Waste Heat Power Recovery?

[Docengineheat]

Nearly everybody knows that both gas and diesel engines waste lots of heat from the coolant system and exhaust system.

I'm interested in the forums opinions on why there do not appear to be any viable systems that recover this waste energy and use it to improve engine efficiency. What comes to mind is using a steam engine that is powered by the exhaust heat.

Anybody have any insight on why this hasn't been done?

 

[Docengineheat]

I visited "

http://www.keelynet.com".

I start being quite skeptical when "pyramid power" and "radionics" are presented as anything other than an example of pseudoscientific thought.

Certainly if there are viable ways to recover coolant and exhaust heat somebody other than those concerned about spaceship energy rays should know about it.

 

[tbuelna]

here is an interesting patent from Honda that covers a system for waste heat recovery on internal combustions engines: (#6,668,786)

http://patft.uspto.gov/netacgi/nph-...0&s1=6668786.WKU.&OS=PN/6668786&RS=PN/6668786

Regards,
Terry

 

[SBBlue]

Okay, I visited the site.

Can anybody tell me what this means? (It's from the patent application)

"A rotary fluid machine including a displacement expanding machine provided in a Rankine cycle apparatus where pressure energy of a first temperature and pressure vapor generated by heating water with waste heat from a prime motor is converted to mechanical energy, and a resulting second temperature and pressure vapor is condensed to be again heated by the waste heat, the expanding machine thus converting the pressure energy to mechanical energy,
wherein the first temperature and pressure vapor are greater than the second temperature and pressure vapor, and wherein the expanding machine comprises at least first and second energy converting means, and integrates and outputs mechanical energy generated by the first and second energy converting means, respectively, by inputting the pressure energy into the first and second energy converting means to convert the pressure energy to the mechanical energy."

 

[gazza285]

Nobody's mention the good old Sterling engine yet.
I thing Greg has hit the nail on the head

" how much plant are you prepared to install in a car to retrieve 22 hp, and what would you do with it?"

As to gbent's comments

"GE makes a combined cycle power plant they claim 60% efficiency on. They fire a gas turbine with natural gas, and use the waste heat to make steam to run a steam turbine. I don't know the size range for these units, but a wag would start at 40,000hp."

I have worked on a similar plant in the UK that use 3 year old willow tree chippings to feed a gasifier, the gas extracted then fired a gas turbine, with the exhaust and furnace burnt chipping remains then combined to turn a steam turbine. The power station produced a net of 8 megawatts, and the willow tree plantation occupied 5000acres. However this proved to be a bit of a failure, after four years of building and commissioning the plant only actually produced for 8 (eight) days before the plug was pulled.

More info here

http://groups.yahoo.com/group/Know_Nukes/message/1854

As a result I am a little bit sceptical to the benefits of such a system.

 

[kiwinjuneer]

If were were not totally familiar with a

500 lb
multi-piston
DOHC multivalve
variable valve timing
multipoint fully mapped injection engine

would we be saying that a gas turbine with a single moving part it too heavy and complex?

IMHO there is an opportunity for a complete rethink of powertrain engineering with potential for a hydrid/combined cycle/CVT powertrain where a tiny, very light gas turbine produces say 50 kW at 25% efficiency, the steam turbine increases this to say 50% and the hybrid capability provides some regenerative load smoothing.

Too expensive? A common shaft gas/steam turbine could be made for very little more than the sophisticated turbochargers now in common use. Check out the William mini jet engine used in cruize missiles etc, which I understand, has a rotor machined from a single forging. The HRSG is nothing to be scared of either as it could likely perform double duty as the catalytic converter.

Such a powertrain could be made to be very fuel tolerant while longevity would likely be incredible. Solar have over 100,000 hrs on some of their GTs with the only maintenance costs being a little oil and filters.

Time to call a halt on development of the "zero emissions", expensive and very fuel-intolerant fuel cell?