Method for measuring refrigerant inventory of a refrigeration device

Abstract

The present application relates to the field of refrigeration equipment, and provides a method for measuring refrigerant storage of refrigeration equipment on site. The method for measuring refrigerant storage of refrigeration equipment on site comprises the following steps: recovering refrigerant for the first time, recovering refrigerant for the second time, obtaining the internal volume of the refrigeration equipment to be measured, obtaining the mass of the remaining refrigerant in the refrigeration equipment to be measured, and obtaining the refrigerant storage in the refrigeration equipment to be measured. The method for measuring refrigerant storage on site realizes accurate measurement of the refrigerant storage of the refrigeration equipment without complete extraction through the design of twice segmented recovery, eliminates the inefficiency of the ordinary complete extraction measurement method in the low-pressure extraction stage, avoids the measurement error caused by the failure to achieve absolute vacuum, and more importantly, ensures that the refrigerant pressure in the refrigeration equipment is always higher than the atmospheric pressure during the measurement process, avoids the possibility of external air and water vapor entering the refrigeration equipment to be measured, and thus effectively prevents system corrosion, performance decline caused by non-condensable gas accumulation, and the combustion risk of flammable refrigerant systems.

Description

Technical Field

[0001] This invention relates to the field of refrigeration equipment and provides a method for on-site measurement of refrigerant levels in refrigeration equipment. Background Technology

[0002] The statements herein are provided only as background information in connection with this application and do not necessarily constitute prior art.

[0003] Refrigerant leakage is a common problem in refrigeration and air conditioning equipment during long-term operation. Refrigerant leakage not only directly causes non-CO2 greenhouse gas emissions, but more importantly, it causes the equipment to deviate from its design specifications, leading to decreased energy efficiency. Therefore, quickly and accurately detecting the refrigerant level in on-site refrigeration equipment is crucial for identifying refrigerant leaks, timely detection, reducing greenhouse gas emissions, and improving the operational performance of refrigeration equipment. Furthermore, accurate refrigerant level testing provides a reliable basis for subsequent refrigerant replenishment, avoiding the serious emission risks associated with completely draining and then fully refilling the system when the refrigerant level cannot be accurately determined in real-world scenarios.

[0004] Currently, refrigeration and air conditioning repair personnel commonly use outlet air temperature and system pressure to determine whether refrigerant is leaking. This can only assess whether a significant leak has occurred, but it cannot quantify the extent of the leak. Theoretically, the remaining refrigerant can be recovered by vacuuming the system and then weighing it. However, this method has three significant drawbacks: 1) As the system pressure decreases, the refrigerant recovery rate slows down. To recover as much refrigerant as possible, the system often needs to be evacuated to an extremely high vacuum, significantly prolonging the refrigerant recovery time and drastically reducing on-site availability; 2) Absolute vacuum is impossible in equipment, so some refrigerant will always remain unrecovered, leading to inaccurate measurements; 3) For equipment with existing leaks, vacuuming will introduce ambient air and water vapor into the system, potentially causing corrosion and performance degradation due to the accumulation of non-condensable gases. More seriously, for systems containing flammable refrigerants, this significantly increases the risk of ignition and explosion. Summary of the Invention

[0005] This invention provides a method for on-site measurement of refrigerant levels in refrigeration equipment, which addresses the shortcomings of related technologies, such as low efficiency, poor accuracy, and significant safety hazards in refrigerant level detection.

[0006] This invention provides a method for on-site measurement of refrigerant levels in refrigeration equipment, comprising: First refrigerant recovery: Extract refrigerant from the refrigeration equipment under test into the refrigerant recovery tank. After stopping extraction and waiting for the system pressure to stabilize, obtain the first weight m1 of the refrigerant recovery tank, the first refrigerant pressure P1 of the refrigeration equipment under test, and the first refrigerant temperature T1. Refrigerant recovery: Extract refrigerant from the refrigeration equipment under test into the refrigerant recovery tank. After stopping extraction and waiting for the system pressure to stabilize, obtain the second weight m2 of the refrigerant recovery tank, the second refrigerant pressure P2 of the refrigeration equipment under test, and the second refrigerant temperature T2. To obtain the internal volume V of the refrigeration device under test: the internal volume V of the refrigeration device under test is calculated based on the first weight m1, the second weight m2, the first pressure P1 of the refrigerant, the second pressure P2 of the refrigerant, the first temperature T1 of the refrigerant, and the second temperature T2 of the refrigerant. Obtain the remaining refrigerant mass in the refrigeration equipment under test: Calculate the remaining refrigerant mass M1 in the refrigeration equipment under test after recycling, based on the internal volume V, the second pressure P2 of the refrigerant, and the second temperature T2 of the refrigerant. To obtain the initial refrigerant quantity in the refrigeration equipment under test: Based on the total mass of the extracted and recovered refrigerant and the remaining refrigerant mass M1, the initial refrigerant quantity M2 in the refrigeration equipment under test is calculated.

[0007] According to one embodiment of the present invention, the formula for calculating the content product V is: V=(m2-m1)×Rg×T1×T2 / (P1×T2-P2×T1); In the formula, Rg is the specific gas constant of the refrigerant gas charged in the refrigeration equipment under test.

[0008] According to one embodiment of the present invention, a vacuuming step is further included before the initial refrigerant recovery step: Without connecting to the refrigeration equipment under test, the measuring pipeline and device outside the refrigeration equipment under test are evacuated. When the pipeline pressure reaches the set pressure, the evacuation is stopped and the initial weight m3 of the refrigerant recovery tank is obtained.

[0009] According to one embodiment of the present invention, the total mass of the extracted and recovered refrigerant is m2-m3, and the initial stock M2 is calculated using the following formula: M2 = M1 + (m2 - m3).

[0010] According to one embodiment of the present invention, in the first refrigerant recovery step, P1 satisfies a pressure higher than the ambient atmospheric pressure and lower than the saturation pressure of the refrigerant corresponding to the lowest ambient temperature of the refrigeration equipment under test. In the step of refrigerant recovery, P2 is higher than ambient atmospheric pressure and lower than P1.

[0011] According to one embodiment of the present invention, the on-site measurement method for refrigerant inventory in refrigeration equipment is applicable to refrigeration equipment using flammable refrigerants.

[0012] According to an embodiment of the present invention, the on-site measurement method of refrigerant inventory in refrigeration equipment is based on an on-site measurement device for refrigerant inventory in refrigeration equipment. The on-site measurement device for refrigerant inventory in refrigeration equipment includes a refrigerant recovery device, a refrigerant recovery tank, a vacuum pump, a weighing balance, a shut-off valve, a pressure sensor, and a temperature sensor. The shut-off valve is installed at the refrigerant charging valve of the refrigeration equipment under test and connected to the inlet of the refrigerant recovery device; The outlet of the refrigerant recovery device is connected to the inlet of the refrigerant recovery tank; The outlet of the refrigerant recovery tank is connected to the vacuum pump; the weighing balance is located below the refrigerant recovery tank.

[0013] According to one embodiment of the present invention, the refrigerant recovery device includes a refrigerant transfer assembly for conveying refrigerant from the inlet of the refrigerant recovery device to its outlet.

[0014] According to an embodiment of the present invention, the refrigerant recovery device is configured with a first working mode. In the first working mode, the inlet, outlet and internal components of the refrigerant recovery device are all in a fully connected state, which is used to transport air in the pipeline from the inlet to the outlet and extract it by turning on the vacuum pump, so as to ensure that the inside of the refrigerant recovery device and the pipeline connected to its inlet and outlet are all in a vacuum state.

[0015] According to one embodiment of the present invention, the refrigerant recovery device is configured with a second operating mode. In the steps of the first refrigerant recovery and the second refrigerant recovery, the device switches to the second operating mode to send the refrigerant in the refrigeration equipment under test to the refrigerant recovery tank through the connecting pipeline and the refrigerant recovery device. It is also used to completely transport the residual refrigerant in the connecting pipeline and the internal flow path of the refrigerant recovery device to the refrigerant recovery tank.

[0016] The on-site measurement method for refrigerant inventory in refrigeration equipment provided by the present invention achieves accurate measurement of refrigerant inventory without complete extraction by means of two-stage recovery. This eliminates the inefficiency of ordinary complete extraction measurement methods in the low-pressure extraction stage and avoids measurement errors caused by the inability to achieve absolute vacuum. More importantly, it ensures that the refrigerant pressure inside the refrigeration equipment is always higher than atmospheric pressure during the measurement process, preventing the possibility of outside air and water vapor entering the refrigeration equipment under test. This effectively prevents system corrosion, performance degradation due to the accumulation of non-condensable gases, and the risk of combustion of flammable refrigerant systems. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of the on-site measurement method for refrigerant inventory in refrigeration equipment provided by the present invention.

[0019] Figure 2 This is a schematic structural diagram of the on-site measurement device for refrigerant inventory in refrigeration equipment provided by the present invention.

[0020] Figure 3 This is a schematic diagram of the first mode operation of the on-site measurement device for refrigerant inventory in refrigeration equipment provided by the present invention.

[0021] Figure 4 This is a schematic diagram illustrating the second mode operation of the on-site measurement device for refrigerant inventory in refrigeration equipment provided by the present invention, in which the refrigerant is recovered to the refrigerant recovery tank via the compressor and condenser.

[0022] Figure 5 This is a schematic diagram illustrating the principle of the on-site measurement device for refrigerant inventory in refrigeration equipment provided by the present invention, which recovers residual refrigerant in the internal flow path to the refrigerant recovery tank via a compressor during the second mode operation.

[0023] Figure label: 100. Refrigerant recovery tank; 102. Refrigerant recovery device; 104. Vacuum pump; 106. Weighing balance; 108. Shut-off valve; 110. Pressure sensor; 112. Temperature sensor. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0025] The specific terms used in this specification are for illustrative purposes only and are not intended to limit the illustrated embodiments. For example, expressions such as "same" and "identical" not only indicate a strictly identical state, but also indicate a state with tolerances or differences in the degree of functionality. For example, expressions indicating relative or absolute arrangement such as "in a certain direction," "along a certain direction," "side by side," "perpendicular," "centered on," "concentric," or "coaxial" not only strictly indicate such an arrangement, but also indicate a state of relative displacement by tolerances or angles or distances with the same degree of functionality.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] Furthermore, features specified as "first" or "second" may explicitly or implicitly include one or more of those features. In the description of this invention, unless otherwise stated, "multiple" means two or more. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified. In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, B1 and / or B2 can represent: B1 existing alone, B1 and B2 existing simultaneously, and B2 existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] like Figures 1 to 5 As shown, this embodiment of the invention provides a method for on-site measurement of refrigerant levels in refrigeration equipment, including: First refrigerant recovery: Extract refrigerant from the refrigeration equipment under test into the refrigerant recovery tank 100. After stopping the extraction and waiting for the system pressure to stabilize, obtain the first weight m1 of the refrigerant recovery tank 100, the first refrigerant pressure P1 of the refrigeration equipment under test, and the first refrigerant temperature T1. Refrigerant recovery: Extract refrigerant from the refrigeration equipment under test into the refrigerant recovery tank 100. After stopping extraction and waiting for the system pressure to stabilize, obtain the second weight m2 of the refrigerant recovery tank 100, the second refrigerant pressure P2 of the refrigeration equipment under test, and the second refrigerant temperature T2. To obtain the internal volume V of the refrigeration device under test: the internal volume V of the refrigeration device under test is calculated based on the first weight m1, the second weight m2, the first pressure P1 of the refrigerant, the second pressure P2 of the refrigerant, the first temperature T1 of the refrigerant, and the second temperature T2 of the refrigerant. Obtain the remaining refrigerant mass in the refrigeration equipment under test: Calculate the remaining refrigerant mass M1 in the refrigeration equipment under test after recycling, based on the internal volume V, the second pressure P2 of the refrigerant, and the second temperature T2 of the refrigerant. To obtain the initial refrigerant quantity in the refrigeration equipment under test: Based on the total mass of the extracted and recovered refrigerant and the remaining refrigerant mass M1, the initial refrigerant quantity M2 in the refrigeration equipment under test is calculated.

[0030] The on-site measurement method for refrigerant inventory in refrigeration equipment provided by the present invention achieves accurate measurement of refrigerant inventory without complete extraction by means of two-stage recovery. This eliminates the inefficiency of ordinary complete extraction measurement methods in the low-pressure extraction stage and avoids measurement errors caused by the inability to achieve absolute vacuum. More importantly, it ensures that the refrigerant pressure inside the refrigeration equipment is always higher than atmospheric pressure during the measurement process, preventing the possibility of outside air and water vapor entering the refrigeration equipment under test. This effectively prevents system corrosion, performance degradation due to the accumulation of non-condensable gases, and the risk of combustion of flammable refrigerant systems.

[0031] Please continue reading Figures 1 to 5 The on-site measurement method for refrigerant inventory in refrigeration equipment provided in this embodiment of the invention relies on refrigerant recovery weighing equipment, pressure acquisition devices, and temperature acquisition devices to complete the entire process.

[0032] The first step is to perform the initial recovery operation. Connect the pipeline to the refrigeration equipment under test and the refrigerant recovery tank 100. Start the recovery mechanism to extract the refrigerant inside the refrigeration equipment. Continue to extract until the preset termination condition is met, then turn off the recovery mechanism. Keep the pipeline connected and let it stand for a sufficient time to wait for the gaseous refrigerant pressure inside the refrigeration equipment to be completely stable. Simultaneously collect three sets of basic data: the current total weight of the refrigeration recovery tank, the internal pressure of the refrigeration equipment, and the first temperature of the refrigerant. Record the collected data as the first set of parameters m1, P1, and T1.

[0033] The second step is to perform a second recycling operation without altering the pipeline connections. The recycling mechanism is restarted to continue extracting refrigerant. Once the conditions for terminating the second recycling are met, the equipment is shut down and allowed to stand until the internal pressure stabilizes. The weight of the updated refrigeration unit recycling tank, the internal pressure of the refrigeration equipment, and the second temperature of the refrigerant are collected and recorded as the second set of parameters m2, P2, and T2.

[0034] The third step involves substituting the two sets of weight differences, two sets of pressure differences, and a uniform ambient temperature into the corresponding volume calculation formula to solve for the overall effective internal volume V of the refrigeration equipment under test. This volume refers to the entire sealed space that can be filled with refrigerant gas.

[0035] The fourth step is to substitute the product V, the equipment pressure P2 after secondary recovery, the first temperature T1 of the refrigerant, and the second temperature T2 of the refrigerant obtained from the solution into the corresponding calculation relationship of the ideal gas to calculate the mass M1 of the refrigerant remaining inside the refrigeration equipment after the secondary recovery.

[0036] The fifth step is to first calculate the total mass of all recovered refrigerant corresponding to the difference between the two weighings, and then add the total recovered mass to the mass of the remaining gaseous refrigerant in the equipment. The sum is the original complete refrigerant stock M2 of the equipment.

[0037] The entire process does not require purging all the refrigerant inside the refrigeration equipment. The complete inventory calculation can be completed by extracting the refrigerant in two stages. The timing of each acquisition step is fixed, the parameter calculation logic is unified, and the entire measurement process can be completely reproduced by relying on conventional weighing, pressure and temperature measuring equipment.

[0038] According to one embodiment of the present invention, the formula for calculating the content product V is: V=(m2-m1)×Rg×T1×T2 / (P1×T2-P2×T1); In the formula, Rg is the specific gas constant of the refrigerant gas charged in the refrigeration equipment under test.

[0039] In one embodiment of the present invention, each parameter in the formula corresponds to a standardized physical quantity collected in the measurement process. m2 and m1 are the weighing values ​​of the refrigeration recovery tank after two stabilization operations, and the difference between them represents the mass of refrigerant medium extracted between the two recovery operations. P1 and P2 are the gas phase pressures inside the refrigeration equipment after two static stabilization operations. T1 is the first temperature of the refrigerant and T2 is the second temperature of the refrigerant. Rg is the specific gas constant that is fixed for the corresponding refrigerant type. The physical properties of different types of refrigerants can be obtained from the refrigerant parameter library.

[0040] The formula derivation is based on the difference elimination process of the ideal gas law under two stable operating conditions, eliminating interference variables other than the unknown volume, and solving the volume only by relying on the weight, pressure and temperature parameters that can be measured on site.

[0041] When using it, you only need to substitute the four sets of measured values ​​collected on site with the pre-known refrigerant gas constant into the formula to complete the four arithmetic operations. No additional correction coefficients or segmented correction steps are required. The standardized calculation rules are uniformly compatible with various types of refrigeration equipment of the same category.

[0042] By using difference elimination to derive the volume calculation formula, the calculation error caused by lubricating oil dissolving refrigerant and equipment pipe wall adsorption medium during single operating condition calculation can be avoided. The two operating conditions cancel out fixed interference terms, and the volume calculation result is close to the actual gas phase space size of the equipment.

[0043] In addition, it should be noted that the on-site measurement method for refrigerant inventory in this refrigeration equipment is applicable to operating conditions where the refrigerant pressure in the system under test is positive.

[0044] According to one embodiment of the present invention, a vacuuming step is further included before the initial refrigerant recovery step: Without connecting to the refrigeration equipment under test, the measuring pipeline and device outside the refrigeration equipment under test are evacuated. When the pipeline pressure reaches the set pressure, the evacuation is stopped and the initial weight m3 of the refrigerant recovery tank 100 is obtained.

[0045] In one embodiment of the present invention, before the formal segmented recycling operation is started, the connection port between the recycling pipeline and the refrigeration equipment to be tested is disconnected, so that the entire set of external measuring pipelines and recycling equipment form an independent closed loop, and the vacuum pump 104 is started to remove the air inside the loop.

[0046] The internal pressure of the pipeline is continuously monitored. When the pressure drops to the preset vacuum threshold, the vacuum pump 104 is turned off to maintain the pipeline in a closed vacuum state. At the same time, the unloaded refrigerant recovery tank 100 is weighed and the initial weight m3 of the refrigerant recovery tank 100 is recorded.

[0047] The vacuuming operation is performed only on the external measurement circuit and does not involve evacuating the internal air of the refrigeration equipment under test. After the vacuuming is completed, the pipeline is kept sealed to prevent atmospheric air from entering the pipeline. The pipeline is then connected to the equipment under test for the first recovery process.

[0048] The initial weight m3 is used as the basis for calculating the weight of the medium. Subsequently, m2 and m3 are used to calculate the difference to obtain the total mass of refrigerant extracted from the equipment throughout the process, completely eliminating the weighing interference caused by the weight of the original medium and air inside the recovery tank and pipeline.

[0049] By independently evacuating the external pipeline before recycling, the interference of residual air in the pipeline and refrigerant left over from previous testing on the weight collection can be eliminated, making m3 a pure no-load reference weight. The subsequent weight difference only represents the medium extracted from the device under test this time, and the weighing calculation error is greatly reduced.

[0050] By only extracting external pipelines and not processing the inside of the equipment under test, the original medium distribution state of the equipment will not be changed. This avoids the distortion of the initial pressure acquisition and the original complete refrigerant inventory measurement value caused by prematurely removing the refrigerant from the equipment, and ensures the effectiveness of the comparison of the parameters of the two recovery conditions.

[0051] Meanwhile, by pre-recording the weight of the empty tank, unifying the medium calculation benchmark, and distinguishing the three weight components of the tank itself, pipeline residual medium, and the medium being recovered this time, the accuracy of calculating the total recovered medium is further improved, providing a reliable basic value for the overall inventory calculation.

[0052] According to one embodiment of the present invention, the total mass of refrigerant extracted and recovered is m2-m3, and the initial stock M2 is calculated using the following formula: M2 = M1 + (m2 - m3).

[0053] In one embodiment of the present invention, m3 is the initial weight of the empty recovery tank after the pipeline is evacuated, and m2 is the overall weight of the recovery tank after the secondary recovery is stabilized. The difference between the two is the total mass of refrigerant medium extracted from the refrigeration equipment under test after the self-detection is started.

[0054] M1 represents the mass of refrigerant remaining inside the equipment after the secondary recovery. The total recovered mass is added to the mass of the residual gas phase, and the sum is the initial mass of complete refrigerant, M2, when the refrigeration equipment under test leaves the factory.

[0055] The calculation logic combines and statistically analyzes all refrigerant forms, including both extracted media and unextracted gaseous media within the equipment, comprehensively covering all refrigerants inside the equipment. The entire calculation formula is built upon parameters collected throughout the entire process, including pre-vacuuming, two-stage recovery, volume back-calculation, and gas phase quality measurement. Every parameter comes from measurable physical quantities on-site, eliminating any human-predicted variables.

[0056] By distinguishing between the empty-load baseline weight and the secondary weighing and taking the difference, the interference of the tank's own weight and residual media in the pipeline is completely eliminated, resulting in a more accurate value for the total mass of the recovered media.

[0057] By combining the recovered medium with the residual gaseous medium in the equipment for calculation, the original total charge of the refrigeration equipment is fully restored, and accurate factory charge data can be obtained without fully emptying the equipment.

[0058] According to one embodiment of the present invention, in the first step of refrigerant recovery, P1 satisfies a pressure higher than the ambient atmospheric pressure and lower than the saturation pressure of the refrigerant charged at the lowest ambient temperature of the refrigeration equipment under test. In the refrigerant recovery step, P2 is higher than ambient atmospheric pressure but lower than P1.

[0059] In one embodiment of the present invention, During the initial recycling process, the value range of P1 is set between two boundary conditions: the lower limit is greater than the ambient atmospheric pressure, and the upper limit is less than the refrigerant saturation pressure corresponding to the lowest ambient temperature.

[0060] During the recycling process, the real-time pressure inside the equipment is continuously monitored. P2 is set to be higher than the ambient atmospheric pressure, and the value of P2 is always less than P1.

[0061] Limiting the initial recovery shutdown pressure P1 to between ambient atmospheric pressure and the minimum ambient temperature saturation pressure ensures that the refrigeration equipment under test is filled with refrigerant.

[0062] The secondary recovery uses a smaller shutdown pressure P2, which is limited to between the ambient atmospheric pressure and P1. This allows for the extraction of most of the gaseous refrigerant from the equipment, resulting in a smaller error in the residual gaseous refrigerant mass calculated using the ideal gas equation, and ensuring that ambient air and water vapor do not enter the refrigeration equipment under test.

[0063] In one embodiment of the present invention, a static pressure stabilization stage is set after both stages of recovery operation are shut down, waiting for the internal temperature and pressure of the refrigeration equipment to be evenly distributed. At this time, the gaseous refrigerant inside the refrigeration equipment fully meets the applicable conditions of the ideal gas law, and there is no local high pressure or low temperature gas phase interference.

[0064] All parameters in the equation correspond one-to-one with the physical quantities measured on site. The pressure p is taken from the internal pressure of the refrigeration equipment after it has been allowed to settle and stabilize. The volume V is the fixed gas phase space of the refrigeration equipment. m is the mass of the gas phase medium in the current refrigeration equipment. T is the thermodynamic refrigerant temperature. Rg is matched with the corresponding fixed constant of the refrigerant.

[0065] Substituting the equations into the two stable operating conditions yields two sets of equations. Subtracting the two sets of equations eliminates the unknown gas phase mass variable, leaving only the measurable weight, pressure, and temperature parameters. From this, the formula for calculating the equipment volume is derived.

[0066] The static pressure stabilization step provides the operating condition premise for the applicability of the equations. Unstable fluctuation pressure and local temperature difference are not included in the data collection, ensuring that the parameters substituted into the equations meet the theoretical applicable conditions and avoiding calculation deviations caused by the mismatch between the theoretical model and the actual operating conditions.

[0067] By collecting data after the pressure has stabilized, the gaseous medium fully meets the applicable conditions of the ideal gas model. The calculation logic is built on the basis of mature gas equations, resulting in higher theoretical completeness and controllable calculation errors.

[0068] At the same time, the volume can be solved by solving the simultaneous equations of the two operating conditions. There is no need to measure the gas phase mass of either stage separately. The inherent volume of the equipment can be deduced by relying solely on the weight change of the two recoveries, thus realizing the core function of non-destructive testing.

[0069] According to one embodiment of the present invention, before obtaining weight, pressure and ambient temperature, pressure disturbance data caused by refrigerant precipitation in the lubricating oil of the refrigeration equipment under test are discarded.

[0070] Since the dissolution and precipitation of refrigerant by lubricating oil can cause short-term irregular pressure fluctuations, eliminating disturbance data in advance and using only parameters under stable equilibrium conditions for calculation can eliminate the measurement system error caused by the dissolution effect of the medium and further improve the accuracy of inventory measurement.

[0071] like Figures 2 to 4 As shown, according to an embodiment of the present invention, the on-site measurement method of refrigerant inventory is implemented based on the on-site measurement device of refrigerant inventory of refrigeration equipment. The on-site measurement device of refrigerant inventory of refrigeration equipment includes a refrigerant recovery device 102, a refrigerant recovery tank 100, a vacuum pump 104, a weighing balance 106, a shut-off valve 108, a pressure sensor 110, and a temperature sensor 112. The shut-off valve 108 is installed at the refrigerant charging valve of the refrigeration equipment under test and connected to the inlet of the refrigerant recovery device 102; The outlet of the refrigerant recovery device 102 is connected to the inlet of the refrigerant recovery tank 100; The outlet of the refrigerant recovery tank 100 is connected to the vacuum pump 104; the weighing balance 106 is located below the refrigerant recovery tank 100.

[0072] In one embodiment of the present invention, the components of the entire refrigerant inventory measurement system are connected in pipelines according to the direction of medium flow. The charging port of the refrigeration equipment under test is equipped with a shut-off valve 108 as a pipeline on / off control node, and the pipeline behind the shut-off valve 108 is connected to the medium inlet of the refrigerant recovery device 102.

[0073] The refrigerant recovery device 102 has the function of medium extraction and transportation. The outlet of the refrigerant recovery device 102 is connected to the refrigerant recovery tank 100 through a sealed pipeline. The refrigerant recovery tank 100 can be placed on the support platform of the weighing balance 106 to continuously collect the overall weight value of the tank in real time.

[0074] The reserved interface at the top of the refrigerant recovery tank 100 is connected to the vacuum pump 104 via a pipeline. The vacuum pump 104 is used to perform the pre-test external pipeline vacuuming process, which can prevent air infiltration and media leakage.

[0075] The pressure sensor 110 signal acquisition terminal and the temperature sensor 112 signal acquisition terminal are connected to the internal space of the refrigeration equipment being tested, and transmit the refrigerant pressure and temperature values ​​of the equipment in real time.

[0076] The pre-line pipeline is evacuated by vacuum pump 104; two-stage refrigerant extraction is performed by refrigerant recovery device 102; the weight of the tank is collected by weighing balance 106; the refrigerant pressure inside the equipment is monitored in real time by pressure sensor 110; the refrigerant temperature inside the equipment is monitored in real time by temperature sensor 112; and the pipeline is controlled by shut-off valve 108, so that the refrigerant stock can work together to complete the aforementioned full-process measurement steps. Those skilled in the art can reproduce the measurement method by assembling the system according to the connection relationship.

[0077] According to one embodiment of the present invention, the refrigerant recovery device 102 includes a refrigerant transfer assembly for conveying refrigerant from the inlet of the refrigerant recovery device 102 to its outlet.

[0078] In one embodiment of the present invention, the refrigerant transfer assembly is integrated inside the housing of the refrigerant recovery device 102. The refrigerant transfer assembly includes a power delivery unit and a flow guide pipe. The power unit provides a medium delivery pressure differential, and the flow guide pipe forms a closed medium flow channel.

[0079] The pipeline inlet is connected to the external pipeline at the front end of the refrigerant recovery device 102, and the pipeline outlet is connected to the refrigerant recovery tank 100. After the transfer component is started, the refrigerant extracted from the device under test can be stably transported to the inside of the recovery tank for storage.

[0080] The refrigerant transfer assembly can smoothly deliver the medium without causing backflow or local eddies that could lead to drastic pressure fluctuations. This facilitates rapid entry into a stable pressure condition, shortens the waiting time for single pressure stabilization, and improves testing efficiency.

[0081] The integrated transfer component simplifies the layout of external pipelines, eliminating the need for additional external equipment such as transfer pumps. The on-site measurement device for refrigerant inventory of the entire refrigeration system is more integrated, making on-site handling and assembly more convenient.

[0082] According to an embodiment of the present invention, the refrigerant recovery device 102 is configured with a first working mode. In the first working mode, the inlet, outlet and internal components of the refrigerant recovery device 102 are all in a fully connected state, which is used to transport and extract air in the pipeline from the inlet to the outlet by turning on the vacuum pump 104, so as to ensure that the interior of the refrigerant recovery device 102 and the pipeline connected to its inlet and outlet are all in a vacuum state.

[0083] In one embodiment of the present invention, the first working mode is the working mode of vacuuming the pre-pipeline. When switching to this mode, all the guide pipes and medium channels inside the refrigerant recovery device 102 are fully open.

[0084] After the vacuum pump 104 is started, the vacuum suction extends along the through channel from the inlet of the refrigerant recovery device 102 to the front external measuring pipeline, which can uniformly remove the air stored in the entire external pipeline and the cavity of the refrigerant recovery device 102 until the pipeline pressure reaches the preset vacuum standard.

[0085] The first working mode is only used in the pre-start process of detection. After the vacuuming is completed, the refrigerant recovery device 102 can be switched to the second medium extraction working mode. The two modes are mutually exclusive and will not be started simultaneously.

[0086] By setting up a vacuum connection working mode, the airflow channel of the entire pipeline is opened up, with no dead corners. The pre-vacuuming process can completely remove residual air in the pipeline, eliminate the interference of air weight on the weighing reference m3, and greatly improve the accuracy of the weighing reference.

[0087] The mode-exclusive switching design separates the physical pathways of the vacuuming process and the media recovery process. During vacuuming, the refrigerant inside the device under test will not be drawn in, and during media recovery, the vacuum circuit will not be connected, preventing media loss. The two processes do not interfere with each other.

[0088] According to one embodiment of the present invention, the refrigerant recovery device 102 is configured with a second working mode. In the steps of the first refrigerant recovery and the second refrigerant recovery, the device switches to the second working mode to send the refrigerant in the refrigeration equipment under test to the refrigerant recovery tank 100 through the connecting pipeline and the refrigerant recovery device 102. It is also used to completely transport the residual refrigerant in the connecting pipeline and the internal flow path of the refrigerant recovery device 102 to the refrigerant recovery tank 100.

[0089] In one embodiment of the present invention, the second working mode is a medium recovery working mode. When switching to this mode, the internal pipeline of the refrigerant recovery device 102 is switched to a medium unidirectional transport path, the vacuum pump 104 circuit is isolated from the medium transport path, and the vacuum channel is closed.

[0090] When the refrigerant transfer component is activated, a one-way medium transport pressure difference is formed. The refrigerant extracted from the refrigeration equipment under test, as well as the residual trace medium adhering to the inner wall of the pipeline, are completely transported to the refrigerant recovery tank 100 for storage along the one-way path, and will not remain in the pipeline or the cavity of the refrigerant recovery device 102.

[0091] Both recovery processes continue to operate in the second working mode until the corresponding pressure shutdown threshold is triggered, at which point the transfer components are shut down, the passage is kept sealed, and the pressure is stabilized while parameters are collected.

[0092] The second working mode isolates the vacuum circuit, and the medium is only transported to the refrigerant recovery tank 100 in one direction, preventing the recovered medium from flowing back into the vacuum pump 104, causing pump body corrosion and medium loss, extending the service life of the vacuum pump 104, and ensuring that all extracted medium is included in the weighing value, so that there is no medium leakage error in the calculation.

[0093] By setting the second working mode, residual refrigerant adhering to the inner wall of the pipeline can be removed, avoiding residual medium remaining in the pipeline and causing the difference between the two weighings to be too small. This ensures that m2-m3 accurately correspond to all extracted media, improving the accuracy of the overall inventory calculation.

[0094] The system distinguishes between two independent pathways: vacuum mode and media recovery mode. The two operating conditions do not cross-flow, solving the problem of mutual interference between the vacuum pumping and media recovery processes. The entire measurement process has clear isolation of operating conditions, and the premise conditions of the theoretical calculation model are stable and controllable.

[0095] According to one embodiment of the present invention, the on-site measurement method for refrigerant inventory is applicable to refrigeration equipment using flammable refrigerants.

[0096] In one embodiment of the present invention, the entire measurement process adopts a segmented low-pressure extraction method, which does not completely empty the refrigerant inside the equipment. The pipeline remains in a closed state throughout the process, and the medium is only circulated between the refrigerant recovery tank 100 and the refrigeration equipment to be tested, without any refrigerant emission and diffusion.

[0097] The pre-vacuuming process only handles the external independent pipelines and does not draw negative pressure into the cavity of the equipment under test, so as not to cause ambient air or water vapor to enter the cavity of the equipment under test; both recovery stages are equipped with pressure shutdown thresholds to limit the amount of vaporized medium released.

[0098] Vacuum pump 104 and refrigerant recovery device 102 both use explosion-proof electrical components, and the pipeline sealing structure can block the leakage of flammable media. The data acquisition and calculation process is conducted under conditions where there is no open flame or electric spark.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for on-site measurement of refrigerant quantity in refrigeration equipment, characterized in that, include: First refrigerant recovery: Extract refrigerant from the refrigeration equipment under test into the refrigerant recovery tank. After stopping extraction and waiting for the system pressure to stabilize, obtain the first weight m1 of the refrigerant recovery tank, the first refrigerant pressure P1 of the refrigeration equipment under test, and the first refrigerant temperature T1. Refrigerant recovery: Extract refrigerant from the refrigeration equipment under test into the refrigerant recovery tank. After stopping extraction and waiting for the system pressure to stabilize, obtain the second weight m2 of the refrigerant recovery tank, the second refrigerant pressure P2 of the refrigeration equipment under test, and the second refrigerant temperature T2. To obtain the internal volume V of the refrigeration device under test: the internal volume V of the refrigeration device under test is calculated based on the first weight m1, the second weight m2, the first pressure P1 of the refrigerant, the second pressure P2 of the refrigerant, the first temperature T1 of the refrigerant, and the second temperature T2 of the refrigerant. Obtain the remaining refrigerant mass in the refrigeration equipment under test: Calculate the remaining refrigerant mass M1 in the refrigeration equipment under test after recycling, based on the internal volume V, the second pressure P2 of the refrigerant, and the second temperature T2 of the refrigerant. To obtain the initial refrigerant quantity in the refrigeration equipment under test: Based on the total mass of the extracted and recovered refrigerant and the remaining refrigerant mass M1, the initial refrigerant quantity M2 in the refrigeration equipment under test is calculated.

2. The method for on-site measurement of refrigerant quantity in refrigeration equipment according to claim 1, characterized in that, The formula for calculating the content product V is: V=(m2-m1)×Rg×T1×T2 / (P1×T2-P2×T1); In the formula, Rg is the specific gas constant of the refrigerant gas charged in the refrigeration equipment under test.

3. The method for on-site measurement of refrigerant quantity in refrigeration equipment according to claim 1, characterized in that, Prior to the initial refrigerant recovery step, a vacuuming step is also included: Without connecting to the refrigeration equipment under test, the measuring pipeline and device outside the refrigeration equipment under test are evacuated. When the pipeline pressure reaches the set pressure, the evacuation is stopped and the initial weight m3 of the refrigerant recovery tank is obtained.

4. The method for on-site measurement of refrigerant quantity in refrigeration equipment according to claim 3, characterized in that, The total mass of the extracted and recovered refrigerant is m2-m3, and the initial stock M2 is calculated using the following formula: M2 = M1 + (m2 - m3).

5. The method for on-site measurement of refrigerant quantity in refrigeration equipment according to claim 1, characterized in that, In the first step of refrigerant recovery, P1 satisfies the condition of being higher than the ambient atmospheric pressure and lower than the saturation pressure of the refrigerant corresponding to the lowest ambient temperature of the refrigeration equipment under test. In the step of refrigerant recovery, P2 is higher than ambient atmospheric pressure and lower than P1.

6. The method for on-site measurement of refrigerant quantity in refrigeration equipment according to any one of claims 1 to 5, characterized in that, The on-site measurement method for refrigerant inventory in refrigeration equipment is applicable to refrigeration equipment using flammable refrigerants.

7. The method for on-site measurement of refrigerant quantity in refrigeration equipment according to any one of claims 1 to 5, characterized in that, The on-site measurement method for refrigerant inventory in the refrigeration equipment is based on an on-site measurement device for refrigerant inventory in the refrigeration equipment. The on-site measurement device for refrigerant inventory in the refrigeration equipment includes a refrigerant recovery device, a refrigerant recovery tank, a vacuum pump, a weighing balance, a shut-off valve, a pressure sensor, and a temperature sensor. The shut-off valve is installed at the refrigerant charging valve of the refrigeration equipment under test and connected to the inlet of the refrigerant recovery device; The outlet of the refrigerant recovery device is connected to the inlet of the refrigerant recovery tank; The outlet of the refrigerant recovery tank is connected to the vacuum pump; the weighing balance is located below the refrigerant recovery tank.

8. The method for on-site measurement of refrigerant quantity in refrigeration equipment according to claim 7, characterized in that, The refrigerant recovery device includes a refrigerant transfer assembly for conveying refrigerant from the inlet to the outlet of the refrigerant recovery device.

9. The method for on-site measurement of refrigerant quantity in refrigeration equipment according to claim 7, characterized in that, The refrigerant recovery device is configured with a first working mode. In the first working mode, the inlet, outlet and internal components of the refrigerant recovery device are all in a fully connected state. This is used to transport and extract air from the inlet to the outlet by turning on the vacuum pump, so as to ensure that the inside of the refrigerant recovery device and the pipelines connected to its inlet and outlet are all in a vacuum state.

10. The method for on-site measurement of refrigerant quantity in refrigeration equipment according to claim 9, characterized in that, The refrigerant recovery device is configured with a second working mode. In the steps of the first refrigerant recovery and the second refrigerant recovery, the device switches to the second working mode to send the refrigerant in the refrigeration equipment under test to the refrigerant recovery tank through the connecting pipeline and the refrigerant recovery device. It is also used to completely transport the residual refrigerant in the connecting pipeline and the internal flow path of the refrigerant recovery device to the refrigerant recovery tank.

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