Get Help

Turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

- Community
- :
- PTC Mathcad
- :
- PTC Mathcad
- :
- Differntial-algebraic equation DAE - chemical reac...

Options

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

Highlighted
##

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

05-15-2017
11:17 AM

05-15-2017
11:17 AM

Differntial-algebraic equation DAE - chemical reactor

Hi,

I have a question to solve a DAE-system of a chemical reactor. In the picture you can see a minimal example. Its a simple reaction A to B with a first order kinetic multiplicated with an arhenius equation and an empirical pressure factor. To solve the DGL system, I have to predict the pressure p, wich depends on the mol fractions and temperatur. So this is my algebraic equation. This equation is combined with a DGL of the energy balance and two mass balnce. How can I solve such a system? With the example of mathcad, i can't solve this. Is there a simple way or standard method? I want to solve the system with RADAU so i have to built the vector function D. How i have to implement the pressure equation?

Thanks for your help

Labels:

8 REPLIES 8

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

05-15-2017
01:38 PM

05-15-2017
01:38 PM

Re: Differntial-algebraic equation DAE - chemical reactor

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

05-15-2017
02:29 PM

05-15-2017
02:29 PM

Re: Differntial-algebraic equation DAE - chemical reactor

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

05-15-2017
02:51 PM

05-15-2017
02:51 PM

Re: Differntial-algebraic equation DAE - chemical reactor

F.M. написал(а):

It is not a temperature - it is one coefficient?

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

05-16-2017
02:32 AM

05-16-2017
02:32 AM

Re: Differntial-algebraic equation DAE - chemical reactor

It is evident that the unit of measurement is incorrect. He must use the most appropriate one.

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

05-16-2017
05:27 AM

05-16-2017
05:27 AM

Re: Differntial-algebraic equation DAE - chemical reactor

It is a simplification of an antoine-equation. Its a fit parameter.

The equation of arhenus was wrong. I correct it. But i only need the method to solve a DAE. The values of the parameters are only for the prediction. they are not messured or physically correct.

@

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

05-16-2017
08:59 AM

05-16-2017
08:59 AM

Re: Differntial-algebraic equation DAE - chemical reactor

As an interesting aside, negative absolute temperatures are actually possible. Although they are hotter than infinite temperature ...

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

05-16-2017
10:14 AM

05-16-2017
10:14 AM

Re: Differntial-algebraic equation DAE - chemical reactor

... it sounds to me almost as if I say something goes at a speed v> c. I agree that numerically everything is possible...

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

05-16-2017
10:33 AM

05-16-2017
10:33 AM

Re: Differntial-algebraic equation DAE - chemical reactor

Before anyone spends time on this, you need to resolve all the typographical errors in the Mathcad worksheet.

For example, in the parameters you have m_FA, but in the equations you have m_AF, etc

Top Tags