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Energetic and Financial Optimization of Solar Heat Industry Process with Parabolic Trough Collectors

The objective of this work is the investigation of a solar heat industry process with parabolic trough solar collectors. The analysis is conducted for the climate conditions of Athens (Greece) and for five load temperature levels (100 °C, 150 °C, 200 °C, 250 °C, and 300 °C). The examined configuration combines parabolic trough solar collectors coupled to a storage tank and an auxiliary heat source for covering the thermal need of 100 kW. The solar thermal system was optimized using the collecting area and the storage tank volume as the optimization variables. There are three different optimization procedures, using different criteria in every case. More specifically, the solar coverage maximization, the net present value maximization, and the payback period minimization are the goals of the three different optimization procedures. Generally, it is found that the payback period is between five and six years, the net present value is between 500–600 k€, and the solar coverage is close to 60%. For the case of the 200 °C temperature level, the optimum design using the net present value criterion indicates 840 m2 of solar collectors coupled to a storage tank of 15.3 m3. The optimization using the solar cover indicates the use of 980 m2 of solar collectors with a tank of 28 m3, while the payback period minimization is found for a 560 m2 collecting area and an 8-m3 storage tank volume. The results of this work can be used for the proper design of solar heat industry process systems with parabolic trough collectors.