Method for preventing loss of molten salt phase-change heat storage material by utilizing activated carbon

Abstract

The invention discloses a method for preventing loss of a molten salt phase-change heat storage material by utilizing activated carbon, and belongs to the field of phase-change heat storage materials.The method comprises the following steps: (1) preparing molten salt particles; (2) adsorbing the molten salt phase-change material by activated carbon; and (3) mixing, pressing and sintering a sample. The molten salt phase-change material is adsorbed by adopting activated carbon, the large molten salt particles are prepared by utilizing a pressing and granulating method based on a stable phase-change heat storage material preparation process, the large molten salt particles are adsorbed by adopting the activated carbon, and finally activated carbon powder adsorbing the molten salt phase-change material and a binder are mixed, pressed and sintered to obtain a composite phase-change heat storage body. The preparation method is simple, low in cost and suitable for large-scale production, notonly solves the problem that the molten salt phase-change material is easy to lose in the use process, but also is long in use period and excellent in mechanical property, and has great significancefor expanding the use of the phase-change heat storage material.

Description

technical field [0001] The invention belongs to the field of phase change heat storage materials, and in particular relates to a method for preventing the loss of molten salt phase change heat storage materials by using activated carbon. Background technique [0002] As a national strategic emerging industry, energy storage technology is an important part of energy conversion and utilization technology. Selecting an appropriate energy storage technology route is important for improving the utilization efficiency of renewable energy, enhancing the peak regulation capacity of thermal power generation, and alleviating grid dispatch. It is of great significance, and its large-scale application will have a significant impact on energy transformation, power grid pattern, and power supply structure. Heat storage material is the core and key of heat storage technology. It collects and stores excess energy that is temporarily unused for a period of time or a certain space, and releas...

AI Technical Summary

Problems solved by technology

[0003] Molten salt phase change materials have high heat storage density and low cost, and are a hotspot in the field of energy storage materials. However, there are still many problems in the heat storage system of molten salt as a phase change heat storage material. Loss, insufficient mechanical properties of heat storage body, etc.

These problems have seriously affected the application cycle and range of use of the heat storage body, and urgently need to be resolved

[0004] Researchers at home and abroad mainly adopt the method of overall encapsulation to solve this problem. Ryo Fukahori (Fukahori R, Nomura T, Zhu C, Sheng N, Okinaka N, Akiyama T. [J].Appl Energy 2016; 170:324-8) Ceramic cups are used to encapsulate the molten salt, and the molten salt is placed in the ceramic cup body and sealed on the outer layer. This method can isolate the humidity environment and provide a supporting structure. The cup The space of the body can leave an expansion space for the molten salt to solve the problem of the large expansion coefficient of the molten salt, but this method is cumbersome to prepare and the cost is high; the bonding between the ceramic cup and the cup cover will appear to fall off and age as the number of cycles increases phenomenon; Pau Gimenez (Gimenez P, Fereres S. Glass encapsulated phase change materials for high temperature thermal energy storage [J]. Renewable Energy, 2017, 107: 497-507.) adopted NaNO 3 Inject glass spheres to play the role of encapsulation and support. Although this method can completely solve the problem of hygroscopicity of molten salt in an integrated way and provide a support structure at room temperature, the process is difficult, and at high temperatures, the glass will soften. phenomenon, and the softened glass cannot bear the weight of the molten salt, which leads to the leakage of the molten salt from the bottom, which not only fails to play a structural support role, but also makes the entire material invalid; TEAP and EPS Ltd (Pendyala S.Macroencapsulation of Phase Change Materials for Thermal Energy Storage [J]. Dissertations&Theses-Gradworks, 2012.) Using polymer and metal materials to encapsulate the molten salt into the ball body can isolate the molten salt from the external humidity environment and provide a stable structural shape, but this This method not only increases the preparation cost and complicates the process, but also the lower service temperature range of the polymer and the high conductivity of the metal material severely limit the application environment of electric heating; Bhardwaj (Bhardwaj A.Metallic Encapsulation for High Temperature (>500 ℃) Thermal Energy Storage Applications[J].2015.) Carbon steel and nickel are used to encapsulate and granulate NaCl-KCl eutectic salt, the carbon steel cylinder is coated with nickel, and the molten salt is placed in the carbon steel cylinder. The material prepared by this method has good thermal conductivity and thermal stability, and can withstand 1700 thermal cycles between 580°C and 680°C. It is easy to rust in the environment. Although the molten salt is prevented from absorbing moisture, the rust of the container will still lead to failure, and carbon steel and nickel are also conductive, which is easy to cause short circuit in the electric heating environment; Noemí Arconada (Arconada N, Arribas L, LucioB, et al. Macroencapsulation of sodium chloride as phase change materials for thermal energy storage [J]. Solar Energy, 2018, 167:1–9.) Using TiO 2 with SiO 2 As the encapsulation material, the sol-gel method is used to coat the NaCl molten salt column to produce microcapsule particles. This method can isolate the molten salt from the external environment in a humid environment and avoid the problem of moisture absorption. The process is complicated, the cost is high, and industrial production is difficult to realize, and SiO 2 The heat conduction is poor, so although the moisture absorption problem is solved, the heat storage performance is reduced; Li et al. (Li J, Lu W, Luo Z, et al. Synthesis and thermal properties of novelsodium nitrate microcapsules for high-temperature thermal energy storage[J].Solar Energy Materials&Solar Cells,2017,159:440-446.) using polysilazane to treat NaNO 3 Microcapsule encapsulation, this method can prepare relatively uniform particles, and there is no significant change in melting point and heat storage capacity, but not only the preparation process is complicated, but also the melting point of the encapsulating material polysilazane is low, so it is not suitable for medium and high temperature molten salt phase variable heat storage materials; Diatomite encapsulates the NaCl-KCl eutectic salt particles, uses the method of spraying diatomite to encapsulate the molten salt particles, and uses diatomite as the matrix material to provide structural support for the brick body. This method is currently relatively The advanced method can not only reduce the contact area between the molten salt and the humidity environment, but also provide a structural matrix material for the block. However, although this method reduces the contact area between the molten salt and the air, the sintering temperature of the brick is far away. The sintering temperature is lower than that of diatomite, so the inside of the sintered block is not dense, so the water can still pass through the gaps in the block and contact the molten salt

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