modelExercise1GasTurbine

Information

English problem description

A gas turbine features a two-stage compression with intercooling and a recuperator. Ambient air (1.00 bar, 300 K) is first compressed in the adiabatic lowPressureCompressor (eta_is = 0.9) to 3.50 bar. Subsequently, the air is cooled isobarically in the cooler to 320 K before entering the highPressureCompressor, where it is further compressed (eta_is = 0.9) to 10.0 bar.

The compressed air is then preheated in the isobaric heat exchanger recuperatorA using turbine exhaust gases, increasing its temperature to 750 K. In the isobaric combustion chamber, the temperature is raised further to 1400 K. The hot gas expands in the turbine (eta_is = 0.9) down to ambient pressure (1.00 bar). The turbine supplies power to both compressors and the generator, with a mechanical shaft efficiency of eta = 0.970.

Downstream of the turbine, the exhaust gas is cooled isobarically in the heat exchanger recuperatorB. The mass flow rate is assumed constant at 5.80 kg/s, neglecting the contribution of the fuel mass flow.

Possible modifications

The following aspects can be varied for further analysis:

• The medium model:
  • SimpleAir: perfect gas with constant isobaric heat capacity and isentropic exponent (R = 287 J/(kg.K), gamma = 1.40)
  • DryAirNasa: ideal gas with temperature-dependent cp and gamma
  • ReferenceMoistAir: ideal mixture of air and water; the water mass fraction X must be specified in the source
• The adiabatic thermodynamic model (FullMedium, IdealGasConstantGamma, or PerfectGas), see UsersGuide.AdiabaticThermodynamicModels .

Known issues

• MoistAir cannot be used, as it is restricted to temperatures below the critical point of water (647 K).
• ReferenceAir (e.g. ReferenceAir.Air_ph) fails when used with the FullMedium thermodynamic model, but works with the other formulations.

Components

Contents

Name	Description
Medium

Revisions

• 2026, by Raphael Gebhart (raphael.gebhart@dlr.de):
  Initial version.