METHOD AND SYSTEM FOR EVALUATING THE EFFICIENCY OF AN AIR CONDITIONING APPARATUS

• US 20080114569A1
• Filed: 01/18/2008
• Published: 05/15/2008
• Est. Priority Date: 05/15/2001
• Status: Active Grant

• Current Assignee: Chillergy Systems, LLC
• Original Assignee: Chillergy Systems, LLC
• Inventors: Seigel, Lawrence
• Granted Patent: US 7,945,423 B2
• Time in Patent Office: Days
• US Class Current: 702/182
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/47 Responding to energy costs

Abstract

The applicant describes a system and methods of calculating the overall operating efficiency of an air conditioning chiller that evaluates efficiency of the component parts of the chiller and generates an overall efficiency based on these component efficiency values. If the overall chiller efficiency is less than the maximum attainable chiller efficiency, the cost of the inefficiency is calculated and presented to the user. Recommendations for corrective action to restore maximum chiller efficiency are identified and presented to the user. The system also adjusts the efficiency calculations as appropriate to account for actual compressor current load conditions.

Claims

1. A method for evaluating the performance of an air conditioning chiller having a compressor and a plurality of components including a condenser and an evaporator, comprising the steps of:

A. receiving performance data for the compressor and each of the plurality of components;

B. for each of the plurality of components, calculating a component loss value using at least one of a plurality of relationships correlating performance data with an efficiency loss;

C. calculating a chiller loss value based upon a plurality of the component loss values.

2. The method of claim 1, further comprising the step of:

D. identifying at least one of the plurality of components that is reducing the efficiency of the air conditioning chiller.

3. The method of claim 2, further comprising the step of:

E. identifying at least one potential cause of the reduction in the efficiency of the air conditioning chiller identified in step D.

4. The method of claim 3, further comprising the step of:

F. identifying a potential solution to the at least one potential cause of the reduction in efficiency of the air conditioning chiller identified in step E.

5. The method of claim 1, further comprising the step of:

D. performing steps A-C for a second air conditioning chiller that along with the air conditioning chiller defines a group of two or more monitored chillers.

6. The method of claim 1, further comprising the step of:

D. calculating an energy cost based on the chiller loss value calculated in step C.

7. The method of claim 1, further comprising the step of:

D. determining for each of the plurality of components whether that component has an adverse effect upon air conditioning chiller efficiency by comparing the component loss value for that component to a component loss threshold value associated with that component.

8. The method of claim 1, further comprising the step of:

D. receiving a full load current of the compressor and a running current of the compressor;

E. receiving information sufficient to define an expected evaporator approach; and

in which the performance data for the evaporator comprises;

i. an evaporator refrigerant temperature,

ii. an evaporator outlet temperature; and

in which step B further comprises, calculating the component loss value for the evaporator by performing steps comprising;

i. calculating a fractional current by dividing the running current of the compressor by a full load current of the compressor,

ii. calculating a full load evaporator approach by subtracting the evaporator refrigerant temperature from the evaporator outlet temperature and dividing the result by the fractional current,

iii. if the full load evaporator approach is greater than the expected evaporator approach, calculating an evaporator approach difference by subtracting the expected evaporator approach from the full load evaporator approach, and

iv. multiplying the evaporator approach difference by an evaporator approach loss factor to result in the component loss value for the evaporator.

9. The method of claim 8, in which the expected condenser approach is selected from the group consisting of:

an estimated evaporator approach based on when the chiller was made and an optimal evaporator approach.

10. The method of claim 1, further comprising the step of:

D. receiving information sufficient to define an optimal condenser pressure and;

in which the performance data for the condenser comprises a condenser pressure; and

in which step B further comprises, calculating the component loss value for the condenser by subtracting the optimal condenser pressure from the condenser pressure and multiplying the result by a non-condensables constant based upon the type of refrigerant used in the air conditioning chiller and the units in which condenser pressure is received.

11. The method of claim 1, further comprising the step of:

D. receiving information sufficient to define an optimal condenser pressure drop and;

in which the performance data for the condenser comprises;

i. an condenser inlet water pressure,

ii. an condenser outlet water pressure,

iii. an condenser inlet water temperature,

iv. an condenser outlet water temperature, and

in which step B further comprises, calculating the component loss value for the condenser by;

i. subtracting condenser outlet water pressure from the condenser inlet water pressure to define an actual condenser water pressure difference,

ii. taking the square root of the ratio of the actual condenser water pressure difference to the optimal condenser water pressure drop to define a delta variance,

iii. subtracting the condenser inlet water temperature from the condenser outlet water temperature to define a condenser water temperature difference,

iv. subtracting delta variance from one and multiplying the result by the condenser water temperature difference to define a final variance,

v. multiplying the final variance by a condenser flow loss factor to result in the component loss value for the condenser.

12. The method of claim 1, further comprising the step of:

D. receiving a full load current of the compressor, a running current of the compressor, and an optimal evaporator approach; and

in which the performance data for the evaporator comprises;

i. an evaporator refrigerant temperature,

ii. a chill water outlet temperature,

in which step B further comprises, calculating the component loss value for the evaporator by performing steps comprising;

i. calculating a fractional current by dividing the running current of the compressor by a full load current of the compressor,

ii. calculating a full load evaporator approach by subtracting the evaporator refrigerant temperature from the chill water outlet temperature and dividing the result by the fractional current,

iii. if the full load evaporator approach is greater than the optimal evaporator approach, calculating a evaporator approach difference by subtracting the optimal evaporator approach from the full load evaporator approach, and

iv. multiplying the evaporator approach difference by a evaporator approach loss factor to result in the component loss value for the evaporator.

13. The method of claim 1, further comprising the step of reading instruments measuring condenser parameters and in which:

the receiving step comprises receiving the performance data for the condenser based upon the condenser parameters; and

steps B and C are performed by the computing device.

14. The method of claim 1, further comprising the step of reading instruments measuring condenser parameters and in which the receiving step comprises receiving by a portable handheld device the performance data for the condenser based upon the condenser parameters, and further comprising the step of:

D. sending the performance data for the condenser to a computing device that performs steps B and C.

15. The method of claim 1, further comprising the steps of:

D. reading with a portable handheld device the performance data for the condenser from a plurality of sensors that measure at least one condenser parameter, and

E. sending the performance data for the condenser to a computing device; and

in which steps B and C are performed by the computing device.

i. a portable handheld device reading the performance data for the condenser from a plurality of sensors that measure at least one condenser parameter,

ii. sending the performance data for the condenser to a computing device that performs steps B and C.

16. A method of evaluating the performance of an evaporator of an air conditioning chiller having an evaporator, comprising the steps of:

A. receiving chiller data, comprising;

i. an expected evaporator approach,

ii. a compressor running current,

iii. a full load compressor current,

iv. an evaporator refrigerant temperature, and

v. an evaporator outlet temperature;

B. determining an evaporator loss value by calculating;

i. a fractional current by dividing the compressor running current by the full load compressor current,

ii. a full load evaporator approach by subtracting the evaporator refrigerant temperature from the evaporator outlet temperature and dividing the result by the fractional current,

iii. an evaporator approach difference if the full load evaporator approach is greater than the expected evaporator approach by subtracting the expected evaporator approach from the full load evaporator approach, and

iv. multiplying the evaporator approach difference by an evaporator approach loss factor to result in the evaporator loss value.

17. The method of claim 16, in which the expected evaporator approach is selected from the group consisting of:

an estimated evaporator approach based on when the chiller was made and an optimal evaporator approach.

18. The method of claim 16, further comprising the step of:

C. determining whether the evaporator loss value represents a significant reduction in the efficiency of the air conditioning chiller by comparing the evaporator loss value to a evaporator loss threshold value.

19. The method of claim 16, further comprising the step of:

C. calculating an energy cost based on the evaporator loss value determined in step B.

20. One or more computer-readable media containing instructions that when executed by a computer perform the method of claim 16.