Gas Turbine Heat Rate Calculator
Calculation Results
Net Heat Rate: 0 kJ/kWh
Thermal Efficiency: 0%
Heat Input: 0 kJ/hr
Understanding Gas Turbine Heat Rate
In thermal power generation, the Heat Rate is a critical performance metric that indicates the efficiency of a gas turbine. It represents the amount of thermal energy (fuel) required to produce one unit of electrical energy. Essentially, it is the inverse of thermal efficiency; a lower heat rate signifies a more efficient turbine.
The Formula
To calculate the heat rate of a gas turbine, we use the mass flow of the fuel, its chemical energy content (Lower Heating Value), and the measured electrical output. The standard formula is:
Heat Rate = (Fuel Flow × LHV) / Net Power Output
Key Parameters
- Fuel Mass Flow Rate: The amount of fuel consumed by the turbine per hour (e.g., kg/hr or lb/hr).
- Lower Heating Value (LHV): The net calorific value of the fuel, excluding the latent heat of vaporization of water formed during combustion.
- Net Power Output: The actual electrical power delivered to the grid after accounting for internal auxiliary loads.
Heat Rate vs. Efficiency
While Heat Rate is measured in kJ/kWh or BTU/kWh, Thermal Efficiency is expressed as a percentage. To convert a Heat Rate (in kJ/kWh) to efficiency, use the following constant (since 1 kWh = 3600 kJ):
Efficiency (%) = (3600 / Heat Rate) × 100
Example Calculation
Imagine a gas turbine operating under the following conditions:
- Fuel Flow Rate: 12,500 kg/hr
- Fuel LHV: 48,000 kJ/kg
- Power Output: 55,000 kW
Step 1: Calculate Heat Input
12,500 kg/hr × 48,000 kJ/kg = 600,000,000 kJ/hr
Step 2: Calculate Heat Rate
600,000,000 kJ/hr / 55,000 kW = 10,909.09 kJ/kWh
Step 3: Calculate Efficiency
(3,600 / 10,909.09) × 100 = 33.0%