I thought I'd see what you guys think a about a design topic that came up at work today. We have a series of cabinets that contain computers that need to stay cool. My question is about fan placement and airflow. I think the single cabinet works perfectly. Using the cabinets in a daisychain fashion isn't so smart. It might work and just the amount of air might just make it okay. But each cabinet venting out the top is a better way to do it. I tried to draw the ideas below.
In series is not as effective, cabinet temp will get hotter and hotter as you go further right, since each cabinet is taking in heat from the cabinet to the left. It's a Human Centipede of heat.
Give each cabinet an independent intake and exhaust (you could pull from the bottom and vent out the back...maybe with "manifolds" if that helps - great place for a central intake filter).
BTW keep in mind that a smaller number of big fans is quieter and more efficient than a big number of small fans. They make fans all the way up to 200mm for computers now.
rather than blowing hot air from the middle cabinets into the outer.. how about some ducting? to a separate fan on the outside cabinet?
mad_machine wrote: rather than blowing hot air from the middle cabinets into the outer.. how about some ducting? to a separate fan on the outside cabinet?
Same problem but with less fans - you want airflow in parallel for even cooling.
I don't know how much space you have available around the cabinets for external ducting, so here's a thought for doing it inside the cabinets.
In the area where the exhaust fans are shown (upper rear quadrant), instead build a duct of the largest possible diameter, vented on the bottom. Use fans as indicated, though depending on the efficiency of the ducting and the CFM of the fans, it may not be necessary to use one per cabinet. This arrangement should pull (via Bernoulli Effect) hot air up and into the airstream, while isolating it from the other cabinets. The duct could be insulated if needed for further efficiency.
You should also consider that you can do without exhaust fans entirely, and in a way that makes it easy to filter out dust - look up positive pressure air cooling.
Old arcade video games used convective cooling.
Instead of porting the outlet into the neighboring cabinet, can you port it out the back? Or the top?
"It's a Human Centipede of heat" The sad thing its it's built and done. During it's use I'll try to see if I can plant some digital thermometers in each cabinet. It's for (2) rather critical 10 hour days. I'll be back with data in a few weeks. Thanks guys.
Create a plenum at the back of the cabinets that are all tied together with a single larger exhaust fan at one end with intake ports of gradually increasing size as distance from exhaust increases
I should have mentioned the cabinets must be reused in various configurations, single and multiple. Keeping them modular and as a system a requirement.
If you want to correct the problem with minimal disruption, I'd say you should make new mounting points for the upper fans on the back or top of the case and move them there, and cover the old holes with some kind of tape or sticker you can slap on quickly. You could do this to the units one at a time.
Just curious, what is this for? Some kind of cluster computing system with removable nodes?
These are for tradeshow use. So they have to keep the stuff cool, easy to ship, quick to set up and be aesthetically pleasing.
How big are the cabinets? How much power in each PC?
Lots of new computer tech is extremely heat efficient compared to the past, so its easy to get away with much less cooling.
And I agree with the others that providing each spot with its own intake/exhaust is going to offer the best performance.
there are whitepapers on this.... lemme see if i can find them...
freestyle wrote: I thought I'd see what you guys think a about a design topic that came up at work today. We have a series of cabinets that contain computers that need to stay cool. My question is about fan placement and airflow. I think the single cabinet works perfectly. Using the cabinets in a daisychain fashion isn't so smart. It might work and just the amount of air might just make it okay. But each cabinet venting out the top is a better way to do it. I tried to draw the ideas below.
make the wall between cabinets 2 and 3 solid, with the airflow going out to the left from 1 and 2, and out to the right on 3 and 4.. this way, the worst case is that the cabinets on the end each have the heat from 2 computers instead of 3 or 4.. but honestly, i don't think it would be much of an issue no matter how you do it as long as the fans are strong enough to keep air moving since there is constant airflow up and away from each computer at all times.
The computers vary, so we typically over design it. We use (2)100cfm fans in these displays. I just want to make it efficient with what we use instead of throwing horsepower at it. (Yes, I autocross a Miata)
novaderrik, I like your idea of using the center cabinets as the intake and blowing towards 1 and 4. We can do that easily.
the front panel layout is almost more critical... dangit i cant find the whitepaper...
What's above them?
Exhaust them up, and call it a day. Then they will all be identical, and can be installed in any order.
freestyle wrote: The computers vary, so we typically over design it. We use (2)100cfm fans in these displays. I just want to make it efficient with what we use instead of throwing horsepower at it. (Yes, I autocross a Miata) novaderrik, I like your idea of using the center cabinets as the intake and blowing towards 1 and 4. We can do that easily.
keep the intakes on all 4- that way they all have the same cooler air coming in.
The top of the cabinets hold a monitor and keyboard. That must be perfect and beautiful. Ideally no vents on top
you could make it perfect and beautiful and still have vents. Think Rack mount vent.. usually a black anodized piece of metal with holes drilled into it. We use them in dimmer and amp racks.
You never said if you could have vents in the back.. if you can, think of something like this. It's slim, quiet, and while a little pricy, sure to move a lot of air reliably
Thanks mad_machine. Those are great looking vents. I could incorporate those into a design nicely in the future.
There are times we can vent out the back, but not this time.
I think a passive setup with a vent panel on the top towards the back and a generously sized kick panel intake would probably suffice. No fans=less noise and ongoing maintenance.
This 19" 2U steel vent panel is $12.99. Other styles, sizes and materials are available.
freestyle wrote: The top of the cabinets hold a monitor and keyboard. That must be perfect and beautiful. Ideally no vents on top
Add a false back to the top section, so the "perfect and beautiful" part is about 3" shallower than the bottom. Then you can have unlimited venting up, and the ability to use them independently and interchangeably in any configuration.
It will also give you the opportunity for them to function as freestanding kiosks, and you can use the backs for display surface.
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