Evenly-filled hollow fiber membrane evaporation radiator

Abstract

The invention discloses a uniformly-filled hollow fiber membrane evaporation radiator which is applied to efficient heat dissipation of extravehicular spacesuits. According to the invention, water is used as a circulating cooling working medium, and water vapor is driven to be evaporated from flowing water by using the pressure difference between the saturated vapor pressure of the water and a space zero-pressure or low-pressure environment and permeates out through micropores in the pipe wall of the hollow fiber membrane, so that heat of the water is quickly taken away in the form of latent heat of evaporation, and the cooling effect is achieved; and efficient heat dissipation is provided for an astronaut out-of-cabin task. According to the uniform filling structure provided by the invention, the hollow fiber membrane tubes can be uniformly arranged, a water vapor flowing dead zone is avoided, and the mass transfer area of each hollow fiber membrane tube can be effectively utilized, so that the uniform filling structure has efficient heat dissipation capability.

Description

Technical Field

[0001] The present invention relates to a hollow fiber membrane evaporation radiator with uniform filling. Background Art

[0002] During extravehicular activities in space, the metabolic intensity of the human body is significantly higher than the normal level, and the thermal control system of the extravehicular spacesuit needs to handle high heat flux loads. Since the Apollo moon landing, the sublimator based on the principle of ice sublimation absorbing heat has always been the standard heat dissipation device for extravehicular spacesuits in various countries. However, problems such as easy blockage and easy breakdown of the sublimator have not been effectively solved. More importantly, its working back pressure must not be higher than the triple point pressure of water (611 Pa), and this inherent defect determines that it cannot be applied to future manned Mars missions.

[0003] Similar to ice sublimation, water evaporation also has a huge latent heat absorption capacity. However, the latter is not limited by back pressure. No matter how high the back pressure is, as long as the saturated vapor pressure of water is higher than the back pressure, water evaporation can be driven to produce a cooling effect. Based on this basic principle, using a porous membrane material to separate water from the evaporated water vapor to form a flowing evaporation with a stable gas-liquid interface to provide stable and controllable heat dissipation, this technology has been relatively common.

[0004] CN202010498862.7 discloses a multi-layer composite nano-porous evaporator for heat dissipation of high-power electronic devices. The nano-porous membrane provides a vapor channel for the evaporation of the coolant, and at the same time separates the coolant from the vapor to achieve gas-liquid separation and avoid the formation of an unstable and high-resistance gas-liquid two-phase flow. CN202411572224.X discloses a passive membrane-type analytical cooling device for solar panels, which evaporates water in the solution by using a hydrophobic flat membrane to produce a cooling effect to dissipate heat from the solar panels. CN202280019026.3 discloses an air conditioner based on a membrane contactor, which separates water from ambient air by using a hydrophobic hollow fiber membrane and uses the difference between the saturated vapor pressure of water and the partial pressure of water vapor in the air to drive water evaporation to produce an endothermic effect to cool the air.

[0005] The membrane evaporation radiators disclosed in the above patent applications are all for conventional terrestrial application scenarios, while aerospace application scenarios are more complicated. The space environment pressure is very low or even 0. Compared with flat membranes, the hollow fiber membrane with a tubular structure has a higher pressure-bearing capacity and should be the first choice for aerospace applications. The membrane tube cannot be directly exposed in space. It needs to be protected by a strict shell and requires a high degree of compactness. Therefore, it is necessary to fill thousands or even tens of thousands of membrane tubes in the shell. The membrane tubes are easily connected to form a flow dead zone. It is difficult for water vapor to circulate in this area, resulting in the mass transfer area of this part of the membrane tube cannot be effectively utilized. CN202310963375.7 discloses a fiber membrane heat exchanger for a vacuum environment, which fills a hollow fiber membrane with a diameter of 325μm in a rectangular shell and uses the membrane evaporation effect to dissipate heat to the space suit outside the cabin, but the document does not involve the filling method and arrangement of the hollow fiber membrane. Summary of the Invention

[0006] In response to the demand for efficient and compact heat dissipation technology for extravehicular space suits, the present invention provides a uniformly filled hollow fiber membrane evaporative radiator, which uses water as a circulating cooling medium and utilizes the pressure difference between the saturated vapor pressure of the cooling water and the zero pressure or low pressure environment in space to drive water vapor to evaporate from the flowing cooling water, and then penetrate out through the micropores in the wall of the hollow fiber membrane tube, quickly taking away the heat of the cooling water in the form of latent heat of evaporation, achieving a cooling effect, thereby dissipating heat from the human body; in the hollow fiber membrane evaporative radiator according to the present invention, the hollow fiber membrane tubes are uniformly filled in the shell to avoid the formation of dead zones for water vapor flow, ensuring that the mass transfer area of each hollow fiber membrane tube can be effectively utilized.

[0007] According to one embodiment of the present invention, a uniformly filled hollow fiber membrane evaporative radiator includes: a hollow fiber membrane tube, a membrane tube bracket, a shell, a cooling water inlet head, a cooling water outlet head, a cooling water inlet end head, a cooling water outlet end head, a cooling water inlet joint, a cooling water outlet joint, a water vapor exhaust port, and a back pressure valve.

[0008] In one embodiment according to the present invention, a hollow fiber membrane tube is arranged on a membrane tube support, and the membrane tube support is arranged inside a shell; the hollow fiber membrane tube divides the space inside the shell into a shell side space and a tube side space, the shell side space is filled with water vapor, and the tube side space is filled with cooling water; a cooling water inlet head and a cooling water outlet head separate the water vapor in the shell side space from the cooling water in the cooling water inlet end and the cooling water outlet end; the membrane tube support includes a first support ring, a second support ring and support beams, both ends of the support beams are respectively connected to the first support ring and the second support ring, the first support ring and the second support ring are multi-layer annular structures, and are concentrically arranged between each layer, and each layer is evenly provided with membrane tube grooves, the size of the membrane tube grooves is slightly larger than the diameter of the hollow fiber membrane tube, and the membrane tube grooves are used to place the hollow fiber membrane tubes. The hollow fiber membrane tubes are evenly arranged both axially and radially in the shell to avoid flow dead zones in the shell side space and ensure that the mass transfer area of each hollow fiber membrane tube can be effectively utilized.

[0009] In one embodiment according to the present invention, cooling water flows into the hollow fiber membrane evaporative radiator from a cooling water inlet joint, is distributed to each hollow fiber membrane tube in the cooling water inlet end, flows inside the hollow fiber membrane tube, water vapor evaporates from the cooling water, and penetrates into the shell side space through the micropores in the wall of the hollow fiber membrane tube, flows in the shell side space, and finally discharges from a water vapor exhaust port. The process of water vapor evaporating from the cooling water absorbs the heat in the cooling water, thereby cooling the cooling water in the form of latent heat. The cooled cooling water flows out of each hollow fiber membrane tube and converges in the cooling water outlet end, and then flows out from the cooling water outlet joint and is sent to the liquid cooling channel of the extravehicular spacesuit to dissipate heat for the object. The heated cooling water returns to the cooling water inlet joint to complete a heat dissipation cycle.

[0010] In one embodiment according to the present invention, the hollow fiber membrane tube is a hydrophobic porous material, which separates the cooling water from the evaporated water vapor, provides a stable gas-liquid interface for the evaporation process, the cooling water is blocked by the surface tension of the membrane pore wall and will not enter the membrane pores, while the water vapor can enter. The water vapor penetrates in the membrane pores in the form of Knudsen diffusion, and its mass transfer driving force is the difference between the saturated vapor pressure of the cooling water in the tube side space and the vapor pressure in the shell side space.

[0011] In one embodiment according to the present invention, the saturated vapor pressure of the cooling water in the tube side space is determined by the temperature of the cooling water itself. The higher the temperature, the higher the saturated vapor pressure. Only when the saturated vapor pressure of the cooling water in the tube side space is higher than the vapor pressure in the shell side space, the hollow fiber membrane evaporative radiator has the ability of evaporative heat dissipation.

[0012] In one embodiment according to the present invention, the heat dissipation capacity of the hollow fiber membrane evaporation radiator is adjusted by a back pressure valve, where: when the opening of the back pressure valve increases, the vapor pressure in the shell side space decreases, the mass transfer driving force increases, the evaporation rate increases, and the heat dissipation capacity is enhanced; when the opening of the back pressure valve decreases, the vapor pressure in the shell side space rises, the mass transfer driving force decreases, the evaporation rate decreases, and the heat dissipation capacity is weakened.

[0013] In one embodiment according to the present invention, the housing is cylindrical.

[0014] In one embodiment according to the present invention, the flow layout of the cooling water and the water vapor can be at least one selected from countercurrent, co-current, and countercurrent / co-current mixed flow, that is, the flow pattern of the water vapor and the cooling water can be at least one selected from counter-flow, co-flow, and both counter-flow and co-flow. Correspondingly, the water vapor exhaust port can be at least one selected from being on the same side as the cooling water inlet, on the same side as the cooling water outlet, and between the two, which is specifically determined according to the layout inside the extravehicular spacesuit.

[0015] The beneficial effects of the present invention include:

[0016] (1) The membrane evaporation heat dissipation technology utilizes the characteristic of the large latent heat of vaporization of water, can efficiently handle the high heat flux load generated by human metabolism during spacewalk activities, and is not restricted by the environmental back pressure, breaking through the inherent limitation that the existing water sublimator cannot be applied to back pressure conditions above the triple point pressure of water, and can be applied to future manned Mars missions;

[0017] (2) The hydrophobic hollow fiber membrane can prevent liquid cooling water from entering the membrane pores, only allowing water vapor to pass through, avoiding the breakdown phenomenon, and providing a stable gas-liquid interface for the evaporation process to ensure the stable and controllable evaporation process;

[0018] (3) The hollow fiber membrane tubes are uniformly filled in the housing, which can avoid the formation of dead zones for water vapor flow and ensure that the mass transfer area of each hollow fiber membrane tube can be effectively utilized;

[0019] (4) The filling quantity of the hollow fiber membrane tubes is determined by optimized calculation according to the structural and working condition parameters, which not only avoids insufficient mass transfer area caused by too few filling quantities, but also avoids too large a water vapor flow resistance caused by too many filling quantities, resulting in too high a local back pressure and thus a decrease in the mass transfer driving force. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of a uniformly filled hollow fiber membrane evaporation radiator according to one embodiment of the present invention.

[0021] Figure 2 It is a schematic diagram of the membrane tube support structure according to one embodiment of the present invention.

[0022] Figure 3 Schematic diagram of the membrane tube filling process according to an embodiment of the present invention. Detailed implementation manners

[0023] The technical solution of the present invention will be described below in conjunction with the accompanying drawings and specific implementation manners.

[0024] As Figure 1 shown, a uniformly filled hollow fiber membrane evaporation radiator according to an embodiment of the present invention includes: a hollow fiber membrane tube 1, a membrane tube support 2, a housing 3, a cooling water inlet head 4, a cooling water outlet head 5, a cooling water inlet end 6, a cooling water outlet end 7, a cooling water inlet joint 8, a cooling water outlet joint 9, a water vapor exhaust port 10, and a back pressure valve 11. Among them, the hollow fiber membrane tube 1 is arranged on the membrane tube support 2, and the membrane tube support 2 is arranged in the cylindrical housing 3; the hollow fiber membrane tube 1 divides the space inside the housing 3 into a shell side space and a tube side space, the shell side space is filled with water vapor, and the tube side space is filled with cooling water; the cooling water inlet head 4 and the cooling water outlet head 5 separate the water vapor in the shell side space from the cooling water in the cooling water inlet end 6 and the cooling water outlet end 7.

[0025] Cooling water flows into the hollow fiber membrane evaporation radiator from the cooling water inlet joint 8, is distributed to each hollow fiber membrane tube 1 in the cooling water inlet end 6, flows inside the tube, water vapor evaporates from the cooling water, and penetrates out through the micropores in the wall of the hollow fiber membrane tube 1, flows outside the tube, and finally discharges from the water vapor exhaust port 10. The process of water vapor evaporating from the cooling water absorbs the heat in the cooling water, thereby cooling the cooling water in the form of latent heat. The cooled cooling water flows out of each hollow fiber membrane tube 1 and converges in the cooling water outlet end 7, and then flows out from the cooling water outlet joint 9 and is sent to the liquid cooling channel of the extravehicular spacesuit to dissipate heat for the object. The heated cooling water returns to the cooling water inlet joint 8 to complete a heat dissipation cycle.

[0026] The hollow fiber membrane tube 1 is a hydrophobic porous material that separates the cooling water from the evaporated water vapor and provides a stable gas-liquid interface for the evaporation process. Among them, the cooling water is blocked by the surface tension of the membrane pore wall and will not enter the membrane pores, while the water vapor can enter. The water vapor penetrates in the membrane pores in the form of Knudsen diffusion, and its mass transfer driving force is the difference between the saturated vapor pressure of the cooling water in the tube side space and the vapor pressure in the shell side space.

[0027] The saturated vapor pressure of the cooling water in the tube side space is determined by the temperature of the cooling water itself. The higher the temperature, the higher the saturated vapor pressure. Only when the saturated vapor pressure of the cooling water in the tube side space is higher than the vapor pressure in the shell side space, the hollow fiber membrane evaporation radiator has the ability of evaporation heat dissipation. Among them: in the completely vacuum space environment, the vapor pressure in the shell side space is the absolute pressure of water vapor; in the high-altitude atmosphere environment of the earth, the vapor pressure in the shell side space is the partial pressure of water vapor in the air / water vapor mixed gas; in the Mars atmosphere environment, the vapor pressure in the shell side space is the partial pressure of water vapor in the Mars atmosphere (mainly carbon dioxide) / water vapor mixed gas.

[0028] The heat dissipation capacity of the hollow fiber membrane evaporation radiator is adjusted by the back pressure valve 11. Among them: when the opening of the back pressure valve 11 increases, the vapor pressure in the shell side space decreases, the mass transfer driving force increases, the evaporation rate increases, and the heat dissipation capacity is enhanced; when the opening of the back pressure valve 11 decreases, the vapor pressure in the shell side space increases, the mass transfer driving force decreases, the evaporation rate decreases, and the heat dissipation capacity is weakened.

[0029] The filling quantity of the hollow fiber membrane tube 1 is not the more the better, but there is an optimal value, which is related to parameters such as the pore characteristics, diameter, wall thickness, length, inner diameter of the shell and operating conditions of the hollow fiber membrane tube 1, and can be determined by heat and mass transfer theory calculation.

[0030] The flow layout of the cooling water and water vapor can be at least one selected from countercurrent, cocurrent, countercurrent / cocurrent mixed flow, that is, the water vapor and the cooling water can flow in opposite directions, in the same direction, or both in opposite and in the same direction. Correspondingly, the water vapor exhaust port 11 can be at least one selected from being arranged on the same side of the cooling water inlet, on the same side of the cooling water outlet, and between the two, which is specifically determined according to the layout inside the extravehicular spacesuit.

[0031] As Figure 2 shown, it is the hollow fiber membrane tube support structure of the uniformly filled hollow fiber membrane evaporation radiator according to an embodiment of the present invention. Among them, the membrane tube support 2 includes a first support ring 2-1, a second support ring 2-2, and support beams 2-3. Both ends of the support beams 2-3 are respectively connected to the first support ring 2-1 and the second support ring 2-2. The first support ring 2-1 and the second support ring 2-2 are multi-layer annular structures. Figure 2 Only one layer is shown, and the layers are concentrically arranged. Each layer is evenly provided with membrane tube grooves, and the size of the membrane tube grooves is slightly larger than the diameter of the hollow fiber membrane tube 1 for placing the hollow fiber membrane tube 1. The hollow fiber membrane tubes 1 are uniformly arranged both axially and radially in the shell 3 to avoid the appearance of flow dead zones in the shell side space and ensure that the mass transfer area of each hollow fiber membrane tube 1 can be effectively utilized.

[0032] As Figure 3As shown, it is a method for filling hollow fiber membrane tubes of a uniformly filled hollow fiber membrane evaporation radiator according to an embodiment of the present invention. First, as shown in step 1, prepare the first layer of membrane tube support 2; then, as shown in step 2, fill the first layer of membrane tube support 2. Place both ends of the hollow fiber membrane tube 1 in the membrane tube grooves of the first support ring 2-1 and the second support ring 2-2 respectively. Inject quick-drying glue into the membrane tube groove of the first support ring 2-1, and use the solidified quick-drying glue to fix one end of the hollow fiber membrane tube 1 in the membrane tube groove. Then, hold the other end of the hollow fiber membrane tube 1 and straighten the hollow fiber membrane tube 1. Also inject quick-drying glue into the membrane tube groove of the second support ring 2-2, and use the solidified quick-drying glue to fix the other end of the hollow fiber membrane tube 1 in the membrane tube groove of the second support ring 2-2, and the hollow fiber membrane tube 1 is in a straightened state. Repeat this process to fill all the membrane tube grooves of the first layer of membrane tube support 2 with the hollow fiber membrane tubes 1. At this time, all the hollow fiber membrane tubes 1 are in a straightened state and will not sag significantly under the action of gravity, and the hollow fiber membrane tubes 1 do not connect with each other but are evenly arranged parallel to the circumference; then, as shown in step 3, fill the second layer of membrane tube support 2 with a smaller diameter in the same process. Put the filled second layer of membrane tube support 2 into the first layer of membrane tube support 2, select several points in the gap between the two layers of membrane tube supports 2 to inject quick-drying glue, and fix the two layers of membrane tube supports 2 to each other; repeat the above steps to finally complete all the membrane tube filling work. Such a multi-layer concentric nested membrane tube support 2 together with the filled hollow fiber membrane tubes 1 constitutes the core structure of the hollow fiber membrane evaporation radiator. Its encapsulation in the housing 3 is a conventional process, similar to the encapsulation process of all hollow fiber membrane components, which will not be elaborated here.

[0033] The above are only specific application examples of the present invention and do not constitute any limitation to the protection scope of the present invention. Any technical solutions formed by equivalent transformation or equivalent substitution fall within the scope of the protection of the present invention.

Claims

1. A uniformly filled hollow fiber membrane evaporation radiator, characterized in that Comprising: A hollow fiber membrane tube (1), a membrane tube support (2), a housing (3), a cooling water inlet head (4), a cooling water outlet head (5), a cooling water inlet end (6), a cooling water outlet end (7), a cooling water inlet joint (8), a cooling water outlet joint (9), a steam vent (10), and a back pressure valve (11). Wherein: The hollow fiber membrane tube (1) is arranged on the membrane tube support (2); The membrane tube support (2) is arranged inside the housing (3); The hollow fiber membrane tube (1) divides the space inside the housing (3) into a shell side space and a tube side space. The shell side space is filled with steam, and the tube side space is filled with cooling water; The cooling water inlet head (4) and the cooling water outlet head (5) separate the steam in the shell side space from the cooling water in the cooling water inlet end (6) and the cooling water outlet end (7); The membrane tube support (2) includes a first support ring (2-1), a second support ring (2-2), and support beams (2-3); Both ends of the support beam (2-3) are respectively connected to the first support ring (2-1) and the second support ring (2-2); The first support ring (2-1) and the second support ring (2-2) are multi-layer annular structures, which are concentrically arranged between layers, and each layer is evenly provided with membrane tube grooves; The size of the membrane tube groove is slightly larger than the diameter of the hollow fiber membrane tube (1), and the membrane tube groove is used to place the hollow fiber membrane tube (1); The hollow fiber membrane tubes (1) are evenly arranged both axially and radially in the housing (3) to avoid flow dead zones in the shell side space and ensure that the mass transfer area of each hollow fiber membrane tube (1) can be effectively utilized.

2. The hollow fiber membrane evaporation radiator according to claim 1, characterized in that: Cooling water flows into the hollow fiber membrane evaporation radiator from the cooling water inlet joint (8), is distributed to each hollow fiber membrane tube (1) in the cooling water inlet end (6), and flows inside the hollow fiber membrane tube (1); Steam evaporates from the cooling water, penetrates into the shell side space through the micropores in the wall of the hollow fiber membrane tube (1), flows in the shell side space, and finally discharges from the steam vent (10); The heat in the cooling water is absorbed during the evaporation process of the steam from the cooling water, so that the cooling water is cooled in the form of latent heat. The cooled cooling water flows out of each hollow fiber membrane tube (1), converges in the cooling water outlet end (7), and then flows out from the cooling water outlet joint (9) and is sent to the liquid cooling channel of the extravehicular spacesuit to dissipate heat for the object. The heated cooling water returns to the cooling water inlet joint (8) to complete a heat dissipation cycle.

3. The hollow fiber membrane evaporation radiator according to claim 1, characterized in that: The hollow fiber membrane tube (1) is a hydrophobic porous material, which separates the cooling water from the evaporated steam and provides a stable gas-liquid interface for the evaporation process. The cooling water is blocked by the surface tension of the membrane pore wall and does not enter the membrane pores, while the steam can enter; The steam penetrates in the membrane pores in the form of Knudsen diffusion, and its mass transfer driving force is the difference between the saturated vapor pressure of the cooling water in the tube side space and the vapor pressure in the shell side space.

4. The hollow fiber membrane evaporation radiator according to claim 1, characterized in that: The saturated vapor pressure of the cooling water in the tube side space is determined by the temperature of the cooling water itself. The higher the temperature, the higher the saturated vapor pressure. Only when the saturated vapor pressure of the cooling water in the tube side space is higher than the vapor pressure in the shell side space, the hollow fiber membrane evaporation radiator has the ability of evaporative heat dissipation.

5. The hollow fiber membrane evaporation radiator according to claim 1, characterized in that: The heat dissipation capacity of the hollow fiber membrane evaporation radiator is adjusted by the back pressure valve (11), wherein: When the opening of the back pressure valve (11) increases, the vapor pressure in the shell side space decreases, the mass transfer driving force increases, the evaporation rate increases, and the heat dissipation capacity is enhanced; When the opening of the back pressure valve (11) decreases, the vapor pressure in the shell side space increases, the mass transfer driving force decreases, the evaporation rate decreases, and the heat dissipation capacity is weakened.

6. The hollow fiber membrane evaporation radiator according to claim 1, wherein: The housing (3) is cylindrical.

7. The hollow fiber membrane evaporation radiator according to claim 1, characterized in that The flow layout of the cooling water and water vapor can be selected from one of the following layouts: A) Countercurrent, where the water vapor and the cooling water flow in opposite directions, B) Co-current, where the water vapor and the cooling water flow in the same direction, C) Countercurrent / co-current mixed flow, where the water vapor and the cooling water have both opposite and same direction flows.

8. The hollow fiber membrane evaporation radiator according to claim 1, wherein The arrangement of the water vapor exhaust port (11) is selected from one of the following methods: The water vapor exhaust port (11) is arranged on the same side as the cooling water inlet, The water vapor exhaust port (11) is arranged on the same side as the cooling water outlet, The water vapor exhaust port (11) is arranged between the cooling water inlet and the cooling water outlet.

9. The filling method of the hollow fiber membrane tube of the hollow fiber membrane evaporation radiator according to any one of claims 1-8, characterized in that Including: S1) Fill the first layer of membrane tube support (2). Place both ends of the hollow fiber membrane tube (1) in the membrane tube grooves of the first support ring (2-1) and the second support ring (2-2), including: S11) Inject quick-drying glue into the membrane tube groove of the first support ring (2-1), and use the solidified quick-drying glue to fix one end of the hollow fiber membrane tube (1) in the membrane tube groove. S12) Then hold the other end of the hollow fiber membrane tube (1), straighten the hollow fiber membrane tube (1), inject quick-drying glue into the membrane tube groove of the second support ring (2-2), and use the solidified quick-drying glue to fix the other end of the straightened hollow fiber membrane tube (1) in the membrane tube groove of the second support ring (2-2). S13) Repeat S11) and S12) to fill all the membrane tube grooves of the first layer of membrane tube support (2) with the hollow fiber membrane tube (1). S2) Then perform the same operation as S1) to fill the second layer of membrane tube support (2) with a smaller diameter. S3) Put the filled second layer of membrane tube support (2) into the first layer of membrane tube support (2). S4) Select several points in the gap between the two layers of membrane tube supports (2) to inject quick-drying glue to fix the two layers of membrane tube supports (2) to each other. S5) Repeat the above steps S1) to S4) until all the membrane tube filling work is completed to obtain a multi-layer concentrically nested membrane tube support (2).

10. The filling method according to claim 9, characterized in that Further including: Encapsulate the multi-layer concentrically nested membrane tube support (2) in the housing (3).

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