Boiling Point Elevation

azikorus-disabl · ‎Jul 14, 2009

Collab,

I am trying to calculate the elevation in boiling point as glycerol is added to water.

On the attached worksheet, I attempted to work from an online example by have a problem with the units.

Also, the expressions do not allow for very high concentration of glycerol in the calculation.

Any comments would be appreciated.

Thanks,

Art

ViktorKorobov · ‎Jul 15, 2009

1.Incorrect units.
Temperature elevation constant must be 0.521 C/mol/kg
Viktor Korobov

Viktor

ValeryOchkov · ‎Jul 15, 2009

... and water boiling point (at normal pressure) is not 100K but 373.15K (100C)
Val
http://twt.mpei.ac.ru/ochkov/v_ochkov.htm

ptc-1368288 · ‎Jul 15, 2009

1. Incorrect units.
Temperature elevation constant must be 0.521 C/mol/kg [Viktor]
2. ... and water boiling point (at normal pressure) is not 100K but 373.15K (100C) [Val]
3. ... boiling point(s) are function of absolute pressure
... the formulation does not look correct [jmG]

azikorus-disabl · ‎Jul 15, 2009

Thanks All,

Viktor's unit correction seemed to be the issue.

There still is an issue as the concentration of glycerol approaches 100%. Does anyone have any thoughts on that?

Art

ptc-1368288 · ‎Jul 15, 2009

On 7/15/2009 12:11:05 PM, ArtZ wrote:
>Thanks All,
>
>Viktor's unit correction
>seemed to be the issue.
>
>There still is an issue as the
>concentration of glycerol
>approaches 100%. Does anyone
>have any thoughts on that?
>
>Art
_______________________________

The issue is that the formulation is incorrect. A problem of same nature as: how much to mix component of x% with component of y% for a resulting z%.

jmG

ptc-1368288 · ‎Jul 15, 2009

Art,

Work directly in Engineering system.

jmG

ValeryOchkov · ‎Jul 16, 2009

On 7/15/2009 12:11:05 PM, ArtZ wrote:
>Thanks All,
>
>Viktor's unit correction
>seemed to be the issue.
>
>There still is an issue as the
>concentration of glycerol
>approaches 100%. Does anyone
>have any thoughts on that?
>
>Art
One picture for this subject:

Val
http://twt.mpei.ac.ru/ochkov/v_ochkov.htm

ViktorKorobov · ‎Jul 16, 2009

Glycerol-water mixtures: Boiling points in attached.
Viktor Korobov

Viktor

ViktorKorobov · ‎Jul 16, 2009

..and saved in MC11 format.
Viktor Korobov

Viktor

ptc-1368288 · ‎Jul 16, 2009

On 7/16/2009 9:26:13 AM, vikkor wrote:
>..and saved in MC11 format.
>Viktor Korobov
____________________________

Tanks Viktor,

Recreated in 11,
as your saved 11 version is scraped
but could be recuperated !

jmG

ptc-1368288 · ‎Jul 16, 2009

Art,

Here is saved 2001i.

azikorus-disabl · ‎Jul 16, 2009

Jean,

Thanks for recovering the file. I have MC2001i and MC13 and couldn't read Viktor's files at all.

Did Viktor cite his source of data in his postings?

If the glycerol mole fraction is 100% wouldn't that represent the BP of 290�C? Seems the x scale is reversed.

The funny step as the glycerol mole fraction --> 100% doesn't seem correct. I'd expect a smooth transition.

Since I am working in mass fraction, I'll need to convert from mole fraction.

Art

ViktorKorobov · ‎Jul 16, 2009

On 7/16/2009 1:41:21 PM, ArtZ wrote:
>Jean,
>
>Thanks for recovering the
>file. I have MC2001i and MC13
>and couldn't read Viktor's
>files at all.
>
>Did Viktor cite his source of
>data in his postings?
>
>If the glycerol mole fraction
>is 100% wouldn't that
>represent the BP of 290�C?
>Seems the x scale is reversed.
>
>The funny step as the glycerol
>mole fraction --> 100% doesn't
>seem correct. I'd expect a
>smooth transition.
>
>Since I am working in mass
>fraction, I'll need to convert
>from mole fraction.
>
>Art

Sorry, see revised variant.
Viktor Korobov

Viktor

ptc-1368288 · ‎Jul 16, 2009

Art,

This work sheet 2001i, is Viktor in mol fraction,
with a slight correction on the 'x' marker.

Jean

azikorus-disabl · ‎Jul 17, 2009

Jean/Viktor,

On the attached worksheet, I have converted the mole fraction values from Viktor to mass fractional.

I was surprised to find that the relationship between mass fraction and boiling point is likely linear.

Viktor, where did you get the mole fraction values versus boiling point.

Please let me know if I didn't do the conversion correctly.

Thanks,

Art

ptc-1368288 · ‎Jul 17, 2009

>I was surprised to find that the relationship between mass fraction and boiling point is likely linear<<br> _________________________

The question is really what are you looking for ?

Jean

azikorus-disabl · ‎Jul 17, 2009

Jean,

I am using glycerol/water mixtures as a stable, variable thermal load.

You may recall that previously, a worksheet with thermal conductivity versus mass fraction was posted.

Recently, I obtained data on heat capacity versus glycerol mass fraction.

With the addition of the boiling point versus mass fraction, I can customize my thermal loads for all three parameters.

Art

ptc-1368288 · ‎Jul 17, 2009

On 7/17/2009 5:56:23 PM, ArtZ wrote:
>Jean,
>
>I am using glycerol/water
>mixtures as a stable, variable
>thermal load.
>
>You may recall that
>previously, a worksheet with
>thermal conductivity versus
>mass fraction was posted.
>
>Recently, I obtained data on
>heat capacity versus glycerol
>mass fraction.
>
>With the addition of the
>boiling point versus mass
>fraction, I can customize my
>thermal loads for all three
>parameters.
>
>Art
_____________________________

Art,

I'm trying to understand that given a volume of glycol p2 you want the temperature of the mixture as function of the variable p1 volume of water.

Does it make sense if you put correct b1, b2 as per handbooks ? The linearity depends upon b1, b2 (which I don't have off hand).

Jean

ViktorKorobov · ‎Jul 18, 2009

Art,

I think your mole/mass conversion is wrong. See attach.

Viktor Korobov

Viktor

azikorus-disabl · ‎Jul 20, 2009

Viktor,

Thanks for your post; that is a lot work! I am just now looking at your worksheet and don't completely follow what you have done.

From your work, it appears that boiling point is very non-linear.

I may have asked you in an earlier post and you may have responded, however, could you name the source of your original boiling point versus mole fraction data?

Thanks again,

Art

ptc-1368288 · ‎Jul 20, 2009

>versus mole fraction data<<br>
That complicates matter, just go by my formula. It does the mole fraction algebraically, look at the formula again where you simply put the weight or the mass if you prefer. The formula is the "homographic function", one form of it, an expanded form of 1/x. For sure it is not linear, it is of the reciprocal form, i.e: a rational fraction. Also, you must understand that you need the specific heat capacity of each component.

Just reproduce the attached, fill-in the respective data.

Jean