Optimizing Gas-Turbine Cycle Network
10 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary reason for operating gas turbines at four times the air needed for complete combustion?

  • To reduce excessive temperatures (correct)
  • To increase thermal efficiency
  • To decrease fuel consumption
  • To increase power output

    • What happens to the working fluid temperature when intercooling and reheating are utilized?

  • It decreases at both the compressor and turbine
  • It increases at the compressor and decreases at the turbine
  • It decreases at the compressor and increases at the turbine (correct)
  • It increases at both the compressor and turbine

    • Why does the back work ratio of a gas-turbine cycle improve with intercooling and reheating?

  • Because the turbine exhaust temperature increases
  • Because the thermal efficiency increases
  • Because the regeneration potential increases (correct)
  • Because the compressor inlet temperature decreases

    • What is the effect of intercooling and reheating on the thermal efficiency of a gas-turbine cycle?

    <p>It decreases the thermal efficiency unless accompanied by regeneration</p> Signup and view all the answers

    What is the ideal limit of thermal efficiency that can be approached by a gas-turbine cycle with intercooling, reheating, and regeneration?

    <p>The Carnot efficiency</p> Signup and view all the answers

    What is the primary goal of multistage compression with intercooling in a gas-turbine cycle?

    <p>To decrease the compression work by reducing the specific volume of the fluid</p> Signup and view all the answers

    What happens to the compression process as the number of stages is increased?

    <p>The compression process becomes isothermal at the compressor inlet temperature</p> Signup and view all the answers

    What is the effect of reheating on the expansion process in a gas-turbine cycle?

    <p>It increases the expansion work output without raising the maximum temperature</p> Signup and view all the answers

    What is the principle behind the effect of multistage compression with intercooling and multistage expansion with reheating on the net work output?

    <p>The steady-flow work is proportional to the specific volume of the fluid</p> Signup and view all the answers

    What is the ultimate goal of optimizing the compression and expansion processes in a gas-turbine cycle?

    <p>To increase the net work output of the cycle</p> Signup and view all the answers

    Study Notes

    Net Work of a Gas-Turbine Cycle

    • Net work is the difference between turbine work output and compressor work input
    • Net work can be increased by decreasing compressor work, increasing turbine work, or both

    Multistage Compression with Intercooling

    • Compression work can be decreased by carrying out compression in stages and cooling the gas in between
    • As the number of stages increases, the compression process becomes nearly isothermal at the compressor inlet temperature
    • Compression work decreases as the number of stages increases

    Multistage Expansion with Reheating

    • Turbine work output can be increased by expanding the gas in stages and reheating it in between
    • Expansion process becomes nearly isothermal as the number of stages increases
    • Maximum temperature in the cycle remains unchanged

    Principle of Work

    • Steady-flow compression or expansion work is proportional to the specific volume of the fluid
    • Specific volume of the working fluid should be as low as possible during compression and as high as possible during expansion
    • Intercooling and reheating accomplish this by reducing and increasing specific volume, respectively

    Combustion in Gas Turbines

    • Combustion typically occurs with four times the amount of air needed for complete combustion to avoid excessive temperatures
    • Exhaust gases are rich in oxygen, allowing reheating by spraying additional fuel between expansion states

    Effects of Intercooling and Reheating

    • Working fluid leaves the compressor at a lower temperature and the turbine at a higher temperature
    • Makes regeneration more attractive and increases potential for regeneration
    • Back work ratio of a gas-turbine cycle improves
    • Thermal efficiency decreases unless accompanied by regeneration

    Ideal Gas-Turbine Cycle

    • Ideal cycle with intercooling, reheating, and regeneration approaches the Ericsson cycle
    • Thermal efficiency approaches the theoretical limit (Carnot efficiency) as the number of stages increases
    • However, the contribution of each additional stage to thermal efficiency is less and less, and more than two or three stages are not economically justified

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    This quiz covers the principles of optimizing gas-turbine cycle network by decreasing compressor work or increasing turbine work, including multistage compression with intercooling. It's based on Chapter 7 and Fig. 9-42.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser