[TRNSYS-users] Absorption chiller

Thu Feb 11 10:07:06 PST 2016

Hi David,

Installing a Buffer tank on the source loop might be a good idea. I'm gonna try it. Also I thought about keeping the electrical generation at constant rates and delivering the excess to the grid, but I was first checking the performance of the system under electrical load following scenario. Perhaps an economic study would show  which option would be preferable.

Great thanks for the ideas and fast response.

Best regards.

Houssein

________________________________
From: David BRADLEY <d.bradley at tess-inc.com>
Sent: Thursday, February 11, 2016 6:00 PM
To: TRNSYS users mailing list at OneBuilding.org; hsein_moussawi at hotmail.com
Subject: Re: [TRNSYS-users] Absorption chiller

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><mailto: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<mailto: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><mailto: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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Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
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P:+1.608.274.2577
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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<mailto:d.bradley at tess-inc.com>

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