Precool coil and AHU coil

1

Hi,

I googled so much but failed to find anything about how to add a precool coil in the AHU/VAV system.
I tried to use Ironbug to add a water coil and variable fan and setpoint in the OA stream, but the sizing doesn’t run correctly and the off-coil temperature of the precool coil doesn’t seem to work.
Is it because EnergyPlus doesn’t support PAU+AHU at all? If so, how do you model this system?

Regards,
Xavier

2

@XavierZhouLadybug
Is your “precool coil” meaning cooling coil with hot gas reheat?
any diagram will be helpful for me to understand.

3

Hi @MingboPeng, diagram attached.

Precool coil in OA stream diagram in OpenStudio
Precool coil in OA stream diagram in OpenStudio740×806 20.8 KB

4

Hi @XavierZhouLadybug This is how you add components in OA stream:

image
image1202×494 68.3 KB

5

Yes, that’s how I did it. I’ll tidy up my script and upload soon.

6

Hi @MingboPeng

Script attached.
20200308_test ironbug_to forum.gh (667.2 KB)

Thank you!

7

@XavierZhouLadybug so what’s your problem? It doesn’t run?

8

It can run. But the off-coil temperature of the PAU is not controlled.

node40 temperature
node40 temperature1890×1001 297 KB

9

@XavierZhouLadybug oh, ok, try this:
image

1 Like
10

It works! And I moved the fan before the coil, it works too!

However, I still encounter the following error. Can it be ignored?

  1. The simulation has not run correctly because of this severe error:
    ** Severe ** Calculation of cooling coil design UA failed for coil COIL COOLING WATER 1
11

Try to check the air/water temperature settings in this coil, the default value might be not working with your setpoint. And also check this coil’s sizing as well.