Thermodynamic Simulation of a Hybrid Brayton Thermosolar Plant

Abstract

We present a purely thermodynamic model for the prediction of the performance records of a solar hybrid gas turbine power plant. Variable irradiance and ambient temperature conditions are considered. A serial hybridization is modeled with the objective of keeping an approximately constant turbine inlet temperature, which thus delivers an stable power output. The overall plant thermal efficiency depends on the efficiencies of the involved subsystems and the required heat exchangers in an straightforward analytical way. Numerical values for input parameters are taken from a central tower field recently developed near Seville, Spain. Real data for irradiance and external temperature are taken in hourly terms. The curves of several variables are presented for representative days of all seasons: overall plant efficiency, solar field thermal efficiency, solar share, fuel conversion rate, and power output. The fuel consumption assuming natural gas fueling is estimated, as well as greenhouse emissions. The model can be applied to predict the daily and seasonal evolution of the performance of real installations in terms of a reduced set of parameters. This can contribute to improve the design of this kind of facilities in order to get better performance and so better economical records.