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Coefficient 2 of the Part Load Performance Curve input range

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

elvin's avatar
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elvin
asked 2016-04-12 09:13:35 -0500
__AmirRoth__'s avatar
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__AmirRoth__
updated 2017-05-04 06:53:22 -0500
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2 Answers

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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.

Julien Marrec's avatar
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Julien Marrec
answered 2016-04-12 13:59:36 -0500, updated 2016-04-13 11:33:39 -0500
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Not sure why the Mathjax isn't displaying correctly, when I edit the question it's working right.

Julien Marrec's avatar 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's avatar 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's avatar Julien Marrec (2016-04-13 11:06:25 -0500) edit
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2

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.

ericringold's avatar
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ericringold
answered 2016-04-13 11:21:13 -0500, updated 2016-04-13 11:22:21 -0500
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