27 December 2017

Difference between brayton and rankine cycle

What is the Brayton cycle?

Brayton cycle is a jet engine, the air is sucked, compressed and then released into the atmosphere, thus making an open cycle.

What is the Rankine cycle?

Rankine cycle is a steam engine, the water is boiled, evaporated, used for work and then condensed for re-use, thus making it a closed cycle. 

Main difference :

The working fluid undergoes a phase change in the Rankine cycle whereas in Brayton cycle there is no phase change the working fluid always remains in the gaseous phase.

Let us have a deep insight into the Brayton cycle vs Rankine cycle. 

Difference :

  • Brayton cycle consists of two reversible isobaric processes and Rankine cycle consist of two reversible adiabatic processes.
  • Both the pump and the steam turbine in the case of the Rankine cycle, and the compressor and the gas turbine in the case of the Brayton cycle operate through the same pressure difference. 
  • The average specific weight of air handled by the compressor is less than the same of gas in the gas turbine in Brayton cycle so the work done by the gas turbine is more than the work input to the compressor while in the case of Rankine cycle, the specific weight of water in the pump is much less than the steam expanding in the steam turbine, therefore, steam power plants are more popular than gas turbine plants for electricity generation.
  • Brayton cycle operates between a higher pressure ratio than the Rankine cycle for the same capacity.