RU2802350C1 - Climatic chamber for testing large products - Google Patents

Abstract

FIELD: testing equipment.

SUBSTANCE: invention relates to mobile climatic chambers with cryogenic liquid vapour cooling for temperature testing of large-sized products and testing their resistance to external loads at low temperatures. The climatic chamber for testing large-sized products includes a heat-insulated chamber with a temperature sensor inside and a cooling system with a cryogenic liquid tank. The walls and ceiling of the chamber are made of collapsible thermally insulated panels connected to each other by external reusable tightening clamps. The design of the climate chamber contains movable heat-insulated partitions forming separate sections inside the climate chamber, while one of the extreme sections is the main one, the working volume of which is connected by an exhaust heat-insulated air duct to the outside atmosphere. The heat-insulated exhaust air duct contains a variable frequency drive fan. The thermal insulation of the floor area of the climatic chamber not occupied by the product under test is made by separate thermally insulated mats. Each section of the climatic chamber contains a removable frame with a cryogenic liquid sprayer hydraulically connected to the cryogenic liquid container, a circulation fan and an electric heater. A non-return valve is installed in the thermally insulated ceiling panel of each section. The temperature sensor is installed in the main section of the chamber. The chamber equipment includes a process controller that connects the temperature sensor with the frequency drive of the duct exhaust fan. One of the ceiling panels is made with a heat-insulated hatch for the rod of the device for external force action on the tested product, and also contains movable supports with a low thermal conductivity coefficient and a height greater than the thickness of the heat-insulating mats of the climate chamber. The lower part of the supports is located on the floor of the climatic chamber, and the tested product is placed on top of the supports.

EFFECT: increased energy efficiency and versatility of the climate chamber.

1 cl, 3 dwg

Description

The invention relates to installations for climatic testing of large-sized products, as well as for testing their resistance to external force effects at low temperatures, for example, reinforced concrete and metal arches of hangars, bridge spans, building reinforced concrete floor slabs, hull units in the construction of ice-class ships, as well as various equipment, including rolling stock, designed to operate at low temperatures, where the ambient air temperature can drop to -60°C in the winter months.

The development of the Far North of Russia includes industrial and housing construction, the construction of port facilities, the laying of railways and pipelines, automobile and railway bridges, the creation of an icebreaker fleet in permafrost and low temperatures. For experimental verification of the strength of building structures and the performance of various equipment at low ambient temperatures, climatic chambers for various purposes are being created.

Known climatic installation for testing products according to patent No. 399839 authors M.G. Dubinsky and others, cl. G05d 23/30, publication date of the description 25.01.1974. air ducts of climatic chambers. The disadvantage of this solution is the very use of an air turborefrigeration machine, which has a high cooling capacity, but is the most energy inefficient in terms of electricity costs per unit of produced cold. Such a turbo-refrigeration machine is installed permanently on the foundation, due to its large mass. In addition, chillers of this type have a high initial cost and require highly qualified service personnel. It is known that the tests themselves in climatic chambers are carried out periodically, while most of the time preparation for testing is carried out - delivery and loading of the test object, installation and fastening of sensors at the object. Then, several hours of testing with the refrigeration system running, after which, with the refrigeration system turned off, the above operations are carried out in reverse order and the test object is shipped to the customer. At this time, the expensive refrigeration system is simply idle, which significantly increases the payback time for the equipment of such a climate chamber.

An alternative to climatic chambers with vapor-compression refrigeration systems are climatic chambers with cooling of test objects with cryogenic liquid vapors. The refrigeration supply systems of such chambers are much simpler in design and cheaper in initial cost. Chambers with such refrigeration systems do not require large amounts of electricity, and this often becomes an obstacle in the development of climatic chambers with vapor-compression refrigeration units, especially when it comes to chambers for low-temperature testing of large building products, where the electric power of the refrigeration system compressors can reach 1 MW .

Testing samples with an open flow of evaporated cryogenic liquid is often used in cryogenic engineering. So known patent 2226657 RU author Demikhov E.I. et al., patent US 6003321 AF25B 19/00, 1999, in which the test sample placed inside the cryostat (a prototype of a climatic low-temperature chamber) is cooled by cryogenic liquid vapor from a Dewar vessel. Such devices confirm the effectiveness and simplicity of what kind of cooling, but the test samples themselves are placed in small cryostats. These cryostats with a cryogenic liquid vapor cooling system are mobile, they can be transported from one laboratory to another, but are intended only for laboratory research of small samples.

As a prototype for the proposed technical solution, the well-known mobile climatic chamber of TsAGI, www.files.tsagi.ru, (RF patent for utility model No. 191353), which is an inflatable hangar for testing samples of large-sized equipment (helicopters, all-terrain vehicles, etc.) .) for operation in the Arctic climate, where it is proposed to use a nitrogen-air machineless cooler as a refrigeration system, according to patent 2715944 of the Russian Federation, MCP F28C 3/06, the owner of the patent is FSUE TsAGI, application 2019123314 dated 07/24/2019, published 03/04/2020. This generator ensures the evaporation of finely dispersed liquid nitrogen in an ascending vortex flow of air entering the inflatable housing of the climatic chamber (hangar) under excess pressure. The applicant indicates the time to reach the air temperature in the chamber -75°C for 1.5 hours, while the flow rate of liquid nitrogen is 0.5-5.0 kg/s.

Along with positive effects, such as the rapid deployment of the climate chamber at the customer's site and its low cost, it has a number of disadvantages associated specifically with the design of the climate chamber itself.

Inflatable large-sized hangars are currently used for indoor ice fields, tennis courts, temporary structures of the Ministry of Emergency Situations to accommodate victims of man-made disasters or for temporary accommodation of military personnel at the site of exercises or hostilities and have proven themselves well at positive temperatures and slightly negative ambient temperatures . The use of such inflatable hangars as the body of a low-temperature chamber is not energetically efficient, since the inflatable wall of such a hangar has poor thermal insulation properties, and the hangar itself has low rigidity when exposed to external loads (snow, freezing rain and strong wind). Therefore, for large hangars, a stationary metal or composite frame is required that holds the inflatable wall of the hangar. At the same time, the greater the width of the hangar, the higher and stronger (snow load on the roof) the supporting frame should be. This leads to additional work on the installation of this frame and its dismantling after testing with the involvement of lifting equipment and to an increase in the cost of installing a climate chamber,

The biggest disadvantage of the design of the prototype mobile climatic chamber is the high operating costs for low-temperature testing, especially of large-sized heavy structures, due to insufficient thermal insulation of the walls and the lack of thermal insulation on the floor of the chamber, which requires an extremely high consumption of liquid nitrogen. The maximum capacity of the cooler declared by the authors is 5.0 kg/s, which means that during the declared time of a one-time test of 1.5 hours, 27 tons of liquid nitrogen will be consumed, which will be removed from the working volume of the climatic chamber into the surrounding atmosphere after gasification and cooling with cold gas of the test object. This will require the cost of ensuring the safety of personnel serving the chamber (installation of alarm sensors for lack of oxygen, mandatory oxygen masks for personnel). In this case, during the time indicated by the authors, only the outer surface of the tested products will cool to the specified temperature (-75°C) at such a flow rate of liquid nitrogen. For climatic tests of multi-ton large-sized building structures, their complete freezing to the required temperature is required. These low-temperature tests, depending on the mass and design of the product, can last up to a day, until the product under study is cooled throughout the mass to the required temperature. And this will require hundreds of tons of liquid nitrogen, which is practically unprofitable.

The disadvantage of the prototype is also the inability to test building structures in this chamber for resistance to destruction under various force effects on a structure frozen to temperatures of -60 - 70 ° C, which is now a mandatory requirement when designing objects for the conditions of the Far North.

Another disadvantage of the prototype is also the design complexity of the nitrogen-air cooler, where, in addition to the container with liquid nitrogen, a source of compressed dry air is a necessary element (this is usually an air compressor station and an air drying system before it is fed into the cooler).

Also, the disadvantage of the prototype mobile chamber is the constancy of its working volume, aimed at testing only large-sized products. If a product of a smaller size is tested in such a chamber, then the external heat gains through its walls and the non-heat-insulated floor will remain the same as when testing large-sized products, so the nitrogen consumption will be slightly less, which makes testing small-sized products in such a chamber even more unprofitable.

The technical result of the present invention is to increase the energy efficiency and versatility of using the climatic chamber (the possibility of testing products with different sizes and external power loads).

This goal is achieved by the fact that in a climatic chamber for testing large-sized products, including a heat-insulated chamber with a temperature sensor inside and a cooling system with a cryogenic liquid capacity, the walls and ceiling of the chamber are made collapsible from heat-insulated panels interconnected by external reusable tightening clamps, the design climate chamber contains movable heat-insulated partitions forming separate sections inside the climate chamber, while one of the extreme sections is the main one, the working volume of which is connected by an exhaust heat-insulated duct with the outside atmosphere, the heat-insulated exhaust duct contains a fan with a frequency drive, thermal insulation of the floor area of the climate chamber, not occupied by the product under test, made of separate heat-insulated mats, each section of the climatic chamber contains a removable frame with a spray of cryogenic liquid (for example, liquid nitrogen), hydraulically connected to the capacity of the cryogenic liquid, a circulation fan and an electric heater, a check valve, a sensor are installed in the heat-insulated ceiling panel of each section temperature sensor is installed in the main section of the chamber, as part of the chamber equipment there is a control controller that connects the temperature sensor with the frequency drive of the air duct exhaust fan, one of the ceiling panels is made with a heat-insulated hatch for the rod of the device for external force impact on the tested product, and also contains movable supports with low coefficient of thermal conductivity, and a height greater than the thickness of the heat-insulating mats of the climatic chamber, while the lower part of the supports is located on the floor of the climatic chamber, and the tested product is placed on top of the supports.

A heat-insulated panel and a heat-insulated partition can be made in the form of a three-layer structure, with a thickness of 40 to 200 mm: thin-walled metal sheets (0.5 mm), galvanized and painted, are located on both sides, with filling the space between them with rigid polyurethane foam, which acts as a high-quality heat-insulating material with thermal conductivity coefficient k = 0.022 W/m2K. Between themselves, the panels are fastened by means of a tenon-groove connection.

As heat-insulating mats, you can use mats in accordance with GOST 21880-94 "Heat-insulating pierced mats made of mineral wool" with lining material made of fabric, non-woven canvas, or other similar materials. These flexible mats with a thickness of 40 to 120 mm, produced in various lengths, widths, and configurations at the request of the customer, provide high thermal insulation properties at temperatures from -180°C to +700°C, namely, a thermal conductivity of not more than 0.048 W/(m⋅ TO).

Supports can be made of solid wood.

We will consider the practical implementation of the proposed technical solution for a climatic chamber for testing large-sized products with cryogenic liquid vapor cooling using the following example.

Figure 1 schematically shows a climatic chamber for testing large-sized products with cooling by vapors of a cryogenic liquid (a-side view and b-top view), where the numbers indicate:

1 - ceiling heat-insulated panels

2 - side heat-insulated panels

3 - reusable tightening clamp

4 - movable heat-insulated partitions

5 - heat-insulated exhaust duct

6 - exhaust fan

7 - frequency drive of the exhaust fan

8 - heat-insulating mats

9 - cryogenic liquid sprayer

10 - container with cryogenic liquid 11 - circulation fan

12 - electric heater

13 - check valve

14 - temperature sensor

15 - control controller

16 - hatch for the rod of the device of external force

17 - rod of the external force action device

18 - movable supports

Figure 2 and figure 3 shows the layout drawings of the proposed climate chamber for testing large products with cooling vapor cryogenic liquid. An overhead crane with a movable trolley and a rod of a force action device are not shown in the layout drawings.

The body of the climatic chamber for testing large-sized products consists of heat-insulated ceiling panels 1 and side heat-insulated panels 2, connected to each other by reusable tightening clamps 3. Moveable heat-insulated partitions 4 are installed inside the climatic chamber, connected by reusable tightening clamps 3 with the side heat-insulated panels of the chamber body, forming separate sections insulated from each other. One of the extreme sections is the main one, the working volume of which is connected with the outside atmosphere through a heat-insulated exhaust air duct 5 and an exhaust fan 6 with a frequency drive 7. The frame is equipped with a cryogenic liquid sprayer 9, hydraulically connected to a container with cryogenic liquid 10, a circulation fan and an electric heater 12. A check valve 13 is installed in the heat-insulated ceiling panel 1 of each section. A temperature sensor 14 is installed in the main section and is electrically connected through the control controller 15 with the drive 7 of the exhaust fan 6. The hatch 16 in the ceiling panel is designed to insert the rod of the external force device 17 into the climatic chamber. The test object is installed on movable supports 18.

The proposed climatic chamber for testing large products works as follows.

In the test shop with a mobile overhead crane having a device for creating a multi-ton force on the test sample, between the supports of the overhead crane on the concrete floor base, a climate chamber body is installed, consisting of heat-insulated ceiling panels 1, laid on top of the side heat-insulated panels previously installed on the concrete floor base 2, fastened together by reusable tightening clamps 3 and movable heat-insulated partitions 4, fixed by reusable tightening clamps 3 to the inner surface of the side heat-insulated panels 2. Ceiling heat-insulated panels 1 are fastened with reusable tightening clips 3 to the outer surface of the side heat-insulated panels 2, thus creating separate heat-insulated sections inside the climate chamber.

The size of the created working section of the climatic chamber is determined by the dimensions of the products tested at this enterprise, while some of the movable heat-insulated partitions 4 may not be installed at the stage of assembling the climatic chamber. To load the test object into the working section of the climatic chamber, the ceiling panels 1 of this section involved in the tests are removed, and the sample is loaded into the section with an overhead crane. After that, the heat-insulated ceiling panels 1 are put in place and fastened with reusable tightening clamps 3 to the side heat-insulated panels 2. After that, the area of the floor of the working section of the chamber not occupied by the tested sample is thermally insulated by laying heat-insulating mats 8 on it. In the working section involved in the tests removable frames are installed, on each of which a cryogenic liquid sprayer 9, a circulation fan 11 and an electric heater 12 are fixed. The electric heater 12 is intended mainly for thermal testing of large-sized products (+40 - +60 ° C). Cryogenic liquid atomizers 9 are hydraulically connected to a container with cryogenic liquid 10. In this case, nitrogen is chosen as the cryogenic liquid, as it is the cheapest and has a boiling point of -195.8°. Through the hatch 16 in the ceiling panel installed in the heat-insulated panel, the rod of the external force device 17 is inserted into the working section.

Since the sections of the climatic chamber are structurally leaky, due to the use of reusable tightening clamps 3 during its assembly (instead of liquid sealants and sealants in stationary chambers), during testing it is always necessary to maintain the gas pressure in the working section of the chamber, lower than the air pressure outside the climatic chamber. To do this, before supplying liquid nitrogen from the tank with cryogenic liquid 10 to the atomizers of the cryogenic liquid 9, the exhaust fan 6 is turned on, creating a small vacuum in the working section of the climatic chamber, after which liquid nitrogen is supplied at the calculated flow rate to the atomizers 9. Circulation fans 11 circulate cold nitrogen vapor inside the working section of the climate chamber. Liquid nitrogen vapor cools the test sample and displaces the remaining air from the volume of the working section of the climate chamber. The controller 15 on the signal of the gas temperature sensor 14 in the working section controls the frequency drive 7 of the exhaust fan 6, maintaining the set temperature by increasing the performance of the exhaust fan 6 when the temperature in the working section drops below the set one. With an increase in the performance of the exhaust fan 6 in the working section, the pressure decreases, the check valves 13 open and warm air from the outside enters the working section of the chamber, is mixed by the circulation fan 11, and the gas temperature inside the section rises. When the gas is heated to a predetermined temperature (-60°C), the controller 15 reduces the performance of the exhaust fan 6 to the minimum required to close the check valves and the access of warm air to the working section is stopped.

After cooling the test object itself to a predetermined temperature, for example -60 ° C and holding it for a predetermined time at this temperature, a force specified by the test conditions is applied to the rod of the external force device 17 and acts on the sample.

After the end of the tests, the supply of liquid nitrogen from the tank with cryogenic liquid 10 to the atomizers of cryogenic liquid 9 is stopped. After that, the exhaust fan 7 is forcibly turned on at full capacity, pumping out nitrogen vapor through a heat-insulated exhaust duct into the atmosphere outside the test shop. The rod of the external force device 17 is also removed from the chamber. When a pressure difference occurs between the working section of the climatic chamber and the atmosphere surrounding the climatic chamber, check valves 13 open in the heat-insulated ceiling panels 1 and warm air from the atmosphere surrounding the climatic chamber begins to enter the working section, displacing nitrogen vapor and at the same time warming the test object. After the temperature in the working section of the climatic chamber is available for personnel to stay there, the reusable tightening clamps 3 are unfastened, releasing the heat-insulated ceiling panels 1. Then these panels are removed or simply laid on the ceiling panels that are not participating in the tests of the sections, after which they are removed with a crane from the working section, the tested sample. If such tests are no longer planned at this facility, the camera and equipment are disassembled and transported by road to the storage site for this equipment or, if there is an order, to another manufacturer of large products.

The technical result when using the proposed climatic chamber for testing large-sized products with cryogenic liquid vapor cooling is achieved due to the fact that, unlike currently existing similar devices, it has the following positive properties.

Increasing the energy efficiency and versatility of using the climatic chamber due to its design is achieved by the following technical solutions:

- the execution of the walls and ceiling of the climate chamber housing from collapsible heat-insulated panels interconnected by external reusable tightening clamps, as well as the thermal insulation of the floor area of the climate chamber not occupied by the tested product, with separate heat-insulated mats, allows you to repeatedly disassemble and assemble the chamber housing, transport it to disassembled to a new test site and install the climatic chamber on a flat concrete floor. Given that the duration of testing products for strength and resistance to power loads at low temperatures is a day or two, thermal insulation of the floor with separate mats reduces heat gain from the floor into the chamber and eliminates freezing of the floor base and its swelling during the tests. This makes it possible to do without installing an expensive soil heating system under a concrete floor with an energy consumption of up to 40 W / m, which is mandatory for stationary refrigerators operating for a long time at such temperatures (-60 - -70 °);

- the introduction of movable thermally insulated partitions into the design of the climatic chamber, which form separate sections inside the climatic chamber, increases the versatility of the climatic chamber, allowing you to create sections with the dimensions of the working area that are optimal for a particular test product, which reduces operating costs (mainly the consumption of cryogenic liquid) during testing. In addition, this design of the chamber makes it possible, along with low-temperature tests in one section, to carry out high-temperature (+40 - +50°C) tests in another section of the climatic chamber;

- the implementation in one of the ceiling panels of the hatch for the rod of the device of external force impact allows testing the stability of building structures under various force effects at low temperatures. Since all ceiling panels are interchangeable, a skylight ceiling panel can be installed in place of any ceiling panel, based on the required location of the force applied to the test object.

- the introduction of movable supports with a low coefficient of thermal conductivity and a height less than the thickness of the thermal insulation mats into the design of the chamber makes it possible to almost completely insulate the floor of the climatic chamber during testing, which reduces the heat influx from the floor and leads to a decrease in nitrogen consumption per test cycle, which affects the energy efficiency of the climatic chamber cameras.

In addition, the invention makes it possible to achieve a reduction in the cost of operating the climatic chamber during testing by reducing the consumption of cryogenic liquid and energy consumption, as well as to increase the operational safety of maintenance personnel in the testing area.

Reducing the cost of operating the proposed climatic chamber during testing by reducing the flow of cryogenic liquid and energy consumption is achieved by the following technical solutions:

- an exhaust fan with a frequency drive makes it possible to ensure the heating of the chamber after the end of the chamber tests due to the entry of warm air from the ambient atmosphere through the check valve into the chamber, which reduces the cost of electricity heating the gas mixture (air with vapors of the cryogenic liquid) after the completion of the tests;

Increasing the industrial safety of maintenance personnel in the testing area is achieved by the following technical solution:

- a control controller that interacts with the frequency drive of the exhaust fan and is electrically connected to a temperature sensor installed in the main section of the climate chamber, which allows, by adjusting the performance of the exhaust fan, to maintain the vapor pressure of the cryogenic liquid inside the climate chamber below the pressure of the environment surrounding the chamber, which prevents these vapors from entering the chamber into the atmosphere around the chamber.

Thus, the use of the proposed invention makes it possible to test large and heavy building structures, large-sized products for various purposes at their production sites, after which the chamber can be disassembled and transported to another manufacturer of similar products. For example, to transport such a 20 m × 5 m × 6 m climatic chamber with test equipment to a new test site by road, two standard trucks with a body volume of 82 m ³ will be required).

This chamber can be used in different regions for both standard climatic tests of heavy and large equipment in the "heat-cold" modes, and tests of large-sized products for their resistance to external forces at low temperatures.

Claims (1)

Climatic chamber for testing large-sized products, including a heat-insulated chamber with a temperature sensor inside and a cooling system with a cryogenic liquid capacity, characterized in that the walls and ceiling of the climatic chamber are made collapsible from heat-insulated panels interconnected by external reusable tightening clamps, the design of the climatic chamber contains movable heat-insulated partitions forming separate sections inside the climatic chamber, while one of the extreme sections is the main one, the working volume of which is connected by an exhaust heat-insulated duct to the outside atmosphere, the heat-insulated exhaust duct contains a fan with a frequency drive, thermal insulation of the floor area of the climate chamber not occupied by the tested made of separate heat-insulated mats, each section of the climate chamber contains a removable frame with a cryogenic liquid sprayer hydraulically connected to the cryogenic liquid container, a circulation fan and an electric heater, a check valve is installed in the heat-insulated ceiling panel of each section, a temperature sensor is installed in the main section of the chamber, in the chamber equipment includes a control controller that connects the temperature sensor with the frequency drive of the air duct exhaust fan, one of the ceiling panels is made with a heat-insulated hatch for the rod of the device for external force action on the tested product, and also contains movable supports with a low thermal conductivity coefficient, and a height greater than the thickness of the heat-insulating mats of the climatic chamber, while the lower part of the supports is located on the floor of the climatic chamber, and the tested product is placed on top of the supports.

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