Gas Turbine Heat Rate Calculator
Calculate Gross Heat Rate and Thermal Efficiency based on power output and fuel consumption.
MW
kg/s
kJ/kg
Natural Gas LHV is typically around 47,000 – 50,000 kJ/kg.
Calculation Results
Heat Rate (Metric):
– kJ/kWh
Heat Rate (Imperial):
– BTU/kWh
Total Heat Input:
– MWth
Thermal Efficiency:
– %
Understanding Gas Turbine Heat Rate
In power generation thermodynamics, the Heat Rate is the inverse of efficiency. It represents the amount of thermal energy (fuel) required to generate one unit of electrical energy. While efficiency is expressed as a percentage, heat rate is expressed in energy units per kilowatt-hour (e.g., kJ/kWh or BTU/kWh).
A lower heat rate indicates a more efficient gas turbine. It means the engine consumes less fuel to produce the same amount of electricity.
Key Formula:
Heat Rate = (Fuel Flow Rate × Lower Heating Value) / Power Output
Heat Rate = (Fuel Flow Rate × Lower Heating Value) / Power Output
How the Calculation Works
This calculator determines the performance of a gas turbine using the following methodology:
- Heat Input: Calculated by multiplying the Mass Flow Rate of the fuel (kg/s) by the Lower Heating Value (LHV) of the fuel (kJ/kg). This gives the thermal energy entering the system.
- Power Output: The gross electrical output measured at the generator terminals (in MW).
- Thermal Efficiency: This is the ratio of useful work (Power Output) to the Heat Input.
Typical Values
Modern Heavy Duty Gas Turbines (Simple Cycle) typically operate with heat rates between 9,000 and 11,000 kJ/kWh (approx. 33% to 40% efficiency). Combined Cycle Gas Turbines (CCGT), which recover waste heat, can achieve heat rates as low as 5,700 kJ/kWh (over 63% efficiency).
Factors Influencing Heat Rate
Several factors can degrade the heat rate (increase fuel consumption) over time:
- Ambient Temperature: Higher intake air temperatures reduce air density, reducing mass flow and efficiency.
- Compressor Fouling: Dirt accumulation on compressor blades reduces compression efficiency.
- Part Load Operation: Running a turbine below its base load significantly increases the heat rate.