Financial Optimization of a Solar-Driven Organic Rankine Cycle

Abstract

The objective of this work is the financial optimization of a solar-driven organic Rankine cycle. Parabolic trough solar collectors are used as the most mature solar concentrating system and also there is a sensible storage system. The unit is examined for the location of Athens in Greece for operation during the year. The analysis is conducted with a developed dynamic model in the program language FORTRAN. Moreover, a developed thermodynamic model in Engineering Equation Solver has been used in order to determine the nominal efficiency of the cycle. The system is optimized with various financial criteria, as well as with energy criteria. The optimization variables are the collecting area and the storage tank volume, while the nominal power production is selected at 10 kW. According to the final results, the minimum payback period is 8.37 years and it is found for a 160 m2 collecting area and a 14 m3 storage tank, while for the same design point the levelized cost of electricity is minimized at 0.0969 € kWh−1. The maximum net present value is 123 k€ and it is found for a 220-m2 collecting area and a 14-m3 storage tank volume. Moreover, the maximum system energy efficiency is found at 15.38%, and, in this case, the collecting area is 140 m2 and the storage tank volume 12 m3. Lastly, a multi-objective optimization proved that the overall optimum case is for a 160-m2 collecting area and a 14-m3 storage tank.

Investigation of Different Storage Systems for Solar-Driven Organic Rankine Cycle

“…[40]. The proper number of sunny days for Athens [6] was used for every month in order to simulate only the days with the potential of adequate solar direct beam irradiation. The dynamic investigation was done with a homemade model in MATLAB.…”

“…The yearly operating and maintenance cost (K O&M ) is selected to be the 1% of the investment capital cost [6]:…”

“…Among them, PTC seems to be the most developed and mature technology for various scale applications [4]. The most common power block that is combined with PTC is the organic Rankine cycle (ORC) [5] because this cycle uses organic fluid with critical temperatures up to 300 • C, and so these fluids are ideal candidates for oil-based PTC, which operates up to 400 • C [6].…”

“…In the literature, there are various storage techniques. The most usual is the use of a sensible storage tank that can store sensible heat by increasing the temperature of the stored thermal oil [6,9]. An alternative choice is the use of two tanks with molten salts in order to store thermal energy in an efficient way.…”

Investigation of a Novel CO2 Transcritical Organic Rankine Cycle Driven by Parabolic Trough Solar Collectors

“…Moreover, for each month, a proper number of sunny days have been used, as they have been presented in Ref. [44]. More specifically, for the months from January to December, the respective sunny days are the following: 13-10-15-18-20-22-29-29-20-18-17-15.…”