CN115013995A - Novel middle-deep buried pipe heat exchanger - Google Patents

Abstract

The invention discloses a novel medium-deep buried pipe heat exchanger which comprises a heat exchanger body, wherein rock-soil body temperature is sequentially divided into a temperature changing layer, an isothermal layer and a temperature increasing layer from top to bottom according to temperature distribution in the depth direction of drilling, and the heat exchanger body is sequentially communicated with a straight pipe section, a single spiral section and a double spiral section from top to bottom; the straight pipe section, the single-spiral section and the double-spiral section are respectively provided with a water inlet pipe and a water outlet pipe, the water inlet pipe of the straight pipe section, the water inlet pipe of the single-spiral section and the water inlet pipe of the double-spiral section are sequentially communicated, and the water outlet pipe of the straight pipe section, the water outlet pipe of the single-spiral section and the water outlet pipe of the double-spiral section are sequentially communicated; the bottom of the double-spiral-section water inlet pipe is communicated with the bottom of the double-spiral-section water outlet pipe; the straight pipe section, the single-spiral section and the double-spiral section are naturally combined into an integral heat exchange structure by adopting a hollow triangular support, a support rod and a hollow guide mounting head. The invention has the outstanding advantages of high heat exchange efficiency, strong bearing capacity, less heat loss, high construction quality and the like.

Description

A new type of medium-deep buried tube heat exchanger

technical field

The invention belongs to the technical field of buried pipe heat exchangers, and in particular relates to a novel medium-deep buried pipe heat exchanger.

Background technique

With the continuous advancement of energy conservation and emission reduction and the proposal of goals, the vertical buried pipe heat pump system has received more and more attention. At present, the vertical buried pipe heat pump system can be divided into drilling depths generally between 50 and 200 meters. The shallow buried pipe heat pump system in between and the medium and deep buried pipe heat pump system with the drilling depth generally between 1000 and 3000 meters, but whether it is a shallow or medium deep buried pipe heat pump system, the buried pipe heat exchanger All are its key components, and its heat exchange efficiency directly determines the initial investment and system efficiency of the system. In order to improve the efficiency of the buried tube heat exchanger, many researchers have given and studied different structural forms of the buried tube heat exchanger. The common structural forms of the shallow buried tube heat exchanger are single U-shaped, double U-shaped and W-type, as well as the newly proposed spiral type, the research on these structural forms has greatly promoted the development and application of shallow buried pipe heat pump systems. Although the shallow buried pipe heat exchange technology has developed relatively early and the technology is relatively mature, in order to better achieve clean heating and promote the early realization of the "dual carbon" goal, the medium and deep buried pipe heat pump system has a small footprint, The heat output is large and stable, not affected by the outdoor climate, and has no unique advantages such as unbalanced cooling and heating of shallow buried pipes. Heater structure and its thermal performance have become a hot research topic.

The medium-deep buried tube heat exchanger is a new technology. At present, the structure is relatively simple. It is mainly a casing-type heat exchanger. At first, the inner/outer pipes of the casing-type heat exchanger were made of steel pipes, but there are serious problems of supply and return water heat. Therefore, the outer tube of the medium-deep casing heat exchanger is generally made of steel pipe, and the inner tube is generally made of plastic tube, which slows down the thermal short-circuit phenomenon to a certain extent, but there are still obvious shortcomings: 1. In the tube heat exchanger, only the outer tube wall is in full contact with the rock and soil mass for heat exchange, and the tube diameter is large and the tube wall is thick, and the entire water outlet pipe not only cannot exchange heat with the rock and soil mass, but also transfers heat to the water inlet pipe. The thermal short circuit is still obvious; ②Compared with the current shallow buried pipe heat exchanger, the outer diameter of the casing heat exchanger is generally larger, although it can increase the heat exchange between the water inlet pipe and the rock and soil mass, but it is difficult to drill in the middle and deep layers. In the initial tube well section of the hole, the heat dissipation to the rock and soil mass also increases, that is, the heat loss also increases. Although the utility model patent (CN 212299509 U) has improved the casing type medium-deep buried pipe heat exchanger, the flow velocity of the inlet water in the annular flow channel and the bending deformation resistance of the outer pipe are improved, but the improvement of the flow velocity and the improvement of the The heat exchange between the rock and soil mass also improves the heat exchange with the inner pipe, that is, the thermal short circuit is also enhanced; in addition, the existing shallow buried pipe heat exchanger structure is not suitable for medium and deep layers.

No matter the single U-shaped, double U-shaped, W-shaped and new spiral type (CN111536810B) of the shallow buried tube heat exchanger, or the casing type medium-deep buried tube heat exchanger, its structural form is an axisymmetric structure. Its inherent defects are: while increasing the heat exchange area to enhance heat transfer, thermal short-circuit and heat loss also increase, and for medium-deep buried tube heat exchangers, the defects of this inherent structure are more prominent.

Therefore, it is necessary to innovate the design of the structure of the buried tube heat exchanger in the middle and deep layers. Only in this way can the heat exchange efficiency of the buried tube heat exchanger be maximized, the energy output of the borehole tube well be enhanced, and the number of drilling wells can be reduced, thereby reducing the initial investment and floor space. In order to further promote energy conservation and emission reduction and promote the early realization of the "dual carbon" goal, a medium-deep underground heat exchanger was proposed.

To sum up, the structure design of the existing buried tube heat exchanger cannot well adapt to the temperature distribution of the borehole, the effective utilization rate of the drilling depth is not high, and the middle-deep buried tube heat exchanger has obvious thermal short-circuit and heat loss phenomenon. Aiming at the shortcomings of the existing buried tube heat exchangers, according to the analysis of the vertical temperature distribution of drilling and the heat transfer process, and based on the principle of heat transfer enhancement, a new type of medium-deep buried tube heat exchanger is creatively presented. The heat exchanger has the outstanding advantages of high heat exchange efficiency, less heat loss, strong pressure bearing capacity and high construction quality.

SUMMARY OF THE INVENTION

The invention provides a novel medium-deep buried pipe heat exchanger, which adopts different heat exchanger structures in different depth sections of drilling. . There are 3 inlet straight pipes and 3 outlet straight pipes in the straight pipe section. On the same horizontal plane, the 3 outlet pipes are located at the 3 vertices of the equilateral triangle, that is, they are evenly distributed on the circumcircle of the equilateral triangle. The water inlet pipe is located at the midpoint of the 3 sides of the equilateral triangle, that is, evenly distributed on the inscribed circle of the equilateral triangle; in a single spiral section, the water outlet pipe is a straight pipe, while the water inlet pipe is a spiral pipe, and the water outlet pipe is located in the spiral pipe. In the double helix section, the inlet and outlet pipes are spiral pipes, the inlet pipe is an inner helix, and the outlet pipe is a coaxial outer helix; and the pipe centers of the inlet and outlet pipes are located on concentric rings of different radii; The inlet and outlet pipes are connected by a U-shaped elbow at the bottom of the double helical section. The outlet pipe located at the vertex of the equilateral triangle is connected with the inlet pipe at the midpoint of the opposite side, and a hollow guide installation head is provided at the U-shaped bend; in order to ensure the installation quality of the heat exchanger, a hollow triangle is used to fix the pipe distance, and the The hollow triangle and the support rod fix the pitch, and the hollow guide mounting head is used to protect the U-shaped elbow and reduce the installation resistance.

The object of the present invention is achieved through the following technical solutions:

A novel medium-deep underground buried pipe heat exchanger comprises a heat exchanger body, wherein the heat exchanger body is a straight pipe section, a single-spiral section and a double-spiral section which are connected in sequence from top to bottom. The water inlet pipe is straight pipe, spiral pipe, spiral pipe from top to bottom along the tube well, and the water inlet straight pipe, enters and exits the middle spiral pipe, and enters and exits the lower spiral pipe in turn; , the water outlet straight pipe, the water outlet straight pipe, and the water outlet spiral pipe, the middle water outlet straight pipe, and the upper water outlet straight pipe are connected in turn; the water inlet pipe and the water outlet pipe are connected at the bottom of the double helical section through a U-shaped elbow, and the outlet corresponding to the triangle vertex The water pipe is communicated with the water inlet pipe corresponding to the center position of the vertex opposite to the edge.

The above-mentioned novel medium-deep buried pipe heat exchanger, the straight pipe section, the single-spiral section and the double-spiral section are all provided with three water inlet pipes and three water outlet pipes, and the three The water outlet pipes are respectively arranged on the circumscribed circle where the three vertices A, B and C of the triangle are located, and the three water inlet pipes are respectively arranged on the inscribed circle where the midpoints D, E and F of the three sides of the triangle are located; for the convenience of description, Let point D be the midpoint of the corresponding edge of vertex A, that is, D is the midpoint of the line connecting vertices B and C; E is the midpoint of the corresponding edge of vertex B, that is, E is the midpoint of the line connecting vertices A and C; F is the midpoint of the corresponding edge of vertex C, that is, F is the midpoint of the line connecting vertices A and B. Each water inlet pipe located at the midpoint of the side corresponding to the vertex of the triangle flows through the straight pipe section, the single helical section and the double helical section, and then flows into the bottom of the tube well, passes through the U-shaped elbow and flows into the water outlet pipe located at the corresponding vertex, and then passes through the double helical section in turn. The outer spiral pipe in the single spiral section, the water outlet straight pipe in the single spiral section and the water outlet straight pipe on the outer ring in the straight pipe section flow out.

In the double-spiral section, the horizontal projection of the outer spiral pipe of the water outlet is located on the ring where the vertices A, B, and C are located; the pipe center of the outlet straight pipe in the single spiral section and the outlet straight pipe in the straight Vertex A, B, C positions. The water inlet pipe core of the straight pipe section is located at the positions D, E, F, the midpoints of the three sides in the equilateral triangle; in the single helical section, the water inlet pipe is a spiral pipe, and the horizontal projection of the water inlet spiral pipe core of this section is located in the straight water outlet pipe of this section. It is located on the inscribed circle of the equilateral triangle ABC; in the double helix section, the water inlet pipe is an inner spiral pipe, and the horizontal projection of the pipe center of the water inlet spiral pipe is still located on the inscribed circle of the equilateral triangle ABC. There is no direct contact between the water inlet pipes, between the water outlet pipes, and between the inlet and outlet pipes, and the horizontal distance from the core of the water outlet pipe to the axis of the tube well is twice the horizontal distance from the core of the water inlet pipe to the axis of the tube well.

The heat medium flows in from the water inlet pipe corresponding to the midpoint of the opposite side of the vertex, and flows through the water inlet straight pipe of the straight pipe section, the water inlet spiral pipe of the single spiral section and the water inlet spiral pipe of the double spiral section in turn, and then passes through U. After the curved pipe, it flows into the water outlet pipe, passes through the water outlet spiral pipe of the double spiral section and the water outlet straight pipe of the single spiral section in turn, and finally is discharged from the water outlet straight pipe in the straight pipe section. That is, the heat medium flows into the water inlet pipe corresponding to the D position, passes through the straight pipe section, the single helix section and the double helix section, and then turns back through the U-shaped elbow, and then flows through the double helix section in turn. The water outlet pipe corresponding to the A position flows out; the heat medium flows from the water inlet pipe corresponding to the E position through the straight pipe section, the single helix section and the double helix section, and then goes back through the U-shaped elbow, and then flows through the double helix section and the single helix section in turn. and the straight pipe section, and finally flows out from the outlet pipe corresponding to the B position; the water inlet pipe corresponding to the F position passes through the double helical section, the single helical section and the straight pipe section, then folds back through the U-shaped elbow, and then flows through the double helical section in turn. The single spiral section and the straight pipe section will finally flow out from the outlet pipe corresponding to the C position.

In the above-mentioned novel medium-deep underground heat exchanger, the water outlet pipe of the single spiral section is a straight pipe, the water outlet pipe is on the circumscribed circle of the triangle, the water inlet pipe is a spiral pipe, and the pipe center of the spiral pipe is on the inscribed circle of the triangle superior.

The above-mentioned novel medium-deep underground heat exchanger, the water inlet pipe and the water outlet pipe of the double helical section are both spiral pipes, and the spiral pipe of the water inlet pipe is on the inscribed circle of the triangle, and the spiral pipe of the water outlet pipe is in the triangle. on the circumcircle.

The above-mentioned novel medium-deep buried pipe heat exchanger also includes a hollow triangular support, and through holes are provided at the positions of the vertices A, B, and C of the triangle support and the midpoints D, E, and F of the three sides. , The three water outlet pipes of the single helical section and the double helical section are respectively sleeved in the through holes corresponding to the three vertices A, B and C of the triangular bracket, and the three water inlet pipes are respectively sleeved in the midpoint D of the three sides of the triangle. , E, F in the corresponding position of the through hole.

The above-mentioned novel medium-deep buried tube heat exchanger also includes a support rod. For metal pipes, in the straight pipe section, no support rods are set between the two hollow triangular brackets; in the single helix section, three support rods are set between the two hollow triangle brackets; in the double helix section, three support rods are set between the two hollow triangle brackets rods, and the support rods are arranged on the outside of the inlet and outlet pipes. For plastic pipes, in the straight pipe section, no support rods are set between the two hollow triangular brackets; in the single spiral section, three support rods are set between the two hollow triangle brackets, and the support rods are located on the outer side of the water inlet spiral pipe and the water outlet straight. The inner side of the tube; in the double helix section, six support rods are arranged between the two hollow triangular brackets, three are arranged on the outer side of the outer spiral tube, and three are arranged on the inner side of the outer helix and the outer side of the inner helix.

The above-mentioned new mid-deep underground heat exchangers are connected by support rods between the upper and lower triangular brackets corresponding to the spiral tubes, so as to keep the inlet and outlet pipes using metal pipes (such as ordinary steel pipes, galvanized steel pipes, stainless steel pipes, etc. ), and its pitch will not be damaged during installation; if the inlet and outlet pipes are non-metallic pipes (such as plastic pipes PB, PE, etc.), it is necessary to set several spiral pipe fixing pipe clamps on the support rod horizontally. The fixed tube is clamped on the spiral tube to fix the plastic tube and fix its screw to ensure that the screw pitch is not damaged during installation. This structure is also suitable for shallow buried tube heat exchangers.

The above-mentioned novel medium-deep buried tube heat exchanger is provided with a hollow guide mounting head at the bottom of the double helical pipe, and at the bottom of the double helical section, the U-shaped connecting pipes connecting the water inlet pipe and the water outlet pipe are arranged in the hollow guide mounting head. The upper part of the hollow guide installation head is hemispherical, and the lower part is conical, and the "water drop"-shaped hollows are evenly distributed on the guide installation head.

In the above-mentioned novel medium-deep underground heat exchanger, the water inlet pipe corresponding to the D position of the double helical section is connected with the water outlet pipe corresponding to the A position through the U-shaped elbow; the water inlet pipe corresponding to the E position is connected to the U-shaped elbow through the U-shaped elbow. The water outlet pipe corresponding to the B position is connected; the water inlet pipe corresponding to the F position is communicated with the water outlet pipe corresponding to the C position through a U-shaped elbow.

In the above-mentioned novel medium-deep buried pipe heat exchanger, an insulating layer is provided on the outer jacket of the water outlet pipe of the straight pipe section.

Compared with the prior art, the present invention has the following beneficial technical effects:

On the basis of fully considering the vertical temperature distribution and lateral heat transfer process of the rock and soil layers in the drilling depth direction, the invention increases the temperature in the longitudinal direction as the depth increases, and increases the heat absorption section of the lower drilling rock and soil body. The effective heat exchange area, reduces the heat exchange area of the upper drilling section, which can not only reduce heat loss, but also improve the heat exchange efficiency of the buried tube heat exchanger, and at the same time improve the effective utilization rate of drilling; in the lateral direction, In the inner ring of the water inlet pipe, the outer ring of the water outlet pipe, the heat transfer process between the inlet and outlet pipes and the lateral heat transfer is macroscopically countercurrent heat exchange, and the heat exchange temperature difference increases, which can improve the heat exchange efficiency of the high temperature section of the rock and soil mass in the lower part of the drilling, and reduce the heat transfer rate. The heat dissipation loss of the rock and soil mass in the upper part of the drilling; compared with the existing medium-deep casing-type buried pipe heat exchanger, under the same drilling, the new middle-deep buried pipe heat exchanger has a small heat transfer thermal resistance, and heat transfer The speed is fast; the diameter of the inlet and outlet pipes is small, and the pressure bearing capacity is strong. In summary, the new type of medium-deep buried tube heat exchanger has the outstanding advantages of high heat exchange efficiency, strong pressure bearing capacity, less heat loss and high construction quality.

Description of drawings

FIG. 1 is a schematic structural diagram of the buried tube heat exchanger of the present invention.

FIG. 2 is a top view of the structure of the buried tube heat exchanger of the present invention.

3 is a schematic structural diagram of the present invention adding a spiral tube to fix the tube clip.

FIG. 4 is a schematic view of the structure of the hollow guide mounting head of the present invention.

Among them: 1 hollow guide installation head; 2 support rod; 3 water outlet spiral pipe; 4 triangular bracket; 5a water inlet spiral pipe; 5b water inlet spiral pipe, 6, 8, 12 water inlet pipe; 7, 9, 11 water outlet pipe; 10 Triangular hollow; 14 well wall; 15 insulation layer; 16 spiral pipe fixed pipe clamp; 17 hollow guide installation head; L1 double helical section; L2 single helical section; L3 double straight pipe section.

Detailed ways

The following are detailed implementation steps of the present invention.

As shown in Figure 1, Figure 2 and Figure 3, a new type of medium-deep buried tube heat exchanger includes a heat exchanger body. According to the temperature distribution in the drilling depth direction, the temperature of rock and soil mass is divided into variable temperature from top to bottom. Layer, isothermal layer and warming layer, most of the heat exchanger body is in the warming layer. Specifically: the heat exchanger body is composed of a straight pipe section L3, a single helical section L2 and a double helical section L1 that are connected in sequence from top to bottom. If the design temperature of the heat medium inlet is low, the straight pipe section is generally in the variable temperature layer. If the inlet heat medium temperature is high, the straight pipe section is in the variable temperature layer and the isothermal layer. The length of the double helical section L1 is determined according to the outlet temperature of the heat medium and the thermal response of the drilling rock and soil, and is generally located in the lower part of the warming layer. The length of the single helical section depends on the total drilling depth and the length of the straight pipe section L3 and the double helical section L2. , which is equal to the total drilling length minus the lengths of L2 and L3, respectively.

The straight pipe section L3, the single helical section L2 and the double helical section L1 are all provided with a water inlet pipe and a water outlet pipe. The water inlet pipe of the straight pipe section L3, the single helical section L2 water inlet pipe and the double helical section L1 water inlet pipe are connected in sequence, and the straight pipe section L3 The outlet pipe of the single helix section L2 and the outlet pipe of the double helix section L1 are connected in turn; at the bottom of the double helix section L1, the inlet pipe and the outlet pipe are connected through a U-shaped elbow, and the outlet pipe at the vertex of the equilateral triangle is connected to the The inlet pipe located at the midpoint of the edge opposite this vertex is connected.

Based on the heat transfer enhancement mechanism and the thermal resistance analysis of the heat transfer process, combined with the temperature distribution of the rock and soil in the drilling depth direction, different buried pipe heat exchange structures are used in different drilling sections of the same well. The area of the device increases sequentially. In the winter heating season, the temperature of the rock and soil increases with the drilling depth, and different heat exchange structures are used to reduce heat loss and improve heat exchange efficiency. Compared with the double helix structure, it can save pipe material and reduce heat loss. Increasing the heat exchange area along the drilling depth direction can improve the heat exchange efficiency with the rock and soil, or reduce the drilling depth under the same heat demand.

As shown in Figure 1, Figure 2 and Figure 3, the straight pipe section L3, the single helical section L2 and the double helical section L1 are all provided with three water inlet pipes 6, 8, 12 and three water outlet pipes 7, 9, 11, so The three water outlet pipes of the straight pipe section L3, the single helical section L2 and the double helical section L1 are respectively arranged on the circumscribed circles corresponding to the three vertices A, B and C of the equilateral triangle, and the three water inlet pipes are respectively arranged on the equilateral sides. On the inscribed circle corresponding to the midpoints D, E, and F of the three sides of the triangle.

The low-temperature heat medium from the heat exchanger flows through the effluent horizontal headers and flows into the three straight water inlet pipes located at the midpoints of the three sides of the equilateral triangle in the straight pipe section L3, and then flows into the spiral pipes in the single spiral section L2 in turn to absorb the rock. The heat of the soil, after raising the temperature of the water inlet pipe, flows into the inner helical pipe in the double helix section. In this pipe section, it continues to absorb the heat of the rock and soil, further increasing the temperature of the water inlet pipe, and finally passes through the double helix section L1. The U-shaped connecting pipe at the bottom flows into the outer helical pipe of the double helical section L1, and continues to absorb the heat of the rock and soil in the outer helical pipe, further increasing the temperature of the water outlet pipe, and then flows through the single helical section L2 and the straight pipe section L3. The three outlet straight pipes at the vertex of the side triangle are finally collected in the outlet horizontal header, and flow into the heat exchanger through the outlet horizontal header for heat exchange and cooling, then flow into the inlet horizontal header, and then split into the inlet water of the straight pipe section L3. tube to complete the heat exchange cycle.

The three water outlet pipes of the straight pipe section L3 are projected on the vertex of the equilateral triangle, that is, on the circumcircle of the equilateral triangle, and the three water inlet pipes are located at the midpoint of the equilateral triangle, that is, on the inscribed circle of the equilateral triangle, The 6 pipes can be fixed by the same equilateral triangle to ensure the pipe spacing and the uniform distribution of the inlet and outlet pipes in the drilling. At the same time, it is easy to distinguish the inlet and outlet pipes, and it is convenient for the connection of the inlet and outlet pipes and the horizontal header in the drilling. The temperature of the rock and soil mass in the straight pipe section L3 is relatively low, and the inlet and outlet pipes mainly play a role in conveying, so as to minimize the heat exchange area of the inlet and outlet pipes in this section, and reduce the heat dissipation to the rock and soil mass from the inlet and outlet pipes. The temperature is high, and the temperature difference between the water outlet pipe and the rock and soil mass is large. In order to further reduce the heat dissipation of the water outlet pipe, an insulation layer 15 is set for the water outlet pipe in the straight pipe section L3, and the temperature difference between the water inlet pipe and the rock and soil mass is small. , the heat dissipation of the water inlet pipe to the rock and soil mass is very small. According to the technical and economic analysis, the water inlet pipe in the straight pipe section is not insulated. This structural design can reduce the heat loss of the buried tube heat exchanger under the condition of saving investment. In the straight pipe section L1 of the present invention, the water inlet pipes are straight pipes 6, 8, and 10 located at positions D, E, and F of the midpoints of the three sides of the equilateral triangle, and the temperature of the water inlet pipe is generally slightly higher than that in the straight pipe section L3. The temperature of the soil body is not much different from the temperature of the rock and soil, and the heat loss of the water inlet pipe in this section can be ignored, so there is no insulation layer outside the water inlet straight pipe of this pipe section. When the heat medium flows downstream along the water inlet straight pipe, the temperature of the rock and soil mass outside the pipe gradually increases. When the temperature of the rock and soil mass is higher than the temperature of the heat medium in the water inlet straight pipe, When the temperature is higher than 3°C), the water inlet straight pipe becomes a helical pipe, and until the bottom of the well, the water inlet pipe is always a helical pipe. In the flow from top to bottom of the helical pipe, the heat of the rock and soil mass is continuously absorbed, and the water intake is continuously increased. The temperature of the water pipe, when the heat medium flows at the bottom of the double helix section, enters the outer helix water outlet pipe in the double helix section L1 through the bottom U-bend pipe, and the heat medium continues to be heated by the rock and soil in the outer helix water outlet pipe. The water inlet pipe adopts a spiral tube to increase the heat exchange area between the water inlet pipe and the rock and soil mass, thereby enhancing the heat exchange between the water inlet pipe and the rock and soil mass, thereby improving the heat exchange efficiency of the drilling.

In the double helical section L1 of the present invention, the water outlet pipe is an outer helical pipe. The heat medium passes through the U-shaped bend and flows from the water inlet spiral pipe 5b into the water outlet spiral pipe 3. As the heat medium flows from bottom to top in the water outlet spiral pipe, the temperature of the rock and soil gradually decreases, while the temperature of the heat medium gradually increases. If the temperature is high, the temperature difference between the rock and soil mass and the heat medium is gradually smaller. When the temperature difference is reduced to a certain extent (for example, when the temperature of the rock and soil mass and the temperature of the heat medium are less than 3-4°C), the water outlet spiral pipe becomes a straight pipe. In the double helix section, the temperature of the rock and soil mass is significantly higher than the temperature of the water outlet pipe. In order to further absorb the heat in the rock and soil mass, the heat exchange area of the water outlet pipe needs to be increased. Therefore, the water outlet pipe is set as a spiral tube to improve the heat exchange of the drilling. efficiency. In the single spiral section, the temperature difference between the temperature of the water outlet pipe and the temperature of the rock and soil mass in this pipe section is small. In order to reduce the circulation resistance and save the pipe material, the water outlet pipe is set as a straight pipe in the single spiral section L2. There is little difference in the temperature difference between the two, and the heat exchange area is small, so the heat exchange between the water outlet pipe and the rock and soil mass is very small, and there is no need to lay a thermal insulation layer outside the water outlet pipe of this pipe section. In the straight pipe section L3, the water outlet straight pipes 9, 11 and 7 are located at the vertices A, B, and C of the equilateral triangle vertices, respectively. The temperature of the water outlet pipe is significantly higher than the temperature of the rock and soil mass, although the water outlet pipe is still a straight pipe section, The heat exchange area is small, but due to the large temperature difference, the heat loss cannot be ignored. Through the technical and economic comparison, it is advisable to set the insulation layer 15 on the outer pipe of the water outlet pipe, which can significantly reduce the heat loss of the water outlet pipe and ensure the temperature of the water outlet pipe. This structural design can improve the effective utilization of drilling depth and reduce heat loss at the same time.

In the buried tube heat exchanger of the present invention, the pipe well section in which the water inlet pipe is a spiral pipe 5a and the water outlet pipe is a straight pipe section is called a single spiral section L2; the tube well section in which both the water inlet and water outlet pipes are spiral pipes is called a double pipe section The spiral pipe section L1, the pipe well section in which both the inlet and outlet pipes are straight pipes is called the straight pipe section L3. The length of the straight pipe section L3 depends on the inlet water temperature and the rock and soil temperature; the length of the double-spiral pipe section L1 depends on the temperature of the water outlet pipe and the rock and soil temperature. The water inlet pipe in the double helical section L1 is the inner helical pipe 5b. In the double helical section, the heat from the rock and soil mass is first transferred to the water outlet spiral pipe 3 of the L1 section, and then transferred to the inner spiral water inlet pipe 5b. The use of inner and outer double helical tubes, with the outer helix as the water outlet pipe and the inner helix as the water inlet pipe, is countercurrent to the lateral heat transfer with the rock and soil mass, which can enhance the heat exchange with the rock and soil mass and further increase the temperature of the water outlet pipe. .

The water inlet pipe 5b and the water outlet pipe 3 of the double helical section L1 of the present invention are both spiral pipes, and the water inlet pipe is an inner spiral pipe 5b, the spiral pipe of the water inlet pipe is on the inscribed circle of an equilateral triangle, and the water outlet pipe is an outer spiral The water outlet spiral tube is on the circumcircle of the triangle, and the inner and outer spiral tubes are concentric spiral tubes, and the outer spiral radius is twice the inner spiral radius.

The temperature of the rock and soil mass in the double-spiral section at the bottom of the novel medium-deep buried tube heat exchanger of the present invention is higher than the temperature of the inlet and outlet pipes. All are set as spiral tubes to further increase the heat exchange area to improve the utilization rate of the heat of the rock and soil mass. The inlet and outlet spiral pipes are arranged in the inner ring, the outlet spiral pipes are arranged in the outer ring, the water outlet pipe is located at a relatively high temperature during the lateral heat transfer process, and the water inlet pipe is located at a relatively low temperature during the lateral heat transfer process. The buried tube heat exchanger and the rock and soil exchange heat in countercurrent, so the heat exchange temperature difference can be increased, and the heat exchange efficiency can be further improved

In the present invention, in the initial section of drilling, straight pipe sections are used for the water inlet and outlet pipes, and the purpose is to reduce the heat exchange area, so the heat loss can be reduced. The water inlet and outlet pipes of the present invention are not in direct contact, which can effectively avoid thermal short circuit existing in the casing heat exchanger. In addition, the lengths of the straight pipe section L3, the single helical section L2 and the double helical section L1 of the present invention should be determined according to drilling response experiments, theoretical analysis and numerical simulation experiments, and depend on rock and soil properties and local water level.

As shown in Figures 1 and 3, the novel medium-deep underground heat exchanger also includes a hollow triangular bracket 10, at the positions D, E, and F corresponding to the vertices A, B, C and the three sides of the triangular bracket. A through hole is provided on the upper part, and the three water outlet pipes of the straight pipe section L3, the single helical section L2 and the double helical section L1 are respectively sleeved in the through holes corresponding to the three vertices A, B, and C of the triangular support, and the three The water inlet pipes are respectively sleeved in the through holes corresponding to the midpoints D, E and F of the three sides of the triangle. The upper and lower triangular brackets 10 corresponding to the helical tubes are connected by a support rod 2 , and a plurality of helical tube fixing tube clips 16 are arranged laterally on the supporting rod, and the helical tube fixing tube clips are clamped on the helical tube. The novel medium-deep buried pipe heat exchanger is provided with a horizontal triangular bracket, which can not only make the heat exchange structure of different drilling sections naturally integrated, but also can fix the pipe spacing between the buried pipes, and at the same time facilitate the entry and exit of water pipes. It can improve the construction quality; there are support rods between the hollow triangular brackets to keep the pitch of the inlet and outlet spiral pipes from being deformed during installation, which overcomes the difficulty in ensuring the installation of shallow buried pipe heat exchangers. Disadvantages of tube spacing and pitch. The guide mounting head of the novel medium-deep buried tube heat exchanger is hollow, the triangular bracket is hollow, and the helix is coaxial with the drilling, which can ensure that the existing construction technology is still applicable; The pipe wall is in close contact with the drilling wall 14, which reduces the contact thermal resistance and further improves the heat transfer efficiency of the buried pipe.

As shown in Figure 1, Figure 2 and Figure 3, in the new type of medium-deep underground heat exchanger, the water outlet pipe corresponding to the position A of the double helical section L1 passes through the U-shaped elbow and the midpoint D on the opposite side of the position A. The water inlet pipe corresponding to the position is connected; the water outlet pipe corresponding to the B position is connected to the water inlet pipe corresponding to the midpoint E position on the opposite side of the B position through the U-shaped elbow; the water outlet pipe corresponding to the C position is connected to the U-shaped elbow through the U-shaped elbow. The water inlet pipe corresponding to the midpoint F position on the opposite side of the C position is connected. A hollow guide installation head is arranged at the bottom of the double helical pipe, and the U-shaped connecting pipes of the water inlet and outlet pipes of the double helix section L1 are arranged in the hollow guide installation head 1 .

The inlet and outlet pipes of the novel medium-deep underground heat exchanger are connected through a U-shaped elbow at the bottom, and the outlet pipe at the vertex of the equilateral triangle is connected with the inlet pipe at the midpoint of the opposite side, rather than the nearest outlet pipe. In this way, the bending radius of the U-shaped elbow can be increased, which is convenient for the production of the U-shaped elbow.

As shown in Figure 4, the U-shaped elbow of the present invention is provided with a hollow guide installation head 1, one can protect the bottom U-shaped elbow, and the other is convenient for installation, so as to avoid the U-shaped elbow from being damaged or deformed during installation ; Set hollows on the guide installation head to facilitate the filling of backfill materials, so the above measures can effectively ensure the construction quality.

Compared with the existing casing type buried pipe heat exchanger, the present invention has smaller pipe diameters of the inlet and outlet pipes of the novel medium-deep buried pipe heat exchanger under the same flow rate and pressure bearing capacity in the same drilling. , The flow rate is high and the tube wall is thin, so the heat transfer resistance is small, so it can further improve the efficiency of the buried tube heat exchanger.

On the basis of fully considering the vertical temperature distribution and lateral heat transfer process of drilling, the invention creatively utilizes the advantages of 3U type, spiral type and casing type buried pipe heat exchanger, overcomes its shortcomings, and effectively avoids the The occurrence of thermal short circuit. Along the drilling longitudinal direction, with the increase of temperature, the heat exchange area increases, that is, the effective heat exchange area of the heat absorption section is increased, and the ineffective heat exchange area of the heat dissipation section is reduced, which can not only reduce heat loss, but also improve heat exchange. Efficiency and effective utilization rate of drilling; in the lateral direction, the water inlet pipe is in the inner ring, the water outlet pipe is outer ring, the inlet and outlet pipes and the transverse heat transfer process are macroscopically countercurrent heat exchange, which can further improve the heat exchange efficiency; compared with the existing For the medium-deep casing-type buried pipe heat exchanger, under the same drilling, the new medium-deep buried pipe heat exchanger has small heat transfer resistance and fast heat transfer rate; the inlet and outlet pipes have small diameters and high pressure bearing capacity. powerful. In summary, the new type of medium-deep buried tube heat exchanger has the outstanding advantages of high heat exchange efficiency, strong pressure bearing capacity, less heat loss and high construction quality.

The technical means disclosed in the technical solutions of the present invention are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims (10)

1. The utility model provides a novel well deep layer ground heat exchanger, includes the heat exchanger body, its characterized in that: the heat exchanger body consists of a straight pipe section, a single spiral section and a double spiral section which are sequentially communicated from top to bottom, wherein the straight pipe section, the single spiral section and the double spiral section are respectively provided with a water inlet pipe and a water outlet pipe; the bottom of the double-spiral section water inlet pipe is communicated with the bottom of the double-spiral section water outlet pipe.

2. A novel mid-depth buried heat exchanger according to claim 1, wherein: the straight pipe section, the single spiral section and the double spiral section are respectively provided with three water inlet pipes and three water outlet pipes, the three water outlet pipes of the straight pipe section, the single spiral section and the double spiral section are respectively arranged at positions corresponding to three vertexes A, B, C of the triangle, and the three water inlet pipes are respectively arranged at the positions of midpoints D, E, F of three sides of the triangle; the water inlet pipe corresponding to the middle point of each triangle three sides sequentially passes through the straight pipe section, the single spiral section and the double spiral section, and then sequentially passes through the double spiral section, the single spiral section and the straight pipe section of the water outlet pipe corresponding to the vertex position opposite to the side to be discharged.

3. A novel mid-depth buried heat exchanger according to claim 2, wherein: the water outlet pipe of the single spiral section is a straight pipe, the water outlet pipe is arranged on the outer circle of the triangle, the water inlet pipe is a spiral pipe, and the spiral pipe is arranged on the inner circle of the triangle.

4. A novel mid-depth buried heat exchanger according to claim 2, wherein: the water inlet pipe and the water outlet pipe of the double-spiral section are both spiral pipes, the spiral pipes of the water inlet pipe are arranged on the inner tangent circle of the triangle, and the spiral pipes of the water outlet pipe are arranged on the outer circumcircle of the triangle.

5. A novel mid-depth buried heat exchanger according to claim 2, wherein: the water outlet pipes of the straight pipe section, the single spiral section and the double spiral section are respectively sleeved in the through holes at the corresponding positions of the three vertexes A, B, C of the triangular support, and the three water inlet pipes are respectively sleeved in the through holes at the corresponding positions of the midpoints D, E, F of the three sides of the triangle.

6. A novel mid-depth buried heat exchanger according to claim 5, wherein: the upper triangular bracket and the lower triangular bracket which correspond to the single spiral section and the double spiral section are connected through a supporting rod; the supporting rod is transversely provided with a plurality of spiral pipe fixing pipe clamps which are clamped on the spiral pipes.

7. A novel mid-depth buried heat exchanger according to claim 6, wherein: in the single spiral section, a supporting rod is arranged between the upper triangular bracket and the lower triangular bracket which correspond to the spiral pipe and the straight pipe; in the double-helix section, an inner supporting rod is arranged between the corresponding upper triangular bracket and the corresponding lower triangular bracket between the inner helix tube and the outer helix tube, and an outer supporting rod is arranged outside the outer helix tube; the internal spiral pipe fixing pipe clamp for clamping the internal spiral pipe is arranged on the internal support rod, and the external spiral pipe fixing pipe clamp for clamping the external spiral pipe is arranged on the external support rod.

8. A novel mid-depth buried heat exchanger according to any one of claims 2 to 7, wherein: the hollow guide mounting heads are arranged at the bottoms of the double spiral pipes, and the water inlet pipe and the water outlet pipe at the bottom of the double spiral section are communicated and are arranged in the hollow guide mounting heads.

9. A novel mid-depth buried heat exchanger according to claim 8, wherein: the water outlet pipe corresponding to the position A at the bottom of the double helix section is communicated with the water inlet pipe corresponding to the position D of the middle point of the opposite side of the position A through the U-shaped bent pipe; the water outlet pipe corresponding to the position B is communicated with the water inlet pipe corresponding to the midpoint E of the opposite side of the position B through the U-shaped bent pipe; and the water outlet pipe corresponding to the C position is communicated with the water inlet pipe corresponding to the middle point F position of the opposite side of the C position through the U-shaped bent pipe.

10. A novel mid-depth buried heat exchanger according to claim 1, wherein: the water outlet pipe of the straight pipe section is sleeved with a heat-insulating layer.

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