Leak detection unit for refrigerant system

Patent metadata

Field	Value
Publication number	US-2016178229-A1
Application number	US-201514962461-A
Country	US
Kind code	A1
Filing date	Dec 8, 2015
Priority date	Dec 17, 2014
Publication date	Jun 23, 2016
Grant date	—

Abstract

An HVAC system is provided having an air supply system, a refrigerant circuit configured to condition air in the air supply system, and an electrochemical sensor configured to detect a refrigerant leak from the refrigerant circuit.

First claim

1 . An HVAC system comprising:
an air supply system; a refrigerant circuit configured to condition air in the air supply system; and an electrochemical sensor configured to detect a refrigerant leak from the refrigerant circuit.

2 . The system of claim 1 , wherein the sensor is disposed in the air supply system downstream of an evaporator of the refrigerant circuit.

3 . The system of claim 2 , further comprising a second sensor disposed in the air supply system upstream of the evaporator.

4 . The system of claim 1 , further comprising a controller in signal communication with the sensor and a blower and a damper of the air supply system, wherein the controller is programmed to:
vent air from the air supply system if the sensor detects the refrigerant leak; and/or supply outside air to the air supply system if the sensor detects the refrigerant leak.

5 . The system of claim 1 , wherein the sensor is a solid polymer electrolyte (SPE) electrochemical (EC) sensor.

6 . The system of claim 5 , wherein the sensor is configured to sense hydrocarbons or substituted hydrocarbons, the sensor comprising:
a housing; a membrane electrode assembly disposed in the housing, the membrane electrode assembly comprising a sensing electrode comprising a first catalyst comprising noble metal nanoparticles, a counter electrode comprising a second catalyst comprising noble metal nanoparticles, and a solid polymer electrolyte disposed between the sensing electrode and the counter electrode, wherein the nanoparticles of the first catalyst are unsupported or are supported on a support other than carbon black; a first current collector in electrical contact with the sensing electrode; a second current collector in electrical contact with the counter electrode; the housing including an opening in fluid communication with the sensing electrode for gaseous refrigerant to contact the sensing electrode; and an electrical circuit connecting the sensing electrode and the counter electrode.

7 . The system of claim 6 , wherein first current collector, the second current collector, or each of the first current collector and the second current collector also functions as a gas diffusion medium, and wherein the first current collector, the second current collector, or each of the first current collector and the second current collector is configured as a mesh or felt.

8 . The system of claim 6 , wherein the electrical circuit connecting the sensing electrode and the counter electrode include the controller, the controller configured to apply a positive bias voltage to the sensing electrode relative to the counter electrode or a reference electrode, and to measure voltage or current in the electrical circuit connecting the sensing electrode and the counter electrode to detect an electrochemical response from oxidation of hydrocarbons or substituted hydrocarbons at the sensing electrode.

9 . The system of claim 8 , wherein the concentrations of hydrocarbons or substituted hydrocarbons are determined according to the electrical signal generated by the sensor.

10 . A method of detecting a refrigerant leak in an HVAC system having an air supply system and a refrigerant circuit configured to condition air in the air supply system, the method comprising:
providing a sensor configured to detect refrigerant from the refrigerant circuit that is present in the air in the air supply system; applying a positive bias voltage to the sensor; conditioning the sensor to establish a baseline response; and measuring voltage or current in the sensor to determine if a refrigerant concentration of the air in the air supply system is greater than a predetermined concentration.

11 . The method of claim 10 , further comprising:
determining refrigerant concentration according to a predetermined database mapping refrigerant concentration to a sensor temperature and an environmental dew point; and measuring a sensor output change rate to determine whether a refrigerant leak is present.

12 . The method of claim 10 , wherein said applying a positive bias voltage comprises applying a positive bias voltage to a sensing electrode relative to a counter electrode or a reference electrode, and wherein said measuring voltage or current comprises measuring voltage or current in an electrical circuit connecting the sensing electrode and the counter electrode to detect an electrochemical response from oxidation of hydrocarbons or substituted hydrocarbons at the sensing electrode.

13 . The method of claim 10 , further comprising reducing the refrigerant concentration of the air in the air supply system, if the determined refrigerant concentration is greater than the predetermined concentration, by at least one of:
venting air from the air supply system; and supplying outside air to the air supply system.

14 . The method of claim 13 , wherein air is vented from the air supply system, and wherein said venting air comprises:
moving a damper of the air supply system to a vent position; and activating a blower of the air supply system to force air from the air supply system.

15 . The method of claim 13 , further comprising, subsequent to said reducing the refrigerant concentration, measuring voltage or current in the sensor to determine if a refrigerant concentration of the air in the air supply system is greater than a second predetermined concentration, where the second predetermined concentration is less than the predetermined concentration.

16 . The method of claim 10 , further comprising:
measuring voltage or current in the sensor to determine if a refrigerant concentration of the air in the air supply system is less than a second predetermined concentration, where the second predetermined concentration is less than the first predetermined concentration; determining if a sensor output variation rate of the sensor is less than a predetermined variation rate or within a predetermined range of variation rates; and updating the sensor baseline if the determined sensor output variation rate of less than the predetermined variation rate or within the predetermined range of variation rates.

17 . The method of claim 15 , further comprising:
measuring voltage or current in the sensor to determine if a sensor output variation rate exceeds a predetermined rate; determining whether the sensor output increases more rapidly than a predetermined increase value; and performing a mitigation action including starting a blower and setting a damper to a venting position, to reduce the accumulation of refrigerant in the HVAC system.

18 . The method of claim 17 , further comprising:
measuring voltage or current in the sensor when the blower is activated to determine if the refrigerant concentration decreases; measuring voltage or current in the sensor when the blower is activated to determine if the sensor output increase rate is diminishing; determining a fault based on whether the concentration of refrigerant continues to exceed a predetermined value or the sensor output increases after performing the mitigation action; and issuing an audible alarm and sending fault information if the fault is detected.

Assignees

• Carrier Corp

Inventors

• Chen Lei
• Yang Zhiwei
• Clough Warren
• Burns Larry D
• Rydkin Ivan

Classifications

• F24F11/70

  Control systems characterised by their outputs; Constructional details thereof · CPC title

• F24F2110/50

  Air quality properties · CPC title

• F24F2110/66

  Volatile organic compounds [VOC] · CPC title

• F24F11/30

  for purposes related to the operation of the system, e.g. for safety or monitoring · CPC title

• G01M3/202

  using mass spectrometer detection systems · CPC title