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I CAN HAZ CROISSANTZ?
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Water boils at 100deg.C. Ethanol boils at <80deg.C.
Why can't we construct a low pressure piston engine powered by expanding ethanol vapour, the exhaust vapour to be collected, condensed and fed back into the ethanol reservoir?
The heat needed to raise the temperature to >80deg. C. can be commonly
found (geothermal, solar, industrial exhaust gases) or generated cheaply, and the engine (constructed of modern materials) put to useful work.
If the unit is designed well, sealed, and the temperature is kept low, the chances of fire should be minimal.
Such engines existed around the turn of the 20th century using naphtha. Could someone please - intellectually - revisit this technology with 21st century experience?
I also understand that there are fluids which boil as low as 65deg.C. (ethanol/benzene or cyclohexane), but I don't know the downsides of using this fluid as a working vapour.
As for Carnot, what does it matter if the piston is as big as a dinner plate and the stroke is small, that's what cogs are for.
The one question to keep in mind is - can this engine do more work for a lower cost than competing systems?
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As you pointed out yourself, it is going to be very low pressure. Also, the higher the pressure gets, the higher the boiling point of your fluid becomes. |
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This is esentailly a Sterling (closed-cycle) engine, and as such is Baked. |
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Why alcohol? There are non-inflammable
liquids that boil at
any temperature you like from about
-273°C upwards. |
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