[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]

Re: [T3] Stretching valve stems?


On 16 Nov 2005 at 0:37, Dave Hall wrote:

> > The sodium valves are mostly empty, with just a bit of solid sodium in them.
> At
> > operating temps, the sodium boils and carries heat very effectively to the top
> > (stem end) of the valve, where it condenses. It then runs back down to the
> head
> > end by gravity and the shaking of the valve.
> 
> Ah, ISTR doing some calculations on such heat pipes with water inside, to
> calculate the thermal 'conductivity' of the system.  Can't remember if it worked
> out better than solid or not, though.  Steam transfers a lot of heat, so I guess
> it's probably better.

If the liquid can return quickly to the heat source, it's an incredibly 
effective technique. As you know, it's all in the heat of vaporization, which 
is huge compared to other heat transfer methods.

Okay, I just looked up sodium's melting and boiling points, which turn out to 
be about 100 and 900 C, respectively. The melting point looks to me like it 
might be too high to be useful here, but I really don't know what temp a valve 
head sees. I'll ask around here and see what kind of opinions I come up with.

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

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]