On Sep 26, 2011, at 11:04 AM, Jed Rothwell wrote:
Horace Heffner <hheff...@mtaonline.net> wrote:
It is nice to see our views so closely aligned.
They are indeed.
I think running the steam and water through a condensing heat
exchanger works very well, provided *all* the flow and temperature
variables are recorded very frequently - more frequently than a
bucket test would allow . . .
For practical purposes, I do not think it is a good idea to
generate steam and water inside the machine. This erodes the pipes
and pumps. Defkalion's method is much better. They use fluid that
boils at a high temperatures and they leave it in liquid state. You
can generate steam in the secondary loop.
Yes, much better and more stable.
When evaluating the device, I do not see any reason to measure the
temperatures in the primary loop.
This depends highly on the feedback mechanism for the hot water, if
there is one, and whether the ability to control input water
temperature is needed. Rossi stated the hot water would be fed back
to E-cat. The most stable way to do that would be to create an
insulated reservoir, at room air pressure, and pump water from the
reservoir as is done now. The reservoir would present a good
probability of unmeasured heat loss. The varying temperature of the
input water creates a varying load on the condenser. The most stable
configuration would be to pump cold water into the E-cat and dump
the primary loop water, measuring its heat content first though. A
system of this kind, with feedback, would then have two inputs to
measure: (M1) cold water into the E-cat and (M2) cold water into the
heat exchanger secondary. The system would have two heat outputs:
(M3) hot water out of the heat exchanger secondary, and (M4) hot
water out of the heat exchanger primary, which could and probably
would involve a substantial amount of power. The measuring stations
Mi have to measure flow and temperature. Summing the two outputs
would be essential if a clean curve of (nearly instantaneous) power
out vs power in were desirable, or timely energy in vs energy out
curves. Measuring all four heat flows provides a means to decouple
the primary circuit output temperature (and pressure) from the E-cat
input temperature (and pressure). Water storage in the E-cat itself
need not be taken into account until the end of the run when cold
water is used to run out the numbers for final total energy
calculations.
It is feasible to build a calorimeter using only three measuring
stations, and I think this approach might be especially good for the
1 MW E-cat. This is accomplished by eliminating the heat exchanger
and simply merging the primary output and secondary input flows into
a continuous sparging condenser, with a single output into one
measuring station M3. The nice thing about this approach for the 1
MW E-cat is all that is needed for cooling is a 5 gal/min pump, some
big hose, and a lake or river. Water to the input measuring
station M1 could be pumped from any desired source. The output
water could be dumped, or air cooled and recycled to the secondary
input, with some recycled to the E-cat input reservoir. If a special
coolant is used, or high pressure primary operation is desired, the
four measuring station approach seems to me necessary to maintain
control of the E-cat, and to avoid heat loss errors for the system as
a whole.
As I said before, in a test to prove the thing is producing excess
energy, I see no reason to generate steam at all. Why not just use
hot water even if it is inefficient? Harry Veeder said that Rossi
is devoting all of this time to steam tests. Perhaps he is but he
can certainly spare a day to have someone do water tests. Since
people will be in the lab taking up space and interfering with his
work anyway, they might as well do a flowing water test.
Since the cooling solution is isolated from the catalyst it would be
possible to use car coolant solution (antifreeze). There are
pressure and temperature instability problems with recycling the
fluid, but not nearly as much as with boiling water.
The principle expense I would expect is in accurate digitally
interfaced flow meters. It is always good to have an independent
method to confirm results and to provide confidence in control run
calibrations.
Yes, this is essential.
[snip]
I think the temperature in such a bucket falls, or at least can
fall, significantly, considering a delta T measurement is being
made. The more accurate the delta T the longer the test and the
bigger the delta T, but then the more error due to heat loss unless
the bucket is insulated. Also, there is not just one calorimetry
constant at higher temperatures. There is a calorimetry function
by temperature (vs constant) due to nonlinear losses due to
evaporation and radiation.
This is not difficult to determine. Mizuno and others do it the
easy way. You fill the container with hot water at the peak
temperature of the experiment. You leave the stirrer running and
the data recorder collecting temperatures. Let it cool for an hour
or two, until it is close to room temperature again, and you will
see how much heat it loses at every temperature along the way.
there is probably a complex set of variables controlling the exact
rate at each temperature, depending upon stirring and other
factors, but you can simply measure it and then plug in the values
for each temperature ~5° apart.
Just thinking out loud a bit here. Yes I have measured temperature
decline curves, as I noted in earlier discussions about bucket and
barrel sparging. For example, page 9 ff in this reference is a
sample experiment I did in Dec. 1997:
http://www.mtaonline.net/~hheffner/BlueAEH.pdf
which shows some basic amateur calorimetry, including use of a post
experiment temperature decline curve to estimate heat loss thorough
the container walls, a technique which might be useful applied to a
barrel calorimeter, though it is obviously best to insulate the barrel.
It would be feasible to do a polynomial regression on the data to
obtain the decline function, integrate the polynomial, and enter the
temperature range and time over which the sparging occurred into a
programmed calculator. For longer term (barrel) sparging at variable
rates it would be feasible to use the data acquisition software to
integrate the heat loss.
Just babbling now. Loss of sleep.
- Jed
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
