Investigating waste heat recovery in a thermal power plant using thermoelectric generators
- Authors: Khumalo, Thabiso Sibonelo
- Date: 2020
- Subjects: Thermoelectric generators , Heat recovery
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/480191 , uj:43460
- Description: Abstract: Energy conservation and green technology are most important aspects in all countries around the world. Various technologies have been investigated to address issues such as global warming by reducing the CO2 emissions to the environment. Thermoelectric generators are one of the fastest growing technologies that are being researched all over the world and it has been proven that it is an excellent technology to recover waste heat. The waste heat can be recovered from different industries such as power plants. Transportation power plants (internal combustion engines) and cooking stoves are also potential sources of waste heat. Countries like Japan have invested significant research into thermoelectric generators and have found them to be useful alternative energy sources. It is therefore of great value to investigate the feasibility of employing this technology in Eskom power plants to produce electricity using waste heat from the plant vessels... , M.Ing. (Mechanical Engineering Science)
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Design framework for the development of an efficient heat recovery system in Photovoltaic Modules for the suitability of low-medium temperature applications
- Authors: Maditsi, Koketso
- Date: 2019
- Subjects: Photovoltaic power systems , Heat recovery
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/444961 , uj:38910
- Description: Abstract: Energy regeneration through heat recovery is practically possible for maximizing energy obtained from the sun, by recovering and reusing the heat that is typically lost within energy dependent electrical equipment. Solar thermal systems utilize flat plates or evacuated tube collectors which absorb the heat from the sun. Similarly, Photovoltaic (PV) systems absorb solar irradiation to generate electricity. A combination of both technologies results in Solar Photovoltaic/Thermal (PV/T) systems wherein thermal plates or liquid contained tubes cool PV collectors resulting in increased efficiency. Solar Photovoltaic/Thermal Optimised (PV/TO) is simply a PV/T module with an improved thermal output designed and investigated in this research study. The PV cooling mechanism is important because excessive heat in PV panels generates high resistance, which impedes the performance of the solar cell and in the process, results in lower efficiency. PV/T systems are also known to produce low thermal output which makes them unsuitable for applications already serviced by market-ready solar thermal systems. The study is aimed at developing an efficient and cost effective heat recovery system which has been designed specifically to improve the thermal output without compromising the electrical output of the PV/T module. To achieve this, a survey was conducted to understand the PV/T technology market share compared to other solar technologies. Furthermore, a prototype was developed to investigate the effect of Peltier cooling method on PV cells. Two models (PV/T and PV/TO) were developed using Autodesk Inventor Professional and simulated using Autodesk CFD Simulation. The results from the simulations were then used with support from the mathematical models developed to determine the economic performance study of the two models. The survey results showed that only 11% of the respondents are actively participating in PV/T related matters. The experimental results showed that Peltier cooling improves performance by 1.1% higher than conventional cooling methods. The results from economic performance study showed that PV/TO model can archive over 100% solar fraction for the DHW demand of 800 litres/day using only 4 panels whereas PV/T model for the same demand and panel size archives just under 80% of the solar fraction using 9 panels. The overall results showed that PV/TO model optimise thermal output by over 150% and can compete with market-matured solar thermal technologies. , M.Tech. (Mechanical Engineering)
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Improving three-phase induction machines power factor using single phase auxiliary winding fed by an active power filter
- Authors: Muteba, Mbika C. , Jimoh, Adisa A. , Nicolae, Dan-Valentin
- Date: 2007
- Subjects: Heat recovery , Heat transfer
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/20373 , uj:16089 , ISBN:078038606x , Citation: Muteba, M.C., Jimoh, A.A. & Nicolae, D.V. 2007. Improving three-phase induction machines power factor using single phase auxiliary winding fed by an active power filter, IEEE AFRICON’07, Windhoek, Namibia, 26-28 September 2007:1-7 , DOI:10.1109/AFRCON.2007.4401570
- Description: Abstract: This paper presents a three-phase induction machine that employs a single phase auxiliary winding, which is only magnetically coupled to the stator main winding, and controlled by an active power filter. The active filter consists mainly of a two leg PWM voltage source inverter, which together with the auxiliary winding serves to supply leading reactive power to the machine. With sufficient ampere-turn capability of the auxiliary winding and an adequate control algorithm, the computer simulation results show that it is possible to obtain nearly unity power factor operation at the terminals of the main winding over a range of load conditions including rated load. The simulated power factor of this scheme is compared with the measured result for a typical practical induction motor.
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