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E+, defining DOAS fan specifications according to manufacturer's book

asked 2019-01-10 00:12:34 -0600

Alexis's avatar

updated 2019-01-18 03:04:13 -0600

I am a beginner with E+
Now, I trying to simulate and represent a DOAS according to the manufacturer's specifications.
I expect to have quite the same electrical power between E+ output and the manufacturer's specifications, in the purpose to have an accurate consumption. But, there is a difference of 36%. E+ gives me 1420 W. The book says 2200 W (green box below). I have set the pressure, the airflow rate according to the book.
The manufacturer doesn't mention the fan efficiency so I checked the reference/brand of the fan, they say that efficiency = 0.45%
image description

Did I do something wrong ? Do I miss something ? The "rated electric power" and "fan motor" (green box) should match ? The "supply fan delta pressure" is the "total static pressure" ?
Thank you for your feedback

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Fan rated electric power shouldn't be the same as fan motor power, as you have to account for motor and drive efficiency. Still, they shouldn't be that far apart.

mdahlhausen's avatar mdahlhausen  ( 2019-01-10 14:28:59 -0600 )edit

I don't expect to be exactly the same but close at least. The "rated electric power" should be more or less than "fan motor" specified in catalog ?
I have some doubt about the pressure, the "supply fan delta pressure" and the "total static pressure" have to be the same ?

Alexis's avatar Alexis  ( 2019-01-10 19:20:22 -0600 )edit

Here there is a post about the pressure input to the fan models, I hope it helps:

Bárbara Torregrosa's avatar Bárbara Torregrosa  ( 2019-01-14 11:17:23 -0600 )edit

I read this post and its what I did. Input the total static pressure in the field "supply fan delta pressure". But it gives me a very low "rated electric power" compared to the manufacturer's book

Alexis's avatar Alexis  ( 2019-01-14 18:47:56 -0600 )edit

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answered 2019-01-18 07:52:50 -0600

Bárbara Torregrosa's avatar

According to the Engineering Reference Manual (p.1044), the electric consumption of the fan is calculated as:

Rated electric power (W) = Maximum Fan Flow Rate (m3/s) * Fan Delta Pressure (Pa) / Fan Total Efficiency

This matches your results: 0.9*710/0.45 = 1420 W

In order to get the electric power you want, I would adjust the either the fan total efficiency or the delta pressure. According to the equations of the simple fan model in the manual, it seems those values aren't used anywhere else in the fan model.

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Thank you for your answer. If I understand well, the electric rated power should be equal to the fan power of the manufacturer ? So you suggest to play with the pressure and the efficiency to get the same value or quite the same

Alexis's avatar Alexis  ( 2019-01-18 08:34:53 -0600 )edit

@Bárbara Torregrosa Hello, I didn't find the formula of electric consumption of the fan that you quoted above. Could you please tell me which version of Engineering Reference Manual you were using? Thanks a lot!

Icy's avatar Icy  ( 2019-11-25 02:46:56 -0600 )edit

Sorry for the delay, I hadn't seen your comment. Probably you already found the formula. At that time, I was using EnergyPlus v9.0. In the Engineering Reference of EnergyPlus v9.1, the formula is in page 526 (Fan Sizing section).

Bárbara Torregrosa's avatar Bárbara Torregrosa  ( 2020-03-10 07:26:43 -0600 )edit

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Asked: 2019-01-10 00:12:34 -0600

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Last updated: Jan 18 '19