Control of cooling towers for chilled fluid systems

• US 8,473,080 B2
• Filed: 05/10/2010
• Issued: 06/25/2013
• Est. Priority Date: 05/10/2010
• Status: Active Grant

• Current Assignee: Tyco Fire & Security GmbH (Johnson Controls International plc)
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Seem, John E., Li, Yaoyu
• Primary Examiner(s): Bahta, Kidest
• Application Number:
  US12/777,097
• Publication Number:
  US 20110276182A1
• Time in Patent Office: 1,142 Days
• Field of Search: 700/28, 700/37, 700/276, 700/277, 700/174, 700/275, 700 31- 33, 318/609, 621/71, 621/83, 621/29, 621/86
• US Class Current: 700/28
• CPC Class Codes: F25B 2600/11 Fan speed control
• CPC Class Codes: F25B 49/027 Condenser control arrangements
• CPC Class Codes: G05B 13/021 in which a variable is automatically adjusted to optimise the performance

Abstract

A system for controlling a cooling tower that cools condenser fluid for a condenser of a chiller includes a cooling tower fan system that controllably varies a speed of at least one fan motor. The system further includes an extremum seeking controller that receives inputs of power expended by the cooling tower fan system and of power expended by the chiller. The extremum seeking controller provides an output to the cooling tower fan system that controls the speed of the at least one fan motor. The extremum seeking controller determines the output by searching for a speed of the at least one fan motor that minimizes the sum of the power expended by the cooling tower fan system and the power expended by the chiller.

Claims

1. A system for controlling a cooling tower that cools condenser fluid for a condenser of a chiller, comprising:

a cooling tower fan system that controllably varies a speed of at least one fan motor; and

an extremum seeking controller that receives inputs of power expended by the cooling tower fan system and of power expended by the chiller;

wherein the extremum seeking controller provides an output to the cooling tower fan system that controls the speed of the at least one fan motor;

wherein the extremum seeking controller determines the output by searching for a speed of the at least one fan motor that minimizes the sum of the power expended by the cooling tower fan system and the power expended by the chiller; and

wherein the extremum seeking controller does not utilize temperature of the condenser fluid as an input.

2. The system of claim 1, wherein the extremum seeking controller is the only controller that controllably varies the speed of the at least one fan motor.

3. The system of claim 1, wherein the extremum seeking controller uses only the inputs of the power expended by the cooling tower fan system and the power expended by the condenser to determine the control signal.

6. The method of claim 1, wherein the extremum seeking controller is the only controller that controllably varies the speed of the at least one fan motor.

4. A method for controlling a cooling tower that cools condenser fluid for a condenser of a chiller, comprising:

receiving, at an extremum seeking controller, an input of power expended by a cooling tower fan system;

receiving, at an extremum seeking controller, an input of power expended by the chiller;

determining, using the extremum seeking controller and the inputs of power expended by the cooling tower fan system and the power expended by the chiller, a control signal representative of the speed of at least one fan motor for the cooling tower fan system; and

wherein the extremum seeking controller does not utilize temperature of the condenser fluid as an input.

5. The method of claim 4, wherein the determining step comprises searching for a speed of the at least one fan motor that minimizes the sum of the power expended by the cooling tower fan system and the power expended by the condenser.

7. The method of claim 4, wherein the extremum seeking controller uses only the inputs of the power expended by the cooling tower fan system and the power expended by the condenser to determine the control signal.

8. The method of claim 4, wherein the inputs are at least one of summed and combined prior to use by the extremum seeking controller.