--- Recover heat from exhaust --- I got just the right heat exchanger!

[basslover911]

A water to air intercooler;



Replace your muffler with one of these, run a water line in/out, and power a small pump to make electricity. (a la BMW, but much simpler).

Theory;
The drop on these intercoolers is VERY low, about .1 psi. The drop on a normal car muffler is of excess of 2 psi. So not only will you get a heat exchanger, but also a free-er flowing muffler.

Since they are made to effectively convert temps from water-air, it will effectively convert temps from air-water.

I think this is the best thing to use as a energy recovery system and easy to implement... what do you think?

[Daox]

I don't see why it wouldn't work.

When I was looking into this, the problem really wasn't finding a heat exchanger, it was trying to find a way to disconnect the heat once the engine is warmed up.


FYI, there is some suspicion that the exhaust heat recovery on the Prius III that the new heat recovery system isn't quite as good as the Prius II's coolant thermos.

[srortega]

The question is how much electricity can you produce and what can you do with it. Would it be to remove all belt driven items from the engine and replace with electric counterparts?

[Old Mechanic]

Great idea!

Heat losses are 67% of the energy content of the fuel. A large portion of that is from the exhaust, probably close to half, or the same amount of energy that actually gets out of the engine to drive the wheels.

Personally I think it would be enough energy to supply all accessory functions. It could possibly be more than that which could be used as an acceleration assist through a toothed belt start stop alternator.

This would also allow the engine to never idle. That would reduce the overall waste heat and reduce the total amount of power available to the re-generator, so the accessory power demands would probably be the overall effect if it was incorporated into a start stop operational strategy.

Idling fuel consumption is calculated to waste 13% of all fuel consumed in vehicles (EPA figures).

The neat thing about steam generation is you can use modern insulation techniques to almost eliminate heat losses in your system. You could also use a lower boiling point self lubricating fluid in place of water.

regards
Mech

[shovel]

Or just wrap copper tubing around your exhaust manifold...

[basslover911]

The point is to remove the alternator, and if electricity generation is that much then yes covert everything to electric.

I tried copper tubing and it's nit efficient AT ALL. That's why I thought about using this. How many watts would this need to produce in order to completely remove the alternator though?

[basslover911]

Originally Posted by Daox

I don't see why it wouldn't work.

When I was looking into this, the problem really wasn't finding a heat exchanger, it was trying to find a way to disconnect the heat once the engine is warmed up.


FYI, there is some suspicion that the exhaust heat recovery on the Prius III that the new heat recovery system isn't quite as good as the Prius II's coolant thermos.

Btw not to correct you but I'm talking about heating a liquid to run a pump via convection NOT to heat up the engine coolant. So it will always be running.

[Christ]

I'd be curious to see it tested, I think pressure drop will be more substantial once you start extracting heat from the exhaust... cooler = more dense, more pressure to move it.

FYI - the pressure drop of intercoolers and radiators is tested under 0 thermal load. the temp going in is the temp going out, minus ambient air changes. In other words, while being tested, it's acting as a free air radiator, but not as an intercooler.

Edit - Darin posted awhile back on wattage required by the alternator for his car - yours is probably higher. I'd say at least 500W to cover all bases, but I'd worry about making it work, first.

[basslover911]

^ Well if it is, that probably how aftermarket mufflers are tested as well (to get "good" numbers). Which is where I got my -2psi (from a magnaflow website I think)... dont you think? (It only makes sense I guess.)

[MetroMPG]

Originally Posted by basslover911

How many watts would this need to produce in order to completely remove the alternator though?

Tested: power draw of Geo Metro accessories & systems (volts, current/amps, watts)