Need help with fan flows/pressure (Fans fighting)

[jasno999]

I have3 a strange situation and I don't even knwo whre to begin in terms of analysis. What I have is a fan that is suckign air out of a space thru a hole in the wall of the space.

However in that hole is a box that takes up most of the hole opening. Therfore I only have the space between the wall edge and the box, or gap, from which air can be sucked out of the space thru the fan locatd over the box.

Now the interesting thing is that the box is actually goign to have a internal fan inside of it that is goign to be blowing air out of the front of the box into the space. Therfoe this air will be goign in the opposite direction of the air being sucked out of the space.

I knwo it sounds trange but this is a real problem I am workign on trying to understand. The concearns are that the internal fan may stall if pressure differences are too great or that the air being blown out of the box may simply be blown back into the area that hte box is sittin in and therefore back into the box (creating a loop of air).

I have some data on each fan but I jsut don't know how to even start looking at thsi type of problem. I need some help startign with the basics.

HEre is a picture that may illistrate what I am working with:

Or try this if that link does not work:

http://i96.photobucket.com/albums/l194/jasno999/Information/FAN.jpg

 

[gcomyn]

Can you duct the air leaving the box away from the opening?

 

[jasno999]

No.

There is a strange looking housing that the box and fan above it are sitting in that I did not show but that is the next step. I need to figure out the 1st step for now.

There is no way to duct it cause there is no room and the box can nto be turend or moved.

 

[STYMIEDPIPER]

Something just isn't right with your situation.
How wide is this gap around perimeter of box?? Sound/looks as if your box is actually housing of the fan in wall
Sight unseen, I would plug the gap with compatible material and install a new exhaust fan elsewhere in the space(right side in your picture). Better design, hence better flow.
The velocity of the air moving thru the gap (right to left in your picture) cannot possibly overcome the velocity of the air in the opposite direction from the fan in the wall.

Stop making a bad situatuion worse--Bite the bullet and install new exhaust fan where good design dictates.
You need to describe your situation better--what is in the two spaces?? Why are you trying to pull air thru the gap??

 

[jasno999]

Ha ha. If only it were so easy. Ok let me explain some more.

The box houses some electrical equipment inside of it and used to be cooled via convesction from the air being sucked out of the space thru the opening in the wall and over the box. Now the box is new and they have built in a fan for convection cooling of the equipment in the box. Great idea but the problem is we do not want to blow air intothe space and we don't know what woudl happen if you even tried to blow air into the space while also suckign air out of the space with the other fan.