CN-122012039-A - Heat storage particles, and preparation method and application thereof

CN122012039ACN 122012039 ACN122012039 ACN 122012039ACN-122012039-A

Abstract

The invention relates to the technical field of heat storage, and discloses heat storage particles, and a preparation method and application thereof. The heat storage particles comprise a conductive magnetic core and a heat storage outer shell layer coating the conductive magnetic core, wherein the heat conductivity of the core is larger than that of the outer shell layer. The preparation method comprises the steps of core preparation, surface roughening treatment, core-shell cladding granulation and green body heat treatment solidification. The heat storage system comprises the heat storage particles, a heat storage tank body, an induction coil and an induction power supply. The heat storage particles utilize the conductive magnetic core as an internal heat source in an alternating magnetic field to directly generate heat, so that the rapid and uniform heating from the inside of the particles to the outer shell layer is realized, the problems of heat transfer lag, large temperature gradient, easy particle damage and the like caused by external heating are effectively overcome, and the heat storage and release rate and the circulation stability are improved.

Inventors

ZHU PEIWANG
DING CHENGJIN
XIAO GANG

Assignees

浙江大学

Dates

Publication Date: 20260512
Application Date: 20260119

Claims (10)

1. A heat storage pellet comprising: a conductive core; the heat storage shell layer is coated outside the conductive magnetic core; the thermal conductivity of the electrically and magnetically conductive core is greater than the thermal conductivity of the thermal storage outer shell layer.
2. The heat storage particle of claim 1, wherein the material of the electrically and magnetically permeable core is selected from one or more of low carbon steel, iron-nickel alloy, iron-chromium-aluminum alloy.
3. The heat storage particle of claim 1, wherein the surface of the electrically conductive magnetically permeable core is structured with a roughened structural layer by sandblasting or chemical etching.
4. The heat storage particle of claim 1, wherein the diameter of the electrically conductive magnetically permeable core is greater than twice its skin depth at the operating frequency.
5. The heat storage particle of claim 1, wherein the heat storage particle is a sensible heat storage type heat storage particle and the heat storage shell layer of the sensible heat storage type heat storage particle is a sensible heat storage shell layer; the sensible heat storage type shell layer is doped with a heat conducting filler or an electric conducting auxiliary phase; the particle size of the sensible heat storage type heat storage particles is 10-30 mm, and the diameter of the conductive magnetic core accounts for 30-40% of the particle size of the sensible heat storage type heat storage particles.
6. The heat storage particles of claim 1, wherein the heat storage particles are thermochemical heat storage type heat storage particles and the heat storage outer shell layer of the thermochemical heat storage type heat storage particles is a thermochemical heat storage outer shell layer; The thermochemical heat storage type shell layer is doped with a pore-forming agent; The particle size of the thermochemical heat storage type heat storage particles is 20-50 mm, and the diameter of the electric conduction magnetic conduction core accounts for 15-25% of the particle size of the thermochemical heat storage type heat storage particles.
7. The heat storage particle of claim 1, wherein the shape of the heat storage particle is spherical, spindle-shaped, or drop-shaped.
8. A method for preparing a heat storage granule, applied to a heat storage granule according to any one of claims 1 to 7, comprising the steps of: preparing a conductive magnetic core, namely processing a conductive magnetic material into a conductive magnetic core; Surface roughening treatment, namely performing surface roughening treatment on the surface of the conductive magnetic core; Coating, granulating and molding a core-shell structure, namely taking the electric conduction and magnetic conduction core obtained in the step of roughening the surface of the core as a granulating seed crystal, and covering the surface of the electric conduction and magnetic conduction core with heat storage shell layer powder through an adhesive until the particle size reaches a set particle size to obtain a green compact of heat storage particles; And (3) carrying out heat treatment and solidification on the green compact, so as to obtain the heat storage particles.
9. A heat storage system comprising the heat storage particles of any one of claims 1-7, a heat storage tank body, an induction coil, and an induction power source, the induction coil being electrically connected to the induction power source, the heat storage particles being disposed within the heat storage tank body, the electrically and magnetically conductive core being heated in an alternating electromagnetic field generated by the induction coil, the generated heat being transferred to and stored by the heat storage outer shell layer.
10. The heat storage system of claim 9, further comprising a flow equalization plate, the heat storage tank body comprising a first opening and a second opening, the flow equalization plate disposed within the heat storage tank body proximate the first opening and the second opening.

Description

Heat storage particles, and preparation method and application thereof Technical Field The invention relates to the technical field of heat storage, in particular to heat storage particles, and a preparation method and application thereof. Background The heat storage technology is used as a key means for balancing energy supply and demand and improving the utilization efficiency of renewable energy sources, and has wide application in the fields of industrial waste heat recovery, solar thermal power generation and the like. The solid heat storage particles become an important medium of the heat storage system due to the advantages of wide working temperature range, low cost, easy large-scale filling and the like. Conventional solid heat storage materials, such as sensible heat storage materials of metal oxides, silicate rocks or concrete, and thermochemical heat storage materials of metal hydroxides, carbonates, etc., usually employ indirect heating, i.e. by heating the walls of the metal container or internal heat exchange elements, and then transfer heat from outside to inside to the particle bed. In this heating mode, heat is transferred from outside to inside the particle bed. Because the thermal conductivity of the solid heat storage material is generally low, and the gas-solid contact thermal resistance exists in the particle stacking bed layer, the heat transfer process is slow, the thermal response is delayed, and part of the heat storage capacity is difficult to effectively use. Meanwhile, the external heating is easy to form a larger temperature gradient in the particle and radial direction of the bed layer, and thermal stress is induced in thermal circulation, so that the problems of micro-cracks, pulverization and the like on the surface of the particle are caused, and the long-term stability of the system is influenced. For thermochemical heat storage particles, external heating may also cause surface sintering, blocking gas diffusion channels, reducing reaction efficiency. Disclosure of Invention Aiming at how to improve the heating rate and uniformity of the heat storage particles under heating and avoiding the problems of heat transfer resistance, large temperature gradient and easy damage of the particles, the invention provides the heat storage particles and a preparation method and application thereof. The first aspect of the present invention provides a heat storage particle. The heat storage particles comprise an electric conduction magnetic core and a heat storage shell layer coated outside the electric conduction magnetic core, wherein the heat conductivity of the electric conduction magnetic core is larger than that of the heat storage shell layer. The conductive core is used as an internal heat source, heat is directly generated in an alternating magnetic field, the heating of the body from the inside of the particle to the outside is realized, and the radial temperature distribution is reconstructed, so that the particle has the gradient characteristics of high internal temperature and low external temperature. Compared with the gradient of high external temperature and low internal temperature formed by the traditional external heating mode, the internal heating mode enables the heat transfer direction and the temperature gradient direction to be from inside to outside, so that the cracking risk of the outer shell layer caused by tensile stress is effectively reduced, the heating rate and the uniformity are improved as a whole, and the damage risk of particles caused by thermal stress is remarkably reduced. Optionally, the material of the conductive magnetic core is selected from one or a combination of a plurality of low-carbon steel, iron-nickel alloy and iron-chromium-aluminum alloy. The materials have high magnetic conductivity and high electric conductivity, can efficiently generate eddy current heat in an alternating magnetic field, and improve induction heating efficiency. Optionally, the surface of the conductive magnetic core is structured with a roughened structural layer obtained by sandblasting or chemical etching. The roughened structure can enhance the mechanical binding force between the core and the outer shell layer, prevent interface peeling, reduce contact thermal resistance and improve heat transfer. Optionally, the diameter of the electrically and magnetically permeable core is greater than twice its skin depth at the operating frequency. This ensures that electromagnetic energy is mainly absorbed by the core and converted into heat energy, avoiding energy transmission loss, and improving heating efficiency. The heat storage particles are optionally sensible heat storage type heat storage particles, a heat storage shell layer of the sensible heat storage type heat storage particles is sensible heat storage type shell layer, a heat conducting filler or an electric conduction auxiliary phase is doped in the sensible heat storage type shell layer, the particle si