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CN-116554838-B - Hectorite@paraffin microcapsule latent heat fluid and preparation method thereof

CN116554838BCN 116554838 BCN116554838 BCN 116554838BCN-116554838-B

Abstract

The invention relates to a hectorite@paraffin microcapsule latent heat fluid and a preparation method thereof. The latent heat fluid comprises hectorite and paraffin microcapsule phase-change material and solvent, wherein the mass fraction of the hectorite and paraffin microcapsule phase-change material is not more than 50%. The preparation method comprises the steps of dispersing hectorite in a solvent, stripping the hectorite into hectorite nanosheets, adding a cationic modifier for modification to obtain a modified hectorite nanosheets suspension, mixing a phase change material, an anionic modifier and water to react to obtain a modified phase change material emulsion, adding the modified hectorite nanosheets suspension into the modified phase change material emulsion, uniformly mixing to obtain a latent heat fluid initial solution, and finally obtaining a target latent heat fluid through the procedures of dilution, concentration or drying, redispersion and the like. The latent heat fluid provided by the invention has better heat conduction and storage capacity, suspension stability and lower viscosity, and has better application prospects in heating, heat exchange and other aspects.

Inventors

  • YI HAO
  • LI MINGHUI
  • SONG SHAOXIAN

Assignees

  • 武汉理工大学

Dates

Publication Date
20260505
Application Date
20230228

Claims (10)

  1. 1. The latent heat fluid is characterized by comprising a hectorite@paraffin microcapsule and a solvent, wherein the hectorite@paraffin microcapsule has a core-shell structure, paraffin is a core, and a hectorite nano-sheet is a shell, and the solvent is at least one selected from water, alcohol and oil.
  2. 2. The latent heat fluid according to claim 1, wherein the mass fraction of hectorite @ paraffin microcapsules in the latent heat fluid is not more than 50%.
  3. 3. The latent heat fluid according to claim 2, wherein the mass fraction of hectorite@paraffin microcapsules in the latent heat fluid is 5% -10%.
  4. 4. The preparation method of the latent heat fluid is characterized by comprising the steps of (a) stripping hectorite into hectorite nanosheets, then modifying by a cationic modifier to obtain modified hectorite nanosheets suspension, wherein the cationic modifier is at least one selected from cetyltrimethylammonium bromide, octadecyldimethylbenzyl ammonium chloride, octadecyltrimethylammonium chloride and dodecyl trimethylammonium chloride, (b) mixing paraffin, an anionic modifier and a solvent for reaction to obtain modified paraffin emulsion, and the anionic modifier is at least one selected from sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate and sodium benzene sulfonate, (c) adding the modified hectorite nanosheets suspension prepared in the step (a) into the modified paraffin emulsion, uniformly mixing to obtain a latent heat fluid initial liquid, and diluting or concentrating or drying and redispersing the latent heat fluid initial liquid.
  5. 5. The method of claim 4, wherein step (a) comprises adding laponite to the solvent, stirring thoroughly at 200-1500rpm for 3-24 hours, then removing laponite into nanosheets by ultrasonic and high shear, and then adding the cationic modifier to modify for 3-24 hours at 200-1500 rpm.
  6. 6. The method of claim 5, wherein the ultrasonic power is 100-500W, the ultrasonic time is 5-20min, the high-speed shearing rotating speed is 2000-15000rpm, and the high-speed shearing time is 5-20min.
  7. 7. The method of claim 4, wherein the hectorite and the cationic modifier are added in an amount corresponding to 0.1% to 6% by mass of the suspension in step (a).
  8. 8. The method according to claim 4, wherein in the step (b), the paraffin, the anionic modifier and the solvent are mixed and then stirred sufficiently at 200-1500rpm and 55-75 ℃, and then the mixture is sheared for 5-20min at 2000-15000rpm to complete the modification.
  9. 9. The method of claim 4, wherein the emulsion of step (b) comprises 1 to 30% by weight of paraffin wax and 0.1 to 5% by weight of anionic modifier.
  10. 10. The method of claim 4, wherein in step (c) after the modified paraffin emulsion is cooled to room temperature, the modified hectorite nanosheet suspension is added, and the mixture is stirred at room temperature at 200-1500rpm for 3-24 hours to obtain a latent heat fluid initial liquid.

Description

Hectorite@paraffin microcapsule latent heat fluid and preparation method thereof Technical Field The invention relates to the technical field of phase change materials and fluids, in particular to a hectorite@paraffin microcapsule latent heat fluid and a preparation method thereof. Background The latent heat fluid is a novel working medium integrating heat storage and enhanced heat transfer, and is formed by dispersing phase change material particles into a single-phase heat transfer fluid. Because of the excellent thermal performance, the latent heat fluid has wide application prospect in the fields of building heating, air conditioning systems, heat exchangers and the like. In general, the performance of a latent heat fluid is determined primarily by the nature of the particles of phase change material dispersed therein. Because the density difference exists between the phase change material particles and the dispersion medium, and the surfaces of most of the phase change material particles are organic matters, the phase change material particles have poor compatibility with water, so that the problems of layering, aggregation of the phase change material particles, poor heat conduction performance and the like are easy to occur. In addition, the phase change material particles in the latent heat fluid cause the viscosity of the suspension fluid to increase and the fluidity to be poor, so that the pipeline is easy to be blocked, and the power of the pump is increased. Zhao Zhenna et al (Zhao Zhenna, wu Ting, ind. Rain et al. Rheological and heat transfer Property study of phase-change emulsions [ J ]. Programme thermal Physics, 2001,22 (5): 589) the emulsion prepared had a tetradecane content of 0.163, a viscosity of 16 times that of water at 278.15K, and the emulsion exhibited significant non-Newtonian fluid properties and was not readily flowable. Zhang Yinping et al (Xu H,Yang R,Zhang Y P,et al.Thermal physical proper,ties and key influence factors of phase change emulsion[J].Chinese Sci Bull,2005,50(1)：88) prepared an emulsion having a viscosity 5 times that of water, but the thermal conductivity of the emulsion was very small, about 0.1-0.2W/(mK), and the thermal conductivity of water was about 0.6W/(mK). The hectorite has natural superior dispersion performance and heat conduction performance in water, and the microcapsule phase change material with the density consistent with that of the water phase can be obtained under the condition of not adding a thickening agent by adjusting the ratio of the hectorite in the microcapsule phase change material, so that the hectorite can be stably suspended and dispersed in the water, and thus, the high-performance latent heat fluid is obtained. Disclosure of Invention The invention aims to solve the problems of poor dispersion performance, high viscosity, low heat conduction performance and the like commonly existing in the existing latent heat fluid, and provides a brand new latent heat fluid, wherein the components of the latent heat fluid comprise hectorite@paraffin microcapsules and solvents, the hectorite@paraffin microcapsules have a core-shell structure, and paraffin is a core and a hectorite nano-sheet is a shell. Further, the solvent is at least one selected from water, alcohol and oil, preferably water. Further, the mass fraction of hectorite@paraffin microcapsules in the latent heat fluid is not more than 50%, preferably 5% -10%. The second object of the invention is to provide a preparation method of the latent heat fluid, which comprises the following steps of (a) dispersing hectorite in a solvent such as ultrapure water and stripping the hectorite into hectorite nanosheets, then adding a cationic modifier for modification to obtain a modified hectorite nanosheets suspension, (b) mixing a phase change material, an anionic modifier and water or other solvents for modification to obtain a modified phase change material emulsion, (c) adding the modified hectorite nanosheets suspension obtained in the step (a) into the modified phase change material emulsion, uniformly mixing to obtain a latent heat fluid initial liquid, and diluting or concentrating or drying the latent heat fluid initial liquid and redispersing the latent heat fluid initial liquid to obtain the target latent heat fluid. Further, the step (a) is to add the hectorite into the solvent, stir for 3-24 hours at the rotation speed of 200-1500rpm, then peel the hectorite into nano-sheets by adopting a mode of ultrasonic firstly and then high-speed shearing, wherein the ultrasonic power is 100-500W, the ultrasonic time is 5-20 minutes, the high-speed shearing rotation speed is 2000-15000rpm, the high-speed shearing time is 5-20 minutes, and the cationic modifier is added and then modified for 3-24 hours at the rotation speed of 200-1500 rpm. Further, the addition amount of the hectorite and the cationic modifier in the step (a) is 0.1% -6% of the mass of the suspension, and the cationic modif