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Re: [EnergyPlus_Support] Re: validation of extensive coefficients use
These are all normalized. I am not aware of any EnergyPlus HVAC equipment
curves that are not normalized.
Mike
On 12 Oct 2005, at 1:42, deserteagle_zhou wrote:
> Thank you,Brent/(Fred), for your elaborated explaination. So can I
> assume that the "normalization" means a ratio of a real-condition
> parameter to a rated-point one? Then how about curves of Electric
> Chiller, WindAC,Direct-fired absorption Chiller? Are they called
> normalized curves?
>
> John
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Griffith, Brent"
> <brent_griffith@n...> wrote:
> >
> > John,
> >
> > Keep in mind that there are at least two possible "policies" for
> curve-fits. One option is to use curves that are normalized with
> respect to capacity (or efficiency) at a single operating point.
> The other is to use curves that directly fit the capacity/efficiency
> data without normalization. It is not unreasonable practice to use
> normalized curves for components that have a different nominal
> capacity or efficiency than the one used to produce the curves.
> Clearly it is better to use performance curves that apply to the
> unit being modeled, but this isn't always practical. On the other
> hand, direct performance curves (that aren't normalized) are
> basically limited to the original unit and cannot be used to model
> components with a different size or nominal performance.
> >
> > Developers have different opinions on which is the best way to
> go. The normalized-curve group want curves to be more general so
> that one can easily adjust equipment capacities when doing a
> simulation study. The direct-curve group are more leary of the
> pitfalls of abusing curves and want to force the user to use curves
> that match the component. I am not sure if it is true across the
> board, but curves tend to be of the normalized type in EnergyPlus.
> So it is not blatently wrong to reuse such curves for different
> capacities. However, do not assume that the example files that ship
> with EnergyPlus represent best modeling practice. It is better to
> think of them as test and demonstration files.
> >
> > Brent
> >
> > -----Original Message-----
> > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]On Behalf Of
> deserteagle_zhou
> > Sent: Tuesday, October 11, 2005 4:13 AM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > Subject: [EnergyPlus_Support] validation of extensive coefficients
> use
> >
> >
> >
> > Hi,there,
> >
> > Components, i.e., chiller, fan, etc, are defined according to a
> > performance curve-fit policy. Curves, however, often have
> something to
> > do with the real working conditions and an equipment capacity. I
> think
> > users are not supposed to use directly the same coefficients as
> before
> > after the equipment capacity has been changed. That means we 'd
> better
> > not use directly the curves and parameters in E+ example files
> directly
> > unless we cannot get the data from the equipment producer.
> > Is this understanding right or not?
> >
> > Another question is whether the object SINGLE DUCT:VAV REHEAT can
> deal
> > with heating condition alone in a zone without a company heating
> device
> > (such as a baseboard heater), especially in a cold area?
> >
> > Thank you.
> > John
> >
> >
> >
> >
> >
> >
> > The primary EnergyPlus web site is found at:
> > http://www.energyplus.gov
> >
> > The group web site is:
> > http://groups.yahoo.com/group/EnergyPlus_Support/
> >
> > Attachments are not allowed -- please post any files to the
> appropriate folder in the Files area of the Support Web Site.
> >
> > EnergyPlus Documentation is searchable. Open EPlusMainMenu.idf
> and press the "search" button.
> >
> >
> >
> >
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>
>
>
> The primary EnergyPlus web site is found at:
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>
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>
> Attachments are not allowed -- please post any files to the appropriate folder
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx
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