Difference between Carnot Cycle and Rankine Cycle

Today I am going to tell you the difference between the Carnot cycle and Rankine cycle. Both the Carnot cycle and Rankine cycle are air standard cycles. Carnot cycle is an ideal cycle for heat engine which gives the highest efficiency between given temperature difference but it is a theoretical cycle and actually, no engine works on it. Rankine cycle is an ideal cycle of vapor or steam power generation. All steam power plant work on this cycle. It uses water as the working substance. Both these cycles have different features which I will describe below.

Carnot cycle has two isothermal processes and two isentropic processes. Heat is added and rejected isothermally and compression and expansion take place at constant entropy. It is a theoretical cycle because actually, it is difficult to achieve isothermal heat addition and rejection. It gives the highest efficiency between the given temperature difference.  As I told the Rankine cycle is an ideal vapor power generation cycle used in a steam turbine. It consists of two isobaric and two isentropic processes. Heat is added and rejected at constant pressure and expansion and compression of steam takes place isentropically. In practically, first water is pumped to a boiler where heat is added at constant pressure which converts water into steam. This high-temperature steam rotates the turbine. This expansion of steam takes places isentropically. Now the heat is rejected into the condenser at constant pressure which converts it into the water. Now, this water is again pumped into boiler isentropically which complete the cycle. This cycle runs continuously which generate power.

The basic and main difference between Carnot and Rankine cycle is that in Carnot cycle heat is added and rejected at constant temperature and in Rankine cycle heat addition and rejection take place at constant pressure. The other main difference is that the Rankine cycle use water as working substance and Carnot cycle use air as working substance. There are many other differences which are described below in tabular form.

Difference between the Carnot Cycle and Rankine cycle:

Sr. No.	Carnot Cycle	Rankine Cycle
1.	It is a theoretical cycle. It gives maximum efficiency between two temperature difference	This one is a practical cycle of the steam engine and turbine.
2.	Heat is added and rejected at a constant temperature.	Heat is added and rejected at constant pressure.
3.	It has the highest efficiency between two temperature differences.	Rankine cycle has lower efficiency than the Carnot cycle.
4.	Carnot cycle uses air as the working substance.	Rankine cycle uses water as a working substance.
5.	Carnot cycle is an ideal cycle for a heat engine.	It is an ideal cycle for vapor power engine.

Today we have discussed about the main difference between the Carnot cycle and Rankine Cycle. If you have any query regarding this article, ask by commenting. If you know any other differences, let us know through comments. Thanks for reading it.