|
Post by silverdragon on Nov 20, 2012 9:45:15 GMT
Appologies... I missed that for some reason... I will read that article and see if it agrees with what I was thinking then.....
|
|
|
Post by alabastersandman on Nov 21, 2012 6:19:40 GMT
Why couldn't water cooling be used? From my understanding, White Oak has closed cells and will hold water just fine. I'm toying with the idea of making my bathroom counter and sink from White Oak, just cause. The flow could be convection fed. I haven't come up with an idea for a radiator yet but I'm sure something could be figured out. What about plant based oils for lubrication? Linseed oil for example? If they could be kept from igniting they should work pretty good. Leather would make a good substitute for piston rings, but how about wrapping the piston in leather? This would act as not only a seal, but also to prevent splitting as well as keep the piston at a more stable moisture level, which in turn would prevent excessive expansion and contraction. Other materials such as rubber (for hoses, seals, etc.) could certainly be used without deviating too much from being made of wood, as rubber is derived from a tree. The reason normal water cooling could not be used is wood doesn't transfer heat very fast. The metal of an engine block is very good at getting the heat that occurs at the cylinder wall to the coolant. Wood on the other hand, is about 50x worse at moving heat. So although water in the cylinder might be able to take the heat off the cylinder walls, water flowing through the engine block would not pick up enough of the heat to keep the cylinder walls from being burnt to a crisp. Thus the abandonment of the traditional coolant design (mostly) and the discussion about in-cylinder cooling. Unless you have some insight? Not sure if it would be enough but I did have a rough idea of how I might give it a go. Whether used as the actual cylinder wall or not, I would chuck up "wads" of white oak and turn individual cylinder heads. What I envisioned would roughly copy the fin structure on motorcycle engines, where the wood fins would add rigidity around the circumference, yet allow for a thinner cylinder wall between the fins. This structure would then be enclosed/wrapped by steaming several ply's of white oak (or other wood). Obviously each fin would need at least one opening to allow the water to flow from the bottom of the cylinder wall to the top. Then the water would be fed to whatever "radiator" was used. No matter the configuration, the only issue I can see with using too hard of a wood would be that the harder a wood is, in general the more brittle it will be. That could be a show stopper in such a hostile environment as a combustion chamber. With a bit of playing around, I'm sure the right combination of hardness and flexibility would be found. White Oak may be too brittle as well. The only reason I brought it up is that I have been told that the wood has closed cells and would hold water well. Of course there are several woods that have a high natural oil content that water would not affect adversely. Bloodwood comes to mind, as well as the already mentioned, tried and true Lignum Vitae. It might turn out that a wood that can soak up a bit of water may hold up better. An example of a wood that will definitely be too brittle is Ebony. Aside from the brittleness it may be ideal, but it is very brittle indeed. I've had Ebony split from simply drilling it too fast. I don't mean just hogging through it either, when drilling 2" to 3" of Ebony you need to stop often and let it cool before proceeding or it will split from the heat. A softer wood will take the heat without splitting, nearly right up to combustion temps.
|
|
|
Post by chriso on Nov 21, 2012 6:30:13 GMT
Don't quite get what your describing, or how it gets around the low heat transfer rate of wood. Could you possibly find a picture? The reason normal water cooling could not be used is wood doesn't transfer heat very fast. The metal of an engine block is very good at getting the heat that occurs at the cylinder wall to the coolant. Wood on the other hand, is about 50x worse at moving heat. So although water in the cylinder might be able to take the heat off the cylinder walls, water flowing through the engine block would not pick up enough of the heat to keep the cylinder walls from being burnt to a crisp. Thus the abandonment of the traditional coolant design (mostly) and the discussion about in-cylinder cooling. Unless you have some insight? Not sure if it would be enough but I did have a rough idea of how I might give it a go. Whether used as the actual cylinder wall or not, I would chuck up "wads" of white oak and turn individual cylinder heads. What I envisioned would roughly copy the fin structure on motorcycle engines, where the wood fins would add rigidity around the circumference, yet allow for a thinner cylinder wall between the fins. This structure would then be enclosed/wrapped by steaming several ply's of white oak (or other wood). Obviously each fin would need at least one opening to allow the water to flow from the bottom of the cylinder wall to the top. Then the water would be fed to whatever "radiator" was used. No matter the configuration, the only issue I can see with using too hard of a wood would be that the harder a wood is, in general the more brittle it will be. That could be a show stopper in such a hostile environment as a combustion chamber. With a bit of playing around, I'm sure the right combination of hardness and flexibility would be found. White Oak may be too brittle as well. The only reason I brought it up is that I have been told that the wood has closed cells and would hold water well. Of course there are several woods that have a high natural oil content that water would not affect adversely. Bloodwood comes to mind, as well as the already mentioned, tried and true Lignum Vitae. It might turn out that a wood that can soak up a bit of water may hold up better. An example of a wood that will definitely be too brittle is Ebony. Aside from the brittleness it may be ideal, but it is very brittle indeed. I've had Ebony split from simply drilling it too fast. I don't mean just hogging through it either, when drilling 2" to 3" of Ebony you need to stop often and let it cool before proceeding or it will split from the heat. A softer wood will take the heat without splitting, nearly right up to combustion temps.
|
|
|
Post by alabastersandman on Nov 25, 2012 10:28:49 GMT
Sorry about the shoddy drawings, I used to be able to draw a line where I wanted one, not so much anymore. Anyway, you should be able to see what I was attempting to describe. The horizontal (or diagonal) fins would give the head some added strength while leaving openings for water to flow along a path closer to the bore. Not sure if this would work but it's the first thing I thought of as a possible way of cooling the head with water. Cutaway View: Cross Section View:
|
|
|
Post by chriso on Nov 25, 2012 23:30:11 GMT
That greatly clarifies things, thanks! And don't worry about the drawing, a lot better than something I could do.
I still don't know whether it could conduct enough heat to keep from burning through, but this looks promising as a traditional cooling system. I suspect that it still wouldn't transfer heat fast enough if the inner wall is thick enough to not burst. Maybe some exotic wood that transfers heat fast... anyhow, how thick do you think the inner wall would have to be?
|
|
|
Post by alabastersandman on Nov 26, 2012 6:05:27 GMT
How thin/thick? That is a good question, not sure I have a good answer. However off the top of my head I would venture a wild guess that if it couldn't be made to hold together with the thinnest part around a quarter inch or so/less, it probably would not transfer heat fast enough.
I'd also venture a wild guess that the smaller the bore, the better the chances of success would be. Might want to use more but smaller cylinders as opposed to fewer large cylinders.
I drew the fins rather far apart just to simplify the drawing, but envisioned them much closer together, perhaps 1/4" to 3/8" apart this would significantly add to the strength. Keeping the inner wall of the water chamber concave should allow it's thinnest point to go pretty thin without leaving an excessively weak spot. It would be fun to play around with this and see if it would actually work. Of course there is the issue of cooling the hot water as well, making a wood radiator may prove harder to accomplish than getting a cylinder head to hold together (dowels bored out with twigs and leaves protruding? Not really serious about that one).
|
|
|
Post by silverdragon on Nov 26, 2012 8:38:45 GMT
Can I venture an idea.... This may involve some strange idea, but, how Valid, I am not sure. If the cylinder walls could be made as a sort of "Double hull" idea, which is the best description that fits, to include the water cooling INSIDE the engine cylinder block?....
The water would need to be at pressure to prevent the combustion chamber blowing through, but if you had as a cross section, combustion chamber, thin-ish wall, water "bath", then STRONG wall, how viable is that?....
I am expecting some seepage through the walls at this point, so the fuel mix would have to take account of the fact the cylinder walls may be damp, but could combustion take place in that environment, and could it lead to a semi- sort of Steam power anyway as the water on the cylinder walls flashes to steam that would increase combustion pressure?....
As always, I am trying to think outside of normal, because what is normal anyway and why let that limit design?....
We dont HAVE to go for a fast RPM, a slower long stroke would be entirely necessary in my opinion to reduce wear anyway.
|
|
|
Post by silverdragon on Nov 26, 2012 8:45:55 GMT
Ok Call me crazy, how about a light oil as coolant instead of water on the above idea?...
The oil (I am thinking something like Olive oil for some crazy reason) would lubricate as well as cool, and seepage would not be a problem....
Otherwise, is using Fuel as coolant just TOO crazy?...
This the seepage would aid combustion?....
Again, thinking strange ideas is my speciality, someone has too, otherwise who the heck would have invented Cats eyes as road markers...........
|
|
|
Post by chriso on Nov 26, 2012 9:21:41 GMT
Can I venture an idea.... This may involve some strange idea, but, how Valid, I am not sure. If the cylinder walls could be made as a sort of "Double hull" idea, which is the best description that fits, to include the water cooling INSIDE the engine cylinder block?.... The water would need to be at pressure to prevent the combustion chamber blowing through, but if you had as a cross section, combustion chamber, thin-ish wall, water "bath", then STRONG wall, how viable is that?.... I am expecting some seepage through the walls at this point, so the fuel mix would have to take account of the fact the cylinder walls may be damp, but could combustion take place in that environment, and could it lead to a semi- sort of Steam power anyway as the water on the cylinder walls flashes to steam that would increase combustion pressure?.... As always, I am trying to think outside of normal, because what is normal anyway and why let that limit design?.... We dont HAVE to go for a fast RPM, a slower long stroke would be entirely necessary in my opinion to reduce wear anyway. That would be one of the advantages of the design alabaster proposed. As for pressurizing the thing, didn't consider that, but what would it do when the pressure gets low? Wouldn't it still burst?
|
|
|
Post by silverdragon on Nov 27, 2012 6:21:55 GMT
Hmm... thinking... how about using the piston pressure with some clever 1-way valves to pump the water through the cylinder block?.. that would equalise the pressure?....
|
|
|
Post by alabastersandman on Nov 27, 2012 6:37:05 GMT
I think you have some great thoughts there SD. I like the idea of using pressurized coolant to help offset the outward pressure. Considering that water does not compress, even at low pressure the cylinder wall should not be able to move much, under higher pressure once things got warmed up, the cylinder wall should reap some benefit from the higher pressured coolant allowing (relatively) higher revs, I think.
Here's a question; What would make a reasonably good blast that would be comparable to the fuel-air mixture in an ICE? What about gunpowder? How much? Half a cup? (just kidding). I suppose just putting a bit of gasoline in there would work as well, but again how much would be about right? A milliliter? Less? If I get time I might bore out some wood and turn it down on the lathe and wrap it in 5-6 ply's of whatever I can find at the Woodcraft store.
Here's another; Any thoughts on whether the coolant would move well enough using only convection? I'm doubtful myself though I have no real knowledge of such a system and what limitations there may be with it.
|
|
|
Post by alabastersandman on Nov 27, 2012 6:42:25 GMT
Hmm... thinking... how about using the piston pressure with some clever 1-way valves to pump the water through the cylinder block?.. that would equalise the pressure?.... Perhaps the block pressure from the down-stroke could be utilized? A pump of some sort would be beneficial.
|
|
|
Post by alabastersandman on Dec 2, 2012 4:50:55 GMT
Started yet another project I don't know when I'll get around to finishing. This one is way out of my usual woodworking , or metalworking, or... but I'm going to give it a go anyway. I can't work on it full time, have other sawdust to make too. I'm thinking I can make most of it with wood. Got an old snow blower in the lower garage that needs a carb rebuild, it was leaking gas last time I used it, planning on robing some parts off it, like the carburetor and that stuff needed to get some spark. I have no idea what I'm doing when it comes to this sort of thing, just Google'd "2 cycle" images and am going from there. Think I'll break down, or just break, the snow blower engine and take a closer look before drilling the ports. Starting the connecting rod: Connecting rod, piston, and part of crankshaft with Lignum Vitae Bushing. Guts are of Black Walnut, and the lighter wood I'm not sure what it is. That came from what was once standing dead wood that blew down about 4 years ago in the back lot, might be Elm:
|
|
|
Post by chriso on Dec 2, 2012 5:37:29 GMT
Your actually trying it!!!? Nice! Just don't test it without a blast screen of some kind... metal, not wood. And run it by someone who knows what they are doing before testing it... Also, might want to check out alcohol-water mixtures to keep it running cool. I am still convinced you are not going to get enough cooling through a piece of wood, even with that special design, and are going to have to push water into the cylinder
|
|
|
Post by alabastersandman on Dec 3, 2012 9:12:17 GMT
Your actually trying it!!!? Nice! Just don't test it without a blast screen of some kind... metal, not wood. And run it by someone who knows what they are doing before testing it... Also, might want to check out alcohol-water mixtures to keep it running cool. I am still convinced you are not going to get enough cooling through a piece of wood, even with that special design, and are going to have to push water into the cylinder The alcohol-water sounds interesting, I'll look into that, any idea if a "standard" carburetor will work with an alcohol-water mixture? As far as water-cooling through the fins goes, I'll probably feed it with a hose and just let it run out on the ground after it cycle's through. At least that way it will always be cold water going in. If the thing doesn't blow into toothpicks or go up in a mini inferno, I'll think about ways to pump the water under it's own power. It just occurred to me that the water temp coming out against the water temp going in would give me some indication of how much heat is being transferred. With cold water going in, if it comes out warm or something close to hot that will be a good thing. If it comes out cold or even not much warmer than it went in, not so good. Got the crank together:
|
|
|
Post by alabastersandman on Dec 3, 2012 9:31:36 GMT
Hmm... thinking... how about using the piston pressure with some clever 1-way valves to pump the water through the cylinder block?.. that would equalise the pressure?.... I don't think block pressure could be used to pump water in a two-stroke, as the block pressure created during the power stroke is used to push the fuel-air mixture through the transfer port and into the combustion chamber. Perhaps on a four-stroke?
|
|
|
Post by freegan on Dec 3, 2012 10:33:22 GMT
Hmm... thinking... how about using the piston pressure with some clever 1-way valves to pump the water through the cylinder block?.. that would equalise the pressure?.... I don't think block pressure could be used to pump water in a two-stroke, as the block pressure created during the power stroke is used to push the fuel-air mixture through the transfer port and into the combustion chamber. Perhaps on a four-stroke? However, a nozzle for atomizing water placed at the same height as the 2-stroke's transfer port's exit into the chamber, would be 'gated' by the piston in the same way that it 'gates' the fuel air mixture. Experimentation and adjustment would, of course, be required to achieve the optimum cooling and power output.
|
|
|
Post by silverdragon on Dec 4, 2012 8:38:35 GMT
May I suggest running the thing initially using something bigger than a "starter motor"... an electric drill perhaps?... low speed of course.....
|
|
|
Post by OziRiS on Dec 16, 2012 0:33:37 GMT
I'm not adding anything to the discussion here, but can I just draw everyone's attention to the fact of how INCREDIBLY COOL it is that alabastersandman is actually attempting to build this thing!?
I don't care if you fail miserably at this. The mere fact that you're willing to pour your energy and obvious skill into this is just awesome!
Bigass virtual high five for you! ;D
|
|
|
Post by alabastersandman on Dec 21, 2012 6:31:28 GMT
I'm not adding anything to the discussion here, but can I just draw everyone's attention to the fact of how INCREDIBLY COOL it is that alabastersandman is actually attempting to build this thing!? I don't care if you fail miserably at this. The mere fact that you're willing to pour your energy and obvious skill into this is just awesome! Bigass virtual high five for you! ;D Thanks for that! Had a bit of a set-back on that project. The chunk of wood I was using as it turns out has some rather alarming defects, there is considerable checking in the wood. But that's okay, I am still using it to figure out just how I can put this together and then I will use different wood. This gives me room to make some mistakes that can potentially be avoided in the next phase. I am also trying to work out what a good solution to movement of the wood in service (warping, expansion, contraction, etc). The block of wood moved a bit and the cylinder went a bit out of round. I went to re-bore it to clean it up and didn't clamp the block down as I should of, the bit caught the wood on one side and grabbed the block spinning it wildly on the drill press. That bent the 1/2" shank on the 2" Forstner bit I was using. Thinking about going to White Oak but I will look more into the properties of the wood before I make a decision. I also am looking into using wood alcohol as a fuel, as I understand it, that burns cooler than "regular" alcohol. Though carburetion of said fuel is something else I will have to figure out. I'd like to use this to at least get to the point of getting combustion, just to see if it all comes apart in spectacular fashion. If I can get this to hold, I'm certain I can make a block and head made of wood minus the defects that will hold up. The thought of using an outside source for the spark occurred to me, that would eliminate the issue of having a non-conductive source (the wood) to complete the circuit. Then it's just a matter of putting a contact in the right place. Initially, I could possibly spray alcohol into the crankcase with a paint gun through a reed valve, how scary does that sound? Outdoors you say? Good idea.
|
|