[TRNSYS-users] R: Air-air heat pump: performance data files

[Jacopo Valente]

Hi David,
in my heating performance data, the normalized capacity and power values depend on outdoor temperature until -19 °C. My minimum ambient temperature is aroud -5 °C.
During the simulation I have the following warning, repeated for several hours:
“the referenced unit has called the psychrometrics routine with humidity ratio above the saturation humidity ratio for the given dry bulb temperature. The air was assumed saturated at the given dry bulb temperature and the humidity ratio set for this condition.”
This error is referred to the type 960.
Could be this the problem of a constant COP during the heating simulation?
Really thank you.

Best regards,

Jacopo

Da: David BRADLEY<mailto:d.bradley at tess-inc.com>
Inviato: lunedì 6 febbraio 2023 16:10
A: TRNSYS users mailing list at OneBuilding.org<mailto:trnsys-users at lists.onebuilding.org>
Cc: Jacopo Valente<mailto:jacopovalente at LIVE.IT>
Oggetto: Re: [TRNSYS-users] Air-air heat pump: performance data files


Jacopo,

 It may be that the evaporator temperatures in the default heating performance file do not correspond with the range of evaporator temperatures that are occurring during your simulation. Type954 is able to interpolate within the range of temperatures (and flow rates, etc.) that is given in the file. However, it cannot extrapolate beyond the range of numbers given. If you have COP values for ambient temperatures from 5C to 20C in the data file but the ambient temperature in your weather data is consistently below 5C then the COP corresponding to 5C would always be returned. Have a look in your *.log file; if the data file is often being accessed with temperatures above or below the range there will be a warning written there.

kind regards,

 David


On 2/4/2023 11:54 AM, Jacopo Valente via TRNSYS-users wrote:
Dear all,

i’m using the type 954 to model an air-to-air heat pump. Analyzing the results of my simulation, the COP is almost constant during the heating working. I’m using the default performance data file. The problem is only for the heating working, while the COP varies for the cooling working.
I can suppose there is some problem with the default heating performance data.
Can u help me please?

I try to attach an image of COP curve:
[cid:image002.png at 01D93F39.FF4C5A60]

Thanks.

Best regards,

Jacopo Valente



_______________________________________________

TRNSYS-users mailing list

TRNSYS-users at lists.onebuilding.org<mailto:TRNSYS-users at lists.onebuilding.org>

http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org

--

***************************

David BRADLEY

Principal

Thermal Energy System Specialists, LLC

3 North Pinckney Street - suite 202

Madison, WI  53703 USA



P:+1.608.274.2577

d.bradley at tess-inc.com<mailto:d.bradley at tess-inc.com>



http://www.tess-inc.com

http://www.trnsys.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/attachments/20230212/b53832f3/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 90A1F24CB3B34915A6723E565BDD9A5D.png
Type: image/png
Size: 44009 bytes
Desc: 90A1F24CB3B34915A6723E565BDD9A5D.png
URL: <http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/attachments/20230212/b53832f3/attachment-0001.png>