Validation of a simulation method for the optical and thermal characterization on small-sized parabolic trough collector for process heat applications

Nowadays, the need for clean energy and energetic dependency has become a critical issue due to global warming caused by the greenhouse effect resulting from the excessive use of fossil fuels, mainly for producing heat in industry (<200 °C). The solar parabolic trough collector, PTC, with one-axis solar tracking is a potential candidate for providing thermal energy to the industry, so contributing to the decarbonisation of this sector. Currently, new commercial products and several prototypes are appearing, but the key components and structure are still the main elements. In this study, one small-sized PTC for industrial solar heat applications has been developed through optical design and thermal modeling. It has been validated by optical measurements and outdoor testing according to international standard ISO 9806. This collector is designed for working up to 200 °C with thermal an overall efficiency about 75 %, following ISO standard. Furthermore, an analytical model for the inspection of solar tracking error has been developed and validated. The optical simulation is conducted through the Monte Carlo ray-tracing technique in Tonatiuh, and the thermal simulation is conducted in CFD. Measurements are conducted in the experimental testing ring in the facilities of CENER (Centro Nacional de Energias Renovables) which is part of its testing laboratory accredited by ENAC, Spanish accreditation body, and recognized by SolarKeyMark in Europe. The simulation and experimental results obtained show a maximum difference of 0.8 %, demonstrating the validity of the models.