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

[dwtaylorpdx]

There is a basic relation ship to the temperature of the incoming exhaust and the speed of the turbo due to the temperature drop as the exhaust gases expand in the turbo but its not much.

On many race cars the alternator is driven by a belt off the pinion gear of the differential. It reduces the load on the engine in the vehicle because its taking advantage of the gearing at the output end of the transmission. It also means the alternator spins at a more consistent RPM and does not see the extreme rpm's at WOT.

Its also only charging when the car is moving, if you added a field switch to the gas pedal it would only charge when your foot is off the pedal. (Coasting) This might work for reducing the charging cost of the vehicle? Might be a intermediate way to extend the distance of a vehicle that is running without a alternator currently but not go to a full time alternator, could even be a downsized alternator, (Mitsubishi forklift alternator) that has like a 45 to 55 A output.

Just thinking..

Dave

[Christ]

Originally Posted by basslover911

Yes but remember your replacing a muffler for this, so the back pressure should be the same or less than how the car came from factory since your not adding anything to the system just replacing something

And what turbine? Well more like a water pump that turns an alternator.

You're not accounting for losing heat from the exhaust, which slows the flow, thereby increasing pressure.

You're not going to take my word for it, and I don't blame you. Just do it, you'll see what I mean.

/debate

[extragoode]

Originally Posted by dwtaylorpdx

On many race cars the alternator is driven by a belt off the pinion gear of the differential. It reduces the load on the engine in the vehicle because its taking advantage of the gearing at the output end of the transmission. It also means the alternator spins at a more consistent RPM and does not see the extreme rpm's at WOT.

Its also only charging when the car is moving, if you added a field switch to the gas pedal it would only charge when your foot is off the pedal. (Coasting) This might work for reducing the charging cost of the vehicle? Might be a intermediate way to extend the distance of a vehicle that is running without a alternator currently but not go to a full time alternator, could even be a downsized alternator, (Mitsubishi forklift alternator) that has like a 45 to 55 A output.

Just thinking..

Dave

I'd love to do this and started a thread discussing it about this time last year. I just couldn't come up with any practical way to accomplish it. I also didn't know that's what was done on race cars, but it makes sense, plus those guys will do anything to get more total power out of the engine. Do you know of any aftermarket parts for this that would work on my pickup? Or on any production vehicle, or are all the setups you're talking about completely custom?

[basslover911]

Originally Posted by Christ

You're not accounting for losing heat from the exhaust, which slows the flow, thereby increasing pressure.

You're not going to take my word for it, and I don't blame you. Just do it, you'll see what I mean.

/debate

Ohh got you got you. Im just thinking if the backpressure of this intercooler is less than an oem muffler, then the extra backpressure made by the "cooling of the exhaust" + lower back pressure intercooler = oem muffler back pressure (hopefully). Again i'm just throwing ideas out there but your right I didnt take that into account.

[nemesis]

Originally Posted by extragoode

I'd love to do this and started a thread discussing it about this time last year. I just couldn't come up with any practical way to accomplish it. I also didn't know that's what was done on race cars, but it makes sense, plus those guys will do anything to get more total power out of the engine. Do you know of any aftermarket parts for this that would work on my pickup? Or on any production vehicle, or are all the setups you're talking about completely custom?

This is a great idea, but there is a downfall to that, there are usually 22-16% losses in the drivetrain, so the engine is going to work little bit harder to turn the alternator which will give you worse results on the highway, but will definitely give you positive results in stop and go traffic. This is my personal opinion only, it my be wrong.

On that same note I think the best idea would be is to get the alternator working while you're gliding/decelerating/coasting, I am sure there is a way to get it working off of tps reading.

[hamsterpower]

Originally Posted by Christ

You're not accounting for losing heat from the exhaust, which slows the flow, thereby increasing pressure.

Wouldn't the loss of velocity be directly proportional to the loss of volume as the exhaust gas cools? Instead of the usual constriction of smaller pathways or a turbo. There for no real change in pressure upstream of the heat exchanger.

[DonR]

How fast do you think you are going to get coolant to flow using natural convection? This is the side of the equation I would concentrate on. Even if you have cooling fins into the airflow on the return line I can't forsee getting much flow out of natural convection.

As far as getting heat out of the exhaust, Someone makes a double wall tubing with fins on the inside. Use this as the exhaust tubing. You would need to turn off some of the outside & weld on a sleeve type fitting on either end for the water lines.

Don

[Christ]

Originally Posted by basslover911

Ohh got you got you. Im just thinking if the backpressure of this intercooler is less than an oem muffler, then the extra backpressure made by the "cooling of the exhaust" + lower back pressure intercooler = oem muffler back pressure (hopefully). Again i'm just throwing ideas out there but your right I didnt take that into account.

Here, you may be correct. It could be the same as the OEM backpressure figure, and I don't think I know the math to confirm or deny, so the best way to test, of course, is to test.

Of course, like I said before, there is an equilibrium point, where you just won't have any more backpressure build up, because you won't be extracting any more heat.

Maybe, if you have the cash, you might consider two of these inline in the exhaust? You might be able to get a marginally higher temperature, but more surface contact, so more fluid velocity due to quicker heating.

[bgd73]

if this worked, why aren't they using cylinder heads to pump thier own water through convection? I have an old boxer that gurgles like a coffee pot in the heater core...and it s a direct shot inches from combustion chambers as the source of heat. As soon as the heat source notices the exhanger, at any distance from the combustion, it will be lost dramatically. As an example, just one foot from the convertor in my own car has an accidental shot of 260 degree paint, that never left it.
The exhaust has radioactivities as well...gurgling noises would only be one unstoppable weirdness..I bet it could recycle its own electrical current from spark plugs. The direct shot of a turbine with actual exhaust pressure is about all one can do and stay sane with a function like this, its called a turbo.

[basslover911]

Well thats my only problem, wondering how much flow there would actually be by natural convection.

And really natural convection is the only real way to do it, because if you use a pump it kind of defeats the purpose of the other pump that is producing electricity... Unless the pump simply gives it a "head start" and the heat further accelerates the flow... would that work?

Ive been trying to look around for videos on maybe sience labs or something that can show heating on one side of a pipe and the water actually moving to the other side of the pipe (so I can see how hot it really needs to get (or the temperature difference between each side for that matter)... but I cant find any...