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Re: [TRNSYS-users] Cooling demand in TRNSYS

José Javier,

  Sorry for the delay in getting back to you. Is the problem specific to one particular fourth air node? In other words, does it all work so long as you have three zones (no matter which three zones they are) and everything turns to zero when you add the fourth zone? Or is there something strange about one particular zone (which happens to be the fourth one that you are adding)?

  In a way, two concepts are getting mixed up here. Your building is operating in "energy rate control" in which it is calculating a load, an energy removal rate that must be provided by the cooling coil. The cooling coil's energy removal rate should not be passed back to the building though because if it is then the load changes. The cooling coil is intended to operate in "temperature level control" in which you turn off the load calculation in the building and allow its temperature to float. You then define a thermostat and some combination of coils, plenums, pumps, and fans, which act together to maintain the building's temperature as close to the setpoint as possible.

  I would recommend that you switch off the idealized COOLING (and HEATING) types in TRNBuild and instead define a VENTILATION for each of your zones. Then, instead of passing the air side heat transfer from the cooling coil to the building, you'll pass the outlet air conditions from the coil to those VENTILATIONs. A thermostat model will be needed in order to command the fan and pump that move air and liquid across the cooling coil.

kind regards,

 David


On 05/12/2021 02:52, RUBIO RUBIO, JOSÉ JAVIER wrote:

David,

 

Thank you for your answer. I see your point but what doesn’t make sense to me is the fact that I have four airnodes with different cooling setpoints. When I use the Air Side Heat Transfer output from the cooling coils (Type508) as an input for the cooling power available in three of the airnodes, it works and Qcool is not zero in any of them but it becomes zero (all of them) when I include the fourth airnode.

 

I have used a plot to compare the Qcool from Type56 and the Air Side Heat Transfer output from the cooling coils and the difference among the airnodes is that in the three which work, as I mentioned in the previous paragraph, the output from the cooling coil is bigger than Qcool from Type56. However, in the fourth airnode is just the opposite.

 

I hope I have explained myself clearly and you can help me to figure it out.

 

Thanks again in advance and sorry for the inconvenience,

 

Best regards,

 

José Javier.

De: David BRADLEY <d.bradley@tess-inc.com>
Enviado el: lunes, 10 de mayo de 2021 19:50
Para: TRNSYS users mailing list at OneBuilding.org <trnsys-users@lists.onebuilding.org>
CC: RUBIO RUBIO, JOSÉ JAVIER <josejavier.rubio@edu.upct.es>
Asunto: Re: [TRNSYS-users] Cooling demand in TRNSYS

 

José Javier,

  What Type56 is reporting in those outputs is the amount of additional energy that must be removed from a zone in order to maintain the setpoint that you have provided. If you give the zone exactly the amount of cooling energy that it needs then the demand for additional cooling energy is zero.

  kind regards,

 David

 

On 05/07/2021 07:52, RUBIO RUBIO, JOSÉ JAVIER via TRNSYS-users wrote:

To whom it may concern,

 

I am developing a cooling system with TRNSYS18 and I have several problems when I try to connect as an input the heat transfer of the coils in the chambers by using the Cooling Type Manager. You have an example below:

 

 

Where Q_evap4C, Q_evap8C, Q_carga4C and Q_descarga4C are the “Air Side Heat Transfer” output of the cooling coils.

 

 

When I use it as an input for the power available in each cooling zone, the cooling demand of the zone is zero which is non-sense. Any way to figure it out?

 

Thanks in advance and sorry for the inconvenience,

 

Best regards.

 

Jose Javier.



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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA
 
P:+1.608.274.2577
d.bradley@tess-inc.com
 
http://www.tess-inc.com
http://www.trnsys.com
-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

P:+1.608.274.2577
d.bradley@tess-inc.com

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