Satamax Antone

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since Sep 24, 2011
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Southern alps, on the French side of the french /italian border 5000ft high Southern alpine climate.
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Recent posts by Satamax Antone

William LeMieux wrote:Satamax- I'm not sure what the animation is suppose to represent sir. Nor do I know what CSA or ISA means. If you would be so kind...



The animation is the movement of gases in a bell.

CSA, cross sectional area of the heat riser.

ISA internal surface area of a bell. Or pipes in the bench. Which is heat extraction surface.
5 days ago
Not taking the mick.



5 times CSA of a downdraft channel, i haven't spoken about ISA nor volume.
6 days ago
Well, i don't want to wreck your dreams. But to act vaguely as a bell, your downdraft tube should be 5 times the CSA of the heat riser. And that's an absolute minimum.

So, please, build it, and report.

Have you ever built a working Rocket before?
6 days ago

William LeMieux wrote:

Satamax Antone wrote:Hot gases tend to rise so in the downdraft leg you would be pushing hot gases down. Not sure the riser can push this.  It already strugles with a barrel without chimney.


But isn't the same thing happening with a bell system?

Nope

Hot gases tend to stagnate up top, and as these are cooling, they go down, and exit through the chimney. But because the volume of the bell is far bigger than heat riser and flue, the bell acts as a faster cooler than a downdraft channel, Reducing the hot plug effect.  A updraft/downdraft channel acts as a siphon, more or less, where the bell having more surface doesn't do this effect as much.  Gases, in the updraft/downdraft channel, have far less contact surface to cool down, hence stay hotter for a longer time, forming that hot plug, which doesn't happen in a bell. Theoretically this could happen in a bell, when all gases, and surrounding mass reach a steady state, being all at the same temp. But this can't happen as easily, as the bell's temperature exchange surface is bigger, and it's outer radiating surface is even bigger.
6 days ago
Hot gases tend to rise so in the downdraft leg you would be pushing hot gases down. Not sure the riser can push this.  It already strugles with a barrel without chimney.

1 week ago
Careful, downdraft tubes don't work very well in rockets. Most of the time.
1 week ago
Dioxin hasn't been tested soo far. But i doubt it can be very high.



IIRC, Most of dioxins are burned above 800C° And all above 900C°
1 week ago