Orionworks wrote:
Joshua,
I waited in anticipation to see if you could help explain to me the
errors I might have made in my reasoning. I was astonished to discover
that the jest of your replies struck me as being just as much of a
"seat-of-the-pants" explanation as you apparently accuse me of doing.
JC:
After all the water is converted to steam,
you can't convert any more water into steam.
You seem to be implying that there is a point where there might not be
any water left in Rossi's reactor core. Where did you come up with
that premise? I was always under the impression that there is ALWAYS a
supply of water replenishing what has been converted into steam.
What's your point?
Holy Mike, Steve, you're totally overlooking the obvious. Think about
it for a minute -- it's a simple energy balance problem.
The water flow rate is fixed, and if the flow is insufficient to carry
off all the heat as steam at 100C, then, by golly, the heat's still
gotta come out, and the steam's going to exit the beast hotter than 100C.
You can argue all day about what the internal structure of the thing
must be and where which drop of water flashes over to steam and what the
internal pressure might have been, but really none of that matters --
all you need is total output power and water flow rate, and you can tell
immediately what's going to be coming out the other end: hot water at
less than 100C, water mixed with steam at 100C, pure steam at 100C, or
pure superheated steam.
Hot water's easy to produce: the effluent phase is stable. If you're
making hot water and the output power varies a little bit, you'll still
be making hot water.
Water mixed with steam at 100C is stable: If the output power varies a
little bit you'll still be producing water mixed with steam at 100C.
The output power can apparently vary over a range of about a factor of
7, and you'll still be producing water mixed with steam at 100C (I
haven't checked the arithmetic on that claim but it's certainly in the
right ballpark).
Pure steam, hotter than 100C, is a stable effluent: If the power output
varies a little bit, you'll still be making pure steam at some
temperature above 100C.
Pure steam, at 100C, is *not* stable: If the output power varies just a
little, you'll either be making a mixture of water+steam (if the power
drops) or superheated steam (if the power increases).
To maintain the output in an unstable state you either need phenomenal
good luck or you need active feedback.
To assert that the output is maintained in an unstable state but that
there is no active feedback you need ... chutzpah.
I should have
stated more clearly the fact that as more energy (thermal heat) is
presumably generated within the reactor core a higher VOLUME of H2O
gas would naturally be produced. This translates to the simple fact of
physics where (assuming there is no deliberate containment going on) a
higher volume of gas has no choice left but exit the reactor core
chamber more quickly than it would do if the reactor core was cooler.
Therefore, the rapidly exiting H2O gas doesn't have much time to
absorb additional heat from the walls of the reactor core.
PV = nRT, guy.
Higher volume == higher temperature.
You can't have a larger volume of steam coming out without making the
steam hotter, too. Turn it around:
V = nRT/P
Pressure is fixed (1 atm), R is fixed (it's a constant), n is fixed by
the flow rate ... so if V goes up, T must go up, too.
And as I said, you can argue 'till you're blue in the face over exposure
times and wall temperatures, but all you're doing is obscuring the basic
simplicity of the problem, which is captured completely by the energy
balance.
If there's more heat produced than the exact amount needed to exactly
vaporize the water, and no more, the steam temperature will be higher --
probably quite a bit higher, as the specific heat of steam is very small
compared to the heat of vaporization of water.
