11 replies to this topic

[robertors]

Dear community,

 

I'am a mechanical engineering student. Currently I am trying to simulate an adsorption chiller in ASPEN Plus or even in ASPEN Adsorption module, I am relatively new in such software.

 

Shortly, In the attempt of simulating the process, I have found the next problems:

1. Find the most appropriate block so that the process of adsorption/desorption could happen.
2. In the case of using ASPEN adsorption module, find a block able to condensate and evaporate the refrigerant fluid (water or ammonia), It's to say, a change of phase in the fluid.
3. Some kind of programation in valves in order to open and close when certain pressure is reached.

I would be really grateful if someone could give some advice in any of those problems or in some case a suggestion so as to find a way for simulating an adsorption chiller in this or anyother software.

[serra]

for any  "non standard" process (supposing that operation is not available ready to use, in your simulator) you may create a procedure in Matlab or Excel or similar tools,

for the properties and solving flash operations you may adopt software tools such as Refprop, Prode Properties etc. which links with Excel, Matlab, Mathcad...

In general I prefer to suggest this approach to students as it allows to understand basic principles and calculations while a simulator makes that more difficult.

[Zauberberg]

See if any of the attached articles helps.

 

Attached Files

•  Modeling Absorption Chillers in ASPEN.pdf   510.65KB   62 downloads
•  Modelling of lithium-bromide (LiBr) chillers.pdf   513.34KB   39 downloads
•  Simulation of Li-Br Absorption.pdf   731KB   39 downloads

[Art Montemayor]

Roberto:

 

Please tell us if you mean aDsorption or aBsorption.  As in Spanish, the English meaning makes a big difference since they are both very different Unit Operations in Chemical Engineering.

 

(I think you mean aBsorption; is that correct?)

[robertors]

Serra:

Thank you very much for your suggestions, in fact I already know REFPROP mainly for obtaining properties in single liquid substances, I will try it for mixtures solid-liquid as an adsorption process requires. I am not really sure how much it could be possible in REFPROP. The purpose of the simulation is obtain the capacity of refrigeration in the chiller varying quantities  in the adsorption process.

 

Zauberberg & Art Montemayor:

Thank you very much, I needed also simulation in an absorption chiller, fortunately I could make it successfully in ASPEN Plus. However in this case I have to make an adsorption chiller simulation, for this reason I am trying to understand the process and be able to simulate it or calculate enthalpies in each point of the process

[Art Montemayor]

Roberto:

Once again, please answer my basic question and  tell us if you mean aDsorption or aBsorption.

 

I need to know for the sake of our Search Engine.

[breizh]

https://perso.limsi....pons/pricyc.htm

 

Roberto ,

Is it what you describe above ?

Hope this helps.
Breizh

[serra]

I agree with Art about correct terms,

if you are not sure you may describe the process (not too difficult for a chiller) and the fluids,

 

"https://en.wikipedia...n_refrigerator"

 

anyway, for a evaporating cycle as that described, you need to model fugacities and enthalpies of mixture,

look for a thermo model which can accurately predict these values,

yes, you can solve the problem in Excel or Mathcad with a series of flash operations, 

I have used PRODE PROPERTIES to model absorption chillers (water-ammonia) with good results,

as alternative you may use a simulator, 

but take care to validate results (you may use for example tables or charts, there are many available for these cycles),

[robertors]

Art Montemayor :

Yes it is aDsortion what I mean, the process by which a fluid is fixed onto a solid. Thank you very much
breizh:

The information you have brought me has been very usefull, in fact I have been searchig equations that describe the process in order to get information about the cycle, such as COP; from fixed data, such as the source's high temperature  and desired cold temperature to reach.

I am trying to obtain data in a cycle working with water and silica-gel.

Serra:

Thank you Serra for your suggestions, could you tell me please,  which thermo model do you think could approximate accurately?. I have never worked with such process, above all because of chemical models that I do not know really. Thank you

[serra]

I assume you mean applications like these:

 

"http://www.ashrae.or...014feature.pdf"

 

"http://sites.brunel....plications.pdf"

depending from selected adsorbents you may decide to adopt empirical or analytical models (for solving mass & energy balance),
with Excel / Matlab or Mathcad it shouldn't be too difficult...

you can adopt a simulator (Aspen) or a process library (Prode) as well but for these specific applications you can possibly prefer empirical models....

[robertors]

Serra:

This is exactly the application that I want to simulate. Thank you! the infomation is so usefull. The main objective is obtaining COP for differents heat source and condensating temperatures. Which model would you think can be the most suitable for water - silica-gel reffrigeration process? I have a little idea to implement an empirical model
 

[Art Montemayor]

Roberto:

 

Attached is some literature regarding Adsorption Refrigeration from my files that may be of interest and use to you.  I have more information on the subject and can upload it if you or others are interested.

 

Just let me know.

 

 Adsorption Refrigeration - Sep 2011.pdf   2.57MB   43 downloads

 Adsorption Refrigeration Thesis -Rezk July 2012.pdf   10.4MB   34 downloads

 SilicaGel-Water Isotherms Investigation Mar 2001.pdf   422.91KB   26 downloads

 Waste Heat Adsorption Chillers2.docx   1.08MB   33 downloads