CN115228515B - Series connection domain limiting device and method for regulating and controlling size distribution of disperse phase in multiphase system - Google Patents
Series connection domain limiting device and method for regulating and controlling size distribution of disperse phase in multiphase system Download PDFInfo
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Abstract
The invention relates to the field of microfluidics, and discloses a series connection domain limiting device and a method for regulating and controlling the size distribution of disperse phases in a multiphase system, wherein the series connection domain limiting device comprises an inlet channel (1), a domain limiting unit and an outlet channel (4) which are arranged continuously, the domain limiting unit comprises at least two domain limiting channels (2) and at least one middle channel (3) which are sequentially and alternately connected in series between the inlet channel and the outlet channel, and the through-flow cross-sectional area of the domain limiting channels is smaller than that of the middle channel at least at the position where the two domain limiting channels are connected with each other. The series connection limiting device can realize the regulation and control of dispersed phases such as bubbles/liquid drops only by being connected in series with other devices, and has the advantages of simple structure, convenient operation and the like; the control method can effectively utilize the extrusion and pulsation impact of the continuous phase and the self-instability, rapid stretching and other breaking mechanisms of the disperse phase, and realize the effective control of the breaking behavior and the size distribution of bubbles/liquid drops.
Description
Technical Field
The invention relates to the field of microfluidics, in particular to a series connection domain limiting device for regulating and controlling size distribution of a disperse phase in a multiphase system. On the basis, the invention also relates to a method for regulating and controlling the size distribution of the disperse phase in the multiphase system.
Background
Multiphase flow is widely found in the process industries of nature, chemical, petroleum, power, metallurgy, food, and the like. For chemical reactors, the disperse phases such as bubbles, liquid drops and the like can directly influence the speed field, and meanwhile, the mass transfer and heat transfer effects of the system can be changed by changing the phase interface property and the like, so that the performance of the equipment at the micro-scale and the macro-scale is finally influenced. Thus, controlling the deformation and collapse behavior of the bubbles/droplets, optimizing the size distribution and multiphase dispersion process has a direct and important impact on the momentum, mass and heat transfer of the overall reaction system.
The bubble/droplet breakup and generation process is generally believed to be the result of a combination of external and internal factors, including flow fields (e.g., turbulence characteristics, shear rates, etc.), liquid phase properties (e.g., viscosity, density, etc.), and other external conditions (e.g., temperature, applied electric field, acoustic field, etc.); internal factors include mainly two-phase nature, and various internal forces (e.g., viscosity, surface tension, etc.) of the dispersed phase. The main causes of deformation and rupture of the dispersed phase include turbulence pulsation and collision, interfacial instability, viscous shearing action of the continuous phase, erosion (scouring) of the fluid, etc. Wherein turbulent flow fields, while providing higher energy to promote bubble collapse, have not yet been well-defined by researchers due to their complex structure and high volatility, and thus achieving control of bubble size using turbulent pulsations and collisions has very high difficulty and very stringent operating conditions. The use of laminar flow system to realize the size regulation of bubbles/liquid drops has the remarkable advantages of stability, controllability and the like, and especially in recent years, micro-channel equipment such as micro-reactors and the like have been increasingly focused and applied due to the characteristics of small size, no back mixing, large specific surface area, high mass and heat transfer coefficients, continuous operation and the like. Most of the micro-channels are laminar flow systems, and a foundation is created for realizing the regulation and control of dispersed phases such as bubbles/liquid drops.
The current method for regulating and controlling the size of bubbles/liquid drops is mostly realized through cross-shaped, T-shaped, coaxial-shaped and similar-shaped channel structures, so that on one hand, the method has very high requirements on equipment processing and process parameter control, and on the other hand, at least two channels and driving devices are needed, so that the cost is increased, and meanwhile, the complexity of the whole process flow is inevitably improved; and the external field reinforcement also increases the cost and difficulty of processing and operation.
Disclosure of Invention
The invention aims to solve the problems that in the prior art, a complex channel structure is required for regulating and controlling the size of a disperse phase, and the size control is unstable, and provides a series connection domain limiting device for regulating and controlling the size distribution of the disperse phase in a multiphase system.
In order to achieve the above object, according to one aspect of the present invention, there is provided a serial domain-limiting device for controlling size distribution of a dispersed phase in a multiphase system, including an inlet channel, a domain-limiting unit, and an outlet channel which are continuously arranged, wherein the domain-limiting unit includes at least two domain-limiting channels and at least one intermediate channel which are sequentially and alternately connected in series between the inlet channel and the outlet channel, and at least at a position where the two domain-limiting channels are connected to each other, a through-flow cross-sectional area of the domain-limiting channels is smaller than a through-flow cross-sectional area of the intermediate channel.
Preferably, the confinement channel has a constant through-flow cross-sectional area over its extension.
Preferably, the extension length of the limiting channel is not less than 10 times of the maximum width dimension of the limiting channel, and/or the through flow cross section area of the limiting channel is not more than 0.01mm 2.
Preferably, the maximum width dimension of the confinement channel does not exceed half the maximum width dimension of the intermediate channel.
Preferably, the through-flow cross-sectional area of the restrictor passage is smaller than the through-flow cross-sectional area of the inlet passage, and the inlet passage tapers in a direction toward the restrictor unit at a position where the inlet passage meets the restrictor unit.
Preferably, the through-flow cross-sectional area of the outlet channel increases in a direction away from the restriction unit.
Preferably, at a position where the outlet channel meets the restricting unit, the outlet channel is gradually extended in a direction away from the restricting unit; and/or the bottom of the outlet channel is formed with a step-down step portion so that the through-flow cross-sectional area of the outlet channel is increased.
Preferably, the tandem confinement device has a housing in which the inlet channel, the confinement channel, the intermediate channel, and the outlet channel are formed along the same line.
Preferably, the shell is made of one or more of glass, metal, ceramic, alloy, polymer and composite material.
In a second aspect, the present invention provides a method for controlling the size distribution of a dispersed phase in a multiphase system, comprising: s1, material analysis and pretreatment, namely determining at least one material parameter of density, viscosity, surface tension and rheological property of a operated material, and filtering a solution in the operated material to remove impurities; s2, selecting the corresponding domain limiting device according to the expected disperse phase size and the determined material parameter, and connecting the serial domain limiting device in series to a fluid conveying control system; s3, the fluid conveying control system is controlled to introduce the multiphase material comprising the operated substance into the inlet channel, and the multiphase material flows through the limit area unit and the outlet channel and is output.
Through the technical scheme, the series connection limiting device can realize the regulation and control of dispersed phases such as bubbles/liquid drops only by being connected in series with other devices, and does not need additional channels, driving devices or internal components, and has the advantages of simple structure, convenience in operation and the like; the control method can effectively utilize the extrusion and pulsation impact of the continuous phase and the self-instability, rapid stretching and other breaking mechanisms of the disperse phase, and can realize the effective control of the breaking behavior and the size distribution of bubbles/liquid drops with higher control precision by connecting a plurality of channels in series.
Drawings
Fig. 1 is a schematic structural view of a serial field limiting device according to a first preferred embodiment of the present invention;
FIG. 2 is a velocity vector diagram of a multiphase system within the series connected domain limiting device shown in FIG. 1;
FIG. 3 is a flow diagram of a multiphase system within the series connected domain limiting device shown in FIG. 1;
Fig. 4 is a schematic view showing a connection structure of an inlet channel and a domain unit in a serial domain-limiting apparatus according to another preferred embodiment of the present invention;
Fig. 5 is a schematic view showing the structure of an outlet channel in a serial field device according to another preferred embodiment of the present invention;
FIG. 6 is a size distribution of bubbles generated in example 1;
FIG. 7 is a size distribution of bubbles generated in comparative example 1;
FIG. 8 is a size distribution of bubbles generated in comparative example 2;
FIG. 9 is a size distribution of droplets produced in example 2;
fig. 10 is a size distribution of droplets produced in comparative example 3.
Description of the reference numerals
1-An inlet channel; 2-a domain-limited channel; 3-an intermediate channel; 4-outlet channel.
Detailed Description
The following describes specific embodiments of the present invention in detail with reference to the drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
Referring to fig. 1 to 3, a serial field limiting device for controlling size distribution of dispersed phases in a multiphase system according to a preferred embodiment of the present invention includes an inlet channel 1, a field limiting unit and an outlet channel 4 which are arranged in series, the field limiting unit including at least two (three are shown) field limiting channels 2 and at least one (two are shown) intermediate channel 3 which are sequentially and alternately connected in series between the inlet channel 1 and the outlet channel 4, and a through-flow cross-sectional area of the field limiting channels 2 is smaller than that of the intermediate channel 3 at least at a position where they meet each other.
By passing a multiphase material into the inlet channel 1, the multiphase material thus continues to flow through the individual confinement units and the outlet channel 4. In the process, the size of the disperse phase in the multiphase system can be regulated and controlled due to the change of the cross section area of the through flow at the position where different channels are connected with each other. Specifically, when flowing from the inlet channel 1 into the restricting channel 2 having a relatively small through-flow cross-sectional area and flowing out from the restricting channel 2 to the intermediate channel 3 and the outlet channel 4, the continuous phase in the multiphase system generates a squeezing action and a pulsation impact, so that the dispersed phase therein is broken; in the process of flowing through the limiting channel 2, a relatively small through-flow sectional area can be used for stretching the disperse phase, and the rupture behavior and size distribution of bubbles/liquid drops can be effectively controlled by utilizing rupture mechanisms such as instability, rapid stretching and the like.
The series connection limiting device can realize the regulation and control of dispersed phases such as bubbles/liquid drops only by being connected in series with other devices, does not need additional channels, driving devices or internal components, and has the advantages of simple structure, convenient operation and the like. The invention can effectively realize the regulation and control of the disperse phase such as bubbles/liquid drops in a multiphase system, is suitable for various multiphase systems such as gas-liquid, liquid-liquid, gas-liquid-solid, gas-liquid, liquid-liquid and the like, and provides required conditions for the material conveying, mixing and dispersing and reaction processes; the provided limiting unit can be independently used as a micro-reactor, a tubular reactor or a micro-mixer, can also be combined with a heat exchange unit, a collection unit or a reaction/mixing unit and the like to realize complete functions, and has wide application prospects in the fields of chemical industry, biology, medicine, electronics, machinery and the like.
Based on the regulation and control mechanism, the series connection domain limiting device can be formed into a plurality of different structural forms, and the regulation and control of the size distribution of the disperse phase in the multiphase system are realized by utilizing a plurality of fracture mechanisms. For example, the inlet channel 1, the restrictor unit and the outlet channel 4 may be formed directly from a pipe-like housing as shown, or may be a fluid channel formed in other forms (casting). In the illustrated preferred embodiment, the inlet channel 1, the restrictor channel 2, the intermediate channel 3 and the outlet channel 4 each have a constant through-flow cross-sectional area over their extension; in other embodiments, it may also be configured to have a varying cross-sectional flow area depending on regulatory requirements.
With continued reference to fig. 1-3, the restricted area channel 2 extends in a straight line and has a constant through-flow cross-sectional area over its extension. Wherein, in order to effectively stretch the disperse phase, the through-flow cross-sectional area of the confining channel 2 should not be too large. For example, the extension length of the confinement channel 2 is not less than 10 times of the maximum width dimension of the confinement channel 2, and/or the through-flow cross-sectional area of the confinement channel 2 is not more than 0.01mm 2. In the preferred embodiment shown in the drawings, the flow cross section of the confinement channel 2 is a square cross section with a width dimension of 100 μm and a flow cross section of 0.01mm 2. In an alternative embodiment in which the confinement channel 2 is formed as having a circular through-flow cross-section, the maximum width dimension mentioned above is the diameter of the channel.
In order to effectively utilize the extrusion and pulsation impact effects of the continuous phase to achieve the rupture and size control of the dispersed phase through the variation of the through-flow cross-sectional areas, the through-flow cross-sectional areas of the confining channels 2 should have a large difference from the through-flow cross-sectional areas of the inlet channel 1, the intermediate channel 3 and the outlet channel 4. In a preferred embodiment, the maximum width dimension of the confining channel 2 does not exceed half the maximum width dimensions of the inlet channel 1, the intermediate channel 3 and the outlet channel 4.
According to the regulation and control requirements, the series connection limiting device can be formed into different structural forms so as to strengthen or weaken the expected effect of one or more regulation and control mechanisms, and the application range is wide according to different selection targeted dominant mechanisms of the system. In the alternative embodiment shown in fig. 4 and 5, at the point of engagement with the confining element, the inlet channel 1 tapers in the direction towards the confining element, for example the part of the inlet channel 1 adjacent to the confining element is formed in a tapered cone shape to reduce the squeezing action of the continuous phase there.
Similarly, the cross-sectional area of the outlet channel 4 increases in a direction away from the restriction element to reduce the pulsating impact of the multiphase system flowing in the outlet channel 4. The portion of the outlet channel 4 adjacent to the restriction unit may be formed in a tapered shape, and a bottom of the outlet channel 4 is formed with a stepped portion gradually downward, so that a through-flow cross-sectional area of the outlet channel 4 increases. Other aspects of this alternative embodiment may be the same as or have the same modifications as the foregoing preferred embodiment, and the description thereof will not be repeated here.
In the above preferred embodiment, the series-connected restriction device is formed of a pipe-type housing in which the inlet passage 1, the restriction passage 2, the intermediate passage 3, and the outlet passage 4 are formed along the same straight line. The shell is made of one or more of glass, metal, ceramic, alloy, polymer and composite material, and the processing mode can be engraving machine processing, dry etching, LIGA, injection molding, wet etching, photoetching, 3D printing and the like.
Based on the series connection finite field device, the invention also provides a method for regulating and controlling the size distribution of the disperse phase in a multiphase system, and the effective control of the rupture behavior and the size distribution of bubbles/liquid drops is realized by scientifically regulating and controlling the mechanisms such as extrusion and pulsation impact of the continuous phase, self-instability and rapid stretching of the disperse phase and the like. The method comprises the following operation steps:
S1, material analysis and pretreatment: determining material parameters such as density, viscosity, surface tension (interfacial tension), rheological property and the like of a material related to operation (operated material) which can influence the effect of a disperse phase; the solution is subjected to suction filtration, temperature control and the like so as to meet the feeding and operation requirements.
S2, determining a finite field structure and operation parameters: and (3) designing a finite field structure and formulating an operation scheme according to the expected requirement of the size of the disperse phase and the like. The serial domain limiting device provided by the invention establishes a slit or pore throat structure with a certain length by reducing the channel size, and is in serial operation with the main channel, and various fracture-causing mechanisms including but not limited to extrusion, pulsation, impact, erosion of a continuous phase, instability of a disperse phase, rapid stretching fracture and the like are utilized, and one or more mechanisms can be enhanced according to the characteristics and requirements of a specific system to achieve the expected effect. The regulation of the disperse phase is determined by the structure (shape, size and the like) and the operation parameters (flow rate/flow rate of various materials, operation pressure, feeding mode and the like), and the method for determining the structure and the operation parameters comprises theoretical analysis, numerical simulation, condition experiment, experience or semi-experience model and the like. Meanwhile, one finite field channel or a plurality of finite field channels can be selected to be used for series/parallel operation according to the characteristics of a specific operation system. It should be noted that, through the intermediate channel connecting in series a plurality of finite field channels between the inlet channel and the outlet channel, the pressure drop can be increased while the uniformity and stability of the system are improved, so that the number of the finite field channels can be adjusted according to specific process requirements and material properties in the actual process.
Building a device: in addition to selecting the series-connected finite field devices, devices (fluid delivery control systems) such as inlet channels, pumps, pipelines, flowmeters, valves, control systems, reactors and the like of each phase which may be required for fluid delivery and control are selected, built and connected. The invention has no special requirements on upstream and downstream conditions, for example, the upstream can be matched with various bubble/liquid drop generating devices such as T-shaped, Y-shaped, coaxial, focusing, cross-shaped and the like, and the bubble/liquid drop generating device only needs to be connected in series with a series-connection limiting device without additional equipment.
S3, regulating and controlling feeding and dispersing phases: and (3) multiphase feeding is carried out according to the set operation conditions, so that the regulation and control of dispersed phases such as bubbles/liquid drops and the like are realized. If the observation is needed, the measurement can be carried out by combining various testing means such as a camera, PIV/PLIF, a probe, a pressure meter/flowmeter and the like. The regulated multiphase system can be connected with a reactor, a mixer, a heat exchanger or other conveying equipment according to the requirements.
In addition, the control method of the invention can comprise post-treatment and correction steps. And if the size of the disperse phase does not reach the ideal condition, carrying out parameter adjustment optimization according to the actual condition.
The invention can promote the coalescence of partial micro bubbles/liquid drops by utilizing the domain limiting function of the wall surface and the contact and collision between the dispersed phases before and after the expanding area while promoting the break-up of larger bubbles/liquid drops, thereby effectively regulating and controlling the size of the dispersed phases within a target range. The finite field structure can effectively improve multiphase mixing and transfer efficiency, not only improves local flow velocity, shear rate and turbulence degree, but also shortens mass transfer distance, and further strengthens the mixing process. According to different process and material characteristics, the invention can adjust the number of units, structural parameters and operation conditions, thereby pertinently strengthening a fracture leading mechanism and realizing the size distribution meeting the expected target, and has wide application range.
The invention can meet the requirement of the fields of chemical industry, biology, medicine, electronics, machinery and the like on the size distribution of dispersed phase bubbles/liquid drops, and is applicable to various multiphase systems such as gas-liquid, liquid-liquid, gas-liquid-solid, gas-liquid, liquid-liquid and the like; can also be used as a micromixer/reactor for a series of chemical processes: oxidation, peroxidation, reduction, addition, substitution, polymerization, nitration, epoxidation, alkylation, hydrogenation, dehydrogenation, organometallic reaction, carbonylation, alkoxylation, halogenation, dehalogenation, carboxylation, arylation, coupling, condensation, dehydration, alcoholysis, hydrolysis, ammonolysis, etherification, ketone, saponification, isomerization, diazotization, enzyme-catalyzed reaction, and the like.
In the specific implementation process of the invention, the structure properties such as channel materials, channel sizes, limit structure sizes/shapes and the like can be adjusted and optimized according to actual process requirements and material properties, and the operating parameters such as flow rate, pressure, proportion and the like are designed, so that the balance of pressure drop and dispersion is adjusted to obtain the optimal performance: for example, by increasing the flow rate of the mixing system, the size ratio of the inlets, the pressure differential at the inlets can be increased to push the bubbles/droplets to collapse; the bubble/droplet break-up can be effectively promoted and the size can be reduced by reducing the size of the confinement structure; by increasing the length of the confinement region, local instability of the bubble/droplet generation can be promoted to initiate breakage; by increasing the size ratio of the outlets, the jet effect of the liquid phase can be increased to promote the shedding of sub-bubbles/droplets.
Example 1: bubble size control in gas-liquid two-phase flow
A mixed system of 95% glycerol and water was prepared at normal temperature, and the properties of the system were measured, such as density 1255 kg.m -3, surface tension coefficient 0.0675N.m -1, viscosity 0.58 Pa.s, etc. Stirring and mixing the solution, and then carrying out suction filtration to remove impurities. The regulation and control aim is to provide nitrogen bubbles with equivalent diameter in the range of 150-200 mu m, theoretical analysis and numerical calculation are carried out according to target requirements and material characteristics, and a scheme of completing generation of micro bubbles through a cross focusing structure and then utilizing two middle channels to connect three finite field channels in series to further regulate and control the bubbles is determined. Wherein the size of the confinement channels is 100 μm and the length is 1mm (FIG. 1). The channel is made of metal, is formed by precision machining of an engraving and milling machine, and is connected and sealed with the shell in a welding and thread mode.
The solution is introduced into a micro injection pump, the injector is connected with a nitrogen steel cylinder, the micro injection pump is filled with nitrogen, and the injector is connected with the micro channel by adopting a rubber tube. And constructing a backlight and a high-speed camera, adjusting the relative positions of the backlight and the high-speed camera and the micro-channel structure, and shooting generated bubbles. And starting a microinjection pump to drive liquid, controlling the flow of each phase, completing the generation of microbubbles by utilizing a cross focusing structure, further regulating and controlling the generated bubbles by utilizing a finite field structure, collecting and maintaining pictures after the flow is stable, and carrying out bubble identification and size calculation by adopting a digital image processing technology in the later stage.
The results show that the structure provided by the method can effectively control the flowing process, similar local speed gradient and pressure difference are generated in each limited domain structure, the bubbles are rapidly distorted and unstable to fracture (figures 2 and 3), the sizes of the bubbles gradually approach to the ideal distribution target, and the final generated bubbles have more than 90% in the size range of 150-200 mu m (figure 6), so that the regulation and control of the sizes of the bubbles can be effectively realized, the process requirements are met, and the control precision is greatly improved without increasing the operation complexity.
Comparative example 1: bubble size regulation and control of single limiting-area channel in gas-liquid two-phase flow
The bubble size of the system of example 1 was controlled using a single confinement channel, wherein the materials used were the same as in example 1, and the driving, connecting and photographing equipment were all the same, except that the multistage tandem structure was changed to only one confinement channel.
And controlling the flow of each phase by utilizing a microinjection pump, collecting and maintaining pictures after the flow is stable, performing bubble identification and size calculation by adopting a digital image processing technology in the later stage, and feeding back and optimizing operation parameters according to results until the size of the generated bubbles is closest to a target condition.
The results show that the device produces bubbles with about 85% in the size range of 150-200 μm (fig. 7), and can achieve control of bubble size to some extent, but control accuracy is lower than that of a plurality of devices connected in series.
Comparative example 2: bubble size regulation and control of T-shaped bifurcation structure on gas-liquid two-phase flow
The bubble size of the system of the embodiment 1 is regulated and controlled by utilizing a single T-shaped bifurcation structure, wherein the used materials are the same as those of the embodiment 1, and the driving, connecting and shooting equipment are the same, and the difference is that the bubble generation system is changed into a gas-liquid two-phase through T-shaped pipeline structure.
And controlling the flow of each phase by utilizing a microinjection pump, collecting and maintaining pictures after the flow is stable, performing bubble identification and size calculation by adopting a digital image processing technology in the later stage, and feeding back and optimizing operation parameters according to results until the size of the generated bubbles is closest to a target condition.
The results show that only about 50% of the bubbles produced by the method are in the size range of 150-200 μm (FIG. 8), the bubble size distribution is uneven, and the control accuracy is significantly lower than that of the device of the invention.
Example 2: droplet size control in liquid-liquid two-phase flow
Adding 0.5% of sodium dodecyl sulfate into deionized water at normal temperature, stirring uniformly in a pretreatment beaker, taking cyclohexane as a continuous phase, taking the cyclohexane as a disperse phase by a syringe, measuring the material properties of the two phases, and filtering and removing impurities.
Theoretical analysis and numerical calculation are performed according to target requirements and material characteristics, and a scheme for completing generation of liquid drops through a T-shaped structure and then further regulating and controlling the liquid drops by utilizing a five-stage serial finite field structure is determined. The micro-channel material is formed by gluing, photoetching, masking and other operations of Polydimethylsiloxane (PDMS) material to form micro-channels for continuous phase and disperse phase to flow and then bonding with the glass substrate. The size of the limiting structure is 80 mu m, the length of the limiting structure is 1mm, and the outlet is provided with a multi-stage stepped variable-diameter structure, so that the purpose of placing the liquid phase impact with a stronger channel size ratio is to cause the liquid drop to rupture again. Unlike the structure of example 1, since the bulk system droplet deformation and rupture are relatively easy, the structures of the inlet and outlet are adjusted to a gradually changing diameter form in order to prevent excessive rupture (fig. 4, 5).
Feeding continuous phase and disperse phase with certain flow rate from channels at two ends respectively, converging the continuous phase and the disperse phase in a T-shaped micro-channel structure, generating liquid drops by the disperse phase under the shearing action of the continuous phase, then breaking large liquid drops through a series-connection limiting domain structure, and converging partial micro liquid drops so as to regulate the size. The regulated mixed system flows out of the micro-channel chip through the outlet, the generation and the cracking process of the micro-bubbles are recorded through an external high-speed camera, and the photos formed by the micro-bubbles are processed and analyzed by utilizing MATLAB, photoshop, image Pro and other software, so that the size distribution condition of the bubbles is obtained. The method is verified to be capable of carrying out continuous and controllable preparation of a large number of tiny bubbles.
The results show that the structure provided by the method can effectively control the flow process, utilizes the finite field structure to generate local velocity gradient and pressure difference, causes droplet extrusion, local stretching and unstable fracture, and finally generates bubbles with more than 88% in the target size range of 80-100 mu m (figure 9), thereby effectively realizing the regulation and control of droplet size.
Comparative example 3: cross focusing structure is to bubble size regulation and control in gas-liquid two-phase flow
The droplet size of the system of example 2 was controlled using a cross-type structure, wherein the materials used were the same as in example 2, and the microchannel materials, processing mode, driving, connecting and photographing equipment were all the same, except that the droplet generation system was changed to a fluid-passing cross-type pipeline structure.
And controlling the flow of each phase by utilizing a microinjection pump, collecting and maintaining pictures after the flow is stable, carrying out liquid drop identification and size calculation by adopting a digital image processing technology in the later stage, and feeding back and optimizing operation parameters according to results until the size of the generated liquid drops is closest to the target condition.
The results show that only about 55% of bubbles generated by the method are in the size range of 80-100 μm (figure 10), and the fluctuation of the droplet size distribution is large, so that the method provided by the invention has obvious advantages.
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of individual specific technical features in any suitable way. The various possible combinations of the invention are not described in detail in order to avoid unnecessary repetition. Such simple variations and combinations are likewise to be regarded as being within the scope of the present disclosure.
Claims (4)
1. A serial field limiting device for regulating the size distribution of a disperse phase in a multiphase system, which is characterized by comprising an inlet channel (1), a field limiting unit and an outlet channel (4) which are continuously arranged, wherein the field limiting unit comprises at least two field limiting channels (2) and at least one middle channel (3) which are sequentially and alternately connected in series between the inlet channel (1) and the outlet channel (4), one of the at least two field limiting channels (2) is connected with the inlet channel (1), the other of the at least two field limiting channels (2) is connected with the outlet channel (4), the field limiting channels (2) and the middle channel (3) are alternately connected, at least at the position where the field limiting channels are connected with each other, the through-flow cross-sectional area of the field limiting channels (2) is smaller than the through-flow cross-sectional area of the inlet channel (1), and at the position where the field limiting units are connected, the through-flow cross-sectional area of the field limiting channels (2) is smaller than the through-flow cross-sectional area of the inlet channel (1) and the inlet channel (1) gradually extends along the direction towards the field limiting unit; at the position connected with the limiting unit, the outlet channel (4) gradually expands and extends along the direction far away from the limiting unit, and the bottom of the outlet channel (4) is provided with a step part which gradually descends, so that the through-flow cross section area of the outlet channel (4) gradually increases along the direction far away from the limiting unit, wherein the limiting channel (2) has a constant through-flow cross section area in the extending range, the extending length of the limiting channel (2) is not less than 10 times of the maximum width dimension of the limiting channel (2), the through-flow cross section area of the limiting channel (2) is not more than 0.01mm 2, and the maximum width dimension of the limiting channel (2) is not more than half of the maximum width dimensions of the inlet channel (1), the middle channel (3) and the outlet channel (4).
2. The tandem confinement device for controlling the size distribution of a dispersed phase in a multiphase system according to claim 1, wherein the tandem confinement device has a housing in which the inlet channel (1), the confinement channel (2), the intermediate channel (3) and the outlet channel (4) are formed along the same straight line.
3. The device for controlling the size distribution of the dispersed phase in the multiphase system according to claim 2, wherein the shell is made of one or more of glass, metal, ceramic, alloy, polymer and composite material.
4. A method for controlling the size distribution of a dispersed phase in a multiphase system, comprising:
S1, material analysis and pretreatment, namely determining at least one material parameter of density, viscosity, surface tension and rheological property of a operated material, and filtering a solution in the operated material to remove impurities;
S2, selecting a corresponding series-connected domain limiting device according to any one of claims 1 to 3 according to the expected disperse phase size and the determined material parameter, and connecting the series-connected domain limiting device in series to a fluid conveying control system;
S3, the fluid conveying control system is controlled to introduce the multiphase material comprising the operated substance into the inlet channel (1), and the multiphase material flows through the limit area unit and the outlet channel (4) and is output.
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