RU2792466C1 - Independent cooling unit - Google Patents

Abstract

FIELD: construction in permafrost conditions.

SUBSTANCE: invention and can be used as a soil thermal stabilizer to protect against degradation of the frozen foundation of building objects, such as roads, residential and industrial buildings. Autonomous cooling device is made in the form of a ventilation channel, contains a suction pipe forming an inlet air channel, a thermosiphon forming an increased cooling zone in the ventilation channel, and a main exhaust pipe, a rotary assembly and a horn deflector, which together form an exhaust channel. The suction pipe of the inlet air channel has a radius bend and a height less than the height of the exhaust channel, while the diameter of the thermosyphon exceeds the diameter of the air channels. The horn deflector of the exhaust channel has an exhaust pipe of the horn deflector connected to the main exhaust pipe by means of a rotary assembly, connecting elements for placing the horn on the exhaust pipe of the deflector and a weather vane.

EFFECT: increased intensity of soil cooling using the force of wind and cold of the surrounding air and the possibility of programming an ice curtain to cut off the base of the object from the lens of thawed soil in the zone of degradation of permafrost soils.

3 cl, 4 dwg

Description

The invention relates to the field of construction in permafrost conditions and can be used as a soil thermal stabilizer to protect against degradation of the frozen base of building objects such as roads, residential and industrial buildings.

In permafrost areas, after the construction of a constructed object is completed, it often becomes necessary to take measures to preserve it. This is due to the fact that after the construction of the facility, the thermal balance of soils has changed, and the building area has not yet adapted to the new conditions. It is during the initial period of operation that the probability of deformation of roads and infrastructure facilities from the degradation of the frozen base increases many times over. Violation of the moss and vegetation cover, and as a result of the depth of seasonal permafrost thawing, leads to a sharp decrease in the bearing capacity of the base soils, and sometimes to the liquefaction of entire areas. This has a detrimental effect on the constructed roads, buildings and structures, their stability worsens, the deformability of the soil base increases, which can lead to the loss of stability of the foundation of buildings, or the destruction of entire sections of roads. These processes are especially dangerous in slope areas, where there is at least a slight slope. In permafrost areas, various types of heat stabilizers are used to prevent such phenomena.

Currently, soil thermal stabilizers are represented by several main types of seasonal cooling devices (SDA), of which the device claimed as an invention belongs to horizontal naturally operating tubular systems (HET). The proposed GET system is a flow heat transfer device that automatically operates in winter due to the pressure difference at different ends of the device and the positive temperature difference between the ground and the outside air. The advantages of GET include the fact that they do not require power sources, as they operate on wind power. The autonomy of work does not require constant maintenance. GET-type LCSs have a wide range of applications (roads, houses, free-standing structures, and so on). Also, the advantages of HET include high efficiency (coefficient of performance) and simplicity of design, they do not have complex mechanisms and components.

Known embankment on highly icy permafrost soils [1] containing a cooling system in the form of a cloth with channels located inside it. The panel with channels can be made in the form of a grid. Channel openings located along the edges of the web are connected to a transverse air intake tube. The cooling system is made in the form of a series of bays, consisting of spirally twisted panels or grids with channels and installed across the axis of the road. The cooling system can be made combined of at least two layers, of which the lower one consists of bays, and the upper one consists of panels with channels or tubes. The disadvantage of this solution for cooling the embankment, consisting of pipes of different diameters, is that the cooling system is placed in the lower part of the embankment, which is covered with snow in winter and the flow of cold air stops. Being in the body of the embankment, the pipes can become clogged with condensate and block the passage of cold air. In addition, many pipes of different diameters significantly complicate the cooling device and require prefabrication.

A device for active ventilation and lowering the temperature of direct suction is known, applicable to an embankment on permafrost [2, 3, 4] designed for active (forced) seasonal cooling of the soils of the base and body of the embankment in winter and contains a ventilation pipe, an aspiration fan, a hollow column, a driving device and a device for converting wind energy.

The disadvantages of the known device is that it has a complex design and large weight and size parameters. In addition, the device has moving parts, which in the northern latitudes are quickly covered with ice and jammed. Also, the disadvantages of the device include the complexity of the design of the ventilation duct, which will collect condensate and freeze inside, clogging the pipe.

Known low-fill design subgrade with a ventilation pipe in areas of permafrost [5, 6] which fits a hollow pipe with free ends, with a bend inside the base of the embankment, serving as a cooler.

The disadvantages of this solution include the fact that such a device cooler has a low coefficient of performance (COP), as the air stagnates inside. The ends of the pipe are located low and are not protected from drifting with snow, which leads to the cessation of the operation of the device.

Closest to the claimed invention (its prototype) is an automatic wind and exhaust ventilation pipe of the road base in the permafrost region [7], which uses the same principle of soil cooling by running cold air through the pipe, which is laid in the lower part of the embankment. The well-known technical solution has a Z - shaped pipe, the lower end of which is equipped with a check valve, is located on the other side of the embankment and is the inlet of outside cold air. The other end of the pipe is a hood that rises above the lower part and has a socket on a swivel base at the end. To keep the bell in the wind, a weather vane is attached above it. The device starts working when the wind blows at a speed of at least 5-7 m/sec. The wind, passing through the bell, bends around it and at the exit creates a thrust, which is transmitted along the entire length of the pipe and causes air to be sucked through the inlet. Under the force of thrust, the valve opens and air enters the pipe and exits the socket. Cold air passes through the pipe and transfers the cold to the surrounding soil, cooling it. Thus, the lower part of the embankment is cooled and protected from degradation (melting). However, the device has a low efficiency due to the fact that a constant strong wind is needed to generate enough thrust so that the cold outside air can pass from beginning to end. Since the cold air is heavy, it moves slowly through the pipe, and therefore brings less cold, and on days when the wind is weak or absent, the device practically does not work. Also, a disadvantage of the known device is that it has the same cross section (diameter) along its entire length, that is, the air passes at the same speed along the entire length, without expanding and without transferring all the cold to the pipe walls. In addition, the inlet is close to the ground, therefore, during a snowfall or a blizzard, it will immediately become clogged with snow, as a result of which it will stop working. Therefore, this device can only work in the absence of snow and will not be able to work all season. The non-return valve after wet snow or frost may freeze and not open, completely paralyzing the operation of the entire device. The device is installed at the base of the embankment and can only cool the body of the embankment, having an impact radius of no more than 1 meter, so they had to be installed frequently, which is not economically feasible. This solution was used in the construction of the Qinghai-Tibet railway and was not widely used. During the summer period, the pipe remains open and will suck in warm air, which will lead to thawing of the soil around, nullifying the previously frozen massif.

The objective of the claimed invention is to create a new autonomous cooling device of simple design for freezing (cooling) permafrost soils in their degradation (thawing) zones using wind power and cold ambient air.

The technical result of the claimed invention, in relation to the known GET systems, is an increase in the intensity of soil cooling and the possibility of programming an ice curtain to cut off the base of the object from the lens of thawed soil in the degradation zone of permafrost soils.

To do this, an autonomous cooling device, made in the form of a ventilation duct in accordance with the claimed technical solution, contains a suction pipe that forms an inlet air duct, a thermosiphon that forms an increased cooling zone in the ventilation duct, and the main exhaust pipe, a rotary assembly and a horn deflector in the aggregate, forming an exhaust channel, while the suction pipe of the inlet air channel has a radius bend and a height less than the height of the exhaust channel, while the diameter of the thermosyphon exceeds the diameter of the air channels, while the horn deflector of the exhaust channel has an exhaust pipe of the horn deflector connected to the main exhaust pipe by means of a rotary assembly , connecting elements for placing a horn on the exhaust pipe of the deflector and a weather vane.

Preferably, when the diameter of the thermosyphon exceeds the diameter of the air channels at least three times. In order to simplify the manufacture and transportation of the device, the self-contained cooling device may have a mounting assembly.

Such a design of an autonomous cooling device will allow, by providing a constant natural inflow of air (in the winter season) and a variable pressure in the ventilation duct, to increase the intensity of cooling of soils at the base of structures. At the same time, having a difference in the diameter of the thermosyphon in relation to the air channels of the device, it becomes possible to program the ice curtain to cut off the base of the object from the lens of the thawed soil in the zone of degradation of permafrost soils. At the same time, this design can be used for both bulk and buried foundations.

In FIG. 1 shows the principle of operation of the proposed autonomous cooling device;

In FIG. 2 shows an autonomous cooling device in accordance with the proposed technical solution.

In FIG. Figure 3 shows a scheme for laying an autonomous cooling device into the ground to restore the degraded permafrost stratum.

In FIG. Figure 4 shows a diagram of laying two autonomous cooling devices into the ground to restore the degraded strata of permafrost soil.

The principle of operation of the proposed SDA is to create a forced draft inside the entire device using a horn deflector to suck in cold air, which transfers cold to the ground through a thermosyphon and cools (freezes) it. The proposed device is designed to preserve (protect against degradation) the soil foundation of roads, residential and industrial buildings and structures built on permafrost soils.

In winter, cold air passing through the thermosyphon and the ventilation ducts of the HET restores the permafrost that has thawed over the summer at the base of the structures, as shown in Fig. 1. To do this, it is necessary to ensure a constant natural flow of air in the design of an autonomous cooling device.

A constant natural flow of air in the design of an autonomous cooling device is provided by creating traction. For this autonomous cooling device (Fig. 2) has an input 1 and exhaust 2 air channels. The inlet air channel 1 is made in the form of a suction pipe 3 protruding outside the base to a height less than the height of the exhaust channel, and has a radius bend 4, which prevents clogging of the inlet channel with snow. The exhaust air channel 2 is made in the form of a main exhaust pipe 5 with a rotary assembly 6 (for example, a bearing), through which it is connected to the horn deflector 7, namely the exhaust pipe 8 of the deflector. The horn 9 of the deflector in the presence of wind takes air masses (as shown in Fig. 1) from the environment, which at the entrance to the horn are compressed and increase speed, creating thrust at the exit. Since an exhaust channel 2 is located at the outlet of the horn 9, a draft is also formed in it, which drives the air in the ventilation channel, from the deflector 7 to the suction pipe 3, since a low pressure area has formed in the exhaust air channel 2 and thermosiphon 10. To place the horn 9 on the exhaust pipe 8 of the deflector, connecting elements 11 (for example, jumpers) are provided, and a weather vane 12 is provided to capture the air mass deflector with the horn 9.

At the same time, an increase in the intensity of soil cooling at the base of structures is achieved by changing the pressure in the ventilation duct with a constant natural influx of air masses. To do this, an autonomous cooling device contains a thermosyphon 10, where cold air entering a wider channel expands, forming a zone of increased cooling in the ventilation channel, while the diameter of the thermosyphon 10 exceeds the diameter of air channels 1 and 2 at least three times.

This solution allows you to change the flow rate of the medium (cold outside air) through the device and increase its efficiency. Also, the thermosiphon 10 has improved properties for the release of cold into the surrounding soil massif. Having a difference in the diameter of the thermosiphon 10 in relation to the air channels 1 and 2, the device allows you to program the creation of an ice curtain to cut off the base of the object from the lens of thawed soil in the zone of permafrost degradation. For example, with a channel diameter of 200 mm and a thermosyphon diameter of 600 mm, the “coverage” zone will be 2.4 meters, which will allow calculating the amount of HET for the required area, and accordingly programming the ice curtain to cut off the base of the object from the lens of thawed soil in the permafrost degradation zone .

The operation of the autonomous cooling device is illustrated by the following example (as shown in Figs. 3 and 4).

To begin with, the drilling method determines the depth of the upper boundary of permafrost soil (VGMG) from the surface of the active layer H ₁ . Then HCMG in the zone of H ₄ degradation. Calculate the power (thickness) of the degradation zone H ₄ - H ₁ = H ₂ .

Based on the diameter of the thermosyphon (D _t ) determine the zone of its action, which is equal to three diameters of the thermosiphon - D _s \u003d 3D _t (for example, with a thermosyphon diameter of 600 mm, its zone of action will be 2.4 m). Taking into account the area of action of the thermosyphon, the depth of its laying H ₃ is determined (Fig. 3). It should be selected in such a way that the thermosyphon coverage area covers as much of the degradation zone as possible in order to create a permafrost curtain under the structure. For each case, the thermosiphon tab is calculated and determined individually.

In cases where the zone of one thermosiphon does not cover the degradation zone, two tiers of thermosiphons should be installed with an offset at the distance of their action. At the same time, the area of action of thermosiphons should overlap each other (Fig. 4).

When installing two rows of autonomous cooling devices, the laying starts from the lower tier, after it is backfilled, a trench is developed for the second thermosyphon and laid according to the previously planned planned and elevation marks. After laying the thermosyphon 10 in the trench, the parts of the independent cooling device are assembled by means of the mounting unit 13. In this case, the position of the suction pipe 3 must be less than the height of the exhaust duct 2 to create an air inflow. At the same time, the radius bend 4 of the suction pipe 3 prevents clogging of the inlet air channel 1 with snow and the exit from the operation of the device, ensuring its operation in the most difficult weather conditions.

When a wind occurs, the weather vane 12 turns the horn 9 of the deflector 7, the exhaust pipe 8 of which is installed on the rotary assembly 6 (bearing support) against the wind. Getting into the horn part of the deflector 7 and passing through it, the air is compressed and simultaneously accelerates its flow (speed), creating draft along the entire ventilation duct from the suction pipe 3 to the exhaust pipe of the deflector 8. Since the horn part of the deflector 7 is fixed to the exhaust deflector pipe 8 (through the connecting elements 11), the outgoing air creates a low pressure area at the outlet, forming a low pressure area at the beginning of the device. Having a difference in pressure at the ends of the device, the outside air rushes into the suction pipe 3 and enters the thermosiphon 10, the diameter of which is wider than the inlet air channel 1. In the thermosyphon 10, the cold outside air slows down and expands, giving some of the cold to the metal walls, through them soil, cooling (freezing) it. Further, the air continues its movement to the outlet and leaves the device through the exhaust air channel 2. This continues as long as the wind blows. After the end of the winter season, the inlet is closed so that warm air does not enter the thermosyphon and does not defrost the surrounding soil massif.

List of used literature:

1. Patent RU 2487213 C1 (IPC: E02D 17/18) for the invention "Embankment on heavily icy permafrost soils"; application: 2011143346/03 dated 10/26/2011; patent holder: FGBOU VPO "TSTU" (RU);

2. Patent CN 108118571 A (IPC: E01C 3/06) for the invention "Direct suction active ventilation and temperature reduction device applicable to permafrost embankment"; application CN 201810075781 A dated 01/26/2018; patentee: UNIV SICHUAN AGRICULTURAL (CN);

3. Patent CN 207987654 U (IPC: E01C 3/06) for a utility model "Multi-support piston-type active ventilation cooling device suitable for permafrost subgrade"; application CN 201820142264 U dated 01/26/2018; patentee: UNIV SICHUAN AGRICULTURAL (CN);

4. Patent CN 207987652 U (IPC: E01C 3/06) for utility model "Initial connecting rod type ventilating cooling device suitable for roadbed with frozen ground for many years"; application CN 201820134152 U dated 01/26/2018; patentee: UNIV SICHUAN AGRICULTURAL (CN);

5. Patent CN 110777592 A (IPC: E01C 3/06) for the invention "Low-fill construction of the subgrade of the ventilation pipe in the permafrost region of the plateau"; application CN 201911075741 A dated 11/06/2019; patent holder: CHINA RAILWAY FIRST SURVEY & DESIGN INST GROUP LTD (CN);

6. Patent CN 211171466 U (IPC: E01C 3/06) for the utility model "Plateau permafrost region low embankment ventilation pipe subgrade"; application CN 201921900291 U dated 11/06/2019; patent holder: CHINA RAILWAY FIRST SURVEY & DESIGN INST GROUP LTD (CN);

7. Patent CN 215164243 U (IPC: E01C 3/00, E01C 3/06) for a utility model "Automatic windproof and exhaust ventilation pipe of the road base in the permafrost area"; application CN 202120606691 U dated 03/25/2021; the patentee is Lanzhou Technical University (CN).

Claims (3)

1. Autonomous cooling device made in the form of a ventilation duct, characterized in that it contains a suction pipe that forms an inlet air duct, a thermosiphon that forms an increased cooling zone in the ventilation duct, and a main exhaust pipe, a rotary assembly and a horn deflector, which together form an exhaust channel, while the suction pipe of the inlet air channel has a radius bend and a height less than the height of the exhaust channel, while the diameter of the thermosiphon exceeds the diameter of the air channels, while the horn deflector of the exhaust channel has an exhaust pipe of the horn deflector connected to the main exhaust pipe by means of a rotary assembly, connecting elements for placing a horn on the exhaust pipe of the deflector and a weather vane. 2. Autonomous cooling device according to claim 1, characterized in that the diameter of the thermosiphon exceeds the diameter of the air channels by at least three times. 3. Autonomous cooling device according to claim 1, characterized in that the exhaust channel is equipped with a mounting assembly.

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