ENVIRONMENTAL CONTROL SYSTEMS AND TECHNIQUES FOR MONITORING HEAT EXCHANGER FOULING

• US 20140008035A1
• Filed: 06/28/2013
• Published: 01/09/2014
• Est. Priority Date: 07/05/2012
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Patankar, Ravindra, Menon, Sunil, Nwadiogbu, Emmanuel Obiesie
• Granted Patent: US 9,689,790 B2
• Time in Patent Office: Days
• US Class Current: 165/11.1
• CPC Class Codes: B64D 13/00 Arrangements or adaptations of air-treatment apparatus for aircraft crew or passengers, or freight space , or structural parts of the aircraft treatment rooms with artificial climate for medical purposes A61G10/02; respiratory apparatus in general A62B; for vehicles in general B60H
• CPC Class Codes: F28F 27/00 Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus control arrangements in general G05
• CPC Class Codes: G01N 17/008 Monitoring fouling
• CPC Class Codes: G05B 23/0221 Preprocessing measurements, e.g. data collection rate adjustment; Standardization of measurements; Time series or signal analysis, e.g. frequency analysis or wavelets; Trustworthiness of measurements; Indexes therefor; Measurements using easily measured parameters to estimate parameters difficult to measure; Virtual sensor creation; De-noising; Sensor fusion; Unconventional preprocessing inherently present in specific fault detection methods like PCA-based methods

Abstract

Environmental control systems and techniques for monitoring heat exchanger fouling are provided herein. In an embodiment, a technique for monitoring heat exchanger fouling includes providing a correlation of heat exchanger fouling to an operating variable. The correlation is programmed into a maintenance system that includes a processor that is adapted to receive data regarding the operating variable. The operating variable is chosen from inlet temperatures of input streams into the heat exchanger and outlet temperatures of output streams out of the heat exchanger, heat exchanger pressure drop, overall heat transfer coefficient value, speed of rotation of an air conditioning machine that includes the heat exchanger, and combinations thereof. Data regarding the operating variable is gathered via a sensor that is adapted to measure the operating variable. The measured operating variable is determined to correspond to excessive heat exchanger fouling in accordance with the correlation using the processor.

Claims

1. A technique for monitoring heat exchanger fouling, wherein the technique comprises the steps of:

providing a correlation of heat exchanger fouling to an operating variable, wherein the correlation is programmed into a maintenance system that includes a processor adapted to receive data regarding the operating variable, and wherein the operating variable is chosen from inlet temperatures of input streams into the heat exchanger and outlet temperatures of output streams out of the heat exchanger, heat exchanger pressure drop, overall heat transfer coefficient value, speed of rotation of an air conditioning machine that includes the heat exchanger, and combinations thereof;

gathering data regarding the operating variable via a sensor that is adapted to measure the operating variable; and

determining that the measured operating variable corresponds to excessive heat exchanger fouling in accordance with the correlation using the processor.

2. The technique of claim 1, wherein the maintenance system is an existing maintenance system, and wherein providing the correlation comprises programming the existing maintenance system with the correlation.

3. The technique of claim 1, wherein the heat exchanger is a component of an environmental control system that includes the maintenance system.

4. The technique of claim 3, wherein gathering the data comprises gathering the data via existing embedded sensors in the environmental control system.

5. The technique of claim 1, wherein providing the correlation comprises providing a mathematical model that uses heat exchanger effectiveness to relate heat exchanger fouling to the heat exchanger effectiveness.

6. The technique of claim 5, wherein providing the mathematical model that uses the heat exchanger effectiveness comprises providing the mathematical model relying on temperatures alone.

7. The technique of claim 5, wherein determining that the measured operating variable corresponds to excessive heat exchanger fouling comprises calculating a difference in effectiveness between an original condition heat exchanger and a degraded heat exchanger.

8. The technique of claim 7, wherein determining that the measured operating variable corresponds to excessive heat exchanger fouling further comprises determining that the calculated difference in effectiveness between the original condition heat exchanger and the degraded heat exchanger is different by at least about 0.1.

9. The technique of claim 1, wherein gathering data regarding the operating variable comprises gathering inlet temperatures of input streams into the heat exchanger and outlet temperatures of output streams out of the heat exchanger on both a hot side and a cold side of the heat exchanger.

10. The technique of claim 9, wherein providing the correlation comprises providing a mathematical model that uses Log Mean Temperature Difference between an original condition heat exchanger and a degraded heat exchanger to relate heat exchanger fouling to the Log Mean Temperature Difference.

11. The technique of claim 10, wherein determining that the measured operating variable corresponds to excessive heat exchanger fouling comprises determining that the calculated difference in Log Mean Temperature Difference between the original condition heat exchanger and the degraded heat exchanger is different by at least about 1.

12. The technique of claim 1, wherein providing the correlation of heat exchanger fouling to the operating variable comprises providing the correlation of heat exchanger fouling to heat exchanger pressure drop.

13. The technique of claim 12, wherein the sensor is a pressure sensor adapted to directly measure pressure drop within the heat exchanger, and wherein gathering data regarding the operating variable comprises gathering pressure measurements with the pressure sensor.

14. The technique of claim 1, wherein providing the correlation comprises providing a mathematical model that uses heat exchanger number of transfer units to relate heat exchanger fouling to the heat exchanger number of transfer units.

15. The technique of claim 14, wherein providing the mathematical model that uses the heat exchanger number of transfer units comprises providing the mathematical model relying upon overall heat transfer coefficient value of the heat exchanger.

16. The technique of claim 15, wherein providing the mathematical model that uses the heat exchanger number of transfer units comprises providing the mathematical model where heat exchanger effectiveness is a direct function of the heat exchanger number of transfer units.

17. The technique of claim 15, wherein heat exchanger fouling is monitored over a range of differences between minimum and maximum heat capacity rates during operation of the heat exchanger.

18. A technique for predictive monitoring of a heat exchanger in an environmental control system comprising a controller, a maintenance system, and a fouling indicator, wherein the technique comprises the steps of:

programming the maintenance system with a correlation of heat exchanger fouling to an operating variable, wherein the correlation is programmed into the maintenance system that includes a processor adapted to receive data regarding the operating variable, and wherein the operating variable is chosen from inlet temperatures of input streams into the heat exchanger and outlet temperatures of output streams out of the heat exchanger, heat exchanger pressure drop, overall heat transfer coefficient value, speed of rotation of an air conditioning machine that includes the heat exchanger, and combinations thereof;

gathering data regarding the operating variable from a sensor that is adapted to measure the operating variable via the controller, wherein the controller is in informational communication with the maintenance system;

determining that the measured operating variable corresponds to excessive heat exchanger fouling in accordance with the correlation using the processor; and

providing an indication of excessive heat exchanger fouling with the fouling indicator.

19. An environmental control system comprising:

a sensor adapted to measure an operating variable of the environmental control system;

an air conditioning machine comprising a heat exchanger, wherein the air conditioning machine is adapted to transfer heat from a bleed flow that is provided by an engine of an aircraft to a ram flow that is provided from outside ambient air;

a maintenance system including a processor;

a controller in informational communication with the sensor and with the maintenance system; and

a fouling indicator in informational communication with the maintenance system;

wherein the maintenance system is programmed with a correlation of heat exchanger fouling to the operating variable, and wherein the operating variable is chosen from inlet temperatures of input streams into the heat exchanger and outlet temperatures of output streams out of the heat exchanger, heat exchanger pressure drop, overall heat transfer coefficient value, speed of rotation of the air conditioning machine that includes the heat exchanger, and combinations thereof.

20. The environmental control system of claim 19, wherein the maintenance system is programmed with the correlation that comprises a mathematical model that uses heat exchanger effectiveness to relate heat exchanger fouling to the heat exchanger effectiveness.