⚡ Combined Cycle (Brayton + Rankine) Calculator
Model gas-steam combined cycle plants. Gas turbine exhaust feeds HRSG to generate steam for a Rankine bottoming cycle. Outputs overall efficiency, power split, HRSG T-Q diagram, and pinch temperature.
📝 Configuration
Key Equations:
ηcombined ≈ 1−(1−ηB)(1−ηR·QHRSG/Qin)
HRSG: ṁgcp(Texh−Tstack) = ṁs(h₁−hfw)
Pinch: Tgas−Tsat ≥ ΔTpinch
ηcombined ≈ 1−(1−ηB)(1−ηR·QHRSG/Qin)
HRSG: ṁgcp(Texh−Tstack) = ṁs(h₁−hfw)
Pinch: Tgas−Tsat ≥ ΔTpinch
📊 Results
Configure inputs and click Analyze to view results.
📘 Methodology
Combined Cycle
A gas turbine (Brayton) topping cycle exhausts hot gas into a Heat Recovery Steam Generator (HRSG), which drives a steam turbine (Rankine) bottoming cycle. Overall efficiency exceeds either cycle alone.
HRSG & Pinch
The pinch point — minimum temperature difference between hot gas and boiling water — constrains steam production. Lower pinch = more heat recovery but larger HRSG.
Assumptions
- Air-standard Brayton with constant cp and γ.
- Simplified water saturation curve fits.
- Single-pressure HRSG (no reheat).
- No pressure losses in HRSG.