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How to calculate Enthalpy in j/mol.kg in ansys ?

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Old   November 22, 2018, 09:13
Default How to calculate Enthalpy in j/mol.kg in ansys ?
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Hi
I have some confusion about how ansys calculates enthalpy in j/mol.kg
I have seen many answers that says just multiply enthalpy of a material by the its molecular weight but that simply does not make sense for me because : enthalpy is in j/kg and molecular weight is in kg/mol so the resultant dimension would be j/mol not j/mol.kg as required by ansys?
may be this naive question but I am new to ansys and fluid mechanics in general and my background is mainly in computer engineering

Thanks
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Old   November 26, 2018, 13:14
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Enthalpy is indeed J/kg or J/mol. I think you are confusing J/kgmol as being kg*mol. A kgmol is not kg*mol but a type of mol.
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Old   November 28, 2018, 10:16
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so if for example, the enthalpy is 2000 j/mol, how to convert it to j/kgmol?
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Old   November 29, 2018, 10:43
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Believe it or not, 2000 J/mol is 2000 000 J/kgmol or 2000 kJ/kgmol
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Old   December 19, 2019, 06:35
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Hi
Actually standard state of enthalpy of CO2 is -393.5 kJ/mol but in fluent the database value of CO2 is -3.935324e+08 J/kg mol. How this is possible??? whether the unit is correct as mentioned before?
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Old   May 14, 2020, 10:01
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kgmol is not kg*mol. It is like a kilo mol.
So 1kgmol = 1000 mol.
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Old   May 20, 2020, 04:35
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Quote:
Originally Posted by Sowmiya View Post
Hi
Actually standard state of enthalpy of CO2 is -393.5 kJ/mol but in fluent the database value of CO2 is -3.935324e+08 J/kg mol. How this is possible??? whether the unit is correct as mentioned before?
Hi Sowmiya,

that is correct. In fact you need to multiply by a factor 1000 to go from kJ to J. Moreover, you need to divide by a factor 1000 to go from mol to kmol (let's remember that the lowercase letter 'k' means 'kilo' which is, I think, ancient Greek for 'a thousand'). Thus, being that at the denominator, you need to multiply everything by 1000.
So, 3 digits because of kJ + 3 digits because of kmol + 2 digits for scientific notation and there you go you have your e+08.
Hope it helps,
Marco
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