CN114806511A - Movable semi-packaged solid-liquid phase change heat storage material and preparation method and application thereof - Google Patents

Abstract

The invention discloses a movable semi-packaged solid-liquid phase change heat storage material and a preparation method and application thereof. The invention uses the melt powder of the sparse solid-liquid phase change heat storage substrate as the packaging material, realizes the packaging of the phase change material in the form of melt marble or solid marble, can prevent the phase change material from leaking, can enable gas to pass through gaps between the powder on the surfaces of the melt marble or the solid marble to be used as a substance transfer channel, realizes the dual control of the components and the temperature of the hot fluid, and can be applied to energy storage and release and substance transfer.

Description

Active semi-encapsulated solid-liquid phase change heat storage material and preparation method and application thereof

technical field

The invention belongs to the technical field of phase change heat storage, and relates to a movable non-fully hermetic encapsulated phase change material formed by encapsulating a solid-liquid phase change material by using a powder encapsulation material, and a preparation method and application thereof.

Background technique

A phase change material refers to a material that can provide latent heat through the change of material state or phase state at a fixed phase transition temperature. The process of using phase change materials to store or release heat or cold is called phase change heat storage or release, which has the ability to control the mismatch of energy supply in time and space.

Phase change materials include solid-liquid phase change materials, solid-liquid phase change materials, liquid-gas phase change materials and solid-solid phase change materials, among which solid-liquid phase change materials are the most widely used, because solid-liquid phase change materials can overcome the Solid-gas and liquid-gas phase changes are too large, and the energy storage efficiency and raw material types are better than solid-solid phase change heat storage.

However, in the process of solid-liquid phase change heat storage, in order to prevent the leakage of the phase change material, the phase change material is generally fixed by encapsulation. At present, packaging methods can be simply divided into fully hermetic packaging and semi-hermetic packaging according to whether there is substance transfer. Fully enclosed packaging (referred to as full packaging) is to completely cover the solid-liquid phase change material with packaging material, so it has high safety and is not easy to leak liquid. The interior of the packaging shell is all phase change material with high heat capacity; It cannot exchange substances with the outside world, and it is difficult to control humidity. Semi-hermetic encapsulation (referred to as semi-encapsulation), that is, non-fully hermetic encapsulation, the usual implementation of semi-encapsulation in the prior art is to fix the solid-liquid phase change material in a porous medium. Although this encapsulation method can make the phase change The material is directly in contact with the heat exchange medium for heat and mass transfer to achieve environmental temperature and humidity control, but the load of the phase change material is limited by the porous medium, the average load is only maintained at about 80%, and the volume heat capacity of the phase change heat medium It will be affected, especially in the process of humidity control and temperature control, the volume change of the phase change material after moisture absorption, and the change of the fluidity caused by the change of thermal physical properties, which are easy to cause the leakage of the phase change material. Therefore, it is difficult for the existing packaging technology to solve the packaging problem of the solid-liquid phase change heat storage material that can realize temperature and humidity control.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a movable semi-encapsulated solid-liquid phase change heat storage material and a preparation method thereof in view of the deficiencies of the prior art, so as to overcome the problems existing in the existing semi-encapsulated manner. Another object of the present invention is to provide the application of the movable semi-encapsulated solid-liquid phase change heat storage material in energy storage and release, and mass transfer.

The movable semi-encapsulated solid-liquid phase thermal storage material of the present invention is a solid-liquid phase thermal storage material formed by coating the melt surface of the solid-liquid phase thermal storage substrate with the melted powder of the sparse solid-liquid phase thermal storage substrate. -The liquid-phase transformation heat storage base material melt marbles or solid marbles formed by the phase transformation of the melt marbles. The reason why it is called movable encapsulation means that the encapsulation material on the surface of the marble, the solid-sparse-liquid phase change heat storage base material melt powder, can move freely and rearrange with the change of external or internal conditions. The reason why it is called semi-encapsulation means that there are gaps between the powder particles on the surface of the marble, and the gas permeability is good, providing a heat and mass transfer channel, which can realize the transfer of substances.

The above-mentioned movable semi-encapsulated solid-liquid phase change heat storage material has elasticity in the molten state, is easy to cut, and the surface powder is in a single-layer or multi-layer state, and the stability of the marble is guaranteed.

The solid-liquid phase transition heat storage substrate in the present invention can be selected according to application requirements, and its phase transition temperature is in the range of 20°C to 600°C. The solid-liquid phase change heat storage substrate is at least one of crystalline hydrate, molten salt, eutectic salt, urea, sulfur, paraffin, alcohol, and some polymers, etc., but the present invention is not limited within the scope of the above example. In a preferred implementation, the crystalline hydrate includes, but is not limited to, ferric nitrate nonahydrate, sodium silicate pentahydrate, ferric trichloride hexahydrate, sodium acetate trihydrate, and the like. The molten salt includes, but is not limited to, sodium nitrate, potassium nitrate, lithium nitrate, and the like. The eutectic salt includes, but is not limited to, 50% lithium chloride-50% aluminum trichloride, sodium nitrate-erythritol, sun salt, potassium iodide-lithium iodide, and the like. The ureas include, but are not limited to, thiourea, urea phosphate, and the like. The alcohols include, but are not limited to, erythritol, polyethylene glycol, butane erythritol, sorbitol, and the like. The initial state of the solid-liquid phase change heat storage substrate is powder.

The solid-repellent-liquid phase change heat storage base material melt powder in the present invention can be metal powders, metal oxide powders and inorganic non-metal powders modified by the solid-phase-liquid phase change heat storage base material melt, as well as solid-repellent heat storage base material powders. -At least one of the organic polymer powders of the liquid phase change heat storage base material melt, but the present invention is not limited to the scope of the above examples. The metal powder includes, but is not limited to, iron powder, copper powder, gold powder, and the like. The metal oxide powder includes, but is not limited to, ferric oxide powder, copper oxide powder, titanium dioxide powder, and the like. The inorganic non-metallic powders include, but are not limited to, silica powder, talc powder, graphene powder, carbon nanotubes, and the like. The organic polymer powder of the solid-liquid phase change heat storage substrate melt includes, but is not limited to, polypropylene powder, polytetrafluoroethylene powder, polystyrene powder, and the like. The size of the solid-phase-liquid phase change heat storage base material melt powder can be nano-scale, micro-scale, millimeter-scale, and the like. The shape of the solid-phobic-liquid phase change heat storage base material melt powder may be at least one of flakes, spheres, blocks, and the like.

The method for preparing the movable semi-encapsulated solid-liquid phase thermal storage material of the present invention uses solid-liquid phase thermal storage substrate powder and solid-sparse-liquid phase thermal storage substrate melt powder as raw materials, and solid-liquid phase thermal storage substrate powder is used as raw materials. -The powder of the liquid phase change heat storage base material and the solid-phobic-liquid phase change heat storage base material melt powder are measured according to the mass ratio (1-1000): 1, and the melt marbles are prepared by the process of melt coating or premix melting ,As shown in Figure 1.

The melt coating process is as follows: the powder of the solid-liquid phase change heat storage base material is heated to a solid-solution temperature higher than the melting point of the solid-liquid phase change heat storage base material and lower than the decomposition temperature of the solid-liquid phase change heat storage base material. The liquid phase change heat storage base material melt is heated and melted on a heating plate to obtain a solid-liquid phase change heat storage base material melt, and then the solid-liquid phase change heat storage base material melt is heated and melted on the solid-liquid phase change heat storage base material. The solid-liquid phase change heat storage base material melt powder arranged on the heating plate of the hot base material melt is rolled on the surface, so that the solid-liquid phase change heat storage base material melt powder is coated on the solid-liquid phase change heat storage material. Melt marbles are formed on the melt surface of the substrate;

The premixed melting process is as follows: the mixture formed by uniformly mixing the powder of the solid-liquid phase change heat storage base material and the melted powder of the solid-sparse liquid phase change heat storage base material is placed above the solid-liquid phase change heat storage base. The melting point of the solid-liquid phase change heat storage base material is lower than the decomposition temperature of the solid-liquid phase change heat storage base material by heating and melting on a hot plate, and the solid-liquid phase change heat storage base material powder in the mixture After being melted and aggregated into a solid-liquid phase thermal storage substrate melt, the solid-liquid phase thermal storage substrate melt powder is coated on the surface of the solid-liquid phase thermal storage substrate melt to form a melt bomb. beads.

The preparation method of the above-mentioned movable semi-encapsulated solid-liquid phase change heat storage material, the melt coating process is to convert the solid-liquid phase change heat storage base material by moving the solid-liquid phase change heat storage base material melt. The melt powder adheres to the melt surface and wraps the solid-liquid phase change heat storage base material to form melt marbles; the premixed melting process is due to the solid-liquid phase change heat storage base material being melted and aggregated into a melt. The solid-liquid phase change heat storage substrate melt powder spontaneously migrates from the melt to the gas-liquid interface and wraps the solid-liquid phase change heat storage base material to form melt marbles. The amount of the solid-repellent-liquid phase change heat storage base material melt powder is mainly related to the particle size and density of the solid-liquid phase change heat storage base material melt powder. When the solid-liquid phase change heat storage base material melt powder is micron silica powder, the mass ratio of the solid-liquid phase change heat storage base material melt powder to the solid-liquid phase change heat storage base material It is preferably 1:2 to 1:20. If the amount of the solid-liquid phase change heat storage base material melt powder is too small, it will cause the solid-liquid phase change heat storage base material melt powder to be difficult to effectively cover the surface of the solid-liquid phase change heat storage material melt, resulting in The phase change material inside the melt marble is exposed or overflowed.

The preparation method of the above-mentioned movable semi-encapsulated solid-liquid phase variable heat storage material has no limited requirements on the material of the heating plate, which can be a metal plate, an alloy plate, an inorganic non-metallic plate and the like with good thermal conductivity, Or a combination of multiple forms. The heating plate should be modified so that its surface has super-repellent solid-liquid phase change heat storage substrate melt properties, so as to avoid the solid-liquid phase change heat storage base melt from adhering to the surface, and it is difficult to realize the self-shrinking of the melt into a melt. The surface of the molten liquid heating plate (especially the superhydrophobic heating plate) should have better corrosion resistance. The heating plate can also be replaced with a closed heating device. For the closed heating device, in order to adhere a sufficient amount of solid-sparse-liquid phase change heat storage substrate melt powder, the closed heating device can be slightly shaken to increase the solid-sparse-liquid phase change heat storage substrate melt powder and solid - The amount of contact with the liquid phase change heat storage substrate.

The preparation method of the above-mentioned movable semi-encapsulated solid-liquid phase change heat storage material, in the premixed melting process, the solid-liquid phase change heat storage base material melt powder and the solid-liquid phase change heat storage base material The mixing method can be shaking, ball milling dispersion, mechanical stirring, shaking mixing and so on.

The movable semi-encapsulated solid-liquid phase change heat storage material provided by the invention can be applied to the field of phase change heat storage, realizes the release and storage of energy, and at the same time, material transfer can occur. The field of phase change heat storage includes energy storage and release in the fields of solar energy, electric energy, wind energy, nuclear energy, geothermal heat, industrial waste heat, and fossil fuels. The present invention can realize dual control of thermal fluid composition and temperature through material transfer. The substance in the mass transfer can be not only water, but also at least one of hydrogen sulfide, carbon dioxide, sulfur gas oxides, nitrogen gas oxides, volatile organics and other gases, etc. limited to the scope of the above examples. The sulfur gas oxides include but are not limited to SO ₂ , SO ₃ , etc.; the nitrogen gas oxides include but are not limited to N ₂ O, NO ₂ , N ₂ O ₃ , etc.; the volatile organics include but are not limited to Not limited to formaldehyde, acetone, etc.

To sum up, the present invention provides a novel movable semi-encapsulation technology of solid-liquid phase change heat storage material, which coats the solid-liquid phase change heat storage base material melt powder on the solid-liquid phase change form. The melt surface of the heat storage material forms melt marbles, and the melt marbles release latent heat during the cooling process and undergo phase transformation to form solid marbles. The molten solid-liquid phase change heat storage base material melt powder on the surface of the melt marble is independent of each other. With the volume expansion or contraction of the melt marble, the solid-liquid phase change heat storage base material melt powder is independent. Migration and rearrangement occur, but it is always located on the surface of the melt marble, forming a tight or loose encapsulation shell to bind the phase change heat storage material to prevent leakage; after the melt marble is transformed into a solid marble, the volume changes little , the solid-liquid phase change heat storage base material melt powder is still coated on the surface of the solid-liquid phase change heat storage material; There are gaps between the powders, and the gas permeability is good, providing a heat and mass transfer channel.

The movable semi-encapsulated solid-liquid phase change heat storage material and its preparation method provided by the present invention have the following beneficial effects:

(1) In the present invention, the solid-liquid phase change heat storage base material melt powder is used as the packaging material, and the movable semi-encapsulated solid-liquid phase change heat storage material is obtained by the process of melt coating or premix melting. The semi-encapsulated solid-liquid phase change heat storage material has a marble-like structure, and the melt powder of the solid-liquid phase change heat storage substrate on its surface can migrate and rearrange as the phase change material expands or contracts. When the volume of the phase change material shrinks, the surface powder is closely arranged, and when the phase change material expands, the surface powder is loosely arranged; however, the surface powder can stably exist at the gas-liquid two-phase interface or the gas-solid two-phase interface, preventing Leaks occur and there is no plastic fatigue failure as described with conventional encapsulation materials.

(2) Since the present invention uses the solid-liquid phase change heat storage base material melt powder as the packaging material, the obtained movable semi-encapsulated solid-liquid phase change heat storage material is non-viscous and elastic, and will not collide with each other. Agglomeration occurs, and it can automatically return to its original shape after deformation.

(3) because the present invention takes the sparse solid-liquid phase change heat storage base material melt powder as the packaging material, obtains the melt marble by the process of melting coating or premixed melting, and the melt marble is cooled to form the solid marble, Therefore, the solid-liquid phase change heat storage material in this packaging method improves the heat exchange efficiency compared with the fully packaged solid-liquid phase heat change heat storage material.

(4) The movable semi-encapsulated solid-liquid phase heat storage material of the present invention provides a heat and mass transfer channel due to the existence of gaps between the melted powders of the solid-liquid phase change heat storage base material on the surface. It can transfer material with the heat exchange medium to achieve dual control of the composition and temperature of the thermal fluid.

(5) The present invention uses the solid-liquid phase change heat storage base material melt powder as the packaging material to realize the movable semi-encapsulation of the solid-liquid phase change heat storage base material, which is completely different from the packaging of any existing phase change materials. It provides a brand new technical solution for the encapsulation of phase change energy storage materials.

Description of drawings

Fig. 1 is a schematic diagram of the preparation method of the movable semi-encapsulated solid-liquid phase heat storage material according to the present invention; wherein (a) corresponds to the melting coating process, and (b) corresponds to the premixed melting process.

Fig. 2 is the photos of water beads in Example 1 and four kinds of marbles prepared; wherein a is water beads, b is water marbles covered with polytetrafluoroethylene, and c is water marbles covered with polytetrafluoroethylene Water ferric nitrate marbles, d is sodium silicate pentahydrate marbles coated with PTFE, e is polyethylene glycol marbles coated with PTFE.

3 is a photograph of the melt marbles obtained by coating different solid-liquid phase change heat storage base material melts with the solid-liquid phase change heat storage base material melt powder in Examples 1-8; wherein, (a1) (a2) is a photo obtained by using a premixed melting process.

Fig. 4 is the melt marble photograph that the erythritol of different mass ratios and the modified silica in Example 8 adopt the premixed melting process to prepare; Wherein, (a) the erythritol and the modified silica The mass ratio is 5:1; (b) the mass ratio of erythritol to modified silica is 10:1; (c) the mass ratio of erythritol to modified silica is 15:1; ( d) The mass ratio of erythritol to modified silica is 20:1; (e) the mass ratio of erythritol to modified silica is 30:1; (f) the mass ratio of erythritol to modified silica The mass ratio of silica is 50:1; (g) the mass ratio of erythritol to modified silica is 2:1; (h) is an enlarged photo of some marbles in (g).

FIG. 5 is a thermal infrared analysis diagram of the phase transition heat process of the melt marble in Example 8. FIG.

6 is a photo of the cyclic phase change process of the movable semi-encapsulated solid-liquid phase change heat storage material prepared by using erythritol as the phase change heat storage substrate in Example 8; wherein, (a) erythritol The solidification time from melt to solid, (b) the process of erythritol from solid state to molten state by heating.

7 is a photograph of melt marbles prepared by mixing erythritol and modified ferric tetroxide powder in different mass ratios in Example 9; wherein, the left and right columns of the same ratio are photographed from different angles for the same sample.

Fig. 8 is a schematic diagram of mass change during moisture absorption and drying of the movable semi-encapsulated solid-liquid phase change heat storage material prepared by using erythritol as the phase change heat storage substrate in Example 8; the erythritol and hydrophobic The mass ratio of the modified silica powder was 15:1.

Detailed ways

The technical solutions of the present invention will be further described below through embodiments and in conjunction with the accompanying drawings.

Since the phase change heat storage substrates used in the following examples have strong polarity, the solid-liquid phase change heat storage substrate melt powder used in the following examples is a non-polar hydrophobic powder.

The following examples use an open type superhydrophobic heating plate. The method of modifying the heating plate is as follows: soak the purchased copper plate in 1M HCl for cleaning to remove surface oxides; then ultrasonically clean the copper plate in acetone, ethanol and distilled water for 10 minutes; and then immerse the cleaned copper plate in Concentration of 1mol/L HCl for 5min; then rinse the copper plate with deionized water and dry it with cold air. The dried copper plate was immersed and etched in a solution of 1 mol/L NaOH and 0.05 mol/L K ₂ S ₂ O ₈ for 30 min, and then the etched copper plate was taken out of the solution and rinsed in deionized water. Then, the etched copper plate was modified with 1 wt% fluorosilane (FAS-17) ethanol solution for 6 hours. Finally, the modified copper plate was heated in an oven at 80 °C for 30 min to obtain a superhydrophobic heating plate.

The method for hydrophobic treatment of needles in the following examples is as follows: coating the surfaces of glass needles and stainless steel needles with polyvinyl alcohol adhesive, and then adhering commercial polytetrafluoroethylene nano-powders to obtain hydrophobic needles.

The preparation method of hydrophobically modified micron-sized silica (referred to as hydrophobically modified silica) in the following examples: mixing fluorosilanol solution (concentration of 1wt%) with silica powder (about 25 microns), fluorosilane The ratio of the volume of the alcohol solution to the mass of the silica powder is 1:1 (the volume of the fluorosilanol solution is in mL, and the mass of the silica powder is in g). All the silica powder was immersed in the fluorosilanol solution and modified for 12 hours; then the solid-liquid separation was performed, the fluorosilanol solution was removed, and the modified silica was placed in an oven at 80°C and dried for more than 12 hours.

The preparation method of hydrophobically modified ferric oxide (referred to as hydrophobically modified ferric tetroxide) in the following examples: adding a fluorosilanol solution (concentration of 1 wt%) into the micro-nano powder of commercial ferric tetroxide, fluorine The amount of silanol solution added is to submerge all the ferric oxide powder, then put the mixture in a centrifuge tube and close it, shake the centrifuge tube to disperse the ferric oxide powder in the fluorosilane solution, and modify it for 12h; then remove it Fluorosilanol solution, place the modified ferric oxide powder in an oven at 80°C and dry for more than 12 hours.

Example 1

In this embodiment, polytetrafluoroethylene powder is used as solid-liquid phase change heat storage base material melt powder, and water droplets, ferric nitrate nonahydrate, sodium silicate pentahydrate and polyethylene glycol are used as solid-liquid phase A variable heat storage substrate is used to prepare a movable semi-encapsulated solid-liquid phase variable heat storage material.

The preparation steps of this embodiment are as follows:

(1) Spread 0.025g of polytetrafluoroethylene hydrophobic powder (outsourced) evenly on the surface of the super-hydrophobic heating plate, and then weigh 0.017g of ferric nitrate nonahydrate, 0.026g of sodium silicate pentahydrate, and 0.011g of polyethylene glycol respectively. And 10 microliters of water droplets were placed on the Teflon hydrophobic powder spread on the surface of the heating plate.

(2) Heating the temperature of the heating plate to 60° C. to melt ferric nitrate nonahydrate, sodium silicate pentahydrate and polyethylene glycol, and use a hydrophobic needle to move ferric nitrate nonahydrate and sodium silicate pentahydrate during the melting process Molten salts, as well as polyethylene glycol melts and water droplets, enable ferric nitrate nonahydrate and sodium silicate pentahydrate molten salts, as well as polyethylene glycol melts and water droplets to adhere to PTFE powder to form a melt marbles.

(3) The melted marbles formed in step (2) have poor sphericity, and the melted marbles are further extruded and cut by a hydrophobic needle to obtain melted marbles with better sphericity, as shown in FIG. 2 .

The extrusion and cutting of the melt marbles in step (3) can also be controlled by controlling the initial feeding amount, so as to avoid the difficulty in controlling the size and quality of the marbles due to cutting.

Example 2

In this example, hydrophobically modified silica powder is used as the solid-liquid phase change thermal storage base material melt powder, and sulfur is used as the solid-liquid phase change heat storage base material to prepare a movable semi-encapsulated solid-liquid phase change material. Thermal storage material.

The steps of this embodiment are as follows:

(1) Spread 0.021 g of hydrophobically modified silica powder evenly on the surface of the super-hydrophobic heating plate, and then weigh 0.021 g of sulfur powder and place it on the hydrophobic modified silica powder spread on the surface of the heating plate.

(2) Heating the temperature of the heating plate to 130° C. to melt the sulfur. During the melting process, use a hydrophobic needle to move the sulfur melt so that it can adhere to the hydrophobically modified silica powder to form melt marbles.

(3) The melted marbles formed in step (2) have poor sphericity, and the melted marbles are further extruded and cut by a hydrophobic needle to obtain melted marbles with better sphericity.

The extrusion and cutting of the melt marbles in step (3) can also be controlled by controlling the initial feeding amount, so as to avoid the difficulty in controlling the size and quality of the marbles due to cutting.

Example 3

In this example, hydrophobically modified silica powder is used as the solid-liquid phase change heat storage base material melt powder, and ferric nitrate nonahydrate and ferric trichloride hexahydrate are used as the solid-liquid phase change heat storage base material to prepare Active semi-encapsulated solid-liquid phase change heat storage material.

The steps of this embodiment are as follows:

(1) Measure according to the mass ratio of the solid-liquid phase change heat storage base material and the solid-phobic-liquid phase change heat storage base material melt powder as 15:1, and separate the ferric nitrate nonahydrate and ferric trichloride hexahydrate respectively. Mix with the hydrophobically modified silica powder, and then weigh 10 mg of the mixed material and place it on the surface of the super-hydrophobic heating plate.

(2) heating the temperature of the heating plate to 60°C, the ferric nitrate nonahydrate and ferric trichloride hexahydrate in the mixed material are melted and spontaneously aggregated into a spherical shape, and the hydrophobically modified silica powder in the mixed material adheres On the surface of spherical melt, melt marbles are formed.

The size of the melt marble can be controlled by extruding and cutting the melt marble with a hydrophobic needle or by controlling the mixing ratio and the amount of the initially added material.

Example 4

In this example, hydrophobically modified silica powder is used as the solid-liquid phase change heat storage base material melt powder, and sulfur is used as the solid-liquid phase change heat storage base material to prepare a movable semi-encapsulated solid-liquid phase heat storage material.

The steps of this embodiment are as follows:

(1) Mix the hydrophobically modified silica powder and the sulfur powder according to the mass ratio of 1:15, weigh 10 mg of the mixed material and place it on the surface of the super-hydrophobic heating plate.

(2) Heating the temperature of the heating plate to 130°C, the sulfur in the mixture melts and spontaneously aggregates into balls, and the hydrophobically modified silica powder in the mixture adheres to the surface of the spherical melt to form melt marbles .

The size of the melt marble can be controlled according to the amount of the mixed material added or the proportion of the mixed material.

Example 5

In this example, hydrophobically modified silica powder is used as the solid-liquid phase change heat storage base material melt powder, and lithium nitrate and sodium nitrate are used as the solid-liquid phase change heat storage base material, respectively, to prepare a movable semi-encapsulated heat storage material. Solid-liquid phase change heat storage material.

The steps of this embodiment are as follows:

(1) Spread 0.02 g of hydrophobically modified silica powder on the surface of the super-hydrophobic heating plate, respectively weigh 0.01 g of lithium nitrate powder and 0.01 g of sodium nitrate powder on the surface of the heating plate to spread the hydrophobically modified silica on the powder.

(2) Heating the temperature of the heating plate to 270°C, the temperature will fluctuate in the range of 270-290°C, close the heating area with a quartz glass cover, the lithium nitrate powder and the sodium nitrate powder are melted and spontaneously aggregated into balls. The preheated hydrophobic glass needle was slightly moved, and the hydrophobically modified silica powder spontaneously adhered to the surface of the lithium nitrate and sodium nitrate melts as the melt rolled, forming melt marbles.

(3) Turn off the heating plate and reduce the temperature of the heating plate, so that the molten marbles of lithium nitrate and sodium nitrate become solid marbles, and then heated to 270 ° C again, so that the solid marbles become melted marbles again, which is realized by phase transition. Heat storage and release.

The hydrophobically modified silica powder used in step (1) can be replaced with hydrophobically modified ferric oxide powder.

In step (2), a plurality of independent lithium nitrate and sodium nitrate melt marbles can be obtained by cutting to increase the heat exchange area.

Example 6

In this example, hydrophobically modified silica powder is used as the solid-liquid phase change heat storage base material melt powder, and lithium nitrate and sodium nitrate are used as the solid-liquid phase change heat storage base material to prepare a movable semi-encapsulated solid-state heat storage material. - Liquid phase change heat storage material.

The steps of this embodiment are as follows:

(1) Mix the hydrophobically modified silica powder with lithium nitrate and sodium nitrate according to the mass ratio of the solid-liquid phase change heat storage base material and the solid-liquid phase change heat storage base material melt powder of 15:1. , and then weigh 10 mg of the mixed material and place it on the surface of the superhydrophobic heating plate.

(2) heating the temperature of the heating plate to 270°C, the lithium nitrate and sodium nitrate in the mixture are melted and spontaneously aggregated into balls, and the hydrophobically modified silica powder in the mixture is adhered to the surface of the spherical melt, Melt marbles are formed.

(3) closing the heating plate, lowering the temperature of the heating plate, so that the lithium nitrate and sodium nitrate melt marbles become solid marbles, and then heated to 270 ° C again, so that the solid marbles become melt marbles again, The energy storage and release of heat are achieved through phase transition.

The quality of the mixed material in step (2) is controlled, and lithium nitrate and sodium nitrate melt marbles of different sizes can be obtained; in step (2), a plurality of independent lithium nitrate and sodium nitrate melt marbles can be obtained by cutting beads, increase the heat exchange area.

Example 7

In this example, hydrophobically modified silica powder is used as the solid-liquid phase change heat storage base material melt powder, and erythritol (C ₄ H ₁₀ O ₄ ) is used as the solid-liquid phase change heat storage base material, Preparation of movable semi-encapsulated solid-liquid phase change heat storage materials.

The steps of this embodiment are as follows:

(1) Spread 0.015 g of hydrophobically modified silica powder on the surface of a super-hydrophobic heating plate, weigh 0.015 g of erythritol and place it on the hydrophobically modified silica powder spread on the surface of the heating plate.

(2) Heating the temperature of the heating plate to 140°C, the erythritol is melted and spontaneously aggregated into balls, slightly moved with a preheated hydrophobic stainless steel needle, and the hydrophobically modified silica powder rolls spontaneously with the melt The erythritol is transferred from the hot plate to the surface of the erythritol melt, wrapping the erythritol to form melt marbles.

(3) Turn off the hot plate, lower the temperature of the hot plate, so that the melt marble is cooled, but the erythritol melt marble has a phenomenon of supercooling, even if the temperature is lower than the phase transition temperature (140 ° C), still remain molten. When a hydrophobic needle is used to touch the molten marble, the molten marble undergoes a rapid phase transition and releases latent heat to form a solid marble.

In step (2), a plurality of independent erythritol melt marbles can be obtained by cutting to increase the heat exchange area.

Example 8

In this example, hydrophobically modified silica powder is used as the solid-liquid phase change heat storage base material melt powder, and erythritol (C ₄ H ₁₀ O ₄ ) is used as the solid-liquid phase change heat storage base material, Preparation of movable semi-encapsulated solid-liquid phase change heat storage materials.

The steps of this embodiment are as follows:

(1) Mixing erythritol and hydrophobically modified silica powder in a ratio of 15:1 by mass to form a mixed material.

(2) Weigh two 0.015g mixed materials and place them on the surface of the super-hydrophobic heating plate respectively; the temperature of the heating plate is heated to 140°C, and the erythritol in the mixed material is melted and spontaneously aggregated into balls , the hydrophobically modified silica powder spontaneously adhered to the surface of the erythritol spherical melt, forming two melt marbles.

(3) Turn off the heating plate, lower the temperature of the heating plate, so that the melt marbles are cooled, but the erythritol melt marbles have supercooling phenomenon, even if the temperature is lower than the phase transition temperature (for example, the temperature of the heating plate decreases When the temperature reaches 67.3°C), the melt marble remains in the melt state without phase transition (see Figure 5); when the melt marble is touched with a hydrophobic needle, the melt marble rapidly undergoes a phase change and releases latent heat, The time to convert from molten marbles to solid marbles is less than 1 s (see Figure 6).

(4) The erythritol melt marbles obtained in step (2) are repeatedly subjected to liquid→solid, solid→liquid phase transformation operations for 10 times, and the results show that the melt marbles can still exist stably.

The hydrophobic powder spread in step (1) can be replaced with hydrophobically modified SiO ₂ powder of different particle size, such as nano-scale hydrophobically modified silica powder or micron-scale hydrophobically modified silica with larger particle size. powder.

Adjust the mass ratio of erythritol and hydrophobically modified silica powder in step (1), the adjustment range is controlled from 2:1 to 50:1, and the melt bomb in the range of 0.3mm-1.8mm can be obtained beads (as shown in Figure 4).

The quality of the mixed material in step (2) can be adjusted to obtain melt marbles of different sizes, and multiple independent erythritol melt marbles can also be obtained by cutting to increase the heat exchange area.

Example 9

In this example, hydrophobically modified ferric oxide powder is used as the melt material of the solid-liquid phase change heat storage base material, and erythritol is used as the solid-liquid phase change heat storage base material to prepare a movable semi-encapsulated solid - Liquid phase change heat storage material.

The steps of this embodiment are as follows:

(1) According to the mass ratio of erythritol and hydrophobically modified ferric oxide powder, respectively 100:1, 300:1, 600:1, 900:1, mix the hydrophobically modified ferric oxide particles and erythritol to form a mixture, then Weigh 10 mg of mixed materials with different mass ratios and place them on the surface of the superhydrophobic heating plate.

(2) Heating the hot plate to 140°C, the erythritol in the mixture melts and spontaneously aggregates into balls, and the hydrophobically modified ferric oxide powder in the mixture adheres to the erythritol spherical melt surface, forming melt marbles.

The melt marbles prepared by this example are shown in FIG. 7 .

The structure and performance of the movable semi-encapsulated solid-liquid phase change heat storage material prepared in the above embodiment are analyzed below:

(1) Structural analysis

The melt marbles prepared in Example 1-Example 9 and the solid marbles formed by the phase transformation of the melt marbles and their preparation process were imaged, and the obtained photos were shown in Figures 2-4 and Figures 6 and 7. As can be seen from the figure, the movable semi-encapsulated solid-liquid phase change heat storage material of the present invention is made of solid-liquid phase change heat storage base material melt powder coated with solid-liquid phase change heat storage material Melt marbles formed by the melt of the base material or solid marbles formed by cooling phase transformation of the melt marbles.

(2) Performance analysis

1. Analysis of phase change heat storage performance

For the pure erythritol melt not coated with hydrophobically modified silica and in Example 8, the hydrophobically modified silica powder was used as the solid-liquid phase change heat storage base material melt powder, and the erythritol was The erythritol melt marbles prepared by sugar alcohol as the phase change heat storage substrate were subjected to thermal infrared analysis, and the test results are shown in Figure 5. The initial temperature of the heating plate was set to 140 °C, but the erythritol melt marbles may be due to the presence of the surface-coated hydrophobically modified silica powder, the initial temperature was only 130 °C, while the pure erythritol melt The initial temperature of 138 °C is higher than the initial temperature of erythritol melt marbles. During the cooling process, with the decrease of temperature, the temperature of pure erythritol melt and erythritol melt marble gradually decreased. After 40s, their temperature decreased from the initial temperature to 67.3 °C, and basically remain stable and never change. The above-mentioned cooling process is the release of sensible heat, and the release speed of pure erythritol melt and erythritol melt marble is almost the same, that is, between the erythritol melt marble and the erythritol melt. The heat transfer efficiency is almost the same, which fully shows that the encapsulation powder of the melt marble can achieve the structural stability of the melt, the phase change material does not leak, and does not affect the heat transfer efficiency of the melt, which is very important for the phase change material. Encapsulation is very beneficial.

The pure erythritol melt and the erythritol melt marbles were then stimulated successively with a hydrophobic needle, respectively, and they underwent phase transitions (see Figure 5). After the phase transition, the temperature of pure erythritol melt and erythritol melt marbles both began to rise first, from 67.3 °C to nearly 100 °C, and the maximum temperature of the two was not much different, and then from the maximum temperature. When the temperature drops to about 67.3°C, the latent heat of phase transition is released; the phase transition temperature change of pure erythritol melt lasts for 25.2s, and all the latent heat is released, and the phase transition temperature change of erythritol melt marble lasts for 30.9s. The latent heat is released because the surface of the erythritol melt marble is coated with hydrophobically modified SiO ₂ powder, which increases the time for releasing the latent heat of phase transition, but the increase is not large. Therefore, although erythritol melt marbles release latent heat relatively slowly compared to pure erythritol melt, on the whole, erythritol melt marbles also have the characteristics of fast latent heat release.

It can be seen from the above analysis that the movable semi-encapsulated solid-liquid phase heat storage material provided by the present invention has good heat exchange performance and can be used as a medium for photothermal energy storage and waste heat recovery.

2. Stability analysis

For the solid-liquid phase change heat storage material prepared by using the hydrophobically modified silica powder as the solid-liquid phase change heat storage base material melt powder and erythritol as the phase change heat storage base material in Example 8 The cyclic phase transition process was tested, and the collected pictures are shown in Figure 6. It can be seen from Figure 6 that during a single phase transition process, erythritol melt marbles are converted into solid marbles by cooling, and erythritol solid marbles are converted into melt marbles by heating and melting. Example 8 shows that the erythritol melt marble has a supercooling phenomenon, and the phase transition occurs rapidly after the melt marble is moved with a hydrophobic needle, and the time for converting from the melt marble to the solid marble is less than 1 s. It can be seen from Figure 6(a) that during the process of converting erythritol melt marbles into solid marbles, the volume hardly changes, the calculated volume change rate is less than 5%, and the contact angle decreases from 137° At 130°, the light transmission performance drops instantly.

As can be seen from Figure 6(b), during the process of heating the erythritol solid marbles from the solid phase to the liquid phase, since the heating plate is at the bottom of the solid marbles, the solid gradually transforms into a melt from the bottom, However, through observation, it was found that the hydrophobically modified silica powder on the surface remained basically stationary at the initial stage of heating, which was mainly due to the fact that the hydrophobically modified silica powder on the surface formed a complete shell layer, contacted and supported each other, and was melted. The body adheres without moving; with the increase of temperature, part of the encapsulation shell on the surface of the marble cracks due to the local uneven force and the expansion of the volume during the solid-liquid conversion of erythritol; The temperature continues to rise, and the cracks will gradually increase until the erythritol is completely molten. During this process, the encapsulated powder will move, rearrange and move, but it is always located on the surface of the melt marble, forming a tight or loose The encapsulation shell binds the phase change heat storage material to prevent leakage; during the process of converting from solid phase to liquid phase, the light transmission performance of marbles is gradually enhanced, and the contact angle of the heating plate is gradually increased. Example 8 shows that the morphology and stability of the melt marble (including volume, light transmittance and contact angle, etc.) remain basically unchanged with the increase of the number of phase transitions. Beads can still exist stably.

It can be seen from the above analysis that in Example 8, the hydrophobically modified silica powder is used as the solid-liquid phase change heat storage base material melt powder, and erythritol is used as the solid-liquid phase change heat storage base material. The movable semi-encapsulated solid-liquid phase change heat storage material has the stability of cyclic phase transition and can realize a stable endothermic-exothermic cycle process. Therefore, the movable semi-encapsulated solid-liquid phase change heat storage material provided by the present invention has good phase change stability, and can be used as a medium for photothermal energy storage and waste heat recovery.

3. Mass transfer performance analysis

The mass transfer performance analysis was carried out with the erythritol solid marbles obtained in step (3) of Example 8, and the test results are shown in Figure 8. It can be seen from Figure 8 that with the introduction of water vapor, the mass of erythritol solid marbles gradually increased from the initial 0.402g, mainly due to the fact that water molecules penetrated the surface encapsulating material and were trapped by the erythritol inside the marble. sugar alcohols are absorbed. Extending the time of passing water vapor, the amount of water absorbed by the erythritol solid marbles gradually increased until the quality became flat after 500s, and finally the mass of the erythritol solid marbles after water absorption increased to 0.421g. Increased transparency of erythritol solid marbles. Subsequently, the erythritol solid marbles after water absorption were placed in a drying box and heated at 80 ° C (because it was lower than the melting point of erythritol, so no phase transition would occur), and the quality of the erythritol solid marbles was found. The decrease was very fast within 30s, from 0.402g to 0.398g. After that, the quality of erythritol solid marbles decreased gradually, but it was still decreasing until the mass of erythritol solid marbles dropped to 0.394g. , the transparency of the dried erythritol solid marbles decreases and appears white, and the mass of the dried erythritol solid marbles is smaller than that of the initially weighed erythritol solid marbles.

It can be seen from the above analysis that in Example 8, the hydrophobically modified silica powder is used as the solid-liquid phase change heat storage base material melt powder, and the movable semi-hydrogen is prepared with erythritol as the phase change heat storage base material. The encapsulated solid-liquid phase change heat storage material has the characteristics of material transfer, and the gas in the external environment can absorb and release the gas through the encapsulation material of the solid marble.

Therefore, the movable semi-encapsulated solid-liquid phase change heat storage material provided by the present invention has good material transfer characteristics, can be used as a medium for waste heat recovery of flue gas, and can be used as an absorbent for moisture, hydrogen sulfide, Carbon dioxide, sulfur gas oxides, nitrogen gas oxides, volatile organic compounds and other gases are absorbed to achieve waste heat recovery from flue gas and gas purification.

Those of ordinary skill in the art will appreciate that the embodiments described herein are intended to assist readers in understanding the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations without departing from the essence of the present invention according to the technical teaching disclosed in the present invention, and these modifications and combinations still fall within the protection scope of the present invention.

Claims (10)

1. A movable semi-packaged solid-liquid phase change heat storage material is characterized in that the phase change heat storage material is a solid-liquid phase change heat storage substrate melt marble formed by coating sparse solid-liquid phase change heat storage substrate molten liquid powder on the surface of solid-liquid phase change heat storage substrate melt or a solid marble formed by phase change of the melt marble.

2. The transportable semi-encapsulated solid-liquid phase change thermal storage material according to claim 1, wherein the solid-liquid phase change thermal storage base material is at least one of a crystalline hydrate, a molten salt, a eutectic salt, a urea, sulfur, paraffin, and an alcohol.

3. The transportable semi-encapsulated solid-liquid phase change thermal storage material according to claim 2, wherein the crystalline hydrate comprises iron nitrate nonahydrate, sodium silicate pentahydrate, iron trichloride hexahydrate, or sodium acetate trihydrate; the molten salt comprises sodium nitrate, potassium nitrate or lithium nitrate; the eutectic salt comprises 50% of lithium chloride-50% of aluminum trichloride, sodium nitrate-erythritol, solar salt or potassium iodide-lithium iodide; the ureas include thiourea or urea phosphate; the alcohol comprises erythritol, polyethylene glycol, erythritol or sorbitol.

4. The mobile semi-encapsulated solid-liquid phase change thermal storage material according to any one of claims 1 to 3, wherein the powder of the solvophobic-liquid phase change thermal storage substrate melt is at least one of a metal powder, a metal oxide powder and an inorganic non-metal powder modified from the solvophobic-liquid phase change thermal storage substrate melt, and an organic polymer powder of the solvophobic-liquid phase change thermal storage substrate melt.

5. The transportable semi-encapsulated solid-liquid phase change thermal storage material according to claim 4, wherein the metal powder comprises iron powder, copper powder or gold powder; the metal oxide powder comprises ferroferric oxide powder, copper oxide powder or titanium dioxide powder; the inorganic non-metal powder comprises silicon dioxide powder, talcum powder, graphene powder or carbon nano tubes; the organic polymer powder of the solid-liquid phase change heat storage substrate molten liquid comprises polypropylene powder, polytetrafluoroethylene powder or polystyrene powder.

6. The mobile semi-encapsulated solid-liquid phase change thermal storage material according to any one of claims 1 to 3, wherein the size of the solid-liquid phase change thermal storage base material melt powder is in the order of nanometers, micrometers or millimeters.

7. The method for preparing a mobile semi-encapsulated solid-liquid phase change thermal storage material according to any one of claims 1 to 6, wherein the solid-liquid phase change thermal storage matrix powder and the solidphobic-liquid phase change thermal storage matrix melt powder are used as raw materials, the solid-liquid phase change thermal storage matrix powder and the solidphobic-liquid phase change thermal storage matrix melt powder are measured according to the mass ratio of (1-1000):1, and the melt marbles are prepared by a melt coating or pre-mixing melting process;

the melting and coating process comprises the following steps: heating and melting solid-liquid phase change heat storage substrate powder on a solid-liquid phase change heat storage substrate melting liquid heating plate which is higher than a solid-liquid phase change heat storage substrate melting point and lower than a solid-liquid phase change heat storage substrate decomposition temperature to obtain solid-liquid phase change heat storage substrate melt, and then rolling the solid-liquid phase change heat storage substrate melt on the solid-liquid phase change heat storage substrate melting liquid powder arranged on the super-solid-liquid phase change heat storage substrate melting liquid heating plate to enable the solid-liquid phase change heat storage substrate melting liquid powder to be coated on the surface of the solid-liquid phase change heat storage substrate melt to form a melt marble;

the premixing and melting process comprises the following steps: the solid-liquid phase change heat storage base material powder and the dispersed solid-liquid phase change heat storage base material molten liquid powder are uniformly mixed to form a mixture, the mixture is placed on a dispersed solid-liquid phase change heat storage base material molten liquid heating plate which is higher than the solid-liquid phase change heat storage base material melting point and lower than the solid-liquid phase change heat storage base material decomposition temperature, the mixture is heated and melted, the solid-liquid phase change heat storage base material powder in the mixture is melted and aggregated into a solid-liquid phase change heat storage base material melt, and then the dispersed solid-liquid phase change heat storage base material molten liquid powder is coated on the surface of the solid-liquid phase change heat storage base material melt to form a melt marble.

8. The method of claim 7, wherein the loose-liquid phase-change heat-storage substrate melt heating plate is one of a loose-liquid phase-change heat-storage substrate melt modified metal plate, an alloy plate, and an inorganic non-metal plate.

9. Use of the mobile semi-encapsulated solid-liquid phase change thermal storage material of any one of claims 1 to 6 for energy storage and release, and mass transfer.

10. Use according to claim 9, characterized in that the substance in the substance transfer comprises water, hydrogen sulphide, carbon dioxide, gaseous oxides of sulphur, gaseous oxides of nitrogen or volatile organic compounds.

Images