[TRNSYS-users] external temperature control for type 107 to type 56

[David BRADLEY]

Gary,
   There is a bit of room for interpretation in your question; I'm not 
sure whether the setpoint to which you refer is the temperature of the 
chilled water that the absorption chiller is providing or whether it is 
the room temperature that you want to maintain. I am guessing that you 
want to change the room temperature setpoint and that you have defined 
your zone temperature using the HEAT and COOL types inside TRNBuild. If 
that is the case, then here are the steps you need to take:

1. turn OFF the automatic HEAT and COOL types in TRNBuild so that the 
zone temperature floats.
2. in the Simulation Studio, define a thermostat (Type108 would be a 
good choice) that watches the zone temperature and has the same set 
point schedule that you previously defined in TRNBuild. The output of 
this thermostat model is going to be the control signal input to your 
cooling equipment.
3. decide how you want to remove energy from the sapce (fan coil, 
radiant cooled slabs, etc.) and choose an appropriate model.
4. define a water loop that includes a pump, the delivery device, a 
thermal storage tank (Type534 would be a good choice), and the 
absorption chiller.
5. connect the cooling signal output of the thermostat model to both the 
pump and the chiller control signal.

One work of caution: in most circumstances, the absorption chiller is 
not directly connected to the delivery device. There are usually two 
loops. If there are multiple energy delivery devices then they are 
usually on a secondary loop while the absorption chiller is on a primary 
loop

(http://www.nanomagnetics.org/chilledwatertips/constant_volumen_constant_speed.php)

Alternatively, you can have a situation where there is a chilled water 
distribution loop with a pump that draws chilled water from a tank, 
passes it to the load, and returns warmer water to the tank. The pump 
runs based on a thermostat that watches the zone temperature. The 
chiller is on a separate loop that pumps water from the tank, cools it 
down with the chiller and returns it to the tank. A thermostat that 
watches the tank temperature and turns on the chiller and a pump when 
needed.

   There is a tutorial online that would be well worth reading; I think 
it will fill in some of the gaps in what I have explained above.

http://sel.me.wisc.edu/trnsys/downloads/tutorials_and_examples/tlc_tutorial.pdf

Best,
  David


On 9/30/2012 04:53, KUM GARY wrote:
> Hi all,
>
> I would like to know how should i model type 107 chiller to respond to 
> the different temperature setpoint of the day needed for my building 
> in TRNbuild?
>
> Thanks
> Gary
>
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at cae.wisc.edu
> https://mailman.cae.wisc.edu/listinfo/trnsys-users

-- 
***************************
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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