Systems and Computer Program Products for Measuring Airflow Rates in Heating, Ventilating, and Air Conditioning (HVAC) Ducts and HVAC Systems Including the Same

• US 20120125558A1
• Filed: 11/22/2011
• Published: 05/24/2012
• Est. Priority Date: 11/23/2010
• Status: Active Grant

• Current Assignee: Truveon Corp.
• Original Assignee: Truveon Corp.
• Inventors: Nortman, Randall C., Spalink, Jan-Dieter
• Granted Patent: US 10,161,774 B2
• Time in Patent Office: Days
• US Class Current: 165/11.1
• 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 11/74 for controlling air flow rate or air velocity
• CPC Class Codes: F24F 2110/00 Control inputs relating to air properties
• CPC Class Codes: F24F 2110/30 Velocity
• CPC Class Codes: G01F 1/68 by using thermal effects
• CPC Class Codes: G01F 1/69 of resistive type
• CPC Class Codes: G01F 1/698 Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters

Abstract

An airflow measurement system configured to be received in a duct of a heating, ventilating and air conditioning (HVAC) system is provided. The air flow measurement system includes a housing, and a plurality of cells positioned in the housing, the plurality of cells being configured such that air flows through the plurality of cells when the flow measurement system is positioned in the duct of the HVAC system, wherein at least one of the cells includes a self-heated thermistor.

Claims

1. An airflow measurement system configured to be received in a duct of a heating, ventilating and air conditioning (HVAC) system, the air flow measurement system comprising:

a housing; and

at least one cell positioned in the housing, the at least one cell being configured such that air flows through the at least one cell when the flow measurement system is positioned in the duct of the HVAC system,

wherein at least one of the at least one cell includes a self-heated thermistor.

2. The system of claim 1, wherein the self-heated thermistor comprises a thermistor pair including both s self-heated thermistor and a reference thermistor.

3. They system of claim 2, wherein the at least one cell comprises a plurality of cells and wherein each of the plurality of cells includes a tube that is configured to allow air to flow through the tube.

4. The system of claim 3, wherein the at least one cell comprises a plurality of cells and wherein each of the plurality of cells further includes at least one of a humidity sensor and a pressure sensor.

5. The system of claim 2, wherein the self-heated thermistor is positioned near a downstream end of a corresponding cell and the reference thermistor is positioned upstream of the heated thermistor.

6. The system of claim 2, wherein the self-heated thermistor is positioned near a downstream end of a corresponding cell and the reference thermistor is positioned adjacent to the self-heated thermistor having a partition therebetween.

7. The system of claim 2, wherein the at least one cell comprises a plurality of cells and wherein each of the plurality of cells includes a thermistor pair.

8. The system of claim 2, wherein the at least one cell comprises a plurality of cells and wherein less than all of the plurality of cells include a thermistor pair.

9. The system of claim 1, wherein the at least one cell comprises a plurality of cells and wherein the housing including the plurality of cells is configured to be removed from the duct and replaced by a similar housing.

10. The system of claim 9, wherein the high-resolution system including self heated thermistors in all the plurality of cells is replaced by a lower resolution system including self-heated thermistors in less than all of the plurality of cells.

11. The system of claim 1, wherein the at least one cell comprises a plurality of cells and wherein the plurality of cells have one of a circular, rectangular, square or hexagonal cross-section.

12. The system of claim 1, wherein the at least one cell comprises a plurality of cells and wherein each of the plurality of cells has a length in the direction of air flow in the duct of about 4.0 inches and a cross section having a diameter of about 1.0 inch.

13. They system of claim 1, wherein the system is configured to filter, condition, straighten and measure the air flow in the duct.

14. A heating, ventilating and air conditioning (HVAC) system, the system comprising:

at least one duct;

an airflow measurement system positioned in the duct, the airflow measurement system including at least one thermistor pair including a self-heated thermistor and a reference thermistor;

a power module configured to regulate a variable amount of power delivered to the self-heated thermistor;

an analog to digital convertor (ADC) configured to receive a non-linear output of the ADC;

a calculation module configured to receive an output of the ADC and calculate data used to control air flow in the HVAC system.

15. The system of claim 14, further comprising a measurement module configured to continuously measure the amount of power being delivered to the self-heated thermistor,

wherein the power module is further configured to adjust the amount of power delivered to the self-heated thermistor responsive to the measured power to maintain a highly functional system.

16. The system of claim 15, wherein the measurement module is configured to continually measure the amount of power delivered to the heated thermistor, a resistance of the self-heated thermistor and a resistance of the reference thermistor.

17. The system of claim 16, wherein the calculation module is further configured to:

determine temperatures of the self-heated thermistor and the reference thermistor using a temperature-resistance relationship of the thermistors;

comparing the temperature of the self-heated thermistor to a temperature of a reference thermistor; and

determining an ambient temperature based on the comparison.

18. The system of claim 17, wherein the calculation module is configured to calculate a temperature rise based on a difference between the temperature of the self-heated thermistor and the temperature of the reference thermistor.

19. The system of claim 18, wherein the calculation module is further configured to calculate the airflow rate based on the temperature rise, the amount of electrical power delivered to the self-heated thermistor and coefficients determined during system calibration.

20. The system of claim 14, further comprising a filter positioned upstream of the air flow measurement system.

21. A computer program product for measuring air flow in a heating, ventilation and air conditioning (HVAC) system, the computer program product comprising:

a non-transitory computer readable storage medium including computer readable program code embodied therein, the computer readable program code comprising;

computer readable program code configured to receive data collected in an HVAC system using a high-resolution system including at least one thermistor pair; and

computer readable program code configured to calculate configuration details for the HVAC system based on the received collected data associated with the HVAC system and data associated with other HVAC systems provided by a centralized reference model.

22. The computer program product of claim 21, further comprising:

computer readable program code configured to regulate a variable amount of power delivered to the self-heated thermistor and provide a non-linear output of the self-heated thermistor to an analog to digital convertor (ADC); and

computer readable program code configured to receive an output of the ADC and calculate data used to control air flow in the HVAC system.

23. The computer program product of claim 22, further comprising:

computer readable program code configured to continuously measure the amount of power being delivered to the self-heated thermistor; and

computer readable program code configured to adjust the amount of power delivered to the self-heated thermistor responsive to the measured power to maintain a highly functional system.

24. The computer program product of claim 23, further comprising computer readable program code configured to continually measure the amount of power delivered to the heated thermistor, a resistance of the self-heated thermistor and a resistance of a reference thermistor.

25. The computer program product of claim 24, further comprising:

computer readable program code configured to determine temperatures of the self-heated thermistor and the reference thermistor using a temperature-resistance relationship of the thermistors;

computer readable program code configured to compare the temperature of the self-heated thermistor to a temperature of a reference thermistor; and

computer readable program code configured to determine an ambient temperature based on the comparison.

26. The computer program product of claim 25, further comprising computer readable program code configured to calculate a temperature rise based on a difference between the temperature of the self-heated thermistor and the temperature of the reference thermistor.