Device and method suitable for testing gas viscosity under multiple working conditions

Abstract

The invention relates to the technical field of gas viscosity testing, in particular to a gas viscosity testing device and method suitable for multiple working conditions, the gas viscosity testing device comprises a constant temperature box, a capillary tube, a driving mechanism, a first cylinder and a second cylinder, and the first cylinder and the second cylinder have the same structure and are arranged oppositely. The device is reasonable and compact in structure, and the coaxial equal-diameter double cylinders which are oppositely mounted are adopted, so that two problems in a gas viscosity capillary method test can be solved: firstly, the gas state is adjusted, and the piston rod moves left and right by utilizing the driving mechanism, so that the volume of a rodless cavity of the cylinder is changed; in this way, the pressure increasing or reducing function can be achieved through the driving mechanism and the air cylinder, and therefore gas reaches the set pressure. The gas state is kept constant in the testing process, the first air cylinder and the second air cylinder are communicated with the capillary tube to form a closed testing loop in the testing process, the gas flow in the testing loop can be adjusted by changing the movement speed of pistons of the two air cylinders, and the requirement for conducting multiple sets of tests in the same gas state is met.

Description

Technical Field

[0001] The present invention relates to the technical field of gas viscosity testing, and is a testing device and method for gas viscosity applicable to multiple working conditions. Background Art

[0002] The accurate determination of gas viscosity is of great significance in many key fields such as petrochemical industry, transportation, and national defense industry. Gas viscosity is closely related to its state, such as high-pressure natural gas in oil and gas wells, negative-pressure air in high-altitude environments, etc. There are mainly two methods for obtaining gas viscosity: one is the theoretical calculation method, which is estimated based on the molecular motion theory and state equation. Although this method is simple, it is limited by the assumptions of the theoretical model and is difficult to accurately reflect the true viscosity of gas under actual working conditions, especially with large errors in high-temperature, high-pressure, or non-ideal gas systems; the other is the experimental measurement method, including the falling ball method, vibrating wire method, and capillary method, etc. The falling ball method is only applicable to transparent media and has high requirements for detecting the movement of the sphere; the vibration method requires isolating external vibration interference and has a complex device structure; the capillary method is widely used in gas viscosity testing in laboratories and industrial sites due to its simple structure and wide application range.

[0003] The principle of measuring gas viscosity by the capillary method is as follows: The gas to be measured is adjusted to a set temperature and pressure, and then flows through a capillary with a known inner diameter and length at a constant volume flow rate. The pressure difference at both ends of the capillary is measured, and the Hagen-Poiseuille formula for laminar flow is used to calculate the gas viscosity. The constancy of the gas state and the stability of the volume flow rate during the entire testing process are two basic prerequisites to ensure the accuracy and reliability of the viscosity measurement results.

[0004] Chinese patent document with the publication number CN111307663A discloses a gas viscosity measurement device, which includes a storage tank, a mass flow control component, a first pressure gauge, a first capillary, a second pressure gauge, and a second capillary connected in sequence through pipelines, as well as a first differential pressure gauge connected in parallel with the first capillary and a second differential pressure gauge connected in parallel with the second capillary; the first pressure gauge is used to measure the pressure at the inlet end of the first capillary, and the second pressure gauge is used to measure the pressure at the inlet end of the second capillary; the gas viscosity measurement device further includes a first constant temperature bath for keeping the gas in the first capillary at a constant temperature, a first thermocouple for measuring the temperature of the gas in the first capillary, a second constant temperature bath for keeping the gas in the second capillary at a constant temperature, and a second thermocouple for measuring the temperature of the gas in the second capillary.

[0005] The Chinese patent document with the publication number CN109142152A discloses a double capillary viscometer for measuring the viscosity of sour natural gas, which includes an inlet stop valve connected to a gas cylinder, a measurement pipeline connected to the inlet stop valve, successively connected with a solid particle filter and a gas dryer, and connected to an upstream inlet piezoelectric valve; along the main test pipeline, there are successively connected an upstream capillary, a middle piezoelectric valve, a downstream preheating capillary, a downstream test capillary, a downstream outlet piezoelectric valve, an outlet stop valve, then connected with an H2S absorption bottle, and finally connected to a vacuum pump; the above test pipeline is divided into an upstream pipeline and a downstream pipeline; among them, the upstream capillary is wound around a columnar aluminum block in a spiral manner and immersed in an alcohol constant temperature device, and the downstream preheating capillary and the downstream test capillary are immersed in a silicone oil constant temperature device in the same way; after the upstream inlet piezoelectric valve, an upstream inlet end pressure gauge is connected, and an upstream outlet end pressure gauge is installed in front of the middle piezoelectric valve, and the two pressure gauges are connected by an upstream differential pressure gauge; between the downstream preheating capillary and the downstream test capillary, a downstream inlet pressure gauge is installed, and a downstream outlet end pressure gauge is installed in front of the downstream outlet piezoelectric valve, and the two pressure gauges are connected by a downstream differential pressure gauge.

[0006] In order to achieve gas state regulation and flow control, components such as a pressure reducing valve and a back pressure valve are used in the gas viscosity measurement device; a double capillary viscometer for measuring the viscosity of sour natural gas uses a piezoelectric valve with control logic, but both of the above two solutions have two problems: one is that the dynamic change of the valve opening during the adjustment of the pressure reducing valve or the piezoelectric valve causes the gas state in the capillary to change during the test; the other is that the flow rate in the pipeline is affected by the compressibility of the gas and it is difficult to maintain stability.

[0007] The Chinese patent document with the publication number CN110646567A discloses a PVT test device and method suitable for ultra-high pressure and high temperature viscosity joint measurement, which consists of upper and lower PVT cylinders, a high-definition camera, a capillary viscometer, a sealed piston cylinder, and a high-temperature oven. The device is located in the high-temperature oven. The upper PVT cylinder has a displacement rod with a piston and a grating ruler, and the advance of the displacement rod is measured by the grating ruler. The lower PVT cylinder has a rigid direct drive with a piston, and the pistons are all provided with tip protruding parts. The displacement rod is connected to the rigid direct drive through a balance pressure pipeline and a control valve, and makes a displacement movement relying on the pressure transmitted by the balance pressure pipeline. The displacement rod and the rigid direct drive are both connected with a magnetic drive stirrer; the upper and lower PVT cylinders have glass windows and channel holes, the channel holes face the high-definition camera, and there is a pneumatic isolation valve between the upper and lower PVT cylinders. The capillary viscometer is respectively connected to the internal spaces of the upper and lower PVT cylinders through a three-way valve and a pressure gauge; the sealed piston cylinder is connected to the internal space of the upper PVT cylinder through a pressure gauge and a three-way valve, and the sealed piston cylinder has a rigid direct drive with a piston. Using two face-to-face arranged PVT cylinders with pistons, the test fluid is introduced into the interconnected PVT cylinders and capillaries through an external high-pressure pipeline.

[0008] It uses two PVT cylinders with pistons arranged face to face. The test fluid is introduced into the interconnected PVT cylinders and capillary through an external high-pressure pipeline. An additional balanced pressure pipeline is used to drive the piston to make the test fluid flow in the capillary for viscosity testing. To ensure the constancy of the fluid state and flow rate in the test pipeline, the medium pressure in the balanced pressure pipeline needs to be high enough and maintained stably.

[0009] Chinese patent document with publication number CN113567302A discloses a high-temperature and high-pressure oil and gas fluid viscosity measuring instrument and its use method, which includes a high-pressure cavity and an external pressure system. The inside of the high-pressure cavity is axially arranged as an open cavity. End face covers are provided at both ports of the high-pressure cavity for sealing. Through holes are opened in the middle of the end faces of the two end face covers. Three through holes are provided in the middle of the top of the outside of the high-pressure cavity. The high-pressure pipeline of the external pressure system is connected to the five through holes of the high-pressure cavity. The through holes are all high-pressure fluid channels. A heating jacket is arranged around the outer side of the high-pressure cavity.

[0010] It connects two high-pressure cavities on both sides of the capillary, and uses two high-pressure displacement pumps and hydraulic oil to push the pistons of the high-pressure cavities, so that the test gas enters the capillary for viscosity testing. To make the state and flow rate of the test gas in the capillary constant, the high-pressure displacement pumps need to provide a high enough thrust and maintain a synchronous operating speed.

[0011] The method of using a balanced pressure pipeline or a high-pressure displacement pump in a PVT test device and method suitable for ultra-high pressure and high-temperature viscosity joint measurement, as well as a high-temperature and high-pressure oil and gas fluid viscosity measuring instrument and its use method, increases the complexity and operation difficulty of the test system, thus affecting the accuracy of viscosity testing.

[0012] Currently, the existing publicly disclosed viscosity testing methods are only applicable to viscosity testing of gases with pressures higher than atmospheric pressure. There are still no effective testing devices and methods for the viscosity of gases in a negative pressure state. Summary of the Invention

[0013] The present invention provides a testing device and method suitable for the viscosity of gases under multiple working conditions, overcoming the above-mentioned deficiencies of the prior art. It can effectively solve the problems of adjustment of the gas state before testing, change of the gas state during testing, and unstable regulation of volume flow rate existing in the existing gas viscosity testing devices.

[0014] One of the technical solutions of the present invention is achieved by the following measures: A test device applicable to the gas viscosity under multiple working conditions includes a constant temperature box, a capillary tube, a driving mechanism, and a first cylinder and a second cylinder with the same structure and arranged back to back. A driving mechanism is provided between the right end of the piston rod of the first cylinder and the left end of the piston rod of the second cylinder. The driving mechanism enables the piston rods of the first cylinder and the second cylinder to move synchronously and in the same direction. The first cylinder is provided with a first air inlet and a first air outlet that are internally and externally connected at intervals on the outside. Both the first air inlet and the first air outlet are communicated with the rodless cavity of the first cylinder. The second cylinder is provided with a second air inlet and a second air outlet that are internally and externally connected at intervals on the outside. Both the second air inlet and the second air outlet are communicated with the rodless cavity of the second cylinder. A capillary tube is provided in the constant temperature box. A first test pipeline is fixedly connected between the first end of the capillary tube and the first air outlet. An evacuation pipeline is fixedly connected to the first test pipeline, and an evacuation valve is installed on the evacuation pipeline. A second test pipeline is fixedly connected between the second end of the capillary tube and the second air outlet. A differential pressure gauge is provided between the first end and the second end of the capillary tube.

[0015] The following is a further optimization or / and improvement of one of the above-mentioned invention technical solutions: The above may further include a first four-way valve and a second four-way valve. A buffer gas tank is provided in the constant temperature box. The air outlet of the buffer gas tank is fixedly connected to the first end of the capillary tube. The first test pipeline is fixedly connected between the air inlet of the buffer gas tank and the first port of the first four-way valve. A third test pipeline is fixedly connected between the second port of the first four-way valve and the first air outlet. A fourth test pipeline is fixedly connected between the third port of the first four-way valve and the third test pipeline. A first exhaust check valve is installed on the fourth test pipeline; The second test pipeline is fixedly connected between the second end of the capillary tube and the first port of the second four-way valve. A fifth test pipeline is fixedly connected between the second port of the second four-way valve and the second air outlet. A sixth test pipeline is fixedly connected between the third port of the second four-way valve and the fifth test pipeline. A second exhaust check valve is installed on the sixth test pipeline; The fourth port of the first four-way valve is fixedly connected to a first air inlet pipeline, and an air inlet valve is installed on the first air inlet pipeline. A second air inlet pipeline is fixedly connected between the first air inlet pipeline at the position corresponding to the air inlet valve and the first four-way valve and the fourth port of the second four-way valve. A third air inlet pipeline is fixedly connected between the first air inlet pipeline at the position corresponding to the second air inlet pipeline and the first four-way valve and the first air inlet. A first air inlet check valve is installed on the third air inlet pipeline. A fourth air inlet pipeline is fixedly connected between the second air inlet pipeline and the second air inlet. A second air inlet check valve is installed on the fourth air inlet pipeline.

[0016] The fourth test pipeline corresponding to the position between the first exhaust check valve and the first four-way valve can be fixedly connected to a first pressure relief pipe, on which a first pressure relief valve is installed; the sixth test pipeline corresponding to the position between the second exhaust check valve and the second four-way valve is fixedly connected to a second pressure relief pipe, on which a second pressure relief valve is installed.

[0017] The above-mentioned constant temperature box may include a thermostat, a temperature controller and a box body. The buffer gas tank, capillary tube and thermostat are fixedly installed in the box body at intervals. A temperature sensor is provided in the box body. The temperature sensor and the thermostat are both connected to the temperature controller. Insulation layers are provided on the outside of the box body, the outside of the first cylinder and the outside of the second cylinder.

[0018] The above-mentioned driving mechanism may include a driving motor and a screw, the output shaft of the driving motor is transmission-connected to the middle part of the screw, and the two ends of the screw are detachably fixedly installed with the right end of the piston rod of the first cylinder and the left end of the piston rod of the second cylinder respectively.

[0019] The second technical solution of the present invention is achieved by the following measures: A method for testing the viscosity of a gas under multiple working conditions comprises the following steps: Step 1, connecting the end of the first air inlet line to the air source; Step 2: close the first pressure relief valve, the second pressure relief valve and the exhaust valve, open the air inlet valve, control the first four-way valve and the second four-way valve, and allow gas to enter the rodless chamber of the first cylinder, the buffer gas tank, the capillary tube and the rodless chamber of the second cylinder; open the exhaust valve so that the driving mechanism drives the piston rod of the first cylinder and the piston rod of the second cylinder to move synchronously to the left or to the right; Step 3: Close the drain valve, open the thermostat and temperature controller, make the temperature in the box reach the test temperature and keep it constant, and close the air inlet valve; Step 4: Make the pressure in the buffer gas tank reach the target value, and drive the motor to move the lead screw to the right or left at a set speed V; Step 5, record the differential pressure gauge reading ΔP on both sides of the capillary tube, and calculate the flow rate Q=VA according to the set speed V and the cross-sectional area A of the first cylinder; Step 6: Calculate the gas viscosity μ according to the following formula: in is the capillary radius, is the capillary length, is the pressure difference, is the volume flow rate; Step 7, change the set speed of the screw, repeat steps 4 to 6, and measure multiple groups of gas viscosities; Step 8: Compare and analyze multiple groups of test results to obtain accurate gas viscosity values.

[0020] The following is a further optimization and / or improvement of the second technical solution of the above invention: As a first preference, the specific step 2 is as follows: Close the first pressure relief valve, the second pressure relief valve, and the drain valve, open the intake valve, the first port and the second port of the first four-way valve, and the first port and the second port of the second four-way valve. Gas enters the rodless cavity of the first cylinder, the buffer gas tank, the capillary tube, and the rodless cavity of the second cylinder. Open the drain valve, and the drive motor drives the piston rods of the first cylinder and the second cylinder to move synchronously to the left or synchronously to the right.

[0021] As a second preference, the specific step 2 is as follows: Close the first pressure relief valve, the second pressure relief valve, and the drain valve, open the intake valve, the first port and the third port of the first four-way valve, and the first port and the third port of the second four-way valve. Gas enters the rodless cavity of the first cylinder, the buffer gas tank, the capillary tube, and the rodless cavity of the second cylinder. Start the drive motor, and the drive motor drives the piston rods of the first cylinder and the second cylinder to reciprocate left and right. The rodless cavities of the first cylinder and the second cylinder inhale and exhaust gas periodically, so that the gas pressure in the first test pipeline is greater than the target value. Open the drain valve, and the drive motor drives the piston rods of the first cylinder and the second cylinder to move synchronously to the left or synchronously to the right.

[0022] As a third preference, the specific step 2 is as follows: Close the first pressure relief valve, the second pressure relief valve, and the drain valve, open the intake valve, the first port and the third port of the first four-way valve, and the first port and the third port of the second four-way valve. Gas enters the rodless cavity of the first cylinder, the buffer gas tank, the capillary tube, and the rodless cavity of the second cylinder. Open the drain valve, and the drive motor drives the piston rods of the first cylinder and the second cylinder to move synchronously to the left or synchronously to the right. Close the intake valve, open the first port and the fourth port of the first four-way valve, the first port and the fourth port of the second four-way valve, the first pressure relief valve, and the second pressure relief valve. The drive motor drives the piston rods of the first cylinder and the second cylinder to move synchronously to the left or synchronously to the right. The rodless cavities of the first cylinder and the second cylinder inhale gas from the first test pipeline and discharge the gas through the first pressure relief pipe and the second pressure relief pipe. The pressure of the first test pipeline is greater than the set negative pressure value.

[0023] The structure of the present invention is reasonable and compact. This application uses coaxially arranged double cylinders with equal diameters mounted back to back (the first cylinder and the second cylinder), which can solve two problems in the gas viscosity capillary method test: one is the adjustment of the gas state. The driving mechanism is used to move the piston rod left and right, thereby changing the volume of the rodless cavity of the cylinder. When the volume of the rodless cavity decreases, the pressurization effect of the gas is achieved; when the volume of the rodless cavity increases, the depressurization effect of the gas is achieved. In this way, the driving mechanism and the cylinder can be used to achieve the pressurization or depressurization function, so that the gas reaches the set pressure, and the thermostat is used to make the gas reach the set temperature. The other is to maintain the constancy of the gas state during the test. During the test, the first cylinder, the second cylinder and the capillary are connected to form a closed test loop. The pistons of the two cylinders produce synchronous and isovelocity push / pull reverse actions on the gas. The gas volume in the test loop remains unchanged, realizing quasi-steady flow, ensuring the constancy of the gas state. Changing the piston movement speed of the two cylinders can also adjust the gas flow in the test loop, meeting the needs of multiple groups of tests under the same gas state, and improving the accuracy of the gas viscosity test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Attached Figure 1 are schematic structural diagrams of Embodiments 1 to 7 of the present invention.

[0025] Attached Figure 2 is the front sectional structural schematic diagram of the driving mechanism in Embodiment 5 of the present invention Figure 1 .

[0026] Attached Figure 3 is the front sectional structural schematic diagram of the driving mechanism in Embodiment 5 of the present invention Figure 2 .

[0027] The codes in the drawings are respectively: 1 is the box body, 2 is the capillary, 3 is the first cylinder, 4 is the second cylinder, 5 is the first test pipeline, 6 is the evacuation pipeline, 7 is the evacuation valve, 8 is the second test pipeline, 9 is the differential pressure gauge, 10 is the first four-way valve, 11 is the second four-way valve, 12 is the buffer gas tank, 13 is the third test pipeline, 14 is the fourth test pipeline, 15 is the first exhaust check valve, 16 is the fifth test pipeline, 17 is the sixth test pipeline, 18 is the second exhaust check valve, 19 is the first air inlet pipeline, 20 is the inlet valve, 21 is the second air inlet pipeline, 22 is the third air inlet pipeline, 23 is the first air inlet check valve, 24 is the fourth air inlet pipeline, 25 is the second air inlet check valve, 26 is the first pressure relief pipe, 27 is the first pressure relief valve, 28 is the second pressure relief pipe, 29 is the second pressure relief valve, 30 is the thermostat, 31 is the temperature controller, 32 is the temperature sensor, 33 is the heat insulation layer, 34 is the lead screw, 35 is the driving motor, 36 is the base, 37 is the reducer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0029] In the present invention, for the convenience of description, the relative position relationship of each component is described according to the attached Figure 1 The layout is described in detail, such as the positional relationship of front, back, top, bottom, left, right, etc., which is based on the attached manual. Figure 1 It is determined by the layout direction.

[0030] The present invention will be further described below in conjunction with embodiments and drawings: Embodiment 1: As shown in the attached Figure 1 As shown, the test device for the viscosity of gases under multiple working conditions comprises a constant temperature box, a capillary 2, a driving mechanism, and a first cylinder 3 and a second cylinder 4 of the same structure and arranged in opposite directions. A driving mechanism is arranged between the right end of the piston rod of the first cylinder 3 and the left end of the piston rod of the second cylinder 4. The driving mechanism enables the piston rods of the first cylinder 3 and the second cylinder 4 to move synchronously in the same direction. A first air inlet and a first air outlet that are connected inside and outside are arranged at intervals on the outer side of the first cylinder 3. The first air inlet and the first air outlet are both connected to the rodless cavity of the first cylinder 3. A second air inlet and a second air outlet which are connected inside and outside are provided at intervals on the outside of the second cylinder 4. Both the second air inlet and the second air outlet are connected to the rodless cavity of the second cylinder 4. A capillary 2 is provided in the constant temperature box. A first test pipeline 5 is fixedly connected between the first end of the capillary 2 and the first air outlet. A drain pipeline 6 is fixedly connected to the first test pipeline 5. A drain valve 7 is installed on the drain pipeline 6. A second test pipeline 8 is fixedly connected between the second end of the capillary 2 and the second air outlet. A differential pressure gauge 9 is provided between the first end and the second end of the capillary 2.

[0031] The first cylinder 3 and the second cylinder 4 are arranged back to back, that is, when the piston rod of the first cylinder 3 moves to the right, the volume of the rodless chamber of the first cylinder 3 increases, and at the same time, the piston rod of the second cylinder 4 moves to the right, and the volume of the rodless chamber of the second cylinder 4 decreases. Conversely, when the piston rod of the first cylinder 3 moves to the left, the volume of the rodless chamber of the first cylinder 3 decreases, and at the same time, the piston rod of the second cylinder 4 moves to the left, and the volume of the rodless chamber of the second cylinder 4 increases.

[0032] According to the requirements, the inner diameter of the capillary 2 is 0.75 to 2 mm, and the length is 3 to 5 m. A connecting pipe is fixedly connected between the left and right ends of the capillary 2, and a differential pressure gauge 9 is installed on the connecting pipe. The pressure bearing capacity of the first cylinder 3 and the second cylinder 4 is not less than 200 MPa.

[0033] This application uses coaxial equal-diameter double cylinders (the first cylinder 3 and the second cylinder 4) installed back-to-back, which can solve two problems in the gas viscosity capillary method test: one is the adjustment of the gas state. By using the driving mechanism to move the piston rod left and right, the volume of the rodless cavity of the cylinder is changed. When the volume of the rodless cavity decreases, the pressurization effect of the gas is achieved. When the volume of the rodless cavity increases, the depressurization effect of the gas is achieved. In this way, the pressurization or depressurization function can be realized by the driving mechanism and the cylinder, so that the gas reaches the set pressure, and the thermostat is used to make the gas reach the set temperature. The other is to maintain the constancy of the gas state during the test. During the test, the first cylinder 3, the second cylinder 4 and the capillary 2 are connected to form a closed test loop. The pistons of the two cylinders produce synchronous and equal-speed push / pull reverse actions on the gas (when one cylinder produces a push action on the gas, the other cylinder produces a synchronous and equal-speed pull action on the gas). The volume of the gas in the test loop remains unchanged, realizing quasi-steady flow, ensuring the constancy of the gas state. Changing the piston movement speed of the two cylinders can also adjust the gas flow rate in the test loop, meeting the needs of multiple groups of tests under the same gas state and improving the accuracy of the gas viscosity test results.

[0034] According to actual needs, the above test device applicable to gas viscosity under multiple working conditions can be further optimized and / or improved: Embodiment 2: As an optimization of the above embodiment, as shown in the appendix Figure 1 It also includes a first four-way valve 10 and a second four-way valve 11. A buffer gas tank 12 is provided in the thermostat. The air outlet of the buffer gas tank 12 is fixedly connected to the first end of the capillary 2. The first test pipeline 5 is fixedly connected between the air inlet of the buffer gas tank 12 and the first port of the first four-way valve 10. A third test pipeline 13 is fixedly connected between the second port of the first four-way valve 10 and the first air outlet. A fourth test pipeline 14 is fixedly connected between the third port of the first four-way valve 10 and the third test pipeline 13. A first exhaust check valve 15 is installed on the fourth test pipeline 14.

[0035] The second test pipeline 8 is fixedly connected between the second end of the capillary 2 and the first port of the second four-way valve 11. A fifth test pipeline 16 is fixedly connected between the second port of the second four-way valve 11 and the second air outlet. A sixth test pipeline 17 is fixedly connected between the third port of the second four-way valve 11 and the fifth test pipeline 16. A second exhaust check valve 18 is installed on the sixth test pipeline 17.

[0036] The fourth port of the first four-way valve 10 is fixedly connected to a first intake pipeline 19. An intake valve 20 is installed on the first intake pipeline 19. A second intake pipeline 21 is fixedly connected between the first intake pipeline 19 at a position corresponding to between the intake valve 20 and the first four-way valve 10 and the fourth port of the second four-way valve 11. A third intake pipeline 22 is fixedly connected between the first intake pipeline 19 at a position corresponding to between the second intake pipeline 21 and the first four-way valve 10 and the first intake port. A first intake check valve 23 is installed on the third intake pipeline 22. A fourth intake pipeline 24 is fixedly connected between the second intake pipeline 21 and the second intake port. A second intake check valve 25 is installed on the fourth intake pipeline 24.

[0037] According to requirements, the first four-way valve 10, the second four-way valve 11, the first exhaust check valve 15, the second exhaust check valve 18, the first intake check valve 23, and the second intake check valve 25 are all well-known prior arts. During use, through the first four-way valve 10 and the second four-way valve 11, according to different gas sources, the other end of the first intake pipeline 19 can be connected to the gas source. When the gas source is a high-pressure gas source, the first port and the second port of the first four-way valve 10 are connected, the first port and the second port of the second four-way valve 11 are connected, the intake valve 20 is opened, and the high-pressure gas source enters the rodless cavity of the first cylinder 3, the third test pipeline 13, the first test pipeline 5, and the capillary 2 through the third intake pipeline 22, and at the same time enters the rodless cavity of the second cylinder 4, the fifth test pipeline 16, the second test pipeline 8, and the capillary 2 through the fourth intake pipeline 24.

[0038] When the gas source is a low-pressure mixed gas, the first port and the third port of the first four-way valve 10 are connected, the first port and the third port of the second four-way valve 11 are connected, the intake valve 20 is opened, and the low-pressure mixed gas enters the rodless cavity of the first cylinder 3, the fourth test pipeline 14, the first test pipeline 5, and the capillary 2 through the third intake pipeline 22, and at the same time enters the rodless cavity of the second cylinder 4, the sixth test pipeline 17, the second test pipeline 8, and the capillary 2 through the fourth intake pipeline 24.

[0039] According to different test methods, the gas source can be a low-pressure mixed gas or a high-pressure gas source. The high-pressure gas source can be the on-line gas of an industrial pipeline / device or the high-pressure gas generated by a pressurizing device.

[0040] Embodiment 3: As an optimization of the above embodiment, as shown in the appendix Figure 1 As shown, a first pressure relief pipe 26 is fixedly connected to the fourth test pipeline 14 at a position corresponding to between the first exhaust check valve 15 and the first four-way valve 10. A first pressure relief valve 27 is installed on the first pressure relief pipe 26. A second pressure relief pipe 28 is fixedly connected to the sixth test pipeline 17 at a position corresponding to between the second exhaust check valve 18 and the second four-way valve 11. A second pressure relief valve 29 is installed on the second pressure relief pipe 28.

[0041] When the gas source is a low-pressure mixed gas, the first port and the fourth port of the first four-way valve 10 are communicated, and the first port and the fourth port of the second four-way valve 11 are communicated. The intake valve 20 is opened, and the low-pressure mixed gas enters the first test pipeline 5 and the capillary 2 through the first intake pipeline 19, and at the same time enters the second test pipeline 8 and the capillary 2 through the second intake pipeline 21. Then the first pressure relief valve 27 and the second pressure relief valve 29 are opened, and the driving mechanism drives the piston rods of the first cylinder 3 and the second cylinder 4 to reciprocate left and right. When the driving mechanism drives the piston rods of the first cylinder 3 and the second cylinder 4 to move to the left, the volume of the rodless cavity of the first cylinder 3 decreases, and at the same time the volume of the rodless cavity of the second cylinder 4 increases, and the gas in the second test pipeline 8 is sucked into the rodless cavity of the second cylinder 4.

[0042] When the driving mechanism drives the piston rods of the first cylinder 3 and the second cylinder 4 to move to the right, the volume of the rodless cavity of the first cylinder 3 increases, and the gas in the first test pipeline 5 is sucked into the rodless cavity of the first cylinder 3. At the same time, the volume of the rodless cavity of the second cylinder 4 decreases, and the gas in the rodless cavity of the second cylinder 4 is discharged through the second pressure relief pipe 28.

[0043] When the driving mechanism drives the piston rods of the first cylinder 3 and the second cylinder 4 to move to the left again, the volume of the rodless cavity of the first cylinder 3 decreases, and the gas in the rodless cavity of the first cylinder 3 is discharged through the first pressure relief pipe 26. At the same time, the volume of the rodless cavity of the second cylinder 4 increases, and the gas in the second test pipeline 8 is sucked into the rodless cavity of the second cylinder 4 again. In this way, the gas in the first test pipeline 5, the second test pipeline 8 and the capillary 2 decreases, and the pressure drops until the set negative pressure value is reached.

[0044] Embodiment 4: As an optimization of the above embodiment, as shown in the attached Figure 1 As shown in the figure, the thermostat box includes a thermostat 30, a temperature controller 31 and a box body 1. The buffer gas tank 12, the capillary 2 and the thermostat 30 are fixedly installed in the box body 1 at intervals. A temperature sensor 32 is provided in the box body 1. The temperature sensor 32 and the thermostat 30 are both connected to the temperature controller 31. Heat insulation layers 33 are provided on the outer side of the box body 1, the outer side of the first cylinder 3 and the outer side of the second cylinder 4.

[0045] According to requirements, the thermostat 30 is a known prior art, such as an electric heater, a heat exchanger, and a refrigerator. The thermostat has heating and refrigerating functions, and the temperature control range is -40 to 220 °C. In the test device for the gas viscosity under multiple working conditions, heat insulation layers 33 are provided on the test pipeline in contact with air, the outer side of the box body 1, the surface of the first cylinder 3, the surface of the second cylinder 4, and the surface of the valve body. A pressure gauge is provided on the buffer gas tank 12 to facilitate the testing of the gas pressure. During the use process, through such a setting, the temperature environment of the buffer gas tank 12 and the capillary 2 is made constant, and the influence of temperature change on the gas in the pipeline during the testing process is reduced, which can improve the accuracy of the test results.

[0046] Embodiment 5: As an optimization of the above embodiment, as shown in the attached Figure 1 , 2 , 3, the driving mechanism includes a driving motor 35 and a lead screw 34. The output shaft of the driving motor 35 is drivingly connected to the middle of the lead screw 34. The two ends of the lead screw are respectively detachably and fixedly installed with the right end of the piston rod of the first cylinder 3 and the left end of the piston rod of the second cylinder 4.

[0047] According to requirements, the driving motor 35 and the lead screw 34 form a known through-type lead screw stepping motor (such as a through-type ball screw stepping motor disclosed in the Chinese patent document with the publication number CN217240551U, whose reciprocating positioning accuracy of the ball screw can be about 0.03 mm, and the motor is input through a pulse signal), as shown in the attached Figure 1 . A base (not shown in the figure) is fixedly installed on the lower side of the driving motor 35. The upper side of the left part of the base is fixedly installed with the lower side of the first cylinder 3, and the upper side of the right part of the base is fixedly installed with the lower side of the second cylinder 4. The left end of the lead screw 34 is rotatably installed with the right end of the piston rod of the first cylinder 3 (rotatably installed through a known rotary joint), and at the same time, the right end of the lead screw 34 is rotatably installed with the left end of the piston rod of the second cylinder 4. In this way, when the lead screw 34 moves left and right (helical movement), it can drive the piston rods of the first cylinder 3 and the second cylinder 4 to move synchronously and in the same direction.

[0048] Or, as shown in the attached Figure 2As shown in the figure, the driving mechanism includes a driving motor (not shown in the figure) and a lead screw 34. A base 36 is fixedly installed on the lower side of the driving motor. The upper side of the left part of the base 36 is fixedly installed together with the lower side of the first cylinder 3, and the upper side of the right part of the base 36 is fixedly installed together with the lower side of the second cylinder 4. A speed reducer 37 is provided behind the driving motor 35. The speed reducer 37 is a well-known double-output shaft speed reducer in the prior art. The rear end of the output shaft of the driving motor is connected to the front end of the input shaft of the speed reducer 37 through a coupling. Lead screws are fixedly installed at both ends of the two output shafts of the double-output shaft speed reducer. The right end of the piston rod of the first cylinder 3 is fixedly installed with a first lead screw nut, and the first lead screw nut is threadedly connected to the outer side of the left lead screw 34. The left end of the piston rod of the second cylinder 4 is fixedly installed with a second lead screw nut, and the second lead screw nut is threadedly connected to the outer side of the right lead screw 34. In order to prevent the first lead screw nut and the second lead screw nut from rotating with the lead screw 34, the lower sides of the first lead screw nut and the second lead screw nut are in contact with the upper side of the base 36 respectively. It can also be attached Figure 3 As shown in the figure, a first guide rod parallel to the left lead screw 34 is inserted into the first lead screw nut, and a second guide rod parallel to the right lead screw 34 is inserted into the second lead screw nut. The left and right ends of the first guide rod are fixedly installed between the right end of the first cylinder 3 and the left side of the speed reducer 37, and the left and right ends of the second guide rod are fixedly installed between the right side of the speed reducer 37 and the left end of the second cylinder 4. In this way, the driving motor drives the lead screws on both sides to rotate through the speed reducer 37, so that the first lead screw nut and the second lead screw nut move leftward or rightward simultaneously. The rotation of the driving motor 35 can be realized through a well-known RCmf stepper motor driver in the prior art. In this way, the stepper motor penetrating the lead screw 34 can convert the rotational motion into the linear reciprocating motion of the pistons of the two cylinders.

[0049] The present application has the following technical effects: First, by using the first cylinder 3 and the second cylinder 4, the functions of pressurizing or decompressing the gas in the first test pipeline and the second test pipeline can be realized, so that the gas reaches the set high pressure or negative pressure state, meeting the requirements of various working conditions tests. This device can test the gas viscosity in the temperature range of -40 to 220 °C and the pressure (gauge pressure) range of -0.098 MPa to 200 MPa.

[0050] Second, during the test process, the gas state is maintained constant. During the test, the first cylinder 3 and the second cylinder 4 are connected to the capillary 2 to form a closed test loop. The pistons of the first cylinder 3 and the second cylinder 4 produce synchronous and isovelocity push / pull reverse effects on the gas. The gas volume in the test loop remains unchanged, realizing quasi-steady-state flow, ensuring the constancy of the gas state. Changing the piston movement speed can also adjust the gas flow in the test loop, meeting the requirements of multiple groups of tests under the same gas state, and improving the accuracy of the gas viscosity test results.

[0051] Thirdly, the first cylinder 3 and the second cylinder 4 with the same diameter and coaxial arrangement and opposite installation are adopted. The piston rods of the first cylinder 3 and the second cylinder 4 are connected to the lead screw, which can ensure the precise synchronous movement of the two pistons. Moreover, the gas forces acting on the end faces of the pistons connected to both ends of the lead screw are balanced. In this way, the driving motor 35 only needs to overcome a small friction force to achieve the precise and stable reciprocating linear motion of the lead screw 34, reducing the complexity and operation difficulty of the test system.

[0052] Example 6: As shown in the appendix Figure 1 The testing method for the gas viscosity under multiple working conditions includes the following steps: Step 1: Connect the end of the first intake pipeline 19 to the gas source. Step 2: Close the first pressure relief valve 27, the second pressure relief valve 29, and the evacuation valve 7. Open the intake valve 20, the first port and the second port of the first four-way valve 10, and the first port and the second port of the second four-way valve 11. The gas enters the rodless cavity of the first cylinder 3, the buffer gas tank 12, the capillary tube 2, and the rodless cavity of the second cylinder 4. Open the evacuation valve 7, and the driving motor 35 drives the piston rods of the first cylinder 3 and the second cylinder 4 to move synchronously to the left or synchronously to the right. Step 3: Close the evacuation valve 7, open the thermostat 30 and the temperature controller 31, so that the temperature inside the box 1 reaches the test temperature and remains constant, and close the intake valve 20. Step 4: Make the pressure in the buffer gas tank 12 reach the target value, and the driving motor 35 makes the lead screw 34 move to the right or to the left at the set speed V. Step 5: Record the reading ΔP of the differential pressure gauge 9 on both sides of the capillary tube 2. According to the set speed V and the cross-sectional area A of the first cylinder 3, calculate the flow rate Q = VA. Step 6: Calculate the gas viscosity μ according to the following formula (Hagen-Poiseuille formula, that is, the Hagen-Poiseuille formula) where is the radius of the capillary tube 2, is the length of the capillary tube 2, is the pressure difference, is the volume flow rate; Step 7: Change the set speed of the lead screw 34, and repeat Steps 4 to 6 to measure multiple groups of gas viscosities. Step 8: Compare and analyze the multiple groups of test results to obtain the accurate gas viscosity value.

[0053] The gas source in this embodiment is a high-pressure gas source, and a viscosity testing method of directly introducing high-pressure gas is adopted: The first step: Check and close all valves, and connect the end of the first intake pipeline 19 to the gas source. In the second step, close the first pressure relief valve 27, the second pressure relief valve 29 and the drain valve 7, and open the intake valve 20, the first port and the second port of the first four-way valve 10, and the first port and the second port of the second four-way valve 11. Gas enters the rodless cavity of the first cylinder 3, the buffer gas tank 12, the capillary tube 2 and the rodless cavity of the second cylinder 4; Open the drain valve 7, and drive the piston rod of the first cylinder 3 and the piston rod of the second cylinder 4 to move synchronously to the left or synchronously to the right by the drive motor 35 to discharge the impurity gas in the test pipeline and the cylinder; In the third step, after the impurity gas is emptied, close the drain valve 7, open the thermostat 30 and the temperature controller 31 to make the temperature in the box body 1 reach the test temperature and remain constant, and close the intake valve 20; In the fourth step, set the rotation speed of the drive motor 35. The drive motor 35 makes the lead screw 34 move to the right or to the left at a set speed V. When the lead screw 34 moves to the right, the second cylinder 4 slowly exhausts gas, and at the same time the first cylinder 3 slowly inhales gas; when the lead screw 34 moves to the left, the first cylinder 3 slowly exhausts gas, and at the same time the second cylinder 4 slowly inhales gas to reach a quasi-steady state; in this way, during the test, the gas volume in the test pipeline remains unchanged and the state remains unchanged; In the fifth step, record the differential pressure gauge 9 reading ΔP on both sides of the capillary tube 2, and calculate the flow rate Q = VA according to the piston movement speed, that is, the set speed V of the lead screw 34 and the cross-sectional area A of the first cylinder 3; In the sixth step, calculate the gas viscosity corresponding to the flow rate in the fifth step according to the Hagen-Poiseuille formula; In the seventh step, change the rotation speed of the drive motor 35, thereby changing the set speed of the lead screw 34, and repeat steps four to six to measure multiple groups of gas viscosities; In the eighth step, compare and analyze multiple groups of test results to obtain an accurate gas viscosity value; In the ninth step, after the test is completed, turn off the drive motor 35 and open the drain valve 7 to release the gas.

[0054] Example seven: As shown in the appendix Figure 1 The test method for the gas viscosity under multiple working conditions includes the following steps: In the first step, connect the end of the first intake pipeline 19 to the gas source; In the second step, close the first pressure relief valve 27, the second pressure relief valve 29 and the drain valve 7, and open the intake valve 20, the first port and the third port of the first four-way valve 10, and the first port and the third port of the second four-way valve 11. Gas enters the rodless cavity of the first cylinder 3, the buffer gas tank 12, the capillary tube 2 and the rodless cavity of the second cylinder 4; Start the drive motor 35, and the drive motor 35 drives the piston rods of the first cylinder 3 and the second cylinder 4 to reciprocate left and right. The rodless chambers of the first cylinder 3 and the second cylinder 4 inhale and exhale periodically, so that the gas pressure in the first test pipeline is greater than the target value; Open the evacuation valve 7, and the drive motor 35 drives the piston rods of the first cylinder 3 and the second cylinder 4 to move synchronously to the left or synchronously to the right; Step 3: Close the evacuation valve 7, turn on the thermostat 30 and the temperature controller 31, so that the temperature in the box 1 reaches the test temperature and remains constant, and close the intake valve 20; Step 4: Make the pressure in the buffer gas tank 12 reach the target value, and the drive motor 35 makes the lead screw 34 move to the right or to the left at a set speed V; Step 5: Record the differential pressure gauge 9 reading ΔP on both sides of the capillary 2, and calculate the flow rate Q = VA according to the set speed V and the cross-sectional area A of the first cylinder 3; Step 6: Calculate the gas viscosity μ according to the following formula where is the radius of the capillary 2, is the length of the capillary 2, is the pressure difference, is the volume flow rate; Step 7: Change the set speed of the lead screw 34, and repeat Steps 4 to 6 to measure multiple sets of gas viscosities; Step 8: Compare and analyze multiple sets of test results to obtain an accurate gas viscosity value.

[0055] In this embodiment, the gas source is for the high-pressure gas viscosity test of the low-pressure mixed gas, and the method of first pressurizing and then performing the viscosity test is adopted: The first step is to check and close all valves, and connect the end of the first intake pipeline 19 to the gas source; Step 2: Close the first pressure relief valve 27, the second pressure relief valve 29, and the drain valve 7. Open the intake valve 20, the first port and the second port of the first four-way valve 10, and the first port and the second port of the second four-way valve 11. Start the drive motor 35. The drive motor 35 drives the piston rods of the first cylinder 3 and the second cylinder 4 to reciprocate left and right through the lead screw 34. When the lead screw 34 moves to the right, the second cylinder 4 slowly exhausts air, and at the same time, the first cylinder 3 slowly inhales air; when the lead screw 34 moves to the left, the first cylinder 3 slowly exhausts air, and at the same time, the second cylinder 4 slowly inhales air. The lead screw 34 reciprocates, and the first cylinder 3 and the second cylinder 4 continuously inhale air from the air source, inflate and pressurize the buffer gas tank 12 and the capillary 2, so that the gas pressure is slightly higher than the test pressure; the two cylinders inhale and exhaust air periodically, pre-pressurizing the gas in the test pipeline. During this process, the gas enters the rodless cavity of the first cylinder 3 through the first intake check valve 23, or enters the rodless cavity of the second cylinder 4 through the second intake check valve 25. Then, after the pistons of the two cylinders move in the opposite direction, the gas in the rodless cavity is compressed. The gas in the rodless cavity respectively enters the rodless cavity of the first cylinder 3, the buffer gas tank 12, the capillary 2, and the rodless cavity of the second cylinder 4 through the first exhaust check valve 15 and the second exhaust check valve 18; Open the drain valve 7. The drive motor 35 drives the piston rods of the first cylinder 3 and the second cylinder 4 to move synchronously to the left or synchronously to the right to discharge the impurity gas in the test pipeline and the cylinders; Step 3: After the impurity gas is emptied, close the drain valve 7. Open the thermostat 30 and the temperature controller 31 to make the temperature in the box 1 reach the test temperature and remain constant. Close the intake valve 20; Step 4: Open the first port and the second port of the first four-way valve 10, and at the same time open the first port and the second port of the second four-way valve 11. At this time, the rodless cavities of the first cylinder 3, the buffer gas tank 12, the capillary 2, and the rodless cavity of the second cylinder 4 are connected, and the gas pressures are the same and slightly higher than the test pressure. Slowly open the drain valve 7 to discharge some gas until the value shown on the pressure gauge reaches the test pressure. Then close the drain valve 7. Set the rotation speed of the drive motor 35. The drive motor 35 makes the lead screw 34 move to the right or to the left at the set speed V; Step 5: Record the differential pressure gauge 9 reading ΔP on both sides of the capillary 2. According to the piston movement speed, that is, the set speed V of the lead screw 34 and the cross-sectional area A of the first cylinder 3, calculate the flow rate Q = VA; Step 6: Calculate the gas viscosity corresponding to the flow rate in Step 5 according to the Hagen-Poiseuille formula; Step 7: Change the rotation speed of the drive motor 35, thereby changing the set speed of the lead screw 34. Repeat Steps 4 to 6 to measure multiple groups of gas viscosities; Step 8: Compare and analyze multiple groups of test results to obtain an accurate gas viscosity value; Step 9: After the test is completed, turn off the drive motor 35 and open the drain valve 7 to release the air.

[0056] Example 8: As shown in the appendix Figure 1 The test method for the gas viscosity under multiple working conditions includes the following steps: Step 1: Connect the end of the first intake pipeline 19 to the gas source. Step 2: Close the first pressure relief valve 27, the second pressure relief valve 29, and the drain valve 7, open the intake valve 20, the first port and the third port of the first four-way valve 10, and the first port and the third port of the second four-way valve 11. The gas enters the rodless cavity of the first cylinder 3, the buffer gas tank 12, the capillary tube 2, and the rodless cavity of the second cylinder 4. Open the drain valve 7, and the drive motor 35 drives the piston rods of the first cylinder 3 and the second cylinder 4 to move synchronously to the left or synchronously to the right. Close the intake valve 20, open the first port and the fourth port of the first four-way valve 10, the first port and the fourth port of the second four-way valve 11, the first pressure relief valve 27, and the second pressure relief valve 29. The drive motor 35 drives the piston rods of the first cylinder 3 and the second cylinder 4 to move synchronously to the left or synchronously to the right. The rodless cavities of the first cylinder 3 and the second cylinder 4 suck in gas from the first test pipeline, and the gas is discharged through the first pressure relief pipe 26 and the second pressure relief pipe 28. The pressure of the first test pipeline is greater than the set negative pressure value.

[0057] Step 3: Close the drain valve 7, turn on the thermostat 30 and the temperature controller 31 to make the temperature in the box 1 reach the test temperature and remain constant, and then close the intake valve 20. Step 4: Make the pressure in the buffer gas tank 12 reach the target value, and the drive motor 35 makes the lead screw 34 move to the right or to the left at the set speed V. Step 5: Record the differential pressure gauge 9 reading ΔP on both sides of the capillary tube 2. According to the set speed V and the cross-sectional area A of the first cylinder 3, calculate the flow rate Q = VA. Step 6: Calculate the gas viscosity μ according to the following formula where is the radius of the capillary tube 2, is the length of the capillary tube 2, is the pressure difference, is the volume flow rate; Step 7: Change the set speed of the lead screw 34 and repeat Steps 4 to 6 to measure multiple groups of gas viscosities. Step 8: Compare and analyze multiple groups of test results to obtain an accurate gas viscosity value.

[0058] The gas source in this embodiment is a low-pressure mixed gas. The method of first reducing pressure and then performing viscosity testing is adopted: First step, check and close all valves, and connect the end of the first intake pipeline 19 to the gas source; Second step, close the first pressure relief valve 27, the second pressure relief valve 29, and the drain valve 7. Open the intake valve 20, the first port and the third port of the first four-way valve 10, and the first port and the third port of the second four-way valve 11. The gas enters the rodless cavity of the first cylinder 3, the buffer tank, the capillary 2, and the rodless cavity of the second cylinder 4; Start the drive motor 35. The lead screw 34 drives the two cylinder pistons to reciprocate left and right. The two cylinders inhale and exhale periodically, pre-pressurizing the gas in the test pipeline. During this process, the gas enters the rodless cavity of the first cylinder 3 through the first intake check valve 23, or enters the rodless cavity of the second cylinder 4 through the second intake check valve 25. Then, after the two cylinder pistons reciprocate, the gas in the rodless cavity is compressed. After the gas in the rodless cavity is compressed and pressurized, it enters the rodless cavity of the first cylinder 3, the buffer gas tank 12, the capillary 2, and the rodless cavity of the second cylinder 4 through the first exhaust check valve 15 and the second exhaust check valve 18 respectively. Close the intake valve 20. Open the first port and the fourth port of the first four-way valve 10, the first port and the fourth port of the second four-way valve 11, the first pressure relief valve 27, and the second pressure relief valve 29. The drive motor 35 drives the piston rod of the first cylinder 3 and the piston rod of the second cylinder 4 to move synchronously to the left or synchronously to the right. The rodless cavity of the first cylinder 3 and the rodless cavity of the second cylinder 4 inhale gas from the first test pipeline 5, and discharge the gas through the first pressure relief pipe 26 and the second pressure relief pipe 28, finally making the pressure in the first test pipeline 5 greater than the set negative pressure value; Open the drain valve 7. The drive motor 35 drives the piston rod of the first cylinder 3 and the piston rod of the second cylinder 4 to move synchronously to the left or synchronously to the right, discharging the impurity gas in the test pipeline and the cylinders; Third step, after discharging the impurity gas, close the drain valve 7, open the thermostat 30 and the temperature controller 31, making the temperature in the box body 1 reach the test temperature and remain constant, and close the intake valve 20; Fourth step, open the first port and the fourth port of the first four-way valve 10, the first port and the fourth port of the second four-way valve 11, the first pressure relief valve 27, and the second pressure relief valve 29. The drive motor 35 drives the piston rod of the first cylinder 3 and the piston rod of the second cylinder 4 to move synchronously to the left or synchronously to the right. The rodless cavity of the first cylinder 3 and the rodless cavity of the second cylinder 4 inhale gas from the first test pipeline 5, and discharge the gas through the first pressure relief pipe 26 and the second pressure relief pipe 28. The pressure in the first test pipeline 5 decreases until it reaches the set negative pressure value; Set the rotation speed of the drive motor 35. The drive motor 35 makes the lead screw 34 move to the right or to the left at the set speed V; Step 5: Record the differential pressure gauge reading ΔP on both sides of the capillary 2, and calculate the flow rate Q = VA according to the piston moving speed, i.e., the set speed V of the lead screw 34 and the cross-sectional area A of the first cylinder 3; Step 6: Calculate the gas viscosity corresponding to the flow rate in Step 5 according to the Hagen-Poiseuille formula; Step 7: Change the rotation speed of the drive motor 35, thereby changing the set speed of the lead screw 34, and repeat Steps 4 to 6 to measure multiple sets of gas viscosities; Step 8: Compare and analyze multiple sets of test results to obtain an accurate gas viscosity value; Step 9: After the test is completed, turn off the drive motor 35 and open the exhaust valve 7 to release the gas.

[0059] The above technical features respectively constitute the embodiments of the present invention, which have strong adaptability and the best implementation effects. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A test device applicable to gas viscosities under multiple working conditions, characterized in that It includes an incubator, a capillary tube, a driving mechanism, and a first air cylinder and a second air cylinder with the same structure and arranged back to back. A driving mechanism is provided between the right end of the piston rod of the first air cylinder and the left end of the piston rod of the second air cylinder. The driving mechanism enables the piston rods of the first air cylinder and the second air cylinder to move synchronously and in the same direction. The first air cylinder is provided with a first air inlet and a first air outlet that are internally and externally connected at intervals. Both the first air inlet and the first air outlet are communicated with the rodless cavity of the first air cylinder. The second air cylinder is provided with a second air inlet and a second air outlet that are internally and externally connected at intervals. Both the second air inlet and the second air outlet are communicated with the rodless cavity of the second air cylinder. A capillary tube is provided in the incubator. A first test pipeline is fixedly communicated between the first end of the capillary tube and the first air outlet. An evacuation pipeline is fixedly communicated with the first test pipeline. An evacuation valve is installed on the evacuation pipeline. A second test pipeline is fixedly communicated between the second end of the capillary tube and the second air outlet. A differential pressure gauge is provided between the first end and the second end of the capillary tube.

2. The test device for gas viscosity applicable to multiple working conditions according to claim 1, wherein It further includes a first four-way valve and a second four-way valve. A buffer air tank is provided in the incubator. The air outlet of the buffer air tank is fixedly communicated with the first end of the capillary tube. The first test pipeline is fixedly communicated between the air inlet of the buffer air tank and the first port of the first four-way valve. A third test pipeline is fixedly communicated between the second port of the first four-way valve and the first air outlet. A fourth test pipeline is fixedly communicated between the third port of the first four-way valve and the third test pipeline. A first exhaust check valve is installed on the fourth test pipeline. The second test pipeline is fixedly communicated between the second end of the capillary tube and the first port of the second four-way valve. A fifth test pipeline is fixedly communicated between the second port of the second four-way valve and the second air outlet. A sixth test pipeline is fixedly communicated between the third port of the second four-way valve and the fifth test pipeline. A second exhaust check valve is installed on the sixth test pipeline. The fourth port of the first four-way valve is fixedly communicated with a first air inlet pipeline. An air inlet valve is installed on the first air inlet pipeline. A second air inlet pipeline is fixedly communicated between the first air inlet pipeline at the position corresponding to between the air inlet valve and the first four-way valve and the fourth port of the second four-way valve. A third air inlet pipeline is fixedly communicated between the first air inlet pipeline at the position corresponding to between the second air inlet pipeline and the first four-way valve and the first air inlet. A first air inlet check valve is installed on the third air inlet pipeline. A fourth air inlet pipeline is fixedly communicated between the second air inlet pipeline and the second air inlet. A second air inlet check valve is installed on the fourth air inlet pipeline.

3. The test device for gas viscosity applicable to multiple working conditions according to claim 2, characterized in that A first pressure relief pipe is fixedly communicated with the fourth test pipeline at the position corresponding to between the first exhaust check valve and the first four-way valve. A first pressure relief valve is installed on the first pressure relief pipe. A second pressure relief pipe is fixedly communicated with the sixth test pipeline at the position corresponding to between the second exhaust check valve and the second four-way valve. A second pressure relief valve is installed on the second pressure relief pipe.

4. The test device for gas viscosity applicable to multiple working conditions according to claim 1 or 2 or 3, characterized in that The incubator includes a thermostat, a temperature controller, and a box body. The buffer air tank, the capillary tube, and the thermostat are fixedly installed in the box body at intervals. A temperature sensor is provided in the box body. Both the temperature sensor and the thermostat are connected to the temperature controller. Heat insulation layers are provided on the outer side of the box body, the outer side of the first air cylinder, and the outer side of the second air cylinder.

5. The test device for gas viscosity applicable to multiple working conditions according to claim 1 or 2 or 3, characterized in that The driving mechanism includes a driving motor and a lead screw. The output shaft of the driving motor is connected to the middle part of the lead screw in a transmission manner. The two ends of the lead screw are respectively detachably and fixedly installed with the right end of the piston rod of the first cylinder and the left end of the piston rod of the second cylinder.

6. The test device for gas viscosity applicable to multiple working conditions according to claim 4, characterized in that The driving mechanism includes a driving motor and a lead screw. The output shaft of the driving motor is connected to the middle part of the lead screw in a transmission manner. The two ends of the lead screw are respectively detachably and fixedly installed with the right end of the piston rod of the first cylinder and the left end of the piston rod of the second cylinder.

7. A method for testing the viscosity of a multi-condition gas using a test device for the viscosity of a multi-condition gas as described in any one of claims 4 to 6, characterized in that It includes the following steps: Step 1: Connect the end of the first intake pipeline to the gas source. Step 2: Close the first pressure relief valve, the second pressure relief valve and the drain valve, open the intake valve, control the first four-way valve and the second four-way valve, and the gas enters the rodless cavity of the first cylinder, the buffer gas tank, the capillary tube and the rodless cavity of the second cylinder; open the drain valve, so that the driving mechanism drives the piston rods of the first cylinder and the second cylinder to move synchronously to the left or synchronously to the right. Step 3: Close the drain valve, open the thermostat and the temperature controller, so that the temperature in the box reaches the test temperature and remains constant, and close the intake valve. Step 4: Make the pressure in the buffer gas tank reach the target value, and the driving motor makes the lead screw move to the right or to the left at the set speed V. Step 5: Record the differential pressure gauge reading ΔP on both sides of the capillary tube, and calculate the flow rate Q = VA according to the set speed V and the cross-sectional area A of the first cylinder. Step 6: Calculate the gas viscosity μ according to the following formula wherein is the capillary radius, is the capillary length, is the pressure difference, is the volumetric flow rate; Step 7: Change the set speed of the lead screw, repeat Steps 4 to 6, and measure multiple groups of gas viscosities. Step 8: Compare and analyze multiple groups of test results to obtain an accurate gas viscosity value.

8. The test method for gas viscosity under multiple working conditions according to claim 7, wherein Specifically, Step 2 is: close the first pressure relief valve, the second pressure relief valve and the drain valve, open the intake valve, the first port and the second port of the first four-way valve, and the first port and the second port of the second four-way valve, and the gas enters the rodless cavity of the first cylinder, the buffer gas tank, the capillary tube and the rodless cavity of the second cylinder; open the drain valve, and the driving motor drives the piston rods of the first cylinder and the second cylinder to move synchronously to the left or synchronously to the right.

9. The test method for gas viscosity under multiple working conditions according to claim 7, wherein Specifically, Step 2 is: close the first pressure relief valve, the second pressure relief valve and the drain valve, open the intake valve, the first port and the third port of the first four-way valve, and the first port and the third port of the second four-way valve, and the gas enters the rodless cavity of the first cylinder, the buffer gas tank, the capillary tube and the rodless cavity of the second cylinder; start the driving motor, and the driving motor drives the piston rods of the first cylinder and the second cylinder to reciprocate left and right. The rodless cavities of the first cylinder and the second cylinder inhale and exhale periodically, so that the gas pressure in the first test pipeline is greater than the target value; open the drain valve, and the driving motor drives the piston rods of the first cylinder and the second cylinder to move synchronously to the left or synchronously to the right.

10. The method for testing the gas viscosity under multiple working conditions according to claim 7, characterized in that Step 2 specifically includes: closing the first pressure relief valve, the second pressure relief valve and the drain valve, opening the intake valve, the first port and the third port of the first four-way valve, and the first port and the third port of the second four-way valve, so that gas enters the rodless cavity of the first cylinder, the buffer gas tank, the capillary tube and the rodless cavity of the second cylinder; opening the drain valve, and driving the piston rods of the first cylinder and the second cylinder to move synchronously to the left or synchronously to the right by the driving motor; closing the intake valve, opening the first port and the fourth port of the first four-way valve, the first port and the fourth port of the second four-way valve, the first pressure relief valve and the second pressure relief valve, and driving the piston rods of the first cylinder and the second cylinder to move synchronously to the left or synchronously to the right by the driving motor, so that the rodless cavity of the first cylinder and the rodless cavity of the second cylinder suck gas from the first test pipeline, and discharge the gas through the first pressure relief pipe and the second pressure relief pipe, and the pressure of the first test pipeline is greater than the set negative pressure value.

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