[TRNSYS-users] Simulating the absorption chiller - hot water storage system

[David BRADLEY]

Martin,
   A couple of pointers come to mind (and these apply to systems in 
general, not just to this particular system).

1. There should also be a pump in the loop whose rated flow rate matches 
the hot water flow requirements of the absorption chiller. The pump 
should be controlled in the same manner as the chiller so that if there 
is no load on the chiller, both the chiller and the pump turn off.

2.  There should probably be an auxiliary heating device in the loop 
(Type6 perhaps) that raises the liquid temperature going to the chiller 
in case the water in the tank was not hot enough.

3. Most importantly, make sure that the tank is large enough to contain 
more than one timestep's worth of flow from the pump. For example, if 
your pump has a rated flow rate of 10000 kg/h and you are running with a 
5 minute timestep, your tank needs to be more than 833L. If you try and 
run with a 1-hour timestep, you will almost never get convergence 
because the tank volume turns over more than once in a timestep.
Best,
  David


On 10/29/2012 04:24, Martin Ssembatya wrote:
> Hello there,
>
> I am carrying out ma Msc. thesis project involving simulation of a 
> solar cooling system. The system contains an absorption chiller 
> connected to a hot thermal storage tank that receives hot water from 
> solar thermal collectors. I am finding a problem with making a closed 
> loop between the absorption chiller (modeled with type 107) and the 
> storage tank (modeled with type 4a). Every time i try to connect the 
> hot water absorption chiller outlet temperature as the inlet 
> temperature of the cold side of the tank, the system returns 
> unexpected errors (i.e lack of convergence). Am getting stuck on this. 
> Can some one please help me with some information how i can go about 
> this problem.
>
> Thanks in advance
>
> Martin
>
>
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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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