Testing and modeling of direct steam generating parabolic trough collectors

The present work is elaborated in the framework of the REELCOOP research project. A mini hybrid (solar/biomass) power plant was installed and is under testing at ENIT (Ecole Nationale d’Ingenieurs de Tunis), Tunisia. The power plant relies on Parabolic Trough Collectors (PTC) operating with Direct Steam Generation (DSG), an Organic Rankine Cycle (ORC) for power generation, and a boiler as a backup system. A general numerical model is developed to predict the thermal behavior of the two-phase flow in the PTC collector. The model is validated against experimental results carried out in DISS test facility and good agreement is found between the numerical and experimental results. The model is then used to investigate the performances of a PTC using hot water under Tunisian climatic conditions. Preliminary tests of the REELCOOP installation were performed for solar only mode on August 2017 and the DSG was successfully demonstrated. The test results showed that the plant is able to produce steam up to 176°C.