Spatial liquid and gas drainage structure and method based on local temperature gradient and geometric configuration

Abstract

The present invention discloses a spatial liquid drainage and exhaust structure and method based on local temperature gradient and geometric configuration in the field of droplet separation technology under a microgravity environment, wherein the contact surface between the cover plate and the mother liquid is arranged as a conical surface, and an outlet for discharging bubbles and / or droplets outward is arranged at the top of the conical surface, and the geometric curvature gradient formed by the conical surface is used to guide the moving direction of the bubbles and / or droplets; a heating plate is arranged on the outer side of the cover plate at the side of the outlet, and the heating plate is used to heat the cover plate to form a temperature gradient from the outlet to the edge of the cover plate; the mother liquid will generate thermal capillary force under the temperature gradient to drive the bubbles and / or droplets in the mother liquid to move along the conical surface toward the outlet.

Description

Technical Field

[0001] The present invention relates to the technical field of droplet separation in a microgravity environment, and in particular to a space liquid and gas discharge structure and method based on local temperature gradient and geometric configuration. Background Art

[0002] The space drainage and exhaust structure is required to be able to smoothly discharge bubbles or droplets suspended in the mother liquid in a microgravity environment.

[0003] In the space environment (space station environment), the effect of gravity basically disappears, and the surface tension, which manifests as a secondary force due to the existence of gravity on the ground, plays a major role, resulting in obvious differences in fluid behavior in the space environment and on the ground.

[0004] On the ground, due to the effect of buoyancy, bubbles will continue to float up until they escape from the mother liquid, and droplets with a smaller density than the mother liquid will also continue to float up until they are spread flat on the top of the mother liquid.

[0005] In a space environment, bubbles and droplets will be randomly suspended in the mother liquor, and a large amount of mother liquor will be lost in the process of discharging droplets and bubbles. Moreover, due to the random suspension characteristics of bubbles and droplets, it is difficult to ensure that droplets and bubbles can be discharged from the mother liquor, and it is difficult to ensure the purity of the mother liquor.

[0006] The patent of the present invention discharges bubbles and droplets in the mother liquid in a microgravity environment by constructing the thermal capillary force generated by the local temperature gradient and the capillary driving force generated by the special geometric configuration, thereby ensuring the purity of the mother liquid. Summary of the invention

[0007] The purpose of the present invention is to provide a spatial drainage and exhaust structure and method based on local temperature gradient and geometric configuration to solve the technical problems in the prior art that a large amount of mother liquid will be lost when bubbles and droplets are discharged from the mother liquid in a space environment, and the purity of the mother liquid is difficult to ensure.

[0008] In order to solve the above technical problems, the present invention specifically provides a spatial liquid drainage and exhaust structure based on local temperature gradient and geometric configuration;

[0009] The cover plate includes a contact surface between the cover plate and the mother liquid, which is a conical surface with different curvatures at different places, and an outlet for discharging bubbles and / or droplets is provided at the top of the conical surface, and the geometric curvature gradient of the conical surface itself forms a capillary driving force for driving bubbles and / or droplets to migrate toward the outlet;

[0010] A heating plate for heating the cover plate is arranged on the outer side of the cover plate at the side of the outlet to form a temperature gradient on the conical surface, and the temperature gradient can induce a thermocapillary force for driving bubbles and / or droplets to migrate toward the outlet;

[0011] The thermocapillary force and the capillary driving force jointly drive the bubbles and / or droplets in the mother liquid to move along the cone surface toward the outlet.

[0012] As a preferred solution of the present invention, the heating plate is evenly adhered to the outer side of the outlet in a ring shape.

[0013] As a preferred solution of the present invention, the distribution state of the temperature gradient on the conical surface is:

[0014] The temperature of the portion where the heating plate is provided decreases gradually from the direction close to the outlet to the direction away from the outlet;

[0015] In the portion where the heating plate is not provided, the temperature drops sharply from the direction close to the outlet to the direction far away from the outlet.

[0016] As a preferred solution of the present invention, thermistors are attached to the center and edge of the cover plate to monitor whether the temperature gradient of the cover plate is uniform.

[0017] In order to solve the above technical problems, the present invention further provides a spatial liquid and gas drainage method based on local temperature gradient and geometric configuration.

[0018] Using the above-mentioned space drainage and exhaust structure includes the following steps:

[0019] Install the cover plate on the mother liquid tank;

[0020] Turn on the heating plate to heat the cover plate so that a temperature gradient gradually decreases from the center to the edge of the conical surface at the bottom of the cover plate;

[0021] After the temperature gradient is formed, the combined force of the thermal capillary force caused by the temperature gradient and the capillary driving force caused by the cone surface drives the bubbles and / or droplets in the mother liquid to move along the cone surface toward the outlet;

[0022] The mother liquid is pushed into the pool from the liquid inlet of the mother liquid pool to raise the liquid level of the mother liquid in the mother liquid pool, so that the droplets and / or bubbles that migrate to the outlet can be discharged smoothly.

[0023] As a preferred solution of the present invention, the temperature gradient formed on the cover plate is monitored by a thermistor;

[0024] When the temperature on the cover is uniform, turn off the heating plate to cool the cover plate, and then turn on the heating plate again.

[0025] As a preferred solution of the present invention, the magnitude of the capillary driving force is adjusted by controlling the curvature of the tapered surface, thereby adjusting the discharge speed of the bubbles and / or droplets;

[0026] The greater the curvature, the greater the capillary driving force.

[0027] As a preferred solution of the present invention, the discharge speed of bubbles and / or droplets is adjusted by controlling the magnitude of the capillary driving force.

[0028] As a preferred embodiment of the present invention, the expression of the capillary driving force is:

[0029] ;

[0030] In the formula, s Represents the position on the coordinate axis pointing to the vertex of the cone along the direction of the half cone surface;

[0031] The free energy equation of a droplet on a solid surface is expressed as:

[0032] ;

[0033] In the formula, σ represents the surface tension, θ represents the liquid contact angle, A LV and A LS represent the gas-liquid contact surface area and the solid-liquid contact surface area respectively;

[0034] For the half cone angle α The droplet on the cone surface, relative to the dimensionless radius of curvature , the dimensionless free energy expression is:

[0035] ;

[0036] In the formula, A s is the gas-liquid contact area of ​​spherical droplets of equal volume, and its expression is:

[0037] ;

[0038] Represents the wall curvature at the solid-liquid contact surface, and the expression is:

[0039] ;

[0040] In the formula, R Represents the radius of the cone at the solid-liquid interface.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The contact surface of the cover plate with the mother liquid is set as a cone surface to form a geometric curvature gradient, thereby generating a capillary driving force to drive bubbles and / or droplets to migrate toward the outlet; by setting a heating plate, a temperature gradient is formed from the outlet to the edge of the cover plate, and the temperature gradient generates a thermal capillary force in the mother liquid, driving the droplets and / or bubbles to move along the cone surface toward the outlet. The capillary driving force combined with the thermal capillary force can expel the droplets and / or bubbles in the mother liquid in a spatial environment without losing the mother liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0044] Figure 1 This is a schematic diagram of the structure of the cover plate in an embodiment of the present invention;

[0045] Figure 2 for Figure 1 A cross-sectional schematic diagram of

[0046] Figure 3 Schematic diagram of temperature gradient and driving mechanism in an embodiment of the present invention;

[0047] Figure 4 Schematic diagram of the movement of droplets during the space station experiment.

[0048] The numbers in the figure represent the following:

[0049] 1-cover plate, 2-cone surface, 3-outlet, 4-heating plate, 5-droplet. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] The present invention specifically provides a spatial liquid drainage and exhaust structure based on local temperature gradient and geometric configuration;

[0052] The cover plate 1 includes a contact surface between the cover plate 1 and the mother liquid, which is a conical surface 2 with different curvatures at different places. The top of the conical surface 2 is provided with an outlet 3 for discharging bubbles and / or droplets 5 outwardly. The geometric curvature gradient of the conical surface 2 itself forms a capillary driving force for driving the bubbles and / or droplets 5 to migrate toward the outlet 3.

[0053] A heating plate 4 for heating the cover plate 1 is arranged on the outer side of the cover plate 1 at the side of the outlet 3, so as to form a temperature gradient with a gradually decreasing temperature from the outlet 3 to the edge of the cover plate 1 on the conical surface, and the temperature gradient can induce a thermocapillary force for driving the bubbles and / or droplets 5 to migrate toward the outlet 3;

[0054] The thermocapillary force and the capillary driving force jointly drive the bubbles and / or droplets 5 in the mother liquid to move along the conical surface 2 toward the outlet 3 .

[0055] In terms of structural configuration, cone 2 is not a common choice. The reasons for choosing cone 2 are:

[0056] The contact surface configuration with the mother liquid requires that the curvature is not equal everywhere. Considering the requirements for temperature gradient, the thickness at the hottest point needs to be the smallest, so cone surface 2 is selected.

[0057] Taking the droplet 5 as an example, the driving mechanism used by the above-mentioned cover plate 1 is: the droplet 5 is immersed in the immiscible mother liquid, and the cover plate 1 is heated by the heating plate 4, so that a temperature gradient is generated in the mother liquid, causing uneven temperature on the interface of the droplet 5, and then uneven interfacial tension, thereby driving the liquid on both sides of the interface to flow, and the droplet 5 will move due to the reaction force of the shear stress of the mother liquid.

[0058] At the same time, the capillary driving force formed by the geometric curvature gradient of the conical surface 2 itself will also drive the bubbles and / or droplets 5 to migrate toward the outlet 3 .

[0059] That is, the thermocapillary force and the capillary driving force jointly drive the bubbles and / or droplets 5 in the mother liquid to move along the conical surface 2 toward the outlet 3 .

[0060] The movement mechanism of the bubbles is the same as that of the droplets 5.

[0061] In summary, the cover plate 1 sets the contact surface with the mother liquid as a conical surface 2 to form a geometric curvature gradient, thereby generating a capillary driving force to drive the bubbles and / or droplets 5 to migrate toward the outlet 3; by setting a heating plate 4, a temperature gradient is formed from the outlet 3 to the edge of the cover plate 1, and the temperature gradient generates a thermal capillary force in the mother liquid, driving the droplets 5 and / or bubbles to move along the conical surface 2 toward the outlet 3. The capillary driving force combined with the thermal capillary force can expel the droplets 5 and / or bubbles in the mother liquid in a spatial environment without losing the mother liquid.

[0062] Furthermore, the heating plate 4 is evenly adhered to the outer side of the outlet 3 in a ring shape, so that an annular temperature gradient surrounding the outlet 3 can be formed on the cover plate 1, covering a wider area, so that the mother liquid in contact with the conical surface generates thermal capillary force, thereby improving the efficiency of expelling droplets 5 and / or bubbles.

[0063] It should be noted that the above-mentioned annular uniform surface pasting is local, that is, the pasting radius is smaller than the radius of the cover plate 1, so that a temperature gradient can be formed.

[0064] Furthermore, the distribution state of the temperature gradient on the conical surface 2 is:

[0065] In the portion where the heating plate 4 is provided, since the straight-line distances between each point on the conical surface 2 and the heating plate 4 are different, the temperature decreases gradually from the direction close to the outlet 3 to the direction far away from the outlet 3, that is, the attenuation is relatively uniform.

[0066] In the portion where the heating plate 4 is not provided, the temperature drops sharply from the direction close to the outlet 3 to the direction far away from the outlet 3 .

[0067] Furthermore, thermistors are attached to the center and edge of the cover plate 1 to monitor the temperature gradient of the cover plate 1 .

[0068] The thermistor is installed in a mounting groove arranged on the circumference of the cover plate 1 .

[0069] In order to solve the above technical problems, the present invention further provides a spatial liquid and gas drainage method based on local temperature gradient and geometric configuration.

[0070] Using the above-mentioned space drainage and exhaust structure includes the following steps:

[0071] Install the cover plate 1 on the mother liquid tank;

[0072] Turn on the heating plate 4 to heat the cover plate 1, so that the conical surface 2 at the bottom of the cover plate 1 forms a temperature gradient with a gradually decreasing temperature from the center to the edge;

[0073] After the temperature gradient is formed, the combined force of the thermal capillary force caused by the temperature gradient and the capillary driving force caused by the cone surface drives the bubbles and / or droplets 5 in the mother liquid to move along the cone surface 2 toward the outlet 3;

[0074] The mother liquid is pushed into the mother liquid pool from the liquid inlet, so that the mother liquid level in the mother liquid pool rises, and the droplets 5 and / or bubbles that migrate to the outlet 3 are discharged smoothly.

[0075] Further, the temperature gradient formed on the cover plate is monitored by a thermistor;

[0076] When the temperature on the cover plate 1 is uniform, the heating plate 4 is turned off to cool the cover plate 1, and then the heating plate 4 is turned on again to re-form the temperature gradient.

[0077] Furthermore, the magnitude of the capillary driving force is adjusted by controlling the curvature of the conical surface 2 , thereby adjusting the discharge speed of the bubbles and / or droplets 5 .

[0078] The greater the curvature, the greater the capillary driving force.

[0079] The method for adjusting the curvature is: adjusting the taper of the conical surface 2.

[0080] Furthermore, the expression of capillary driving force is:

[0081] ;

[0082] In the formula, s Represents the position on the coordinate axis pointing to the vertex of the cone along the direction of half cone surface 2;

[0083] The free energy equation of droplet 5 on the solid surface is expressed as:

[0084] ;

[0085] In the formula, σ represents the surface tension, θ represents the liquid contact angle, A LV and A LS represent the gas-liquid contact surface area and the solid-liquid contact surface area respectively;

[0086] For the half cone angle α The conical surface of the droplet 5, relative to the dimensionless radius of curvature , the dimensionless free energy expression is:

[0087] ;

[0088] In the formula, A s is the gas-liquid contact area of ​​a spherical droplet 5 of the same volume, and its expression is:

[0089] ;

[0090] Represents the wall curvature at the solid-liquid contact surface, and the expression is:

[0091] ;

[0092] In the formula, R Represents the radius of the cone at the solid-liquid interface.

[0093] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A spatial drainage and exhaust structure based on local temperature gradient and geometric configuration, characterized in that: It comprises a cover plate, wherein the contact surface of the cover plate (1) with the mother liquid is arranged as a conical surface (2) with different curvatures at various places, an outlet (3) for discharging bubbles and / or liquid droplets (5) outward is arranged at the top of the conical surface (2), and the geometric curvature gradient of the conical surface (2) itself forms a capillary driving force for driving the bubbles and / or liquid droplets (5) to migrate toward the outlet (3); A heating plate (4) for heating the cover plate (1) is arranged on the outer side of the cover plate (1) at the side edge of the outlet (3), and the heating plate (4) is evenly adhered to a portion of the outer side of the outlet (3) in a ring shape to form a temperature gradient on the conical surface, and the temperature gradient can induce a thermal capillary force for driving bubbles and / or droplets (5) to migrate toward the outlet (3); The thermal capillary force and the capillary driving force jointly drive the bubbles and / or droplets (5) in the mother liquid to move along the conical surface (2) toward the outlet (3).

2. A spatial liquid drainage and exhaust structure based on local temperature gradient and geometric configuration according to claim 1, characterized in that: The distribution state of the temperature gradient on the conical surface (2) is: The temperature of the portion where the heating plate (4) is provided decreases as the distance from the outlet (3) increases; The temperature of the portion where the heating plate (4) is not provided decreases sharply as the distance from the outlet (3) increases.

3. A spatial liquid drainage and exhaust structure based on local temperature gradient and geometric configuration according to claim 2, characterized in that: Thermistors are attached to the center and edge of the cover plate (1) to monitor whether the temperature gradient of the cover plate (1) is uniform.

4. A method for draining liquid and exhausting air from a space based on local temperature gradient and geometric configuration, characterized in that: Using a spatial liquid drainage and exhaust structure based on local temperature gradient and geometric configuration as described in any one of claims 1 to 3 comprises the following steps: Installing the cover plate (1) on the mother liquid tank; Turning on the heating plate (4) to heat the cover plate (1) so that the conical surface (2) at the bottom of the cover plate (1) forms a temperature gradient with the temperature gradually decreasing from the center to the edge; After the temperature gradient is formed, the combined force of the thermal capillary force caused by the temperature gradient and the capillary driving force caused by the conical surface drives the bubbles and / or droplets (5) in the mother liquid to move along the conical surface (2) toward the outlet (3); The mother liquid is pushed into the mother liquid pool from the liquid inlet, so that the mother liquid level in the mother liquid pool rises, and the droplets (5) and / or bubbles that migrate to the outlet (3) are discharged smoothly.

5. A method for draining liquid and exhausting air from a space based on local temperature gradient and geometric configuration according to claim 4, characterized in that: The temperature gradient formed on the cover plate is monitored by a thermistor; When the temperature on the cover plate (1) is uniform, the heating plate (4) is turned off to cool the cover plate (1), and then the heating plate (4) is turned on again.

6. A method for draining liquid and exhausting air from a space based on local temperature gradient and geometric configuration according to claim 4, characterized in that: Controlling and adjusting the curvature of the conical surface (2) to adjust the magnitude of the capillary driving force, thereby adjusting the discharge speed of the bubbles and / or droplets (5); The greater the curvature, the greater the capillary driving force.

7. A method for draining liquid and exhausting air from a space based on local temperature gradient and geometric configuration according to claim 6, characterized in that: The expression of the capillary driving force is: ; In the formula, s Represents the position on the coordinate axis pointing to the vertex of the cone along the direction of the half cone surface; The free energy equation of a droplet on a solid surface is expressed as: ; In the formula, σ represents the surface tension, θ represents the liquid contact angle, A LV and A LS represent the gas-liquid contact surface area and the solid-liquid contact surface area respectively; For the half cone angle α The droplet on the cone surface, relative to the dimensionless radius of curvature , the dimensionless free energy expression is: ; In the formula, A s is the gas-liquid contact area of ​​a spherical droplet (5) of equal volume, Its expression is: ; Represents the wall curvature at the solid-liquid contact surface, and the expression is: ; In the formula, R Represents the radius of the cone at the solid-liquid interface.

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