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Re: [EnergyPlus_Support] Re: GSHP Parameter coefficient generator
First, in the 'rated' values of the CoeffCalculator the manual says to
uses based on max Q. Is this Qmax that the heat pump could produce? or
the Qmax of the design case condition I am modeling?
I haven't used the CoeffCalculator or read the manual, but I have
created many empirical models before. I would say Qmax is a reference
point for the equipment not the absolute maximum output of the
equipment. So with that in mind......
If you look in my spreadsheet you will see where there is a gray bar
across the data set. This is the ARI rating point (80F DB / 67 F WB / 85
F inlet water temp) for WSHP's and is what I am using (or choosing) for
the design capacity. This "design" capacity is what I will use to
normalize the data and also use as the design capacity in the E+ coil
object as shown below with 7702.901 as the design total capacity and
5994.726 as the design sensible capacity.. It really doesn't matter
which capacity you pick as the design as long as the capacity used to
create the coefficients "has the same operating conditions" as the
capacity entered as the design in the E+ coil object. The reason is -
when you multiply the coefficients and the input data (operating DB / WB
/ inlet water temp) and then multiply this value by the "design"
capacity, you should get what the manufacturer says the capacity is at
those conditions. If this is confusting, all I am saying is if you
multiply out this equation, you should get the capacity at those
specific conditions. I'll give you an example using my spreadsheet and
70 F / 61 F / 70 F as the operating conditions where the total capacity
of this HP is 6955.757 W (see spreadsheet).
QLoadTotal = TotalCapRated * (TotalCapCoeff1 + (ratioTWB *
TotalCapCoeff2) + (ratioTS * TotalCapCoeff3) + (ratioVL *
TotalCapCoeff4) + (ratioVS * TotalCapCoeff5))
QLoadTotal = 7702.901 * (-9.77431084562635 + [1.058983 *
12.0680417507462 ] + [1.077288 * -1.94392063450029] + [1.0 * 0] + [1.0 *
0] )
QLoadTotal = 7702.901 * 0.91137784
QLoadTotal = 7020.253 W
The error is 7020.253 - 6955.757 / 6955.757 = 0.927 % which is very
reasonable.
Coil:Cooling:WaterToAirHeatPump:EquationFit,
Sys 1 Heat Pump Cooling Mode, !- Name
Sys 1 Water to Air Heat Pump Source Side1 Inlet Node, !- Water
Inlet Node Name
Sys 1 Water to Air Heat Pump Source Side1 Outlet Node, !- Water
Outlet Node Name
Sys 1 Cooling Coil Air Inlet Node, !- Air Inlet Node Name
Sys 1 Heating Coil Air Inlet Node, !- Air Outlet Node Name
0.73895, !- Rated Air Flow Rate {m3/s}
0.000165, !- Rated Water Flow Rate {m3/s}
7702.901, !- Rated Total Cooling Capacity {W}
5994.726, !- Rated Sensible Cooling Capacity {W}
1650.00, !- Rated Cooling Power Consumption {W}
-9.774310846, !- Total Cooling Capacity Coefficient 1
12.06804175, !- Total Cooling Capacity Coefficient 2
-1.943920635, !- Total Cooling Capacity Coefficient 3
0.0, !- Total Cooling Capacity Coefficient 4
0.0, !- Total Cooling Capacity Coefficient 5
-5.646916353, !- Sensible Cooling Capacity Coefficient 1
20.33485601, !- Sensible Cooling Capacity Coefficient 2
-13.48127419, !- Sensible Cooling Capacity Coefficient 3
-1.108040037, !- Sensible Cooling Capacity Coefficient 4
0.0, !- Sensible Cooling Capacity Coefficient 5
0.0, !- Sensible Cooling Capacity Coefficient 6
-5.023053229, !- Cooling Power Consumption Coefficient 1
0.984855162, !- Cooling Power Consumption Coefficient 2
4.482457509, !- Cooling Power Consumption Coefficient 3
0.0, !- Cooling Power Consumption Coefficient 4
0.0, !- Cooling Power Consumption Coefficient 5
0, !- Nominal Time for Condensate Removal to
Begin
Now lets say I want to use a larger HP after I have taken the time to
curve fit a smaller model, that's OK if the performance of the 2 HP's
are similar AND I use the capacity of the larger unit at the "same
operating conditions" chosen at the design point which were used to
create the original coefficients.
Secondly, where does the part load ratio relate to all this? I do not
see it as a variable in the IDF file? so therefor I am unclear how to
make use of the spreadsheet you uploaded and the purpose of it.
The simulation calculates a load for the WSHP. Lets say the total
sensible load required is 1000 W, and the HP has an operating sensible
capacity of 7500 W at the current air inlet conditions and entering
water temperature (determined by the simulation), the model will use a
PartLoadRatio = 1000/7500 = 0.133. So if you plug 0.1333 into the
equation below, you get 0.1333 * 7500 W = 1000 W. Do not get confused
here, 7500 W is QSensible in the equations below, not SensCapRated.
SensCapRated would be what you entered into the coil object above, or
7702.901 W.
Alan Jackson wrote:
>
>
> Richard
>
> I greatly appreciate the information that you provided. But in all
> honesty you have completely lost me.
>
> First, in the 'rated' values of the CoeffCalculator the manual says to
> uses based on max Q. Is this Qmax that the heat pump could produce? or
> the Qmax of the design case condition I am modeling?
>
> Secondly, where does the part load ratio relate to all this? I do not
> see it as a variable in the IDF file? so therefor I am unclear how to
> make use of the spreadsheet you uploaded and the purpose of it.
>
> Please forgive my ignorance
>
> -
> aj
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> <RRaustad@...> wrote:
> >
> > I should have included the "ratio" variables. You need to know this
> when
> > creating the coefficients. I was actually just doing this today for a
> > simulation. I'll upload the spreadsheet so you can have a look.
> >
> > I am not including the air and water flow rate variations since I will
> > be operating the HP at the design flow rates. And I have only done
> > cooling so far (too many other things to do today).
> >
> >
> http://tech.groups.yahoo.com/group/EnergyPlus_Support/files/Examples/SimpleModel_Coefficients.xls
> <http://tech.groups.yahoo.com/group/EnergyPlus_Support/files/Examples/SimpleModel_Coefficients.xls>
> >
> > Tref = 273.15
> > ratioTDB = ((LoadSideInletDBTemp+Tref)/Tref)
> > ratioTWB = ((LoadSideInletWBTemp+Tref)/Tref)
> > ratioTS = ((SourceSideInletTemp+Tref)/Tref)
> > ratioVL =
> >
> (LoadSideMassFlowRate/(AirVolFlowRateRated*PsyRhoAirFnPbTdbW(StdBaroPress,LoadSideInletDBTemp,LoadSideInletHumRat)))
> > ratioVS =
> >
> (SourceSideMassFlowRate/(WaterVolFlowRateRated*RhoH2O(SourceSideInletTemp)))
> >
> > Richard Raustad wrote:
> > >
> > >
> > > Use only the full load data set, the part-load performance is
> calculated
> > > inside the model based on the part-load ratio (PLR) required to
> meet the
> > > load
> > >
> > > QLoadTotal = TotalCapRated*(TotalCapCoeff1 + (ratioTWB *
> TotalCapCoeff2)
> > > + (ratioTS * TotalCapCoeff3) + &
> > > (ratioVL * TotalCapCoeff4) + (ratioVS * TotalCapCoeff5))
> > >
> > > QSensible = SensCapRated*(SensCapCoeff1 + (ratioTDB * SensCapCoeff2) +
> > > (ratioTWB * SensCapCoeff3) + &
> > > (ratioTS * SensCapCoeff4) + (ratioVL * SensCapCoeff5) +
> > > (ratioVS * SensCapCoeff6))
> > >
> > > !scale heat transfer rates
> > > QLoadTotal = QLoadTotal*PartLoadRatio
> > > QSensible = QSensible*PartLoadRatio
> > >
> > > Alan Jackson wrote:
> > > >
> > > >
> > > > 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
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, 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
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > >
> > >
> <mailto:EnergyPlus_Support%40yahoogroups.com><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
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> > > --
> > > Richard A. Raustad
> > > Senior Research Engineer
> > > Florida Solar Energy Center
> > > University of Central Florida
> > > 1679 Clearlake Road
> > > Cocoa, FL 32922-5703
> > > Phone: (321) 638-1454
> > > Fax: (321) 638-1439 or 1010
> > > Visit our web site at: http://www.fsec.ucf.edu
> <http://www.fsec.ucf.edu> <http://www.fsec.ucf.edu
> <http://www.fsec.ucf.edu>>
> > >
> > > UCF - From Promise to Prominence: Celebrating 40 Years
> > >
> > >
> >
> > --
> > Richard A. Raustad
> > Senior Research Engineer
> > Florida Solar Energy Center
> > University of Central Florida
> > 1679 Clearlake Road
> > Cocoa, FL 32922-5703
> > Phone: (321) 638-1454
> > Fax: (321) 638-1439 or 1010
> > Visit our web site at: http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
>
>
--
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL 32922-5703
Phone: (321) 638-1454
Fax: (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu
UCF - From Promise to Prominence: Celebrating 40 Years
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