Author Topic: My tube cell, i need your ideas & suggestions  (Read 8306 times)

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My tube cell, i need your ideas & suggestions
« on: September 14, 2008, 18:59:58 pm »
Hi,
finally i got my steel tubes and set up my wfc.
4 tubes, each 12" long. Outer Diameter of the larger one is around 1",
but the gap is around "1 layer of electrical tape" and ~1mm.

There's the problem ;) I ran Ravi's/Dave Lawton's conditioning process for the first time today, and all was fine. But the different size of the gap annoyed me and after i changed the water after the first conditioning cycle some pipes had contact.
I now plan to redo the electrical tape isolation tomorrow, but maybe you have a tip what i could use as a spacer?

I had elastic band or thin plastic in my mind, but it didn't work out good, i couldn't get anything of that into the very small gap.
What do you use?


Second thing i noticed: In D14 it states "The MOSFET is rated for 22amp and should run very cool ...", i'm using the IRFP240 (200V,20A), and it gets hot, i had to mount a heat sink, but its getting hot in seconds (10V 2,5A). Is that okay or are your mosfets running cool?

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Re: My tube cell, i need your ideas & suggestions
« Reply #1 on: September 14, 2008, 20:30:57 pm »
in your picture it looks like the screws holding you outter connection on are touching the inner tube  that could be short causing your mosfet to get hot

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Re: My tube cell, i need your ideas & suggestions
« Reply #2 on: September 14, 2008, 20:41:48 pm »
the screws are isolated from the other tubes via the electrical tape. I paid attention to that point, they don't touch and i have measured it via multimeter. doesn't the voltage drop and the amps go up unnormaly high when a tube is short circuited? i once shorted my mosfet because i had forgotten to put a resistor in between and it draw 3.5 amps instead of the 0.1amps it normally does, anyway i'll take a look at that again tomorrow. thank you.


and thanks for the tip with the nylon, i'll look what i can do.

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Re: My tube cell, i need your ideas & suggestions
« Reply #3 on: September 15, 2008, 21:10:37 pm »
Okay i isolated the tubes again, again with electrical tape but more evenly. The ohmmeter on a scale of 20k ohms says they are definitely not touching each other, well the mosfet is getting hot, i'd say around 60-70°C, but i have to measure it. Hope it is okay with a RDSon of 0.18Ohms, especially with the heatsink.


By the way, some observations:
When i disassembled the tubes today i could see the white coating which had formed, it was very thin but very well bound to the tube (low amp conditioning), i had to use sanding paper to get the coating off.
The screws on the outer tubes got rusty after two hours of conditioning while the inner ones stayed normal. I'll replace them with stainless steel screws. The top area of the water got a light touch of gold/brown in it while conditioning, but no brown scum has formed.
I was using the water from our well and plan to change to rainwater or mix both to see if it works, so you can get your water for free if you aren't living in the center of africa where rain is as rare as gold.

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Re: My tube cell, i need your ideas & suggestions
« Reply #4 on: September 15, 2008, 22:30:03 pm »
Fortunely we have a shop which sells all types of screws in the amounts you want (from one single screw to as many you want), so i'll get me rust free ones tomorrow.
Thanks for the tip with the brass, an enermgency alternative ;)

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Re: My tube cell, i need your ideas & suggestions
« Reply #5 on: September 17, 2008, 21:05:05 pm »
damn, the electrical tape is losing grip with the tubes because of all the water and the white layer.
i'll disassemble it tomorrow and try super thin twisted yarn, nylon was too large, it won't fit in, even if the diameter is 0,8mm. it seems that i have a much closer gap as i thought of, no way its 1mm.


after i took out one inner pipe some minutes ago i could see the grey/white layer which had been built. while some of the powder is easily removed there is a thin layer which you can only scrub away with sanding paper. i'm curious to see this layer in a month and the change on amp draw and gas production.

after the third conditioning cycle i had the feeling the gas production already increased and the bubbles got bigger.
let's see... i'll keep you informed.

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Re: My tube cell, i need your ideas & suggestions
« Reply #6 on: September 19, 2008, 13:49:30 pm »
14.25 Watts into the system (pulse generator, mosfet -> tubes)
=> 1.5A * 9.5V

10seconds video

I noticed that with every conditioning cycle the watts i put into the system get lower, but if i put in more then 2 amps the coating flakes off partly, i'll think i'll only condition from 0.5A - 1.5A now. By the way 100% duty cycle while conditioning.

Maybe the tubes will be cut to 6" in length in order to minimize the way the gas has to go through the tubes.

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Re: My tube cell, i need your ideas & suggestions
« Reply #7 on: September 19, 2008, 15:40:02 pm »
i was using (plastic coated) copper wires from the beginning on, i don't have ss wires and i dont see how they could help. the resistance is much too high and depending on your setup they are not necessarily underwater, so the only advantage of ss wires is gone.

Second video: 2_8.3gp (1.2 MB)

Will measure the output compared to the input of the tubes next week. I'm hoping for more than 50% efficiency.
« Last Edit: September 19, 2008, 18:47:17 pm by haithar »