WO2019023267A1 - Système de mesure de composition de fluide frigorigène - Google Patents

Système de mesure de composition de fluide frigorigène Download PDF

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Publication number
WO2019023267A1
WO2019023267A1 PCT/US2018/043540 US2018043540W WO2019023267A1 WO 2019023267 A1 WO2019023267 A1 WO 2019023267A1 US 2018043540 W US2018043540 W US 2018043540W WO 2019023267 A1 WO2019023267 A1 WO 2019023267A1
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WO
WIPO (PCT)
Prior art keywords
refrigerant
refrigerant blend
vapor compression
composition
compression system
Prior art date
Application number
PCT/US2018/043540
Other languages
English (en)
Inventor
Damien Jean-Daniel ARNOU
Laurent Claude Eric THIBAUD
François Charles André CLUNET
Paul Eric LE SAUSSE
Original Assignee
Johnson Controls Technology Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Johnson Controls Technology Company filed Critical Johnson Controls Technology Company
Priority to EP18752400.4A priority Critical patent/EP3658829A1/fr
Publication of WO2019023267A1 publication Critical patent/WO2019023267A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
    • F25B9/006—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant containing more than one component
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/30—Expansion means; Dispositions thereof
    • F25B41/39—Dispositions with two or more expansion means arranged in series, i.e. multi-stage expansion, on a refrigerant line leading to the same evaporator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/04—Refrigerant level
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/19—Pressures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2108—Temperatures of a receiver

Definitions

  • This application relates generally to vapor compression systems, such as chillers, and more specifically to a refrigerant composition measurement system for determining the composition of a refrigerant blend in a vapor compression system.
  • Refrigeration systems are used in a variety of settings and for many purposes.
  • refrigeration systems may include a free cooling system and a mechanical cooling system.
  • the free cooling system may include a liquid-to-air heat exchanger, which is used in some heating, ventilation, and air conditioning applications.
  • the mechanical cooling system may be a vapor compression refrigeration cycle, which may include a condenser, an evaporator, a compressor, and/or an expansion device.
  • a cooling fluid e.g., water
  • Refrigeration systems typically use a refrigerant, sometimes referred to as a working fluid, that can be a pure fluid having a single refrigerant component or a refrigerant blend that is a mixture with multiple refrigerant components.
  • refrigerant blends can be described as being “non-azeotropic,” “zeotropic,” or “with glide,” meaning that there are composition differences in the refrigerant blend as it transitions between liquid and vapor states as a result of partial distillation of the components at different points in the refrigeration system.
  • a refrigerant blend measurement system is configured to determine a composition of a refrigerant blend within a refrigerant circuit of a vapor compression system.
  • the RBMS includes a sample vessel disposed between a condenser and an evaporator of the refrigeration circuit and configured to receive a portion of the refrigerant blend, wherein the sample vessel comprises a first sensor configured to measure a temperature of a liquid portion of the refrigerant blend and a second sensor configured to measure a pressure of the refrigerant blend.
  • the vapor compression system includes a control unit communicatively coupled to the first sensor and the second sensor of the sample vessel.
  • the control unit includes a processor configured to execute instructions stored in a memory of the control unit to perform actions including: receiving a measured temperature value from the first sensor; receiving a measured pressure value from the second sensor; determining a composition of the refrigerant blend based on the measured temperature value and the measured pressure value; and determining that the composition is beyond a predefined threshold stored in the memory, and in response, modifying operation of the vapor compression system.
  • a method controlling operation of a vapor compression system includes: (A) determining a calculated saturation temperature value based on a measured pressure of a refrigerant blend along a liquid line of the vapor compression system and based on an estimated composition of the refrigerant blend; and then (B) comparing the calculated saturation temperature value to a measured temperature of a liquid phase of the refrigerant blend along the liquid line of the vapor compression system; and then (C) adjusting the estimated composition of the refrigerant blend and repeating step A and B until the calculated saturation temperature value and the measured temperature value are substantially equal; and then (D) determining that the estimated composition is a current composition of the refrigerant blend; and then (E) modifying operation of the vapor compression system based on the current composition of the refrigerant blend.
  • a vapor compression system has a refrigerant circuit, including: a sample vessel including a liquid level sensor; and a first electronic expansion valve (EEV) disposed downstream of the sample vessel in the refrigerant circuit and upstream of an evaporator of the refrigerant circuit; and a temperature sensor and a pressure sensor located between a condenser of the refrigerant circuit and the first EEV; and a controller communicatively coupled to the liquid temperature sensor, the pressure sensor, and the first EEV of the refrigerant circuit, The controller is configured to perform actions including: controlling the first EEV based on a liquid level measured by the liquid level sensor; determining a current composition of a refrigerant blend within the sample vessel based on a temperature measured by the liquid temperature sensor and a pressure measured by the pressure sensor; and modifying operation of the vapor compression system when the current composition of the refrigerant blend is beyond a predefined threshold.
  • EEV electronic expansion valve
  • FIG. 1 is a perspective view of a building that may utilize an embodiment of a heating, ventilation, and air conditioning (HVAC) system in a commercial setting, in accordance with an aspect of the present disclosure
  • HVAC heating, ventilation, and air conditioning
  • FIG. 2 is a perspective view of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure
  • FIG. 3 is a schematic illustration of an embodiment of a vapor compression system, in accordance with an aspect of the present disclosure
  • FIG. 4 is a schematic illustration of another embodiment of a vapor compression system, in accordance with an aspect of the present disclosure
  • FIG. 5 is a schematic diagram of an embodiment of the vapor compression system having a refrigerant blend measurement system (RBMS), in an accordance with an aspect of the present disclosure.
  • RBMS refrigerant blend measurement system
  • FIG. 6 is a flow chart representing an embodiment of a process for operating the vapor compressions system having the RBMS illustrated in FIG. 5, in accordance with an aspect of the present disclosure.
  • a refrigerant blend can have a first composition in a first portion of the refrigerant system, in which the refrigerant comprises a first biphasic mixture (e.g., upstream of an expansion valve) and a second composition in a second portion of the refrigerant system, in which the refrigerant comprises a second biphasic mixture (e.g., downstream of an expansion valve).
  • this compositional difference in the refrigerant blend can be observed throughout a refrigerant system, including, for example, in differences between the composition of a liquid and a vapor refrigerant blend within a heat exchanger of a refrigeration system, in differences between the composition of a liquid refrigerant blend in a condenser and a liquid refrigerant blend in an evaporator of a refrigeration system, and/or in differences in the composition of a refrigerant blend as a result of stagnation and/or heat transfer between the system and the ambient environment.
  • composition of a refrigerant blend in a refrigeration system can vary over its lifetime due to non-homogeneous losses, which will preferentially vent the more volatile component of the refrigerant blend outside the system.
  • present embodiments are directed to a refrigerant blend measuring system (RBMS) for measuring and determining a current composition of a non-azeotropic (zeotropic) refrigerant blend circulating in a refrigeration system, such as a vapor compression system of a chiller.
  • a refrigerant blend measuring system for measuring and determining a current composition of a non-azeotropic (zeotropic) refrigerant blend circulating in a refrigeration system, such as a vapor compression system of a chiller.
  • a refrigeration system such as a vapor compression system of a chiller.
  • the disclosed RBMS includes a sample vessel that is disposed along a liquid line of the refrigeration system to receive a flow of the refrigerant blend for analysis.
  • Control circuitry of the RBMS is communicatively coupled to suitable sensors (e.g., pressure sensors, temperature sensors, liquid level sensors) of the sample vessel and is programmed to measure physical properties (e.g., pressure, temperature, liquid level) of the refrigerant blend within the sample vessel.
  • the control circuitry of the RBMS is further programmed to determine a composition of the refrigerant blend using stored data relating values of the measured physical properties in the sample vessel with different refrigerant blend compositions.
  • the control circuitry of the RBMS may monitor the composition of the refrigerant blend over time and provide an indication (e.g., an alert or alarm) when the composition of the refrigerant blend differs from a target composition by greater than a predetermined threshold.
  • control circuitry may modify operation of the refrigeration system based on the determined composition of the refrigerant blend, for example, to improve the efficiency of the refrigeration system, to ensure integrity of the components of the refrigeration system, and/or to ensure regulatory compliance with respect to the composition of the refrigerant blend and/or the refrigeration system.
  • control techniques of the present disclosure may be used in a variety of systems. However, to facilitate discussion, examples of systems that may incorporate the control techniques of the present disclosure are depicted in FIGS. 1-4, which are described hereinbelow.
  • FIG. 1 is a perspective view of an embodiment of an environment for a heating, ventilation, and air conditioning (HVAC) system 10 in a building 12 for a typical commercial setting.
  • the HVAC system 10 may include a vapor compression system 14 that supplies a chilled liquid, which may be used to cool the building 12.
  • the HVAC system 10 may also include a boiler 16 to supply warm liquid to heat the building 12 and an air distribution system which circulates air through the building 12.
  • the air distribution system can also include an air return duct 18, an air supply duct 20, and/or an air handler 22.
  • the air handler 22 may include a heat exchanger that is connected to the boiler 16 and the vapor compression system 14 by conduits 24.
  • the heat exchanger in the air handler 22 may receive either heated liquid from the boiler 16 or chilled liquid from the vapor compression system 14, depending on the mode of operation of the HVAC system 10.
  • the HVAC system 10 is shown with a separate air handler on each floor of building 12, but in other embodiments, the HVAC system 10 may include air handlers 22 and/or other components that may be shared between or among floors.
  • FIGS. 2 and 3 illustrate embodiments of the vapor compression system 14 that can be used in the HVAC system 10.
  • the vapor compression system 14 may circulate a refrigerant through a circuit starting with a compressor 32.
  • the circuit may also include a condenser 34, an expansion valve(s) or device(s) 36, and a liquid chiller or an evaporator 38.
  • the vapor compression system 14 may further include a control panel 40 (e.g., controller) that has an analog to digital (A/D) converter 42, a microprocessor 44, a non-volatile memory 46, and/or an interface board 48.
  • A/D analog to digital
  • HFC hydrofluorocarbon
  • R-410A R-407, R-134a
  • HFO hydrofluoro-olefin
  • NH3 ammonia
  • R-717 R-717
  • C02 carbon dioxide
  • R-744 hydrocarbon based refrigerants
  • water vapor refrigerants with low global warming potential (GWP)
  • GWP global warming potential
  • the vapor compression system 14 may be configured to efficiently utilize refrigerants having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit or less) at one atmosphere of pressure, also referred to as low pressure refrigerants, versus a medium pressure refrigerant, such as R-134a.
  • refrigerants having a normal boiling point of about 19 degrees Celsius (66 degrees Fahrenheit or less) at one atmosphere of pressure also referred to as low pressure refrigerants
  • medium pressure refrigerant such as R-134a.
  • "normal boiling point” may refer to a boiling point temperature measured at one atmosphere of pressure.
  • the vapor compression system 14 may use one or more of a variable speed drive (VSDs) 52, a motor 50, the compressor 32, the condenser 34, the expansion valve or device 36, and/or the evaporator 38.
  • the motor 50 may drive the compressor 32 and may be powered by a variable speed drive (VSD) 52.
  • the VSD 52 receives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor 50.
  • the motor 50 may be powered directly from an AC or direct current (DC) power source.
  • the motor 50 may include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.
  • the compressor 32 compresses a refrigerant vapor and delivers the vapor to the condenser 34 through a discharge passage.
  • the compressor 32 may be a centrifugal compressor.
  • the refrigerant vapor delivered by the compressor 32 to the condenser 34 may transfer heat to a cooling fluid (e.g., water or air) in the condenser 34.
  • the refrigerant vapor may condense to a refrigerant liquid in the condenser 34 as a result of thermal heat transfer with the cooling fluid.
  • the refrigerant liquid from the condenser 34 may flow through the expansion device 36 to the evaporator 38.
  • the condenser 34 is water cooled and includes a tube bundle 54 connected to a cooling tower 56, which supplies the cooling fluid to the condenser.
  • the refrigerant liquid delivered to the evaporator 38 may absorb heat from another cooling fluid, which may or may not be the same cooling fluid used in the condenser 34.
  • the refrigerant liquid in the evaporator 38 may undergo a phase change from the refrigerant liquid to a refrigerant vapor.
  • the evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to a cooling load 62.
  • the cooling fluid of the evaporator 38 enters the evaporator 38 via return line 60R and exits the evaporator 38 via supply line 60S.
  • the evaporator 38 may reduce the temperature of the cooling fluid in the tube bundle 58 via thermal heat transfer with the refrigerant.
  • the tube bundle 58 in the evaporator 38 can include a plurality of tubes and/or a plurality of tube bundles. In any case, the refrigerant vapor exits the evaporator 38 and returns to the compressor 32 by a suction line to complete the cycle.
  • FIG. 4 is a schematic of the vapor compression system 14 with an intermediate circuit 64 incorporated between condenser 34 and the expansion device 36.
  • the intermediate circuit 64 may have an inlet line 68 that is directly fluidly connected to the condenser 34.
  • the inlet line 68 may be indirectly fluidly coupled to the condenser 34.
  • the inlet line 68 includes a first expansion device 66 positioned upstream of an intermediate vessel 70.
  • the intermediate vessel 70 may be a flash tank (e.g., a flash intercooler).
  • the intermediate vessel 70 may be configured as a heat exchanger or a "surface economizer.” In the illustrated embodiment of FIG.
  • the intermediate vessel 70 is used as a flash tank, and the first expansion device 66 is configured to lower the pressure of (e.g., expand) the refrigerant liquid received from the condenser 34. During the expansion process, a portion of the liquid may vaporize, and thus, the intermediate vessel 70 may be used to separate the vapor from the liquid received from the first expansion device 66. Additionally, the intermediate vessel 70 may provide for further expansion of the refrigerant liquid because of a pressure drop experienced by the refrigerant liquid when entering the intermediate vessel 70 (e.g., due to a rapid increase in volume experienced when entering the intermediate vessel 70). The vapor in the intermediate vessel 70 may be drawn by the compressor 32 through a suction line 74 of the compressor 32.
  • the vapor in the intermediate vessel may be drawn to an intermediate stage of the compressor 32 (e.g., not the suction stage).
  • the liquid that collects in the intermediate vessel 70 may be at a lower enthalpy than the refrigerant liquid exiting the condenser 34 because of the expansion in the expansion device 66 and/or the intermediate vessel 70.
  • the liquid from intermediate vessel 70 may then flow in line 72 through a second expansion device 36 to the evaporator 38.
  • the intermediate vessel 70 may be a sample vessel including suitable sensors for measuring properties of a refrigerant blend flowing within the vapor compression system 14.
  • the intermediate vessel 70 may serve more than one function (e.g., sample vessel, flash intercooler, heat exchanger, surface economizer, or a combination thereof) in the vapor compression system 14.
  • the relative composition of a refrigerant blend e.g., a refrigerant mixture comprising two or more refrigerants
  • a refrigerant blend e.g., a refrigerant mixture comprising two or more refrigerants
  • the refrigerant blend may be a mixture of refrigerant components A and B, where component A is more volatile (e.g., has a higher vapor pressure) than component B under the operating conditions of the vapor compression system 14.
  • component A is more volatile (e.g., has a higher vapor pressure) than component B under the operating conditions of the vapor compression system 14.
  • FIG. 5 is a schematic diagram illustrating an embodiment of a refrigerant circuit 76 of the vapor compression system 14 that includes a refrigerant blend measurement system (RBMS) 77, in accordance with the present techniques.
  • the intermediate vessel 70 discussed above with respect to FIG. 4 is, more specifically, a sample vessel 78.
  • the sample vessel 78 may be generally described as being disposed downstream of the condenser 34, upstream of the evaporator 38, and along a liquid line 79 (also referred to herein as an expansion line) of the refrigerant circuit 76.
  • the illustrated sample vessel 78 includes suitable sensors 80, such as a pressure sensor 80A, a liquid temperature sensor 80B, and a liquid level sensor 80C, configured to measuring properties of a refrigerant blend 82 within the sample vessel 78. It may be appreciated that, in certain embodiments, the sample vessel 78 may include other suitable sensors that measure properties of the refrigerant blend 82, in accordance with the present disclosure.
  • the sensors 80 may be positioned in other locations in the refrigerant circuit 76, in addition or in alternative to being positioned within the sample vessel 78. That is, it is recognized that temperature and pressure measurements may be performed in one or more locations along the liquid (expansion) line 79 in various embodiments.
  • the sample vessel 78 may not be present, and there may be one or more sets of pressure and temperature sensors 80 disposed at one or more locations, including downstream of the condenser 34, downstream of the EEV 66, upstream of the EEV 36, downstream of the EEV 36, and/or upstream of the evaporator 38.
  • sensors 80 may be disposed upstream of the sample vessel 78, within the sample vessel 78, and/or downstream of the sample vessel 78.
  • a single set of pressure and temperature sensors 80 may be disposed downstream of the sample vessel 78 (or another suitable intermediate vessel 70).
  • the refrigerant circuit 76 may include a first set of pressure and temperature sensors 80 disposed downstream of the EEV 66 and upstream of the EEV 36, and also include a second set of pressure and temperature sensors 80 disposed downstream of the EEV 36 and upstream of the evaporator 36.
  • the embodiment of the RBMS 77 illustrated in FIG. 5 also includes a control unit 84 that is communicatively coupled to the sensors 80 (e.g., sensors 80A, 80B, 80C) to receive measurement data.
  • the control unit 84 includes memory circuitry 86 configured to store instructions and processing circuity 88 configured to execute the instructions to determine the composition of the refrigerant blend 82 within sample vessel 78, as discussed below.
  • the control unit 84 is communicatively coupled to other components of the vapor compression system 14, such as the compressor 32, to modify or alter operation of the vapor compression system 14 in response to the determined refrigerant blend composition.
  • control unit 84 may be the control panel 40, may be included as part of the control panel 40, or may be communicatively coupled to the control panel 40, such that the control panel 40 can control operation of the vapor compression system 14 based on the determined refrigerant blend composition.
  • control panel 40 and the control unit 84 may perform any or all of the monitoring, determining, and/or controlling aspects discussed herein, in different embodiments.
  • the first expansion device 66 and the second expansion device 36 are electronic expansion valves (EEV) that are controlled by the control unit 84.
  • EEVs 36 and 66 may be controlled by a proportional-integral-derivative (PID) controller 90 that is part of the control unit 84, or a separate PID controller.
  • PID proportional-integral-derivative
  • the EEVs 36 and 66 may operate based on measured conditions of the refrigerant circuit 76.
  • EEV 36 may operate to maintain a predefined target liquid level 92 within the condenser 34, as measured by a liquid level sensor 94 disposed within the condenser 34.
  • EEV 66 may operate to maintain a predefined liquid level 96 within the sample vessel 78, as measured by the liquid level sensor 80C disposed in the sample vessel 78. As such, based on signals from the control unit 84, the EEVs 36 and 66 operate to regulate the flow of the refrigerant blend 82 into and out of the sample vessel 78.
  • the refrigerant circuit 76 may include a secondary flow path, such as a bypass line 98, fluidly coupling the condenser 34 and the evaporator 30, which where the bypass line 90 includes the expansion device 36 but not the sample vessel 78 or the expansion device 66.
  • the control unit 84 may provide suitable signals to three-way control valves 100A and 100B associated with the bypass line 98 to divert the refrigerant blend 82 to flow through the bypass line 98 instead of the sample vessel 78.
  • control unit 84 may provide such signals to improve the efficiency of the operation of the refrigerant circuit 76 and the vapor compression system 14 at times when the composition of the refrigerant blend 82 is not being measured and determined.
  • the bypass line 98 may not be present in the vapor compression system 14.
  • the illustrated sample vessel 78 of the disclosed RBMS 77 generally receives a flow of the refrigerant blend 82 for compositional analysis that has traversed the EEV 66. Accordingly, the flow of the refrigerant blend 82 delivered to the sample vessel 78 exists in both a vapor phase 82A and a liquid phase 82B during operation of the vapor compression system 14.
  • the sensors 80 of the sample vessel 78 interact with the received portion of the refrigerant blend to measure properties thereof.
  • the pressure sensor 80A is designed and suitably positioned to measure a static pressure of the received refrigerant blend 82 (e.g., within either of the vapor phase 82A or the liquid phase 82B), while the liquid temperature sensor 80B is designed and suitably positioned to measure a temperature of the liquid phase 82B of the received refrigerant blend 82.
  • vapor phase 82A and the liquid phase 82B can each have a different composition due to the different physical properties (e.g., vapor pressure, saturation temperature) of the refrigerant components that make up the refrigerant blend 82.
  • a composition of the vapor phase 82A of the refrigerant blend 82 may include a relatively greater amount of a more volatile refrigerant component of the refrigerant blend 82
  • the liquid phase 82B of the refrigerant blend 82 may include a relatively greater amount of a less volatile refrigerant component.
  • control unit 84 is configured to receive pressure measurements from the pressure sensor 80A and temperature measurements from the liquid temperature sensor 80B and is configured to use these measurements, along with physical property data stored in the memory 86 for different refrigerant blend compositions, to determine the composition of the current refrigerant blend 82 in the sample vessel 78.
  • control unit 84 may determine the composition of the refrigerant blend 82 continuously, periodically (e.g., at the beginning a cycle), or based on input received from an operator.
  • the determined composition of the refrigerant blend 82 may be provided (e.g., via the control panel 40, a thermostat panel, or a portable electronic device) to an operator or technician to monitor for potential maintenance issues.
  • the control unit 84 may provide the current composition of the refrigerant blend 82 to the control panel 40 to be presented via a display device 102.
  • control unit 84 and/or the control panel 40 may determine and present, on the display device 102, an amount of one or more refrigerant components of the refrigerant blend 82 that should be added to the refrigeration system to modify the composition of the refrigerant blend (e.g., back to the originally charged refrigerant blend composition or to a completely different refrigerant blend).
  • the composition of a refrigerant blend 82 can be modified, in accordance with the present method, to create a dedicated refrigerant blend that meets or adapts to these restrictions.
  • the disclosed RBMS 77 can monitor (e.g., periodically or on-demand) the composition of the refrigerant blend 82 within the vapor compression system 14 over time to ensure that the composition of the refrigerant blend 82 remains in compliance with operator defined thresholds, which may be based on GWP regulations.
  • the operation of the vapor compression system 14 may be controlled, at least in part, based on the determined composition of the refrigerant blend 82.
  • the memory 86 of the control unit 84 may store one or more predefined thresholds, and the control unit 84 may repeatedly compare the current composition of the refrigerant blend 82 to the stored thresholds to determine whether they have been exceeded.
  • the control unit 84 may modify operation of the vapor compression system 14.
  • the control unit 84 e.g., alone or in cooperation with the control panel 40
  • control unit 84 may store a collection of previously determined compositions of the refrigerant blend 82 in the memory 86 and may identify and track changes to the composition of the refrigerant blend 82 over time.
  • control unit 84 may store predefined thresholds for a rate of change of the composition of the refrigerant blend 82 that, when exceeded, may result in the control unit 84 modifying operation of the vapor compression system 14.
  • this approach can enable the control unit 84 to differentiate between a large, gradual shift in composition of the refrigerant blend 82 (e.g., due to slow refrigerant loss or long-term degradation of a refrigerant component) and a large, sudden shift in composition of the refrigerant blend 82 (e.g., due to a substantial loss of refrigerant in the refrigerant circuit 76).
  • the composition of a refrigerant blend 82 can be adjusted to accommodate differences in the performance of certain refrigeration system components between implementations and/or to accommodate potentially varying performance of certain refrigeration system components over the life of the system 14.
  • a dedicated refrigerant blend having a lower saturated pressure can be introduced or created to increase the performance of the vapor compression system 14 despite this high volumetric flow.
  • a dedicated refrigerant blend having a higher saturated pressure can be introduced or created to increase the performance of the system 14 despite this low volumetric flow.
  • the refrigerant circuit 76 includes two refrigerant reservoirs 104A and 104B that are both selectively fluidly coupled to the refrigerant circuit 76 via respective two-way valves 106A and 106B (e.g., two-way solenoid valves).
  • the valves 106 A and 106B are each communicatively coupled to the control unit 84.
  • control unit 84 may send suitable control signals to actuate (e.g., open and/or close) one or more of the valves 106A and 106B to provide a refrigerant component or refrigerant blend to the refrigerant circuit 76 to compensate for a loss of refrigerant of the refrigerant blend 82 (e.g., based on the composition of the refrigerant blend 82 determined by the control unit 84).
  • the refrigerant circuit 76 may include one reservoir (e.g., reservoir 104A).
  • FIG. 6 is a flow chart illustrating an embodiment of a process 110 for operating the refrigerant circuit 76 using the RBMS 77, in accordance with the present disclosure.
  • the process 110 is discussed with reference to elements illustrated in FIG. 5. It is to be understood that the steps discussed herein are merely provided as an example, and certain steps may be omitted or performed in a different order than the order described below in other embodiments.
  • process 110 is discussed below with respect to the control unit 84, it may be appreciated that, in different embodiments, the process 110 may be stored in the memory 86 and executed by the processor 88 of the control unit 84, stored in the memory 46 and executed by the processor 44 of the control panel 40, or stored in other suitable memory circuitry and executed by other suitable processing circuitry of the vapor compression system 14.
  • the illustrated embodiment of the process 1 10 begins with the processor 88 directing (block 1 12) the flow of the refrigerant blend 82 into the sample vessel 78 downstream of the condenser 34 and the EEV 66.
  • the processor 88 may provide suitable signals to the three-way control valves 100A and 100B associated with the bypass line 98 to discontinue the flow of the refrigerant blend 82 through the bypass line 98 and to instead direct the flow to through the sample vessel 78 for analysis.
  • the processor 88 may provide suitable control signals to actuate the EEVs 36 and 66 to maintain the predetermined liquid level 92 of refrigerant blend 82 in the condenser 34 based on measurements received from the liquid level sensor 94 and to maintain the predetermined liquid level 96 in the sample vessel 78 based on measurements received from the liquid level sensor 80C of the sample vessel 78.
  • the processor 88 then receives (block 1 14) measurements of properties of the refrigerant blend 82 from the sensors 80 of the sample vessel 78.
  • the refrigerant blend 82 within the sample vessel 78 includes a vapor phase 82A and a liquid phase 82B.
  • the processor 88 may receive a pressure measurement that corresponds to the static pressure of the refrigerant blend 82 and receive a temperature measurement that corresponds to the temperature of the liquid phase 82B from the liquid temperature sensor 80B.
  • the processor 88 determines (block 1 16) a composition of the refrigerant blend 82 based at least in part on the measurements received from the sensors 80 and data (e.g., lookup tables stored in the memory 86) that relates these measurements for different refrigerant blend compositions.
  • an enthalpy value may be calculated using the upstream temperature and/or pressure measurements (e.g., using suitable sensors 80 disposed upstream of EEV 36) and an assumed refrigerant blend composition. For this method, the enthalpy may be assumed to be constant throughout the expansion line 79.
  • the processor 88 can determine the current composition of the refrigerant blend 82 in the expansion line 79. The processor 88 can continue to iterate this process until convergence is reached between the assumed composition and new composition.
  • An example of an iterative computation process is discussed below. In these embodiments, the sample vessel 78 or intermediate vessel 70 may not be present.
  • the process 1 10 continues with the processor 88 storing (block 120) the determined composition of the refrigerant blend 82 in the memory 86 of the control unit 84.
  • the processor 88 may compare the current determined composition of the refrigerant blend 82 to previously determined and stored compositions to identify trends. For example, the processor 88 may determine a rate of change of the composition of the refrigerant blend 82 based on the stored composition values.
  • the steps recited in block 120 may be skipped, and the processor 88 may proceed through the remainder of the process 110 based only the current determined composition of the refrigerant blend 82.
  • the compositions stored in the memory 86 may be accessible (e.g., by a service technician or a regulatory compliance officer) via the display device 102 of the control panel 40, or another suitable display device 102, to enable presentation of the determined compositions of the refrigerant blend 82, as well as trends of changes in the determined compositions over time.
  • the processor 88 determines (block 122) whether the composition of the refrigerant blend 82 determined in block 1 16 is outside or beyond a predetermined threshold value or range stored in the memory 86, and if it is, the processor 88 may modify operation of the vapor compression system 14 and/or takes other corrective action (block 124).
  • the processor 88 may further compare the trends to one or more predetermined threshold values stored in the memory 86.
  • the memory 86 may store at threshold value defining an acceptable rate of change in the composition of the refrigerant blend 82 over time (e.g., ⁇ 0.01% per week), and when the processor 88 determines that the determined rate of change of the composition is greater than this threshold value, the processor 88 may proceed to block 124 to take corrective action.
  • the processor 88 may proceed back to block 1 12, as indicated by the arrow 126. In certain embodiments, the processor 88 may wait a predetermined amount of time before repeating the process 110. Additionally, for embodiments that include the bypass line 98, the processor 88 may provide control signals to direct the refrigerant blend 82 to traverse the bypass line 98 instead of the sample vessel 78 until the processor 88 is ready to repeat execution of the process 1 10.
  • the processor 88 determines that the composition of the refrigerant blend 82 is outside of a predefined threshold or range, and/or that one or more identified trends are beyond a respective predefined threshold or range, the processor 88 takes corrective action. More specifically, when the processor 88 determines that the composition of the refrigerant blend 82 has changed (e.g., has exceeded an inner or smaller predefined threshold), but is still within an acceptable range to allow operation of the vapor compression system 14 (e.g., has not exceeded an outer or greater predefined threshold), the processor 88 may perform one or more corrective actions.
  • the processor 88 may provide suitable signals to present (e.g., to an operator or service technician) that the inner threshold has been exceeded, and that the outer threshold has not yet been exceed. Additionally, in certain embodiments, the processor 88 may use the determined composition (e.g., as one or more inputs to one or more control algorithms executed by the processor 88) to determine how to modify the operation of one or more electrical and/or mechanical components of the vapor compression system 14 to improve efficiency and/or to ensure proper operation of the system 14.
  • the processor 88 may provide control signals to one or more components or devices of the vapor compression system 14 to adapt to these actual conditions (e.g., a different vapor pressure, saturation pressure, saturation temperature of the determined composition of the refrigerant blend 82).
  • the processor 88 may directly provide control signals to adjust a component depending on the determined composition of the refrigerant blend 82 or indirectly provide control signals by providing communication signals to the control panel 40, such that the processor 44 provides suitable control signals to adjust operation of the component.
  • the processor 44 or 88 may, for example, provide suitable control signals to adjust a speed of a compressor 32, adjust a position of EEVs 36 and/or 66, or make any other suitable adjustments based on the determined composition of the refrigerant blend 82.
  • the processor 88 may provide suitable signals to temporarily open at least one corresponding valve (e.g., valves 106A and/or 106B) to introduce one or more refrigerant components to the refrigerant blend 82 as part of the corrective action of block 124 in order to modify the composition of the refrigerant blend 82.
  • at least one corresponding valve e.g., valves 106A and/or 106B
  • the processor 88 opens the valves 106A and/or 106B of the associated reservoirs 104A and/or 104B for a predetermined period of time to introduce the corresponding refrigerant components, and then the processor 88 repeats the process 110 again (as indicated by the arrow 128) to determine the composition of the adjusted refrigerant blend 82. In certain embodiments, the processor 88 may continue repeating these steps until the composition of the refrigerant blend 82 is gradually modified to once again be within one or more predetermined threshold values stored in the memory 86.
  • the corrective action may include the processor 88 providing signals to discontinue operation of the refrigerant circuit 76 and/or the vapor compression system 14.
  • the processor 88 may provide signals to deactivate the refrigerant circuit 76 (e.g., deactivate the compressor 32) and to block or prevent the system 14 from returning to an active state.
  • the corrective action of block 124 may include the processor 88 providing an indication to an operator (e.g., via the display device 102 of the control panel 40) that the refrigerant blend 82 should be adjusted, or the vapor compression system 14 otherwise serviced, to restore operation of the refrigerant circuit 76.
  • the temperature of refrigerant blend 82 inside the sample vessel 78 is determined to have a value Ti, which corresponds to the saturation temperature of the liquid phase 82B of the refrigerant blend 82 in the sample vessel 78.
  • the pressure inside the sample vessel 78 is determined have a value Pi, which corresponds to the saturation pressure of the vapor phase 82A of the refrigerant blend 82 in the sample vessel 78.
  • composition of the refrigerant blend 82 is assumed to have an initial value Ci, which may be based on the composition of the refrigerant blend 82 charged in the refrigerant circuit 76.
  • TsatLiq is a function that returns liquid saturated temperature (7) at a given pressure (P) and a given refrigerant blend composition (C).
  • the TsatLiq function accesses a look-up table stored in memory 86 that includes data available from National Institute of Standards and Technology (NIST) Reference Fluid Thermodynamic and Transport Properties Database (REFPROP) (e.g., available from https://w ⁇ nist.gov/srd refprop).
  • the look-up table may include a plurality of rows that each describe a relationship between particular values of T, P, and C, for various combinations of the refrigerant components of the refrigerant blend 82.
  • the iterative process involves providing the measured pressure, Pi, and the initial refrigerant blend composition, Ci, as inputs to the TsatLiq function.
  • the value of liquid saturation temperature, T, returned by the function is compared to the measured liquid saturation temperature, Ti. Based on a difference between the two values, a new value for the composition of the refrigerant blend, C2, is selected. For example, in certain cases, when T > Ti, C2 may be assigned a new value resulting in lower saturated temperature than Ci, while when Ti > T, C2 may be assigned a new value resulting in higher saturated temperature than Ci.
  • the measured pressure, Pi, and the new refrigerant blend composition, C2 are then provided as inputs to the TsatLiq function.
  • This iterative process of adjusting the values of C x continues until the output of the function, T, substantially matches (e.g., is within a predefined tolerance of 3%, 2%, 1% of) the measured temperature value Ti, at which the final value of the composition, C z , is determined to be indicative of the composition of the refrigerant blend 82 in the sample vessel 78.
  • a particular refrigerant circuit 76 is charged with a refrigerant blend 82 that includes 174 kilograms (kg) of R125 and 225 kg of R134a.
  • the refrigerant blend 82 includes a mass fraction of 0.44 (or 44%) of R125 and a mass fraction of 0.56 (or 56%) R125.
  • the refrigerant blend 82 within the sample vessel 78 is measured by the sensors 80 and these measurements are provided to the control unit 84 for analysis.
  • the temperature of the liquid phase 82 in the sample vessel 78 is measured to be 23.6 °C
  • the pressure 82A of the refrigerant blend 82 in the sample vessel is measure to be 9.73 bar.
  • the processor 88 provides the pressure value of 9.73 bar and an initial estimate of the mass fraction of R125 (e.g., 0.44) as inputs to the TsatLiq function, which generally returns a temperature value that is different than (e.g. greater than, less than) the 23.6 °C measured temperature value. Accordingly, the processor 88 continues to adjust (e.g., increase or decrease) the estimated mass fraction of R125 until the returned temperature value is substantially the same as the 23.6 °C measured temperature value.
  • the processor 88 increases the mass fraction of R125 incrementally, as discussed above, until the processor 88 determines or estimates that the composition of the refrigerant blend 82 in the sample vessel 78 is approximately 53% R125 and 47% R134a.
  • the determined composition of the refrigerant blend 82 in the sample vessel 78, or anywhere along the liquid line 79, should be substantially the same as the composition of the refrigerant blend 82 in certain portions of the refrigerant circuit 76 (e.g., compressor suction lines, discharge lines), and will vary from the composition of the refrigerant blend 82 in other portions of the refrigerant circuit 76 (e.g., in the condenser 34 and the evaporator 38) due to partial distillation of the refrigerant blend 82.
  • portions of the refrigerant circuit 76 e.g., compressor suction lines, discharge lines
  • the refrigerant circuit 76 is charged with another refrigerant blend (R454B).
  • This refrigerant blend 82 initially has a composition that has a mass fraction that is 0.689 (about 69%) R32 and 0.311 (about 31%) R1234yf. Since R32 is more volatile than R1234yf, the relative amount of R32 may change within the refrigerant blend 82 as a result of refrigerant loss. Additionally, it is presently recognized that, a saturation temperature of the refrigerant blend 82 (e.g., as measured by the liquid temperature sensor 80B) will be reduced by about 0.1 °C each time the mass fraction of R32 in the mixture is reduced by about 1%.
  • the saturation temperature of the refrigerant blend 82 may be monitored and tracked over time by the processor 88, and the processor 88 may subsequently use a determined reduction in saturation temperature to initially estimate an amount of R32 that has been lost from the refrigerant blend 82. For example, in certain embodiments, this may be used to determine an initial value for the composition of the refrigerant blend (Ci) that is provided to the TsatLiq function, along with a measured pressure value (P), and the process may be iterated until the output of the TsatLiq function is substantially the same as the a measured temperature value (7).
  • Table 1 is an example table that includes the mass fractions of R32 and R1234yf in the liquid and vapor phases based on a refrigerant loss and fractional distillation of the refrigerant blend (% loss).
  • the data of Table 1 is based on a modeled refrigerant loss scenario performed for R454B following American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 34, assuming a temperature of 23 °C and a charge of 15% of the capacity of the refrigerant circuit 76.
  • ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers
  • Table 1 As indicated by Table 1, as an amount of the refrigerant blend R454B is lost, the mass fraction of the more volatile refrigerant component, R32, continually drops, while the mass fraction of the less volatile refrigerant component, R1234yf, continually increases, with increasing losses of the refrigerant blend 82. It may be appreciated that Table 1, or other similar tables, may be stored within a suitable memory (e.g., memory 86 or 46) for use as a look-up table. For example, in an embodiment, the after determining the composition of the refrigerant blend 82 using the iterative method described above, the processor 88 may use the determined composition to determine the total loss of refrigerant from the refrigerant circuit 76.
  • a suitable memory e.g., memory 86 or 46
  • Table 1- A table showing a percent loss of refrigerant based on different compositions of vapor and liquid at 23.0 °C and at 15% fill.
  • the presently disclosed technique may be applied, additionally or alternatively, to other portions of the refrigeration system (e.g., refrigerators, chillers, heat pumps, Organic Rankine Cycle (ORC) units) as well as with different types of refrigerant blends (e.g., ORC fluids). It may also be appreciated that, in certain embodiments, the present approach may be applied to refrigerant blends 82 having more than two components (e.g., three, four, five, or more components).
  • additional information e.g., equations, values, models
  • additional information may be stored in the memory and utilized, in conjunction with the aforementioned information and measurements, to determine the actual refrigerant blend from local pressure and temperature measurements.
  • refrigerant blends 82 include three components
  • the system can be solved applying the Raoult law or by use of REFPROP, mentioned above.
  • the technical effects of the present disclosure include a refrigerant blend measuring system (RBMS) configured to measure the current composition of a non- azeotropic (zeotropic) refrigerant blend circulating in a vapor compression system.
  • the control circuitry of the RBMS is further programmed to determine a composition of the refrigerant blend using stored data relating values of the measured physical properties in the sample vessel with different refrigerant blend compositions.
  • the control circuitry of the RBMS can monitor the composition of the refrigerant blend over time and take corrective action when the composition of the refrigerant blend differs from a target composition by greater than a predetermined threshold.
  • control circuitry may modify operation of the refrigeration system based on the determined composition of the refrigerant blend, for example, to improve the efficiency of the refrigeration system, to ensure the integrity of the components of the refrigeration system, and/or to ensure regulatory compliance with respect to the composition of the refrigerant blend and/or the refrigeration system.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Abstract

L'invention concerne un système de mesure de mélange de fluide frigorigène (RBMS) (77) qui est configuré pour déterminer une composition d'un mélange de fluide frigorigène à l'intérieur d'un circuit de fluide frigorigène (76) d'un système de compression de vapeur. Le RBMS comprend: un récipient d'échantillon (70) configuré pour recevoir une partie du mélange de fluide frigorigène, le récipient d'échantillon comprenant un premier capteur configuré pour mesurer une température d'une partie liquide (80B) du mélange de fluide frigorigène et un second capteur configuré pour mesurer une pression (80A) du mélange de fluide frigorigène. Le système de compression de vapeur comprend une unité de commande (84) configurée pour: recevoir une valeur de température mesurée à partir du premier capteur; recevoir une valeur de pression mesurée à partir du second capteur; déterminer une composition du mélange de fluide frigorigène sur la base de la valeur de température mesurée et de la valeur de pression mesurée; et déterminer que la composition est au-delà d'un seuil prédéfini enregistré dans la mémoire, et en réponse, modifier le fonctionnement du système de compression de vapeur.
PCT/US2018/043540 2017-07-24 2018-07-24 Système de mesure de composition de fluide frigorigène WO2019023267A1 (fr)

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WO2020013894A1 (fr) * 2018-07-10 2020-01-16 Johnson Controls Technology Company Système de compression de vapeur
WO2021061520A1 (fr) * 2019-09-24 2021-04-01 Carrier Corporation Échangeur de chaleur pour systèmes à fluides frigorigènes mixtes
EP3919839A1 (fr) 2020-06-04 2021-12-08 Commissariat à l'Energie Atomique et aux Energies Alternatives Procédé de détermination de l évolution de la composition circulante d'un fluide de travail
EP4317840A4 (fr) * 2021-03-31 2024-04-17 Daikin Industries, Ltd. Dispositif de pompe à chaleur

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EP2924372A1 (fr) * 2012-11-20 2015-09-30 Mitsubishi Electric Corporation Dispositif de réfrigération

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DE4230818A1 (de) * 1992-09-15 1994-03-17 Fritz Egger Gmbh Verfahren und Einrichtung zur Leistungsregelung einer Kompressions-Wärmepumpe und/oder Kältemaschine
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EP2924372A1 (fr) * 2012-11-20 2015-09-30 Mitsubishi Electric Corporation Dispositif de réfrigération

Cited By (8)

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Publication number Priority date Publication date Assignee Title
WO2020013894A1 (fr) * 2018-07-10 2020-01-16 Johnson Controls Technology Company Système de compression de vapeur
US10697674B2 (en) 2018-07-10 2020-06-30 Johnson Controls Technology Company Bypass line for refrigerant
US11592212B2 (en) 2018-07-10 2023-02-28 Johnson Controls Tyco IP Holdings LLP Bypass line for refrigerant
WO2021061520A1 (fr) * 2019-09-24 2021-04-01 Carrier Corporation Échangeur de chaleur pour systèmes à fluides frigorigènes mixtes
EP3919839A1 (fr) 2020-06-04 2021-12-08 Commissariat à l'Energie Atomique et aux Energies Alternatives Procédé de détermination de l évolution de la composition circulante d'un fluide de travail
FR3111193A1 (fr) 2020-06-04 2021-12-10 Commissariat A L'energie Atomique Et Aux Energies Alternatives Procédé de détermination de l’évolution de la composition circulante d’un fluide de travail
EP4317840A4 (fr) * 2021-03-31 2024-04-17 Daikin Industries, Ltd. Dispositif de pompe à chaleur
US12044452B2 (en) 2021-03-31 2024-07-23 Daikin Industries, Ltd. Heat pump device using a non-azeotropic mixture refrigerant

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