# Transport Dispersive Model in CADET

**URL:** <https://forum.cadet-web.de/t/transport-dispersive-model-in-cadet/939>\
**Category:** Chromatography Modeling\
**Created:** [April 26, 2024, 2:53pm UTC](https://forum.cadet-web.de/t/transport-dispersive-model-in-cadet/939 "2024-04-26T14:53:53Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![nils.gehrmann1](https://forum.cadet-web.de/letter_avatar_proxy/v4/letter/n/dec6dc/32.png) [@nils.gehrmann1](https://forum.cadet-web.de/u/nils.gehrmann1)\
**Post date:** [April 26, 2024, 2:53pm UTC](https://forum.cadet-web.de/t/transport-dispersive-model-in-cadet/939/1 "2024-04-26T14:53:53Z")

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Hi everyone!

I want to use CADET to model breakthorugh curves using the Transport Dispersive Model:

![Formula TDM](https://forum.cadet-web.de/uploads/default/original/2X/3/35a59d83e1e59ed9a567931fc9c31503722fee39.png)

I am struggling with the formulas a bit. Is this equivalent to the ‘Lumped Rate Models with Pores’ in CADET?  
[https://cadet.github.io/master/modelling/unit\_operations/lumped\_rate\_model\_with\_pores.html](https://cadet.github.io/master/modelling/unit_operations/lumped_rate_model_with_pores.html)

Thank you and best regards  
Nils

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**Author:** ![j.breuer](https://forum.cadet-web.de/user_avatar/forum.cadet-web.de/j.breuer/32/1139_2.png) [@j.breuer](https://forum.cadet-web.de/u/j.breuer)\
**Post date:** [April 26, 2024, 3:17pm UTC](https://forum.cadet-web.de/t/transport-dispersive-model-in-cadet/939/2 "2024-04-26T15:17:10Z")

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Hi Nils,

The equation you’ve posted does look like the transport equation for the interstitial volume of the Lumped Rate Model With Pores (LRMP), assuming c\_p is the liquid concentration inside the pores and a\_f is the volumetric shape factor.  
The transport dispersive model that I usually see in literature is similar to our Lumped Rate Model Without Pores (LRM).  
The main difference between the models is that the LRMP additionally accounts for film diffusion into the particles, and thus describes two liquid phases: Liquid phase in the interstitial column volume/bulk, and liquid phase inside the pores, which can be subject to a binding model, i.e. can be adsorbed.  
The LRM assumes film diffusion to be non-limiting and thus does not differentiate between the aforementioned liquid phases.

Best regards,  
Jan

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**Author:** ![nils.gehrmann1](https://forum.cadet-web.de/letter_avatar_proxy/v4/letter/n/dec6dc/32.png) [@nils.gehrmann1](https://forum.cadet-web.de/u/nils.gehrmann1)\
**Post date:** [April 29, 2024, 8:39pm UTC](https://forum.cadet-web.de/t/transport-dispersive-model-in-cadet/939/3 "2024-04-29T20:39:55Z")

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Hi Jan,

thank you, that helps a lot!

Best  
Nils