I found a problem with the spreadsheet and have uploaded a new version.
The problem, Tref = 283.15, not 273.15. Tref is used to normalize the
temperature data and using the incorrect value gave strange results. It
took me a while to figure out the cause of the problem.
Richard Raustad wrote:
> Alan, I finished the spreadsheet to calculate the coefficients for
> both cooling and heating for the simple WSHP model.
>
> I added the manufacturers data and many comments so you can follow
> what is required to develop these coefficients.
>
>
http://tech. groups.yahoo. com/group/ EnergyPlus_ Support/files/ Examples/ WSHPSimpleModel_ CoefficientDevel opment.xls >
>
> Richard Raustad wrote:
>>
>>
>>
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: WaterToAirHeatPu mp: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@ yahoogroups. com >> <mailto:EnergyPlus_ Support%40yahoog roups.com>
>> > <mailto:EnergyPlus_ Support%40yahoog roups.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>
>>
>> >
>> <
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 = ((LoadSideInletDBTe mp+Tref)/ Tref)
>> > > ratioTWB = ((LoadSideInletWBTe mp+Tref)/ Tref)
>> > > ratioTS = ((SourceSideInletTe mp+Tref)/ Tref)
>> > > ratioVL =
>> > >
>> >
>> (LoadSideMassFlowRa te/(AirVolFlowRa teRated*PsyRhoAi rFnPbTdbW( StdBaroPress, LoadSideInletDBT emp,LoadSideInle tHumRat)) )
>>
>> > > ratioVS =
>> > >
>> >
>> (SourceSideMassFlow Rate/(WaterVolFl owRateRated* RhoH2O(SourceSid eInletTemp) ))
>>
>> > >
>> > > 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*PartLoad Ratio
>> > > > QSensible = QSensible*PartLoadR atio
>> > > >
>> > > > 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@ yahoogroups. com >> <mailto:EnergyPlus_ Support%40yahoog roups.com>
>> > <mailto:EnergyPlus_ Support%40yahoog roups.com>
>> > > > <mailto:EnergyPlus_ Support%40yahoog roups.com>
>> > > > > <mailto:EnergyPlus_ Support%40yahoog roups.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@ yahoogroups. com >> <mailto:EnergyPlus_ Support%40yahoog roups.com>
>> > <mailto:EnergyPlus_ Support%40yahoog roups.com>
>> > > > <mailto:EnergyPlus_ Support%40yahoog roups.com>
>> > > > >
>> > > >
>> >
>> <mailto:EnergyPlus_ Support%40yahoog roups.com> <EnergyPlus_ Support%40yahoog roups.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-coefficie nt
>> > > > 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>>
>> <
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> <
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.eduUCF - From Promise to Prominence: Celebrating 40 Years