High temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires

Abstract

The application relates to a high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires, belonging to the technical field of thermoelectricity, and particularly relates to high-temperature waste heat recovery in industrial production processes. The system solves the problem that the existing silicon germanium nanowires still have limitations in the reduction of thermal conductivity and are difficult to meet the demand of efficient thermoelectric conversion. The system comprises a thermoelectric conversion module, a cold source area and an electric energy output module. The thermoelectric material layer is used for responding to the temperature difference between the heat source area and the cold source area, generating a thermoelectric effect to generate an electric current. The high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires is suitable for high-temperature waste heat recovery in industrial production processes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermoelectricity, in particular to high-temperature waste heat recovery in industrial production processes. BACKGROUND

[0002] In industrial production processes, a large amount of high-temperature waste heat is directly discharged, not only causing energy waste, but also having adverse effects on the environment. According to statistics, high-temperature waste heat in the industrial field accounts for 20%-50% of total energy consumption, and if it can be effectively recovered and utilized, it will significantly improve energy utilization efficiency and reduce carbon emissions.

[0003] Thermoelectric conversion technology, as a technology for directly converting heat energy into electrical energy, has broad application prospects in waste heat recovery due to its simple structure, no moving parts, and high reliability. However, the thermal conductivity of traditional thermoelectric materials is relatively high, and the thermoelectric figure of merit (ZT value) is relatively low, which limits its efficiency in practical applications.

[0004] In recent years, nanowire structures have shown excellent thermoelectric performance due to their unique phonon scattering effect and quantum localization effect, and have become a research hotspot. In particular, silicon germanium nanowires are considered an ideal thermoelectric material due to their good thermoelectric performance and high-temperature stability. However, traditional random disordered silicon germanium nanowires still have limitations in reducing thermal conductivity, making it difficult to meet the demand for efficient thermoelectric conversion.

[0005] In summary, there is an urgent need to optimize the design of silicon germanium nanowires to improve their thermoelectric conversion efficiency and achieve efficient recovery of high-temperature waste heat. SUMMARY

[0006] The present application proposes a high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires, which solves the problem of existing silicon germanium nanowires that still have limitations in reducing thermal conductivity, making it difficult to meet the demand for efficient thermoelectric conversion.

[0007] The high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires described in the present application includes a thermoelectric conversion module, a cold source region, and an electrical energy output module:

[0008] The thermoelectric conversion module is located below the heat source region and is used to collect the heat of the high-temperature waste heat in the heat source region to generate electrical energy;

[0009] The thermoelectric conversion module includes a thermal conductivity layer and a thermoelectric material layer; the thermoelectric material layer is composed of spatially correlated disordered silicon germanium nanowires; in the spatially correlated disordered silicon germanium nanowires, the distribution of germanium atoms is spatially correlated and disordered;

[0010] The heat-conducting layer is arranged on the upper and lower sides of the thermoelectric material layer, and is used for uniformly distributing the heat transferred from the heat source area to the thermoelectric material layer and uniformly dissipating the heat of the thermoelectric material layer to the cold source area.

[0011] The thermoelectric material layer is used for generating electric current by responding to the temperature difference between the heat source area and the cold source area.

[0012] The cold source area is located below the thermoelectric conversion module, and the temperature of the cold source area is lower than that of the heat source area, so as to provide a temperature difference for the thermoelectric material layer to realize the thermoelectric effect.

[0013] The electric energy output module is used for outputting the electric energy generated by the thermoelectric conversion module to an external circuit.

[0014] Further, a preferred embodiment is provided, wherein the thickness of the heat-conducting layer is 0.4-0.6 mm.

[0015] Further, a preferred embodiment is provided, wherein the material of the heat-conducting layer is one of copper, aluminum, tungsten alloy, graphite or silicon carbide.

[0016] Further, a preferred embodiment is provided, wherein the cross-sectional size of the cold source area is the same as that of the heat source area, so as to provide a uniform temperature difference for the thermoelectric material layer.

[0017] Further, a preferred embodiment is provided, wherein the temperature of the cold source area is 20-100℃ lower than that of the heat source area.

[0018] Further, a preferred embodiment is provided, wherein the system further comprises a packaging plate, and the packaging plate is arranged between the heat source area and the thermoelectric conversion module.

[0019] Further, a preferred embodiment is provided, wherein the thickness of the thermoelectric material layer is 100 microns to 10 mm.

[0020] Further, a preferred embodiment is provided, wherein the distribution of germanium atoms is a spatially correlated disordered distribution.

[0021] The spatial coordinates of germanium atoms are related to the distance between adjacent germanium atoms, and the correlation decays as a power law with the distance between germanium atoms:

[0022] C(r)~|r| -a

[0023] Wherein, a is a correlation parameter, and r is the distance between adjacent germanium atoms.

[0024] Further, a preferred embodiment is provided, wherein in the spatially correlated disordered silicon-germanium nanowire, the concentration of germanium atoms is 10%-20%.

[0025] Further, a preferred embodiment is provided, which is the spatially correlated disordered silicon germanium nanowire is made by the following preparation process:

[0026] Material selection step: selecting silicon and germanium as the alloy components of the nanowire, and adjusting the proportion to achieve the desired degree of disorder;

[0027] Lattice matching and mismatching step: depositing a silicon germanium alloy thin film on a substrate by epitaxial growth method, the lattice constant of the substrate is different from that of the silicon germanium alloy, so as to introduce lattice mismatch and generate spatially correlated disordered structure;

[0028] Annealing step: after the growth of the silicon germanium alloy thin film by epitaxial growth method, annealing treatment is carried out to adjust the degree of disorder and correlation;

[0029] Patterning step: using electron beam lithography or nanoimprint technology to define a nanowire pattern on the silicon germanium alloy thin film;

[0030] Etching step: using reactive ion etching technology to etch nanowire structure on the silicon germanium alloy thin film according to the nanowire pattern, and complete the preparation of spatially correlated disordered silicon germanium nanowire.

[0031] The present application has the following advantages:

[0032] 1. The high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowire of the present application optimizes the microstructure design of silicon germanium nanowire by introducing spatially correlated disordered distribution, which realizes more excellent thermoelectric performance compared with traditional thermoelectric materials; Specifically: it can effectively suppress phonon heat transport, thereby significantly reducing the thermal conductivity of silicon germanium nanowire; At the same time, the electronic transport performance is maintained or optimized, so that the overall thermoelectric figure of merit (ZT value) of the silicon germanium nanowire is greatly improved; Finally, more efficient thermoelectric conversion and waste heat recovery are realized.

[0033] 2. The high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowire of the present application optimizes the microstructure design of silicon germanium nanowire by introducing spatially correlated disordered distribution, so that the optimized silicon germanium nanowire can still maintain high thermoelectric performance at high temperature, effectively enhancing the thermoelectric conversion capacity of the high-temperature waste heat recovery system, and widening its application range in high temperature environment, which can be widely used in various high-temperature industrial scenes, such as metallurgy, chemical industry, power, automobile industry, aerospace and other fields.

[0034] The high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowire of the present application is suitable for high-temperature waste heat recovery in industrial production process. BRIEF DESCRIPTION OF DRAWINGS

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of a high-temperature waste heat recovery system based on spatially correlated disordered silicon-germanium nanowires in one embodiment of the present invention.

[0037] Figure 2 A schematic cross-sectional view of spatially correlated disordered silicon-germanium nanowires in one embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram comparing the thermal conductivity of spatially correlated disordered silicon-germanium nanowires with that of traditional random disordered silicon-germanium nanowires, as shown in one embodiment of the present invention.

[0039] Reference numerals: 1. Heat source area; 2. Encapsulation plate; 3. Thermally conductive layer; 4. Thermoelectric material layer; 5. Cold source area; 6. Wire; 7. Power output module. Detailed Implementation

[0040] To make the technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail and completely below with reference to the accompanying drawings. The various embodiments described below are only some preferred embodiments of the present invention, and not all of them; the various embodiments described below are intended to explain the present invention and should not be construed as limiting the present invention; reasonable combinations of the technical features defined in the various embodiments of the present invention, as well as all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort, are all within the scope of protection of the present invention.

[0041] In one embodiment, a high-temperature waste heat recovery system based on spatially correlated disordered silicon-germanium nanowires is provided. The system includes a thermoelectric conversion module, a cold source zone 5, and an electrical energy output module 7.

[0042] The thermoelectric conversion module is located below the heat source area 1 and is used to collect the heat from the high-temperature waste heat of the heat source area 1 to generate electrical energy.

[0043] The thermoelectric conversion module includes a thermally conductive layer 3 and a thermoelectric material layer 4; the thermoelectric material layer is composed of spatially correlated disordered silicon-germanium nanowires; in the spatially correlated disordered silicon-germanium nanowires, the distribution of germanium atoms is spatially correlated disordered.

[0044] The heat-conducting layer 3 is disposed on the upper and lower sides of the thermoelectric material layer 4, and is used to evenly distribute the heat transferred from the heat source area 1 onto the thermoelectric material layer 4, and evenly dissipate the heat of the thermoelectric material layer 4 to the cold source area 5.

[0045] The thermoelectric material layer 4 is used to generate current by generating a thermoelectric effect in response to the temperature difference between the heat source region 1 and the cold source region 5.

[0046] The cold source area 5 is located below the thermoelectric conversion module; the temperature of the cold source area 5 is lower than that of the heat source area 1, and it is used to provide a temperature difference for the thermoelectric material layer 4 to achieve the thermoelectric effect.

[0047] The power output module 7 is used to output the power generated by the thermoelectric conversion module to an external circuit.

[0048] In this embodiment, the high-temperature waste heat recovery system aims to improve the energy recovery efficiency of high-temperature sources such as industrial waste heat and vehicle emissions, and to convert this heat energy into usable electrical energy through thermoelectric conversion technology, thereby reducing energy waste.

[0049] In this embodiment, the heat source area 1 is close to the high temperature source in industrial production and is used to collect the high temperature waste heat (or waste heat) released by the high temperature source; the heat source area 1 is located at the top of the system and transfers the heat collected high temperature waste heat to the heat-conducting layer 3, thermoelectric material layer 4 and other components of the system through heat conduction or radiation.

[0050] The high-temperature sources include industrial furnaces, steam boilers, and engine exhaust, etc.

[0051] In this embodiment, the temperature of the heat source zone 1 can be as high as 500°C to 800°C.

[0052] In this embodiment, the heat-conducting layer 3 includes a hot-end heat-conducting layer and a cold-end heat-conducting layer, which are respectively disposed on the upper and lower sides of the thermoelectric material layer 4, that is, the hot-end heat-conducting layer is disposed on the upper side of the thermoelectric material layer 4, and the cold-end heat-conducting layer is disposed on the lower side of the thermoelectric material layer 4.

[0053] In this embodiment, the hot end heat-conducting layer is located between the heat source region 1 and the thermoelectric material layer 4, and is responsible for transferring the waste heat of the heat source region 1 to the thermoelectric material layer 4.

[0054] Furthermore, in one embodiment, the thickness of the thermally conductive layer 3 is 0.4 to 0.6 mm.

[0055] Furthermore, in one embodiment, the material of the heat-conducting layer 3 is one of copper, aluminum, tungsten alloy, graphite, or silicon carbide.

[0056] In this embodiment, the design requirement of the heat-conducting layer 3 is high thermal conductivity efficiency to reduce heat energy loss and ensure that the heat energy can be efficiently transferred to the thermoelectric material layer 4. The heat-conducting layer 3 uses high-thermal-conductivity materials such as copper, aluminum, tungsten alloy, graphite, or silicon carbide, so that the heat maintains as high a temperature as possible when entering the thermoelectric material layer 4, thereby providing a larger temperature difference for the thermoelectric effect.

[0057] In this embodiment, the silicon germanium nanowire material has very excellent thermoelectric performance, and in particular, the spatially correlated disordered structure can effectively inhibit heat conduction and improve the thermoelectric conversion efficiency of the system. Specifically, the spatially correlated disordered silicon germanium nanowire realizes lower thermal conductivity by regulating the internal disordered structure.

[0058] By observing the cross-sectional structure of the spatially correlated disordered silicon germanium nanowire, it can be seen that at the nanoscale, the thermal conductivity of these nanowires is significantly reduced, while the electrical conductivity remains at a high level. The advantage of this spatially correlated disordered structure is that it can effectively isolate heat flow, reduce heat loss, while retaining high electron mobility, realizing efficient thermoelectric conversion.

[0059] Further, in an embodiment, the diameter of the spatially correlated disordered silicon germanium nanowire is 50 nm.

[0060] Further, in an embodiment, the thickness of the thermoelectric material layer 4 is 100 microns to 10 millimeters.

[0061] In this embodiment, the thickness of the thermoelectric material layer 4 can be optimized in design according to the temperature of the heat source area 1 and the thermoelectric efficiency requirement (customizable, adjustable), and is usually several hundred microns to several millimeters.

[0062] In this embodiment, by optimizing the thickness of the thermoelectric material layer 4, the thermoelectric conversion efficiency can be greatly improved.

[0063] Further, in an embodiment, the current generated by the thermoelectric effect of the thermoelectric material layer 4 is direct current, i.e., the electric energy generated by the thermoelectric conversion module is direct current.

[0064] Further, in an embodiment, the cold source area 5 and the heat source area 1 have the same cross-sectional size to provide a uniform temperature difference for the thermoelectric material layer 4.

[0065] Further, in an embodiment, the temperature of the cold source area 5 is 20℃ to 100℃ lower than that of the heat source area 1.

[0066] In this embodiment, the lower the temperature of the cold source area 5, the higher the thermoelectric conversion efficiency of the thermoelectric material layer 4.

[0067] Further, in an embodiment, the cold source area 5 provides a low temperature environment by a cooling system or natural cooling, maintaining a temperature difference with the heat source area 1; wherein the cooling system can be realized by a liquid cooling system (such as a cooling liquid circulation system) or an air cooling system.

[0068] Further, in an embodiment, the electric energy output module 7 is circuit-connected with the thermoelectric conversion module through the wire 6.

[0069] Further, in an embodiment, the wire 6 is made of a material with good electrical conductivity, such as copper or aluminum alloy, for efficiently conducting the electric energy generated by the thermoelectric material layer 4.

[0070] Further, in an embodiment, the wire 6 has good high-temperature resistance to ensure stability under long-time work.

[0071] Further, in an embodiment, the wire 6 is a copper wire with a diameter of 2 mm to reduce electric energy transmission loss.

[0072] Further, in an embodiment, the electric energy output module 7 is used to output the direct current generated by the thermoelectric conversion module after power adjustment.

[0073] Further, in an embodiment, the electric energy output module 7 includes a battery storage system (such as a lithium battery), a DC / AC inverter, and an electric energy management system.

[0074] The electric energy management system is used to control whether to store the electric energy generated by the thermoelectric conversion module or directly provide electric power to the outside according to the demand:

[0075] If it is controlled to store the electric energy generated by the thermoelectric conversion module, the electric energy generated by the thermoelectric conversion module is sent to the battery storage system; the battery storage system is used to store the electric energy generated by the thermoelectric conversion module.

[0076] If it is controlled to directly provide electric power to the outside, the electric energy generated by the thermoelectric conversion module is sent to the DC / AC inverter; the DC / AC inverter is used to convert the direct current generated by the thermoelectric conversion module into alternating current and provide electric power to the outside after power adjustment.

[0077] Further, in an embodiment, the system further includes a packaging plate 2; the packaging plate 2 is arranged between the heat source area 1 and the thermoelectric conversion module.

[0078] In this embodiment, the packaging plate 2 is an external protective component of the system, mainly serving as a support and fixing function. The packaging plate 2 can effectively prevent external pollution from affecting the internal components of the system (such as the thermoelectric conversion module), and provide a good contact surface between the heat source area 1 and the thermoelectric material layer 4, ensuring the stability of the system.

[0079] Further, in an embodiment, the thickness of the packaging plate 2 is 1-2 mm.

[0080] Further, in an embodiment, the material of the packaging plate 2 is (high-strength) ceramic or metal alloy to ensure structural stability and high-temperature resistance.

[0081] In this embodiment, the working principle of the high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires is as follows:

[0082] Heat transfer from the heat source: When high-temperature waste heat enters the system from the heat source area 1, it is first transferred through the heat conduction layer 3. The heat conduction layer 3 ensures that heat can be effectively and rapidly conducted from the heat source area 1 to the thermoelectric material layer 4, and reduces heat loss during transmission.

[0083] Thermoelectric effect: After the heat is transferred to the thermoelectric material layer 4 through the heat conduction layer 3, the thermoelectric material (spatially correlated disordered silicon germanium nanowires) will respond to the temperature difference between the heat source area 1 and the cold source area 5, and the thermoelectric effect, especially the Seebeck effect, will occur. Due to the existence of a significant temperature gradient within the thermoelectric material layer 4, the temperature difference between the heat source area 1 and the cold source area 5 causes the flow of electrons in the thermoelectric material, thereby generating an electric current.

[0084] Electricity recovery: In the thermoelectric material layer 4, the electric current generated by the thermoelectric effect is transmitted to the electricity output module 7 through the wire 6. The main function of the electricity output module 7 is to convert the flowing electric current into usable electrical energy. The electricity output module 7 can store or directly supply electrical energy to external loads according to demand. The power conversion circuit in the electricity output module 7 can be optimized to efficiently convert the electric current generated by the thermoelectric effect into a stable voltage, thereby providing supplemental power for industrial equipment or storing the electrical energy generated by the thermoelectric effect for subsequent use.

[0085] Further, in an embodiment, the distribution of germanium atoms is a spatially correlated disordered distribution:

[0086] The spatial coordinates of germanium atoms are related to the distance between adjacent germanium atoms, and the correlation decays as a power law with the distance between germanium atoms:

[0087] C(r)~|r| -a

[0088] where a is the correlation parameter and r is the distance between adjacent germanium atoms.

[0089] It should be noted that thermoelectric devices play an important role in managing heat and converting waste heat into electricity.

[0090] The efficiency of thermoelectric materials is quantified by the thermoelectric figure of merit:

[0091]

[0092] where σ is the electrical conductivity, S is the Seebeck coefficient, T is the temperature, and κ is the thermal conductivity.

[0093] It is often complicated to improve the thermoelectric figure of merit by manipulating electronic properties to change electrical conductivity. Reducing the lattice thermal conductivity is a more facile and effective strategy without significantly changing other factors. By alloying with an element of similar chemical properties (e.g., germanium), the lattice thermal conductivity of silicon can be reduced by at least an order of magnitude without significantly changing the electronic transport coefficients.

[0094] It should be noted that the silicon germanium alloy nanowires in the current conventional thermoelectric devices often adopt a random disordered structure, that is, the germanium atoms are randomly and orderly distributed in the silicon nanowires. However, in nature, the inhomogeneity is not completely randomly distributed, and the random and orderly distributed structure cannot truly reflect the natural phenomenon, and the silicon nanowires with random and orderly distributed structure still have limitations in reducing thermal conductivity, and it is difficult to meet the demand of efficient thermoelectric conversion.

[0095] It should be noted that in nature, the inhomogeneity is not completely randomly distributed, but is correlated with each other at a large distance, that is, the correlation decays as a power law with the interatomic distance (such as the distance between adjacent germanium atoms), rather than exponentially. The spatially correlated disordered distribution reflects the real natural phenomenon.

[0096] In the embodiment, if the correlation parameter a is less than the spatial dimension, the correlation is considered to be long-range.

[0097] In the embodiment, germanium atoms with spatially correlated distribution are introduced into the pure silicon nanowires to form spatially correlated disordered silicon germanium nanowires.

[0098] Further, in an embodiment, the spatially correlated disordered silicon germanium nanowires are made by using the following preparation process:

[0099] Material selection step: silicon (Si) and germanium (Ge) are selected as the alloy components of the nanowires, and the proportion is adjusted to achieve the desired degree of disorder;

[0100] Lattice matching and mismatching step: by epitaxial growth method, a silicon germanium alloy thin film is deposited on a substrate with a specific lattice constant, a lattice mismatch is introduced on the substrate, and a spatially correlated disordered structure (i.e., the distribution of germanium atoms is a spatially correlated disordered distribution) is generated;

[0101] Heat treatment step: After the growth of the silicon germanium alloy thin film using the epitaxial growth method, annealing treatment is performed to adjust the degree of disorder and correlation;

[0102] Patterning step: Using electron beam lithography or nanoimprint technology, a nanowire pattern is defined on the silicon germanium alloy thin film;

[0103] Etching step: Using reactive ion etching (RIE) technology, appropriate gases such as chlorine or fluorides are used to etch nanowire structures on the silicon germanium alloy thin film according to the nanowire pattern, completing the fabrication of spatially correlated disordered silicon germanium nanowires.

[0104] It should be noted that, regarding the lattice matching and mismatching step: In an ideal case, the lattice constant of the epitaxially grown thin film should be completely matched with the substrate to avoid stress and defects caused by lattice mismatch. However, in this step, instead of pursuing complete lattice matching, a specific mismatch is introduced to introduce a disordered structure.

[0105] Further, in an embodiment, the introduction of lattice mismatch on the substrate: By selecting a substrate with a different lattice constant than the silicon germanium alloy (i.e. a substrate with a specific lattice constant), stress and defects are introduced to form a spatially correlated disordered structure.

[0106] In this embodiment, by selecting a substrate with a different lattice constant than the silicon germanium alloy (i.e. a substrate with a specific lattice constant), the difference in lattice constant causes stress and defects between the thin film and the substrate during growth, which propagates in the thin film, forming a spatially correlated disordered structure; it is this disordered structure that gives silicon germanium nanowires unique physical and chemical properties.

[0107] Further, in an embodiment, in the heat treatment step, the annealing treatment temperature range is 600°C to 800°C, and the duration is 30 minutes to 2 hours.

[0108] In this embodiment, the heat treatment step helps to adjust the degree of disorder and correlation, optimizing the performance of the nanowire.

[0109] Further, in an embodiment, in the lattice matching and mismatching step, the material of the substrate with a specific lattice constant is silicon or sapphire.

[0110] Further, in an embodiment, in the lattice matching and mismatching step, the substrate with a specific lattice constant needs to be thoroughly cleaned and surface treated to ensure high-quality epitaxial growth.

[0111] Further, in an embodiment, in the lattice matching and mismatching step, the epitaxial growth method is molecular beam epitaxy (MBE) or chemical vapor deposition (CVD) technique, which is performed under high vacuum conditions.

[0112] In the present embodiment, the molecular beam epitaxy (MBE) is a technique that epitaxially grows a thin film on a substrate surface by precisely controlling the flux of source molecules or atoms under ultra-high vacuum conditions. In the MBE process, source materials such as silane SiH4 and germane GeH4, or their cracked products, are heated to vaporize and form molecular or atomic beams. These beams are directed and deposited on a cleaned and pretreated substrate after passing through precise mass flow controllers and shutter systems.

[0113] The advantages of MBE technology include:

[0114] High precision: The growth rate and film composition can be precisely controlled.

[0115] Low temperature growth: It is usually performed at lower temperatures, which helps to reduce the impact of thermal stress on film quality.

[0116] Good interface control: Thin films with steep interfaces and excellent crystal quality can be grown.

[0117] In the present embodiment, the chemical vapor deposition (CVD) is a technique that generates solid materials on the surface of a substrate through chemical reactions. In the CVD process, gaseous precursors containing silicon (Si) and germanium (Ge) elements such as silane SiH4 and germane GeH4 are introduced into the reaction chamber and chemically react on the heated substrate surface to generate a solid silicon-germanium alloy thin film.

[0118] The advantages of CVD technology include:

[0119] High efficiency: It can quickly grow thicker films.

[0120] Flexibility: The composition and properties of the film can be controlled by adjusting the reaction conditions such as temperature, gas flow and reaction time.

[0121] Good coverage: Good film coverage can be achieved even on substrates with complex shapes.

[0122] Further, in an embodiment, in the epitaxial growth method of the lattice matching and mismatching step, the epitaxial growth parameters are as follows:

[0123] Temperature control is between 500°C and 700°C to optimize crystal quality and disorder level;

[0124] The growth rate is adjusted from 0.1 to 1 nanometer per second to precisely control the thickness and composition of the thin film;

[0125] For the case of using chemical vapor deposition (CVD) technology:

[0126] The gas flow ratio of silane (SiH4) and germane (GeH4) is precisely controlled to achieve the desired silicon (Si) and germanium (Ge) ratio.

[0127] In this embodiment, through the lattice matching and mismatching steps, the preparation of silicon-germanium alloy thin film (or silicon-germanium alloy material) with spatially correlated disordered structure is completed; and then through the patterning and etching process steps, the preparation of nanowires is completed.

[0128] Further, in an embodiment, after the preparation of spatially correlated disordered silicon-germanium nanowires, structural and performance analysis (structural and performance characterization step) can also be performed:

[0129] Microstructure analysis: Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) are used to observe the morphology and disordered structure of spatially correlated disordered silicon-germanium nanowires;

[0130] Composition analysis: Energy Dispersive X-ray Spectroscopy (EDS) or Secondary Ion Mass Spectrometry (SIMS) is used to determine the distribution of silicon atoms (Si) and germanium atoms (Ge) in spatially correlated disordered silicon-germanium nanowires;

[0131] Physical property measurement: Electrical and thermal performance tests are conducted to evaluate the impact of spatially correlated disordered structure on the performance of nanowires.

[0132] Further, in an embodiment, to verify the effect of the spatially correlated disordered silicon-germanium nanowires, a comparative experiment is provided to compare the thermal conductivity of spatially correlated disordered silicon-germanium nanowires with that of traditional random disordered silicon-germanium nanowires:

[0133] From the comparison results, the thermal conductivity of spatially correlated disordered silicon-germanium nanowires is lower, which means that it can more effectively maintain temperature difference and avoid rapid heat dissipation, thereby improving the efficiency of thermoelectric conversion, i.e. it is proved that by optimizing the germanium distribution structure in nanowires, the efficiency of thermoelectric conversion can be greatly improved.

[0134] Further, in an embodiment, in the spatially correlated disordered silicon-germanium nanowires, the concentration of germanium atoms is 10% to 20%.

[0135] In this embodiment, according to the above comparative experiments, when the Ge (germanium atom) concentration is 10% to 20%, the structure of spatially correlated disorder has the most significant inhibitory effect on heat transport, and the decline in thermal conductivity can be up to 58%. This result shows that, within this concentration range, the spatially correlated disorder structure significantly weakens the heat conduction caused by lattice vibration through its special microscopic design, greatly optimizing the thermoelectric performance of the material. The special microscopic structure of the spatially correlated disorder silicon-germanium nanowire effectively enhances the mobility of electrons while reducing the thermal conductivity, allowing heat to remain in the thermoelectric material for a longer period of time, ensuring that the thermoelectric effect is more persistent and stable.

[0136] In summary, the high-temperature waste heat recovery system based on spatially correlated disorder silicon-germanium nanowires has the following advantages:

[0137] 1. By introducing spatially correlated disorder distribution to optimize the microscopic structure design of silicon-germanium nanowires, the scattering of low-frequency phonons carrying most of the heat is significantly increased, effectively reducing the thermal conductivity of the material. This innovative design significantly inhibits heat conduction, while maintaining the integrity of the crystal lattice structure, thus maintaining good electrical conductivity of the material, thereby improving the thermoelectric conversion efficiency.

[0138] 2. Compared with traditional random disorder silicon-germanium nanowires, by introducing spatially correlated disorder distribution to optimize the microscopic structure design of silicon-germanium nanowires, the optimized silicon-germanium nanowires can still maintain high thermoelectric performance at high temperatures (i.e., they can still maintain high-efficiency thermoelectric conversion in high-temperature environments), thereby expanding their application range in high-temperature environments.

[0139] 3. The system takes into account the production process that is easy to implement. By introducing spatially correlated disorder distribution to optimize the microscopic structure design of silicon-germanium nanowires, the germanium nanowires have lower production costs and higher production efficiency. The system design is simple and easy to implement, making it suitable for large-scale production and practical application.

[0140] 4. The micron-level thickness and integrated design of the thermoelectric material layer 4 make the system structure compact and occupy less space, making it easy to install and apply.

[0141] 5. The spatially correlated disorder silicon-germanium nanowires have adjustability and customizability (such as thickness adjustment), which can be adjusted according to different application requirements, adapting to different scales and conditions of industrial environments.

[0142] 6. The system can recover waste heat from industrial waste heat and traffic emissions and convert it into usable electrical energy, achieving energy reuse, reducing energy waste, and reducing environmental pollution, with high economic and social benefits.

[0143] 7. The system is particularly suitable for various high-temperature industrial fields, transportation fields and other industries generating high-temperature waste heat, such as metallurgy, chemical industry, power, automobile industry, aerospace and other fields, and provides a new technical path for high-temperature waste heat recovery and electric energy conversion.

[0144] The above further describes the technical solutions provided by the present application in detail through several specific embodiments, in order to highlight the advantages and benefits of the technical solutions provided by the present application. However, the above several specific embodiments are not used as a limitation on the present application, and any reasonable changes and improvements, reasonable combinations and equivalent replacements of the embodiments, etc. based on the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A high temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires, characterized in that, The system comprises a thermoelectric conversion module, a cold source area and an electric energy output module. The thermoelectric conversion module is located below the heat source area and is used to collect the heat of the high-temperature waste heat of the heat source area to generate electric energy. The thermoelectric conversion module comprises a heat-conducting layer and a thermoelectric material layer; the thermoelectric material layer is composed of spatially correlated disordered silicon germanium nanowires; in the spatially correlated disordered silicon germanium nanowires, the distribution of germanium atoms is spatially correlated and disordered. The heat-conducting layer is arranged on the upper and lower sides of the thermoelectric material layer and is used to uniformly distribute the heat transmitted from the heat source area to the thermoelectric material layer and uniformly dissipate the heat of the thermoelectric material layer to the cold source area. The thermoelectric material layer is used to generate electric current through thermoelectric effect in response to the temperature difference between the heat source area and the cold source area. The cold source area is located below the thermoelectric conversion module; the temperature of the cold source area is lower than that of the heat source area and is used to provide a temperature difference for the thermoelectric material layer to realize thermoelectric effect. The electric energy output module is used to output the electric energy generated by the thermoelectric conversion module to an external circuit.

2. The high temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires as claimed in claim 1, wherein, The thickness of the heat-conducting layer is 0.4-0.6 mm.

3. The spatially correlated disordered silicon-germanium nanowire based high temperature waste heat recovery system of claim 1, wherein, The material of the heat-conducting layer is one of copper, aluminum, tungsten alloy, graphite or silicon carbide.

4. The spatially correlated disordered silicon-germanium nanowire based high temperature waste heat recovery system of claim 1, wherein, The cold source area has the same cross-sectional size as the heat source area to provide a uniform temperature difference for the thermoelectric material layer.

5. The spatially correlated disordered silicon-germanium nanowire based high temperature waste heat recovery system of claim 1, wherein, The temperature of the cold source area is 20-100℃ lower than that of the heat source area.

6. The spatially correlated disordered silicon-germanium nanowire based high temperature waste heat recovery system of claim 1, wherein, The system further comprises a packaging plate arranged between the heat source area and the thermoelectric conversion module.

7. The spatially correlated disordered silicon-germanium nanowire based high temperature waste heat recovery system of claim 1, wherein, The thickness of the thermoelectric material layer is 100 microns to 10 mm.

8. The spatially correlated disordered silicon-germanium nanowire based high temperature waste heat recovery system of claim 1, wherein, The distribution of germanium atoms is spatially correlated and disordered: The spatial coordinates of germanium atoms are related to the distance between adjacent germanium atoms, and the correlation decays with the distance between germanium atoms according to a power law: C(r)～|r| -a wherein a is a correlation parameter and r is the distance between adjacent germanium atoms.

9. The spatially correlated disordered silicon-germanium nanowire based high temperature waste heat recovery system of claim 8, wherein, In the spatially correlated disordered silicon germanium nanowires, the concentration of germanium atoms is 10%-20%.

10. The spatially correlated disordered silicon-germanium nanowire based high temperature waste heat recovery system of claim 9, wherein, The spatially correlated disordered silicon germanium nanowires are made by the following preparation process: Material selection step: selecting silicon and germanium as nanowire alloy components and adjusting their proportions to achieve the desired degree of disorder; Lattice matching and mismatching step: depositing a silicon germanium alloy thin film on a substrate by epitaxial growth method, wherein the lattice constant of the substrate is different from that of the silicon germanium alloy to introduce lattice mismatch and thus generate a spatially correlated disordered structure; Heat treatment step: annealing after the growth of the silicon germanium alloy thin film by the epitaxial growth method to adjust the degree of disorder and correlation; Pattern processing step: defining a nanowire pattern on the silicon germanium alloy thin film using electron beam lithography or nanoimprint technology; Etching process step: etching nanowire structures on the silicon germanium alloy thin film according to the nanowire pattern by reactive ion etching technology to complete the fabrication of the spatially correlated disordered silicon germanium nanowires.

Images