Carbon dioxide refrigeration cycle

• US 9,062,898 B2
• Filed: 10/03/2012
• Issued: 06/23/2015
• Est. Priority Date: 10/03/2011
• Status: Expired due to Fees

• Current Assignee: Echogen Power Systems, LLC
• Original Assignee: Echogen Power Systems, LLC
• Inventors: Held, Timothy James, Vermeersch, Michael Louis, Xie, Tao
• Primary Examiner(s): Bauer, Cassey D
• Application Number:
  US13/644,177
• Publication Number:
  US 20140090405A1
• Time in Patent Office: 993 Days
• US Class Current: 1/1
• CPC Class Codes: F01K 25/10 the vapours being cold, e.g. ammonia, carbon dioxide, ether
• CPC Class Codes: F01K 25/103 Carbon dioxide F01K25/065 takes precedence
• CPC Class Codes: F25B 1/06 with compressor of jet type, e.g. using liquid under pressure F25B1/005, F25B1/10 take precedence
• CPC Class Codes: F25B 2400/141 the extracted power is not recycled back in the refrigerant circuit
• CPC Class Codes: F25B 9/008 the refrigerant being carbon dioxide
• CPC Class Codes: Y02P 80/15 On-site combined power, heat or cool generation or distribution, e.g. combined heat and power [CHP] supply

Abstract

A refrigeration cycle is operated in conjunction with various thermodynamic cycle working fluid circuits to cool a target fluid that may be used in a separate system or duty. In one embodiment, the refrigeration cycle includes an ejector that extracts a motive fluid from the working fluid cycles in order to entrain a suction fluid that is also extracted from the working fluid circuits. Expanding the suction fluid reduces the pressure and temperature of the suction fluid for cooling the target fluid in an evaporator, which evaporates the suction fluid before being entrained into the ejector by the motive fluid. A mixed fluid is discharged from the ejector and injected into the working fluid circuits upstream from a condenser that cools the mixed fluid and the working fluid circulating throughout the working fluid circuits.

Claims

1. A working fluid circuit for converting thermal energy into mechanical energy, comprising:

a pump configured to circulate a working fluid through the working fluid circuit;

a heat exchanger in fluid communication with the pump and in thermal communication with a heat source, the heat exchanger being configured to transfer thermal energy from the heat source to the working fluid;

a condenser fluidly coupled to the pump and configured to cool the working fluid before returning the working fluid to the pump for recirculation;

an ejector fluidly coupled to the heat exchanger and configured to receive a motive fluid and a suction fluid, the motive fluid being a portion of the working fluid discharged from the heat exchanger and the suction fluid being a portion of the working fluid discharged from the condenser, wherein the ejector discharges a mixed fluid into or adjacent an inlet of the condenser;

an expansion valve fluidly coupled to the condenser and configured to receive and expand the suction fluid; and

an evaporator in fluid communication with the expansion valve and having a target fluid circulating therein, the evaporator configured to transfer thermal energy from the target fluid to the suction fluid while cooling the target fluid.

2. The working fluid circuit of claim 1, wherein the working fluid comprises carbon dioxide.

3. The working fluid circuit of claim 1, wherein the heat source comprises a waste heat source.

4. The working fluid circuit of claim 1, wherein the target fluid originates from an upstream source used primarily to cool the working fluid in the condenser.

5. The working fluid circuit of claim 4, wherein the upstream source comprises water.

6. The working fluid circuit of claim 4, wherein the upstream source is in a liquid state or a gas state.

7. The working fluid circuit of claim 1, further comprising:

an expansion device fluidly coupled to the heat exchanger for expanding the working fluid discharged from the heat exchanger; and

a recuperator fluidly coupled to the expansion device and configured to transfer thermal energy from the working fluid discharged from the expansion device to the working fluid discharged from the pump.

8. The working fluid circuit of claim 1, further comprising a first mass flow of the working fluid separated from a second mass flow of the working fluid within the working fluid circuit, the heat exchanger receiving the first mass flow and the working fluid circuit further comprising:

a first expansion device fluidly coupled to the heat exchanger and configured to receive and expand the first mass flow discharged from the heat exchanger;

a first recuperator fluidly coupled to the first expansion device and configured to receive the first mass flow discharged from the first expansion device and transfer residual thermal energy from the first mass flow to the second mass flow;

a second expansion device in fluid communication with the first recuperator and configured to receive and expand the second mass flow; and

a second recuperator fluidly coupled to the second expansion device and configured to receive the second mass flow discharged from the second expansion device.

9. The working fluid circuit of claim 1, further comprising a first mass flow of the working fluid separated from a second mass flow of the working fluid within the working fluid circuit, wherein the heat exchanger is a first heat exchanger configured to receive and transfer thermal energy to the first mass flow, the working fluid circuit further comprising:

a first expansion device fluidly coupled to the first heat exchanger and configured to expand the first mass flow;

a first recuperator fluidly coupled to the first expansion device and configured to transfer residual thermal energy from the first mass flow discharged from the first expansion device to the first mass flow directed to the first heat exchanger;

a second heat exchanger fluidly coupled to the pump and in thermal communication with the heat source, the second heat exchanger being configured to receive the second mass flow and transfer thermal energy from the heat source to the second mass flow, wherein the first and second heat exchangers are arranged in series in the heat source, but the first mass flow circulates in parallel with the second mass flow; and

a second expansion device fluidly coupled to the second heat exchanger and configured to expand the second mass flow.

10. The working fluid circuit of claim 9, further comprising:

a second recuperator fluidly coupled to the second expansion device and configured to transfer residual thermal energy from the combined mass flow to the second mass flow directed to the second heat exchanger; and

a third heat exchanger in thermal communication with the heat source and arranged between the pump and the first heat exchanger, the third heat exchanger being configured to receive and transfer thermal energy to the first mass flow prior to the first mass flow passing through the first heat exchanger, wherein the first, second, and third heat exchangers are arranged in series in the heat source.

11. The working fluid circuit of claim 10, further comprising a third recuperator arranged between the pump and the third heat exchanger, the third recuperator being configured to transfer residual heat from the combined mass flow discharged from the second recuperator to the first mass flow directed to the third heat exchanger.

12. A method for cooling a target fluid, comprising:

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

heating the working fluid in a heat exchanger arranged in the working fluid circuit in fluid communication with the pump, wherein the heat exchanger is configured to be in thermal communication with a waste heat source;

cooling the working fluid with a condenser arranged in the working fluid circuit upstream from and fluidly coupled to the pump;

extracting a portion of the working fluid discharged from the heat exchanger to be used as a motive fluid in an ejector, the ejector being fluidly coupled to the heat exchanger;

extracting a portion of the working fluid discharged from the condenser to be used as a suction fluid in the ejector;

expanding the suction fluid in an expansion valve to generate a cooled suction fluid, the expansion valve being fluidly coupled to the condenser; and

cooling the target fluid with the cooled suction fluid in an evaporator fluidly coupled to the expansion valve.

13. The method of claim 12, further comprising:

entraining the suction fluid discharged from the evaporator into the ejector;

discharging a mixed fluid from the ejector; and

introducing the mixed fluid into or adjacent an inlet of the condenser.

14. The method of claim 12, further comprising extracting the target fluid from an upstream source, where the upstream source provides a coolant.

15. The method of claim 14, further comprising cooling the working fluid in the condenser with the coolant from the upstream source.

16. A refrigeration cycle, comprising:

an ejector fluidly coupled to a heat exchanger arranged in a working fluid circuit and configured to receive a motive fluid from the heat exchanger, wherein the heat exchanger is configured to transfer thermal energy from a waste heat source to a working fluid comprising carbon dioxide circulating throughout the working fluid circuit, wherein the motive fluid is a portion of the working fluid discharged from the heat exchanger;

a condenser arranged in the working fluid circuit and fluidly coupled to a discharge of the ejector, the condenser being configured cool the working fluid in the working fluid circuit and simultaneously cool a mixed fluid discharged from the ejector;

an expansion valve fluidly coupled to the condenser and configured to receive and expand a suction fluid to generate a cooled suction fluid, the suction fluid being a portion of the working fluid discharged from the condenser and subsequently entrained into the ejector to form part of the mixed fluid;

an evaporator in fluid communication with the expansion valve and having a target fluid circulating therein, the evaporator being configured to transfer thermal energy from the target fluid to the suction fluid such that the target fluid is cooled and the suction fluid evaporates; and

an upstream source fluidly coupled to the evaporator and providing the target fluid to the evaporator.

17. The refrigeration cycle of claim 16, wherein the expansion valve is a turbine.

18. The refrigeration cycle of claim 16, wherein the upstream source comprises water and is operable to cool the working fluid and the mixed fluid in the condenser.

19. The refrigeration cycle of claim 16, wherein the upstream source is in a liquid state or a gas state.

20. The refrigeration cycle of claim 16, wherein the target fluid is used in a separate system of duty after being cooled in the evaporator.