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Studies assessing the electricity generation cost of various power generating technologies are becoming increasingly common and references to such studies can often be heard in the public debate. Different studies do however often present significantly different results. This is a problem as electricity generation cost assessments are important when it comes to choosing and designing future energy systems. In this thesis, existing electricity generation cost assessments are reviewed and issues and differences with current methodologies are investigated. As many of the reviewed studies lack detailed sensitivity analyses, an electricity generation cost model has been implemented in order to shed some light on the sensitivity in the produced results. The thesis shows that different methodological approaches and assumptions have a significant impact on electricity generation cost results. The habit of generalising electricity generation costs in a public context can also be questioned. Generation costs tend to be site-specific and sensitive to changes in input parameters. Another finding is that current methodologies are not suitable for comparing intermittent and dispatchable power generating technologies. The reasons are missing electricity system cost perspective and failure to account for differences in production profiles.

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Research to date has highlighted a number of conditions where dropwise condensation may offer heat transfer enhancements over filmwise condensation. Previous studies have shown at pressures above or around atmospheric, dropwise condensation offers significant benefit over filmwise. However, some of this research suggests that as the system pressure is reduced below atmospheric, the benefits of dropwise condensation diminish rapidly, to the extent that, at pressures around 50mbar the benefits of dropwise over filmwise are minimal. This thesis details a series of experiments which were conducted to investigate the heat transfer and pressure drop distributions in tube bundles during both dropwise and filmwise condensation of steam. The primary objective of the work was to determine the design implications associated with switching the mode of condensation of a electricity generating steam turbine condenser from the current filmwise mode, to dropwise. Experimental data were obtained from a new purpose build apparatus containing seventy-five, 150mm long titanium tubes, arranged in an in line configuration of five columns and fifteen rows. Dropwise and filmwise data were recorded from each row at test cell inlet pressures down to 50mbar using both pure steam and steam air mixtures. Filmwise heat transfer data indicated that, under most conditions, heat transfer coefficients were generally in agreement with those obtained by previous workers. Heat transfer data obtained during dropwise condensation suggested that the benefits of dropwise condensation are not significantly diminished at low pressure, and that, unlike filmwise condensation, inundation has little or no effect in a fifteen row bundle. The data also indicated that the pressure drop characteristics and effects of air are, within experimental error, identical during both modes of condensation and in line with models and theories proposed by previous workers.

MBL 3 Research Report / This study investigated the economic significance of using bagasse as a source of raw material for pulp and paper manufacturing. The study also compared this issue with the currently undergoing practices of cogeneration, where bagasse is burnt in the sugar mill boilers to produce steam and generate electricity.

Rural electrification has long been the most important topic on the development agenda of many countries. The needs for power supplies to rural areas increased significantly in the past decades. Extending electricity grids to rural areas is of a very high initial cost and is not viable economically. Micro hydroelectric power plants provide a good economical solution, which is also environmentally very friendly. The current study concentrates on selecting and optimizing a suitable cross-flow micro-turbine to be used in micro hydroelectric power plants. Cross-flow turbines are in general of simple structure, low cost, easy to fabricate and of modest efficiency. The main purpose of the present work is to optimize the performance of a selected turbine by establishing the optimal turbine’s design parameters. A complete analysis of the internal flow, which is of turbulent, two-phase and three dimensional in nature, was undertaken by simulating it using various CFD simulation codes. This study reports on the flow simulation using ANSYS CFX with a two-phase flow model, water-air free surface model and shear stress transport (SST) turbulence model. Prediction velocity and pressure fields of inside the turbine are, subsequently, used to characterize the turbine performance for different geometric parameters including the number of runner blades, the angle of attack, the ratio of inner to outer diameter, the nozzle profile, the blade profile, the nozzle throat width, the nozzle to runner blades width and the runner blades width to outer runner diameter. The results revealed the highly complex nature of the flow and provided a very good insight to the flow structure and performance optimization parameters.

MBL 3 Research Report / This study investigated the economic significance of using bagasse as a source of raw material for pulp and paper manufacturing. The study also compared this issue with the currently undergoing practices of cogeneration, where bagasse is burnt in the sugar mill boilers to produce steam and generate electricity.