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H-H25 Cp Calculation


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#1 coolgoh98

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Posted 27 October 2019 - 03:26 AM

Hi, this is my first post. Please forgive my grammar mistake. 
 
I am doing the H-H25 energy balance for scrubber. After cross check with old excel provided by my superior. I found out the integration is different. 
 
For example, to calculate H-H25 of O2 at 300 C, I integrate the heat capacity correlation and form the following formula.

h_25 = (a * T + 1 / 2 * b * T ^ 2 + 1 / 3 * c * T ^ 3 + 1 / 4 * d * T ^ 4 + 1 / 5 * e * T ^ 5) / M - (a * 298.15 + 1 / 2 * b * 298.15 ^ 2 + 1 / 3 * c * 298.15 ^ 3 + 1 / 4 * d * 298.15 ^ 4 + 1 / 5 * e * 298.15 ^ 5)
 
however I found out that the excel is using 
h_25 = (a * T + 2 * b * c / (exp(2 * c / T) - 1) + 2 * d * e / (exp(2 * e / T) + 1) - a * 298.15 - 2 * b * c / (exp(2 * c / 298.15) - 1) - 2 * d * e / (exp(2 * e / 298.15) + 1)
 
My question is, why they are using different integration method

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#2 breizh

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Posted 27 October 2019 - 06:32 AM

https://www.cheric.o...d=1935&prop=CPG

 

Hi,

Not using the same correlation ! 

note : the coefficients a,b,c,d  are not the same ….

 

I've added a link to a Korean Data base which is using a similar polynomial form .

Good luck

Breizh 


Edited by breizh, 27 October 2019 - 09:19 PM.


#3 breizh

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Posted 28 October 2019 - 12:37 AM

Hi ,

To add to my previous reply other correlations with range of applicability .

Document issued by Ankur (moderator in this forum)  a few years ago.

Good luck

Breizh

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Edited by breizh, 28 October 2019 - 12:46 AM.


#4 coolgoh98

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Posted 28 October 2019 - 06:32 AM

Hi ,

To add to my previous reply other correlations with range of applicability .

Document issued by Ankur (moderator in this forum)  a few years ago.

Good luck

Breizh

 

 

https://www.cheric.o...d=1935&prop=CPG

 

Hi,

Not using the same correlation ! 

note : the coefficients a,b,c,d  are not the same ….

 

I've added a link to a Korean Data base which is using a similar polynomial form .

Good luck

Breizh 

 

 

 

Hi Breizh,

 

Really appreciate your time and help. I just got to know there is different coefficient for this calculation. 

It raised another question. which coefficient is more accurate ? The temperature range is around 25c to 500 c


Edited by coolgoh98, 28 October 2019 - 06:32 AM.


#5 breizh

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Posted 28 October 2019 - 07:05 AM

Hi ,

It's up to you ….!

To me the polynomial form is good enough for this type of calculation [design of a scrubber ].

note : Do the math and make your own conclusion .

My view only.

Breizh


Edited by breizh, 28 October 2019 - 07:44 AM.





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