Stephen A. Lawrence <> 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:

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

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