I changed the property model to NRTL, and Also UNIFAC.
after investigation I saw NRTL has around 15-20% deviation from data that given by Batista.
"http://pubs.acs.org/....1021/je9900169"
and the result for UNIF-LL has to much deviation from his data.
Which parameter should change to get the better result? and How can I add new UNIFAC group interaction parameters to aspen plus.
Thanks for your advice
Edited by Mehrbod, 11 October 2012 - 01:56 PM.