[BLDG-SIM] answer - refrigeration / PowerDOE

[Alec Stevens]

Here is the response, posted by request.

Thanks to Jeff Hirsch for the answer.

----- Original Message -----
From: Jeff Hirsch <Jeff.Hirsch at DOE2.com>
To: <astevens at dmiinc.com>
Sent: Friday, April 21, 2000 3:16 PM
Subject: Re: [BLDG-SIM] refrigeration / PowerDOE


> see below ...
>
> ---
> Jeff Hirsch
> James J. Hirsch & Associates
> Building Performance Analysis Software & Consulting
> 12185 Presilla Road
> Camarillo, CA 93012-9243 USA
> phone: (805) 553-9000
> fax: (805) 532-2401
> email: Jeff.Hirsch at DOE2.com
> web: http://DOE2.com
>
>
> ----- Original Message -----
> From: "Alec Stevens" <astevens at dmiinc.com>
> To: <BLDG-SIM at gard.com>
> Sent: Friday, April 21, 2000 11:26 AM
> Subject: [BLDG-SIM] refrigeration / PowerDOE
>
>
> > Hello,
> > I have a specific question regarding the Compressor kW= f(condensing
temp)
> > curve fit for modeling refrigeration in PowerDOE.  This curve fit
returns a
> > factor from about .5 to 1.25 in the provided default curve
> > "Refg-kW-fECT-T1."
> >
> > I am making my own curve based on published data for the compressors
that
> > are in place at the store I am modeling.
> >
> > 1) Does the factor returned by this curve fit only apply to compressor
input
> > kW?  If so, how is the effect of compressor capacity as a function of
> > condensing temperature taken into account?   I think that it would make
more
> > sense if this factor was applied to EER.  Is that the case?
>
> The hourly compressor input power is calculated using
>  design capacity * design btu/wat * f(Tcond) * f(PLR)
> so the effect of part load and condensing temp is explicity
> taken into account through the two CURVE-FIT commands.
> The EER is modified but throught these two "normalized"
> curve-fit commands to make the formulation more general
> and flexible.
>
> > 2) In the default curve, the factor is 1.00 at about 100 F condensing
> > temperature.  Should you always normalize your curve to 100 F, or should
you
> > set it equal to 1.00 at some other temperature based on the store
> > conditions, or at the same temperature that you calculated your EER?
>
> You can normalize the cures to anything, but all must be normalized to the
> same values and those are the values for which the design capacity and
> BTU/watt values are also specified.  This is just like the HVAC input
> values in DOE-2/PowerDOE/eQUEST.
>
> > Thanks for your help.
> >
> > Sincerely,
> >
> > Alec Stevens
> > DMI
> > 617-527-1525x105
> >
> >
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> >
>


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