Efficiency Improvements for Internal Combustion Engines

[NeilBlanchard]

What is the best way to produce something useful from the waste heat from an ICE?

I think the best thing to do is produce electricity with the waste heat -- something that can contribute a significant amount of work to actually moving the vehicle.

Do you have better ideas?

[dcb]

Will it be more efficient than hydraulic? Show your work and assumptions and cite any references.

[Frank Lee]

Originally Posted by NeilBlanchard

What is the best way to produce something useful from the waste heat from an ICE?

Do you have better ideas?

ICEs have such built-in inefficiencies and they seem insurmountable to a large degree. So I'd think that a strategy or algorythm that minimizes the inefficient phases of operation has the potential to "cancel out" much of those losses. Such as, a hybrid system that allows the ICE to run in it's max efficiency zone for a brief period of time while the other power "source" be it flywheel, hydraulic, electric, etc., covers the rest of the needs. AND/or an automated, semi-automated, or advisory P&G system that takes over for/partially takes over for/assists by advising the non-Wayne Gerdes' of the world to achieve optimal P&G strategies.

Another approach I've considered is to accept that there will be waste heat and figure out how to utilize it not necessarily for motive power for the vehicle... like, if the excess heat, instead of being dissipated through radiators, was all stored in a thermos of some sort, then when you get home you hook it up to the house and release all that heat into the living space for heating. Or whatever...?

[jakobnev]

Originally Posted by NeilBlanchard

What is the best way to produce something useful from the waste heat from an ICE?

I'm thinking steam engine - the heat could be taken just after the cat on a gasser or from the EGR-cooler on a diesel

[autoteach]

How about instead of refrigeration trailers for semis we create oven trailers using the waste heat... or dehydrators. That way the jerky could be made in route to the delivery. Just saying...

[Rokeby]

Originally Posted by NeilBlanchard

What is the best way to produce something useful from
the waste heat from an ICE?

On the 'Web:

Cooking... with your car

[todayican]

The remark about steam engines turning a gen got me to thinking....
Found this:
Green Steam Engine Home Page

[mnmarcus]

(I could be corrected on any of the following by many) These are thoughts, impressions and recollections...

I think the problem with exhaust heat is how do you tranfer it to do work? Increasing back pressure would make the ice even more inefficient. The amount of heat you could "capture" from the exhaust would be negligible, I'd assume. I think after things like motor inefficiencies and the extra weight, you wouldn't even be able to run an alternator off most cars exhaust using some kind of steam engine. Possibly a tiny turbine? I think the efficiencies of most turbines is not scalable, the smaller you get the less efficient they become.

Maybe a ceramic motor would help create more useable exhaust heat. I'm pretty sure an ice's maximum efficiency is linked to a temperature differential, that is, a very very hot engine would be a lot more efficient than a "cool" engine with the same outside temperature. So sapping heat from the engine probably would not get you a net gain.

I believe the same thing can be said for most hybrids. Using an ice to charge a battery (or hydraulic accumulator) for propulsion would be less efficient than just using a direct motor to propulsion transmission. Except for gains made in engine off (coasting or stopped) time. Which would be possible with most any car now.

Sorry for the tangents...

[NeilBlanchard]

The Crower 6-stroke engine has one way to add work from the excess heat. With about 80 of the energy going into waste heat; there is significant amount of heat. Even at the theoretical maximum of ~54% efficiency, there is still a very significant amount of heat wasted.

Steam could power a generator, or be used directly like in the Crower, to spin the engine. Heat can be used (though not particularly efficiently) to directly make electricity. So, it seems the most likely ways to get the efficiency above the theoretical limit is to use the otherwise wasted heat to make steam and/or make a hybrid with an electric drive.

[jakobnev]

Originally Posted by mnmarcus

I think the problem with exhaust heat is how do you tranfer it to do work? Increasing back pressure would make the ice even more inefficient. The amount of heat you could "capture" from the exhaust would be negligible, I'd assume.

Wow, well that settles it - there's nothing more conclusive that the assumption of someone who doesn't even know that a counter current heat exchanger is the best way to transfer heat between two fluids.