[carve]

It looks like a fun project, but needlessly heavy and complicated for the small improvements.

What we're really trying to do is, after the nice high-quality heat has already been harnessed by the pistons, find a way to squeeze a little more energy out of the waste heat that is left over, particularly at part-power conditions. There are ALWAYS ways to squeeze out a bit more energy; the problem is the smaller the temperature difference available, the bigger the device squeezing the heat out of the fluid needs to be for a given amount of power.

This makes the challenge as follows: find a way to squeeze energy out of waste heat with minimal growth in weight and complexity. I see a few ways to do this that would be superior to the steam system.

1) Turbo alternator. Turbochargers work by squeezing waste heat out of exhaust. While cruising, we open the wastegate and they basically sit there not doing much of anything. Why not gear an alternator to the turbo and use it to charge a battery? Particularly on a hybrid system, this power could be fed to an electric motor. On a nonhybrid, perhaps there could just be a small motor-generator (like a robust starter motor mild-hybrid system) to add power to the crankshaft. When high power is demanded, the turbo alternator becomes a motor and quickly spins up the compressor on the turbocharger, dramatically reducing lag. Of course, this would require some way to decouple the compressor from the turbine. Perhaps pairing this with an electric supercharger would be best.

2) Control power by controling valve duration and going into a deep Atkinson cycle. Valvetronic already does this to a very small degree, but MUCH more needs to be done.

An Atkinson cycle engine has a short intake stroke and a long power stroke. This longer power stroke give a longer expansion ratio, and more energy is extracted from the hot gases inside. While the original Atkinson cycle engines used a complicated linkage to do this, you can achieve a similar affect on a normal engine through controlling the intake valves. Hybrids, like the Prius, run on an Atkinson cycle. They intake a full cylinder of air, but as the piston starts coming up for the compression stroke, it keeps the intake valve open for a bit, puking some of the air back out into the intake. The rest of the stroke operates normally. Of course, this lowers the effective displacement of the engine, so it sacrifices power if you run this way all the time. It would be even better if we could just shut the intake valve early because we wouldn't be pumping air back and forth across the intake valve.

If you could find a way to vary the valve duration across a very big range, you could control the power output of the engine this way. Part throttle crusing would become VERY efficient. When you needed full power, it would intake a full charge of air.

3) Ethanol and Super high compression ratios. Corn based biofuels are a farse, but ethanol has the benefit of being VERY high octane. A fuels highest octane rating is only needed for that brief time where lots of torque is demanded and cylinder pressures are very high. I propose, essentially, a factory meth system. This would allow you to run very high compression ratios, increasing efficiency and power, or you could also run very high boost levels. Ford is actually working on something like this.

All three of these ideas could be implemented at once with only small cost and weigh increases compared to any other turbo engine, and all accomplish the same goal of extracting more heat energy. The only new tech would be the valve lift control for Atkinson power control, and much of that could be adapted from existing tech like Valvetronic or Fiat Multiair.

[bimmerJP]

Originally Posted by tag824

lol, I think they have a lot of catching up to do with MB who has come out with way more innovative stuff than all car companies to date combined.

tell me you are joking..

[nyc4runnin]

just another expensive part waiting to fail ....

[bmwdinamo]

Originally Posted by tag824

lol, I think they have a lot of catching up to do with MB who has come out with way more innovative stuff than all car companies to date combined.

they have invented some safety tech as well as raised the bar for comfort. but bmw have always been true in delivering the ultimate driving machine for the future. mb can't beat bmw engines, nor the handling characteristics of their cars.

[bmwdinamo]

Originally Posted by nyc4runnin

just another expensive part waiting to fail ....

not really. seems very simple; like a "duh, why didn't we think of this earlier" type of thing.
in fact, i bet this could be easily retrofitted to vehicles on the road today

[Venom]

Originally Posted by BMWPower06

This is nothing new...I remember a professor of mine teaching us about this over a year ago in an engineering class. Still very cool nonetheless

Agreed, it seems like this came up a lot in engineering and/or physics classes. Not a new idea...

[Tag]

Originally Posted by jerrypon83

tell me you are joking..

They own the vast majority of all auto patents worldwide. Laugh all you want, that still doesn't change the facts. I'm not a MB fanboy or anything, just calling it as it is.

[bman8]

Originally Posted by IancoleTX

I think they should make an effort to simplify where possible.. Modern cars are incredibly complex as is, and the more systems you add, the more things will break and wear out.

Further, if the vehicle itself is designed as a disposable item with a shelf life of 10 years instead of 20 due to prohibitively expensive maintenance, what does that do for efficiency?

I think this innovation is excellent and commendable.. it just seems like things are getting so very complex.

+1

[FstopBMW]

So with the TEG and the twinpower turbo on the N20 we should be seeing some nice performance and efficiency!

[Glim]

If it increases efficiency by 10% the average savings is only $130 per year. I wonder what the ROI will be.

[b33g33]

Originally Posted by tag824

They own the vast majority of all auto patents worldwide. Laugh all you want, that still doesn't change the facts. I'm not a MB fanboy or anything, just calling it as it is.

+1

A lot of people these days can't seem to distinguish between brand/party/national loyalty and reality. Why let facts get in the way when you can thump your chest about something and feel good because you're part of a group?

There are some things BMW does extraordinarily well and there are some places where they need to do some serious catching-up. As fans and consumers of the brand it is our right and, maybe even responsibility, to stay objective and point out the areas of improvement for everybody's benefit.

We're all here because we're fans of BMW cars. This doesn't mean we should check our brains and our ability for independent thought at the door.

[Motovation]

Originally Posted by carve

It looks like a fun project, but needlessly heavy and complicated for the small improvements.

What we're really trying to do is, after the nice high-quality heat has already been harnessed by the pistons, find a way to squeeze a little more energy out of the waste heat that is left over, particularly at part-power conditions. There are ALWAYS ways to squeeze out a bit more energy; the problem is the smaller the temperature difference available, the bigger the device squeezing the heat out of the fluid needs to be for a given amount of power.

This makes the challenge as follows: find a way to squeeze energy out of waste heat with minimal growth in weight and complexity. I see a few ways to do this that would be superior to the steam system.

1) Turbo alternator. Turbochargers work by squeezing waste heat out of exhaust. While cruising, we open the wastegate and they basically sit there not doing much of anything. Why not gear an alternator to the turbo and use it to charge a battery? Particularly on a hybrid system, this power could be fed to an electric motor. On a nonhybrid, perhaps there could just be a small motor-generator (like a robust starter motor mild-hybrid system) to add power to the crankshaft. When high power is demanded, the turbo alternator becomes a motor and quickly spins up the compressor on the turbocharger, dramatically reducing lag. Of course, this would require some way to decouple the compressor from the turbine. Perhaps pairing this with an electric supercharger would be best.

2) Control power by controling valve duration and going into a deep Atkinson cycle. Valvetronic already does this to a very small degree, but MUCH more needs to be done.

An Atkinson cycle engine has a short intake stroke and a long power stroke. This longer power stroke give a longer expansion ratio, and more energy is extracted from the hot gases inside. While the original Atkinson cycle engines used a complicated linkage to do this, you can achieve a similar affect on a normal engine through controlling the intake valves. Hybrids, like the Prius, run on an Atkinson cycle. They intake a full cylinder of air, but as the piston starts coming up for the compression stroke, it keeps the intake valve open for a bit, puking some of the air back out into the intake. The rest of the stroke operates normally. Of course, this lowers the effective displacement of the engine, so it sacrifices power if you run this way all the time. It would be even better if we could just shut the intake valve early because we wouldn't be pumping air back and forth across the intake valve.

If you could find a way to vary the valve duration across a very big range, you could control the power output of the engine this way. Part throttle crusing would become VERY efficient. When you needed full power, it would intake a full charge of air.

3) Ethanol and Super high compression ratios. Corn based biofuels are a farse, but ethanol has the benefit of being VERY high octane. A fuels highest octane rating is only needed for that brief time where lots of torque is demanded and cylinder pressures are very high. I propose, essentially, a factory meth system. This would allow you to run very high compression ratios, increasing efficiency and power, or you could also run very high boost levels. Ford is actually working on something like this.

All three of these ideas could be implemented at once with only small cost and weigh increases compared to any other turbo engine, and all accomplish the same goal of extracting more heat energy. The only new tech would be the valve lift control for Atkinson power control, and much of that could be adapted from existing tech like Valvetronic or Fiat Multiair.

Your ideas are somewhat naive Carve, 1st you need to come up with some drive system from the turbocharger as well as maintaining the spool speed not to cause excessive turbo lag. Don’t forget that turbos run at well over 20,00 rpm.
2nd The Prius runs on a modified Atkinson cycle and requires the hybrid motors to maintain a sustainable low speed torque. BMW’s valvetronic and Vanos as well as Audis AVS and variable valve timing has been doing this in a smaller degree for a few years now.
Thirdly Ethanol or any Alcohol based fuel runs extremely hot and actually requires a much richer fuel mixture to cool the combustion chambers down. Only if they could manage this extra heat to run the turbo steamer and therefor control the combustion temps and therefore higher NOX levels which is the highest contributor of harmful exhaust emissions.

[carve]

Originally Posted by Motovation

Your ideas are somewhat naive Carve, 1st you need to come up with some drive system from the turbocharger as well as maintaining the spool speed not to cause excessive turbo lag. Don’t forget that turbos run at well over 20,00 rpm.

Gearing may be a challenge. You could put the magnets right on the shaft. Many small electric motors, such as in RC cars, can spin over 80,000 rpm, so the magnets and windings can be built to handle it. As I already said in my original post, the alternator could be used as a motor to eliminate lag. You could even get rid of the compressor and run a supercharger or electric supercharger...or no forced induction at all. Extracting motive force from the turbine was my main point, and that accomplishes the same thing the steam generator does in a much more compact, simple package.

Turbo-alternator prototypes have already been built.

2nd The Prius runs on a modified Atkinson cycle and requires the hybrid motors to maintain a sustainable low speed torque. BMW’s valvetronic and Vanos as well as Audis AVS and variable valve timing has been doing this in a smaller degree for a few years now.

I already mentioned this. Remember- it wouldn't run atkinson all the time- just at part load, when full power isn't required.

Thirdly Ethanol or any Alcohol based fuel runs extremely hot and actually requires a much richer fuel mixture to cool the combustion chambers down. Only if they could manage this extra heat to run the turbo steamer and therefor control the combustion temps and therefore higher NOX levels which is the highest contributor of harmful exhaust emissions.

GM produced a car that did just this in the 60's. There's an article in car and driver that just came a couple days ago proposing this very idea. Ford is building prototypes of it. It is the same idea as meth systems many already add to their cars. Alcohol provides much more cooling than gasoline since it absorbs more heat on evaporation, and because you spray more of it into the cylinder for a given power requirement.

Naive, eh?