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Thermal Compression + Expansion Index

  1. Mar 28, 2008 #1
    Could anyone tell me what the compression and expansion is used for in a Thermodynamics situation?

    What is the notation for Compression and Expansion in a formula?

    I am trying to calculate work done by a heat engine.

  2. jcsd
  3. Apr 7, 2008 #2
    Hi there:

    In general, compression is used to compress the working fluid, increase the pressure -- pressurized the working fluid. Work and/or power input are required to do so. In an ideal case, isentropic compression is used.

    In general, expansion is used to expand the working fluid, reduce the pressure -- expand the working fluid. Work and/or power output are generated. In an ideal case, isentropic expansion is used.

    Here are two URLs when dealing with compression and expansion.

    Theoretical background information on compression and expansion:
    http://members.aol.com/engware/components.htm [Broken]

    Online calculators dealing with compression and expansion:
    http://members.aol.com/engware/calc4.htm [Broken]

    In order to get the full meaning of compression and expansion with respect to the operation of simple power cyles, here are two more URLs dealing with simple power cycles (Carnot, Brayton, Otto and Diesel).

    Theoretical background information on simple power cycles:
    http://members.aol.com/engware/cycles.htm [Broken]

    Online calculators dealing with simple power cycles:
    http://members.aol.com/engware/calc3.htm [Broken]

    Here are two plots regarding the compression power input and expansion power output.



    I do hope that the provided URLs will be useful to you when dealing with theoretical background and doing related basic engineering calculations.


    Last edited by a moderator: May 3, 2017
  4. Apr 11, 2008 #3
    Thanks for those urls, they have done the trick, I have read, understood, and now completed, so thanks for all the help, most appreciated...
  5. Apr 11, 2008 #4

    No problem.


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