Okay, I need some more brains on a thought.

Would it be possible to leverage waste heat from an internal combustion engine to drive boost? Either alone or as a composite setup with a supercharger or turbo?

Which I guess comes down to whether one can think of a design that harvests excess heat from the engine, either through conduction of the hot side of the coolant, a direct transmission from the crankcase (heat pipes?) or from the exhaust casings (cat maybe?) ... and then drive (or help drive) an impeller for manifold pressure.

Anyone ever heard of this being done? Seems like everyone shoots for the moon with replacing the internal combustion engine in a vehicle, but what if you could increase manifold pressure without a) pulleys off the engine or obstructing exhaust flow?

I once thought of this. Almost like driving a small steam turbine using the engine heat. Here's some of the ideas and problems I came across.

Engine heats to around waters boiling point, water doesnt boil due to it's pressure inside the engine. So use a liquid that boils at a lower temp (say 140`F) and use that. Well if you have a sealed system (something that will boil, use it's pressure, then condense it to be reused), you tend to have equal pressure though out the system, so that wont work. You'd have to purge the "exhaust steam" (portion directly after turbine) into the atmosphere. And this could work. How-ever you'd be stopping every few miles to re-fill up on this special fluid.

So If you could build a way to have a the hot high pressure side, and a cold low pressure side that could recirculate, then it could be possible, and work quite well. You might not get enough energy to run any kind of manifold pump (turbo/supercharger) but you might be enough to run things like power steering pump, A/C, maybe recharge a hybrid system (Gas/Elect).

Any system can be scavenged for leftover energy and redirected, but the amount of power you are talking about with a sterling engine is fairly improbable. You would most likely be looking for a gas/liquid combo that has a low flash and evap point. You would probably stand a more effcient chance if you used a reverse peltier system along the exhaust.

At this point in the life of the ICE, the most proabable suspect is the gas/fuel system itself.

Try looking up references for Pogue Carb and the GEET engine. Both of these were solid attempts to recycle and process excess energy.

Mind the conspiracy theory and shower before you post back to us..
(Once it gets on you, it's hard to get off.)
SJ

I wonder, though, if you could siphon the heat effectively, and you could balance coolant flow so as not to counteract your need for a high differential, since the stirling would be acting as a heat pump pulling heat from the engine, if the differential would be so big that it yielded significant power? Might even use a quasi.



Or maybe just an enclosed phase change system, where the vapor stage drives a turbine prior to being sent back to the cool-down stage, ie radiator.

I will review those links tonight, sj.

Okay, this guy is a pretty wacky writer, but a darn interesting stream of consciousness.

Physics in an Automotive

Oh, and guess I am late to the party. Steam generation to power engine accessories.

Yes. You will find some seemingly crazy ideas in certain places. I will give you an "interesting" example. I was doing research on plasma and high temperature engine modifications when I came across a reference to a section of the Geet engine which the users said HAD to be aligned with true north during the first 30 minutes of it's operation. I thought "Voodoo Magik Mahn!" They said that the alignment was critical to the operation of the engine. I kinda chuckled because the object in question was a spindle rod of steel that was heated by the flow of exhaust gas. But about two weeks later I came across a reference from an MIT experiment showing the changing properties of plasma as it was subjected to A MAGNETIC FIELD. Oddly enough it's properties changed quite a bit. Thats when I remembered that there are three ways to make a magnetic alignment, one of them being heating while aligned in a magnetic field.
So in the end, he really DID have a reason to have this funky alignment. Sounded odd when I read it, but if you are willing to crawl around in anarea that is about 90% crackpot ideas and 10% genius, then there are rewards waiting for you.

A lot of the heat in a gasoline engine does go to waste heat.

A few points: While the block and head are limited to (about) the boiling point of water by the cooling system, I can tell you that the exhaust manifold will get signifigantly hotter. (If you're feeling up to it, pour a little bit of water on the exhaust after driving around. Doesn't even have to be driving hard.) There's more than enough heat to boil water in that system.

Second: You CAN have a circulating system, particularly with steam. Water itself will equalise pressure, since it doesn't compress, but steam does compress, so you can have a pressure inequalibrium.

However, the efficiency gained in this way is unlikely to be all that great, and really, if what you're doing is driving an impeller in order to force more air into the engine, what you're doing is making more power by burning more gas, and the existing turbo/supercharger technology out there is more than adequate to the task.

If you want to increase power for LESS fuel, no type of forced aspiration is going to do that. Turbochargers and Superchargers do SORT OF do that already, because when driven off-boost, they perform like a relatively small displacement engine. My engine is 3L displacement, which can get pretty decent mileage, but under 1.2 bar of boost, it acts more like a 7.5L high compression engine, and makes tons of power, giving me the ability to have that kind of power OR the economy of a smaller engine, but there's no way that I can do better than the base 3L engine for economy.

There is (and has been mentioned in here already) a Six stroke engine idea, which uses the normal 4 strokes for gasoline, but at the top of the normal exhaust stroke, you inject liquid water. This boils on contact with the piston, and gives you an additional power stroke, which is then exhausted before the next regilar air/fuel intake stroke. This recycles the waste heat, reducing the load on the cooling system, increases power (Now getting 2 power strokes for every 3 crank revolutions, instead of 1 power stroke for 2 crankshaft revolutions) and increases fuel economy since it uses zero air/fuel for the additional power stroke. In addition, even if you run out of water, the engine will continue to run. This would be much more effective, in that it increases both power and fuel economy. The downside is that it requires extensive modification to the engine. The camshafts need to be redesigned to rotate once every three crank revolutions, instead of every 2, as well as redesigned to give 2 exhaust strokes per revolution, so it's a more complex shape. This will probably also be more limiting to the amount of lift that the cam can give. (Or else you need to have completely electronic valve timing, in which case, it's a pure electronics mod, and it can still run as a regular 4 stroke if need be.) The ignition system also needs to be modified similarly, but again, this can be done purely electronically. I'd figure that you'd run it as a 4 stroke engine until it gets warmed up, then start the water injection when the engine reaches operating temperatures.

In any case, this is probably NOT something that can be adapted to existing engines.

Existing engines COULD probably be adapted (though with difficulty) to intermittant water injection, particularly direct port injected diesel engines. You'd need a separate water injector in the cylinder head. A logic device (flip-flop/counter) can take the ECU signal and instead of injecting fuel at the top of the compression stroke, inject water instead, say one out of every 3 cycles. Instead of the fuel igniting under compression, the water would boil instead, and generate power the same as the diesel fuel would (though possibly generate less power.)

Hmmm... Now that's an idea. Let's see... Issues... You're still taking in air, so this could cause an issue with an O2 sensor monitoring the exhaust gasses. There would be excess O2 in the exhaust gas stream. This could also cause some premature corrosion in the exhaust system, since we'll be expelling hot O2 into it. The air will, however help the water make more power, but the high pressure in the combustion chamber would also raise the boiling point... I don't think that would be a problem.

The same thing couldn't work with gasoline engines, since the water would boil during the intake stroke, and cause a lot of problems. You'd have to not only change the signal to fire a differnet injector, you'd also need to change the timing, so that it fires later.... Hmmm... Perhaps we do two things, one, interrupt the fuel injector for that revolution, and two, fire a diesel style injecotr directly into the cylinder instead of the spark plug. That's still a little early, being before TDC, but it might work out okay and still avoid problems, since the engine is already designed to deal with the pressure building up. Here we DEFINITELY get issues with the O2 sensor, but maybe that can be programmed around...