Waste Heat from Exhaust

[TES111]

I have seen plenty of sterlings and Tesla engines screaming on you tube but I have not ever seen one running an alternator or a generator. If you have seen this then put a link up. Make sure they are showing their results. Amps, volts, ect......

[modmonster]

Originally Posted by Big Dave

What you describe is called compounding.

Compounding can indeed increase eficiency. The old B-29 engine (R-3360 I think) and the Napier Sabre were some of the most efficient engines ever built.

Compounding works well (with some reliability issues) at high engine load, but has no scope for contribution at the low loads used by us MPG seekers. Consider turbo lag. A tirbocharger is a form of compounding where the waste heat engine (the turbo) drives a centrifugal compressor. At a low gas flow and heat rate, the turbo makes almost no boost. At high gasflow rate(high RPM) and high heat rate, it works well enough to require a wastegate to prevent overboost.

For a car, with its very light duty cycle to be able to use compounding the main engine would have to be so underpowered as to be running at high load a high percentage of the time. It ain't worth the effort on a high-MPG car.

so you mean if the engine is propperly sized for the load, like a car that mpg seekers would buy, then it would work. of couse its worth the effort. on the highway my 1.0L engine is at 70% load (estimate) at 60mph.

[aerohead]

Originally Posted by elhigh

You're driving something that's 33% efficient? I'm not willing to believe that.

Last I heard, the best gasoline engine out there was only 20, maybe 25% efficient at its very very best. Diesels, by nature of their combustion cycle, are a little better.

I could be wrong - I'm remembering from ten years ago and I haven't heard anybody give an efficiency rating since then. Then again, my ride is older than that and so are a lot of other folks' cars.

I'd give body parts to hit 33% efficiency.

That's the chemical release energy in Btus before any mechanical losses.About 66% of your fuel's energy goes out the tailpipe, or is lost to the cooling system.Some automobiles have efficiencies less than 20% overall.

[MetroMPG]

Some more news on the waste heat recovery front:

Waste Heat Recovery System Receives Powertrain Innovation of the Year Award

The Paris, France-based developer of a waste heat recovery (WHR) system, heat2power, won the Powertrain Innovation of the Year Award at the Professional Motorsport World Expo in Cologne (11-13 November) with its Thermal Energy Recovery System (TERS). heat2power says that its WHR system can provide fuel savings of 15-35% under all driving conditions at a cost of approximately 30% more than a comparable turbocharged gasoline engine.

Source: Green Car Congress: Waste Heat Recovery System Receives Powertrain Innovation of the Year Award

[dichotomous]

I want to do this but I'm annoyed because I just bought a new raceheader and I dont wanna see that as a waste of money.

though, removing everything on the accessory belt and the crank pulley would sure free up power and let the engine use almost no power at idle. imagine the easy low RPM driving with no accessories on the motor....

[tasdrouille]

Originally Posted by MetroMPG

[...]at a cost of approximately 30% more than a comparable turbocharged gasoline engine.[...]

Looks like the cost will be highly prohibitive, which probably limits the tech to high markup vehicles. It's still a good thing for fuel conservation as a whole.