• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 6
  • 2
  • 2
  • Tagged with
  • 134
  • 134
  • 122
  • 121
  • 119
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Modelling dry process cement kilns using acid/alkali mixing technique

Tosunoglu, Melahat January 1984 (has links)
At present, the main cost items associated with cement manufacture are due to the fuel and the electric energy consumed. Reducing the fuel cost can be achieved either by reducing the specific consumption or by using lower grade cheap fuels in the process. One of the simplest and most important methods of reducing the specific consumption is the flame control, which, in addition to saving energy also results in better quality product and steadier kiln operation. By changing the process from wet to suspension preheater dry system, the industry can reduce its fuel consumption up to 50%. Application of precalcining system to these dry process suspension kilns can even further improve the heat transfer conditions in the kiln and the preheater. Precalcining can be achieved either by introducing some proportion of the total heat input into the riser duct connecting the kiln to the preheater or by adding another stage of separate calciner chamber. The advantages obtained by precalcining are several, some of the important ones being increase in production capacity for a given kiln unit, improved kiln lining life, steadier operation, better heat transfer conditions in suspension state for the decarbonation of the material, and the possibility of utilizing lower grade fuels in the secondary firing unit in the calciners. In order to achieve the aim of energy saving, it is essential to have a very good understanding and investigation of the aerodynamics of the furnace, and the effects of the modifications introduced to the system for energy saving purposes, like auxiliary burners. Modelling techniques prove to be very useful in such cases. In this present work, the technique of physical modelling has been chosen and the acid/alkali mixing method has been applied for flow visualization. By comparing the model results concerning the length and behaviour of the flame under different kiln operating conditions with the results of the experiments carried out on the prototype itself by earlier workers, the reliability of the technique and its usefulness in flame studies have been proved. By applying the same technique and flow visualization methods to a 1 :40th scale down geometric model of a suspension preheater kiln with auxiliary firing arrangement, the optimum operating conditions for such systems in case of secondary firing have been determined. It has been established that for the auxiliary firing systems in four-stage cyclone preheaters with combustion air being supplied through the kiln, the proportion of the fuel supplied at the back-end of the kiln in the riser duct should not exceed 30% of the total heat input, the optimum value being 27%. In designing auxiliary burners for such systems, it has also been found that the stream to jet velocity ratios (p) should be in the range 0.62 < p < 0.83 for burners 30&deg; inclined to the horizontal, and 0.41 < p < 0.49 for the burners perpendicular to the stream flow in the riser duct for purpose of having an axisymmetric flame in the riser duct.
112

The effect upon UK energy supply schedules of the use of combined heat and power with district heating

Armson, R. January 1984 (has links)
The widescale use of combined heat and power with district heating will have a significant effect upon the quantities of primary and secondary fuels used in the United Kingdom. A new methodology for investigating the complex technological interactions between supplies and demands for fuels is developed, and the effect of sample CHP/dh scenarios calculated. Particular attention is paid to electricity generation to determine the impact of CHP/dh upon the operation of the merit order.
113

The human dimension of domestic energy use : an integrated approach

Hitchcock, Guy St John January 1992 (has links)
Domestic energy consumption is a multifaceted phenomenon which is dependent on both the social and technical characteristics of domestic households. In this thesis it is argued that such a phenomenon is best understood using an integrated approach, combining both the physical and social theories of energy use. Such an integrated approach is developed with the use of systems theory and focuses on the interaction between the physical and social aspects of the household. This integrated approach is used to analyse UK and US domestic energy consumption patterns and is compared with a purely physical and a purely social analysis. These analyses also highlight the inadequacies of the physical or social approach and demonstrates the difficulty involved in trying to consider both in a single integrated analysis.
114

Telecommunications networks for remote electricity supply metering and load control

Brown, Paul Anthony January 1990 (has links)
The aims and objectives of this thesis are to investigate remote electricity supply metering and load control in terms of the now availble UK Electricity Supply Industry (ESI) private and national telecommunications networks, the intelligent building, the home computer and domestic energy management concepts. This work commences with an overview of private telecommunications systems utilised within the U.K. electricity supply industry together with those network services provided by Public Telecommunications Service Operators (PTO's) for customer access (Chapters 1 and 2). The thesis continues by describing the meter reading and billing processes (Chapter 3) and introduces the concepts of remote metering, the consumer billing interface (Chapters 4 and 5), load control and spot pricing theory (Chapter 6). A review of recent load control and remote metering field trials, conducted in the UK, including feasibility studies are then detailed (Chapter 7). A mathematical analysis of two basic approaches to the principle of 'idle-line' working is also considered (Chapter 7). The 'intelligent home' concept and the customer billing interface are then considered in conjunction with the development of a 'home computer' applications strategy (Chapter 8). The development of text, communications and control simulation on the BBC microcomputer, are then detailed by reference to the 'Adaptive Microprocessor based System for Experimentation in the Transmission of Text' (AMTEXT) developed to test the feasibility of the home computer applications strategy developed in Chapter 8 (Chapter 9). The concept of 'idle-time working is then introduced coupled with the concept of 'integration' by way of the national telecommunications network services. Proposals for a Modular Integrated Data Aquisition System (MIDAS) are then considered as a means of illustrating a practical application of both integration and idle-time working (Chapter 10). The thesis continues by considering network integrity, security and reliability in terms of network architecture and the development of a strategy for quantifying network resilience as a design parameter (Chapter 11). Finally, the thesis concludes by summarisirig the work undertaken and the results obtained with respect to the initial objectives, and details potential areas for further research.
115

Evaluation of the design, construction and operation of a gas fuelled, engine driven heat pump, and its possible role in a UK market

Newport, C. A. January 1983 (has links)
This thesis describes the results of several years work on the design, construction, testing and evaluation of a gas fuelled, engine driven heat pump and its possible role in a future U. K. market. In 1977 a joint venture was embarked upon by the Open University Energy Research Group, Lucas Aerospace and Milton Keynes Development Corporation to design, manufacture and install a gas fuelled heat pump in a rented house, and to monitor its performance in real operating conditions. It was one of a number of projects in the field of heat pump research and development supported by the Department of Energy. Due to a delay in receiving research funds however, and because of the size of the unit, it was impossible to install the system in a suitable property and so it underwent an intensive laboratory test programme simulating various load patterns and operating conditions. The heat pump, using air as its source of heat was driven by a 360 cc single cylinder marine engine converted to run on natural gas. The work was completed in 1980 and the heat pump was found to work well and justified the design assumptions made, after allowing for the poor performance of the engine used. At 6°C (ambient) an output of 14 kW was achieved with an overall efficiency or C. O. P. of 1.1 which compares favourably with a typical seasonal gas boiler efficiency of around 0.65-0.70. As well as giving a full technical description of the heat pump system, plus an analysis of the various individual components, the thesis looks at the historical development of heat pumps generally and briefly considers the applications to which heat pumps can be put in domestic, commercial and industrial markets, and the possible economies this would bring. It concludes by looking at the future work needed in order to achieve these ends.
116

A dynamic physical energy model of the United Kingdom

Barrett, M. A. January 1981 (has links)
This report describes the structure and simulation results of a dynamic physical model of the UK energy system. The model traces the hourly flows of energy from energy sources through various energy converters and stores to useful energy demands. Effects such as the temporal and climatic dependence of demands have been accounted for. Technical data has been collected so that it is possible to simulate the performance of the system as it was in 1976 or as it might be at some future date. The model has been validated against measured data and has been used to simulate the UK system with changed demands and new conservation and supply technologies.
117

Zero energy for the Cyprus house

Serghides, Despina January 1993 (has links)
The thesis aims at the optimization of the regulatory systems inherent in domestic architecture through choice of orientation, building materials and the use of natural resources of energy, to achieve comfort conditions without the need for mechanical heating and cooling for the Cypriot climate. The thesis is classified in six chapters as follows: CHAPTER 1 In this chapter, analysis of the energy situation in Cyprus to investigate the potential for energy saving in houses and the possible environmental improvement is carried out. For this, existing and newly built houses are evaluated to identify deficiencies in the regulatory systems inherent in the built form that result in heating and cooling demands. CHAPTER 2 The prevailing climatic conditions in Cyprus are analyzed, in this chapter, to assess how energy demands for heating and cooling arise in domestic buildings and to evaluate the free energy systems available to contribute to these requirements. Moreover in this chapter standards of comfort for single family detached houses in Cyprus are established, through investigation of current thermostat settings and reviews of thermal comfort studies, so that they may be taken as a basis in the optimization study. CHAPTER 3 This chapter deals with the optimization of a specific house type, to be designed in an ideal environment, to the point of zero fuel consumption for heating and cooling with the aid of microcomputer programmes for thermal analysis. Initially simplified thermal calculations are carried out by using "Method 5000°, a well established method adopted by the Commission of the European Community Handbook. These are followed by detailed hourly simulations of selected variants using dynamic simulation model SERIRES. CHAPTER 4 This chapter also makes use of thermal calculations as chapter 3, and concludes to comparative assessment of results obtained under chapter 3, and design recommendations for new houses through economic analysis of the varied design measures. From those the profile of the "Zero Energy House for Cyprus" is outlined. CHAPTER 5 The study in this chapter identifies the occupants' factors that influence the efficiency of building performance and the thermal environmental conditions of the "Zero Energy House". It analyses the intervention of the occupants in the design, which is reflected in the variable of fenestration. The analysis is carried out interdependently, in various combinations of shading and ventilation profiles, in computer simulations using thermal analysis programme "AGRI". A case-study further investigates the thermal effects of the user interaction with the building and confirms the validity of the simulation results. The proposed strategies, at the end of the chapter, aim at reducing the operational counter-effects on the building design. CHAPTER 6 The conclusions are outlined in the form of criteria for the selection of different design alternatives. These are based on flexibility, operational ease, potential thermal efficiency and elimination of constraints for securing optimal performance for "Zero Energy Houses" for Cyprus.
118

Power system optimisation and stability studies using real-time simulation

Williams, S. K. January 1986 (has links)
No description available.
119

Energy conservation in urban planning : An ecological approach towards the development of more energy efficient urban patterns

Kadi, H. E. January 1988 (has links)
No description available.
120

Investigation of smooth and rough corrugated cooling tower packings in various arrangements

Goshayshi, Hamid Reza January 1999 (has links)
No description available.

Page generated in 0.0423 seconds