Are you a fan of fans? Centrifugal (I prefer to call Centripetal but that’s a tale for another day), Axial, Cross flow, whichever you like, fans can prove to be a challenging topic. A recent series in the Ashrae Journal discusses industrial fans, but what got me thinking about the topic of fans was a much smaller situation. PC computer fans.
Your standard 120 mm PC fan is a fairly homogenous product, but there also exist other fans in the same frame size with considerably higher energy use, cfm, and static pressure capability. These fans can be used to cool equipment, like say a bitcoin miner or a 4U server, sometimes coupled with a direct chip to water to air setup (something like this).
So which use of fans is best? 1 really impressive fan (like this) or 2 run of the mill fans stacked or 2 run of the mill fans next to each other (like these). The single fan consumes 30 watts, while the 2 fans consume 4 watts each. The 30 watt fan moves 240 cfm, while the cheapo fan moves 70 cfm. How much air do you need, and how much static pressure do you need? These fans get slapped in an application but they won’t move that same air volume with any resistance. That’s where the fan curves come into play.