AHU design

[pramodpatil]

Dear All
pl tell me, How to design a AHU means cooling & heating coil dimensions, its rows, in & out temp of chilled & hot water, fan calculation etc.
thanks

[Brian_UK]

Start by reading as much as you can on the design of air handling units, fans, coils, belt drives etc.

Then attend a college providing training in the design and construction of these items.

Next gain employment at a manufacturer of these plant items, when you have received training from the senior members then you should be able to design an air handling unit yourself.

[Abby Normal]

Well you should know the entering condition of the air and a required leaving condition and the amount of air flow ahead of time.

You select coils that will cool and heat the air as needed.Perhaps there is a manufactuer's selection chart you can use or a program that gives you this.

Then you add up the pressure drop internal to your unit, what it takes to move the air through the coils, filters and whatever else you have inside your AHU. Then you make an allowance for the satatic pressure required to move the air through the ducts. For filters you may want to carry a pressure drop value you could expect when the filters are half loaded with dirt.

Then you select a fan, the drives to give you the correct RPM and the required motor size.

[Abby Normal]

The height and width of the unit will all be based on the cooling coil because you do not to have mositure carryover.

If your coil is too small, the air flows too fast through the coil and it 'pulls' the condensate off of the coil.

So a rule of dumb to make sure this does not happen is to size your cooling coil for a 'face velocity' of 500 feet per minute as a maximum.

"multiply by 0.3048 and divide by 60"