Compartir
Titolo
Multi-stage configurations for central receiver hybrid gas-turbine thermosolar plants
Autor(es)
Soggetto
Thermal energy engineering
Thermosolar gas-turbines
Hybrid plants
Thermodynamic model
Multi-stage gas-turbines
Working fluids
Fecha de publicación
2018
Resumen
[EN]A thermodynamic model for hybrid Brayton thermosolar plants is proposed with the aim to analyze possible
configurations with improved performance. In these plants an array of mirrors with a two-axis tracking system
gathers solar power and redirects it to a central receiver. In turn the receiver acts as a heat exchanger that
heats up a gaseous working fluid that runs a Brayton-like cycle. These plants also include a combustion
chamber that ensures an approximately constant power output even during night or in periods with poor
solar irradiance. Throughout the last years it has been demonstrated by means of experimental projects and
prototypes that this concept is technically feasible but still R+D+i efforts are required in order to reach
commercial feasibility. From the thermodynamic viewpoint it is necessary to increase overall plant efficiency.
The model proposed in this paper is an extension of previous studies from our group that takes into
consideration multi-stage configurations with an arbitrary number of compression steps with intercooling and
expansion stages with reheating between turbines. The model is comprehensive and includes the main
sources of losses in real plants: pressure decays in heat absorption and release, losses in compressors,
turbines and heat exchangers, non-ideal recuperators and, of course, losses in the solar subsystem and
combustion chamber.
A numerical application is done taking as reference the data from the project Solugas, developed by the
Abengoa Solar at the south of Spain. Several plant configurations are analyzed and also different working
fluids checked, including air, nitrogen, carbon dioxide, and helium at subcritical conditions. It is concluded
that for air, nitrogen and carbon dioxide, plant configurations with 2-3 compression/expansion steps are
capable of achieving improved overall plant thermal efficiency (about 25% above single step plants) and also
fuel conversion efficiency, i.e., lead to a considerable increase in power output without an appreciable
increase in fuel consumption.
URI
Aparece en las colecciones