Condensation heat transfer enhancement structure for spacecraft humidity control system water collection inlet and preparation method thereof

Abstract

The application discloses a condensation heat exchange reinforcing structure for a spacecraft humidity control system water collecting inlet and a preparation method thereof. The condensation heat exchange reinforcing structure comprises a metal sheet base and a metal wire mesh. A single needle fin array is formed on the surface of the metal sheet base. The single needle fin has a circular arc top. The metal wire mesh is formed by interweaving warp and weft threads and is fixed at multiple points on the outside of the single needle fin array. The metal wire mesh is in contact with the top and side wall of each single needle fin. The condensation heat exchange reinforcing structure is fixed at the end of an air side channel and the water collecting inlet area. A water collecting cavity with a suction hole is arranged below the water collecting inlet area. The single needle fin array-wire mesh structure promotes the nucleation and coalescence of liquid droplets and directs them to the suction hole and the water collecting cavity. Meanwhile, the single needle fin array increases the effective heat exchange area, strengthens the turbulence and improves the condensation heat exchange performance.

Description

Technical Field

[0001] This invention relates to the field of humidity control technology for spacecraft environmental control and life support systems, specifically to a condensation heat transfer enhancement structure for the water collection inlet of a spacecraft humidity control system and its preparation method. Background Technology

[0002] In the humidity control loop of a spacecraft's environmental control and life support system, a condensing heat exchanger cools the humid air inside the cabin to below the dew point, causing water vapor to condense on the heat exchange surface. The resulting condensate needs to be collected promptly and introduced into the subsequent gas-liquid separation loop to meet the water management requirements of the sealed cabin and maintain stable temperature and humidity. Under microgravity conditions, the lack of gravity-driven drainage and phase stratification makes it easy for condensate to remain on the air-side surface, forming a liquid film. This can lead to reduced heat and mass transfer capacity, partial blockage of airflow channels, and may even entrain droplets into the gas path, affecting system stability. Existing technologies generally enhance drainage and separation by incorporating capillary suction components, surface wettability treatments, and combining suction and heating. However, under different heat fluxes, wind velocities, and contamination aging conditions, condensation often occurs in a dispersed nucleation manner, with insufficient droplet merging and directional transport, easily leading to unstable drainage paths, local flooding, and performance degradation. Summary of the Invention

[0003] Purpose of the invention: The first purpose of this invention is to address the problems of unstable drainage, local flooding, and performance degradation that easily occur in existing microgravity condensation dehumidification and drainage schemes under fluctuating operating conditions and pollution aging. This invention provides a condensation heat transfer enhancement structure for the water collection inlet of a spacecraft humidity control system that can promote condensate coalescence and stably guide the water collection port. The second purpose of this invention is to provide a method for preparing this condensation heat transfer enhancement structure.

[0004] Technical Solution: The present invention provides a condensation heat exchange enhancement structure for a water collection inlet of a spacecraft humidity control system, comprising a metal sheet substrate and a metal mesh. The surface of the metal sheet substrate is formed with a single needle fin array, each needle fin having a rounded top. The metal mesh is formed by interlacing warp and weft threads and is fixed at multiple points on the outside of the single needle fin array, with the metal mesh in contact with the top and sidewalls of each single needle fin. The condensation heat exchange enhancement structure is fixed at the water collection inlet area at the end of the air-side channel, and a water collection cavity with suction holes is provided below the water collection inlet area.

[0005] Furthermore, the wire diameter and aperture of the metal mesh are determined according to the resistance and fluid conduction requirements.

[0006] Furthermore, the shape of the metal sheet substrate is adapted to its mounting surface, which includes both planar and curved surfaces.

[0007] Furthermore, the metal sheet substrate is welded and fixed to the mounting surface of the air-side channel.

[0008] The method for preparing the condensation heat transfer enhancement structure of the present invention includes:

[0009] S1: Pretreatment of metal sheet substrate;

[0010] S2: A uniformly spaced single-needle fin array blank is rough-machined on the surface of a thin metal sheet substrate using micro-milling.

[0011] S3: Perform top finishing on the single needle wing array blank to change the top of the single needle wing from a square top shape to a rounded shape;

[0012] S4: Deburring and surface consistency treatment are performed on the finished single needle fin array to obtain a smooth and uniform surface;

[0013] S5: Cover the outside of the single needle-fin array with a metal wire mesh and fix it at multiple points to obtain the condensation heat transfer enhancement structure.

[0014] Further, in step S1, the metal sheet substrate pretreatment includes: degreasing cleaning, ultrasonic cleaning and drying of the metal sheet substrate.

[0015] Furthermore, in step S2, a single needle wing array blank is obtained by a cross-directional processing method.

[0016] Furthermore, in step S4, the deburring and surface consistency treatment includes: placing the finished single needle fin array in an organic solvent for ultrasonic cleaning for a period of time, followed by electrochemical polishing for a set time.

[0017] Furthermore, in step S5, the metal wire mesh is first covered over the single needle fin array area and pre-pressed and positioned so that the wire mesh is attached to the top and side wall of the single needle fin to form a continuous capillary liquid guiding interface; then, a combination of spot welding and brazing is used for multi-point fixation.

[0018] Furthermore, when fixing at multiple points, the welding points are first positioned along the edge of the wire mesh, and then reinforced inside the wire mesh.

[0019] Technical principle of the invention:

[0020] The core of the directional fluid guiding technology lies in the deep synergy between the single-needle array and the wire mesh structure. This coupling mechanism effectively solves the limitations of a single structure in a microgravity environment: if only a single-needle array is used, the condensate is prone to stagnation in the gaps under microgravity, forming liquid bridges, leading to deteriorated heat transfer and blockage of the gas path; if only a wire mesh is laid, due to the lack of morphological induction force, the dispersed droplets are difficult to quickly coalesce, and local flooding and performance degradation are likely to occur when operating conditions fluctuate. The mechanism of this single-needle array and wire mesh synergistic structure can be summarized as the coupling of "structure-induced coalescence and spatial pressure difference guidance". First, the curvature pressure difference (Laplace pressure) provided by the single needle-fin dome, combined with the surface energy difference at the intersection of the wire mesh, forces the dispersed condensed droplets to spontaneously aggregate towards nodes such as the wire mesh interlacing points and the contact points between the wire mesh and the top of the needle fin. Subsequently, the continuous three-dimensional capillary channels formed by the wire mesh attached to the top and sidewalls of the needle fins provide a low-resistance path for the droplets to cross the array. Finally, combined with the local underpressure generated by the suction hole below the water collection area, a well-defined pressure gradient is constructed in the microgravity disordered force field, ensuring that the condensate overcomes retention resistance and achieves efficient, directional, and fixed-point discharge.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0022] (1) The single needle-fin array-wire mesh structure can promote droplet nucleation, aggregation and directional guidance of the suction hole into the water collection cavity under microgravity conditions, reduce the risk of liquid film retention, liquid bridge and entrainment, and make dehumidification condensation drainage more stable and performance degradation slower; on the other hand, the single needle-fin array increases the effective heat exchange area and strengthens the turbulence, thereby improving the condensation heat exchange performance.

[0023] (2) The single needle fin array-wire mesh structure is compact, small in size, light in weight, easy to integrate, and does not significantly increase resistance. It is suitable for water collection in spacecraft humidity control systems.

[0024] (3) The preparation method of single needle wing array-wire mesh structure is simple and easy to implement, and is convenient for mass production. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a condensation heat transfer enhancement structure for a water collection inlet of a spacecraft humidity control system, provided by an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the structure of the metal wire mesh in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the condensation heat exchange enhancement structure applied to the water inlet area at the end of the air-side channel of the condensing heat exchanger in this embodiment of the invention. Detailed Implementation

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] Appendix Figures 1 to 3 The accompanying figure labels are as follows:

[0030] 1. Enhanced condensation heat exchange structure; 101. Single needle fin array; 102. Metal wire mesh; 2. Air-side channel; 3. Suction hole; 4. Water collection chamber.

[0031] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a condensation heat transfer enhancement structure for the water collection inlet of a spacecraft humidity control system. The condensation heat transfer enhancement structure 1 includes a metal sheet substrate and a metal mesh 102.

[0032] A single-needle fin array 101 is formed on the surface of a metal sheet substrate, with each fin having a rounded top. In this embodiment, the height of each fin is 0.4 mm, the spacing between fins is 0.9 mm, and the radius of the rounded top is approximately 0.15 mm, which helps to reduce liquid buildup at sharp corners and improve droplet coalescence efficiency. The shape of the metal sheet substrate is adapted to its mounting surface, which includes both flat and curved surfaces. The metal sheet substrate is welded and fixed to the mounting surface of the air-side channel 2. In this embodiment, the metal sheet substrate is made of materials such as copper, stainless steel, or copper-plated stainless steel, with a thickness of 0.5 mm to balance flexible adhesion to the mounting surface and structural strength.

[0033] The metal mesh 102 is formed by interlacing warp and weft threads. The wire diameter and aperture of the metal mesh 102 are determined according to resistance and liquid conduction requirements to improve drainage reliability. In this embodiment, the wire diameter of the metal mesh 102 is 80µm and the aperture is 0.2mm. The metal mesh 102 covers the outside of the single needle fin array 101, and the metal mesh 102 is attached to the top and sidewall of each single needle fin. It is fixed to the single needle fin array 101 at multiple points by a combination of spot welding and brazing. This allows the metal mesh 102 to form a continuous capillary interface with the single needle fin array 101 while ensuring the permeability of the pores, promoting the coalescence and directional flow of condensate. Multi-point fixing also improves the connection reliability of the metal mesh 102 under airflow scouring and thermal cycling conditions.

[0034] This invention also provides a method for preparing the condensation heat transfer enhancement structure described in this invention, comprising the following steps:

[0035] S1: Pretreatment of metal sheet substrate;

[0036] The metal sheet substrate was sequentially cleaned with acetone, rinsed with deionized water, ultrasonically cleaned for 15-20 minutes, and then vacuum dried.

[0037] S2: A uniformly spaced single-needle fin array blank is rough-machined on the surface of a thin metal sheet substrate using micro-milling.

[0038] The pre-treated metal sheet substrate is clamped in a precision micro-milling system, and roughing is performed by a ball end mill with cross-cutting two-way feed to obtain a regular array of blanks. The ball end mill has a tip diameter of 300µm, a spindle speed of 60000r / min and a feed rate of 150mm / min, and a single-insert depth of cut of 40µm.

[0039] With a preset single needle wing spacing of 0.9mm, the striped grooves are first milled at equal intervals along the first direction and then cut layer by layer to the target depth. The workpiece is then rotated 90° to switch to a vertical toolpath and the same equal-interval layered cutting is repeated along the second direction, thereby forming a regular and uniformly spaced single needle wing array blank on the surface of the thin sheet.

[0040] S3: Perform top finishing on the single needle wing array blank to change the top of the single needle wing from a square top shape to a rounded shape;

[0041] The single needle fin array blank is further clamped in the micro-milling system. First, a 0.3mm flat-bottom end mill is used to pre-shape the top of the single needle fin. The process is carried out with a small depth of cut and multiple passes to gradually cut the square top corners and form a transition contour that is close to a rounded arc.

[0042] Then, a small ball end mill with a diameter of 0.2mm was used to perform surface fitting and finishing on the top of the single needle wing, so that the top formed a continuous arc shape. The spindle speed was 60000r / min, the feed rate was 140mm / min, and a contour finishing toolpath was used to perform multi-layer micro-cutting, so that the top of the single needle wing transitioned from a square top shape to a round top shape.

[0043] S4: Deburring and surface consistency treatment are performed on the finished single needle fin array to obtain a smooth and uniform surface;

[0044] The processed dome-shaped single-needle fin array was sequentially subjected to ultrasonic cleaning in acetone and anhydrous ethanol for 5–20 minutes, followed by thorough rinsing with deionized water and drying under a nitrogen flow. Then, the array surface underwent a slight electrochemical polishing treatment using an electrolyte system adapted to the substrate metal, at 10... The sample was treated at a current density for 120 seconds. After treatment, it was rinsed with deionized water and cleaned with ethanol, and then dried in a clean airflow to obtain a single needle-wing array structure with a smooth surface, uniform morphology and no obvious burrs.

[0045] S5: A condensation heat transfer enhancement structure is obtained by covering and fixing a metal wire mesh 102 at multiple points on the outside of a single needle-fin array.

[0046] The metal wire mesh 102 is cut and pre-shaped according to the outer dimensions of the single needle fin array 101. Then, the metal wire mesh 102 is covered on the area of ​​the single needle fin array 101 and pre-pressed and positioned so that the metal wire mesh 102 is attached to the top and side wall of the single needle fin to form a continuous capillary liquid guiding interface. Subsequently, a combination of spot welding and brazing is used for multi-point fixation. The welding points are first positioned along the edge of the metal wire mesh 102 and then reinforced inside the metal wire mesh 102 to ensure that the metal wire mesh 102 does not warp or fall off under airflow scouring and thermal cycling, and to avoid large-area welding causing pore blockage.

[0047] Figure 3 An example of a condensation heat transfer enhancement structure applied to the air-side passage of a condensation heat exchanger is shown.

[0048] The air-side channel 2 is formed by corrugated thin fins with a thickness of 0.15 mm, a height of 1.2 mm, and a pitch of 1.6 mm. The effective heat exchange length on the air side is 120 mm, and the effective channel width is 60 mm. A water collection inlet area is provided at the end of the air-side channel 2, with a length of 12 mm along the airflow direction. Below it, a water collection cavity 4 is formed, which communicates with an external gas-liquid separator. The depth of the water collection cavity 4 is 3 mm. Several suction holes 3 are formed on the heat exchange wall above the water collection cavity 4 and are connected to the hole-suction gas-liquid separation circuit. In this embodiment, the diameter of the suction holes 3 is 1.2 mm, and the center distance between the holes is 4 mm. The suction holes 3 are used to draw condensate into the water collection cavity 4 under under-voltage conditions and guide it into the external gas-liquid separator, realizing the liquid-water discharge and recovery and gas recirculation of the gas-liquid separation circuit.

[0049] In microgravity environments, condensate tends to linger on the air-side surface, forming liquid films or bridges, leading to decreased heat and mass transfer capacity and increased channel pressure drop. To enhance the nucleation, aggregation, and liquid guiding processes in the terminal water collection inlet region, the condensation heat transfer enhancement structure described in this embodiment is welded and fixed onto the fins corresponding to the terminal water collection inlet region of the air-side channel 2. This guides the condensate to steadily collect towards the suction hole 3, improving the stability of water collection through the hole under microgravity conditions and ensuring the reliable operation of the humidity control loop.

[0050] When fixing the condensation heat exchange enhancement structure, first cut and pre-form the condensation heat exchange enhancement structure according to the outer dimensions of the water inlet area so that it matches the length of the water inlet area, and then position and fix it at the end of the air-side channel 2 water inlet area.

[0051] In actual operation, after the humid air flows through the condensation heat exchange area, the condensate first nucleates and forms microdroplets at the wire mesh and junction nodes. As the condensation process proceeds, the microdroplets rapidly coalesce at the wire mesh junctions and at the top and sidewalls of the single needle fins to form larger droplets. Under the combined action of capillary force, surface energy difference, and curvature pressure difference, the condensate migrates directionally from the dispersion area to the coalescence node area and converges along the continuous capillary channel formed by the single needle fin array and wire mesh to the water collection inlet area and is discharged through the suction hole. This achieves fixed-point collection and continuous drainage under microgravity conditions, thereby significantly reducing the probability of liquid film, liquid bridge, and droplet entrainment in the end water collection area, suppressing local flooding and pressure drop rise, and improving drainage smoothness and dehumidification stability under wet load fluctuations and droplet enrichment conditions.

[0052] The enhanced condensation heat exchange structure provided by this invention is applicable not only to the condensation heat exchanger of the example, but also to the condensation dehumidifier and condensate recovery component of the spacecraft humidity control system, for efficient collection of condensate, orifice suction drainage and stable operation of gas-liquid separation under microgravity environment.

Claims

1. A condensation heat transfer enhancement structure for the water collection inlet of a spacecraft humidity control system, characterized in that, It includes a metal sheet substrate and a metal wire mesh (102). The surface of the metal sheet substrate is formed with a single needle wing array (101), and the single needle wing has a rounded top. The metal wire mesh (102) is formed by interlacing warp and weft threads and is fixed at multiple points on the outside of the single needle wing array (101). The metal wire mesh (102) is attached to and in contact with the top and sidewall of each single needle wing. The condensation heat exchange enhancement structure is fixed at the water inlet area at the end of the air side channel (2). The water inlet area has a water collection cavity (4) with a suction hole (3) below it.

2. The condensation heat transfer enhancement structure according to claim 1, characterized in that, The wire diameter and aperture of the metal wire mesh (102) are determined according to the resistance and liquid conduction requirements.

3. The condensation heat transfer enhancement structure according to claim 1, characterized in that, The shape of the metal sheet substrate is adapted to its mounting surface, which includes both planar and curved surfaces.

4. The condensation heat transfer enhancement structure according to claim 3, characterized in that, The metal sheet substrate is welded and fixed to the mounting surface of the air-side channel (2).

5. A method for preparing a condensation heat transfer enhancement structure according to any one of claims 1 to 4, characterized in that, include: S1: Pretreatment of metal sheet substrate; S2: A uniformly spaced single-needle fin array blank is rough-machined on the surface of a thin metal sheet substrate using micro-milling. S3: Perform top finishing on the single needle wing array blank to change the top of the single needle wing from a square top shape to a rounded shape; S4: Deburring and surface consistency treatment are performed on the finished single needle fin array to obtain a smooth and uniform surface; S5: Cover the outside of the single needle fin array with a metal wire mesh (102) and fix it at multiple points to obtain the condensation heat exchange enhancement structure.

6. The method for preparing the condensation heat transfer enhancement structure according to claim 5, characterized in that, In step S1, the metal sheet substrate pretreatment includes: degreasing, ultrasonic cleaning and drying of the metal sheet substrate.

7. The method for preparing the condensation heat transfer enhancement structure according to claim 5, characterized in that, In step S2, a single needle wing array blank is obtained by a cross-two-way processing method.

8. The method for preparing the condensation heat transfer enhancement structure according to claim 5, characterized in that, In step S4, the deburring and surface consistency treatment includes: placing the finished single needle fin array in an organic solvent for ultrasonic cleaning for a period of time, followed by electrochemical polishing for a set time.

9. The method for preparing the condensation heat transfer enhancement structure according to claim 5, characterized in that, In step S5, the metal wire mesh (102) is first covered on the area of ​​the single needle wing array (101) and pre-pressed and positioned so that the wire mesh is attached to the top and side wall of the single needle wing to form a continuous capillary liquid guiding interface; then, a combination of spot welding and brazing is used for multi-point fixation.

10. The method for preparing the condensation heat transfer enhancement structure according to claim 9, characterized in that, When fixing at multiple points, the welding points are first positioned along the edge of the wire mesh (102), and then reinforced inside the wire mesh (102).

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