Preparation method of corn cob / steel slag binary solid waste composite phase change energy storage material

Abstract

The application belongs to the technical field of composite phase change materials, and particularly relates to a preparation method of a corn cob / steel slag binary solid waste composite phase change energy storage material, which comprises the following steps: taking corn cob and steel slag as base matrix raw materials, performing carbonization treatment on the corn cob to construct a porous network cross-linked carbon matrix, performing high-temperature calcination treatment on the steel slag to reconstruct crystals, and mixing and co-sintering to form a binary solid waste framework. A phase change material is loaded into the binary solid waste framework through an immersion adsorption method, and finally the corn cob / steel slag binary solid waste composite phase change energy storage material is obtained. The application realizes resource utilization of solid wastes which are widely sourced and low in cost. The porous structure has adsorption performance and heat conduction performance. The solid waste composite phase change energy storage material prepared by the application has excellent heat storage performance and good stability and is not prone to leakage, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of composite phase change materials technology, and in particular relates to a method for preparing a composite phase change energy storage material based on corn cob / steel slag binary solid waste. Background Technology

[0002] With the continuous exploitation of fossil fuels, environmental problems and resource depletion are becoming increasingly prominent. Phase change energy storage technology, through state changes, achieves energy storage and release, addressing the temporal and spatial mismatch in new energy supply. However, phase change materials are prone to leakage during solid-liquid transitions and have low thermal conductivity, severely impacting the performance and safety of thermal storage systems. Porous frameworks, through their capillary effect and surface tension, enhance the stability of phase change materials within pores, while simultaneously improving thermal conductivity, thermal stability, and chemical stability. Exploring novel composite phase change materials with lower costs and stronger thermal performance is an important research direction in this field.

[0003] Solid waste, through pretreatment, can form unique porous structures with large specific surface areas and adsorption properties, providing a new approach for preparing composite phase change materials. Current research mostly uses single-type solid waste framework materials. For example, Chinese invention patent CN114890811A discloses a method for preparing porous phase change energy storage materials using mining solid waste. This technology mixes organic foam with a slurry of iron tailings and waste rock with additives, sintersties the dried preform, and removes the organic foam at high temperature. This porous ceramic has high mechanical strength, but poor porosity, and the decomposition of the foam releases a large amount of CO2. Chinese invention patent CN113861946A discloses a method for preparing porous carbon composite phase change materials from lotus root biomass. High-temperature carbonization under an argon atmosphere yields porous carbon materials from lotus root. These porous carbon materials have good pore structure and high thermal conductivity, but the bio-based framework has poor compressive and bending resistance, low mechanical strength, and a large coefficient of thermal expansion that may lead to cracking, thus limiting their practical application.

[0004] Therefore, this application needs to provide a method for preparing a corn cob / steel slag binary solid waste composite phase change energy storage material to solve the problems existing in the prior art. Summary of the Invention

[0005] The purpose of this invention is to effectively utilize industrial waste and agricultural waste as a porous framework to overcome the problems of easy leakage and poor thermal conductivity of phase change materials. The invention proposes a method for preparing a corn cob / steel slag binary solid waste composite phase change energy storage material. The solid waste composite phase change energy storage material prepared by this method has a stable shape and good thermal performance and cycle stability.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a composite phase change energy storage material based on corn cob / steel slag binary solid waste, wherein the composite phase change energy storage material comprises a binary porous solid waste framework consisting of a mixture of steel slag material and corn cob carbon material, and a phase change material located inside the porous framework. The preparation method includes the following steps:

[0008] Step 1: Steel slag pretreatment

[0009] Steel slag is placed in a muffle furnace, calcined at high temperature, and then naturally cooled to room temperature. It is then ground into powdered steel slag material for later use.

[0010] Step 2: Pre-treatment of corn cob carbonization

[0011] The crushed corn cobs were dried at a constant temperature to a constant weight, carbonized in a tube furnace according to a heating mechanism, naturally cooled to room temperature, and finally ground into powder to obtain corn cob carbon material samples for later use.

[0012] Step 3: Preparation of a corn cob / steel slag binary porous solid waste framework

[0013] Weigh the steel slag pretreatment material from step 1 and the corn cob carbon material from step 2 according to a certain mass ratio, mix, grind and co-sinter them in a planetary ball mill to prepare a corn cob / steel slag binary porous solid waste skeleton.

[0014] Step 4: Preparation of corn cob / steel slag binary solid waste composite phase change energy storage material

[0015] Weigh the corn cob / steel slag binary porous solid waste skeleton and paraffin wax prepared in step 3 according to a certain mass ratio, set a drying oven at a certain temperature to completely melt the paraffin wax, stir the mixed material at intervals to fully mix the paraffin wax and skeleton material, and cool to room temperature; put the mixed and cooled sample into a mold and press it to obtain the corn cob / steel slag binary solid waste composite phase change energy storage material.

[0016] Furthermore, in step 1, the high-temperature calcination temperature of the muffle furnace is 800℃-900℃, and the calcination time is 8-10 hours, and the particle size of the ground steel slag material is 200-300 mesh.

[0017] Furthermore, in step 2, the crushed corn cob particle size is 2-5 cm, and argon gas with a flow rate of 300 mL / min is introduced into the tubular furnace for 30 min before heating to ensure that an inert atmosphere is formed inside the tubular furnace; the carbonization temperature is 400℃-500℃, the heating rate is 10℃ / min, the holding time is 60 min, and the reaction is naturally cooled to room temperature after completion. During carbonization, the argon gas flow rate is adjusted to 100 mL / min.

[0018] Furthermore, in step 3, the mass ratio of the corn cob carbon material to the steel slag pretreatment material is 2-4:1.

[0019] Furthermore, in step 3, the planetary ball mill rotates at 200 rpm and grinds for 30 minutes.

[0020] Furthermore, in step 3, the co-sintering process of the corn cob carbon material and the steel slag pretreatment material is carried out by nitrogen gas at a flow rate of 200 mL / min, a heating rate of 5℃ / min, and co-pyrolysis at a temperature of 400℃-500℃ for 1 hour.

[0021] Furthermore, in step 4, the mass ratio of the binary porous solid waste skeleton to paraffin is 1-2:1.

[0022] Furthermore, in step 4, the temperature of the drying oven is set to 50°C, and the oven is stirred once every 30 minutes, with a total heat preservation time of 2 hours.

[0023] Furthermore, in step 4, the mold is a cylindrical mold, and the press is pressed at a pressure of 6MPa for 3 minutes.

[0024] By adopting the above technical solution, a mixture of corn cobs and steel slag with porous structures is used as the raw material for preparing porous materials. The unique morphological characteristics and natural structure of corn cobs can form a cylindrical channel structure after drying and carbonization, providing sufficient storage space for phase change materials. Steel slag has certain compressive strength, compensating for the cracking problem of corn cobs caused by the volume expansion of phase change materials. The binary mixture of steel slag and corn cobs complements each other in terms of composition, properties and morphology. The composite phase change material prepared by using binary solid waste to replace the traditional encapsulation framework not only realizes the transtemporal regulated control of energy and improves energy utilization efficiency, but also reduces carbon emissions and environmental pollution caused by the framework production process, promoting the deep integration and circular development of multiple industries in the field of phase change energy storage and the resource utilization of solid waste.

[0025] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention uses agricultural solid waste corn cobs and industrial solid waste steel slag as skeleton materials to realize the resource utilization of industrial and agricultural solid waste, effectively reduce carbon emissions and environmental pollution from solid waste treatment, and the energy storage material combined with phase change material has a stable shape and does not leak, promoting the deep integration and circular development of multiple industries in the field of phase change energy storage and the resource utilization of solid waste.

[0027] 2. This invention optimizes the pore structure of corn cob and steel slag treatment, and effectively encapsulates phase change materials through adsorption impregnation. Experimental results show that this solid waste composite phase change energy storage material can adsorb 30% paraffin wax, has a latent heat of 28.56 J / g, and a thermal conductivity of 0.44 W / (m*K), exhibiting good thermal performance and cycle stability.

[0028] 3. This invention features a simple operating process, minimal capital investment, a short preparation cycle (24 hours), and requires no large-scale instruments or equipment, enabling large-scale automated industrial production. This solid waste composite phase change energy storage material has broad application prospects in thermal management fields such as heat dissipation for electronic devices.

[0029] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, the following detailed description is provided in conjunction with preferred embodiments and accompanying drawings. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0031] Figure 1 This is a SEM image of the corn cob carbon material in this invention;

[0032] Figure 2 This is a SEM image of the corn cob / steel slag binary solid waste composite phase change energy storage material of the present invention;

[0033] Figure 3 This is a macroscopic physical image of the corn cob / steel slag binary solid waste composite phase change energy storage material of the present invention;

[0034] Figure 4 This is a differential scanning calorimetry curve of the corn cob / steel slag binary solid waste composite phase change energy storage material of the present invention;

[0035] Figure 5 This is a macroscopic characterization comparison diagram of the composite phase change material with corn cob / steel slag, corn cob, and steel slag as the skeleton of the present invention. Detailed Implementation

[0036] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this specification. These embodiments illustrate the principles of the invention, and other aspects, features, and advantages of the invention will become apparent from this detailed description. In the accompanying drawings, the same or similar parts in different figures are indicated by the same reference numerals.

[0037] Example 1

[0038] A method for preparing a corn cob / steel slag binary solid waste composite phase change energy storage material comprises the following steps:

[0039] (1) Place crushed corn cobs with a particle size of 2-5 cm in a constant temperature drying oven at 105℃ and dry for 48 hours. After cooling, weigh 10 g of corn cobs and place them in a tube furnace. Heat the furnace at a rate of 10℃ / min to a carbonization temperature of 500℃ and carbonize for 60 min. After stopping heating, allow the mixture to cool naturally to room temperature. Grind the mixture into powder with a particle size of 200 mesh to obtain a corn cob carbon material sample.

[0040] (2) Take 10g of steel slag and place it in a muffle furnace. Calcine it at 900℃ for 8 hours, cool it naturally to room temperature, and grind it into powder with a particle size of 200 mesh.

[0041] (3) Weigh 1g of corn cob charcoal and 1g of steel slag, and grind them in a planetary mill at a speed of 200 rpm for 20 minutes. After mixing and grinding, place the mixture in a tube furnace and heat it to 500℃ for pyrolysis for 1 hour under a nitrogen atmosphere (N2 flow rate of 200 mL / min) at a heating rate of 5℃ / min. After cooling, grind it in a planetary mill at a speed of 200 rpm for 20 minutes to obtain binary solid waste skeleton material.

[0042] (4) Weigh 1g of binary solid waste framework material and 1g of paraffin wax and place them in a beaker. Mix them and place the beaker in a 50℃ drying oven. Keep the oven at this temperature for 2 hours to allow the liquefied paraffin wax to completely melt. Stir the mixture every 30 minutes during this period to ensure that the paraffin wax and the binary solid waste framework material are thoroughly mixed. Cool the mixture to room temperature. Place the mixed and cooled sample into a cylindrical mold and press it at a pressure of 6MPa for 3 minutes to obtain the corn cob / steel slag binary solid waste composite phase change energy storage material.

[0043] (5) Place the prepared corn cob / steel slag binary solid waste composite phase change energy storage material into a 50℃ drying oven to remove the phase change material on the surface or that has not been adsorbed into the pores. Replace the filter paper continuously to ensure that there is no leakage of liquid phase change material.

[0044] The corn cob carbon material prepared in Example 1 was characterized by scanning electron microscopy (SEM) as follows: Figure 2 As shown, carbonized corn cobs form a three-dimensional porous structure; scanning electron microscopy characterization of the corn cob / steel slag solid waste composite phase change energy storage material is as follows. Figure 3 As shown, the pores are filled after paraffin adsorption; the corn cob / steel slag solid waste composite phase change energy storage material was characterized using differential scanning calorimetry (DSC). Figure 4 As shown, the phase change temperature is 28.56℃ and the phase change enthalpy is 32.24J / g, indicating good thermal storage performance. The thermal conductivity of the composite phase change energy storage material of pure paraffin and corn cob / steel slag solid waste was measured at room temperature using a thermal constant analyzer to be 0.21W / (m*K) and 0.44W / (m*K), respectively. Steel slag and corn cob, as porous skeletons, have an effect on improving the thermal conductivity of the phase change material.

[0045] Comparative Example 1

[0046] The preparation method of corn cob solid waste composite phase change energy storage material described in this comparative example consists of the following steps:

[0047] (1) Place crushed corn cobs with a particle size of 2-5 cm in a constant temperature drying oven at 105℃ and dry for 48 hours. After cooling, weigh 10 g of corn cobs and place them in a tube furnace. Heat the furnace at a rate of 10℃ / min to a carbonization temperature of 500℃ and carbonize for 60 min. After stopping heating, allow the mixture to cool naturally to room temperature. Grind the mixture into powder with a particle size of 200 mesh to obtain a corn cob carbon material sample.

[0048] (2) Weigh 1g of corn cob carbon material and 1g of paraffin wax and place them in a beaker. Mix them and place the beaker in a 50℃ drying oven. Keep the oven at this temperature for 2 hours to allow the liquefied paraffin wax to completely melt. Stir the mixture every 30 minutes during this period to ensure that the paraffin wax and corn cob carbon material are thoroughly mixed. Cool the mixture to room temperature. Place the mixed and cooled sample into a cylindrical mold and press it with a press (MSY-50) at a pressure of 6MPa for 3 minutes to obtain the corn cob composite phase change energy storage material.

[0049] Comparative Example 2

[0050] The preparation method of the composite phase change energy storage material based on steel slag solid waste described in this comparative example consists of the following steps:

[0051] (1) Take 10g of steel slag and place it in a muffle furnace. Calcine it at 900℃ for 8 hours, cool it naturally to room temperature, and grind it into powder with a particle size of 200 mesh.

[0052] (2) Weigh 1g of steel slag and 1g of paraffin wax and place them in a beaker. Mix the mixture and place it in a 50℃ drying oven. Keep it at this temperature for 2 hours to allow the liquefied paraffin wax to completely melt. Stir the mixture every 30 minutes during this period to ensure that the paraffin wax and steel slag material are thoroughly mixed. Cool the mixture to room temperature. Place the mixed and cooled sample into a cylindrical mold and press it with a press (MSY-50) at a pressure of 6MPa for 3 minutes to obtain the steel slag composite phase change energy storage material.

[0053] The composite phase change energy storage materials of Example 1, Comparative Example 2, and Comparative Example 3 were macroscopically characterized using a digital camera, and the results are as follows: Figure 5 As shown, the structure of the corn cob / steel slag binary solid waste composite phase change energy storage material is stable and can prevent leakage of phase change materials.

[0054] In summary, this invention utilizes widely available and inexpensive solid waste resources. Its porous structure possesses adsorption and thermal conductivity properties, and the resulting solid waste composite phase change energy storage material exhibits excellent thermal storage performance, good stability, and is not prone to leakage, thus possessing broad application prospects.

[0055] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a corn cob / steel slag binary solid waste composite phase change energy storage material, characterized in that, The composite phase change energy storage material comprises a binary porous solid waste framework consisting of a mixture of steel slag and corn cob carbon, and a phase change material located inside the porous framework. The preparation method includes the following steps: Step 1: Steel slag pretreatment Steel slag is placed in a muffle furnace, calcined at high temperature, and then naturally cooled to room temperature. It is then ground into powdered steel slag material for later use. Step 2: Pre-treatment of corn cob carbonization The crushed corn cobs were dried at a constant temperature to a constant weight, carbonized in a tube furnace according to a heating mechanism, naturally cooled to room temperature, and finally ground into powder to obtain corn cob carbon material samples for later use. Step 3: Preparation of a corn cob / steel slag binary porous solid waste framework Weigh the steel slag pretreatment material from step 1 and the corn cob carbon material from step 2 according to a certain mass ratio, mix, grind and co-sinter them in a planetary ball mill to prepare a corn cob / steel slag binary porous solid waste skeleton. Step 4: Preparation of corn cob / steel slag binary solid waste composite phase change energy storage material Weigh the corn cob / steel slag binary porous solid waste skeleton and paraffin wax prepared in step 3 according to a certain mass ratio, set a drying oven at a certain temperature to completely melt the paraffin wax, stir the mixed material at intervals to fully mix the paraffin wax and skeleton material, and cool to room temperature; put the mixed and cooled sample into a mold and press it to obtain the corn cob / steel slag binary solid waste composite phase change energy storage material. In step 1, the high-temperature calcination temperature of the muffle furnace is 800℃-900℃, and the calcination time is 8-10 hours. The particle size of the ground steel slag material is 200-300 mesh. In step 2, the crushed corn cob particles are 2-5 cm in size. Before heating the tubular furnace, argon gas is introduced at a flow rate of 300 mL / min for 30 min to ensure that an inert atmosphere is formed inside the tubular furnace. The carbonization temperature is 400℃-500℃, the heating rate is 10℃ / min, the holding time is 60 min, and the reaction is allowed to cool naturally to room temperature after the reaction is completed. During carbonization, the argon gas flow rate is adjusted to 100 mL / min. In step 3, the mass ratio of the corn cob carbon material to the steel slag pretreatment material is 2-4:1; In step 3, the planetary ball mill rotates at 200 rpm and the grinding time is 30 min. In step 3, the co-sintering process of the corn cob carbon material and the steel slag pretreatment material is carried out by nitrogen gas with a flow rate of 200 mL / min, a heating rate of 5℃ / min, and co-pyrolysis at a temperature of 400℃-500℃ for 1 hour. In step 4, the mass ratio of the binary porous solid waste skeleton to paraffin is 1-2:1; In step 4, the temperature of the drying oven is set to 50°C, and the oven is stirred once every 30 minutes, with a total heat preservation time of 2 hours. In step 4, the mold is a cylindrical mold, and the press is pressed at 6MPa for 3 minutes.

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