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Coefficient 2 of the Part Load Performance Curve input range

asked 2016-04-12 09:13:35 -0500

elvin gravatar image

updated 2017-05-04 06:53:22 -0500

I'm wondering if anyone knows the input range for "Coefficient 2 of the Part Load Performance Curve" for variable speed headered pumps.

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answered 2016-04-13 11:21:13 -0500

updated 2016-04-13 11:22:21 -0500

The EnergyPlus.idd file does not specify an input range for the pump coefficients:

N7, \field Coefficient 1 of the Part Load Performance Curve
     \default 0.0
N8, \field Coefficient 2 of the Part Load Performance Curve
     \default 1.0
N9, \field Coefficient 3 of the Part Load Performance Curve
     \default 0.0
N10, \field Coefficient 4 of the Part Load Performance Curve
     \default 0.0

However, the simulation will throw an error if pump power is negative, so you should probably stay away from negative coefficient values. You can see where the program is using the coefficients in the pump power calculation; there may be some other implicit limits based on what's physically realistic for pump operation.

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answered 2016-04-12 13:59:36 -0500

updated 2016-04-13 11:33:39 -0500

From the docs, the fraction of full load power is defined according to this equation

$$FractionFullLoadPower=C1 + C2 \times PLR + C3 \times PLR^2 + C4 \times PLR^3$$

c1, c2, c3, c4 = (0, 1, 0, 0) is the EnergyPlus default as highlighted in the EnergyPlus example files.

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Comments

Not sure why the Mathjax isn't displaying correctly, when I edit the question it's working right.

Julien Marrec gravatar image Julien Marrec  ( 2016-04-12 14:00:41 -0500 )edit

@Julien Marrec The markdown was confusing the asterisks as italics markers. Escaping them fixed the equation. I don't know why it's handled differently in the preview.

Neal Kruis gravatar image Neal Kruis  ( 2016-04-13 11:00:01 -0500 )edit

Ah ok, I didn't think about that. Next times I'll use \times (seems like markdown is not working in the comment box)

Julien Marrec gravatar image Julien Marrec  ( 2016-04-13 11:06:25 -0500 )edit

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Asked: 2016-04-12 09:13:35 -0500

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Last updated: Apr 13 '16