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EnergyPlus - Static Pressure Reset

asked 2023-05-15 11:54:29 -0500

Phan Truong's avatar

updated 2023-05-15 17:40:44 -0500

Hello, Is there a way to model static pressure reset in EnergyPlus? Most of the posts on this are older (i.e. https://unmethours.com/question/40768...), so wanted to see if there have been any new developments/example files.

This PNNL paper from 2017 suggests this:

Maximum Damper Position. This method simulates control of static pressure setpoints in response to the most open damper position in the VAV network. Ordinarily, a trim-and-respond feedback control would be used to maintain the most open damper at between 90 and 100%; however, because this cannot be done in EnergyPlus, a simple ratio is used to adjust the fan pressure rise. If the maximum damper command is 50% or lower, the fan pressure rise is set to half of its default value. If the maximum damper command is 95% or greater, the fan pressure rise is set to the full value. In between, the fan pressure rise is linearly reset.

How exactly is this implemented in the Fan Pressure Rise and Duct Static Pressure Reset Curves?

Thanks.

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answered 2023-05-19 16:02:01 -0500

The simplest, and most common, way to represent a DSP reset in EnergyPlus is to specify a different fan curve. Either the Good-SP-Reset curve (originally from DOE2, I believe) or the Perfect-SP-Reset curve (from Advanced VAV System Design Guide). See this plot showing various fan curves and their coefficients.

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Hi Eric, thanks for the reply. I have implemented these curves before in eQuest, but not sure how to do this in E+. Would I modify the Fan Pressure Rise or the Duct Static Pressure Reset Curve? From what I can see, the dependent variable here is not fraction of full load power as what you have in your curves. How would I use the coefficients you provided in E+? Thanks.

Phan Truong's avatar Phan Truong  ( 2023-05-22 13:03:11 -0500 )edit

You input these coefficients directly into the fan object. The dependent variable is full load power (PLF); the equation gives PLF as a function of flow fraction. Same as eQuest just in SI units instead of IP. See the documentation for Fan:VariableAirVolume, the example object using the curve coefficients labeled "EnergyPlus inlet vane dampers" in the plot I linked above.

ericmartinpe's avatar ericmartinpe  ( 2023-05-22 15:41:51 -0500 )edit

Got it, thanks for the clarification!

Phan Truong's avatar Phan Truong  ( 2023-05-22 15:54:32 -0500 )edit

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Asked: 2023-05-15 11:54:29 -0500

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Last updated: May 19 '23