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[deltaChe]

I tried to find out the latent heat of a mixture by using aspen plus.
Step 1. I defined the stream 1 represent the equal molar ratio of mixture compound,propane and p-xylene. Then I define te flash drum 1 and set up the pressure drop = 0, but don't know how to set up the other variable of the flash drum 1.
Step 2. I defined the stream 2, stream 3, and the flash drum 2. Then I set up the pressure drop = 0 and heat duty = 0 in the flash drum 2, and stream 3 leave flash drum 2 as a vapor phase.

Step 3. I defined the stream 4 leaving the flash drum 2 and enterng the flash drum 3.
Then I set up the pressure drop =0 in the flash drum 3.

I am confused how to assign the desire vapor fraction 5% in which flash drum, and how to get the latent heat by
substracting stream from which stream.

Hope you can understand what I wrote, I know I may wrote unclear.
Thank you.

[sheiko]

In order to determine the total latent heat of vaporization of a mixture, i would simply follow these steps:

Step 1: Designate a material stream, denoted as "stream 1", to represent the mixture in fully liquid phase at its bubble point; specify its composition and pressure, and assign a vapor fraction of 0 (representing bubble point)

Step 2: Designate a second stream, denoted as "stream 2", having the same composition and pressure as "stream 1" but assign a vapor fraction of 1 (representing the dew point).

Step 3: Since the composition of "stream 1" is equal to that of "stream 2", the latent heat, is the difference between the specific enthalpies of the two streams.

Edited by sheiko, 04 May 2010 - 07:10 AM.