Optimum design and thermodynamic analysis of a gas turbine and ORC combined cycle with recuperators

• A GT-ORC combined cycle with recuperators was designed.
• The effect of the ORC turbine inlet pressure on the combined cycle was examined.
• Toluene was a more suitable working fluid for the GT-ORC combined cycle.
• The GT-ORC combined cycle performed better than the GT-Rankine combined cycle.
• The sensitivity analysis to the ambient temperature was completed.

Gas turbines are widely used in distributed power generation because of their high efficiency, low pollution and low operational cost. To further utilize the waste heat from gas turbines, an organic Rankine cycle (ORC) was proposed as the bottoming cycle for gas turbines in this paper. Two recuperators were coupled with the combined cycle to increase the thermal efficiency, and aromatics were chosen as the working fluid for the bottoming cycle. This paper focused on the optimum design and thermodynamic analysis of the gas turbine and ORC (GT-ORC) combined cycle. Results showed that the net power and thermal efficiency of the ORC increased with the ORC turbine inlet pressure and achieved optimum values at a specific pressure based on the optimum criteria. Furthermore, compared with the GT-Rankine combined cycle, the GT-ORC combined cycle had better thermodynamic performance. Toluene was a more suitable working fluid for the GT-ORC combined cycle. Moreover, ambient temperature sensitivity simulations concluded that the GT-ORC combined cycle had a maximum thermal efficiency and the combined cycle net power was mainly determined by the topping gas turbine cycle.