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  1. #1
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    Thermodynamic properties equation



    Hi all

    I need some help here. i need to manually calculate the thermodynamic properties of few refrigerants such as R134A etc. I am pretty much unsure of what equations i should use.
    There are few thermodynamic properties table online ( such as NIST ) but my lecturer does not allow me to refer to.

    I have previously used EES ( engineering equation solver ) to obtain the properties. but again my lecturer does not agree to it.

    I need these these thermodynamic properties such as specific enthalpy and entropy to design thermodynamic cycle , Organic Rankine cycle.

    The thermodynamic properties table by NIST however shows the principal equation to calculate the pressure. But I do not know how to derive the equation in order to calculate the entropy and enthalpy.


    It would be very great if someone can share anything on those equations. Thanks



  2. #2
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    Re: Thermodynamic properties equation

    Hi, hafiza ... welcome to RE forums ...

    maybe you can tell us something more about yourself here .... http://www.refrigeration-engineer.co...p?72-New-to-RE ... then you can search RE and find a lot of very good information ... links ... etc ...

    Quote Originally Posted by hafiza View Post
    Hi all

    I need some help here. i need to manually calculate the thermodynamic properties of few refrigerants such as R134A etc. I am pretty much unsure of what equations i should use.
    There are few thermodynamic properties table online ( such as NIST ) but my lecturer does not allow me to refer to.

    I have previously used EES ( engineering equation solver ) to obtain the properties. but again my lecturer does not agree to it.

    I need these these thermodynamic properties such as specific enthalpy and entropy to design thermodynamic cycle , Organic Rankine cycle.

    The thermodynamic properties table by NIST however shows the principal equation to calculate the pressure. But I do not know how to derive the equation in order to calculate the entropy and enthalpy.


    It would be very great if someone can share anything on those equations. Thanks
    As your lecturer is asking you to do all by yourself here is the nice program CoolPack where you can find all what you need:

    CoolPack is a collection of simulation models each with a specific purpose. The following simulation purposes are covered:

    • Cycle analysis (process design)
    • System dimensioning
    • System simulation
    • Component calculations
    • Analysis of operating conditions
    • Transient simulation (cooling of an object/room)
    • Refrigerant calculations (property plots, thermodynamic & transport properties, comparison of refrigerants)
    • Life cycle cost (LCC)


    ... http://www.en.ipu.dk/Indhold/refrige.../coolpack.aspx ... it is free to download and then play with ...

    Hope it will be of some help to you ...

    Best regards, Josip

    It's impossible to make anything foolproof because fools are so ingenious...

    Don't ever underestimate the power of stupid people when they are in large groups.

    Please, don't teach me how to be stupid....
    No job is as important as to jeopardize the safety of you or those that you work with.

  3. #3
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    Re: Thermodynamic properties equation


  4. #4
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    Re: Thermodynamic properties equation

    Quote Originally Posted by Josip View Post
    Hi, hafiza ... welcome to RE forums ...

    maybe you can tell us something more about yourself here .... http://www.refrigeration-engineer.co...p?72-New-to-RE ... then you can search RE and find a lot of very good information ... links ... etc ...



    As your lecturer is asking you to do all by yourself here is the nice program CoolPack where you can find all what you need:

    CoolPack is a collection of simulation models each with a specific purpose. The following simulation purposes are covered:

    • Cycle analysis (process design)
    • System dimensioning
    • System simulation
    • Component calculations
    • Analysis of operating conditions
    • Transient simulation (cooling of an object/room)
    • Refrigerant calculations (property plots, thermodynamic & transport properties, comparison of refrigerants)
    • Life cycle cost (LCC)


    ... http://www.en.ipu.dk/Indhold/refrige.../coolpack.aspx ... it is free to download and then play with ...

    Hope it will be of some help to you ...

    Best regards, Josip


    Thanks Josip for the coolpack. will check it out.

    err.. did I open this thread in a wrong place since I am a newbie ?

  5. #5
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    Re: Thermodynamic properties equation

    Quote Originally Posted by narkom View Post


    Thanks Narkom !

    I ve found the equations finally .

    I have downloaded other Duropont table for R134A and it does not contain the equations like the one you gave.

    Can I use the same equations then for r134a ? but the constants will vary isnt it


    thanks

  6. #6
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    Re: Thermodynamic properties equation

    Equations for R134a can be found here
    http://chlazeni.kovosluzbaots.cz/chl...diva/r134a.pdf

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