Model Brayton performance using realistic operating inputs. See efficiency, temperatures, work split, and pressure effects. Use graphs, exports, formulas, examples, and plain guidance easily.
This calculator estimates ideal and actual Brayton cycle performance using pressure ratio, temperature limits, efficiencies, and working-fluid properties.
Enter thermodynamic inputs below to estimate efficiency, work, heat transfer, and power.
These sample cases show how changing pressure ratio, temperatures, and component efficiencies affects Brayton cycle performance.
| Case | T1 (K) | T3 (K) | rp | γ | cp (kJ/kg·K) | ηc (%) | ηt (%) | ṁ (kg/s) | Actual efficiency (%) | Net work (kJ/kg) | Power (kW) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Base gas turbine | 300 | 1400 | 8 | 1.40 | 1.005 | 85 | 88 | 3.0 | 32.63 | 266.82 | 800.45 |
| Moderate pressure rise | 290 | 1300 | 10 | 1.40 | 1.005 | 82 | 86 | 2.5 | 30.81 | 210.83 | 527.09 |
| Higher temperature limit | 310 | 1500 | 12 | 1.38 | 1.020 | 87 | 90 | 4.0 | 37.97 | 325.34 | 1301.35 |
n = (γ - 1) / γ
T2s = T1 × rpn
T2 = T1 + (T2s - T1) / ηc
T4s = T3 / rpn
T4 = T3 - ηt(T3 - T4s)
wc = cp(T2 - T1)
wt = cp(T3 - T4)
qin = cp(T3 - T2)
qout = cp(T4 - T1)
ηth = (wt - wc) / qin × 100
Back work ratio = wc / wt × 100
Net power = ṁ × (wt - wc)
These equations assume constant specific heats and a simple Brayton cycle with constant-pressure heat addition and rejection.
It is the fraction of supplied heat converted into useful net work. A higher value means the gas turbine converts more thermal energy into mechanical output.
Increasing pressure ratio usually raises ideal efficiency because it increases the compressor discharge temperature and reduces the relative heat rejection. Excessive ratios can reduce practical gains when component losses are included.
Ideal calculations assume reversible compression and expansion. Actual machines have losses, so compressors need more work and turbines deliver less work, reducing real efficiency.
Back work ratio is the compressor work divided by turbine work. It shows how much turbine output is consumed internally to drive the compressor.
Use kelvin for temperatures, kilopascals for pressure, kilograms per second for mass flow, and kilojoules per kilogram-kelvin for specific heat. Results then remain internally consistent.
Yes, for first-pass estimates. It is useful for preliminary sizing, learning, and comparison. Detailed design still needs variable properties, pressure losses, combustion details, and mechanical losses.
A less efficient compressor raises the outlet temperature more than the ideal case. That increases compressor work and lowers the net work available from the cycle.
It is the ideal pressure ratio that maximizes specific net work for the chosen minimum and maximum temperatures. It does not guarantee maximum real efficiency for every practical turbine setup.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.