Quote:
Originally Posted by eco86
I'm beginning to think that the steam solution is an overly complex solution to this problem of extracting waste heat from the exhaust. Exhaust heat is pretty close to 500F, probably more if you get to it closer to the exhaust ports. Seems that a Stirling engine made to close tolerances would work well off of just the exhaust gas flowing over the hot side heat exchanger, with the cold side of the Stirling being exposed to outside air. The larger the temperature differential the engine is exposed to, the more power it can make.
If you have to machine parts to make a boiler, heat exchanger, and whatever adapters are necessary to join a compressor or gerotor to to the system to work as a steam engine, not to mention the condensor if the system is going to be a closed loop, why not just work on adapting a kit Stirling motor to generating power? Or just machining one? Or arranging some reduction gears to reduce the rpm's of a turbocharger from 150K to 3-5K to drive an alternator?
Just seems like the thread is getting away from DIY when dealing with the necessary specifications to make steam power safe.
So anyway, here's a DIY machined Stirling engine that would produce the necessary power to run an alternator in a vehicle, using air as the working medium.
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Steam is hard to integrate, but really offers the best potential for recovering a high percentage of heat. I really can't see getting much power back from a sterling, though it could be fine for a alternator and or other accessories.
Of the fuel's potential energy 70-90% is lost as heat. If 25% of that energy could be used you would have about twice the power.