Refrigerant Inspection

Abstract

A refrigerant testing apparatus and method for testing refrigerant diverted from a refrigeration system, the method including diverting refrigerant from the refrigeration system to a vessel, varying the temperature of the refrigerant in the vessel, measuring the pressure and temperature of the refrigerant as the temperature varies, comparing the measured pressure and temperature values ​​to reference values ​​and generating a warning indication if the comparison indicates that the measured values ​​differ by more than a predetermined amount from the stored reference values.

Description

[Technical field]

[0001] The present invention relates to the inspection of refrigerants. [Background technology]

[0002] Closed loop refrigeration systems generally contain a quantity of working fluid (hereafter also referred to as refrigerant or gas). These systems may operate on any one or combination of thermodynamic cycles such as, but not limited to, the Joule-Thomson cycle, the GM cycle, the Stirling cycle, etc. The refrigerant in these systems may be a single compound or a mixture of several different compounds.

[0003] Since the system is closed, i.e. no significant amount of working fluid flows into or out of the system, the performance of such systems is very sensitive to the amount of working fluid contained in the system. Such systems are typically filled (sealed) with the exact amount of working fluid required for optimal performance. If for any reason (manufacturing defect, installation error, equipment damage, operator error, etc.) the system loses some of the working fluid, i.e. if the working fluid leaks out of the system, or if the composition of the working fluid changes, the performance of the system can be seriously affected. This generally has a detrimental effect on the system performance and, if not observed in time, can lead to a total system failure, requiring time-consuming and expensive measures to repair the system. Furthermore, some refrigeration systems contain working fluids that are harmful to the environment, so it is illegal to release these gases into the atmosphere. In the event of a leak in such a system, the owner / manufacturer / operator may also be held legally liable according to applicable environmental protection laws.

[0004] For the above reasons, it is important to monitor the condition of the refrigerant in the system (during operation) so that potential problems can be spotted and corrective action can be taken in a timely manner. Problems may be caused by deterioration of the refrigerant charge, loss of refrigerant charge from the system, and / or changes in the composition of the mixed refrigerant charge. Summary of the Invention [Means for solving the problem]

[0005] A first aspect provides a refrigerant testing apparatus for testing a refrigerant diverted from a refrigeration system, the refrigerant testing apparatus comprising: a vessel having an inlet for receiving the refrigerant from the refrigeration system and an outlet for returning the refrigerant to the refrigeration system; an inlet flow control device for opening and closing the inlet; an outlet flow control device for opening and closing the outlet; a temperature sensor for detecting a temperature of the refrigerant in the vessel; a pressure sensor for detecting a pressure of the refrigerant in the vessel; a temperature control device for controlling the temperature of the refrigerant in the vessel; a control circuit configured to control the inlet flow control device and the outlet flow control device to introduce the refrigerant into the vessel and isolate the refrigerant in the vessel, control the temperature control device to vary a temperature of the refrigerant, and control the temperature sensor and the pressure sensor to test the refrigerant by measuring the temperature and pressure of the refrigerant as the temperature changes; and an analysis circuit configured to compare the measured temperature and pressure values ​​with reference values ​​and to indicate an error if the measured pressure and temperature values ​​differ from the reference values ​​by more than a predetermined amount.

[0006] It has been recognized that deterioration and / or leakage of the working fluid in a refrigeration system can significantly affect performance, and that if the problem is not identified or addressed, performance will continue to degrade. It has therefore been found to be advantageous to be able to monitor the working fluid in situ, or at least to some degree in situ, so that changes in the properties or quantity of the working fluid can be identified.

[0007] This has been addressed by using a refrigerant testing device configured to divert a small amount of refrigerant from the refrigeration system into a testing chamber or vessel. The vessel has a predetermined volume and testing of the fluid involves varying the temperature of the fluid over a temperature range while monitoring how the pressure and temperature change. Because the vessel has a predetermined set volume, changes in pressure can be directly related to changes in temperature. These changes can be compared to baseline values ​​to determine if they are as expected or within a predetermined range of baseline values. If not, an alert can be issued. This alert can be a simple "fault detection" type alert or can include information such as data collected during testing that provides some indication of a fault.

[0008] In this regard, if the pressure is higher than expected, this may indicate deterioration or decomposition of the refrigerant. If the pressure is lower than expected, this may indicate a leak or similarly deterioration of the refrigerant. In this regard, depending on the nature of the refrigerant and the temperature at which the unexpected pressure reading occurs, it is possible to separate possible causes of the unexpected pressure reading from several possible ones.

[0009] In some embodiments, the inlet is configured to connect to a portion of a refrigerant line in the refrigeration system and the outlet is configured to connect to another portion of the refrigerant line in the refrigeration system, the other portion being at a lower pressure than the one portion.

[0010] In some embodiments, the refrigerant testing device is configured to test a mixed refrigerant and the temperature control device is configured to control the temperature to vary over a temperature range over which at least one component of the mixed refrigerant varies between a liquid state and a gas state.

[0011] If the refrigerant is a mixed refrigerant, further details regarding the different components of the mixed refrigerant can be determined by controlling the temperature controller to vary the temperature over a temperature range that includes at least one phase change of the components of the mixed refrigerant. In this regard, the difference in pressure compared to a reference pressure value on either side of the phase change can indicate the contribution to this difference by a particular component, allowing a more complete diagnosis of the fault to be made. In this regard, certain refrigerants may be more susceptible to decomposition than others, while some refrigerants may be more susceptible to escape if there is a small leak, and therefore determining which refrigerant is causing the unexpected results can help diagnose what the problem is.

[0012] As described in more detail below, in some embodiments, the refrigerant is sampled from two or more locations, and in such cases it may be advantageous to sample the mixed refrigerant at one location where all of the components are gases to test over the temperature range where the mixed refrigerant remains gaseous, and to sample the mixed refrigerant at another location in the refrigeration system where at least one of the components is liquid at the time of sampling and changes to a gaseous state during testing.

[0013] In some embodiments, the refrigerant testing device includes a data storage unit that stores the reference value.

[0014] It should be noted that the temperature control device can be a cooler and / or a heater, but in some embodiments the temperature control device comprises a heater, which is an inexpensive and space efficient way to control temperature.

[0015] In some embodiments, the analysis circuitry is configured to analyze changes in the pressure at different temperatures and determine from the changes information regarding a composition of the mixed refrigerant.

[0016] In some embodiments, the control circuitry is configured to control the refrigerant testing device to periodically test the refrigerant.

[0017] As mentioned above, it is important to determine problems with the working fluid in a refrigeration system, and therefore, if a refrigerant testing device is present, it may be advantageous to control the device to periodically test the refrigerant. This may be periodically in time or periodically in the use of the refrigeration system. For example, it may be tested after a particular process has been performed or at a particular point in the process of the refrigeration system.

[0018] In some embodiments, the refrigerant testing device comprises two or more vessels, each including an inlet and an outlet and corresponding inlet and outlet flow control devices, the inlets and outlets configured to connect to different locations within the refrigeration system, and the control circuitry configured to compare the pressure and temperature changes to the reference values ​​for the refrigerant in each of the vessels and indicate an error if the pressure and temperature changes differ from the reference values ​​in one or more of the vessels by more than a predetermined amount.

[0019] The refrigerant testing equipment may include a single vessel, but may in some cases include two or more vessels, which may be positioned such that the refrigerant being sampled is diverted from different portions of the refrigeration system. Changes in the refrigerant properties extracted from different portions of the refrigeration system may provide further diagnostic information regarding the performance of the refrigeration system and where and / or which portions or components of the refrigerant mix are particularly affected by the problem.

[0020] In this regard, the inlet and outlet are attached to different portions of the refrigerant line so that the refrigerant is sampled at different points in the refrigeration cycle.

[0021] In some embodiments, the analysis circuitry comprises a machine learning algorithm configured to analyze the measured pressure and temperature values ​​and a signal received from the refrigeration system indicative of its operation, to determine predicted pressure and temperature values ​​from the received signal and previously measured pressure and temperature values, and to update the reference values ​​with the predicted pressure and temperature values.

[0022] Accurately setting the initial baseline values ​​is difficult, especially if the refrigerant testing device is not connected to the refrigeration system at the time of manufacture. Even if the refrigerant testing device is part of the refrigeration system, the system being cooled, and therefore the load of the system, only exists once the system is in service and may not be testable at the time of manufacture, which will affect the pressure and temperature samples taken at a particular time and during a particular operation. By providing a machine learning algorithm that can analyze the measurements over time, along with signals received from the refrigeration system indicative of the temperature, pressure at different locations in the system, and the operating mode of the system when these values ​​were measured, the machine learning algorithm can determine changes in pressure and temperature values ​​that are deemed not indicative of a change in the refrigerant, which allows the machine learning algorithm to update the baseline values ​​and possibly the predetermined amounts.

[0023] In some embodiments, the machine learning algorithm is configured to analyze the measured pressure and temperature values ​​during an initial period after initiation of the refrigerant test and to derive the predicted pressure and temperature values ​​from the analyzed values.

[0024] As mentioned above, one problem in setting the baseline values ​​is that the refrigerant testing equipment may not be installed in the refrigeration system or the refrigeration system may not be installed in the system it is cooling when these values ​​are set. Pressure and temperature values ​​measured early in the operation of the refrigerant testing equipment can provide a good indication of expected values ​​prior to a refrigerant leak or decomposition and therefore may be used by the machine learning algorithm to update the baseline values.

[0025] A further aspect provides a refrigeration system comprising a refrigerant supply line for supplying refrigerant to an evaporator, a refrigerant return line for returning refrigerant from the evaporator, a compressor for compressing refrigerant received from the return line, and a refrigerant inspection apparatus according to the first aspect.

[0026] In some embodiments, the inlet of the refrigerant testing device is connected to the refrigerant supply line and the outlet is connected to the refrigerant return line.

[0027] In some embodiments, the control circuitry is configured to perform an initial step of generating and storing the reference value for the refrigeration system by controlling the refrigerant testing device to test the refrigerant a predetermined number of times and generating the reference value from the results.

[0028] The reference values ​​can be preloaded into the refrigerant testing device, but typically they are generated by the device itself during an initial calibration type step, whereby the refrigerant in the refrigeration system is tested multiple times, typically when the system is new, and temperature and pressure values ​​are measured and used to generate the reference values. In this regard, the reference value can be generated from a kind of average of these measurements, and can be a taken average value or a mode value.

[0029] In some embodiments, the predetermined amount that triggers the error indication can be generated from this initial calibration measurement, and in particular from the measured difference between the values ​​measured during the different initial tests. If these measurements are not significantly different, even small variations in the measurements are expected to indicate some change in the working fluid, whereas if there is a large difference in the measurements during the calibration tests, then a higher predetermined amount as a threshold will obviously be required.

[0030] In some embodiments, the initial step is performed for a number of different refrigeration system operating conditions or modes to generate a number of corresponding baseline values.

[0031] In some cases, the baseline values ​​may be generated during multiple different operating conditions and / or modes, and corresponding baseline values ​​generated accordingly. If the refrigerant is tested during operation, tests are performed during these different operating modes, and the associated baseline values ​​are used for comparison. Again, these additional tests can provide further diagnostic information if any unexpected values ​​are measured.

[0032] In some embodiments, the control circuitry is configured to control the refrigerant testing apparatus to perform the initial step in both of the vessels, and the baseline value is generated and stored for each of the two or more vessels.

[0033] If the refrigerant testing apparatus has more than one vessel or test chamber, an initial calibration measurement can be made on each vessel to generate a reference value applicable to each vessel. During refrigerant testing, depending on which vessel a measurement comes from, the associated reference value will be used for comparison.

[0034] In some embodiments, the comparison step may be a comparison of trends or curves rather than a comparison of actual values.

[0035] The first vessel and the second vessel can be connected to any two different locations within the refrigeration system, but in some embodiments the refrigeration system further comprises at least one phase separator and at least one heat exchanger, wherein a first inlet to a first vessel is connected to the refrigerant supply line at a first point and a second inlet to a second vessel is connected to the refrigerant supply line at a second point, the first point and the second point being separated by at least one of the phase separator and the heat exchanger.

[0036] In some embodiments, the working fluid of the refrigeration system includes a mixed refrigerant.

[0037] In some embodiments, the sampling point may be selected to be a point where the temperature and pressure stabilize, and, if the refrigerant is a mixed refrigerant, the composition stabilizes.

[0038] If there are two sampling points and it is a mixed refrigerant, the first and second points can be selected to be at different temperatures, pressures and / or compositions of the mixed refrigerant. These two points can be different parts of the refrigerant line at different points in the refrigeration system. In some embodiments, one can be taken before the phase separator and one after the phase separator, such that a particular component of the mixed refrigerant is more present in one of the samples than the other, so that the difference between the reference value and the measured sample can indicate not only a fault, but also which particular component of the refrigerant is not as expected.

[0039] In some embodiments, the control circuitry is configured to determine operation of the refrigeration system and to control the refrigerant testing device to monitor the refrigerant during a particular operating mode of the refrigeration system, and possibly during multiple different operating modes of the refrigeration system.

[0040] A further aspect provides a method of inspecting refrigerant in a refrigeration system comprising diverting refrigerant from the refrigeration system to a container, varying a temperature of the refrigerant in the container, measuring a pressure and temperature of the refrigerant as the temperature varies, comparing the measured pressure and temperature values ​​to reference values ​​and generating a warning indication if the comparison indicates a difference between the measured values ​​and the reference values ​​by more than a predetermined amount.

[0041] In some embodiments, the method includes a first step of installing a refrigerant testing apparatus according to a first aspect in a refrigeration system.

[0042] Refrigeration systems can be manufactured with the refrigerant testing equipment installed, however, in some embodiments, the refrigerant testing equipment can be retrofitted to existing refrigeration systems to improve the system to continuously monitor refrigerant quality / quantity.

[0043] In some embodiments, the method includes generating the reference value prior to testing the refrigerant by performing a method for testing the refrigerant a predetermined number of times and generating the reference value from the measured pressure and temperature values.

[0044] Further particular and preferred aspects are set out in the independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate or in combinations other than those explicitly set out in the claims.

[0045] Where features of an apparatus are described as operable to provide a certain functionality, this should be understood to include features of the apparatus that provide that functionality or that are adapted or configured to provide that functionality.

[0046] Embodiments of the invention are further described below with reference to the accompanying drawings. [Brief description of the drawings]

[0047] [Figure 1] 1 illustrates a refrigerant testing apparatus according to one embodiment. [Diagram 2] 1 illustrates a refrigeration system according to one embodiment. [Diagram 3] 2 shows a flow diagram illustrating steps in a method according to one embodiment. [Figure 4] 2 shows a flow chart illustrating steps in a method for calibrating a refrigerant testing device. [Diagram 5] 4 illustrates steps in a method for updating a reference value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] Before describing the embodiments in detail, an overview will first be provided.

[0049] The embodiments provide a method and apparatus for periodically monitoring the health of the refrigerant charge in a system. The embodiments operate on the principle that a known gas or mixture of gases will exhibit consistent temperature and pressure characteristics based on the thermodynamic properties of the gas(es). By applying the thermodynamic relationship between pressure and temperature for a volume of gas, the amount (and composition) of gas in that volume can be determined. By employing this technique at appropriate locations in the system, the overall health of the refrigerant charge of the system can be inferred from measurements.

[0050] The embodiments operate on the principle that for a given gas or mixture of gases, the P, V and T (pressure volume and temperature) properties of the gas are interrelated and can be predicted using a thermodynamic equation of state.

[0051] The embodiments utilize the principle of periodically diverting a small portion of the refrigerant charge in the system (typically less than 5%) to a specific test portion of the system (called the test volume). The test volume can be an integral part of the system so that it does not need to be connected / disconnected to perform measurements. In this regard, the test volume may be part of the system when it is manufactured or may be added to the system as an add-on component after manufacture. This test volume may be a tank, pressure vessel, container, or similar, with its shape and internal volume selected depending on the size and type of the overall system.

[0052] This particular test portion of the system (test volume) is maintained at a set temperature and pressure, and the inlet and outlet of this test volume are maintained at predetermined P and T values. Flow control devices such as valves (manual or powered) are used to control the flow of gas into and out of this volume. By controlling the time (in the open position), inlet geometry, and inlet pressure of the flow control devices, a predetermined amount of working fluid can be diverted into this test volume. Once the working fluid is isolated in this volume, the temperature of the working fluid can be precisely altered / controlled using heaters or cooling means as required.

[0053] The test volumes considered have temperature and pressure monitoring devices (thermocouples, diodes, pressure transducers, etc.) that can accurately measure the temperature and pressure of the working fluid within the vessel. As the temperature of a given working fluid (or mixture) changes, the pressure will likewise change in a predictable and repeatable manner.

[0054] The temperature and pressure values ​​for the particular working fluid (or mixture) in this control volume can be compiled for various system operating conditions, operating modes, states, etc., to create an electronic table or plot of T vs. P relationships. This is best accomplished when the system is new and free of wear, defects, leaks, etc. that may occur after continued operation. Once reference values ​​and / or relationships for T and P have been established for all system performance modes, these can be used as baseline reference values ​​or curves for future comparisons.

[0055] As an example for a refrigeration system in use, a portion of the working fluid is diverted to a measurement volume using the flow control device described above. The amount of working fluid diverted is small enough that it does not affect the performance of the system. This working fluid is captured in a test volume and heated or cooled to a predetermined temperature over a temperature range. The pressure of the working fluid is measured while its temperature is increased and / or decreased and when it is further heated or cooled to reach a final temperature (set temperature). For a given operating state of the system, the pressure and temperature values ​​of the working fluid in the test volume should very closely follow baseline reference values ​​established and stored when the system was manufactured / installed / initialized.

[0056] In some embodiments, the above method is performed periodically to observe trends in P and T values. If the trends in P and T values ​​fall outside of a predetermined acceptable range, it can be concluded that there is a problem with the working fluid. This can indicate a leak in the system, a change in the packing composition, deterioration / deterioration of one or more components of the packing, etc. However, all scenarios are important to detect, as they have a negative impact on system performance. At this point, the system's controller can present an alarm / error message to bring the problem to attention. If addressed in time, expensive repairs and downtime of the refrigeration system can be avoided or at least reduced.

[0057] In some embodiments, such as those where mixed refrigerants are used, it is advantageous to divert the working fluid to the test volume from a location in the system where the inlet T, P, and composition of the working fluid vary less between samples. In systems that operate with a single refrigerant / working fluid, this is easy since only the T and P of the working fluid need to be controlled. However, in systems that operate with a mixture of gases, it is important to divert the working fluid from a location where the composition of the working fluid is most consistent for any given duty cycle of the system. System designers can identify such locations during their design to ensure consistency of measurements.

[0058] Another aspect of this invention is a method for obtaining / determining baseline T and P values ​​for a given system. The following approaches or any combination thereof are possible: 1. Baseline T and P values ​​can be recorded by operating the system in all possible operating modes and diverting the working fluid into the test volume several times in each operating mode, and a baseline and acceptable error bands can be established. 2. T and P values ​​can be predicted using thermodynamic equations. In this approach, the working fluid is diverted into a test volume in one particular operating mode of the system, which is repeated several times to establish a baseline for the operating mode. Once this is established, baseline values ​​of T and P for different modes can be calculated using the thermodynamic equations. 3.ML Machine Learning and AI Artificial Intelligence techniques, in conjunction with the curves / data and thermodynamic equations, can be used to create and train intelligent "models" to predict the T and P of sample working fluids for comparison.

[0059] In summary, embodiments seek to estimate the overall refrigerant charge health of a system based on small samples of the working fluid, in some embodiments taken periodically during operation of the system, which is particularly advantageous for systems that use mixed refrigerants as the working fluid.

[0060] In a mixed refrigerant system, the composition of the working fluid varies depending on the physical location of the fluid mixture in the system as well as the duty cycle of the cycle (idle, no load, full load, etc.). It is proposed that the refrigerant mixture is sampled at a specific location in the system where the composition is known to be constant. This sample is then isolated in an environment where the temperature of the sample is changed to a value such that variations due to phase changes and similar physical phenomena (such as freezing point depression) are eliminated, and the sample is essentially "homogenized / baselined" for measurement. For example, the temperature can be set such that each component of the mixed refrigerant is in a gaseous state. The pressure difference between when the sample is multiphase and when it is single phase is then compared to the corresponding reference value, providing additional information.

[0061] 1 shows a refrigerant testing apparatus 15 according to an embodiment. The refrigerant testing apparatus 15 comprises a vessel 10 of a given volume that is insulated to reduce temperature fluctuations and is surrounded by a heating element 13 that in this embodiment is controlled by a temperature controller 20. The vessel 10 comprises an inlet 16 for receiving refrigerant from a refrigeration system and an outlet 18 for returning refrigerant to the refrigeration system. The inlet 16 has an inlet passage connected to a valve 26 for controlling the flow of refrigerant, and the outlet 18 has an outlet passage connected to a valve 28. The valves 26 and 28, and the temperature control circuit 20, are controlled by a control circuit 21. The control circuit 21 in some embodiments comprises an input port 23 for receiving signals from the refrigeration system. These signals may indicate the current operating mode of the refrigeration system and / or may include measurements from temperature, pressure and flow sensors within the refrigeration system.

[0062] Control circuitry 21 controls the refrigerant testing equipment to sample and then test the refrigerant by controlling valves 26 and 28 to allow the refrigerant to enter the testing chamber or vessel 10 and then be sealed within the vessel 10. Temperature controller 20 controls the temperature of the refrigerant within vessel 10 by controlling heater 13 to heat the vessel from an initial low temperature to a pre-determined high temperature setting. Temperature sensor 14 and pressure sensor 12 monitor the temperature and pressure of the refrigerant as it warms. Values ​​from these sensors are sent to analysis circuitry 22 which compares the measurements to reference values ​​stored in data store 24 and determines whether the values ​​are as expected or if the values ​​indicate an anomaly.

[0063] If these are not as expected, a warning indication can be generated. This warning indication can be simply a binary indication, such as turning on a light or producing a sound, or can include data from the measurements that can indicate the type of anomaly that has been detected. For example, higher or lower than expected pressure, and the temperature at which the unexpected pressure reading occurs, all indicate the type of fault. High pressure may indicate refrigerant decomposition, while low pressure may indicate a leak in the system.

[0064] In some embodiments, the refrigerant is a mixed refrigerant containing different components. In such cases, a combination of temperature and pressure measurements can provide an indication of the components in the refrigerant that are responsible for the unexpected results. In this regard, if the pressure is measured over a temperature range where at least one of the mixed refrigerant components changes state, the contribution of this component to any anomalous results can be derived. In this regard, one or more components of the refrigerant may be prone to degradation or decomposition, so that the pressure may increase when these components are in a gaseous state, while one or more components may be prone to leakage, leading to a lower than expected pressure.

[0065] In some embodiments, if a signal is received from the refrigeration system at input 23, control circuitry 21 may control refrigerant testing device 15 to execute a refrigerant testing routine at a particular time during a particular operating mode of the refrigeration system. Data store 24 may then store pressure and temperature reference values ​​associated with these different operating modes, and a comparison of the measurements will be performed against the associated reference values. In some embodiments, the refrigerant testing device may sample and test the refrigerant multiple times and average the results before making a comparison to determine whether the refrigerant is performing as expected.

[0066] The reference values ​​stored in the data store 24 may be generated during an initial calibration step in which the control circuit controls the refrigerant testing device to sample the refrigerant, vary the temperature and measure pressure and temperature variations. This may be done a predetermined number of times and a reference value may be generated from an average of these measurements, and a threshold may be generated indicative of how much the measurements may vary from the reference value before an anomaly is indicated. The threshold may be generated depending on the variation in the values ​​measured during the calibration step. The calibration step may be performed during different operating modes of the refrigeration system to generate a reference value for each mode, or in different test chambers if there are multiple test chambers, and a reference value for each test chamber may be generated.

[0067] In some embodiments, the analysis circuitry 22 includes a machine learning algorithm. The machine learning algorithm may receive signals from the refrigeration system in addition to the temperature and pressure measurements. The machine learning algorithm may analyze the pressure and temperature measurements along with the signals from the refrigeration system to identify differences and trends in the measurements. The machine learning algorithm may be used to update the baseline values ​​stored in the data store 24 when the measured values ​​are consistently different from the baseline values ​​and are deemed not to be due in any way to changes in the refrigerant properties.

[0068] In this embodiment, the refrigerant testing apparatus has a single testing chamber or vessel 10, however, in some embodiments, there may be multiple vessels with inlet and outlet paths connected to different portions of the refrigeration system to sample the refrigerant at different locations in the system. In these embodiments, a reference value associated with each location is used.

[0069] Figure 2 shows a refrigeration system according to one embodiment. The refrigeration system is a mixed refrigerant Joule-Thompson cryochiller. The cryochiller comprises a compressor 1 that compresses the refrigerant received from the return refrigerant line and sends it along a refrigerant supply line towards an evaporator 30. There are separators 2 and 5 that separate oil or liquid from the high pressure supply line and send it to a low pressure return line, and there are heat exchangers 3, 4, 6, 9 that serve to cool the compressed refrigerant before it reaches the evaporator 30. In the evaporator 30, the liquid refrigerant will expand to form a gas, which will create a cooling effect.

[0070] In this embodiment, there are two refrigerant testing devices 15a, 15b, each with an insulated and temperature controlled vessel 10 of a given volume, each with an associated pressure sensor 12 and temperature sensor 14. The vessel inlet and outlet have valves to control the flow in and out of the vessel 10. A control circuit (not shown) controls these valves so that the refrigerant is diverted from the refrigerant supply line to the testing vessel and then back to the refrigerant return line after testing. For an initial sampling, both the inlet and outlet valves can be left open to clean the chamber, after which the outlet valve can be closed and the inlet valve left open to allow the refrigerant to be sampled. Then both valves can be closed to isolate the sample from the refrigeration system. A temperature control circuit associated with the vessels 10 then changes the temperature of the vessels 10 over a temperature range sufficient to change the state of at least some of the components of the mixed refrigerant in at least one of the vessels, in this embodiment. The temperature and pressure of the refrigerant during these temperature changes are measured and compared to stored reference values ​​to determine the state of the refrigerant in the refrigeration system.

[0071] In this embodiment, the refrigerant is sampled at two locations, location 1 and location 2. Location 1 is closer to the compressor and has a higher refrigerant temperature, while location 2 is further away from the compressor. The refrigerant at location 2 is cooler than the refrigerant at location 1, so the phase composition of the refrigerant mixture at the time of sampling may be different. Differences in the measurements and analysis of the measurements from the two locations may provide additional information in diagnosing any faults.

[0072] 3 shows a schematic of the steps of a method according to one embodiment. In this embodiment, in step S10, a refrigerant testing device is attached to a refrigeration system. In some embodiments, the refrigerant testing device can be manufactured with an integrated refrigerant testing device, while in other embodiments, the refrigerant testing device can be manufactured separately and retrofitted to an existing refrigeration system. In the latter case, step S10 is performed, while in the former case, this step is unnecessary.

[0073] Next, step S20 is performed, where the refrigeration system is attached to a load, which may be a semiconductor wafer refrigeration circuit, and the attachment of the refrigeration system to the load will affect the volume of the refrigeration system and therefore the pressure within the refrigeration system.

[0074] In step S30, freezing is initiated in the refrigeration system, and in step S40, the refrigerant is sampled by controlling the inlet and outlet valves to the sample chamber to admit refrigerant into the sample chamber. In step S50, the refrigerant is isolated in the sample chamber.

[0075] Next, in step S60, a refrigerant testing regime is initiated on the isolated sample by varying the temperature of the refrigerant over a temperature range. This can be done by heating or cooling the refrigerant over a temperature range. If the refrigerant is a mixed refrigerant, the temperature range can be selected such that at least one of the components of the refrigerant changes state between gas and vapor during the temperature change. In some embodiments, the change in temperature can cause the mixed refrigerant to be homogenized, i.e., all components are in the same state.

[0076] In step S70, the temperature and pressure of the isolated refrigerant are measured as the temperature changes. In some embodiments, the test steps S40 through S70 are repeated one or more times in step S80 and the results are averaged in step S90. In other embodiments, the results of a single test can be used without repeating the steps and averaging the results.

[0077] Next, in step S100, the result is compared to a stored reference value to determine whether it differs from the stored reference value by more than a predetermined amount (threshold) in step D5. If it is determined that there is a difference, a warning is output in step S110, otherwise it is determined in step D15 whether a predetermined time has elapsed, and if so, the inspection step is repeated.

[0078] In this way, the refrigerant in the refrigeration system is measured periodically and an alarm is issued if there is a significant change in the results compared to the reference value, allowing early detection of signs of refrigerant deterioration or leakage before the system fails.

[0079] In some cases, the refrigerant is sampled at multiple locations and method steps S40 to S110 are performed for each location. In some cases, the refrigerant may be tested during different operating modes of the refrigeration system, in which case different reference values ​​and different thresholds associated with the different modes may be used.

[0080] FIG. 4 shows a flow diagram illustrating steps performed in generating a reference value during an initial calibration procedure of a reference test device according to one embodiment. In an initial step S200, the refrigeration system is turned on and controlled to perform one mode of refrigeration. In this regard, the refrigeration system can operate in a number of different modes, such as a refrigeration mode and a standby mode. In step S210, the refrigerant is sampled and in step S220, it is isolated. In step S230, the temperature of the isolated refrigerant is varied over a temperature range, and in step S240, the temperature and pressure of the isolated refrigerant are measured as the temperature changes. In step S250, steps S210 to S240 are repeated. Step S250 itself can be repeated multiple times. In step S260, the repeated measurements are averaged, and in step S270, a reference value is generated from these averaged results. A threshold value is then generated in step S280. In this regard, the threshold value may depend on the variance of the averaged measurements to form the reference value. These reference values ​​and threshold values ​​are stored for use in the test steps of the method of FIG. 3.

[0081] Next, in step D205, it is determined whether all operating modes have been tested, and if not, step S290 is executed to control the refrigeration system to perform additional operating modes, and steps S210 through S280 and D205 are executed again. If it is determined in step D205 that all operating modes have been tested, the calibration procedure ends in step S295.

[0082] FIG. 5 shows a schematic of how the reference value can be updated to more accurately reflect the refrigerant in the refrigeration system. In some cases, this is done using machine learning algorithms in the analysis circuit of an embodiment. In an initial step S300, a load is attached to the refrigeration system, and in step S310, the refrigerant is tested by performing the steps of sampling, isolating, and varying the temperature while measuring temperature and pressure. In step S320, the refrigerant test is repeated, and in step S330, the results are averaged. In this regard, in some embodiments, the refrigerant test may be repeated two or more times. In step S340, the average result is compared to the stored reference value, and in step D35, it is determined whether a threshold has been exceeded, i.e., whether the measured value differs from the reference value by more than a predetermined amount. If so, in step D350, a warning is output, and if not, the test is repeated a predetermined number of times N, and thus in step D45, it is determined whether the test has been repeated N times, and if not, the test is repeated again, and if so, the results are analyzed.

[0083] The analysis circuitry analyzes the results in step S360 and determines in step D55 whether there is a consistent difference between the results and the reference value that does not exceed a threshold. Inputs from the refrigeration system, such as temperature and pressure measurements taken at various locations during refrigerant sampling, can also be received and considered and included in determining in step D35 whether the variation in the results indicates a consistent difference between the measurements and the reference value. If so, the reference value can be updated with the consistent difference in step S370 and the test can continue to be repeated.

[0084] In some cases, the method can be performed at an early stage of use of a refrigeration system with a particular load, since the baseline values ​​were generated without load and therefore there may be some offset in the baseline values, which can be detected and corrected by measurements taken during use. As the refrigeration system ages and refrigerant leaks or decomposition becomes more likely, the machine learning algorithm is configured to not update the baseline values ​​or to refrain from updating them, in other words to request more data indicative of changes not due to changes in refrigerant properties, before updating the values.

[0085] Although exemplary embodiments of the present invention are disclosed in detail herein with reference to the accompanying drawings, it should be understood that the present invention is not limited to the precise embodiments, and various changes and modifications may result by those skilled in the art without departing from the scope of the present invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0086] 1 Compressor 2 separator 5 Separator 3 Heat exchanger 6 Heat exchanger 9 Heat exchanger 10 Inspection chamber / container 12 Pressure Sensor 13 Heater / Heating Element 14 Temperature Sensor 15 Refrigerant inspection equipment 15a Refrigerant inspection equipment 15b Refrigerant inspection equipment 16 Entrance 18 Exit 20 Temperature control device 21 Control circuit 22 Analysis circuit 23 Input 24 Data storage unit 26 Valve 28 Valve 30 Evaporator

Claims

1. 1. A refrigerant testing device for testing a refrigerant diverted from a refrigeration system, comprising: a vessel having an inlet for receiving the refrigerant from the refrigeration system and an outlet for returning the refrigerant to the refrigeration system; an inlet flow control device for opening and closing the inlet; an outlet flow control device for opening and closing the outlet; a temperature sensor that detects the temperature of the refrigerant in the container; a pressure sensor that detects the pressure of the refrigerant in the container; a temperature control device for controlling the temperature of the refrigerant in the container; A control circuit configured to control the refrigerant testing apparatus, controlling the inlet flow control device and the outlet flow control device to introduce the refrigerant into the vessel and isolate the refrigerant within the vessel; Controlling the temperature control device to change the temperature of the refrigerant; controlling the temperature and pressure sensors to measure the temperature and the pressure of the refrigerant as the temperature changes; a control circuit configured to test the refrigerant by an analysis circuit configured to compare the measured temperature and pressure values ​​to reference values ​​and to indicate an error if the measured pressure and temperature values ​​differ from the reference values ​​by more than a predetermined amount; A refrigerant inspection device comprising:

2. 2. The refrigerant testing apparatus of claim 1, wherein the refrigerant testing apparatus is configured to test a mixed refrigerant, and the temperature control device is configured to control the temperature to vary over a temperature range in which at least one component of the mixed refrigerant varies between a liquid state and a gas state.

3. 3. The refrigerant testing apparatus of claim 2, wherein the analysis circuitry is configured to analyze the changes in pressure at different temperatures and determine information about the composition of the mixed refrigerant from the changes.

4. 4. The refrigerant inspection device according to claim 1, wherein the control circuit is configured to control the refrigerant inspection device to periodically inspect the refrigerant.

5. The analysis circuit includes: analyzing the measured pressure and temperature values ​​and signals received from the refrigeration system indicative of operation of the refrigeration system; determining expected pressure and temperature values ​​from the received signals and previously measured pressure and temperature values; updating the reference values ​​with the predicted pressure and temperature values; The refrigerant inspection device according to claim 1 , further comprising a machine learning algorithm configured to:

6. 6. The refrigerant testing apparatus of claim 5, wherein the machine learning algorithm is configured to analyze the measured pressure and temperature values ​​during an initial period after initiation of the refrigerant testing and to derive the predicted pressure and temperature values ​​from the analyzed values.

7. The refrigerant testing apparatus includes two or more vessels each including an inlet and an outlet and corresponding inlet and outlet flow control devices, the inlets and outlets configured to connect to different locations within the refrigeration system, and the control circuitry includes: comparing the pressure and temperature changes to the reference values ​​for the refrigerant in each of the vessels; indicating an error if the pressure and temperature changes in one or more of the vessels differ from the reference values ​​by more than a predetermined amount; The refrigerant inspection device according to any one of claims 1 to 6, which is configured as follows.

8. a refrigerant supply line for supplying a refrigerant to the evaporator; a refrigerant return line for returning refrigerant from the evaporator; a compressor for compressing the refrigerant received from the refrigerant return line; A refrigerant inspection device according to any one of claims 1 to 7, A refrigeration system comprising:

9. 9. The refrigeration system of claim 8, wherein the inlet of the refrigerant testing device is connected to the refrigerant supply line and the outlet is connected to the refrigerant return line.

10. 10. The refrigeration system of claim 8, wherein the control circuit is configured to execute an initial step of controlling the refrigerant testing device to generate and store the reference value for the refrigeration system by controlling the refrigerant testing device to test the refrigerant a predetermined number of times and generating the reference value from the results.

11. The refrigeration system of claim 10 , wherein the initial step is performed for a plurality of different refrigeration system operating conditions or modes to generate a plurality of corresponding baseline values.

12. The refrigerant inspection device is the refrigerant inspection device described in claim 7, and the control circuit is configured to control the refrigerant inspection device to perform the initial step in both of the containers, and the reference value is generated and stored for each of the two or more containers.

13. The refrigeration system further comprises at least one phase separator and at least one heat exchanger; 13. The refrigeration system of claim 12, wherein a first inlet to a first vessel is connected to the refrigerant supply line at a first point and a second inlet to a second vessel is connected to the refrigerant supply line at a second point, the first point and the second point being separated by at least one of a phase separator and a heat exchanger.

14. 14. A refrigeration system according to any of claims 8 to 13, wherein the refrigerant of the refrigeration system comprises a mixed refrigerant.

15. 1. A method for testing a refrigerant in a refrigeration system, comprising: diverting refrigerant from the refrigeration system to a vessel; varying the temperature of the refrigerant in the vessel; measuring the pressure and temperature of the refrigerant as the temperature changes; comparing the measured pressure and temperature values ​​to reference values ​​and generating a warning indication if the comparison indicates that the measured values ​​differ from the stored reference values ​​by more than a predetermined amount; The method includes:

16. 16. A method according to claim 15, comprising a first step of installing a refrigerant testing apparatus according to any one of claims 1 to 7 in a refrigeration system.

17. Before inspecting the refrigerant, performing a method for testing the refrigerant a predetermined number of times to generate the reference values ​​from the measured pressure and temperature values; 17. The method of claim 16, comprising generating the reference value by:

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