WO2023067567A1 - Detection device for monitoring the state of a fluid in a conduit and system for monitoring the state of a fluid in a conduit, particularly for refrigeration circuits - Google Patents

Detection device for monitoring the state of a fluid in a conduit and system for monitoring the state of a fluid in a conduit, particularly for refrigeration circuits Download PDF

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Publication number
WO2023067567A1
WO2023067567A1 PCT/IB2022/060137 IB2022060137W WO2023067567A1 WO 2023067567 A1 WO2023067567 A1 WO 2023067567A1 IB 2022060137 W IB2022060137 W IB 2022060137W WO 2023067567 A1 WO2023067567 A1 WO 2023067567A1
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WO
WIPO (PCT)
Prior art keywords
detection device
digital camera
box
fluid
state
Prior art date
Application number
PCT/IB2022/060137
Other languages
French (fr)
Inventor
Davide Elardo
Lorenzo BOLOGNESE
Andrea PASQUALIN
Original Assignee
Bereva S.R.L.
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Filing date
Publication date
Application filed by Bereva S.R.L. filed Critical Bereva S.R.L.
Publication of WO2023067567A1 publication Critical patent/WO2023067567A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • 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
    • F25B41/006—Fluid-circulation arrangements optical fluid control arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/74—Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
    • G01F23/284—Electromagnetic waves
    • G01F23/292—Light, e.g. infrared or ultraviolet
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/85—Investigating moving fluids or granular solids
    • 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
    • F25B2700/03—Oil level
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
    • G01N2021/354—Hygrometry of gases
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/85—Investigating moving fluids or granular solids
    • G01N2021/8578—Gaseous flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3577—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing liquids, e.g. polluted water
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
    • G01N21/81—Indicating humidity

Definitions

  • the invention concerns a detection device for monitoring the state of a fluid in a conduit, and a system for monitoring the state of a fluid in a conduit, comprising such a detection device, particularly for refrigeration circuits.
  • the temperature of evaporation of the fluid, at the pressure found in the evaporator, must be lower than that of the environment to be cooled.
  • the fluid in the vapour state is drawn from the compressor and then brought from the initial pressure to a pressure that corresponds to a temperature compatible with that of the cooling fluid used to bring the refrigerant fluid back to the liquid state.
  • the refrigerant gas can assume a physical conformation that indicates a specific criticality for the correct operation of the circuit itself.
  • a first critical situation is given by the fact that, upstream of the expansion valve, the refrigerant gas may be in the not completely liquid state, showing more or less evident traces of vapour in the form of bubbles. This state is critical to the proper operation of the expansion valve, where the latter can regulate the flow rate of the fluid correctly only if it receives gas exclusively in the liquid state.
  • the bubbles must be detectable and avoided by condensation regulation or, if caused by a low presence of refrigerant, by charging the circuit with an appropriate amount of gas.
  • a second critical situation is given by moisture being present in the refrigerant gas, which can damage the circuit components, like for example the compressor; in fact, as to the compressor the risk is that of finding traces of liquid that, being incompressible, would cause it to break. Moisture must therefore be detected and removed from the refrigeration circuit.
  • a third critical situation concerns the possibility of a refrigerant gas with a low oil content; in fact, the presence of lubricating oil emulsified to the refrigerant fluid allows the moving parts of a compressor, the moving parts of which are traversed by the fluid itself, to remain lubricated.
  • a fourth critical situation concerns the possibility of a non-evaporated refrigerant gas; in fact, in the position between evaporator and compressor, the refrigerant gas may be found in a not completely evaporated state creating problems for the next compression phase since the liquid is not compressible. Liquid drops can be detected and avoided through proper regulation of the expansion valve and/or efficiency of the exchanger.
  • the critical situations outlined above can be viewed and monitored by observing the aforementioned phenomena through some transparent inspection surfaces, defined on a corresponding pipe and placed in direct contact with a refrigerant fluid and/or an emulsified oil to be observed and monitored.
  • the vapour bubbles present in the refrigeration circuit in the position upstream of the expansion valve can be seen through an inspection “sight glass” placed in the line crossed by the same refrigerant gas;
  • this sight glass comprises a tubular sleeve configured to be inserted between two coaxial sections of a line, on which sleeve an observation window is defined, comprising in turn a perimeter collar developing radially from the tubular sleeve and a transparent glass sealed inside said tubular collar.
  • the tubular sleeve of an inspection sight glass at the observation window, there is defined a viewing chamber with radial dimensions greater than the conduit through which the gas passes, at the centre of which a sensitive indicator element is placed that changes its colour according to the moisture content of the refrigerant; for example, “green/dry” values indicate a perfect condition, with complete protection against the harmful effects of moisture; if the green colour starts fading, the moisture content is reaching a critical level.
  • one of the methods for checking whether the amount of oil in the circuit is sufficient for the lubrications of the moving parts of the compressor consists in checking the correct oil level optically, or by means of optical sensors.
  • the drops of liquid present in the refrigeration circuit in the position downstream of the evaporator and upstream of the compressor can also be seen in this case through an inspection “sight glass” similar to that described above; the same sight glass also shows the colouring of the indicator placed in its centre, which assumes different colours depending on the moisture rate present in the gas.
  • a first limitation of the prior art is related to the fact that the inspection through an observation window can only take place if the glass of this observation window is installed in a position accessible to the operator; if this position is unfavourable (little space inside the machine, reduced overall dimensions,...), the inspection would be very difficult.
  • a second limitation of the prior art is related to the fact that the assessment of the state of the fluid within the glass of the observation window can only be assessed if an operator is physically present at the site where the conditioning plant to be monitored is placed; therefore, the presence and the assessment by an operator on site is always necessary to analyse the images and assess any corrective actions on the conditioning plant to be monitored.
  • an operator checks the state of the fluid through the glass only while he is staying at the site, effectively preventing a continuous analysis of the evolution of the state of the same refrigerant fluid.
  • the assessment of the state of the fluid depends on the different technical sensitivity to the phenomenon that each operator has, making data not very objective and therefore of little qualitative technical value.
  • the task of the present invention is to develop a detection device for monitoring the state of a fluid in a conduit and a system for monitoring the state of a fluid in a conduit, particularly for refrigeration circuits capable of remedying the aforementioned drawbacks and limitations of the prior art.
  • an object of the invention is to develop a system that allows monitoring the presence of bubbles or of moisture in a pipe in which refrigerant fluid flows even in the event that the inspection window is positioned out of reach of an operator’s eye.
  • Another object of the invention is to develop a system that allows monitoring the state of a fluid in a pipe continuously and independently of the presence of an operator.
  • a further object of the invention is to develop a system that can be used both to detect the presence of bubbles and to detect the presence of moisture, as well as to detect the oil level at a predetermined point of a refrigeration circuit.
  • an object of the invention is to develop a refrigeration plant comprising such a similar monitoring system.
  • a detection device for monitoring the state of a fluid in a conduit according to claim 1 a system for monitoring the state of a fluid in a conduit, particularly for refrigeration circuits, according to claim 9 and a refrigeration plant according to claim 15.
  • FIG. 1 represents a schematic perspective partial exploded view of a system according to the invention
  • FIG. 2 represents a schematic side view of a first application of a system according to the invention
  • FIG. 3 represents a schematic side view of a second application of a system according to the invention.
  • FIG. 4 represents a schematic side view of a third application of a system according to the invention.
  • FIG. 5 represents a schematic side view of a fourth application of a system according to the invention.
  • FIG. 6 represents a refrigeration plant according to the invention.
  • a system for monitoring the state of a fluid in a conduit according to the invention is indicated as a whole with the number 10.
  • This monitoring system 10 comprises a tubular inspection element 11, comprising in turn:
  • central body 12 within which a tubular passage conduit 26 is defined; said central body 12 comprises a transparent inspection wall 13;
  • the monitoring system 10 is characterized in that it comprises a detection device 16, comprising in turn:
  • a digital camera 19 placed inside the box-like body 17, configured and positioned to make a shoot in the direction of the transparent inspection wall 13, i.e. to make a shoot towards the transparent inspection wall 13;
  • the tubular inspection element 11 may be a liquid indicator, or a moisture indicator, or an oil indicator of the type known per se.
  • the transparent inspection wall 13 comprises a collar 23 protruding from the central body 12 of the tubular inspection element 11.
  • a transparent window 24 for example made of glass.
  • the transparent window 24 is sealed to the collar 23.
  • a viewing chamber 25 with radial dimensions greater than the passage conduit 26 in which the refrigerant fluid passes.
  • the joining ends 14 and 15 can be threaded or prepared for welding.
  • the box-like body 17 consists, for example, of a container made of plastic.
  • the box-like body 17 defines a shield against the light coming from the environment, allowing precise and repeatable detection by the digital camera 19
  • the coupling opening 18, configured for connection with the transparent inspection wall 13, is defined by a through hole made on the box-like body 17, shaped so as to couple with the collar 23 of the transparent inspection wall 13.
  • the box-like body 17 is fixed to the tubular inspection element 11 by means of a coupling by interference between the coupling opening 18 and the collar 23.
  • box-like body 17 is fixed to the tubular inspection element 11 by other equivalent fixing means.
  • the coupling opening 18 is coaxial to the axis X of the digital camera 19.
  • the digital camera 19 is intended to be a digital camera of the type known in itself.
  • the digital camera 19 is preferably positioned coaxially with respect to the transparent inspection wall 13.
  • the lighting means 20 placed inside the box-like body 17 comprise at least one emitter element facing the coupling opening 18.
  • the lighting means 20 comprise two LEDs 31 and 32 positioned on either sides of the digital camera 19.
  • the LEDs 31 and 32 are preferably, but not exclusively, positioned symmetrically on either sides of the digital camera 19.
  • the lighting means 20 comprise one or more infrared emitters.
  • the electronic control unit 21 supports the digital camera 19 and the lighting means 20.
  • the electronic control unit 21 is inside the box-like body 17.
  • the electronic control unit 21 is external to the box-like body 17 and is connected to the digital camera 19 and to the lighting means 20 via corresponding cables or ‘wirelessly’.
  • the electronic control unit 21 comprises an electronic board PCB having a micro-controller for image acquisition and for data processing.
  • the electronic control unit 21 comprises an image acquisition, processing software for the calculation of a specific index that is characteristic of the specific application, for example for the detection of the oil level, or specific for the calculation of the percentage of bubbles detected, or specific for the calculation of the percentage of drops detected, or specific for the calculation of the relative moisture; this software is configured to send as output the data in digital format.
  • the monitoring system 10 is schematically shown in Figure 2 in a first application thereof for the detection of non-condensed refrigerant gas.
  • the electronic control unit 21 processes the video images with dedicated hardware and software for the recognition and quantification of the bubbles B.
  • the measurement operation involves acquiring digital video and recognising bubbles within the acquired frames; as an output the system provides the video image and an index, which with regard to the bubbles, for example, is a percentage value of bubbles detected over the total surface area of the scanned area.
  • the collected and coded data are transmitted to a PLC for processing thereof and/or to a supervisor for being read by an operator.
  • the detection device 16 is mounted on the transparent inspection wall 13 in order to make, with the digital camera 19, the shoot of the flow of the gas FG, possibly with the presence of drops of liquid GL.
  • the electronic control unit 21 processes the video images with dedicated hardware and software for the recognition and quantification of drops of liquid GL.
  • the collected and coded data are transmitted to a PLC for processing thereof and/or to a supervisor for being read by an operator.
  • the detection device 16 is applied to a tubular inspection element 111 consisting of a moisture indicator, i.e. comprising, in the centre of the inspection chamber 125, an optical moisture indicator component 140 configured to change its colour depending on the degree of moisture of the gaseous fluid crossing it.
  • a moisture indicator i.e. comprising, in the centre of the inspection chamber 125, an optical moisture indicator component 140 configured to change its colour depending on the degree of moisture of the gaseous fluid crossing it.
  • the detection device 16 via the digital camera 19, films the optical moisture indicator component 140.
  • the electronic control unit 21 processes the video images with dedicated hardware and software for colour recognition of the optical moisture indicator component 140 and the relative accounting of the moisture rate.
  • the collected and coded data are transmitted to a PLC for processing thereof and/or to a supervisor for being read by an operator.
  • the monitoring system according to the invention is schematically shown therein for the detection of the oil level OL at the bottom of a collection base 311.
  • the detection device 16 is applied to a transparent inspection wall 313 of the collection base 311.
  • the detection device 16 via the digital camera 19, films the oil level.
  • the electronic control unit 21 processes the video images with dedicated hardware and software for oil level recognition and relative accounting as a percentage over the total height detected.
  • the collected and coded data are transmitted to a PLC for processing thereof and/or to a supervisor for being read by an operator.
  • the invention also relates to the detection device 16 as such, as described above, i.e. comprising:
  • a digital camera 19 placed inside the box-like body 17, configured and positioned to make a shoot in the direction of the transparent inspection wall 13, i.e. to make a shoot towards the transparent inspection wall 13;
  • the invention also relates to a refrigeration plant 50, comprising a circuit 51 for a refrigerant fluid; a similar cooling plant 50 is schematically shown in Figure 6.
  • This circuit 51 comprises:
  • the peculiarity of the refrigeration plant 50 according to the invention lies in the fact that it comprises at least one monitoring system 10 as described above, positioned in at least one of the following points of the circuit:
  • the plant 50 comprises a monitoring system 10 upstream of the expansion valve 53.
  • the plant 50 may alternatively comprise a monitoring system 110 between evaporator 54 and compressor 55.
  • the plant 50 may comprise a monitoring system 310 on the compressor 55 or on a derivation thereof.
  • the invention develops a detection device for monitoring the state of a fluid in a conduit, and a system for monitoring the state of a fluid in a conduit, particularly for refrigeration circuits, which detection device allows the optical detection by a human operator to be replaced with the acquisition of images by means of a digital camera and with the processing of the acquired images in order to show, by means of a display or data acquisition system:
  • the extrapolated data from the video acquisition, which characterize the states (level, moisture, presence of bubbles) of the fluid: measurement of the level of oil, moisture rate, number (absolute or percentage) of bubbles present in the crossing fluid.
  • This data can then be acquired by control or supervision systems to monitor the state of the fluid, implement new regulation functions or activate specific alarms to preserve the correct operation of the refrigeration plant to which the system according to the invention is applied.
  • the detection and image processing device 16 is mounted on an inspection glass; this device is to be understood as consisting of:
  • a digital camera closed in a protective box i.e. the container of the device
  • a system has been developed with the invention that allows the state of a refrigerant fluid to be continuously inspected even in the case in which the transparent inspection wall is positioned in a position that a human operator cannot reach.
  • a system has been developed with the invention that allows a continuous inspection of a refrigerant fluid remotely through a user interface device (Personal Computer), therefore even in the absence of a human operator near the refrigeration plant to which the system is applied.
  • a user interface device Personal Computer
  • the immediate digitisation, the processing and the sending of signals to a PLC allow to activate an automatic and real-time control of the data themselves, and possibly to activate the devices connected to the PLC itself for a corrective action or the sending of an alarm signal.
  • Converting images into digital in a continuous manner through an acquisition system allows to historicize the state of the refrigerant fluid, or of the lubricating oil, and to analyse the related database as a post-process.
  • the sensor acquires and processes the images in the same way and according to a precise and validated calculation, in this way the measurements are repeatable and the consequent analysis will be quantitative.
  • reference marks are intended to be affixed solely for the purpose of increasing the intelligibility of the claims and consequently such reference marks have no limiting effect on the interpretation of each element identified by way of example by such reference marks.

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Abstract

The present invention concerns a detection device (16) for monitoring the state of a fluid in a conduit, characterized in that it comprises: - a box-like body (17) of containment, having a coupling opening (18) configured for connection with a transparent inspection wall (13) of a tubular inspection element (11); - a digital camera (19) placed inside said box-like body (17), configured and positioned to make a shoot of said transparent inspection wall (13); - lighting means (20) placed inside said box-like body (17), configured to illuminate said coupling opening (18); - an electronic control unit (21) connected to said digital camera (19) and to said lighting means (20).

Description

DETECTION DEVICE FOR MONITORING THE STATE OF A FLUID IN A CONDUIT AND SYSTEM FOR MONITORING THE STATE OF A FLUID IN A CONDUIT, PARTICULARLY FOR REFRIGERATION CIRCUITS.
DESCRIPTION
The invention concerns a detection device for monitoring the state of a fluid in a conduit, and a system for monitoring the state of a fluid in a conduit, comprising such a detection device, particularly for refrigeration circuits.
It is nowadays known that, in a refrigeration circuit, a low-pressure, low- temperature refrigerant fluid passes from the liquid state to the vapour state, removing heat from the environment it is wished to cool.
This transformation takes place at constant pressure and temperature in the evaporator.
For the heat exchange to be possible, the temperature of evaporation of the fluid, at the pressure found in the evaporator, must be lower than that of the environment to be cooled.
The fluid in the vapour state is drawn from the compressor and then brought from the initial pressure to a pressure that corresponds to a temperature compatible with that of the cooling fluid used to bring the refrigerant fluid back to the liquid state.
The change of state takes place in the condenser where the fluid returns to the liquid state.
Therefore, this creates the need to return the condensate that is at high pressure and high temperature into the evaporator. This is achieved by expanding the fluid through the expansion valve which allows to lower the pressure thereof and to return it to its initial condition. The fundamental parts of a saturated vapour-compression refrigerating machine are therefore:
- the compressor;
- the condenser;
- the expansion valve;
- the evaporator.
In the refrigeration circuits there are certain points where, under certain operating conditions, the refrigerant gas can assume a physical conformation that indicates a specific criticality for the correct operation of the circuit itself.
A first critical situation is given by the fact that, upstream of the expansion valve, the refrigerant gas may be in the not completely liquid state, showing more or less evident traces of vapour in the form of bubbles. This state is critical to the proper operation of the expansion valve, where the latter can regulate the flow rate of the fluid correctly only if it receives gas exclusively in the liquid state.
The bubbles must be detectable and avoided by condensation regulation or, if caused by a low presence of refrigerant, by charging the circuit with an appropriate amount of gas.
A second critical situation is given by moisture being present in the refrigerant gas, which can damage the circuit components, like for example the compressor; in fact, as to the compressor the risk is that of finding traces of liquid that, being incompressible, would cause it to break. Moisture must therefore be detected and removed from the refrigeration circuit.
A third critical situation concerns the possibility of a refrigerant gas with a low oil content; in fact, the presence of lubricating oil emulsified to the refrigerant fluid allows the moving parts of a compressor, the moving parts of which are traversed by the fluid itself, to remain lubricated.
If the oil level is low, the moving parts will be unlubricated and therefore subject to breakage.
A fourth critical situation concerns the possibility of a non-evaporated refrigerant gas; in fact, in the position between evaporator and compressor, the refrigerant gas may be found in a not completely evaporated state creating problems for the next compression phase since the liquid is not compressible. Liquid drops can be detected and avoided through proper regulation of the expansion valve and/or efficiency of the exchanger.
The critical situations outlined above can be viewed and monitored by observing the aforementioned phenomena through some transparent inspection surfaces, defined on a corresponding pipe and placed in direct contact with a refrigerant fluid and/or an emulsified oil to be observed and monitored.
With regard to the first critical situation of a non-condensed and/or hydrated refrigerant gas, the vapour bubbles present in the refrigeration circuit in the position upstream of the expansion valve can be seen through an inspection “sight glass” placed in the line crossed by the same refrigerant gas; this sight glass comprises a tubular sleeve configured to be inserted between two coaxial sections of a line, on which sleeve an observation window is defined, comprising in turn a perimeter collar developing radially from the tubular sleeve and a transparent glass sealed inside said tubular collar.
With regard to the second critical situation, in the tubular sleeve of an inspection sight glass, at the observation window, there is defined a viewing chamber with radial dimensions greater than the conduit through which the gas passes, at the centre of which a sensitive indicator element is placed that changes its colour according to the moisture content of the refrigerant; for example, “green/dry” values indicate a perfect condition, with complete protection against the harmful effects of moisture; if the green colour starts fading, the moisture content is reaching a critical level.
With regard to the third critical situation, one of the methods for checking whether the amount of oil in the circuit is sufficient for the lubrications of the moving parts of the compressor consists in checking the correct oil level optically, or by means of optical sensors.
With regard to the fourth critical situation, the drops of liquid present in the refrigeration circuit in the position downstream of the evaporator and upstream of the compressor can also be seen in this case through an inspection “sight glass” similar to that described above; the same sight glass also shows the colouring of the indicator placed in its centre, which assumes different colours depending on the moisture rate present in the gas.
These detection systems, albeit known and widespread, have respective limitations and drawbacks.
A first limitation of the prior art is related to the fact that the inspection through an observation window can only take place if the glass of this observation window is installed in a position accessible to the operator; if this position is unfavourable (little space inside the machine, reduced overall dimensions,...), the inspection would be very difficult.
A second limitation of the prior art is related to the fact that the assessment of the state of the fluid within the glass of the observation window can only be assessed if an operator is physically present at the site where the conditioning plant to be monitored is placed; therefore, the presence and the assessment by an operator on site is always necessary to analyse the images and assess any corrective actions on the conditioning plant to be monitored.
In addition, an operator checks the state of the fluid through the glass only while he is staying at the site, effectively preventing a continuous analysis of the evolution of the state of the same refrigerant fluid.
In addition, the assessment of the state of the fluid depends on the different technical sensitivity to the phenomenon that each operator has, making data not very objective and therefore of little qualitative technical value.
The task of the present invention is to develop a detection device for monitoring the state of a fluid in a conduit and a system for monitoring the state of a fluid in a conduit, particularly for refrigeration circuits capable of remedying the aforementioned drawbacks and limitations of the prior art.
In particular, an object of the invention is to develop a system that allows monitoring the presence of bubbles or of moisture in a pipe in which refrigerant fluid flows even in the event that the inspection window is positioned out of reach of an operator’s eye.
Another object of the invention is to develop a system that allows monitoring the state of a fluid in a pipe continuously and independently of the presence of an operator.
A further object of the invention is to develop a system that can be used both to detect the presence of bubbles and to detect the presence of moisture, as well as to detect the oil level at a predetermined point of a refrigeration circuit.
Still, an object of the invention is to develop a refrigeration plant comprising such a similar monitoring system.
The above-mentioned task and objects are achieved by a detection device for monitoring the state of a fluid in a conduit according to claim 1 , a system for monitoring the state of a fluid in a conduit, particularly for refrigeration circuits, according to claim 9 and a refrigeration plant according to claim 15.
Further features of the system according to claim 1 are described in the dependent claims.
The aforesaid task and objects, together with the advantages that will be mentioned hereinafter, are highlighted by the description of an embodiment of the invention, which is given by way of non-limiting example with reference to the attached drawings, where:
- Figure 1 represents a schematic perspective partial exploded view of a system according to the invention;
- Figure 2 represents a schematic side view of a first application of a system according to the invention;
- Figure 3 represents a schematic side view of a second application of a system according to the invention;
- Figure 4 represents a schematic side view of a third application of a system according to the invention;
- Figure 5 represents a schematic side view of a fourth application of a system according to the invention;
- Figure 6 represents a refrigeration plant according to the invention.
With reference to the aforementioned figures, a system for monitoring the state of a fluid in a conduit according to the invention is indicated as a whole with the number 10.
This monitoring system 10 comprises a tubular inspection element 11, comprising in turn:
- a central body 12, within which a tubular passage conduit 26 is defined; said central body 12 comprises a transparent inspection wall 13;
- two opposite joining ends 14, 15 developing from the central body 12.
The monitoring system 10 according to the invention is characterized in that it comprises a detection device 16, comprising in turn:
- a box-like body 17, of containment, having a coupling opening 18 configured for connection with the transparent inspection wall 13;
- a digital camera 19 placed inside the box-like body 17, configured and positioned to make a shoot in the direction of the transparent inspection wall 13, i.e. to make a shoot towards the transparent inspection wall 13;
- lighting means 20 placed inside the box-like body 17, configured to illuminate the transparent inspection wall 13;
- an electronic control unit 21 connected to the digital camera 19 and to the lighting means 20.
In particular, the tubular inspection element 11 may be a liquid indicator, or a moisture indicator, or an oil indicator of the type known per se.
The transparent inspection wall 13 comprises a collar 23 protruding from the central body 12 of the tubular inspection element 11.
Inside the collar 23 there is a transparent window 24, for example made of glass.
The transparent window 24 is sealed to the collar 23.
In a preferred but not exclusive embodiment variant, at the transparent inspection wall 13 there can be defined a viewing chamber 25, with radial dimensions greater than the passage conduit 26 in which the refrigerant fluid passes.
The joining ends 14 and 15 can be threaded or prepared for welding.
The box-like body 17 consists, for example, of a container made of plastic.
The box-like body 17 defines a shield against the light coming from the environment, allowing precise and repeatable detection by the digital camera 19
The coupling opening 18, configured for connection with the transparent inspection wall 13, is defined by a through hole made on the box-like body 17, shaped so as to couple with the collar 23 of the transparent inspection wall 13. The box-like body 17 is fixed to the tubular inspection element 11 by means of a coupling by interference between the coupling opening 18 and the collar 23.
Alternatively, the box-like body 17 is fixed to the tubular inspection element 11 by other equivalent fixing means.
The coupling opening 18 is coaxial to the axis X of the digital camera 19.
The digital camera 19 is intended to be a digital camera of the type known in itself.
The digital camera 19 is preferably positioned coaxially with respect to the transparent inspection wall 13.
The lighting means 20 placed inside the box-like body 17 comprise at least one emitter element facing the coupling opening 18.
In particular, in this non-limiting embodiment example of the invention, the lighting means 20 comprise two LEDs 31 and 32 positioned on either sides of the digital camera 19.
The LEDs 31 and 32 are preferably, but not exclusively, positioned symmetrically on either sides of the digital camera 19.
As an alternative to the LEDs 31 and 32, the lighting means 20 comprise one or more infrared emitters.
The electronic control unit 21 supports the digital camera 19 and the lighting means 20.
The electronic control unit 21 is inside the box-like body 17.
Alternatively, the electronic control unit 21 is external to the box-like body 17 and is connected to the digital camera 19 and to the lighting means 20 via corresponding cables or ‘wirelessly’.
The electronic control unit 21 comprises an electronic board PCB having a micro-controller for image acquisition and for data processing. The electronic control unit 21 comprises an image acquisition, processing software for the calculation of a specific index that is characteristic of the specific application, for example for the detection of the oil level, or specific for the calculation of the percentage of bubbles detected, or specific for the calculation of the percentage of drops detected, or specific for the calculation of the relative moisture; this software is configured to send as output the data in digital format.
The monitoring system 10 according to the invention is schematically shown in Figure 2 in a first application thereof for the detection of non-condensed refrigerant gas.
With the digital camera 19 the shoot is made of the flow of refrigerant fluid in the liquid state FL, possibly with the presence of air/vapour bubbles B.
The electronic control unit 21 processes the video images with dedicated hardware and software for the recognition and quantification of the bubbles B. For example, the measurement operation involves acquiring digital video and recognising bubbles within the acquired frames; as an output the system provides the video image and an index, which with regard to the bubbles, for example, is a percentage value of bubbles detected over the total surface area of the scanned area.
The collected and coded data are transmitted to a PLC for processing thereof and/or to a supervisor for being read by an operator.
The monitoring system according to the invention, indicated with 110 in Figure
3, is schematically shown therein for the detection of drops of non-evaporated refrigerant fluid GL, i.e. in the liquid state, in the flow of refrigerant fluid in the gaseous state FG.
The detection device 16 is mounted on the transparent inspection wall 13 in order to make, with the digital camera 19, the shoot of the flow of the gas FG, possibly with the presence of drops of liquid GL.
The electronic control unit 21 processes the video images with dedicated hardware and software for the recognition and quantification of drops of liquid GL.
The collected and coded data are transmitted to a PLC for processing thereof and/or to a supervisor for being read by an operator.
The monitoring system according to the invention, indicated with 210 in Figure
4, is schematically shown therein for the detection of the presence of moisture in a flow of refrigerant fluid in the gaseous state FG.
In this case, the detection device 16 is applied to a tubular inspection element 111 consisting of a moisture indicator, i.e. comprising, in the centre of the inspection chamber 125, an optical moisture indicator component 140 configured to change its colour depending on the degree of moisture of the gaseous fluid crossing it.
The detection device 16, via the digital camera 19, films the optical moisture indicator component 140.
The electronic control unit 21 processes the video images with dedicated hardware and software for colour recognition of the optical moisture indicator component 140 and the relative accounting of the moisture rate.
The collected and coded data are transmitted to a PLC for processing thereof and/or to a supervisor for being read by an operator.
The monitoring system according to the invention, indicated with 310 in Figure 5, is schematically shown therein for the detection of the oil level OL at the bottom of a collection base 311.
In this case, the detection device 16 is applied to a transparent inspection wall 313 of the collection base 311.
The detection device 16, via the digital camera 19, films the oil level.
The electronic control unit 21 processes the video images with dedicated hardware and software for oil level recognition and relative accounting as a percentage over the total height detected.
The collected and coded data are transmitted to a PLC for processing thereof and/or to a supervisor for being read by an operator.
The invention also relates to the detection device 16 as such, as described above, i.e. comprising:
- a box-like body 17, of containment, having a coupling opening 18 configured for connection with the transparent inspection wall 13;
- a digital camera 19 placed inside the box-like body 17, configured and positioned to make a shoot in the direction of the transparent inspection wall 13, i.e. to make a shoot towards the transparent inspection wall 13;
- lighting means 20 placed inside the box-like body 17, configured to illuminate the transparent inspection wall 13;
- an electronic control unit 21 connected to the digital camera 19 and to the lighting means 20. All components of the detection device 16 are to be understood as described above.
The invention also relates to a refrigeration plant 50, comprising a circuit 51 for a refrigerant fluid; a similar cooling plant 50 is schematically shown in Figure 6. This circuit 51 comprises:
- a condenser 52,
- an expansion valve 53 downstream of said condenser 52,
- an evaporator 54 downstream of said expansion valve 53,
- a compressor 55 between evaporator 54 and condenser 52,
- an outlet 54b of said evaporator 54 and an inlet 52a of said condenser 52 being connected by a line of the vapour 56 comprising said compressor 55, said refrigerant fluid crossing said line of the vapour 56 in a vapour state,
- an outlet 52b of said condenser 52 and an inlet 54a of said evaporator 54 being connected by a line of the liquid 57 comprising said expansion valve 53, said refrigerant fluid crossing said line of the liquid 57 in a liquid state.
The peculiarity of the refrigeration plant 50 according to the invention lies in the fact that it comprises at least one monitoring system 10 as described above, positioned in at least one of the following points of the circuit:
- upstream of said expansion valve 53, for the detection of any bubbles in the refrigerant fluid in the liquid state,
- between said evaporator 54 and said compressor 55, for the detection of any drops in the refrigerant fluid in the vapour state,
- on the compressor 55 or on a derivation thereof, for the detection of the oil level in the same compressor 55.
Preferably, the plant 50 comprises a monitoring system 10 upstream of the expansion valve 53.
The plant 50 may alternatively comprise a monitoring system 110 between evaporator 54 and compressor 55.
The plant 50 may comprise a monitoring system 310 on the compressor 55 or on a derivation thereof.
Practically, it has been established that the invention achieves the intended task and objects.
In particular, the invention develops a detection device for monitoring the state of a fluid in a conduit, and a system for monitoring the state of a fluid in a conduit, particularly for refrigeration circuits, which detection device allows the optical detection by a human operator to be replaced with the acquisition of images by means of a digital camera and with the processing of the acquired images in order to show, by means of a display or data acquisition system:
- the digitised image and/or video of the fluid during operation of the refrigeration plant to which the system is applied;
- the extrapolated data, from the video acquisition, which characterize the states (level, moisture, presence of bubbles) of the fluid: measurement of the level of oil, moisture rate, number (absolute or percentage) of bubbles present in the crossing fluid.
This data, either video or numerical, can then be acquired by control or supervision systems to monitor the state of the fluid, implement new regulation functions or activate specific alarms to preserve the correct operation of the refrigeration plant to which the system according to the invention is applied.
The advantage of digitising and enhancing the images by creating characterization parameters of the images themselves allows this information to be integrated into the regulation of the refrigeration plant and/or be sent remotely to operators for a verification and management thereof.
The detection and image processing device 16 is mounted on an inspection glass; this device is to be understood as consisting of:
- a digital camera closed in a protective box, i.e. the container of the device;
- one or more LED or infrared illuminators for illuminating the chamber;
- an electronic board PCB with microcontroller for video acquisition and data processing;
- a cable of connection to the controller of the refrigeration plant or to the signal acquisition device or to the supervisor with user interface;
- an image acquisition, processing software for the calculation of the specific characteristic index (oil level, percentage of bubbles detected, percentage of drops detected, relative moisture, all typical of the critical state of the chosen fluid), sending as output the relative data in digital format.
In particular, a system has been developed with the invention that allows the state of a refrigerant fluid to be continuously inspected even in the case in which the transparent inspection wall is positioned in a position that a human operator cannot reach.
In addition, a system has been developed with the invention that allows a continuous inspection of a refrigerant fluid remotely through a user interface device (Personal Computer), therefore even in the absence of a human operator near the refrigeration plant to which the system is applied.
The immediate digitisation, the processing and the sending of signals to a PLC allow to activate an automatic and real-time control of the data themselves, and possibly to activate the devices connected to the PLC itself for a corrective action or the sending of an alarm signal.
Converting images into digital in a continuous manner through an acquisition system allows to historicize the state of the refrigerant fluid, or of the lubricating oil, and to analyse the related database as a post-process.
The sensor acquires and processes the images in the same way and according to a precise and validated calculation, in this way the measurements are repeatable and the consequent analysis will be quantitative.
The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; moreover, all the details may be replaced by other technically equivalent elements.
In practice, the components and materials used, as well as the dimensions and shapes, as long as they are compatible with the specific use, can be any according to requirements and the prior art.
Where the characteristics and techniques mentioned in any claim are followed by reference marks, such reference marks are intended to be affixed solely for the purpose of increasing the intelligibility of the claims and consequently such reference marks have no limiting effect on the interpretation of each element identified by way of example by such reference marks.

Claims

1 ) Detection device (16) for monitoring the state of a fluid in a conduit, characterized in that it comprises:
- a box-like body (17) of containment, having a coupling opening (18) configured for connection with a transparent inspection wall (13) of a tubular inspection element (11);
- a digital camera (19) placed inside said box-like body (17), configured and positioned to make a shoot in the direction of said transparent inspection wall (13);
- lighting means (20) placed inside said box-like body (17), configured to illuminate said coupling opening (18);
- an electronic control unit (21 ) connected to said digital camera (19) and to said lighting means (20).
2) Detection device (16) according to claim 1 , characterized in that said lighting means (20) placed inside the box-like body (17) comprise at least one emitter element facing the coupling opening (18).
3) Detection device (16) according to claim 2, characterized in that said lighting means (20) comprise two LEDs (31 , 32) positioned on either sides of the digital camera (19).
4) Detection device (16) according to claim 1 , characterized in that said electronic control unit (21 ) supports said digital camera (19) and said lighting means (20).
5) Detection device (16) according to one or more of the preceding claims, characterized in that said box-like body (17) defines a shield against the light coming from the environment.
6) Detection device (16) according to one or more of the preceding claims, characterized in that the coupling opening (18) is coaxial with the axis (X) of the digital camera (19).
7) Detection device (16) according to one or more of the preceding claims, characterized in that said LEDs (31 ) and (32) are positioned symmetrically on either sides of said digital camera (19).
8) Detection device (16) according to one or more of the preceding claims, characterized in that said electronic control unit (21 ) comprises an electronic board PCB having a micro-controller for image acquisition and for data processing, said electronic control unit (21 ) comprising an image acquisition and processing software for the calculation of a specific index that is characteristic of a specific application, for example for the detection of the oil level, or specific for the calculation of the percentage of bubbles detected, or specific for the calculation of the percentage of drops detected, or specific for the calculation of the relative moisture, said software being configured to send as output data in digital format.
9) Monitoring system (10) for monitoring the state of a fluid in a conduit, particularly for refrigeration circuits, comprising a tubular inspection element (11 ), comprising in turn:
- a central body (12), within which a tubular passage conduit (26) is defined, said central body (12) comprising a transparent inspection wall (13);
- two opposite joining ends (14, 15) developing from said central body (12), characterized in that it comprises a detection device (16), comprising in turn:
- a box-like body (17) of containment, having a coupling opening (18) configured for connection with said transparent inspection wall (13);
- a digital camera (19) placed inside said box-like body (17), configured and positioned to make a shoot in the direction of said transparent inspection wall (13);
- lighting means (20) placed inside said box-like body (17), configured to illuminate said transparent inspection wall (13);
- an electronic control unit (21 ) connected to said digital camera (19) and to said lighting means (20).
10) Monitoring system (10) according to claim 9, characterized in that said tubular inspection element (11 ) is a liquid indicator, or a moisture indicator, or an oil level indicator.
11 ) Monitoring system (10) according to claim 9, characterized in that said transparent inspection wall (13) comprises a collar (23) protruding from the central body (12) of the tubular inspection element (11 ), inside said collar (23) there being a transparent window (24), said transparent window (24) being sealed to said collar (23).
12) Monitoring system (10) according to one or more of claims 9 to 11 , characterized in that at said transparent inspection wall (13) there is defined a viewing chamber (25) with radial dimensions greater than a passage conduit (26) in which the refrigerant fluid passes.
13) Monitoring system (10) according to one or more of the preceding 14 claims 9 to 12, characterized in that said coupling opening (18), configured for connection with the transparent inspection wall (13), is defined by a through hole made on the box-like body (17), shaped so as to couple with the collar (23) of said transparent inspection wall (13).
14) Monitoring system (10) according to one or more of the preceding claims 9 to 13, characterized in that it is configured for the detection of non-condensed refrigerant gas, by filming, through said digital camera (19), the flow of refrigerant fluid in the liquid state (FL), possibly with the presence of air/vapour bubbles (B), said electronic control unit (21 ) being adapted to process the video images with dedicated hardware and software for the recognition and quantification of said bubbles (B).
15) Refrigeration plant (50), comprising a circuit (51 ) for a refrigerant fluid, said circuit (51 ) comprising:
- a condenser (52),
- an expansion valve (53) downstream of said condenser (52),
- an evaporator (54) downstream of said expansion valve (53),
- a compressor (55) between evaporator (54) and condenser (52),
- an outlet (54b) of said evaporator (54) and an inlet (52a) of said condenser (52), the outlet and the inlet being connected by a line of the vapour (56) comprising said compressor (55), and said refrigerant fluid crossing said line of the vapour (56) in a vapour state;
- an outlet (52b) of said condenser (52) and an inlet (54a) of said evaporator (54), the outlet and the inlet being connected by a line of the liquid (57) comprising said expansion valve (53), and said refrigerant fluid crossing said line of the liquid (57) in a liquid state, the refrigeration plant (50) being characterized in that it comprises at least one monitoring system (10) according to one or more of claims 9 to 14, positioned in at least one of the following points of the circuit:
- upstream of said expansion valve (53), for the detection of any bubbles in the refrigerant fluid in the liquid state;
- between said evaporator (54) and said compressor (55), for the detection of any drops in the refrigerant fluid in the vapour state;
- on the compressor (55) or on a derivation thereof, for the detection of the oil level in the same compressor (55).
PCT/IB2022/060137 2021-10-21 2022-10-21 Detection device for monitoring the state of a fluid in a conduit and system for monitoring the state of a fluid in a conduit, particularly for refrigeration circuits WO2023067567A1 (en)

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Application Number Priority Date Filing Date Title
IT102021000027038 2021-10-21
IT102021000027038A IT202100027038A1 (en) 2021-10-21 2021-10-21 DETECTION DEVICE FOR MONITORING THE STATE OF A FLUID IN A DUCT AND SYSTEM FOR MONITORING THE STATE OF A FLUID IN A DUCT, PARTICULARLY FOR REFRIGERATION CIRCUITS

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180038179A1 (en) * 2016-08-04 2018-02-08 J. M. Canty, Inc. Mud flow monitoring devices and methods
WO2019202129A1 (en) * 2018-04-19 2019-10-24 Castrol Limited Apparatus and method for fluid analysis
JP2020003166A (en) * 2018-06-29 2020-01-09 日立ジョンソンコントロールズ空調株式会社 Refrigerator oil deterioration determination system, water component contamination determination system, refrigeration cycle device and water component residual inspection method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180038179A1 (en) * 2016-08-04 2018-02-08 J. M. Canty, Inc. Mud flow monitoring devices and methods
WO2019202129A1 (en) * 2018-04-19 2019-10-24 Castrol Limited Apparatus and method for fluid analysis
JP2020003166A (en) * 2018-06-29 2020-01-09 日立ジョンソンコントロールズ空調株式会社 Refrigerator oil deterioration determination system, water component contamination determination system, refrigeration cycle device and water component residual inspection method

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