Supercritical pressure regulation of vapor compression system by regulation of adaptive control

• US 6,813,895 B2
• Filed: 09/05/2003
• Issued: 11/09/2004
• Est. Priority Date: 09/05/2003
• Status: Expired due to Term

• Current Assignee: Carrier Corporation (Carrier Global Corporation)
• Original Assignee: Carrier Corporation (Carrier Global Corporation)
• Inventors: Kang, Pengju, Eisenhower, Bryan, Sienel, Tobias, Finn, Alan, Park, Christopher G.
• Primary Examiner(s): Tapolcai, William E.
• Application Number:
  US10/655,970
• Publication Number:
  US 20040050080A1
• Time in Patent Office: 431 Days
• Field of Search: 621/15, 621/763, 622/26, 622/281, 622/285
• US Class Current: 62/115
• CPC Class Codes: C08F 2/46 Polymerisation initiated by wave energy or particle radiation
• CPC Class Codes: C09J 4/00 Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
• CPC Class Codes: F25B 2309/061 with cycle highest pressure above the supercritical pressure
• CPC Class Codes: F25B 2600/17 by controlling the pressure of the condenser
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems
• CPC Class Codes: F25B 9/008 the refrigerant being carbon dioxide
• CPC Class Codes: G05D 16/2066 using controlling means acting on the pressure source

Abstract

A vapor compression system includes a compressor, a gas cooler, an expansion device, and an evaporator. Refrigerant is circulated through the closed circuit cycle. Preferably, carbon dioxide is used as the refrigerant. Adaptive control is employed to optimize the coefficient of performance of the vapor compression system. As the system changes over time, a model that operates the system is modified. The model is determined by an adaptive control algorithm including variable coefficients. As the model changes, the variables of the adaptive control algorithm change. A control of the gas cooler is then adjusted to regulate the high pressure of the system, and therefore the coefficient of performance. In a first example, Least Mean Squares (LMS) is used to modify the variables of the adaptive control algorithm to optimize the coefficient of performance. In a second example, the coefficient of performance is optimized by a slowly varying periodic excitation method. A third example employs triangularization to find the optimal coefficient of performance.

Claims

1. A method of regulating high pressure of A transcritical vapor compression system comprising the steps of:

operating the system base on a model, and an adaptive control algorithm having variable coefficients operates the model;

exciting the system with an excitation signal to generate a system output;

comparing the system output to a model output of the model; and

adapting the model to obtain a desired high pressure of the system by modifying the variable coefficients such that the model output of the model substantially equals the system output of the system.

2. The method as recited in claim 1, further comprising the steps of:

compressing a refrigerant to the high pressure;

cooling the refrigerant;

expanding the refrigerant; and

evaporating the refrigerant.

3. The method as recited in claim 2 further comprising the steps of:

controlling a flow of the refrigerant through the step of cooling; and

adjusting the step of controlling to obtain the desired high pressure.

4. The method as recited in claim 2 wherein the refrigerant is carbon dioxide.

5. The method as recited in claim 1 wherein the desired high pressure obtains a maximum coefficient of performance.

6. The method as recited in claim 1 wherein the step of comparing determines a system identification error.

7. The method as recited in claim 6 wherein the step of adapting utilizes the system identification error.

8. A method of regulating a high pressure of a transcritical vapor compression system comprising the steps of;

operating the system base on a model; and

adapting the model to obtain a desired high pressure of the system, wherein the step of adapting further includes the steps of;

1) sinusoidally exciting the system with an exciation signal to generate a response;

2) filtering the response to generate a harmonic response;

3) multiplying the harmonic response by the excitation signal to demodulate the harmonic response to a demodulated harmonic response;

4) filtering an oscillation factor from the demodulated harmonic response to separate a static gain; and

5) utilizing the static gain as a new excitation signal.

10. The method as recited in claim 8 further comprising the steps of:

compressing a refrigerant to the high pressure;

cooling the refrigerant;

expanding the refrigerant; and

evaporating the refrigerant.

11. The method as recited in claim 10 further comprising the steps of:

controlling a flow of the refrigerant through the step of cooling; and

adjusting the step of controlling to obtain the desired high pressure.

12. The method as recited in claim 10 wherein the refrigerant is carbon dioxide.

13. The method as recited in claim 8 wherein the desired high pressure obtains a maximum coefficient of performance.

14. The method as recited in claim 8 further comprising the step of repeating steps 1) to 5) utilizing the new excitation signal as the excitation signal.

9. A method of regulating high pressure of a transcritical vapor compression system comprising the steps of:

operating the system base on a model; and

adapting the model to obtain a desired high pressure of the system, wherein the step of adapting further includes the steps of;

1) establishing a left input point, a right input point, and a middle input point therebetween;

2) determining a coefficient of performance for each of the left input point, the right input point, and the middle input point;

3) determining a left middle coefficient of performance of a left middle input point between the left input point and the middle input point and determining a right middle coefficient of performance of a right middle input point between the right input point and the middle input point;

4) comparing the left middle coefficient of performance and the right middle coefficient of performance;

5) determining which of the left middle coefficient of performance and the right middle coefficient of performance is a greater value;

6) determining a new middle input point that corresponds to the greater value; and

7) repeating step

     1) to step

     6) employing the new middle input point as the middle input point.

15. The method as recited in claim 9 further comprising the steps of:

compressing a refrigerant to the high pressure;

cooling the refrigerant;

expanding the refrigerant; and

evaporating the refrigerant.

16. The method as recited in claim 15 further comprising the steps of:

controlling a flow of the refrigerant through the step of cooling; and

adjusting the step of controlling to obtain the desired high pressure.

17. The method as recited in claim 15 wherein the refrigerant is carbon dioxide.

18. The method as recited in claim 9 wherein the desired high pressure obtains a maximum coefficient of performance.

19. The method as recited in claim 9 wherein the step of repeating utilizes the middle input point as the left input point if the right middle coefficient of performance is the greater value, and the step of repeating utilizes the middle input point as the right input point if the left middle coefficient of performance is the greater value.

20. A method of regulating a high pressure of a transcritical vapor compression system comprising the steps of:

compressing a refrigerant to the high pressure;

cooling the refrigerant with a fluid;

expanding the refrigerant;

evaporating the refrigerant;

operating the system based on a model;

adapting the model to obtain a desired high pressure of the transcritical vapor compression system;

exciting the system with an excitation signal to generate a system output;

comparing the system output to a model output of the model; and

adjusting the high pressure of the system by adjusting a flow rate of the fluid in the step of cooling based on the step of comparing.