Resumo:
Hydroelectricity is the main source of generation in the Brazilian electrical system and due to the hydrological problems observed recently and plans to expand the matrix, the country is looking for alternative energy technologies, such as a concentrated solar power plant and planning to improve the system's efficiency. As an example, the parabolic trough solar plant (PTC) is used to produce electricity and heat simultaneously. The present work develops energy and thermal modeling of a 100 MW PTC plant for the city of Itacarambi-MG. In this work, the performance of the solar collector is improved considering different geometries of internal fins and the use of nanofluids as thermal transfer fluid. For that, nine final cases were proposed, including, smooth tube, rectangular longitudinal fin, triangular longitudinal fin, magnesium oxide nanoparticle (MgO) and silica nanoparticle (SiO2) with 2% volume fraction. Therminol-VP1 is chosen as the heat transfer fluid (HTF) of the system. Through the CFD tool, the main parameters of the problem are evaluated, namely: heat transfer coefficient, friction factor, pressure loss, pumping work, thermal efficiency and collector exergy. The best performance was obtained for the case with rectangular longitudinal fins of size 25 mm and thickness of 4 mm, using 2% MgO nanofluid. For this case, the maximum HTC was 1426.8 W/m² K, while the pressure and friction factor had a percentage increase of 338.56% and 220%, respectively. The maximum thermal efficiency was 72.36% and exergy 32.22%, which represented an improvement of 5.6% and 5.3% in relation to the reference tube. The lowest LCOE obtained ranged from 0.02648 to 0.02746 euro kW/h.
