8 replies to this topic

[ReeN]

Dear all,

I am a new member in this forum and i like it a lot because it gives me loads of useful information.
I have a question here, if I would like to model heat exchanger in dynamic state by using AspenTech HYSYS, how can it be done?
Besides that, what data is necessary and needed to complete the modelling?
Btw, I am a new user of HYSYS, there are lots of thing which i have to learn.

Thanks.

Regards,
Reen

[Zauberberg]

Reen,

This is a huge subject. Since you already mentioned that HYSYS modeling is a new thing in your life, the best you can do at the beginning is to go through complete set of tutorials related to Simulation Basis and Operations Guide: there you'll find how to set the basic input data required for accurate simulation: true and hypothetical components selection/generation, appropriate thermo-model(s), correlation set etc. Detailed explanation of heat exchanger modeling is also included in the Operations Guide. If you have someone more experienced in HYSYS modeling by your side, it would be very convenient. First steps are the most important, in my opinion.

Dynamic modeling is somewhat more complicated and is a part of Dynamic Modeling tutorial, where the basics of dynamics and control theory and applications are explained: how to set required inputs and switch from steady-state to dynamic simulation, use basic or advanced type of control etc.

Best of luck,

[ReeN]

I've learnt how to model hysys in dynamic state for last few days.
but i just found one problem, can i model the double pipe heat exchanger by Aspen HYSYS? it seems like only applicable to TEMA type heat exchanger. I do not have the Aspen Tasc, just Aspen HYSYS.

Thank you so much.

[Zauberberg]

Double-pipe heat exchangers involve true counter-current flow, and it depends what are you trying to model: full set of heat exchangers parameters in steady-state or dynamic operation, pressure drop, heat transfer rate/change, or maybe you are interested only in system duty. In such case, I think you actually don't need HYSYS for your calculations: simply recall basic heat transfer equations and it will be easy for you to calculate and solve this system.

What exactly are you trying to model, and what is the purpose of heat exchanger simulation?

Best regards,

[ReeN]

I am actually need to model a hairpin Heat exchanger (as in attached file) in dynamic state by using Aspen HYSYS. I need to use this model to check the performance of the Heat Exchanger at different temperature. Therefore i will need to do the simulation in HYSYS.

Thank you.

Attached Files

•  Multitube_HE.doc   66KB   167 downloads

[Zauberberg]

For this type of application I think you can use one of these two approaches:

1. E-shell TEMA exchanger with single tube pass and counter-current flow pattern. And split your exchanger in two equivalent parts (upper and lower exchanger). This way, you will have two heat exchangers in HYSYS flowsheet representing your application.
2. F-shell TEMA exchanger with two tube passes and counter-current flow pattern.

The difference between TEMA and hairpin heat exchangers is the presence of baffles in the former type. But since you are interested only in thermal performance, I think this will serve the purpose.

Best regards,

[ReeN]

Zauberberg,

I would like to use first approach.
Thank you for your reply

Reen

[ReeN]

One more question..
How about the heat transfer at U bend?
i will have to ignore that if i use the first approach.

Can i assume it is a long single pass shell and tube heat exchanger?

[Zauberberg]

Simply add the length of U-bend to the tube length in E-shell exchanger. This number should be very small compared to double-pipe or hairpin total exchanger length, and the influence on final result is negligible.

Of course, all these guidances apply only if you are interested in overall thermal performance of an exchanger - without getting deepful insight in hydraulics and heat transfer issues.

Regards,