Rankine Cycle

The figure above shows Rankine cycle which includes the following  processes :

2-3 Boiler : in this stage compressed water at point (2) enters the boiler to increase it's temperature by heat exchange between fire and water, it then leaves as superheated vapor at point (3).This process called Isobaric process since the pressure during this process remains constant .

3-4 Turbine : superheated vapor (high pressure and high temperature) enters the turbine, during this process the vapor will expand and rotate the blades of the turbine. the turbine connected with electrical generator to produce electricity,after this vapor leaves the turbine as mixture of liquid and vapor state at low pressure at point (4).This process called Isentropic process that means equal entropy process.

4-1 Condenser :  isobaric process, the mixture will condensate by convection or conduction heat transfer between the air or the pipes of cooled water, so it will leave as saturated liquid at point (1). 

1-2 Pump : isentropic process in which the saturated liquid will increase it's pressure and leave the pump as compressed liquid to enter the boiler again.