High efficiency dual cycle internal combustion steam engine and method

A combined internal combustion and Rankine cycle engine for recovering waste combustion heat comprising,

• at least one cylinder having a combustion piston slidably and sealingly mounted therein at one end of a combustion chamber and said engine having a steam expansion chamber,
• the combustion chamber being outward of the piston and including a combustion intake valve and a combustion exhaust valve communicating therewith,
• the steam expansion chamber being located in a cylinder of the engine,
• at least one steam inlet valve connected to be operated in timed relationship to the piston movement for admitting steam produced by waste combustion heat into the steam expansion chamber through a fixed cylinder head as a part of the engine,
• a steam exhaust valve connected for exhausting steam from the steam expansion chamber,
• a cooling jacket at least partially surrounding a cylinder,
• a pump connected to the cooling jacket to cause the coolant to flow therethrough in a coolant perturbation pathway inside the engine comprising an endless intrajacket circuit that is independent of coolant flow outside of the cooling jacket,
• a second pump for transferring coolant from the cooling jacket through a second circuit outside of the cooling jacket to a heat exchange coupling between the coolant and a steam condensate to transfer heat to the steam condensate from the coolant and
• a steam generator fired by waste combustion gas connected to further heat the steam condensate to provide steam for the steam expansion chamber.

A combined internal combustion and Rankine cycle engine for recovering waste combustion heat comprising,

• at least one cylinder having a combustion piston slidably and sealingly mounted therein at one end of a combustion chamber that comprises a first thermodynamic cycle of energy conversion and said engine having an expansion chamber for steam comprising a second thermodynamic cycle of energy conversion,
• the combustion chamber being outward of the piston and including a combustion intake valve and a combustion exhaust valve communicating therewith,
• the steam expansion chamber is located in at least one of the cylinders in communication with the piston of the at least one of the cylinders,
• at least one steam exhaust port and at least one steam inlet valve to power the piston of the at least one of the cylinders by admitting steam produced by waste combustion heat from the combustion chamber into the steam expansion chamber through the steam inlet valve as a part of the engine,
• a cooling jacket for the first thermodynamic cycle in thermal transfer relationship with the combustion chamber,
• a liquid non-aqueous coolant contained in a cooling jacket circuit of the first thermodynamic cycle is interposed as a thermal interface between the first and the second thermodynamic cycles of energy conversion to transfer heat from the cooling jacket to a heat exchange coupling between the liquid non-aqueous coolant and the steam or a condensate of the steam from the steam expansion chamber to thereby heat the steam or condensate.

A high efficiency method of operating a dual internal combustion and Rankine cycle engine to recover waste heat and having at least one cylinder, said engine containing a combustion chamber and a steam expansion chamber with a piston slidably and sealingly mounted for reciprocation therein comprising the steps of,

• providing a fixed steam cylinder head mounted as a part of the engine,
• providing a cooling jacket in thermal transfer relationship with a combustion chamber,
• providing a non-aqueous liquid coolant that has a boiling point of at least 225° F. in the cooling jacket of the combustion chamber,
• transferring the non-aqueous coolant from the cooling jacket to a heat exchanger circuit for heating steam or a steam condensate and thereby recovering waste heat from the combustion chamber while maintaining the coolant thus transferred above 212° F.,
• transferring the heated steam or the condensate thereof through a steam generator fired by waste combustion gases from the combustion chamber that supplies additional heat to the steam or the condensate which is then transferred to the steam expansion chamber,
• such that the non-aqueous liquid coolant serves as a thermal interface between two thermodynamic cycles of energy conversion comprising (a) at least one of an Otto, Atkinson, two-stroke or Diesel cycle and (b) the Rankine cycle.

A combined internal combustion and Rankine cycle engine for recovering waste combustion heat comprising,

• at least one cylinder having a combustion piston slidably and sealingly mounted therein at one end of a combustion chamber and said engine having a steam expansion chamber for a working fluid,
• the combustion chamber being outward of the piston and including a combustion intake valve and a combustion exhaust valve, the steam expansion chamber being located in at least one of the cylinders in communication with the piston thereof,
• a steam inlet valve for injecting steam to power the piston of the steam expansion chamber and connected to be operated in timed relationship to piston movement for admitting steam from a steam supply produced by waste combustion heat from the combustion chamber into the steam expansion chamber through a fixed cylinder cap,
• a steam exhaust valve having an exhaust port for discharging steam from the steam expansion chamber,
• a connecting rod which is moveable along a central longitudinal axis of at least one of the cylinders is operatively connected between the piston thereof and a crankshaft and is disposed for movement in a space between the cylinder cap and the crankshaft,
• the steam supply including a heater connected to the combustion exhaust valve to receive exhaust gas therefrom to heat the working fluid for injection through the steam inlet valve into the steam expansion chamber, and
• a fuel burner comprising a source of supplemental heat that is separate and independent of the combustion chamber and is operatively connected to supply heat to the working fluid so as to provide a portion of the Rankine thermal energy input from a source that is external to the heat energy from the combustion chamber exhaust gas.

A method of recovering waste heat in a dual Rankine cycle and internal combustion piston engine comprising the steps of,

• providing at least one cylinder having a piston slidably and sealingly mounted therein and a cylinder head with an internal combustion chamber therebetween, the engine also having a steam expansion chamber in at least one of the cylinders that is operatively associated with a piston therein, wherein each piston is operatively connected to a crankshaft;
• providing the internal combustion chamber with a cooling jacket that at least partially surrounds the combustion chamber;
• providing a heater fired by combustion products from the internal combustion chamber;
• providing a Rankine working fluid in a circuit that passes through the heater, followed by a Rankine cycle expansion in the steam expansion chamber and thereafter through a condenser to form a condensate;
• providing a non-aqueous coolant that has a boiling point which is above the boiling point of the working fluid;
• heating the non-aqueous coolant in the cooling jacket of the combustion chamber to a temperature that is above the boiling point of the working fluid but is below the boiling point of the coolant;
• circulating the heated non-aqueous coolant as a thermal interface between two thermodynamic cycles, of energy conversion comprising the internal combustion cycle and the Rankine cycle to thereby heat the Rankine working fluid in a first heating stage;
• and
• thereafter passing the working fluid through the heater fired by combustion exhaust gas from the combustion chamber.