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Chiller heater performance curve

asked 2016-03-10 19:00:14 -0500

kbk78 gravatar image

updated 2016-03-10 19:01:32 -0500

I am evaluating the chiller heater system and working with the example file CentralChillerHeaterSystem_Cooling_Heating.idf

Perticularly, I am trying the find out the temperature dependence of performance curves. To evaluate this I created temperature independent curve as below:

Curve:Biquadratic,
ChillerHeaterHtgEIRFT_Const,   !- Name
1,                       !- Coefficient1 Constant
0,                       !- Coefficient2 x
0,                       !- Coefficient3 x**2
0,                       !- Coefficient4 y
0,                       !- Coefficient5 y**2
0,                       !- Coefficient6 x*y
4.44,                    !- Minimum Value of x
15.56,                   !- Maximum Value of x
35.0,                    !- Minimum Value of y
57.22,                   !- Maximum Value of y
,                        !- Minimum Curve Output
,                        !- Maximum Curve Output
Temperature,             !- Input Unit Type for X
Temperature,             !- Input Unit Type for Y
Dimensionless;           !- Output Unit Type

I output the "Chiller Heater EIR Temperature Modifier Multiplier Unit 1" hourly variable and anticipated the output to be a 0 or a 1 at all times. However I am getting fractional values indicating that the output of the above curve is not always 1.

Is this anticipated? I have attached the file with the modified curve.

C:\fakepath\CentralChillerHeaterSystem_Cooling_Heating_CurveTest.idf.jpg

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answered 2016-03-10 21:10:48 -0500

Chandan Sharma gravatar image

updated 2016-03-11 02:04:24 -0500

ChillerHeaterClgEIRFT should also be set to constant 1. Also reporting frequency should be set to detailed as hourly frequency aggregates the output value for an hour.

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It is set to one In the input file. All the capacity curves are also set to one. Reporting frequency is certainly hourly.

kbk78 gravatar imagekbk78 ( 2016-03-10 22:21:36 -0500 )edit

That seems odd. I just pulled CentralChillerHeaterSystem_Cooling_Heating.idf and set ChillerHeaterClgEIRFT and ChillerHeaterHtgEIRFT to 1 as you did above. It is giving 1 as output for Chiller Heater EIR Temperature Modifier Multiplier Unit X (X =1,2,3,4) for detailed frequency. Once it is verified that output is 1 as expected, reporting frequency can be changed back to hourly.

Chandan Sharma gravatar imageChandan Sharma ( 2016-03-11 01:58:01 -0500 )edit

reporting frequency detailed does give the anticipated results.Thanks.

kbk78 gravatar imagekbk78 ( 2016-03-11 09:03:06 -0500 )edit

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Asked: 2016-03-10 19:00:14 -0500

Seen: 151 times

Last updated: Mar 11 '16