Gas Turbine Performance Test

EPro+ delivers independent thermodynamic performance evaluations and firing temperature benchmarking for gas turbine power generation assets in accordance with ISO 2314 and ASME PTC-22 methodologies.

A gas turbine’s firing temperature cannot be measured directly. The control system calculates it from exhaust temperature, pressure, and ambient conditions. Over time, instrument drift, commissioning errors, and OEM conservatism can affect this calculation. EPro+ determines the true turbine inlet temperature through a rigorous thermodynamic energy balance. It accounts for every mass and energy flow entering and leaving the engine and compares the results with design values.

Every evaluation follows the same disciplined four-stage process, whether delivered fully remotely or with onsite support.

Initial Technical Consultation

Every evaluation starts with a clearly defined scope. After project award, we meet with your engineering team to establish the evaluation requirements and prepare the data plan.

  • Define the evaluation scope — The unit(s), technology, and the power modes to be evaluated — dry, wet, and inlet conditioning modes such as evaporative cooling, wet compression / high fogging, and inlet chilling.
  • Select the delivery model — Fully office-based, with your plant staff performing site activities under our remote guidance, or with AIM engineers onsite for pre-evaluation inspections and test coordination.
  • Build the unit-specific data plan — We review unit configuration, system P&IDs, and available control system signals to confirm the required signal list — typically around 100 signals covering firing temperatures, exhaust temperatures, compressor conditions, cooling air systems, fuel flows, and ambient conditions.
  • Set the quality bar up front — Measurement tolerances, data fidelity requirements, data acquisition configuration (PI, Depp2000, or any other plant data historian), and any hand readings (fuel gas meter readings, intake and exhaust differential pressures) are agreed before testing begins.

Data & Site Evaluation

Accurate results require accurate data. Even small input errors can significantly affect the evaluated firing temperature. For example, a 1% fuel-flow error can shift the calculated firing temperature by more than 4°C. For this reason, we treat data collection and validation as a core engineering activity.

  • Controlled measurement points — We take measurement points after the engine reaches steady-state and becomes fully heat-soaked. We average high-fidelity plant data for at least 20 minutes in each power mode. This process uses calibrated plant instrumentation and requires no additional test equipment.
  • Criteria-based stabilization — We confirm thermal stability directly from the operating data instead of relying on fixed hold times. Real-time mass-flow calculations help us determine when the engine is stable. This approach can shorten test durations without reducing accuracy.
  • Fuel gas composition — Captured by online gas chromatograph or laboratory analysis of a sample taken during the measurement period.
  • Data validation — Engine-specific checks and balances embedded in EPro+ screen every input against historical data, similar-build units, and original design parameters before any modeling begins.

When onsite scope is selected, pre-evaluation checks can include: variable guide vane and blow-off valve inspections and position verification, inlet housing inspection, weather station evaluation, thermal block instrumentation calibration status checks, data acquisition configuration assessment, fuel gas flow meter and gas chromatograph checks, and review of alarms/events, operating concept, and commissioning settings.

Thermodynamic Modeling

After validating the data, our engineers perform the EPro+ energy balance. Our team developed the methodology using OEM design and commissioning expertise and validated it against ASME PTC-22 requirements.

  • Full control-volume energy balance — A global energy balance to ASME PTC-22 accounts for every mass and energy flow in and out of the engine: fuel heat input, combustion products, cooling air flows, injection fluids, and mechanical, generator, and external heat losses.
  • Combined mass and energy balance — Conventional energy-balance calculations must assume the exhaust gas composition, leaving both compressor intake flow and exhaust enthalpy unknown. EPro+ takes a more accurate approach, formulating the energy balance and mass balance together: stoichiometric combustion of the fuel determines the exhaust constituents — combustion products, water, and excess air — directly, so the compressor inlet mass flow becomes the only unknown and is solved from the energy equation.

 

Gas Turbine Energy Balance & Performance Calculations

  • Firing temperature to ISO 2314 — Mass and energy balances around each combustor are then combined to solve for the turbine inlet enthalpy and temperature to the ISO 2314 standard — including both high-pressure and low-pressure turbine inlet temperatures (TIT1 / TIT2) for sequential combustion engines such as the GT24 and GT26.
  • Component-level efficiencies — EPro+ evaluates compressor inlet mass flow, compressor efficiency, and HP/LP turbine efficiencies on both an isentropic and polytropic basis. These calculations help identify where the engine is losing performance.
  • Reference-grade gas properties — Gas properties are computed per the NIST Chemistry WebBook (SRD 69) and NASA Glenn thermodynamic coefficients; results are corrected to ISO reference conditions for benchmarking.
  • Validation built into the tool — Data validation is a core strength of EPro+ — engine-specific checks and balances are built directly into the tool. Cooling air flows are screened against expected values for similar-build units, fuel mass flow is independently verified through the mass balance, and heat exchanger losses are confirmed from both the air and water sides — so anomalies in field data are flagged and resolved before they can distort results.

Reporting & Recommendations

We deliver the EPro+ report within two weeks after receiving all required data. The report presents the evaluation results, performance benchmarks, and recommended actions.

  • Calculated firing temperatures benchmarked against design and against your control system’s setpoints — identifying over-firing, under-firing, drift, or prior adjustment errors.
  • Compressor and turbine efficiency and mass flow results, with expected values for comparison and a clear split between recoverable degradation (fouling, filters) and non-recoverable degradation (clearances, hardware).
  • Exhaust temperature spread analysis for conventional and sequential combustion units as an indicator of combustor and turbine health.
  • Actionable recommendations — from firing temperature adjustment to optimize capacity, efficiency, and component life, to targeted follow-ups on the compressor, cooling air systems, or instrumentation.
  • All of your evaluated data, returned to you. No black box — you keep the complete evaluated dataset to support your own monitoring, maintenance planning, and LTSA discussions.

Every evaluation includes follow-up technical support, and establishes a baseline for ongoing performance monitoring. Many clients schedule periodic re-evaluations (for example, every six months) to track degradation rates, catch emerging issues early, and time compressor washes and outage scopes. Where adjustment is warranted, AIM can support full engine adjustment through a complete commissioning process.

Why firing temperature accuracy pays

  • Correcting 2°C of under-firing yields approximately 1 MW of additional output — up to $350k per year in revenue gains.
  • Correcting 2°C of over-firing mitigates roughly 5% reduction in parts life — up to $1m per interval in maintenance costs.

Applicable fleet

EPro+ was specifically developed for gas turbine technologies that utilize ISO 2314 methodologies for turbine inlet temperature evaluation, and is compatible with a wide range of industrial and aeroderivative gas turbines.

EPro+ also supports turbine technologies that utilize alternative turbine inlet temperature definitions. While OEMs may define turbine inlet temperature differently, the underlying thermodynamic principles remain the same. EPro+ accounts for these manufacturer-specific differences through tailored thermodynamic models and correction methodologies, enabling accurate and consistent performance evaluations across multiple turbine platforms.

Standards applied

EPro+ is based on internationally recognized standards and reference data to ensure accurate and repeatable performance calculations, including:

  • ASME PTC 22-2014 — Energy balance and mass flow calculations.
  • ISO 2314:2009 — Gas turbine inlet temperature calculations.
  • NIST Chemistry WebBook (SRD 69) — Thermodynamic property reference data.
  • NASA Glenn Research Center Thermodynamic Coefficients — Species enthalpy and specific heat calculations using fifth-order polynomial representations.

EPro+ applies ideal gas assumptions for gas turbine working fluids, providing a robust and reliable basis for gas turbine performance assessment and optimization.