Power plants – Motive fluid energized by externally applied heat – Process of power production or system operation
Reexamination Certificate
2002-01-07
2003-07-22
Nguyen, Hoang (Department: 3748)
Power plants
Motive fluid energized by externally applied heat
Process of power production or system operation
C060S671000
Reexamination Certificate
active
06594997
ABSTRACT:
TECHNICAL FIELD
The invention relates to the development of energy for the purpose of creating power that can be used in a variety of applications, including the generation of electric or motive power for land, marine or air transportation, and to devices and engines for using the same.
BACKGROUND
The present day forms of creating power are generally dependent upon the burning of fossil fuels to generate electric power. In doing so, a serious environmental problem is created in the form of air, water and land pollution. Also, in burning such fuels to create kinetic energy, thermal efficiencies are relatively inefficient due to the formation of incomplete combustion products. This results in exhaust pollution of these products, such as carbon monoxide, carbon dioxide, nitrous oxides and particulates.
Certain attempts have been made to create power without generating such pollutants. Williams U.S. Pat. Nos. 4,086,772 and 4,170,116 disclose a continuous method and closed cycle system for converting thermal energy into mechanical energy. This system comprises vaporizing means, including an energy conversion tube having a special nozzle section, for converting a liquid working fluid stream to a vapor stream. This vapor stream operates a turbine means wherein a portion of the energy of the vapor stream is converted to mechanical shaft work. This system also includes means for increasing the thermal and static energy content of the fluid stream, this means typically being pump means. The vapor fraction of that exits the turbine means passes through condensing means, such as a diffuser, to regenerate the working liquid stream. Finally, means are provided for recycling the condensed liquid stream back to the vaporizing means. The working fluid may be carbon dioxide, liquid nitrogen, or a fluorocarbon. Preferred fluorocarbons are difluoromonochloromethane, pentafluoromonochloroethane, difluorodichloromethane and mixtures and azeotropes thereof.
Johnston U.S. Pat. Nos. 4,805,410 and 4,698,973 disclose closed loop systems that recirculate a vaporizable working fluid between its liquid and vapor states in a thermodynamic working cycle. In this cycle, energy received from an external energy source is utilized to vaporize the fluid to a high pressure in a boiler unit. The resulting vapor is utilized in an energy utilizing device, such as a slidable piston which causes rotation of a crank shaft coupled to a flywheel to deliver mechanical output at a rotating shaft connected thereto. Thereafter, the vapor is condensed into a condensate at a relatively lower pressure in a condensing unit and then is returned to the boiler unit for repeating of the thermodynamic cycle. Also, the condensate flow between the condensing unit and boiler unit is collected in one of two holding tanks in selective pressure communication with the boiler unit. Preferred working fluids include water, Freon or ammonia. Also, thermal regeneration means may be included for providing regenerative heating of the working fluid.
While these prior art systems are somewhat suitable for their intended purpose, there remains a need for improvements in power generation, in particular for small, more efficient systems including engines for generating torque and power. This is now provided by the embodiments of the present invention disclosed herein.
SUMMARY OF THE INVENTION
The present invention relates to a method for efficiently generating mechanical energy which comprises heating a vaporizable, first liquid heat transfer medium to generate a high pressure vapor; utilizing the high pressure vapor to provide mechanical energy and thereafter condensing the vapor to a liquid; and recycling the condensed liquid to the heating step for re-use as the first liquid heat transfer medium. The first heat transfer medium is maintained in a hermetically sealed circuit so that essentially no loss of the heat transfer medium occurs during the heating and condensing steps.
Advantageously, the first liquid heat transfer medium comprises a fluorocarbon or fluorocarbon mixture that (a) generates a high pressure of at least 400 psi at a pressure generation temperature that is below the boiling point of water, (b) has a boiling point which is below the freezing point of water, and (c) has a critical temperature which is above that of the pressure generation temperature. Preferably, the first liquid heat transfer medium comprises a fluorocarbon mixture that (a) generates a high pressure of at least 500 psi at a pressure generation temperature that is below 190° F., (b) has a boiling point which is at least 10° F. below the freezing point of water, and (c) has a critical temperature which is above 150° F.
The heating step advantageously comprises heating a second liquid heat transfer medium which is different from the first heat transfer medium and utilizing the heated second heat transfer medium to heat and vaporize the first heat transfer medium. The second heat transfer medium is preferably heated to a temperature of less than 200° F. by nuclear energy, solar energy, electric energy, or combustion of fossil fuels, natural or synthetic gases, alcohol, or vegetable or plant material. The heated second medium is passed through heat exchanger tubes which are in contact with and heat the first medium.
The vapor utilizing step comprises passing the vapor through a turbine to rotate a shaft for generation of power or torque. The rotating shaft may be operatively associated with vehicle wheels to provide motion to the vehicle. When arranged in this manner, the vapor pressure passing through the turbine can be reversed to provide braking to the wheels and vehicle.
Alternatively, the vapor utilizing step may include utilizing the pressure of the vapor to operate one or a plurality of pistons in an engine to generate horsepower. The engine may be located on a boat or ship and is operatively associated with a propeller or blade to provide marine propulsion. Also, the vapor utilizing step may comprise passing the vapor through a turbine of an aircraft engine to provide flight propulsion.
The vapor may be condensed in an air cooled condenser, or in a heat exchanger where heat is recovered from the vapor and utilized elsewhere. If desired, the movement of the first heat transfer medium in the circuit can be assisted by pumping it from the vapor utilizing step to the condensing step. In addition, valving can be included to assist in movement of the medium.
The invention also relates to an apparatus for efficiently generating power or torque which comprises a closed loop heat transfer medium system comprising a first heat exchanger for heating a vaporizable, first liquid heat transfer medium to generate a high pressure vapor; a mechanical device which utilizes the high pressure vapor to provide mechanical energy; a condenser for condensing the vapor to a liquid; and piping for fluidly connecting the first heat exchanger, mechanical device and condenser, as well as for recycling the condensed liquid to the first heat exchanger for re-use.
The first heat exchanger has exchanger tubes that include therein a second liquid heat transfer medium which is different from the first heat transfer medium, and the apparatus further comprises a second heat exchanger for heating second heat transfer medium, wherein the heated second heat transfer medium is passed through the exchanger tubes of the first heat exchanger to heat and vaporize the first heat transfer medium. The second heat transfer medium is heated to a temperature of less than 200° F. by a heating device that is powered by nuclear energy, solar energy, electric energy, or combustion of fossil fuels, alcohol, or vegetable or plant material.
The first heat transfer medium is generally maintained in a hermetically sealed circuit so that essentially no loss of heat transfer medium occurs during the heating and condensing steps. Also, the mechanical device may be a turbine that rotates a shaft for generation of power or torque, or an engine that includes one or more pistons with the pressure of the vapor utilized to operate
Nguyen Hoang
Winston & Strawn
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