Thermoelectric power generation module and preparation method thereof

Abstract

The invention discloses a preparation method of a thermoelectric power generation module and the thermoelectric power generation module thereof, and the thermoelectric power generation module comprises a high-temperature thermoelectric unit, a medium-temperature thermoelectric unit, a low-temperature thermoelectric unit and a cooling plate. The high-temperature thermoelectric unit, the medium-temperature thermoelectric unit and the low-temperature thermoelectric unit are respectively made into thermoelectric power generation unit elements for different temperatures, and then the thermoelectric power generation unit elements are stacked and connected and then are connected with the cooling plate; wherein the high-temperature thermoelectric unit element, the medium-temperature thermoelectric unit element and the low-temperature thermoelectric unit element, which are laminated and connected, are used independently or in combination as required. According to the preparation method of the thermoelectric power generation module provided by the invention, the prepared thermoelectric power generation module can obtain a high-efficiency thermoelectric effect in a high-temperature region, a medium-temperature region and a low-temperature region, and the industrial requirement that ZT is greater than or equal to 2 can be met in the three temperature regions.

Description

Technical Field

[0001] The present invention relates to the field of thermoelectric power generation, and in particular to a method for preparing a thermoelectric power generation module. Background Art

[0002] Thermoelectric power generation using various heat sources as heat sources has significant advantages such as small equipment and almost no need for daily maintenance, as it does not have movable parts required by hydropower and thermal power. From the perspective of general practicality, the indicator of whether the heat source side (thermoelectric power generation) can be practical is whether the dimensionless index ZT exceeds 1 (when ZT = 1, the hot spot conversion efficiency is about 10%), where Z is the Zeebeck index and T is the absolute temperature. So far, thermoelectric materials of various materials have been studied and developed, but the ZT index mostly hovers below 1.5, which is still far from practical application.

[0003] Practical products require thermoelectric materials with a ZT index of more than 2.0, but such materials are almost non-existent. There are materials with a tendency to increase the ZT index toward 2, such as P-type pb 18 Sb 20 , but P type pb 18 Sb 20 The composition is relatively complex and the cost is significantly higher. Pb and Te are toxic to a certain extent. Working for a long time in a high temperature environment is not environmentally friendly and there is a possibility of releasing certain harmful substances.

[0004] The existing thermoelectric power generation module has high production costs and complex process flow; it is difficult to further improve the performance of the existing thermoelectric power generation module structure; at the same time, the existing technology cannot meet the different temperature conditions of high temperature zone, medium temperature zone or low temperature zone at different time periods. Silicon series materials are not fully utilized, and the power generation efficiency is low. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is that the existing thermoelectric power generation module has high production costs and complex process flow, and cannot meet the different temperature conditions of high temperature zone, medium temperature zone or low temperature zone in different time periods. Therefore, the present invention provides a method for preparing a thermoelectric power generation module, and the prepared thermoelectric power generation module can obtain high-efficiency thermoelectric effect in the high temperature zone, medium temperature zone and low temperature zone, and can achieve the industrial demand of ZT≥2 in the above three temperature zones.

[0006] To achieve the above-mentioned purpose, the present invention provides a method for preparing a thermoelectric power generation module, comprising a high-temperature thermoelectric unit, a medium-temperature thermoelectric unit, a low-temperature thermoelectric unit and a cooling plate, wherein the high-temperature thermoelectric unit, the medium-temperature thermoelectric unit and the low-temperature thermoelectric unit are respectively made into thermoelectric power generation unit elements for different temperatures, and then stacked and connected with the cold end. The stacked thermoelectric unit elements for high temperature, the medium-temperature thermoelectric unit elements and the low-temperature thermoelectric unit elements are used alone or in combination according to the needs.

[0007] Furthermore, the high temperature thermoelectric unit element, the medium temperature thermoelectric unit element, and the low temperature thermoelectric unit element are connected in a stacked manner, including being connected in series or in parallel.

[0008] Furthermore, it also includes a power controller for adjusting voltage and current, and the power controller is connected to the load.

[0009] Furthermore, the high temperature thermoelectric unit is a silicon-germanium alloy series thermoelectric unit.

[0010] Further, the nano silicon powder and the nano germanium powder are fully stirred and mixed in a certain ratio to form nano silicon germanium based powder;

[0011] Using elements M and M′ and silicon powder to make p-type material and n-type material;

[0012] The p-type material and the n-type material are fully mixed with the silicon germanium base powder, and are made into a silicon germanium series thermoelectric unit through a casting mold.

[0013] Furthermore, the medium temperature thermoelectric unit is a calcium silicon alloy series thermoelectric unit.

[0014] Furthermore, firstly, the nano silicon powder and the nano calcium powder are fully stirred and mixed in a certain ratio to form nano calcium silicon-based powder;

[0015] Then, the elements M and M′ are made into p-type material and n-type material with nano silicon powder;

[0016] The p-type material and the n-type material are fully mixed with the calcium silicon base powder, and then made into a calcium silicon series thermoelectric unit through a casting mold.

[0017] Furthermore, the low-temperature thermoelectric unit is a silicon series thermoelectric unit.

[0018] Furthermore, the elements M and M' are made into p-type material and n-type material with nano silicon powder; the p-type material and the n-type material are fully stirred and mixed, and then made into a silicon series thermoelectric unit through a casting mold.

[0019] In a preferred embodiment of the present invention, a thermoelectric power generation module prepared by the above-mentioned method for preparing a thermoelectric power generation module obtains high-efficiency thermoelectric effect in high temperature region, medium temperature region and low temperature region.

[0020] Technical Effects

[0021] The present invention provides a method for preparing a thermoelectric power generation module and a thermoelectric power generation module thereof, which can obtain high-efficiency thermoelectric effect in high-temperature, medium-temperature and low-temperature regions under industrial conditions of a heat source of 1000°C, and can meet the industrial demand of ZT≥2 in the above three temperature ranges, and is suitable for waste heat recovery (about 600-700°C) of nuclear power plants, thermal power plants and biomass power plants, and is of great significance for environmental protection and energy saving; the thermoelectric power generation module is a solid material with stable chemical properties and can be used permanently, and the silicon-based material is non-toxic and environmentally friendly; the thermoelectric power generation units applicable to high-temperature, medium-temperature and low-temperature regions are prepared in a stacked manner, and can maximize the use of energy recovery in production and daily life; the thermoelectric power generation material is nanosized, the resistance between nanoparticles can be reduced to the limit, and the effect is more obvious after hydrogen purification.

[0022] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of a single thermoelectric unit of a preferred embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of a series connection of a single thermoelectric unit according to a preferred embodiment of the present invention;

[0025] Figure 3 It is a schematic diagram of the manufacturing process of different series of thermoelectric units of a preferred embodiment of the present invention;

[0026] Figure 4 It is a schematic diagram of the series connection of thermoelectric unit elements in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] In the following description, specific details such as specific internal procedures and techniques are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0029] The present invention provides a method for preparing a thermoelectric power generation module, including a high-temperature thermoelectric unit, a medium-temperature thermoelectric unit, a low-temperature thermoelectric unit and a cooling plate. The high-temperature thermoelectric unit, the medium-temperature thermoelectric unit and the low-temperature thermoelectric unit are respectively made into thermoelectric power generation unit elements for different temperatures and then stacked and connected. Then the thermoelectric power generation unit is connected to the cold end 2; wherein the stacked thermoelectric unit elements for high temperature, the medium-temperature thermoelectric unit elements and the low-temperature thermoelectric unit elements are used alone or in combination according to needs. For details on the connection of a single thermoelectric unit, see Figure 1 As shown; among them, 1 is load, 2 is cold end, 3 is n-type material, 4 is high temperature hot end, 5 is p-type material, and the arrow indicates the direction of current.

[0030] Specifically, after the annealed thermoelectric unit is inspected for shape and cracks on the outer tube, a series of parameter tests are carried out, including hardness, conductivity σ, heat conduction κ and coefficient S, etc. Different ZT values ​​are calculated and classified according to the ZT values. The qualified thermoelectric unit is introduced into the electrode to form a thermoelectric power generation unit element. The thermoelectric unit for each temperature can be a variety of shapes suitable for the production needs of the heat source site, such as U-shaped or comb-shaped, and different stacking forms are determined according to different usage occasions.

[0031] like Figure 2 As shown in the figure, it is a schematic diagram of a single thermoelectric unit (a single high-temperature thermoelectric unit element / a single medium-temperature thermoelectric unit element / a single low-temperature thermoelectric unit element) connected in series, which consists of two thermoelectric units connected in series. The conductor is made of a material with low resistivity such as copper or aluminum. One end of the conductor is connected to the cold end of the p-type material, and the other end is connected to the cold end of the n-type material. The conductor is used to connect the hot end p-type and n-type materials of the thermoelectric unit between the two thermoelectric units, forming a -pnpn- connection structure. Series and parallel connections will increase its voltage and thermoelectric conversion efficiency. Figure 4As shown, high-temperature thermoelectric unit elements, medium-temperature thermoelectric unit elements, and low-temperature thermoelectric unit elements are stacked and connected, and the stacked materials are all p-type or n-type. The stacked thermoelectric units are connected by wires in series or parallel, and the wires include aluminum wires and copper wires. The wires are connected to the low-temperature conductor, and one side of the low-temperature conductor is connected to the low-temperature p-type or n-type material, and the other side is connected to the cooling plate at the cold end. The heat at the heat source end is transferred to the high-temperature thermoelectric unit, the medium-temperature thermoelectric unit, and the low-temperature thermoelectric unit in turn through the insulating ceramic and the conductor, and finally cooled by the cooling plate at the cold end. The insulating ceramic is silicon nitride, aluminum oxide or boron nitride with good heat transfer. Heat is transferred through the gradient of thermoelectric units of different materials to generate electricity, which makes full use of the heat and increases the voltage and efficiency of power generation. The current and voltage are controlled by the power generation receiving equipment, and different current and voltage outputs are achieved through series or parallel connection so that they can be used for different electrical appliances. As Figure 4 A series diagram is shown. In the manufacturing process of thermoelectric units for high temperature, medium temperature and low temperature, high temperature materials, medium temperature materials and low temperature materials are added to the mold in a certain order, and vacuum hot isostatic pressing sintering is performed to realize thermoelectric units with high temperature, medium temperature and low temperature combinations. In this embodiment, a power controller is also included, which is connected to the load 1 and is used to automatically adjust the voltage and current, and can track the output current and voltage as needed and change at any time.

[0032] like Figure 3 As shown, the low temperature thermoelectric unit is a silicon series thermoelectric unit. Further, the elements M and M' are made into p-type material 5 and n-type material 3 with nano silicon powder; the p-type material and the n-type material are fully stirred and mixed, and made into a silicon series thermoelectric unit through a casting mold. The dimensionless index ZT of the silicon series thermoelectric unit is greater than or equal to 1.5, preferably, ZT-2 to 3.

[0033] Specifically, the nanometal includes nanometal M and M', wherein: the purity of silicon powder is ≥99.9999% and the particle size is ≤600nm; M and M' are metal nanopowders with a purity of ≥99.9% and a particle size of ≤800nm. The nanometal M and M', the metal M is at least one of Li, Sb and Bi; the metal M' is at least one of Al, Ga, In and Ti.

[0034] The following steps are involved:

[0035] Step 100, fully mix and stir high-purity nano silicon powder and nano metal M in a p-type mixing barrel, and fully mix and stir high-purity nano silicon powder and nano metal M' in an n-type mixing barrel for 0.2 to 2 hours. Metals M and M' appear in pairs, and the doping ratio is set to 1 to 50‰, forming a resonant doping intermediate energy band for distinguishing n-type and p-type. Metal M includes n-type materials Li, Sb and Bi, etc., and the added amount is at least one of them; the types of M' include p-type materials Al, Ga, In and Ti, etc., and the added amount is at least one of them. Among them, the purity of high-purity nano silicon powder is set to ≥99.9999%, and the particle size is ≤600nm; the purity of metals M and M' is ≥99.9%, and the particle size is ≤800nm.

[0036] Step 200, the nano-silicon powder and metal M mixture and the nano-silicon powder and metal M' mixture are fully stirred and then introduced into the thermoelectric unit casting mold respectively; the thermoelectric unit casting mold includes a p-type part and an n-type part, and the p-type part and the n-type part are connected.

[0037] Step 300, applying high-intensity pressure to the material in the thermoelectric unit casting mold at atmospheric pressure and room temperature to form a primary fixed shape in the thermoelectric unit casting mold, and the specific pressure intensity setting range is 8-12t / cm 2 The maintenance time is 5 to 15 minutes; then the thermoelectric unit mold is first vacuumed, and when the vacuum degree is lower than 100Pa, heating is started, and high-intensity pressure is applied at the same time to form a dense part in the casting mold; specifically, the thermoelectric unit mold is vacuumed and heated, wherein the vacuum degree is lower than 100Pa, the heating temperature is 1300 to 1400℃, and the heating rate is 20 to 100℃ / min; at the same time, high-intensity pressure is applied in the range of 8 to 12t / cm 2 , preferably 10t / cm 2 The best effect is maintained for 5 to 20 minutes, forming a dense part in the casting mold to form a silicon series thermoelectric unit.

[0038] Step 400, after completion at high temperature, the temperature is gradually lowered to room temperature by program control, taken out from the casting mold, and placed in a vacuum annealing furnace for annealing to remove stress, thereby obtaining a new thermoelectric power generation material. The annealing conditions include a vacuum degree lower than 100Pa and a maximum annealing temperature of 1000°C. The materials are kept at 1000°C and 800°C for 30 minutes each, and at 400°C and 100°C for 60 minutes each. Through different temperature curves, the internal stress is completely released, and new stress is prevented from forming during the cooling process.

[0039] The high temperature thermoelectric unit is a silicon-germanium alloy series thermoelectric unit.

[0040] Further, the nano silicon powder and the nano germanium powder are fully stirred and mixed in a certain proportion to prepare a silicon germanium based alloy mixed powder;

[0041] Using metals M and M′ and silicon powder to make p-type material and n-type material;

[0042] The p-type material and the n-type material are fully mixed with the silicon germanium base powder, and then made into a silicon germanium series thermoelectric unit through a casting mold. The dimensionless index ZT of the silicon germanium series thermoelectric unit is greater than or equal to 1.5, preferably, ZT=2-3.

[0043] Specifically, firstly, nano silicon powder and nano germanium powder are mixed in a certain proportion, and the silicon germanium stoichiometry is 8:0.5-3. After fully stirring the mixed powder, a silicon germanium mixed powder is formed. The optimal value of the silicon germanium stoichiometry is preferably 8:2. The mixture of nano silicon powder and element M and the mixture of nano silicon powder and element M′ are respectively added to the mixed silicon germanium powder to form p-type silicon germanium powder and n-type silicon germanium powder. Then, high-intensity pressure is applied to the material in the thermoelectric unit casting mold at atmospheric pressure and room temperature to form a primary shaping shape in the thermoelectric unit casting mold. The specific pressure intensity setting range is 8-12t / cm 2 The maintenance time is 5 to 15 minutes; then the thermoelectric unit mold is first vacuumed, and when the vacuum degree is lower than 100Pa, heating is started, and high-intensity pressure is applied at the same time to form a dense part in the casting mold; specifically, the thermoelectric unit mold is vacuumed and heated, wherein the vacuum degree is lower than 100Pa, the heating temperature is 1300 to 1400℃, and the heating rate is 20 to 100℃ / min; at the same time, high-intensity pressure is applied in the range of 8 to 12t / cm 2 , preferably 10t / cm 2 The best effect is maintained for 5 to 20 minutes, forming a dense piece in the casting mold to form p-type and n-type silicon germanium thermoelectric units.

[0044] After the high temperature is completed, the annealing process is entered to remove stress and obtain a new thermoelectric power generation material. Among them, the annealing conditions include a vacuum degree lower than 100Pa and a maximum annealing temperature of 1000℃. Keep the temperature at 1000℃ and 800℃ for 30 minutes each, and keep the temperature at 400℃ and 100℃ for 60 minutes each. Through different temperature curves, the internal stress is completely released, and new stress is prevented from forming during the cooling process.

[0045] Furthermore, the medium temperature thermoelectric unit is a calcium silicon alloy series thermoelectric unit.

[0046] Furthermore, firstly, nano silicon powder and nano calcium powder are fully stirred and mixed in a certain proportion to make a calcium silicon based alloy mixed powder;

[0047] Then, the metals M and M′ are made into p-type materials and n-type materials with nano-silicon powder;

[0048] The p-type material and the n-type material are fully mixed with the calcium silicon-based powder, and then made into a calcium silicon series thermoelectric unit through a casting mold. The dimensionless index ZT of the calcium silicon series thermoelectric unit is greater than or equal to 1.5, preferably ZT-2 to 3.

[0049] Specifically, firstly, nano silicon powder and nano calcium powder are mixed in a certain proportion, and the silicon germanium stoichiometry is 10:1.5-3.5. After fully stirring the mixed powder, a silicon calcium mixed powder is formed. The nano silicon powder and element M mixture and the nano silicon powder and element M' mixture are added to the mixed silicon calcium powder to form p-type silicon calcium powder and n-type silicon calcium powder. Then, high-intensity pressure is applied to the material in the thermoelectric unit casting mold at atmospheric pressure and room temperature to form a primary shaping shape in the thermoelectric unit casting mold. The specific pressure intensity setting range is 8-12t / cm 2 The maintenance time is 5 to 15 minutes; then the thermoelectric unit mold is first vacuumed, and when the vacuum degree is lower than 100Pa, heating is started, and high-intensity pressure is applied at the same time to form a dense part in the casting mold; specifically, the thermoelectric unit mold is vacuumed and heated, wherein the vacuum degree is lower than 100Pa, the heating temperature is 1300 to 1400℃, and the heating rate is 20 to 100℃ / min; at the same time, high-intensity pressure is applied in the range of 8 to 12t / cm 2 , preferably 10t / cm 2 The best effect is maintained for 5 to 20 minutes, forming a dense piece in the casting mold to form p-type and n-type calcium silicon thermoelectric units.

[0050] After the high temperature is completed, the annealing process is entered to remove stress and obtain a new thermoelectric power generation material. Among them, the annealing conditions include a vacuum degree lower than 100Pa and a maximum annealing temperature of 1000℃. Keep the temperature at 1000℃ and 800℃ for 30 minutes each, and keep the temperature at 400℃ and 100℃ for 60 minutes each. Through different temperature curves, the internal stress is completely released, and new stress is prevented from forming during the cooling process.

[0051] In a preferred embodiment of the present invention, a thermoelectric power generation module prepared by the above-mentioned method for preparing a thermoelectric power generation module obtains high-efficiency thermoelectric effect in high temperature region, medium temperature region and low temperature region.

[0052] The thermoelectric power generation module provided by the embodiment of the present invention, when used in the high temperature field of 700-1000°C, is made by stacking the high temperature thermoelectric unit, the medium temperature thermoelectric unit and the low temperature thermoelectric unit, which significantly improves the practical effect. Secondly, when used for the medium temperature heat source of 400-700°C, the medium temperature thermoelectric unit and the low temperature thermoelectric unit are stacked to form a thermoelectric unit; when used for the low temperature heat source below 400°C, only the low temperature heat unit is used.

[0053] In addition, the low-temperature thermoelectric unit provided in the embodiment of the present invention can be made into a Peltier thermoelectric object (Peltier Thermoelectric Effect), which can be used in compressor-free refrigeration and freezing equipment or can be used in vibration-free air conditioners through voltage reversal. In addition, the low-temperature thermoelectric power generation unit can also be used in power generation devices for the moon and Mars.

[0054] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for preparing a thermoelectric power generation module, characterized in that: It includes a high-temperature thermoelectric unit, a medium-temperature thermoelectric unit, a low-temperature thermoelectric unit and a cooling plate. The high-temperature thermoelectric unit, the medium-temperature thermoelectric unit and the low-temperature thermoelectric unit are respectively made into thermoelectric power generation unit elements for different temperatures, which are stacked and connected, and then connected to the cold end; wherein the stacked thermoelectric unit elements for high temperature, the medium-temperature thermoelectric unit elements and the low-temperature thermoelectric unit elements are used alone or in combination according to needs.

2. A method for preparing a thermoelectric power generation module according to claim 1, characterized in that: The high-temperature thermoelectric unit element, the medium-temperature thermoelectric unit element, and the low-temperature thermoelectric unit element are connected in a stacked manner, including being connected in series or in parallel.

3. The method for preparing a thermoelectric power generation module according to claim 1, characterized in that: The device also includes a power controller for adjusting voltage and current, and the power controller is connected to a load.

4. The method for preparing a thermoelectric power generation module according to claim 1, characterized in that: The high temperature thermoelectric unit is a silicon-germanium alloy series thermoelectric unit.

5. The method for preparing a thermoelectric power generation module according to claim 4, characterized in that: The nano silicon powder and the nano germanium powder are fully stirred and mixed in a certain proportion to form nano silicon germanium based powder; Using elements M and M′ and silicon powder to make p-type material and n-type material; The p-type material and the n-type material are fully mixed with the silicon germanium base powder, and are made into a silicon germanium series thermoelectric unit through a casting mold.

6. The method for preparing a thermoelectric power generation module according to claim 1, characterized in that: The medium temperature thermoelectric unit is a calcium silicon alloy series thermoelectric unit.

7. A method for preparing a thermoelectric power generation module according to claim 6, characterized in that: Firstly, nano silicon powder and nano calcium powder are fully stirred and mixed in a certain proportion to form nano calcium silicon-based powder; Then, the elements M and M′ are made into p-type material and n-type material with nano silicon powder; The p-type material and the n-type material are fully mixed with the calcium silicon base powder, and then made into a calcium silicon series thermoelectric unit through a casting mold.

8. The method for preparing a thermoelectric power generation module according to claim 1, characterized in that: The low-temperature thermoelectric unit is a silicon series thermoelectric unit.

9. A method for preparing a thermoelectric power generation module according to claim 8, characterized in that: Elements M and M' are made into p-type material and n-type material with nano silicon powder; the p-type material and the n-type material are fully stirred and mixed, and then made into silicon series thermoelectric units through a casting mold.

10. A thermoelectric power generation module prepared by the method for preparing a thermoelectric power generation module according to any one of claims 1 to 9, characterized in that: High-efficiency thermoelectric effect is obtained in high-temperature, medium-temperature and low-temperature regions.

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