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Re: [TRNSYS-users] Simulation of a cooling tower using type 510 and link a cooling load to it

Hello to all,

David, thank you very much for this detailed response. As I don't have
any zone loads from another software, I'd prefer to solve it with the
type 56. And I have already simulated some single rooms of the building
with the type 56 with the ceiling panels modelled in the TRNBuild
environment as an active surface (chilled ceiling) with a fixed supply
temperature. The supply of the cooled water for the panels via the
cooling tower was later added to the building.

The following question remains for me: I suppose that the way with
modelling the ceiling panels in the TRNBuild environment is not the
correct way? So I probably need a separate type in the simulation
studio? The panels are heating and cooling panels (but I'm especially
interested in the cooling case) which are hanging about 10 cms off from
the ceiling and are not covering the whole ceiling. Which type might be
the best to represent this construction? I looked into the category of
chillers and chilled beams, but couldn't find something that fits this
construction...maybe I dont see the obvious, so I would be grateful for
a suggestion.

And another question: is it possible to use the already simulated rooms
to conclude to the cooling load of the whole building? The four rooms
are example rooms and not adjacent to each other. In a first run, I set
the inner walls as adiabatic then. Or do I have to build exactly the
whole building in the type 56?

Thanks again for your help and advice.

Best regards,

Susanne


Am 31.05.2022 um 16:23 schrieb David BRADLEY:


Susanne,

 You're correct that you'll need some model of a delivery device
between the cooling loads and the cooling tower. The most rigorous way
to model the system would be to get away from loads entirely, make a
Type56 model of the building in temperature level control and
explicitly model the ceiling panels with their controls on inlet water
temperature and the model of the cooling tower all in one project.

 If implementing the building model in Type56 is not feasible because
you already have zone loads from some other software tool then you can
use Type682 in the TESS Libraries (or an equation) to impose those
loads onto the water flow that comes from the cooling tower. What 683
does is to take the load and the inlet temperature from the cooling
tower and return the outlet temperature that goes back to the cooling
tower.

 With this second method, however, you'll need some way of estimating
the effectiveness of the ceiling panels so that you can convert the
zone loads to the loads that will be seen by the tower. One method
would be to find a ceiling panel model and give it the entering water
temperature and flow rate as well as the air setpoint temperature. The
model will hopefully be able to then give you a panel efficiency that
you can feed to an equation that modifies your zone loads before
passing them to Type682. If you don't have a ceiling panel model then
you could assume a constant effectiveness for the panels and modify
your loads accordingly.

kind regards,

 David


On 05/31/2022 07:42, Susanne Urlaub via TRNSYS-users wrote:

Hi everyone,

I have a question about the simulation of a cooling tower in TRNSYS. My
focus question is what fluid outlet temperature the cooling tower is
able to deliver in combination with a certain cooling load of a whole
building. The building is equipped with ceiling panels for which the
fluid outlet temperature of the cooling tower is the input as supply
temperature of the ceiling panels corrected for dew point control. I
tested out the Type 510 from the TESS Libraries. How is it then possible
to link the cooling load from the building with the cooling tower?
Probably I have to build the ceiling panels with another type? Or is it
possible to read in a external load file?

Any help, suggestions or advices are highly welcome!

Many, many thanks in advance.

Susanne


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David BRADLEY
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Thermal Energy System Specialists, LLC
3 North Pinckney Street - suite 202
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