High efficiency dual cycle internal combustion engine with steam power recovered from waste heat

摘要

A high efficiency combined cycle internal combustion and steam engine includes a cylinder having a piston mounted for reciprocation therein with an internal combustion chamber outward of the piston, a fixed cylinder cap sealingly and slideably mounted within the piston and a steam expansion/recompression chamber inside the piston adjacent the cylinder cap. The cylinder cap can be unheated or heated externally to reduce condensation of steam entering the steam chamber from a steam generator fired by waste combustion heat. Steam remaining in the cylinder when a steam exhaust valve closes at the top center position is recompressed during an inward stroke of the piston up to admission pressure prior to admitting the next charge of steam. One valve or a pair of retractable steam inlet valves connected in series within the cylinder cap act in cooperation with steam recompression and clearance volume to achieve an effective zero steam chamber clearance and a gain in mean Rankine cycle temperature to maximize efficiency. The amount of steam admitted each outward stroke is continuously regulated, e.g. by shifting the phase of one steam admission valve of a pair to vary their overlap for determining the steam mass admitted during each cycle to reduce specific fuel consumption. Other valves balance steam displacement with the steam generator output to use steam more efficiently. Engine coolant can be evaporated in a combustion chamber cooling jacket to form steam which is then superheated in a combustion exhaust manifold.