Stephen A. Lawrence <sa...@pobox.com> wrote:
> > - Finally, if the probe is actually in a backwash, dead zone, or side > channel, isolated from the main flow . . . > > In the Feb. 10 test, at 1 L/s there can be no such thing as a backwash or dead zone. This test also had a Delta-T as much as 31°C, which I think is impossible with any kind of barrier in the tube. The March 29 test had the slowest flow rate thus far reported: 500 ml over 278 s. That's 1.7 ml/s or 108 ml/min. I have never heard of a problem with dead spots or mixing at over 30 ml/min. However, in this test, the outlet temperature is measured in the "chimney." That is large enough to implement this trick fairly easily, with steam passing the thermocouple, well insulated from the stream of cold water. However, the outlet tube would be close to tap water temperature, which would be a dead giveaway. I am assuming someone had the sense to hold a hand near it or touch it for a moment. I would do that the moment I saw the test. To make the black tube hot, you have to imagine there is barrier within the hose that allows a thin layer of steam to pass on the outside at a high temperature without being cooled by the water in the center. It is moving at 1.7 ml/s. From the photo I suppose that hose is 1 cm OD and 0.8 cm ID, which is to say a volume of 0.5 cm^3 per centimeter of hose. So if the water is liquid, it is moving about 4 cm per second. It would cool down a short distance from the chimney. Real steam moving out of that hose would reach a lot farther than 4 cm per second, and heat the entire hose. There would still be a lot of steam coming out of the end of the hose in the bathroom. I think that is science fiction. By the way, regarding the hypothesis that wet steam has 20 times less enthalpy than dry steam, I thought back to the steam engines I used to play with as a child. I have one of them on the shelf here, a Wilesco D6 model: http://www.ministeam.com/acatalog/Wilesco_Steam_.html This steam is often quite wet when the machine first starts turning. A mixture of steam and hot water spurt out of the cylinder for quite a while before it finally comes out as clear (invisible) steam vapor. The total enthalpy can be estimated roughly by the speed of the turning wheel. You bank the fire a little and the wheel slows down immediately. I did not measure the revolutions but from the sound and vibration it is obvious that the RPMs are changing. I'm sure that if the enthalpy was only 1/20 of the total when the steam was wet, the wheel would not turn at all. There is quite a lot of friction from the cylinder and wheel bearings. I cannot imagine where the 95% of the heat from the flame would hide while the machine spits out a mixture of hot water and steam. - Jed
