Quote:
Originally Posted by Harlan
I am not violating the laws of thermodynamics nor Carnot's heat engine, I'm simply massaging an Otto cycle adding some Rankine elements and creating something slightly new.
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Still need a turbo to get the biggest gains. Then it would be a true coexisting Rankine cycle.
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IIRC, I'm pretty certain that what you are describing can not be compared to (or claimed to be) a Rankine cycle. Further, adding a turbo (a Brayton cycle) still won't allow the energy in the additional quantity of dry-steam (coming from your method, as you've described it) to generate any further work (aka an efficiency gain).
The reason for this is that by transferring a portion of the exhaust heat to the inlet heat (forget what your method of doing this is for now, ie. ignore the water/steam) you are moving heat from the hot reservoir to the cold reservoir BUT without doing any useful (mechanical) work. This cannot be at all ideal!
You describe the water/steam as
moderating the cylinder temperature, but, if by this you mean
lowering, then this is presciently the opposite of what provides highest Thermal efficiency - ie. The Maximum differential between hot and cold reservoirs. In a way you are diluting this very effect.
If alternatively by moderation you mean limiting the in-cylinder peak-pressure then, yes agreed, but plain old water would do this even better, plus it has no negative impact on the thermal efficiency.
Quote:
Originally Posted by Harlan
As for heating only with engine coolant. ... It drops coolant temperatures because it removes heat from the cycle because it's wet steam. Using the coolant is self limiting because the steam acts as internal coolant.
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If there was some (unexplained) validity to your design then it would undoubtedly be an extra win to produce steam from the block. Remember block cooling is a totally parasitic effect in piston engines (unlike the exhaust temp which is inherent to the heat-engine's workings). Further the cylinder walls are by nature incredibly hot and, though perhaps not an easy modification for the backyard tinkerer, a heatpipe will happily transfer superheating temps all day long (and at a rapid rate too!). ... Imagine the possibilities to completely delete the cooling circuit!