[Equest-users] eQuest heat pump performance curves

Wed Nov 18 13:40:32 PST 2015

Thanks Daniel. It seems you're right and maybe the curve is not intended to
be used outside the range you mentioned.

Thank you everybody for the quick responses.
El 18/11/2015 19:45, "Daniel Knapp" <danielk at arborus.ca> escribió:

> I’m not sure I understand why the 39+ capacity curve falls after after
> 54ºF, but I don’t think that the 39+ and 39- curves have been switched. The
> 39+ curve goes negative at about 11ºF so it won’t work as a replacement for
> the 39- curve. Also the 39- curve flattens out as it drops to -13ºF and
> then starts to rise again. I suspect the curves are intended to be used
> over an operating range of about -10ºF to 50ºF. Below -10ºF the heat pump
> chiller shuts off and goes to supplemental resistance heating. Above 54ºF
> the heat pump chiller is unlikely to have a call for heating? It does seem
> a bit strange.
>
> Cheers,
> Dan
>
> —
> Daniel Knapp, PhD, PPhys, LEED® AP O+M
> danielk at arborus.ca
>
> Arborus Consulting
> Energy Strategies for the Built Environment
> www.arborus.ca
> 76 Chamberlain Avenue
> Ottawa, ON, K1S 1V9
> Phone: (613) 234-7178 ext. 113
> Fax: (613) 234-0740
>
>
>
>
> > On Nov 18, 2015, at 11:49 AM, Fernando Varela <fvarela at ind.uned.es>
> wrote:
> >
> > 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.png>
> >
> > 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
> >
> >
> >
> > <image001.png>
> >
> >
> >
> >
> >
> > William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers &
> Architects LLP
> >
> > Senior Energy Engineer
> >
> > <image010.jpg>  <image011.jpg>
> >
> >
> >
> > 134 South Fitzhugh Street                 Rochester, NY 14608
> >
> > T: (585) 698-1956                        F: (585) 325-6005
> >
> > bbishop at pathfinder-ea.com             www.pathfinder-ea.com
> >
> > <image012.png>Carbon Fee and Dividend - simple, effective, and
> market-based.
> >
> >
> >
> >
> >
> > 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.
> >
> > <image013.jpg>
> >
> > 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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