Thermoeconomic optimization for green multi-shaft gas turbine engines

• The cost of the series gas turbine is higher than the parallel (by 7%).
• The performance of the components affects its cost directly.
• For the parallel configuration, sacrificing little cost increase power 10%.
• For series configuration, its optimum pressure ratio up to 11.43.
• For the two configurations work increases with (TIT).

The thermoeconomic analysis of a gas turbine engine with two turbines is presented and discussed in this work. Two configurations (in parallel and series free turbine) are presented and analysed. The thermoeconomic analysis relies on the energy and exergy analysis of the system, and the capital cost evaluated for each component using annualized capital cost equations. Then it is used in combination with exergy analysis to evaluate the net work and cost rate.Optimization is performed by considering pressure ratio, turbine inlet temperature and cost as the important operating variables. The results are obtained for both configurations and represented in graphs and tables, the results are discussed and compared to each other.The comparison of the two configurations shows that the specific cost (cost per kW) is higher for parallel than series (by 4%). However, the series has higher total cost than the parallel (by 7%).