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Submersible Robot Diesel Recycles Its Exhaust
An Anonymous Coward writes: "This might be a good weekend topic to kick around. Trends in Japan has a short article on an undersea robot that uses a contained diesel. 'The engine itself is a completely closed system that needs no intake of air to run and chemically processes exhaust gas inside the robot. On-board devices reinfuse the exhaust with oxygen after removing its carbon dioxide and reuse the gas in the fuel mixture. The seawater is kept clean, as no gas is released.' Any /.'s working with this tech? Can it be applied to low emission vehicles?"
Turbo's dont usually take more fuel, the act like a powered blower and increase compression and air volume without needing a pull like a blower, so they should in theory be as efficient as a vehical without. Turbo's also out put as much garbage as any typical car. So they are very different from this system.... the Cat on cars removes some of the nasties..... so really the Robot has a super cat on it and not a Turbo.
I'm pretty sure that Subaru's WRC rally cars have an efficency-increasing trick that, although not as scientifically interesting as the concept peresented in the story, would improve a car's effeciency.
AFAIK, there is a heated plate in between the engine exhaust outlet and the turbo turbines. This plate heats up any uncombusted fuel in the exhaust (there's generally a fair amount of uncombusted fuel left over) and it ignites, thus giving more power to the turbines. Of course, in the rally cars, it is tuned towards power (it does wonders to decrease low-end lag, I guess).
I bet this would be a great thing to add to, say, a high-efficency economy turbocharged engine. Also, it doesn't seem that complicated to implement. Anybody ever try adding a similar mod to their car?
I'm sure that the substance used to scrub the CO2 back down to O2 is Lithium Hydroxide, just like in space vehicles. Lithium Hydroxide is a much more polluting substance than a little CO2. Using this idea in our atmosphere where O2 is freely available is not a viable idea.
TAANSTFL.
I work on all kinds of cars, whenever I can. I used to be a faculty advisor for a college car club at Purdue University, (http://fox.vet.purdue.edu/) and got down and dirty with all sorts of automobiles.
My current project vehicle and daily driver is a 1984 Chevy K10 Blazer with the 6.2L diesel. I'm planning on adding a turbo kit from Banks in a year or so, and get this truck over 40mpg on the highway.
Should be interesting...
Although this is offtopic, I thought I'd put in a couple of words.
It's true that superchargers are lesser used in production vehicles than turbochargers. This is for several reasons.
First, turbos use exhaust energy instead of the crankshaft to drive them. Turbos have a lot of useful features that make them better than superchargers for production vehicles. Firstly they are more efficient (this is assuming a properly sized unit that is tuned by the factory), they can compensate for altitude, and they can be controlled by an emissions computer.
Superchargers on the other hand are not computer controlled, do not compensate for altitude, and (in production vehicles) have a higher air temperature than turbos (most all production vehicles have intercoolers).
The type of supercharger used on production vechicles is usually a roots/twin screw positive displacement variety. These produce almost instantaneous boost, but are inefficient at high boost values. Cosequently they usually don't go higher than 8 psi max, 4 or 5 psi nominal. These installations use aftercoolers (water cooled radiators in the manifold) to cool the intake charge, on vehicles with enough intake volume (such as the Ford Lightning). The primary manufacturer of these superchargers is Eaton.
Turbochargers on the other hand are very widely used and generally produce more power than superchargers. The 1984 Mustang SVO and Thunderbird Turbo Coupe saw about 18psi max. That is an HPT (High Pressure Turbo) design. Volvo uses LPT (Low Pressure Turbo) turbos in several of their vehicles, the S80 T6 to be one. LPT turbos provide a small amount of improvement over NA power, however they can be tuned via computer to produce much more power. Turbos suffer from an efficiency problem that many are not aware of. Specifically they have anywhere from a 2:1 up to 6:1 pressure differential between the exhaust port and intake port of cylinders. This means that if you have 10 psi boost, you have 20 to 60 psi backpressure. This is a significant limitation of turbo designs and what limits their output. Maximum compressor RPM is the other limitation. Most compressors do not exceed 120,000 RPM. Smaller turbos turn faster to move the same amount of air that larger turbos move at lower RPM.
In conclusion, superchargers are generally installed on cars that were originally naturally aspirated, because it's a relatively easy conversion. However, turbos do not easily adapt to naturally aspirated cars because they don't integrate with the engine control system easily.
Here's a list of cars that come with superchargers (that I know off the top of my head):
Volkswagen Corrado G60
Ford Thunderbird SC
Pontiac Grand Prix GTP
Mercedes SLK Kompressor
Jaguar XK8
Ford Lightning (1999+)
Nissan Frontier (2001+)
Aston Martin Coupe (Jaguar)
However the list of turbo cars is probably 20 times the above.
As a side-note: the Dutch actually had invented the schnorkel I think already before the war. The Germans discovered and applied the invention later on. (I read Doenitz's memoirs so I consider it a good source)
Don't get me wrong, this sound's pretty cool, but the article makes false claims:
The Autonomous Benthic Explorer (ABE) built at the Deep Submergence Laboratory of the Woods Hole Oceanographic Institute originally used lead-acid batteries and now uses lithium cells.
I worked on a building a brain upgrade for ABE. The original system runs in FORTH and C on an agglomeration of hand-coded microcontrollers and Transputers. The new system (still under development) is a PC104 stack... running Linux.