Adhesive flow meter

Patent metadata

Field	Value
Publication number	US-10845226-B2
Application number	US-201715493673-A
Country	US
Kind code	B2
Filing date	Apr 21, 2017
Priority date	Apr 21, 2017
Publication date	Nov 24, 2020
Grant date	Nov 24, 2020

Abstract

Methods and apparatus for non-intrusively measuring fluid flow in a conduit, such as a pipe or tubing. The apparatus includes an insulator having self-adhesive inner surface attachable to the conduit, a temperature sensor on the inner surface of the insulator that senses the conduit surface temperature, a heat source on the inner surface of the insulator that imparts heat into the conduit, and a microcontroller connected to the heat source activator and the sensor assembly. In one embodiment, a baseline conduit temperature is measured, and the heat source raises the temperature of the conduit by a predetermined amount. When the conduit reaches target temperature, the heat source is deactivated and the cooling time for the conduit to return to its baseline temperature is measured. Fluid flow rate is determined from the cooling time, the temperature rise within a predetermined time, a temperature drop within a predetermined time, and/or a temperature gradient over time.

First claim

What is claimed is:

1. A method for non-intrusively determining a fluid flow in a liquid refrigerant line of an HVAC system, comprising:
attaching an adhesive sensor assembly to an exterior surface of the liquid refrigerant line, wherein the adhesive sensor assembly is configured to determine the fluid flow in a non-intrusive manner that does not modify an internal structure of the liquid refrigerant line;
sensing a first temperature of the exterior surface of the liquid refrigerant line;
changing a temperature of the exterior surface of the liquid refrigerant line to a second temperature;
measuring a time for the exterior surface of the liquid refrigerant line to return to the first temperature from the second temperature; and
determining the fluid flow in the liquid refrigerant line based at least in part upon the time.

2. The method in accordance with claim 1 , wherein changing the temperature of the exterior surface of the liquid refrigerant line includes increasing the temperature of the exterior surface of the liquid refrigerant line.

3. The method in accordance with claim 1 , wherein determining the fluid flow includes multiplying the time by a predetermined coefficient.

4. The method in accordance with claim 1 , wherein sensing the first temperature of the exterior surface of the liquid refrigerant line includes determining that the temperature of the exterior surface of the liquid refrigerant line has fallen within a predetermined temperature range for at least a predetermined period of time.

5. The method in accordance with claim 1 , wherein sensing the first temperature of the exterior surface of the liquid refrigerant line includes determining that the temperature of the exterior surface of the liquid refrigerant line has not changed by more than a predetermined amount for at least a predetermined period of time.

6. The method in accordance with claim 1 , further comprising thermally insulating the exterior surface of the liquid refrigerant line from an ambient environment.

7. The method in accordance with claim 1 , wherein determining is performed in accordance with the formula

Q
=

k
⁢

1

t
2

-

t
1

.

8. An apparatus for non-intrusively determining a fluid flow rate within a liquid refrigerant line of an HVAC system, comprising:
an insulator having an inner surface comprising an adhesive configured for attachment to the liquid refrigerant line;
a temperature sensor disposed on the inner surface of the insulator and configured for sensing a temperature of the liquid refrigerant line;
a heat source disposed on the inner surface of the insulator and configured for imparting heat into the liquid refrigerant line; and
a microcontroller in operative communication with the heat source activator and the temperature sensor, wherein microcontroller is configured to determine the fluid flow rate based on a temperature value determined from the sensing, and further configured to determine the fluid flow rate in a non-intrusive manner that does not expose the temperature sensor to the fluid.

9. The apparatus in accordance with claim 8 , wherein microcontroller is configured to:
measure a baseline temperature of the liquid refrigerant line;
activate the heat source to raise the temperature of the conduit by a predetermined amount;
deactivate the heat source;
measure the cooling time for the liquid refrigerant line to cool to its original temperature; and
determine the fluid flow rate within the conduit from the cooling time.

10. The apparatus in accordance with claim 8 , wherein microcontroller is configured to:
measure a baseline temperature of the conduit;
activate the heat source to raise the temperature of the conduit for a predetermined amount of time;
deactivate the heat source;
measure the raised temperature of the conduit; and
determine the fluid flow rate within the conduit from the difference between the baseline temperature and the raised temperature.

11. The apparatus in accordance with claim 8 , wherein heat source is formed from resistance wire.

12. The apparatus in accordance with claim 8 , further comprising an electronic switch in communication with the microcontroller and configured to selectively activate the heat source.

13. The apparatus in accordance with claim 8 , further comprising an adhesive coating on the inner surface of the insulator.

14. The apparatus in accordance with claim 8 , wherein insulator is formed from material selected from the group consisting of polyethylene foam and glass wool.

15. The apparatus in accordance with claim 8 , wherein microcontroller determines the fluid flow rate in a manner that is independent of a direction of flow.

Assignees

• Trane Int Inc

Inventors

• Han Dong Hyouck

Classifications

• G01F1/6986

  with pulsed heating, e.g. dynamic methods · CPC title

• G01F1/688

  using a particular type of heating, cooling or sensing element {(G01F1/6847 takes precedence)} · CPC title

• G01F1/6847

  where sensing or heating elements are not disturbing the fluid flow, e.g. elements mounted outside the flow duct · CPC title

• G01F1/684 Primary

  Structural arrangements; Mounting of elements, e.g. in relation to fluid flow · CPC title