Desert sand-based low-cost composite heat storage material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of heat storage materials, in particular to a desert sand-based low-cost composite heat storage material and a preparation method and application thereof.The desert sand, fly ash, magnesium oxide, an adhesive and a modifier serve as raw materials to be subjected to dry grinding to obtain mixed powder, the mixed powder is subjected to tabletting forming to obtain a blank sample, and the blank sample is dried to obtain the desert sand-based low-cost composite heat storage material. And sintering to obtain the desert sand-based low-cost composite heat storage material. The preparation method is simple in operation and low in raw material price, and the obtained composite heat storage material has the advantages of being large in heat storage density, good in heat stability, high in mechanical strength, low in cost and the like, can be used in the fields of solar thermal power generation, industrial waste heat recovery, building energy conservation and the like, and has wide application prospects. Meanwhile, a new way is provided for high-value resource utilization of solid wastes such as desert sand and fly ash.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat storage materials, in particular to a low-cost composite heat storage material based on desert sand and a preparation method and application thereof. BACKGROUND

[0002] Heat storage materials have broad application prospects in the fields of solar energy utilization, industrial waste heat recovery, building energy saving, etc. Traditional heat storage materials such as pure phase change materials and ceramic materials have problems such as high cost, poor thermal stability or insufficient mechanical strength. At the same time, a large amount of solid waste such as fly ash and desert sand is not effectively utilized, causing resource waste and environmental pressure.

[0003] In the prior art, there are various related solutions, for example: CN201710933608.3 proposes a fly ash-based composite phase change heat storage material, which constructs a heat conduction network by using expandable graphite and modified fly ash, and embeds ternary phase change materials, but its process is complex, relies on ultrasonic peeling and acid modification treatment, and has high cost; CN202411173628.1 improves the encapsulation and leakage prevention performance of phase change materials by using a porous ceramic matrix and silica gel secondary sealing method, but high-temperature calcination and pore-forming agent assistance are required in the preparation process, which is complicated and energy-consuming; CN202410925533.4 improves light-heat conversion and moisture resistance by carbon self-growth modification of fly ash and hydrophobic treatment, but still faces problems such as difficulty in preparing porous support body, limited heat conduction performance, etc.; CN202510434597.9 uses fly ash and magnesium oxide as main raw materials, supplemented by sintering aids and heat conduction enhancers, to maintain good thermal performance while reducing cost, but the heat storage density and cycle stability still have room for improvement; CN202510026838.6 uses sand as a seasonal heat storage medium, and the system has high integration, but it focuses more on the construction of energy storage systems, and the improvement of the heat storage performance of the material itself is limited.

[0004] In summary, although the prior art has made some progress in the resource utilization of solid waste and the development of heat storage materials, it still has problems such as complex process, insufficient cost control, and unsatisfactory comprehensive thermal properties. SUMMARY

[0005] In view of the above problems of the prior art, the present application provides a low-cost composite heat storage material based on desert sand and a preparation method and application thereof. The preparation method provided by the present application provides a composite heat storage material which is simple, low in cost and excellent in comprehensive performance, solves the problems of high cost of traditional heat storage materials and low utilization rate of solid waste, and realizes significant improvement in heat storage performance, thermal stability and mechanical strength of the material by using advanced technology.

[0006] To solve the above technical problems, the present application adopts the following technical solutions: A preparation method of a desert sand-based low-cost composite heat storage material, comprising the following steps: Dry grinding desert sand, fly ash, magnesium oxide, a binder, and a modifier to obtain a mixed powder.

[0007] The mixed powder is pressed and formed to obtain a green body sample.

[0008] The green body sample is dried and sintered to obtain the desert sand-based low-cost composite heat storage material.

[0009] In a preferred embodiment of the present application, the mass fraction of desert sand is 20% to 50%, the mass fraction of fly ash is 0% to 60%, the mass fraction of magnesium oxide is 0% to 50%, the mass fraction of the binder is 0% to 25%, and the mass fraction of the modifier is 0% to 20%, totaling 100%.

[0010] In a preferred embodiment of the present application, further, the sum of the mass percentages of desert sand, fly ash, and magnesium oxide in the desert sand-based low-cost composite heat storage material is 100%, wherein the desert sand accounts for 40%, the fly ash accounts for 30%, and the magnesium oxide accounts for 30%. In addition, the mass percentage of the binder kaolin is 5%, and the mass percentage of the modifier nano-copper oxide is 5%. Performance research of this material under high-temperature environment shows that the compressive strength and flexural strength of the desert sand concrete reach a maximum value at a specific replacement rate, indicating that the composite material has good high-temperature resistance.

[0011] In a preferred embodiment of the present application, further, in the desert sand-based low-cost composite heat storage material, the sum of the mass percentages of desert sand, magnesium oxide, and the binder fireclay is 100%, wherein the desert sand accounts for 50%, the magnesium oxide accounts for 25%, and the binder fireclay accounts for 25%. This material utilizes the natural heat storage performance of desert sand, combines the characteristics of magnesium oxide and fireclay, and aims to provide an economical, efficient, and environmentally friendly heat storage solution.

[0012] In a preferred embodiment of the present application, in the desert sand-based low-cost composite heat storage material, the sum of the mass percentages of desert sand, fly ash, and the binder kaolin is 100%, wherein the desert sand accounts for 38%, the fly ash accounts for 57%, and the binder kaolin accounts for 5%.

[0013] In a preferred embodiment of the present application, in the desert sand-based low-cost composite heat storage material, the sum of the mass percentages of desert sand, fly ash, and the binder kaolin is 100%, wherein the desert sand accounts for 38%, the fly ash accounts for 57%, and the binder kaolin accounts for 5%; and the mass percentage of the modifier aluminum oxide is 5%.

[0014] In the preferred embodiment of the present application, most preferably, in the desert sand-based low-cost composite heat storage material, the sum of the mass percentages of desert sand, fly ash, binder kaolin and modifier alumina is 100%, wherein the proportion of desert sand is 43%, the proportion of fly ash is 17%, the proportion of binder kaolin is 23%, and the proportion of modifier alumina is 17%.

[0015] In the preferred embodiment of the present application, the particle size of the desert sand is 50-800 μm, and the SiO2 content is ≥90%.

[0016] In the preferred embodiment of the present application, the fly ash is F-class grade I fly ash, the particle size of the fly ash is 10-500 μm, the particle size of the magnesium oxide is 10-500 μm, and the purity is ≥85%.

[0017] In the preferred embodiment of the present application, the modifier is alumina, expanded graphite or nano-copper oxide heat conduction enhancer; and the binder is kaolin or refractory clay.

[0018] In the preferred embodiment of the present application, the preparation method of the desert sand-based low-cost composite heat storage material comprises the following steps: dry grinding desert sand, fly ash, magnesium oxide, a binder and a modifier to obtain a mixed powder; tabletting the mixed powder to form a green body sample; drying the green body sample, and sintering to obtain the desert sand-based low-cost composite heat storage material.

[0019] In the preferred embodiment of the present application, the fly ash is subjected to calcination pre-burning treatment to remove carbon, and the experimental conditions are calcination at a temperature of 500-900℃ for 0.5-4 h; the pre-treatment of the desert sand is drying, and the drying temperature is 100-200℃, and the drying time is 0.5-4 h.

[0020] In the preferred embodiment of the present application, the drying temperature of the green body sample is 100-200℃, the drying time is 0-4 h, the sintering temperature is 800-1400℃, and the sintering time is 2-12 h.

[0021] In the preferred embodiment of the present application, the pressure in the tabletting is 1-50 MPa, and the pressure holding time is 1-30 min.

[0022] Another object of the present application is the desert sand-based low-cost composite heat storage material prepared by the preparation method.

[0023] The desert sand-based low-cost composite heat storage material can be used in the fields of solar thermal power generation, industrial waste heat recovery and building energy saving.

[0024] Compared with the prior art, the present application has the beneficial effects that: 1. The present application provides a kind of desert sand-based low-cost composite heat storage material, a kind of desert sand-based low-cost composite heat storage material preparation method, with desert sand, fly ash, magnesium oxide, binder and modifier as raw material dry grinding, obtain mixed powder, after the mixed powder is pressed into shape and obtains green body sample, the green body sample is dried, after sintering, obtain desert sand-based low-cost composite heat storage material, the preparation method of the present application simple process, raw material cost is low.

[0025] 2. The high-efficiency heat storage performance of the desert sand-based low-cost composite heat storage material: the heat storage density can reach 300J / g~800J / g, the working temperature range is 300℃~800℃, excellent thermal stability: after 100 times of thermal cycle, the heat storage capacity attenuation rate is <5%, high mechanical strength: compressive strength is greater than or equal to 30MPa, low cost: using desert sand or solid waste as main raw material, through physical and chemical treatment, solar heat storage material with high-efficiency heat storage performance can be prepared. This material is not only environmentally friendly, but also reduces the cost of traditional heat storage materials by more than 30%. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The present application is a desert sand-based low-cost composite heat storage material preparation process flow chart.

[0027] Figure 2 The present application is a desert sand-based low-cost composite heat storage material preparation process flow chart.

[0028] Figure 3 The present application is a desert sand-based low-cost composite heat storage material preparation process flow chart.

[0029] Figure 4 The present application is a desert sand-based low-cost composite heat storage material preparation process flow chart.

[0030] Figure 5 The present application is a desert sand-based low-cost composite heat storage material preparation process flow chart. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described in connection with the preferred embodiments and the accompanying drawings, and obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0032] It should be noted that all the professional terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the protection scope of the present application. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present application can be purchased from the market or prepared by the existing method.

[0033] Embodiment 1 A desert sand-based composite heat storage material with good heat storage performance and more economic, which is made of the following proportion of raw materials, the sum of the mass percentage of desert sand, fly ash and magnesium oxide in the desert sand-based low-cost composite heat storage material is 100%, the proportion of desert sand is 40%, the proportion of fly ash is 30%, and the proportion of magnesium oxide is 30%; the proportion of the binder kaolin is 5% and the proportion of the modifier nano copper oxide is 5% in terms of mass percentage.

[0034] The preparation steps of the heat storage material are as follows: (1) Raw material preparation: prepare the raw materials needed for preparing the desert sand-based low-cost composite heat storage material, including desert sand, fly ash, magnesium oxide, binder and modifier.

[0035] (2) Raw material pretreatment: screen the desert sand to obtain desert sand particles with a particle size of about 150 mesh, wash the desert sand with deionized water to remove clay and organic matter, and then dry at 105℃ for 2 hours to constant weight; for the pretreatment of fly ash and binder, put the fly ash into a muffle furnace, increase the temperature in the furnace to 800℃ at a rate of 10℃ / min, heat for 1 hour to remove carbon; put the binder into a muffle furnace, increase the temperature in the furnace to 800℃ at a rate of 10℃ / min and keep for 1 hour.

[0036] (3) Raw material mixing: add desert sand, fly ash, magnesium oxide, binder kaolin and modifier nano copper oxide into a beaker according to the proportion, and mix them uniformly by stirring.

[0037] (4) Raw material forming: pour the mixed material into a tablet press mold, and perform compression molding operation by a tablet press, the pressure is set to 30t, the pressure holding time is set to 5min, and the formed material is taken out after the pressure holding is completed.

[0038] (5) Green body sintering: the shaped material is placed in a muffle furnace, heated to 1200°C at a heating rate of 10°C / min and held for 8 hours, and finally different thermal properties of desert sand-based composite heat storage materials are obtained.

[0039] Example 2 A desert sand-based composite heat storage material with good heat storage performance and more economic, made of raw materials in the following proportions, the sum of the mass percentages of desert sand, magnesium oxide and binder fireclay is 100%, the desert sand share is 50%, the magnesium oxide share is 25%, and the binder fireclay share is 25%.

[0040] wherein the preparation steps of the heat storage material are: (1) Raw material preparation: prepare the raw materials needed to prepare the desert sand-based low-cost composite heat storage material, including desert sand, magnesium oxide, and binder; the magnesium oxide is an industrial-grade light-burned powder with a purity of more than 98% and a particle size of 10-40 μm.

[0041] (2) Raw material pretreatment: screen the desert sand to obtain desert sand particles with a particle size of about less than 0.1 mm, wash the desert sand with pure water to remove clay and organic matter, and then dry at 105°C for 2 hours to constant weight; for the pretreatment of fly ash and binder, take the fly ash and place it in a muffle furnace, increase the temperature in the furnace to 800°C at a rate of 10°C / min, and heat for 1 hour to remove carbon; take the binder fireclay and place it in a muffle furnace, increase the temperature in the furnace to 800°C at a rate of 10°C / min and hold for 1 hour.

[0042] (3) Raw material mixing: add desert sand, magnesium oxide, and binder fireclay into a beaker in the order of the proportions, and mix them evenly by stirring.

[0043] (4) Raw material shaping: pour the mixed material into a tablet press mold, and perform a compression shaping operation by a tablet press, with a pressure setting of 30t and a pressure holding time setting of 5min, and then take out the shaped material after the pressure holding is completed.

[0044] (5) Green body sintering: dry the shaped green body sample in a constant temperature oven at 105°C for 2 hours until the sample mass remains unchanged, then place the shaped material in a muffle furnace, heat to 1200°C at a heating rate of 10°C / min and hold for 12 hours, and finally obtain different thermal properties of desert sand-based high-temperature solid composite heat storage materials.

[0045] Example 3 The application discloses a desert sand-based composite heat storage material with good heat storage performance and higher economy, which is prepared from raw materials in the following proportion, wherein the sum of mass percentages of the desert sand, fly ash and bonding agent kaolin is 100%, the proportion of the desert sand is 38%, the proportion of the fly ash is 57%, and the proportion of the bonding agent kaolin is 5%.

[0046] The preparation steps of the heat storage material are as follows: (1) Raw material preparation: preparing raw materials needed for preparing the desert sand-based low-cost composite heat storage material, including desert sand, fly ash and a bonding agent.

[0047] (2) Raw material pretreatment: screening the desert sand to obtain desert sand particles with a particle size of about 150 mesh, washing the desert sand with deionized water to remove clay and organic matters, and then drying the desert sand at 105 DEG C for 2 hours until the weight is constant; as for the pretreatment of the fly ash and the bonding agent, the fly ash is put into a muffle furnace, the temperature in the furnace is increased to 800 DEG C at a temperature increasing rate of 10 DEG C / min, and heating is performed for 1 hour to remove carbon; the bonding agent is put into a muffle furnace, the temperature in the furnace is increased to 800 DEG C at a temperature increasing rate of 10 DEG C / min, and the temperature is kept for 1 hour.

[0048] (3) Raw material mixing: the desert sand, the fly ash and the bonding agent kaolin are sequentially added into a beaker according to the proportion, and mixing is performed through stirring.

[0049] (4) Raw material forming: the mixed material after proportioning is poured into a tabletting die, and compression forming operation is performed through a tablet press; and the formed material is taken out after pressure keeping.

[0050] (5) Sintering: the formed material is put into a muffle furnace, heating is performed to 1200 DEG C at a temperature increasing rate of 10 DEG C / min, and the temperature is kept for 8 hours, and finally, desert sand-based high-temperature solid composite heat storage materials with different thermal properties are obtained.

[0051] Example 4 The application discloses a desert sand-based composite heat storage material with good heat storage performance and higher economy, which is prepared from raw materials in the following proportion, wherein the sum of mass percentages of the desert sand, fly ash, bonding agent kaolin and modifier alumina is 100%, the proportion of the desert sand is 36%, the proportion of the fly ash is 54%, the proportion of the bonding agent kaolin is 5%, and the proportion of the modifier alumina is 5%.

[0052] The preparation steps of the heat storage material are as follows: (1) Raw material preparation: preparing raw materials needed for preparing the desert sand-based low-cost composite heat storage material, including desert sand, fly ash and a bonding agent, a modifier.

[0053] (2) Raw material pretreatment: screen the desert sand, obtain desert sand particles with a particle size of about 150 mesh, wash the desert sand with deionized water to remove clay and organic matter, and then dry at 105°C for 2 hours to constant weight; for the pretreatment of fly ash and binder, take the fly ash and put it into a muffle furnace, increase the temperature in the furnace to 800°C at a rate of 10°C / min, heat for 1 hour to remove carbon; take the binder and put it in a muffle furnace, increase the temperature in the furnace to 800°C at a rate of 10°C / min and keep it for 1 hour.

[0054] (3) Raw material mixing: add desert sand, fly ash, binder kaolin, and modifier alumina into a beaker in the order of the ratio, and mix them evenly by stirring.

[0055] (4) Raw material forming: pour the mixed material into a tablet press mold, and perform a compression forming operation by a tablet press, with a pressure setting of 30t and a pressure holding time setting of 5min. After the pressure holding is completed, the formed material is taken out.

[0056] (5) Green body sintering: place the formed material into a muffle furnace, heat to 1200°C at a rate of 10°C / min and keep it for 8 hours, and finally obtain desert sand-based high-temperature solid composite heat storage materials with different thermal properties.

[0057] Example 5 A desert sand-based composite heat storage material with good heat storage performance and better economy is made from the following raw materials, the sum of the mass percentages of the desert sand, fly ash, binder kaolin, and modifier alumina being 100%, wherein the desert sand accounts for 43%, the fly ash accounts for 17%, the binder kaolin accounts for 23%, and the modifier alumina accounts for 17%.

[0058] The preparation steps of the heat storage material are as follows: (1) Raw material preparation: prepare the raw materials needed to prepare the desert sand-based low-cost composite heat storage material, including desert sand, fly ash, binder, and modifier.

[0059] (2) Raw material pretreatment: dry the desert sand in a 110°C drying oven for 2 hours, then screen the desert sand to obtain desert sand particles with a particle size of 100-120 mesh; for the pretreatment of fly ash and binder, take the fly ash and put it into a muffle furnace, increase the temperature in the furnace to 800°C at a rate of 10°C / min, heat for 1 hour to remove carbon; take the binder and put it in a muffle furnace, increase the temperature in the furnace to 800°C at a rate of 10°C / min and keep it for 1 hour.

[0060] (3) Raw material mixing: add desert sand, fly ash, binder kaolin, and modifier alumina into a beaker in the order of the ratio, and mix them evenly by stirring.

[0061] (4) Raw material forming: pour the mixed material into the tablet press mold, and perform compression forming operation by tablet press, the pressure is set to 50t, the pressure is 398.1MPa, and the pressure holding time is set to 5min, and the formed material is taken out after the pressure holding is completed.

[0062] (5) Green body sintering: the formed material is placed in a muffle furnace, heated to 1000℃ at a heating rate of 10℃ / min and kept for 4 hours, and finally different thermal properties of desert sand based high temperature solid composite heat storage materials are obtained.

[0063] Comparative Example 1 The sum of the mass percentages of the desert sand, fly ash, binder kaolin and modifier alumina is 100%, wherein the desert sand accounts for 40%, the fly ash accounts for 13%, the binder kaolin accounts for 20%, and the modifier alumina accounts for 27%.

[0064] The preparation steps of the heat storage material are as follows: (1) Raw material preparation: prepare the raw materials needed to prepare the desert sand based low cost composite heat storage material, including desert sand, fly ash, binder, and modifier.

[0065] (2) Raw material pretreatment: dry the desert sand in a 110℃ drying oven for 2 hours, then screen the desert sand to obtain desert sand particles with a particle size of 100-120 mesh; as for the pretreatment of fly ash and binder, take the fly ash and put it into a muffle furnace, increase the temperature in the furnace to 800℃ at a rate of 10℃ / min, and heat for 1 hour to remove carbon; take the binder and put it in a muffle furnace, increase the temperature in the furnace to 800℃ at a rate of 10℃ / min and keep for 1 hour.

[0066] (3) Raw material mixing: add desert sand, fly ash, binder kaolin and modifier alumina into a beaker according to the proportion, and mix them evenly by stirring.

[0067] (4) Raw material forming: pour the mixed material into the tablet press mold, and perform compression forming operation by tablet press, the pressure is set to 50t, the pressure is 398.1MPa, and the pressure holding time is set to 5min, and the formed material is taken out after the pressure holding is completed.

[0068] (5) Green body sintering: the formed material is placed in a muffle furnace, heated to 1000℃ at a heating rate of 10℃ / min and kept for 4 hours, and finally different thermal properties of desert sand based high temperature solid composite heat storage materials are obtained.

[0069] Further, as for the tablet forming of the material, the mold containing the mixed material is placed in the tablet press, the pressure is set to 50t, the pressure is 398.1MPa, and the pressure holding time is set to 5min.

[0070] Further, regarding the sintering of the shaped material, the desert sand-based composite heat storage material is first placed in a muffle furnace, heated to 1000°C at a heating rate of 10°C / min and held for 4 hours.

[0071] Comparative Example 2 The desert sand, fly ash, binder kaolin, modifier alumina and heavy magnesium oxide are prepared from raw materials in the following proportions, with the sum of the mass percentages of the desert sand, fly ash, binder kaolin, modifier alumina and heavy magnesium oxide being 100%, wherein the proportion of desert sand is 40%, the proportion of fly ash is 20%, the proportion of binder kaolin is 15%, the proportion of modifier alumina is 10%, and the proportion of heavy magnesium oxide is 15%.

[0072] The preparation steps of the heat storage material are as follows: (1) Raw material preparation: prepare the raw materials needed to prepare the desert sand-based low-cost composite heat storage material, including desert sand, fly ash, binder, modifier, and heavy magnesium oxide.

[0073] (2) Raw material pretreatment: dry the desert sand in a 110°C drying oven for 2 hours, then screen the desert sand to obtain desert sand particles with a particle size of 100-120 mesh; regarding the pretreatment of fly ash and binder, place the fly ash in a muffle furnace, increase the temperature in the furnace to 800°C at a rate of 10°C / min, and heat for 1 hour to remove carbon; place the binder in a muffle furnace, increase the temperature in the furnace to 800°C at a rate of 10°C / min, and hold for 1 hour.

[0074] (3) Raw material mixing: add the desert sand, fly ash, binder kaolin, modifier alumina, and heavy magnesium oxide into a beaker according to the proportions, and mix them evenly by stirring.

[0075] (4) Raw material shaping: pour the mixed material into a tablet press mold, and perform a compression shaping operation by a tablet press. After the pressure holding is completed, the shaped material is taken out.

[0076] (5) Sintering of the green body: place the shaped material in a muffle furnace and apply different sintering temperatures and times to finally obtain desert sand-based high-temperature solid composite heat storage materials with different thermal properties.

[0077] Further, regarding the tablet shaping of the material, place the mold containing the mixed material in a tablet press, set the pressure to 50t, the pressure to 398.1MPa, and the pressure holding time to 5min.

[0078] Further, regarding the sintering of the shaped material, the desert sand-based composite heat storage material is first placed in a muffle furnace, heated to 1000°C at a rate of 10°C / min and held for 4 hours.

[0079] Result analysis Table 1. Comparison of compressive strength between embodiments of the present invention and comparative examples. As shown in Table 1, the desert sand-based composite thermal storage material prepared by the present invention has a compressive strength higher than 30 MPa, and also has the characteristics of moderate thermal conductivity, good thermal stability, reasonable density, high specific heat capacity and good formability. The desert sand-based composite thermal storage material prepared by the present invention has high comprehensive performance.

[0080] Figure 1 This is a flowchart of the preparation process of the desert sand-based low-cost composite thermal storage material of the present invention. The process involves raw material preparation, raw material pretreatment, raw material mixing, raw material forming and green body sintering to obtain the desert sand-based low-cost composite thermal storage material.

[0081] like Figure 2 The image shown is a morphological diagram of a circular sample with a diameter of 13 mm and a height of 10 mm. The sample has a smooth and even appearance, without any peeling, slag shedding, or cracks, indicating that sintering at 1200℃ can significantly improve the structural integrity of the sample. The pressure test results show that the sample exhibits excellent load-bearing capacity, with a compressive strength of 33.43 MPa.

[0082] like Figure 3 The image shows the morphology of a circular sample with a diameter of 13 mm. Its appearance is smooth and even, without any peeling, slag shedding, or cracks, indicating that sintering at 1200℃ significantly improves the structural integrity of the sample. The pressure test results show that all samples exhibit excellent load-bearing capacity, with maximum compressive strength generally exceeding 30 MPa.

[0083] like Figure 4 The figure shows the specific heat capacity curve for a circular composite thermal storage material sample with a diameter of 13 mm. The specific heat capacity of the sample increases slowly with increasing temperature. The specific heat capacity of the sample is 0.773 J / (g·K) at 25℃ and 1.109 J / (g·K) at 500℃. The average specific heat capacity of the sample from 25℃ to 500℃ is 0.987 J / (g·K). The density of the thermal storage sample is known to be 1.9 g / cm³. 3 Within the operating temperature range (25℃~500℃), the heat storage density per unit volume of this heat storage sample is 8.9×10⁵ kJ / m³. 3, the unit mass heat storage density is 467J / g, and the heat storage capacity is relatively strong. The sintered sample is subjected to 11 heat storage and release cycle tests, and the results show that the sample quality and density do not change obviously, and the sample is free of defects such as slagging and cracking. The sample after 11 heat storage and release cycles is tested by a pressure testing machine, and the compressive strength is 31.65MPa, indicating that the sample has good cycle heat stability. Considering that the heat conductivity of the heat storage sample is moderate, the heat stability is good, the density is reasonable, the specific heat capacity is relatively high, and the forming property is good, the desert sand-based composite heat storage material prepared by the application has high comprehensive performance, and has significant feasibility and popularization potential in actual engineering application.

[0084] As shown in Figure 5 , it is a compressive curve analysis diagram of a composite heat storage material sample which is rectangular, 40mm long, 30mm wide and 14.2mm high. The test results show that the sample has excellent bearing performance, and the compressive strength is 78.60MPa.

[0085] The desert sand-based composite heat storage material and the preparation method thereof provide a desert sand-based high-temperature solid composite heat storage material with good heat storage performance and higher economy and a preparation method thereof, and have the following beneficial effects: the desert sand-based composite heat storage material with good heat storage performance and higher economy and the preparation method thereof are mixed by desert sand, fly ash, magnesium oxide, a binder kaolin and a heat conduction enhancer, cold-pressed into a shape, and further sintered to obtain a high-temperature composite heat storage material. The desert sand and industrial solid waste fly ash are mixed, the heat storage temperature range of the original magnesium oxide heat storage brick is not affected, the compressive strength can be increased to more than 30MPa, the production cost is greatly reduced, the entire solid heat storage material structure is simple, and the production steps are simple.

[0086] It should be noted that when numerical ranges are involved in the present application, both endpoints of each numerical range and any number between the two endpoints can be selected. Since the same steps and examples are used, the preferred embodiments are described in the present application to prevent redundancy. Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to the embodiments once they understand the basic inventive concept. Therefore, the appended claims are intended to include the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0087] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application also intends to include these modifications and variations.

Claims

1. A method for preparing a low-cost composite thermal storage material based on desert sand, characterized in that, Includes the following steps: The mixture is obtained by dry grinding of desert sand, fly ash, magnesium oxide, binder and modifier. The mixed powder is compressed into tablets to obtain a preform sample; The blank sample was dried and sintered to obtain a low-cost composite heat storage material based on desert sand. The desert sand comprises 20%–50% by mass, fly ash comprises 0%–60% by mass, magnesium oxide comprises 0%–50% by mass, binder comprises 0%–25% by mass, and modifier comprises 0%–20% by mass, totaling 100%.

2. The preparation method of the low-cost composite thermal storage material based on desert sand according to claim 1, characterized in that, The desert sand has a particle size of 50μm to 800μm and a SiO2 content of ≥90%.

3. The preparation method of the low-cost composite thermal storage material based on desert sand according to claim 1, characterized in that, The fly ash particle size is 10μm~500μm; the magnesium oxide particle size is 10μm~500μm, and the purity is ≥85%.

4. The preparation method of the low-cost composite thermal storage material based on desert sand according to claim 1, characterized in that, The modifier is alumina, expanded graphite or nano copper oxide thermal conductivity enhancer; the binder is kaolin or refractory clay.

5. The low-cost composite thermal storage material based on desert sand according to claim 1, characterized in that, Fly ash was pre-calcined to remove carbon, with experimental conditions of calcination at 500℃~900℃ for 0.5h~4h; desert sand was pre-treated by drying at 100℃~200℃ for 0.5h~4h.

6. The low-cost composite thermal storage material based on desert sand according to claim 1, characterized in that, The green body sample is dried at a temperature of 100℃~200℃ for 0 hours to 4 hours, and sintered at a temperature of 800℃~1400℃ for 2 hours to 12 hours.

7. The low-cost composite thermal storage material based on desert sand according to claim 1, characterized in that, The pressure during tableting is 1 MPa to 50 MPa, and the holding time is 1 min to 30 min.

8. A low-cost composite thermal storage material based on desert sand, prepared by the method according to any one of claims 1-7.

9. The application of the desert sand-based low-cost composite thermal storage material according to claim 8 in the fields of solar thermal power generation, industrial waste heat recovery, and building energy conservation.

Images