Carbon dioxide pressure differential controlled quick switch valve and method

Abstract

This invention relates to the field of fluid control and supercritical fluid technology, specifically to a carbon dioxide differential pressure controlled rapid switching valve and method; it includes a valve body, valve core, ultrasonic transducer array, and pilot drive mechanism; the system utilizes the area difference of the valve core to establish a fluid differential pressure field to maintain self-sealing; its core is to prioritize the activation of the ultrasonic transducer before opening, using acoustic cavitation and suspension effects to vaporize the fluid in the guide gap, forming an air film that puts the valve core in an air-floating state; subsequently, the pilot pressure is released to drive the valve core to eject and open, and the fluid dynamic pressure centering effect generated by the spiral groove maintains precession stability; this invention transforms contact friction into a near-zero friction air-floating state, significantly reducing starting inertia while ensuring high-pressure self-sealing, achieving rapid response and extending equipment life.

Description

Technical Field

[0001] This invention relates to the field of fluid control and supercritical fluid technology, specifically to a carbon dioxide differential pressure control type fast switching valve and method. Background Technology

[0002] In supercritical fluid extraction and high-pressure fluid control applications, control valves need to frequently perform rapid opening and closing actions in a high-pressure carbon dioxide environment to maintain the stability of the system's process parameters. The medium is usually in a supercritical fluid state and accompanied by complex phase change processes.

[0003] For fluid control in such operating conditions, existing solutions generally employ traditional mechanical contact sealing structures combined with electromagnetic or pneumatic drive mechanisms. High-pressure sealing performance under static conditions is ensured by applying high-intensity contact specific pressure, and the control logic largely relies on open-loop drive from external commands. While this solution has some applicability in conventional fluid control, the significant Joule-Thomson effect during the throttling process of carbon dioxide media easily leads to a drastic temperature drop at the valve port, inducing dry ice accumulation and causing the valve core to freeze and seize. At the same time, there is an inherent contradiction between the large contact force required for high-pressure sealing and the low friction force required for rapid response. Traditional contact friction mode results in large starting inertia and severe wear on the sealing surface. Furthermore, in the extreme flow channel environment of cryogenic high pressure, it is difficult to directly implant sensors for real-time monitoring, resulting in the inability to detect the internal phase change blockage rate and motion attitude, causing system response lag and inability to effectively compensate for operating condition disturbances.

[0004] Therefore, how to resolve the contradiction between high-pressure sealing and rapid response, eliminate icing failures caused by medium phase change, and achieve precise closed-loop control of valve core movement and flow characteristics in the absence of internal sensors has become an urgent technical problem to be solved. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a carbon dioxide differential pressure controlled fast switching valve and method, which can solve the technical problems existing in the prior art. Specifically, the technical solution of this invention is as follows:

[0006] A method for a carbon dioxide differential pressure controlled quick-opening valve includes:

[0007] S1. A valve body, valve core, ultrasonic transducer array, and pilot drive mechanism are configured, wherein the valve core is slidably disposed inside the configured valve body, the valve core is constructed as a differential pressure piston structure, the valve core is provided with a tangential non-through spiral groove in the circumferential direction, an annular reflux cavity is provided on the inner wall of the configured valve body corresponding to the position of the tangential non-through spiral groove, and the ultrasonic transducer array is arranged around the guide sleeve inside the configured valve body.

[0008] S2. Introduce supercritical carbon dioxide fluid into the configured valve body, and use the area difference between the upper and lower surfaces of the valve core to generate a fluid pressure differential field, and use the fluid pressure differential field to maintain the self-sealing closed state of the valve core.

[0009] S3. Upon receiving the opening command, the ultrasonic transducer array is activated first, generating acoustic cavitation heat effect and acoustic suspension effect in the guide gap between the valve core and the guide sleeve, converting the supercritical carbon dioxide fluid in the guide gap into a low-density gaseous fluid or a supercritical gaseous medium, and forming an air film on the surface of the valve core, so that the valve core is in an air-floating state.

[0010] S4. Control the pilot drive mechanism to release the pilot pressure, and drive the valve core in the air-float state to open under the action of the fluid pressure difference field. The fluid enters the tangential non-through spiral groove to form a high-speed vortex ring, generating a fluid dynamic pressure centering effect and a dynamic pressure squeezing film effect to maintain the axial precession stability of the valve core.

[0011] S5. Monitor and extract the characteristics of the drive signal and the pressure waveform in real time, and adjust the intensity of the ultrasonic transducer array or the control parameters of the pilot drive mechanism according to the characteristics of the drive signal and the pressure waveform to complete the switching action cycle.

[0012] Preferably, before step S1, the following steps are included: S1.1, constructing a flow-electric-thermal impedance mapping model, taking the phase change critical blocking rate at the valve port and the valve core air float gap eccentricity as implicit physical parameters, and taking the high-frequency harmonic component of the drive coil current and the attenuation rate of the pressure waveform after the valve as measurable signals, and constructing a variable stiffness compensation model.

[0013] Preferably, in step S5, the specific logic of the feature feedback adjustment includes: collecting the pressure step response time at the moment the valve opens and the slope of the pressure decay curve at the moment the valve closes; when the pressure step response time is prolonged and low-frequency high-amplitude oscillations occur in the high-frequency harmonic components of the current, it is determined to be the initial stage of dry ice sticking, and the power and frequency of the ultrasonic transducer array are increased; when the slope of the pressure decay curve becomes slower and is accompanied by a high-frequency whistling signal, it is determined to be a micro-leakage or wear of the sealing surface, and the pulse width duty cycle of the pilot drive mechanism is adjusted to perform differential pressure fine-tuning compensation.

[0014] Preferably, step S3 includes: activating the ultrasonic transducer array within a preset microsecond time before the valve core opens; reducing the viscosity of the medium in the guide gap using the acoustic cavitation heat effect and preventing dry ice particles from adhering; and using the acoustic levitation effect to generate radiation force to separate the valve core from the inner wall of the guide sleeve.

[0015] Preferably, in step S4, the specific mechanism of the dynamic pressure squeezing film effect is as follows: when the valve core is deflected by a lateral force, the fluid velocity in the tangential non-through spiral groove on the side with smaller gap increases; the pumping action of the tangential non-through spiral groove causes the local pressure on the side with smaller gap to rise, generating a reverse thrust to push the valve core back to the center position.

[0016] Preferably, in step S2, the pressure of the supercritical carbon dioxide fluid is set to be greater than 7.38 MPa.

[0017] Preferably, the pilot drive mechanism is an electromagnetic pilot valve, and the monitoring object in step S5 is the current of the electromagnetic pilot valve drive coil.

[0018] Preferably, in step S3, the gaseous medium or the supercritical gaseous medium is used as a low-viscosity lubricating layer to change the friction mode between the valve core and the guide sleeve from fluid lubrication or solid particle abrasive wear to gas film lubrication.

[0019] A carbon dioxide differential pressure controlled quick-on / off valve includes:

[0020] The system includes a valve body with a guide sleeve and an annular reflux cavity inside; a valve core slidably disposed within the guide sleeve, the valve core being a differential pressure piston structure, with tangential non-through spiral grooves on its circumferential surface, the positions of which correspond to the annular reflux cavity; an ultrasonic transducer array arranged around the outer periphery of the guide sleeve, used to apply an acoustic cavitation heat field and an acoustic levitation force field to the gap between the valve core and the guide sleeve; and a pilot drive mechanism connected to the valve body, used to control the fluid pressure differential acting on the valve core.

[0021] Preferably, the switching valve further includes a control unit, which is connected to the ultrasonic transducer array and the pilot drive mechanism. The control unit is equipped with a current detection module and a pressure signal processing module for performing closed-loop control based on the current-electric-thermal impedance mapping model.

[0022] Compared with the prior art, the present invention has the following improvements and advantages:

[0023] 1. This invention utilizes the acoustic cavitation heat effect and acoustic levitation effect to instantly convert the supercritical fluid in the guide gap into a gaseous or gas-like medium before opening, forming a high-heat-energy gas film on the valve core surface. This mechanism changes the friction mode between the valve core and the guide sleeve from traditional contact friction or fluid lubrication to a near-zero friction air-float state. While ensuring self-sealing using the high-pressure characteristics of the fluid under static conditions, it significantly reduces the starting inertia and frictional resistance, thereby achieving rapid ejection opening and avoiding abrasive wear of key moving parts, thus extending the service life of the equipment.

[0024] 2. This invention utilizes the acoustic cavitation heat effect generated by ultrasonic waves propagating in a medium to rapidly raise the local temperature within the guide gap to above the quasi-critical temperature; that is, the isobaric specific heat capacity. Reaching the peak temperature point; this active thermal intervention mechanism not only significantly reduces the viscosity of the medium, but also effectively prevents dry ice particles from adhering and accumulating on the guide surface, fundamentally eliminating the potential fault of valve core jamming due to low temperature freezing, and ensuring the stable operation of the valve under supercritical fluid phase change and cryogenic conditions.

[0025] 3. This invention utilizes the cooperation between the tangential non-through spiral groove in the circumferential direction of the valve core and the annular reflux cavity on the inner wall of the valve body to force the formation of a high-speed vortex ring when the fluid flows through at high speed. The resulting hydrodynamic centering effect maintains the axial precession stability of the valve core, while the hydrodynamic pressure film effect generates a reverse thrust to push the valve core back to its center position when it is deflected by lateral force. This self-healing mechanism, which requires no external sensors, effectively resists fluid pulsation disturbances and ensures the stability of the valve core's high-frequency switching motion within a micrometer-level gap.

[0026] 4. This invention establishes a flow-electric-thermal impedance mapping model, which maps the difficult-to-measure valve port phase change blockage rate and valve core air flotation eccentricity to the high-frequency harmonic components of the drive coil current and the waveform characteristics of the downstream pressure, which can be monitored externally. By monitoring these signal characteristics, the system can accurately identify different failure modes such as the initial stage of dry ice sticking and micro-leakage of the sealing surface, and adjust the ultrasonic transducer intensity or pilot drive parameters accordingly. This method solves the blind zone problem of internal state perception of cryogenic high-pressure flow channels, and realizes precise compensation and intelligent control of valve core motion posture and flow channel characteristics. Attached Figure Description

[0027] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0028] Figure 1 This is a schematic diagram of the overall external structure of the device;

[0029] Figure 2 This is a structural diagram of the valve core and guide sleeve;

[0030] Figure 3 This is a flowchart of the method of the present invention.

[0031] In the figure: 100, valve body configuration; 110, annular reflux chamber; 120, inner wall of valve body; 200, valve core; 210, tangential non-through spiral groove; 220, differential pressure piston structure; 300, guide sleeve; 310, guide clearance; 400, ultrasonic transducer array; 500, pilot drive mechanism. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0033] Example 1:

[0034] Please see Figures 1-3 A method for a carbon dioxide differential pressure controlled fast-on / off valve, comprising:

[0035] S1. The valve body 100, valve core 200, ultrasonic transducer array 400 and pilot drive mechanism 500 are configured. The valve core 200 is slidably disposed inside the valve body 100. The valve core 200 is constructed as a differential pressure piston structure 220. The valve core 200 is provided with a tangential non-through spiral groove 210 in the circumferential direction. The valve inner wall 120 of the valve body 100 is provided with an annular reflux cavity 110 corresponding to the position of the tangential non-through spiral groove 210. The ultrasonic transducer array 400 is arranged around the guide sleeve 300 inside the valve body 100.

[0036] S2. Supercritical carbon dioxide fluid is introduced into the valve body 100, and a fluid pressure differential field is generated by the difference in surface area between the upper and lower surfaces of the valve core 200. The fluid pressure differential field is used to maintain the self-sealing closed state of the valve core 200.

[0037] S3. Upon receiving the opening command, the ultrasonic transducer array 400 is activated first, generating acoustic cavitation heat effect and acoustic suspension effect in the guide gap 310 between the valve core 200 and the guide sleeve 300. This transforms the supercritical carbon dioxide fluid in the guide gap 310 into a low-density gaseous fluid or a supercritical gaseous medium, and forms an air film on the surface of the valve core 200, putting the valve core 200 in an air-floating state.

[0038] S4. Control the pilot drive mechanism 500 to release the pilot pressure, and drive the valve core 200 in the air-float state to open under the action of the fluid pressure difference field. In this process, the fluid enters the tangential non-through spiral groove 210 to form a high-speed vortex ring, which generates a fluid dynamic pressure centering effect and a dynamic pressure squeezing film effect to maintain the axial precession stability of the valve core 200.

[0039] S5. Monitor and extract drive signal characteristics and pressure waveform characteristics in real time, and adjust the intensity of ultrasonic transducer array 400 or the control parameters of pilot drive mechanism 500 according to the drive signal characteristics and pressure waveform characteristics to complete the switching action cycle.

[0040] This embodiment provides a method for a carbon dioxide differential pressure controlled fast-acting valve, aiming to solve the contradiction between valve core 200 freezing and jamming due to the Joule-Thomson effect and high-pressure sealing and fast response during supercritical fluid extraction. The method is configured with a hardware system including a valve body 100, valve core 200, ultrasonic transducer array 400 and pilot drive mechanism 500. The valve core 200 is constructed as a differential pressure-bearing piston structure 220. The tangential non-through spiral groove 210 set in the circumferential direction of the valve core 200 cooperates with the annular reflux cavity 110 of the inner wall of the valve body 120 to construct a fluid dynamic self-stabilizing structure.

[0041] During operation, the system introduces supercritical carbon dioxide fluid into the valve body 100 and generates a fluid pressure differential field by utilizing the area difference between the upper and lower surfaces of the valve core 200. This fluid pressure differential field acts directly on the valve core 200 and uses the high pressure characteristics of the fluid itself to maintain the valve core 200 in a self-sealing closed state, thus ensuring high pressure sealing performance without additional energy consumption under static conditions.

[0042] When the system receives an activation command, the control logic prioritizes activating the ultrasonic transducer array 400 arranged around the guide sleeve 300, within a preset short window before the physical action of the valve core 200 occurs, i.e., the set ultrasonic pre-excitation time. Inside, high-frequency microbubble nucleation is induced within the guide gap 310 between the valve core 200 and the guide sleeve 300, at which point the driving power... Set as The power density setpoint is calculated based on the theoretical critical cavitation threshold of carbon dioxide in this temperature range from the NIST database, ensuring that the sound pressure amplitude exceeds the tensile strength of the medium; and the power density is not lower than... ; This forces the supercritical carbon dioxide fluid in the guide gap 310 to undergo a local phase transition, transforming it into a gaseous medium or a supercritical gaseous medium, thereby forming a high-heat-energy gas film on the surface of the valve core 200, causing the valve core 200 to instantly change from a contact friction state to an air-float state.

[0043] The pilot drive mechanism 500 releases pilot pressure, breaking the original force balance. Under the action of the fluid pressure difference field, it drives the valve core 200, which is in an air-floating state, to achieve ejection opening. During this process, the fluid flows at high speed through the tangential non-through spiral groove 210 and is forced to form a high-speed vortex ring. The resulting fluid dynamic pressure centering effect and dynamic pressure squeezing film effect are used to maintain the axial precession stability of the valve core 200 in high-frequency reciprocating motion. The system monitors and extracts the characteristics of the drive signal and pressure waveform in real time. Based on these characteristics, it adjusts the intensity of the ultrasonic transducer array 400 or the control parameters of the pilot drive mechanism 500 to complete one closed-loop switching action cycle.

[0044] Before step S1, the following steps are included: S1.1, constructing a flow-electric-thermal impedance mapping model, taking the phase change critical blocking rate at the valve port and the eccentricity of the 200 air float gap of the valve core as implicit physical parameters, taking the high-frequency harmonic component of the drive coil current and the attenuation rate of the pressure waveform after the valve as measurable signals, and constructing a variable stiffness compensation model.

[0045] This embodiment is a further specification of the steps in constructing the flow-electric-thermal impedance mapping model. When constructing this variable stiffness compensation model, the system sets the physical quantities that are difficult to measure directly, namely the phase change critical blocking rate at the valve port and the eccentricity of the 200 air float gap of the valve core, as implicit physical parameters, and uses the high-frequency harmonic components of the electromagnetic pilot valve drive coil current and the attenuation rate of the pressure waveform after the valve as measurable input signals to the model.

[0046] The construction of this flow-electric-thermal impedance mapping model follows clear functional objectives and physical logic: The model aims to solve the problem of directly implanting sensors into the flow channel under cryogenic high-pressure environments. By establishing a mathematical mapping between externally measurable electrical and pressure signals and the internal implicit physical state, it accurately inverses the microscopic motion posture of the valve core 200 and the phase change blockage of the flow channel. Logically, the model consists of three coupled sub-modules:

[0047] The first part is the electromagnetic impedance calculation module, which receives the high-frequency harmonic components of the drive coil current as input. Using fast Fourier transform and pre-calibrated inductance-displacement characteristic curves, it maps the amplitude changes of specific harmonics to the air gap non-uniformity of the magnetic circuit, thereby calculating the eccentricity of the air float gap of the valve core 200.

[0048] The specific calculation logic of the electromagnetic impedance calculation module is as follows: the instantaneous current value of the drive coil is obtained through the sampling circuit. Extracting specific sub-high frequency harmonic components using Fast Fourier Transform Based on the pre-calibrated reluctance-current mapping table, the equivalent air gap length under the corresponding eccentric state is calculated. Combined with formula We obtain the dimensionless eccentricity, where, This is the maximum design clearance between the valve core 200 and the guide sleeve 300. The equivalent air gap length is monitored in real time. This is the standard initial clearance when the valve core 200 is in the center position.

[0049] The second part is the fluid impedance analysis module, which receives the attenuation rate of the pressure waveform after the valve as input; the critical blockage rate of the phase change. It is dimensionless parameters, This indicates that the flow channel is completely unobstructed. This indicates that the flow channel is completely blocked due to dry ice buildup; the specific quantitative calculation formula is as follows:

[0050] ;

[0051] In the formula: The pressure decay curve is measured in real time by a high-frequency dynamic pressure sensor installed downstream of the valve, in units of... ;

[0052] Theoretical pressure decay curve calculated based on the Span-Wagner equation of state, in units of... The calculation method is as follows: based on the closing time... Valve inlet pressure and temperature Assuming the initial state is a pure gas phase undergoing isentropic expansion, the process is determined by a step size... The iterative calculation yielded the result; during the calculation, the fluid sound velocity... Satisfying the formula:

[0053] ;

[0054] in The entropy value is isentropic. Indicates fluid pressure. Indicates fluid density;

[0055] The moment the shutdown command was received, in units of ; The calculation window time is set to a range that covers the characteristic period of pressure decay. ;

[0056] Flow coefficient correction factor, used to compensate for actual flow deviations caused by flow channel machining roughness and geometric tolerances. It is dimensionless. The introduction of this is to compensate for the nonlinear contribution of supercritical fluid density fluctuations to the pressure response, ensuring... Dimensional consistency and numerical robustness under different inlet pressures; the calibration method for this value is: at room temperature... Inlet pressure Under operating conditions, the actual mass flow rate is measured using a standard orifice plate flow meter. , and theoretically calculated flow The ratio, that is:

[0057] ;

[0058] Typical value range is This value is determined by the ratio of the actual flow rate to the theoretical flow rate measured in a standard orifice plate flow meter calibration experiment at room temperature.

[0059] The third part is the thermal impedance balance module, which combines the implicit physical parameters of the two solutions mentioned above, introduces the calculation of the balance between the cold generated by the Joule-Thomson effect and the heat generated by the ultrasonic thermal effect, and outputs the thermal correction factor.

[0060] Explanation of the physical relationships represented: This model as a whole represents the dynamic coupling mechanism of three factors during the movement of valve core 200: the electromagnetic drive characteristics affected by air gap geometric changes, the fluid resistance affected by medium phase change and icing, and the mating clearance affected by thermal expansion and contraction, all within a microsecond timescale. The system uses the output of this model to correct the stiffness coefficient in the variable stiffness compensation model in real time, in order to predict and compensate for changes in frictional resistance and dry ice accumulation trends during the movement of valve core 200. The corrected stiffness coefficient in the variable stiffness compensation model... Defined as:

[0061] ;

[0062] in, The initial mechanical stiffness of the valve core 200 system, in units of: ; The temperature rise of valve core 200 relative to the initial moment, in units of: It needs to be combined with the thermal correction factor. Normalization is performed to eliminate the nonlinear effects under different inlet pressures; Stiffness temperature sensitivity coefficient, unit: This is used to characterize the linear decay rate of a material's elastic modulus with respect to the thermal field; considering the elastoplastic evolution of materials under supercritical conditions, The values ​​should be strictly based on the experimental data of 316L stainless steel in the cryogenic state, and the values ​​should meet the following requirements. That is, the stiffness weakens with increasing temperature. In this embodiment, using 316L stainless steel, the stiffness temperature sensitivity coefficient is... The typical value range is set as follows to This parameter was obtained by consulting the Cryogenic Materials Mechanics Handbook and correcting it using finite element thermo-mechanical coupling simulation, so as to accurately reflect the change in the motion resistance of the guide pair;

[0063] In this model, the lumped parameter method is used, assuming a uniform temperature distribution in valve core 200 and neglecting axial heat conduction losses; specifically, the thermal correction factor in the flow-electric-thermal impedance mapping model... Defined as the normalized deviation of the instantaneous temperature of valve core 200 from its initial calibration temperature, it is calculated based on the integration of the following energy balance equation. The rate of temperature change of valve core 200 is calculated using the following formula:

[0064] ;

[0065] In the formula, The instantaneous temperature of valve core 200, in units of ; The specific heat capacity at constant volume for valve core 200 material, in units of... Considering the changes in physical properties within the operating temperature range, the average specific heat capacity within this range is taken here. For the 316L stainless steel material selected in this embodiment, the value is [value missing]. ; The mass of the valve core is 200, obtained by weighing using a precision electronic balance, and the unit is . ; Electro-acoustic conversion efficiency, dimensionless, is measured under standard atmospheric pressure. The values ​​were obtained through offline calorimetric calibration under specific environmental conditions, with a typical range of values. ;

[0066] The active power of ultrasonic drive is expressed in units of 1. ; The convective heat transfer coefficient between the outer circumferential surface of valve core 200 and the fluid is equal to the value described below. The unit is ; The heat exchange area of ​​the outer circumference of valve core 200 is given in units of... ; The temperature of the fluid after throttling, in units of This value is determined by the control unit by calling the NISTREFPROP database in memory or the Span-Wagner state equation interface, based on the real-time monitored downstream valve pressure. And the isenthalpic process is assumed to be obtained through querying; The natural convection heat transfer coefficient of the outer wall of valve body 100 to the environment is specified in units of... ; To configure the heat dissipation area of ​​the valve body's outer wall 100, the unit is... ; The external ambient temperature is used to calculate the natural convection heat loss of the valve body 100 facing the atmosphere or cooling medium, and is a necessary boundary condition to maintain the accuracy of the overall energy balance integral of the valve core 200.

[0067] Then calculate the 200°C temperature rise value of the valve core. :

[0068] ;

[0069] Here The calculations follow the aforementioned energy balance equations and will not be repeated here; in the equations, Specifically refers to the ambient air temperature outside the valve body 100 or the temperature of the cooling medium surrounding the valve body 100; The dead zone volume after the valve is obtained by filling the closed chamber after the valve with a known mass of gas and measuring the pressure rise curve.

[0070] Among them, leakage mass flow rate ,unit: Based on the slope of the pressure decay curve detected in the previous cycle, the following mass conservation differential equation is used for inversion calculation:

[0071] ;

[0072] in, This refers to the dead zone volume after the valve, in units of... It is pre-calibrated by filling a known mass of gas into the closed chamber after the valve and measuring the pressure rise curve. It is the carbon dioxide compressibility factor; Let be the gas constant for carbon dioxide, and take the value of . ; Pressure decay rate, in units of ;

[0073] convective heat transfer coefficient ,unit: Based on real-time calculations using the modified Dittus-Boelter correlation for helical groove channels, the following results were obtained:

[0074] ;

[0075] All physical parameters in the formula are obtained from a property library based on the bulk fluid temperature: The thermal conductivity of carbon dioxide fluid, in units of . ;

[0076] The hydraulic diameter of the spiral groove, in units of... The calculation formula is the wetted perimeter of the flow channel cross-sectional area:

[0077] ;

[0078] in The cross-sectional area of ​​the flow channel. For wet period;

[0079] The Reynolds number is defined as:

[0080] ;

[0081] in, fluid density ( ), The average flow velocity of the fluid ( ), The hydraulic diameter of the spiral groove flow channel on the 200mm circumferential surface of the valve core is used to characterize a characteristic dimension in a non-circular cross-section flow channel. Dynamic viscosity ( );

[0082] Prandtl number, dimensionless;

[0083] The average radius of curvature of the spiral groove, in units of ;

[0084] The centrifugal force enhancement factor constant is used to characterize the enhancing effect of secondary flow caused by helical flow on boundary layer heat transfer; under the geometry of this embodiment, its value was determined by CFD simulation fitting. ;

[0085] Valve core 200 air float gap eccentricity High-frequency harmonic components of the drive coil current The mapping relationship is represented as:

[0086] ;

[0087] in, The fundamental effective value of the driving coil current, in units of: ; The selected effective value of a specific sub-high frequency harmonic current, in units of: ; The phase difference between the high-frequency harmonic current component and the fundamental driving voltage, in units of: ; This is the magnetoresistive sensitivity coefficient, in units of: The gain effect of air gap reluctance variation on current amplitude ratio is determined by the number of coil turns and magnetic permeability. Phase coupling coefficient, unit: , representing the weight of the effect of eddy current loss on phase hysteresis; and All constants were obtained through finite element electromagnetic simulation combined with experimental pre-calibration. During the experiment, the coil temperature was kept constant, and the eccentric position of the valve core 200° was changed using a precision displacement stage. Multiple sets of data were recorded. and The data is solved by least squares fitting. For the selected specific sub-high frequency harmonic current effective value, in this embodiment, the 3rd or 5th harmonic component that is most sensitive to air gap changes is selected;

[0088] The experimental pre-calibration method is as follows:

[0089] Sound-to-electric conversion efficiency Calibration: The ultrasonic transducer is immersed in an insulated container using the calorimetric method. The rate of temperature rise of the fluid per unit time is measured, and the ratio of the actual power dissipated as heat energy to the input electrical power is calculated.

[0090] magnetoresistive sensitivity coefficient With phase coupling coefficient Calibration: A laser displacement sensor was used to monitor the 200° micro-displacement of the valve core, and an LCR impedance analyzer was used to record different degrees of eccentricity. Lower coil inductance and phase angle , defined as the phase difference between the fundamental wave of the driving voltage and the fundamental wave of the current, is obtained by fitting the above formula using the least squares method;

[0091] In step S5, the specific logic for feature feedback adjustment includes:

[0092] Collect the pressure step response time at the moment the valve opens and the slope of the pressure decay curve at the moment the valve closes;

[0093] When the pressure step response time is prolonged and low-frequency high-amplitude oscillations appear in the high-frequency harmonic components of the current, it is determined to be the initial stage of dry ice viscosity, and the power and frequency of the ultrasonic transducer array are increased by 400.

[0094] When the slope of the pressure decay curve becomes slower and is accompanied by a high-frequency whistling signal, it is determined that there is a micro-leakage or wear on the sealing surface. The pilot drive mechanism is adjusted to a 500 pulse width duty cycle to perform differential pressure fine-tuning compensation.

[0095] This embodiment is a further specification of the specific logic of feature feedback adjustment; the adjustment logic aims to dynamically adjust the physical field parameters according to the real-time operating conditions in order to cope with two completely different failure modes: dry ice stickiness and seal wear; the system collects the pressure step response time at the moment the valve is opened and the slope of the pressure decay curve at the moment the valve is closed in real time, and makes judgments based on preset logic thresholds.

[0096] The pressure step response time is defined as the time required from the issuance of the opening command to the downstream pressure reaching 90% of the target pressure. The system compares this with a preset health baseline response time, such as 3 based on statistics from a large number of normal switching cycles. Compare with the upper limit of the confidence interval or 1.2 times the initial system calibration value;

[0097] The slope of the pressure decay curve is defined as the pressure within a preset time window after the valve closing command is issued, such as... The system compares the rate of internal pressure decrease with the minimum seal decay rate threshold. Comparison; among which Set according to the system's maximum allowable leakage, for example, set to... When the calculated real-time slope absolute value When the attenuation rate is negative, it indicates a leak.

[0098] The specific adjustment logic is as follows: when the real-time calculated pressure step response time is detected... Response time exceeding health baseline Health baseline response time Should be based on current inlet pressure The speed of sound Dynamic calibration, satisfying ,Right now:

[0099] ;

[0100] Furthermore, low-frequency, high-amplitude oscillations occur alongside the high-frequency harmonic components of the current, i.e. An amplitude exceeding the fundamental frequency amplitude occurs within the frequency band. When the oscillation component is detected, the system determines that the flow channel is in the initial stage of dry ice viscosity; at this time, the damping increases, and the system immediately increases the power and frequency of the ultrasonic transducer array 400, with a power increase step size of [missing value]. The frequency scanning range is expanded. The enhanced acoustic cavitation heat effect is used to sublimate or pulverize dry ice, and the upper limit of the power increase is set to the rated power. To prevent transducer damage from prolonged overload; if the pressure step response time is after three consecutive power increases. Still not back to healthy benchmarks If the mechanical structure is forcibly jammed within the specified range, the system will trigger an emergency stop and output an alarm signal.

[0101] In the shutdown state, the control unit automatically executes the heat dissipation procedure: activating the ultrasonic transducer array 400 for a full-power frequency sweep, within a frequency range... The residual dry ice on the sealing surface is peeled off by micro-jet generated by acoustic cavitation effect; the pilot drive mechanism 500 performs 3-5 small pulse width impact opening actions, and the flow channel is self-cleaned by the mechanical impact force of high pressure carbon dioxide fluid.

[0102] Conversely, when the slope of the pressure decay curve calculated in real time is monitored... Less than the minimum sealing attenuation rate threshold The attenuation rate is negative, that is:

[0103] ;

[0104] The absolute values ​​compared here represent the rate of leakage, and are accompanied by a high-frequency whistling signal; that is, the high-frequency whistling signal specifically refers to a frequency within... Within range and the sound intensity level exceeds the background noise The narrow-band characteristic peaks indicate that there is micro-leakage or insufficient stiffness due to wear on the sealing surface; the system then adjusts the pulse width duty cycle of the pilot drive mechanism 500 by increasing the pulse width modulation duty cycle. By finely adjusting the pressure difference to compensate for mechanical clearance errors, and ensuring the consistency of flow output, this feature-based hierarchical control strategy effectively improves the robustness of the valve under complex operating conditions.

[0105] Step S3 includes:

[0106] The ultrasonic transducer array 400 is activated within a preset microsecond time before the valve core 200 is opened.

[0107] The viscosity of the medium inside the guide gap 310 is reduced by the acoustic cavitation heat effect, and dry ice particles are prevented from adhering; the radiation force generated by the acoustic levitation effect is used to separate the valve core 200 from the inner wall of the guide sleeve 300.

[0108] In step S3, a gaseous medium or supercritical gaseous medium is used as a low-viscosity lubricating layer to change the friction mode between valve core 200 and guide sleeve 300 from fluid lubrication or solid particle abrasive wear to gas film lubrication.

[0109] This embodiment is a further specification of the ultrasonic action mechanism in step S3; the ultrasonic transducer array 400 is activated within a preset microsecond time before the valve core 200 is opened, in order to use the acoustic cavitation heat effect to make the local temperature in the gap jump to above the pseudo-critical temperature, thereby significantly reducing the density and rapidly reducing the viscosity of the medium in the guide gap 310, and preventing dry ice particles from adhering to the guide surface.

[0110] The acoustic radiation force generated by the propagation of ultrasound in the medium creates an acoustic levitation effect, forcibly separating the valve core 200 from the inner wall of the guide sleeve 300. Utilizing the converted gaseous medium or supercritical gaseous medium as a low-viscosity lubricating layer, the friction mode between the valve core 200 and the guide sleeve 300 changes from a high-resistance fluid lubrication or solid particle abrasive wear mode to an air-floating state, i.e., a high-heat-energy gas film lubrication mode based on ultrasonic cavitation. In this state, the surface friction coefficient of the valve core 200 is... Approaching ;

[0111] Specifically, the acoustic radiation force The following force balance criteria must be met:

[0112] ;

[0113] in, For the valve core, 200 units of weight, The unbalanced force is generated by the lateral pulsating pressure of the fluid; in a supercritical high-density carbon dioxide medium, the sound pressure amplitude is adjusted. Make sound energy density The valve core 200 suspension threshold is met, thereby ensuring that the valve core 200 is physically decoupled from the guide surface; acoustic energy density. With sound pressure amplitude Satisfying the relation The system adjusts the amplitude by adjusting the driving voltage. To ensure the generated sound radiation force It is sufficient to overcome the gravity of the valve core 200 and the radial disturbance of the fluid;

[0114] This lubrication mode switching not only significantly reduces the starting inertia of valve core 200 and achieves millisecond-level response, but also avoids motion jamming caused by the accumulation of low-temperature dry ice, extending the service life of key moving parts.

[0115] In step S4, the specific mechanism of the dynamic pressure extrusion film effect is as follows:

[0116] When the valve core 200 is deflected by a lateral force, the gap becomes smaller and the fluid velocity in the lateral non-through spiral groove 210 increases.

[0117] The tangential non-through spiral groove 210 pumps the valve core 200 back to the center position by increasing the local pressure on the side where the gap is smaller, which generates a reverse thrust.

[0118] In step S2, the pressure of the supercritical carbon dioxide fluid is set to be greater than 7.38 MPa;

[0119] The pilot drive mechanism 500 uses an electromagnetic pilot valve, and the monitoring object in step S5 is the current of the electromagnetic pilot valve drive coil.

[0120] This embodiment is a further specification of the specific mechanism of the dynamic pressure extrusion film effect; the mechanism utilizes the structural characteristics of the tangential non-through spiral groove 210 to realize the self-centering function of the valve core 200; when the valve core 200 is subjected to lateral force interference and deviates during high-speed movement, the fluid velocity in the tangential non-through spiral groove 210 on the side with smaller gap increases due to the extrusion effect.

[0121] Unlike the adsorption force caused by the conventional Bernoulli effect, this structure utilizes the pumping action of the spiral groove to cause a sharp increase in local pressure on the side with smaller gaps, thereby generating a reverse thrust pointing towards the center, pushing the valve core 200 back to the center position. At the same time, the high-speed rotating fluid vortex ring has the characteristic of conserving angular momentum, forming a high-rigidity hydrodynamic pressure bearing film, which suppresses the radial oscillation of the valve core 200 during axial movement. This self-healing mechanism based on the hydrodynamic pressure extrusion film effect can maintain the coaxiality of the valve core 200 at the micrometer level under fluid pulsation disturbances without the participation of external sensors, ensuring motion stability during high-frequency switching.

[0122] Example 2:

[0123] Please see Figures 1-2 A carbon dioxide differential pressure controlled quick-on / off valve, comprising:

[0124] The valve body 100 is configured, and a guide sleeve 300 and an annular reflux chamber 110 are provided inside the valve body 100.

[0125] The valve core 200 is slidably disposed within the guide sleeve 300. The valve core 200 is constructed as a differential pressure-bearing piston structure 220. A tangential non-penetrating spiral groove 210 is provided on the circumferential surface of the valve core 200. The position of the tangential non-penetrating spiral groove 210 corresponds to the annular return cavity 110.

[0126] An ultrasonic transducer array 400 is arranged around the outer periphery of the guide sleeve 300 to apply an acoustic cavitation heat field and an acoustic levitation force field to the gap between the valve core 200 and the guide sleeve 300.

[0127] A pilot drive mechanism 500 is connected to the configured valve body 100 and is used to control the fluid pressure differential acting on the valve core 200.

[0128] It also includes a control unit, which is connected to the ultrasonic transducer array 400 and the pilot drive mechanism 500. The control unit is equipped with a current detection module and a pressure signal processing module to perform closed-loop control based on the flow-electric-thermal impedance mapping model.

[0129] This embodiment relates to the specific hardware implementation and operating parameter setting of a carbon dioxide differential pressure controlled fast switching valve; the switching valve is applied to a supercritical fluid environment, and the supercritical carbon dioxide fluid pressure is set to be greater than 7.38 MPa to maintain the supercritical state of the medium; the main body of the device includes a valve body 100, a differential pressure piston structure 220 slidably disposed in a guide sleeve 300, a valve core 200, and an ultrasonic transducer array 400 arranged around the outer periphery of the guide sleeve 300;

[0130] The pilot drive mechanism 500 uses an electromagnetic pilot valve to precisely control the fluid pressure differential acting on the valve core 200. The control unit connects the ultrasonic transducer array 400 and the pilot drive mechanism 500, and is equipped with a current detection module and a pressure signal processing module. During operation, the control unit executes closed-loop control based on a current-electric-thermal-impedance mapping model, focusing on the current of the electromagnetic pilot valve drive coil. Perform high-order feature extraction to construct the current deviation vector:

[0131] ;

[0132] in, To detect the sampling period, For the measured current waveform, The standard reference current waveform is preset; this deviation vector quantifies the degree of deviation between the measured signal and the ideal operating condition by integrating the square of the Euclidean distance.

[0133] By utilizing this deviation vector combined with the flow-electric-thermal impedance mapping model, a sub-microsecond closed-loop response to the 200 air-float state of the valve core is achieved; when Exceeding the preset threshold At that moment, the system determined that the air film was unstable and immediately adjusted the amplitude of the ultrasonic drive voltage using a closed-loop algorithm. By analyzing the characteristics of the current waveform, the ultrasonic field intensity and pilot pressure are adjusted in real time, thereby realizing high-frequency and high-reliability switching control in complex environments such as ultra-high pressure, cryogenic and phase change.

[0134] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for a carbon dioxide differential pressure controlled fast-on / off valve, characterized in that, include: S1. A valve body (100), a valve core (200), an ultrasonic transducer array (400), and a pilot drive mechanism (500) are configured, wherein the valve core (200) is slidably disposed inside the valve body (100), the valve core (200) is constructed as a differential pressure piston structure (220), the valve core (200) is provided with a tangential non-through spiral groove (210) in the circumferential direction, the valve inner wall (120) of the valve body (100) is provided with an annular reflux cavity (110) corresponding to the position of the tangential non-through spiral groove (210), and the ultrasonic transducer array (400) is arranged around the guide sleeve (300) inside the valve body (100); S2. Supercritical carbon dioxide fluid is introduced into the configured valve body (100), and a fluid pressure difference field is generated by the difference in surface area between the upper and lower surfaces of the valve core (200). The fluid pressure difference field is used to maintain the self-sealing closed state of the valve core (200). S3. Upon receiving the activation command, the ultrasonic transducer array (400) is activated first, generating acoustic cavitation heat effect and acoustic suspension effect in the guide gap (310) between the valve core (200) and the guide sleeve (300), converting the supercritical carbon dioxide fluid in the guide gap (310) into a low-density gaseous fluid or a supercritical gaseous medium, and forming an air film on the surface of the valve core (200), so that the valve core (200) is in an air-floating state; S4. Control the pilot drive mechanism (500) to release the pilot pressure, and drive the valve core (200) in the air-float state to eject and open under the action of the fluid pressure difference field. The fluid enters the tangential non-through spiral groove (210) to form a high-speed vortex ring, generating a fluid dynamic pressure centering effect and a dynamic pressure extrusion film effect to maintain the axial precession stability of the valve core (200). S5. Monitor and extract the characteristics of the driving signal and the pressure waveform in real time, and adjust the intensity of the ultrasonic transducer array (400) or the control parameters of the pilot drive mechanism (500) according to the characteristics of the driving signal and the pressure waveform to complete the switching action cycle.

2. The method for a carbon dioxide differential pressure controlled quick-opening valve according to claim 1, characterized in that, Before step S1, the following steps are included: S1.1, constructing a flow-electric-thermal impedance mapping model, taking the phase change critical blocking rate at the valve port and the eccentricity of the air-float gap of the valve core (200) as implicit physical parameters, and taking the high-frequency harmonic component of the driving coil current and the attenuation rate of the pressure waveform after the valve as measurable signals, and constructing a variable stiffness compensation model.

3. The method for a carbon dioxide differential pressure controlled quick-opening valve according to claim 2, characterized in that, In step S5, the specific logic of the feature feedback adjustment includes: collecting the pressure step response time at the moment the valve opens and the slope of the pressure decay curve at the moment the valve closes; when the pressure step response time is prolonged and low-frequency high-amplitude oscillations occur in the high-frequency harmonic components of the current, it is determined to be the initial stage of dry ice sticking, and the power and frequency of the ultrasonic transducer array (400) are increased; when the slope of the pressure decay curve becomes slower and is accompanied by a high-frequency whistling signal, it is determined to be a micro-leakage or wear of the sealing surface, and the pulse width duty cycle of the pilot drive mechanism (500) is adjusted to perform differential pressure fine-tuning compensation.

4. The method for a carbon dioxide differential pressure controlled quick-opening valve according to claim 3, characterized in that, The S3 step includes: starting the ultrasonic transducer array (400) within a preset microsecond time before the valve core (200) is opened; using the acoustic cavitation heat effect to reduce the viscosity of the medium in the guide gap (310) and prevent dry ice particles from adhering; using the acoustic levitation effect to generate radiation force to forcibly separate the valve core (200) from the inner wall of the guide sleeve (300).

5. The method for a carbon dioxide differential pressure controlled quick-opening valve according to claim 4, characterized in that, In step S4, the specific mechanism of the dynamic pressure squeezing film effect is as follows: when the valve core (200) is deflected by the lateral force, the fluid velocity in the tangential non-through spiral groove (210) on the side with smaller gap increases; the pumping action of the tangential non-through spiral groove (210) causes the local pressure on the side with smaller gap to rise, generating a reverse thrust to push the valve core (200) back to the center position.

6. The method for a carbon dioxide differential pressure controlled quick-opening valve according to claim 5, characterized in that, In step S2, the pressure of the supercritical carbon dioxide fluid is set to be greater than 7.38 MPa.

7. The method for controlling the carbon dioxide differential pressure type quick-opening valve according to claim 6, characterized in that, The pilot drive mechanism (500) is an electromagnetic pilot valve, and the monitoring object in step S5 is the current of the electromagnetic pilot valve drive coil.

8. The method for a carbon dioxide differential pressure controlled quick-opening valve according to claim 7, characterized in that, In step S3, the gaseous medium or the supercritical gaseous medium is used as a low-viscosity lubricating layer to change the friction mode between the valve core (200) and the guide sleeve (300) from fluid lubrication or solid particle abrasive wear to gas film lubrication.

9. A carbon dioxide differential pressure controlled quick-on / off valve, configured to perform the steps of the method as described in any one of claims 1 to 8, characterized in that, include: A valve body (100) is configured, wherein a guide sleeve (300) and an annular reflux cavity (110) are provided inside the valve body (100); a valve core (200) is slidably disposed in the guide sleeve (300), the valve core (200) is constructed as a differential pressure piston structure (220), and a tangential non-through spiral groove (210) is provided on the circumferential surface of the valve core (200), the position of the tangential non-through spiral groove (210) corresponds to the annular reflux cavity (110); an ultrasonic transducer array (400) is arranged around the outer periphery of the guide sleeve (300) for applying an acoustic cavitation heat field and an acoustic levitation force field to the gap between the valve core (200) and the guide sleeve (300); a pilot drive mechanism (500) is connected to the valve body (100) for controlling the fluid pressure difference acting on the valve core (200).

10. A carbon dioxide differential pressure controlled quick-on / off valve according to claim 9, characterized in that, It also includes a control unit, which is connected to the ultrasonic transducer array (400) and the pilot drive mechanism (500). The control unit is equipped with a current detection module and a pressure signal processing module for performing closed-loop control based on the current-electric-thermal impedance mapping model.

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