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Amos Madhlopa  - - - 
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Distribution of Articles published per year 
(2016 - 2018)
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3
 
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BOOK-CHAPTER 0 Reads 0 Citations Design and Testing of Solar Gas Turbines Amos Madhlopa Published: 01 January 2018
Green Energy and Technology, doi: 10.1007/978-3-319-68388-1_7
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System design and testing are important processes in the development of any technology. Usually, it is desirable to theoretically optimize the design of a solar gas turbine (SGT). Based on simulation results, a real SGT system can be constructed and tested. At present, prototyping of SGTs is based on modification of the existing conventional gas turbine engines. A review of previous work shows that there is a deficiency in Standards for testing of concentrating solar power technologies. Some initiatives are under way to bridge this gap, which may also facilitate the development of relevant standards for testing SGTs. A limited number of projects have been implemented to test the performance of SGTs. Most of these projects are at demonstration scale, and there is lack of commercial-scale SGT power plants. Some challenges to the development of the SGT technology have been presented and discussed.
BOOK-CHAPTER 0 Reads 0 Citations Thermodynamic Cycles of Solar Gas Turbines Amos Madhlopa Published: 01 January 2018
Green Energy and Technology, doi: 10.1007/978-3-319-68388-1_5
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Thermodynamic cycles play a vital role in the development of solar gas turbines. Currently, the Rankine cycle is the most-widely exploited engine cycle in concentrating solar power (CSP) technology. However, this cycle exhibits high loss of low grade heat at the condenser. In view of this limitation, researchers are paying attention to gas cycles. The Brayton cycle (gas turbine) is a good candidate for solarisation because it has a higher thermodynamic efficiency than the Rankine cycle. Based on flow path, gas turbines are classified into three basic types: (a) closed cycle gas turbine (CLCGT), (b) open cycle gas turbine (OCGT) and (c) semi-closed cycle gas turbine (SCLCGT). It is also possible to combine the Brayton cycle with a bottoming cycle such as the Rankine cycle to yield a combined cycle which is advanced with high thermodynamic efficiency (>50%). Many studies have examined the solarisation of the CLCGT and OCGT systems. In spite of the environmental and other potential benefits of the SCLCGT, integration of this cycle with the CSP technology is scarce. So, a conceptual semi-closed cycle solar gas turbine (SCLCSGT) has been proposed in this book.
BOOK-CHAPTER 0 Reads 0 Citations Configurations of Solar Gas Turbines Amos Madhlopa Published: 01 January 2018
Green Energy and Technology, doi: 10.1007/978-3-319-68388-1_6
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Components of a gas turbine can be assembled together in many ways, thereby yielding a wide variety of system configurations. It is possible to use multiple units of each type of component (such as compressor, combustor, turbine and shaft). The configuration of a gas turbine, which is also influenced by the intended application, affects the optimal performance of the system. This flexibility in gas turbine configuration provides a good opportunity for the development of the solar gas turbine (SGT) technology. Major configurations of SGTs can be generally classified into solar-only or hybrid categories. Recovery of heat from the exhaust helps to augment the efficiency of the power plant. In this vein, a review of the literature shows that both recuperative and regenerative types of heat exchangers were used on the exit side of the turbine in previous work. Based on the theory of heat exchangers, it is shown in this chapter that recuperative exchangers are most suitable for heat recovery downstream of the turbine. Hybridization and inclusion of a thermal storage unit enhance the performance of SGTs.
BOOK-CHAPTER 0 Reads 0 Citations Economic Performance of Solar Gas Turbines Amos Madhlopa Published: 01 January 2018
Green Energy and Technology, doi: 10.1007/978-3-319-68388-1_8
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Usually, decision-making about project development is influenced by the costs and benefits over the lifetime of a project. Costs and benefits of a project can be analyzed using several methods, which fall into two groups: (a) methods without time value and (b) those with time value of money. Two widespread indicators of methods without time value are payback period and average rate of return on investment. However, cash flows take place over a certain period of time. Consequently, methods with time value are more relevant, and they include net present value, discounted payback, internal rate of return and levelized cost of energy (LCOE). Some advantages of LCOE over NPV are: (a) the absence of restrictions on project scale, (b) LCOE is independent of energy technologies, and (c) LCOE is applicable even when energy technologies are of different types. Attractive theoretical values of LCOE have been reported (as low as 0.06 US$/kWh) for solar gas turbines (SGTs), which compare very well with LCOE values (0.092-0.095 US$/kWh) for some coal power plants. This indicates that the economic performance of the SGT technology is theoretically approaching parity with conventional thermal power plants.
BOOK-CHAPTER 0 Reads 0 Citations Introduction to Solar Gas Turbines Amos Madhlopa Published: 01 January 2018
Green Energy and Technology, doi: 10.1007/978-3-319-68388-1_1
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Fossil fuels are the main source of primary energy worldwide. Nevertheless, heavy reliance on these fuels is contributing to environmental degradation. In addition, concerns about energy security are arising from the consideration of depletion of the reserves of fossil fuels, fossil price fluctuations, rising competition from evolving consumer countries, political conflicts in areas which are rich in hydrocarbons and high economic impacts which ensue when there is disruption in the energy supply. In this vein, international and national policies are being reviewed to increase the share of renewable energy in the energy mix. A gas turbine engine is one of the technologies which can be driven by renewable energy resources such as solar radiation and biofuels. This engine exhibits higher thermodynamic performance compared to the widely exploited steam cycle. Existing gas turbines are designed to operate on conventional fuels and, therefore, they need modification before solar energy can be integrated on the inlet side of the turbine. Solar radiation can be converted to high-grade heat (up to 1773 K) using concentrating solar power technology. These levels of temperature are suitable for solarisation of the gas turbine system.
BOOK-CHAPTER 0 Reads 0 Citations Main Components of Solar Gas Turbines Amos Madhlopa Published: 01 January 2018
Green Energy and Technology, doi: 10.1007/978-3-319-68388-1_4
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Major components of a solar gas turbine (SGT) for generating electricity are solar field, compressor, combustion chamber (combustor), turbine and generator. The solar field comprises concentrators and receivers. Four widely exploited concentrating solar power (CSP) technologies are the parabolic trough concentrator (PTC), linear Fresnel reflector (LFR), parabolic dish concentrator (PDC) and solar tower (ST). Of all the CSP technologies, the ST system exhibits the highest potential for solarisation of gas turbines. The compressor helps to increase the pressure of the working fluid before it enters the solar receiver (or combustor where combustion of fuel–air mixture proceeds). Pollution control is one of the factors that influence the design of modern combustors. Turbines operate at very high temperatures and so they need to be cooled to avoid overheating and material failure. To enable generation of electricity, an electric generator is linked to a turbine. Many processes take place in a SGT, which require proper control to ensure the right output is obtained at a given time. A detailed discussion of the major gas turbine components has been presented in this chapter. It is shown that the receiver and combustor are critical components in the development of the SGT system.