Static Efficiency in Fan

[ToysunStory]

Hi all,

I am about to write a new program for HVAC units design. I am using Nicotra's datas on it but there is a problem the datas Nicotra provided me. They gave me Total Efficiency of fan data but not Static Efficiency. I think I have to calculate it by myself. Is there anyone knows what the formula of Static Efficiency is?

Thanks all

 

[Drazen]

How did you come to "static efficiency"?

If you use the term in a manner I consider it, total efficiency is ratio of total fan airflow power (effective power exerted to air) to power input from prime mover's connection. I did not hear for such term as static efficiency, please try to explain.

 

[ToysunStory]

Actually I am not a mechanical and I don't know what is static efficiency. I can get Total efficiency by the datas but Nicotra's main program (ventil) usually gives that data too. If you want to look at it for me maybe you can help me to find a way.

Thanks

Ventil can be found:

http://www.nicotra.it/nicframe-it/areadwl/Ventil_312.zip

 

[Drazen]

Fan power on total pressure would be:

Nt = (Volume flow * total pressure loss)/(3600 * etat) in kW

Volume - volume flow in m3/h
Total pressure loss in Pa
etat - (toatal) fan efficiency, dimensionless or in %

Effiecency (call it total) should be etat = Nt/Noutp

Noutp - power output from electric motor in kW (not installed motor power input!)

So, fan power for static pressure would be:

Ns = (Volume flow * static pressure loss)/(3600 * etas) in kW

and static efficiency sould be etas = Ns/ Noutp,

but looking in a data at selection pages of your program, this data doesn't give adequate results.

(Total efficiency in percent should equal "fan power" divided by "motor power"). I presume "motor power" is given as motor power input, so you need to know motor efficiency, to calculate motor power output, and than you should be able to use formulas above.

 

[Drazen]

OK, I made additional check:

They assumed etat = etas, that is fan efficiency doesn't change with minor changes in working point (which is a bit illogical, that way they don't need term "total" and "static" efficency).

In that case

Total efficiency/Static efficiency = Total pressure/ Static pressure.

So Static efficiency = Total efficinecy * (Static pressure / total pressure)

There could be discussion are these terms they choose fully correct, but I beleive this formula can fulfill your needs.

 

[ToysunStory]

Thanks for your great help Drazen. You saved my life