Calculator · Thermal Engineering
Brayton Cycle
The ideal gas-turbine cycle: isentropic compression and expansion with constant-pressure heat addition and rejection. Set the pressure ratio and γ for the efficiency; the inlet state and turbine inlet temperature fix the four corner states.
Inputs
Ideal cycle limits: reversible Carnot models between two reservoirs, and ideal air-standard Otto, Diesel and Brayton cycles with constant specific heats. Real machines fall below these values.
Results
Thermal efficiency η
Ideal air-standard limit with constant specific heats.
| Heat added q_in | 1195.2 kJ/kg |
|---|---|
| Heat rejected q_out | 587.62 kJ/kg |
| Net work w_net | 607.56 kJ/kg |
| Thermal efficiency η | 50.83 % |
| State | p | v | T |
|---|---|---|---|
| 1 | 100 kPa | 0.861 m³/kg | 300 K |
| 2 | 1.2 MPa | 0.14593 m³/kg | 610.181 K |
| 3 | 1.2 MPa | 0.4305 m³/kg | 1800 K |
| 4 | 100 kPa | 2.5399 m³/kg | 884.983 K |
Assumptions
- · ideal air-standard cycle
- · constant specific heats
- · ideal compressor and turbine
- · constant-pressure heat addition and rejection
Explore in the Lab
The full cycle state travels; the Lab adds the state diagram and the comparison view.
Technical reference
η = 1 − r_p^((1−γ)/γ)
T2 = T1·r_p^((γ−1)/γ)
q_in = cp(T3 − T2)
- T_H
- hot reservoir temperature (absolute)[K]
- T_C
- cold reservoir temperature (absolute)[K]
- r
- compression ratio[—]
- r_c
- cutoff ratio[—]
- r_p
- pressure ratio[—]
- γ
- heat-capacity ratio cp/cv[—]
Air-standard cycle with constant specific heats and an ideal compressor and turbine.
Heat is added and rejected at constant pressure.
The turbine inlet temperature T3 must exceed the compressor outlet temperature T2.