Rankine Cycle
Also known as: Clausius-Rankine cycle, steam cycle, vapor power cycle
The Rankine Cycle is the fundamental thermodynamic cycle for steam power plants. It describes how thermal energy from burning fuel or concentrated solar radiation is converted to mechanical work and ultimately electricity. The cycle consists of four processes: isobaric heat addition in the boiler, isentropic expansion through the turbine, isobaric heat rejection in the condenser, and isentropic compression by the pump.
Key highlights
- Provides exact thermodynamic framework for practical steam power systems
- Well-established property tables and correlations available for water
- Accounts for realistic irreversibilities (nonideal turbine/pump efficiencies)
- Modular structure allows systematic improvements (superheat, reheat, regeneration)
Intuition
This section is available to Pro members. Upgrade to Pro
How it works
This section is available to Pro members. Upgrade to Pro
When to use it
Use Rankine Cycle analysis for designing and evaluating steam power plants, including conventional thermal plants, nuclear stations, and concentrated solar power systems. It is the correct framework for any system converting heat to work at intermediate (200-600 K) temperatures using water as the working fluid.
Strengths & limitations
- Provides exact thermodynamic framework for practical steam power systems
- Well-established property tables and correlations available for water
- Accounts for realistic irreversibilities (nonideal turbine/pump efficiencies)
- Modular structure allows systematic improvements (superheat, reheat, regeneration)
- Assumes quasi-equilibrium processes, not applicable to transient startups
- Standard Rankine Cycle ignores pressure drops and real fluid effects
- Performance is relatively insensitive to turbine inlet temperature above ~600 K
- Water's critical temperature limits highest possible cycle temperature
Common pitfalls
This section is available to Pro members. Upgrade to Pro
Applications
This section is available to Pro members. Upgrade to Pro
Frequently asked
Why is the Rankine Cycle more practical than the Carnot Cycle for power generation?
Carnot Cycle requires isothermal heat transfer at constant temperature, which is impractical at industrial scale. Rankine uses isobaric (constant pressure) heat addition, matching how real boilers work. Though less efficient, Rankine is thermodynamically sensible and economically viable.
What is the benefit of superheat and reheat in a Rankine Cycle?
Superheat (heating steam above saturation) and reheat (reheating partially expanded steam) shift heat addition to higher average temperatures, increasing efficiency. They also reduce moisture in the turbine exhaust, protecting turbine blades.
How does regenerative feedwater heating improve cycle efficiency?
Regeneration uses turbine bleed steam at intermediate pressures to preheat the boiler feedwater. This shifts heat addition from lower temperature (pump outlet) to higher temperature regions, increasing the average temperature of heat input and thus efficiency.
Sources
- 1.Smith, J. M., Van Ness, H. C., & Abbott, M. M. (2005). Introduction to Chemical Engineering Thermodynamics (7th ed.). McGraw-Hill.ISBN 978-0071247009
- 2.Moran, M. J., Shapiro, H. N., Boettner, D. D., & Bailey, M. B. (2014). Fundamentals of Engineering Thermodynamics (8th ed.). Wiley.ISBN 978-1118412947
You have read it. What now?
Cite this page
ScholarGate. (2026, June 3). Rankine Cycle. ScholarGate. https://scholargate.app/thermodynamics/rankine-cycle