Turbine Heat Rate Calculator
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Turbine Heat Rate Calculator
Measurement System
Imperial (Btu, lb, MW)
Metric (kJ, kg, MW)
Calculate Heat Rate
Print Results to PDF
Total Heat Input:
–
Gross Heat Rate:
–
Thermal Efficiency:
–
Understanding Turbine Heat Rate Calculation
In power generation engineering, the Heat Rate is one of the most critical performance metrics for thermal power plants. It represents the efficiency of a power plant to convert the chemical energy of a fuel into electrical energy. Unlike standard efficiency percentages where higher is better, a lower heat rate indicates higher efficiency .
This guide serves as a digital resource comparable to a "turbine heat rate calculation pdf" for engineers and plant operators looking to verify thermal performance.
The Heat Rate Formula
The gross heat rate is calculated by dividing the total heat energy input by the gross electrical energy output. The standard formula used in this calculator is:
Heat Rate = (Fuel Flow Rate × Heating Value) / Power Output
Where:
Fuel Flow Rate: The mass of fuel consumed per unit of time (e.g., lb/hr or kg/hr).Heating Value: The energy content per unit of mass of the fuel (e.g., Btu/lb or kJ/kg). Usually, the Lower Heating Value (LHV) is used for gas turbines, while Higher Heating Value (HHV) is often used for steam turbines in the US.Power Output: The electrical generation, typically converted from Megawatts (MW) to Kilowatts (kW) for the final calculation.
Imperial vs. Metric Units
Power plant thermodynamics are calculated differently depending on regional standards:
Imperial (US Customary)
Heat Rate Unit: Btu/kWh (British Thermal Units per Kilowatt-hour).Conversion constant: 1 kWh = 3412.14 Btu.Efficiency Formula: η (%) = 3412.14 / Heat Rate (Btu/kWh) × 100.
Metric (SI)
Heat Rate Unit: kJ/kWh (Kilojoules per Kilowatt-hour) or kCal/kWh.Conversion constant: 1 kWh = 3600 kJ.Efficiency Formula: η (%) = 3600 / Heat Rate (kJ/kWh) × 100.
Example Calculation
Consider a Combined Cycle Gas Turbine (CCGT) plant with the following operating parameters:
Fuel Flow: 150,000 lb/hrHeating Value: 20,500 Btu/lb (Natural Gas)Generation: 450 MW
Step 1: Calculate Total Heat Input
Step 2: Convert Power to kW
Step 3: Calculate Heat Rate 6,833 Btu/kWh
Step 4: Calculate Thermal Efficiency 49.93%
Factors Influencing Heat Rate
Several factors can degrade a turbine's heat rate over time, requiring regular calculation and monitoring:
Ambient Conditions: High ambient temperatures reduce air density, reducing mass flow through gas turbines and increasing heat rate.Part Load Operation: Turbines are most efficient at base load (100% capacity). Operating at partial loads significantly increases the heat rate.Compressor Fouling: Deposits on compressor blades reduce airflow and compression efficiency.Condenser Pressure: In steam turbines, higher back pressure in the condenser reduces the enthalpy drop across the turbine, increasing heat rate.
function updateLabels() {
var system = document.getElementById('unitSystem').value;
var labelFlow = document.getElementById('labelFuelFlow');
var labelHV = document.getElementById('labelHeatingValue');
if (system === 'imperial') {
labelFlow.innerText = "Fuel Flow Rate (lb/hr)";
labelHV.innerText = "Fuel Heating Value (Btu/lb)";
} else {
labelFlow.innerText = "Fuel Flow Rate (kg/hr)";
labelHV.innerText = "Fuel Heating Value (kJ/kg)";
}
}
function calculateHeatRate() {
// 1. Get Input Values
var system = document.getElementById('unitSystem').value;
var fuelFlow = parseFloat(document.getElementById('fuelFlow').value);
var heatingValue = parseFloat(document.getElementById('heatingValue').value);
var powerMW = parseFloat(document.getElementById('powerOutput').value);
// 2. Validate Inputs
if (isNaN(fuelFlow) || isNaN(heatingValue) || isNaN(powerMW) || powerMW === 0) {
alert("Please enter valid numerical values for all fields. Power Output cannot be zero.");
return;
}
// 3. Perform Calculations
// Convert MW to kW for the denominator
var powerKW = powerMW * 1000;
// Calculate Total Heat Input per hour
// Imperial: lb/hr * Btu/lb = Btu/hr
// Metric: kg/hr * kJ/kg = kJ/hr
var totalHeatInput = fuelFlow * heatingValue;
// Calculate Heat Rate
// Formula: Heat Input / Power Output (kW)
var heatRate = totalHeatInput / powerKW;
// Calculate Efficiency
var efficiency = 0;
var heatRateUnit = "";
var heatInputUnit = "";
if (system === 'imperial') {
// 1 kWh = 3412.14 Btu
efficiency = (3412.14 / heatRate) * 100;
heatRateUnit = " Btu/kWh";
heatInputUnit = " Btu/hr";
} else {
// 1 kWh = 3600 kJ
efficiency = (3600 / heatRate) * 100;
heatRateUnit = " kJ/kWh";
heatInputUnit = " kJ/hr";
}
// 4. Update UI
var displayHeatInput = totalHeatInput.toLocaleString(undefined, {maximumFractionDigits: 0});
var displayHeatRate = heatRate.toLocaleString(undefined, {maximumFractionDigits: 2});
var displayEfficiency = efficiency.toFixed(2);
document.getElementById('resHeatInput').innerHTML = displayHeatInput + '
' + heatInputUnit + ' ';
document.getElementById('resHeatRate').innerHTML = displayHeatRate + '
' + heatRateUnit + ' ';
document.getElementById('resEfficiency').innerHTML = displayEfficiency + '%';
document.getElementById('results').style.display = 'block';
}