have been made to the tube design and material specification throughout the project, with further changes employed in trial tubes, currently in use at CAPL furnace, with the aim of confirming theory discussed in this thesis and improving tube longevity.