Method for estimating refrigerant inventory of refrigeration system, estimation device, and refrigeration system

Abstract

The embodiment of the present application provides a kind of refrigerant inventory estimation method of refrigeration system, estimation device and refrigeration system.The method comprises obtaining the first temperature information of refrigerant at the inlet of throttling valve, first pressure information and the refrigerant quality information at the inlet of throttling valve;According to the first pressure information at the inlet of throttling valve and the first temperature information of refrigerant at the inlet of throttling valve, determine the supercooling degree at the inlet of throttling valve;According to the refrigerant quality information at the inlet of throttling valve, calculate flash gas correction coefficient;According to the supercooling degree at the inlet of throttling valve, obtain the modified supercooling degree at the inlet of throttling valve by the flash gas correction coefficient;According to the modified supercooling degree at the inlet of throttling valve, based on the modified supercooling degree at the inlet of throttling valve and refrigerant inventory correlation model, estimate the refrigerant inventory of refrigeration system.The technical scheme provided by the embodiment can improve the precision of quality estimation of refrigerant inventory.

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: This invention provides a method for estimating the refrigerant inventory in a refrigeration system, comprising: Obtain the first temperature information of the refrigerant at the throttle valve inlet. First pressure information and the refrigerant dryness information at the inlet of the throttle valve ; Based on the first pressure information at the throttle valve inlet and the first temperature information of the refrigerant at the inlet of the throttle valve Determine the subcooling degree at the inlet of the throttle valve. ; Based on the refrigerant dryness information at the throttle valve inlet Calculate the correction factor for flash gas. ; According to the flash gas correction factor Correcting the subcooling at the inlet of the throttle valve The corrected subcooling at the throttle valve inlet is obtained. ; Based on the corrected subcooling at the inlet of the throttle valve Based on the modified subcooling correlation model of the throttle valve inlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated.

[0006] Secondly, this embodiment provides a device for estimating the refrigerant inventory of a refrigeration system, comprising: The acquisition module is used to acquire the first temperature information of the refrigerant at the inlet of the throttle valve. First pressure information and the refrigerant dryness information at the inlet of the throttle valve ; The subcooling calculation module is used to calculate the subcooling based on the first pressure information at the inlet of the throttle valve. and the first temperature information of the refrigerant at the inlet of the throttle valve Determine the subcooling degree at the inlet of the throttle valve. ; The flash gas coefficient determination module is used to determine the refrigerant dryness information at the inlet of the throttle valve. Calculate the correction factor for flash gas. ; The supercooling correction module is used to adjust the supercooling based on the flash gas correction coefficient. Correcting the subcooling at the inlet of the throttle valve The corrected subcooling at the throttle valve inlet is obtained. ;; The estimation module is used to estimate the corrected subcooling at the inlet of the throttle valve. Based on the modified subcooling correlation model of the throttle valve inlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated.

[0007] 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, a throttle valve, an evaporator, a first temperature sensor, a first pressure sensor, and a refrigerant dryness detection device; The compressor is connected to the condenser, the condenser is connected to the throttle valve, the throttle valve is connected to the evaporator, and the evaporator is connected to the compressor; the first pressure sensor, the first temperature sensor, and the refrigerant dryness detection device are located at the inlet of the throttle valve; the first temperature sensor, the first pressure sensor, and the refrigerant dryness detection device are respectively connected to the refrigerant inventory estimation device of the refrigeration system.

[0008] 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 utilizes a refrigerant dryness detection device to detect the refrigerant dryness information at the inlet of the throttle valve. Based on the refrigerant dryness information at the throttle valve inlet. Calculate the correction factor for flash gas. According to the flash gas correction factor Correcting the subcooling at the inlet of the throttle valve The corrected subcooling at the throttle valve inlet is obtained. And based on the corrected subcooling at the throttle valve inlet. Based on the correlation model between the corrected subcooling at the throttle valve inlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated. This allows for real-time and accurate estimation of the refrigerant inventory of the refrigeration system, while also offering advantages such as ease of operation, strong versatility, and strong anti-interference capabilities. Attached Figure Description

[0009] 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.

[0010] 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; Figure 2 This is a schematic diagram of the structure of a refrigeration system provided in an embodiment of the present invention; 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; Figure 4 This is a fitting curve of the refrigerant inventory and the corrected subcooling degree of the corresponding throttle valve inlet provided by an embodiment of the present invention; 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

[0011] 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.

[0012] 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.

[0013] Based on the above-mentioned technical problems, this embodiment proposes the following solutions: Figure 1 This is a flowchart illustrating a method for estimating the refrigerant inventory in a refrigeration system, provided in 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: S101. Obtain the first temperature information of the refrigerant at the inlet of the throttle valve. First pressure information and the refrigerant dryness information at the inlet of the throttle valve .

[0014] 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, a throttle 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 throttle valve inlet and estimating the refrigerant inventory.

[0015] For example, a first temperature sensor 811 and a first pressure sensor 812 are installed at the inlet of the throttle valve to collect the actual temperature and pressure of the refrigerant at the throttle valve inlet. A refrigerant dryness detection device 11 is installed at the inlet of the throttle valve to collect the refrigerant dryness information at the throttle valve inlet. .

[0016] For example, a second temperature sensor 821 and a second pressure sensor 822 can be installed at the inlet of evaporator 4 to collect the actual temperature T3 and pressure P3 of the refrigerant at the inlet of evaporator 4. A third temperature sensor 841 and a third pressure sensor 842 can be installed at the outlet of evaporator 4 to collect the actual temperature T4 and pressure P4 of the refrigerant at the outlet of evaporator 4. A fifth pressure sensor 85 can be installed at the compressor suction port to collect the compressor suction pressure.

[0017] 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.

[0018] If the refrigeration system is a single-temperature zone device, the actual temperature and pressure of the refrigerant at the throttle valve inlet can be used as the temperature information T1 and pressure information P1 of the refrigerant at the throttle valve inlet.

[0019] If the refrigeration system is a multi-temperature zone device containing multiple parallel evaporators, a temperature sensor, a pressure sensor, and a refrigerant dryness detection device 11 should be installed at the inlet of each expansion valve. The average temperature of all expansion valve inlets should be taken as temperature information T1, the average pressure of all expansion valve inlets should be taken as pressure information P1, and the average refrigerant dryness of all expansion valve inlets should be taken as refrigerant dryness information. This is to eliminate the uneven parameter effects caused by differences in the piping of multiple indoor units.

[0020] S102, Based on the first pressure information at the throttle valve inlet... and the first temperature information of the refrigerant at the inlet of the throttle valve Determine the subcooling degree at the inlet of the throttle valve. .

[0021] Specifically, the subcooling at the throttle valve inlet refers to the difference between the refrigerant temperature at the throttle valve inlet and the refrigerant saturation temperature at the corresponding pressure. The subcooling at the throttle valve inlet directly reflects the liquefaction stability of the refrigerant in the section from condenser 2 to throttle 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 throttle valve inlet. Conversely, when the refrigerant level is excessive, the subcooling at the throttle valve inlet will increase abnormally.

[0022] S103. Based on the refrigerant dryness information at the inlet of the throttle valve. Calculate the correction factor for flash gas. .

[0023] Specifically, when the refrigerant dryness information x=0, i.e., there is no flash gas, the flash gas correction factor is... No attenuation; when refrigerant dryness information x>0, i.e. flash gas is present, flash gas correction factor. Targeted corrections are made to address the undercooling.

[0024] S104, Based on the flash gas correction coefficient Correcting the subcooling at the inlet of the throttle valve The corrected subcooling at the throttle valve inlet is obtained. .

[0025] Specifically, based on the flash gas correction factor Subcooling at the throttle valve inlet The correction can effectively prevent the subcooling of the throttle valve inlet by flash gas. The impact of calculation accuracy.

[0026] S105. Based on the corrected subcooling at the inlet of the throttle valve. Based on the modified subcooling correlation model of the throttle valve inlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated.

[0027] Specifically, the subcooling after correction at the throttle valve inlet... The corrected subcooling and refrigerant inventory correlation model input to the throttle valve inlet is used to calculate and output the refrigerant inventory. Because the calculation is performed using the corrected subcooling and refrigerant inventory correlation model at the throttle valve inlet, it is easier to reduce the interference of abnormal flash gas on the refrigerant inventory estimation, thus 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, such as complex operation, weak anti-interference ability, and low accuracy. The refrigerant inventory estimation method for refrigeration systems provided in this embodiment estimates the refrigerant inventory based on the refrigerant dryness information at the throttle valve inlet. Calculate the correction factor for flash gas. And according to the flash gas correction factor Correcting the subcooling at the inlet of the throttle valve The corrected subcooling at the throttle valve inlet is obtained. Based on the corrected subcooling at the throttle valve inlet, and using a correlation model between the corrected subcooling at the throttle valve inlet and the refrigerant inventory, the system achieves real-time and accurate estimation of the refrigerant inventory in the refrigeration system. It also boasts advantages such as ease of operation, strong versatility, and strong anti-interference capability.

[0028] Optionally, based on the above embodiments, step S102, based on the first pressure information at the inlet of the throttle valve... and the first temperature information of the refrigerant at the inlet of the throttle valve Determine the subcooling degree at the inlet of the throttle valve. ,include: Firstly, based on the first pressure information at the inlet of the throttle valve. Determine the first pressure information at the inlet of the throttle valve. The corresponding saturation temperature of the refrigerant .

[0029] Secondly, based on the first temperature information of the refrigerant at the inlet of the throttle valve. With the saturation temperature The difference is used to determine the subcooling at the inlet of the throttle valve. .

[0030] Specifically, based on the throttle valve inlet pressure information P1, the saturation temperature of the refrigerant corresponding to the first throttle valve inlet pressure information P1 is obtained by referring to the refrigerant thermodynamic property table and considering the type of refrigerant used in the refrigeration system, such as R134A, R23, R410A, etc. .

[0031] Calculate the actual subcooling at the throttle valve inlet. The formula is: = - .

[0032] in, The actual subcooling degree at the inlet of the throttle valve (unit: °C). This is the actual refrigerant temperature information at the throttle valve inlet (unit: °C). The first pressure information P1 at the throttle valve inlet corresponds to the saturation temperature of the refrigerant (unit: °C).

[0033] Optionally, based on the above embodiments, step S103, and the step of using the refrigerant dryness information at the throttle valve inlet... Calculate the correction factor for flash gas. ,include: Based on the refrigerant dryness information at the throttle valve inlet The flash gas correction factor is determined by multiplying it by the dryness factor. .

[0034] Specifically, the correction factor for flash gas The following formula is used for calculation: Wherein, k is the dryness factor, determined through calibration experiments, with a value ranging from 0.8 to 1.2 and a default value of 1.0. k characterizes the degree to which flash gas weakens the supercooling. The refrigerant dryness information at the inlet of the throttle valve is monitored in real time by the refrigerant dryness detection device 11.

[0035] Optionally, based on the above embodiments, step S104, and the step of adjusting the flash gas correction coefficient... Correcting the subcooling at the inlet of the throttle valve The corrected subcooling at the throttle valve inlet is obtained. ,include: According to the flash gas correction factor subcooling at the inlet of the throttle valve The product of these factors determines the corrected subcooling at the throttle valve inlet. .

[0036] Specifically, the corrected undercooling The following formula is used for calculation: ,Right now .in, The subcooling at the inlet of the throttle valve. This is the correction factor for flash gas.

[0037] 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: S201. Obtain the first temperature information of the refrigerant at the inlet of the throttle valve. First pressure information and the refrigerant dryness information at the inlet of the throttle valve .

[0038] S202, Based on the first pressure information at the inlet of the throttle valve and the first temperature information of the refrigerant at the inlet of the throttle valve Determine the subcooling degree at the inlet of the throttle valve. .

[0039] S203, Based on the refrigerant dryness information at the inlet of the throttle valve. Calculate the correction factor for flash gas. .

[0040] S204, Based on the flash gas correction coefficient Correcting the subcooling at the inlet of the throttle valve The corrected subcooling at the throttle valve inlet is obtained. .

[0041] S205. Based on the calibration experiment, determine the correlation model between the corrected subcooling degree and the refrigerant inventory at the throttle valve inlet of the refrigeration system.

[0042] Specifically, calibration experiments were conducted to obtain experimental data on the corrected subcooling and refrigerant quantity at the inlet of the refrigeration system's expansion valve. Based on these experimental data, a fitting process was performed to determine the functional relationship between the corrected subcooling and refrigerant quantity at the expansion valve inlet, thereby establishing a correlation model between the two.

[0043] S206. Based on the corrected subcooling at the inlet of the throttle valve. Based on the modified subcooling correlation model of the throttle valve inlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated.

[0044] Optionally, based on the above embodiments, see also... Figure 3 Step S205 above, determining the correlation model between the corrected subcooling degree and refrigerant inventory at the throttle valve inlet of the refrigeration system based on calibration experiments, may include: First, set the calibration conditions, which include ambient temperature, evaporator load, and compressor frequency.

[0045] For details, please refer to [link / reference]. Figure 2 Collect compressor operating frequency f and ambient temperature T a Evaporator load Q. Ambient temperature T. a The ambient temperature is on the condenser side. The evaporator load Q is the cooling capacity requirement on the evaporator side.

[0046] Experimental preparation: Before calibration, the refrigeration system needs to be evacuated, for example, with a vacuum degree ≤50Pa, and left to 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.

[0047] Calibration condition settings: Conduct experiments under the rated operating conditions of the refrigeration system. The rated operating conditions of the refrigeration system can be the ambient temperature T. a =35℃, evaporator load Q=100%, compressor frequency f = rated frequency.

[0048] 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 first temperature information at the inlet of the throttle valve for each experimental group was recorded. First pressure information Refrigerant dryness information Based on the actual refrigerant stock mass, calculate the corrected subcooling at the throttle valve inlet for each experimental group. .

[0049] 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 corrected subcooling at the expansion valve inlet is recorded every 5% of the designed refrigerant quantity. Record the corresponding refrigerant inventory. (Unit: kg)

[0050] Thirdly, the mass of the refrigerant stock based on the calibration experiment and the corrected subcooling at the corresponding throttle valve inlet. The least squares method was used to fit the model, and the modified subcooling and refrigerant inventory relationship model at the throttle valve inlet was obtained.

[0051] Specifically, Figure 4 This is a fitting curve of the refrigerant inventory and the corrected subcooling at the corresponding throttle valve inlet, 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 throttle valve inlet when the refrigerant charge is 8.5 kg. Blue indicates all calibration test data points. The black curve is a quadratic fitting curve of the corrected subcooling at the throttle valve inlet and the refrigerant charge corresponding to the calibration test data points.

[0052] 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. The least squares method was used to fit a quadratic correlation model of "corrected subcooling at the throttle valve inlet - refrigerant quantity," ensuring that the relative error of the correlation model was ≤5%, resulting in high accuracy in estimating the refrigerant quantity.

[0053] Optionally, based on the above embodiments, the modified subcooling degree at the throttle valve inlet and the refrigerant inventory correlation model is calculated using the following formula: .

[0054] 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 (unit: °C) at the actual throttle valve inlet. 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.

[0055] Optionally, based on the above embodiments, in step three above, the subcooling degree after correction based on the mass of the refrigerant stock from the calibration experiment and the corresponding throttle valve inlet... After obtaining the corrected correlation model between subcooling and refrigerant inventory at the throttle valve inlet using the least squares fitting method, the model also includes: Step 1: Select the corrected supercooling values ​​corresponding to at least two experimental groups that did not participate in the fitting. Substituting the corrected subcooling degree and refrigerant inventory correlation model at the throttle valve inlet, the estimated refrigerant inventory value is calculated. .

[0056] Step 2: Estimate the refrigerant inventory. The actual refrigerant charge corresponding to the at least two experimental groups that did not participate in the fitting. contrast.

[0057] Step 3, in relative error If the error is less than or equal to a preset error threshold, the correlation model between the corrected subcooling at the throttle valve inlet and the refrigerant inventory is deemed acceptable. For example, the preset error threshold can be 5%.

[0058] Step 4: In relative error >Under the preset error threshold, recalibrate and fit the corrected subcooling and refrigerant inventory correlation model at the throttle valve inlet.

[0059] The method for estimating the refrigerant inventory in a refrigeration system provided in this embodiment uses refrigerant dryness information. By calculating the flash gas correction coefficient, the interference of flash gas caused by pipeline pressure drop and environmental heat absorption on the subcooling measurement is eliminated, and the correlation between the corrected subcooling and refrigerant inventory is significantly enhanced. By focusing on the corrected subcooling at the throttle valve inlet, a key parameter strongly coupled with refrigerant inventory, and by acquiring data through high-precision sensors and fitting a quadratic correlation model using the least squares method, the relative estimation error is controlled within 5%, which is far superior to the error level of more than 15% in related technologies for estimating refrigerant inventory. The refrigerant inventory estimation method for refrigeration systems provided in this embodiment provides accurate data support for the operation and maintenance of refrigeration systems.

[0060] 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: S301. Obtain the first temperature information of the refrigerant at the inlet of the throttle valve. First pressure information and the refrigerant dryness information at the inlet of the throttle valve .

[0061] S302, Based on the first pressure information at the throttle valve inlet... and the first temperature information of the refrigerant at the inlet of the throttle valve Determine the subcooling degree at the inlet of the throttle valve. .

[0062] S303, Based on the refrigerant dryness information at the inlet of the throttle valve. Calculate the correction factor for flash gas. .

[0063] S304, Based on the flash gas correction coefficient Correcting the subcooling at the inlet of the throttle valve The corrected subcooling at the throttle valve inlet is obtained. .

[0064] S305. Based on the calibration experiment, determine the correlation model between the corrected subcooling degree and the refrigerant inventory at the throttle valve inlet of the refrigeration system.

[0065] S306. Based on the corrected subcooling at the inlet of the throttle valve. Based on the modified subcooling correlation model of the throttle valve inlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated.

[0066] S307. Obtain the current operating conditions of the refrigeration system.

[0067] Specifically, the current operating conditions of the refrigeration system include the current ambient temperature, current evaporator load, and current compressor frequency.

[0068] S308. Based on the difference between the current operating condition and the calibration operating condition, the correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory is corrected, and the correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory after the operating condition correction is determined.

[0069] Specifically, the calibration condition refers to the ambient temperature T under the rated operating conditions of the refrigeration system. arated =35℃, evaporator load Q rated =100%, compressor frequency f rated =Rated frequency.

[0070] Based on the differences between the current operating conditions and the calibration conditions, the correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory is modified. The modified correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory is determined to ensure that the modified correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory is applicable to the accuracy requirements of refrigerant inventory estimation under different operating conditions.

[0071] S309. Based on the correlation model between the corrected subcooling degree at the throttle valve inlet and the refrigerant inventory after the operating condition correction, estimate the refrigerant inventory according to the corrected subcooling degree at the throttle valve inlet.

[0072] Specifically, the model relating the corrected subcooling at the throttle valve inlet to the refrigerant inventory under the corrected throttle valve inlet input condition improves the accuracy of refrigerant inventory estimation under different operating conditions.

[0073] Optionally, based on the above embodiments, step S308, which involves correcting the correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory according to the difference between the current operating condition and the calibration condition, and determining the correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory after condition correction, may include: First, obtain the ambient temperature T under the current operating conditions. a Evaporator load Q and compressor frequency f.

[0074] Secondly, based on the ambient temperature under the current operating conditions. Ambient temperature under calibration conditions The difference between them, the evaporator load under the current operating conditions Evaporator load under rated operating conditions The difference between them, the compressor frequency under the current operating conditions Compressor frequency under rated operating conditions The difference between the values ​​is used to correct the correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory, resulting in the corrected correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory after operating condition correction.

[0075] Specifically, when there is a deviation between the actual operating conditions and the calibration conditions, the correlation model between the subcooling and refrigerant inventory at the throttle valve inlet 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 -0.3 to 0.3.

[0076] Optionally, based on the above embodiments, the modified subcooling degree at the throttle valve inlet and the refrigerant inventory correlation model adopts the following formula: .

[0077] Where, m est '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. , , These are the operating condition correction factors. These factors can be obtained through multi-operating condition calibration and fitting.

[0078] Optionally, based on the above embodiments, after estimating the refrigerant inventory of the refrigeration system according to the corrected subcooling at the throttle valve inlet and a refrigerant inventory correlation model, the system may further include: Step 1: Trigger a refrigerant shortage warning based on the difference between the refrigerant inventory and the first preset inventory threshold.

[0079] 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.

[0080] 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.

[0081] One alternative implementation, exemplary, is illustrated below using a refrigeration system for a 10HP split-type environmental test facility employing R410A refrigerant (design refrigerant capacity m). design Taking (e.g., 8.5kg) as an example, the specific implementation process of the present invention will be described in detail: This embodiment provides a specific implementation method for a system calibration experiment as follows: Experimental Preparation: The refrigeration system of the environmental testing equipment was installed in the enthalpy difference laboratory, allowing for precise control of ambient temperature and evaporator load. The refrigeration system was evacuated to a vacuum level ≤50Pa and allowed to stand for 2 hours. Sensor Installation: A capacitor + infrared dual-algorithm refrigerant dryness detection device 11 was installed, with a detection accuracy of ±0.03. Temperature Sensor: Pt100 three-wire system, with an accuracy of ±0.2℃. Pressure Sensor: Piezoelectric type, with an accuracy of ±0.13% FS.

[0082] Calibration conditions: enthalpy difference, laboratory condenser side ambient temperature Evaporator load on the evaporator side That is, the design cooling capacity; compressor frequency. That is, the rated frequency, and the dryness influence coefficient k=1.0.

[0083] Data Acquisition: R410A refrigerant was charged into the refrigeration system at a rate of 6.0 kg (70.6%). Begin with 0.4 kg (approximately 4.7%) at intervals. Record the data once, until it reaches 11.0 kg (129.4%). A total of 13 data points were collected, and some of the data is shown in Table 1 below: Model Fitting: The least squares method was used to fit the above 13 data points to obtain the correlation model of "corrected subcooling at the throttle valve inlet - refrigerant inventory". .

[0084] Model validation: Combining Figure 3 Select refrigerant inventory =8.0kg (x=0.03, =7.32℃), 9.0kg (x=0.02, =9.05℃), 10.0kg (x=0.01, The corrected subcooling at the throttle valve inlet at three points (=10.23℃) is substituted into the correlation model of "corrected subcooling at the throttle valve inlet - refrigerant inventory" to calculate... The values ​​were 7.98 kg, 8.95 kg, and 9.87 kg, respectively, with relative errors of ≤0.5%, indicating that the correlation model of "corrected subcooling at the throttle valve inlet - refrigerant inventory" is qualified.

[0085] Table 1 shows the relationship between the parameter information of the refrigeration system and the actual refrigerant inventory. 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 ( ).

[0086] This embodiment provides a specific implementation method for real-time refrigerant inventory estimation as follows: 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 throttle valve inlet. =2602kPa, first temperature information at the throttle valve inlet. =41.0℃, the refrigerant dryness information x=0.05 at the inlet of the throttle valve was measured by the dryness detection device.

[0087] Calculate the actual subcooling at the inlet of the actual throttle valve. : Depend on =2602 kPa. Referring to the thermodynamic property table of R410A, we get... =43.7℃; =43.7-41.0=2.7℃.

[0088] Calculate the correction factor for flash gas : .

[0089] Calculate the corrected undercooling : .

[0090] Refrigerant inventory estimation: Will Substituting "corrected subcooling at the throttle valve inlet - refrigerant inventory" into the correlation model: .

[0091] Operating condition correction: ≈5.38kg.

[0092] Early warning output: This triggers a "severe refrigerant shortage" warning, prompting maintenance personnel to replenish the refrigerant.

[0093] The refrigerant inventory estimation method for the refrigeration system provided in this embodiment uses a capacitor + infrared dual-algorithm refrigerant dryness detection device 11 installed at the inlet of the throttle valve to acquire refrigerant dryness information at the inlet of the throttle valve in real time. Accurately captures the content of flashing gases. Based on refrigerant dryness information. Determine the correction factor for flash gas. and through The effective subcooling is calculated to eliminate interference from flash gas in the subcooling detection. High-vacuum treatment and settling are performed before calibration to ensure data accuracy. A quadratic correlation model of "subcooling after throttling valve correction - refrigerant inventory" is obtained with a relative error ≤5%. Furthermore, the refrigerant inventory estimation method for the refrigeration system provided in this embodiment, combined with operating condition correction coefficients, is adapted to different operating conditions, improving the estimation accuracy of refrigerant inventory in complex environments. The refrigerant inventory estimation method for the refrigeration system provided in this embodiment is adaptable to various refrigerant types and multi-temperature zone systems. Personalized matching of model coefficients is achieved through targeted calibration, resulting in strong versatility.

[0094] Without interrupting the operation of the refrigeration system, it can estimate the refrigerant inventory 1 to 5 times per second by collecting parameters such as temperature and pressure information in real time, meeting 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.

[0095] 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.

[0096] 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 refrigerant dryness detection device 11 and 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 installation and maintenance are simple, the investment cost is low, and it is easy to promote and apply in engineering projects.

[0097] In addition to the core function of estimating refrigerant inventory, the refrigerant inventory estimation method for the refrigeration system provided in this embodiment can extend to automatic early warning based on the estimation results, and intelligent refrigerant replenishment control for refrigerant shortage and / or refrigerant excess. At the same time, it provides data basis for refrigeration system COP (coefficient of performance) optimization, compressor overheat protection, etc., effectively improving the overall intelligent operation level and reliability of the refrigeration system.

[0098] 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: The acquisition module is used to acquire the first temperature information of the refrigerant at the inlet of the throttle valve. First pressure information and the refrigerant dryness information at the inlet of the throttle valve ; The subcooling calculation module is used to calculate the subcooling based on the first pressure information at the inlet of the throttle valve. and the first temperature information of the refrigerant at the inlet of the throttle valve Determine the subcooling degree at the inlet of the throttle valve. ; The flash gas coefficient determination module is used to determine the refrigerant dryness information at the inlet of the throttle valve. Calculate the correction factor for flash gas. ; The supercooling correction module is used to adjust the supercooling based on the flash gas correction coefficient. Correcting the subcooling at the inlet of the throttle valve The corrected subcooling at the throttle valve inlet is obtained. ; The estimation module is used to estimate the corrected subcooling at the inlet of the throttle valve. Based on the modified subcooling correlation model of the throttle valve inlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated.

[0099] The refrigerant inventory estimation device for a refrigeration system provided in this embodiment addresses the problems of existing refrigerant inventory estimation devices, such as complex operation, weak anti-interference ability, and low accuracy. This embodiment's refrigerant inventory estimation device acquires the first temperature information of the refrigerant at the throttle valve inlet through an acquisition module. First pressure information and the refrigerant dryness information at the inlet of the throttle valve ; and by using the first pressure information at the inlet of the throttle valve and the first temperature information of the refrigerant at the inlet of the throttle valve Determine the subcooling degree at the inlet of the throttle valve. Then, the flash gas coefficient determination module determines the refrigerant dryness information at the throttle valve inlet. Calculate the correction factor for flash gas. And the supercooling correction module adjusts the correction based on the flash gas correction coefficient. Correcting the subcooling at the inlet of the throttle valve The corrected subcooling at the throttle valve inlet is obtained. Finally, the estimation module calculates the subcooling based on the correction at the throttle valve inlet. Based on the modified subcooling correlation model between the throttle valve inlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated. The refrigerant inventory estimation device for the refrigeration system provided in this embodiment achieves real-time and accurate estimation of the refrigerant inventory, and also has the advantages of simple operation, strong versatility, and strong anti-interference ability.

[0100] 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, a throttle valve 3, an evaporator 4, a first temperature sensor 811, a first pressure sensor 812, and a refrigerant dryness detection device 11. The compressor 1 is connected to the condenser 2, the condenser 2 is connected to the throttle valve 3, the throttle valve 3 is connected to the evaporator 4, and the evaporator 4 is connected to the compressor 1. The first pressure sensor 812, the first temperature sensor 811, and the refrigerant dryness detection device 11 are located at the inlet of the throttle valve. The second temperature sensor 821 is located at the inlet of the throttle valve 3. The first temperature sensor 811, the first pressure sensor 812, and the refrigerant dryness detection device 11 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.

[0101] 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 of the refrigeration system, 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 the control unit 40 is used to acquire the first temperature information of the refrigerant at the inlet of the throttle valve collected by the sensor 8. First pressure information and the refrigerant dryness information at the inlet of the throttle valve The data storage unit 30 is connected to the control unit 40. The data storage unit 30 is used to store the first temperature information and the first pressure information of the refrigerant at the throttle valve inlet, as well as the refrigerant dryness information at the throttle valve inlet. The system displays data such as the second pressure information at the throttle valve inlet, the second temperature information of the refrigerant at the throttle valve inlet, and the corrected subcooling degree and refrigerant inventory correlation model at the throttle valve inlet of the refrigeration system. The display unit 50 is connected to the control unit and displays the first temperature and first pressure information of the refrigerant at the throttle valve inlet, and the refrigerant dryness information at the throttle valve inlet. The system includes information such as the second pressure at the throttle valve inlet, the second temperature of the refrigerant at the throttle valve inlet, refrigerant inventory estimation results, and early warning information. Early warning information may include information such as insufficient or excessive refrigerant.

[0102] 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.

[0103] 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 inlet of the throttle valve. First pressure information () ) and the refrigerant dryness information at the inlet of the throttle valve ( ); Based on the first pressure information at the inlet of the throttle valve ( ) and the first temperature information of the refrigerant at the inlet of the throttle valve ( ), determine the subcooling degree at the inlet of the throttle valve ( ); Based on the refrigerant dryness information at the inlet of the throttle valve ( ), calculate the flash gas correction factor ( ); According to the flash gas correction factor ( Correcting the subcooling at the inlet of the throttle valve ( ), to obtain the corrected subcooling at the throttle valve inlet ( ); Based on the corrected subcooling at the inlet of the throttle valve ( Based on the modified subcooling correlation model of the throttle valve inlet 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 pressure information at the inlet of the throttle valve ( ) and the first temperature information of the refrigerant at the inlet of the throttle valve ( ), determine the subcooling degree at the inlet of the throttle valve ( ),include: Based on the first pressure information at the inlet of the throttle valve ( ), determine the first pressure information at the inlet of the throttle valve ( The saturation temperature of the refrigerant corresponding to () ); Based on the first temperature information of the refrigerant at the inlet of the throttle valve ( ) and the saturation temperature ( The difference between the values ​​of ) determines the subcooling at the inlet of the throttle valve. ).

3. The method according to claim 1 or 2, characterized in that, The information based on the refrigerant dryness at the inlet of the throttle valve ( ), calculate the flash gas correction factor ( ),include: Based on the refrigerant dryness information at the inlet of the throttle valve ( The product of the product of the dryness factor and the dryness factor is used to determine the flash gas correction factor. ).

4. The method according to claim 3, characterized in that, The correction factor based on the flash gas ( Correcting the subcooling at the inlet of the throttle valve ( ), to obtain the corrected subcooling at the throttle valve inlet ( ),include: According to the flash gas correction factor ( ) and the subcooling at the inlet of the throttle valve ( The product of ) determines the corrected subcooling at the throttle valve inlet. ).

5. The method according to claim 1 or 2, characterized in that, The subcooling after correction according to the inlet of the throttle valve ( Before estimating the refrigerant inventory of the refrigeration system based on the modified subcooling-refrigerant inventory correlation model at the throttle valve inlet, the following steps are also included: Based on calibration experiments, a modified subcooling correlation model between the throttle valve inlet of the refrigeration system and the refrigerant inventory was determined.

6. The method according to claim 5, characterized in that, The modified subcooling correlation model between the refrigeration system's expansion valve inlet and refrigerant inventory, determined based on calibration experiments, includes: Set calibration conditions, which include ambient temperature, evaporator load, and compressor frequency; Different masses of refrigerant were charged into the refrigeration system, starting from 70% of the designed refrigerant quantity, increasing in increments of 5% of the designed refrigerant quantity, and ending at 130% of the designed refrigerant quantity. Calibration experiments were conducted, and the first temperature information at the inlet of the throttle valve for each experimental group was recorded. First pressure information () Refrigerant dryness information () ) and the corresponding actual refrigerant mass, calculate the corrected subcooling at the inlet of the throttle valve for each experimental group ( ) ); Based on the mass of the refrigerant stock from the calibration experiment and the corrected subcooling at the corresponding throttle valve inlet ( The least squares method was used to fit the data to obtain the modified subcooling and refrigerant inventory correlation model at the throttle valve inlet.

7. The method according to claim 6, characterized in that, The mass of the refrigerant stock based on the calibration experiment and the corresponding subcooling after correction at the throttle valve inlet ( After obtaining the corrected correlation model between subcooling and refrigerant inventory at the throttle valve inlet using the least squares fitting method, the model also includes: Select the corrected supercooling corresponding to at least two experimental groups that did not participate in the fitting. Substituting the corrected subcooling and refrigerant inventory correlation model at the throttle valve inlet, the estimated refrigerant inventory is calculated. ); The estimated refrigerant inventory ( The actual refrigerant charge corresponding to the at least two experimental groups that did not participate in the fitting () )contrast; In relative error If the error threshold is less than or equal to the preset error threshold, the correlation model between the corrected subcooling at the throttle valve inlet and the refrigerant inventory is deemed to be qualified. In relative error >Under the preset error threshold, recalibrate and fit the corrected subcooling and refrigerant inventory correlation model at the throttle valve inlet.

8. 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 throttle valve inlet 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 condition and the calibration operating condition, the correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory is corrected, and the correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory after the operating condition correction is determined. Based on the correlation model between the corrected subcooling at the throttle valve inlet and the refrigerant inventory after the operating condition correction, the refrigerant inventory is estimated according to the corrected subcooling at the throttle valve inlet.

9. The method according to claim 8, characterized in that, The step of correcting the correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory based on the difference between the current operating condition and the calibration operating condition, and determining the corrected correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory after the operating condition correction, includes: Obtain the ambient temperature under current operating conditions ( ), Evaporator load ( ) and compressor frequency ( ); Based on the ambient temperature under current operating conditions ( ) and ambient temperature under the rated operating conditions ( The difference between ) and the evaporator load under the current operating conditions ( ) and evaporator load under rated operating conditions ( The difference between ) and the compressor frequency under the current operating conditions ( ) and compressor frequency under rated operating conditions ( The difference between the values ​​is used to correct the correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory, resulting in the corrected correlation model between the subcooling at the throttle valve inlet and the refrigerant inventory after operating condition correction.

10. The method according to any one of claims 1, 2, 4, 6, 7, and 9, characterized in that, After estimating the refrigerant inventory of the refrigeration system based on the corrected subcooling at the throttle valve inlet 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.

11. 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 inlet of the throttle valve. First pressure information () ) and the refrigerant dryness information at the inlet of the throttle valve ( ); The subcooling calculation module is used to calculate the subcooling based on the first pressure information at the inlet of the throttle valve ( ) and the first temperature information of the refrigerant at the inlet of the throttle valve ( ), determine the subcooling degree at the inlet of the throttle valve ( ); The flash gas coefficient determination module is used to determine the refrigerant dryness information at the inlet of the throttle valve ( ), calculate the flash gas correction factor ( ); The supercooling correction module is used to adjust the flash gas correction coefficient according to the supercooling correction coefficient. Correcting the subcooling at the inlet of the throttle valve ( ), to obtain the corrected subcooling at the throttle valve inlet ( ); The estimation module is used to estimate the corrected subcooling at the inlet of the throttle valve ( Based on the modified subcooling correlation model of the throttle valve inlet and the refrigerant inventory, the refrigerant inventory of the refrigeration system is estimated.

12. A refrigeration system, characterized in that, include: The refrigerant inventory estimation device of the refrigeration system according to claim 11, as well as the compressor, condenser, expansion valve, evaporator, first temperature sensor, first pressure sensor and refrigerant dryness detection device; The compressor is connected to the condenser, the condenser is connected to the throttle valve, the throttle valve is connected to the evaporator, and the evaporator is connected to the compressor; the first pressure sensor, the first temperature sensor, and the refrigerant dryness detection device are located at the inlet of the throttle valve; the first temperature sensor, the first pressure sensor, and the refrigerant dryness detection device are respectively connected to the refrigerant inventory estimation device of the refrigeration system.

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