Crazy idea: Steam hybrid?

[Wyldesoul]

I was thinking about something. With most internal combustion engines, they're only about 20% efficient, and a lot is lost in heat. Everyone knows that the exhaust pipes get hot, real hot.

What if someone were to create a hybrid that harnesses steam power? Use that wasted exhaust heat to power some of the car's accessories, and free up that much energy to hit the wheels.

Wrap some tubing around the exhaust manifold to create the steam, and have that steam power the alternator or ps pump? Or something along that lines.

The main thought is that about 40% of gasoline's energy is lost as heat (in the exhaust system. Radiator heat is about 30%) If you could just reclaim 10% of that, you'd have a 50% increase in FE, theoretically.

Any thoughts as to the (im)possibility of this?

[Spencyg]

Hey...I read Popular Science too!

The latest issue is all about inventions, and there is a guy in there with a "6 stroke" engine. The standard 4 cycles still apply (Intake , Compression, Power, Exhaust), but after the exhaust cycle, his engine injects a mist of water directly into the cylinder when the piston is close to TDC. The steam hits the hot metal and expands 1600 times, forcing the piston down for 1 more power stroke. Bloody Brilliant!

Spence

[BainDreanor]

Look up a six stroke engine. It pumps water directly into the cylinder to generate steam to drive the piston an extra power stroke. It cools so well it also eliminates the need for a radiator.

[Silveredwings]

Good idea...

Hey...I read Popular Science too!

http://www.popsci.com/popsci/automot...cbccdrcrd.html

and...
http://www.gizmag.com/go/4936/
(just google bmw steam)

[psyshack]

The six stroke is nice. So is a pure steam engine.

The biggest issue with 6 stroke as with any steam engine is cylinder wash down. Steam turbines escape some of the issues that piston driven engines have. But require high psi steam and great quantity's of steam to drive them effective.

A steam hybrid comes up from time to time. BMW has done some work on this issue. Even BMW's system has issues to over come. Steam is simple in principle. But very had to work with and stay safe with. I work with steam on a daily basics.

You have control systems, safety systems, thermal shock issues, water quality and condensate to deal with.

When you see the water dripping out of a cars exhaust pipe. You are seeing a very acidic water. Its just like what we call condensing flue gas. When flue gas condense they rain back down on the boilers flue martial or sometimes back down on the boiler tubes themselves. Always causing massive damage.

The idea of using a coil around a cat is great. It would deal better with thermal shock and put up with the vibration inherent in cars. But what psi are we going to run the system at? If we want what we would like to think as safe psi levels. Then 15 to 30 psi isn't going help us much. We would need a huge volume of steam and to get that would require massive pipe and lots of water.

Old steam locomotives required anywhere from 125 psi to 250 psi to handle there jobs. And they got HUGE! Some of this requirement was needed to make up for the inherent slop in the piston driven engines. Back to the cylinder wash down and lube issues.

I would think to make a steam hybrid even close to practical one would need to get in the 600 psi range. You could then keep the system small and compact. But then you have to look at fittings and all the hardware needed for a 600 psi system in a micro use with all the vibration and thermal issues. The two hardest things on a steam system of any type is start up and shut down. And you cant have any leaks in a small micro system at all.

I'm not saying it cant be done. But the fact remains steam as a energy medium has been pushed pretty darn far already. Not to say there isn't room for improvement or better tech concerning. I would bet its a real fricking long shot.

psy

[Sludgy]

A steam cycle needs a condenser to avoid needing to fill up with distilled water every 20 miles and to avoid ~100 gallons (834 pounds) of distilled water in the trunk. Condensers themselves are heavy, add drag, use power and thus represent a weak link in any automotive steam cycle.

[richochet]

Fascinating thread, but bitty. In Veteran and Vintage car times steam cars were in there with reliability and some speed records. Names Serpollet, Stanley, White and Locomobile come to mind. There seem to be quite a lot of Stanleys still running; whether this is because there were more of them produced or that their boilers were indestructable - enthusiasts who keep them running would know more about this - I don't know. Their engines are said to be capable of producing 100 bhp, outstanding by Vintage standards, for a limited period. Was the limitation imposed by lubrication issues or steam supply? It could have been the latter because their boilers seem to have been rated at 10, 20 or 30 hp. Stanleys used exhaust steam to pre-heat boiler feed water then the exhaust steam went to a radiator/condenser which looked about the same as any other Vintage car radiator - of similar power - so not a huge "weak link".

A hybrid's I. C. engine could be smaller. The "cylinder cut-out" people have shown us that working the smaller engine harder is more efficient. They have just fallen over on using "auto" systems which cannot look at changing road conditions ahead. Perhaps their engine cooling water, if kept clean, could be boiler feed (overflow to radiator). Then after a moderate boiler heated by exhaust gases, and a superheater - but no mad pressures, its the heat that matters in heat engines, perhaps a turbine, a bit like exhaust steam turbines of the 1950's, to be sure, but just perhaps getting up towards an additional 50% power? Power when its needed. I have not done all the sums - next go!

[Wyldesoul]

I just figured out something... A way to make the 6 stroke more practical.

The nice thing about the six stroke is that it doubles the power and efficiency, and removes the need for a radiator. However, you need as much water as gas, and that is sent out the exhaust pipe into the air, so you need a secondary water tank as well as the gas tank, and both need to be filled just as often, thus negating the ease.

However... Modern exhaust systems are incredibly well sealed, so....

What if you were to have a secondary exhaust system. Have 2 exhaust valves (common in engines), but instead of both leading out the tailpipe, have one lead to a condenser. A 6 stroke would need a completely different cam profile, so it could easily be set that the 2 valves open in different exhaust strokes.
The steam could be piped to the front of the car to a condenser that would be taking the place of the radiator. So you would only need a couple gallons of water in a reservoir rather than as many gallons of water as fuel.
The water would cycle from the reservoir, through a direct injection into the cylinder, through secondary pipes to the condenser, then back to the reservoir.

[richochet]

The Prius petrol/gas-electric hybrid stores energy in its rather large, heavy and expensive battery and using this starts off and gets up to 26 mph - 40 kph, I think it is, presumably with satisfactory acceleration. Then the I. C. engine starts up, takes the bigger portion of the load (the clever epicyclic gearbox doing the load splitting) and starts replenishing the battery, which probably needs it by now especially if the acceleration has been noticeable or uphill.

But neither the 6 stroke nor the pipe coiled around the exhaust pipe or manifold - that's a form of flash steam generator - stores energy in either steam or hot water. Even a gas guzzler, loaded to say 2000 kg, with 2.5 m^2 frontal area and Cd about 0.35 will need less than 5 hp (DIN not SAE, and if my sums are right) to cruise at 80 kph - 50 mph. That's about 212 B.T U per minute, which means more than 250 B. t. u./min. in the exhaust and 190 in the radiator, so there is not much steam raising available there, probably less than 2 horsepower's worth. Sure, this is a 40% saving, but if the steam plant is scaled so that it is efficient enough to get 80 hp out of the waste heat of a 200 hp gas guzzler it's not likely to do more than keep itself warm with the waste heat from the same engine developing only 5 hp.

If the 6 stroker is to be adequately cooled by the water injected on the 5th stroke, and not just flooded either, the water injection needs control. Maybe Biffmeistro shouldn't have a condenser instead of a radiator, but a radiator that can be a condenser. Also, if the steam plant is arranged to provide 40% of the total then the I. C. engine only needs to provide over 140 hp for the same total. It is still not likely to help a lot cruising at 50 mph.

That is where a separate steam engine can be useful. If the I. C. engine exhaust heats water/steam in a water tube boiler that can store a bit of energy with the engine cooling perhaps heating the boiler feed water, then there is a much more flexible system. Storage of energy in hot water under pressure is comparatively efficient, but it still needs turning into steam for use. To keep the weight down, it could be best to extract exhaust heat energy only up 90 -100 hp, letting the rest go, if that rest is not used very often! That system could remain efficient at lower powers with stored energy filling in below that.

[ShadowWorks]

Originally Posted by Biffmeistro

Any thoughts as to the (im)possibility of this?

I started a thread on this very same topic, it turns out its already been done and patented, If i get some money and time together I will make a steam boiler of my manifold, the benefits of steam injections are amazing.