CN114591717B - Nanometer microcapsule suspension phase change material and preparation method thereof - Google Patents
Nanometer microcapsule suspension phase change material and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a nano microcapsule suspension phase change material and a preparation method thereof, wherein the preparation method comprises the following steps: mixing the pre-prepared pre-polymerization solution with emulsion to react to generate nano microcapsule initial solution; adding the flow stability auxiliary agent into the initial solution of the nano microcapsule, wherein the flow stability auxiliary agent can be combined on the surface of the urea formaldehyde resin microcapsule structure through Van der Waals force and form a film layer to prepare the mixed solution of the nano microcapsule; and filtering and drying the nano microcapsule mixed solution to obtain nano microcapsule phase change material dry matter, adding flow enhancement nano particles into the nano microcapsule phase change material dry matter to obtain nano microcapsule mixed dry matter, and finally adding the obtained nano microcapsule mixed dry matter into microcapsule suspension medium liquid to obtain the nano microcapsule suspension phase change material. The method of the invention improves the stability, the cold accumulation efficiency and the dispersion uniformity of microcapsule particles while keeping the better fluidity of the nano microcapsule suspension phase change material.
Description
Technical Field
The invention relates to the technical field of phase change materials, in particular to a nano capsule suspension phase change material and a preparation method thereof.
Background
The traditional microcapsule suspension is generally characterized in that the acting force between capsule shells is large, the friction coefficient is high, meanwhile, the friction force between the capsule body and carrier liquid is large, so that the microcapsule suspension is agglomerated, and the problems of difficulty in uniform dispersion, nonuniform phase change and the like are caused. Generally, in order to ensure stability and uniformity of microcapsule suspension, no floating or precipitation occurs over time, a large amount of thickener needs to be added to make the mixed solution become viscous, but the viscous solution greatly reduces the uniformity of microcapsule dispersion and the cold storage efficiency, and meanwhile affects the flow of the mixed solution, so that some phase change cold storage air conditioner applications requiring better fluidity are difficult to apply.
Accordingly, the prior art is still in need of improvement and development.
Disclosure of Invention
In view of the shortcomings of the prior art, the invention aims to provide a nano microcapsule suspension phase change material and a preparation method thereof, and aims to solve the problems of poor fluidity, poor dispersion uniformity and low cold storage efficiency of the existing microcapsule phase change material.
The technical scheme of the invention is as follows:
the preparation method of the nano microcapsule suspension phase change material comprises the following steps:
adding urea and formaldehyde into deionized water, regulating the pH of the solution to 7-8, stirring at 50-90 ℃ for 30-90min, and finally adding deionized water for dilution to obtain a prepolymer;
adding an emulsifier, a polymerizer, sodium chloride and a phase change material into deionized water, and stirring at a rotation speed of 500-2000rpm for 10-60min at a temperature of 40-90 ℃ to prepare emulsion;
adding the prepolymer into the emulsion at the rotating speed of 50-300rpm, adding pH regulating solution to regulate the pH to 3-4, raising the rotating speed by 30-80% after white turbidity appears in the reaction, and continuously stirring for 2-10h at the temperature of 40-60 ℃ to prepare nano microcapsule initial liquid;
regulating the pH of the initial solution of the nano microcapsule to 5-7, increasing the reaction temperature to 70-90 ℃, adding a flow stability auxiliary agent, regulating the rotating speed to 500-1000rpm, and reacting for 0.5-3 hours to obtain a mixed solution of the nano microcapsule;
filtering the nano microcapsule mixed solution, washing a precipitate obtained by filtering, and drying to obtain a nano microcapsule phase change material dry matter, wherein flow-enhanced nano particles are added into the nano microcapsule phase change material dry matter to obtain a nano microcapsule mixed dry matter;
adding a density regulator into deionized water to enable the density of the prepared mixed solution to be the same as the density of the dry matter of the nano microcapsule phase change material, and adding a thickener into the mixed solution to obtain microcapsule suspension medium liquid;
and adding the mixed dry matter of the nano microcapsule into the microcapsule suspension medium liquid, and mixing to obtain the nano microcapsule suspension phase change material.
The preparation method of the nano microcapsule suspension phase change material comprises the step of preparing the nano microcapsule suspension phase change material, wherein the emulsifying agent is one or more of carboxylate, sulfate, sulfonate, sodium stearate, sodium dodecyl sulfate, polyoxyethylene ether and polyoxypropylene ether.
The preparation method of the nano microcapsule suspension phase change material comprises the step of preparing a nano microcapsule suspension phase change material, wherein the polymerization agent is one or more of resorcinol, phenol and cresol.
The preparation method of the nano microcapsule suspension phase change material comprises the step of preparing the nano microcapsule suspension phase change material, wherein the phase change material is one or more of n-tetradecane, pentadecane and hexadecane.
The preparation method of the nano microcapsule suspension phase change material comprises the step of preparing a nano microcapsule suspension phase change material, wherein the pH regulator is one or more of carboxylic acid, sulfonic acid, sulfinic acid and thiocarboxylic acid.
The preparation method of the nano microcapsule suspension phase change material comprises the step of preparing a nano microcapsule suspension phase change material, wherein the flow stability auxiliary agent is one or more of PVA, polyethylene glycol and SDS.
The preparation method of the nano microcapsule suspension phase change material comprises the step of preparing the nano microcapsule suspension phase change material, wherein the flow enhancement nano particles are polytetrafluoroethylene particles.
The preparation method of the nano microcapsule suspension phase change material comprises the step of preparing a nano microcapsule suspension phase change material, wherein the density regulator is a water-soluble salt or an organic alcohol.
The preparation method of the nano microcapsule suspension phase change material comprises the step of preparing a nano microcapsule suspension phase change material, wherein the thickening agent is one or more of attapulgite, nano fumed silica, bentonite, aluminum silicate and methylcellulose.
The invention relates to a nano microcapsule suspension phase change material, which is prepared by adopting the preparation method of the nano microcapsule suspension phase change material.
The beneficial effects are that: compared with the microcapsule phase-change material prepared by the traditional method, the preparation method of the invention
Drawings
FIG. 1 is a flow chart of a method for preparing a nano microcapsule suspension phase change material.
Detailed Description
The invention provides a nano microcapsule suspension phase change material and a preparation method thereof, which are used for making the purposes, the technical scheme and the effects of the invention clearer and more definite, and the invention is further described in detail below. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1, fig. 1 is a preparation method of a nano microcapsule suspension phase change material according to the present invention, as shown in the figure, comprising the steps of:
s10, adding urea and formaldehyde into deionized water, adjusting the pH of the solution to 7-8, stirring at 50-90 ℃ for 30-90min, and finally adding deionized water for dilution to obtain a prepolymer;
s20, adding an emulsifier, a polymerizer, sodium chloride and a phase change material into deionized water, and stirring at a rotation speed of 500-2000rpm for 10-60min at a temperature of 40-90 ℃ to prepare emulsion;
s30, adding the prepolymer into the emulsion at the rotating speed of 50-300rpm, adding a pH regulating solution to regulate the pH to 3-4, lifting the rotating speed by 30-80% after white turbidity appears in the reaction, and continuously stirring for 2-10h at the temperature of 40-60 ℃ to prepare a nano microcapsule initial solution;
s40, regulating the pH value of the initial solution of the nano microcapsule to be 5-7, increasing the reaction temperature to 70-90 ℃, adding a flow stability auxiliary agent, regulating the rotating speed to 500-1000rpm, and reacting for 0.5-3 hours to obtain a mixed solution of the nano microcapsule;
s50, filtering the nano microcapsule mixed solution, washing a precipitate obtained by filtering, and drying to obtain a nano microcapsule phase change material dry matter, wherein flow-enhanced nano particles are added into the nano microcapsule phase change material dry matter to obtain a nano microcapsule mixed dry matter;
s60, adding a density regulator into deionized water to enable the density of the prepared mixed solution to be the same as the density of the dry matter of the nano microcapsule phase change material, and adding a thickener into the mixed solution to obtain microcapsule suspension medium liquid;
and S70, adding the mixed dry matter of the nano microcapsule into the microcapsule suspension medium liquid, and mixing to obtain the nano microcapsule suspension phase change material.
The nano microcapsule suspension phase change material prepared by the embodiment is composed of microcapsule suspension medium liquid and microcapsule mixed particles suspended in the microcapsule suspension medium liquid, the microcapsule mixed particles are composed of nano microcapsule phase change material dry matters and flow enhancement nano particles, the nano microcapsule phase change material dry matters (namely microcapsule particles) are composed of phase change materials and urea resin microcapsule structures coating the phase change materials, the urea resin microcapsule structures are coated in the phase change materials, and leakage of the phase change materials in the phase change process is prevented. In this embodiment, the pre-polymerized liquid and the emulsion generate a nano microcapsule initial liquid after reaction; and then adding the flow stability auxiliary agent into the initial solution of the nano microcapsule, wherein the flow stability auxiliary agent can be combined on the surface of the urea resin microcapsule structure through Van der Waals force and form a film layer, and the film layer can reduce the resistance of microcapsule particles to each other, intermolecular acting force and resistance between microcapsule particles and deionized water, so that the suspension flow of the microcapsule particles can be effectively enhanced. Furthermore, by adding the flow enhancement nano particles into the dry matter of the nano microcapsule phase change material, the agglomeration of the dry matter of the nano microcapsule phase change material can be prevented, and the rapid dispersion of the dry matter of the nano microcapsule phase change material is facilitated. That is, in this embodiment, by adding a film layer formed by a flow stability auxiliary agent on the surface of the conventional microcapsule resin and adding a flow enhancement nanoparticle manner, the interaction force between microcapsule particles is effectively reduced, and simultaneously, the friction force between the microcapsule particles and the carrier aqueous solution is reduced, so that the stability, the cold accumulation efficiency and the dispersion uniformity of the microcapsule particles of the suspension phase change material of the nano microcapsule are improved while the fluidity is maintained on the premise of reducing the addition amount of the thickener.
In some specific embodiments, the nanocapsule suspension phase change material can be prepared by the following method: adding 1-10 parts of urea and 1-10 parts of formaldehyde into 10-20 parts of deionized water, adding a pH regulator to regulate the pH of the solution to 7-8, stirring at 50-90 ℃ for 30-90min, and finally adding 10-20 parts of deionized water for dilution to prepare a prepolymer solution for later use; adding 5-30 parts of emulsifier, 1-5 parts of polymerizer, 3-20 parts of sodium chloride and 20-100 parts of phase change material into 50-150 parts of deionized water, and stirring at a speed of 500-2000rpm for 10-60min at a temperature of 40-90 ℃ to prepare emulsion for later use; adding the prepolymer into the emulsion at the rotating speed of 50-300rpm, adding pH regulating solution to regulate the pH to 3-4, raising the rotating speed by 30-80% after white turbidity appears in the reaction, and continuously stirring for 2-10h at the temperature of 40-60 ℃ to prepare nano microcapsule initial liquid; adding a pH regulating solution into the initial solution of the nano microcapsule to regulate the pH to 5-7, increasing the reaction temperature to 70-90 ℃, adding 1-25 parts of flow stability auxiliary agent, regulating the rotating speed to 500-1000rpm, and reacting for 0.5-3 hours to prepare the mixed solution of the nano microcapsule; filtering the nano microcapsule mixed solution, washing a precipitate obtained by filtering, and drying to obtain a nano microcapsule phase change material dry matter, wherein flow-enhanced nano particles are added into the nano microcapsule phase change material dry matter to obtain a nano microcapsule mixed dry matter; adding a density regulator into deionized water to enable the density of the prepared mixed solution to be the same as the density of the dry matter of the nano microcapsule phase change material, and adding 1-10 parts of thickener into the mixed solution to obtain microcapsule suspension medium liquid; and adding 50-100 parts of the mixed dry matter of the nano microcapsule into the microcapsule suspension medium liquid, and mixing to prepare the nano microcapsule suspension phase change material.
In some embodiments, the emulsifier is one or more of carboxylate, sulfate, sulfonate, sodium stearate, sodium lauryl sulfate, polyoxyethylene ethers, and polyoxypropylene ethers, but is not limited thereto.
In some embodiments, the polymerization agent is one or more of resorcinol, phenol, and cresol, but is not limited thereto.
In some embodiments, the phase change material is one or more of n-tetradecane, pentadecane, and hexadecane, but is not limited thereto. The phase transition temperature of the phase change material in this embodiment is 5-12 ℃.
In some embodiments, the pH adjuster is one or more of carboxylic acid, sulfonic acid, sulfinic acid, and thiocarboxylic acid, but is not limited thereto.
In some embodiments, the flow stability aid is one or more of PVA, polyethylene glycol, and SDS, but is not limited thereto.
In some embodiments, the flow enhancing nanoparticles are polytetrafluoroethylene particles, but are not limited thereto. Polytetrafluoroethylene particles having a diameter of 20-150nm are preferred in this embodiment.
In some embodiments, the density modulator is a water soluble salt, which may be sodium chloride, or an organic alcohol, which may be propanol, ethanol, or the like, as examples.
In some embodiments, the thickener is one or more of attapulgite, nano fumed silica, bentonite, aluminum silicate, and methylcellulose, but is not limited thereto.
In some embodiments, a nano microcapsule suspension phase change material is also provided, wherein the nano microcapsule suspension phase change material is prepared by adopting the preparation method of the nano microcapsule suspension phase change material. In this embodiment, the nano microcapsule suspension phase-change material may be used in a cold storage phase-change air conditioner, and the nano microcapsule suspension phase-change material is stored in a phase-change cold storage pool, because the nano microcapsule suspension phase-change material is formed by storing the phase-change material in microcapsules with micron-sized diameters and uniformly distributing the phase-change material in a liquid medium, the nano microcapsule suspension phase-change material remains in a liquid state before and after the phase-change material is stored, and has better flowing property, the nano microcapsule suspension phase-change material can release the stored cold energy into a cold supply air conditioner loop through a heat exchanger, so that the phase-change cold storage pool storing the nano microcapsule suspension phase-change material can be integrated through the heat exchanger structure, and the cold storage phase-change air conditioner has a simple structure and safe and stable operation, can realize night valley electricity cold storage and daytime peak electricity cold storage, thereby exerting the capacity of transferring peak load of the phase-change cold storage pool, and achieving the effects of saving energy and reducing cost. In this embodiment, the phase transition temperature of the phase change material is 5-12 ℃. Therefore, the base-loaded host can realize stable cold accumulation at night only by preparing cold water at 2-4 ℃, refrigeration is not required to be performed below 0 ℃, and the cold accumulation is performed only at night, so that the environment temperature is low, and the refrigeration efficiency of the base-loaded host is improved. In this embodiment, the microcapsule coats the phase-change material inside, so that the phase-change material can be ensured to perform phase change inside the microcapsule, and the problem that the circulating water is polluted due to leakage of the phase-change material can not occur.
The invention is further illustrated by the following examples:
example 1
The preparation method of the nano microcapsule suspension phase change material comprises the following steps:
1. preparing a prepolymerization liquid: to 10g of deionized water was added 3.1g of urea, 9.5g of formaldehyde, ethanolamine was added to adjust to ph=8, and the mixture was heated and stirred at 70 ℃ for 60 minutes at >50rpm. After completion, 25ml portions of deionized water were added for dilution.
2. And adding 8.5g of sodium stearate, 4g of cresol, 3g of sodium chloride, 40g of n-pentadecane and 1000rpm into 100ml of deionized water, stirring and emulsifying for 30 minutes, and keeping the temperature at 80 ℃ to prepare emulsion.
3. The rotation speed was adjusted to 300rpm, and the prepolymer was added to the emulsion while formic acid was added to adjust the pH to 3. And after the white turbidity appears in the reaction vessel, the speed of the stirrer is increased to 500rpm, the reaction is continued for 4 hours, and the temperature is controlled at 55 ℃ to prepare the nano microcapsule mixed solution.
4. The reaction temperature was raised to 80℃and pH 7 was adjusted by adding sodium hydroxide, 3.2g of SDS was added thereto and the rotation speed was adjusted to 1000rpm, and the reaction was continued for 2 hours.
5. Filtering after the reaction is finished, washing the precipitate with deionized water at the temperature of more than 50 ℃ for 3 times, drying the precipitate for 24 hours by adopting vacuum drying equipment to obtain the dry matter of the nano microcapsule phase change material, and adding 5g of polytetrafluoroethylene particles with the diameter of 70nm into the nano microcapsule to obtain 55g of the mixed dry matter of the nano microcapsule.
6. Sodium chloride was added to 100g of water so that the overall density of the microcapsules was the same as the density of the solution, and 1.5g of fumed silica was additionally added to adjust the overall viscosity to prepare a microcapsule suspension medium.
7. And adding 55g of the component nano microcapsule mixture into the obtained liquid, and fully stirring and mixing to obtain the nano microcapsule suspension phase change material.
Example 2
The preparation method of the nano microcapsule suspension phase change material comprises the following steps:
1. preparing a prepolymerization liquid: to 2g deionized water was added 4g urea, 5g formaldehyde, ethanolamine to adjust to ph=7, and heated to 50 ℃ for 30-90 minutes with >50rpm. After completion, 25ml portions of deionized water were added for dilution.
2. And adding 8.5g of sodium stearate, 4.5g of cresol, 3g of sodium chloride, 40g of n-pentadecane and 1000rpm into 100ml of deionized water, stirring and emulsifying for 30 minutes, and keeping the temperature at 80 ℃ to prepare emulsion.
3. The rotation speed is regulated to 300rpm, the prepolymer liquid is added into the emulsion, and hydrochloric acid is added to regulate the PH to 3-4. And after the white turbidity appears in the reaction vessel, the speed of the stirrer is increased to 500rpm, the reaction is continued for 4 hours, and the temperature is controlled at 55 ℃ to prepare the nano microcapsule mixed solution.
4. The reaction temperature was increased to 80℃and pH 7 was adjusted by adding sodium hydroxide, and the rotational speed was adjusted to 500rpm by adding 3.2g of polyethylene glycol. The reaction was continued for 2 hours
5. Filtering after reaction, washing the precipitate with deionized water at the temperature of more than 50 ℃ for 3 times, and drying for 24 hours by adopting vacuum drying equipment to obtain the dry matter of the nano microcapsule phase change material, and adding 5g of polytetrafluoroethylene particles with the diameter of 70nm into the nano microcapsule to obtain 50g of mixed dry matter of the nano microcapsule.
6. Sodium chloride was added to 100g of water so that the overall density of the microcapsules was the same as that of the solution, and 1.3g of methylcellulose was additionally added to adjust the overall viscosity to prepare a microcapsule suspension medium.
7. And adding 50g of nano microcapsule mixture into the obtained liquid, and fully stirring and mixing to obtain the nano microcapsule suspension phase change material.
Comparative example 1
The preparation method of the nano microcapsule suspension phase change material comprises the following steps:
1. preparing a prepolymerization liquid: to 10g of deionized water was added 3.1g of urea, 9.5g of formaldehyde, ethanolamine was added to adjust to ph=8, and the mixture was heated and stirred at 70 ℃ for 60 minutes at >50rpm. After completion, 25ml portions of deionized water were added for dilution.
2. And adding 8.5g of sodium stearate, 4g of cresol, 3g of sodium chloride, 40g of n-pentadecane and 1000rpm into 100ml of deionized water, stirring and emulsifying for 30 minutes, and keeping the temperature at 80 ℃ to prepare emulsion.
3. The rotation speed was adjusted to 300rpm, and the prepolymer was added to the emulsion while formic acid was added to adjust the pH to 3. And after the white turbidity appears in the reaction vessel, the speed of the stirrer is increased to 500rpm, the reaction is continued for 4 hours, and the temperature is controlled at 55 ℃ to prepare the nano microcapsule mixed solution.
4. Filtering after the reaction is finished, washing the precipitate with deionized water at the temperature of more than 50 ℃ for 3 times, drying the precipitate for 24 hours by adopting vacuum drying equipment to obtain the dry matter of the nano microcapsule phase change material, and adding 5g of polytetrafluoroethylene particles with the diameter of 70nm into the nano microcapsule to obtain 55g of the mixed dry matter of the nano microcapsule.
5. Sodium chloride was added to 100g of water so that the overall density of the microcapsules was the same as the density of the solution, and 1.5g of fumed silica was additionally added to adjust the overall viscosity to prepare a microcapsule suspension medium.
6. And adding 55g of the component nano microcapsule mixture into the obtained liquid, and fully stirring and mixing to obtain the nano microcapsule suspension phase change material.
Comparative example 2
The preparation method of the nano microcapsule suspension phase change material comprises the following steps:
1. preparing a prepolymerization liquid: to 10g of deionized water was added 3.1g of urea, 9.5g of formaldehyde, ethanolamine was added to adjust to ph=8, and the mixture was heated and stirred at 70 ℃ for 60 minutes at >50rpm. After completion, 25ml portions of deionized water were added for dilution.
2. And adding 8.5g of sodium stearate, 4g of cresol, 3g of sodium chloride, 40g of n-pentadecane and 1000rpm into 100ml of deionized water, stirring and emulsifying for 30 minutes, and keeping the temperature at 80 ℃ to prepare emulsion.
3. The rotation speed was adjusted to 300rpm, and the prepolymer was added to the emulsion while formic acid was added to adjust the pH to 3. And after the white turbidity appears in the reaction vessel, the speed of the stirrer is increased to 500rpm, the reaction is continued for 4 hours, and the temperature is controlled at 55 ℃ to prepare the nano microcapsule mixed solution.
4. The reaction temperature was raised to 80℃and pH 7 was adjusted by adding sodium hydroxide, 3.2g of SDS was added thereto and the rotation speed was adjusted to 1000rpm, and the reaction was continued for 2 hours.
5. Filtering after the reaction is finished, washing the precipitate with deionized water at the temperature of more than 50 ℃ for 3 times, drying the precipitate for 24 hours by adopting vacuum drying equipment to obtain the dry matter of the nano microcapsule phase change material, and adding 5g of polytetrafluoroethylene particles with the diameter of 70nm into the nano microcapsule to obtain 55g of the mixed dry matter of the nano microcapsule.
6. A microcapsule suspension medium was prepared by adding 1.5g of fumed silica to 100g of water to adjust the overall viscosity.
7. And adding 55g of the component nano microcapsule mixture into the obtained liquid, and fully stirring and mixing to obtain the nano microcapsule suspension phase change material.
Comparative example 3
The preparation method of the nano microcapsule suspension phase change material comprises the following steps:
1. preparing a prepolymerization liquid: to 10g of deionized water was added 3.1g of urea, 9.5g of formaldehyde, ethanolamine was added to adjust to ph=8, and the mixture was heated and stirred at 70 ℃ for 60 minutes at >50rpm. After completion, 25ml portions of deionized water were added for dilution.
2. And adding 8.5g of sodium stearate, 4g of cresol, 3g of sodium chloride, 40g of n-pentadecane and 1000rpm into 100ml of deionized water, stirring and emulsifying for 30 minutes, and keeping the temperature at 80 ℃ to prepare emulsion.
3. The rotation speed was adjusted to 300rpm, and the prepolymer was added to the emulsion while formic acid was added to adjust the pH to 3. And after the white turbidity appears in the reaction vessel, the speed of the stirrer is increased to 500rpm, the reaction is continued for 4 hours, and the temperature is controlled at 55 ℃ to prepare the nano microcapsule mixed solution.
4. The reaction temperature was raised to 80℃and pH 7 was adjusted by adding sodium hydroxide, 3.2g of SDS was added thereto and the rotation speed was adjusted to 1000rpm, and the reaction was continued for 2 hours.
5. Filtering after the reaction is finished, taking the precipitate, washing the precipitate with deionized water with the temperature of more than 50 ℃ for 3 times, and then drying the precipitate for 24 hours by adopting vacuum drying equipment to obtain 50g of nano microcapsule phase change material dry matter.
6. Sodium chloride was added to 100g of water so that the overall density of the microcapsules was the same as the density of the solution, and 1.5g of fumed silica was additionally added to adjust the overall viscosity to prepare a microcapsule suspension medium.
7. And adding 55g of the component nano microcapsule mixture into the obtained liquid, and fully stirring and mixing to obtain the nano microcapsule suspension phase change material.
The nanocapsule suspension phase change materials prepared in examples 1 to 2 and comparative examples 1 to 3 were subjected to performance test, and the results are shown in Table 1.
TABLE 1 Performance test results
The difference between the latent heat of the top layer and the latent heat of the bottom layer can reflect the instability of the material after standing, because the apparent density of each microcapsule is difficult to be guaranteed to be completely consistent, the lighter microcapsules can stay in place after standing, the heavier microcapsules sink, and if the stability of microcapsule distribution is not high, or the difference between the carrier liquid and the microcapsule density is large, the situation that the difference between the top and bottom latent heat is large after standing can occur. Thus, the smaller the latent heat difference, the better while ensuring a low viscosity.
The viscosity is related to the friction between the microcapsules, the friction between the microcapsules and the carrier liquid, and the viscosity of the carrier liquid itself. The carrier fluid itself must ensure a basic consistency and density to prevent the microcapsules from delaminating too fast and to ensure a substantially stable distribution of the microcapsules. Therefore, the friction force between the microcapsules and the carrier liquid can be reduced, and the whole fluidity can be improved as much as possible under the condition that the adding proportion of the carrier liquid and the microcapsules is the same.
As can be seen from table 1, the viscosity of the nanocapsule suspension phase change material of examples 1 to 2 and comparative example 2 was significantly lower than that of comparative example 1, compared to comparative example 1. Specifically, after the flow stabilizing additive SDS is added in examples 1-2 and comparative example 2, the overall viscosity is reduced from 530 to 140 or so under the condition of the same thickener formulation and the same dry matter addition amount of the microcapsules, which indicates that the addition of the flow stabilizing additive SDS can significantly improve the overall flow of the nano-microcapsule suspension phase change material.
In comparison to comparative example 3, the viscosity of the nanocapsule suspension phase change material in examples 1-2 and comparative example 2 was significantly lower than that of comparative example 3. Specifically, after the flow enhancement nanoparticle polytetrafluoroethylene is added in examples 1-2 and comparative example 2, the overall viscosity is reduced from 480 to about 140 under the condition of the same thickener formulation and the same dry matter addition of the microcapsules, which shows that the addition of the flow enhancement nanoparticle polytetrafluoroethylene can significantly improve the fluidity of the whole suspension phase change material of the microcapsules.
The difference in latent heat between the top and bottom layers of the nano-microcapsule suspended phase change material in examples 1-2 and comparative examples 1 and 3 is significantly lower than that in comparative example 2. That is, the formula of adjusting the density without adding sodium chloride has a larger difference between the top latent heat and the bottom latent heat, so that the effect of improving the stable distribution of the microcapsules is achieved by adding NaCL to adjust the density.
It is to be understood that the invention is not limited in its application to the examples described above, but is capable of modification and variation in light of the above teachings by those skilled in the art, and that all such modifications and variations are intended to be included within the scope of the appended claims.
Claims (9)
1. The preparation method of the nano microcapsule suspension phase change material is characterized by comprising the following steps:
adding urea and formaldehyde into deionized water, regulating the pH of the solution to 7-8, stirring at 50-90 ℃ for 30-90min, and finally adding deionized water for dilution to obtain a prepolymer;
adding an emulsifier, a polymerizer, sodium chloride and a phase change material into deionized water, and stirring at a rotation speed of 500-2000rpm for 10-60min at a temperature of 40-90 ℃ to prepare emulsion;
adding the prepolymer into the emulsion at the rotating speed of 50-300rpm, adding pH regulating solution to regulate the pH to 3-4, raising the rotating speed by 30-80% after white turbidity appears in the reaction, and continuously stirring for 2-10h at the temperature of 40-60 ℃ to prepare nano microcapsule initial liquid;
regulating the pH of the initial solution of the nano microcapsule to 5-7, increasing the reaction temperature to 70-90 ℃, adding a flow stability auxiliary agent, regulating the rotating speed to 500-1000rpm, and reacting for 0.5-3 hours to obtain a mixed solution of the nano microcapsule;
filtering the nano microcapsule mixed solution, washing a precipitate obtained by filtering, and drying to obtain a nano microcapsule phase change material dry matter, wherein flow-enhanced nano particles are added into the nano microcapsule phase change material dry matter to obtain a nano microcapsule mixed dry matter;
adding a density regulator into deionized water to enable the density of the prepared mixed solution to be the same as the density of the dry matter of the nano microcapsule phase change material, and adding a thickener into the mixed solution to obtain microcapsule suspension medium liquid;
adding the mixed dry matter of the nano microcapsule into the microcapsule suspension medium liquid, and mixing to prepare the nano microcapsule suspension phase change material;
wherein the polymerizer is one or more of resorcinol, phenol and cresol.
2. The method for preparing a nano-microcapsule suspension phase-change material according to claim 1, wherein the emulsifier is one or more of carboxylate, sulfate, sulfonate, sodium stearate, sodium dodecyl sulfate, polyoxyethylene ether and polyoxypropylene ether.
3. The method of claim 1, wherein the phase change material is one or more of n-tetradecane, pentadecane and hexadecane.
4. The method for preparing a nano-microcapsule suspension phase-change material according to claim 1, wherein the pH adjuster is one or more of carboxylic acid, sulfonic acid, sulfinic acid and thiocarboxylic acid.
5. The method of preparing a nano-microcapsule suspended phase change material according to claim 1, wherein the flow stability aid is one or more of PVA, polyethylene glycol and SDS.
6. The method of claim 1, wherein the flow enhancing nanoparticles are polytetrafluoroethylene particles.
7. The method for preparing a nano-microcapsule suspension phase change material according to claim 1, wherein the density regulator is a water-soluble salt or an organic alcohol.
8. The method for preparing a nano-microcapsule suspension phase change material according to claim 1, wherein the thickener is one or more of attapulgite, nano fumed silica, bentonite, aluminum silicate and methylcellulose.
9. A nano microcapsule suspension phase change material, which is characterized in that the nano microcapsule suspension phase change material is prepared by the preparation method of any one of claims 1-8.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101298552A (en) * | 2008-06-13 | 2008-11-05 | 南京大学 | Nanocapsule phase-change material for cold storage and preparation thereof |
| CN110408365A (en) * | 2019-07-10 | 2019-11-05 | 浙江工业大学 | A kind of preparation method of phase-change microcapsule |
| CN113773810A (en) * | 2021-09-17 | 2021-12-10 | 广州市香港科大霍英东研究院 | Melamine resin shell phase change microcapsule and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101298552A (en) * | 2008-06-13 | 2008-11-05 | 南京大学 | Nanocapsule phase-change material for cold storage and preparation thereof |
| CN110408365A (en) * | 2019-07-10 | 2019-11-05 | 浙江工业大学 | A kind of preparation method of phase-change microcapsule |
| CN113773810A (en) * | 2021-09-17 | 2021-12-10 | 广州市香港科大霍英东研究院 | Melamine resin shell phase change microcapsule and preparation method thereof |
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