Heat Engine and Heat to Electricity Systems and Methods with Working Fluid Mass Management Control

• US 20120047892A1
• Filed: 10/21/2011
• Published: 03/01/2012
• Est. Priority Date: 09/17/2009
• Status: Active Grant

• Current Assignee: Echogen Power Systems, LLC
• Original Assignee: Echogen Power Systems, LLC
• Inventors: Held, Timothy James, Hostler, Stephen, Miller, Jason D.
• Granted Patent: US 8,613,195 B2
• Time in Patent Office: Days
• US Class Current: 60/652
• CPC Class Codes: F01K 25/103 Carbon dioxide F01K25/065 takes precedence
• CPC Class Codes: F01K 3/185 using waste heat from outside the plant F02G5/00 takes precedence
• CPC Class Codes: F01K 7/08 Control means specially adapted therefor
• CPC Class Codes: F24H 2240/12 with thermodynamic cycle for converting thermal energy to mechanical power to produce electrical energy

Abstract

Various thermodynamic power-generating cycles employ a mass management system to regulate the pressure and amount of working fluid circulating throughout the working fluid circuits. The mass management systems may have a mass control tank fluidly coupled to the working fluid circuit at one or more strategically-located tie-in points. A heat exchanger coil may be used in conjunction with the mass control tank to regulate the temperature of the fluid within the mass control tank, and thereby determine whether working fluid is either extracted from or injected into the working fluid circuit. Regulating the pressure and amount of working fluid in the working fluid circuit helps selectively increase or decrease the suction pressure of the pump, which can increase system efficiency.

Claims

1. A heat engine system for converting thermal energy into mechanical energy, comprising:

a working fluid circuit that circulates a working fluid through a high pressure side and a low pressure side of the working fluid circuit, the working fluid circuit comprising;

a first heat exchanger in thermal communication with a heat source to transfer thermal energy to the working fluid;

a first expander in fluid communication with the first heat exchanger and fluidly arranged between the high and low pressure sides;

a first recuperator fluidly coupled to the first expander and configured to transfer thermal energy between the high and low pressure sides;

a cooler in fluid communication with the first recuperator and configured to control a temperature of the working fluid in the low pressure side; and

a first pump fluidly coupled to the cooler and configured to circulate the working fluid through the working fluid circuit; and

a mass management system fluidly coupled to the working fluid circuit and configured to regulate a pressure and an amount of working fluid within the working fluid circuit, the mass management system comprising;

a mass control tank fluidly coupled to the high pressure side at a first tie-in point located upstream from the first expansion device and to the low pressure side at a second tie-in point located upstream from an inlet of the pump; and

a control system communicably coupled to the working fluid circuit at a first sensor arranged before the inlet of the pump and at a second sensor arranged after an outlet of the pump, and communicably coupled to the mass control tank at a third sensor arranged either within or adjacent the mass control tank.

2. The system of claim 1, wherein the working fluid is carbon dioxide.

3. The system of claim 1, wherein the mass management system further comprises a heat exchanger coil configured to transfer heat to and from the mass control tank.

4. The system of claim 3, wherein the heat exchanger coil is disposed within the mass control tank.

5. The system of claim 4, wherein the heat exchanger coil is fluidly coupled to the cooler and uses thermal fluid derived from the cooler to heat or cool the working fluid in the mass control tank.

6. The system of claim 4, wherein the heat exchanger coil is fluidly coupled to the working fluid circuit downstream from the first pump such that the heat exchanger coil uses the working fluid discharged from the pump to heat or cool the working fluid in the mass control tank.

7. The system of claim 1, further comprising:

a first valve arranged between the mass control tank and the first tie-in point; and

a second valve arranged between the mass control tank and the second tie-in point.

8. The system of claim 7, wherein the control system is operatively coupled to and able to selectively actuate the first and second valves in response to operating parameters derived from the first, second, and third sensors.

9. The system of claim 7, wherein the mass control tank is further fluidly coupled to the high pressure side of the working fluid circuit at a third tie-in point arranged downstream from the pump, a third valve being arranged between the mass control tank and the third tie-in point, wherein the control system is operatively coupled to and able to selectively actuate the third valve in response to operating parameters derived from the first, second, and/or third sensors.

10. The system of claim 1, wherein the mass management system further comprises a transfer pump arranged between the mass control tank and the second tie-in point, the transfer pump being configured to pump working fluid from the mass control tank and into the working fluid circuit via the second tie-in point.

11. The system of claim 1, wherein the mass management system further comprises a vapor compression refrigeration cycle having a vapor compressor and condenser fluidly coupled to the mass control tank.

12. The system of claim 1, wherein the mass management system further comprises an external heater communicable with the mass control tank to transfer thermal energy thereto.

13. A method for regulating a pressure and an amount of a working fluid in a thermodynamic cycle, comprising:

placing a thermal energy source in thermal communication with a heat exchanger arranged within a working fluid circuit, the working fluid circuit having a high pressure side and a low pressure side;

circulating the working fluid through the working fluid circuit with a pump;

expanding the working fluid in an expander to generate mechanical energy;

sensing operating parameters of the working fluid circuit with first and second sensor sets communicably coupled to a control system, the first sensor set being configured to sense at least one of a pressure and a temperature proximate an inlet of the pump and the second sensor set being configured to sense at least one of the pressure and the temperature proximate an outlet of the pump;

extracting working fluid from the working fluid circuit at a first tie-in point arranged upstream from the expander in the high pressure side, the first tie-in point being fluidly coupled to a mass control tank; and

injecting working fluid from the mass control tank into the working fluid circuit via a second tie-in point arranged upstream from an inlet of the pump to increase a suction pressure of the pump.

14. The method of claim 13, further comprising extracting additional working fluid from the working fluid circuit at a third tie-in point arranged between the pump and the heat exchanger.

15. The method of claim 13, wherein injecting working fluid from the mass control tank into the working fluid circuit via the second tie-in point further comprises pumping the working fluid into the working fluid circuit with a transfer pump arranged between the second tie-in point and the mass control tank.

16. The method of claim 13, further comprising sensing operating parameters of the mass control tank with a third sensor set configured to sense at least one of the pressure and the temperature either within or adjacent the mass control tank and being communicably coupled to the control system.

17. The method of claim 13, further comprising cooling the working fluid within the mass control tank with a vapor compression refrigeration cycle having a vapor compressor and condenser fluidly coupled to the mass control tank.

18. The method of claim 13, further comprising heating the working fluid within the mass control tank with an external heater in communication with the mass control tank.

19. A method for regulating a pressure and an amount of a working fluid in a thermodynamic cycle, comprising:

placing a thermal energy source in thermal communication with a heat exchanger arranged within a working fluid circuit, the working fluid circuit having a high pressure side and a low pressure side;

circulating the working fluid through the working fluid circuit with a pump;

expanding the working fluid in an expander to generate mechanical energy;

extracting working fluid from the working fluid circuit and into a mass control tank by transferring thermal energy from working fluid in the mass control tank to a heat exchanger coil, the working fluid being extracted from the working fluid circuit at a first tie-in point arranged upstream from the expander in the high pressure side and being fluidly coupled to the mass control tank; and

injecting working fluid from the mass control tank to the working fluid circuit via the first tie-in point by transferring thermal energy from the heat exchanger coil to the working fluid in the mass control tank.

20. The method of claim 19, further comprising circulating a thermal fluid through the heat exchanger coil to transfer thermal energy to or from the working fluid in the mass control tank, the thermal fluid being extracted from a cooler arranged in the working fluid circuit upstream from the pump.

21. The method of claim 19, further comprising circulating a portion of the working fluid in the working fluid circuit through the heat exchanger coil to transfer thermal energy to or from the working fluid in the mass control tank, the portion of the working fluid being extracted from the working fluid circuit at a point downstream from the pump.

22. A mass management system, comprising:

a mass control tank fluidly coupled to a low pressure side of a working fluid circuit that has a pump configured to circulate a working fluid throughout the working fluid circuit, the mass control tank being coupled to the low pressure side at a tie-in point located upstream from an inlet of the pump;

a heat exchanger configured to transfer heat to and from the mass control tank to either draw in working fluid from the working fluid circuit and to the mass control tank via the tie-in point or inject working fluid into the working fluid circuit from the mass control tank via the tie-in point; and

a control system communicably coupled to the working fluid circuit at a first sensor set arranged adjacent the inlet of the pump and a second sensor set arranged adjacent an outlet of the pump, and communicably coupled to the mass control tank at a third sensor set arranged either within or adjacent the mass control tank.

23. The system of claim 22, wherein the heat exchanger is a heat exchanger coil disposed within the mass control tank.

24. The system of claim 23, wherein the heat exchanger coil is fluidly coupled to a cooler arranged within the working fluid circuit, the heat exchanger coil using thermal fluid derived from the cooler to heat or cool the working fluid in the mass control tank.

25. The system of claim 23, wherein the heat exchanger coil is fluidly coupled to the working fluid circuit downstream from the pump, the heat exchanger coil using a portion of the working fluid discharged from the pump to heat or cool the working fluid in the mass control tank.

26. The system of claim 23, wherein operation of the heat exchanger coil is determined by the control system in response to operational parameters sensed by the first, second, and/or third sensor sets.

27. The system of claim 26, wherein the control system is operatively coupled to and able to selectively control an output of the heat exchanger coil in response to operating parameters derived from the first, second, and third sensor sets