Enhancement of domestic solar photovoltaic unit productivity through the use of a cost effective tracking system
- Authors: Cawood, John Henry
- Date: 2021-04
- Subjects: Photovoltaic power systems , Tracking (Engineering)
- Language: English
- Type: Doctoral's theses , text
- Identifier: http://hdl.handle.net/10948/59215 , vital:60313
- Description: The majority of new and existing small photovoltaic (PV) installations in South Africa are fixed-panel systems, largely due to the cost of photovoltaic panel components having reduced steadily in recent years where an increased requirement is met with a larger number of panels, whilst tracking system costs remain prohibitively expensive. Fixed installations realise only a part of their energy potential as they are truly effective for only short periods of the day. The aim of this study is to investigate and build on the current technology of PV tracking systems with the aim of specifying a simple control and actuation system which performs the tracking function. The eventual purpose of this thesis is to reliably produce more energy from solar photovoltaic installations than similar installations using fixed panels. This would be achieved by the use of an effective and affordable tracking system which yields acceptable accuracy and reliability and opens the potential for the system to be further developed for other purposes. These alternative uses could be the control of sunlight into green buildings, control of dampers for building ventilation and cooling and Trombe wall air control. This study has investigated the potential of several passive and active methods to actuate a sun tracking system. A useful closed loop system, which uses low pressure hydraulics, was developed and tested. The prototype is detailed in the drawings, Appendix D. , Thesis (PhD) -- Faculty of Engineering, the Built Environment, and Technology, 2021
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- Date Issued: 2021-04
Potable water production from atmospheric vapour using an ejector evacuated solar powered refrigeration system
- Authors: Cawood, John Henry
- Date: 2018
- Subjects: Solar energy , Solar radiation
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/23481 , vital:30567
- Description: This research project explores the possibility of using solar radiation energy to produce safe liquid water through the condensation of atmospheric water vapour for human consumption, livestock watering and also for small scale high value crop irrigation. The research activities are comprised of a literature study, comparison of similar devices in use, a design and prototyping exercise, a measure of development work to enhance the performance of the prototype and testing in Al-Batinah province in the Sultanate of Oman, where the author is currently on a work assignment. This dissertation describes the research activities performed to answer the following question: ‘Is it possible to economically produce sufficient quantities of liquid water from atmospheric vapour using only heat energy from the sun?’ This question poses a further two questions which need to be answered in the literature study. These are: ‘What is an economical price for clean drinking water?’ and ‘What is a sufficient quantity of water?’ The purpose of producing liquid water from atmospheric water vapour is an attempt to develop the technology to harvest an alternative and almost inexhaustible water source. The reason for requiring a new source of water is due to the fact that the available fresh water resources of the world are diminishing due to pollution, extensive utilisation and salination. Several references indicate that the problem is compounding itself due the increasing demand on a diminishing resource, with deepening negative effects on agriculture1, health2, economy3, industry and lifestyle4. Many future scenarios depict clean water as a scarce and expensive commodity, unaffordable to many. The condensation of atmospheric vapour is not a new concept. The literature study explores historical attempts to achieve this, as well as detailing the shortcomings of contemporary vapour condensation units as the modern state of the art. This survey covers the spectrum from large versions deployed by military and remote area construction operations to produce water for all purposes, to small desktop electrical water producing machines. The focus of the research is on a more environmentally conscious process, attempting to use a simple ejector driven device with sunshine as the energy source and water as the refrigerant. A further environmental enhancement of the concept is that of designing the machine to last for an extremely long working life, thereby diluting the carbon footprint of manufacture over a great number of years. A portion of the research is devoted to the development of a basic model which takes into account the climatic and meteorological variables to accurately predict a water harvest. The development of the model is then used to optimise the process, narrow the variability of assumptions and assist with the design. The model also serves to predict the performance of the unit in other locations under different prevailing climatic conditions. A design specification and a prototype are produced and tested. Finally the design is scrutinised using value engineering principles to reduce cost, effort and environmental impact and also to reduce the overall cost to provide a more economically viable appliance. The prototype device used in this study will use a collector area of 1 square meter, roughly equivalent to 1000 Watts of solar power under ideal conditions.
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- Date Issued: 2018