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...one of the many tests lined up on my 'todo' list. I will let you know how i get on.
Statistics: Posted by golden_guppy — Thu Dec 29, 2005 9:40 am
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All of the information I present here is from the following page and my limited (but growing) undestanding of things:
I found this web page VERY enlightening... and it may explain problems I have read others had with unexplained current changes in their electrolysers. The whole page is worth reading IMHO, even if some of it is mind numbing for those of us who were not able to go to college. But I won't make you read it if you don't want to... The long and short of it is this:
"The rate of hydrogen gas formation can be increased by increasing the electrical current through electrolyte and electrodes in the electrolysis cell."
Ok, I know, that is not so exciting yet... but hold on... that statement was preceded by a lot of explanation, and documented experimentation from which I draw a couple of conclusions. Now, I am no electrical engineer, so please feel free to correct me on this part if I am wrong. But as best as I can understand it, there are two major factors in determining increased current and therefore increased hydrogen and oxygen liberation. To use the analogy of cars travelling down a highway. If you want to increase the number cars per hour that can travel a stretch of highway you have two options.
1) Wider highway and therefore more cars (electrons) can travel it at the same time.
Now, much like in the analogy itself, there is only one way to increase the number of electrons that can make the journey at a time. You have to widen the highway, or in our case, increase the surface area of the electrodes.
2) Make the cars (electrons) trip faster.
Now, there are two options to making the trip faster. Keeping with the car analogy consider the following:
1) One obvious way to make the trip faster is to make it shorter right? If you shorten the stretch of highway, you are obviously going to get more cars (electrons) through that stretch in a given period of time, compared to a long stretch of highway.
However if your on ramp is connected directly to the off ramp then they didn't really travel on the highway at all did they? Likewise if we short the electrodes then all of the electrons will follow that path and if they never get on the Water highway, they will liberate no hydrogen nor oxygen. In our case there is another consideration. If our electrodes are so close together that the bubbles can touch both electrodes they may be even harder to dislodge themselve and come to the surface. Now it may seem great to have a bunch of big bubbles on your electrodes. But consider that those bubbles are blocking lanes on your highway. If bubbles are covering 20% of the electrode surface, then you have just managed to successfully reduce your efficiency by 20%. So we want them close but not too close. How close is too close???? If you know, tell me too... A like AntDavisons setup, but 2mm seems a bit tight to me. That doesnt mean it is. but it seems like it. I would love to know for sure. One thing is for sure.
2) We can also make them faster by reducing resistance. We increase the speed limit as it were, to allow them to travel at a higher rate of speed thereby travelling the same distance in a shorter period of time.
Guess how many ways there are to do this??? If you guessed two then pat yourself on the back...
1) One is to increase the level of the alkali salts used (i.e. KOH, NaOH). I believe that at some point (probably somewhere above the recommended 28%), you will probably start causing more problems than you solve. We must keep in mind that we are trying to increase the current to the end that we want to make more hydrogen. If we simply want to make the current move quickly from the postive side of the battery to the negative side then you can just take a foot long piece of metal and touch both poles. I don't think you will like the results...
That is it... We are down to my final point and the real purpose of this by now rather lengthy post...
2) Temperature. Whats that? The temperature you say? That doesn't affect the electrical resistance does it? Well, if this is the first time you have heard this, then GREAT! That means I am not alone in never having heard anything about it. But according to the experiments conducted in the page I linked to at the top Temperature does have an impact on efficiency via electrical resistance.
As with everything there are limits. This doesn't mean you can go to extremes to achive spectacular results. But it is certainly worth noting. Not sure if you are all up in the Northern Hemisphere with me, but up here it is winter and most of us probably experiment in our cold garage, shed, outside etc. According to that page the difference in resistance between electrolyte that is at approx. 45.5 F or 7.5 C and electrolyte that is approx. 145.4 F or 63 C can mean the difference of 89 kiloohms of resistance and that of 1 kiloohm. Did you get that? About 100 degrees F or 55.5 degrees C can mean a difference of 89 times the efficiency!?!?!?!
I have to run for now, but bear in mind that if the heat is coming entirely from the electrolisys then that is bad... heat is generated from lost efficiency. We arent going to achive 100% efficiency or anything, but that doesn't mean that we want to count on our on inefficiency to generate heat to increase efficiency... that is kinda counter productive. But if we can keep the electrolisys process from generating any unnecessary heat, and yet maintain a relatively high temperature for the electrolyte then we can be pretty darn efficient.
So where do we get the heat from? how do we keep it from messing up the Cell? What about steam??? I have a few thoughts on those as well, but they will have to wait until I get home... will post again then... until I do... please tell me what you think?
Thanks,
SDG
Statistics: Posted by SumDumGuy — Wed Dec 28, 2005 8:18 pm
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