๐ฅ Steam-Injected Gas Turbine (STIG / Cheng)
Calculate Steam-Injected Gas Turbine (STIG / Cheng cycle) performance: power boost gain (+40-70%), thermal efficiency, HRSG steam duty, and turbine expansion.
โก Fortran 90 Engine
Double Precision (IEEE 754)
โ ISO / ASME Validated
Thermodynamics
๐ Solver Telemetry
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๐ฆ Fortran Code
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๐
Released
Jun 2026
โฑ๏ธ Latency
< 1 ms
๐ฅ Dual-Fluid Gas Turbine & HRSG Steam Injection Manifold
Real-time visual simulation: High-temperature exhaust generating superheated steam injected into combustor for massive power boost๐ Configuration & Presets
โ๏ธ Aeroderivative LM5000 STIG
โก Frame 6B Peaker Boost (+50%)
๐ฅ Cheng Dual-Fluid Cycle (18% Steam)
๐ญ Microturbine Distributed CHP
STIG / Cheng Dual-Fluid Formulation:
โข Turbine Expansion: Wฬturb = (แนair ยท cp,air + แนsteam ยท cp,steam) ยท TIT ยท [1 โ (1/rp)(ฮณโ1)/ฮณ] ยท ฮทt
โข Power Boost: ฮPnet / Psimple โ +40% to +70%
โข Steam specific heat (cp,steam โ 2.15 kJ/kgยทK) is ~2ร air, multiplying expansion power.
โข Drastic reduction in thermal NOx emissions in combustor.
โข Turbine Expansion: Wฬturb = (แนair ยท cp,air + แนsteam ยท cp,steam) ยท TIT ยท [1 โ (1/rp)(ฮณโ1)/ฮณ] ยท ฮทt
โข Power Boost: ฮPnet / Psimple โ +40% to +70%
โข Steam specific heat (cp,steam โ 2.15 kJ/kgยทK) is ~2ร air, multiplying expansion power.
โข Drastic reduction in thermal NOx emissions in combustor.
๐ STIG Performance Results
๐ Output Summary
STIG Net Electrical Power Output
0.50 MW (vs 0.40 MW simple)
STIG Efficiency: 28.06 % (vs 25.09 %) | Boost: +25.1 %
+0.1 MW Boost
Net Power Boost Gain
+25.1 %
Without extra compressor power
Injected Steam Flow Rate
0.15 kg/s
6 % of air flow
HRSG Steam Heat Duty
0.45 MW
Exhaust waste heat recovery
Turbine Exhaust Gas Temp
672.0 ยฐC
Inlet to HRSG boiler
๐ Power Boost Gain (%) vs Steam Injection Ratio แนs/แนa (%)
๐ STIG Thermal Efficiency (%) vs Pressure Ratio r_p
================================================================= THERMOFLUIDCALC โ STEAM-INJECTED GAS TURBINE (STIG / CHENG) REPORT ================================================================= Case Title : Distributed Microturbine Combined Heat & Power (CHP) Gas Turbine Parameters : Pressure Ratio rp = 4.5, TIT = 950.0 C, Air Flow = 2.5 kg/s Steam Injection System : Injection Ratio = 6.0 % (m_steam = 0.15 kg/s), Steam Temp = 350.0 C ----------------------------------------------------------------- STIG NET POWER OUTPUT : 0.501 MW Simple Cycle Baseline Power: 0.400 MW POWER BOOST GAIN : +25.09 % (+0.100 MW) STIG THERMAL EFFICIENCY : 28.059 % (vs 25.089 % simple) HRSG Steam Heat Recovery : 0.450 MW Turbine Exhaust Temperature: 672.0 deg C NOx Reduction Effect : Substantial flame temperature cooling & steam dilution =================================================================
๐ Calculation Methodology & STIG Standards
Dual-Fluid Expansion Principle
Injecting superheated steam increases mass flow and specific heat ($c_{p,steam} \approx 2.15\,\text{kJ/kg}\cdot\text{K}$) across turbine expanders without demanding additional compressor parasitic power.
Single-Shaft Simplicity
Achieves combined-cycle-class efficiency ($\eta \approx 45 - 50\%$) without the capital complexity of a separate steam turbine, condenser, cooling tower, and vacuum system.
Key Engineering Assumptions
- Superheated steam injected at $P_{inj} > 1.15 P_{comp}$.
- Ideal gas mixture thermodynamics for exhaust products + steam.
- Applicable to aeroderivative turbines, peaker power stations, and industrial cogeneration.