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RE: [T3] Stretching valve stems?


On 16 Nov 2005 at 9:12, Steve Jackson wrote:

> 100 C is only 212 degrees F; I would think the valve filled with sodium
> would have excellent thermal properties due to convection heat transfer
> via the sodium.  Not sure what the vibration would do to the convection
> patterns though, I guess that is why I am an electronic tech instead of
> a fluid dynamics engineer!

A heat pipe works by boiling the working fluid, so it's the boiling point 
that's important. 900 C works out to about 1650 F, which would be bright 
yellow. I don't know for sure, but I really doubt that even exhaust valves work 
that hot.

Just for fun, I looked up some other low boiling point elements:

sodium: 900 C (1650 F)
cesium: 690 C (1250 F)
sulfur: 445 C (800 F)
mercury: 356 C (650 F)
phosphorus: 280 C (540 F)
iodine: 185 C (333 F)
bromine: 58 C (140 F)

I don't know what the effects of these elements might be on steel, but I can't 
help wondering why sodium was chosen for this application.

-- 
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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