[Equest-users] eQuest heat pump performance curves

[Fernando Varela]

Dear Bill and Jeff:

The problem arises when you plot for a fix hot water outlet (let's say
113ºF) the whole curve for exterior temperatures (from 9 to 59ºF), using
the expression of 39- curve for values till 39ºF and 39+ for the rest of
them.

It shows like this:

[image: Imágenes integradas 1]

Shouldn't  COP  increase with higher exterior temperatures for a fixed hot
water outlet temperature? It seems even to decay after 54ºF...

With capacity curves is the same, but in that case it makes more sense.

Thanks.


*Fernando Varela Díez*
Dpto. Ingeniería Energética - ETSI Industriales
Email: fvarela at ind.uned.es
Tlf: 91 398 6468

Universidad Nacional de Educación a Distancia (UNED)
C/ Juan del Rosal, 12. Despacho 2.20
Ciudad Universitaria, 28040, Madrid



2015-11-17 16:03 GMT+01:00 Bishop, Bill <bbishop at pathfinder-ea.com>:

> Fernando,
>
> The curves look okay to me. I plotted them out for a range of hot water
> temperatures from 90F to 130F.
>
> -        I plotted the “…39+” curve for the range of entering dry bulb
> from 40F to 60F.
>
> -        I plotted the ”…39-“ curve for the range of Edb from 20F to 38F.
>
> -        Both curves show decreasing capacity as the heat pump chiller
> makes hotter water, which makes sense.
>
> -        Both curves show decreasing capacity with lower outside air
> condenser temperatures, which makes sense.
>
> -        The “…39-“ curve shows rapidly decreasing capacity with
> decreasing condenser temperature below 39F, which makes sense since larger
> portions of the chiller heat pump heat is needed to defrost the condenser
> coils.
>
> -        I’m guessing that the curves are normalized to 110F HWT and 44F
> Edb.
>
> I can share an Excel file I used to generate the curves and chart if
> anybody wants it.
>
> ~Bill
>
>
>
>
>
>
>
> *William Bishop, PE, BEMP, BEAP, CEM, LEED AP **|** Pathfinder Engineers
> & Architects LLP*
>
> *Senior Energy Engineer*
>
>
>
>
>
> 134 South Fitzhugh Street                 Rochester, NY 14608
>
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>
> bbishop at pathfinder-ea.com <wbishop at pathfinder-ea.com>
> www.pathfinder-ea.com
>
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>
> *From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
> Behalf Of *Fernando Varela
> *Sent:* Tuesday, November 17, 2015 5:04 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] eQuest heat pump performance curves
>
>
>
> Dear users:
>
>
>
> I've noticed that eQuest heat pump performance curves:
>
>
>
> ChlrHPAirHeatCap-fHW&39+
>
> ChlrHPAirHeatCap-fHW&39-
>
>
>
> which refer, respectively, to the temperature capacity factor of the heat
> pump in normal and defrost mode, seem to be exchanged. This is,
> ChlrHPAirHeatCap-fHW&39+ curve seems to be the defrost mode curve, and
> ChlrHPAirHeatCap-fHW&39- the curve regarding to normal mode.
>
>
>
> I've plotted (with fixed condensing temperature) both capacities varying
> exterior temperature, and observing the results taking the curves in the
> opposite way as it shoud be (below 39ºF,ChlrHPAirHeatCap-fHW&39+, and
> ChlrHPAirHeatCap-fHW&39- above 39ºF ), the resulting HP capacity curve
> seems more like it should be.
>
>
>
> Am I doing something wrong?
>
>
>
> Thank you in advance.
>
> [image: Image removed by sender.]
>
> *Fernando Varela Díez*
> Dpto. Ingeniería Energética - ETSI Industriales
> Email: fvarela at ind.uned.es
> Tlf: 91 398 6468
>
> Universidad Nacional de Educación a Distancia (UNED)
> C/ Juan del Rosal, 12. Despacho 2.20
> Ciudad Universitaria, 28040, Madrid
>
>
>
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