Waste heat recovery device adopting stepped fins and using method of waste heat recovery device

Abstract

The invention discloses a waste heat recovery device adopting stepped fins and a using method of the waste heat recovery device, and belongs to the technical field of thermoelectric power generation. The device comprises a stepped fin module, an annular thermoelectric module and a liquid cooling module which are sequentially sleeved from inside to outside, a ceramic plate is arranged between the stepped fin module and the annular thermoelectric module; a ceramic plate is arranged between the annular thermoelectric module and the liquid cooling module; the stepped fin module comprises a heat pipe, and a plurality of fins arranged in a spiral stepped mode are attached to the outer wall of the heat pipe. The annular thermoelectric module comprises a plurality of stages of P / N type semiconductor units which are axially arranged to form a cylindrical structure; the P / N type semiconductor unit comprises a plurality of P type semiconductors and N type semiconductors which are arranged at intervals to form a circular ring shape, and the adjacent P type semiconductors and N type semiconductors are connected through conducting strips. Due to the unique design of the stepped fin module, particularly the fins are arranged in a spiral stepped manner, the contact area between the heat pipe and a surrounding medium is greatly increased.

Description

Technical Field

[0001] The invention belongs to the technical field of thermoelectric power generation, and relates to a waste heat recovery device using stepped fins and a use method thereof. Background Art

[0002] Industrial exhaust, as an inevitable product of the production process, often carries a large amount of heat energy. Due to technical limitations and the limitations of traditional treatment methods, this part of heat energy is often not fully utilized, but is directly discharged into the atmosphere, resulting in a huge waste of energy. With the continuous growth of global energy demand and the increasing awareness of environmental protection, how to effectively utilize this neglected part of heat energy has become a focus of common concern in academia and industry. Thermoelectric power generation technology, as an innovative means of energy conversion, provides a new possibility for solving this problem. Based on the principle of thermoelectric effect, this technology can directly convert waste heat in exhaust gas into electrical energy, thereby realizing energy reuse. This process not only helps to reduce energy waste and improve overall energy utilization efficiency, but also can alleviate the negative impact of industrial emissions on the environment to a certain extent, making a positive contribution to environmental protection.

[0003] However, despite the many advantages of thermoelectric power generation technology, it still faces some challenges in its actual application. Especially in the waste heat recovery link, when the heat flow passes through the pipe of the waste heat recovery device, although most of the heat can be gradually absorbed by the pipe wall and converted into electrical energy, the gas flowing to the tail end still carries a part of the heat that has not been fully absorbed. If this part of the residual heat is directly discharged, it will mean a reduction in energy conversion efficiency and a waste of potential energy. Therefore, how to further improve the absorption efficiency of waste heat and ensure that the heat energy in the tail gas is more fully utilized is one of the key issues that need to be solved in the current development of thermoelectric power generation technology. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problem in the waste heat recovery link in the prior art, that when the heat flow passes through the pipeline of the waste heat recovery device, the gas flowing to the tail end still carries a part of the heat that has not been fully absorbed, and to provide a waste heat recovery device using stepped fins and a method for using the same.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention discloses a waste heat recovery device using stepped fins, comprising a stepped fin module, an annular thermoelectric module and a liquid cooling module which are sequentially sleeved from the inside to the outside; a ceramic plate is arranged between the stepped fin module and the annular thermoelectric module; a ceramic plate is arranged between the annular thermoelectric module and the liquid cooling module; The stepped fin module includes a heat pipe, and a plurality of fins arranged in a spiral step shape are attached to the outer wall of the heat pipe; the annular thermoelectric module includes a plurality of levels of P / N-type semiconductor units arranged in a cylindrical structure along the axial direction; the P / N-type semiconductor unit includes a plurality of P-type semiconductors and N-type semiconductors arranged in a circular ring shape at intervals, and the adjacent P-type semiconductors and N-type semiconductors are connected by a conductive sheet.

[0006] Further improvements are: The liquid cooling module comprises a double-layer liquid cooling pipe, and a liquid cooling part is formed between the double-layer liquid cooling pipe; the flow direction of the cooling medium in the liquid cooling part is consistent with the heat flow direction.

[0007] The outer wall of the heat pipe is attached with a plurality of rows of n-level fins arranged in a spiral staircase shape; the thickness of each level of fins in a single row is W 2, and the spacing between the two-stage fins is D 2; The fins of the single-row spiral staircase have the same total axial length as the heat pipe, both of which are n ( W 2+ D 2); The first level fin in the single-row spiral staircase fin is set at the heat flow inlet, denoted as A 1; The nth level fin is set at the heat flow outlet, denoted as A n .

[0008] The fins are evenly distributed at equal intervals along the radial direction on the outer wall of the heat pipe.

[0009] The geometric parameters of the P-type semiconductor and the N-type semiconductor in the same P / N-type semiconductor unit are the same.

[0010] The number of P-type semiconductors and the number of N-type semiconductors in the same P / N-type semiconductor unit are the same.

[0011] 7. The waste heat recovery device using stepped fins according to claim 5 is characterized in that the central angles of the P-type semiconductor and the N-type semiconductor are both , the central angle between adjacent P-type semiconductors and N-type semiconductors is ; The central angles of the conductive sheets connecting adjacent P-type semiconductors and N-type semiconductors are .

[0012] The width of each P / N type semiconductor unit is W 1. The distance between two adjacent levels is D 1. The length of the annular thermoelectric module is M ( W 1+ D 1).

[0013] Both ends of the heat pipe are hollow structures, which are used to reduce the back pressure of air flow loss along the pipe wall.

[0014] In a second aspect, the present invention discloses a method for using a waste heat recovery device using stepped fins, comprising: The waste heat recovery device is installed near the heat source that needs to recover waste heat, and the heat source is started so that the heat is transferred to the stepped fins through the heat pipe, and then evenly dispersed to the entire waste heat recovery device; the annular thermoelectric module converts thermal energy into electrical energy through the thermoelectric effect, and the converted electrical energy is exported through the conductive sheet for use or storage by external equipment; at the same time, the liquid cooling module starts to work, and takes away excess heat through the circulating coolant to prevent the waste heat recovery device from overheating and damage; according to the actual waste heat recovery efficiency and temperature control requirements, the working fluid flow in the heat pipe and the cooling rate of the liquid cooling module are adjusted to achieve the best thermoelectric conversion efficiency and waste heat recovery effect.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a waste heat recovery device using stepped fins. The unique design of the stepped fin module, especially the spiral stepped arrangement of the fins, greatly increases the contact area between the heat pipe and the surrounding medium, thereby improving the heat exchange efficiency. This design enables heat to be transferred to the thermoelectric module more quickly and evenly, and then converted into electrical energy. The present invention allows the performance of the heat exchange device to be further optimized by changing the thickness, spacing and angle of the stepped fins according to actual needs. This flexibility enables the device to be suitable for waste heat recovery needs under different working conditions and achieve higher energy utilization efficiency. The stepped fin module, the annular thermoelectric module and the liquid cooling module are sequentially arranged from the inside to the outside, so that the entire device has a compact structure and a small footprint. This design not only saves installation space, but also helps to reduce manufacturing and maintenance costs. The ceramic plate, as a heat insulation and support material, not only improves the high temperature resistance of the device, but also effectively isolates the heat transfer between the thermoelectric module and the liquid cooling module, avoiding performance degradation or damage caused by excessive temperature gradient. At the same time, the ceramic plate also enhances the mechanical strength of the device and improves the overall stability and reliability. The invention reduces dependence on traditional energy and carbon emissions by efficiently recovering and utilizing waste heat resources, which is in line with the sustainable development concept currently advocated by the world. In addition, the device is easy to maintain and upgrade, providing a strong guarantee for long-term stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 It is a three-dimensional diagram of a waste heat recovery device using stepped fins in the present invention; Figure 2 It is a front view of a waste heat recovery device using stepped fins in the present invention; Figure 3 A three-dimensional diagram of a waste heat recovery device using stepped fins without fins in the present invention; Figure 4 It is a front view of a waste heat recovery device using stepped fins in the present invention without fins; Figure 5 A three-dimensional diagram of an annular thermoelectric module of a waste heat recovery device using stepped fins in the present invention; Figure 6 It is a front view of an annular thermoelectric module of a waste heat recovery device using stepped fins in the present invention; Figure 7 A three-dimensional diagram of fins arranged in a single row of spiral steps in a waste heat recovery device using stepped fins in the present invention; Figure 8 It is a front view of a single row of spiral stepped fins arranged in a waste heat recovery device using stepped fins in the present invention; Fig. 9 A side view of a single row of spiral stepped fins of a waste heat recovery device using stepped fins in the present invention; Fig.10 It is a schematic diagram of the liquid cooling part of a waste heat recovery device using stepped fins in the present invention; Fig.11 It is a schematic diagram of improving the heat exchange efficiency of a waste heat recovery device using stepped fins in the present invention.

[0018] Among them: 1-P / N type semiconductor unit; 2-conductive sheet; 3-heat pipe; 4-fin; 5-liquid cooling part; 6-double-layer liquid cooling pipeline; 7-ceramic plate; 8-ring thermoelectric module. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0022] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0023] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 1 , Figure 2 , Figure 3 and Figure 4 The embodiment of the present invention provides a waste heat recovery device using stepped fins, including a stepped fin module, an annular thermoelectric module and a liquid cooling module which are sequentially sleeved from the inside to the outside; a ceramic plate is arranged between the stepped fin module and the annular thermoelectric module; a ceramic plate 7 is arranged between the annular thermoelectric module and the liquid cooling module; the stepped fin module includes a heat pipe 3, and a plurality of fins 4 arranged in a spiral step shape are attached to the outer wall of the heat pipe 3; the annular thermoelectric module 8 includes a plurality of P / N type semiconductor units 1 arranged in a cylindrical structure along the axial direction; the P / N type semiconductor unit 1 includes a plurality of P type semiconductors and N type semiconductors arranged in a circular ring shape at intervals, and the adjacent P type semiconductors and N type semiconductors are connected by a conductive sheet 2. The liquid cooling module includes a double-layer liquid cooling pipe 6, and a liquid cooling part 5 is provided between the double-layer liquid cooling pipe 6; the flow direction of the cooling medium in the liquid cooling part 5 is consistent with the heat flow direction.

[0026] See also Figure 5 and Figure 6 , the annular thermoelectric modules are axially distributed into M rows at equal intervals along the heat flow direction, and the center angles of the M rows of annular thermoelectric modules along the heat flow direction remain unchanged; two adjacent rows of annular thermal modules are connected by upper and lower conductive sheets. The geometric parameters of the P-type semiconductor and the N-type semiconductor in the same P / N-type semiconductor unit are the same, the number of P-type and N-type thermoelectric semiconductors in each row of thermoelectric modules is equal, both are m, n = 1, 2, 3, ..., and the number of upper and lower conductive sheets is equal, both are n / 2; the specifications of the P-type and N-type thermoelectric semiconductors in each row are the same and are staggered; the center angles corresponding to the P-type and N-type thermoelectric semiconductors are both , the central angle between adjacent P-type and N-type thermoelectric semiconductors is ; The central angles of the upper and lower conductive sheets are . The thickness of the upper and lower ceramic plates is the same; the thickness of the upper and lower conductive sheets is the same; the thickness of the P-type and N-type semiconductors are the same. The pipeline surrounded by the annular thermoelectric module is divided into M columns along the heat flow direction, M = 1, 2, 3, ..., the width of each column is W1, the spacing between two adjacent columns is D1, and the length of the entire pipeline is M (W1+ D1); the first column of annular modules is close to the heat flow inlet, and the Mth column of annular modules is close to the heat flow outlet.

[0027] See also Figure 7 , Figure 8 and Fig. 9 The stepped fins are attached to the surface of the heat pipe and are distributed in a stepped manner with equal spacing along the heat flow direction; a single row of stepped fins is composed of n levels of fan-shaped fins, n = 1, 2, 3, ..., and the width of each level is W2. The total axial length of the single-row stepped fin and the heat pipe is the same, both are n ( W 2+ D 2); Among them, the first-stage fan-shaped fin of the single-row stepped fin is close to the heat flow inlet, which is recorded as A 1; The nth level fan-shaped fin is close to the heat flow outlet, denoted as A n The step-shaped fins are evenly distributed along the radial direction at equal intervals. The step-shaped fins can be divided into n levels along the radial direction, which are respectively denoted as A, B, ...; wherein the first level fan-shaped fins of each row are respectively denoted as A 1, B 1, and the second-stage fan-shaped fins of each row are respectively A 2, B 2, and so on. The total axial length of the stepped fin is equal to that of the annular thermoelectric module, that is, M( W 1+ D 1) = n ( W 2+ D 2). The stepped fins are attached to the surface of the heat pipe and are distributed in a stepped manner with equal spacing along the heat flow direction; the angle between adjacent fan-shaped fins is , A 1 and A n The radial angle is 0, that is, The two ends of the heat pipe 3 are hollow structures to reduce the back pressure of air flow loss along the pipe wall.

[0028] join Fig.10 The liquid cooling module comprises a double-layer liquid cooling pipe (6), and a liquid cooling part (5) is formed between the double-layer liquid cooling pipe (6); the flow direction of the cooling medium in the liquid cooling part (5) is consistent with the heat flow direction. The inner wall of the double-layer liquid cooling pipe 6 is connected to the upper and lower ceramic plates, and the outer wall of the double-layer liquid cooling pipe 6 is in contact with the air.

[0029] The present invention discloses a waste heat recovery device using stepped fins. The unique design of the stepped fin module, especially the spiral stepped arrangement of the fins, greatly increases the contact area between the heat pipe and the surrounding medium, thereby improving the heat exchange efficiency. This design enables heat to be transferred to the thermoelectric module more quickly and evenly, and then converted into electrical energy. The present invention allows the performance of the heat exchange device to be further optimized by changing the thickness, spacing and angle of the stepped fins according to actual needs. This flexibility enables the device to be suitable for waste heat recovery needs under different working conditions and achieve higher energy utilization efficiency. The stepped fin module, the annular thermoelectric module and the liquid cooling module are sequentially arranged from the inside to the outside, so that the entire device has a compact structure and a small footprint. This design not only saves installation space, but also helps to reduce manufacturing and maintenance costs. The ceramic plate, as a heat insulation and support material, not only improves the high temperature resistance of the device, but also effectively isolates the heat transfer between the thermoelectric module and the liquid cooling module, avoiding performance degradation or damage caused by excessive temperature gradient. At the same time, the ceramic plate also enhances the mechanical strength of the device and improves the overall stability and reliability. The invention reduces dependence on traditional energy and carbon emissions by efficiently recovering and utilizing waste heat resources, which is in line with the sustainable development concept currently advocated by the world. In addition, the device is easy to maintain and upgrade, providing a strong guarantee for long-term stable operation.

[0030] The embodiment of the present invention further discloses a method for using a waste heat recovery device using stepped fins, comprising: The waste heat recovery device is installed near the heat source that needs to recover waste heat, and the heat source is started so that the heat is transferred to the stepped fins 4 through the heat pipe 3, and then evenly distributed to the entire waste heat recovery device; the annular thermoelectric module converts thermal energy into electrical energy through the thermoelectric effect, and the converted electrical energy is exported through the conductive sheet 2 for use or storage by external equipment; at the same time, the liquid cooling module starts to work, and the excess heat is taken away by the circulating coolant to prevent the waste heat recovery device from overheating and damage; according to the actual waste heat recovery efficiency and temperature control requirements, the working fluid flow in the heat pipe 3 and the cooling rate of the liquid cooling module are adjusted to achieve the best thermoelectric conversion efficiency and waste heat recovery effect.

[0031] A power calculation method for a waste heat recovery device using stepped fins in the present invention comprises the following steps: In order to verify the feasibility of the structure, COMSOL simulation was used for verification. Here, in order to reduce the calculation time, the selected stepped fins are divided into 4 rows and 20 levels, and each row of stepped fins is arranged at full angles around the heat pipe in the radial direction, and the axial extension distance is the same as the total length of the heat pipe wall. There are 16 pairs * 16 rows of thermoelectric semiconductors on the annular thermoelectric module. In fact, a larger heat exchanger specification is used to ensure it, but the overall device is symmetrically distributed, so it will not affect the feasibility verification.

[0032] The total output power of the entire device is calculated as:

[0033] in and Respectively represent i The output power and the square of the output voltage of the ring-shaped thermoelectric module. n represents the number of thermoelectric modules. R L is the load resistance, here it is 12.5Ω.

[0034] The airflow passes through the heat exchanger, generating back pressure loss:

[0035] in and are the mass flow rate of the exhaust gas and the air density at this temperature, represents the pressure drop between the inlet and outlet. Here, =0.005, , The specific values ​​were obtained through COMSOL simulation [1].

[0036] [1].Luo, D., et al., Exhaust channel optimization of the automobile thermoelectric generator to produce the highest net power. Energy, 2023.281. Table 1 shows the various boundary conditions required for the simulation, including the inlet temperature and mass flow rate of the exhaust gas.

[0037] Table 1 Various boundary conditions

[0038] The thermoelectric materials used for the P-type semiconductor and the N-type semiconductor used in this example are bismuth telluride-based thermoelectric materials. The parameters of the P-type semiconductor and the N-type semiconductor and other materials are shown in Table 1.

[0039] Table 2 Material parameters of bismuth telluride-based thermoelectric devices

[0040] The relevant size parameters of each component are shown in Table 3.

[0041] Table 3 Specific parameters

[0042] Change the angle of the fan-shaped fins in the stepped fins and select The performance of the heat exchange device under (traditional), 9, 18, and 36 is compared. It can be seen that the total power increases with The increase of back pressure loss is gradually increasing, and the net power obtained is = 18. At this time, N = 4, the air inlet temperature is 500K, the improvement effect is 35%, the effect is as follows Fig.11 shown.

[0043] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A waste heat recovery device using stepped fins, characterized in that: It comprises a stepped fin module, an annular thermoelectric module and a liquid cooling module which are sequentially arranged from the inside to the outside; a ceramic plate is arranged between the stepped fin module and the annular thermoelectric module; and a ceramic plate (7) is arranged between the annular thermoelectric module and the liquid cooling module; The stepped fin module comprises a heat pipe (3), the outer wall of the heat pipe (3) being attached with a plurality of fins (4) arranged in a spiral stepped shape; the annular thermoelectric module (8) comprises a plurality of levels of P / N-type semiconductor units (1) arranged in a cylindrical structure along the axial direction; the P / N-type semiconductor unit (1) comprises a plurality of P-type semiconductors and N-type semiconductors arranged in a circular ring shape at intervals, and the adjacent P-type semiconductors and N-type semiconductors are connected via a conductive sheet (2).

2. The waste heat recovery device using stepped fins according to claim 1, characterized in that: The liquid cooling module comprises a double-layer liquid cooling pipe (6), and a liquid cooling part (5) is provided between the double-layer liquid cooling pipe (6); the flow direction of the cooling medium in the liquid cooling part (5) is consistent with the heat flow direction.

3. The waste heat recovery device using stepped fins according to claim 1, characterized in that: The outer wall of the heat pipe (3) is attached with a plurality of rows of n-level fins (4) arranged in a spiral staircase shape; the thickness of each level of fins (4) in a single row is W 2, and the spacing between the two-stage fins (4) is D 2; The fins of the single-row spiral staircase have the same total axial length as the heat pipe (3), both of which are n ( W 2+ D 2); The first stage fin (4) of the single-row spiral staircase fin is set at the heat flow inlet, denoted as A 1; the nth fin (3) is set at the heat flow outlet, denoted as A n .

4. The waste heat recovery device using stepped fins according to claim 3 is characterized in that: The fins (4) are evenly distributed at equal intervals along the radial direction on the outer wall of the heat pipe (3).

5. The waste heat recovery device using stepped fins according to claim 1, characterized in that: The geometric parameters of the P-type semiconductor and the N-type semiconductor in the same P / N-type semiconductor unit are the same.

6. The waste heat recovery device using stepped fins according to claim 5, characterized in that: The number of P-type semiconductors and the number of N-type semiconductors in the same P / N-type semiconductor unit are the same.

7. The waste heat recovery device using stepped fins according to claim 5, characterized in that: The central angles of the P-type semiconductor and the N-type semiconductor are , the central angle between adjacent P-type semiconductors and N-type semiconductors is ; The central angles of the conductive sheets connecting adjacent P-type semiconductors and N-type semiconductors are .

8. The waste heat recovery device using stepped fins according to claim 5, characterized in that: The width of each level of the P / N type semiconductor unit (1) is W 1. The distance between two adjacent levels is D 1, the length of the annular thermoelectric module (8) is M ( W 1+ D 1).

9. The waste heat recovery device using stepped fins according to claim 1, characterized in that: Both ends of the heat pipe (3) are hollow structures, which are used to reduce the back pressure of airflow loss along the pipe wall.

10. A method for using a waste heat recovery device using stepped fins, characterized in that: include: The waste heat recovery device is installed near a heat source from which waste heat needs to be recovered, and the heat source is started so that the heat is transferred to the stepped fins (4) through the heat pipe (3), and then evenly distributed throughout the waste heat recovery device; the annular thermoelectric module converts heat energy into electrical energy through the thermoelectric effect, and the converted electrical energy is conducted through the conductive sheet (2) for use or storage by external equipment; at the same time, the liquid cooling module starts to work, and removes excess heat through circulating coolant to prevent the waste heat recovery device from overheating and damage; according to the actual waste heat recovery efficiency and temperature control requirements, the working fluid flow in the heat pipe (3) and the cooling rate of the liquid cooling module are adjusted to achieve the best thermoelectric conversion efficiency and waste heat recovery effect.

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