Damned Interesting!

[Lloyd Danforth]

I just heard about this on the radio the other day.


http://www.damninteresting.com/?p=467

[Nicholas Gilman]

  The idea of combining a fuel/air mixture and then using the residual cylinder heat
to make steam is an interesting idea.  About 70-80% of the energy is usually
wasted as heat in a four stroke gasoline engine anyway. 

[dalebert]

OK, there are some idiots leaving comments there. Distilled water is not going to use more energy to make or cost more to make than gas! Even if you just buy it off the grocery store shelf, it's like $1 max. That would scale up really well when you're not putting  it in plastic jugs. They could even have the devices to filter/distill it at the pumps themselves. It would be silly to transport it.

A good point is cold weather though. That presents a real obtacle that they need to start thinking about but it's not a deal-breaker by any means.

[mvpel]

The Prius, I gather, has a dewar flask in which some of the latent heat of the coolant is stored.  Perhaps that'd be an option for the water storage - keep the water piping hot with engine heat, and perhaps have a self-resetting relief valve if the water cools from 200 to <32 degrees over the course of a month in the dewar.

[KBCraig]

The key to making this work in all climates will be electronically controlled valves, so that it is a 4-stroke when cold, switching to 6-stroke when conditions allow. Dump engine heat into the water tank to pre-heat (or thaw!) it.

[dalebert]

The key to making this work in all climates will be electronically controlled valves, so that it is a 4-stroke when cold, switching to 6-stroke when conditions allow. Dump engine heat into the water tank to pre-heat (or thaw!) it.

Yeah, that's what I was thinking. Tricky not having a tank and pipes that crack when water freezes though, right? But perhaps if you recirculate the output of the pistons through pipes around the water tank or something before exhausting it, you could melt it and start using it. Seems like the steam created will help heat it pretty well along with the gas exhaust. I'm sure a little ingenuity could work those things out.

[Raineyrocks]

The key to making this work in all climates will be electronically controlled valves, so that it is a 4-stroke when cold, switching to 6-stroke when conditions allow. Dump engine heat into the water tank to pre-heat (or thaw!) it.

I was just about to write the same thing, you beat me to it!