Seasonal thermodynamic prediction of the performance of a hybrid solar gas-turbine power plant

•A thermodynamic model for a solar hybrid gas turbine power plant is presented.•Variable conditions for solar irradiance and ambient temperature are considered.•Hybridization intends to get a stable power, independent of solar irradiance.•Numerical parameters are taken from an experimental plant in Spain.•Efficiency in hourly basis for days representative of each season is presented.

An entirely thermodynamic model is developed for predicting the performance records of a solar hybrid gas turbine power plant with variable irradiance and ambient temperature conditions. The model considers a serial solar hybridization in those periods when solar irradiance is high enough. A combustion chamber allows to maintain an approximately constant inlet temperature in the turbine ensuring a stable power output. The overall plant thermal efficiency is written as a combination of the thermal efficiencies of the involved subsystems and the required heat exchangers. Numerical values of model input parameters are taken from a central tower installation recently developed near Seville, Spain. Real data for irradiance and external temperature are taken in hourly terms. The curves of several variables are obtained for representative days of all seasons: overall plant efficiency, solar subsystem efficiency, solar share, fuel conversion rate, and power output. The fuel consumption assuming natural gas fueling is calculated and the reduction in greenhouse emissions is discussed. 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.

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