Thermodynamic Simulation of a Small Power Plant Equipped with Solar Brayton Cycle (SBC) Combined with an Organic Rankine Cycle (ORC)

One of the latest technologies in the field of small thermal power plants is the combination of the solar Brayton cycle and organic Rankine cycle. These power plants have advantages such as preserving natural resources, reducing emissions, reducing fuel costs, and increasing efficiency. Consequently, these power plants contribute to sustainable development goals by producing clean energy. In this study, the thermodynamic analysis of a small power plant equipped with a Solar Brayton Cycle (SBC) combined with an Organic Rankine Cycle (ORC) is performed with the THERMOFLEX code. In such a power plant, solar energy is used to preheat the air entering the combustion chamber in the Brayton cycle. Also, the heat in the exhaust air from the Brayton cycle turbine is used to drive the organic Rankine cycle (ORC). The results from thermodynamic simulations showed that the expansion power of the gas turbine in the Brayton cycle and the steam turbine in the ORC cycle are 98.91 kW and 8.11 kW, respectively. Also, the electrical power produced by the generators connected to these turbines is 37.82 kW and 7.24 kW respectively. The total electrical efficiency of the power plant was calculated as 24.25%. This efficiency value was obtained in the condition that the solar input power is 64.67 kW and the combustion chamber heating power is 116.7 kW. In Brayton cycle modeling, the compressor pressure ratio was considered to be 4.3. By increasing the compressor pressure ratio up to 7.6, the efficiency of the power plant increased, and with a further increase in the pressure ratio, the efficiency had a decreasing trend.