Waste heat recovery device for diesel locomotive, waste heat recovery assembly and manufacturing method

Abstract

The invention relates to the technical field of waste heat recovery, and particularly discloses a waste heat recovery device for an internal combustion locomotive, a waste heat recovery assembly for the internal combustion locomotive and a manufacturing method of the waste heat recovery device for the internal combustion locomotive. An inner pipeline is arranged in the heat dissipation plate, an outer connector is arranged on the portion, on one side wall of the heat dissipation plate, of the inner pipeline, the heat pipe is connected with the outer connector, so that the inner pipeline and the heat pipe form a closed pulsating heat pipe connected end to end, a working medium is arranged in the pulsating heat pipe, and the heat pipe is configured to be exposed in the high-temperature tail gas flow channel. The heat dissipation plate is configured to be exposed out of the high-temperature tail gas flow channel; the thermoelectric power generation sheet is attached to the heat dissipation plate. Due to the fact that the internal pipeline is directly defined by the heat dissipation plates, the working medium entering the internal pipeline can directly transfer heat through the heat dissipation plates, the transfer path is shortened, heat resistance is reduced, and the heat conversion efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of waste heat recovery technology, and in particular to a waste heat recovery device for internal combustion engine vehicles, a waste heat recovery assembly for internal combustion engine vehicles, and a method for manufacturing the waste heat recovery device for internal combustion engine vehicles. Background Technology

[0002] Against the backdrop of global energy shortages, improving energy efficiency has become a crucial direction for the research and development of rail transit vehicles. With the continuous growth of global energy demand and the uncertainty of energy supply, energy security and sustainable development have become a focus of attention for all countries. As a vital component of transportation, rail transit accounts for a significant portion of energy consumption; therefore, improving its energy efficiency is of great importance for achieving the low-carbon transformation of the transportation industry.

[0003] The energy efficiency of a locomotive directly affects its operating costs. However, traditional internal combustion engines have low energy efficiency; only about 40%-50% of the energy generated by fuel combustion is converted into mechanical energy, while the remainder is lost as heat, with about 40% of this heat being emitted into the environment through exhaust gases. This inefficiency not only leads to significant energy waste but also increases operating costs. Therefore, improving the energy efficiency of internal combustion engines, especially by recovering waste heat from exhaust gases, has become a key issue in the development of rail transit locomotives.

[0004] In the field of waste heat recovery from internal combustion engine exhaust, the synergistic power generation technology of pulsating heat pipes and thermoelectric generators has attracted widespread attention due to its ability to improve exhaust back pressure. In existing technologies, pulsating heat pipe units typically employ a closed-loop structure with the hot end directly exposed to the high-temperature exhaust gas flow channel, transferring heat to the cold end through the phase change cycle of the working fluid. The cold end is embedded inside a metal heat sink, forming a heat conduction path with the thermoelectric generator attached to the surface of the heat sink. This design achieves rapid heat transfer through the highly efficient thermal conductivity of the pulsating heat pipe and utilizes the heat sink's heat equalization effect to provide stable low-temperature (cold end) boundary conditions for the thermoelectric generator, thereby creating a temperature difference across the thermoelectric material to drive power generation.

[0005] However, the existing structure has a significant heat transfer bottleneck: the nested assembly between the cold end of the pulsating heat pipe and the heat sink causes heat to have to pass through multiple interfaces (such as the heat pipe wall, contact interface, and heat sink substrate) before it can be transferred to the thermoelectric generator, which significantly increases thermal resistance; this long-path, multi-level heat transfer mode reduces thermoelectric conversion efficiency.

[0006] Therefore, there is an urgent need for waste heat recovery devices for internal combustion engine vehicles to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide a waste heat recovery device for internal combustion engine vehicles, a waste heat recovery assembly for internal combustion engine vehicles, and a method for manufacturing the waste heat recovery device for internal combustion engine vehicles, so as to solve the problem that the nested assembly between the cold end of the pulsating heat pipe and the heat sink plate causes heat to have to pass through multiple interfaces before it can be transferred to the thermoelectric generator, which significantly increases thermal resistance and reduces thermoelectric conversion efficiency.

[0008] On one hand, the present invention provides a waste heat recovery device for internal combustion engine vehicles, the waste heat recovery device for internal combustion engine vehicles comprising:

[0009] A pulsating heat pipe unit includes a heat sink and a heat pipe. The heat sink has an internal pipeline, and the internal pipeline has an external connector on one side wall of the heat sink. The heat pipe is connected to the external connector so that the internal pipeline and the heat pipe form a closed pulsating heat pipe with the ends connected. The pulsating heat pipe has a working fluid inside it. The heat pipe is configured to be exposed inside a high-temperature exhaust gas channel, and the heat sink is configured to be exposed outside the high-temperature exhaust gas channel.

[0010] A thermoelectric generator is attached to the heat sink.

[0011] As a preferred technical solution for waste heat recovery devices for internal combustion engine vehicles, the heat pipe is made of austenitic stainless steel or nickel-based alloy, and its chemical composition by weight percentage should meet the following requirements: chromium ≥ 16%, nickel ≥ 10%, molybdenum ≥ 2%, and carbon ≤ 0.03%.

[0012] As a preferred technical solution for a waste heat recovery device for internal combustion engine vehicles, the outer surface roughness Ra of the heat pipe is ≤0.1μm.

[0013] As a preferred technical solution for waste heat recovery devices for internal combustion engine vehicles, it also includes a piezoelectric ceramic vibrator, which is attached to the heat sink.

[0014] As a preferred technical solution for a waste heat recovery device for internal combustion locomotives, it also includes an installation pipe, the peripheral wall of which is provided with an installation hole, the pulsating heat pipe unit passing through the installation hole, the heat pipe being located inside the installation pipe, the heat dissipation plate passing through the installation hole and sealing the installation hole, and the heat dissipation plate being fixedly connected to the installation pipe.

[0015] As a preferred technical solution for a waste heat recovery device for internal combustion engine vehicles, the side wall of the heat sink connected to the heat pipe is an arc-shaped wall, and the diameter of the arc-shaped wall is the same as the inner wall diameter of the mounting pipe.

[0016] As a preferred technical solution for a waste heat recovery device for internal combustion engine vehicles, the internal pipeline includes multiple internal U-shaped tubes, and the two free ends of each internal U-shaped tube form two external connectors on one side wall of the heat sink. Multiple heat pipes are provided, and the two ends of the multiple heat pipes are respectively connected to the external connectors.

[0017] The outer diameter of the heat pipe is d, the length of the heat pipe is L, the inner diameter of the mounting tube is D, and n is the number of heat pipes. .

[0018] On the other hand, the present invention provides a waste heat recovery assembly for internal combustion engine vehicles, including a first single flange pipe, a second single flange pipe, and at least one waste heat recovery device for internal combustion engine vehicles according to any of the above embodiments, wherein the first single flange pipe, at least one of the waste heat recovery devices for internal combustion engine vehicles, and the second single flange pipe are connected in series.

[0019] In another aspect, the present invention provides a method for manufacturing a waste heat recovery device for internal combustion engine vehicles, used to manufacture the waste heat recovery device for internal combustion engine vehicles in any of the above-mentioned embodiments, including a heat pipe outer surface treatment method, comprising:

[0020] The outer surface of the heat pipe is subjected to alkaline solution ultrasonic degreasing and acid activation;

[0021] The outer surface of the heat pipe is electropolished for 8–12 minutes in a phosphoric acid-sulfuric acid-based electrolyte at 65±5℃ and a current density of 25–35 A / dm² to achieve a roughness of Ra≤0.1μm.

[0022] The heat pipe is immersed in a nitric acid solution at 50–60°C for 20–30 minutes to form a dense passivation film.

[0023] As a preferred technical solution for the manufacturing method of a waste heat recovery device for internal combustion engine vehicles, the waste heat recovery device for internal combustion engine vehicles further includes a piezoelectric ceramic vibrator, which is attached to the heat dissipation plate;

[0024] It also includes piezoelectric ceramic resonator installation methods, including:

[0025] The heat sink is cleaned, polished, and baked in an inert gas environment to ensure that the surface moisture content is ≤0.1% and the surface roughness Ra is ≤0.1μm.

[0026] The bonding surface of the piezoelectric ceramic oscillator is subjected to deoxidation and activation treatment;

[0027] The piezoelectric ceramic oscillator is attached to the surface of the heat sink using a high-temperature resistant, high-bonding-strength epoxy resin adhesive, and then cured by step-by-step heating at 80°C and 0.1–0.2 MPa.

[0028] The bonding area between the piezoelectric ceramic oscillator and the heat sink is encapsulated with protective silicone.

[0029] This invention has at least the following beneficial effects:

[0030] This waste heat recovery device for diesel locomotives includes a pulsating heat pipe unit and a thermoelectric generator. The pulsating heat pipe unit comprises a heat sink and heat pipes. Internal piping is installed within the heat sink, and external connectors are located on one side wall of the heat sink. The heat pipes connect to these external connectors, forming a closed pulsating heat pipe system. A working fluid is placed within the pulsating heat pipes, which are positioned to be exposed within the high-temperature exhaust gas passage. The heat sink is positioned to be exposed outside the high-temperature exhaust gas passage. The thermoelectric generator is attached to the heat sink. When the waste heat recovery device is operating, the heat pipes absorb heat, causing the working fluid within them to absorb heat and vaporize. The vaporized working fluid moves into the internal piping within the heat sink, transferring heat to the heat sink. The thermoelectric generator then generates electricity under the influence of the heat on the heat sink. Because the internal piping is directly enclosed by the heat sink, the working fluid entering the internal piping can directly transfer heat through the heat sink, thus shortening the heat transfer path, reducing thermal resistance, and improving heat conversion efficiency. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the installation of the waste heat recovery assembly for internal combustion engine vehicles in an embodiment of the present invention. Figure 1 ;

[0032] Figure 2 This is a schematic diagram of the waste heat recovery device for internal combustion engine vehicles in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the pulsating heat pipe unit of the waste heat recovery device for internal combustion engine vehicles in an embodiment of the present invention;

[0034] Figure 4 This is an exploded schematic diagram of the pulsating heat pipe unit of the waste heat recovery device for internal combustion engine vehicles in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of the installation of the waste heat recovery assembly for internal combustion engine vehicles in an embodiment of the present invention. Figure 2 ;

[0036] Figure 6 This is a schematic diagram of the installation of the waste heat recovery assembly for internal combustion engine vehicles in an embodiment of the present invention. Figure 3 ;

[0037] Figure 7 This is a schematic diagram of the installation of the waste heat recovery assembly for internal combustion engine vehicles (parallel pipe cluster) in an embodiment of the present invention.

[0038] Figure 8 This is a schematic diagram of the installation of the waste heat recovery assembly for internal combustion engine vehicles (forklift pipe cluster) in an embodiment of the present invention.

[0039] Figure 9 This is a flowchart of the heat pipe outer surface treatment method in the manufacturing method of the waste heat recovery device for internal combustion engine vehicles in an embodiment of the present invention;

[0040] Figure 10 This is a flowchart of the piezoelectric ceramic vibrator installation method in the manufacturing method of the waste heat recovery device for internal combustion engine vehicles in an embodiment of the present invention.

[0041] In the picture:

[0042] 1. Pulsating heat pipe unit; 11. Heat sink; 111. Internal piping; 1111. First flow channel; 1112. Second flow channel; 112. Arc-shaped wall; 113. First plate; 114. Second plate; 12. Heat pipe;

[0043] 2. Thermoelectric generator; 3. Piezoelectric ceramic resonator; 4. Mounting pipe; 41. Flange;

[0044] 51. First single flange pipe; 52. Second single flange pipe; 53. Double flange pipe. Detailed Implementation

[0045] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions. Furthermore, "above," "on top of," and "over" the first feature in relation to the second feature includes the first feature directly above and diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" the first feature in relation to the second feature includes the first feature directly below and diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0047] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0048] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0049] like Figures 1 to 8 As shown, this embodiment provides a waste heat recovery device for internal combustion locomotives. The waste heat recovery device for internal combustion locomotives includes a pulsating heat pipe unit 1 and a thermoelectric generator 2. The pulsating heat pipe unit 1 includes a heat sink 11 and a heat pipe 12. An internal pipe 111 is provided inside the heat sink 11. An external connector is provided on one side wall of the internal pipe 111. The heat pipe 12 is connected to the external connector so that the internal pipe 111 and the heat pipe 12 form a closed pulsating heat pipe with the ends connected. A working fluid is provided inside the pulsating heat pipe. The heat pipe 12 is configured to be exposed inside the high-temperature exhaust gas passage, and the heat sink 11 is configured to be exposed outside the high-temperature exhaust gas passage. The thermoelectric generator 2 is attached to the heat sink 11. When the waste heat recovery device for this diesel locomotive is working, the heat pipe 12 absorbs heat, causing the working fluid inside the heat pipe 12 to absorb heat and vaporize. The vaporized working fluid moves to the internal pipes 111 within the heat sink 11, thereby transferring heat to the heat sink 11. The thermoelectric generator 2 generates electricity under the action of the heat on the heat sink 11. Since the internal pipes 111 are directly surrounded by the heat sink 11, the working fluid entering the internal pipes 111 can directly transfer heat through the heat sink 11, thus shortening the transfer path, reducing thermal resistance, and improving the heat conversion efficiency.

[0050] Optionally, multiple thermoelectric generators 2 are provided, and the array of multiple thermoelectric generators 2 is closely attached to the heat sink 11. The thermoelectric generators 2 and the heat sink 11 are connected by high-temperature resistant thermally conductive grease. The high-temperature resistant thermally conductive grease has good thermal conductivity and high-temperature resistance, which can effectively reduce contact thermal resistance and improve heat transfer efficiency. After the heat pipe 12 absorbs the heat of the exhaust gas, the heat is transferred from the heat pipe 12 to the heat sink 11, providing a high-temperature side for the thermoelectric generator 2. At the same time, air convection cools the other side of the thermoelectric generator 2, thereby creating a temperature difference between the two sides of the thermoelectric generator 2. According to the Seebeck effect, this temperature difference drives the thermoelectric generator 2 to generate electricity, realizing the conversion of waste heat into electrical energy. In the thermoelectric generator 2, multiple thermoelectric generators 2 are connected in series. Series connection can increase the output voltage and improve the power generation efficiency. By reasonably designing the number and layout of the thermoelectric generators 2 in series, the output voltage and power can be adjusted according to actual needs to meet the needs of different electrical equipment.

[0051] Diesel engine exhaust temperatures typically range from 100℃ to 700℃. For the same model of diesel engine, the exhaust temperature can vary significantly depending on the installation location of the waste heat recovery device in the locomotive. To fully utilize the heat energy in the diesel engine exhaust and achieve waste heat recovery across all operating conditions, the pulsating heat pipe in the waste heat recovery device can select a suitable working fluid based on the exhaust temperature at its location. Different working fluids exhibit different heat transfer properties under different temperature conditions. By appropriately selecting the working fluid, the pulsating heat pipe can operate efficiently under various exhaust temperature conditions, transferring and utilizing the heat energy in the exhaust. Therefore, the pulsating heat pipe in the waste heat recovery device for locomotives can select the working fluid based on temperature to meet the waste heat recovery requirements across the entire operating range. Optionally, when the exhaust temperature is below 200℃, commonly used working fluids include water, ethanol, and acetone. In the range of 200℃ to 500℃, commonly used working fluids are biphenyl, diphenyl ether, or a mixture of both. When the exhaust gas temperature is above 500℃, the commonly used working fluids are sodium, potassium, sodium-potassium alloy, rubidium, and cesium.

[0052] Optionally, the working fluid filling rate of the pulsating heat pipe is 30% to 80%, which can effectively prevent it from burning dry while maintaining good heat transfer performance.

[0053] Alternatively, the heat sink 11 can be manufactured by casting or additive manufacturing, which makes the heat sink 11 a one-piece molded part, resulting in better sealing of the internal pipes 111 and less leakage.

[0054] In other embodiments, the heat sink 11 may also include a first plate 113 and a second plate 114. The first plate 113 is provided with a first flow channel 1111, and the second plate 114 is provided with a second flow channel 1112. The first plate 113 and the second plate 114 are stacked and fixed to each other, so that the first flow channel 1111 and the second flow channel 1112 form an internal pipe 111. When the internal pipe 111 is blocked, the first plate 113 and the second plate 114 can be separated, which is conducive to cleaning and unblocking the internal pipe 111.

[0055] Optionally, multiple thermoelectric generators 2 can be provided, and multiple thermoelectric generators 2 can be arranged in an array on the heat sink 11.

[0056] Specifically, the thermoelectric generator 2 is existing technology and will not be described in detail here.

[0057] Because heat pipe 12 is exposed to high-temperature flue gas containing corrosive components for extended periods, it is prone to particle adhesion, bonding, sintering, and accelerated corrosion, thereby reducing device performance. To address this issue, heat pipe 12 can optionally be made of austenitic stainless steel or a nickel-based alloy, with a chemical composition by weight percentage meeting the following requirements: chromium ≥ 16%, nickel ≥ 10%, molybdenum ≥ 2%, and carbon ≤ 0.03%. In this embodiment, the rationale for selecting the material of heat pipe 12 is based on corrosion resistance design: high chromium (Cr ≥ 16%) content is crucial for ensuring the material resists high-temperature oxidation and sulfuric acid dew point corrosion in diesel engine exhaust environments, as it can form a dense Cr2O3 passivation film on the surface. The addition of molybdenum (Mo ≥ 2%) aims to enhance resistance to pitting and crevice corrosion to address potential halide ions in the exhaust gas. The ultra-low carbon (C ≤ 0.03%) requirement prevents carbide precipitation at grain boundaries during welding and high-temperature service, thereby avoiding intergranular corrosion and ensuring structural integrity and long service life. Working fluid compatibility assurance: The high nickel content (Ni≥10%) not only stabilizes the austenitic matrix, but more importantly, it significantly improves the chemical compatibility of the material with highly reactive working fluids (especially sodium-potassium liquid metals), effectively inhibiting the corrosive dissolution and embrittlement of the heat pipe 12 wall by the working fluid. Simultaneously, this composition system exhibits inertness to conventional working fluids such as water and ethanol, ensuring the versatility of material selection.

[0058] Optionally, the surface roughness Ra of the heat pipe 12 is ≤0.1μm. In this embodiment, to achieve long-term anti-fouling and anti-corrosion performance of the heat pipe 12 in the high-temperature and high-pollution environment of exhaust gas, its outer surface in contact with the flue gas needs to be precisely optimized. Specifically, the outer surface of the heat pipe 12 must be treated to achieve a mirror-like finish, and its arithmetic mean roughness Ra value is not greater than 0.1μm. The preferred range is 0.05 to 0.08μm. The core purpose of this indicator is to physically deprive carbon soot particles and tar-like substances of their attachment anchor points by greatly reducing the microscopic unevenness of the surface, thereby inhibiting the formation of fouling at the source.

[0059] Optionally, the waste heat recovery device for internal combustion locomotives also includes a piezoelectric ceramic vibrator 3, which is attached to the heat sink 11. In this embodiment, to solve the problem of exhaust gas impurities adhering to the surface of the heat sink 11, a piezoelectric ceramic vibrator 3 is integrated on the surface of the heat sink 11 to achieve active vibration cleaning. The piezoelectric ceramic vibrator 3 is attached to the surface of the heat sink 11 in the form of a small sheet. It generates high-frequency micro-vibration through an external driving signal, causing the dust, carbon residue, and corrosive particles adhering to the surface of the heat sink 11 to loosen and be carried away by the cooling airflow.

[0060] Optionally, during the operation or shutdown of the internal combustion engine, an AC drive signal is applied to the piezoelectric ceramic vibrator 3 via an external drive controller, causing it to vibrate at a high frequency of 20–50 kHz and an amplitude of 0.5–5 μm. Each cleaning cycle lasts 5–15 minutes, and the cleaning frequency is adjusted according to the degree of exhaust gas pollution. At least one cleaning is performed after the internal combustion engine has accumulated 40–60 hours of operation. The cleaning effect is evaluated by measuring the heat transfer performance recovery rate of the pulsating heat pipe; the recovery rate should be no less than 90% of the initial heat transfer performance, thus achieving online active descaling and performance maintenance without disassembling the cooling module. This technical solution effectively improves the long-term reliability of the waste heat recovery device for internal combustion engines under complex operating conditions and reduces the risk of heat transfer performance degradation and corrosion caused by the adhesion of impurities in the exhaust gas.

[0061] To address the problem of impurities in exhaust gas, this invention proposes a comprehensive solution. Through a triple protection strategy of surface modification, material optimization, and active scale inhibition, it effectively solves the problems of impurity adhesion and corrosion faced by traditional waste heat recovery devices. First, by modifying the surface of the heat pipe 12, the roughness of the heat transfer surface is controlled to a mirror-like level of Ra≤0.1μm, fundamentally reducing the adhesion points of impurities. Second, special stainless steels (such as 310S, 316L) or nickel-based alloys with high chromium-nickel content are selected as the material for the pulsating heat pipe. These materials have excellent resistance to sulfide corrosion and high-temperature stability, effectively resisting the corrosive erosion of the exhaust gas environment. Furthermore, the pulsating heat pipe is innovatively designed as a tube-plate coupled structure, with a tubular structure for the heating section and a plate structure for the cooling section. The heat pipe 12 reduces the flow resistance of the exhaust gas, and piezoelectric ceramic oscillators 3 can be attached to the surface of the heat dissipation plate 11, increasing the heat dissipation area. The piezoelectric ceramic oscillator 3 actively disrupts the adhesive boundary layer attached to the wall by applying high-frequency micro-amplitude vibrations of 50-200Hz, continuously suppressing particulate matter deposition, realizing the online self-cleaning function of the device, and maintaining the advantages of strong heat dissipation capacity and strong structural applicability in the cooling section.

[0062] In summary, waste heat recovery technology from internal combustion engine exhaust plays a crucial role in improving the energy efficiency of rail transit locomotives. However, existing technologies still have significant shortcomings in areas such as exhaust back pressure control, heat exchange efficiency improvement, and anti-fouling capabilities. Especially in the high-temperature, high-corrosion, and high-particulate-concentration environment of the exhaust flue, heat transfer structures are prone to fouling accumulation and corrosion failure, becoming a key bottleneck limiting the stable operation of the system. The high-fouling-resistant pulsating heat pipe technology proposed in this invention, through structural optimization, efficient heat transfer design, combined with surface modification, selection of corrosion-resistant materials, and piezoelectric ceramic active defouling technology, can significantly improve waste heat utilization efficiency and operational reliability while ensuring low exhaust back pressure, providing strong technical support for achieving the energy conservation and emission reduction goals of rail transit locomotives.

[0063] Optionally, the waste heat recovery device for internal combustion locomotives further includes an installation pipe 4. The peripheral wall of the installation pipe 4 has an installation hole. A pulsating heat pipe unit 1 passes through the installation hole, a heat pipe 12 is located inside the installation pipe 4, and a heat dissipation plate 11 passes through and seals the installation hole. The heat dissipation plate 11 is fixedly connected to the installation pipe 4. In this embodiment, the installation pipe 4 can be connected to a high-temperature exhaust gas passage so that high-temperature exhaust gas flows through the installation pipe 4.

[0064] Optionally, flanges 41 are provided at both ends of the mounting pipe 4 to facilitate connection of the mounting pipe 4 to the high-temperature exhaust gas passage, or to connect the mounting pipe 4 to the mounting pipe 4 of other internal combustion engine waste heat recovery devices.

[0065] Optionally, due to the anti-gravity operation characteristic of the pulsating heat pipe, a single waste heat recovery device for internal combustion locomotives can be equipped with multiple pulsating heat pipe units 1. Multiple mounting holes are spaced around the mounting pipe 4 circumferentially, with each mounting hole corresponding to one of the multiple pulsating heat pipe units 1. This flexible installation angle allows the waste heat recovery device for internal combustion locomotives to adapt to different installation environments and piping layout requirements.

[0066] For example, two pulsating heat pipe units 1 are symmetrically mounted on the mounting tube 4.

[0067] Optionally, the side wall of the heat sink 11 connected to the heat pipe 12 is an arc-shaped wall 112, the diameter of which is the same as the inner diameter of the mounting pipe 4. In this embodiment, the arc-shaped wall 112 is completely fitted to the inner wall of the mounting pipe 4, and the two are connected by welding. On the one hand, the design of the arc-shaped wall 112 can increase the contact area between the heat sink 11 and the mounting pipe 4, improving heat transfer efficiency; on the other hand, the welding connection can ensure the stability of the connection, preventing loosening or leakage during long-term operation, thereby improving the overall stability and heat transfer capacity of the device. The mounting pipe 4 is a circular pipe structure, and its material and inner diameter are the same as those of the diesel engine exhaust pipe, enabling the waste heat recovery device for internal combustion engine vehicles to be seamlessly connected to the diesel engine exhaust pipe, reducing the impact on the original exhaust system and improving the system's compatibility.

[0068] Optionally, the internal piping 111 includes multiple internal U-shaped tubes, each internal U-shaped tube having two external connectors formed at its two free ends on one side wall of the heat sink 11. Multiple heat pipes 12 are provided, with both ends of each heat pipe 12 connected to the external connectors. In this embodiment, the multiple internal U-shaped tubes and multiple heat pipes 12 are connected in a serpentine arrangement, forming a pulsating heat pipe system.

[0069] The outer diameter of heat pipe 12 is d, the length of heat pipe 12 is L, the inner diameter of mounting pipe 4 is D, and n is the number of heat pipes 12. In this embodiment, the outer diameter d of the heat pipe 12 and the number n of the heat pipe 12 can be determined based on the inner diameter D of the mounting tube 4.

[0070] Optionally, the inner diameter of the pulsating heat pipe is r, and the range of values ​​for r is: ,in, The surface tension of the working fluid, For the working fluid density, For gas density, Let r be the acceleration due to gravity. In this embodiment, the inner diameter of the pulsating heat pipe can be obtained as r using the above formula.

[0071] Optionally, the heat pipe 12 has a wall thickness of 1 mm, and the heat sink 11 is 2 mm thicker than the internal pipe 111. The tubular structure of the heat pipe 12 can greatly reduce its frontal area, significantly reducing the impact on exhaust gas flow after the installation of the waste heat recovery device for internal combustion locomotives. The heat sink 11 can make the cooling section temperature more uniform, increase the cooling area, and provide space for attaching the piezoelectric ceramic oscillator 3 and the thermoelectric generator 2.

[0072] Depending on the specific application, the layout and environment of diesel engine exhaust pipes in internal combustion locomotives are highly complex. The modular design of waste heat recovery devices for internal combustion locomotives significantly improves their flexibility and applicability. To adapt to complex working environments, this embodiment also provides a waste heat recovery assembly for internal combustion locomotives, such as... Figure 5 As shown, the waste heat recovery assembly for internal combustion locomotives includes a first single-flange pipe 51, a waste heat recovery device for internal combustion locomotives, and a second single-flange pipe 52. One side of the first single-flange pipe 51 is an exhaust gas inlet, and the other side is connected to one end of an installation pipe 4 via a flange. The other end of the installation pipe 4 is connected to the second single-flange pipe 52 via a flange. The function of the second single-flange pipe 51 is to discharge the exhaust gas passing through the waste heat recovery device for internal combustion locomotives. Through this specific connection method, the exhaust gas enters from the exhaust gas inlet of the first single-flange pipe 51, and when it passes through the waste heat recovery device for internal combustion locomotives, its heat energy is recovered and utilized, thus achieving waste heat recovery.

[0073] Optionally, to improve energy utilization efficiency and increase heat transfer efficiency, such as Figure 6 As shown, the waste heat recovery assembly for internal combustion locomotives includes two waste heat recovery devices. One side of the first single-flange pipe 51 is the exhaust gas inlet, and the other side is connected via a flange to the mounting pipe 4 of the first waste heat recovery device. The other side of the mounting pipe 4 of the first waste heat recovery device is connected via a flange to one end of the mounting pipe 4 of the second waste heat recovery device. The other side of the mounting pipe 4 of the second waste heat recovery device is connected via a flange to the second single-flange pipe 52. The function of the second single-flange pipe 52 is to discharge the exhaust gas passing through the waste heat recovery devices. Through this specific connection method, the exhaust gas enters from the exhaust gas inlet of the first single-flange pipe 51, and its heat energy is recovered and utilized as it passes through the first and second waste heat recovery devices. Optionally, a double-flange pipe 53 of different lengths can be added between the two waste heat recovery devices.

[0074] Optionally, to further improve energy utilization efficiency and increase heat transfer efficiency, where space and actual operating conditions permit, such as Figure 1 As shown, the waste heat recovery assembly for internal combustion locomotives can provide multiple waste heat recovery devices for internal combustion locomotives. The mounting pipes 4 of the multiple waste heat recovery devices for internal combustion locomotives are connected in series. The first single flange pipe 51 and the second single flange pipe 52 are respectively connected to the two ends of the multiple waste heat recovery devices for internal combustion locomotives connected in series. Optionally, according to actual needs, double flange pipes 53 of different lengths can be added between any two waste heat recovery devices for internal combustion locomotives.

[0075] Optionally, after arranging multiple waste heat recovery devices for internal combustion locomotives in the flue, the first step is to determine whether the pulsating heat pipes are in-line or out-of-line configurations. In-line configurations offer advantages such as low flow resistance (pressure drop 30%–60% lower than out-of-line configurations) and a regular structure that facilitates maintenance. However, their disadvantage is lower heat transfer efficiency (weak stagnation at the tail end results in a heat transfer coefficient 10%–30% lower than out-of-line configurations). Out-of-line configurations offer advantages such as high heat transfer efficiency (alternating contraction and expansion of the flow channels enhances turbulence, resulting in a heat transfer coefficient 10%–30% higher than in-line configurations), excellent performance at high Reynolds numbers, and uniform temperature distribution. However, their disadvantages include high flow resistance and sensitivity to pipe spacing design; if the transverse or longitudinal pipe spacing is large, the heat transfer advantage may disappear.

[0076] like Figure 7 As shown, for the in-line tube bundle, the exhaust gas flow velocity is:

[0077]

[0078] In the formula: For the speed of the exhaust gas, Let be the volumetric flow rate of the exhaust gas, and let D be the inner diameter of the mounting pipe 4. Then the maximum velocity of the exhaust gas is:

[0079]

[0080] In the formula: Ls is the maximum velocity of the exhaust gas, Ls is the longitudinal tube spacing, and d is the outer diameter of heat pipe 12.

[0081] The next step is to calculate the maximum Reynolds number. According to the definition of the maximum Reynolds number, its expression is:

[0082]

[0083] In the formula: For the maximum Reynolds number, The kinematic viscosity of the exhaust gas.

[0084]

[0085]

[0086] In the formula, Here, C1 and m1 are Nusselt numbers, and C1 and m1 are constants. For the Prandtl number of exhaust gases, The Prandtl number is calculated based on the tube wall temperature. The thermal conductivity of the exhaust gas, This is a correction factor for sequential arrangement.

[0087] when When, C1=0.50, m1=0.50; when When, C1=0.26, m1=0.65; when At that time, C1=0.023, m1=0.80.

[0088] When the number of pipe rows is greater than or equal to 16 =1; When the number of pipe rows is less than 16: the number of rows is 1. =0.70; when the number of rows is 2, =0.80; when the number of rows is 3, =0.86; when the number of rows is 4, =0.90; when the number of rows is 5, =0.92; when the number of rows is 7, =0.95; when the number of rows is 10, =0.97; when the number of rows is 13, =0.98. When the number of pipe rows is between these values, the correction factor is estimated using linear interpolation.

[0089] The Nusselt number of the in-line tube cluster is obtained using the above calculation method.

[0090] like Figure 8As shown, for staggered tube clusters, the maximum Reynolds number is calculated in the same way as for inline tube clusters. Further calculation of the Nusselt number follows:

[0091] Further calculation of the Nusel number:

[0092]

[0093] In the formula, C2 and m2 are constants. This is a correction factor for sequential arrangement.

[0094] when When, C2=0.90, m2=0.40; when When, C2=0.40, m2=0.60; when At that time, C2=0.031, m2=0.80.

[0095] When the number of pipe rows is greater than or equal to 16 =1; When the number of pipe rows is less than 16: the number of rows is 1. =0.64; when the number of rows is 2, =0.76; when the number of rows is 3, =0.84; when the number of rows is 4, =0.89; when the number of rows is 5, =0.92; when the number of rows is 7, =0.95; when the number of rows is 10, =0.97; when the number of rows is 13, =0.98. When the number of pipe rows is between these values, the correction factor is estimated using linear interpolation.

[0096] Average convective heat transfer coefficient of heat pipe 12 The following formula can be used to obtain:

[0097]

[0098] The heat exchange capacity of heat pipe 12 can be calculated using the following formula:

[0099]

[0100] In the formula, For the number of modules, To exchange heat, This refers to the temperature difference between the exhaust gas and the external environment.

[0101] Another important factor to consider when selecting between in-line and staggered tube clusters is the pressure drop of the exhaust gas as it passes through heat pipe 12. The pressure drop can be calculated using the following formula:

[0102]

[0103] In the formula, For exhaust gas density, As the friction factor, As a correction factor, and All of these were obtained by looking up a table.

[0104] Based on actual engineering requirements and combined with the calculated pressure drop and heat exchange results, the tube bundle arrangement of multiple waste heat recovery devices for internal combustion locomotives is determined. Furthermore, without adding complex sensors, multiple waste heat recovery devices for internal combustion locomotives are designed and installed.

[0105] This embodiment also provides a method for manufacturing a waste heat recovery device for internal combustion engine vehicles, used to manufacture the waste heat recovery device for internal combustion engine vehicles in the above-described scheme. The method for manufacturing the waste heat recovery device for internal combustion engine vehicles includes a heat pipe outer surface treatment method, such as... Figure 9 As shown, it includes:

[0106] A10: The outer surface of heat pipe 12 is subjected to ultrasonic degreasing with alkaline solution and acid activation.

[0107] In this step, the purpose of first performing alkaline ultrasonic degreasing on the outer surface of heat pipe 12 is to remove organic contaminants such as grease, oil, cutting fluid, and rust inhibitors from the metal surface. Then, acid activation is performed to remove oxides (such as iron oxide and aluminum oxide), rust layers, or passivation films from the metal surface, exposing a clean, active metal surface. This provides an ideal surface condition for subsequent processes.

[0108] A20: Electropolishing of the outer surface of the heat pipe 12 for 8–12 minutes in a phosphoric acid-sulfuric acid-based electrolyte at 65±5℃ and a current density of 25–35 A / dm², so that the roughness Ra≤0.1μm.

[0109] In this step, the combination of process parameters can reduce the arithmetic mean deviation Ra of the surface profile from the initial 0.8-1.6 μm to below 0.1 μm, while the surface peak-to-valley difference (Rz) can be controlled within 0.5 μm, thus meeting the surface quality requirements of precision heat transfer elements.

[0110] A30: Immerse heat pipe 12 in nitric acid solution at 50–60°C for 20–30 minutes to form a dense passivation film.

[0111] In this step, the passivation film can protect the heat pipe 12, thereby effectively improving the corrosiveness of the exhaust gas to the heat pipe 12.

[0112] like Figure 10 As shown, optionally, the manufacturing method of the waste heat recovery device for internal combustion locomotives also includes a piezoelectric ceramic oscillator mounting method, including:

[0113] B10: The heat sink 11 is cleaned, polished, and baked in an inert gas environment to make the surface moisture content ≤0.1% and the surface roughness Ra ≤0.1μm.

[0114] In this step, surface contaminants and oxide layers are removed by cleaning, and an ultra-smooth surface (Ra≤0.1μm) is achieved by polishing to enhance interfacial contact. Inert gas baking completely removes moisture (≤0.1%) and prevents secondary oxidation, providing a clean, flat, and dry substrate surface for subsequent bonding.

[0115] B20: Deoxidize and activate the bonding surface of the piezoelectric ceramic oscillator 3.

[0116] In this step, the oxide layer and impurities on the bonding surface of the piezoelectric ceramic oscillator 3 are removed, and the surface activity and wettability are improved by chemical or physical methods to enhance its chemical bonding ability with epoxy resin.

[0117] B30: The piezoelectric ceramic oscillator 3 is attached to the surface of the heat sink 11 using a high-temperature resistant, high-adhesion epoxy resin adhesive, and then cured by step-by-step heating at 80°C and 0.1–0.2 MPa.

[0118] In this step, high-bonding-strength, heat-resistant epoxy resin is used to achieve a reliable connection between the heat sink 11 and the piezoelectric ceramic oscillator 3. Stepwise heating and pressurization curing optimizes the flow and cross-linking of the adhesive layer, reduces bubbles and internal stress, and forms a uniform and dense bonding interface.

[0119] B40: Protective silicone sealant is applied to the bonding area between the piezoelectric ceramic vibrator 3 and the heat sink 11.

[0120] In this step, silicone sealant is used to isolate external moisture and corrosive media and buffer thermal stress, protecting the bonding area from environmental damage. It also absorbs mechanical stress caused by vibration and thermal expansion differences, extending the service life of the overall structure.

[0121] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A waste heat recovery device for internal combustion locomotives, characterized in that, include: The pulsating heat pipe unit (1) includes a heat sink (11) and a heat pipe (12). The heat sink (11) is provided with an internal pipe (111). The internal pipe (111) is provided with an external connector on one side wall of the heat sink (11). The heat pipe (12) is connected to the external connector so that the internal pipe (111) and the heat pipe (12) form a closed pulsating heat pipe with the ends connected. The pulsating heat pipe is provided with a working fluid. The heat pipe (12) is configured to be exposed in the high-temperature exhaust gas channel. The heat sink (11) is configured to be exposed outside the high-temperature exhaust gas channel. Thermoelectric generator (2) is attached to the heat sink.

2. The waste heat recovery device for internal combustion locomotives according to claim 1, characterized in that, The heat pipe (12) is made of austenitic stainless steel or nickel-based alloy, and its chemical composition by weight percentage should meet the following requirements: chromium ≥ 16%, nickel ≥ 10%, molybdenum ≥ 2%, and carbon ≤ 0.03%.

3. The waste heat recovery device for internal combustion locomotives according to claim 1, characterized in that, The surface roughness Ra of the outer tube of the heat pipe (12) is ≤0.1μm.

4. The waste heat recovery device for internal combustion locomotives according to claim 1, characterized in that, It also includes a piezoelectric ceramic oscillator (3), which is attached to the heat sink (11).

5. The waste heat recovery device for internal combustion locomotives according to claim 1, characterized in that, It also includes an installation tube (4), the peripheral wall of which is provided with an installation hole, the pulsating heat pipe unit (1) passes through the installation hole, the heat pipe (12) is located inside the installation tube (4), the heat sink (11) passes through the installation hole and closes the installation hole, and the heat sink (11) is fixedly connected to the installation tube (4).

6. The waste heat recovery device for internal combustion locomotives according to claim 5, characterized in that, The heat sink (11) has an arc-shaped wall (112) on one side connected to the heat pipe (12), and the diameter of the arc-shaped wall (112) is the same as the inner wall diameter of the mounting pipe (4).

7. The waste heat recovery device for internal combustion locomotives according to claim 5, characterized in that, The internal pipeline (111) includes multiple internal U-shaped tubes. The two free ends of each internal U-shaped tube form two external connectors on one side wall of the heat sink (11). Multiple heat pipes (12) are provided, and the two ends of the multiple heat pipes (12) are respectively connected to the external connectors. The outer diameter of the heat pipe (12) is d, the length of the heat pipe (12) is L, the inner diameter of the mounting tube (4) is D, and n is the number of heat pipes (12). .

8. A waste heat recovery assembly for internal combustion engine vehicles, characterized in that, It includes a first single flange pipe (51), a second single flange pipe (52), and at least one waste heat recovery device for internal combustion locomotives as described in any one of claims 1-7, wherein the first single flange pipe (51), at least one of the waste heat recovery devices for internal combustion locomotives, and the second single flange pipe (53) are connected in series.

9. A method for manufacturing a waste heat recovery device for internal combustion locomotives, characterized in that, A method for manufacturing a waste heat recovery device for internal combustion engine vehicles according to any one of claims 1-7, comprising: a heat pipe outer surface treatment method, including: The outer surface of the heat pipe (12) is subjected to ultrasonic degreasing in an alkaline solution and acid activation. The outer surface of the heat pipe (12) was electropolished for 8–12 minutes in a phosphoric acid-sulfuric acid-based electrolyte at 65±5℃ and a current density of 25–35 A / dm² to achieve a roughness of Ra≤0.1μm. The heat pipe (12) is immersed in a nitric acid solution at 50–60°C for 20–30 minutes to form a dense passivation film.

10. The method for manufacturing the waste heat recovery device for internal combustion locomotives according to claim 9, characterized in that, The waste heat recovery device for internal combustion engine vehicles also includes a piezoelectric ceramic vibrator (3), which is attached to the heat sink (11). It also includes piezoelectric ceramic resonator installation methods, including: The heat sink (11) is cleaned, polished and baked in an inert gas environment to make the surface moisture content ≤0.1% and the surface roughness Ra≤0.1μm; The bonding surface of the piezoelectric ceramic oscillator (3) is subjected to deoxidation and activation treatment; The piezoelectric ceramic oscillator (3) was attached to the surface of the heat sink (11) using a high-temperature resistant and high-adhesion epoxy resin adhesive, and then cured by step-by-step heating at 80°C and 0.1–0.2 MPa. The bonding area between the piezoelectric ceramic oscillator (3) and the heat sink (11) is encapsulated with protective silicone.

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