As part of my work, I needed a cluster of Raspberry Pi’s to host various analytics and web applications but somewhere in the planning process I got it my head to cool it by submerging it in oil and use a pump to create a circulation vortex.

The reason for this is the Oil keeps the CPUs significantly cooler than air cooling and the vortex constantly interchanges this heat with the air.

Here it is in action:

It consists of:

  • Six Pis (in my case it was a mix of Rock64 and Pi3)
  • Mineral Oil to submerge (also known as paraffin oil)
  • 12V Bilge Pump to create the flow
  • 3D Printed fins to force the flow to rotate
  • an 8 port network switch at the bottom with the case removed

Ultimately, I no longer use this system because it turns out another use for Paraffin Oil is as a powerful laxative and for whatever reason my dog decided it was great to drink from the tank 🤦 leading to visit to the vet and the worst possible disaster to clean up…

I have lost the original CAD files - but here is a view of the blade assembly image

Printed in two parts

image

Also here is an alternate design with a 5v 120mm fan - as you can see this would be enough to circulate the oil but not enough for the vortex effect (which I never was fully satisfied with)