What Is the Rankine Cycle (Reheat) Thermal Efficiency Calculator?
The reheat Rankine cycle expands steam in two separate turbine stages: High Pressure (HP) and Low Pressure (LP).
It increases mean temperature of heat addition and raises exhaust steam quality above the 90% erosion threshold.
How Does the Rankine Cycle (Reheat) Thermal Efficiency Calculator Work?
Evaluates enthalpy drops across the HP turbine from boiler pressure to reheat pressure.
Adds reheat enthalpy input from the boiler reheater coils.
Evaluates LP turbine expansion to condenser vacuum.
Calculates net specific work, thermal efficiency, and heat rate in kJ/kWh.
Rankine Cycle (Reheat) Thermal Efficiency Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Thermodynamic energy balance summing work output from HP and LP turbines divided by primary boiler and reheat heat inputs.
How to Use the Rankine Cycle (Reheat) Thermal Efficiency Calculator
- Enter boiler pressure, reheat pressure, and condenser pressure in bar.
- Enter main steam and reheat steam temperatures in degrees Celsius.
Step-by-Step Example Calculation
500 MW Subcritical Coal/Gas Steam Power Plant
Input Values:
Understanding Your Result
Thermal efficiency indicates the percentage of fuel heat converted into net shaft electricity.
Plant heat rate in kJ/kWh is the inverse of efficiency, measuring fuel energy required per kilowatt-hour.
Factors That Affect the Result
- Condenser vacuum: Lower condenser pressure drastically expands the LP turbine pressure ratio, boosting efficiency.
- Reheat pressure optimization: Optimal reheat pressure typically lies around 20% to 25% of boiler throttle pressure.
When Should You Use This Calculator?
- Thermodynamic feasibility modeling of thermal power plants and cogeneration facilities.
- Evaluating turbine retrofits and heat rate improvements.
Assumptions & Limitations
- Uses idealized steam table property approximations with constant isentropic stage efficiencies.
- Neglects regenerative feedwater heater bleed extractions.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Correlates within 3% of ASME steam tables for utility superheat conditions.