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Re: [EnergyPlus_Support] Converting DOE-2 Chiller curves to EnergyPlus
It is a little tricky to convert these curves in a spreadsheet. I have
done this before and it is always good to check your work by "testing"
the DOE and Energyplus curves with F and C temperature data to see if
you get the same answer with both curves. When developing curves, always
check the Engineering Reference to make sure you know what the
independent variables are. The reformulated EIR chiller model uses
"leaving" condenser water temp, so always be careful when doing this. In
a spreadsheet, set up these equations and use [(T-32)/1.8] and
[(T+32)*1.8]*[(T+32)*1.8] in the required places. Then multiply out
these equation until you are left with just the T's with a coefficient
and all other constants are combined with the equation constant (a)..
For example, b*CWSf = b*[(CWSc+32)*1.8] = b*1.8 * CWSc + b*32*1.8. The
"b*32*1.8" becomes part of the new constant a. Do this type of
conversion on the whole equation.
When you finalize the new Energyplus coefficients, test both the DOE and
Energyplus curve outputs by multiplying out the equation with the
corresponding temperature (F or C) to see that they match. You will
probably find a mistake in this step and can then revise the conversion
until you get the same answer with both curves. When the answers match,
you know you have the correct coefficients. Once this spreadsheet is
correct, all you have to do is enter the coefficients for a new chiller,
and you will automatically calculate the Energyplus coefficients (so set
up your spreadsheet to this will be easy the next time). I just looked
and I can not find the spreadsheet I used before.
From the IDD for Chiller:Electric:EIR:
A2 , \field Cooling Capacity Function of Temperature Curve Name
\object-list BiquadraticCurves
\note curve = a + b*CWS + c*CWS**2 + d*ECT + e*ECT**2 + f*CWS*ECT
\note CWS = supply (leaving) chilled water temperature(C)
\note ECT = entering condenser fluid temperature(C)
A3 , \field Electric Input to Cooling Output Ratio Function of
Temperature Curve Name
\note Electric Input Ratio (EIR) as a function of temperature
\note EIR = 1/COP
\object-list BiquadraticCurves
\note curve = a + b*CWS + c*CWS**2 + d*ECT + e*ECT**2 + f*CWS*ECT
\note CWS = supply (leaving) chilled water temperature(C)
\note ECT = entering condenser fluid temperature(C)
A4 , \field Electric Input to Cooling Output Ratio Function of Part
Load Ratio Curve Name
\note Electric Input Ratio (EIR) as a function of Part Load Ratio
(PLR)
\note EIR = 1/COP
\object-list QuadraticCurves
\note quadratic curve = a + b*PLR + c*PLR**2
\note PLR = part load ratio (cooling load/steady-state capacity)
Zhen Tian wrote:
>
>
> Hello all,
>
> I have question regarding converting the DOE-2 electric chiller curves
> to EnergyPlus Chiller:Electric:EIR curves.
>
> For the part load ratio curve, as it is a quadratic performace curve
> with only one variable, it is easy to convert from DOE-2 curve to
> EneryPlus curve.
>
> The problem is in the other two curves: cooling capacity function of
> temperature curve and electric input to cooling output ratio function
> of temperature curve. These two are biquadratic curves with two
> variables and also need to convert the degree F in DOE-2 to degree C
> in EnergyPlus at the same time. I am wondering is there any easy way
> to convert these DOE-2 curves to EnergyPlus curves? Is it possible to
> convert within tools such as Excel?
>
> Thank you. Any advice will be appreciated.
>
> Regards,
>
> David
>
>
>
--
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
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