- #1
maistral
- 235
- 17
So I wanted to create an enthalpy-concentration diagram generator in Excel using Dalton's Law and Raoult's Law (ideal stuff).
The problem is with the formulation. I studied and used this .pdf file form a university in HK:
http://ihome.ust.hk/~kexhu/ceng3210/221-05.pdf
Seeing as it also agrees with this paper in SA:
http://faculty.ksu.edu.sa/Emad.Ali/mylib/CHE411/CH3.pdf
I then decided to give it a roll. I managed to do their computations in an Excel spreadsheet with the reference temperature equal to the boiling point of the lighter component.
The problem began to appear when I changed the reference temperature. Changing the reference temperature totally changed the values of the intermediate enthalpies. If I am correct, the difference in enthalpies for the vapor lines and the liquid lines must be constant whatever the reference temperature is. I then backtracked to the previous example by the .pdf files, the computations seem to be correct. The changes in enthalpy for (0,0) and (1,1) of the VLE were held constant, though.
I managed to whip up an Excel spreadsheet for it. I'm hoping you guys could pinpoint what I did wrong, or did I miss something else. And yes, this again wasn't discussed in our undergraduate studies (lol). This is the link for the file:
http://media.angelfire.lycos.com/5684886/2337329.xlsx
The problem is with the formulation. I studied and used this .pdf file form a university in HK:
http://ihome.ust.hk/~kexhu/ceng3210/221-05.pdf
Seeing as it also agrees with this paper in SA:
http://faculty.ksu.edu.sa/Emad.Ali/mylib/CHE411/CH3.pdf
I then decided to give it a roll. I managed to do their computations in an Excel spreadsheet with the reference temperature equal to the boiling point of the lighter component.
The problem began to appear when I changed the reference temperature. Changing the reference temperature totally changed the values of the intermediate enthalpies. If I am correct, the difference in enthalpies for the vapor lines and the liquid lines must be constant whatever the reference temperature is. I then backtracked to the previous example by the .pdf files, the computations seem to be correct. The changes in enthalpy for (0,0) and (1,1) of the VLE were held constant, though.
I managed to whip up an Excel spreadsheet for it. I'm hoping you guys could pinpoint what I did wrong, or did I miss something else. And yes, this again wasn't discussed in our undergraduate studies (lol). This is the link for the file:
http://media.angelfire.lycos.com/5684886/2337329.xlsx