Turbine Heat Rate Calculator
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.calculator-container {
max-width: 800px;
margin: 0 auto;
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padding: 30px;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0,0,0,0.1);
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.calculator-header {
text-align: center;
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.calculator-header h1 {
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.input-group select,
.input-group input {
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.btn-calculate:hover {
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margin-bottom: 15px;
padding-bottom: 10px;
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.result-row:last-child {
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.result-label {
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.result-value {
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.unit-hint {
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.formula-box {
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Unit System
Imperial (Btu, lb, MW)
Metric (kJ, kg, MW)
Calculate Efficiency
Heat Input:
–
Gross Heat Rate:
–
Thermal Efficiency:
–
Understanding Turbine Heat Rate
In power generation engineering, Heat Rate is one of the most critical performance metrics for thermal power plants, including gas turbines, steam turbines, and combined cycle plants. It represents the amount of thermal energy required to generate one unit of electrical energy.
Simply put, the Heat Rate tells you how efficiently a power plant converts fuel into electricity. A lower heat rate indicates higher efficiency (less fuel is needed for the same output), while a higher heat rate indicates lower efficiency.
The Calculation Formula
The calculation involves determining the total heat energy input and dividing it by the electrical power output. The standard engineering formulas used are:
Heat Rate = (Mass Flow Rate × Heating Value) / Power Output
Where:
Mass Flow Rate: The amount of fuel consumed per unit of time (e.g., lbs/hr or kg/hr).Heating Value: The energy content of the fuel (e.g., Btu/lb or kJ/kg). This can be Higher Heating Value (HHV) or Lower Heating Value (LHV).Power Output: The electrical generation, typically measured in Megawatts (MW) or Kilowatts (kW).
Thermal Efficiency Conversion
Heat Rate is the inverse of thermal efficiency. While efficiency is expressed as a percentage, Heat Rate is expressed in energy units per kWh. The conversion depends on the unit system used:
Imperial: Efficiency (%) = 3,412 / Heat Rate (Btu/kWh) × 100Metric: Efficiency (%) = 3,600 / Heat Rate (kJ/kWh) × 100
Note: 3,412 Btu is the thermal equivalent of 1 kWh, and 3,600 kJ is the metric thermal equivalent of 1 kWh.
Factors Affecting Heat Rate
Several operational factors can degrade a turbine's heat rate, increasing fuel costs:
Ambient Temperature: Gas turbines generally perform better in cooler air due to increased air density.Load Factor: Running a turbine at partial load (e.g., 50% capacity) significantly increases the heat rate compared to base load operation.Component Degradation: Compressor fouling, seal leakage, and blade erosion reduce internal efficiency over time.Back Pressure: High exhaust pressure reduces the expansion capability of the turbine, lowering power output for the same fuel input.
Typical Heat Rate Values
While values vary heavily by technology and age, here are general benchmarks:
Simple Cycle Gas Turbine: 9,000 – 11,000 Btu/kWh (31% – 38% efficiency).Combined Cycle Gas Turbine (CCGT): 6,000 – 7,000 Btu/kWh (48% – 57% efficiency).Coal Steam Turbine: 9,500 – 10,500 Btu/kWh (32% – 36% efficiency).
// Update labels based on selected unit system
function updateLabels() {
var system = document.getElementById('unitSystem').value;
var flowLabel = document.getElementById('flowLabel');
var hvLabel = document.getElementById('hvLabel');
if (system === 'metric') {
flowLabel.textContent = "Fuel Mass Flow Rate (kg/hr)";
hvLabel.textContent = "Fuel Heating Value (kJ/kg)";
} else {
flowLabel.textContent = "Fuel Mass Flow Rate (lb/hr)";
hvLabel.textContent = "Fuel Heating Value (Btu/lb)";
}
}
// Main Calculation Logic
function calculateHeatRate() {
// Get Inputs
var flow = parseFloat(document.getElementById('fuelFlow').value);
var hv = parseFloat(document.getElementById('heatingValue').value);
var powerMW = parseFloat(document.getElementById('powerOutput').value);
var system = document.getElementById('unitSystem').value;
// Validation
if (isNaN(flow) || isNaN(hv) || isNaN(powerMW) || powerMW <= 0) {
alert("Please enter valid positive numbers for all fields.");
return;
}
// 1. Calculate Total Heat Input per Hour
// Metric: kg/hr * kJ/kg = kJ/hr
// Imperial: lb/hr * Btu/lb = Btu/hr
var heatInputTotal = flow * hv;
// 2. Convert Power from MW to kW
var powerKW = powerMW * 1000;
// 3. Calculate Heat Rate
// Result is Energy/kWh (Btu/kWh or kJ/kWh)
var heatRate = heatInputTotal / powerKW;
// 4. Calculate Thermal Efficiency
// 1 kWh = 3412.14 Btu
// 1 kWh = 3600 kJ
var efficiency = 0;
var unitLabel = "";
var inputUnitLabel = "";
if (system === 'metric') {
efficiency = (3600 / heatRate) * 100;
unitLabel = " kJ/kWh";
inputUnitLabel = " MMkJ/hr"; // Million kJ per hour for display readability
} else {
efficiency = (3412.14 / heatRate) * 100;
unitLabel = " Btu/kWh";
inputUnitLabel = " MMBtu/hr"; // Million Btu per hour
}
// Display Results
var resultsDiv = document.getElementById('results');
resultsDiv.style.display = "block";
// Format Total Heat Input (divide by 1,000,000 for MM units)
document.getElementById('resHeatInput').textContent = (heatInputTotal / 1000000).toFixed(2) + inputUnitLabel;
// Format Heat Rate
document.getElementById('resHeatRate').textContent = Math.round(heatRate).toLocaleString() + unitLabel;
// Format Efficiency
document.getElementById('resEfficiency').textContent = efficiency.toFixed(2) + "%";
}