Micro mixer

Abstract

The invention provides a micro-mixer which comprises a mixer body, the mixer body is used for mixing two different liquids, the mixer body is of a T-shaped structure and comprises two branch connecting parts, a mixing part and a main connecting part, branch channels are formed in the branch connecting parts in a penetrating mode, and the main connecting part is connected with the mixing part. The two connecting parts are respectively used for conveying two different liquids; the two branch connecting parts are symmetrically and fixedly connected with the mixing part, a first channel is formed in the mixing part, a second channel corresponding to the branch channels is formed in the mixing part in a penetrating mode, a plurality of third channels are formed in the mixing part, and the two ends of each third channel are communicated with the first channel and the second channel respectively; a main channel is formed in the main connecting part in a penetrating mode, a fourth channel is formed in the mixing part, one end of the fourth channel is communicated with the first channel, the other end of the fourth channel penetrates through the mixing part, the main connecting part is fixedly connected to the fourth channel of the mixing part, the main channel is communicated with the fourth channel, and two different kinds of liquid flow out through the main connecting part after entering the mixing part to be mixed.

Description

Technical Field

[0001] The invention relates to the technical field of mixers, and in particular to a micro mixer. Background Art

[0002] Microfluidics is a technology that manipulates fluids at a microscale, and micromixers, as an important part of microfluidics systems, have been widely studied and applied. The development of micromixing technology aims to achieve rapid and uniform mixing of trace amounts of liquids, and can precisely control fluid concentration and volume, which is of great significance in chemical reactions, biological analysis and other fields.

[0003] In microchannels, due to the small scale and low flow rate, the fluid is in a laminar state, and its mixing is mainly through free diffusion of the contact surface, resulting in limited mixing efficiency. Domestic and foreign scholars have conducted a lot of research work, and their working principles can be mainly divided into two categories: active micromixers and passive micromixers. Active micromixers use external force sources (magnetic field, acoustic field, electric field, thermal field, etc.) to interfere with fluid flow or induce chaotic convection in the fluid to achieve the purpose of mixing, but active micromixers have the disadvantages of complex production, high cost, and cumbersome structure; while passive micromixers change the shape and structure of the microchannel to make the fluid produce secondary flow, lateral flow, vortex, etc., thereby improving the mixing efficiency.

[0004] In the prior art, most studies have improved the mixing efficiency by adding obstacles in the channel of the micromixer or changing the channel shape to change the fluid laminar flow. However, the laminar flow is essentially difficult to change at a low Reynolds number, so the mixing efficiency is not improved much at a low Reynolds number. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a micro mixer which can improve the mixing efficiency.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A micro mixer comprises a mixer body, which is used to mix two different liquids. The mixer body is in a T-shaped structure, and comprises: a branch connection part, two of which are provided, and a branch channel is opened through the branch connection part, and the two branch connection parts are respectively used to transport two different liquids; a mixing part, two of which are symmetrically fixedly connected to the mixing part, a channel one is provided in the mixing part, a channel two corresponding to the branch channel is opened through the mixing part, a plurality of channels three are provided in the mixing part, and the two ends of the channel three are respectively connected with the channel one and the channel two; a main connection part, a main channel is opened through the main connection part, a channel four is opened on the mixing part, one end of the channel four is connected with the channel one, and the other end of the channel four passes through the mixing part, the main connection part is fixedly connected to the four channels of the mixing part, the main channel is connected with the channel four, and two different liquids flow out through the main connection part after entering the mixing part and mixing.

[0008] The branch connection part and the main connection part are provided with external threads, and the main connection part and the branch connection part are vertically distributed.

[0009] The mixing part is in a cubic structure, the channel one is in an annular structure, the channel one is located at the center of the mixing part, and the channel two is arranged concentrically with the channel one.

[0010] The channel three is distributed at equal angles with the center of the channel one as the center.

[0011] There are four channels three, and the four channels three are distributed at 90 degrees with the center of the channel one as the center.

[0012] The interfaces among the branch channel, channel one, channel two, channel three, channel four and the main channel are circular, and the ratio of the sum of the cross-sectional areas of the multiple channels three to the cross-sectional area of ​​the channel two is 0.6-0.8:1.

[0013] Beneficial effects of the present invention:

[0014] The micro mixer of the present invention provides a channel one in a mixing portion, and provides a plurality of channels three at equal angles with the channel one as the center, the channel three is connected with the channel one, two different liquids are input through the branch channels on both sides and mixed in the channel one and the channel three, thereby improving the mixing efficiency of the liquids. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is an overall plan view of a micro-mixer according to an embodiment of the present invention;

[0016] Figure 2 It is a schematic diagram of the overall structure of a micro mixer according to an embodiment of the present invention;

[0017] Figure 3 A cross-sectional view of a micro-mixer according to an embodiment of the present invention;

[0018] Figure 4 A cross-sectional view of a mixing portion according to an embodiment of the present invention;

[0019] Figure 5 A plan cross-sectional view of a mixing portion according to an embodiment of the present invention;

[0020] Figure 6 This is the concentration cloud diagram of the alkali solution at the outlet of the T-type, 2-6 branch pipe when Re is 10;

[0021] Figure 7 is the mixing efficiency of T-type, 2 to 6 branches when Re is 10;

[0022] Figure 8 The cloud diagram of the alkali solution concentration at the outlets of the four branches under different Reynolds numbers;

[0023] Fig. 9 is the mixing efficiency of T-type and each branch number under different Reynolds numbers;

[0024] Fig.10 This is the cross-sectional view of the four branch pipes when the branch pipe is deflected by 40°;

[0025] Fig.11 The cloud diagram of outlet alkali solution concentration at different branch pipe axial deflection angles;

[0026] Fig.12 Schematic diagram of the effect of different branch pipe axial deflection angles on mixing efficiency;

[0027] Fig.13 The cloud diagram of outlet alkali solution concentration with different cross-sectional area ratios;

[0028] Fig.14 The 0.5 contour line of the alkaline solution concentration cloud diagram at the outlet of the four branches when the cross-sectional area ratio is 0.6;

[0029] Fig.15 Schematic diagram of the effect of different cross-sectional area ratios on mixing efficiency.

[0030] Description of reference numerals:

[0031] 10-connecting part, 11-channel;

[0032] 20-mixing part, 21-channel one, 22-channel two, 23-channel three, 24-channel four;

[0033] 30-main connection part, 31-main channel. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] like Figure 1-Figure 5 As shown, a micro mixer according to an embodiment of the present invention comprises a mixer body, which is used to mix two different liquids. The mixer body is in a T-shaped structure and comprises a branch connection part 10, a mixing part 20 and a main connection part 30.

[0036] Among them, there are two branch connection parts 10, and a branch channel 11 is opened through the branch connection part 10, and the two branch connection parts 10 are used to transport two different liquids respectively; the two branch connection parts 10 are symmetrically fixedly connected to the mixing part 20, a channel 1 21 is provided in the mixing part 20, and a channel 2 22 corresponding to the branch channel 11 is opened through the mixing part 20, and a plurality of channels 3 23 are provided in the mixing part 20, and the two ends of the channel 3 23 are respectively connected with the channel 1 21 and the channel 2 22; a main channel 31 is opened through the main connection part 30, and a channel 4 24 is opened on the mixing part 20, one end of the channel 4 24 is connected with the channel 1 21, and the other end of the channel 4 24 passes through the mixing part 20, the main connection part 30 is fixedly connected to the channel 4 24 of the mixing part 20, the main channel 31 is connected with the channel 4 24, and two different liquids enter the mixing part 20 and mix and then flow out through the main connection part 30.

[0037] In one embodiment of the present invention, the branch connection portion 10 and the main connection portion 30 are provided with external threads, and the main connection portion 30 and the branch connection portion 10 are vertically distributed.

[0038] During installation, the branch connection part 10 and the main connection part 30 are respectively connected to the liquid input pipeline and the liquid output pipeline by threaded connection. Two different liquids are transported to the mixing part through the input pipeline for mixing, and then transported out through the liquid output pipeline after mixing.

[0039] In one embodiment of the present invention, the mixing part 20 is a cubic structure, the channel 1 21 is an annular structure, the channel 1 21 is located at the center of the mixing part 20 , and the channel 2 22 is cocentrically arranged with the channel 1 21 .

[0040] In one embodiment of the present invention, the channel three 23 is distributed at equal angles with the center of the channel one 21 as the center.

[0041] In one embodiment of the present invention, four channels three 23 are provided, and the four channels three 23 are distributed at 90° with the center of the channel one 21 as the center.

[0042] In one embodiment of the present invention, the interface between the branch channel 11, the channel one 21, the channel two 22, the channel three 23, the channel four 24 and the main channel 31 is circular, and the ratio of the sum of the cross-sectional areas of the plurality of channels three 23 to the cross-sectional area of ​​the channel two 22 is 0.6-0.8:1.

[0043] The mixing efficiency of the micro mixer of the present invention is described as follows:

[0044] The mixing efficiency is calculated by the mass fraction or concentration variance of a component on a certain cross section at all calculation nodes. It is often used to characterize macroscopic mixing. Its calculation is shown in equations (1) to (3).

[0045]

[0046] Where N is the total number of nodes in the grid; C i is the mass fraction or mole fraction of the component at each computational node i in the grid; is the average mass fraction or mole fraction of the component at all calculation nodes i on the cross section; σ 2 is the variance of mass fraction or mole fraction, which is used to measure the degree of dispersion of data distribution; σ 2 max is the maximum variance of mass fraction or mole fraction, which is used to indicate the maximum unevenness of component distribution during mixing; M is the mixing intensity. When the material reaches an ideal uniform mixing state, that is, the mass fraction or mole fraction of the components at each node is equal, Mixing intensity M = 100%; the larger the M value, the higher the mixing uniformity, that is, the higher the mixing efficiency.

[0047] Effects of various factors on mixing efficiency

[0048] (1) Effect of the number of branch pipes on mixing efficiency (it should be noted that the branch pipe described in the present invention is channel three, and the branch pipes described below are all referred to as channel three):

[0049] The number of branch pipes in the present invention directly determines the flow mode and characteristics of one of the liquids. Considering the actual manufacturing wall thickness and processing difficulty, the mixing efficiency of 2-6 branch pipes when Re (Reynolds coefficient) is 10 is studied.

[0050] like Figure 6 and Figure 7 As shown, Figure 6 When Re is 10, the concentration cloud diagram of the alkali solution at the outlet of T-type, 2-6 branch pipes is shown below: Figure 7 It is the mixing efficiency of T-type and 2 to 6 branches when Re is 10.

[0051] It should be noted that, the T-shape means that channel one and channel three (branch pipes) are provided, channel two and channel four are connected, and channel two and channel four are T-shaped.

[0052] Depend on Figure 6 and Figure 7 It can be seen that in an ordinary T-tube, the two liquids diffuse in single-sided contact, and the area is small; when there are two branches, there are two contact surfaces, and the increased area speeds up the diffusion speed. As the number of branches increases, the number of liquid strands increases, the contact surface and area increase, and the mixing efficiency improves. When there are five branches, the liquids in adjacent branches contact each other, and the diffusion area decreases. After five branches, the more branches there are, the more contacts there are, the smaller the diffusion area, and the lower the mixing efficiency. When there are four branches, the contact surface area of ​​the two fluids is the largest, and the mixing efficiency is the highest.

[0053] (2) The influence of Reynolds number on mixing efficiency:

[0054] When discussing the mixing efficiency of the micro mixer, the Re (Reynolds number) in the channel is an important influencing factor, which directly determines the mixing effect. The present invention adjusts the range of Re by adjusting the velocity at the entrance of the channel 4. The set inlet velocity interval is 0.001-0.1 m / s, and its variation range corresponds to the Reynolds number of 1-100.

[0055] like Figure 8 and Fig. 9 As shown, Figure 8 The cloud diagram of the alkaline solution concentration at the outlet of the four pipes under different Reynolds numbers is shown in Figure 2. Fig. 9 is the mixing efficiency of the T-type and each branch number under different Reynolds numbers.

[0056] like Fig. 9 As shown in the figure, by observing the mixing efficiency change curves of T-shaped, 2-6 branches at Re of 1, 5, 10, 50, and 100, it is found that when Re is low, the fluid velocity is low, resulting in a longer fluid residence time, which increases the diffusion time and ultimately improves the mixing efficiency. On the contrary, if Re is high, the fluid velocity is accelerated and the fluid diffusion time is reduced, resulting in relatively poor mixing efficiency. It can be observed that there is no interaction between the number of branches and the Reynolds number. Regardless of Re, the mixing efficiency of 4 branches is the best; regardless of the number of branches, the mixing efficiency of this structure is optimal at low Re, and the lower the Reynolds number, the better the improvement of the mixing efficiency compared with the initial structure.

[0057] (3) The influence of the axial angle deflection of the branch pipe on the mixing efficiency:

[0058] The axial deflection angle of the branch pipe will cause flow changes between the fluid in the branch pipe and another fluid. In order to explore the effect of the axial deflection of the branch pipe on the mixing efficiency, the present invention conducts simulation experiments under nine conditions of branch pipe deflection of -40° to 40°, among which the cross-sections of the four branch pipes under the deflection of 40° are as follows: Fig.10 As shown, the corresponding distance of the main pipe is extended or shortened to ensure that the position of the two fluids when they converge is kept at an equal distance from the outlet surface.

[0059] like Fig.10 , Fig.11 and Fig.12 As shown, Fig.10 This is the cross-sectional view of the four branch pipes when the branch pipe is deflected by 40°; Fig.11 The cloud diagram of outlet alkali solution concentration at different branch pipe axial deflection angles; Fig.12 The effect of different branch pipe axial deflection angles on mixing efficiency.

[0060] Depend on Fig.11 Export concentration cloud map and Fig.12 From the change of mixing efficiency, it can be seen that the concentration cloud diagram has almost no change, and the mixing efficiency fluctuates slightly. The reason is that although changing the axial deflection angle of the branch pipe changes the fluid flow characteristics to a certain extent, it does not change the essence of the fluid laminar flow. Its mixing efficiency is still determined by the free diffusion of the contact surface. It can be concluded that the axial deflection angle of the branch pipe has little effect on the mixing efficiency.

[0061] The influence of the cross-sectional area ratio of the branch pipe and the main pipe on the mixing efficiency (it should be noted that the main pipe is the main channel, and the main pipes described below are all represented as main channels):

[0062] The relative size of the branch pipe cross section will affect the shape and size of the single fluid, and thus affect the mixing efficiency of the structure. Without changing the cross-sectional area of ​​the main pipe and the two inlet velocities, the effect of the cross-sectional area ratio of the branch pipe to the main pipe on the mixing efficiency is explored in the range of 0.6 to 1.4.

[0063] like Fig.13 As shown in the figure, it is a cloud diagram of the outlet alkali solution concentration with different cross-sectional area ratios. It can be seen from the figure that the smaller the cross-sectional area ratio, that is, the smaller the cross-sectional area of ​​the branch pipe is relatively, the fluid shape extends to the middle and is relatively "slender", the adjacent branch fluids have no contact, the contact area of ​​the two fluids is large, and the mixing efficiency is high; on the contrary, the larger the cross-sectional area of ​​the branch pipe is relatively, the fluid shape extends to both sides and is relatively "wide and flat", the adjacent branch fluids have contact, the contact area of ​​the two fluids is small, and the mixing efficiency is low.

[0064] (4) Mixing efficiency of mixer under laminar flow condition:

[0065] The mixing efficiency calculation of the mixer in the numerical simulation usually uses the concentration calculation of the nodes on the surface, or uses the fluid flow tracking module to count the distribution of particles on a certain surface. However, the existing methods are relatively complicated for evaluating the mixing efficiency under laminar flow conditions, and it is not possible to quickly and conveniently judge the mixing efficiency. The present invention proposes a method for evaluating the mixing efficiency under laminar flow conditions: the length of the 0.5 contour line of the surface concentration cloud map is used for characterization. Fig.14 As shown, Fig.14 The 0.5 contour line of the outlet concentration cloud map of the four branches when the cross-sectional area ratio is 0.6 is extracted and the total length is calculated, that is, the length L = L1 + L2 + L3 + L4.

[0066] like Fig.15 As shown, it is the influence of different cross-sectional area ratios on mixing efficiency, and the 0.5 isoline in the outlet concentration cloud map of different cross-sectional area ratios is compared with the mixing efficiency. It can be seen that there is a strong correlation between the mixing efficiency and the length of the 0.5 isoline in the concentration cloud map, which indicates that the mixing efficiency can be indirectly characterized by a certain surface concentration 0.5 isoline. It can be further verified that the contact area of ​​the two fluids in the present invention is the decisive factor in the mixing efficiency.

[0067] This paper improves the traditional T-shaped micro-mixer and proposes a micro-mixer with multiple branches at equal spacing. It explores the influence of the Reynolds number and the number of branches on the mixing efficiency and their correlation. It also explores the influence of the axial deflection angle of the branch and the cross-sectional area ratio of the branch to the main pipe on the mixing efficiency when the Reynolds number is 10. The main conclusions are as follows:

[0068] (1) Through simulation analysis, it is found that the mixing efficiency is best when the number of branches is 4. When there are four branches, the contact area between the two fluids is the largest and the mixing efficiency is the highest.

[0069] (2) When other conditions remain unchanged, it is found that the lower the Reynolds number, the better the mixing efficiency. The main reason is that the lower the Reynolds number, the longer the mixing time of the fluid in the pipeline. It is also found that the Reynolds number and the number of branches have no interactive effect on the mixing efficiency. The mixing efficiency can be improved by 18.66% to 34.18%, and the mixing efficiency improvement effect is best at low Reynolds numbers.

[0070] (3) When the Reynolds number is 10 and the cross-sectional area ratio is 1, it is found that the axial deflection angle of the branch pipe has no obvious effect on the mixing efficiency. The reason is that changing the axial deflection angle cannot change the nature of the fluid laminar flow, that is, the mixing efficiency is still determined by the free diffusion of the contact surface.

[0071] (4) When only the cross-sectional area of ​​the branch pipe is changed while the cross-sectional area of ​​the main pipe remains unchanged, it is found that the mixing efficiency is highest when the cross-sectional area ratio of the branch pipe to the main pipe is 0.6 to 0.8. The mixing efficiency method is characterized by the 0.5 contour line length of the concentration cloud map under laminar flow conditions, and the mixing efficiency of four branches with different cross-sectional area ratios when Re is 10 and the 0.5 contour line are used to verify the method, further verifying that the larger the contact area between the two fluids in the present invention, the higher the mixing efficiency.

[0072] According to the micro-mixer of the embodiment of the present invention, channel one is arranged in the mixing part, and multiple channels three are arranged at equal angles with channel one as the center, channel three is connected to channel one, two different liquids are input through branch channels on both sides and mixed in channel one and channel three, so that the mixing efficiency of the liquids can be improved.

[0073] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0074] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, various modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A micro mixer, characterized in that: The invention comprises a mixer body, which is used to mix two different liquids. The mixer body is in a T-shaped structure and comprises: A branch connection part, wherein two branch connection parts are provided, and a branch channel is opened through the branch connection part, and the two branch connection parts are respectively used to transport two different liquids; a mixing part, wherein the two branch connection parts are symmetrically fixedly connected to the mixing part, a channel 1 is provided in the mixing part, a channel 2 corresponding to the branch channel is penetrated through the mixing part, a plurality of channels 3 are provided in the mixing part, and two ends of the channel 3 are respectively connected to the channel 1 and the channel 2; and A main connecting part, wherein a main channel is formed through the main connecting part, a channel four is formed on the mixing part, one end of the channel four is connected with the channel one, and the other end of the channel four passes through the mixing part, the main connecting part is fixedly connected to the channel four of the mixing part, the main channel is connected with the channel four, and two different liquids enter the mixing part and mix and then flow out through the main connecting part.

2. The micro mixer according to claim 1, characterized in that The branch connection part and the main connection part are provided with external threads, and the main connection part and the branch connection part are vertically distributed.

3. The micro mixer according to claim 1, characterized in that: The mixing part is in a cubic structure, the channel one is in an annular structure, the channel one is located at the center of the mixing part, and the channel two is arranged concentrically with the channel one.

4. The micro mixer according to claim 3, characterized in that: The channel three is distributed at equal angles with the center of the channel one as the center.

5. The micro mixer according to claim 4, characterized in that: There are four channels three, and the four channels three are distributed at 90 degrees with the center of the channel one as the center.

6. The micro mixer according to claim 1, characterized in that: The interfaces among the branch channel, channel one, channel two, channel three, channel four and the main channel are circular, and the ratio of the sum of the cross-sectional areas of the multiple channels three to the cross-sectional area of ​​the channel two is 0.6-0.8:1.

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