At 12:50 PM 7/14/2011, Joshua Cude wrote:
On Thu, Jul 14, 2011 at 10:30 AM, Abd ul-Rahman Lomax
<<mailto:a...@lomaxdesign.com>a...@lomaxdesign.com> wrote:
In many discussions of this, it was assumed that the only issue was
"steam quality." If we were to assume very wet steam, say 20% by
weight, we would then be able to infer excess heat, assuming
complete boiling (only merely "wet"), of about 3.6 kW. This is why
some think steam quality is a red herring.
I agree with much of what you wrote, but not with this. Very wet
steam is not 20% by weight (I assume you mean 20% liquid by weight);
it is 90% or 99% liquid by weight.
Semantics. Yes, steam can be much wetter than 20%, particularly after
condenstation, under marginal conditions it could approach 100%.
This, however, wouldn't be called "steam." It would be called "hot
water." We are here talking about what amounts to a boiler, and I was
looking for a "low" value for steam quality, for steam at the port of
such a boiler. Obviously, with various devices or arrangements, one
could get much wetter steam. By 20% I meant that 20% of the total
mass of the steam was liquid water, here considering that as mist,
i.e., "entrained microscopic droplets." Yes, this is 80% quality steam.
Steam that is 99% liquid by weight corresponds to "steam quality"
of 1%, and is still 94% gas by volume (at atmospheric pressure). In
the literature on two-phase flow, the charts show data with steam
quality below 1%, so this is not just a hypothetical fluid, in
spite of what Storms seems to think.
Whether the fluid is mainly a gas with entrained microscopic
droplets (wet steam or mist), or largely separated fluids, we don't
know. Inside the chimney, it is certainly possible to arrange the
conduits or design an atomizer to produce a mist with 99% liquid by
mass, but it seems reasonable that in the hose, where the diameter
is quite large, that some separation of the liquid and gas would
occur (in addition to some condensation). But it is important to
realize that even for a fraction of a per cent gas by mass, the
liquid cannot flow through the hose in the ordinary sense, where it
fills the hose. The volume of the gas exceeds the volume of the
liquid when only a part in 1000 of the water is vaporized (by mass).
That means it has to move through the hose faster, and the liquid
has to get out of its way. For a larger tube, this sort of flow is
usually annular or annular/mist, with a film of liquid flowing along
the walls, and the gas/mist flowing along the center of the tube.
If there is no excess heat, under these conditions, there might be a
small level of boiling, it's marginal and would depend on the exact
power and the accuracy of the flow rate. If there is some boiling,
the water and steam will be exiting the E-Cat at 100 C., as
observed. However, at minimum boiling, 2 ml/sec of water would be
flowing out through the hose to the drain. That water would be at
the boiling point, it would be "steamy," i.e., mist would rise from
it, plus any actual steam would create some visible steam flow.
I agree that 2 mL/s of water (liquid) would be flowing through the
hose, but I think your description of it is not apt. If 1% of the
liquid (by mass) were vaporized, then 94% of the fluid would be gas
(by volume), and what you would see would be dominated by this steam.
No, you've become confused here. 2 ml/s is the input flow rate. I.e.,
if the water is at 100 C., and there is the "minimum boiling," which
means there is an infinitesimal amount of boiling -- or, we could
say, none -- then the water flowing out would be 2 ml/s. What I wrote
about 2 ml/s of *water* flowing out would still be true, even though
with a *little* boiling, much more volume of steam will come off.
There was no expression of the ratio of water to steam.
The much less voluminous water would come out as a mixture of mist
and larger sputtered droplets. It's hard to think of it as flowing
out steamily, when steam occupies 94% of the volume.
If there is overflow water, it would flow into the hose, over the
threshold of the hose outlet, steam would flow above this water. Both
would be at 100 C. The steam would transfer more heat to the hose,
however, and would cool. The water would build up in the hose, with
condensed steam adding to it. It would fill up the hose to the level
of the drain. Steam would create some small pressure on the water,
forcing it up to the drain pipe.... I don't care to predict precisely
what would happen, and it would partly depend on the hose inside diameter....
Would water flow be visible from the hose? In the Krivit video,
Rossi holds up the hose to drain it before pulling the end from the
drain. If the hose is 16 mm inside diameter, the hose capacity is 5
g/cm, or 500 grams per meter. To fill a meter of hose would then
require 250 seconds. Rossi empties more than a meter of hose. There
is plenty of time to show the end of the hose with no visible water
flow and some steam and/or mist exiting.
Right. The water doesn't have to fill the entire hose and reach the
end before something happens though. It only has to block the hose
before the more voluminous steam behind it will cause some sort of
sputtering which might scald the holder of the hose.
Yes. So Rossi has a perfectly good reason for emptying the hose, and
this is so even if there is no overflow water, because of condensed
steam cooled by passage through the hose.
The time for such blockage presumably depends on how much of the
hose is lying at the lowest point (on the floor). And of course,
the hose probably wouldn't actually block completely.
The hose won't block, exactly, rather, water would flow instead of
steam. Exactly what happens would depend on the balance.
As the opening for the steam closed, you might expect the level of
sputtering to increase gradually until some kind of equilibrium is
reached. Rossi was clearly not interested in recording that on video.
Right. I figured that 2 g/s would fill a meter of hose in four
minutes. That's plenty of time to display the end without showing
water flowing out. Rossi easily emptied more than a meter of hose.
You just have to assume some (possibly small and possibly large)
level of liquid inclusion in the fluid, whether as a mist, or a film
on the wall of the hose, or some combination. I don't think "flow"
or "runoff" is descriptive of the sputtered, misty, spray of liquid
that seems likely to come out along with a much greater volume of steam.
Maybe. I was originally imagining better separation between the steam
and water. It could be frothy. It might not be very misty.
