Systems and Methods for Detecting Malfunctions in Refrigerant Based Systems based on Changes in Measured System Metrics

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present disclosure claims priority to U.S. Application No. 63/636,615, filed on Apr. 19, 2024, the entire disclosure of which is herein incorporated by reference.

FIELD

The disclosure relates generally to a system for detecting refrigerant performance issues (like leaks) by measuring various metrics of performance of a refrigerant system to infer a change in efficiency. Following, relevant reductions in efficiency serve as a basis for a refrigerant leak or other failure indicator.

BACKGROUND

Minimizing loss of refrigerant (working fluid) from refrigeration, cooling, and heating systems (“refrigeration device”) is of paramount importance to owners and operators. A release of refrigerants into the atmosphere causes significant damage to the environment due to the high ozone depletion and global warming potential of many of these chemicals.

As mandated by regulatory bodies, indoor equipment/mechanical rooms housing refrigeration equipment are equipped with “sniffers,” which are detectors that draw in sample gas from the room and detect trace concentrations of leaked refrigerant. Such detectors, however, require a significant amount of leakage in order to detect a leak. Moreover, for a rooftop or other outdoor refrigeration unit, the detectors are likely unable to detect a leak at all due to ambient movement of air leading to a lack of any leaked refrigerant being collected by the detector.

SUMMARY

In one example, a method is described comprising measuring a plurality of metrics of performance of a refrigeration device, analyzing the plurality of metrics for changes in efficiency of operation of the refrigeration device, and based on the changes in efficiency of operation of the refrigeration device being reductions in efficiency, outputting an indicator of a refrigerant leak and/or failure of components, such as compressors, of the refrigeration device.

In another example, a system is described comprising a temperature sensor externally mounted to a line, of a refrigerant loop, that couples components of a refrigeration device, and a monitoring device, in communication with the temperature sensor, including one or more processors for performing functions of (i) sampling the temperature sensor and generating temperature readings of the line, (ii) analyzing the temperature readings, over time, at start and stop instances of operation of the refrigeration device; and (iii) outputting an indicator of a refrigerant leak of the refrigeration device based on analyzing the temperature readings at start and stop instances of operation of the refrigeration device.

In another example, a method is described comprising sampling a temperature sensor that is externally mounted to a line, of a refrigerant loop, that couples components of a refrigeration device and generating temperature readings of the line, analyzing the temperature readings, over time, at start and stop instances of operation of the refrigeration device, and outputting an indicator of a refrigerant leak of the refrigeration device based on analyzing the temperature readings at start and stop instances of operation of the refrigeration device.

The features, functions, and advantages that have been discussed can be achieved independently in various examples or may be combined in yet other examples. Further details of the examples can be seen with reference to the following description and drawings.

BRIEF DESCRIPTION OF THE FIGURES

Examples, objectives and descriptions of the present disclosure will be readily understood by reference to the following detailed description of illustrative examples when read in conjunction with the accompanying drawings, wherein:

FIG. 1 illustrates a system for detecting refrigerant leaks based on changes in measured system metrics, according to an example implementation.

FIG. 2 illustrates another example of the system for detecting refrigerant leaks based on changes in measured system metrics, according to an example implementation.

FIG. 3 illustrates another example of the system for detecting refrigerant leaks based on changes in measured system metrics, according to an example implementation.

FIG. 4A illustrates an example plot of temperature readings over time from temperature sensors, according to an example implementation.

FIG. 4B illustrates an example plot of a rate of change of temperature readings over time from temperature sensors, according to an example implementation.

FIG. 5 illustrates another example of the system for detecting refrigerant leaks based on changes in measured system metrics, according to an example implementation.

FIG. 6 is a flowchart illustrating an example of a method for detecting refrigerant leaks based on changes in measured system metrics, according to an example implementation.

FIG. 7 is a flowchart illustrating an example of a method for detecting temperature changes of components of a refrigeration device as a basis for indicating a refrigerant leak, according to an example implementation.

FIG. 8 illustrates a block diagram of a computing device, according to an example implementation.

DESCRIPTION OF THE EMBODIMENTS

Disclosed examples will now be described more fully hereinafter with reference to the accompanying drawings. Several different examples are described and should not be construed as limited to all possible alternatives. Rather, these examples are described so that this disclosure is thorough and complete and fully conveys a scope of the disclosure to those skilled in the art.

Referring now to the figures, FIG. 1 illustrates a system for detecting refrigerant leaks (or other failures or reduced performance of the system) based on changes in measured system metrics, according to an example implementation. The system 100 includes one or more sensors 102 coupled to a component or multiple components of a refrigeration device 104, and a monitoring device 106, in communication with the sensors 102, including one or more processors for performing functions of (i) sampling the sensors and generating readings, (ii) analyzing the readings for changes in efficiency of operation of the refrigeration device, and (iii) based on changes in efficiency of operation of the refrigeration device being reductions in efficiency, outputting an indicator of a refrigerant leak (or other failures or reduced performance) of the refrigeration device. As an example, various metrics of performance of the refrigeration device are analyzed to infer a change in efficiency. Following, relevant reductions in efficiency serve as a basis for a refrigerant leak indicator (or other failures or reduced performance of the system).

Although shown in the illustration in FIG. 1 of the system 100, the refrigeration device 104 itself is being monitored and, in some examples, is not an element of the system 100.

In one example, the refrigeration device 104 is an air conditioning unit. In another example, the refrigeration device 104 is a heat pump. The refrigeration device 104 can take a number of other forms as well, such as refrigerators, automotive air conditioning units, freezers, etc. The system 100 operates to monitor the refrigeration device 104 for early detection of refrigerant leaks or reduced performance. High frequency sampling of the sensors 102 enables a longitudinal analysis of starts and stops (when the refrigeration device 104 turns on and turns off) to identify changes in operation of the refrigeration device 104 over time.

The monitoring device 106 includes a data acquisition unit 108 to sample the sensors 102, a computing device 110 to process data received from the sensors 102 to generate temperature readings of the line, and a communication module 112 coupled to the computing device 110 to transmit and receive data to and from a network 114. Details of the computing device 110 and communication module 112 are described below with reference to FIG. 8.

The network 114 can include a local area network (LAN), a wide area network (WAN), or the Internet. Communications between the monitoring device 106 and the network 114 can be direct via wired or wireless communications.

In addition, in other examples, the monitoring device 106 further includes a battery to supply power to components of the monitoring device 106.

In one example, the monitoring device 106 performs on board the monitoring device 106 the analyzing of the readings, over time, at start and stop instances of operation of the refrigeration device, and outputting of the indicator of a refrigerant leak of the refrigeration device based on analyzing the readings at start and stop instances of operation of the refrigeration device. The monitoring device 106 outputs the indicator to the communication module 112 for transmission over the network 114.

In another example, the monitoring device 106 samples the sensors 102 and sends data received from the sensors 102 over the network for cloud processing including generating and analyzing the readings, and outputting of the indicator of a refrigerant leak or malfunction of the refrigeration device based on analyzing the readings at start and stop instances of operation of the refrigeration device.

Within examples, the system 100 collects measurement outputs from the sensors 102, using a variety of sensing methods, and maps the measurement outputs or collection of measurement outputs to efficiency levels and/or system performance of the refrigeration device 104. Following, relevant changes in efficiency that include either observations of transient changes or trend level changes over time, are identified and can serve as a basis for a refrigerant leak indicator. Particularly, when the efficiency changes are a reduction in efficiency, the refrigerant leak indicator is output.

The system 100 collects measurement outputs from the sensors 102 for a sensor-fusion analysis in which a combination of different measurements are analyzed to determine the measurement of efficiency, for example. In one example, some measurements are direct measurements of system performance of the refrigeration device 104, and some measurements are indirect measurements of performance of the refrigeration device 104.

An example measurement of performance of the refrigeration device 104 includes measuring a temperature of the refrigerant directly in the system. Another example includes measuring a line (e.g., the tube containing refrigerant) of a refrigerant loop that couples components of the refrigeration device. Another example measurement of performance of the refrigeration device 104 includes measuring a power usage of the refrigeration device. Another example measurement of performance of the refrigeration device 104 includes measuring a pressure of refrigerant in a line of the refrigeration device (e.g., static pressure of refrigerant where a leak results in a pressure reduction or change in behavior of pressure). Still other example measurements of performance of the refrigeration device 104 include measuring a vibration or acoustics of the refrigerant device 104, measuring an amount of refrigerant in gas collected in an environment of the refrigerant device 104, capturing thermal images of a portion of the refrigerant device 104, performing spectral analysis of one or more components of the refrigerant device 104, and measuring a condensation of one or more components of the refrigerant device 104. Any number or combination of measurements of performance of the refrigeration device 104 are used to determine an efficiency of the refrigeration device 104. From the efficiency levels over time (either over short time periods or longer time periods enabling trend lines), when a reduction in efficiency is determined, the monitoring device 106 outputs the refrigerant leak or reduced performance indicator.

FIG. 2 illustrates another example of the system 100 for detecting refrigerant leaks based on changes in measured system metrics, according to an example implementation. FIG. 2 illustrates the system 100 in an example in which the sensors 102 include temperature sensors 102a-d, and the system detects temperature changes of components of the refrigeration device 104 as a basis for indicating a refrigerant leak. In particular, the system 100 includes the temperature sensors 102a-d externally mounted to a line, of a refrigerant loop, that couples components of a refrigeration device 104, and the monitoring device 106 is in communication with the temperature sensors 102a-d (either via direct wired communication or wireless communication) and performs functions of (i) sampling the temperature sensors 102a-d and generating temperature readings of the line, (ii) analyzing the temperature readings, over time, at start and stop instances of operation of the refrigeration device, and (iii) outputting an indicator of a refrigerant leak of the refrigeration device based on analyzing the temperature readings at start and stop instances of operation of the refrigeration device.

In FIG. 2, the refrigeration device 104 has components including an evaporator 116, a compressor 118, a condenser 120, and a metering/expansion device 122. A suction line 124 connects the evaporator 116 to the compressor 118, a discharge line 126 connects the compressor 118 to the condenser 120, a liquid line 128 connects the condenser 120 to the metering/expansion device 122, and a transport line 130 connects the metering/expansion device 122 to the evaporator 116. A refrigerant loop is created, as shown in FIG. 2, via the components of the refrigeration device 104 interconnected by the various lines.

The system 100 in FIG. 2 is shown to include a plurality of temperature sensors 102a-d, and each of the temperature sensors is mounted externally to one of a plurality of lines 124, 126, 128, 130 of the refrigerant loop that couple components of the refrigeration device 104. Thus, each temperature sensor 102a-d is externally mounted to a different line of the plurality of lines of the refrigerant loop to monitor the refrigerant loop at key locations. The temperature sensors are externally mounted in a manner to be in contact with one of the plurality of lines 124, 126, 128, 130 of the refrigerant loop or at least positioned adjacent to or proximal to one of the plurality of lines 124, 126, 128, 130 of the refrigerant loop such that an accurate temperature reading of the plurality of lines 124, 126, 128, 130 of the refrigerant loop is performed (or of a surface temperature of the plurality of lines 124, 126, 128, 130 of the refrigerant loop).

In one example, the temperature sensor 102a is mounted to the suction line 124 connecting the evaporator 116 to the compressor 118, the temperature sensor 102b is mounted to the discharge line 126 connecting the compressor 118 to the condenser 120, the temperature sensor 102c is mounted to the liquid line 128 connecting the condenser 120 to the metering/expansion device 122, and the temperature sensor 102d is mounted to the transport line 130 connecting the metering/expansion device 122 to the evaporator 116.

The temperature sensors 102a-d are in communication with the data acquisition unit 108 of the monitoring device 106 via data lines 132a-d. The data lines 132a-d are hard-wired communication lines enabling data transmission, for example.

FIG. 3 illustrates another example of the system 100 for detecting refrigerant leaks based on changes in measured system metrics, according to an example implementation. In FIG. 3, the monitoring device 106 includes a short range communication module 134, which includes a transmitter, a receiver, or circuitry for performing transmission and reception of data. Within examples, the short range communication module 134 communicates wirelessly with the temperature sensors 102a-d using Wi-Fi communications (e.g., IEEE 802.11 standard protocol) or using Bluetooth® communications (e.g., device-to-device communications). In this regard, the short range communication module 134 is a wireless communication unit to wirelessly communicate with the temperature sensors 102a-d to sample the temperature sensors 102a-d.

Thus, within examples, the temperature sensors 102a-d also include short range communication modules, similar to the monitoring device 106, to communicate wirelessly with the monitoring device 106.

Within examples, the monitoring device 106 samples the sensors 102 (or the plurality of temperature sensors 102a-d in one example) and generates readings of the respective lines, analyzes the temperature readings, over time, at start and stop instances of operation of the refrigeration device 104, and outputs an indicator of a refrigerant leak of the refrigeration device 104 based on analyzing the temperature readings at start and stop instances of operation of the refrigeration device.

Refrigerant is a cooling agent that absorbs heat and leaves cool air behind when passed through the compressor 118 and evaporator 116. There are many types of refrigerant, such as chlorofluorocarbons (CFC), hydrochlorofluorocarbons (HCFC), or hydrofluorocarbons (HFC). The refrigerant fluctuates between a liquid or gas state as the refrigerant undergoes a thermodynamic process. When operated as an air conditioning or cooling unit, the refrigeration loop removes unwanted heat from one place and discharges the heat into another place. To accomplish this, the refrigerant is pumped through the refrigeration device 104, which is a closed refrigeration system. Because the system is closed, the same refrigerant is used repeatedly, as the refrigerant passes through the refrigerant loop removing some heat and discharging heat. The closed loop serves other purposes as well, and the loop keeps the refrigerant from becoming contaminated and from entering the external environment and atmosphere.

In general, the refrigeration device 104 operates by the metering/expansion device 122 (e.g., which includes a thermal expansion valve, a capillary tube, or any other device to control flow of refrigerant into the evaporator 166) beginning a cycle with the refrigerant in a low-pressure, low-temperature state. The refrigerant passes through the transport line 130 to the evaporator 116 and expands and evaporates (changes state) when passing through the evaporator 116, where the refrigerant removes heat from a substance or space in which the evaporator 116 is located. Heat will travel from a warmer substance to the evaporator 116 cooled by evaporation of the refrigerant within the system, causing the refrigerant to “boil” and evaporate, changing the refrigerant to a vapor. This low-pressure, low-temperature vapor is drawn to the compressor 118, through the suction line 124 where the vapor is compressed into a high-temperature, high-pressure vapor. The compressor 118 discharges the vapor through the discharge line 126 to the condenser 120, so that the vapor can release heat. The refrigerant vapor is at a higher temperature than the air passing across the condenser 120 (air-cooled type) or water passing through the condenser 120 (water-cooled type), and therefore, that is transferred from the warmer refrigerant vapor to the cooler air or water. In this process, as heat is removed from the vapor, a change of state takes place and the vapor is condensed back into a liquid, at a high-pressure and high-temperature. The liquid refrigerant travels through the liquid line 128 back to the metering/expansion device 122 where the refrigerant passes through a small opening or orifice and a drop in pressure and temperature occurs, and then the refrigerant makes is passed into a large opening of the evaporator 116 tubing or coil (to be vaporized), and ready to start another cycle through the system.

There are many different kinds and variations of the refrigeration cycle components. Variations of the refrigeration device 104 are possible and the refrigeration device 104 can take many forms, such as a refrigerator, a freezer, an air conditioning system, an industrial chiller, or commercial cooling equipment, for example. In addition, when the refrigerant cycle is operated in a reverse manner, the refrigeration device 104 is considered a heat pump. For example, in heat pump systems, refrigerant flow is reversed, allowing the system to pump heat into a location.

The refrigeration device 104 uses the lines to connect the components, and the lines are tubing to enable transfer of the refrigerant in fluid or gas form so that the refrigerant will not leak out into the atmosphere. However, the refrigeration device 104 can exhibit leaks of refrigerant due to various reasons, and it is desirable to detect such leaks to prevent the refrigerant from entering the environment.

In the example shown in FIGS. 2-3, the monitoring device 106 generates temperature readings of the various lines in the refrigeration device 104 on a basis of a surface temperature measurement of a surface of the line, from data output from the temperature sensors 102a-d, in order to determine and output an indicator of a refrigerant leak of the refrigeration device 104. The surface temperature measurement results from the temperature sensors 102a-d being mounted in contact with the line, adjacent to the line, or proximal to the line, for example. The temperature sensors 102a-d are sampled rapidly, such as at high frequency rates above 10 Hz, to gain readings that capture changes occurring over various operation states of the refrigeration device 104 as refrigerant travels through the refrigerant loop. For example, each start and stop instance of the refrigeration device 104 is analyzed closely, and plots are generated of the temperature readings at those instances. Various factors including first and second order derivatives are calculated and compared over time to identify changes in temperature readings. A change in a temperature reading either over a threshold amount of temperature change (such as 1.25 times the baseline value) or occurring over a threshold amount of time (such as occurring once or more per day for 5 days in a row) has been shown to be an indicator of a refrigerant leak of the refrigeration device 104.

In one example, the compressor 118 also includes a vibration or acoustic sensor 136 (e.g., in one instance in a form of ultrasonic sensing) coupled to or nearby the compressor 118 to output data to the monitoring device 106 (e.g., using wireless communication) indicative of a status of operation of the compressor 118. For instance, upon starting or stopping operation, the compressor 118 will exhibit a mechanical vibration detectable by the vibration sensor 136. In other embodiments, the acoustic sensor 136 can directly detect signals or make measurements indicator of leakage of refrigerant through a small orifice.

For start and stop purposes, the monitoring device 106 maps a time of occurrence of the vibration detection to sampled temperature readings from the temperature sensors 102a-d to mark instances of each start and stop operation of the refrigeration device 104. The timings for starting and stopping of operation are important as refrigerant flows through the refrigeration device 104 between a start and stop time.

Over time, an analysis of the temperature readings via comparison at the start and stop time, which are indicative of temperatures of the lines with refrigerant of a transient behavior when the system is changing, illustrate a trend of data. When the trend of data consistently moves in one direction, a prediction that an amount of refrigerant in the system has changed can be made.

In another example, an analysis of the temperature readings via comparison at the start and stop time that indicates a sudden change in temperature has been shown to be related to how much refrigerant is in the system (based on thermodynamic effect), and when the temperature change is above a threshold amount, an indicator that the system has experienced a refrigerant leak is issued.

FIG. 4A illustrates an example plot of temperature readings over time from temperature sensors, according to an example implementation. FIG. 4B illustrates an example plot of a rate of change of temperature readings over time from temperature sensors, according to an example implementation.

In FIGS. 4A-4B, the temperature readings are from the temperature sensor 102c mounted to the liquid line 128 before the metering/expansion device 122 under two separate conditions in which the refrigeration device 104 is operated as an air conditioning device. A first temperature series 140 includes temperature readings with the refrigeration device 104 at full refrigerant load, and a second temperature series 142 includes temperature readings with the refrigeration device 104 that has had a refrigerant load intentionally reduced.

In FIG. 4A, a more gradual rise or slower rise in temperature is seen after start up, before the metering valve, in the condition in which the refrigeration device 104 has undergone “leakage” or reduction in refrigerant. FIG. 4A illustrates this occurrence in which the first temperature series 140 reaches 34° C. sooner than the second temperature series 142.

In FIG. 4B, evidence of leakage is also identified in an initial rate of change of the temperature readings (e.g., first derivative) as start/stop events occur. FIG. 4B illustrates the occurrence in which the second temperature series 142 starts a change in temperature more quickly than the first temperature series 140 starts a change in temperature.

The plots shown in FIGS. 4A-4B include example analysis of temperature readings from a temperature sensor mounted to a surface of a line in a refrigerant loop of a refrigeration device in which indicators for a refrigerant leak are determined.

In other examples, other types of data analysis of temperature readings can be a basis for outputting the indicator for a refrigerant leak. As one example, a steep drop in temperature (e.g., high negative slope) during operation is an indicator for a refrigerant leak

With data sampling of the temperature sensors occurring at a high frequency, a high level of granularity is observable to see behavioral changes that do not last too long during operation of the refrigeration device 104, and thus, even a small leak can be detected such as occurs at an early stage of a leak (e.g., early stages of a mechanical issue with the refrigeration device). Thus, changes measured in temperature readings from any or all of the temperature sensors 102a-d are analyzed and compared, either at instantaneous times or over a time period, and are used as metrics of performance of the refrigeration device 104 that can be analyzed for changes in efficiency of operation of the refrigeration device 104.

The various channels of data may be combined for further analysis. For instance, the difference between temperature at two different points, as normalized by a third point in time may yield a synthetic metric that when analyzed for anomaly patterns can identify malfunctions.

FIG. 5 illustrates another example of the system 100 for detecting refrigerant leaks based on changes in measured system metrics, according to an example implementation. In FIG. 5, gas collection devices 144a-d are mounted proximal to connection points of components of the refrigeration device 104, such as adjacent to the evaporator 116, the compressor 118, the condenser 120, and the metering/expansion device 122. The gas collection devices 144a-d are positioned at localized sampling points in the refrigeration device 104, and connect via lines/tubing to a pump 146 of the monitoring device 106. The pump 146 operates to collect gas in a vicinity of the gas collection devices 144a-d, and passes collected gas to a gas detecting sensor module 148, which includes sensors to detect whether refrigerant is present in the collected gas, and when present, to determine at least an approximate measurement of how much refrigerant is present over a time period. The gas detecting sensor module 148 outputs data indicating an amount of refrigerant in the collected gas to the computing device 110.

The computing device 110 uses the data received from the gas detecting sensor module 148 as a primary basis, secondary basis, or in combination with the temperature readings to generate performance or efficiency measurements of the refrigeration device 104 where analysis or trends of a reduction in efficiency cause output of an indicator of a refrigerant leak. Thus, changes measured in an amount of refrigerant detected in gas by the gas detecting sensor module 148 are analyzed and compared, either at instantaneous times or over a time period, and are used as metrics of performance of the refrigeration device 104 that can be analyzed for changes in efficiency of operation of the refrigeration device 104.

In one example, the gas collection devices 144a-d offer a way to verify whether the analysis of the temperature readings indicating a refrigerant leak is more likely than not. In another example, the temperature sensors 102 offer a way to verify whether an analysis of the readings from the gas collection devices 144a-d indicating a refrigerant leak is more likely than not. In either manner, a combination of measurement readings from various sensors enables an efficiency of the refrigeration device 104 to be determined that serves as a basis for indicating a refrigerant leak.

In yet another example, an analysis of power consumption of the refrigeration device 104 over time is performed to generate a metric of performance of the refrigeration device 104 useful for determination of changes in efficiency of operation. For example, a sudden change in instantaneous power consumption for a non-variable heat pump is related to an amount of refrigerant in the system (based on thermodynamic effects). When a change in power consumption exceeds a certain threshold, the change in power consumption is then useful for an indicator that the system has experienced a refrigerant leak.

To analyze the power consumption, the monitoring device 106, and specifically the data acquisition unit 108, is in communication with a power source that supplies power to the refrigeration device 104 (or in communication with a power meter connected to the power source) to receive data representative of power consumption by the refrigeration device 104. In some examples, current and voltage monitors attached to the refrigeration device 104 collect continuous power consumption data and output the power consumption data on a continuous basis to the monitoring device 106. The data can be real-time power consumption data, or data on a daily, weekly, or monthly basis according to a billing cycle, for example.

In yet another example, an analysis of pressure of refrigerant in a line of the refrigeration device 104 is performed to generate a metric of performance of the refrigeration device 104 useful for determination of changes in efficiency of operation. For example, a temperature of the suction line 124 and of the liquid line 128, along with a low and a high pressure of the system—commonly referred to as superheat and subcooling—indicates that the system has experienced a refrigerant leak.

To analyze pressure of the system, pressure sensors positioned in the lines of the refrigeration device 104, such as in the suction line 124 and/or in the liquid line 128, output measurements to the data acquisition unit 108 of the monitoring device 106. The data can be real-time pressure data output during operation of the refrigeration device 104, for example.

In one instantiation, measurements to analyze the vibrations of the compressor 118 in the refrigeration device 104 are used to generate a metric of performance of the refrigeration device 104 useful for determination of changes in efficiency of operation. The vibration sensor 136 (e.g., a piezoelectric sensor) is placed directly on or near the compressor 118. The vibration sensor 136 provides real-time vibration data during operation of the compressor 118. A frequency analysis of this data (e.g., Fourier analysis) is conducted to identify a fundamental frequency and its harmonics. Changes in these frequencies over time can indicate variations in system efficiency or developing failure modes.

In some examples, to analyze temperature variations at different locations along the refrigerant loop, a concept of continuous temperature sensing is implemented through the use of an array of temperature sensors, such as a thermopile array or a microbolometer as in a thermal camera, to record temperature changes over time. The captured temperature data is then processed and analyzed using a machine learning algorithm (as in method 200 described below) to generate a metric of performance of the refrigeration device 104 useful for determination of changes in efficiency of operation.

In other examples, methods to indirectly measure temperature of components could also be used. For example, application of a thermally sensitive paint or dye can be made to components of the refrigeration device 104, and then imaging of such components can be made using a photodetector or array of photodetectors (such as a CCD or CMOS device). Output images captured that include changes to color are interpreted as an increase in the spatial resolution of temperature measurements and, when calibrated, are used to replace traditional temperature measurements.

Thermal imaging (e.g., through a plurality of temperature sensors such as a thermopile array, a cooled detector, or a microbolometer), may also be used to directly detect leaks of refrigerant gas from the closed loop system by measuring the significant temperature and/or emissivity changes due to leaking refrigerant.

In still other examples, for the direct detection of refrigerant gas in the environment around a refrigerant based device, use of ultraviolet, infrared, or visible spectroscopy may be employed. Direct detection of leaked working fluid, especially when combined with other efficiency metrics, increases the efficacy of the detection methodology. For these examples, infrared or UV cameras or photodetectors are positioned proximate components of the refrigeration device 104 to capture images.

In still other examples, measuring condensation of components of the refrigeration device 104 is performed to generate a metric of performance of the refrigeration device 104 useful for determination of changes in efficiency of operation. Condensation is measured using moisture, humidity and/or temperature sensors mounted on the linesets of the refrigerant loop, and can indicate a potential formation of ice. Ice buildup on the vapor line directly impacts the efficiency of the outdoor coil in a refrigeration system by restricting heat exchange between the refrigerant coil and the surrounding air or water.

FIG. 6 is a flowchart illustrating an example of a method 200 for detecting refrigerant leaks based on changes in measured system metrics, according to an example implementation. Method 200 shown in FIG. 6 presents an example of a method that could be used with or performed by the system 100 in FIGS. 1-3 and FIG. 5, and the monitoring device 106 described herein.

Within examples, devices or systems described herein are used or configured to perform logical functions presented in FIG. 6. In some instances, components of the devices and/or systems are configured to perform the functions such that the components are actually configured and structured (with hardware and/or software) to enable such performance. In other examples, components of the devices and/or systems are arranged to be adapted to, capable of, or suited for performing the functions, such as when operated in a specific manner. Method 200 includes one or more operations, functions, or actions as illustrated by one or more of blocks 202-206. Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. In addition, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.

It should be understood that for this and other processes and methods disclosed herein, flowcharts show functionality and operation of one possible implementation of present examples. In this regard, some blocks or portions of blocks may represent a module, a segment, or a portion of program code, which includes one or more instructions executable by a processor for implementing specific logical functions or steps in the process. The program code may be stored on any type of computer readable medium or data storage, for example, such as a storage device including a disk or hard drive. Further, the program code can be encoded on a computer-readable storage media in a machine-readable format, or on other non-transitory media or articles of manufacture. The computer readable medium includes non-transitory computer readable medium or memory, for example, such as computer-readable media that stores data for short periods of time like register memory, processor cache and Random Access Memory (RAM). The computer readable medium additionally or alternatively includes non-transitory media, such as secondary or persistent long-term storage, like read only memory (ROM), optical or magnetic disks, compact-disc read only memory (CD-ROM), for example. The computer readable media may also be any other volatile or non-volatile storage systems. The computer readable medium may be considered a tangible computer readable storage medium, for example.

In addition, each block or portions of each block in FIG. 6, and within other processes and methods disclosed herein, may represent circuitry that is wired to perform the specific logical functions in the process. Alternative implementations are included within the scope of the examples of the present disclosure in which functions may be executed out of order from that shown or discussed, including substantially concurrent or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art.

At block 202, the method 200 includes measuring a plurality of metrics of performance of a refrigeration device. Within examples, measuring the plurality of metrics of performance of the refrigeration device includes one or more of (in any combination) measuring a temperature of a line, of a refrigerant loop, that couples components of the refrigeration device, measuring a power usage of the refrigeration device, measuring a pressure of refrigerant in a line of the refrigeration device, measuring a vibration of the refrigerant device, measuring an amount of refrigerant in gas collected in an environment of the refrigerant device, capturing thermal images of a portion of the refrigerant device, performing infrared spectroscopy analysis of one or more components of the refrigerant device, measuring a condensation of one or more components of the refrigerant device.

At block 204, the method 200 includes analyzing the plurality of metrics for changes in efficiency of operation of the refrigeration device.

At block 206, the method 200 includes based on the changes in efficiency of operation of the refrigeration device being reductions in efficiency, outputting an indicator of a refrigerant leak or reduced performance of the refrigeration device. In one example, reductions in efficiency are identified based on comparisons against absolute thresholds, or a deviation from baseline performance such as a 10% or greater deviation in a given metric. A change of the subcooling or superheating temperature (as calculated using temperature and pressure readings) can itself trigger a leak indicator.

In examples where the method includes determining a reduced performance of the refrigeration device 104, additional functions include determining a severity level of the reduced performance. For example, the method 200 optionally includes the root cause diagnoses of a detected failure based on one or more of the data sources used in the detection of the failure, comparing sensor data to known failure patterns and physics-based system models, and computing the relative severity of a failure (such as but not limited to the severity of a leak in a refrigerant system) based on the metrics or data sources utilized in the issue detection. A deviation of the detected data as compared to expected data is useful for determination of the severity level, for example.

FIG. 7 is a flowchart illustrating an example of a method 210 for detecting temperature changes of components of a refrigeration device as a basis for indicating a refrigerant leak, according to an example implementation. Method 210 shown in FIG. 7 presents an example of a method that could be used with or performed by the system 100 in FIGS. 1-3 and FIG. 5, and the monitoring device 106 described herein.

Within examples, devices or systems described herein are used or configured to perform logical functions presented in FIG. 7. Method 210 includes one or more operations, functions, or actions as illustrated by one or more of blocks 212-216. Although the blocks are illustrated in a sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. In addition, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation. Some blocks or portions of blocks may represent a module, a segment, or a portion of program code, which includes one or more instructions executable by a processor for implementing specific logical functions or steps in the process. The program code may be stored on any type of computer readable medium or data storage, for example, such as a storage device including a disk or hard drive. Further, the program code can be encoded on a computer-readable storage media in a machine-readable format, or on other non-transitory media or articles of manufacture. The computer readable medium includes non-transitory computer readable medium or memory, for example, such as computer-readable media that stores data for short periods of time like register memory, processor cache and Random Access Memory (RAM). The computer readable medium additionally or alternatively includes non-transitory media, such as secondary or persistent long-term storage, like read only memory (ROM), optical or magnetic disks, compact-disc read only memory (CD-ROM), for example. The computer readable media may also be any other volatile or non-volatile storage systems. The computer readable medium may be considered a tangible computer readable storage medium, for example.

At block 212, the method 210 includes sampling a temperature sensor that is externally mounted to a line, of a refrigerant loop, that couples components of a refrigeration device and generating temperature readings of the line. In one example, sampling the temperature sensor comprises sampling the temperature sensor at a frequency greater than 1 Hz.

At block 214, the method 210 includes analyzing the temperature readings, over time, at start and stop instances of operation of the refrigeration device. In one example, analyzing the temperature readings includes calculating an instantaneous rate of change of the temperature readings. In another example, analyzing the temperature readings includes calculating an amount of a rate of change of the temperature readings.

In still another example, analyzing the temperature readings includes measuring a change of efficiency over time, which can include an analysis of on-board data as well of the refrigeration device 104.

At block 216, the method 210 includes outputting an indicator of a refrigerant leak of the refrigeration device based on analyzing the temperature readings at start and stop instances of operation of the refrigeration device. In examples, all data is communicated to the cloud over the network 114, or targeted sections of the data as relevant is communication, or all data remains on the monitoring device 106.

Within examples, the method 210 additionally includes receiving an ambient temperature of an environment (e.g., outdoor air temperature) of the refrigeration device, and adjusting the efficiency calculations based on the ambient temperature. For instance, efficiency metrics are normalized by dividing by ambient temperature (or the ambient temperature normalized to a given threshold) so that the ambient temperature does not influence the temperature readings more than the given threshold.

Within examples herein, the methods shown in FIGS. 6-7 optionally include additional functions including performing a closed-loop analysis in which instructions are generated to alter operation of the refrigeration device 104 based on the measurements output from the sensors. In one example, the efficiency of the refrigeration device 104 is controllable and/or actively operable to search for leaks in “100% on” mode or similar. Thus, when some sensor measurements are trending toward an indication of a refrigerant leak, the monitoring device 106 outputs instructions (either to a display for manual operation of the refrigeration device 104 or directly to the refrigeration device 104 to automatically operate the refrigeration device 104), and the instructions indicate for a specific operation of the refrigeration device 104, such as to turn on at full capacity, in order to enable the sensors to perform measurements related to specific operation of the refrigeration device 104.

Within examples herein, the methods shown in FIGS. 6-7 also optionally include additional functions for integration to an existing building management system or refrigerant management system that has documented measurements for use or comparison.

Within examples herein, the methods shown may optionally be integrated directly onto the original refrigerant based equipment being monitored, running so-called on-device and utilizing preexisting temperature, pressure and/or power sensors. In this example, the methodologies outlined may be integrated at the time of manufacture of the original equipment.

FIG. 8 illustrates a block diagram of a computing device 220, according to an example implementation. FIG. 8 does not necessarily show all of the hardware and software modules included in the computing device 220, and omits physical and logical connections that will be apparent to one of ordinary skill in the art after review of the present disclosure.

The computing device 220 in FIG. 8 is representative of any of the computing devices, control processors, or modules as described herein (including the computing device 110 shown in FIGS. 1-3 and FIG. 5, for example).

The computing device 220 includes one or more processor(s) 222, and a non-transitory computer-readable media (data storage) 224 storing instructions 226, which when executed by the one or more processor(s) 222, causes the computing device 220 to perform functions (e.g., such as described in the flowcharts of FIGS. 6-7). To perform functions, the computing device 220 includes a communication interface 228, an input interface 230, an output interface 232, and optionally includes a display/touchscreen/status light 234 and a speaker/microphone 236, and each component of the computing device 220 is connected to a communication bus 238. The computing device 220 may also include hardware to enable communication within the computing device 220 and between the computing device 220 and other devices (not shown). The hardware may include transmitters, receivers, and antennas, for example.

The communication interface 228 is a wireless interface and/or one or more wireline interfaces that allow for both short-range communication and long-range communication to one or more networks or to one or more remote devices. Such wireless interfaces provide for communication under one or more wireless communication protocols, Bluetooth, WiFi (e.g., an institute of electrical and electronic engineers (IEEE) 802.11 protocol), Long-Term Evolution (LTE), cellular communications, near-field communication (NFC), and/or other wireless communication protocols. Such wireline interfaces include an Ethernet interface, a serial interface, Universal Serial Bus (USB) interface, or similar interface to communicate via a wire, a twisted pair of wires, a coaxial cable, an optical link, a fiber-optic link, or other physical connection to a wireline network. Thus, the communication interface 228 is configured to receive input data from one or more devices, and configured to send output data to other devices.

The data storage 224 includes or takes the form of memory, such as one or more computer-readable storage media that can be read or accessed by the one or more processor(s) 222. The computer-readable storage media includes volatile and/or non-volatile storage components, such as optical, magnetic, organic or other memory or disc storage, which can be integrated in whole or in part with the one or more processor(s) 222. The non-transitory data storage 224 is considered non-transitory computer readable media. In some examples, the non-transitory data storage 224 is implemented using a single physical device (e.g., one optical, magnetic, organic or other memory or disc storage unit), while in other examples, the non-transitory data storage 224 is implemented using two or more physical devices. The non-transitory data storage 224 thus is a computer readable medium, and instructions 164 are stored thereon. The instructions 226 include computer executable code.

The one or more processor(s) 222 include a special purpose processor (e.g., digital signal processors, application specific integrated circuits, etc.). The one or more processor(s) 222 receives inputs from the communication interface 228 as well as from other components (e.g., the display/touchscreen 234 or the speaker/microphone 236), and processes the inputs to generate outputs that are stored in the non-transitory data storage 224. The one or more processor(s) 222 are configured to execute the instructions 226 (e.g., computer-readable program instructions) that are stored in the non-transitory data storage 224 and are executable to provide the functionality of the computing device 220 described herein.

The input interface 230 is used to enter data or commands and can include, for example, a keyboard, a user pointing device such as, for example, a mouse, a trackball, or a touch pad, or may further include the touchscreen or microphone.

The input interface 230 may also include direct information from the refrigerant device 104, such as a direct serial connection to read error codes, set points, or other registers such as status, indirect methods of determining errors (such as optically reading a status light), or a direct connection to, for example, a building management system or controls network.

The input interface 230 might also gather data from networked or connected data points such as occupancy data or weather data and/or forecasts over the network 114.

The output interface 232 outputs information for reporting or storage in the data storage 224, and thus, the output interface 232 may be similar to the communication interface 228 and can be a wireless interface (e.g., transmitter) or a wired interface as well.

In some instantiations, it is desirable to compute most or all of the parameters to determine system status onboard the computing device 220. In this case, algorithms, such as machine learning algorithms which can be pre-trained or trained on device, can compute these metrics directly and send only representative status over the communication interface 228 using the panoply of sensors to directly and indirectly measure performance on or about the refrigerant device 104.

In other instantiations, little to no processing occurs on device and instead the majority of data is sent directly from computing device 220 over the communication interface 228 into a remote server in the network 114 This remote server could then perform analysis based on algorithms or machine learning algorithms & techniques which can be pre-trained or trained in the cloud. The results of these analyses can then be sent back over the communications interface 228 to, for example, set off the alarm on device or change the status light to a different color.

Different examples of the system(s), device(s), and method(s) disclosed herein include a variety of components, features, and functionalities. It should be understood that the various examples of the system(s), device(s), and method(s) disclosed herein may include any of the components, features, and functionalities of any of the other examples of the system(s), device(s), and method(s) disclosed herein in any combination or any sub-combination, and all of such possibilities are intended to be within the scope of the disclosure.

The description of the different advantageous arrangements has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the examples in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different advantageous examples describe different advantages as compared to other advantageous examples. The example or examples selected are chosen and described to explain the principles of the examples, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various examples with various modifications as are suited to the particular use contemplated.

Having described the subject matter of the present disclosure in detail and by reference to specific examples thereof, it is noted that the various details disclosed herein should not be taken to imply that these details relate to elements that are essential components of the various examples described herein, even in cases where a particular element is illustrated in each of the drawings that accompany the present description. Further, it will be apparent that modifications and variations are possible without departing from the scope of the present disclosure, including, but not limited to, examples defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.

Moreover, while some examples have been described in the context of fully functioning computers and computer systems, those skilled in the art will appreciate that various examples are capable of being distributed as a program product in a variety of forms, and that the disclosure applies equally regardless of a particular type of machine or computer-readable media used to effect the distribution.

Further examples of machine-readable storage media, machine-readable media, or computer-readable (storage) media include, but are not limited to, recordable type media such as volatile and non-volatile memory devices, floppy and other removable drives, hard drives, optical disks (e.g., Compact Disk Read-Only Memory (CD ROMS), Digital Versatile Disks, (DVDs), etc.), among others, and transmission type media such as digital and analog communication links.

For the purposes of describing and defining examples herein, it is noted that terms “substantially” or “about” are utilized herein to represent an inherent degree of uncertainty attributed to any quantitative comparison, value, measurement, or other representation. The terms “substantially” and “about,” when utilized herein, represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in a basic function of the subject matter at issue, such as varying by 0-2% of the quantitative measurement.