Recycle Heat From Engine

[N0WVA]

What if most of the heat from your car engine could be converted into rotary motion and somehow applied to the rest of the drive train. How much more efficient would that make the internal combustion engine?

[KA9VQF]

I read an article years ago about how some German engineers were experimenting with magnets mounted on the wheels of a car. The idea was that an electric motor would propel the car and the moving magnets would recharge the batteries.

It didn’t work out because in order to have a strong enough magnetic field to generate a useable amount of electrical power there was too much resistance to moving the vehicle.

It was in effect, more of an electric breaking system.

[wd0ct]

Quote[/b] (N0WVA @ July 08 2006,15:50)]What if most of the heat from your car engine could be converted into rotary motion and somehow applied to the rest of the drive train. How much more efficient would that make the internal combustion engine?
a turbocharger linked to the drivetrain would do this. i'm sure it has been done.

search adiabatic engines

[ka5s]

Quote[/b] (N0WVA @ July 08 2006,18:50)]How much more efficient would that make the internal combustion engine?
As much of the heat from your car engine is already converted as is practical under the contraints of vehicle design. It's not the most efficient engine, but the result of design, economic and even political compromises. See this article about heat engines. (http://www.sesusa.org/StirlingPrimer.htm)

Cortland
KA5S

[kd8dpl]

Quote[/b] (wd0ct @ July 08 2006,16:46)]Quote[/b] (N0WVA @ July 08 2006,15:50)]What if most of the heat from your car engine could be converted into rotary motion and somehow applied to the rest of the drive train. How much more efficient would that make the internal combustion engine?
a turbocharger linked to the drivetrain would do this. i'm sure it has been done.

search adiabatic engines
While a turbocharger will increase the adiabatic effeciency of an engine, it's nowhere near the roughly 70% gain you'd see if you could do what was asked in the first post. Off the top of my head, roughly 30% of an engines thermal energy is lost through the cooling system and roughly 50% is lost through the exhaust system. Yes, I'm aware that 50% and 30% do not add up to 70%, which is why I added "roughly". I believe the total "waste" is about 70% and the other 30%/50% numbers will be a bit more or less, totalling roughly 70%. Did that make sense?

[KA9VQF]

Turbochargers are nice enough things but really not as efficient in increasing usable horsepower as a supercharger.

[kd8dpl]

I'm not so sure that I completely agree with that. Turbos have been very effectively used to make a lot of hp. Superchargers have also been used for making a lot of hp. Turbos often heat the air less for a given boost level than a blower, but that can all change with the size of the turbo selected and the type of supercharger you are using. A "roots" style blower is less effecient than a vortech or paxton style (basically a belt driven turbocharger). There are a lot of if's in that statement, but I'm not sure I'd give the nod to the supercharger. A turbo can make more boost at a low rpm by adjusting the wastegate while a supercharger is limited by the maximum boost you can handle at redline and it will often suffer a reduction of boost at lower RPM (where a turbo will just adjust the waste gate for more boost). On a paxton or vortech style (and others) blower, also known as "centrifugal", you suffer a reduction of boost at lower rpm and it's generally a factor of 4 (not 1/2 the boost at 1/2 the RPM, it's typically not that linear).

Anyway, enough of my rambling.

[wd0ct]

Quote[/b] (kd8dpl @ July 09 2006,07:20)]Quote[/b] (wd0ct @ July 08 2006,16:46)]Quote[/b] (N0WVA @ July 08 2006,15:50)]What if most of the heat from your car engine could be converted into rotary motion and somehow applied to the rest of the drive train. How much more efficient would that make the internal combustion engine?
a turbocharger linked to the drivetrain would do this. i'm sure it has been done.

search adiabatic engines
While a turbocharger will increase the adiabatic effeciency of an engine, it's nowhere near the roughly 70% gain you'd see if you could do what was asked in the first post. Off the top of my head, roughly 30% of an engines thermal energy is lost through the cooling system and roughly 50% is lost through the exhaust system. Yes, I'm aware that 50% and 30% do not add up to 70%, which is why I added "roughly". I believe the total "waste" is about 70% and the other 30%/50% numbers will be a bit more or less, totalling roughly 70%. Did that make sense?
Yeah you make sense. As far as I know no energy conversion can be 100% efficient.

I didn't mean a turbo by itself was the total answer. I only meant that a turbo or exhaust driven turbine has been geared to the driveline before. You have to lose the cooling system too for more efficiency.

[KC0KBH]

There are people that take old Lister diesel engines, run the engine on used veggie oil, generate electricity and use the coolant to heat (or partially heat) their house. ;)

[wd0ct]

here is a novel way of increasing efficiency. steam expansion and getting rid of the cooling system. of course it was done by an old hot rodder.

and don't forget one of sharpest guys around was smokey yunick.

bruce crower (http://paultan.org/archives/2006/03/14/bruce-crowers-6-stroke-crower-cycle-engine/)

[KC0KBH]

I just came in from messing around with one of the biggest engines I own, a Kawasaki 250 four stroke 4 valve DOHC engine that belongs in my '84/'85/'87 KLR250 enduro. Just torqued the cam gear bolts on the cams, and will be waiting on a head gasket, and cylinder honing soon. http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif