Posted: Thu Jun 23, 2011 6:15 am
Any steam coming out at 100C, or 100.1C, or 101C on slight overpressure, is clearly not dry.D Tibbets wrote:Actually, my recollection was that his claim was that cool steam at ~ 100.1 degrees C. was more cloudy than hotter steam. That is false, except that condensation to small liquid water droplets would occur more quickly as there is less delta T to overcome. My counter argument in my previous post was that at the anticipated flow rates through a rubber (insulated) tube the DRY steam would not start to condense till well after it exited the tube.dch24 wrote:The other data Rossi presents clearly shows the steam is around 101C (at the thermocouple). Yeah, yeah, without a flow measurement we don't know the power output at that point.
But I don't think you'll get a lot of traction by attacking his assertion in the video, "it is very hot. Because it is so hot, the density is less." Realistically, he's not making a quantitative assertion there. I do think he's unrealistic, trying to explain the image by saying the steam is very hot -- I would expect that kind of talk from a salesman. Nevertheless, attacking it is not that interesting when Rossi freely shows the 101C measurement taken by the thermocouple.
As far as merely 100 degree C steam not being so hot, remember that if any steam (even if it is only ~ 15% of the water outflow like my guestimate) hits your hand, it will condense to liquid water, and this will quickly deposit 100Cal/ g of heat (the heat of vaporization). It will easily scald you.
Dan Tibbets
Dry steam would have some temperature higher than 100C. The chances of the heat output over time being constant and exactly balancing the water input rate X evaporation enthalphy+ inputer temp->100C specific heat is zero. Zilch. The evaporation enthalpy is large, even a 1% increase in output power above this would cause significant temp rise (I am sure somone can do the thermo calcs for this easier than me - my bet is it would be +10C at least - pure guess).
We have been told heat output varies greatly over time. So this is impossible.