[TRNSYS-users] Absorption chiller

[David BRADLEY]

Hsein,
   We faced a similar situation in a project a few years ago. We 
investigated a number of possible solutions because what TRNSYS is 
showing you is a real world potential problem in systems such as yours. 
One thing we looked at was to put a buffer tank onto the source loop. 
When the electrical load exceeded the immediate cooling demand we were 
able to allow the buffer tank temperature to rise a little bit. When the 
electrical load dropped off then we were able to use some of the energy 
in the buffer to continue running the absorption chillers. If the tank 
temperature dropped off too much for the absorption chillers to operate 
then we investigated reliance on traditional electric chillers. We also 
investigated the option of running the generators so that if the 
electrical load dropped low enough that the absorption chiller could not 
run then we would overproduce electricity and send it back into the 
utility's electric grid.
kind regards,
  David


On 02/10/2016 16:49, Hsein Moussawi wrote:
>
> Hi there,
>
> Sorry for the mistake I mentioned in the previous email.
>
> In fact, I can control the flow rate to the evaporator by installing a 
> storage (buffer) tank and this is what I already did.
>
> The real problem behind the negative values is the low flow rate to 
> the generator and not the evaporator. That's what I can't control 
> since the generator is driven by exhaust gases from certain prime 
> mover which in turn depends on the electrical load of the building 
> (that I can't change).
>
> Sorry and Thanks...again!
>
>
>
>
> ------------------------------------------------------------------------
> *From:* David BRADLEY <d.bradley at tess-inc.com>
> *Sent:* Thursday, February 11, 2016 12:07 AM
> *To:* TRNSYS users mailing list at OneBuilding.org; 
> hsein_moussawi at hotmail.com
> *Subject:* Re: [TRNSYS-users] Absorption chiller
> Hsein,
>   This would be a problem in a real system as well, not just in 
> simulation. You need to isolate the load flow from the source flow by 
> using either a primary/secondary pumping scheme or by putting a buffer 
> tank between the load loop and the source loop.
> kind regards,
>  David
>
>
> On 02/10/2016 15:38, Hsein Moussawi wrote:
>>
>> Hi angel,
>>
>> Yes I know how it works and the negative values mainly appear 
>> when the flow rate to the evaporator is low. However in the system I 
>> am simulating, I can't control this flow rate, it is imposed by other 
>> components (cooling load from building). So do you have other 
>> suggestions?
>>
>> Thanks for the fast reply.
>>
>> Regards.
>>
>>
>>
>> ------------------------------------------------------------------------
>> *From:* Angel Carrera <angel.carrera at aiguasol.coop>
>> *Sent:* Wednesday, February 10, 2016 9:28 PM
>> *To:* TRNSYS users mailing list at OneBuilding. org
>> *Subject:* Re: [TRNSYS-users] Absorption chiller
>>
>>
>> Hi,
>>
>> I giess that the flowrate you are giving as an input is too low 
>> related to the power requirement at the evaporator.
>> I suggest you to read the descripción of the type to understand how 
>> it is working, regards
>>
>> Angel
>>
>> El 10/2/2016 20:14, "Hsein Moussawi" <hsein_moussawi at hotmail.com 
>> <mailto:hsein_moussawi at hotmail.com>> escribió:
>>
>>     Hello there,
>>
>>     I am using an exhaust fired absorption chiller in a certain
>>     system. After simulation the temperature of the hot fluid exiting
>>     the chiller is observed to be negative in many instances. This is
>>     impossible in reality. I am wondering if anyone faced a similar
>>     problem!?
>>
>>     My question is:
>>
>>     Is there a way by which I can limit the output of a component to
>>     a certain point?? (e.g. outlet temperature of chiller to ambient
>>     temperature)
>>
>>     Thanks in advance TRNSYS community,
>>
>>     Best regards.
>>
>>
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>>
>>
>>
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>
> -- 
> ***************************
> David BRADLEY
> Principal
> Thermal Energy Systems Specialists, LLC
> 22 North Carroll Street - suite 370
> Madison, WI  53703 USA
>
> P:+1.608.274.2577
> F:+1.608.278.1475
> d.bradley at tess-inc.com
>
> http://www.tess-inc.com
> http://www.trnsys.com
>
>
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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