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[EnergyPlus_Support] Re: GSHP Parameter coefficient generator
I am glad you mentioned the curve fit model because this is really the origin of my original question. The problem I have is that if I input a series of full load condition into the spreadsheet i can get error % less than 5 in both heating and cooling, but as soon as I include the part load values the error % ends up between 30-40%.
-
aj
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Edwin Lee <leeed2001@...> wrote:
>
> Alan,
>
> It looks like R410 is not available in the spreadsheets, if you enter R410a,
> the code should issue a warning such as "Refrigerant not in list". You may
> want to try using the simpler curve fit routine before going to the
> parameter estimation to see how well the curve fit works. In heating mode,
> with a large data set (~1000 points), I have curve fits that match to within
> 3-4% of the manufacturer's data points. In cooling mode, the sensible
> capacity does not typically match as well, but it may be within 10%. Using
> the curve fit would alleviate the problem with the refrigerant being
> unavailable, and there are also known issues with the parameter estimation
> model. (For instance, if you attempt to autosize the capacity in E+ after
> you generate the parameters, the parameters and new capacity may be in
> conflict, and could cause errors. Whereas the curve fit model scales nicely
> with capacity, and has not shown any problems.)
> Just my thoughts,
> Edwin
>
> On Thu, Jun 4, 2009 at 8:46 AM, Alan Jackson <alanjackson7@...> wrote:
>
> >
> >
> > Edwin
> >
> > Thank you for your response. I have expanded my dataset and I believe I
> > have enough information for a good curve fit. I am looking a the
> > ParamEstimator Tab and do not see R410a listed as a refrigerant.
> >
> > Is this an acceptable refrigerant for these calculations?
> >
> > -
> > aj
> >
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx<EnergyPlus_Support%40yahoogroups.com>,
> > Edwin Lee <leeed2001@> wrote:
> > >
> > > I think the basic answer is that you want the data to cover the spectrum
> > of
> > > operation for that component during the simulation. The curve fit will
> > fit
> > > best within the data provided. Extrapolation from that data may result in
> > > inaccuracies.
> > > The input to the utility requires that each input must vary. If a
> > constant
> > > is given for entering air temperature throughout your data points,
> > without
> > > any variation, a curve fit won't really make sense, and the spreadsheet
> > tool
> > > may give non-sensible answers.
> > > A more advanced tool is currently under development which will allow the
> > > user to easily enter the tabulated data as found in a heat pump data
> > sheet
> > > along with the correction factors which are also found. This is used to
> > > develop a large dataset which will then result in a good quality curve
> > fit.
> > > For the spreadsheet the user must apply these manually.
> > >
> > > Edwin
> > >
> > > On Wed, Jun 3, 2009 at 4:57 PM, Alan Jackson <alanjackson7@> wrote:
> > >
> > > >
> > > >
> > > > This is my first go around at modeling a GSHP in Energyplus and I am
> > going
> > > > through the documentation for the parameter-coefficient generator
> > > > spreadsheet and needed some feedback. I have all the manufacturer
> > > > information as far as performance values. My question relates to the
> > amount
> > > > of data required.
> > > >
> > > > The user manual states "The data points must have varying inlet
> > conditions
> > > > (e.g. water flow rates, inlet water temperatures, etc.) that covers the
> > > > entire range of the heat pump operating conditions."
> > > >
> > > > When they say "covers the entire range" doe s this mean we would need
> > to
> > > > enter both part load and full load conditions? or is it possible to get
> > > > useful outputs with varying temperatures at full load ratings?
> > > >
> > > > I think I already know the answer to this but looking for some
> > > > confirmation.
> > > >
> > > > Thanks
> > > >
> > > > -
> > > > aj
> > > >
> > > >
> > > >
> > >
> >
> >
> >
>
------------------------------------
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