calculating enthalpy of mixture from Peng-Robinson EOS
calculating enthalpy of mixture from Peng-Robinson EOS
(OP)
I know the equation for calculating the enthalpy of a mixture using Peng-Robinson. However, there is a derivative, d(am(T))/dT,
where am(T) = xi*xj*(a(T,i)*a(T,j))^(1/2)
a(T) = ac*(1+k*(1-(T/Tc)^(1/2))^2
k = 0.37464+1.54226*om - 0.26992*om^2
that I am having a difficult time solving. I used my TI-89 and it gave me an extremely long result. Does any one know the solution to this derivative or know where I may find it to verify my solution (which is too long to reproduce here)
Thanks!
where am(T) = xi*xj*(a(T,i)*a(T,j))^(1/2)
a(T) = ac*(1+k*(1-(T/Tc)^(1/2))^2
k = 0.37464+1.54226*om - 0.26992*om^2
that I am having a difficult time solving. I used my TI-89 and it gave me an extremely long result. Does any one know the solution to this derivative or know where I may find it to verify my solution (which is too long to reproduce here)
Thanks!





RE: calculating enthalpy of mixture from Peng-Robinson EOS
RE: calculating enthalpy of mixture from Peng-Robinson EOS
Have a read of this
http:/
or do a search on the net
RE: calculating enthalpy of mixture from Peng-Robinson EOS
RE: calculating enthalpy of mixture from Peng-Robinson EOS
ut I still reckon you should solve the derivative! maybe two pages of work max?
RE: calculating enthalpy of mixture from Peng-Robinson EOS
d(am)/dT = (xi.xj/2)(a(T,i).d(a(T,j))/dT + a(T,j).d(a(T,i))/dT)^(-0.5)
Now (and I did this very quickly so it is probably wrong) ...
da/dT = ac(k^2/Tc-ac.(T.Tc)^(-0.5).(1-k^2))
Also where is the dependance on i or j in the equation for a?
RE: calculating enthalpy of mixture from Peng-Robinson EOS
a(T) = ac(i)*(1+k*(1-(T/Tc(i))^(1/2))^2
k = 0.37464+1.54226*om(i) - 0.26992*(om(i))^2
ac, om, and Tc are component specific, therefore a(T) is different for each component and am(T) is the sumproduct of the following equation, where i, j are different components:
am(T) = (sumproduct of) xi*xj*(a(T,i)*a(T,j))^(1/2)
RE: calculating enthalpy of mixture from Peng-Robinson EOS
Read the FAQ ... ht tp://www.e ng-tips.co m/faqs.cfm ?pid=731&a mp;fid=376