Here we show the third run of small-scale experiments....
We did another run naked with no insulation jacket, basically the same as Test One detailed earlier, but with the refinement of weighing the envelope while it was hanging up before introduction of steam. (The umbilicus was arranged to impose as little burden upon the scales as possible). The envelope dry weight was 600 gm. Then the envelope was inflated with steam as before. The hanging-type scales can be seen in this photo:
In the steady-state with the envelope full of steam, the scales read 510 gm, so this Steam Balloon appeared to be 90 gm lighter than when it was empty. The implications of this are as follows: since the volume of the envelope is 0.6 m3, the lift of the steam filling it is actually 383 gm (see the basic physics page), and therefore we can determine that the mass of water trickling down the envelope is about 290 gm. Since the area of the envelope is 3.5 m2, the mass of trickling-down water per square meter is 84 grams. This is a very important figure to know.
The amounts of condensate collected were as follows.
First 30 minutes, 2600 gm;
Second 30 minutes, 2650 gm.
Again deducting 1000 gm/hour, as in the previous cases, and dividing by 3.5 square meters of area, we now get the result:
Naked condensation rate - 1.21 kg/m2.hour
We must admit that we don't know why this result differs somewhat from the result of Test One. Perhaps in this case there was a small quantity of air in the envelope, although we did our best to eliminate it.
At the end of this test we took down the envelope as quickly as possible, briskly squeezed out of it all the steam but none of the water which had been trickling down, and weighed it. The weight was 890 gm. This was as perfect a confirmation of the fact that the mass of water trickling down the envelope was around 290 gm, as one could possibly wish for!
Anyway, we had evidently done all that we could with this small-scale experimental rig, so we proceeded to the mid-scale experiments.
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