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Steam Hybrid Car from BMW
RMX writes "BMW is unveiling its turbosteamer hybrid engine, which uses the excess heat in the exhaust system and reclaims 80% of it by powering a steam engine that assists the gas engine. Overall, this gives a 15% more efficient engine; and significant additional performance (power and torque) with practically no downside. "This project resolves the apparent contradiction between consumption and emission reductions on one hand, and performance and agility on the other," commented Professor Burkhard Göschel. Are steam engines the future of environmental-friendly hybrid vehicles?"
BMW has the ability to make Hydrogen-powered production cars, it is a shame that they have not caught on yet.
Current fuels will eventually go the way of the steam engine, or wait, maybe not the steam.
Interesting site: http://www.bmwworld.com/hydrogen/
He who knows best knows how little he knows. - Thomas Jefferson
German online news site Spiegel Online has more details on this:
Heat plant in the car. It uses a high temperature (up to 550 Celsius) circuit using water and a low temperature one using ethanol (alcohol) (operating at 150 Celsius). Both are closed systems.
The pictures accompanying the article suggest the system interfaces with the relatively large radiator already in the front of the car. It is not going to produce nearly as much steam as an engine that would power the entire car, and this steam engine doesn't need a heat source either.
Don't forget that most turbocharged engines will give up some fuel efficiency as compared to a naturally aspirated engine of the same displacement even when operating under light loads. This is because in order to handle (without blowing head gaskets or detonation) the increased charge density provided by forced induction, they must use a lower static compression ratio. Lower compression ratio generally equals less efficient combustion.
This is why Saab developed this.
"Prefiero morir de pie que vivir siempre arrodillado!"
" I think you are confusing fuel and engine form. Diesel is just a fuel, it doesn't dictate the engine type."
Oh yes it does! Just try putting diesel fuel into your Otto Cycle automobile!
The Diesel Cycle is inherently different from the Otto Cycle in that there are no sparkplugs. As opposed to an external ignition source, diesel engines use nothing but the compression in the cylinder to ignite the air-fuel mixture. Overgenerallizing a little, diesel engines operate entirely on what you would call "knock."
I could go on about temperature vs. entropy comparisons between the Diesel and Otto cycles, but your eyes would glaze over.
For the same compression ratio, the Otto Cycle is more efficient than the Diesel Cycle. However, when engineering comes into play, you can have much, much greater compression ratios with a Diesel engine than an Otto engine. The source of ignition in a Diesel Engine is the pressure in the cylinder, and the pressure is uniform throughout the chamber, ensuring uniform combustion and uniform expansion of the cylinder. You can get away with building cylinders, say, 1 m in diameter. With the Otto Cycle, because you need an ignition source (sparkplugs), combustion in the chamber will be non-uniform and there will be more energy lost because of it, so F-1 and GPX cars use many, many cylinders that are very long but very slender. Only a fool would use an Otto Cycle engine to power a locomotive, let alone a ship.
"So... there's no reason you couldn't make a highly efficient diesel external combustion (probably steam) engine."
No. Diesel means internal combustion. If you want external combustion, you build a steam turbine (far fewer moving parts), and they don't care what you burn. There's no reason to burn something as expensive as refined diesel fuel. Modern steamships burn whatever it is the refineries can't sell to anybody else.
You could try a gas turbine, but, again, diesel fuel isn't designed for that; it will ignite when you don't want it to, and not ignite when you need it to. Go with kerosene.
"So... there's no reason you couldn't make a highly efficient diesel external combustion (probably steam) engine."
Not a mechanical engineer, are we?
"If the water runs out,"
Then you take it back to the dealer. The water isn't supposed to come out, you put your superheated steam through the preheater, getting it back down to saturation before you put it back into the boiler again. You should no less run out of water than you would run out of motor oil or transmission fluid (with similar Very Bad Things happening to your engine if you do).
" I think you are confusing fuel and engine form. Diesel is just a fuel, it doesn't dictate the engine type."
;-)."
Umm no a Diesel engine it a specific type of engine the correct name is a Diesel cycle engine. It was invented by a man named Rudolf Diesel and uses extermly high compression to ignite an air fuel mixture. The typical car engine is also called an Otto cycle engine after it's inventor.
While by definition any fuel you put into a Diesel engine is Diesel fuel Diesel engines can burn a many differn't types of fuel. Everything from heating oil to jet fuel will work in a diesel cycle engine.
"The biggest problem with internal combustion is that the heat of the reaction can't be avoided and is absolutely not wanted, so you have to carry around cooling systems. For external combustion the heat is exactly what you want, and it's pretty easy to obtain
Again no. The heat is what makes an internal engine work. It is a good thing. You only have to cool an engine because of the limits of the material. The hotter a Diesel gets the better it will work up to the point the lubrication or the material fails. BTW External combustion systems have EXACTLY the same limitations on max temp. A steam turbine is limited by how much heat the material and lubrication system can take before failure. You will still have to a cooling system for a steam engine and limit the temperature of the turbine.
An Otto cycle engine has issues with detonation so there is also a chemical limitation on max temp.
" The downside is you have to carry around some other material (for the state change) which is typically voided rather than cooled and re-used."
Not all external combustion engines use a state change. The Stirling cycle engine for example.
Some of the most efficient prime movers on Earth are massive Diesel cycle engines used in shipping and at power plants.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
> The only thing hydrogen is good for is to reduce emissions from the
> vehicles themselves, but you only end up pushing the pollution to
> power generating stations, which we'll need a lot more of if the
> 'hydrogen economy' takes off.
Except that you're missing a critical piece here: since hydrogen extraction facilities are very large and stationary (something most cars are not), they can use fuels that would simply not be an option for the cars themselves, such as wind, solar, wave or nuclear power. And even if you do keep producing hydrogen by burning fossil fuels, because of the size and relatively low number of production facilities you have the economic luxury of investing in technologies that burn fossil fuels more efficiently and transform waste into more benign forms than would be feasible in the cars themselves.
This idea isnt new, doing it in a potentially production car is.
35+ years go we did a paper exercise in a thermodynamics class to evaluate the potential efficincy of a Rankine cycle (steam) engine running off waste heat from an internal combustion engine. IIRC, we got efficency numbers about like what BMW is claiming.
One weakness is that the systems aren't very efficent at low power, such as stop and go traffic or slow driving. There just isn't enough waste heat in the cooling system to do anything useful until you start making a reasonable amount of horsepower.
Some ships and stationary power plant use steam engines (usually steam turbines) that run off waste heat from gas turbine engines to boost efficency. Celebrity's Millenium Class cruise ships are one example.
For Hondas... this is inaccurate. There are two variations of Hybrid technology that are generally on the road (I'm sure there are others... but these are the two most popular). There is Gasoline-Electric (Integrated Motor Assist - IMA) and Electric-Gasoline (Hybrid Synergy Drive). Toyota's implementation (which has been licensed by just about everybody EXCEPT Honda) starts with electric and uses the gasoline engine only when additional power is needed for acceleration or higher speeds (highway). Honda, on the other hand, uses a 4-cylinder engine to power the car... and when you need extra acceleration... kicks in the electric motor (which also acts as a starter) that is powered by the batteries.
However, depending upon how the steam system was established, it could work as an additional powering tool for the vehicle. Especially if there was a mechanism for storage and gradual building of heat in the system. Maybe... instead of using the steam to actually drive the vehicle... use it as another means to build electrical energy into the batteries.
Reclaiming heat and inertia to help power elements of a vehicle are old concepts. The true key on all of these technologies (in their application towards an automobile) is advances in alloys. Back in the day... all you had was iron and steel (that was affordable and strong enough). With those materials... your weight was insane and not worth the trouble of adding additional drive mechanisms to the vehicle (as the extra weight negated the extra power you were going to get). With engines going to aluminum alloys and advances in frame structure techniques lowering curb weights, we can afford to put more of the total weight back into drive mechanisms.
Personally, I have a 2004 Honda Civic Hybrid. I love it. It was more expensive than the Toyota Prius (but not by much) but was well worth it. While the instrumentation evokes "spaceship"... looking at the car from the outside doesn't. That is why my wife and I didn't like the Prius. It looks like something out of a Carl Sagan inspired picture of tomorrow. While that's nice for some... I don't like it. I still get enough "ooglers" who ask me about my gas mileage to keep me happy. My gas mileage hangs out around 55 MPG during the summer and dips down to 42-45 during the winter due to the effect of cold on the system... it protects the battery by only allowing it to be used a little until the cabin heats up. This hurts my MPG performance during the winter alot (55 down to 42/45) because I pull-out onto the main road which is a very steep up-hill. Since the gasoline engine is doing most of the work on the cold mornings... it eats more gas than usual.
I think there's still some promise left in gasoline... but I think we definitely need to push for alternative methods for doing the primary drive of the vehicle under stress. Hydrogen would be a good one if we could create it effectively (pbbbt! to those that complain about distribution... the gasoline infrastructure could be converted).
In the words of Daft Punk: Harder, Better, Faster, Stronger.
Andrew 'Mickey Knox' Gearhart
You can't take heat from the catalytic converter because that heat is required to catalyze the gasses. That's why emissions suck for the first 5 or so minutes that you run your car - the catalyst is cold and not doing its job. That's also why urban areas use MTBE and other oxygenates in fuel in the winter time - so that the mal effects of the cold catalyst are mitigted.
The used cars don't get crushed as soon as the first owner is done with them, they go onto the used market and hopefully allow less enviro-trendy people, who just want a new car, to replace the old gas-guzzler they'd been driving.
You're assuming the new owner doesn't have to drop a few k on new batteries. If a used car is going to take many thousands to make right, how well will it do in the used market?
From that standpoint this new "Snobby Steamer" is better as there are not lots of nasty batteries that eventually wear out.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
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I can't imagine a reason why a turbocharger couldn't be used at the same time as an exhaust-heat-powered steam engine. The steam engine uses the heat from the exhaust to drive the car (efficiency + performance gain), while the turbocharger uses kinetic energy from the exhaust to shove more fuel/air into the combustion engine (performance gain only).
because the heat is kinetic energy. if you transfer the heat to a steam system, you're slowing down the exhaust molecules. if you take the kinetic energy to run a turbine in a turbocharger, you're cooling down the molecules. you only have so much energy to work with. one set of numbers i do know: turbodiesel pickup truck towing a 12,000lb trailer up a hill. exhaust temperature before the turbo: 1200F. exhaust temperature after the turbo: 900F. the energy turning the turbine cooled the exhaust by about 400F.
one thing that i don't think has been mentioned yet, is that cool gasses resist flow more than hot ones. the cooler exhaust gasses will create more backpressure (==work for the engine) in the exhaust, just like adding a turbo - so that's one downside. over all, i think the turbosteamer is kinda neat though.