Energy conversion method and system with enhanced heat engine

• US 20030074900A1
• Filed: 10/18/2002
• Published: 04/24/2003
• Est. Priority Date: 10/24/2001
• Status: Active Grant

• Current Assignee: Rory S. Mcfarland
• Original Assignee: Rory S. Mcfarland
• Inventors: McFarland, Rory S.
• Granted Patent: US 6,606,860 B2
• Time in Patent Office: Days
• US Class Current: 60/670
• CPC Class Codes: F01K 25/10 the vapours being cold, e.g. ammonia, carbon dioxide, ether
• CPC Class Codes: F02C 1/10 Closed cycles

Abstract

An energy conversion device for converting heat to mechanical energy. The apparatus includes a heat exchanger vessel absorbing heat from an ambient or energy-rich fluid and transferring heat to a working fluid within an interior chamber of the vessel containing pressurized working gas. An isolation vessel is positioned within the interior chamber, with a gas flow loop defined between the two vessels through which the working gas flows. The isolation vessel is insulated to create a temperature differential and is pressure resistant to allow low pressures in the interior chamber to be maintained. A compressor is positioned within the isolation vessel to compress and discharge the gas into the gas flow loop. An expander is placed in the isolation vessel for converting energy of the expanding gas into a mechanical energy and for rarefying the expanded gas prior to discharge to create a lower bottom temperature or cold reservoir.

Claims

1. An apparatus for efficiently converting heat to mechanical energy, comprising:

a heat exchanger vessel configured for resisting a high working fluid pressure developed within the vessel and for transferring heat into an interior chamber of the heat exchanger vessel;

an isolation vessel positioned within the interior chamber of the heat exchanger vessel, the isolation vessel including an outer wall that thermally isolates a volume interior to the outer wall and maintains a pressure differential between the interior volume and other portions of the interior chamber of the heat exchanger vessel;

a working gas flow loop defined in the interior chamber by an exterior surface of the isolation vessel and an interior surface of the heat exchanger vessel;

a compressor positioned at least partially in the isolation vessel with an inlet within the interior volume of the isolation vessel receiving an expanded, cooled working gas, wherein the compressor is adapted for compressing the working gas to about the high working fluid pressure and discharging the working gas through a compressor outlet to the working gas flow loop; and

an expander positioned in the isolation vessel with an inlet in the working gas flow loop receiving the working gas discharged by the compressor after the discharged working gas passes through the working gas flow loop to absorb the heat transferred through the heat exchanger vessel, wherein the expander includes means for converting energy in the received working gas to mechanical energy and includes an outlet within the interior volume of the isolation vessel for discharging the expanded, cooled working gas.

2. The apparatus of claim 1, further including a drive shaft linked to the converting energy means of the expander, the mechanical energy being used to rotate the drive shaft and further including means for exporting at least a portion of the mechanical energy rotating the drive shaft to a load external to the isolation vessel.

3. The apparatus of claim 2, wherein the exporting means comprises a generator positioned within the interior volume of the isolation vessel that is linked to the drive shaft and configured to generate electricity when the drive shaft is rotated by the expander.

4. The apparatus of claim 3, wherein the compressor is linked to the drive shaft.

5. The apparatus of claim 4, further including a first thermal partition for thermally isolating the expander from the generator and a second thermal partition thermally isolating the generator from the compressor.

6. The apparatus of claim 1, wherein the expander further includes means for rarefying the received working gas prior to discharging as the expanded, cooled working gas, thereby creating an increased temperature differential between the working gas in the working gas flow loop and the expanded, cooled working gas discharged by the expander.

7. The apparatus of claim 6, further including a condensate tank fluidically linked to the expander for collecting a portion of the received working gas that condensates prior to being discharged from the expander.

8. The apparatus of claim 7, further including a cooling system between the expander and condensate tank removing additional heat from the received working to cause the portion of the received working gas to condensate.

9. The apparatus of claim 7, further including a liquid pump connected to the condensate tank pumping the condensate through a cryogenic loop external to the isolation vessel and further including a discharge from the cryogenic loop in the working gas flow loop.

10. The apparatus of claim 1, wherein the working gas is a binary gas and further including a gas supply with an outlet within the heat exchanger vessel supplying additional volumes of the working gas to maintain a mass flow rate within the working gas flow loop.

11. The apparatus of claim 1, further including an exterior shell enclosing the heat exchanger vessel and defining a hot flow loop for passing an energy-rich fluid over the heat exchanger vessel to provide the heat for transferring into the interior chamber of the heat exchanger vessel, wherein the exterior shell further includes an inlet device for drawing the energy-rich fluid into the hot flow loop.

12. The apparatus of claim 11, wherein the inlet device comprises a compressor for compressing the energy-rich fluid drawn into the hot flow loop to a hot flow loop pressure.

13. The apparatus of claim 12, further including a cracking device at an outlet of the exterior shell including means for selectively discharging the compressed energy-rich fluid to condense a portion of the compressed energy-rich fluid prior to discharge from the exterior shell.

14. The apparatus of claim 1, further including a heat input device in the working gas flow loop for inputting a quantity of heat from a source external to the heat exchanger vessel to the working gas discharged by the compressor.

15. The apparatus of claim 1, further including a motor powered by a source external to the heat exchanger vessel linked to the expander and the compressor to operate the expander and the compressor to develop desired pressure and temperature differentials between the working gas flow loop and the interior volume of the isolation vessel.

16. The apparatus of claim 1, further including a secondary energy conversion device positioned within the isolation vessel including:

a secondary heat exchanger vessel configured for resisting a high working fluid pressure developed within the secondary vessel and for transferring heat into an interior chamber of the secondary vessel from the discharged cooled working gas from the expander;

a secondary isolation vessel positioned within the interior chamber of the secondary vessel, the secondary isolation vessel including an outer wall that thermally isolates a volume interior to the outer wall and maintains a pressure differential between the interior volume and other portions of the interior chamber of the secondary vessel;

a secondary working gas flow loop defined in the interior chamber by an exterior surface of the secondary isolation vessel and an interior surface of the secondary vessel;

a secondary compressor positioned at least partially in the secondary isolation vessel with an inlet within the interior volume of the secondary isolation vessel receiving a secondary expanded, cooled working gas differing from the working gas in the expander, wherein the secondary compressor is adapted for compressing the secondary working gas to about the high working fluid pressure and discharging the secondary working gas through a compressor outlet to the secondary working gas flow loop; and

a secondary expander positioned in the secondary isolation vessel with an inlet in the secondary working gas flow loop receiving the secondary working gas discharged by the secondary compressor after the discharged secondary working gas passes through the secondary working gas flow loop to absorb the heat transferred through the secondary vessel, wherein the secondary expander includes means for converting energy in the received secondary working gas to mechanical energy and includes an outlet within the interior volume of the secondary isolation vessel for discharging the expanded, cooled working gas.

17. A method for converting a low grade energy to a high grade energy, comprising:

increasing a pressure of a working gas in a cold side of a heat exchanger to a working pressure, wherein the working gas is at a cold side temperature;

passing a fluid with a hot side temperature greater than the cold side temperature through a hot side of the heat exchanger, wherein the hot side and cold side are in heat transfer contact such that the passing causes a quantity of heat to be transferred to the working gas in the cold side;

inputting the working gas in the cold side of the heat exchanger into a chamber having a pressure lower than the working pressure and a temperature lower than the cold side temperature;

expanding the input working gas to convert heat in the input working gas into mechanical energy; and

exporting a portion of the mechanical energy to a load outside the lower pressure, lower temperature chamber.

18. The method of claim 17, further including after the expanding, rarefying the expanded working gas to remove an additional quantity of the heat in the input working gas to lower the chamber temperature and create a cold reservoir.

19. The method of claim 17, further including chilling the expanded working gas to form a condensate, pumping the condensate through a loop outside the lower pressure, lower temperature chamber wherein the condensate is heated, and injecting the heated condensate into the cold side of the heat exchanger.

20. The method of claim 17, wherein the mechanical energy created in the expanding rotates a drive shaft and the exporting includes operating a generator with the drive shaft to generate electricity and transmitting a portion of the generated electricity to the load.

21. The method of claim 17, wherein the pressure increasing comprises operating a compressor positioned within the lower pressure, lower temperature chamber to compress the expanded working gas and to discharge the compressed working gas into the cold side of the heat exchanger.

22. The method of claim 17, wherein the fluid passing includes collecting exhaust fluids from a heat-generating process and then directing the exhaust fluids through the hot side of the heat exchanger.

23. The method of claim 17, wherein the pressure increasing includes inputting energy into the lower pressure, lower temperature chamber to operate a heat engine to perform the expanding and to operate a compressor to compress the expanded working gas discharged from the heat engine to the working pressure until a desired differential is achieved between the cold side temperature and the hot side temperature.

24. An energy conversion system, comprising:

an outer tank defining an inner chamber with a cold side loop of a heat exchanger, wherein the outer tank is sealed to maintain a working gas in the cold side loop at a working pressure and is thermally insulated;

an expander positioned within the inner chamber with an inlet for receiving the working gas after the working gas travels through the cold side loop, wherein the expander includes an expansion device for converting expansion by the received working gas into mechanical energy;

a compressor positioned within the inner chamber adjacent the expander with an inlet linked to an outlet of the expander for receiving expanded working gas from the expander, wherein the compressor functions to compress the expanded working gas to about the working pressure and to discharge the compressed working gas into the cold side loop; and

a heat source system having a hot side loop positioned within the cold side loop with a heat transfer device through which a hot fluid flows and having an exterior portion positioned outside the outer tank with means for transferring heat to the hot fluid.

25. The system of claim 24, wherein the hot fluid is hydraulic fluid and the heat transfer means includes loads within a hydraulic system.

26. The system of claim 24, wherein the heat transfer means includes a heat source selected from the group consisting of a geothermal heat source, a solar energy collection device, and an ambient energy source.

27. The system of claim 24, wherein the hot side loop includes a liquid pump and wherein the liquid pump is driven by a shaft rotated by the expansion device.

28. The system of claim 24, further including a refrigeration loop positioned within the cold side loop carrying refrigerant at a temperature greater than a temperature in the cold side loop of the compressed working gas, wherein the refrigerant releases energy to the compressed working gas and wherein the refrigerant loop extends out of the outer tank.

29. The system of claim 24, further including a drive shaft within the outer tank linked to the expansion device to rotate based on the generation of the mechanical energy and including a generator linked to the drive shaft to generate electricity when driven by the rotating drive shaft, wherein the generator exports at least a portion of the generated electricity to a load external to the outer shell.

30. An energy conversion mechanism, comprising:

means for isolating a set of internal components from external pressures and temperatures;

means for initially lowering the temperature of the set of internal components to create an artificial cold reservoir in the energy conversion mechanism;

means for directing a working gas at a temperature higher than the temperature of the artificial cold reservoir through the set of internal component, wherein the working gas performs work on the internal components to produce mechanical energy and to lower the temperature of the working gas;

means for converting the mechanical energy into an exportable form of energy; and

means for exporting the exportable form of energy from the isolating means.

31. The energy conversion mechanism of claim 30, wherein the exporting means is adapted to perform the exporting without transferring heat.

32. The energy conversion mechanism of claim 30, further including means for controlling a rate of the exporting performed by the exporting means, wherein the exporting rate is maintained at about a selectable steady rate.

33. A method for starting an energy conversion system, comprising:

providing an energy conversion device including an expander and a compressor, an isolation vessel enclosing the expander and the compressor, and a cold loop of a heat exchanger including an external wall, wherein the external wall is sealed to maintain a working pressure within the cold loop, the isolation vessel is constructed to isolate the expander and compressor from pressure and heat of a working gas in the cold loop;

injecting a quantity of the working gas into the cold loop to create a starting pressure in the cold loop;

importing energy into the energy conversion device to cool a chamber in the isolation vessel containing the expander to a cold reservoir temperature lower than the temperature of the working gas in the cold loop;

operating the expander to receive a portion of the working gas from the cold loop and to allow the working gas to expand to generate mechanical energy; and

using a portion of the generated mechanical energy to maintain the cold reservoir temperature.

34. The method of claim 33, wherein the energy conversion device includes a motor and generator device operable to generate electricity when run in a generate mode and to drive a shaft when run in a motor mode connected to the compressor and expander and wherein the energy importing includes providing electricity to the motor and generator device running in motor mode to drive the shaft and operate the compressor and the expander, the compressor having an inlet in communication with an outlet of the expander and an outlet in the cold loop.

35. The method of claim 34, wherein the energy importing includes operating means for rarefying the working gas received by the expander to rarefy the received working gas to the cold reservoir temperature.

36. The method of claim 34, further including switching the motor and generator device to the generate mode after the expander operating to convert the generated mechanical energy to electricity and exporting at least a portion of the generated electricity to a load outside of the isolation vessel.