Thank you Professor, but sustainable mobility is also a political choice.

Interesting, but complex--similar in concept to high-efficiency combined cycle power plants. How does this mesh with BMW's avowed intention to include idle-stop and regen braking on all their cars? Sure seems like a lot of complexity under the hood, with attendant higher costs and expensive maintenance.

"Sure seems like a lot of complexity under the hood, with attendant higher costs and expensive maintenance."

Their current products are not priced for the mass market.

Some complex tradeoffs here. If there's a significant amount of high pressure steam storage, then the system offers some of the same performance features that make hybrids attractive. I.e., high torque at low speed, enabling a smaller engine, and idle stop capability. Good fuel mileage, but no regenerative braking.

Where something like this could make sense is in a plug-in serial hybrid. The engine would be undersized, delivering somewhat less than the average power needed for freeway driving. It would be run full on to extend the range of what would be mostly a battery EV.

Catalytic converters add energy to the exhaust stream by burning fuel that wasn't burned inside the cylinders. It may be advantageous to use an inherently dirtier but smaller engine like a two-stroke or wankel. The small engine would be essentially an apu in which its exhaust is burned inside a larger boiler and using the steam for vehicle propulsion. Something similar was tried in the 1920s but never went into production.

Very reminescent of the compound turbo.

Exactly. Turbocompounding sure sounds simpler and lighter weight than adding a full-featured steam engine.

IIRC Scania is using it in some of their newest truck engines.

What they should do, and maybe have, is study all possible bottoming cycles, including stirling engines ( my one note theme, endlessly repeated) Stirlings are compact and highly reliable these days, and recover available energy better than steam cycles. You can arrange a multi piston stirling to receive heat at several temperatures, analogous to a multiple expansion steam engine, all blowing the stirling working gas over one turbine, which could be driving an alternator, or be geared to the engine.

This system might not have gone into diesel ships, because the exhaust temperatures are already significantly lower. Diesel engines have a much higher compression ratio and a turbocharger. Both, high compression ratios and turbochargers lead to lower exhaust temperatures.
The potential gains on a gasoline engine should be significantly higher. Although, I wonder how effective this system is at mainly partial throttle operation.

What's not to like? Free power with better fuel economy? "

Er, its not free if it adds systems complexity and weight to the whole engine ... but it may be worth it.

"similar in concept to high-efficiency combined cycle power plants."

Exactly so. and the 'turbocompounding' concepts. ICEs today top out
at 40% thermal efficiency, but combined cycle power plants push it over 50%. This apparently may do the same thing.

"What amazes me is that a system like this has not already gone into diesel ships and heavy long-haul trucks."
Good point.

Since it also uses the car radiator for a heat exchanger, would it not mean a bigger radiator, or a second radiator for the special coolant? Or am I reading the diagram wrong?

The positive can be that it complements regenerative breaking, because a car idling at traffic lights will heat up considerably more, thereby creating more heat that can later be used as a boost to get it going in the form of electric energy.

The system does not appear to be that large. I'd like if it was available as a kit for all cars, seeying as how custom exhausts once thought to be for racing guys is commonplace now. The electricity generated does not have to be linked up to some fancy electric drive system. It may just accumulate to be used to complement incar electronics. At the very least a complement to the alternator when the car is idle.

Also, how do you think this system compares to the fuel vapouriser thats supposed to use the exhaust to heat incoming fuel so when it enters the intake its close to boiling point necessitating better mixture hence better burn? I know its not the same thing, but in essence it uses the exhaust energy so I thought to give it a mention.

when will this car be produced or be available for the public to purchase?

how much will one of these cars cost?

will they be low maintenance vehicles as far as car parts go?

will they be considered a sports car or a town car?

I've been telling people this idea since gas hit $1.00 a gallon. Only difference is this "Turbosteamer" is much more complex than my idea. Mine was a simple steam driven design with the water already in the block being super-heated by the exhaust via a simple heat exchanger to drive the turbo. As for the high emission problems, incorporate the catalyst in the exchanger. As previously pointed out, a low design / production cost idea that can be retrofitted to ANY existing vehicle is the golden egg.

During the early years of automotive developement when both gas and steam vehicles were produced, a combination of both was tried. The car was called the "Compound". It features a three cylinder engine. The two outer cylinders ran on gas and both alternately exhausted into the center cylinder which functioned as a steam engine. The outer cylinders had four inch pistons and the center cylinder had an eight inch piston. One of the advantages of this configuration included low noise output as the steam cylinder absorbed a lot of the noise. As far as efficiency and fuel milage I have no idea. If a catalitic converter was added between the gas and steam cylinders along with water injection to convert the extra heat to more steam pressure before entering the steam cylinder, this type of engine might prove to be efficient yet somewhat simple. What do you think, and does anyone have further and more detailed information about the Compound automobile?