Understanding Rankine Cycle Pressures: Should P2 Equal P3?

In summary: C1 = 18 MPa, TMC1 = 580 C, P1 = 6 kPa, P2 = 18.5 MPa, P3 = 18 MPa, T3 = 25 C, Wturbine = m_dot*(h1-h2), Wpump = m_dot*(h3-h4), boiler efficiency = 85%, mechanical efficiency = 88%, generator efficiency = 92%In summary, The problem is about a Rankine cycle power plant where superheated steam at 18 MPa and 580 C enters a turbine and expands through a single stage with an efficiency of 82%. The steam then discharges at 6 kPa and is pumped to
  • #1
Kamuna
9
1
Homework Statement
determine:
a) Electrical power output of the plant if mechanical efficiency & generator efficiency
are 88 % & 92 %, respectively.
b) Heat added in the steam generator if boiler efficiency is 85 %
c) Plant thermal efficiency
Relevant Equations
Rankine cycle
Is this the right path in solving this problem? Am i finding the correct enthalpies? I am also having difficulty understanding so what I've understood is that in a rankine cycle P2=P3 but here P2 is given and P3 has a given variable which is T=25 C too so should I neglect P2=P3?

Heres my problem set and the attempt to solve it:

In a Rankine cycle power plant superheated steam enters the turbine at 18 MPa and 580 C. Steam expands through a single stage turbine and discharges at 6 kPa with stage efficiency of 82 %. The condensate leaves the condenser at 25 C and pumped to 18.5 MPa going to the steam generator. The pump efficiency is 77 %. For steam flow of 9,000 kg/hr, determine:

  • Electrical power output of the plant if mechanical efficiency & generator efficiency
  • are 88 % & 92 %, respectively.
  • Heat added in the steam generator if boiler efficiency is 85 %
  • Plant thermal efficiency
Any help would be much appreciated, thanks

1649171596176.png
 

Attachments

  • IMG_20220405_215442.jpg
    IMG_20220405_215442.jpg
    25.2 KB · Views: 86
Last edited by a moderator:
Physics news on Phys.org
  • #2
I don't quite understand this part: "The condensate leaves the condenser at 25 C and pumped to 18.5 MPa going to the steam generator. Does this mean the pump compresses the steam at 25C and 6 kPa to a pressure of 18.5 MPa and then that steam/hot water is heated in the steam generator at constant volume? If so, how does this result in steam exiting the steam generator at 18 MPa?

AM
 

Related to Understanding Rankine Cycle Pressures: Should P2 Equal P3?

What is a Rankine cycle power plant?

A Rankine cycle power plant is a type of thermal power plant that converts heat energy into mechanical energy, which is then used to generate electricity. It is named after William John Macquorn Rankine, a Scottish engineer who developed the concept in the 19th century.

How does a Rankine cycle power plant work?

A Rankine cycle power plant works by using a fuel source, such as coal or natural gas, to heat water and produce steam. The steam then drives a turbine, which is connected to a generator that produces electricity. The steam is then condensed back into water and the process repeats.

What are the main components of a Rankine cycle power plant?

The main components of a Rankine cycle power plant include a boiler, turbine, condenser, and pump. The boiler is where the fuel is burned to heat the water and produce steam. The turbine converts the energy from the steam into mechanical energy. The condenser cools the steam back into water, and the pump circulates the water back to the boiler.

What are the advantages of a Rankine cycle power plant?

One of the main advantages of a Rankine cycle power plant is its high efficiency. It can achieve efficiencies of up to 45%, making it one of the most efficient types of power plants. It also uses a closed-loop system, meaning the water is recycled and not released into the environment, reducing its environmental impact.

What are the limitations of a Rankine cycle power plant?

One limitation of a Rankine cycle power plant is that it requires a large amount of water for the steam to be produced. This can be a challenge in areas with limited water resources. Additionally, the burning of fossil fuels in these power plants contributes to air pollution and greenhouse gas emissions.

Similar threads

  • Engineering and Comp Sci Homework Help
Replies
4
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
675
  • Engineering and Comp Sci Homework Help
Replies
1
Views
574
  • Engineering and Comp Sci Homework Help
Replies
8
Views
4K
  • Engineering and Comp Sci Homework Help
Replies
9
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
4
Views
3K
  • Engineering and Comp Sci Homework Help
Replies
8
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
1
Views
3K
Replies
14
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
1K
Back
Top