20 results about "Bubble nucleation" patented technology

This invention relates to the field of ultra-precision polishing technology, specifically to an ultrasonic cavitation microjet polishing module for polishing microstructures. The module includes an acoustic focusing nozzle, a center-penetrating piezoelectric transducer, an adaptive acoustic impedance frequency tracking system, and a liquid supply and bubble nucleation system. The acoustic focusing nozzle employs a variable cross-section acoustic amplitude rod structure, ensuring that the standing wave antinodes and nozzle outlet are confocal, thus increasing energy density. The piezoelectric transducer has a ring structure with fluid flowing through its center, achieving efficient energy conversion. The frequency tracking system adjusts the excitation frequency in real time to maintain resonance. The liquid supply system introduces cavitation nuclei through a venturi tube, reducing the cavitation threshold. This invention, through an acoustic-fluid coupling mechanism, utilizes the dual effects of macroscopic kinetic energy removal and microscopic cavitation removal to solve the problems of traditional polishing techniques, such as difficulty in processing high aspect ratio microstructures, incomplete bottom polishing, and low efficiency. It achieves high-precision polishing of microstructure surfaces, and is particularly suitable for ultra-precision machining of deep and narrow grooves.

The utility model relates to a nanobubble preparation device based on a resistance thermal effect. The nanobubble preparation device based on the resistance heat effect comprises a box body, the bottom of the box body is fixedly connected with two fixing plates which are arranged in parallel at intervals, the opposite side faces of the two fixing plates are each provided with a plurality of inserting grooves which are distributed at equal intervals in the length direction, and the inserting grooves in the two sides are distributed in a mirror symmetry mode to jointly form a positioning groove of a heat production resistor; the two ends of each heat generation resistor are embedded in the corresponding positioning grooves respectively, a composite heat conduction coating layer is arranged on the surface of each heat generation resistor, the composite heat conduction coating layers are formed by aluminum foil and tin foil in a composite lamination mode and tightly wrap the outer surfaces of the heat generation resistors, and micron-scale channels or nano-scale holes are formed in the surfaces of the composite heat conduction coating layers through laser etching. Therefore, bubble nucleation is promoted. The nanobubble preparation device based on the resistance thermal effect solves the problems of low nanobubble generation efficiency, non-uniform size, poor stability and the like in the prior art.

A two-phase immersion cooling system includes a work tank, a device to be cooled, and a heat conduction device. The work tank has a vapor section and a liquid-phase section to contain a liquid-phase working fluid. At least one portion of the device to be cooled is in the vapor section. The heat conduction device including a heat conduction element and a boiling-assisting structure has a closed space to contain a heat conduction fluid to have the heat conduction fluid flow inside the closed space. The heat conduction element has a first section in the liquid-phase section and a second section connected to the at least one portion of the device to be cooled. The boiling-assisting structure is connected to the first section and exposed to the liquid-phase section of the work tank, thereby causing bubble nucleation at a heterogeneous interface between the boiling-assisting structure and the liquid-phase working fluid.

The invention relates to an immersed liquid cooling device and method, and relates to the technical field of thermal management and electronic cooling. Comprising a closed cavity, an electronic element, a phase change material layer and a condensation piece, the closed cavity is filled with dielectric cooling liquid, the phase change material layer is loaded on the surface of the electronic element, and the superheat degree needed by bubble nucleation is remarkably reduced through the combined action of heat absorption and phase change of the phase change layer; a large number of effective nucleation sites are formed on the heating surface, so that bubbles are generated more easily, bubble merging is reduced, and bubble separation and updating are promoted; the phase change material layer maintains more stable nucleate boiling under medium-high heat flow, the porous structure not only can improve the average heat transfer coefficient, but also can absorb cold fluid through the capillary force effect to form heat convection to delay local dry spot formation, higher boiling heat exchange intensity is achieved, and boiling enhancement and heat flux density improvement are achieved.

The present application relates to the field of micro-nano fluid, in particular to a cavitation bubble periodic generation method based on laser plasmon effect. The method uses continuous wave laser in plasmon resonance wave band, which is focused by a microscope objective and irradiated to the surface of a fused quartz sample covered with noble metal nanoparticles placed in liquid water environment; the laser spot is positioned near the solid object on the sample surface in advance, and the laser is turned on, the laser with power exceeding the threshold value will induce micron-scale cavitation bubble nucleation, growth and collapse at the laser spot position; the solid object near the laser spot as the flow field boundary will make the bubble produce movement towards the solid object during the collapse process, so that the bubble nucleus after collapse is pinned out of the laser spot area; the laser spot area is covered by liquid again, and under the condition of continuous laser energy input, cavitation bubble nucleation can be induced again at the laser spot position, thus forming a high-frequency, periodic cavitation bubble nucleation, growth and collapse process. The operation of the present application to realize the periodic generation of cavitation bubbles is very simple and easy to realize, can produce strong disturbance to the local fluid, and can realize the control of the generation frequency, size, periodic generation area range size of cavitation bubbles.

This invention relates to the field of heat flux technology and provides a novel wall heat flux partitioning model based on bubble merging behavior and the evaporation region. Spatially, the model divides the wall into a non-bubble-affected region, a nucleation point region, a bubble sliding region, and an evaporation region. Temporally, it divides the bubble nucleation cycle into bubble waiting time and bubble generation time, and the bubble sliding cycle into transient heat transfer-dominated time and one-way convective heat transfer-dominated time. Based on this spatiotemporal partitioning, the total wall heat flux is composed of quenching heat transfer caused by bubbles leaving the nucleation point, transient heat transfer caused by sliding bubbles, evaporation heat transfer during bubble growth, one-way convective heat transfer in the non-bubble-affected region, and steam heat transfer in the evaporation region. The total wall heat flux is expressed as: [Formula omitted for brevity]. This model can accurately predict the wall heat flux during the nucleation boiling stage and successfully predict the occurrence of the critical heat flux density.

The invention relates to the technical field of display screen packaging, in particular to a full-lamination packaging process and dispensing equipment for a COB integrated packaging LED display screen, and the full-lamination packaging process comprises the steps: placing a COB substrate after die bonding into a cavity, and obtaining three-dimensional topological data and environmental parameters of a chip array; executing multi-stage gradient air exhaust and applying dual-frequency ultrasonic pretreatment, activating surface energy and removing adsorbed gas; in a vacuum state, dispensing is carried out based on three-dimensional data, a colloid volume expansion rate and a bubble nucleation critical pressure difference threshold value are calculated in real time by utilizing a dynamic rheological pressure coupling model, dispensing pressure and speed are dynamically and reversely compensated, and it is ensured that colloid tensile stress is lower than a critical value; the in-situ optical detection unit is used for scanning and recognizing micron-sized bubbles or missing in real time, and the Z-axis height and the glue output amount of a subsequent dispensing path are fed back and corrected; and finally, a nonlinear variable-voltage oscillation program is executed to induce micro-bubble resonance fracture and solidification, so that the bubble defect in the packaging process is effectively eliminated, and the product yield is improved.

This invention relates to the field of aluminum foam technology and discloses a method for preparing highly uniform aluminum foam by blowing, comprising the following steps: (1) raw material preparation; (2) smelting treatment; (3) setting up the blowing device; (4) blowing and foaming; (5) cooling and molding; (6) post-treatment. This invention achieves full-process control from bubble nucleation, growth, shaping to finished product molding through the synergistic matching of raw material pretreatment, composite foam stabilization, combined stirring, bubble homogenization, segmented cooling and post-treatment, significantly improving the uniformity and comprehensive performance of aluminum foam. The solution of this invention fundamentally solves the problems of uneven bubble cell size, low closed-cell rate, fluctuating mechanical properties and large dimensional deviation in the traditional blowing method through the synergistic effect of each step and parameter, and finally obtains highly uniform aluminum foam with uniform bubble cell size, excellent mechanical properties, high dimensional accuracy and good appearance quality, meeting the needs of high-end application scenarios.

The invention relates to the technical field of heat dissipation of electronic devices, in particular to a dot matrix type super-hydrophilic-super-hydrophobic mixed wetting surface for strengthening boiling heat transfer and a preparation method of the dot matrix type super-hydrophilic-super-hydrophobic mixed wetting surface. According to the dot matrix type super-hydrophilic-super-hydrophobic mixed wetting surface, a super-hydrophilic surface with a CuO micro-nano sheet thorn structure is constructed and formed on the surface of a copper substrate through a chemical oxidation method, and a super-hydrophobic dot matrix surface is prepared on the super-hydrophilic surface by spraying a super-hydrophobic coating and used for increasing bubble nucleation sites and accelerating supply of liquid to the bubble nucleation sites, so that the number of bubble nucleation sites is increased. Bubble combination is inhibited; the super-hydrophobic dot matrix surface is obtained by discretely arranging hexagonal dot matrix units; the contact angle of the surface of the super-hydrophobic dot matrix is not less than 160 degrees; and the contact angle of the super-hydrophilic surface is 0-10 degrees. Hexagonal dot matrix units are discretely distributed on a super-hydrophilic surface of a CuO micro-nano sheet thorn structure to form a super-hydrophobic dot matrix surface; the technical problem that the boiling heat transfer coefficient and the critical heat flux of an existing boiling heat transfer surface are difficult to consider at the same time is solved.

The invention discloses a radioactive drug subpackaging device and method, and relates to the field of biological medicines.The subpackaging method comprises the following steps that S1, drugs are extracted at the flow speed of 0.8 mL / s and used for rapidly establishing a stable flow field and inhibiting surfactant adsorption and bubble nucleation; s2, the flow speed is smoothly transited to 0.3 mL / s from 0.8 mL / s, and the medicine is extracted at the flow speed of 0.3 mL / s to be used for promoting breakage of generated bubbles; and S3, the medicine is extracted in a pulse mode, the pulse mode comprises extraction at the flow speed of 1.2 mL / s for 80 ms, then extraction is paused for 40 ms, and the pulse operation is repeated until the total subpackaging amount is completed so as to be used for flushing residual bubbles. The three-stage dynamic coupling flow velocity time sequence chain is adopted, so that full automation of bubble suppression is achieved, bubble control can be completed without interrupting the process, the continuity and reliability of subpackaging operation are effectively improved, and process interruption and operation accidents caused by bubbles are reduced.

The present application relates to the technical field of power transformer manufacturing and insulation processing, in particular to a transformer vacuum oil injection and hot oil circulation integrated pipeline device and method; the device comprises a main oil tank, a vacuum pump, a main circulating pump, a coaxial antagonistic Helmholtz self-leveling pipeline and a fluid oscillator; the system combines three-dimensional immersion saturation gradient to judge fluid equivalent stiffness, thereby dynamically adjusting pulsation frequency and air extraction pulse width; the core is to make transformer oil generate self-excitation high-frequency pulsation field through the fluid oscillator and coanda effect flow channel, and to realize rapid penetration in the positive pressure period and micro-bubble separation in the negative pressure period by using high-frequency positive and negative pressure alternation; the present application does not simply rely on the traditional way of static pressure, breaks the surface tension of capillary pores and suppresses local bubble nucleation, effectively solves the problems of micro-bubble retention and insufficient deep penetration, and improves the immersion efficiency and uniformity.

The application discloses a kind of porous structure's hollow glass microsphere precursor microparticle preparation and application, comprising: mixing silica sol with water, then under magnetic stirring, add water glass, obtain mixed solution;Metal acetate and boric acid are dissolved into saturated aqueous solution, under magnetic stirring, add to mixed solution, with acetic acid adjustment pH, obtain white emulsion, after stirring by homogenizer, carry out spray drying, obtain porous structure's hollow glass microsphere precursor microparticle.The microporous of porous structure's hollow glass microsphere precursor microparticle inside has been replaced with the bubble nucleation process of microparticle in the process of foaming into ball in the process of foaming into ball, shorten foaming into ball time, eliminate the bubble that ball wall is not coalesced, reduce the particle of incomplete foaming, improve the yield and performance of hollow glass microsphere.The application uses crosslinking incomplete silica sol as raw material, with chemical bonding replaces the traditional soft chemical method preparation microparticle's cohesive aggregation, enhances the pressure strength of precursor microparticle.

The CO2 bubble nucleation and ripening process in-situ observation device and method based on nano CT belongs to the technical field of porous medium in-situ imaging. The device comprises a nano CT scanning device, a high temperature and high pressure reaction kettle, a CO2-saline pre-equilibrium and injection unit, a pressure control unit, a temperature control unit, a pipeline bundling and rotating adaptation unit, a synchronous data acquisition unit and an image analysis unit. During the experiment, the CO2 saturated liquid or residual CO2 occurrence state is established, then the bubble nucleation is induced by pressure reduction or fluid displacement, and the time sequence CT scanning is carried out under the condition of no flow or controllable seepage, so as to obtain the parameters such as bubble volume, interface area, curvature, connectivity and ripening type. The application can be used for quantitatively revealing the CO2 bubble nucleation, Ostwald ripening, dissolution and stable residence mechanism under the temperature and pressure conditions of the reservoir.

The invention relates to the field of heat dissipation devices, and provides a phase change heat dissipation device. The phase change heat dissipation device comprises a sealed cavity, and the sealed cavity is provided with a heat transfer face used for making contact with a heat source, a working medium inlet and a working medium outlet. The macroscopic turbulent flow structure is arranged in the sealing cavity and is used for generating a transverse velocity component and a secondary flow in a working medium flowing through the sealing cavity so as to damage and reconstruct a near-wall boundary layer; and the microscopic nucleation structure is arranged on the heat transfer surface or the surface of the macroscopic turbulent flow structure and is used for providing bubble nucleation points. The phase change heat dissipation device can accelerate heat transfer, start nucleate boiling in advance, effectively meet the requirement for high-heat-flux heat dissipation and solve the problem that a traditional device is low in heat exchange efficiency. The limitation that a traditional phase change heat dissipation device is prone to failure under the high heat flux density is broken through, and the application range is expanded.

The utility model relates to the technical field of polyurethane, in particular to an observation device and an observation system for observing polyurethane bubble nucleation. The observation device comprises an annular sample holder for placing an observation sample, a heating device for heating the observation sample to promote nucleation and an optical device for observing the bubble nucleation process in the sample, and the annular sample holder is arranged in the heating device and is connected with the heating device; the optical device is arranged on one side of the annular sample holder and is used for observing the bubble nucleation process of the observation sample placed on the annular sample holder. According to the invention, the nucleation process of the polyurethane bubbles can be directly observed, then the nucleation capability of the foam stabilizer of a polyurethane system can be rapidly evaluated, and the foam stabilizing capability and functionality of the foam stabilizer can be judged by intuitively observing the mutual bubble merging process after the bubbles are formed and the final form.

The invention belongs to the technical field of additive manufacturing, and particularly discloses a high-temperature heat pipe with high bubble nucleation site density and an integrated preparation method of the high-temperature heat pipe. The high-temperature heat pipe is provided with a special liquid absorption core structure design aiming at the working principle of an evaporation section, and a liquid absorption core part is provided with a porous framework and an adhesion metal powder layer on the framework; and the pipe wall part of the high-temperature heat pipe is compact and free of pores and is tightly combined with the wick part. According to the preparation method provided by the invention, the adhesion metal powder layer can be uniformly formed on the surface of the porous framework of the liquid absorption core part, V-shaped grooves and edges formed between the metal powder and the framework provide a large number of bubble nucleation sites, the bubble surface energy is remarkably reduced, and the evaporation efficiency of the liquid working medium is greatly improved; and meanwhile, independent process parameter regulation and control are conducted on the compact pipe wall and the porous wick through the selective laser melting process, integrated forming of the heat pipe wall and the wick is achieved, interface thermal resistance can be reduced, and the heat transfer performance of the high-temperature heat pipe is further improved.

The invention relates to the field of fluid conveying and precision control, and discloses a circulating feeding and temperature control method for a high-viscosity fluid coating roller, a system takes a composite thermal field as a unique driving force, and the core of the system comprises a pipeline with a built-in thermal response high-thermal conductivity flexible composite lining, a distributed thermoelectric actuating unit array and a central controller. The controller calculates and applies a composite thermal field: firstly, a longitudinal traveling wave thermal field is utilized to drive the flexible lining to generate physical peristaltic waves, and mild non-contact pumping is realized; secondly, the local viscosity of fluid near the pipe wall is accurately regulated and controlled through a transverse static thermal field, and the parabola-shaped flow velocity profile is actively shaped into uniform plug flow; and finally, by utilizing a composite perturbation thermal field, migration is carried out through a thermophoresis effect, and bubble nucleation is inhibited on line. The functions of pumping, shaping and defoaming are highly integrated in the integrated static pipeline, no mechanical moving part exists, response is rapid, control is accurate, and the purity and uniformity of fluid conveying are remarkably improved.

The invention discloses a microsphere directional driving method and system based on wall cavitation bubbles. According to the method, laser is used for inducing cavitation of bubbles on a photothermal conversion substrate, and the sizes of the bubbles and the relative positions of the bubbles and silicon dioxide (SiO2) microspheres are regulated and controlled, so that an asymmetric flow field formed in the growth and collapse processes of the bubbles generates controllable thrust on the microspheres, and directional driving is realized. The method comprises the following steps: providing a photothermal conversion substrate and placing microspheres, irradiating a target position of the substrate by laser to generate cavitation bubbles, and adjusting the sizes of the bubbles and the distance between a bubble nucleation point and the microspheres to realize one-way or reciprocating motion of the microspheres. The system is composed of a laser device with energy adjustment and position regulation and control functions, a photothermal conversion substrate and microspheres on the surface of the photothermal conversion substrate. The device is driven based on fluid dynamics, is irrelevant to a microsphere material, is simple in structure, is easy to integrate, and is suitable for micro-nano scenes such as microfluidics, biological particle control, micro-assembly and the like.

This invention relates to the field of phase change heat transfer technology, and provides a capillary wick structure for a vapor chamber and its preparation method. First, a micron-scale array structure is prepared on the surface of a metal substrate at the bottom of the vapor chamber. Then, the surface of the metal substrate with the micron-scale array structure is oxidized. Subsequently, a carbon nanotube growth catalyst is loaded onto the surface of the metal substrate, and then vertically oriented carbon nanotubes are grown on the surface of the metal substrate via chemical vapor deposition. The capillary wick structure prepared by this invention can simultaneously increase the density of bubble nucleation sites and enhance capillary action, endowing the metal substrate with excellent phase change heat transfer performance.

The invention relates to the technical field of active noise reduction, and particularly provides an active noise reduction method for heating an electric kettle, which comprises the following steps of: in a heating process, acquiring real-time data representing a thermodynamic state of liquid in a container; judging the current heating stage of the liquid according to the real-time data, wherein the heating stage comprises a bubble nucleation dominant stage and a turbulence sensitive stage; in the bubble nucleation dominant stage, fluid dynamic intervention is executed, forced convection is generated in the container through a fluid driving device, and the fluid driving device is used for disturbing a thermal boundary layer at a heating interface; in the turbulence sensitive stage, the operation of the fluid driving assembly is inhibited, so that the disturbance of fluid circulation to the liquid boiling state is reduced; according to the active noise reduction method for heating of the electric kettle, fluid is driven to circulate across a heat area, and then the state of a heat boundary layer is dynamically regulated and controlled to restrain cavitation noise and turbulence noise in the liquid heating process.