Method and device for estimating refrigerant stock of refrigerating system and refrigerating system

Abstract

The embodiment of the invention provides an estimation method and device for refrigerant stock of a refrigerating system and the refrigerating system. The method comprises the steps that first temperature information and first pressure information of a refrigerant at an outlet of a condenser and second temperature information of a refrigerant at an inlet of an expansion valve are obtained; according to the first pressure information and the first temperature information, the supercooling degree of an outlet of the condenser is determined; according to the difference between the supercooling degree of the outlet of the condenser and a preset supercooling degree threshold value, it is judged that abnormal flash gas exists in the refrigerating system; according to the first temperature information, the second temperature information and latent heat of vaporization of the refrigerant under the first pressure information, the flash gas ratio is calculated, the supercooling degree of an outlet of the condenser is corrected, and the corrected supercooling degree is obtained; and according to the corrected supercooling degree of the condenser outlet, the refrigerant stock of the refrigerating system is estimated based on a correlation model of the corrected supercooling degree of the condenser outlet and the refrigerant stock. According to the technical scheme provided by the embodiment of the invention, the accuracy of quality estimation of the refrigerant stock can be improved.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, and in particular to a method, device and system for estimating the refrigerant inventory in a refrigeration system. Background Technology

[0002] In vapor compression refrigeration systems, refrigerant, as the core medium for energy transfer, directly determines the system's operational performance, energy efficiency, and reliability. Insufficient refrigerant can lead to reduced cooling / heating capacity, increased compressor discharge temperature, and decreased COP (coefficient of performance), potentially causing compressor damage due to poor lubrication or overheating. Conversely, excessive refrigerant can cause condenser buildup and abnormal evaporation pressure, similarly affecting system stability and lifespan. Therefore, accurately determining the refrigerant level within the refrigeration system is crucial for system installation, commissioning, maintenance, and troubleshooting.

[0003] Existing methods for detecting refrigerant levels in refrigeration systems suffer from poor accuracy in estimating refrigerant levels. Summary of the Invention

[0004] This invention provides a method, apparatus, and system for estimating the refrigerant inventory in a refrigeration system, in order to address the problem of poor accuracy in estimating refrigerant inventory in existing methods for detecting refrigerant inventory in refrigeration systems.

[0005] To address the aforementioned technical problems, the present invention adopts the following technical solution:

[0006] This invention provides a method for estimating the refrigerant inventory in a refrigeration system, comprising:

[0007] Obtain the first temperature and first pressure information of the refrigerant at the condenser outlet, and the second temperature information of the refrigerant at the expansion valve inlet;

[0008] The subcooling degree of the condenser outlet is determined based on the first pressure information of the condenser outlet and the first temperature information of the refrigerant at the condenser outlet.

[0009] Based on the difference between the subcooling degree at the condenser outlet and the preset subcooling threshold, it is determined that there is abnormal flash gas in the refrigeration system;

[0010] Based on the first temperature information and the second temperature information, as well as the latent heat of vaporization of the refrigerant under the first pressure information, the flash gas ratio is calculated, the subcooling of the condenser outlet is corrected, and the corrected subcooling is obtained.

[0011] Based on the corrected subcooling at the condenser outlet, and using a correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated.

[0012] Optionally, the step of calculating the flash gas ratio based on the first temperature information and the second temperature information, as well as the latent heat of vaporization of the refrigerant under the first pressure information, and correcting the subcooling at the condenser outlet to obtain the corrected subcooling includes:

[0013] The flash gas ratio is calculated by multiplying the difference between the first temperature information and the second temperature information by the product of the specific heat capacity of the refrigerant at constant pressure in the subcooled liquid state and the product of the latent heat of vaporization of the refrigerant at the first pressure information.

[0014] Calculate the flash gas correction factor based on the flash gas ratio;

[0015] The corrected subcooling is determined by multiplying the flash gas correction factor by the subcooling at the condenser outlet.

[0016] Optionally, determining the subcooling at the condenser outlet based on the first pressure information at the condenser outlet and the first temperature information of the refrigerant at the condenser outlet includes:

[0017] Based on the first pressure information at the condenser outlet, determine the saturation temperature of the refrigerant corresponding to the first pressure information at the condenser outlet;

[0018] The subcooling at the condenser outlet is determined based on the difference between the first temperature information of the refrigerant at the condenser outlet and the saturation temperature.

[0019] Optionally, before estimating the refrigerant inventory of the refrigeration system based on the corrected subcooling at the condenser outlet and a refrigerant inventory correlation model, the method further includes:

[0020] Based on calibration experiments, a corrected correlation model between the subcooling at the condenser outlet of the refrigeration system and the refrigerant inventory was determined.

[0021] Optionally, the step of determining the correlation model between the subcooling degree at the condenser outlet of the refrigeration system and the refrigerant inventory based on calibration experiments includes:

[0022] Set calibration conditions, which include ambient temperature, evaporator load, and compressor frequency;

[0023] Different masses of refrigerant were charged into the refrigeration system, starting from 70% of the designed refrigerant quantity, and increasing in increments of 5% to 130% of the designed refrigerant quantity. Calibration experiments were conducted, and the corrected subcooling of the condenser outlet corresponding to the refrigerant quantity of each experimental group was calculated. The mass of the corresponding refrigerant quantity was also recorded.

[0024] Based on the mass of refrigerant stock from the calibration experiment and the corresponding corrected subcooling at the condenser outlet, a least squares method was used to fit and obtain a correlation model between the corrected subcooling at the condenser outlet and the refrigerant stock.

[0025] Optionally, after estimating the refrigerant inventory of the refrigeration system based on the corrected subcooling at the condenser outlet and a refrigerant inventory correlation model, the method further includes:

[0026] Obtain the current operating status of the refrigeration system;

[0027] Based on the difference between the current operating conditions and the calibration conditions, the correlation model between the subcooling at the condenser outlet and the refrigerant inventory is modified, and the correlation model between the subcooling at the condenser outlet and the refrigerant inventory after the operating conditions are modified is determined.

[0028] Based on the correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory after the operating condition correction, the refrigerant inventory is estimated according to the corrected subcooling at the condenser outlet.

[0029] Optionally, the step of correcting the correlation model between the subcooling and refrigerant inventory at the condenser outlet based on the difference between the current operating condition and the calibration operating condition, and determining the corrected correlation model between the subcooling and refrigerant inventory at the condenser outlet after the operating condition correction, includes:

[0030] Obtain the ambient temperature, evaporator load, and compressor frequency for the current operating conditions;

[0031] Based on the differences between the ambient temperature under the current operating condition and the ambient temperature under the calibration condition, the differences between the evaporator load under the current operating condition and the evaporator load under the calibration condition, and the differences between the compressor frequency under the current operating condition and the compressor frequency under the calibration condition, the correlation model between the corrected subcooling and refrigerant inventory at the condenser outlet is corrected to obtain the corrected correlation model between the corrected subcooling and refrigerant inventory at the condenser outlet.

[0032] Optionally, after estimating the refrigerant inventory of the refrigeration system based on the corrected subcooling at the condenser outlet and a refrigerant inventory correlation model, the method further includes:

[0033] Based on the difference between the refrigerant inventory and the first preset inventory threshold, a refrigerant shortage warning is triggered;

[0034] Based on the difference between the refrigerant inventory and the second preset inventory threshold, a refrigerant overload warning is triggered;

[0035] The first preset inventory threshold is less than the second preset inventory threshold.

[0036] Secondly, this embodiment provides a device for estimating the refrigerant inventory of a refrigeration system, comprising:

[0037] The acquisition module is used to acquire the first temperature and first pressure information of the refrigerant at the condenser outlet, and the second temperature information of the refrigerant at the expansion valve inlet.

[0038] The subcooling calculation module is used to determine the subcooling of the condenser outlet based on the first pressure information of the condenser outlet and the first temperature information of the refrigerant at the condenser outlet.

[0039] The flash gas detection module is used to determine whether there is abnormal flash gas in the refrigeration system based on the difference between the subcooling degree at the condenser outlet and a preset subcooling threshold.

[0040] The subcooling correction module is used to calculate the flash gas ratio based on the first temperature information and the second temperature information, as well as the latent heat of vaporization of the refrigerant under the first pressure information, and to correct the subcooling at the condenser outlet to obtain the corrected subcooling.

[0041] The estimation module is used to estimate the refrigerant inventory of the refrigeration system based on the corrected subcooling at the condenser outlet and a correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory.

[0042] Thirdly, this embodiment provides a refrigeration system, including: a refrigerant inventory estimation device for the refrigeration system provided in the second aspect, as well as a compressor, a condenser, an expansion valve, an evaporator, a first temperature sensor, a first pressure sensor, and a second temperature sensor.

[0043] The compressor is connected to the condenser, the condenser is connected to the expansion valve, the expansion valve is connected to the evaporator, and the evaporator is connected to the compressor; the first pressure sensor and the first temperature sensor are located at the outlet of the condenser; the second temperature sensor is located at the inlet of the expansion valve; the first temperature sensor, the first pressure sensor, and the second temperature sensor are respectively connected to the refrigerant storage estimation device of the refrigeration system.

[0044] The refrigerant inventory estimation method for refrigeration systems provided in this embodiment addresses the problems of existing refrigerant inventory estimation methods, such as complex operation, weak anti-interference ability, and low accuracy. This embodiment's method determines the presence of abnormal flash gas in the refrigeration system, calculates the flash gas ratio based on first and second temperature information and the latent heat of vaporization of the refrigerant under first pressure information, corrects the subcooling at the condenser outlet, and obtains the corrected subcooling. Based on the corrected subcooling at the condenser outlet and a correlation model between the corrected subcooling and refrigerant inventory, real-time and accurate estimation of the refrigerant inventory in the refrigeration system is achieved. This method also boasts advantages such as ease of operation, strong versatility, and strong anti-interference ability. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0046] Figure 1 This is a flowchart of a method for estimating the refrigerant inventory in a refrigeration system provided in an embodiment of the present invention;

[0047] Figure 2 This is a schematic diagram of the structure of a refrigeration system provided in an embodiment of the present invention;

[0048] Figure 3 This is a flowchart of another method for estimating the refrigerant inventory in a refrigeration system provided by an embodiment of the present invention;

[0049] Figure 4 This is a fitting curve of the refrigerant inventory and the corresponding subcooling at the condenser outlet provided in an embodiment of the present invention.

[0050] Figure 5 This is a flowchart of another method for estimating the refrigerant inventory in a refrigeration system provided in an embodiment of the present invention. Detailed Implementation

[0051] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0052] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0053] Based on the above-mentioned technical problems, this embodiment proposes the following solutions:

[0054] Figure 1 This is a flowchart illustrating a method for estimating the refrigerant inventory in a refrigeration system according to an embodiment of the present invention. See also... Figure 1 The method for estimating the refrigerant inventory in a refrigeration system provided in this embodiment of the invention includes:

[0055] S101. Obtain the first temperature information of the refrigerant at the condenser outlet. and first pressure information Second temperature information of the refrigerant at the expansion valve inlet .

[0056] Specifically, Figure 2 This is a schematic diagram of a refrigeration system provided in an embodiment of the present invention. See also... Figure 2 The refrigeration system may include a compressor 1, a condenser 2, an expansion valve 3, an evaporator 4, a refrigerant mass flow meter 5, a gas-liquid separator 6, and connecting pipes 7. Sensors 8 are installed at key locations in the refrigeration system to collect operating parameters, providing a data basis for calculating the subcooling degree at the outlet of the condenser 2 and estimating the refrigerant inventory.

[0057] For example, a first temperature sensor 801 and a first pressure sensor 802 are installed at the outlet of condenser 2 to collect the actual temperature and pressure of the refrigerant at the outlet of condenser 2.

[0058] For example, a second temperature sensor 811 and a second pressure sensor 812 are installed in the inlet pipe of the expansion valve 3 to collect the actual temperature and pressure of the refrigerant at the inlet of the expansion valve 3.

[0059] For example, a third temperature sensor 821 and a third pressure sensor 822 can be installed at the inlet of evaporator 4 to collect the actual temperature of the refrigerant at the inlet of evaporator 4. With pressure A fourth temperature sensor 841 and a fourth pressure sensor 842 are installed at the outlet of evaporator 4 to collect the actual temperature of the refrigerant at the outlet of evaporator 4. With pressure A sixth pressure sensor 85 is installed at the compressor intake port to collect the compressor intake pressure.

[0060] Among them, the measurement accuracy of sensor 8 must meet the following requirements: temperature sensor accuracy ±0.2℃, pressure sensor accuracy ±0.13% of full scale, to ensure the accuracy of parameter acquisition.

[0061] If the refrigeration system is a single-temperature zone device, the actual temperature and pressure of the refrigerant at the condenser outlet can be used as the temperature information of the refrigerant at the condenser outlet. and stress information .

[0062] If the refrigeration system is a multi-temperature zone device containing multiple parallel evaporators, a temperature sensor and a pressure sensor should be installed at the outlet of each condenser, and the average temperature of all condenser outlets should be taken as the temperature information. The average pressure at all condenser outlets is taken as the pressure information. This is to eliminate the uneven parameter effects caused by differences in the piping of multiple indoor units.

[0063] S102, Based on the first pressure information at the condenser outlet and the first temperature information of the refrigerant at the outlet of the condenser Determine the subcooling degree at the condenser outlet. .

[0064] Specifically, the subcooling at the condenser outlet refers to the difference between the refrigerant temperature at the condenser outlet and the refrigerant saturation temperature at the corresponding pressure. The subcooling at the condenser outlet directly reflects the liquefaction stability of the refrigerant in the section from condenser 2 to expansion valve 3, and its changes are strongly coupled with the refrigerant level in the refrigeration system. For example, when the refrigerant level decreases, the refrigerant level in condenser 2 drops, resulting in insufficient heat exchange and a significant decrease in the subcooling at the condenser 2 outlet. Conversely, when the refrigerant level is excessive, the subcooling at the condenser 2 outlet will increase abnormally.

[0065] S103. Based on the difference between the subcooling degree at the condenser outlet and the preset subcooling degree threshold, it is determined that there is abnormal flash gas in the refrigeration system.

[0066] Specifically, if the subcooling at the condenser outlet is less than a preset subcooling threshold, and it is determined that there is abnormal flash gas in the refrigeration system, then step S104 is executed. For example, the preset subcooling threshold can be zero.

[0067] S104, Based on the first temperature information and the second temperature information And the refrigerant in the first pressure information The latent heat of vaporization is used to calculate the flash gas ratio, and the subcooling at the condenser outlet is corrected to obtain the corrected subcooling.

[0068] Specifically, the current first temperature information at the condenser outlet. and the second temperature information of the expansion valve inlet The temperature difference, and the refrigerant in the first pressure information The latent heat of vaporization is used to calculate the flash gas ratio. The subcooling at the condenser outlet is then corrected using the flash gas ratio to generate a corrected subcooling at the condenser outlet.

[0069] S105. Based on the corrected subcooling at the condenser outlet, and using the correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory, estimate the refrigerant inventory of the refrigeration system.

[0070] Specifically, the corrected subcooling at the condenser outlet is input into the correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory, and the refrigerant inventory is calculated and output. Because the calculation is performed through the correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory, the interference of abnormal flash gas on the refrigerant inventory estimation is reduced, improving the accuracy of the refrigerant inventory estimation. The refrigerant inventory estimation method for refrigeration systems provided in this embodiment addresses the problems of existing refrigerant inventory estimation methods being complex to operate, having weak anti-interference capabilities, and low accuracy. This embodiment's refrigerant inventory estimation method determines the presence of abnormal flash gas in the refrigeration system, calculates the flash gas ratio based on the first and second temperature information, and the latent heat of vaporization of the refrigerant under the first pressure information, corrects the subcooling at the condenser outlet, and obtains the corrected subcooling. Based on the corrected subcooling at the condenser outlet, and using a correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory, the system can achieve real-time and accurate estimation of the refrigerant inventory in the refrigeration system. It also has the advantages of being easy to operate, highly versatile, and having strong anti-interference capabilities.

[0071] In one optional implementation, if the subcooling at the condenser outlet is greater than or equal to a preset subcooling threshold, and it is determined that there is no abnormal flash gas in the refrigeration system, then the refrigerant inventory of the refrigeration system can be estimated based on the subcooling at the condenser outlet and a refrigerant inventory correlation model.

[0072] Optionally, based on the above embodiments, step S104, based on the first temperature information... and the second temperature information And the refrigerant in the first pressure information The latent heat of vaporization is used to calculate the flash gas ratio, and the subcooling at the condenser outlet is corrected to obtain the corrected subcooling, including:

[0073] Firstly, based on the first temperature information and the second temperature information The product of the difference and the isobaric specific heat capacity of the refrigerant in the subcooled liquid state, and the product of the refrigerant under the first pressure information. The ratio of latent heat of vaporization is used to calculate the flash gas ratio. .

[0074] Specifically, the first temperature information Second temperature information The difference Based on the first temperature information Second temperature information The difference Based on the refrigerant type, such as R134A, R32, R410A, etc., the flash gas ratio is calculated using a flash gas generation model. Flash gas ratio It refers to the ratio of the mass of flash gas to the total mass of refrigerant.

[0075] Flash gas ratio The following formula can be used for calculation: .in, This is the isobaric specific heat capacity of the refrigerant in a subcooled liquid state, in kJ / (kg・℃), which can be obtained from the refrigerant thermodynamic property table. For refrigerant, first pressure information The latent heat of vaporization at the corresponding pressure, in kJ / kg, can be obtained from the refrigerant thermodynamic property table.

[0076] Secondly, calculate the flash gas correction factor based on the flash gas ratio.

[0077] Specifically, the correction factor for flash gas The following formula is used for calculation: .in, This is the correction factor for flash gases, with a range of values: , This refers to the flash gas ratio.

[0078] Third, the corrected subcooling is determined by multiplying the flash gas correction coefficient by the subcooling at the condenser outlet.

[0079] Specifically, the corrected undercooling The following formula is used for calculation: .in, The subcooling at the condenser outlet. This is the correction factor for flash gas.

[0080] Optionally, based on the above embodiments, step S102, based on the first pressure information at the condenser outlet... and the first temperature information of the refrigerant at the outlet of the condenser Determine the subcooling degree at the condenser outlet. ,include:

[0081] Firstly, based on the first pressure information at the condenser outlet. Determine the first pressure information at the condenser outlet. The corresponding saturation temperature of the refrigerant .

[0082] Secondly, based on the first temperature information of the refrigerant at the condenser outlet. With the saturation temperature The difference is used to determine the subcooling at the condenser outlet. Specifically, based on the condenser outlet pressure information... By using the refrigerant thermodynamic property table and based on the type of refrigerant used in the refrigeration system, such as R134A, R23, or R410A, the first pressure information at the condenser outlet can be obtained. The corresponding saturation temperature of the refrigerant .

[0083] Calculate the actual subcooling at the condenser outlet. The formula is: .

[0084] in, This represents the actual subcooling at the condenser outlet (unit: °C). This is the actual refrigerant temperature information at the condenser outlet (unit: °C). First pressure information at the condenser outlet The corresponding saturation temperature of the refrigerant (unit: °C).

[0085] Optional, Figure 3 This is a flowchart illustrating another method for estimating the refrigerant inventory in a refrigeration system provided by an embodiment of the present invention. Based on the above embodiments, see [link to other embodiments]. Figure 3 The method for estimating the refrigerant inventory in a refrigeration system provided in this embodiment of the invention may include:

[0086] S201. Obtain the first temperature information of the refrigerant at the condenser outlet. and first pressure information Second temperature information of the refrigerant at the expansion valve inlet .

[0087] S202, Based on the first pressure information at the condenser outlet and the first temperature information of the refrigerant at the outlet of the condenser Determine the subcooling degree at the condenser outlet. .

[0088] S203. Based on the difference between the subcooling degree at the condenser outlet and the preset subcooling degree threshold, it is determined that there is abnormal flash gas in the refrigeration system.

[0089] S204, Based on the first temperature information and the second temperature information And the refrigerant in the first pressure information The latent heat of vaporization is used to calculate the flash gas ratio, and the subcooling at the condenser outlet is corrected to obtain the corrected subcooling.

[0090] S205. Based on the calibration experiment, determine the correlation model between the corrected subcooling degree at the condenser outlet of the refrigeration system and the refrigerant inventory.

[0091] Specifically, through calibration experiments, experimental data on the corrected subcooling and refrigerant inventory at the condenser outlet of multiple refrigeration systems are obtained. Based on the experimental data on the corrected subcooling and refrigerant inventory at the condenser outlet of the refrigeration system, the functional relationship between the corrected subcooling and refrigerant inventory at the condenser outlet of the refrigeration system is determined, and then the correlation model between the corrected subcooling and refrigerant inventory at the condenser outlet of the refrigeration system is determined.

[0092] S206. Based on the corrected subcooling at the condenser outlet, and using the correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory, estimate the refrigerant inventory of the refrigeration system.

[0093] Optionally, based on the above embodiments, see also... Figure 3 Step S205 above, determining the corrected subcooling correlation model between the condenser outlet of the refrigeration system and the refrigerant inventory based on calibration experiments, may include:

[0094] First, set the calibration conditions, which include ambient temperature, evaporator load, and compressor frequency.

[0095] For details, please refer to [link / reference]. Figure 2 Collect compressor operating frequency f and ambient temperature. And evaporator load Q. Ambient temperature. The ambient temperature is on the condenser side. The evaporator load Q is the cooling capacity requirement on the evaporator side.

[0096] Experimental preparation: Before calibration, the refrigeration system needs to be evacuated, for example, the vacuum level needs to be adjusted. Let it stand for more than 2 hours to ensure that the refrigerant in the refrigeration system is evenly distributed and to avoid residual air or moisture interfering with the experimental data.

[0097] Calibration condition setting: Conduct the experiment under the rated operating conditions of the refrigeration system. The rated operating conditions of the refrigeration system can be ambient temperature. Evaporator load The compressor frequency f = the rated frequency.

[0098] Secondly, the refrigeration system was charged with different masses of refrigerant, starting from 70% of the designed refrigerant quantity, increasing in increments of 5% to 130% of the designed refrigerant quantity, and calibration experiments were conducted. The corrected subcooling at the condenser outlet was calculated for each experimental group corresponding to the refrigerant quantity. Record the quality of the corresponding refrigerant inventory.

[0099] Specifically, for example, the refrigeration system is charged with standard refrigerant of varying masses, ranging from 70% to 130% of the designed refrigerant quantity. The calculated corrected subcooling at the condenser outlet is recorded every 5% of the designed refrigerant quantity. Record the corresponding refrigerant inventory. (Unit: kg)

[0100] Thirdly, based on the mass of refrigerant stock from the calibration experiment and the corresponding corrected subcooling at the condenser outlet, the least squares method is used to fit and obtain the correlation model between the corrected subcooling at the condenser outlet and the refrigerant stock.

[0101] Specifically, Figure 4 This is a fitting curve of the refrigerant inventory and the corresponding corrected subcooling at the condenser outlet, provided by an embodiment of the present invention. (See also...) Figure 4 Green indicates the design refrigerant charge rating point, which corresponds to the corrected subcooling at the condenser outlet when the refrigerant charge is 8.5 kg. Blue represents all calibration experimental data points. The black curve is a quadratic fit curve between the corrected subcooling at the condenser outlet and the refrigerant charge corresponding to the calibration experimental data points.

[0102] Before calibration, the refrigeration system was evacuated to a high vacuum and allowed to stand to ensure the accuracy of the experimental data. Under rated operating conditions, standard refrigerant was charged at 70%~130% of the designed refrigerant quantity, and data was recorded at 5% intervals. A quadratic correlation model of "corrected subcooling at the condenser outlet - refrigerant inventory" was fitted using the least squares method, ensuring that the relative error of the correlation model was ≤5%, resulting in high accuracy in estimating the refrigerant inventory.

[0103] The refrigerant inventory estimation method for refrigeration systems provided in this embodiment eliminates the interference of flash gas caused by pipeline pressure drop and environmental heat absorption on subcooling measurement by introducing a flash gas correction coefficient. The correlation between subcooling and refrigerant inventory is significantly enhanced after correction. By focusing on the corrected subcooling at the condenser outlet—a key parameter strongly coupled with refrigerant inventory—and using high-precision sensor data acquisition and least-squares fitting of a quadratic correlation model, the relative estimation error is controlled within 5%, far superior to the error level of over 15% in related technologies. This embodiment provides accurate data support for the operation and maintenance of refrigeration systems.

[0104] Optionally, based on the above embodiments, the modified subcooling degree at the condenser outlet and the refrigerant inventory correlation model are calculated using the following formula: .in, Let be the mass of the refrigerant in the refrigeration system (unit: kg), and a, b, and c be model coefficients. This represents the corrected subcooling at the actual condenser outlet (unit: °C). The model coefficients are obtained by fitting calibration experimental data; different refrigerant types and refrigeration system structures correspond to different model coefficients, thus improving versatility. For example, Figure 4 The example shown is a=0.01, b=0.391, c=4.574, and no limitation is made here.

[0105] Optional, Figure 5 This is a flowchart illustrating another method for estimating the refrigerant inventory in a refrigeration system provided by an embodiment of the present invention. Based on the above embodiments, see [link to other embodiments]. Figure 5 The method for estimating the refrigerant inventory in a refrigeration system provided in this embodiment of the invention may include:

[0106] S301. Obtain the first temperature information of the refrigerant at the condenser outlet. and first pressure information Second temperature information of the refrigerant at the expansion valve inlet .

[0107] S302, Based on the first pressure information at the condenser outlet and the first temperature information of the refrigerant at the outlet of the condenser Determine the subcooling degree at the condenser outlet. .

[0108] S303. Based on the difference between the subcooling degree at the condenser outlet and the preset subcooling degree threshold, it is determined that there is abnormal flash gas in the refrigeration system.

[0109] S304, Based on the first temperature information and the second temperature information And the refrigerant in the first pressure information The latent heat of vaporization is used to calculate the flash gas ratio, and the subcooling at the condenser outlet is corrected to obtain the corrected subcooling.

[0110] S305. Based on the calibration experiment, determine the correlation model between the corrected subcooling degree at the condenser outlet of the refrigeration system and the refrigerant inventory.

[0111] S306. Based on the corrected subcooling at the condenser outlet, and using the correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory, estimate the refrigerant inventory of the refrigeration system.

[0112] S307. Obtain the current operating conditions of the refrigeration system.

[0113] Specifically, the current operating conditions of the refrigeration system include the current ambient temperature, current evaporator load, and current compressor frequency.

[0114] S308. Based on the difference between the current operating condition and the calibration operating condition, the correlation model between the subcooling and refrigerant inventory at the condenser outlet is corrected to determine the correlation model between the subcooling and refrigerant inventory at the condenser outlet after the operating condition is corrected.

[0115] Specifically, the rated operating condition refers to the ambient temperature under the rated operating conditions of the refrigeration system. Evaporator load compressor frequency =Rated frequency.

[0116] Based on the differences between the current operating conditions and the calibration conditions, the correlation model between the corrected subcooling and refrigerant inventory at the condenser outlet is modified. The modified correlation model between the corrected subcooling and refrigerant inventory at the condenser outlet is then determined, making the modified correlation model suitable for the accuracy requirements of refrigerant inventory estimation under different operating conditions.

[0117] S309. Based on the correlation model between the corrected subcooling degree at the condenser outlet and the refrigerant inventory after the operating condition correction, estimate the refrigerant inventory according to the corrected subcooling degree at the condenser outlet.

[0118] Specifically, the model relating the corrected subcooling at the condenser outlet to the refrigerant inventory under the corrected input conditions improves the accuracy of refrigerant inventory estimation under different operating conditions.

[0119] Optionally, based on the above embodiments, the step of correcting the correlation model between the subcooling and refrigerant inventory at the condenser outlet according to the difference between the current operating condition and the calibration operating condition, and determining the corrected correlation model between the subcooling and refrigerant inventory at the condenser outlet after the operating condition correction, includes:

[0120] First, obtain the ambient temperature under the current operating conditions. Evaporator load Q and compressor frequency f.

[0121] Secondly, based on the ambient temperature under the current operating conditions. Ambient temperature under calibration conditions The difference between the two, the evaporator load Q under the current operating condition and the evaporator load under the calibration condition. The difference between them, the compressor frequency f under the current operating condition and the compressor frequency under the calibrated operating condition The difference between the two values ​​is used to correct the correlation model between the subcooling and refrigerant inventory at the condenser outlet, resulting in the corrected correlation model between the subcooling and refrigerant inventory at the condenser outlet after operating condition correction.

[0122] Specifically, when there is a deviation between the actual operating conditions and the calibration operating conditions, the correlation model between the subcooling at the condenser outlet and the refrigerant inventory is corrected by introducing an operating condition correction coefficient, thereby improving the estimation accuracy under different operating conditions. For example, the value range of the operating condition correction coefficient is -0.01 to 0.01.

[0123] Optionally, based on the above embodiments, the modified subcooling degree of the condenser outlet and the refrigerant inventory correlation model adopts the following formula:

[0124] .

[0125] in, This is an estimated value (in kg) of the refrigerant stock after operating condition correction. , , These are the ambient temperature, evaporator load, and compressor frequency under the rated operating conditions. , , This is the working condition correction factor.

[0126] Optionally, based on the above embodiments, after estimating the refrigerant inventory of the refrigeration system according to the corrected subcooling at the condenser outlet and a refrigerant inventory correlation model, the system may further include:

[0127] Step 1: Trigger a refrigerant shortage warning based on the difference between the refrigerant inventory and the first preset inventory threshold.

[0128] Step 2: Trigger an over-refrigerant warning based on the difference between the refrigerant level and the second preset refrigerant level threshold. The first preset refrigerant level threshold is less than the second preset refrigerant level threshold.

[0129] Specifically, the first preset refrigerant level threshold can be 0.8 × the designed refrigerant quantity. The second preset refrigerant level threshold can be 1.2 × the designed refrigerant quantity. For example, when the refrigerant level is less than the first preset level threshold, a refrigerant shortage warning is triggered. When the refrigerant level is greater than the second preset level threshold, a refrigerant excess warning is triggered, thus achieving timely warning of the refrigerant status of the refrigeration system.

[0130] An alternative implementation, exemplary, is illustrated below with a refrigeration system for a 10HP split-type environmental test facility using R410A refrigerant (design refrigerant capacity). Taking (e.g., 8.5kg) as an example, the specific implementation process of the present invention will be described in detail:

[0131] This embodiment provides a specific implementation method for a system calibration experiment as follows:

[0132] Experimental Preparation: The refrigeration system of the environmental testing equipment was installed in the enthalpy difference laboratory to precisely control the ambient temperature and evaporator load. The refrigeration system was evacuated to a vacuum degree ≤50Pa and allowed to stand for 2 hours. Sensors were installed: Temperature sensor: Pt100 three-wire system, accuracy ±0.2℃. Pressure sensor: piezoelectric type, accuracy ±0.13% FS.

[0133] Calibration conditions: enthalpy difference, laboratory condenser side ambient temperature =35℃; Evaporator load on evaporator side =100%, which is the design cooling capacity; compressor frequency =60Hz, which is the rated frequency.

[0134] Data acquisition: R410A refrigerant was charged into the refrigeration system, starting from 6.0 kg ( Start at 0.4 kg intervals (approximately) Record the data once, until it reaches 11.0 kg. A total of 13 data points were collected, and some of the data is shown in Table 1 below:

[0135] Table 1 shows the relationship between the parameter information of the refrigeration system and the actual refrigerant inventory.

[0136]

[0137] Model Fitting: The least squares method was used to fit the above 13 data points to obtain the correlation model of "corrected subcooling at condenser outlet - refrigerant inventory". .

[0138] Model validation: Combining Figure 3 Select refrigerant inventory The corrected subcooling at the condenser outlet at three points (7.0 kg, 9.5 kg, and 10.0 kg) is substituted into the "corrected subcooling at condenser outlet - refrigerant inventory" correlation model to calculate... The values ​​were 6.98 kg, 9.55 kg, and 10.02 kg, respectively, with relative errors of ≤0.5%, indicating that the correlation model of "corrected subcooling at condenser outlet - refrigerant inventory" is qualified.

[0139] Operating condition correction factor calibration: changing ambient temperature ( Multi-condition calibration was performed using parameters at 30℃ and 40℃, evaporator load (Q=80%, 120%), and compressor frequency (f=50Hz, 70Hz), and the resulting calibration coefficients were fitted to obtain the corrected operating conditions. =0.005 ( ), =0.003 ( (Based on design load) =0.002 ( ).

[0140] This embodiment provides a specific implementation method for real-time refrigerant inventory estimation as follows:

[0141] Parameter acquisition: The actual operating parameters of the refrigeration system at a certain moment are as follows: =32℃, Q=90%, f=55Hz. Real-time acquisition of: First pressure information at the condenser outlet. =2631kPa, first temperature information at the condenser outlet. =40.8℃, second pressure information at the expansion valve inlet =2602kPa, second temperature information at the expansion valve inlet. =41.0℃. Calculate the actual subcooling at the actual condenser outlet. :

[0142] Depend on =2631kPa. Referring to the thermodynamic property table of R410A, we get... =43.5℃.

[0143] (<0, flash gas correction is required).

[0144] Calculate the correction factor for flash gas With the corrected undercooling :

[0145] = 2631 - 2602 = 29kPa, = 40.8 - 41.0 = -0.2℃ (take the absolute value of 0.2℃).

[0146] From the R410A thermodynamic property table, we find: cp_r = 1.85 kJ / (kg・℃). =235kJ / kg.

[0147] = (1.85×0.2) / 235 ≈ 0.00158. = 1 / (1 + 0.00158) ≈ 0.9984.

[0148] = (-2.7)×0.9984 ≈ -2.696℃. This is the corrected supercooling. A negative result indicates a severe shortage of refrigerant in the refrigeration system, requiring further analysis using a model.

[0149] Refrigerant inventory estimation:

[0150] Will Substituting -2.696℃ into the formula "corrected subcooling at condenser outlet - refrigerant inventory" and applying it to the relevant model:

[0151] = ≈ 0.021×7.27 - 0.412 +4.215 ≈ 0.153 - 0.412 + 4.215 ≈ 3.956kg.

[0152] Operating condition correction:

[0153] = 3.956×[1 + 0.005×(32-35) + 0.003×(90%-100%) + 0.002×(55-60)]

[0154] = 3.956×[1 + 0.005×(-3) + 0.003×(-0.1) + 0.002×(-5)]

[0155] = 3.956 × [1 - 0.015 - 0.0003 - 0.01]

[0156] = 3.956×0.9747 ≈ 3.856kg.

[0157] Early warning output: The refrigerant level is approximately 3.856 kg < 0.8 × 8.5 = 6.8 kg, triggering a "severe refrigerant shortage" warning and prompting maintenance personnel to replenish the refrigerant.

[0158] The refrigerant inventory estimation method for the refrigeration system provided in this embodiment does not require interruption of the refrigeration system operation. By collecting parameters such as temperature and pressure information in real time, it can achieve refrigerant inventory estimation 1 to 5 times per second, which meets the real-time monitoring needs of the dynamic operation of the refrigeration system and is especially suitable for complex refrigeration systems that require dynamic adjustment.

[0159] The refrigerant inventory estimation method for the refrigeration system provided in this embodiment fits the model coefficients through a single calibration experiment for different refrigeration systems and different types of refrigerants. It can be adapted to different refrigerant types, such as R134A, R23, and R410A, and can also be adapted to refrigeration systems with different structures, such as industrial refrigeration equipment and commercial chiller units. There is no need to redevelop the algorithm for different systems, so it has a wide range of applications.

[0160] The refrigerant inventory estimation method for the refrigeration system provided in this embodiment does not require additional complex hardware. It only requires the addition of a small number of high-precision temperature and pressure sensors to the existing refrigeration system. Some refrigeration systems already have relevant temperature and pressure sensors, which can be directly reused. The method is easy to install and maintain, has low investment costs, and is convenient for engineering promotion and application.

[0161] In addition to the core function of estimating refrigerant inventory, the refrigerant inventory estimation method provided in this embodiment can extend to automatic early warning based on the estimation results, intelligent refrigerant replenishment control for refrigerant shortage and / or refrigerant excess, and provide data basis for refrigeration system optimization and compressor overheat protection, effectively improving the overall intelligent operation level and reliability of the refrigeration system.

[0162] Based on the same inventive concept, this embodiment provides a device for estimating the refrigerant inventory in a refrigeration system. The device for estimating the refrigerant inventory in a refrigeration system provided in this embodiment may include:

[0163] The acquisition module is used to acquire the first temperature and first pressure information of the refrigerant at the condenser outlet, and the second temperature information of the refrigerant at the expansion valve inlet.

[0164] The subcooling calculation module is used to determine the subcooling of the condenser outlet based on the first pressure information of the condenser outlet and the first temperature information of the refrigerant at the condenser outlet.

[0165] The flash gas detection module is used to determine whether there is abnormal flash gas in the refrigeration system based on the difference between the subcooling degree at the condenser outlet and a preset subcooling threshold.

[0166] The subcooling correction module is used to calculate the flash gas ratio based on the first temperature information and the second temperature information, as well as the latent heat of vaporization of the refrigerant under the first pressure information, and to correct the subcooling at the condenser outlet to obtain the corrected subcooling.

[0167] The estimation module is used to estimate the refrigerant inventory of the refrigeration system based on the corrected subcooling at the condenser outlet and a correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory.

[0168] The refrigerant inventory estimation device for a refrigeration system provided in this embodiment addresses the problems of complex operation, weak anti-interference ability, and low accuracy of existing refrigerant inventory estimation devices. This device acquires the first temperature and first pressure information of the refrigerant at the condenser outlet and the second temperature information of the refrigerant at the expansion valve inlet through an acquisition module. Then, a subcooling calculation module determines the subcooling at the condenser outlet based on the first pressure and first temperature information of the refrigerant at the condenser outlet. Next, a flash gas determination module determines the presence of abnormal flash gas in the refrigeration system based on the difference between the subcooling at the condenser outlet and a preset subcooling threshold. Finally, a subcooling correction module calculates the flash gas ratio based on the first and second temperature information and the latent heat of vaporization of the refrigerant at the first pressure information, correcting the subcooling at the condenser outlet to obtain the corrected subcooling. Finally, the estimation module estimates the refrigerant inventory of the refrigeration system based on the corrected subcooling at the condenser outlet and a correlation model between the corrected subcooling and refrigerant inventory. The refrigerant inventory estimation device for the refrigeration system provided in this embodiment achieves real-time and accurate estimation of the refrigerant inventory, while also possessing advantages such as ease of operation, strong versatility, and strong anti-interference capability.

[0169] Based on the same inventive concept, this embodiment provides a refrigeration system. See also... Figure 2The refrigeration system provided in this embodiment includes a refrigerant quantity estimation device for the refrigeration system provided in any of the above embodiments, as well as a compressor 1, a condenser 2, an expansion valve 3, an evaporator 4, a first temperature sensor 801, a first pressure sensor 802, and a second temperature sensor 811. The compressor 1 is connected to the condenser 2, the condenser 2 is connected to the expansion valve 3, the expansion valve 3 is connected to the evaporator 4, and the evaporator 4 is connected to the compressor 1. The first pressure sensor 802 and the first temperature sensor 801 are located at the outlet of the condenser 2; the second temperature sensor 811 is located at the inlet of the expansion valve 3; the first temperature sensor 801, the first pressure sensor 802, and the second temperature sensor 811 are respectively connected to the refrigerant quantity estimation device of the refrigeration system. In an optional embodiment, the refrigerant quantity estimation device of the refrigeration system can be integrated into the control unit 40.

[0170] It should be noted that, Figure 2 The diagram illustrates, for example, that 10 is the outdoor unit of the refrigeration system, 20 is the indoor unit, 30 is the data storage unit, 40 is the control unit, and 50 is the display unit. The control unit is connected to the sensor 8 and is used to acquire the first temperature and first pressure information of the refrigerant at the outlet of the condenser 2, and the second temperature information of the refrigerant at the inlet of the expansion valve 3, collected by the sensor 8. The data storage unit 30 is connected to the control unit 40 and is used to store data such as the first temperature and first pressure information of the refrigerant at the outlet of the condenser 2, the second pressure and second temperature information of the refrigerant at the inlet of the expansion valve, and the corrected subcooling correlation model of the condenser outlet and refrigerant inventory. The display unit 50 is connected to the control unit and is used to display the first temperature and first pressure information of the refrigerant at the outlet of the condenser 2, the second pressure and second temperature information of the refrigerant at the inlet of the expansion valve, refrigerant inventory estimation results, and warning information. Warning information may include information such as insufficient or excessive refrigerant.

[0171] The refrigeration system provided in this embodiment includes the refrigerant inventory estimation device of the refrigeration system provided in any of the above embodiments, and has the beneficial effects of the refrigerant inventory estimation device of the refrigeration system provided in any of the above embodiments, which will not be described in detail here.

[0172] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for estimating the refrigerant inventory in a refrigeration system, characterized in that, include: Obtain the first temperature information of the refrigerant at the condenser outlet. and first pressure information Second temperature information of the refrigerant at the expansion valve inlet ; Based on the first pressure information at the condenser outlet and the first temperature information of the refrigerant at the outlet of the condenser Determine the subcooling degree at the condenser outlet. ; Based on the subcooling at the condenser outlet The difference between the actual value and the preset subcooling threshold indicates that there is abnormal flash gas in the refrigeration system. Based on the first temperature information and the second temperature information And the refrigerant in the first pressure information The latent heat of vaporization is used to calculate the flash gas ratio and correct the subcooling at the condenser outlet. The corrected undercooling was obtained; Based on the corrected subcooling at the condenser outlet, and using a correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated.

2. The method according to claim 1, characterized in that, The first temperature information and the second temperature information And the refrigerant in the first pressure information The latent heat of vaporization is used to calculate the flash gas ratio and correct the subcooling at the condenser outlet. The corrected undercooling is obtained, including: Based on the first temperature information and the second temperature information The product of the difference and the isobaric specific heat capacity of the refrigerant in the subcooled liquid state, and the product of the refrigerant under the first pressure information. The ratio of latent heat of vaporization is used to calculate the flash gas ratio. ; Calculate the flash gas correction factor based on the flash gas ratio; Based on the flash gas correction factor and the subcooling at the condenser outlet The product of these factors determines the corrected subcooling.

3. The method according to claim 1 or 2, characterized in that, The first pressure information from the condenser outlet and the first temperature information of the refrigerant at the outlet of the condenser Determine the subcooling degree at the condenser outlet. ,include: Based on the first pressure information at the condenser outlet Determine the first pressure information at the condenser outlet. The corresponding saturation temperature of the refrigerant ; Based on the first temperature information of the refrigerant at the condenser outlet With the saturation temperature The difference is used to determine the subcooling at the condenser outlet. .

4. The method according to claim 1 or 2, characterized in that, Before estimating the refrigerant inventory of the refrigeration system based on the corrected subcooling at the condenser outlet and a refrigerant inventory correlation model, the method further includes: Based on calibration experiments, a corrected correlation model between the subcooling at the condenser outlet of the refrigeration system and the refrigerant inventory was determined.

5. The method according to claim 4, characterized in that, The subcooling degree at the condenser outlet of the refrigeration system is determined based on calibration experiments. Models relating to refrigerant inventory include: Set calibration conditions, which include ambient temperature, evaporator load, and compressor frequency; Calibration experiments were conducted by charging the refrigeration system with different masses of refrigerant, starting from 70% of the designed refrigerant quantity and increasing in increments of 5% to 130% of the designed refrigerant quantity. The corrected subcooling at the condenser outlet was calculated for each experimental group corresponding to its refrigerant quantity. And record the quality of the corresponding refrigerant inventory; Based on the mass of refrigerant stock from the calibration experiment and the corresponding corrected subcooling at the condenser outlet, a least squares method was used to fit and obtain a correlation model between the corrected subcooling at the condenser outlet and the refrigerant stock.

6. The method according to claim 1 or 2, characterized in that, After estimating the refrigerant inventory of the refrigeration system based on the corrected subcooling at the condenser outlet and a refrigerant inventory correlation model, the method further includes: Obtain the current operating status of the refrigeration system; Based on the difference between the current operating conditions and the calibration conditions, the correlation model between the subcooling at the condenser outlet and the refrigerant inventory is modified, and the correlation model between the subcooling at the condenser outlet and the refrigerant inventory after the operating conditions are modified is determined. Based on the correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory after the operating condition correction, the refrigerant inventory is estimated according to the corrected subcooling at the condenser outlet.

7. The method according to claim 6, characterized in that, The step of correcting the correlation model between the subcooling and refrigerant inventory at the condenser outlet based on the difference between the current operating condition and the calibration operating condition, and determining the corrected correlation model between the subcooling and refrigerant inventory at the condenser outlet after the operating condition correction, includes: Obtain the ambient temperature under current operating conditions ( ), evaporator load (Q) and compressor frequency (f); Based on the ambient temperature under current operating conditions ( ) and ambient temperature under the rated operating conditions ( The difference between the current operating condition evaporator load (Q) and the rated operating condition evaporator load (Q) The difference between the compressor frequency (f) under the current operating condition and the compressor frequency under the calibrated operating condition (f) The difference between the two values ​​is used to correct the correlation model between the subcooling at the condenser outlet and the refrigerant inventory, resulting in the corrected correlation model between the subcooling at the condenser outlet and the refrigerant inventory after operating condition correction.

8. The method according to any one of claims 1, 2, 5 or 7, characterized in that, After estimating the refrigerant inventory of the refrigeration system based on the corrected subcooling at the condenser outlet and a refrigerant inventory correlation model, the method further includes: Based on the difference between the refrigerant inventory and the first preset inventory threshold, a refrigerant shortage warning is triggered; Based on the difference between the refrigerant inventory and the second preset inventory threshold, a refrigerant overload warning is triggered; The first preset inventory threshold is less than the second preset inventory threshold.

9. A device for estimating the refrigerant inventory in a refrigeration system, characterized in that, include: The acquisition module is used to acquire the first temperature information of the refrigerant at the condenser outlet. ) and first pressure information ( The second temperature information of the refrigerant at the expansion valve inlet ( ); The subcooling calculation module is used to calculate the subcooling based on the first pressure information at the condenser outlet ( ) and the first temperature information of the refrigerant at the outlet of the condenser ( Determine the subcooling degree at the condenser outlet. ; The flash gas determination module is used to determine the amount of gas emitted based on the subcooling at the condenser outlet. The difference between the actual value and the preset subcooling threshold indicates that there is abnormal flash gas in the refrigeration system. The supercooling correction module is used to adjust the temperature based on the first temperature information ( ) and the second temperature information ( ), and the refrigerant in the first pressure information ( The latent heat of vaporization at the specified temperature is used to calculate the flash gas ratio and correct the subcooling at the condenser outlet. The corrected undercooling was obtained; The estimation module is used to estimate the refrigerant inventory of the refrigeration system based on the corrected subcooling at the condenser outlet and a correlation model between the corrected subcooling at the condenser outlet and the refrigerant inventory.

10. A refrigeration system, characterized in that, include: The refrigerant inventory estimation device for the refrigeration system according to claim 9, as well as the compressor, condenser, expansion valve, evaporator, and the first temperature sensor, the first pressure sensor, and the second temperature sensor; The compressor is connected to the condenser, the condenser is connected to the expansion valve, the expansion valve is connected to the evaporator, and the evaporator is connected to the compressor; the first pressure sensor and the first temperature sensor are located at the outlet of the condenser; the second temperature sensor is located at the inlet of the expansion valve; the first temperature sensor, the first pressure sensor, and the second temperature sensor are respectively connected to the refrigerant storage estimation device of the refrigeration system.

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