5 replies to this topic

[Said Salim]

Dear All,

 

I am calculating the change of the enthalpy of a system using this equation:

     

dH= ∫ Cp dT.

However, I am using fomula used Perry's to calculate Cp of ideal gas but I need the integral of this equation:

cp=c1+c2*(c3/t/(sinh(c3/t))^2+c4(c5/t/cosh(c5/t))^2

where,

c1, c2, c3, c4 & c5 are constants and t is the temperature in K

 

anyone can help to find the integral form

Edited by Said Salim, 12 June 2014 - 06:29 AM.

[breizh]

Said .

 

thanks to share the reference ( Perry edition &page)  and product name !

I would expect a polynomial . 

 

Breizh

Edited by breizh, 12 June 2014 - 07:31 AM.

[MrShorty]

This equation is often called the Ally and Lee equation: http://www.trc.nist....0/AlyLeeCp0.htm

 

I expect you should be able to get a hold of Ally and Lee's original publication (http://www.sciencedi...378381281850029) and see how they derived the equation for H.

 

With an integral table and your own skill at deriving antiderivatives, you should be able to come up with your own formula. http://en.wikipedia....bolic_functions

[Said Salim]

Hello Dear Sir,

 

The reference is Perry 7th Edition Page (2-182)

 

Regards

[PingPong]

 

However, I am using fomula used Perry's to calculate Cp of ideal gas but I need the integral of this equation:

cp=c1+c2*(c3/t/(sinh(c3/t))^2+c4(c5/t/cosh(c5/t))^2

 

The number of brackets in your equation is not correct, the bracket just before sinh should not be there.

It should be: c1+c2*(c3/x/sinh(c3/x))^2+c4(c5/x/cosh(c5/x))^2

in which I also replaced t by x to allow integration by website software.

 

Copy/paste that corrected formula into the window of the Wolfram website (overwrite example that is already there) and press the blue button:

 Cp Integration.jpg   64.43KB   10 downloads

 

http://integrals.wolfram.com/index.jsp

Edited by PingPong, 16 June 2014 - 04:43 AM.

[Said Salim]

Thanx alot Sir.

I appreciate you response..