TR & cfm Selection of an AHU

[arcturus02]

There is a Gym Area, in cooling load estimation, grand total heat is 276522 BTU/h i.e 23.04 TR.
And dehumidified cfm is 5319 cfm. if i consider 1.0TR=400cfm. then TR = 13.30 TR.
So what should be the TR & cfm of AHU for the given area? how come? I'm confuse.
Thanks!

[Bashir01219]

What is your air change rate in the required room? Humidity range? Everything depends on cfm..........

[arcturus02]

design condition is 72F & 55 RH, adp 49.6. & ACPH is coming around 9.67.

[Bashir01219]

design condition is 72F & 55 RH, adp 49.6. & ACPH is coming around 9.67.
1 TR = 400 cfm, is not clear to me, from where u find it? It depends on lots of thing including ACR.
What is your design cfm for the unit, if their is any dehumidification unit then their should be two designed cfm and most probably their are pre & post cooling in ur system.
If you already achieved ur designed condition then ur cooling load calculation is faulty.
Did U consider line loss/Ducting loss?
What about exhaust, fresh air damper condition or 100% return for the AHU system?

[Magoo]

Gyms are a nightmare.
Fresh air, fresh air. Hot smelly sweaty bodies everywhere. Sucking in huge amounts of oxygen. Return air-regeneration is the most important factor, minimal. Ladies gyms add the refresh/ sanitizing /ozone / sterilizing factor . [ dare I say I say Fann* factor] Fresh air is cheaper, full recycled air NO WAY. definitly air sanitization with ozone generators

[GBRD]

Hi arcturus02,

You need min 9250 cfm for this AHU based on your conditions given above. Pl double check your demudified cfm before going ahead, your RSH should be 128678 BTU/h.....correct?

[B G Scott]

The air flow should be based on the Sensible Heat load.
From the Formula :

CFM = Room Sensible Heat
-----------------------
1.08x (Room temp F - Supply air temp F)

However your application will need to be plotted on a psychometric chart to establish the air mix condition as you will have a large amount of fresh air.

Give us the full details of your site requirements and I am sure people on this site will be able to help.

[B G Scott]

That did not print out well.

Read the formula

CFM = RSH Divded by 1.08 x (Rt F- Sa F)

[arcturus02]

thnx all 4 ur valuable replies :)