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Help Calculating Enthalpy

  • 1.  Help Calculating Enthalpy

    Posted 14 days ago
    Edited by Claire Schiefelbein 14 days ago
    ​Hey guys, I'm trying to calculate the enthalpy of some streams for a materials and energy balance, but I'm not sure that I have all the data I need. I know the operating temperature and pressure, and I have SDS for all the materials, but that doesn't include specific heat, which I thought was necessary to calculate the enthalpy? Am I just going about this the wrong way?​


  • 2.  RE: Help Calculating Enthalpy

    Posted 14 days ago
    Hello Claire,

    I understood your question but, i think I can't give a perfect explanation regarding this matter.
    According to your question,
    Yes,you do need Specific Heat for your calculation of enthalpy.

    ---------------------------------
    Vijay Jadeja
    Gujarat technological university,
    Gujarat,
    India.
    ---------------------------------





  • 3.  RE: Help Calculating Enthalpy

    EXECUTIVE STUDENT
    COMMITTEE
    Posted 14 days ago
    Hey @Claire Schiefelbein, are you looking to calculate the change in enthalpy? Do you know your reference point?​

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    Anna Wagner
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  • 4.  RE: Help Calculating Enthalpy

    EXECUTIVE STUDENT
    COMMITTEE
    Posted 13 days ago
    Hey Claire! In case you want to calculate the change in Enthalpy for each stream, here are some steps to help you:

    1- Pick a reference temperature and a reference state for your stream.
    2- Get the specific heat constants (A, B, C, and D) for each component using your textbook (reference), then apply them into the specific heat equation "f(temperature)".
    3- You can use the operating temperature to calculate the vapor pressure using Antoinne equation (in case you need it).
    4- Calculate the change in specific Enthalpy between your reference temperature and the operating temperature. (Don't forget the latent heat if you have to use it)
    5- Multiply the specific enthalpy of each component by its corresponding composition (In the material balance) then calculate the sum of these products (you can use (sumproduct) function in your excel spreadsheet).

    I hope this helps you and that I got your question right

    ------------------------------
    Ahmad Muhmmad
    Cairo
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  • 5.  RE: Help Calculating Enthalpy

    EXECUTIVE STUDENT
    COMMITTEE
    Posted 13 days ago
    Tutor me please @Ahmad Muhmmad! Very nice.

    Also, @Claire Schiefelbein, you can use Knovel to look up the Antoine coefficients that Ahmad was referencing. If you limit your search to Graphs/Tables and use the "Equation plotter" then Knovel can run the calculations for you.

    ​​​You can access Knovel with your AIChE student membership here.

    Good luck!

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    Anna Wagner
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  • 6.  RE: Help Calculating Enthalpy

    Posted 11 days ago
    Ahmad, Nice explanation...

    ---------------------------------
    Vijay Jadeja
    Gujarat technological university,
    Gujarat,
    India.
    ---------------------------------





  • 7.  RE: Help Calculating Enthalpy

    Posted 11 days ago
    ​Thanks for the help guys; that's a really thorough explanation! Unfortunately, the part I'm stuck on is that my textbook doesn't have specific heat values for some of the components of the streams, and I haven't had much luck finding them anywhere else


  • 8.  RE: Help Calculating Enthalpy

    EXECUTIVE STUDENT
    COMMITTEE
    Posted 9 days ago
    Thank you guys!

    Hey @Claire Schiefelbein , I think you can find them in the Appendix of Coulson Richardson's Chemical Engineering Design. Please let me know if you can't reach it.

    ------------------------------
    Ahmad Muhmmad
    Cairo
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  • 9.  RE: Help Calculating Enthalpy

    Posted 8 days ago
    Hi
    I think that also you can find entalpies on 

    Жоров Ю.М. Термодинамика химических процессов

    Good luck 





  • 10.  RE: Help Calculating Enthalpy

    Posted 8 days ago
      |   view attached
    We're all here to help, I think this is the textbook @Ahmad Muhmmad is referring you to. check the attached file.

    ------------------------------
    Mubarak
    GDUPT, China
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