turbo alternator

[BrianAbington]

ceramic bearings would help over come those resistance issues.

Car alternators are designed to work most efficently while at speed, if you look at a graph of output for an alternator its not much at idle, then its power output increases with engine speed the out put increases propotionate to rpms and drops off at higher rpms.

However that airplane generator you refered to probably has a step gear in it like a centrifugal super charger to keep speeds under control.

A car turbo charger often spins at 200,000-300,000 RPMs so you wouldn't even be generating power because it would be spining way to fast to produce anything.

[NiHaoMike]

What if water injection is used between the cats and turbine? Wouldn't the steam allow the turbine to operate with a higher flow but lower pressure drop?

[NeilBlanchard]

Hi,

A gate could be opened up to spin the turbo and generate power as needed. You would need to design for higher loads on the battery, but I think this idea has merit.

[evolutionmovement]

A wastegate to throttle the amount of exhaust gas spinning the alternator, you mean?

BMW is working on a system that uses exhaust heat to generate steam to spin an alternator.

[NiHaoMike]

I'm thinking that if water is added to the exhaust gases, it will form steam to add to the volume. Then the required power could be attained with a lower pressure drop. Someone should thermodynamically analyse it but I think it would mean higher overall efficiency.

For even higher efficiency, preheat the water by running it through a heat exchanger heated by coolant.

[Frank Lee]

How about use a magneto for ignition and throw out all that electric crap except for lighting.

[orange4boy]

I hate to throw the wrench of reality into this thread but the turbo/heat extraction/steam recovery/alternator idea is not one for the average backyard mechanic.

Get one or two deep cycle batteries and stop being a mental master debater. And switch as many lights to LED as humanly possible. Simple effective and cheap. It's plug and play.

If you are having fun thinking about this anyway...fill your boots.

[chuckm]

AMEN!

If there were a ton of easily recovered energy in exhaust gas, then two things would become quite apparent: 1) The engine was not doing a good job and 2) Auto companies, with the hoards of engineers working full time, would have pursued and knocked this out already. Heat energy, with the working medium at ambient (or very nearly ambient) pressure, is very difficult to extract efficiently without a ton of accessory equipment (power plants have feedwater heaters, extremely high pressure pumps, and lots of etc). All of this means extra weight. If BMW is pulls off the system the system evolutionmovment mentioned, it would be a hell of an engineering accomplishment.

[NiHaoMike]

We know aerodynamic modifications work and are very cost effective, but why aren't the major auto companies using that to the extent the Aerocivic does?

[chuckm]

NiHaoMike: The answer, IMO, lies in the fact that under the hood, engineers get the most influence. In the cabin and in the body shape, non-engineer designers have more influence. The aerocivic just doesn't fit the general public's concept of what a car should look like. The key question is "Will it sell?"