A device for regulating the behavior and movement of condensation droplets by surface charge patterns

Abstract

The present invention proposes a device for regulating the movement of condensed droplets by surface charge patterns, characterized in that it comprises a device for generating ion wind, ITO glass and an insulating film, wherein the insulating film is attached to the conductive side of the ITO glass, the device for generating ion wind is vertically placed directly in front of the ITO glass, and the insulating film is provided with small holes arranged crosswise in an array. The present invention utilizes electrostatic force to generate a charge deposition effect on the surface of the insulating film, regulates the movement of condensed droplets by designing the shape of the PET film surface, strengthens the convergence and collection of surface water mist, and enables the droplets to reach the critical value of shedding faster by strengthening condensation, thereby better realizing operations such as water mist condensation, shedding and collection.

Description

Technical Field

[0001] The present invention belongs to the field of liquid microfluidic control, relates to the technical field of enhanced condensation heat exchange in thermal energy engineering, and specifically relates to a device for regulating the behavior and movement of condensation droplets using surface charge patterns. Background Art

[0002] Condensation is a common phenomenon in nature and industry. Enhanced condensation is widely used in industrial production such as water collection, seawater desalination, and nuclear industry. Many modern technologies require the control of droplet migration, such as condensation heat transfer, digital microfluidics, oil-water separation, and fog collection. In recent years, enhancing condensation by controlling the behavior of condensed droplets has received increasing attention. In the field of droplet microfluidics, how to overcome the resistance of microfluidics to complete various other complex movements and study the relationship between the contact angle of droplets and contact surfaces have become the main research content of scientists.

[0003] In the field of liquid control microfluidics at the nanoscale, this behavior is generally controlled in two ways: the first way is to improve the material or microstructure of the droplet bearing surface, and to achieve droplet control by changing the wettability of the droplet on the bearing surface; the other way is to control the droplet behavior by applying external force on a bearing surface with suitable wettability so that the droplet overcomes resistance. This invention mainly relies on the research ideas of Chinese and foreign scholars to regulate the behavior and movement of droplets by using the electrostatic force generated by the surface charge pattern to enhance the condensation heat exchange effect. Summary of the invention

[0004] The purpose of the present invention is to provide a method for utilizing electrostatic force to produce a charge deposition effect on the surface of a (PET) blue film, regulating the movement of condensed droplets by designing the shape of a specific insulating film surface, strengthening the convergence and collection of surface water mist, and making the droplets reach a critical value for shedding by strengthening condensation, thereby better realizing operations such as water mist condensation, shedding and collection.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A device for regulating the behavior and movement of condensed droplets by surface charge patterns, comprising a device for generating ion wind, ITO glass and an insulating film, wherein the insulating film is attached to the conductive side of the ITO glass, the device for generating ion wind is vertically placed in front of the ITO glass, and the insulating film is provided with small holes arranged in an array crosswise.

[0007] Furthermore, the ITO glass has one conductive surface and one insulating surface.

[0008] Furthermore, the device for generating ion wind comprises a high voltage power supply and a needle tip electrode, wherein the positive electrode of the high voltage power supply is connected to the needle tip, and the ground wire of the high voltage power supply is connected to the conductive side of the ITO glass.

[0009] Furthermore, a thermoelectric cooling sheet is provided on the back of the ITO glass.

[0010] Furthermore, the contact angle of the insulating film is 90-100°.

[0011] Furthermore, the outer dimensions of the small holes are larger than the outer dimensions of the droplets condensed on the insulating film.

[0012] Furthermore, the needle tip is 20 mm to 40 mm away from the ITO glass.

[0013] Furthermore, the voltage adjustment range of the high voltage power supply is 0-20KV.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] The present invention proposes ion wind air discharge, which causes charged particles to collide with uncharged particles under the drive of an electric field. Due to the conservation of energy and charge, the neutral molecules after the collision have initial kinetic energy and charge, and also begin to move in a directional manner driven by the electric field force. Ion wind has the advantages of large airflow coverage area and wide wind force adjustment range, and can be applied to heat dissipation of microelectronic components and control of micromachines and microfluids.

[0016] The ion wind technology generates a charge deposition effect on the insulating surface of the grounded electrode. Then, the electrostatic force is applied to the droplets by means of the deposited charges on the droplets and the insulating surface. Driven by the electrostatic force, the droplets break the original balance and overcome the resistance to achieve sliding. Many experiments have proved that the application of electrostatic force can enhance condensation and greatly promote the speed and efficiency of water collection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the device provided by the present invention;

[0018] Figure 2 Schematic diagram of different small holes in Example 1 and Example 2 of the present invention;

[0019] Figure 3 It is a schematic diagram of the principle of the present invention;

[0020] In the figure, 1-thermoelectric cooling sheet, 2-ITO glass, 3-insulating film, 4-needle tip electrode, 5-high voltage power supply. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the embodiments of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0023] In the description of the present invention, unless otherwise specified, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] Embodiment 1:

[0025] like Figure 2 As shown, a device for regulating the behavior and movement of condensed droplets by surface charge patterns, the main structure includes, a thermoelectric cooling sheet 1, an ITO glass 2, an insulating film 3, a needle tip electrode 4 and a high voltage power supply 5. Among them, in this embodiment, the insulating film adopts a smooth PET film (blue film), and the contact angle of the droplet surface is 100°, which is easy to slide off. The cut PET film is centered on the ITO glass; the needle tip electrode is connected to the positive pole of the high voltage power supply, and the conductive wire on the conductive side of the ITO glass is connected to the ground wire of the high voltage power supply; the needle tip electrode is vertically pointed to the ITO glass attached with the PET film.

[0026] The working process is as follows:

[0027] Prepare the PET (blue film) required for the experiment. Cut the PET film into a rectangle with a side length of 40*40mm, and ensure that the edges do not warp during the cutting process to prevent the droplets from sliding off in subsequent experiments.

[0028] The cut PET film is attached to the center of the 50×50mm ITO glass, and a laser engraving machine is used to make a cross array of small holes on the surface of the film, where the small holes are circular holes with a radius of 2mm. The experimental platform is adjusted and fixed vertically on the thermoelectric cooling chip (pay attention to controlling the current size and heat dissipation).

[0029] Connect the experimental circuit. Fix the needle tip connected to the positive electrode of the high-voltage power supply at a distance of 25 mm from the ITO glass, ensuring that it can always remain perpendicular to the ITO glass during the platform tilting process. Then use double conductive copper foil tape to connect the conductive side of the ITO glass to the ground wire of the high-voltage power supply. Start the high-voltage DC power supply 5 and adjust the voltage to 11KV.

[0030] Turn on the thermoelectric cooling sheet to start cooling, and you can quickly see small water mist beginning to appear on the surface of the blue film. When the water mist covers the entire surface of the blue film, turn on the high voltage power supply.

[0031] In the above embodiment, the needle tip corona discharge generates a large number of positive ions. Under the action of the ion wind, the positive ions will be deposited on the surface of the blue film (PET). The grounded ITO glass is exposed at the position after the cut hole. The electrical properties of the droplets near the small hole change and oscillate. Through the tip discharge, the ion wind will blow the water vapor in the air to the condensation surface, and the surface of the insulating film will produce a charge deposition effect. Small water droplets will gradually form on the surface. Due to the electrostatic force around the hole, the electrical properties of the charge carried by the small water droplets will change. By strengthening the condensation, the droplets reach the critical value of shedding. Compared with the experimental data of the intact PET film without needle tip discharge, the condensation efficiency is enhanced by about 2.5 times, so as to better realize the operations such as water mist condensation, shedding and collection.

[0032] Example 2

[0033] Unlike Example 1, the small hole in Example 2 is a hole formed by a combination of a circle with a radius of 2 mm and an ellipse with a major axis and a minor axis in a relationship of twice. As the positive pressure increases, it is found that the water mist condenses rapidly, and droplets oscillate or bounce around the small hole. As the degree of oscillation increases, small water droplets gather into large droplets. When the droplets reach a size that is detached from the surface, they overcome the friction and electrostatic forces and slide down. From the perspective of improving the condensation heat exchange efficiency, Example 2 has a better mist treatment effect, which is about 16% higher than that of Example 1. The elliptical arc structure makes it easier for droplets to fall off.

[0034] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A device for regulating the behavior and movement of condensed droplets by surface charge patterns, characterized in that: The invention comprises an ion wind generating device, ITO glass and an insulating film, wherein the insulating film is attached to the conductive side of the ITO glass, the ion wind generating device is vertically placed in front of the ITO glass, and the insulating film is provided with small holes arranged crosswise in an array; the outer dimensions of the small holes are larger than the outer dimensions of the droplets condensed on the insulating film, and the small holes are elliptical holes arranged crosswise in an array, wherein the length ratio of the major axis to the minor axis of the elliptical holes is 2:

1.

2. The device for regulating the behavior and movement of condensed droplets by surface charge patterns according to claim 1, characterized in that: The ITO glass has one conductive surface and one insulating surface.

3. The device for regulating the behavior and movement of condensed droplets by surface charge patterns according to claim 2, characterized in that: The device for generating ion wind comprises a high voltage power supply and a needle tip electrode, wherein the positive electrode of the high voltage power supply is connected to the needle tip electrode, and the ground wire of the high voltage power supply is connected to the conductive side of the ITO glass.

4. The device for regulating the behavior and movement of condensed droplets by surface charge patterns according to claim 1, characterized in that: A thermoelectric cooling sheet is arranged on the back of the ITO glass.

5. The device for regulating the behavior and movement of condensed droplets by surface charge patterns according to claim 1, characterized in that: The contact angle of the insulating film is 90-100°.

6. The device for regulating the behavior and movement of condensed droplets by surface charge patterns according to claim 3, characterized in that: The distance between the needle tip electrode and the ITO glass is 20 mm to 40 mm.

7. The device for regulating the behavior and movement of condensed droplets by surface charge patterns according to claim 3, characterized in that: The voltage adjustment range of the high voltage power supply is 0-20KV.

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