Bubble formation and movement regulation and control system for enhancing mass transfer

Abstract

The invention discloses a regulation and control system for forming and moving bubbles for enhancing mass transfer. The regulation and control system comprises a gas phase injector, a liquid phase injector, a micro-mixer and a high-speed camera, an outlet of the gas phase injector and an outlet of the liquid phase injector are communicated with an inlet of the micro-mixer, a mixed liquid outlet of the micro-mixer is communicated with an inlet of the recoverer, the micro-mixer is of a transparent structure, the high-speed camera directly faces the micro-mixer, and the system can be used for observing forming and moving processes of bubbles.

Description

Technical Field

[0001] The invention belongs to the technical field of microbubble preparation and microfluid property analysis, and relates to a control system for bubble formation and movement for enhancing mass transfer. Background Art

[0002] Carbon dioxide (CO2) is one of the main greenhouse gases contributing to global climate change, and its increasing emissions pose a serious threat to the environment and ecosystems. Photo- / electrical CO2 reduction technologies can convert CO2 into valuable chemicals or fuels, which is crucial for mitigating the greenhouse effect and achieving carbon resource recycling. In traditional reactors, the thick boundary layer between the gas and liquid phases creates significant mass transfer resistance, limiting the CO2 mass transfer rate. Therefore, mass transfer efficiency is a key factor in determining overall reaction performance during CO2 reduction.

[0003] Publication No. CN105013547B discloses a microbubble / droplet generation and control device and method, including a microinjection pump and a syringe, a microchip and a collector, wherein the microinjection pump is provided with a syringe, and the syringe is connected to the microchip inlet with a hose, the microinjection pump and the syringe are provided with three, respectively connected to the three inlets of the microchip, and the microchip outlet is connected to the collector with a hose. The microchip is formed by the intersection of a square channel and a T-shaped channel, and the microchip inlet has three inlets, the square channel is provided with a first inlet for the continuous phase, one end of the T-shaped channel is provided with a second inlet for the continuous phase at the bifurcation, and the two ends of the T-shaped channel are provided with a dispersed phase inlet and outlet, respectively, the straight channel from the cross-focusing point of the square channel and the T-shaped channel to the outlet is the main channel, and the connecting channel from the second inlet of the continuous phase to the main channel is the branch channel; the width and height of the cross section of the microchip main channel are both less than 1mm; the length of the inlet section of the dispersed phase and the continuous phase is not less than 10mm; the channel cross-sectional size of the second inlet of the continuous phase is smaller than the main channel size; the distance between the second inlet of the continuous phase and the cross-focusing point is not less than 10mm, and the distance from the outlet is not less than 10mm. A novel microbubble / droplet generation and control method includes the following steps: liquid pretreatment: first, the solution is filtered to remove impurities in the solution to prevent channel clogging; device debugging: a. The prepared solutions are transported through microinjection pumps and connected to the microchannels; b. The microchip outlet is connected to the collector; c. The air tightness of the system is checked to see if there is any leakage; d. The microinjection pump is started, the diameter of the injection syringe and the liquid phase volume flow rate are set, and the liquid is driven; (3) Microbubble generation and control: The continuous phase and the dispersed phase enter at the inlet shown in the microchip, and bubbles / droplets are formed at the cross intersection. The continuous phase is input into the second inlet of the continuous phase at the T-shaped fork to facilitate the adjustment of the porosity of the bubbles / droplets and the re-cutting of the bubble size. The microbubbles / droplets are generated in the cross-focusing structure of the microchip; the microbubble / droplet size is re-controlled at the T-shaped fork of the microchip; the generated microbubbles / droplets are re-cut to meet the requirements of subsequent emulsification, reaction, etc. By controlling the flow rate through a microinjection pump and controlling the bubble size through the microchip's channel structure, the device and method significantly improve the efficiency of microbubble / droplet production and emulsification, while reducing the microchip's footprint and costs. The device and method simplify the microbubble / droplet control operation, improve control precision, and enhance controllability.

[0004] Publication number CN109433075A discloses a method for regulating the shape of irregular bubbles in a microchannel. A compound system of a set amount of cetyltrimethylammonium bromide (CTAB), silica nanoparticles and water and a gas are respectively introduced into the microchannel. The microchannel includes the following structures: a liquid phase inlet, a gas phase inlet, a liquid phase channel, a gas phase channel, a mixing channel, a regulation tube and an outlet channel. The microchannel is cross-shaped and is composed of two liquid phase channels, a gas phase channel and a mixing channel communicating with each other. The liquid phase channel, the gas phase channel and the mixing channel are on the same plane. The gas phase inlet is connected to the gas phase channel. The gas phase channel is linear. The gas phase channel and the mixing channel are arranged on a straight line. The liquid phase channel is U-shaped. One ends of the two liquid phase channels are respectively connected to the mixing channel and the gas phase channel, and the other ends of the two liquid phase channels are respectively connected to the liquid phase inlet. The mixing channel is connected to one end of the regulation tube, and the other end of the regulation tube is connected to the outlet channel. The inner diameters of the liquid phase inlet, the gas phase inlet, the liquid phase channel, the gas phase channel and the mixing channel are the same and are all smaller than the inner diameter of the regulation tube. The compound system is injected as the continuous phase into the liquid phase inlet of the microchannel, and the gas is injected as the dispersed phase into the gas phase inlet of the microchannel, and continuous irregular-shaped bubbles are obtained in the regulation tube. In the prior art, adding silica and CTAB to water can play a role in foaming or foam stabilizing, but the formed foams are all nearly spherical or elliptical, with regular shapes, and because they all float to the liquid surface and are exposed to air, they are prone to rupture and cannot stably exist in the liquid, and subsequent research cannot be carried out. The present invention utilizes the electrostatic interaction between negatively charged silica nanoparticles and the cationic surfactant CTAB. The silica nanoparticles are modified by CTAB and are given surface activity. By changing the concentration of CTAB, the surface activity of the silica nanoparticles is changed, so as to control the density of the silica nanoparticles at the gas-liquid interface to precisely regulate the bubble shape. The higher the CTAB concentration, the stronger the activity of the silica nanoparticles. Therefore, more silica nanoparticles are more likely to be adsorbed on the gas-liquid interface. Due to the diameter difference between the mixing channel and the regulation tube, the bubbles are more likely to deform after being extruded from the mixing channel into the regulation tube. In the prior art, most of the generated bubbles are due to the existence of fluid shear force, making the bubble head sharper. However, due to the existence of silica nanoparticles in the present invention, the adsorption equilibrium has been reached in the mixing channel. When entering the regulation tube, the silica nanoparticles are rearranged rather than re-adsorbed, and the rearrangement time is much shorter than the time required for re-adsorption. Therefore, the silica nanoparticles can more quickly protect the bubble head and maintain the spherical shape of the bubble head.

[0005] Taylor flow is a common gas-liquid two-phase flow pattern in microchannels or small reactors. Gas is dispersed in the form of bubbles in a continuous liquid phase, forming an alternating bubble and liquid-elastic structure. This flow pattern offers efficient mass transfer, low backmixing, strong controllability, and excellent heat transfer properties, demonstrating unique advantages in photo- / electro-CO2 reduction reactions. Due to the small size of the microchannels, the boundary layer thickness between the CO2 and the wall is correspondingly reduced, significantly shortening the transfer distance and enhancing the mass transfer effect, which in turn helps improve the reaction efficiency of photo- / electro-CO2 reduction.

[0006] However, the prior art cannot observe the process of bubble formation and movement. Summary of the Invention

[0007] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a control system for bubble formation and movement for enhancing mass transfer, which can observe the formation and movement process of bubbles.

[0008] To achieve the above-mentioned object, the present invention discloses a control system for bubble formation and movement for enhancing mass transfer, comprising a gas phase injector, a liquid phase injector, a micro mixer and a high-speed camera;

[0009] The outlet of the gas phase injector and the outlet of the liquid phase injector are connected to the inlet of the micro mixer, and the mixed liquid outlet of the micro mixer is connected to the inlet of the recovery device. The micro mixer is a transparent structure, and the high-speed camera faces the micro mixer.

[0010] The further improvement of the control system for bubble formation and movement for enhanced mass transfer of the present invention is:

[0011] Furthermore, it also includes a first injection pump for controlling the injection speed of the gas phase syringe and a second injection pump for controlling the injection speed of the liquid phase syringe.

[0012] Furthermore, the outlet of the gas phase injector is connected to the first inlet of the micro mixer via a gas phase inlet conduit and a first micro straight-through connector.

[0013] Furthermore, the outlet of the liquid-phase syringe is connected to the second inlet of the micro-mixer via a liquid-phase inlet conduit and a second micro-through connector.

[0014] Furthermore, a spiral rectangular cross-section flow channel is provided in the micro-mixer, wherein the cross-sectional dimension of the spiral rectangular cross-section flow channel is between 0.1 mm and 1 mm, and the spiral radius dimension is between 0.75 mm and 8.25 mm.

[0015] Furthermore, the flow rate of the gas phase injected into the gas phase injector is 2-30 mL / min.

[0016] Furthermore, the flow rate of the liquid phase injected by the liquid phase syringe is 2.5-15 mL / min.

[0017] Furthermore, the micro mixer is placed on a base, and the base is fixed with an EPE pearl cotton foam board.

[0018] Furthermore, the inner diameter of the gas phase inlet conduit and the inner diameter of the liquid phase inlet conduit are both 0.5 mm.

[0019] Furthermore, the gas injection flow rate of the gas phase syringe was controlled by the first injection pump, and the liquid injection flow rate of the liquid phase syringe was controlled by the second injection pump. The formation and movement of the bubbles were observed using a high-speed camera.

[0020] The present invention has the following beneficial effects:

[0021] The control system for bubble formation and movement for enhancing mass transfer described in the present invention is extremely practical in that, during specific operation, the gas injection flow rate of the gas phase injector and the liquid injection flow rate of the liquid phase injector are controlled, and then the formation and movement process of the bubbles are observed using a high-speed camera.

[0022] Furthermore, a spiral rectangular cross-section flow channel is provided in the micromixer, and the boundary layer thickness between the carbon dioxide bubbles and the KOH or KHCO3 wall is correspondingly reduced, which greatly shortens the transfer distance to improve the mass transfer enhancement effect, thereby facilitating the improvement of the reaction efficiency of photo / electric carbon dioxide reduction. The system is stable and easy to operate, and the generated bubbles are uniform and controllable. The thin gas-liquid boundary layer thickness gives the system excellent mass transfer performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 It is a structural diagram of the present invention;

[0025] Figure 2 Micrographs at different gas and liquid flow rates.

[0026] Among them, 1 is a gas phase syringe, 2 is a liquid phase syringe, 3 is a gas phase inlet conduit, 4 is a liquid phase inlet conduit, 5 is a micro straight-through connector, 6 is a micro mixer, 7 is a mixed liquid outlet, and 8 is a high-speed camera. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] In the description of the present invention, it is to be understood that the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0029] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0030] It should be further understood that the term "and / or" as used in the present specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0031] It should be understood that although the terms "first," "second," and "third" may be used to describe preset ranges in embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are merely used to distinguish one preset range from another. For example, without departing from the scope of embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0032] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0035] Example 1

[0036] refer to Figure 1 The control system for bubble formation and movement for enhancing mass transfer of the present invention includes a gas phase injector 1, a liquid phase injector 2, a gas phase inlet conduit 3, a liquid phase inlet conduit 4, a micro mixer 6 and a high-speed camera 8;

[0037] The outlet of the gas phase injector 1 and the outlet of the liquid phase injector 2 are connected to the inlet of the micro mixer 6, and the mixed liquid outlet 7 of the micro mixer 6 is connected to the inlet of the recovery device. The micro mixer 6 is a transparent structure, and the high-speed camera 8 is facing the micro mixer 6.

[0038] In this embodiment, the outlet of the gas phase injector 1 is connected to the first inlet of the micro mixer 6 through the gas phase inlet conduit 3 and the first micro straight-through connector 5 .

[0039] In this embodiment, the outlet of the liquid-phase injector 2 is connected to the second inlet of the micro-mixer 6 via the liquid-phase inlet conduit 4 and the second micro-through connector 5 .

[0040] In this embodiment, a spiral rectangular cross-section flow channel is provided in the micro-mixer 6 , wherein the cross-sectional dimension of the spiral rectangular cross-section flow channel is between 0.1 mm and 1 mm, and the spiral radius is between 0.75 mm and 8.25 mm.

[0041] In this embodiment, the inner diameter of the gas phase inlet conduit 3 and the inner diameter of the liquid phase inlet conduit 4 are both 0.5 mm.

[0042] In this embodiment, the gas phase injector 1 and the liquid phase injector 2 are both large-capacity injectors with a volume of 200 ml or more, so as to ensure that the system can work continuously for a long time.

[0043] The gas phase inlet conduit 3 and the liquid phase inlet conduit 4 form a T-shaped interface in the micro mixer 6. In this embodiment, the liquid phase channel is a main channel of the T-shaped structure, and the gas phase channel is a branch channel of the T-shaped structure.

[0044] In this embodiment, the gas phase in the gas phase injector 1 is a dispersed phase, which is carbon dioxide gas; the liquid phase in the liquid phase injector 2 is a continuous phase, which is a KOH or KHCO3 aqueous solution.

[0045] In this embodiment, the micro mixer 6 is made of transparent polymethyl methacrylate or quartz glass.

[0046] In this embodiment, a first injection pump for controlling the injection speed of the gas phase syringe 1 and a second injection pump for controlling the injection speed of the liquid phase syringe 2 are also included. The gas phase flow rate and the liquid phase flow rate are adjusted by the first injection pump and the second injection pump to change the size and frequency of bubble generation.

[0047] In this embodiment, the two-phase flow images are collected by the optical microscope of the high-speed camera 8, and the formation and movement process of microbubbles are studied based on the obtained images.

[0048] In this embodiment, the flow rate of the gas phase injected by the gas phase injector 1 is 2-30 mL / min, and the flow rate of the liquid phase injected by the liquid phase injector 2 is 2.5-15 mL / min.

[0049] In this embodiment, the width of the bubbles formed in the present invention is 500-900 μm, the generation frequency is 3-220 Hz, and the movement speed is 0.075-0.5 m / s.

[0050] In this embodiment, the micro mixer 6 is placed on a base, and the base is fixed with an EPE pearl cotton foam board.

[0051] It should be noted that the present invention adjusts the gas phase flow rate and liquid phase flow rate through the injection pump, changes the size and frequency of bubble generation, and then uses the high-speed camera 8 to observe the formation and movement process of the bubbles. The system is stable and easy to operate. The generated bubbles are uniform and controllable, and the thin gas-liquid boundary layer thickness makes the system have excellent mass transfer performance.

[0052] During specific use, the gas phase injection flow rate of the gas phase syringe 1 is first controlled by the first injection pump, and the liquid phase injection flow rate of the liquid phase syringe 2 is controlled by the second injection pump, wherein the gas phase injection flow rate of the gas phase syringe 1 is set to 2mL / min, and the liquid phase injection flow rate of the liquid phase syringe 2 is set to 2.5mL / min. The high-speed camera 8 is turned on and the focal length is adjusted to ensure that the entire flow channel is recorded in the camera screen. The frame rate of the high-speed camera 8 is set to 10,000 frames / second, and the resolution is 896×504 at this time. Finally, the high-speed camera 8 is used to record the bubble movement under this working condition, including bubble size, spacing, number and other parameters.

[0053] Example 2

[0054] This embodiment is based on the first embodiment, and the similarities between this embodiment and the first embodiment are not repeated here. The differences between this embodiment and the first embodiment are as follows:

[0055] refer to Figure 2 , keep the flow rate of the liquid phase injected by the liquid phase injector 2 unchanged, change the flow rate of the gas phase injected by the gas phase injector 1 according to the appropriate gradient change, and then use the high-speed camera 8 to record the bubble movement under different working conditions, including bubble size, spacing, number and other parameters.

[0056] Example 3

[0057] This embodiment is based on the first embodiment, and the similarities between this embodiment and the first embodiment are not repeated here. The differences between this embodiment and the first embodiment are as follows:

[0058] refer to Figure 2 The flow rate of the gas phase injected by the gas phase injector 1 is kept constant, and the flow rate of the liquid phase injected by the liquid phase injector 2 is changed according to an appropriate gradient. Subsequently, a high-speed camera 8 is used to record the bubble movement under different working conditions, including parameters such as bubble size, spacing, and number.

[0059] Those skilled in the art will readily identify other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

[0060] It should be understood that the present invention is not limited to the exact construction described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0061] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A control system for bubble formation and movement for enhancing mass transfer, characterized in that: It comprises a gas phase injector (1), a liquid phase injector (2), a micro mixer (6) and a high-speed camera (8); The outlet of the gas phase injector (1) and the outlet of the liquid phase injector (2) are connected to the inlet of the micro mixer (6), and the mixed liquid outlet (7) of the micro mixer (6) is connected to the inlet of the recovery device. The micro mixer (6) is a transparent structure, and the high-speed camera (8) is facing the micro mixer (6).

2. The control system for bubble formation and movement for enhanced mass transfer according to claim 1, characterized in that: It also includes a first injection pump for controlling the injection speed of the gas phase injector (1) and a second injection pump for controlling the injection speed of the liquid phase injector (2).

3. The control system for bubble formation and movement for enhanced mass transfer according to claim 1, characterized in that: The outlet of the gas phase injector (1) is connected to the first inlet of the micro mixer (6) via the gas phase inlet conduit (3) and the first micro straight-through connector (5).

4. The control system for bubble formation and movement for enhanced mass transfer according to claim 3, characterized in that: The outlet of the liquid phase injector (2) is connected to the second inlet of the micro mixer (6) via the liquid phase inlet conduit (4) and the second micro straight-through connector (5).

5. The control system for bubble formation and movement for enhanced mass transfer according to claim 1, characterized in that: The micro mixer (6) is provided with a spiral rectangular cross-section flow channel, wherein the cross-section size of the spiral rectangular cross-section flow channel is between 0.1 mm and 1 mm, and the spiral radius size is between 0.75 mm and 8.25 mm.

6. The control system for bubble formation and movement for enhanced mass transfer according to claim 1, characterized in that: The flow rate of the gas phase injected by the gas phase injector (1) is 2-30 mL / min.

7. The control system for bubble formation and movement for enhanced mass transfer according to claim 1, characterized in that: The flow rate of the liquid phase injected by the liquid phase injector (2) is 2.5-15 mL / min.

8. The control system for bubble formation and movement for enhanced mass transfer according to claim 1, characterized in that: The micro mixer (6) is placed on the base, and the base is fixed with an EPE pearl cotton foam board.

9. The control system for bubble formation and movement for enhanced mass transfer according to claim 4, characterized in that: The inner diameter of the gas phase inlet conduit (3) and the inner diameter of the liquid phase inlet conduit (4) are both 0.5 mm.

10. The control system for bubble formation and movement for enhanced mass transfer according to claim 2, characterized in that: The gas phase injection flow rate of the gas phase injector (1) is controlled by a first injection pump, the liquid phase injection flow rate of the liquid phase injector (2) is controlled by a second injection pump, and the formation and movement process of the bubbles are observed using a high-speed camera (8).

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