Application of LaSrMnO3-based magnetocaloric effect material in thermomagnetic power generation

Abstract

The invention belongs to the technical field of thermomagnetic power generation, and relates to application of a LaSrMnO3-based magnetocaloric effect material in thermomagnetic power generation. The structural general formula of the LaSrMnO3-based magnetocaloric effect material is perovskite of La < 0.7 > Sr < 0.3 > Mn < 1-x > RxO3, R represents one of Ti, Cr, Mn, Fe, Co, Ni and Cu, and x is 0-0.05; the LaSrMnO3-based magnetocaloric effect material is obtained by adopting a solid phase sintering method. The LaSrMnO3-based magnetothermal effect material has appropriate Curie temperature and large magnetic entropy change, and is beneficial to waste heat recycling, such as waste heat power generation, especially thermomagnetic power generation by using low-grade waste heat.

Description

Technical Field

[0001] This invention belongs to the field of thermomagnetic power generation technology, and relates to the application of LaSrMnO3-based magnetocaloric effect materials in thermomagnetic power generation. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Thermoelectric conversion technology, which converts heat energy into electrical energy, is considered a promising waste heat recovery technology. Low-grade waste heat (generally gases or liquids at 100-230℃; gases can be flue gas, exhaust gas, waste gas, etc., and liquids can be industrial waste liquids such as chemical waste liquids and high-concentration organic waste liquids) accounts for about 60% of total waste heat; however, its recovery faces significant technical challenges. Due to its high proportion, how to efficiently recover low-grade waste heat has become the core direction of current waste heat recovery technology research. Ferromagnetic-paramagnetic phase change thermomagnetic power generation technology based on magnetocaloric materials can theoretically achieve a Carnot efficiency of up to 55%, demonstrating strong potential.

[0004] Magnetothermal materials with suitable Curie temperatures are crucial for energy conversion in thermomagnetic power generation devices. Furthermore, the magnetocaloric materials used generally need to exhibit a large magnetic entropy change under low magnetic fields. A larger magnetic entropy change helps increase the energy storage during phase transitions, improving the energy conversion efficiency of the magnetocaloric material in thermomagnetic power generation and resulting in better output performance. Phase transitions are achieved through periodic changes at the Curie temperature, converting thermal energy into magnetic energy. The resulting change in magnetic flux is then converted into electrical energy according to the law of electromagnetic induction.

[0005] Generally, the Curie temperature is the minimum temperature for waste heat recovery. A lower Curie temperature is beneficial for increasing the range of waste heat recovery, but an excessively low Curie temperature makes it difficult to cool the material and transition it from a ferromagnetic state to a paramagnetic state. Studies have shown that when the Curie temperature of a magnetocaloric material is around 350K, it is not conducive to the utilization of waste heat from 100 to 230℃, and room temperature gas or water can be used as a cooling medium, thus facilitating the practical application of low-grade waste heat in thermomagnetic power generation. However, the current availability of magnetocaloric materials suitable for low-grade waste heat thermomagnetic power generation limits its development. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide the application of LaSrMnO3-based magnetocaloric materials in thermomagnetic power generation. These LaSrMnO3-based magnetocaloric materials possess suitable Curie temperatures and large magnetic entropy changes, which are beneficial for waste heat recovery and utilization, such as waste heat power generation, especially the use of low-grade waste heat for thermomagnetic power generation.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: An application of LaSrMnO3-based magnetocaloric material in thermomagnetic power generation, wherein the general structural formula of the LaSrMnO3-based magnetocaloric material is La 0.7 Sr 0.3 Mn 1-x R x The perovskite of O3, wherein R represents one of Ti, Cr, Mn, Fe, Co, Ni, and Cu, and x is 0 to 0.05; the LaSrMnO3-based magnetocaloric material is obtained by solid-state sintering.

[0008] Mn occupies the body center of a cubic lattice, typically with a coordination number of 6. O ions are located at the face centers of the cube, forming Mn-O octahedra with the Mn-site ions. The Mn-O octahedral structure provides the possibility for the entry of larger molecules, which is the theoretical basis for ion doping of perovskite manganese oxides.

[0009] The cubic structure with space group pm3m is the ideal structure for perovskites. In actual doping processes, perovskite manganese oxides usually deviate from the ideal cubic structure and become orthorhombic or rhombohedral, thereby altering the magnetocaloric properties of the material.

[0010] The heat source for the thermomagnetic power generation is waste heat. In some embodiments, the heat source is low-grade waste heat. The LaSrMnO3-based magnetocaloric material obtained by the solid-state sintering method of this invention has a Curie temperature of 340~360K, and power generation can be achieved at a cold source temperature near room temperature. Simultaneously, this material exhibits a relatively sharp peak at the Curie temperature and a large dM / dT value. During thermomagnetic power generation, a small temperature difference can generate a large change in magnetic flux, which is beneficial for the thermomagnetic power generation device to obtain a larger output voltage and output power. Therefore, it is a good magnetocaloric power generation material for room temperature range. Furthermore, the maximum magnetic entropy change of this material under a magnetic field change of 0-1.5T can reach 2.3J / (kg·K), exhibiting a good magnetocaloric effect, which is conducive to its further development in low-grade waste heat recovery applications.

[0011] The beneficial effects of this invention are as follows: (1) The experiment of this invention found that the LaSrMnO3-based magnetocaloric material prepared by solid-state sintering has a large room temperature magnetocaloric effect, the Curie temperature is close to room temperature, and the maximum magnetic entropy change under a magnetic field change of 0~1.5T is 2.3J / (kg·K), which is beneficial to use low-grade waste heat for thermomagnetic power generation.

[0012] (2) The solid-state sintering method used in this invention to prepare LaSrMnO3-based magnetocaloric materials is relatively simple, with straightforward operation steps and a short reaction cycle, which can effectively improve production efficiency. During the preparation process, the raw material cost is low, and there is no environmental pollution, meeting the requirements of green manufacturing. At the same time, this process has low energy consumption, which helps to reduce production costs. Due to its stability and operability, it is suitable for large-scale industrial production. Attached Figure Description

[0013] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0014] Figure 1 La synthesized in Examples 2, 4, and 7 of this invention 0.7 Sr 0.3 MnO3, La 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3 and La 0.7 Sr 0.3 Mn 0.98 Ni 0.02 XRD pattern of O3; Figure 2 This is the synthesis of La in Example 2 of the present invention. 0.7 Sr 0.3 EDS-Mapping spectrum of MnO3, where (a) is La 0.7 Sr 0.3 FESEM image of MnO3, (b) is La 0.7 Sr 0.3 EDS diagrams for each element of MnO3: (c) is the mapping diagram for the La element, (d) is the mapping diagram for the Sr element, (e) is the mapping diagram for the Mn element, and (f) is the mapping diagram for the O element. Figure 3 This is the synthesis of La in Example 4 of the present invention. 0.7 Sr 0.3 Mn 0.98 Co 0.02 EDS-Mapping of O3, where (a) is La 0.7 Sr 0.3 Mn 0.98 Co 0.02 FESEM plot of O3, (b) is La 0.7 Sr 0.3 Mn 0.98 Co 0.02EDS diagrams for each element of O3: (c) is the mapping diagram for the La element, (d) is the mapping diagram for the Sr element, (e) is the mapping diagram for the Mn element, (f) is the mapping diagram for the O element, and (g) is the mapping diagram for the Co element. Figure 4 This is the synthesis of La in Example 7 of the present invention. 0.7 Sr 0.3 Mn 0.98 Ni 0.02 EDS-Mapping of O3, where (a) is La 0.7 Sr 0.3 Mn 0.98 Ni 0.02 FESEM plot of O3, (b) is La 0.7 Sr 0.3 Mn 0.98 Ni 0.02 EDS diagrams for each element of O3: (c) is the mapping diagram for La element, (d) is the mapping diagram for Sr element, (e) is the mapping diagram for Mn element, (f) is the mapping diagram for O element, and (g) is the mapping diagram for Ni element. Figure 5 This is the synthesis of La in Example 2 of the present invention. 0.7 Sr 0.3 MnO3's MT plot and its dM / dT differential plot (inset); Figure 6 This is the synthesis of La in Example 4 of the present invention. 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3's MT plot and its dM / dT differential plot (inset); Figure 7 This is the synthesis of La in Example 7 of the present invention. 0.7 Sr 0.3 Mn 0.98 Ni 0.02 O3's MT plot and its dM / dT differential plot (inset); Figure 8 This is the synthesis of La in Example 2 of the present invention. 0.7 Sr 0.3 MH diagram of MnO3; Figure 9 This is the synthesis of La in Example 4 of the present invention. 0.7 Sr 0.3 Mn 0.98 Co 0.02 MH diagram of O3; Figure 10 This is the synthesis of La in Example 7 of the present invention.0.7 Sr 0.3 Mn 0.98 Ni 0.02 MH diagram of O3; Figure 11 This is the synthesis of La in Example 2 of the present invention. 0.7 Sr 0.3 Magnetic entropy change diagram of MnO3 under a 1.5T magnetic field; Figure 12 This is the synthesis of La in Example 4 of the present invention. 0.7 Sr 0.3 Mn 0.98 Co 0.02 Magnetic entropy change diagram of O3 under a 1.5T magnetic field; Figure 13 This is the synthesis of La in Example 7 of the present invention. 0.7 Sr 0.3 Mn 0.98 Ni 0.02 Magnetic entropy change diagram of O3 under a 1.5T magnetic field. Detailed Implementation

[0015] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0016] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0017] This invention proposes the application of LaSrMnO3-based magnetocaloric materials in thermomagnetic power generation.

[0018] A typical embodiment of the present invention provides an application of LaSrMnO3-based magnetocaloric material in thermomagnetic power generation, wherein the general structural formula of the LaSrMnO3-based magnetocaloric material is La 0.7 Sr 0.3 Mn 1-x R x The perovskite of O3, wherein R represents one of Ti, Cr, Mn, Fe, Co, Ni, and Cu, and x is 0 to 0.05; the LaSrMnO3-based magnetocaloric material is obtained by solid-state sintering.

[0019] In some embodiments, the heat source for the thermomagnetic power generation is low-grade waste heat. The low-grade waste heat described in this invention refers to a gas or liquid with a temperature of 100~230℃; wherein the gas can be flue gas, tail gas, exhaust gas, etc., and the liquid can be industrial waste liquid such as chemical waste liquid or high-concentration organic waste liquid.

[0020] x can be 0, 0.01, 0.02, 0.03, 0.04, or 0.05. In some embodiments, x is 0.01 to 0.05. Further, x is 0.01 to 0.03, 0.015 to 0.025, etc.

[0021] In some embodiments, the process of preparing LaSrMnO3-based magnetocaloric materials using solid-state sintering involves: mixing the raw materials according to stoichiometric ratios and sintering them once, then grinding them and sintering them a second time to obtain the final product. This two-stage sintering process improves the crystallinity of the material and better ensures a single phase.

[0022] The raw materials include lanthanum compounds, strontium compounds, manganese compounds, and R compounds; wherein, lanthanum compounds are compounds containing only one metal element, and the metal element is lanthanum, such as lanthanum carbonate, lanthanum oxide, etc.; strontium compounds are compounds containing only one metal element, and the metal element is strontium, such as strontium carbonate, strontium oxide, etc.; manganese compounds are compounds containing only one metal element, and the metal element is manganese, such as manganese carbonate, manganese oxide, etc.; and R compounds are compounds containing only one metal element, and the metal element is R, such as carbonates of R, oxides of R, etc.

[0023] Specifically, the raw materials are oxides of lanthanum oxide, strontium carbonate, manganese carbonate, and R. Studies have shown that materials made from these raw materials perform better.

[0024] Specifically, the mixing before primary sintering includes grinding, with a grinding time of no less than 2 hours. The grinding time can be 3 hours, 4 hours, 5 hours, etc. By controlling the grinding time, it can be ensured that all raw materials can fully contact each other, which is beneficial for nucleation of the solid-phase reaction and crystal growth. More specifically, the mixing before primary sintering involves sequential grinding and ball milling. This mixing method is more conducive to the mixing of various materials.

[0025] Specifically, the temperature of the first sintering should not be higher than the temperature of the second sintering.

[0026] Specifically, the heating rate for a single sintering operation is 3~4 °C min. -1 .

[0027] Specifically, the sintering temperature is 800~1200℃. More specifically, the sintering time is 10~15 hours.

[0028] Specifically, the heating rate for the secondary sintering is 3~4 ℃ min. -1 .

[0029] Specifically, the temperature for the second sintering is 1200~1300℃. More specifically, the time for the second sintering is 15~18 hours.

[0030] Both the primary sintering and the secondary sintering described in this invention can be carried out in a sintering furnace, which can be a muffle furnace, a tube furnace, or the like.

[0031] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0032] Example 1 Magnetothermic materials La 0.7 Sr 0.3 MnO3 is prepared through the following steps: (1) 14 mmol La2O3, 12 mmol SrCO3 and 40 mmol MnCO3 were ground in a mortar for 2 hours and then mixed in a ball mill for 30 minutes to obtain a uniform material.

[0033] (2) Place the homogeneous material obtained in step (1) into a corundum crucible and heat it at 3.5℃ for 1 minute. -1 The crucible was placed in a muffle furnace at a heating rate of 800℃ and sintered in air for 15 hours to obtain sintered powder.

[0034] (3) Transfer the sintered powder obtained in step (2) into a mortar and grind it thoroughly for 30 minutes to obtain fine powder.

[0035] (4) Place the fine powder obtained in step (3) in a corundum crucible and heat it at 3.5℃ for 1 minute. -1 At a heating rate of 1200℃, the crucible was placed in a muffle furnace and sintered in air for 18 hours to obtain the magnetocaloric material La. 0.7 Sr 0.3 MnO3.

[0036] Example 2 Magnetothermic materials La 0.7 Sr 0.3 MnO3 is prepared through the following steps: (1) 14 mmol La2O3, 12 mmol SrCO3 and 40 mmol MnCO3 were ground in a mortar for 2 hours and then mixed in a ball mill for 30 minutes to obtain a uniform material.

[0037] (2) Place the homogeneous material obtained in step (1) into a corundum crucible and heat it at 3.5℃ for 1 minute. -1 The crucible was placed in a muffle furnace at a heating rate of 900℃ and sintered in air for 15 hours to obtain sintered powder.

[0038] (3) Transfer the sintered powder obtained in step (2) into a mortar and grind it thoroughly for 30 minutes to obtain fine powder.

[0039] (4) Place the fine powder obtained in step (3) in a corundum crucible and heat it at 3.5℃ for 1 minute. -1 At a heating rate of 1200℃, the crucible was placed in a muffle furnace and sintered in air for 18 hours to obtain the magnetocaloric material La. 0.7 Sr 0.3 MnO3.

[0040] Example 3 Magnetothermic materials La 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3 is prepared through the following steps: (1) 14 mmol La2O3, 12 mmol SrCO3, 39.2 mmol MnCO3 and 0.08 mmol CoO were ground in a mortar for 2 hours and then mixed in a ball mill for 30 minutes to obtain a uniform material.

[0041] (2) Place the homogeneous material obtained in step (1) into a corundum crucible and heat it at 3.5℃ for 1 minute. -1 The crucible was placed in a muffle furnace at a heating rate of 900℃ and sintered in air for 15 hours to obtain sintered powder.

[0042] (3) Transfer the sintered powder obtained in step (2) into a mortar and grind it thoroughly for 30 minutes to obtain fine powder.

[0043] (4) Place the fine powder obtained in step (3) in a corundum crucible and heat it at 3.5℃ for 1 minute. -1 At a heating rate of 1200℃, the crucible was placed in a muffle furnace and sintered in air for 18 hours to obtain the magnetocaloric material La. 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3.

[0044] Example 4 Magnetothermic materials La 0.7 Sr 0.3 Mn 0.98 Co0.02 O3 is prepared through the following steps: (1) 14 mmol La2O3, 12 mmol SrCO3, 39.2 mmol MnCO3 and 0.08 mmol CoO were ground in a mortar for 2 hours and then mixed in a ball mill for 30 minutes to obtain a uniform material.

[0045] (2) Place the homogeneous material obtained in step (1) into a corundum crucible and heat it at 3.5℃ for 1 minute. -1 The crucible was placed in a muffle furnace at a heating rate of 1000℃ and sintered in air for 15 hours to obtain sintered powder.

[0046] (3) Transfer the sintered powder obtained in step (2) into a mortar and grind it thoroughly for 30 minutes to obtain fine powder.

[0047] (4) Place the fine powder obtained in step (3) in a corundum crucible and heat it at 3.5℃ for 1 minute. -1 At a heating rate of 1200℃, the crucible was placed in a muffle furnace and sintered in air for 18 hours to obtain the magnetocaloric material La. 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3.

[0048] Example 5 Magnetothermic materials La 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3 is prepared through the following steps: (1) 14 mmol La2O3, 12 mmol SrCO3, 39.2 mmol MnCO3 and 0.08 mmol CoO were ground in a mortar for 2 hours and then mixed in a ball mill for 30 minutes to obtain a uniform material.

[0049] (2) Place the homogeneous material obtained in step (1) into a corundum crucible and heat it at 3.5℃ for 1 minute. -1 The crucible was placed in a muffle furnace at a heating rate of 1200℃ and sintered in air for 15 hours to obtain sintered powder.

[0050] (3) Transfer the sintered powder obtained in step (2) into a mortar and grind it thoroughly for 30 minutes to obtain fine powder.

[0051] (4) Place the fine powder obtained in step (3) in a corundum crucible and heat it at 3.5℃ for 1 minute. -1At a heating rate of 1200℃, the crucible was placed in a muffle furnace and sintered in air for 18 hours to obtain the magnetocaloric material La. 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3.

[0052] Example 6 Magnetothermic materials La 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3 is prepared through the following steps: (1) 14 mmol La2O3, 12 mmol SrCO3, 39.2 mmol MnCO3 and 0.08 mmol CoO were ground in a mortar for 2 hours and then mixed in a ball mill for 30 minutes to obtain a uniform material.

[0053] (2) Place the homogeneous material obtained in step (1) into a corundum crucible and heat it at 3.5℃ for 1 minute. -1 The crucible was placed in a muffle furnace at a heating rate of 1200℃ and sintered in air for 15 hours to obtain sintered powder.

[0054] (3) Transfer the sintered powder obtained in step (2) into a mortar and grind it thoroughly for 30 minutes to obtain fine powder.

[0055] (4) Place the fine powder obtained in step (3) in a corundum crucible and heat it at 3.5℃ for 1 minute. -1 At a heating rate of 1300℃, the crucible was placed in a muffle furnace and sintered in air for 16 hours to obtain the magnetocaloric material La. 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3.

[0056] Example 7 Magnetothermic materials La 0.7 Sr 0.3 Mn 0.98 Ni 0.02 O3 is prepared through the following steps: (1) 14 mmol La2O3, 12 mmol SrCO3, 39.2 mmol MnCO3 and 0.04 mmol Ni2O3 were ground in a mortar for 2 hours and then mixed in a ball mill for 30 minutes to obtain a uniform material.

[0057] (2) Place the homogeneous material obtained in step (1) into a corundum crucible and heat it at 3.5℃ for 1 minute.-1 The crucible was placed in a muffle furnace at a heating rate of 1000℃ and sintered in air for 12 hours to obtain sintered powder.

[0058] (3) Transfer the sintered powder obtained in step (2) into a mortar and grind it thoroughly for 30 minutes to obtain fine powder.

[0059] (4) Place the fine powder obtained in step (3) in a corundum crucible and heat it at 3.5℃ for 1 minute. -1 At a heating rate of 1250℃, the crucible was placed in a muffle furnace and sintered in air for 16 hours to obtain the magnetocaloric material La. 0.7 Sr 0.3 Mn 0.98 Ni 0.02 O3.

[0060] Example 8 Magnetothermic materials La 0.7 Sr 0.3 Mn 0.98 Ni 0.02 O3 is prepared through the following steps: (1) 14 mmol La2O3, 12 mmol SrCO3, 39.2 mmol MnCO3 and 0.04 mmol Ni2O3 were ground in a mortar for 2 hours and then mixed in a ball mill for 30 minutes to obtain a uniform material.

[0061] (2) Place the homogeneous material obtained in step (1) into a corundum crucible and heat it at 3.5℃ for 1 minute. -1 The crucible was placed in a muffle furnace at a heating rate of 1100℃ and sintered in air for 12 hours to obtain sintered powder.

[0062] (3) Transfer the sintered powder obtained in step (2) into a mortar and grind it thoroughly for 30 minutes to obtain fine powder.

[0063] (4) Place the fine powder obtained in step (3) in a corundum crucible and heat it at 3.5℃ for 1 minute. -1 At a heating rate of 1250℃, the crucible was placed in a muffle furnace and sintered in air for 16 hours to obtain the magnetocaloric material La. 0.7 Sr 0.3 Mn 0.98 Ni 0.02 O3.

[0064] Example 9 Magnetothermic materials La 0.7 Sr 0.3 Mn 0.98 Ni 0.02O3 is prepared through the following steps: (1) 14 mmol La2O3, 12 mmol SrCO3, 39.2 mmol MnCO3 and 0.04 mmol Ni2O3 were ground in a mortar for 2 hours and then mixed in a ball mill for 30 minutes to obtain a uniform material.

[0065] (2) Place the homogeneous material obtained in step (1) into a corundum crucible and heat it at 3.5℃ for 1 minute. -1 The crucible was placed in a muffle furnace at a heating rate of 1100℃ and sintered in air for 12 hours to obtain sintered powder.

[0066] (3) Transfer the sintered powder obtained in step (2) into a mortar and grind it thoroughly for 30 minutes to obtain fine powder.

[0067] (4) Place the fine powder obtained in step (3) in a corundum crucible and heat it at 3.5℃ for 1 minute. -1 At a heating rate of 1300℃, the crucible was placed in a muffle furnace and sintered in air for 15 hours to obtain the magnetocaloric material La. 0.7 Sr 0.3 Mn 0.98 Ni 0.02 O3.

[0068] Example 10 Magnetothermic materials La 0.7 Sr 0.3 Mn 0.98 Ni 0.02 O3 is prepared through the following steps: (1) 14 mmol La2O3, 12 mmol SrCO3, 39.2 mmol MnCO3 and 0.04 mmol Ni2O3 were ground in a mortar for 2 hours and then mixed in a ball mill for 30 minutes to obtain a uniform material.

[0069] (2) Place the homogeneous material obtained in step (1) into a corundum crucible and heat it at 3.5℃ for 1 minute. -1 The crucible was placed in a muffle furnace at a heating rate of 1200℃ and sintered in air for 12 hours to obtain sintered powder.

[0070] (3) Transfer the sintered powder obtained in step (2) into a mortar and grind it thoroughly for 30 minutes to obtain fine powder.

[0071] (4) Place the fine powder obtained in step (3) in a corundum crucible and heat it at 3.5℃ for 1 minute. -1At a heating rate of 1300℃, the crucible was placed in a muffle furnace and sintered in air for 15 hours to obtain the magnetocaloric material La. 0.7 Sr 0.3 Mn 0.98 Ni 0.02 O3.

[0072] Examples 2, 4, and 7: Synthesis of La 0.7 Sr 0.3 MnO3, La 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3 and La 0.7 Sr 0.3 Mn 0.98 Ni 0.02 The XRD pattern of O3 is as follows: Figure 1 As shown, comparison with the standard card reveals a single phase and good crystallinity. Furthermore, through... Figures 2-4 The EDS-Mapping spectra show that La synthesized in Examples 2, 4, and 7 respectively 0.7 Sr 0.3 MnO3, La 0.7 Sr 0.3 Mn 0.98 Co 0.02 O3 and La 0.7 Sr 0.3 Mn 0.98 Ni 0.02 O3, and the elements are evenly distributed.

[0073] The MT plot and its dM / dT differential plot show that the La synthesized in Example 2 0.7 Sr 0.3 The Curie temperature of MnO3 is 356K, and the La synthesized in Example 4... 0.7 Sr 0.3 Mn 0.98 Co 0.02 The Curie temperature of O3 is 344 K; the La synthesized in Example 7 0.7 Sr 0.3 Mn 0.98 Ni 0.02 The Curie temperature of O3 is 344K.

[0074] Example 2 Synthesized La 0.7 Sr 0.3 When MnO3 is in a ferromagnetic state below the Curie temperature, it essentially reaches saturation magnetization in an external magnetic field of 0.2 T. The external magnetic field required for the ferromagnetic sample to reach saturation magnetization corresponds to the external magnetic field required in the thermomagnetic power generation process, such as... Figure 8 As shown.

[0075] Example 4 Synthesized La 0.7 Sr 0.3 Mn 0.98 Co 0.02 When O3 is in a ferromagnetic state below the Curie temperature, it essentially reaches saturation magnetization in an external magnetic field of 0.2 T. The external magnetic field required for a ferromagnetic sample to reach saturation magnetization corresponds to the external magnetic field required in the thermomagnetic power generation process. Figure 9 As shown.

[0076] Example 7 Synthesized La 0.7 Sr 0.3 Mn 0.98 Ni 0.02 When O3 is in a ferromagnetic state below the Curie temperature, it essentially reaches saturation magnetization in an external magnetic field of 0.2 T. The external magnetic field required for a ferromagnetic sample to reach saturation magnetization corresponds to the external magnetic field required in the thermomagnetic power generation process. Figure 10 As shown.

[0077] Figure 11 This indicates that the La synthesized in Example 2 0.7 Sr 0.3 The maximum magnetic entropy change of MnO3 under a magnetic field of 1.5T is 1.3 J / (kg·K).

[0078] Figure 12 This indicates that the La synthesized in Example 4 0.7 Sr 0.3 Mn 0.98 Co 0.02 The maximum magnetic entropy change of O3 under a 1.5T magnetic field is 1.1 J / (kg·K).

[0079] Figure 13 This indicates that Example 7 synthesized La 0.7 Sr 0.3 Mn 0.98 Ni 0.02 The maximum magnetic entropy change of O3 under a 1.5T magnetic field is 2.3J / (kg·K).

[0080] Example 11 A magnetocaloric power generation device includes an external magnetic field, a low-grade waste heat source, a cooling water source, and a power generation chamber. A columnar structure is installed inside the power generation chamber. The columnar structure is made of a magnetocaloric effect material prepared in Example 4 (or Example 2, Example 7). A magnetically inductive conductive coil is wound around the surface of the columnar structure. A cooling water heat exchanger pipe is installed inside the power generation chamber. The low-grade waste heat source supplies low-grade waste heat into the power generation chamber to heat the columnar structure inside the chamber. The cooling water source supplies cooling water to the cooling water heat exchanger pipe inside the power generation chamber to cool the columnar structure inside the chamber.

[0081] The process of thermomagnetic power generation is as follows: (1) Under a certain external magnetic field, low-grade waste heat is transported to the power generation chamber, and the columnar structure in the power generation chamber is heated by the low-grade waste heat until the temperature of the columnar structure is higher than the Curie temperature of the magnetocaloric material.

[0082] (2) When the temperature of the columnar structure is higher than the Curie temperature of the magnetocaloric material, stop supplying low-grade waste heat to the power generation chamber; at the same time, supply cooling water to the cooling water heat exchange tube in the power generation chamber, and cool the columnar structure in the power generation chamber through the cooling water until the temperature of the columnar structure is lower than the Curie temperature of the magnetocaloric material.

[0083] Repeat the above processes (1) and (2). Since the temperature of the columnar structure made of the magnetocaloric material varies around the Curie temperature to achieve the mutual transformation between the paramagnetic and ferromagnetic states, the magnetic field of the magnetocaloric material changes, thereby changing the magnetic flux of the columnar structure made of the magnetocaloric material. The changed magnetic flux generates an induced current by winding a magnetic induction conductive coil on the surface of the columnar structure, thereby realizing thermomagnetic power generation.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An application of a LaSrMnO3-based magnetocaloric material in thermomagnetic power generation, wherein the general structural formula of the LaSrMnO3-based magnetocaloric material is La 0.7 Sr 0.3 Mn 1-x R x O3 perovskite, in which R represents one of Ti, Cr, Mn, Fe, Co, Ni, and Cu, and x is 0 to 0.05; the LaSrMnO3-based magnetocaloric material is obtained by solid-state sintering.

2. The application as described in claim 1, characterized in that, The heat source for the thermomagnetic power generation is low-grade waste heat.

3. The application as described in claim 1, characterized in that, x is between 0.01 and 0.

05.

4. The application as described in claim 1, characterized in that, The process of preparing LaSrMnO3-based magnetocaloric material by solid-state sintering is as follows: the raw materials are mixed according to the stoichiometric ratio and sintered once, then ground and sintered a second time to obtain the final product.

5. The application as described in claim 4, characterized in that, The raw materials are lanthanum oxide, strontium carbonate, manganese carbonate, and oxides of R.

6. The application as described in claim 4, characterized in that, The mixing method before sintering includes grinding, and the grinding time before sintering is not less than 2 hours.

7. The application as described in claim 4, characterized in that, The temperature of the first sintering should not be higher than the temperature of the second sintering.

8. The application as described in claim 4, characterized in that, The heating rate for a single sintering operation is 3-4 °C / min. -1 ; Alternatively, the heating rate for secondary sintering is 3~4 ℃ min. -1 .

9. The application as described in claim 4, characterized in that, The temperature for the first sintering is 800~1200℃; specifically, the temperature for the second sintering is 1200~1300℃.

10. The application as described in claim 9, characterized in that, The sintering time is 10-15 hours. Alternatively, the secondary sintering time is 15-18 hours.

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