Stick computers in oil

Spring 2009

Engr 45

By,

Sergy Pretetsky &

Jeff Hitchcock

Why computers need cooling

• Greater conductivity at low temperatures

• Avoid critical failure

• Overheating= over stressing components

Common Computer cooling

• Air cooled heatsinks

• Water cooling

• Peltier cooling

• Phase change cooling

• Liquid nitrogen & Dry ice and acetone

Thermal properties(water vs. air)

• Volumetric Heat capacity (Jcm-3K-1)– Water - 4.186– Air - 0.001297

• Thermal conductivity (W/(m·K))– Water - 0.6– Air - 0.025

• Heat Transfer Coefficients– Water – 500-10,000 W/(m2K) – Air – 10-100 W/(m2K)

Thermal properties(water vs. oil)

• Volumetric Heat capacity (Jcm-3K-1)– Water - 4.186– Oil - ~2 (FAR more than air)

• Thermal conductivity (W/(m·K))– Water - 0.6– Oil - .15 (60 times more than air)

• Heat Transfer Coefficients– Water – 500-10,000 W/(m2K) – Oil – ?

The complete set up

The Tub

The Oil

The Computer submerged

The Overclocking test

Thermal paste test

ResultsLong term test

• Processing remained the same

• Problems– Plastics– Heat retention in oil

ResultsOverclocking Test

• With oil– no additional performance

• Old computer– possibly maxed out components– If we had new computer, could have pushed it further

ResultsThermal Paste test

• Out of 3 popular thermal pastes– 1 was dissolved away– 2 were unaffected

• @ RT– Possibly more degrading at running temps

Conclusion• With an old computer

– Didn’t help boost performance• Didn’t cause failure

What to do next time• Use a radiator to cool the oil• Keep power supply separate

Sources

• http://en.wikipedia.org/wiki/Specific_heat_capacity• http://en.wikipedia.org/wiki/Heat_transfer_coefficient• http://www.medwelljournals.com/fulltext/jeas/2006/495-4

99.pdf• http://www.mobil.com/USA-English/Lubes/PDS/glxxenpvl

momobil1_truck_suv_5w-30.pdf• http://www.engineeringtoolbox.com/thermal-conductivity-

d_429.html