[TRNSYS-users] Yazaki chiller unit model

[David BRADLEY]

Martin,
   I would recommend that you make a very simple project where the 
chiller is subject to a known constant load with known constant outdoor 
conditions. Hook up a Type65 online plotter to the chiller and take a 
look at its performance under these known conditions; once the model 
looks up the performance data in the data file, its computations are 
really quite simplistic. You can verify them by hand using the 
documentation in the 04-Mathematical Reference. This will give you some 
confidence in your model.

   One of the issues that often occurs in modeling absorption chillers 
is that if you compute a building load and pass it directly to the 
chiller then the chiller spends a lot of its time running at a very very 
low part load. In reality, a chiller can't operate much below 20% 
capacity so you have to make sure that this is reflected in the data 
file. The data file should have near zero capacity and near zero 
fraction of design energy input below about 20% PLR (part load ratio). 
At one time, I think there was an error in the Type107 example data file 
that showed too large a capacity at very low PLR. The more correct way 
to model the system would be to place the chiller on its own primary 
loop and to place the load on a secondary loop. The loops can be 
separated by a thermal storage tank whose volume is equal to the volume 
of the primary and secondary loops. The chiller operates to keep the 
primary loop cold and the secondary loop draws off only as much as it 
needs to meet the load.
Kind regards,
  David



On 12/19/2012 01:51, Martin Ssembatya wrote:
> Hello there,
> I have been modelling a solar ooling system that uses one of the 
> YAazaki chiller models. I used type 107 for the modelling of the 
> absorption chiller partly because i did not have satisfactory chiller 
> performance data from the manufacturer to model the chiller unit, but 
> alos because i did not have enough time and compiling language to 
> create my own model for this chiller. /But on using type 107 for this 
> purpose, i am not getting satifactory results from my simulation i.e. 
> the chilling energy is always too low compared to the rated capacity 
> of the chiller regardless of the season of the year, including summer 
> periods with high insolation values. Is there any one who could have 
> created a TRNSYS model for any Yazaki absorption chiller unit? If yes, 
> can you kindly help me with that model you created and to use it in my 
> simulation and see its effect on results. I will be very grateful. /
> //
> Best regards
> 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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