modified FAN power curve doesn't work

I am using EnergyPlus 9.2 and OpenStudio 2.9 for modeling with an RTU+VAV HVAC system. I initially used the default fan power curve settings and had a successful simulation. However, after modifying the fan power curve to use the ratio of actual airflow to the maximum design airflow, I encountered errors, specifically indicating that surface temperatures are too high. Can someone provide assistance with this issue? Thank you very much."

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Please add some IDF snippets showing what curve you used, and onto what object.

Julien Marrec (2023-10-16 08:12:32 -0500) edit

Thank you,I repost my IDF snippets . Pleast help me check what's going wrong.

just a undergraduated (2023-10-16 20:57:07 -0500) edit

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The coefficients make no sense.

Here's a plot of the resulting PLF. PLF should generally be in the [0, 1] range, here it explodes to more than 2200.

image description

See the I/O reference: https://bigladdersoftware.com/epx/doc...

The python code I used to plot it

def plf(flow_fraction):
    c1 = 10.553 
    c2 = 3432.2 
    c3 = -1244.2
    c4 = 0.0
    c5 = 0.0
    return (
        c1 + 
        c2*flow_fraction +
        c3 * pow(flow_fraction, 2) +
        c4 * pow(flow_fraction, 3) +
        c5 * pow(flow_fraction, 4)
    )

flow_fractions = np.arange(0, 1.01, 0.05)
plfs = plf(flow_fractions)

fig, ax = plt.subplots(figsize=(8, 4))
ax.plot(flow_fractions, plfs)

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Julien Marrec

answered 2023-10-17 14:40:52 -0500, updated 2023-10-17 14:41:31 -0500