400V voltage grade induction type electric heating solid heat storage device

Abstract

The utility model provides a 400V voltage grade induction type electric heating solid heat storage device, a heat storage unit is made of cast iron, and a heating element is a coil. Under the action of a generated alternating magnetic field, when magnetic flux on the surface of cast iron changes, induced electromotive force can be spontaneously formed in a conductor loop, then eddy current is formed in a metal conductor to achieve the heating purpose, the maximum heat storage temperature of the device exceeds 1000 DEG C, the overall average temperature can be 900 DEG C, and the device has good heat storage characteristics. And when the heat release stage is finished, the temperature of the heat accumulator is maintained within the range of 300-500 DEG C. The overall geometric structure of the device is composed of a heat storage body, induction heating coils, a device shell, a controller, a frequency conversion fan and the like, a plurality of ventilation opening channels are formed in the heat storage body, the induction heating coils in the electric heating energy storage device are geometrically in a circular ring shape and evenly arranged on the heat storage body in a sleeving mode according to a certain distance, and the stored heat is driven by fluid to be output through the controller.

Description

Technical Field

[0001] The utility model relates to the technical field of heat storage, and more specifically, to an inductive electric heating solid heat storage device with a 400V voltage level. Background Art

[0002] Solid electric heat storage devices are widely regarded as an effective means to solve the problem of new energy consumption, and have made indelible contributions to the new energy consumption in China. However, at present, most solid electric heat storage devices use resistive heating, which has many problems such as long heating time, uneven temperature, easy aging of resistance elements, single heat storage material, and complex high-voltage insulation. Therefore, we have made improvements and proposed an inductive electric heating solid heat storage device with a 400V voltage level. Summary of the Utility Model

[0003] The purpose of the utility model is to address the problems raised in the existing background art. To achieve the above utility model purpose, the utility model provides the following technical solutions: An inductive electric heating solid heat storage device with a 400V voltage level, including a heat storage body and a thermal insulation layer. An induction heating coil is sleeved on the outer surface of the heat storage body. Seven ventilation openings are formed throughout the heat storage body. The main channel is located at the central position of the ventilation openings, and the auxiliary air ducts are located on the periphery.

[0004] As a preferred technical solution of the utility model, the heat storage body is connected to a variable-frequency fan, a gap is provided between the induction heating coils, and a device housing is provided on the outer surface of the heat storage body.

[0005] As a preferred technical solution of the utility model, the variable-frequency fan is connected to a diverter through a pipeline, and the diverter diverts low-temperature gas.

[0006] As a preferred technical solution of the utility model, the negative pressure of the air inside the heat storage body is transported through the main channel and the auxiliary air ducts to a heat exchanger through a pipeline, and the heat exchanger is connected to a controller.

[0007] As a preferred technical solution of the utility model, the heat storage body is made of integrally formed cast iron material.

[0008] As a preferred technical solution of the utility model, the induction heating coil is in a circular ring shape and is evenly sleeved on the heat storage body.

[0009] As a preferred technical solution of the utility model, the thermal insulation layer is composed of ceramic fiber and asbestos board.

[0010] As a preferred technical solution of the utility model, the structure of the thermal insulation layer is a double-layer thermal insulation structure. The side close to the heat storage body is ceramic fiber, and the side outside the heat storage body is asbestos board.

[0011] Compared with the prior art, the beneficial effects of the present utility model are as follows: In the solution of the present utility model: The heat storage body in this article adopts a cylindrical geometric design. In the central area of the heat storage body, 7 cylindrical ventilation ducts with the same size are designed. In the layout of these heat exchange air ducts, the main air duct is located in the center of the heat storage body, and several auxiliary air ducts with the same size as the main air duct are distributed around it according to the law of the circumference. Such a design aims to increase the heat exchange area in the device, enhance the overall heat transfer efficiency, and optimize the transfer and distribution of thermal energy by adding the auxiliary air ducts. Through this structure, a more uniform heat distribution can be achieved inside the heat storage body, thereby improving the heat release performance of the entire device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a heat storage unit composed of a heat storage body and an induction heating coil;

[0013] Figure 2 is the geometric structure of the heat storage body of the electro-thermal energy storage device;

[0014] Figure 3 is the overall structure of the induction heating solid electrothermal heating device.

[0015] Labels in the figures:

[0016] 1. Heat storage body, 2. Thermal insulation layer; 3. Induction heating coil; 4. Main channel; 5. Auxiliary air duct; 6. Device shell; 7. Gap; 8. Heat exchanger; 9. Variable frequency fan; 10. Controller; 11. Shunt; 12. Low-temperature air; 13. High-temperature air. SPECIFIC EMBODIMENTS

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model.

[0018] Therefore, the following detailed description of the embodiments of the present utility model is not intended to limit the scope of the present utility model claimed, but merely represents some embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope of protection of the present utility model. It should be noted that, without conflict, the embodiments in the present utility model and the features and technical solutions in the embodiments can be combined with each other. It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0019] Embodiment 1: Please refer toFigures 1 - 3 , an inductive electric heating solid heat storage device with a voltage rating of 400V, including a heat storage body 1, an induction heating coil 3, a thermal insulation layer 2, a device housing 6, a variable-frequency blower 9, a heat exchanger 8, a controller 10, and a shunt 11. Among them, the heat storage body 1 is provided with seven ventilation openings throughout the body. The main channel 4 is located at the central position, and the outer ones are... Through this structure, a more uniform heat distribution can be achieved inside the heat storage body, thereby improving the heat release performance of the entire device.

[0020] The geometric shape of the induction heating coil 3 is a ring, which is evenly sleeved on the heat storage body 1 at a certain distance. The parameters and winding forms of the heating coil are shown in the following table. The thermal insulation layer 2 is mainly composed of ceramic fiber and asbestos board. Ceramic fiber has good high-temperature resistance and heat insulation performance, which is suitable for the heat insulation requirements in high-temperature environments; asbestos board is a traditional heat insulation material with good heat insulation performance and high-temperature resistance,... The structure of the thermal insulation layer 2 is a double-layer thermal insulation structure. The side close to the heat storage body is ceramic fiber, and the outer side is asbestos board. The main function of the thermal insulation layer 2 is to insulate the heat stored in the heat storage body 1 so as not to cause a temperature drop when releasing heat.

[0021] The material of the heat storage body 1 is made of cast iron. Cast iron can be integrally cast, which can greatly improve the production speed and reduce the labor cost compared with magnesia brick heat storage. The raw materials can use recycled old steel to further reduce costs, which has great advantages compared with magnesia bricks. In addition, as an efficient heat storage material, cast iron has better thermal stability and heat capacity than traditional magnesia heat storage media. Based on the excellent characteristics of cast iron above, the material of the heat storage body 1 is selected as cast iron. When an alternating current is passed through the induction heating coil 3 to generate an alternating magnetic field, a magnetic flux change occurs inside the heat storage body 1 through the principle of electromagnetic induction, and then an induced current is generated to heat the heat storage body 1. When there is an external heat demand, the fluid generated by the variable-frequency blower 9 is divided under the action of the shunt 11 into... and the heat in the heat storage body 1 is transported to the heat exchanger 8 through the air negative pressure circulation inside the heat storage body 1 through the main channel 4, the auxiliary air duct 5 and between the heat storage bodies 1 from different directions, and under the action of the controller 10, the heat inside the heat storage body 1 is output to the outside in the form of hot water, hot oil, hot air, etc. through heat exchange methods such as gas-gas and gas-liquid in the heat exchanger 8.

[0022] Example 2: Please refer to Figures 1 - 3, An inductive electric heating solid heat storage device with a voltage rating of 400V. The overall structure of the heat storage unit consists of a heat storage body, an induction heating coil, and a heat insulation layer. When selecting the material for the heat storage body, if a material with a relatively high magnetic permeability is chosen, it will lead to a decrease in the penetration depth of the magnetic field, which will cause a greater resistance on the surface of the heat storage body, and then induce a stronger eddy current, which can effectively improve the heating efficiency. It should be noted that the magnetic permeability of ferromagnetic materials is significantly higher than that of non-ferromagnetic materials, and this influencing factor cannot be ignored when selecting the heat storage body material. Therefore, the heat storage body material of this utility model is selected as ferromagnetic cast iron, and the integrated molding is achieved through the casting process, which not only simplifies the production process but also can effectively reduce the manufacturing cost, which is of great significance for improving the economy and practicability of the entire device.

[0023] Combined with Figure 2 It can be seen that there are 7 ventilation ducts on the heat storage body. In the layout of these heat exchange ducts, the main duct is located in the center of the heat storage body, and several auxiliary ducts with the same size as the main duct are distributed around it according to the law of the circumference. Such a design aims to increase the heat exchange area in the device, enhance the overall heat transfer efficiency, and optimize the transfer and distribution of thermal energy by adding the auxiliary ducts. The geometric shape of the induction heating coil in the electro-thermal energy storage device is a ring, which is evenly sleeved on the heat storage body at a certain distance. It should be noted that when sleeving the induction heating coil, it is necessary to make the magnetic field as evenly distributed as possible in the heat storage body to avoid uneven heating of the heat storage body during heating, which will not only affect the heat storage capacity but also damage the service life of the heat storage body.

[0024] The electro-thermal energy conversion of an inductive electric heating solid heat storage device with a voltage rating of 400V mainly includes processes such as heat generation, heat storage, heat transfer, heat release, and heat control. According to the eddy current electromagnetic field theory, the electromagnetic field generated by the alternating current will induce the generation of induced current on the skin layer surface of the heat storage body. These induced currents generate heat on the surface of the heat storage body due to the thermoelectric effect. Subsequently, the heat gradually penetrates deeper into the heat storage body through the way of heat conduction and is stored under the action of the heat insulation layer.

[0025] The heat storage and heat release process of the device can be described as follows: when the coil is connected to a 400V AC voltage of a certain frequency, heat storage begins, and the heat storage stage ends after 21600s. At the end of the final heat storage stage, the maximum temperature of the heat storage body is 1020℃, and its overall average temperature is 900℃, which has good heat storage characteristics. In the heat release stage, the air velocity at the inlet boundary conditions of the electric thermal energy storage device is set to 1.5m / s, the air inflow temperature is 100℃, and the heat release time is 14400s. As the heat release time increases, the heat exchange air enters the electric thermal energy storage device to take away the heat of the heat storage body. At the end of the heat release stage, the heat exchange gas takes away the heat from the lower part of the heat storage body through convection heat transfer. Therefore, the temperature of the lower part of the heat storage body is the lowest, which is 120℃. The heat is mainly concentrated in the middle and upper part of the heat storage body, with a maximum temperature of 340℃ and a temperature difference of 220℃.

[0026] A 400V voltage-level induction electric heating solid heat storage device includes three main heat transfer methods: heat conduction, heat convection, and heat radiation. When the coil is connected to alternating current, a heating source is established on the surface of the heat storage body, causing the temperature at the heating source to rise. Then the heat begins to conduct to the inside of the heat storage body, causing the temperature to rise. This heat transfer method is called heat conduction. The heat conduction process is calculated using Fourier's law:

[0027]

[0028] Where: q1 is the heat flux in this direction, unit W / m2; λ is the thermal conductivity, unit W / (m·K); / is the temperature gradient in this direction, unit K / m. Convective heat transfer in induction heating electric thermal energy storage devices can be divided into natural convection and forced convection. In the heat storage stage, when the fan stops working, the hot air around the heat storage body will flow to the surrounding cold air for natural convection. In the heat release stage, the fan blows heat exchange gas into the electric thermal energy storage device, which is forced convection. The thermal convection process can be described by Newton's cooling formula, which is expressed as:

[0029] q2=β(T1-T2)#(9)

[0030] Where: q2 is the convective heat flux, unit W / m2; β is the surface convective heat transfer coefficient, unit W / (m2·K); T1 is the temperature of the solid surface, unit K; T2 is the temperature of the fluid in contact with the solid, unit K. Thermal radiation exists between all objects with temperature. Objects will always radiate to the surrounding in the form of electromagnetic waves, and at the same time, they will constantly absorb the radiation released by the surrounding substances. The effect caused by the combination of absorption and release is called radiation heat transfer. The calculation formula for radiation heat transfer is:

[0031]

[0032] Where: q3 is the radiant heat flux, with the unit of W / m2; ξ is the radiation coefficient, with the unit of W / (m2

[0033] ·K4), which is related to the properties and shape of the object, etc.; T1 and T2 are the temperatures of the radiation surfaces, with the unit of K.

[0034] Combined with Figure 3 , when there is an external heat demand, the variable-frequency fan is started to perform a negative-pressure circulation of the air inside the heat storage body, driving the energy stored in the heat storage body by the inductive heating solid electric heating device, and the heat inside the heat storage body is output to the outside in the forms of hot water, hot oil, hot air, etc. through various heat exchange methods via the external heat exchange equipment along each ventilation path.

[0035] Embodiment 3: An inductive electric heating solid heat storage device with a voltage grade of 400V. An inductive electric heating solid heat storage device with a voltage grade of 400V uses cast iron as the heat energy storage medium. The innovation lies in that the cast iron can be integrally cast, which can significantly improve the production speed and reduce the labor cost compared with the magnesite brick heat storage. The raw materials can utilize recycled old steel, further reducing the cost, and it has a great advantage compared with the magnesite brick. In addition, as an efficient heat storage material, cast iron has better thermal stability and heat capacity than the traditional magnesia heat storage medium. Therefore, selecting cast iron as the new heat storage material can improve the thermal efficiency and economy of the entire electric heat energy storage device.

[0036] The inductive heating technology used in the inductive electric heating solid heat storage device with a voltage grade of 400V proposed by the present utility model is based on the law of electromagnetic induction. When an electric current is passed through the coil, a magnetic field is established around the wire. When the magnetic flux in the conductor changes in the alternating magnetic field, an induced electromotive force will be generated in the conductor loop, and the specific polarity direction of the induced electromotive force can be determined by Lenz's law. In an alternating magnetic field environment, the conductor can be considered as composed of countless tiny closed loops connected in series, and these loops are arranged circumferentially along the conductor. At the same time, the inside of the conductor is not unobstructed, and there is a resistance that hinders the movement of the current. According to Joule's law, when the current passes through the resistance, heat will be generated in the heat storage body due to the loss of electrical energy. When an object is placed in a magnetic field, the magnetic flux Φ passing through its surface is:

[0037] Φ = B·S·cosθ #(1)

[0038] Where: S is the surface area of the object, with the unit of m2; θ is the angle between the magnetic induction intensity and the surface of the object. Under vacuum conditions, the magnetic induction intensity B at a certain point in the magnetic field is:

[0039]

[0040] Where: B is the magnetic induction intensity at this point, with the unit of T; μ0 is the vacuum permeability, μ0 = 4π×10 -7, with the unit of T·m / A; I is the magnitude of the current in the wire, with the unit of A; r is the distance between this point and the wire, with the unit of m. The induced electromotive force e generated by the alternating magnetic field in the conductor loop is:

[0041]

[0042] Suppose the number of turns of the energized wire coil is N, and the input current waveform is a sine wave. Substituting Equation (1) into Equation (2), it can be obtained that the magnetic flux Φ also changes according to the same waveform as the current, that is:

[0043] Φ = N·Φ M sinωt#(4)

[0044] Among them: ΦM is the amplitude of the magnetic flux Φ, with the unit of Wb; ω is the angular frequency, with the unit of rad / s. Substituting Equation (4) into Equation (3), the induced electromotive force e in the conductor can be obtained as:

[0045]

[0046] Its effective value is:

[0047] E = 4.44N·f·Φ M #(6)

[0048] Under the action of eddy currents, heat is generated in the conductor, that is:

[0049]

[0050] Among them: Iw is the magnitude of the eddy current, with the unit of A; Rw is the equivalent resistance of the conductor, with the unit of Ω; t is the energization time, with the unit of s. The heat storage function of an induction electric heating solid heat storage device with a voltage level of 400V is exactly realized through the above-mentioned induction heating principle and mathematical model

[0051] The heat exchange mechanism of an induction electric heating solid heat storage device with a voltage level of 400V is similar to that of a traditional resistive electric heating energy storage device. A complete working cycle of the entire induction heating electric heating energy storage device is divided into a heat storage stage and a heat release stage. In terms of heat transfer, the main heat transfer method in the heat storage stage is solid heat transfer, while the main heat transfer method in the heat release stage is fluid-solid coupling heat transfer.

[0052] In the heat storage stage, using the electric power during low-load periods, the electromagnetic energy is converted into heat energy through the induction heating coil and stored in the heat storage body through heat conduction; in the heat release stage, the relatively low-temperature heat exchange gas flows into the interior of the heat storage device from the inlet of the heat exchange channel under the action of the circulating fan and conducts contact fluid-solid coupling convective heat exchange with the surface of the heat storage body, thereby absorbing the heat stored in the heat storage body and taking it away to raise the temperature of the heat exchange gas. Subsequently, these heated heat exchange gases transfer the heat energy to the heat users through the heat exchanger

[0053] The above are only some embodiments of the present utility model. For those of ordinary skill in the art, without departing from the creative concept of the present utility model, several modifications and improvements can still be made, and these all fall within the protection scope of the present utility model.

[0054] The above embodiments are only used to illustrate the present utility model and not to limit the technical solutions described in the present utility model. Although this specification has described the present utility model in detail with reference to the above respective embodiments, the present utility model is not limited to the above specific implementation manners. Therefore, any modification or equivalent replacement made to the present utility model; and all technical solutions and their improvements that do not depart from the spirit and scope of the utility model are covered by the scope of the claims of the present utility model.

Claims

1. An induction electric heating solid heat storage device with a voltage level of 400V, comprising a heat storage body (1) and a heat insulation layer (2), characterized in that: The outer surface of the heat storage body (1) is covered with an induction heating coil (3), and the heat storage body (1) has seven ventilation holes throughout the body, the ventilation hole located in the center is the main channel (4), and the ventilation holes located on the periphery are auxiliary air ducts (5).

2. According to the 400V voltage level induction electric heating solid heat storage device of claim 1, it is characterized in that: The heat storage body (1) is connected to a variable frequency fan (9), a gap (7) is provided between the induction heating coils (3), and a device casing (6) is provided on the outer surface of the heat storage body (1).

3. According to the 400V voltage level induction electric heating solid heat storage device of claim 2, it is characterized in that: The variable frequency fan (9) is connected to a diverter (11) via a pipeline, and the diverter (11) diverts low-temperature gas.

4. The 400V voltage-level induction electric heating solid heat storage device according to claim 3 is characterized in that: The negative air pressure inside the heat storage body (1) is transported through the main channel (4), the auxiliary air duct (5) and the heat exchanger (8), and the heat exchanger (8) is connected to the controller (10).

5. The 400V voltage-level induction electric heating solid heat storage device according to claim 4 is characterized in that: The heat storage body (1) is made of an integrally formed cast iron material.

6. The 400V voltage-level induction electric heating solid heat storage device according to claim 5 is characterized in that: The induction heating coil (3) is in the shape of a circular ring and is evenly sleeved on the heat storage body (1).

7. The 400V voltage-level induction electric heating solid heat storage device according to claim 6 is characterized in that: The thermal insulation layer (2) is composed of ceramic fibers and asbestos boards.

8. The 400V voltage-level induction electric heating solid heat storage device according to claim 7, characterized in that: The structure of the heat-insulating layer (2) is a double-layer heat-insulating structure, with ceramic fibers on the side close to the heat-storing body (1) and asbestos boards on the outside close to the heat-storing body (1).

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