Where do you want to go ?

Rankine Cycle with Regeneration

Splitter - stream 3 is split into streams 4 and 5.

3-4,5:

Pump #2- isentropic Compression.

9-1:

In a

Rankine Cycle with Regeneration

, pumping the condenser effluent back up to the high pressure of the boiler is done in two stages.

At the intermediate pressure between the two pumps, the working fluid is heated back to the saturated liquid state in the feedwater heater.

The feedwater heater shown here is called an open feedwater heater because some of the effluent from the high pressure turbine actually mixes with the effluent from the first pump.

Process flow diagram of a Rankine Vapor Power Cycle with regeneration using an open feedwater heater.

Boiler - heat added at constant pressure.

1-2:

High-Pressure Turbine (HP) - isentropic expansion.

2-3:

Low-Pressure Turbine (LP)- isentropic expansion.

5-6:

Condenser - heat rejected at constant pressure.

6-7:

Pump #1 - isentropic compression.

7-8:

Feedwater Heater (FWH) - temperature increases by mixing.

8-9:

Feedwater Heater (FWH) - temperature decreases by mixing

4-9:

Lesson
9C Blog

Confused and have questions? We've got answers. With Chegg Study, you can get step-by-step solutions to your questions from an expert in the field. If you rather get 1:1 study help, try 30 minutes of free online tutoring with Chegg Tutors.

Roll your mouse over this box to close.

Join Learn Thermodynamics Advantage

Download Data Tables
Download Study Aids
Homework problem hints and answers
Get Help from Dr. B in the LT Blog
120 day membership

Click here to Log-In to your LTA account

Get it ALL for $5 US

Lesson 9C: page 7 of 16

Regeneration is an attempt to reduce the irreversibility associated with transferring heat from the high-temperature reservoir to the subcooled liquid that leaves the pump in an ordinary Rankine Cycle.
There is a very large difference between the temperature of the hot reservoir the temperature of the pump effluent.
So, it is wasteful to feed such cold liquid to the boiler.
In a regeneration cycle, two turbines are used and a portion of the effluent from the high pressure turbine is used to “preheat” or “regenerate” the boiler feed.
The device in which the boiler feed stream is preheated is called a Feedwater Heater.
The feedwater heater shown here is called an OPEN feedwater heater because the condenser effluent is pumped up to the same pressure as the high-pressure turbine effluent and they are allowed to MIX or combine into one stream.
Before I describe a CLOSED feedwater heater, let’s see what a regeneration cycle with an open feedwater heater looks like on a TS Diagram.

Rankine Cycle with Regeneration

Rankine Cycle with Regeneration

Ch 9, Lesson C, Page 7 - Rankine Cycle with Regeneration