A device for realizing micro-ice crystal freezing, thawing

Abstract

The application discloses a device for realizing micro-ice crystal freezing and melting, which comprises a micro-ice crystal suspension freezing device and an ice crystal melting device; the micro-ice crystal suspension freezing device is used for generating micro-ice crystal particles which are suspended in the air and do not directly contact with a wall surface; the ice crystal melting device is used for controlling temperature and gradually melting the ice crystals under certain conditions; the micro-ice crystal suspension freezing device comprises a water chiller, an ice crystal suspension freezing assembly, a temperature controller, a temperature sensor and a direct-current adjustable power supply. The device for realizing micro-ice crystal freezing and melting can generate ice crystals with different particle sizes and is provided with a melting device, thereby laying a foundation for measuring the temperature and the melting rate in the freezing generation and the melting process of the ice crystals with different particle sizes.

Description

Technical Field

[0001] This invention relates to a device for freezing and melting tiny ice crystals. Background Technology

[0002] Ice crystals ingested by aircraft engines severely impact aircraft safety and operational stability. Unlike supercooled droplets, ice crystals can accumulate in areas above freezing, meaning their accretion zone can penetrate deep into the engine, affecting aerodynamic performance and even damaging mechanical structures. After being ingested into the engine's internal flow channels, ice crystals first undergo a melting phase transition, then impact engine components as an ice-water mixture. Subsequent issues such as ice crystal collision, fragmentation, splashing, adhesion, and erosion are all closely related to the melting stage of the ice crystals, making the mechanism exceptionally complex. Conducting freeze-thaw experiments on individual micro-ice crystals to obtain the characteristics of the ice crystal phase transition stage is fundamental and a prerequisite for revealing the ice crystal formation mechanism within engines, and is of great significance for accurately predicting ice crystal formation and preventing / de-icing.

[0003] Current research on the melting process of micro-ice crystals focuses on theoretical analysis and numerical calculations, while related experiments are urgently needed. The difficulty of experimental research lies in generating micro-ice crystals with controllable particle sizes, controlling factors affecting ice crystal melting and freezing, and creating a stable environment for measuring relevant parameters of the ice crystal melting process. There are very few relevant experimental devices both domestically and internationally. For ice crystal generation, methods either use liquid nitrogen to freeze droplets or collect micro-ice crystal particles from supercooled walls. However, the obtained ice crystals may have uncontrollable particle sizes or not be naturally formed, which does not match reality. For ice crystal suspension, ultrasonic suspension is mainly used. However, due to the influence of ambient temperature, airflow, etc., vibrations and overturning inevitably occur during the ice crystal melting process, affecting the melting and related measurements. Summary of the Invention

[0004] In view of this, the present invention provides an apparatus for freezing and melting micro ice crystals, capable of producing ice crystals of different sizes, and equipped with a melting device, laying the foundation for studying the measurement of temperature and melting rate during the freezing and melting process of ice crystals of different sizes.

[0005] To address the aforementioned problems, embodiments of the present invention provide an apparatus for freezing and melting tiny ice crystals, characterized in that:

[0006] Includes a micro-ice crystal suspension freezing device and an ice crystal melting device;

[0007] The micro ice crystal suspension freezing device is used to generate micro ice crystal particles that are suspended in the air and do not directly contact the wall surface; the ice crystal melting device is used to control the temperature and make the ice crystals gradually melt under certain conditions.

[0008] The micro ice crystal suspension freezing device includes a chiller, an ice crystal suspension freezing component, a temperature controller, a temperature sensor, and a DC adjustable power supply.

[0009] The ice crystal suspension freezing assembly includes a housing and, from bottom to top, a freezing device base, a silicone pad, a microchannel water-cooled heat exchanger, a sponge layer, a second-stage cooling plate, a top cover, and a cooling guide plate. The housing includes a main body and a drawer-type suspension support. The main body has openings at the top and bottom. The cooling guide plate extends into the main body from the bottom opening. Through holes are formed in the lower parts of two opposite side walls of the main body. The drawer-type suspension support passes through these through holes and can move horizontally within them. The suspension support includes a plate-like structure with two through rectangular holes. A silver wire is arranged inside one of the rectangular holes, and the silver wire is bent into circular silver rings of different diameters in the middle. The base of the freezing device has a groove in the middle. The inlet and outlet pipes of the chiller enter the groove and then connect to the inlet and outlet of the microchannel water-cooled heat exchanger. A filter is installed on the inlet pipe of the chiller. The upper cover plate and the base of the freezing device are fixed with bolts to fix the silicone pad, the microchannel water-cooled heat exchanger, the sponge layer, and the second-stage refrigeration plate.

[0010] The temperature controller is used to control the operation of the second-stage thermoelectric cooler. The DC adjustable power supply is connected to the temperature controller, and the temperature sensor is used to obtain the temperature of the second-stage thermoelectric cooler.

[0011] In some embodiments, the ice crystal melting device includes a water-cooled heat exchanger, a constant-temperature circulating water bath, a filter, and an insulation pipe;

[0012] The water-cooled heat exchanger is installed on the side wall outside the housing. The constant temperature circulating water bath is connected to the water-cooled heat exchanger through an insulation pipe. A filter is installed on the insulation pipe connected to the outlet of the water-cooled heat exchanger.

[0013] In some embodiments, small holes are provided on the side of the box to allow hot air to flow into the box, thereby creating conditions for ice crystal melting.

[0014] In some embodiments, the cooling plate includes a copper U-shaped plate, the bottom of which is connected to the cold surface of the second-stage cooling plate, the two wings of which are provided with serrated ribs, and the inner wall between the two wings of which is provided with multiple channels.

[0015] In some embodiments, the upper part of the microchannel water-cooled heat exchanger is provided with a boss structure, which can fit more closely with the hot surface of the second-stage cooling chip for heat dissipation. At the same time, the contact surface is uniformly coated with high-performance thermally conductive silicone grease to reduce contact thermal resistance.

[0016] In some embodiments, the sponge layer is wrapped around the periphery of the second-order cooling chip to reduce heat transfer between the cold and hot surfaces; the heat-conducting sheet is bonded to the cold end of the cooling chip using high-performance thermal grease.

[0017] In some embodiments, the two ends of the silver wire are respectively fixed to the edge of the rectangular hole in the drawer-type suspension bracket, and the silver ring is located in the middle of the rectangular hole.

[0018] In some embodiments, a microsample injector is also included for injecting droplets into the silver ring.

[0019] In some embodiments, the micro-ice crystal suspension freezing device further includes an ultra-fine thermocouple inserted into the interior of a droplet on a silver ring to obtain temperature data of the melting process.

[0020] Compared with the prior art, the apparatus of the present invention for freezing and melting tiny ice crystals has at least the following beneficial effects:

[0021] 1) The micro ice crystal suspension freezing device of the present invention can realize the suspension freezing generation of ice crystals of different particle sizes with high repeatability;

[0022] 2) The micro ice crystal suspension freezing device of the present invention has stable particle position during the freezing and melting process of ice crystals and will not vibrate, which can prevent frost formation on the surface of ice crystals and facilitate the observation and measurement of the freezing and melting morphology of ice crystal particles.

[0023] 3) The measurement system provided by this invention is a visual experimental device that can be used for temperature measurement and melting rate measurement during the freezing and melting process of tiny ice crystals;

[0024] 4) This invention can be used to conduct melting experiments and measurements of ice crystals under various environments such as constant wall temperature, constant hot airflow, and changing airflow.

[0025] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the device provided by the present invention for freezing and melting tiny ice crystals;

[0028] Figure 2 A structural diagram of a device for suspending and freezing tiny ice crystals;

[0029] Figure 3 An exploded view of a device for suspending and freezing tiny ice crystals;

[0030] Figure 4 Structural diagram of the box body and drawer-type suspension bracket;

[0031] Figure 5 This is a structural diagram of the heat exchanger.

[0032] Figure 6 This is a structural diagram of a microchannel water-cooled heat exchanger;

[0033] Figure 7 Images of completely frozen ice crystals and partially melted ice crystals obtained according to the present invention.

[0034] The attached figures are labeled as follows:

[0035] 1-Chiller; 2-Ice crystal suspension freezing assembly; 3-Temperature controller; 4-Temperature sensor; 5-DC adjustable power supply; 6-Water-cooled heat exchanger; 7-Constant temperature circulating water bath; 8-Second filter; 10-Ultra-fine thermocouple; 14-Small hole; 16-CCD camera; 17-Micro sample feeder;

[0036] 21-Box body; 22-Freezing device base; 23-Silicone pad; 24-Microchannel water-cooled heat exchanger; 25-Sponge layer; 26-Second-stage cooling plate; 27-Top cover; 28-Cooling plate; 101-First filter; 210-Drawer-type suspension bracket; 211-Silver wire; 241-Boss structure; 242-Water inlet; 243-Water outlet. Detailed Implementation

[0037] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0038] In the description of this invention, it should be clearly stated that the terms "first," "second," etc., in the specification, claims, and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0039] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] Example 1

[0041] This embodiment provides a device for freezing and melting tiny ice crystals, see [link to device]. Figure 1 The system includes a micro-ice crystal suspension and freezing device and an ice crystal melting device. The micro-ice crystal suspension and freezing device is used to generate micro-ice crystal particles that are suspended in the air and do not directly contact the wall surface, while the ice crystal melting device is used to control the temperature and gradually melt the ice crystals under set conditions.

[0042] See Figure 1 The micro-ice crystal suspension freezing device includes a chiller 1, an ice crystal suspension freezing assembly 2, a temperature controller 3, a temperature sensor 4, and a DC adjustable power supply 5. Because the required ice crystal particle size is very small, the required cooling capacity is very small, and rapid and precise cooling is required, this system selects semiconductor refrigeration as the cooling method. The temperature controller 3 is a semiconductor refrigeration temperature controller; the temperature sensor 4 is a PT1000 resistance temperature sensor.

[0043] See Figure 2 and Figure 3 The ice crystal suspension freezing assembly 2 includes a housing 21 and, arranged sequentially from bottom to top, a freezing device base 22, a silicone pad 23, a microchannel water-cooled heat exchanger 24, a sponge layer 25, a second-stage cooling plate 26, an upper cover plate 27, and a cooling plate 28.

[0044] The enclosure 21 includes a main body and a drawer-type suspension support 210. The main body has openings at the top and bottom. A cooling fin 28 extends into the main body from the bottom opening. Corresponding through holes are provided on the lower parts of two opposite side walls of the main body. The drawer-type suspension support 210 passes through these through holes and can move horizontally back and forth within them. The drawer-type suspension support 210 includes a plate-like structure with two through rectangular holes. A silver wire 211 is arranged in one of these rectangular holes; this rectangular hole serves as an ice crystal suspension hole. The silver wire 211 is bent into circular silver rings of different diameters in the middle. See details... Figure 4 The two ends of the silver wire 211 are respectively fixed to the edge of the rectangular hole in the drawer-type suspension bracket 210, and the silver ring is located in the middle of the rectangular hole. The drawer-type suspension bracket 210 moves horizontally back and forth in the through hole, so that one of the rectangular holes can be independently located in the box body.

[0045] The freezing device base 22 has a boss structure with four threaded holes for fixing various components. A groove is cut into the center of the boss structure, through which the inlet and outlet pipes of the chiller 1 enter and connect to the inlet 242 and outlet 243 of the microchannel water-cooled heat exchanger 24. A first filter 101 is installed on the inlet pipe of the chiller 1 to filter impurities in the medium in the circuit, preventing them from clogging the microchannels within the microchannel water-cooled heat exchanger 24. The upper cover 27 and the freezing device base 22 are fixed with bolts to secure the silicone pad 23, the microchannel water-cooled heat exchanger 24, the sponge layer 25, and the second-stage cooling plate 26, ensuring a tight connection of the entire multi-layered composite structure. The silicone pad 23 on the top of the freezing device base 22 helps to mitigate the impact of vibrations caused by fluid flow in the pipes on the microchannel water-cooled heat exchanger 24, making experiments and observations more stable.

[0046] The temperature controller 3 controls the operation of the second-stage thermoelectric cooler 26. The DC adjustable power supply 5 is connected to the temperature controller 3, and the temperature sensor 4 is used to acquire the temperature of the second-stage thermoelectric cooler 26. The DC adjustable power supply 5 supplies power to the temperature controller 3, which receives the surface temperature signal of the second-stage thermoelectric cooler 26 from the PT100 resistance temperature sensor 4. Based on a comparison with a preset temperature, the temperature controller 3 adjusts the power output to the second-stage thermoelectric cooler 26 to ensure its surface temperature reaches the preset value. After the second-stage thermoelectric cooler 26 in the ice crystal suspension freezing assembly 2 begins operation under the control of the temperature controller 3, the chiller 1 needs to be turned on to circulate cooling water into the microchannel water-cooled heat exchanger 24 to dissipate heat from the hot end of the second-stage thermoelectric cooler 26.

[0047] As a preferred embodiment of the present invention, see [link to previous document]. Figure 5 The heat-conducting plate 28 is a copper heat-conducting plate. The heat-conducting plate 28 includes a copper U-shaped plate. The bottom of the copper U-shaped plate is used to connect with the cold surface of the secondary cooling plate 26. The two wings of the copper U-shaped plate are provided with serrated ribs. The inner wall between the two wings of the copper U-shaped plate is provided with multiple U-shaped channels from the inside to the outside to increase the heat exchange area. The heat-conducting plate 28 uses high-performance thermal grease to adhere to the cold surface of the secondary cooling plate 26, which can better create a low-temperature environment for freezing droplets.

[0048] As a preferred embodiment of the present invention, see [link to previous document]. Figure 6 The microchannel water-cooled heat exchanger 24 has a small boss structure on its upper part, which can fit more closely with the hot surface of the second-stage cooling chip 26 for heat dissipation. At the same time, high-performance thermally conductive silicone grease is uniformly coated on the contact surface to reduce contact thermal resistance. The water inlet 242 and water outlet 243 of the microchannel water-cooled heat exchanger 24 are located at the bottom and are used to connect to the water inlet pipe and water outlet pipe of the chiller 1.

[0049] As a preferred embodiment of the present invention, see [link to previous document]. Figure 3 The sponge layer 25 has a central hole, which allows the second-stage cooling chip 26 to be embedded in the hole of the sponge layer 25, thereby reducing heat transfer between the cold and hot surfaces of the second-stage cooling chip 26.

[0050] As a preferred embodiment of the present invention, see [link to previous document]. Figure 1 The ice crystal melting device includes two water-cooled heat exchangers 6 and a constant-temperature circulating water bath 7. The two water-cooled heat exchangers 6 are arranged opposite each other on the side wall of the outer casing 21. The constant-temperature circulating water bath 7 is connected to the water-cooled heat exchangers 6 via insulated pipes. A second filter 8 is installed on the insulated pipe connected to the outlet of each water-cooled heat exchanger 6. The second filter 8 is used to filter impurities in the medium within the circuit. The ice crystal melting device is used to control the temperature and gradually melt the ice crystals under set conditions.

[0051] See Figure 4 Alternatively, small holes 14 can be made on the side of the box 21 to allow hot air to be introduced into the box 21 through the small holes 14 to create conditions for melting ice crystals.

[0052] As a preferred embodiment of the present invention, see [link to previous document]. Figure 1 The ice crystal suspension freezing component 2 also includes an ultrafine thermocouple 10.

[0053] See Figure 4 A wire groove is provided on the edge of the drawer-type suspension support 210 for placing an ultra-fine thermocouple 10. The ultra-fine thermocouple 10 is inserted into the droplet on the silver ring to obtain temperature data of the melting process. A CCD camera 16 is set above the box 21 to acquire images of the ice crystal melting process.

[0054] The working process of this invention is as follows:

[0055] 1. Making ice crystals

[0056] Pull out the ice crystal suspension hole of the drawer-type suspension bracket 210 so that another rectangular hole is located inside the main body of the chamber. Power the temperature controller 3 through the DC adjustable power supply 5, set the temperature to be reached inside the main body of the chamber, and turn on the temperature controller 3. The temperature controller 3 receives the temperature signal from the temperature sensor 4 and compares it with the preset value, adjusting the power output to the second-stage cooling chip 26 to reach and maintain the preset temperature. Some water vapor in the air inside the main body of the chamber gradually sublimates, and the water vapor content in the air gradually reaches saturation. After the temperature of the cooling chip stabilizes, inject droplets into the silver ring using the micro-sample feeder 17, insert the ultrafine thermocouple into the center of the droplet without contacting the silver ring, and fix the ultrafine thermocouple on the surface of the drawer-type bracket. Then push the ice crystal suspension hole into the main body of the chamber. The ultrafine thermocouple can obtain the ice crystal temperature curve during the freezing and melting process. At this time, no frost crystals will form on the surface of the droplet after freezing. The diameter of the silver ring can be adjusted here to produce ice crystals of different sizes.

[0057] 2. Manufacturing melting rate conditions

[0058] The chamber has transparent walls and an open top, providing conditions for various melting rate measurement methods. These include visually determining the melting rate by acquiring images of the melting process, indirectly determining the melting rate by observing changes in the projected area of ​​ice crystal particles, or calculating the melting rate by using laser-induced fluorescence to measure the different luminescence intensities of partially melted ice crystals. Regardless of the method used, data acquisition begins after the ice crystals are completely frozen, while the voltage output of the temperature controller is simultaneously turned off to stop cooling. Once the ice crystals have completely melted, data acquisition stops and is stored for later calculation of the ice crystal melting rate.

[0059] There are two methods to melt ice crystals under constant wall temperature conditions: First, multiple water-cooled heat exchangers are attached to the cavity wall, and the fluid temperature inside the water-cooled heat exchangers is adjusted by a constant temperature circulating water bath to achieve experimental conditions for melting ice crystals at different cavity wall temperatures; Second, an airflow of a certain temperature can be introduced into the cavity to create melting conditions in a hot airflow.

[0060] It will be readily understood by those skilled in the art that, without conflict, the aforementioned advantageous technical features can be freely combined and superimposed.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A device for freezing and melting tiny ice crystals, characterized in that: Includes a micro-ice crystal suspension freezing device and an ice crystal melting device; The micro ice crystal suspension freezing device is used to generate micro ice crystal particles that are suspended in the air and do not directly contact the wall surface. The ice crystal melting device is used to control the temperature and make the ice crystals gradually melt under set conditions. The micro ice crystal suspension freezing device includes a chiller (1), an ice crystal suspension freezing component (2), a temperature controller (3), a temperature sensor (4), and a DC adjustable power supply (5). The ice crystal suspension freezing assembly (2) includes a housing (21) and, from bottom to top, a freezing device base (22), a silicone pad (23), a microchannel water-cooled heat exchanger (24), a sponge layer (25), a second-stage cooling plate (26), a top cover (27), and a cooling plate (28). The housing (21) includes a housing body and a drawer-type suspension support (210). The housing body has openings at the top and bottom. The cooling plate (28) extends into the housing body from the bottom opening. Through holes are opened at the bottom of the two opposite side walls of the housing body. The drawer-type suspension support (210) passes through the through holes and can move horizontally within the through holes. The frame (210) includes a plate-like structure with two through rectangular holes. A silver wire (211) is arranged in one of the rectangular holes. The silver wire (211) is bent into a circular silver ring of different diameters in the middle. The freezing device base (22) has a groove in the middle. The water inlet pipe and water outlet pipe of the chiller (1) enter the groove and are then connected to the water inlet and water outlet of the microchannel water-cooled heat exchanger (24). The water inlet pipe of the chiller (1) is equipped with a first filter (101). The upper cover plate (27) and the freezing device base (22) are fixed by bolts to fix the silicone pad (23), the microchannel water-cooled heat exchanger (24), the sponge layer (25), and the second-stage cooling plate (26). The temperature controller (3) is used to control the operation of the second-stage thermoelectric cooler (26). The DC adjustable power supply (5) is connected to the temperature controller (3). The temperature sensor (4) is used to obtain the temperature of the second-stage thermoelectric cooler (26).

2. The apparatus for freezing and melting micro-ice crystals according to claim 1, characterized in that: The ice crystal melting device includes a water-cooled heat exchanger (6) and a constant temperature circulating water bath (7); The water-cooled heat exchanger (6) is installed on the side wall outside the box (21). The constant temperature circulating water bath (7) is connected to the water-cooled heat exchanger (6) through the heat insulation pipe. The heat insulation pipe connected to the outlet of the water-cooled heat exchanger (6) is equipped with a second filter (8).

3. The apparatus for freezing and melting micro-ice crystals according to claim 1, characterized in that: The box (21) has a small hole (14) on its side, through which hot air is introduced into the box (21).

4. The apparatus for freezing and melting micro-ice crystals according to any one of claims 1-3, characterized in that: The cooling plate (28) includes a copper U-shaped plate. The bottom of the copper U-shaped plate is connected to the cold surface of the second-stage cooling plate (26). The two wings of the copper U-shaped plate are provided with serrated ribs, and the inner wall between the two wings of the copper U-shaped plate is provided with multiple channels.

5. The apparatus for freezing and melting micro-ice crystals according to claim 4, characterized in that: The microchannel water-cooled heat exchanger (24) has a boss structure on its upper part, which can fit more closely with the hot surface of the second-stage cooling chip (26) to dissipate heat. At the same time, the contact surface is uniformly coated with high-performance thermal conductive silicone grease to reduce the contact thermal resistance.

6. The apparatus for freezing and melting micro-ice crystals according to claim 5, characterized in that: The sponge layer (25) is wrapped around the periphery of the second-order cooling plate (26) to reduce heat transfer between the cold and hot surfaces; the heat-conducting plate (28) is bonded to the cold end of the cooling plate using high-performance thermal grease.

7. The apparatus for freezing and melting micro-ice crystals according to claim 6, characterized in that: The two ends of the silver wire (211) are respectively fixed to the edge of the rectangular hole in the drawer-type suspension bracket (210), and the silver ring is located in the middle of the rectangular hole.

8. The apparatus for freezing and melting micro-ice crystals according to claim 1, characterized in that: The micro-ice crystal suspension freezing device also includes a micro-sample feeder (17) for injecting droplets into the silver ring.

9. The apparatus for freezing and melting micro-ice crystals according to claim 8, characterized in that: The micro-ice crystal suspension freezing device also includes an ultra-fine thermocouple (10), which is inserted into the droplet on the silver ring to obtain temperature data of the melting process.

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