At 10:08 AM 7/18/2011, Jed Rothwell wrote:
P.J van Noorden wrote:
It is very important to notice that water boils at 100.5 C when the
outside air pressure is 1030 mBar, which can be the case when
a high pressure system is covering Italy . . .
In the April 28 tests, Lewan reported: "we calibrated the probe by
immersing it in a pot with boiling water, and the measured value was
then 99.6 degrees centigrade." Later during the test they measured
vapor at "about 100.5 degrees centigrade." There is no doubt that
was vapor, since it is substantially hotter than the boiling water,
plus you can see steam coming out of the pipe. I expect that
backpressure is minimal with this system.
Jed is correct here in one way. The boiling test rules out
"atmospheric pressure" as a cause of an increase boiling point.
However, Jed is not correct that "backpressure is minimal." Even a
little back pressure, from the steam, could cause the elevated temperature.
Whatever is the cause, that the temperature is nailed shows that
there is steam and water in equilibrium. This is not a characteristic
of dry steam.
Now, if the temperature record for the higher temperature shows
substantial variation, this would be different. It's not seen in,
say, the Kullander and Essen data. What is seen in the Lewan data is,
shall we say, puzzing, but there was some variation above boiling.
Problem is, they were sparging steam and they, themselves, said that
this explains the elevated temperature. I.e., back pressure.
