Design method of fine microfluidic tube liquid distributor and liquid distributor

Abstract

This invention provides a design method and a liquid distributor for a fine microfluidic tubular liquid distributor, belonging to the field of chemical mass transfer equipment design and manufacturing technology. The method includes: determining the number of overflow pipes; determining the outer diameter, wall thickness, distribution plate thickness, and a first height from the lower edge of the overflow orifice to the upper surface of the distribution plate of the overflow pipes; using a single overflow pipe as the research object, calculating the liquid level height through numerical simulation to determine the diameter of the overflow orifice and a second height from the top of the overflow pipe to the upper edge of the overflow orifice; calculating the allowable deviation of the overflow pipe installation height based on a pre-set distribution volume difference; and designing the fine microfluidic tubular liquid distributor based on the number of overflow pipes, their outer diameter, wall thickness, distribution plate thickness, overflow orifice diameter, first height, second height, and allowable installation height deviation. This method improves the reliability of the design results and enhances the precise control of the performance of the fine microfluidic tubular liquid distributor.

Description

Technical Field

[0001] This invention relates to the field of chemical mass transfer equipment design and manufacturing technology, specifically to a design method for a fine microfluidic tubular liquid distributor and the liquid distributor itself. Background Technology

[0002] For gas-liquid mass transfer equipment in the chemical industry, in order to fully utilize the performance of the packing material and ensure sufficient contact and mixing of gas and liquid within the packed tower, it is necessary to achieve a uniform distribution of the gas and liquid two-phase fluids at any cross-section within the tower. Studies have shown that the initial distribution of liquid on the packed bed is a key factor affecting mass transfer efficiency.

[0003] To ensure uniform liquid distribution on the packing bed and prevent liquid accumulation or leakage, a liquid distributor can be used to guide the liquid evenly onto the packing bed. Currently, there are many types of liquid distributors, categorized by application (general-purpose and special-purpose), by the driving force of fluid flow (pressure and gravity), by the liquid outflow method (capillary flow, thin film flow on guide plates, orifice type, weir type, etc.), and by structure (tubular, impact, nozzle, pagoda, lotus seedpod, disc, and trough type, etc.).

[0004] Currently, trough-type liquid distributors are considered one of the most commonly used liquid distributors in the industrial field. They are gravity-type liquid distributors, compact devices whose tanks can be interconnected to maintain a uniform liquid level and relatively easily achieve uniform liquid distribution. However, conventional trough-type distributors typically suffer from the following problems: when the liquid load is low, the spray point density is low, and the liquid distributor cannot achieve the designed uniform distribution effect; when the liquid load is high, severe liquid splashing occurs on the surface of the liquid distribution plate, making it impossible to ensure uniform distribution of liquid across all area units on the packing surface. This results in a high liquid distribution difference on the packing surface, and may even lead to localized dry areas on the packing surface, thus affecting the mass transfer efficiency of the packing.

[0005] To overcome the uncontrollable differences in spray point density and liquid distribution volume in trough-type distributors, a fine microfluidic tubular liquid distributor has been developed. However, for fine microfluidic tubular liquid distributors, existing technologies lack empirical formulas for predicting liquid level height. Furthermore, the liquid level height is related to overflow orifice diameter, overflow pipe diameter, overflow pipe wall thickness, rated flow rate, and working fluid properties, making it difficult to provide a universally accurate empirical formula. Current technologies generally rely on empirical judgment when designing fine microfluidic tubular liquid distributors, which can easily lead to unreliable design results and make it difficult to achieve precise control over the performance of the fine microfluidic tubular liquid distributor. Summary of the Invention

[0006] The purpose of this invention is to provide a design method and a liquid distributor for a fine microfluidic tubular liquid distributor, so as to improve the reliability of the design results of the fine microfluidic tubular liquid distributor and improve the precise control of the performance of the fine microfluidic tubular liquid distributor.

[0007] To achieve the above objectives, in a first aspect, embodiments of the present invention provide a design method for a fine microfluidic tubular liquid distributor. The method includes: determining the number of overflow pipes based on the spray point density requirements of the packing section; determining the outer diameter, wall thickness, distribution plate thickness, and a first height from the lower edge of the overflow hole to the upper surface of the distribution plate of the overflow pipes based on engineering practice and structural strength requirements; using a single overflow pipe as the research object, calculating the liquid level height through numerical simulation to determine the diameter of the overflow hole and a second height from the top of the overflow pipe to the upper edge of the overflow hole; calculating the allowable deviation of the overflow pipe installation height based on a pre-set distribution liquid volume difference; and designing the fine microfluidic tubular liquid distributor based on the number of overflow pipes, the outer diameter and wall thickness of the overflow pipes, the thickness of the distribution plate, the diameter of the overflow hole, the first height, the second height, and the allowable deviation of the installation height.

[0008] Optionally, taking a single overflow pipe as the research object, the diameter of the overflow orifice is determined by calculating the liquid level height through numerical simulation, including: determining the liquid flow rate of a single overflow pipe using numerical simulation; and obtaining Q based on the numerical simulation calculation method of the liquid flow rate. s -H characteristic curve formula, where Q s Where Q is the liquid flow rate of a single overflow pipe, and H is the liquid level height; based on the aforementioned Q s -H characteristic curve formula, to obtain the liquid level height when the flow rate of a single overflow pipe is the rated liquid flow rate; and based on the liquid level height when the rated liquid flow rate is reached, to determine the diameter of the overflow hole.

[0009] Optionally, the numerical simulation calculation method for the liquid flow rate of a single overflow pipe includes: determining the calculation region, boundary conditions, governing equations and initial conditions; and simulating the flow process of liquid through the overflow hole using a gas-liquid interface capture method and a velocity-pressure coupling solution algorithm to obtain the calculation formula for the liquid flow rate of a single overflow pipe.

[0010] Optionally, the calculation area is the area formed by the upper surface of the distribution plate, the virtual wall, the virtual inlet, the overflow hole, and the overflow pipe.

[0011] Optionally, the boundary conditions include: wall boundary conditions, pressure inlet boundary conditions, and pressure outlet boundary conditions, wherein the wall boundary conditions include the upper surface of the distribution plate, the virtual wall, and the outer wall of the overflow pipe, the pressure inlet boundary conditions include the virtual inlet, and the pressure outlet boundary conditions include the overflow pipe outlet.

[0012] Optionally, the governing equations include a volume fraction transport equation, a continuity equation, and a momentum equation, wherein the volume fraction transport equation is:

[0013]

[0014] The continuity equation is:

[0015]

[0016] The momentum equation is:

[0017]

[0018] ρ(θ)=K(θ)ρ g +(1-K(θ))ρ l

[0019] μ(θ)=K(θ)μ g +(1-K(θ))μ l

[0020]

[0021] Where α is the volume fraction, representing the ratio of liquid to the volume of the unit, U is the two-phase velocity of gas and liquid within the computational region, p is the pressure of gas and liquid within the computational region, t is time, θ is the sign distance function, ρ(θ) is the two-phase density of gas and liquid within the computational region, and ρ g To calculate the gas phase density of the gas within the region, ρ l To calculate the liquid phase density of the liquid within the calculation region, μ(θ) represents the two-phase dynamic viscosity of the gas and liquid within the calculation region. g To calculate the gas phase dynamic viscosity of the gas in the region, μ l To calculate the liquid phase dynamic viscosity of the liquid within the region, K(θ) is the Heaviside function, F s σ(θ) is the surface tension of the liquid at the two-phase interface, σ is the surface tension coefficient of the liquid at the two-phase interface, κ(θ) is the interface curvature of the liquid at the two-phase interface, and δ(θ) is the Dirac distribution function.

[0022] Optionally, the initial conditions include: two-phase velocity U = 0; in the virtual pool, the space below the liquid surface α = 1, the space above the liquid surface α = 0, and the space inside the overflow pipe α = 0.

[0023] Optionally, the liquid flow process through the overflow orifice is simulated using a gas-liquid interface capture method and a velocity-pressure coupled solution algorithm. The formula for calculating the liquid flow rate of a single overflow pipe includes: simultaneously using the VOSET method in the gas-liquid interface capture method and the IDEAL algorithm in the velocity-pressure coupled solution algorithm to solve the governing equations, simulating the liquid flow process through the overflow orifice, and obtaining the two-phase velocity U; and based on the two-phase velocity U, calculating the flow rate at the middle cross-section of the overflow orifice to obtain the liquid flow rate of a single overflow pipe. The formula for calculating the liquid flow rate of a single overflow pipe is as follows:

[0024]

[0025] Among them, Q s U represents the liquid flow rate of a single overflow pipe. i Let A be the two-phase velocity U at the grid on the cross-section of the overflow orifice. i Let M be the area of ​​the grid on the cross-section of the overflow orifice, and M be the total number of grids on the cross-section of the overflow orifice.

[0026] Optionally, based on the numerical simulation calculation method of the liquid flow rate, Q is obtained. s The -H characteristic curve formula includes: adjusting the calculation area according to the preset first overflow orifice diameter; adjusting the initial conditions according to multiple preset different liquid level heights; after each adjustment, simulating and calculating the liquid flow rate of the single overflow pipe at the corresponding liquid level height using the numerical simulation calculation method of the liquid flow rate of the single overflow pipe; and fitting the multiple preset different liquid level heights and the liquid flow rate of the single overflow pipe at the corresponding liquid level heights to obtain Q. s -H characteristic curve formula, the Q s The formula for the -H characteristic curve is:

[0027] Q s =mH k

[0028] Where m and k are constants obtained by fitting the results of simulation calculations.

[0029] Optionally, determining the diameter of the overflow orifice based on the liquid level height at the rated liquid flow rate includes: determining whether the liquid level height at the rated liquid flow rate is within a preset height range; and if yes, determining the diameter of the overflow orifice as a preset first overflow orifice diameter; if no, performing the following operations until the liquid level height at the rated liquid flow rate is within the preset height range, and determining the diameter of the overflow orifice as a new first overflow orifice diameter:

[0030] If the liquid level at the rated liquid flow rate is less than a preset height range, the diameter of the first overflow orifice is reduced by a first preset percentage, and the liquid level at the rated liquid flow rate is recalculated based on the new first overflow orifice diameter and the liquid flow rate using a numerical simulation calculation method. If the liquid level at the rated liquid flow rate is greater than the preset height range, the diameter of the first overflow orifice is increased by a second preset percentage, and the liquid level at the rated liquid flow rate is recalculated based on the new first overflow orifice diameter and the liquid flow rate using a numerical simulation calculation method.

[0031] Optionally, the preset height range is 10mm≤H≤50mm, the first preset ratio is 10%, and the second preset ratio is 10%.

[0032] Optionally, the first height a is 30mm ≤ a ≤ 50mm.

[0033] Optionally, the second height b is:

[0034] b = H o +x

[0035] Among them, H o The liquid level is the height at the rated liquid flow rate, and x is the preset adjustment value, 10mm≤x≤50mm.

[0036] Optionally, based on a pre-set difference in liquid distribution, the allowable deviation for the overflow pipe installation height is calculated, including:

[0037]

[0038] Where ε is the allowable deviation of the overflow pipe installation height, z is the difference in liquid distribution, and 0≤z≤5%.

[0039] On the other hand, embodiments of the present invention provide a fine microfluidic tubular liquid distributor, wherein the fine microfluidic tubular liquid distributor is designed using any of the methods described herein.

[0040] Through the above technical solution, this invention first determines the number of overflow pipes based on the required spray point density, ensuring the uniformity of the spray. Then, based on engineering practice and structural strength requirements, other parameters of the overflow pipes are determined. Addressing the unreliability caused by relying on empirical judgment in existing technologies, this invention proposes using numerical simulation to calculate the liquid level height, thereby determining the diameter of the overflow orifice based on the liquid level height. This reduces uncertainties in the design process, improves the reliability and consistency of the design results, and helps to achieve precise control of the performance of the fine microfluidic pipe-type liquid distributor, further improving the efficiency and stability of the entire gas-liquid mass transfer device.

[0041] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0042] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0043] Figure 1 This is a flowchart illustrating the design method of a fine microfluidic pipe liquid distributor provided in an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram of the structure of the fine microfluidic tube liquid distributor provided in an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of the overflow component provided in an embodiment of the present invention;

[0046] Figure 4 This is a schematic diagram of the computational region provided in an embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of the design process of the fine microfluidic tubular liquid distributor provided in the embodiment of the present invention;

[0048] Figure 6 This is a schematic diagram of the flow process of liquid working fluid through the overflow hole at different liquid level heights H provided in the embodiments of the present invention;

[0049] Figure 7 Q is provided in the embodiments of the present invention. s -H characteristic curve schematic diagram;

[0050] Figure 8 This is a schematic diagram of the simulation and experimental results of the water flow rate of a single overflow pipe under different liquid level heights provided in the embodiments of the present invention;

[0051] Figure 9 This is a schematic diagram illustrating the simulation and experimental results of methanol flow rate in a single overflow pipe at different liquid levels, as provided in this embodiment of the invention.

[0052] Explanation of reference numerals in the attached figures

[0053] 1. Liquid Inlet 2. Distribution Pipe

[0054] 3. Distribution branch pipes 4. Distribution plate

[0055] 5 Overflow pipe 6 Overflow hole

[0056] 7 Gas inlet 8 Gas-liquid mixture outlet

[0057] 9. Outer shell 11. Distribution plate upper surface

[0058] 12 Virtual Walls 13 Virtual Imports

[0059] 14. Overflow pipe outer wall surface; 15. Overflow pipe outlet

[0060] 16 virtual pools Detailed Implementation

[0061] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0062] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application all comply with the relevant provisions of national laws and regulations. In the embodiments of this application, certain existing industry solutions such as software, components, and models may be mentioned. These should be considered exemplary, intended only to illustrate the feasibility of implementing the technical solution of this application, and do not imply that the applicant has already used or necessarily used such solutions.

[0063] Figure 1 This is a flowchart illustrating the design method of a fine microfluidic pipe liquid distributor provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the design method of the fine microfluidic tubular liquid distributor provided by the present invention includes the following steps S1-S5.

[0064] Step S1: Determine the number of overflow pipes 5 based on the required spray point density of the packing section.

[0065] Unlike traditional liquid distributors, the fine microfluidic pipe liquid distributor can autonomously control the spray point density. Once the required spray point density is determined, the number of overflow pipes 5 can be manually set. The spray point density is the number of overflow pipes 5 per unit area. Therefore, the number of overflow pipes 5 N = spray point density × area of ​​the distribution plate.

[0066] Step S2: Based on engineering practice and structural strength requirements, determine the outer diameter and wall thickness of the overflow pipe 5, the thickness of the distribution plate 4, and the first height of the lower edge of the overflow hole 6 from the upper surface 11 of the distribution plate.

[0067] Step S3: Taking a single overflow pipe as the research object, the liquid level height is calculated through numerical simulation to determine the diameter of the overflow hole 6 and the second height of the top of the overflow pipe 5 from the upper edge of the overflow hole 6.

[0068] Among them, the second height is positively correlated with the liquid level; the higher the liquid level, the higher the second height also increases.

[0069] In the embodiments of the present invention, the liquid level fluctuation is small, and it is assumed that the liquid level is equal everywhere. Therefore, a single overflow pipe can be selected as the research object.

[0070] Step S4: Based on the pre-set distribution liquid volume difference, calculate the allowable deviation of the installation height of the overflow pipe 5. The installation height is the sum of the diameter of the overflow hole 6, the first height of the lower edge of the overflow hole 6 from the upper surface 11 of the distribution plate, and the second height of the top of the overflow pipe 5 from the upper edge of the overflow hole 6.

[0071] Step S5: Based on the number of overflow pipes 5, the outer diameter and wall thickness of the overflow pipes 5, the thickness of the distribution plate 4, the diameter of the overflow hole 6, the first height, the second height, and the allowable deviation of the installation height, the fine microfluidic tubular liquid distributor is designed.

[0072] Figure 2 This is a schematic diagram of the structure of the fine microfluidic tube liquid distributor provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the overflow component provided in an embodiment of the present invention, as shown below. Figure 2 and Figure 3 As shown, the fine microfluidic liquid distributor mainly consists of a distribution component and an overflow component. The distribution component includes a main distribution pipe 2 and a branch distribution pipe 3; the overflow component includes a distribution plate 4 and an overflow pipe 5, with an overflow hole 6 on the overflow pipe 5. The fine microfluidic liquid distributor also includes a liquid inlet 1, a gas inlet 7, a gas-liquid mixture outlet 8, and a housing 9. The liquid flow process within the distributor is as follows: liquid flows from the liquid inlet 1 into the main distribution pipe 2, is distributed through the branch distribution pipe 3, and accumulates above the distribution plate 4. Then, due to gravity, the fluid accumulated on the distribution plate 4 flows through the overflow hole 6 into the overflow pipe 5, and finally flows out in droplets through the overflow pipe 5.

[0073] For precision microfluidic liquid distributors, the design process primarily involves determining the number of overflow pipes and the diameter of the overflow orifices. The diameter of the overflow orifice directly affects the liquid level (the height of the liquid surface from the upper edge of the overflow orifice at the rated liquid flow rate). If the overflow orifice diameter is too large, the liquid level will be too low. In this case, to ensure the distributed liquid volume difference meets the pre-set requirements, the allowable deviation in installation height will be too small, making it impractical in engineering. Conversely, if the overflow orifice diameter is too small, the liquid level will be too high, leading to problems such as liquid waste, excessive equipment size, high structural strength requirements, and easy clogging of the overflow orifice. Therefore, the diameter of the overflow orifice is crucial in the design of precision microfluidic liquid distributors.

[0074] The proposed design method for a fine microfluidic pipe-type liquid distributor first determines the number of overflow pipes based on the required spray point density, ensuring spray uniformity. Then, based on engineering practice and structural strength requirements, other parameters of the overflow pipes are determined. Addressing the unreliability caused by relying on empirical judgment in existing technologies, this invention proposes using numerical simulation to calculate the liquid level height, thereby determining the overflow orifice diameter based on the liquid level height. This reduces uncertainties in the design process, improves the reliability and consistency of the design results, and facilitates precise control of the performance of the fine microfluidic pipe-type liquid distributor, further enhancing the efficiency and stability of the entire gas-liquid mass transfer device.

[0075] Furthermore, taking a single overflow pipe as the research object, the diameter of the overflow orifice 6 is determined by numerical simulation calculation of the liquid level height, including: determining the liquid flow rate of a single overflow pipe using numerical simulation calculation of the single overflow pipe as the research object; and obtaining Q based on the numerical simulation calculation method of the liquid flow rate. s -H characteristic curve formula, where Q s Where Q is the liquid flow rate of a single overflow pipe, and H is the liquid level height; based on the aforementioned Q s -H characteristic curve formula, to obtain the liquid level height when the flow rate of a single overflow pipe is the rated liquid flow rate; and based on the liquid level height when the rated liquid flow rate is obtained, to determine the diameter of the overflow hole 6.

[0076] Among them, the rated liquid flow rate Q of a single overflow pipe s’ The set value is calculated using the set total rated liquid flow rate Q and the number N of overflow pipes 5. The calculation formula is as follows:

[0077] Numerical simulation methods for liquid flow rate are used to simulate the liquid flow rate of a single overflow pipe under preset overflow orifice diameter and liquid level height. When the overflow orifice diameter is fixed, different simulation results of the liquid flow rate of a single overflow pipe can be obtained by changing the liquid level height. Based on the simulation results, Q is obtained through fitting. s -H characteristic curve formula. Obtain Q s After obtaining the -H characteristic curve formula, the liquid level height at the rated liquid flow rate can be deduced. If the liquid level height meets the requirements, it indicates that the diameter of the overflow orifice is appropriate. If the liquid level height does not meet the requirements, the diameter of the overflow orifice needs to be changed, and the numerical simulation needs to be performed again to fit a new Q. s The -H characteristic curve formula is used to calculate the liquid level height at the rated liquid flow rate until the liquid level height meets the requirements.

[0078] This numerical simulation method can flexibly and accurately adjust the diameter of the overflow orifice according to different liquid flow rates and liquid level requirements, and has wide applicability and flexibility.

[0079] Furthermore, the numerical simulation calculation method for the liquid flow rate of a single overflow pipe includes: determining the calculation region, boundary conditions, governing equations and initial conditions; and simulating the flow process of liquid through overflow hole 6 using a gas-liquid interface capture method and a velocity-pressure coupling solution algorithm to obtain the calculation formula for the liquid flow rate of a single overflow pipe.

[0080] Figure 4 This is a schematic diagram of the computational region provided in an embodiment of the present invention, such as... Figure 4 As shown, the computational region is the area formed by the upper surface 11 of the distribution plate, the virtual wall 12, the virtual inlet 13, the overflow hole 6, and the overflow pipe 5. This region forms a virtual pool 16. The virtual wall 12 is for facilitating the simulation of a hypothetical wall, and the virtual inlet 13 is also for facilitating the simulation of a hypothetical inlet.

[0081] Furthermore, the boundary conditions include: wall boundary conditions, pressure inlet boundary conditions, and pressure outlet boundary conditions. Specifically, the wall boundary conditions include the upper surface 11 of the distribution plate, the virtual wall 12, and the outer wall 14 of the overflow pipe; the pressure inlet boundary conditions include the virtual inlet 13; and the pressure outlet boundary conditions include the overflow pipe outlet 15.

[0082] Furthermore, the governing equations include the volume fraction transport equation, the continuity equation, and the momentum equation.

[0083] The volume fraction transport equation is as follows:

[0084]

[0085] The continuity equation is:

[0086]

[0087] The momentum equation is:

[0088]

[0089] ρ(θ)=K(θ)ρ g +(1-K(θ))ρ l

[0090] μ(θ)=K(θ)μ g +(1-K(θ))μ l

[0091]

[0092] Where α is the volume fraction, representing the ratio of liquid volume to the volume of the unit. The spatial distribution of the volume fraction determines the specific location and shape of the interface between the two phases; U is the two-phase velocity of gas and liquid within the computational region, in m / s; p is the pressure of gas and liquid within the computational region, in Pa; t is time, in s; θ is the signed distance function, in m; and ρ(θ) is the two-phase density of gas and liquid within the computational region, in kg / m³. 3 ;ρ g To calculate the gas phase density of the gas within the region, the unit is kg / m³. 3 ;ρ l To calculate the liquid phase density of the liquid within the region, the unit is kg / m³. 3 μ(θ) is the two-phase dynamic viscosity of the gas and liquid in the calculation region, in Pa·s; g To calculate the gas phase dynamic viscosity of the gas within the region, the unit is Pa·s; μ l To calculate the dynamic viscosity of the liquid phase within the region, the unit is Pa·s; K(θ) is the Heaviside function; F s (θ) represents the surface tension of the liquid at the interface between the two phases, in N / m. 3 σ is the surface tension coefficient of the liquid at the two-phase interface, in N / m; κ(θ) is the interfacial curvature of the liquid at the two-phase interface, in 1 / m; δ(θ) is the Dirac distribution function.

[0093] After establishing the control equations, the initial conditions are determined. In one embodiment of the present invention, the initial conditions include: two-phase velocity U = 0; within the virtual pool 16, the space below the liquid surface α = 1, the space above the liquid surface α = 0, and the space inside the overflow pipe α = 0.

[0094] Furthermore, the flow process of liquid through overflow hole 6 is simulated using a gas-liquid interface capture method and a velocity-pressure coupled solution algorithm. The formula for calculating the liquid flow rate of a single overflow pipe is obtained by: simultaneously using the VOSET method in the gas-liquid interface capture method and the IDEAL algorithm in the velocity-pressure coupled solution algorithm to solve the governing equations, simulating the flow process of liquid through overflow hole 6, and obtaining the two-phase velocity U; and based on the two-phase velocity U, the liquid flow rate of a single overflow pipe is obtained by calculating the flow rate at the middle cross section of overflow hole 6. The formula for calculating the liquid flow rate of a single overflow pipe is as follows:

[0095]

[0096] Among them, Q s U represents the liquid flow rate of a single overflow pipe. i Let A be the two-phase velocity U at the grid on the cross-section of the overflow orifice. i1000×3600 represents the area of ​​the grid on the central cross-section of the overflow orifice, where M is the total number of grids on the central cross-section of the overflow orifice. 1000×3600 indicates the flow rate in cubic meters (m³). 3 / s is converted to L / h.

[0097] The volume fraction transport equation corresponds to the gas-liquid interface capture method, while the continuity and momentum equations correspond to the velocity-pressure coupled solution algorithm. By simultaneously using the two methods to solve the governing equations, the two-phase velocity U can be obtained, and the position and shape of the gas-liquid interface can also be obtained based on α. ​​In the method proposed in this invention, only the value of the two-phase velocity U needs to be collected to obtain the two-phase velocity U at the grid on the middle cross-section of the overflow orifice. i .

[0098] Furthermore, based on the numerical simulation calculation method for the liquid flow rate, Q is obtained. s The -H characteristic curve formula includes: adjusting the calculation area according to the preset first overflow orifice diameter; adjusting the initial conditions according to multiple preset different liquid level heights; after each adjustment, simulating and calculating the liquid flow rate of the single overflow pipe at the corresponding liquid level height using the numerical simulation calculation method of the liquid flow rate of the single overflow pipe; and fitting the multiple preset different liquid level heights and the liquid flow rate of the single overflow pipe at the corresponding liquid level heights to obtain Q. s -H characteristic curve formula, the Q s The formula for the -H characteristic curve is:

[0099] Q s =mH k

[0100] Where m and k are constants obtained by fitting the results of simulation calculations.

[0101] When performing numerical simulation calculations, the size of the first overflow hole diameter will affect the calculation area, and the liquid level height will affect the position of the liquid surface in the initial conditions. Therefore, by adjusting the diameter of the overflow hole 6 or the liquid level height, different characteristic curve formulas can be obtained.

[0102] Furthermore, determining the diameter of the overflow hole 6 based on the liquid level height at the rated liquid flow rate includes the following steps S31-S32.

[0103] Step S31: Determine whether the liquid level height at the rated liquid flow rate is within the preset height range.

[0104] Step S32: If yes, the diameter of the overflow hole 6 is determined to be the pre-set first overflow hole diameter; if no, the following steps S321 or S322 are executed.

[0105] Step S321: If the liquid level height at the rated liquid flow rate is less than the preset height range, the diameter of the first overflow hole is reduced by a first preset ratio. Based on the new first overflow hole diameter and the numerical simulation calculation method of the liquid flow rate, the liquid level height at the rated liquid flow rate is recalculated, and the process returns to step S31.

[0106] Step S322: If the liquid level height at the rated liquid flow rate is greater than the preset height range, the diameter of the first overflow hole is increased by a second preset ratio. Based on the new first overflow hole diameter and the numerical simulation calculation method of the liquid flow rate, the liquid level height at the rated liquid flow rate is recalculated, and the process returns to step S31.

[0107] By continuously adjusting the diameter of the first overflow hole through steps S31-S32, the diameter of the overflow hole 6 is obtained so that the liquid level height conforms to the preset height range.

[0108] Specifically, the preset height range is 10mm≤H≤50mm, the first preset ratio is 10%, and the second preset ratio is 10%.

[0109] In an embodiment of the present invention, if the rated liquid flow rate Q s’ When the lower liquid level height H is less than 10 mm, liquid surface fluctuations will cause instability in the flow rate at the overflow orifice. In this case, it is necessary to reduce the overflow orifice diameter by 10% and then refit Q based on numerical simulation. s -H characteristic curve formula, and calculate the liquid level height at rated liquid flow rate; if the liquid level height H>50mm, it will result in too much liquid in the distributor, increasing the weight of the equipment. In this case, the overflow orifice diameter needs to be increased by 10%, and then Q is refitted based on numerical simulation calculation method. s -H characteristic curve formula, and calculate the liquid level height at rated liquid flow rate.

[0110] Furthermore, the first height a is 30mm≤a≤50mm to prevent the upper surface 11 of the distribution plate from affecting the overflow process.

[0111] Furthermore, the second height b is:

[0112] b = H o +x

[0113] Among them, H o The liquid level is the height at the rated liquid flow rate, and x is the preset adjustment value, 10mm≤x≤50mm. This setting effectively prevents liquid from flowing in or splashing from the top of the overflow pipe 5.

[0114] Furthermore, based on the pre-set difference in liquid distribution, the allowable deviation in the installation height of overflow pipe 5 is calculated, including:

[0115]

[0116] Where ε is the allowable deviation of the installation height of overflow pipe 5, z is the difference in liquid distribution, and 0≤z≤5%.

[0117] In addition, by specifying the allowable deviation of the installation height of the overflow pipe 5, the difference in liquid distribution in each area unit on the surface of the packing section can be controlled independently.

[0118] Secondly, such as Figure 2 and Figure 3 As shown, the present invention also provides a fine microfluidic tubular liquid distributor, which is designed using any of the fine microfluidic tubular liquid distributor design methods described in the present invention.

[0119] Figure 5 This is a schematic diagram of the design process of the fine microfluidic tubular liquid distributor provided in the embodiment of the present invention, as shown below. Figure 5 As shown, the design primarily focuses on the structural dimensions of the overflow assembly. In this embodiment, the liquid working fluid's physical properties are: liquid phase density ρ l = 933.71 kg / m 3 Liquid phase dynamic viscosity μ l =8.56×10 -3 Pa·s, gas phase density ρ g =3.92kg / m 3 Gas phase dynamic viscosity μ g =1.24×10 -4 Pa·s, surface tension coefficient σ=0.0275N / m; total rated liquid flow rate Q=478.95L / h; based on the required packing section area under rated flow rate, the area of ​​distribution plate 4 was determined to be 1.13m². 2 The required spray point density for the packing section is 430 points / m². 2 The design steps are as follows:

[0120] Step S101: Determine the number N of overflow pipes 5 based on the density requirements of the spray points in the packing section.

[0121] The number of overflow pipes 5, N = spray point density × area of ​​distribution plate 4 = 430 × 1.13 = 486 pipes.

[0122] Step S102: Based on engineering practice and structural strength requirements, determine the outer diameter φ, wall thickness δ, thickness h of distribution plate 4, and first height a of overflow pipe 5.

[0123] In this embodiment, the outer diameter φ of the overflow pipe 5 is 10mm, the wall thickness δ of the overflow pipe 5 is 2mm, and the thickness h of the distribution plate 4 is 50mm.

[0124] To prevent the upper surface 11 of the distribution plate from affecting the overflow process, the first height a is set to 50 mm.

[0125] Step S103: Taking a single overflow pipe as the research object, the computational domain, governing equations, boundary conditions, and initial conditions are determined. The gas-liquid interface capture method and velocity-pressure coupled solution algorithm are used to simulate the flow process of liquid through overflow hole 6, and a method for calculating the liquid flow rate Q of a single overflow pipe is developed. s Numerical simulation calculation methods.

[0126] The calculation area is as follows Figure 4 As shown, the computational region is the area formed by the upper surface 11 of the distribution plate, the virtual wall 12, the virtual inlet 13, the overflow hole 6, and the overflow pipe 5. The governing equations include the volume fraction transport equation, the continuity equation, and the momentum equation. Boundary conditions include wall boundary conditions, pressure inlet boundary conditions, and pressure outlet boundary conditions. Specifically, the wall boundary conditions include the upper surface 11 of the distribution plate, the virtual wall 12, and the outer wall 14 of the overflow pipe; the pressure inlet boundary conditions include the virtual inlet 13; and the pressure outlet boundary conditions include the overflow pipe outlet 15. Initial conditions include a two-phase velocity U = 0; within the virtual pool 16, the space below the liquid surface α = 1, the space above the liquid surface α = 0, and the space inside the overflow pipe α = 0.

[0127] After determining the above conditions, the VOSET method in the gas-liquid interface capture method is used to solve the volume fraction transport equation. The shape and position of the gas-liquid interface are obtained through the value of α, and the sign distance function θ in the momentum equation is obtained. The IDEAL algorithm in the velocity-pressure coupling solution algorithm is used to solve the continuity equation and the momentum equation to obtain the two-phase velocity U and pressure p.

[0128] Based on the two-phase velocity U obtained from the solution, the liquid flow rate Q of a single overflow pipe is obtained by calculating the flow rate at the middle cross-section of the overflow orifice. s .

[0129]

[0130] Step S104: Using the numerical simulation calculation method of step S103, with the overflow hole 6 being a preset first overflow hole diameter d h Under the condition of different liquid level heights H, the liquid flow rate Q of a single overflow pipe is calculated. s By fitting these simulation results, Q is obtained. s -H characteristic curve formula.

[0131] In this implementation example, the diameter d of the first overflow hole is set. h=1mm. Based on this condition, the numerical simulation method in step S103 is used to calculate the liquid level height H = 15mm, 20mm, 30mm, 40mm, 60mm, 80mm, and 100mm. Figure 6 This is a schematic diagram of the flow process of the liquid working medium through the overflow hole at different liquid level heights H provided in the embodiments of the present invention. Table 1 shows the liquid flow rate Q of a single overflow pipe at different liquid level heights H. s See the simulation results. Figure 6 The simulation results are fitted to Table 1.

[0132] Table 1. Liquid flow rate Q of a single overflow pipe at different liquid levels H. s

[0133]

[0134] Figure 7 Q is provided in the embodiments of the present invention. s -H characteristic curve diagram, by fitting the above simulation results, as shown Figure 7 Q shown s -H characteristic curve, corresponding Q s The formula for the -H characteristic curve is:

[0135] Q s =0.064H 0.754

[0136] Step S105: Based on Q s The H characteristic curve formula is used to calculate the liquid flow rate of a single overflow pipe as the rated liquid flow rate Q. s’ Liquid level height H at that time o .

[0137] Rated liquid flow rate Q of a single overflow pipe s’ The following calculations were performed using the total rated liquid flow rate Q and the number N of overflow pipes 5:

[0138]

[0139] Based on Q s The H characteristic curve formula is used to calculate the liquid flow rate of a single overflow pipe as the rated liquid flow rate Q. s’ Liquid level height H at that time o :

[0140]

[0141] Step S106: If the liquid level height H o If the diameter is between 10mm and 50mm, then the preset diameter of the first overflow hole is d. h The requirements are met, and at this point, the diameter of overflow hole 6 is determined to be d.h .

[0142] In this implementation case, the liquid level height H o =37.6mm, which is between 10 and 50mm. Therefore, the diameter of the first overflow hole meets the requirements, and the diameter of overflow hole 6 is determined to be d. h =1mm.

[0143] Step S107: Based on the rated liquid flow rate Q s’ Liquid level height H at that time o Determine the second height b between the top of the overflow pipe 5 and the upper edge of the overflow hole 6.

[0144] To prevent liquid from flowing in or splashing from the top of the overflow pipe 5, the second height b between the top of the overflow pipe 5 and the upper edge of the overflow hole 6 is 50 mm.

[0145] Step S108: For Q s The derivative of the -H characteristic curve formula was used, and the allowable deviation ε of the installation height of the overflow pipe 5 was calculated under the requirement that the difference in liquid distribution should be ≤5%.

[0146] In this implementation case, the allowable deviation ε for the installation height of overflow pipe 5 is:

[0147]

[0148] To demonstrate the accuracy of the numerical simulation method provided by this invention, experiments were conducted using water and methanol as working fluids to obtain the water flow rate through a single overflow pipe at different liquid levels. Figure 8 This is a schematic diagram illustrating the simulation and experimental results of water flow rate in a single overflow pipe at different liquid levels, provided in an embodiment of the present invention. Figure 9 This is a schematic diagram illustrating the simulation and experimental results of methanol flow rate in a single overflow pipe at different liquid levels, as provided in this embodiment of the invention. Figure 8 and Figure 9 As shown, the maximum deviation between the simulation results and the experimental results is less than 9%, verifying the accuracy of the numerical simulation calculation method provided by this invention. Based on this numerical simulation calculation method, accurate prediction of liquid level height can be achieved, thereby enabling precise design of the overflow orifice diameter and the second height from the top of the overflow pipe to the upper edge of the overflow orifice.

[0149] The method proposed in this invention also incorporates engineering practice and structural strength requirements to determine the outer diameter and wall thickness of the overflow pipe, the thickness of the distribution plate, the initial height of the lower edge of the overflow hole from the upper surface of the distribution plate, and the allowable deviation of the overflow pipe installation height, thereby achieving accurate and reasonable design of a fine microfluidic pipe-type liquid distributor. Furthermore, this method is applicable to any liquid working fluid and any rated flow rate, exhibiting broad versatility.

[0150] This invention provides a storage medium storing a program that, when executed by a processor, implements the design method for the fine microfluidic pipe liquid distributor.

[0151] This invention provides a processor for running a program, wherein the program executes the fine microfluidic pipe liquid distributor design method during runtime.

[0152] This invention provides a device including a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps of the fine microfluidic pipe-type liquid distributor design method. The device described herein can be a server, PC, PAD, mobile phone, etc.

[0153] This application also provides a computer program product that, when executed on a data processing device, is adapted to execute a program that initializes the design method of the fine microfluidic tubular liquid distributor.

[0154] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0155] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0156] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0157] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0158] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0159] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0160] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0161] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0162] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A design method for a fine microfluidic pipe-type liquid distributor, characterized in that, The method includes: The number of overflow pipes is determined based on the required spray point density of the packing section; Based on engineering practice and structural strength requirements, determine the outer diameter of the overflow pipe, the wall thickness, the thickness of the distribution plate, and the first height of the lower edge of the overflow hole from the upper surface of the distribution plate. Taking a single overflow pipe as the research object, the liquid level height is calculated through numerical simulation to determine the diameter of the overflow hole and the second height from the top of the overflow pipe to the upper edge of the overflow hole; Based on the pre-set difference in liquid distribution, the allowable deviation of the overflow pipe installation height is calculated; and The fine microfluidic tubular liquid distributor is designed based on the number of overflow pipes, the outer diameter and wall thickness of the overflow pipes, the thickness of the distribution plate, the diameter of the overflow hole, the first height, the second height, and the allowable deviation of the installation height.

2. The method according to claim 1, characterized in that, Taking a single overflow pipe as the research object, the liquid level height is calculated through numerical simulation to determine the diameter of the overflow orifice, including: A numerical simulation method for calculating the liquid flow rate of a single overflow pipe is used as the research object. Based on the numerical simulation calculation method for the liquid flow rate, Q is obtained. s -H characteristic curve formula, where Q s Here, H represents the liquid flow rate of a single overflow pipe, and H represents the liquid level height. Based on the Q s The -H characteristic curve formula yields the liquid level height when the flow rate of a single overflow pipe is the rated liquid flow rate; and The diameter of the overflow orifice is determined based on the liquid level height at the rated liquid flow rate.

3. The method according to claim 2, characterized in that, The numerical simulation calculation method for the liquid flow rate of the single overflow pipe includes: Determine the computational domain, boundary conditions, governing equations, and initial conditions; and The flow process of liquid through the overflow hole is simulated by using a gas-liquid interface capture method and a velocity-pressure coupling solution algorithm, and the calculation formula of liquid flow rate of a single overflow pipe is obtained.

4. The method according to claim 3, characterized in that, The calculation area is the area formed by the upper surface of the distribution plate, the virtual wall, the virtual inlet, the overflow hole, and the overflow pipe.

5. The method according to claim 3, characterized in that, The boundary conditions include: wall boundary conditions, pressure inlet boundary conditions, and pressure outlet boundary conditions. The wall boundary conditions include the upper surface of the distribution plate, the virtual wall, and the outer wall of the overflow pipe; the pressure inlet boundary conditions include the virtual inlet; and the pressure outlet boundary conditions include the overflow pipe outlet.

6. The method according to claim 3, characterized in that, The governing equations include the volume fraction transport equation, the continuity equation, and the momentum equation. The volume fraction transport equation is as follows: The continuity equation is: The momentum equation is: ρ(θ)=K(θ)ρ g +(1-K(θ))ρ l μ(θ)=K(θ)μ g +(1-K(θ))μ l Where α is the volume fraction, representing the ratio of liquid to the volume of the unit, U is the two-phase velocity of gas and liquid within the computational region, p is the pressure of gas and liquid within the computational region, t is time, θ is the sign distance function, ρ(θ) is the two-phase density of gas and liquid within the computational region, and ρ g To calculate the gas phase density of the gas within the region, ρ l To calculate the liquid phase density of the liquid within the calculation region, μ(θ) represents the two-phase dynamic viscosity of the gas and liquid within the calculation region. g To calculate the gas phase dynamic viscosity of the gas in the region, μ l To calculate the liquid phase dynamic viscosity of the liquid within the region, K(θ) is the Heaviside function, F s σ(θ) is the surface tension of the liquid at the two-phase interface, σ is the surface tension coefficient of the liquid at the two-phase interface, κ(θ) is the interface curvature of the liquid at the two-phase interface, and δ(θ) is the Dirac distribution function.

7. The method according to claim 6, characterized in that, The initial conditions include: Two-phase velocity U = 0; In the virtual pool, the space below the liquid surface is α=1, the space above the liquid surface is α=0, and the space inside the overflow pipe is α=0.

8. The method according to claim 6, characterized in that, The flow process of liquid through an overflow orifice is simulated using a gas-liquid interface capture method and a velocity-pressure coupled solution algorithm. The calculation formula for the liquid flow rate of a single overflow pipe is as follows: The governing equations are solved by combining the VOSET method from the gas-liquid interface capture method with the IDEAL algorithm from the velocity-pressure coupled solution algorithm, simulating the flow process of liquid through the overflow orifice to obtain the two-phase velocity U; and Based on the two-phase velocity U, the liquid flow rate of a single overflow pipe is obtained by calculating the flow rate at the middle cross-section of the overflow orifice. The formula for calculating the liquid flow rate of a single overflow pipe is as follows: Among them, Q s U represents the liquid flow rate of a single overflow pipe. i Let A be the two-phase velocity U at the grid on the cross-section of the overflow orifice. i Let M be the area of ​​the grid on the cross-section of the overflow orifice, and M be the total number of grids on the cross-section of the overflow orifice.

9. The method according to claim 3, characterized in that, Based on the numerical simulation calculation method for the liquid flow rate, Q is obtained. s The formula for the -H characteristic curve includes: Adjust the calculation area according to the preset diameter of the first overflow hole; Based on multiple preset liquid level heights, the initial conditions are adjusted. After each adjustment, the liquid flow rate of the single overflow pipe at the corresponding liquid level height is simulated and calculated using a numerical simulation method for the liquid flow rate of the single overflow pipe. By fitting multiple preset liquid level heights with the liquid flow rate of a single overflow pipe at the corresponding liquid level height, Q is obtained. s -H characteristic curve formula, the Q s The formula for the -H characteristic curve is: Q s =mH k Where m and k are constants obtained by fitting the results of simulation calculations.

10. The method according to claim 9, characterized in that, Determining the diameter of the overflow orifice based on the liquid level height at the rated liquid flow rate includes: Determine whether the liquid level is within a preset height range at the rated liquid flow rate; and If yes, then the diameter of the overflow orifice is set to a preset first overflow orifice diameter; otherwise, the following operations are performed until the liquid level at the rated liquid flow rate is within a preset height range, and the diameter of the overflow orifice is set to a new first overflow orifice diameter: If the liquid level at the rated liquid flow rate is less than a preset height range, the diameter of the first overflow hole is reduced by a first preset ratio, and the liquid level at the rated liquid flow rate is recalculated based on the new first overflow hole diameter and the numerical simulation calculation method of the liquid flow rate. If the liquid level at the rated liquid flow rate is greater than a preset height range, the diameter of the first overflow hole is increased by a second preset ratio, and the liquid level at the rated liquid flow rate is recalculated based on the new first overflow hole diameter and the numerical simulation calculation method of the liquid flow rate.

11. The method according to claim 10, characterized in that, The preset height range is 10mm≤H≤50mm, the first preset ratio is 10%, and the second preset ratio is 10%.

12. The method according to claim 1, characterized in that, The first height 'a' is 30mm ≤ a ≤ 50mm.

13. The method according to claim 1, characterized in that, The second height b is: b=H o +x Among them, H o The liquid level is the height at the rated liquid flow rate, and x is the preset adjustment value, 10mm≤x≤50mm.

14. The method according to claim 1, characterized in that, Based on the pre-set difference in liquid distribution, the allowable deviation of the overflow pipe installation height is calculated to include: Where ε is the allowable deviation of the overflow pipe installation height, z is the difference in liquid distribution, and 0≤z≤5%.

15. A fine microfluidic tubular liquid distributor, characterized in that, The fine microfluidic tubular liquid distributor is designed using the method described in any one of claims 1-14.

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