Re: [EnergyPlus_Support] Re: GSHP Parameter coefficient generator

[Edwin Lee <leeed2001@xxxxxxxxx>]

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@xxxxxxxxx> 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, 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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