A Master of Science thesis in Mechanical Engineering by Mohammed Fouad Azfar Khan entitled, “Thermo-Economic Analysis of Organic Rankine Power Cycles Using Parabolic Trough Solar Technology”, submitted in December 2018. Thesis advisor is Dr. Mohamed Gadalla. Soft and hard copy available.
Abstract
Diversifying into several renewable energy resources has become the goal for many countries striving for a sustainable future. Solar energy is currently one of the most reliable and abundant renewable resource that can be harnessed especially in the United Arab Emirates (UAE). Concentrated Solar Power (CSP) is currently the foremost solar technology able to convert solar radiation to useful heat energy. An Organic Rankine Cycle (ORC) is a variation to the Conventional Rankine Cycle (CRC), where the working fluid used is an organic fluid, which gives several advantages to the ORC such as a low turbine inlet temperature and the absence of moisture content in inlet fluid flow to the turbine, thus increasing plant life. A Regenerative Organic Rankine Cycle (RORC) is proposed to further improve the overall efficiency of the power block. The Parabolic Trough Solar Collector (PTSC) is one of the techniques used in collecting solar energy by concentrating the heat via highly deflective material to a pipe containing a heat transfer fluid (HTF). Thermal Energy Storage (TES) systems are integrated to store thermal energy, which can then be released when required based on the energy demand. Although TES increases the capital cost, it allows CSP to run during night hours to increase the solar share. This in turn improves the feasibility of the integrated system and further reduces carbon emissions. The Integrated Solar Organic Regenerative Rankine Cycle (ISORRC) with thermal energy storage is analyzed using thermodynamic and economic models. In this thesis, a 1 MWe output from the ORC is powered solely by solar energy from the PTSC, and the integrated system is then analyzed for TES with 0, 5 and 8 hours of operation to meet energy demands in rural areas and communities. The optimum fluid for the ORC cycle was found to be cyclopentane based on thermal efficiency and exergetic efficiency analyses. Hitec salt was found to be the optimum molten salt to be used for the TES system. Therminol VP-1 was found to be the optimum heating fluid for the PTSC system. It was concluded that the ISORRC, with 8 operating hours of TES, provides the best thermo-economic system to be implemented in UAE, providing a Levelized Cost of Electricity (LCOE) of 3.59 ¢/kWh and producing annual energy of 4,183,339 kWh.