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AssigneeThe United States of America as represented by the United States Department of Energy
InventorsJohn C. Wheatley, Gregory W. Swift, Albert Migliori
Estimating the term…
A class of heat engines based on an intrinsically irreversible heat transfer process is disclosed. In a typical embodiment the engine comprises a compressible fluid that is cyclically compressed and expanded while at the same time being driven in reciprocal motion by a positive displacement drive means. A second thermodynamic medium is maintained in imperfect thermal contact with the fluid and bears a broken thermodynamic symmetry with respect to the fluid. the second thermodynamic medium is a structure adapted to have a low fluid flow impedance with respect to the compressible fluid, and which is further adapted to be in only moderate thermal contact with the fluid. In operation, thermal energy is pumped along the second medium due to a phase lag between the cyclical heating and cooling of the fluid and the resulting heat conduction between the fluid and the medium. In a preferred embodiment the engine comprises an acoustical drive and a housing containing a gas which is driven at a resonant frequency so as to be maintained in a standing wave. Operation of the engine at acoustic frequencies improves the power density and coefficient of performance. The second thermodynamic medium can be coupled to suitable heat exchangers to utilize the engine as a simple refrigeration device having no mechanical moving parts. Alternatively, the engine is reversible in function so as to be utilizable as a prime mover by coupling it to suitable sources and sinks of heat.
A heat engine comprising a first medium and a second medium in imperfect thermal contact with one another, said first medium being movable in reciprocal motion with respect to said second medium along a path of reciprocal motion, said reciprocal motion of said first medium being accompanied by a temperature change in said first medium such that the temperature of said first medium varies progressively as a function of its displacement with respect to said second medium, the average heat flow between said first and second mediums per unit length along said path of reciprocal motion increasing along said path of reciprocal motion in a first region and decreasing along said path of reciprocal motion in a second region, and wherein said second medium is of a length in the direction of said reciprocal motion which is substantially greater than the range of said reciprocal motion, whereby the heat engine is operable either as a heat pump, by driving said first medium in said reciprocal motion so as to produce a useful differential temperature distribution in said second medium, or as a prime mover, by inducing a differential temperature distribution in said second medium to thereby cause said first medium to move in cyclical reciprocal motion that may be applied to perform useful mechanical work.
A heat pump comprising a first medium and a second medium in imperfect thermal contact with one another, said first medium being movable in reciprocal motion with respect to said second medium along a path of reciprocal motion, said reciprocal motion of said first medium being accompanied by a temperature change in said first medium such that the temperature of said first medium varies progressively as a function of the displacement of said first medium with respect to said second medium, the average heat flow between said first and second mediums per unit length along said path of reciprocal motion increasing in a first region and decreasing in a second region, drive means coupled to said first medium for driving said first medium in reciprocal motion, and wherein said second medium is of a length in the direction of said reciprocal motion which is substantially greater than the range of said reciprocal motion, whereby driving of said first medium in said reciprocal motion results in production of a differential temperature distribution in said second medium.
A prime mover comprising a first medium and a second medium in imperfect thermal contact with one another, said first medium being movable in reciprocal motion with respect to said second medium along a path of reciprocal motion, said reciprocal motion of said first medium being accompanied by a temperature change in said first medium such that the temperature of said first medium varies progressively as a function of the displacement of said first medium with respect to said second medium, the average heat flow between said first and second mediums per unit length along said path of reciprocal motion increasing in a first region and decreasing in a second region, said second medium being of a length in the direction of said reciprocal motion which is substantially greater than the range of said reciprocal motion, and means thermally connected to said second medium for inducing a differential temperature distribution in said second medium to thereby result in cyclical reciprocal motion that may be applied to perform useful mechanical work.
Dependencies are inferred from the claim text.