BMW Turns to Steam to Boost Power, Improve Fuel Economy
By FELIX BAUER | AUTOMOTIVE NEWS
AutoWeek | Published 02/13/06, 1:17 pm et
MUNICH, Germany -- BMW is applying steam-engine technology in an auxiliary drive that the automaker says can boost both power and fuel efficiency in ordinary piston-driven cars.
The automaker is testing a two-stage device called the Turbosteamer on a stationary conventional 1.8-liter engine at BMW headquarters here.
The device works entirely on the waste heat from the engine.
Turbosteamer converts more than 80 percent of the heat energy in the exhaust into usable power, says Raymond Freymann, head of BMW's advanced research and development subsidiary.
BMW could start building production vehicles with the system by the first half of the next decade, Burkhard Goeschel, BMW board member for r&d, said during a briefing.
The system can be used on any combustion engine.
In trials on a test rig, the system when attached to a regular BMW four-cylinder, 1.8-liter Valvetronic engine reduced fuel consumption by 15 percent. It also generated an extra 13 hp and 14.8 pounds-feet of torque.
The concept is hardly new. The first patent for a steam auxiliary drive harnessing exhaust heat was issued in 1914 to Wilhelm Schmidt of Germany.
The sheer size of a heat-recovery system had been the biggest problem. But the Turbosteamer fits in a regular 3-series body.
"All we lose is a bit of ground clearance," says Freymann.
BMW knows that a production version of the Turbosteamer system must provide enough benefit to justify the higher price tag.
Says Freymann: "The clients have to save more fuel than the system's extra cost."
How the system works
BMW's system uses two fluid-circulating systems to recover exhaust heat from the gasoline engine. The primary high- temperature circuit pumps water through a heat exchanger, surrounding the exhaust gases immediately behind the catalytic converter. Water is heated to 1,022 degrees Fahrenheit.
Steam is converted into mechanical energy in an expander and transferred by pulleys to the engine crankshaft.
The steam flows through another heat exchanger and transfers its remaining heat to a second circuit filled with ethanol. This lower temperature system replaces the engine's regular coolant system.
This system also collects heat in a heat exchanger in the exhaust-gas flow. It releases its energy in a second expander unit that transfers the energy to the crankshaft.
Unlike the electric hybrids now in use which work best in city driving and have minimal benefits on the highway, this one's the opposite. Of course, there's the slight problem of a boiler explosion in case of a car accident.
aerius: I'll vote for you if you sleep with me. Lusankya: Deal!
Say, do you want it to be a threesome with your wife? Or a foursome with your wife and sister-in-law? I'm up for either.
Natorgator wrote:IIRC, this sounds very similar to the 6-stroke engine that I posted about a couple weeks ago.
The 6-stroke sprayed water directly into the cylinders, which is an inherently very lossy system. This system captures waste heat from the exhaust, in a closed loop boiler system. You should only have to refill the tank during regular maintenance.
"preemptive killing of cops might not be such a bad idea from a personal saftey[sic] standpoint..." --Keevan Colton
"There's a word for bias you can't see: Yours." -- William Saletan
Man, attach that to a diesel and you'll have some wicked fuel economy.
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Natorgator wrote:IIRC, this sounds very similar to the 6-stroke engine that I posted about a couple weeks ago.
This system is about as close to that engine as it is to the nuclear reactor powered steam turbines on an SSN. Anyway, steam engines have never been known for long term reliability and I think that plus the weight will kill this idea for anything but perhaps use on commercial trucks.
aerius wrote:
Unlike the electric hybrids now in use which work best in city driving and have minimal benefits on the highway, this one's the opposite. Of course, there's the slight problem of a boiler explosion in case of a car accident.
Yeah, safety is going to be a real bitch. A boiler explosion isn’t too likely with a properly designed system, but a simple leak from an accident or rust/corrosion/vibration would be extremely dangerous. High temperature steam basically melts flesh and fat together on contact, its basically like a flamethrower without the charring effect. I’d expect there wont be all that much steam in the system at any one time though, and BMW is smart enough to think of this shit.
"This cult of special forces is as sensible as to form a Royal Corps of Tree Climbers and say that no soldier who does not wear its green hat with a bunch of oak leaves stuck in it should be expected to climb a tree"
— Field Marshal William Slim 1956
Sea Skimmer wrote:Yeah, safety is going to be a real bitch. A boiler explosion isn’t too likely with a properly designed system, but a simple leak from an accident or rust/corrosion/vibration would be extremely dangerous. High temperature steam basically melts flesh and fat together on contact, its basically like a flamethrower without the charring effect. I’d expect there wont be all that much steam in the system at any one time though, and BMW is smart enough to think of this shit.
That too. I think rust & vibration is going to be the big killer up here in Canada with all the salt they dump on the roads every winter. It's pretty common for fuel lines, brake lines, and exhaust pipes to rust through after 5-10 years on the road. Some of our roads are also in bad shape so that's not going to help either.
It's a promising system though if they can get all the safety issues and other stuff worked out.
aerius: I'll vote for you if you sleep with me. Lusankya: Deal!
Say, do you want it to be a threesome with your wife? Or a foursome with your wife and sister-in-law? I'm up for either.
Not explosion. . .rupture. The ancient fire-tube boilers ala the steam locomotive were indeed prone to explosion. Basically, that was a big pressure vessel with tubes running through them to carry the hot gases to heat the water to generate steam. Very dangerous. And very obsolete.
Modern boilers all work on the water-tube design (where the hot gases flow around the tubes that carry the water). Much less catastrophic when a tube fails. Not saying that it's absolutely safe, but it's inherently less dangerous than all this talk of explosions make it out to be.
Time makes more converts than reason. -- Thomas Paine, Common Sense, 1776
Turbosteamer converts more than 80 percent of the heat energy in the exhaust into usable power, says Raymond Freymann, head of BMW's advanced research and development subsidiary.
That sounds like a bullshit number to me. 80% of waste heat -> usable power? Unlikely. There's way too much work being done for more than 50% efficiency in waste heat-> power.
