air distribution trough holed duct 1

[pardal]

Hi all , I desire to calc how to distribute holes on a duct
so I can manage a given flow.

This is the task.

A 300 mm diameter 17000 mm length duct is to be perforated to handle 24 m3/minute of air, avaiable static pressure is 25 mm.

The duct will be at 3 meter hight , the area to be cooled is at 1,2 mt from floor.

The holes will be located at the 4 to 8 hour pattern.
Hope I make it clear , but if needed I can give more data on request.

Thanks in advance







Pardal

 

[arto]

Maybe try the industrial perforator's association handbook?

http://www.iperf.org/IPRF_CD.pdf

they have stuff on pressure drops

 

[bendit]

In designing cooling air distribution ducting for two large industrial buildings where cooling was critical to the process (investment casting), we used prefabricated coated nylon cloth ducting approximately 1 m in diameter x 30 m long. The air exit holes (each approx. 12 cm in diameter) were already cut into the cloth duct at approximately the 4 & 8 o'clock positions and spaced about 40 cm cc.

The ratio of airflow to duct diameter was such that the distribution duct acted as a plenum thereby providing almost unifrom internal pressure along the entire length of the cloth duct. The ducting was supported on small steel cables installed across the building.

As I remember (15 yrs ago !) The DX fan/coil units were arranged along both sides of the building and each suplied two of the cloth ducts. The angle between each of the ducts was maybe 25/30 degrees. Total cooling load was perhaps 150 tons.

This cloth duct system was very inexpensise and provided very uniform air distribution. Sorry, that I can't remember any sources of supply.