On Oct 11, 2011, at 10:27 AM, Alan J Fletcher wrote:
At 01:37 AM 10/11/2011, Horace Heffner wrote: ......
In the section :
NO HEAT TRANSFER TO HEAT EXCHANGER UNTIL 13:22
19:22: "Measured outflow of primary circuit in heat exchanger,
supposedly condensed steam, to be
345 g in 180 seconds, giving a flow of 1.92 g/s. Temperature 23.2 °C."
you're using the flow after it was increased to cool down the system.
You should use Lewan's 0.9 g/s .. (or the pump's 2ml * 40 strokes/
minute = 1.33 g/s)
0.91 * 7800 seconds = 7.1 litres.
This system supposedly has one eCat, while Lewan's Sept version had
two or three, and needed 25 litres to start overflowing, so this
data is more consistent than most that we've seen from October.
I have significantly changed my review at:
http://www.mtaonline.net/~hheffner/Rossi6Oct2011Review.pdf
The following sections I think are relevant. Only very rough
estimates are provided because there is not enough data to go on for
accurate calculations. However, hopefully the basic concepts are OK.
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NO HEAT TRANSFER TO HEAT EXCHANGER UNTIL 13:22
The heat showed up in the exchanger at about 146 minutes, or 8760
seconds into the run. See appended graph, or see spreadsheet at:
http://www.mtaonline.net/~hheffner/Rossi6Oct2011.pdf
See appended graphs, or see spreadsheet at:
http://www.mtaonline.net/~hheffner/Rossi6Oct2011.pdf
In the ecat.com video at:
http://www.youtube.com/watch?v=EhvD4KuAEmo
at time 0:29, there were 30 strokes in 40 seconds, or about 45
strokes per minute. That is a maximum flow rate of (30 str/(40 s))*(2
ml/str) = 1.5 ml/sec, or 5.4 liters per hour, if the pump stroke were
set at 2 ml.
The earlier noted flow measurement of 0.9 g/s, by Lewan, was at the
output of the water/steam from the condenser heat exchanger. It
might have had nothing to do with with the actual pump rate. It only
had to do with the volume of steam being output, which is independent
of the volume of water being pumped in - unless overflow is
occurring, which seems unlikely at the early stage.
A flow of 1.5 ml/sec means the flow filled a void of (8760 s)*(1.5
ml/s) = 13.1 liters, or about 13 liters before hot water began to
either overflow or percolate out of the device, and thus make it to
the heat exchanger.
If overflow started after 13 liters then it would appear 81 - 12 = 68
liters were already present. The device weighed in at 98 kg before
the test and 99 kg after, when the water was drained, making this
impossible.
If the E-cat cold water input is 24°C and 12 liters were input, it
takes (4.2 J/(gm K)) *(13,000 gm))*(76K) = 4.15 MJ = 1.15 kWh to
heat the water to boiling.
CHARACTERISTICS OF THE CENTRAL MASS
Looking at the spread sheet, by time 146 the input energy Ein
reached was 4.446 kWh. This implies about 4.446 kWh - 1.15 kWh = 3.3
kWh = 11.88 MJ was required to heat up the thermal mass of metal in
the center of the E-cat, and immediately surrounding area.
Suppose there is a mass of iron between the cooling fins and heater.
There might also be a layer of higher thermal resistance between the
iron and the cooling fins. Use 50 kg as a rough guess at the mass of
the iron.
The specific heat capacity of iron is 0.46 J/(gm °C). The heat
capacity of 50 kg of iron is thus (0.46 J/(gm °C)) * ( 50,000 gm) =
2.3x10^4 J/°C.
Storing the 11.88 MJ requires a mean storage Delta T of (1.188x10^7
J)/(2.3x10^4 J/°C) = 516°C. Assuming the metal started out at 27°C
that means an iron temperature of 543°C.
This sets a limit on the period of heat after death boiling that can
occur. If the central metal is heated to 543°C, then energy stored
for boiling is 443°C * (2.3x10^4 J/°C) = 10.2 MJ.
To last through the heat after death period from 284 min. to 476 min.
= 192 min., the water boiling power output is limited to an average
of 10.2 MJ/(192 min.) = 885 W. Limiting the mean thermal output of
the stored thermal mass to a mean output of 885 W requires a
significant degree of thermal resistance between the thermal mass and
the water heat exchanger above the thermal mass.
At a midpoint of heat after death, thus a thermal mass delta T of 443°
C/2 = 222°C, i.e. delta T of 22°C to the boiling water, the thermal
resistance required between the thermal mass and the water is (222°C)/
(885 W) = 0.025 °C/W.
Registering a multi-kilowatt heat output at the heat exchanger then
requires that the Tout thermocouple be under the influence of the
steam/water mix, and that a mean output of 885 W provides a steam/
water mix that can drive the Tout reading up about 8°C.
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Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
