# US 2019/0170600 A1 · Systems and methods for detecting refrigerant leaks in heating, ventilating, and air conditioning (hvac) systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0170600 A1 - Document ID: US20190170600A1 - Status: Published application - Kind: A1 - Application number: 15/871,704 - Filed: 2018-01-15 - Published: 2019-06-06 - Earliest claimed: 2017-12-01 - Assignees: Johnson Controls Technology Company - Applicants: Johnson Controls Technology Company - Inventors: Steven A. Tice; William F. McQuade - Web page: https://patentgrep.com/patent/US20190170600A1 ## CPC - G01M 3/16: using electric detection means ({G01M3/045,} G01M3/06, G01M3/12, G01M3/20, G01M3/24, G01M3/26 take precedence) - F25B 49/005: {of safety devices (F25B49/02 and F25B49/04 take precedence)} - G01M 3/002: {by using thermal means} - G01M 3/2815: {using pressure measurements} - F25B 2500/222: Detecting refrigerant leaks - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS ## Abstract The present disclosure relates to a refrigerant leak detection and mitigation system of a heating, ventilating, and air conditioning (HVAC) unit. The refrigerant leak detection and mitigation system includes a controller configured to determine a plurality of parameters correlated to refrigerant leak conditions based on data from a plurality of sensors. The controller is also configured to determine a probability of a refrigerant leak in the HVAC unit based on the plurality of parameters. Additionally, the controller is configured to provide a control signal to modify operation of the HVAC unit in response to comparison of the probability with a threshold value. ## Claims ### Claim 1 A refrigerant leak detection and mitigation system of a heating, ventilating, and air conditioning (HVAC) unit, comprising a controller configured to: determine a plurality of parameters correlated to refrigerant leak conditions based on data from a plurality of sensors; determine a probability of a refrigerant leak in the HVAC unit based on the plurality of parameters; and provide a control signal to modify operation of the HVAC unit in response to a comparison of the probability with a threshold value. ### Claim 2 (depends on 1) The system of claim 1, wherein the controller is configured to determine an amount of icing based on measurements from an icing sensor associated with the HVAC unit, the amount of icing being one of the plurality of parameters. ### Claim 3 (depends on 1) The system of claim 1, wherein the controller is configured to determine an amount of subcooling based on measurements from a subcooling sensor associated with the HVAC unit, the amount of subcooling being one of the plurality of parameters. ### Claim 4 (depends on 1) The system of claim 1, wherein the controller is configured to determine an amount of superheat based on measurements from superheat sensors associated with the HVAC unit, the amount of superheat being one of the plurality of parameters. ### Claim 5 (depends on 1) The system of claim 1, wherein the controller is configured to determine the probability of the refrigerant leak based on a weighted combination of two or more of: a measured amount of icing, a measured amount of subcooling, and a measured amount of superheat. ### Claim 6 (depends on 1) The system of claim 1, comprising an icing sensor, wherein the icing sensor comprises a pressure sensor and a temperature sensor disposed between an evaporator and a compressor of the HVAC unit. ### Claim 7 (depends on 6) The system of claim 6, wherein the controller is configured to: receive a pressure signal from the pressure sensor and a temperature signal from the temperature sensor, wherein the pressure signal and the temperature signal are indicative of a pressure and temperature of a refrigerant between an evaporator and a compressor of the HVAC unit; and predict an amount of icing based on the pressure and the temperature signal. ### Claim 8 (depends on 7) The system of claim 7, wherein the pressure sensor and the temperature sensor are disposed at a refrigerant outlet of the evaporator. ### Claim 9 (depends on 8) The system of claim 8, wherein the pressure sensor and the temperature sensor are integrated into a single body of a combination pressure temperature sensor. ### Claim 10 (depends on 1) The system of claim 1, comprising an ice sensor disposed on an outer surface of an evaporator of the HVAC unit, wherein the controller is configured to determine a level of ice on the outer surface of the evaporator based on data from the ice sensor. ### Claim 11 (depends on 1) The system of claim 1, comprising a pressure sensor and a temperature sensor disposed between a condenser and an expansion device of the HVAC unit, and wherein the controller is configured to determine an amount of subcooling based on signals received from the pressure sensor and the temperature sensor. ### Claim 12 (depends on 1) The system of claim 1, comprising a pressure sensor and a temperature sensor disposed between a compressor and a condenser of the HVAC unit, wherein the controller is configured to determine an amount of superheat based on signals received from the pressure sensor and the temperature sensor. ### Claim 13 (depends on 1) The system of claim 1, wherein the controller is configured to: determine an air temperature based on measurements from an air temperature sensor; and determine the probability of the refrigerant leak in the HVAC unit based on the determined air temperature. ### Claim 14 (depends on 1) The system of claim 1, wherein the controller is configured to provide the control signal to adjust a position of a damper to allow environmental air into the HVAC unit. ### Claim 15 (depends on 1) The system of claim 1, wherein the controller is configured to provide the control signal to adjust a speed of a supply fan to increase airflow through the HVAC unit. ### Claim 16 (depends on 1) The system of claim 1, wherein the controller is configured to provide the control signal to deactivate the HVAC unit. ### Claim 17 (depends on 1) The system of claim 1, wherein the controller is configured to provide to the control signal to adjust a speed of a variable speed supply fan proportional to the probability of the refrigerant leak. ### Claim 18 A heating, ventilating, and air conditioning (HVAC) system having a condenser, an expansion device, an evaporator, and a compressor fluidly coupled to form a vapor compression system, wherein the HVAC system includes a refrigerant leak detection and mitigation system, comprising: icing sensors, subcooling sensors, and superheat sensors communicatively coupled to a controller that is configured to: determine an amount of icing, an amount of subcooling, and an amount of superheat based on measurements from the icing, subcooling, and superheat sensors, respectively; determine a probability of a refrigerant leak in the vapor compression system based on at least two of the determined amount of icing, subcooling, and superheat; and provide a control signal to modify operation of the HVAC system in response to results of comparing the probability to a threshold value. ### Claim 19 (depends on 18) The system of claim 18, wherein the controller is configured to determine the probability of the refrigerant leak based on a weighted combination of the determined amount of icing, subcooling, and superheat. ### Claim 20 (depends on 18) The system of claim 18, wherein the icing sensors comprise a pressure sensor and a temperature sensor disposed at a refrigerant outlet of the evaporator, and wherein the controller is configured to: receive respective signals from the pressure sensor and the temperature sensor indicating a pressure and temperature of refrigerant in the vapor compression system between the evaporator and the compressor; and determine the amount of icing based on the respective signals received from the pressure and temperature sensor. ### Claim 21 (depends on 20) The system of claim 20, wherein the icing sensors comprise an ice sensor disposed on an outer surface of the evaporator, and wherein the controller is configured to determine the amount of icing based on a signal received from the ice sensor. ### Claim 22 (depends on 18) The system of claim 18, wherein the subcooling sensors comprise a pressure sensor and a temperature sensor disposed at a refrigerant outlet of the condenser, and wherein the controller is configured to determine the amount of subcooling based on signals received from the pressure sensor and the temperature sensor. ### Claim 23 (depends on 22) The system of claim 22, comprising an air temperature sensor communicatively coupled to the controller, wherein the controller is configured to: determine the air temperature based on signals received from the air temperature sensor; and determine the amount of subcooling based on the determined air temperature. ### Claim 24 (depends on 18) The system of claim 18, wherein the superheat sensors comprise a pressure sensor and a temperature sensor disposed at a refrigerant outlet of the compressor, and wherein the controller is configured to: receive respective signals from the pressure sensor and the temperature sensor indicating a pressure and temperature of refrigerant in the vapor compression system between the compressor and the condenser; determine an amount of discharge superheat based on the respective signals received from the pressure sensor and the temperature sensor; and determine the probability of the refrigerant leak based on the determined amount of discharge superheat. ### Claim 25 (depends on 24) The system of claim 24, comprising an air temperature sensor communicatively coupled to the controller, wherein the controller is configured to: receive signals from the air temperature sensor indicating an air temperature; determine the air temperature based on the signals received from the air temperature sensor; and determine the amount of superheat based on the determined air temperature. ### Claim 26 (depends on 18) The system of claim 18, wherein the controller is configured to provide the control signal to adjust a position of a damper to allow fresh air into the HVAC system and adjust a speed of a supply fan to increase airflow through the HVAC system. ### Claim 27 (depends on 18) The system of claim 18, wherein the control signal comprises a control signal to send an email, text message, or phone call to an electronic device. ### Claim 28 (depends on 27) The system of claim 27, wherein the controller is configured to: determine a second amount of icing, a second amount of subcooling, and a second amount of superheat based on second measurements from the icing, subcooling, and superheat sensors, respectively; determine a second probability of the refrigerant leak in the vapor compression system based on the determined second amount of icing, second amount of subcooling, and second amount of superheat; and provide an additional control signal to modify operation of the HVAC system in response to determining that the second probability exceeds the predetermined threshold value. ### Claim 29 (depends on 18) The system of claim 18, wherein the controller is configured to provide to the control signal to adjust a speed of a variable speed supply fan proportional to the probability of the refrigerant leak. ### Claim 30 (depends on 18) The system of claim 18, wherein the superheat sensors comprise a pressure sensor and a temperature sensor disposed at a refrigerant inlet of the compressor, and wherein the controller is configured to: receive respective signals from the pressure sensor and temperature sensor indicating a pressure and temperature of refrigerant in the vapor compression system between the evaporator and the compressor; determine an amount of suction superheat based on the respective signals received from the pressure sensor and the temperature sensor; and determine the probability of the refrigerant leak based on the determined amount of suction superheat. ### Claim 31 A heating, ventilating, and air conditioning (HVAC) system having a condenser, an expansion device, an evaporator, and a compressor fluidly coupled to form a vapor compression system, wherein the HVAC system includes a refrigerant leak detection and mitigation system, comprising: icing sensors, subcooling sensors, and superheat sensors communicatively coupled to a controller that is configured to: determine an amount of icing, an amount of subcooling, and an amount of superheat based on measurements from the icing, subcooling, and superheat sensors, respectively; determine a probability of a refrigerant leak in the vapor compression system based on the determined amount of icing, subcooling, and superheat; and provide a control signal to modify operation of the HVAC system in response to results of comparing the probability to a threshold value. ### Claim 32 (depends on 31) The system of claim 31, wherein the controller is configured to: determine a second probability of icing based on the measurements from the icing sensors; and provide an additional control signal to modify operation of the HVAC system in response to determining that the second probability exceeds a second threshold value. ### Claim 33 (depends on 32) The system of claim 32, wherein the controller is configured to: determine a subcooling factor based at least partially based on the measurements from the subcooling sensors; and provide the additional control signal to modify operation of the HVAC system in response to determining that the subcooling factor is less than a third threshold value. ### Claim 34 (depends on 33) The system of claim 33, wherein the controller is configured to: determine a superheat factor based at least partially on the measurements from the superheat sensors; and provide the additional control signal to modify operation of the HVAC system in response to determining that the superheat factor exceeds a fourth threshold value. ### Claim 35 (depends on 31) The system of claim 31, wherein the controller is configured to provide to the control signal to adjust a speed of a variable speed supply fan proportional to the probability of the refrigerant leak.