CN-122012029-A - Dihydrate oxalic acid-boric acid eutectic phase change composite material and preparation method and application thereof

Abstract

The invention discloses a dihydrate oxalic acid-boric acid eutectic phase change composite material, and a preparation method and application thereof. The dihydrate oxalic acid-boric acid eutectic phase change composite material takes dihydrate oxalic acid and boric acid as eutectic phase change material components, takes fumed silica as a porous adsorption carrier, takes expanded graphite as conductive filler, and realizes the compounding by a melt blending method. The material utilizes the high specific surface area and the mesoporous structure of the fumed silica to effectively adsorb the eutectic phase change material component in the pore canal of the fumed silica, and the expanded graphite is used as a lamellar heat conduction enhancing component, so that a continuous heat conduction passage is constructed in the material, and the thermal response capability and the structural stability of the dihydrate oxalic acid-boric acid eutectic phase change composite material are improved. By regulating and controlling the proportion of each component, the dihydrate oxalic acid-boric acid eutectic phase change composite material can remarkably improve the morphological stability and the cyclic stability while keeping higher latent heat of phase change. The material has simple preparation process and can be widely applied to the fields of medium-high temperature heat storage and electric heat conversion management.

Inventors

• FANG XIAOMING
• ZHUO JIAJIA
• ZHANG ZHENGGUO
• LING ZIYE

Assignees

• 华南理工大学

Dates

Publication Date

20260512

Application Date

20260126

Claims (10)

1. 1. The dihydrate oxalic acid-boric acid eutectic phase change composite material is characterized by comprising eutectic phase change material components, a porous adsorption carrier and conductive filler, wherein the eutectic phase change material components are boric acid and dihydrate oxalic acid, the porous adsorption carrier is fumed silica, and the conductive filler is expanded graphite.
2. 2. The dihydrate oxalic acid-boric acid eutectic phase change composite material according to claim 1, wherein the eutectic phase change material composition comprises 88 parts by mass of dihydrate oxalic acid and 12 parts by mass of boric acid.
3. 3. The oxalic acid dihydrate-boric acid eutectic phase change composite material according to claim 2, wherein the purity of the boric acid is 99% or more and the purity of the oxalic acid dihydrate is 99% or more.
4. 4. The oxalic acid-boric acid dihydrate eutectic phase change composite material of claim 1, wherein the oxalic acid-boric acid dihydrate eutectic phase change composite material comprises an oxalic acid-boric acid dihydrate/silica eutectic phase change material.
5. 5. The dihydrate oxalic acid-boric acid eutectic phase change composite material according to claim 4, wherein the ratio of the porous adsorption carrier to the conductive filler to the eutectic phase change material component in parts by mass is 5-35:0:65-95, and the sum of the porous adsorption carrier, the conductive filler and the eutectic phase change material component in parts by mass is 100 parts.
6. 6. The oxalic acid-boric acid dihydrate eutectic phase change composite material of claim 1, wherein the oxalic acid-boric acid dihydrate eutectic phase change composite material comprises oxalic acid-boric acid dihydrate/silica/expanded graphite eutectic phase change material.
7. 7. The dihydrate oxalic acid-boric acid eutectic phase change composite material according to claim 6 is characterized in that the ratio of the porous adsorption carrier to the conductive filler to the eutectic phase change material component in the dihydrate oxalic acid-boric acid/silicon dioxide/expanded graphite eutectic phase change material is 6-14:1-9:85 in parts by mass, and the sum of the porous adsorption carrier, the conductive filler and the eutectic phase change material component is 100 parts by mass.
8. 8. Claim 1 of The method for preparing the dihydrate oxalic acid-boric acid eutectic phase change composite material according to any one of claims 7, which is characterized by comprising the following steps: (1) Boric acid and oxalic acid dihydrate are mixed, heated and melted to obtain a clear and transparent melted mixture which is a eutectic phase change material component; (2) Adding the porous adsorption carrier and the conductive filler into the molten mixture and continuing stirring; (3) And (3) cooling and crystallizing the molten mixture obtained in the step (2) to obtain the dihydrate oxalic acid-boric acid eutectic phase change composite material.
9. 9. The method of claim 8, wherein the cooling condition in step (3) is sealing and the cooling temperature is room temperature.
10. 10. The application of the dihydrate oxalic acid-boric acid eutectic phase change composite material in the fields of medium-temperature heat storage and electrothermal conversion.

Description

Dihydrate oxalic acid-boric acid eutectic phase change composite material and preparation method and application thereof Technical Field The invention relates to the technical field of phase change energy storage materials, in particular to a dihydrate oxalic acid-boric acid eutectic phase change composite material and a preparation method and application thereof. Background Along with the continuous improvement of energy structure adjustment and renewable energy utilization ratio, efficient storage and regulation of heat energy become an important research direction in the field of energy utilization. The phase-change heat storage technology can absorb or release a large amount of heat in a near-constant temperature mode in the phase-change process, has the advantages of high heat storage density, stable operation and the like, and is widely applied to solar heat utilization, industrial waste heat recovery, building energy conservation and thermal management systems. The medium-temperature Duan Xiangbian heat storage material (about 80-120 ℃) has important application value in practical engineering, can meet the working temperature requirements of various industrial and civil systems, and also has the safety and the material stability of the system. In recent years, with rapid development of electric heating technology and electric heat conversion systems, attention has been paid to heat management and heat storage based on electric energy driving. In devices such as electrically heated energy storage devices, electrically driven thermal management systems and partly energy storage and temperature regulating devices, the electrothermal conversion unit generally converts electrical energy directly into thermal energy and achieves the storage and slow release of heat by means of heat storage materials. The existing research shows that in most electric heat conversion application scenes, the system working temperature is generally concentrated in a medium temperature range, and particularly has higher application frequency in a range of 80-120 ℃. In the temperature range, if the phase change of the matched heat storage material is too low, the heat storage effect is difficult to fully play, and if the phase change temperature is too high, the electric heat conversion efficiency is reduced, and the energy consumption of the system is increased. Therefore, the development of the phase-change heat storage material which has the phase-change temperature matched with the electrothermal conversion working interval, higher heat storage capacity and stable operation has important significance for improving the overall performance of the electrothermal conversion system （Xiao Q, Xu Y, Li X, et al. Enhanced solar-thermal and electro-thermal storage performance of solid-solid composite phase change material[J]. Composites Communications, 2024, 45: 101818.）. The phase-change heat storage materials commonly used at present mainly comprise organic phase-change materials, inorganic hydrated salt materials and eutectic phase-change materials. Although the organic phase change material has better chemical stability, the problems of lower heat conduction performance, limited phase change latent heat, limited temperature resistant range and the like generally exist, and the heat storage density and the response speed are difficult to be combined in the electrothermal conversion application. The eutectic phase change material can realize accurate regulation and control of the phase change temperature through multicomponent cooperation, and has larger application potential in the field of medium temperature Duan Chure （Islam A, Pandey A K, Saidur R, et al. Shape stable composite phase change material with improved thermal conductivity for electrical-to-thermal energy conversion and storage[J]. Materials Today Sustainability, 2024, 25: 100678..） The eutectic system formed by the dihydrate oxalic acid and the boric acid has more proper phase transition temperature and higher latent heat in the medium temperature range, can cover a typical working temperature area of part of the electric heat conversion system, and has the basic condition of being used as a medium-temperature phase transition heat storage material. However, the eutectic phase change material is easy to cause the problems of molten state migration and liquid leakage in the phase change process, particularly under the condition of electrothermal conversion, the material is often subjected to a faster heating process, the duration of the molten state is longer, the leakage risk is further increased, the problems of unstable material form, latent heat attenuation, structural damage and the like are caused, and the engineering application of the eutectic phase change material is severely restricted （Xie S, Sun J, Wang Z, et al. A thermally stable phase change material with high latent heat based on an oxalic acid dihydrate/boric acid binary eutectic system[J]. Solar Ener