[TRNSYS-users] unmet cooling load with Type 665.

[Jeff Thornton]

<You can run the file and see that, during the summer, the temperature of
the inhabited space (SPACE1) exceeds the cooling setpoint temperature
while cooling rate stays almost constant.This made me think that there
might be a cooling coil capacity limit somewhere, which I could not figure
how to modify/change. >

The heat pump model that you are using (665) has the capacity built into
the external data files that accompany this model.  To increase the
capacity you'll have to go in and edit these data files.  However, the
heat pump model you are using is an older model and has been replaced in
the new version of the TESS Libraries with one that allows you to set the
capacity as a parameter to the model and uses a normalized performance map
in the external data files.  I highly recommend that you upgrade to the
newest version of the Libraries.

<I suppose TRNSYS actually autosizes the cooling coil in Type 665. What
might be the parameter that is limiting this capacity? ...or is there some
other reason? >

No this is not the case - TRNSYS rarely (if ever) auto-sizes anything on
the HVAC side.  If your equipment is too small it will run 100% of the
time and your space will not meet the temperature setpoints - as happens
in real life...

Jeff


Jeff Thornton
President - TESS, LLC

22 North Carroll Street - Suite 370
Madison WI 53703 USA

Phone: 608-274-2577
Fax: 608-278-1475
E-mail: thornton at tess-inc.com
Web: www.tess-inc.com