Performance Investigation of Solar ORC Using Di ff erent Nanofluids

: A parabolic solar dish concentrator, as the heat source of an organic Rankine cycle (ORC), can be used for power generation. Di ff erent types of tubular cavity receivers with di ff erent nanofluids can be considered for use in the solar dish collector to improve its e ffi ciency. In the current research, an ORC with three di ff erent cavity receivers including hemispherical, cubical, and cylindrical are investigated using three nanofluids: Al 2 O 3 / oil, CuO / oil, and SiO 2 / oil. A numerical model is validated using experimental data. The ORC analysis is done for a constant evaporator pressure of 2.5 MPa, and condenser temperature of 38 ◦ C. Methanol is employed as the ORC’s working fluid and a non-regenerative, ideal ORC system with di ff erent turbine inlet temperatures is considered. Furthermore, a fixed solar heat transfer fluid flow rate of 60 mL / s and dish diameter of 1.9 m is investigated. Results show that, compared to pure oil, the thermal e ffi ciency of the cavity receivers increases slightly, and the pressure drop increases with the application of nanofluids. Furthermore, results show that the cubical cavity receiver, using oil / Al 2 O 3 nanofluid, is the most e ffi cient choice for application as the investigated solar ORC’s heat source. 2.5 MPa, and a condenser temperature of 38 ◦ C. Methanol was considered as the ORC working fluid. A fixed solar heat transfer fluid mass flow rate of 60 mL / s and dish diameter of 1.9 m was investigated. Results showed that the working fluid outlet temperature, and thermal e ffi ciency is the highest for the cubical cavity receiver. Also, the total irreversibility rate of the ORC, the ORC mass flow rate, and the ORC overall e ffi ciency are the highest for the cubical cavity receiver. Furthermore, it was shown that the total irreversibility rate of the three cavity receivers investigated is increased by increasing the TIT of the ORC system. Results showed that the pressure drop through the cavity receivers was increased by the application of nanofluids. For all three cavity receivers, di ff erent thermal parameters were insignificantly increased with the application of nanofluids. Further improvements are recommended based on the optimization of variables, such as the mass flow rate, fixed in this work. The application of the SiO 2 / oil nanofluid had the lowest e ff ect on improving the ORC performance. The cubical cavity receiver, using oil / Al 2 O 3 , was found to be the most e ffi cient choice for application as the investigated solar ORC’s heat source. Finally, the thermal e ffi ciency improved with about 2%–3% using the application of Al 2 O 3 / oil or CuO / oil nanofluid with higher nanofluid concentration as the solar ORC system’s working fluid.