Gas mark 5
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- Leeds / Harwell, UK
I'm doing an EPQ thing - "Extended Project Qualification" at school, and apparently we can do literally anything for it, and get a grade at the end. So I naturally checked with our supervisor, and yes, creating a working prototype lawnmower engine running off hydrogen gas is a perfectly good idea!
I'm not after any of these magic products that will run my... engine, forever, using the power from the ... engine, to generate hydrogen (perpetual motion? ). But I know simply running an engine off hydrogen is possible at least.
I know the basics, and I've got a rough idea in my head of how I want to do this, but I'm really desperately looking for more sources of information. I don't have any chums at university who can analyse gasses for me or anything like that, so if anyone here can provide helpful advice, or suggest where I might look for more information it really would be great!
So, my current plan. I've got a pair of identical Suffolk Colt lawnmower engines, one of which I want to leave standard, the other convert to hydrogen and compare them. As far as the conversion goes, I know I need to set the timing at roughly TDC, I'll play around and see what works best. I don't know if the valve timing is adjustable on these engines, I'll have to investigate that. I was planning to keep it simple, so just remove the carburettor altogether and have it free breathing, like a diesel. Then I can inject the hydrogen right next to the intake valve, preventing any large build ups of gas which could be dramatic. As for injecting it, I was thinking maybe those hypodermic syringe needles or something, I don't know if they would be to small. Then just regulate the flow of the gas for a throttle.
I know one of the main problems is preignition, and there are lots of complicated things I can do about it, exhaust gas recirculation and so on, but I thought I might get away with it with this size engine (75cc) and such a low compression ratio (Actually, I don't know what it is, but it doesn't feel like much ).
As for getting the hydrogen, I was thinking of renting a BOC bottle or something, but they seem a bit big / expensive for me, plus I'd have to find all the correct regulators, special air lines and so on. And I'm not sure I trust myself with that much flammable gas...
So I was planning to make it on the spot with electrolysis. I've done it before when I was young on a small scale, just filling up little balloons and popping them. I like the idea of several sandwiched sheets of stainless steel, alternating positive to negative. The efficiency of a cell is better the closer the electrodes are to each other, from what I gather. I was going to use Potassium Hydroxide as the electrolyte. My theory on this is somewhat dodgy, despite me doing AS level chemistry, but wikipedia seems to suggest with a base as my electrolyte no oxygen gas would be given off at the positive electrode. This would be great, but I'm sure I have done this before and see oxygen given off,albeit in small quantities. If there are significant quantities of oxygen given off, I think it will be difficult separating the gasses without significantly reducing the efficiency of the cell. If I can produce gas at the rate the engine uses it it won't be a problem, because at any one time there'll never be large quantities of gas around, but I highly doubt I'll be able to get that sort of flow rate, meaning I'll have to store it up for a bit. This is only a prototype, I just want it to idle for a minute, so I shouldn't need much hopefully, I don't know if I can just fill up a bunch of balloons or something then run it from that for any meaningful length of time. Also I don't know how unstable a mix of hydrogen and oxygen is. I know it makes a really cool bang, but is it likely to just spontaneously combust? Is it safe to store it even for a few minutes in balloons??
So yes, there's my initial ideas, sorry for the essay. I've got a vague plan in my head, and I'm happy to experiment and see what works, but if anyone knows anything at all about this please say! I want more information, are there any good books on the subject? Any people I should contact? Anything at all would be good!
Thanks!
George
I'm not after any of these magic products that will run my... engine, forever, using the power from the ... engine, to generate hydrogen (perpetual motion? ). But I know simply running an engine off hydrogen is possible at least.
I know the basics, and I've got a rough idea in my head of how I want to do this, but I'm really desperately looking for more sources of information. I don't have any chums at university who can analyse gasses for me or anything like that, so if anyone here can provide helpful advice, or suggest where I might look for more information it really would be great!
So, my current plan. I've got a pair of identical Suffolk Colt lawnmower engines, one of which I want to leave standard, the other convert to hydrogen and compare them. As far as the conversion goes, I know I need to set the timing at roughly TDC, I'll play around and see what works best. I don't know if the valve timing is adjustable on these engines, I'll have to investigate that. I was planning to keep it simple, so just remove the carburettor altogether and have it free breathing, like a diesel. Then I can inject the hydrogen right next to the intake valve, preventing any large build ups of gas which could be dramatic. As for injecting it, I was thinking maybe those hypodermic syringe needles or something, I don't know if they would be to small. Then just regulate the flow of the gas for a throttle.
I know one of the main problems is preignition, and there are lots of complicated things I can do about it, exhaust gas recirculation and so on, but I thought I might get away with it with this size engine (75cc) and such a low compression ratio (Actually, I don't know what it is, but it doesn't feel like much ).
As for getting the hydrogen, I was thinking of renting a BOC bottle or something, but they seem a bit big / expensive for me, plus I'd have to find all the correct regulators, special air lines and so on. And I'm not sure I trust myself with that much flammable gas...
So I was planning to make it on the spot with electrolysis. I've done it before when I was young on a small scale, just filling up little balloons and popping them. I like the idea of several sandwiched sheets of stainless steel, alternating positive to negative. The efficiency of a cell is better the closer the electrodes are to each other, from what I gather. I was going to use Potassium Hydroxide as the electrolyte. My theory on this is somewhat dodgy, despite me doing AS level chemistry, but wikipedia seems to suggest with a base as my electrolyte no oxygen gas would be given off at the positive electrode. This would be great, but I'm sure I have done this before and see oxygen given off,albeit in small quantities. If there are significant quantities of oxygen given off, I think it will be difficult separating the gasses without significantly reducing the efficiency of the cell. If I can produce gas at the rate the engine uses it it won't be a problem, because at any one time there'll never be large quantities of gas around, but I highly doubt I'll be able to get that sort of flow rate, meaning I'll have to store it up for a bit. This is only a prototype, I just want it to idle for a minute, so I shouldn't need much hopefully, I don't know if I can just fill up a bunch of balloons or something then run it from that for any meaningful length of time. Also I don't know how unstable a mix of hydrogen and oxygen is. I know it makes a really cool bang, but is it likely to just spontaneously combust? Is it safe to store it even for a few minutes in balloons??
So yes, there's my initial ideas, sorry for the essay. I've got a vague plan in my head, and I'm happy to experiment and see what works, but if anyone knows anything at all about this please say! I want more information, are there any good books on the subject? Any people I should contact? Anything at all would be good!
Thanks!
George