Design of a solar-driven cogeneration system using flat plate collectors and evacuated tube collectors

The objective of this work is the investigation of a novel solar-driven cogeneration system, which combines both flat plate collectors (FPCs) and evacuated tube collectors (ETCs). This system includes an organic Rankine cycle in order to produce electricity and heat exchangers in order to produce useful heating at 50 degrees C, which is a usual temperature level for domestic applications. The combination of FPCs and ETCs aims to reduce the investment cost and so to design a cost-effective solar-driven cogeneration system. The FPCs are located before the ETCs in order to work at lower temperature levels and the ETC at higher temperature levels, a design which provides optimum compatibility between temperature levels and solar thermal efficiency values. The system is examined energetically, exergetically, and financially. The power production is selected at 5 kW, while the heating production is studied from 5 kW up to 35 kW. According to the final results, it is found that in the typical case of 20-kW heating production, the simple payback period of the system is around 11 years, while the energy and exergy efficiency at 16% and 4%, respectively. The analysis is conducted with a developed model in Engineering Equation Solver under steady-state conditions.