RU172000U1 - Device for freezing soils on the side sections of building structures - Google Patents

Abstract

The utility model relates to the field of construction of engineering structures in the permafrost zone. A device is known for freezing side sections of building structures containing a hollow tank with a cavity of uniform height and closed at both ends, while the hollow tank has two parts in length: a heat exchanger located on top and adjacent to it bottom evaporator, and the heat exchanger borders on the outside air, and the evaporator is located in the ground. The disadvantage of the system is that the vertical surface itself is excluded from cooling, which reduces overall efficiency. A novel feature of the proposed utility model is that the heat exchanger is adjacent to the vertical surface of the side sections, and the cavity in cross section is divided in half by a solid partition located parallel to the vertical surface and having gaps in the upper and lower ends of the cavity, while the gap area is equal to half the cross-sectional area of the cavity, and the upper sleep gap female valve, providing opening or closing of the upper gap. In addition, the partition along the heat exchanger can be provided with thermal insulation. In addition, the device along the length of the vertical surface can be made in the form of a continuous wall. The technical result is to increase the cooling efficiency.

Description

The utility model relates to the construction of engineering structures in the permafrost zone.

A device is known for freezing soils on the lateral sections of building structures (Tsernant A.A., Passek V.V., Pereselenkov G.S., Pozin V.A., Verbukh N.F. Features of subgrade construction, small artificial structures and bridges in climatic and permafrost-soil conditions of Central Yakutia (Collection of "Construction of Railways and Highways in Permafrost Areas", Proceedings of the Central Scientific Research Institute of Automotive Engineering, issue 242, pp. 44-50). The device (Fig. 1 Appendices) is a vertical wall constructed of gabions. In regions where there is no strong snow transfer, the vertical surface is exposed to snow. Therefore, during the winter period of the structure, cold enters through the vertical surface, and during the summer period it is warm. But since the average annual temperature is negative, a gradual freezing of the massif occurs. The advantage of this device is simplicity. Two flaw. Firstly, there is an outflow of cold reserves accumulated in winter and in summer. Secondly, due to the thawing in summer of a part of the massif from the side of the vertical surface, it is required to construct a rather expensive wall that would keep the massif from destruction.

A device is known for freezing side sections of building structures, comprising a hollow container with a cavity having a uniform height cavity closed at both ends, while the hollow container has two parts in length: a heat exchanger located on top and an evaporator adjacent to it from below, and the heat exchanger is adjacent to the outside air, and the evaporator is located in the ground (Passek V.V., Baev M.A., Nabokov A.V., Palavoshev I.N., Babukh A.P., Bai V.F. Combination of application of thermal supports and thermal insulation when erecting buildings on the eternal permafrost. Scientific but-technical journal "Vestnik TyumGASU", 2015, No. 4, pp. 43-46).

Soil freezing in the area of a vertical surface is carried out using automatic cooling units in combination with thermal insulation of the surface. The cooling circuit is shown in Fig. 2 Applications (three options). In this scheme, soil cooling is carried out only by cooling units. The vertical surface is used only to preserve the cold. Due to the fact that the soil at the vertical surface is frozen all year round, the thermal insulation device does not require powerful fastening.

The advantage of this technical solution is the reliability of the cooling system. The disadvantage of the system is that the vertical surface itself is excluded from cooling, which reduces overall efficiency.

The goal of creating a new technical solution is to increase the cooling efficiency.

The goal is achieved by combining in one device the functions of thermal insulation in the summer and cooling in the winter.

For this, a device for freezing soils on the lateral sections of building structures contains a hollow tank with a cavity that is uniformly closed at both ends, and the hollow tank has two parts in length: a heat exchanger located on top and an evaporator adjacent to it from the bottom, and the heat exchanger borders on the outside air and the evaporator is located in the ground. The heat exchanger is adjacent to the vertical surface of the side sections, and the cavity in cross section is divided in half by a solid partition located parallel to the vertical surface and having gaps in the upper and lower ends of the cavity, while the gap area is equal to half the cross-sectional area of the cavity, and the upper gap is equipped with a valve, providing opening or closing of the upper gap. In addition, the partition along the heat exchanger can be provided with thermal insulation. In addition, the device along the length of the vertical surface can be made in the form of a continuous wall.

The essence of the utility model is illustrated by drawings, where

in FIG. 1 shows a device for freezing soils on the lateral sections of building structures (section BB in Fig. 2);

in FIG. 2 shows a device for freezing soils on the side sections of building structures (section AA in FIG. 1);

in FIG. 3 shows a heat exchanger in winter in section BB in FIG. 2;

in FIG. 4 shows a summer heat exchanger in section BB in FIG. 2.

For an additional explanation of the subject matter, an Appendix to the description has been formed.

There are a significant number of different permafrost building structures that have side sections 1 with vertical surfaces 2, which are necessary or economically feasible to maintain in the frozen state during operation both in winter and in summer. These sections are scattered from the ground or constructed from other materials and located on an array of natural soil 3. An example is bulk sites in residential areas, dams, ice-soil barriers, moorings, zones of retaining walls, bridge abutments, etc.

The proposed device for freezing soils on the side sections of building structures contains a hollow tank 4 with a cavity having a uniform height closed at both ends 5. The tank has two parts in height: a heat exchanger 6 located on top and an evaporator 7 adjacent to the bottom 7. The heat exchanger 6 is adjacent to the vertical surface 2 The evaporator 7 can be located horizontally, vertically and obliquely.

The cavity 5 in cross section is divided in half by a solid partition 8, which is parallel to the vertical surface within the heat exchanger 2. The partition 8 is provided with heat insulation 9 along the heat exchanger 6. Heat insulation 10 is adjacent to the side sections 1 of the building structures and to the side parts of the hollow tank 4. In the upper and the lower ends of the partition 8 has gaps 11 and 12, respectively. The area of each gap is equal to half the cross-sectional area of the cavity. The upper gap is equipped with a valve 13, providing the opening or closing of the upper gap. In FIG. 1 shows an open valve 13, a closed valve in position 14.

To clarify the essence of the following notation:

- position 15 - direction of convective heat transfer;

- position 16 is the line along which it is possible to make the wall of thermal insulation 10;

- position 17 - a cavity that heats up in the warm season;

- position 18 is the cavity in which cold air remains in the summer.

A device for freezing soils on the side sections of building structures works as follows. At the beginning of the cold season, the upper gap 11 opens and the valve acquires position 13.

, где α_1з - коэффициент теплоотдачи с поверхности (ккал/(м²⋅час⋅град)). По мере того как охлаждается стенка, начинает охлаждаться воздух полости 5, контактирующей со стенкой. Формируется тепловой поток q_2з при термическом сопротивлении

. Поскольку холодный воздух тяжелее теплого, он начинает перемещаться вниз по направлению 15. По мере его перемещения формируются тепловые потоки q_3з за счет градиента температур вертикальной поверхности грунта t_пз и воздуха в полости 5. Этот теплообмен имеет место как в пределах теплообменника, так и испарителя,

. Таким образом, общие потери тепла (т.е. охлаждение грунта) в зимний период за время τ_зимн можно представить приближенно следующим образом:Due to the fact that the temperature t _{wintry of the} outdoor air in the cold period becomes negative, the outer wall (i.e., the wall in contact with the outside air) of the hollow cavity 4 begins to cool. The process of cooling the wall can be provided by a heat flux q _lz (Fig. 3), which is formed due to the temperature gradient of the outside air (t _winter ) and the wall. Thermal resistance

where α _1z is the heat transfer coefficient from the surface (kcal / (m ² ⋅ hour ⋅ hail)). As the wall cools, the air of the cavity 5 in contact with the wall begins to cool. A heat flux q _{2z is formed} at thermal resistance

. Since cold air is heavier than warm air, it begins to move down in the direction of 15. As it moves, heat flows q _{3z are formed} due to the temperature gradient of the vertical surface of the soil t _pz and air in the cavity 5. This heat exchange takes place both within the heat exchanger and the evaporator ,

. Thus, the total heat loss (i.e., cooling of the soil) in the winter period during τ _wintry can be represented approximately as follows:

At the beginning of the summer period, the upper gap is closed, and the valve acquires position 14. This eliminates the possibility of air convection in the summer period and, therefore, the possibility of heating the soil is sharply reduced. 1. With the upper gap closed, the total heat input (Fig. 4) will be determined by the formula:

where δ _of and λ _of are the thickness (m) and thermal conductivity coefficient (kcal / (m⋅h⋅grad), respectively) of the thermal insulation layer 9.

In formula (2), a coefficient of 1/3 is introduced for the thermal resistance R _3z , and this coefficient is not introduced for a similar thermal resistance in the summer period R _6l . This is because in the summer period there is no heat exchange in the underground part of the installation and, therefore, the heat transfer surface is approximately three times smaller (see Figs. 3 and 4).

For an approximate comparison of winter and summer heat transfer, we accept the following numerical values of the parameters:

α _1s = α _1l = 20 kcal / (m ² ⋅ hour ⋅ hail); α _2s = α _3s = α _2l = α _3l = α _5l = α _6l = 5 kcal / (m ² ⋅ hour ⋅ hail); δ _of = 0.1 m; λ _of = 0.05 kcal / (m⋅h⋅grad).

;Then

;

In other words, the thermal resistance in the winter is almost an order of magnitude less than the summer, and therefore, in the winter, the heat flux from the soil to the outside air is greater. In addition, the duration of the winter period τ _{winter is} greater than the duration of the summer period τ _summer . Therefore, we have a pronounced diode, i.e. Intensive heat transfer occurs in one direction (i.e., in winter), and heat transfer in the other (i.e., in summer) can be reduced to zero. By choosing the appropriate value of δ _from, heat transfer in the summer period can be almost completely eliminated.

Thermal insulation 10 (Fig. 2) is located between the cooling devices. It reduces heat flow in both winter and summer. It is possible to arrange devices over the entire width of the surface 2.

The proposed device for freezing soils on the lateral sections of building structures has the following essential features.

The first sign is a hollow container with a cavity uniform in height. The main essence of this technical solution is based on convective heat transfer. Without the presence of a single cavity with a height, convection is impossible.

Sign of the second - the cavity is closed at both ends. The cavity should not be connected to the outside air, since an open cavity is clogged with frost in the winter and stops working.

The third sign is the presence of a heat exchanger. This is necessary to ensure that the cavity contacts the outside air through the wall of the heat exchanger, which, in turn, is necessary for cooling the air inside the cavity during winter.

The fourth sign is the presence of an evaporator located in the ground and adjacent to the heat exchanger from below. Strictly speaking, in this design of the heat exchanger, the part of the cavity adjacent to the vertical surface 2 of the soil partially plays the role of the evaporator. However, with such a scheme, the cavity length may not be enough for the formation of “traction” in it, i.e. convection formation. In the presence of a part of the cavity located in the ground, a temperature difference is established along the length of the cavity, which creates a “traction”. In this case, the evaporator 7 can be located not only horizontally, but also vertically. As the height of bulk part 1 increases, the size of the evaporator may decrease.

The fifth sign - the heat exchanger is adjacent to the vertical surface 2. This is necessary, since it is from this part of the cavity 18 that the vertical surface is cooled in winter.

The sixth sign is a solid partition 8 with gaps at both ends, since it is this sign that ensures the separation of downward and upward flows 15, which provides a sharp increase in heat transfer efficiency.

The seventh sign is a valve located at position 13 in the winter and at position 14 in the summer. If the gap 11 is left unclosed in the summer, then thawing convection can form, while the air flows will move in the opposite direction to direction 15.

All these seven essential features are necessary and sufficient to achieve the goal - to increase cooling efficiency.

In addition to the above seven essential features, there may be two more that are noted in additional claims.

The sign of the eighth - thermal insulation 9. As noted above, thermal insulation can significantly increase thermal resistance in the summer, which will reduce the amount of thawing.

Sign ninth - the ability to perform the device in the form of a continuous wall. Unlike the prototype, where the channel for upward flows is located coaxially in the center of the cross section of the device, in the proposed technical solution, the cross section is divided in half by a flat partition, and therefore, it is more convenient to make the cross section of the device rectangular or extended in one of the directions.

Improving the cooling efficiency compared to the prototype is provided by combining active and passive cooling in one device: in winter the active system works, and only in the summer period additional thermal resistance is put into operation (in the prototype it works all year round). The use of thermal insulation 9 additionally significantly increases thermal resistance and also only in the summer.

Claims (3)

1. A device for freezing soils on the lateral sections of building structures, containing a hollow tank with a cavity that is uniformly closed at both ends, and the hollow tank has two parts in length: a heat exchanger located on top and an evaporator adjacent to it from the bottom, and the heat exchanger borders on the outside air, and the evaporator is located in the ground, characterized in that the heat exchanger is adjacent to the vertical surface of the side sections, and the cavity in the cross section is divided in half by solid second partition disposed parallel to the vertical surface and having gaps in the upper and lower ends of the cavity, wherein the gap area is equal to half of the cross sectional area of the cavity, wherein the upper gap is provided with a valve providing the opening or closing of the upper gap. 2. The system according to claim 1, characterized in that the partition along the heat exchanger is provided with thermal insulation. 3. The system according to p. 1, characterized in that the device along the length of the vertical surface is made in the form of a continuous wall.

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