[TRNSYS-users] total heating rate and total cooling rate in heat pump 954
David BRADLEY
d.bradley at tess-inc.com
Thu Nov 20 07:59:49 PST 2014
Enyuan,
The total cooling rate is the sensible and latent energy being
removed from the air stream by the active section of the heat pump. It
is computed as the mass flow rate of air multiplied by the difference
between the enthalpy of air leaving the heat pump and the enthalpy of
the mixed air (return + ambient) entering the evaporator. The heat pump
does not have any kind of economizer controls built into it. The amount
of outdoor air being mixed with return air is simply a function of how
you have set the outdoor air damper position input. It could be that
your heat pump is cooling because there is no ambient air being mixed in
and the heat pump is working only with return air. If your concern is
that the heat pump would not operate when the ambient temperature is so
low (because of freeze up in the condenser) then you have to be careful
of your external data file. Performance is interpolated within the range
of data given in the file but it is not extrapolated beyond the range.
If the heat pump asks for cooling (because of the way you have set the
cooling signal input and fan control signal) then the performance
(cooling capacity and COP) will be returned for the closest ambient
temperature found in the data file.
Regards,
David
On 11/19/2014 14:26, Enyuan Hu wrote:
> Dear all,
>
> When I'm using a type 954 air-to-air heat pump to condition a one zone
> building, I found that even during the winter (ambient temperature is
> below the cooling threshold), the 'total cooling rate' output from the
> heat pump is positive instead of being zero as expected. Can anyone
> help me explain why? Thanks!
>
> best regards,
> Enyuan Hu
>
>
> _______________________________________________
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> TRNSYS-users at lists.onebuilding.org
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--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA
P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com
http://www.tess-inc.com
http://www.trnsys.com
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