[TRNSYS-users] Problems connecting Type 1231 with type 56

[David BRADLEY]

Jorge,

  It sounds like there might be two issues going on here. One is the 
connection between the radiator and the building and the other is the 
connection between the radiator and the heat pump. I would suggest 
trying to separate the two problems. First, run your building with its 
radiator. From what you describe, it sounds as though your connections 
are correct. Put an ideal temperature and flow rate of water into the 
radiator and make sure that the water coming out of the radiator and the 
building both react as expected. Next, put a forcing function onto the 
flow rate going into the radiator and make sure that it still makes sense.

  Once you are sure that the radiator is getting heat into the building 
and that the water comes out of the radiator at a reasonable temperature 
then add a pump, piping, and the heat pump back in. The pump is there to 
control the flow obviously. The pipes are there to make sure that you 
have thermal capacitance in your liquid loop. Make sure that the volume 
of liquid moved by the pump in one time step is less than the volume of 
the piping. If it isn't, you can get convergence problems.

  The COP at which the heat pump operates is a function not only of the 
air temperature on its source side but also of the returning water 
temperature on its load side. If the COP increases when the ambient 
temperature decreases while the entering water temperature stays the 
same then you'll need to look at the performance data file that you're 
using as it may have a problem.

kind regards,

  David


On 03/24/2021 09:50, Jorge Ignacio Ortega Arriagada via TRNSYS-users wrote:
> Hello,
>
> I have a question about Type 1231, how does it connect to type 56? The 
> radiator model is connected to a heat pump.
>
> I have connected the radiator heat as a gain (through gain type 
> manager) that brings radiation and convection to the house, however, I 
> have noticed that the SCOP of the heat pump increases as the ambient 
> temperature decreases, which is not possible (I have tested for 
> different climatic conditions in Chile).  In my model, I found the 
> problem in Type 1231, which causes this anomaly. As radiator inputs 
> connect the water flow and water temperature from the heat pump (type 
> 941). From type 56 connect the indoor temperature of the house to the 
> radiator model.
>
> I would like some help on this, please.
>
-- 
***************************
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 at tess-inc.com

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

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