Fan Sizing 1

[Bluzman]

I have a room I need to cool 5-10°F, using outside air only. The volume of the room is 20,000 cuft. The heat load is 200KW. What is the CFM of my fan?

 

[DRWeig]

Bluzman, your calcs are correct for the air volume. Just understand that with 95°F outdoor air and a 19°F delta T, your exhaust will be 114°F and your room temperature will be a gradient between the two, or 105° on average. Of course, it'll be warmer on a 100°F day. You can't make 85°F without refrigeration of some sort.

Best to you,

Goober Dave

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[317069]

you mentioned delta T twice as a 19 then as a 15F, but you didn't mention this delta between what? and how did you calculated.

 

[Drazen]

you will have to come to the understanding that you cannot use outside air of 100 degrees to get any temperature bellow 100 degrees. as someone mentioned, that comes out of fundamental thermodynamics.

in practice, it is impossible to get any meaningful heat rejection with delta t bellow 10-15, so at best you can reach 110-115 degrees with heat rejection.

 

[Bluzman]

Thanks I well aware see a few post up.
Looking at a average summer day 95f so a rise if ten degrees in the room is acceptable

 

[dbill74]

I don't see in your cooling load calcs any consideration for solar loads. If the room's ceiling is the roof or faces south, there could be a significant solar load on the space plus your internal equipment loads.