RU2798386C1 - Closed loop artificial freezing and icing unit - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention can be used in laboratory studies of the processes of icing of automobile, air and railway transport, ropes, wires and materials for power transmission line supports, as well as for testing materials used in arctic conditions. Personal computer 17 and controller 18 are introduced into the artificial freezing and icing unit with a closed circuit, with which a chilled water preparation and accurate dosing module is interfaced, including water flow meter 23, pressure converter 20, tank for cooling water 15 with level gauge 25, which is coupled with second unistat 14, compressor 16, reducer 27 and connected by pipeline 24 through water flow meter 23 to nozzle 5. At the same time, video camera 19, air speed and temperature sensor 28, fan 1, which is associated with frequency converter 29, and first unistat 13, which is associated with first heat exchanger 3/1 and second heat exchanger 3/2, are also interface with personal computer 17 and controller 18.

EFFECT: faster preparation of the test process, reduced complexity of tests and increased accuracy.

7 cl, 1 tbl, 1 dwg

Description

The invention relates to the field of mechanical engineering and can be used in laboratory studies of the processes of icing of automobile, air and railway transport, ropes, wires and materials for power transmission line supports, as well as for testing materials used in "arctic" conditions.

Recently, devices have been developed for ground testing of aircraft under conditions of crystalline icing. For example, in the utility model patent "Installation for simulating the flight of an aircraft in cloudy conditions" [RU No. 87142, IPC B64D 15/20, publication date 27.09.2009], the installation contains: a freezer and a device for preparing normalized ice cubes located inside it. crystals, a container with a stirrer, a screw dispenser connected to the outlet of the container, and a source of dry cold air.

The disadvantages of this device are high energy consumption, low accuracy of maintaining process parameters, high cost of creation and operation for laboratory research.

Known installation containing aero-cooling tube with an air flow temperature of up to -50°C [K. Saleh, D. Buttsworth, T. Yusaf "Development of a small icing wind tunnel for simulating the initial stages of solid phase ice accretion", 17th Australasian Fluid Mechanics Conference, Auckland, New Zealand, 5-9 December 2010]. Cooling of the stream to low temperatures in this installation is ensured by pumping it through a heat exchanger with dry ice (CO ₂ ) having a temperature of -79°C. The disadvantage of this device is the small cross-sectional area of the working part of the wind tunnel and the impossibility of increasing the flow velocity above 10 m/s.

Known installation, patent RU 1112880, IPC G01M 9/02, filing date 1982.12.30 (prototype), consisting of a cryogenic wind tunnel containing a prechamber, a working part, a diffuser with ejectors, a return channel, vertically placed cold regenerators with a nozzle and a system injection of refrigerant (liquid nitrogen) into the flow, including nozzles and pipelines for supplying liquid nitrogen to them. The nozzles of the liquid nitrogen injection system are installed in the cavity of the regenerator, while the nozzle of the regenerator is divided by nozzles into a number of sections unequal in height. However, the process of chilling regenerators with liquid nitrogen, due to their large cold capacity, is quite lengthy. The injection of liquid nitrogen into the pipe channel during its operation, which is necessary to maintain the specified flow temperature, requires complex control equipment and does not guarantee accurate temperature maintenance and high flow quality due to uneven evaporation of nitrogen droplets over the pipe channel cross section, and also does not allow selecting the mode parameters formation of drip, crystalline or mixed icing. Thus, the disadvantages of the prototype are the duration of the preparation of the test process, its complexity, low accuracy and the inability to obtain various types of icing.

The technical result of the invention is to speed up the preparation of the test process, reduce the complexity of the tests, increase their accuracy. The essence of the invention lies in the fact that a closed loop artificial freezing and icing installation contains a prechamber associated with the working part, in which a sample holder, a return channel, a nozzle are installed, a personal computer and a controller are introduced, with which a chilled water preparation module is associated and accurate dosing, including a water flow meter, a pressure converter, a tank for cooling water with a level gauge, which is coupled with a second unitat, a compressor, a reducer and connected by a pipeline through a water flow meter with a nozzle, while a video camera, a speed sensor and air temperature, a fan that is coupled with a frequency converter, and the first unistat that is coupled with the first heat exchanger and the second heat exchanger.

There is a variant in which a cyclone with two baffle grids with heating elements and a direct channel are introduced into the device, while the cyclone is associated with a direct channel and a return channel.

There is also a variant in which slopes are provided for natural water drainage on the direct channel from the fan to the cyclone and on the return channel from the cyclone to the fan.

There is also a variant in which the pre-chamber and the working part are connected into a unit made of transparent glass and optically coupled to the video camera.

There is also a variant in which a mechanical shaker is introduced into the device, coupled with a sample holder.

There is also a variant in which a heating element connected to the nozzle is introduced into the device.

There is also a variant in which the nozzle is installed with the possibility of changing its position.

The attached graphic materials show a diagram of the installation of artificial freezing and icing with a closed loop

Implementation of the invention

The installation contains a fan 1, which is connected to the first heat exchanger 3/1 via a direct channel 2. The rotation speed of the fan 1 is controlled by a frequency converter 29. The first heat exchanger 3/1 is connected to a prechamber 4 and a working part 6 coupled into a glass assembly. A nozzle 5, heated by a heating element 22, is placed in the prechamber 4, designed to create a water-air aerosol. Nozzle 5 is mounted on position change module 31. Compressed air from compressor 16 and chilled water from tank 15 through flow meter 23 are supplied to nozzle 5 through reducer 27. Level gauge 25 is installed in tank 15. Mechanical shaker 7 with sample holder 26 is installed in working part 6 for fixing samples 30. Video camera 19 is optically coupled with prechamber 4 and working part 6. Cyclone 8, with two fender grids 10 with heating elements 9 located inside, is coupled with direct channel 2 and return channel 12. On the return channel 12, between the cyclone 8 and fan 1, the second heat exchanger 3/2 is located. The first unit 13 through pipes 24 has the ability to cool or heat, using the first heat exchanger 3/1 and the second heat exchanger 3/2 of the air circulating in the installation, to temperatures in the range from plus 10°C to minus 60°C with an accuracy of 1° WITH. The second unistat 14 through pipes 24 has the possibility of cooling water in the tank 15, which is then fed into the nozzle 5.

As a fan 1, you can use a fan brand VTs 5-45 No. 4.25. As the first heat exchanger 3/1 and the second heat exchanger 3/2, heat exchangers of the brand 273TNG-1.6-M8/20G-1-1-K (F=4.27 m ² ) can be used. To automate the installation, a personal computer 17 with a control system based on the controller 18 is used. The controller 18 is connected to resistance temperature converters 20, a flow meter 23, a float level meter 25, an air velocity and temperature sensor 28, pressure converters 32 and pressure gauges 33. Heating elements 9 and a heating element 22 are connected to thermostat 21. The equipment used to automate the installation:

- personal computer 17 (you can use the adapted program "Master SCADA");

- control system based on controller 18 (you can use PLC110);

- resistance thermocouples 20 (can be used: DTS 065-Pt 100. B 3.100);

- float level gauge 25 (remote control can be used - I. 1250.5);

- air speed and temperature sensor 28 (EE75-VTB635/BN-V12T12 can be used);

- pressure transducers 32 (PD100I-DI 0.025-121-1.5 can be used);

- pressure gauges (TM-621R.00 (0-0.6MPa) can be used).

All the main elements of the installation are displayed on the mnemonic diagrams of a personal computer 17.

Description of operation of the freezing and icing installation

Power is supplied to the installation of artificial freezing and icing, the first unistat 13, the second unistat 14, the fan 1, the compressor 16 and the personal computer 17.

At the same time, you should make sure that fire and utility water enters the first unistat 13 and the second unistat 14. Then, using the MasterSCADA program, turn on in sequence: fan 1, first heat exchanger 3/1, second heat exchanger 3/2, first unistat 13, second unistat 14, water cooling in tank 15, compressor 16 and video camera 19. Samples 30 are installed in the working part 6 on a sample holder 26 with a mechanical shaker 7, having previously weighed them. Set on the reducer 27 pressure in the range of 1 atm. up to 5 atm., and on the flow meter 23 - the required water flow in the range from 1 l to 20 l per hour. When the working part 6 reaches the set temperature parameters from plus 10 to minus 60°C and the flow rate from zero to 200 km/h, the water spray system is switched on. They include a heating element 22 in the nozzle 5, heating elements 9 in the cyclone 8, as well as a mechanical shaker 7. The mode parameters for the formation of drip, crystalline and mixed icing are selected empirically and easily reproduced by fine adjustment of the installation control process using digitalization and automation.

As a result of these operations, the formed water-air aerosol, in the form of snow and ice crystals, enters the test sample 30 of the anti-icing coating or material. From this moment, one should start counting the duration of the test with fixation of snow and ice accumulation on the surface of sample 30, and study the dynamics of the development of these glacial processes.

Moisture and the resulting snow, not adhering to the sample 30, is directed from the working part 6 to the cyclone 8, where the specified mixture is collected and separated from the air flow, which continues to circulate with the help of a fan 1 in a closed circuit of the installation.

At the end of the test, the temperature of the air flow in the installation of artificial freezing and icing is raised to plus 20 ° C using the first thermostat 13, the snow mass collected in cyclone 8 is melted, and the resulting water is drained from cyclone 8 into a sewer or into a container 15 for cooling water.

The study of the dynamics of glacial processes on the surface of the sample 30, covered with an anti-icing compound or without it (blank test), should be carried out at constant values of the air flow rate, temperature and operating parameters of the nozzle 5. In this case, it is necessary to record the change in the mass of snow and ice accumulated on the above-mentioned sample 30. To obtain such a dependence, 10 minutes after the start of the test, it is necessary to stop the supply of air and water to the nozzle 5, turn off the fan 1, remove the sample 30 from the working part 6 and weigh them on a technical scale. After that, the sample 30 with ice and snow frozen on it should be fixed again with the holder 26 and quickly returned to the working part 6, continuing the test (to do this, turn on the fan 1 and supply air and water to the nozzle 5).

The described operation should be repeated every 10 minutes during the entire testing of sample 30, ultimately establishing the nature of the change in the mass of snow and ice accumulated on the indicated surface over time.

Based on a comparison of the dynamics of glacial processes that occurred on the surface of sample 30 without coating (blank test) and with coating, one should draw a conclusion about its anti-icing effectiveness.

Example

The purpose of the tests: to evaluate the effectiveness of anti-icing protection of solids using organosilicon coatings based on studying the dynamics of the development of glacial processes on their surfaces.

Test parameters: Air speed = 100 km/h, working chamber temperature = minus 5°C, air pressure = 2 atm., water pressure = 4 atm., water supply rate 2 l/h, mode - for the formation of crystalline icing, mechanical shaker off.

Test results:

Conclusions: on the surface of the samples coated with an organosilicon composition, with crystalline icing with the shaker turned off, an average of 40% less icing is observed than on a sample without AOP. After 30 minutes, the growth of frost stops.

Technical results

The fact that a personal computer 17 and a controller 18 are introduced into the installation of artificial freezing and icing with a closed circuit, with which a chilled water preparation and accurate dosing module is interfaced, including a water flow meter 23, a pressure converter 20, a tank for cooling water 15 with a level gauge 25, which is interfaced with the second unistat 14, compressor 16, reducer 27 and connected by pipeline 24, through water flow meter 23 with nozzle 5, while video camera 19, air velocity and temperature sensor 28, fan 1, which is associated with frequency converter 29, and the first unistat 13, which is associated with the first heat exchanger 3/1 and the second heat exchanger 3/2, which leads, due to the complete automation of the process of maintaining the set parameters, to speed up the preparation of the test process, reduce the complexity of tests and increase their accuracy. The fact that the installation is cooled by the first unistat 13, and not by liquid nitrogen, makes it possible to abandon complex control equipment due to uneven evaporation of nitrogen droplets and guarantees accurate temperature maintenance and high flow quality.

The fact that a cyclone 8 with two fender grids 10 with heating elements 9 and a direct channel 2 is introduced into the installation, while the cyclone 8 is associated with a direct channel 2 and a return channel 12, leads to accelerated removal of snow and ice and an increase in the speed of preparation for carrying out next test. The fact that the installation provides for slopes on the direct channel 2 from fan 1 to cyclone 8 and on the return channel 12 from cyclone 8 to fan 1 leads to a natural drain of water and an increase in the speed of preparation for the next test.

The fact that the prechamber 4 and the working part 6 are connected into a unit made of transparent glass and optically coupled to the video camera 19 makes it possible to observe and record the process of snow formation in the nozzle 5 and the process of snow and ice accumulation on the sample 30 in real time and receive various types of icing.

The fact that a mechanical shaker 7 is introduced into the installation, coupled with a sample holder 26, makes it possible to bring the tests closer to the actual operating conditions of the coatings and increase their accuracy.

The fact that the heating element 22 is introduced into the installation, coupled with the nozzle 5, leads to the fact that the nozzle of the nozzle 5 during the preparation of water-air aerosol is not clogged with ice, increasing the reliability of the test and the speed of preparation for the next test. The fact that the nozzle 5 is installed with the possibility of changing its position makes it possible to obtain various types of icing.

Claims (7)

1. Installation of artificial freezing and icing with a closed circuit, containing a prechamber associated with the working part, in which a sample holder, a return channel and a nozzle are installed, characterized in that a personal computer and a controller are introduced into it, with which a chilled water preparation module is connected and accurate dosing, including a water flow meter, a pressure converter, a tank for cooling water with a level gauge, which is coupled with a second unitat, a compressor, a gearbox and is connected by a pipeline through a water flow meter with a nozzle, while a video camera, a speed and temperature sensor are also connected to a personal computer and a controller air, a fan that is coupled with a frequency converter, and the first unistat that is coupled with the first heat exchanger and the second heat exchanger. 2. Installation according to claim. 1, characterized in that it introduced a cyclone with two fender grids with heating elements and a direct channel, while the cyclone is associated with a direct channel and a return channel. 3. Installation according to claim 2, characterized in that slopes are provided for natural water drainage on the direct channel from the fan to the cyclone and on the return channel from the cyclone to the fan. 4. Installation according to claim 1, characterized in that the pre-chamber and the working part are connected into a node made of transparent glass and optically coupled to the video camera. 5. Installation according to claim. 1, characterized in that a mechanical shaker is introduced into it, coupled with a sample holder. 6. Installation according to claim. 1, characterized in that it introduced a heating element associated with the nozzle. 7. Installation according to claim. 1, characterized in that the nozzle is installed with the possibility of changing its position.

Images