High-temperature waste heat recovery system based on space correlation disordered silicon germanium nanowires

Abstract

The invention discloses a high-temperature waste heat recovery system based on space correlation disordered silicon germanium nanowires, belongs to the technical field of thermoelectricity, and particularly relates to high-temperature waste heat recovery in the industrial production process. The problems that an existing silicon germanium nanowire still has limitation in the aspect of reduction of heat conductivity, and the requirement for efficient thermoelectric conversion is difficult to meet are solved. 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 and generating a thermoelectric effect to generate current. The high-temperature waste heat recovery system based on the space correlation disordered silicon germanium nanowires is suitable for high-temperature waste heat recovery in the industrial production process.

Description

Technical Field

[0001] The invention relates to the field of thermoelectric technology, and in particular to high-temperature waste heat recovery in industrial production processes. Background Art

[0002] In the industrial production process, a large amount of high-temperature waste heat is directly discharged, which not only causes energy waste, but also has an adverse impact on the environment. According to statistics, high-temperature waste heat in the industrial field accounts for 20%-50% of the total energy consumption. If it can be effectively recycled and utilized, it will significantly improve energy utilization efficiency and reduce carbon emissions.

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

[0004] In recent years, nanowire structures have become a research hotspot due to their unique phonon scattering effect and quantum localization effect, showing excellent thermoelectric performance. In particular, silicon germanium nanowires are considered to be 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 needs of 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 of the invention

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

[0007] The high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires of the present invention comprises a thermoelectric conversion module, a cold source area and an electric energy output module:

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

[0009] 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 disordered distribution;

[0010] The heat-conducting layer is arranged on the upper and lower sides of the thermoelectric material layer, and is used to evenly distribute the heat transferred from the heat source area to the thermoelectric material layer, and evenly dissipate the heat of the thermoelectric material layer to the cold source area;

[0011] The thermoelectric material layer is used to generate current by thermoelectric effect in response 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; the temperature of the cold source area is lower than that of the hot source area, and is used to provide a temperature difference for the thermoelectric material layer to achieve a thermoelectric effect;

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

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

[0015] Furthermore, 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] Furthermore, a preferred embodiment is provided, wherein the cross-sectional dimensions of the cold source region and the hot source region are the same, so as to provide a uniform temperature difference for the thermoelectric material layer.

[0017] Furthermore, a preferred embodiment is provided, wherein the temperature of the cold source zone is 20° C. to 100° C. lower than that of the hot source zone.

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

[0019] Furthermore, a preferred embodiment is provided, wherein the thickness of the thermoelectric material layer is 100 micrometers to 10 millimeters.

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

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

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

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

[0024] Furthermore, a preferred embodiment is provided, in the spatially correlated disordered silicon germanium nanowires, the concentration of germanium atoms is 10% to 20%.

[0025] Further, a preferred embodiment is provided, wherein the spatially correlated disordered silicon germanium nanowires are prepared by the following preparation process:

[0026] Materials selection step: Select silicon and germanium as the nanowire alloy components and adjust their ratio to achieve the desired degree of disorder;

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

[0028] Heat treatment step: after the growth of the silicon germanium alloy film is completed by the epitaxial growth method, annealing treatment is performed to adjust the disorder degree and correlation;

[0029] Patterning process: using electron beam lithography or nanoimprinting technology to define the nanowire pattern on the silicon germanium alloy film;

[0030] Etching process steps: Reactive ion etching technology is used to etch a nanowire structure on the silicon-germanium alloy film according to the nanowire pattern to complete the production of spatially correlated disordered silicon-germanium nanowires.

[0031] The present invention has the following beneficial effects:

[0032] 1. The high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires described in the present invention achieves better thermoelectric performance than traditional thermoelectric materials by optimizing the microstructure design of silicon germanium nanowires, that is, introducing spatially correlated disordered distribution; specifically: it can effectively suppress phonon heat transport, thereby significantly reducing the thermal conductivity of silicon germanium nanowires; at the same time, the electron transport performance is maintained or optimized, thereby greatly improving the overall thermoelectric figure of merit (ZT value) of silicon germanium nanowires; and ultimately achieving more efficient thermoelectric conversion and waste heat recovery. .

[0033] 2. The high-temperature waste heat recovery system based on spatially correlated disordered silicon-germanium nanowires described in the present invention optimizes the microstructure design of silicon-germanium nanowires by introducing spatially correlated disordered distribution, so that the optimized silicon-germanium nanowires can still maintain high thermoelectric performance at high temperatures, effectively enhancing the thermoelectric conversion capacity of the high-temperature waste heat recovery system, and at the same time broadening its application range in high-temperature environments. It can be widely used in various high-temperature industrial scenarios, such as high-temperature waste heat recovery in metallurgy, chemical industry, electric power, automobile industry, aerospace and other fields.

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

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 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 A schematic diagram showing a comparison of thermal conductivity between spatially correlated disordered silicon germanium nanowires and conventional random disordered silicon germanium nanowires in one embodiment of the present invention;

[0039] Figure numerals: 1. heat source area; 2. packaging board; 3. heat conductive layer; 4. thermoelectric material layer; 5. cold source area; 6. wire; 7. power output module. DETAILED DESCRIPTION

[0040] In order to make the technical solutions and advantages of the present invention more clearly described, the specific implementation methods of the present invention will be further described in detail and completely in conjunction with the accompanying drawings. The various implementation methods described below are only part of the preferred solutions of the present invention, rather than all implementation methods; the various implementation methods described below are intended to explain the present invention and cannot be understood as limitations on the present invention; the reasonable combination of technical features defined in the various implementation methods of the present invention, and all other implementation methods obtained by ordinary technicians in the field without creative work based on the implementation methods of the present invention, are 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 comprising a thermoelectric conversion module, a cold source area 5 and an electric energy output module 7:

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

[0043] The thermoelectric conversion module comprises a heat-conducting 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 distribution;

[0044] The heat conducting layer 3 is arranged 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 to 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 thermoelectric effect in response to the temperature difference between the heat source area 1 and the cold source area 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 hot source area 1, and is used to provide a temperature difference for the thermoelectric material layer 4 to achieve the thermoelectric effect;

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

[0048] In this embodiment, the high-temperature waste heat recovery system is intended to improve the energy recovery efficiency of high-temperature sources such as industrial waste heat and automobile emissions, and convert these thermal energies into usable electrical energy through thermoelectric conversion technology to reduce 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 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 collected high-temperature waste heat to the system's thermal conductive layer 3, thermoelectric material layer 4 and other components 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 area 1 can be as high as 500°C to 800°C.

[0052] In this embodiment, the thermal conductive layer 3 includes a hot end thermal conductive layer and a cold end thermal conductive layer, which are respectively arranged on the upper and lower sides of the thermoelectric material layer 4, that is, the hot end thermal conductive layer is arranged on the upper side of the thermoelectric material layer 4, and the cold end thermal conductive layer is arranged 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 area 1 and the thermoelectric material layer 4 , and is responsible for transferring the waste heat of the heat source area 1 to the thermoelectric material layer 4 .

[0054] Furthermore, in one embodiment, the thickness of the heat conducting layer 3 is 0.4-0.6 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 heat conduction efficiency to reduce heat energy loss and ensure that heat energy can be efficiently transferred to the thermoelectric material layer 4. The heat conducting layer 3 is made of a material with high thermal conductivity, such as copper, aluminum, tungsten alloy, graphite or silicon carbide, so that the heat is kept at 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, especially 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 achieves lower thermal conductivity by regulating its internal disordered structure.

[0058] By observing the cross-sectional structure of spatially correlated disordered silicon germanium nanowires, 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 and reduce heat loss, while retaining high electron mobility to achieve efficient thermoelectric conversion.

[0059] Furthermore, in one embodiment, the diameter of the spatially correlated disordered silicon germanium nanowires is 50 nm.

[0060] Furthermore, in one embodiment, the thickness of the thermoelectric material layer 4 is 100 micrometers to 10 millimeters.

[0061] In this embodiment, the thickness of the thermoelectric material layer 4 can be optimized and designed (customizable and adjustable) according to the temperature of the heat source area 1 and the thermoelectric efficiency requirements, 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] Furthermore, in one embodiment, the current generated by the thermoelectric effect of the thermoelectric material layer 4 is direct current, that is, the electric energy generated by the thermoelectric conversion module is direct current.

[0064] Furthermore, in one embodiment, the cross-sectional dimensions of the cold source region 5 and the hot source region 1 are the same, so as to provide a uniform temperature difference for the thermoelectric material layer 4 .

[0065] Furthermore, in one embodiment, the temperature of the cold source area 5 is 20° C. to 100° C. lower than that of the hot source area 1 .

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

[0067] Furthermore, in one embodiment, the cold source area 5 provides a low temperature environment through a cooling system or natural cooling to maintain a temperature difference with the hot source area 1; wherein the cooling system can be implemented by a liquid cooling system (such as a coolant circulation system) or an air cooling system.

[0068] Furthermore, in one embodiment, the electric energy output module 7 is circuit-connected to the thermoelectric conversion module via a wire 6 .

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

[0070] Furthermore, in one embodiment, the wire 6 has good high temperature resistance to ensure stability during long-term operation.

[0071] Furthermore, in one embodiment, the conductor 6 is a copper wire with a diameter of 2 mm to reduce power transmission loss.

[0072] Furthermore, in one 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 one embodiment, the power output module 7 includes a battery storage system (such as a lithium battery), a DC / AC inverter, and a power management system;

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

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

[0076] If the electric energy generated by the thermoelectric conversion module is controlled to directly provide external power, the electric energy generated by the thermoelectric conversion module is sent to a 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 external power after power regulation.

[0077] Furthermore, in one embodiment, the system further comprises 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 protection component of the system, which mainly plays a supporting and fixing role. The packaging plate 2 can effectively prevent the influence of external pollution on 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, thereby ensuring the stability of the system.

[0079] Furthermore, in one embodiment, the packaging plate 2 has a thickness of 1 to 2 mm.

[0080] Furthermore, in one 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 heat source: When high-temperature waste heat enters the system from the heat source area 1, it is first transferred through the heat conductive layer 3. The heat conductive layer 3 ensures that the heat can be effectively and quickly transferred from the heat source area 1 to the thermoelectric material layer 4, and reduces heat loss during the transfer process.

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

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

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

[0086] The spatial coordinates of germanium atoms are related to the distances between adjacent germanium atoms, and the correlation decays in 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 electrical energy.

[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] Improving thermoelectric figures of merit by manipulating electronic properties to change electrical conductivity is often complicated. Reducing lattice thermal conductivity is a simpler and more effective strategy without significantly changing other factors. By alloying with chemically similar elements (such as germanium), the lattice thermal conductivity of silicon can be reduced by at least an order of magnitude without significantly changing the electron transport coefficient.

[0094] It should be noted that the silicon-germanium alloy nanowires in current conventional thermoelectric devices often adopt a random and disordered structure, that is, the germanium atoms are randomly and disorderly distributed in the silicon nanowires. However, in nature, the inhomogeneity is often not completely randomly distributed, and the use of random and disordered distribution cannot truly reflect natural phenomena. At the same time, silicon nanowires with random and disordered distribution structures still have limitations in reducing thermal conductivity, making it difficult to meet the needs of efficient thermoelectric conversion.

[0095] It should be noted that in nature, inhomogeneities are often not completely randomly distributed, but are correlated over larger distances, that is, the correlation decays in a power law with the interatomic distance (such as the distance between adjacent germanium atoms) rather than exponentially; the spatially correlated disordered distribution reflects real natural phenomena.

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

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

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

[0099] Material selection step: Select silicon (Si) and germanium (Ge) as the nanowire alloy components and adjust their ratio to achieve the desired degree of disorder;

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

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

[0102] Patterning process: using electron beam lithography or nanoimprinting technology to define the nanowire pattern on the silicon germanium alloy film;

[0103] Etching process steps: Reactive ion etching (RIE) technology is used, using appropriate gases (such as chlorine or fluoride) to etch a nanowire structure on the silicon-germanium alloy film according to the nanowire pattern, thereby completing the production of spatially correlated disordered silicon-germanium nanowires.

[0104] It should be noted that regarding the lattice matching and mismatching steps: ideally, the lattice constants of the epitaxially grown film and the substrate should be completely matched to avoid stress and defects caused by lattice mismatch. However, in this step, the goal is not to achieve complete lattice matching, but to introduce a disordered structure through a specific mismatch.

[0105] Furthermore, in one embodiment, the lattice mismatch is introduced on the substrate by selecting a substrate with a lattice constant different from that of the silicon-germanium alloy (ie, a substrate with a specific lattice constant), thereby introducing stress and defects to form a spatially correlated disordered structure.

[0106] In this embodiment, by selecting a substrate with a lattice constant different from that of the silicon-germanium alloy (i.e., a substrate with a specific lattice constant), the difference in lattice constants is used to cause stress and defects to be generated between the film and the substrate during the growth process. These stresses and defects propagate in the film to form a spatially correlated disordered structure; it is this disordered structure that gives silicon-germanium nanowires unique physical and chemical properties.

[0107] Further, in one embodiment, in the heat treatment step, the annealing treatment is performed at a temperature ranging from 600° C. to 800° C. and lasts for 30 minutes to 2 hours.

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

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

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

[0111] Furthermore, in one embodiment, in the lattice matching and mismatching steps, the epitaxial growth method is molecular beam epitaxy (MBE) or chemical vapor deposition (CVD) technology, and the epitaxial growth is performed under high vacuum conditions.

[0112] In this embodiment, the molecular beam epitaxy (MBE) is a technology that precisely controls the beam of raw material molecules or atoms under ultra-high vacuum conditions to perform epitaxial growth on the substrate surface. In the MBE process, source materials of silicon (Si) and germanium (Ge) (such as silane SiH4 and germanium GeH4, or their cracking products) are heated to evaporate to form molecular beams or atomic beams. These beams are guided and deposited on the substrate that has been cleaned and pre-treated after passing through a precise mass flow controller and shutter system.

[0113] The advantages of MBE technology include:

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

[0115] Low temperature growth: Usually carried out at lower temperatures, which helps to reduce the impact of thermal stress on film quality.

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

[0117] In this embodiment, the chemical vapor deposition (CVD) is a technology for generating 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 germanium GeH4) are introduced into a reaction chamber and chemically react on the heated substrate surface to generate a solid silicon-germanium alloy film.

[0118] The advantages of CVD technology include:

[0119] High efficiency: thicker films can be grown quickly.

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

[0121] Good coverage: Good film coverage can be achieved even on complex-shaped substrates.

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

[0123] The temperature is controlled between 500°C and 700°C to optimize crystal quality and disorder;

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

[0125] For Chemical Vapor Deposition (CVD) technology:

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

[0127] In this embodiment, the production of a silicon-germanium alloy film (or silicon-germanium alloy material) having a spatially correlated disordered structure is completed through lattice matching and mismatching steps; subsequently, the preparation of nanowires is completed through a graphic processing step and an etching process step.

[0128] Further, in one embodiment, after the spatially correlated disordered silicon germanium nanowires are fabricated, the structure and performance analysis (structure and performance characterization step) may be performed:

[0129] Microstructure analysis: Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to observe the morphology and disordered structure of spatially correlated disordered SiGe 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 SiGe nanowires;

[0131] Physical property measurements: Electrical and thermal performance tests were performed to evaluate the impact of spatially correlated disordered structures on the performance of nanowires.

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

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

[0134] Furthermore, in one 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 spatially correlated disordered structure has the most significant inhibitory effect on heat transport, and the reduction in thermal conductivity can reach up to 58%. This result shows that within this concentration range, the spatially correlated disordered 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 microstructure of the spatially correlated disordered silicon germanium nanowires effectively enhances the mobility of electrons while reducing thermal conductivity, allowing heat to be retained in the thermoelectric material for a longer time, ensuring that the thermoelectric effect is more durable and stable.

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

[0137] 1. By introducing spatially correlated disordered distribution to optimize the microstructure design of silicon germanium nanowires, the scattering of low-frequency phonons that carry most of the heat is significantly increased, thereby effectively reducing the thermal conductivity of the material; this innovative design significantly suppresses heat conduction, and by maintaining a complete lattice structure, the electrical conductivity of the material is well maintained, thereby improving the thermoelectric conversion efficiency.

[0138] 2. Compared with traditional randomly disordered silicon germanium nanowires, the microstructure design of silicon germanium nanowires is optimized by introducing spatially correlated disordered distribution, so that the optimized silicon germanium nanowires can still maintain high thermoelectric performance at high temperatures (that is, they can still maintain efficient thermoelectric conversion in high temperature environments), broadening their application range in high temperature environments.

[0139] 3. The system is designed with easy-to-implement production processes in mind. By introducing spatially correlated disordered distribution and optimizing the microstructure 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, and is convenient 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, occupy a small space, and facilitate installation and application.

[0141] 5. The spatially correlated disordered silicon germanium nanowires are adjustable and customizable (such as thickness adjustment), and can be adjusted according to different application requirements to adapt to industrial environments of different scales and conditions.

[0142] 6. The system can recycle waste heat from industrial waste and traffic emissions and convert it into usable electrical energy, thereby realizing energy reuse, reducing energy waste, and lowering environmental pollution, and has high economic and social benefits.

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

[0144] The technical solution provided by the present invention is further described in detail above through several specific implementation modes in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the several specific implementation modes described above are not intended to be used as limitations on the present invention. Any reasonable changes and improvements to the present invention, reasonable combinations of implementation modes and equivalent substitutions based on the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires, characterized in that: The system includes 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 high-temperature waste heat of the heat source area to generate electrical 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 disordered distribution; The heat-conducting layer is arranged on the upper and lower sides of the thermoelectric material layer, and is used to evenly distribute the heat transferred from the heat source area to the thermoelectric material layer, and evenly dissipate the heat of the thermoelectric material layer to the cold source area; The thermoelectric material layer is used to generate current by 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 hot source area, and is used to provide a temperature difference for the thermoelectric material layer to achieve a 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 according to claim 1 is characterized in that: The thickness of the heat-conducting layer is 0.4-0.6 mm.

3. The high temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires according to claim 1 is characterized in that: The material of the heat conducting layer is one of copper, aluminum, tungsten alloy, graphite or silicon carbide.

4. The high temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires according to claim 1, characterized in that: The cross-sectional dimensions of the cold source region and the hot source region are the same to provide a uniform temperature difference for the thermoelectric material layer.

5. The high temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires according to claim 1, characterized in that: The temperature of the cold source area is 20° C. to 100° C. lower than that of the hot source area.

6. The high temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires according to claim 1, characterized in that: The system further comprises a packaging plate; the packaging plate is arranged between the heat source area and the thermoelectric conversion module.

7. The high temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires according to claim 1, characterized in that: The thickness of the thermoelectric material layer is 100 micrometers to 10 millimeters.

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

9. The high temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires according to claim 8, characterized in that: In the spatially correlated disordered silicon germanium nanowires, the concentration of germanium atoms is 10% to 20%.

10. The high temperature waste heat recovery system based on spatially correlated disordered silicon germanium nanowires according to claim 9, characterized in that: The spatially correlated disordered silicon germanium nanowires are manufactured using the following preparation process: Materials selection step: Select silicon and germanium as the nanowire alloy components and adjust their ratio to achieve the desired degree of disorder; Lattice matching and mismatching step: depositing a silicon-germanium alloy thin film on a substrate by an epitaxial growth method, wherein the lattice constant of the substrate is different from that of the silicon-germanium alloy, so as to introduce a lattice mismatch, thereby generating a spatially correlated disordered structure; Heat treatment step: after the growth of the silicon germanium alloy film is completed by the epitaxial growth method, annealing treatment is performed to adjust the disorder degree and correlation; Patterning process: using electron beam lithography or nanoimprinting technology to define the nanowire pattern on the silicon germanium alloy film; Etching process steps: Reactive ion etching technology is used to etch a nanowire structure on the silicon-germanium alloy film according to the nanowire pattern to complete the production of spatially correlated disordered silicon-germanium nanowires.

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