Quote from: Sprocket on June 19, 2008, 04:57:54 PM
Air temp atm is 15 Celcius, which sounds about right.

Doing a quick comparasion between my last results and my kettle results doesn't inspire confidence (assuming my rough calculation is ok)

1.7L tap-water => avg power required = 2,000W * 320 secs (time to boil) = 640,000 joules.
400mL Distilled water => avg power required = (Avg Current) 4A * 230V (AC mains) *  150 (time to boil) = 138,000
Adjusting for different amounts of water => 138,000 * 1700 / 400 = 586,500 joules

640,000 versus 586,000 - Not a big difference...

Out of curiousity, I have just boiled the same 400mL of distilled water, then 400mL of tap-water in the kettle - both took 89 seconds.

400mL distilled water => 2000 * 89 sec = 178,000 joules

So, it is about 29% more efficient than my clapped-out kettle.

Finally, seeing that the currents being drawn are fairly low, I chanced boiling 400mL of tap-water with my Davey heater, with meter attached.  Time taken was 70 seconds.  Current starts at 4A, raises steadily, maxing at 7.8A on meter before falling to between 5.5-6.5A when boiling.  There is a lot of fluctuation in current, in sync with the bubbles being produced.

400mL tap-water => 7.8 * 230 * 70 = 125580 joules

The higher conductivity of my (crappy) tap-water seems to improve efficiency (42%) relative to my kettle.

All assuming my math is correct!

Hey Sprocket according to your last set of figures you're talking about a COP of 1.53.  When one gets figures like this it is time to get more serious about all the data.
Are you saying that :
Water Qty is 400ml
Start temp of water is 15 deg
End Temp is 100 deg
Time taken is 70 sec
And avg amps is 5.9 (start of 4 and end of 7.9)
If so COP is 1.53
Are you using a temperature guage on the water?

Hi guys,

Sorry for having disappeared. Very interresting posts...
I almost gave up but I'm motivated again..
------------------------------------------------
@EMdevices:
Yes, a COP about 1.5 (and tree times in a row!) would be interesting.
-----------------------------------------------
A couple of days ago (16/17 June), I tried other cups with thiner metal
"walls". I also tried to adjust the 2 cups distances or to build a device
with 2 similar cups. I have now almost 5 models of cups. I weighed my water
to check the accuracy of my measuring glass... Etc..
My results were discouraging with these new devices:  COPs between 0.81 and 0.91!

The COPs are slightly underestimated because I do take into account the fact
that the cups are also heated. But a short calculation shows that, for
example, a 160 grams iron device is eqivalent to about 17 grams of water. Is it not?
----------------------------------------------------------
I also tried to make electrolysis with my cups, results:
No measurable gas with tap water. Bubbles appreared, but, obviously, my
plastic "cell" leak. Pictures to come.

With distilled water + baking soda:
12 volts DC bat.
Amps consumption:
Begin= 8.8 A  - End = 10 A.
2 min O6 sec = 0.25 liters
3 min 50 sec  = 0.5  liters.
(3600/(3*60 + 50)) *0.5 = 7.8 litres/hour

Changing the polarity of the cups.
Amps consumption:
40" = 12.8 A
2 min 10 sec = 12.20 A
2 min 45 sec = 0.5 liters >>> (3600/(2*60+45)) *0.5= 10.9 liters/hour.
3 min = 11.8 amps

The water heat!!! I do not expect to run a landmover with that!
----------------------------
@Sprocket:
You gave me and idea! Distilled water.... Thanks. I will test that...
----------------------------
@Enki09: thanks for all your 'inputs'.
----------------------------

Best

Quote from: Sprocket on June 20, 2008, 03:26:41 PM
Attempting to take this up a level, so I sampled my inner bell's sound, found the fundamental frequency was pretty close to 1000Hz (933Hz), so ground it down till I got closer.  As you can see, not an ideal bell by any means, and hitting the magic 1000 proved illusive!  But I did look for effects between 990 -> 1010Hz with no success.  There's also a little soundfile attached - the bells sounds first, then a 1000Hz tone I generated for comparison.  As you can hear, (and see in pic.) they are pretty close.

So, question, am I right in thinking that 1000Hz is a harmonic of the 50Hz mains frequency?

The octave harmonics of 50Hz would be 100Hz, 200Hz, 400Hz, 800Hz, 1600Hz, 3200Hz, etc

I don't think it's the electricity that vibrates the bell but the electricity passing through the water at 60Hz having a 60Hz contraction expansion which is then aided by the bells also naturally vibrating at that same frequency. So it's the electricity to the water to the bell that the vibration propagates. The water becomes the hammer to the bell.

Quote from: DOCV on June 20, 2008, 06:48:14 PM
Hey Sprocket according to your last set of figures you're talking about a COP of 1.53.  When one gets figures like this it is time to get more serious about all the data.
Are you saying that :
Water Qty is 400ml
Start temp of water is 15 deg
End Temp is 100 deg
Time taken is 70 sec
And avg amps is 5.9 (start of 4 and end of 7.9)
If so COP is 1.53
Are you using a temperature guage on the water?

Make no mistake, I do not have a well-equipped lab here, so tend to err on the side of caution with regard to the measurments (ie. use max. rather than avg. current in calcs).  The 400mL is accurate, the start temp was current air temp at time of test, and the end boil-time taken from visual queues - vigorous boiling!

What does my kettle COP come to based on the measurments I posted?  If the COP is greater than 1, you will know my measurments are suspect!   Also, just did another test - different distilled water/baking soda solution, results were:

400mL distilled water @ 15 deg Celsius.
Start Current 1.8A, rising to 4.4A
Time taken to boil very vigourously 190 seconds

Personally, since I heard about "electrode boiler" (which is all this is) I have been looking for any info about the power Mr. Davey's device may have used, but can't find any!  Without some evidence that the power required was unexplainably small, we could well just be dealing with an electrode boiler here...

Quote from: storre on June 20, 2008, 08:56:01 PM
The octave harmonics of 50Hz would be 100Hz, 200Hz, 400Hz, 800Hz, 1600Hz, 3200Hz, etc

I don't think it's the electricity that vibrates the bell but the electricity passing through the water at 60Hz having a 60Hz contraction expansion which is then aided by the bells also naturally vibrating at that same frequency. So it's the electricity to the water to the bell that the vibration propagates. The water becomes the hammer to the bell.

Aha, thanks, that's what I needed to know!  Also sucks of course 'cos both 'bells' aren't suitable - small one 1000Hz, (after much work!) large one is about 825Hz...  Of course, it also means that there is a valid reason for it not having worked!