Is smaller better-plate size vs quantity

[madman]

Trying to figure out if it is better to have smaller plates with more stacks or larger plates with fewer stacks.

Lets say I am looking to produce 3 LPM at about 45 amps. 13.8 volts 6 neutrals so just over 2 volts per cell gap. Both units will have plate design of 2high x3wide, like 4x6 or 3x9. Standard bipolar build with water jet cut 316l plates,media blast,clean,passivate.condition plates, epdm gaskets,hpde endplates,high temp fittings, ss steel comp. bolts, etc.

Smaller: 4 stacks arrox 11 amps per stack so aprox 22 sq. inch per plate active area 29 plates -NNNNNN+NNNNNN-NNNNNN+NNNN

Lager:2 stack aprox 22 amps per stack so aprox44 sq. inch per plate active area 15 plates

Forgot charged plates will have tabs for dual conn, at opposite corners.

Madman

[myoldyourgold]

Trying to figure out if it is better to have smaller plates with more stacks or larger plates with fewer stacks.

Lets say I am looking to produce 3 LPM at about 45 amps. 13.8 volts 6 neutrals so just over 2 volts per cell gap. Both units will have plate design of 2high x3wide, like 4x6 or 3x9. Standard bipolar build with water jet cut 316l plates,media blast,clean,passivate.condition plates, epdm gaskets,hpde endplates,high temp fittings, ss steel comp. bolts, etc.

Smaller: 4 stacks arrox 11 amps per stack so aprox 22 sq. inch per plate active area 29 plates -NNNNNN+NNNNNN-NNNNNN+NNNN

Lager:2 stack aprox 22 amps per stack so aprox44 sq. inch per plate active area 15 plates

Forgot charged plates will have tabs for dual conn, at opposite corners.

Here is the difference. The less stacks you have in a bipolar setup the better the flow (shorter travel time for the gas) and easier it is to maintain equal electrolyte levels in all the cells. Center cells are always a problem in anthing over 2 stacks. The reverse is what happens in more stacks. I have found anything more than three stacks looses a measurable amount of efficiency. The most efficient is a single stack but there just is not enough gas produced so more plates are required, so there is a trade off. Remember with duel tabs on the power plates 1/2 the amps go in the top and 1/2 the bottom. Hope that helps.

[koya1893]

going with two stack with the center as the Cathode (+NNNNNN-NNNNNN+) without any holes, it's like having a single stack. Dual supply and exit fitting is a must, power them up seperately. also, incoroporate a dual reservoir to keep it cool. the secondary at the min 3-4 quarts capacity.

[BioFarmer93]

Hey Ben,
If the two stacks share a common center power plate, how would you power them up separately? Are you getting trickier than usual on us??

Carter, would not another benefit of fewer plates be lowered resistance?

[koya1893]

Gus,
I do better with pictures, I hope this helps. I also, shown the neg plate and the bipolars.

[myoldyourgold]

going with two stack with the center as the Anode (+NNNNNN-NNNNNN+)without any holes, it's like having a single stack. Dual supply and exit fitting is a must, power them up seperately. also, incoroporate a dual reservoir to keep it cool. the secondary at the min 3-4 quarts capacity.

A no hole center plates advantage is that there is NO current leakage between the two stacks, but the temperature goes up ever so little on the center plate, just slightly compared to a duel sided input / output with the center plate with holes, that is flowing evenly from both stacks which is almost impossible. The center plate is always hotter, it carries double the amps. If the reactor does not flow/fill/ or have equal levels then the center plate with the holes will have increased temperature. When I talk about flow it is gas flow not electrolyte. If the level is exactly the same in all the cells then temperatures are closer to the same. Gas flow and electrolyte level are what are important. A thicker center plate seams to help but there is a better solution. Because the center plate is a Unipolar plate there is only one solution to keep it as cool as the end two plates and that is going to 2 no hole plates separated by a special gasket. This is proprietary to me but I am giving permission to use it non commercially. The reactor will perform much better with no holes in a flooded state which is where most are running there reactors but will run a little hotter in a non flooded state but will still be better overall, everything else being right in a non flooded state. There are lots of variables here like port insulation, port location, duel connected power plates, size of the reservoir, pressure from the reservoir, and the list goes on and on. In my testing of bipolar 2 stack reactors with 2 plates with no holes and a special gasket with a section at the top and the bottom cut out, so some air can get in and flow out by convection. Both plates are the same polarity so no risk of shorting with moisture etc. Remember this is proprietary to me but can be used for no commercial purposes. Based on other tests I have done it runs better and almost eliminates the center heating problems and reducing overall temperatures in a two stack bipolar reactor making it a better reactor with only adding very little to the size.

Carter, would not another benefit of fewer plates be lowered resistance?

Yes and no. The center doing double duty is the problem. You are pushing twice the amount through. Yes it is better than the three or four stack though.

[madman]

Hey guys thanks for the input. Been working on my mini beast which has been a little challenging. Want to build something a bit easier. I only need 3LPM for the blazer.

What if I build 2 sep. units, single stacks with 6N and 2 Power plates and wire them in series. Each plate to have 44 sq. inch active . Use a ccpmw for a target of 44 amps.

Question 1: Since they are in series does the voltage and amps divide thus aprox. 2 volts per cell and 22 amps per unit

Question 2: Can I use single in and out ports which is the way my res. is set up now( 2 in 2 out)? Or do I need a sep. res. for each unit? Res. is 5 qt.

Mark

[myoldyourgold]

Hey guys thanks for the input. Been working on my mini beast which has been a little challenging. Want to build something a bit easier. I only need 3LPM for the blazer.

What if I build 2 sep. units, single stacks with 6N and 2 Power plates and wire them in series. Each plate to have 44 sq. inch active . Use a ccpmw for a target of 44 amps.

Question 1: Since they are in series does the voltage and amps divide thus aprox. 2 volts per cell and 22 amps per unit

Question 2: Can I use single in and out ports which is the way my res. is set up now( 2 in 2 out)? Or do I need a sep. res. for each unit? Res. is 5 qt.

Mark 2 separate units is OK. I do think you need to wire them in parallel and run each one at 22 amps. You will not have enough voltage to run anything if in series. Voltage will be divided by 14 if in series. If you are going to do that I would do it the way I explained. That way you save two ends but that is up to you. It depends on room available to mount the reactor(s).

You can run one reservoir just need to use y connectors.