Thermochemical heat storage device and heat storage method based on electromagnetic heating

Abstract

The invention relates to a thermochemical heat storage device based on electromagnetic heating and a heat storage method. The invention provides a thermochemical heat storage device based on electromagnetic heating, and the device comprises an electromagnetic heater which comprises a power generation module and an induction coil electrically connected with the power generation module; the composite heat storage body comprises a heating carrier and a thermochemical heat storage material, the heating carrier is a three-dimensional porous conductive material or a ferromagnetic material, and the heating carrier is filled with the thermochemical heat storage material; and the induction coil surrounds the composite heat storage body. The heating carrier serves as a carrier of the eddy current heating body and the thermochemical heat storage material and also serves as a gas diffusion channel, electric energy is converted into heat energy, the thermochemical heat storage material is heated, the advantages of high electromagnetic induction heating efficiency, low energy consumption and high speed are brought into full play, and the heat storage efficiency is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, specifically relating to a thermochemical thermal storage device and method based on electromagnetic heating. Background Technology

[0003] Thermal energy storage is generally classified into sensible thermal energy storage, phase change thermal energy storage, and thermochemical thermal energy storage. Most existing thermochemical thermal energy storage methods rely on wall-based heat conduction, but the poor thermal conductivity of most inorganic oxides leads to excessively long heating times. While fluidized beds allow for more thorough contact between the fluid and solid particles, resulting in better heat transfer, the poor thermal conductivity between inorganic oxide particles remains a problem.

[0004] Electromagnetic induction heating technology is a highly efficient heating method that converts electrical energy into heat energy using the principle of electromagnetic induction. Induction heating is a non-contact heating technology that heats the object being heated without physical contact. Compared to traditional heating methods, it offers numerous advantages, including high heating efficiency, low energy consumption, small size, non-contact operation, the ability to provide localized heating, and no pollution. Traditional resistance heating methods, on the other hand, consume a large amount of energy from the crucible and have low thermal efficiency.

[0005] In summary, the problems of slow energy storage speed and poor thermal conductivity of traditional non-magnetic thermal storage media urgently need to be solved. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of slow energy storage speed and poor thermal conductivity of traditional non-magnetic thermal storage media.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A thermochemical thermal storage device based on electromagnetic heating, comprising:

[0009] An electromagnetic heater includes a power generating module and an induction coil electrically connected to the power generating module;

[0010] A composite thermal storage body includes a heat carrier and a thermochemical thermal storage material, wherein the heat carrier is a three-dimensional porous conductive material or a ferromagnetic material, and the thermochemical thermal storage material is filled in the heat carrier;

[0011] The induction coil surrounds the composite thermal storage body.

[0012] The power generation module includes a frequency conversion power module and a power adjustment module, which are used to generate different electromagnetic heating frequencies.

[0013] Preferably, the heating carrier is metal foam.

[0014] Preferably, the metal foam is one of iron-based metal foam, nickel-based metal foam, and copper-based metal foam.

[0015] Preferably, the porosity of the metal foam is 20 ppi to 30 ppi.

[0016] Preferably, the thermochemical heat storage material is mixed with water and then impregnated onto the metal foam to form a composite heat storage body.

[0017] Preferably, the composite volume accounts for 50% to 75% of the volume of the induction coil.

[0018] Preferably, the heating carrier is a graphite crucible, and one end of the graphite crucible is provided with multiple axial circular blind holes or honeycomb blind holes, and the thermochemical heat storage material is filled in the graphite crucible.

[0019] In traditional crucibles, due to the skin effect, heat is concentrated on the surface during electromagnetic heating, resulting in uneven heating of the internal material. This application improves heating efficiency by using a zoned heating design and processing an array of blind holes on the top of the crucible to ensure uniform heating of the internal material.

[0020] Preferably, the volume of the graphite crucible accounts for 50% to 60% of the volume of the induction coil.

[0021] Preferably, the circular blind hole includes a central blind hole and four surrounding radii, the radius of the central blind hole is 9-11 mm, the radius of the surrounding blind holes is 7-9 mm, and the hole depth is 60%-70% of the axial length of the graphite crucible.

[0022] Preferably, the inscribed circle diameter of the honeycomb-shaped blind hole is 5-7 mm, and the hole depth is 60%-70% of the axial length of the graphite crucible.

[0023] Preferably, the thermochemical heat storage material is one of CaO / Ca(OH)2, MgO / Mg(OH)2, CaO / CaCO3, and MgO / MgCO3.

[0024] Preferably, it further includes a cooling module, which is connected to the power generating module.

[0025] Preferably, it further includes a thermocouple connected to the composite thermal storage body.

[0026] The present invention also provides a thermochemical heat storage method based on electromagnetic heating, wherein the thermochemical heat storage device based on electromagnetic heating is used for heat storage, comprising:

[0027] The induction coil is powered by a power generation module.

[0028] The heating carrier is heated by an induction coil;

[0029] The thermochemical heat storage material is heated by the heating carrier;

[0030] The thermochemical heat storage material undergoes a reversible chemical reaction to store thermal energy.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention proposes a thermochemical thermal storage device based on electromagnetic heating, comprising: an electromagnetic heater, including a power generating module and an induction coil electrically connected to the power generating module; a composite thermal storage body, including a heating carrier and a thermochemical thermal storage material, wherein the heating carrier is a three-dimensional porous conductive material or a ferromagnetic material, and the thermochemical thermal storage material is filled in the heating carrier; and the induction coil surrounds the composite thermal storage body. The heating carrier serves as a carrier for both the eddy current heating element and the thermochemical thermal storage material, and also as a gas diffusion channel, converting electrical energy into heat energy to heat the thermochemical thermal storage material. This fully utilizes the advantages of electromagnetic induction heating—high efficiency, low energy consumption, and fast speed—significantly improving thermal storage efficiency.

[0033] This invention proposes a thermochemical energy storage method based on electromagnetic heating. It innovatively proposes to perform thermochemical energy storage in the form of electromagnetic heating, using a graphite crucible and metal foam as electromagnetic heating media to convert electrical energy into heat energy to heat the energy storage material. The heating structure is improved by using a metal foam composite and a graphite crucible with a blind hole structure, which solves the problems of slow energy storage speed and poor thermal conductivity of traditional non-magnetic energy storage media, resulting in better energy storage effect. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a thermochemical thermal storage device based on electromagnetic heating according to an embodiment of the present invention;

[0035] Figure 2 This is a physical diagram of a thermochemical thermal storage device based on electromagnetic heating, according to an embodiment of the present invention.

[0036] Figure 3 This is a graph showing the test results of Test Example 1 of the present invention;

[0037] Figure 4 This is a schematic diagram of the structure of the circular blind-hole graphite crucible of Embodiment 3 of the present invention;

[0038] Figure 5 This is a physical image of the circular blind-hole graphite crucible of Embodiment 3 of the present invention;

[0039] Figure 6 This is a photograph of the circular blind-hole graphite crucible of Embodiment 3 of the present invention after being filled with heat storage material;

[0040] Figure 7 This is a graph showing the test results of Test Example 2 of the present invention;

[0041] Figure 8This is a cross-sectional view of the honeycomb-shaped blind-hole graphite crucible of Embodiment 4 of the present invention;

[0042] Figure 9 This is a graph showing the test results of Test Example 3 of the present invention;

[0043] The components include: 1. thermocouple; 2. composite heat storage body; 3. induction coil; 4. power generation module; and 5. cooling module. Detailed Implementation

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other instances that are improved or modified by those skilled in the art are within the scope of protection of the present invention. It should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the methods used in the embodiments are conventional methods.

[0045] Example 1

[0046] This embodiment provides a thermochemical heat storage device based on electromagnetic heating, comprising: an electromagnetic heater, including a power generating module and an induction coil electrically connected to the power generating module; a composite heat storage body, including a heating carrier and a thermochemical heat storage material, wherein the heating carrier is a three-dimensional porous conductive material or a ferromagnetic material, and the thermochemical heat storage material is filled in the heating carrier; and the induction coil surrounds the composite heat storage body.

[0047] In this embodiment, the composite thermal storage body includes a heat-generating carrier and a thermochemical thermal storage material. The heat-generating carrier is a 20 ppi iron-based metal foam, and the thermochemical thermal storage material is CaO / Ca(OH)2. The composite thermal storage body is prepared by the following method: calcium hydroxide powder is added to water and stirred to dissolve a portion, which is then impregnated onto the metal foam, leaving 30% of the pores to facilitate gas diffusion. The mixture is then dried. The 30% pore filling is designed to facilitate gas diffusion.

[0048] The volume of the composite thermal storage body accounts for 65% of the volume of the induction coil.

[0049] The thermal storage device in this embodiment further includes a thermocouple and a cooling module. The cooling module is connected to the power generation module, and the thermocouple is connected to the composite thermal storage body. Figure 1 The diagram shown is a structural schematic of the thermal storage device in this embodiment, including a thermocouple 1, a composite thermal storage body 2, an induction coil 3, a power generation module 4, and a cooling module 5. In this embodiment, the power generation module 4 is a ZVS electromagnetic induction heating device, and the cooling module 5 is a cooling water device. Figure 2The image shown is a physical diagram of the thermal storage device in this embodiment.

[0050] The thermal storage device in this embodiment performs thermochemical energy storage in the form of electromagnetic heating, using metal foam as the electromagnetic heating medium. The metal foam serves as a carrier for the eddy current heating element and the thermochemical thermal storage material, and at the same time as a gas diffusion channel to convert electrical energy into thermal energy to heat the thermal storage material. This improved heating structure solves the problems of slow energy storage speed and poor thermal conductivity of traditional non-magnetic thermal storage media, resulting in better thermal storage effect.

[0051] Example 2

[0052] The difference between this embodiment and Embodiment 1 is that the heating carrier is a 30ppi iron-based metal foam.

[0053] Test Example 1

[0054] The thermal storage devices of Examples 1 and 2 were tested by heating the filled metal foam-calcium hydroxide composite with an electromagnetic heating frequency of 700W and 50Hz for 20 minutes.

[0055] Figure 3 The display shows the temperature changes of the heat storage material during 20 minutes of heating. It can be seen that the temperature of the composite heat storage body rises to around 500℃ after 7 minutes, and a temperature plateau phenomenon occurs. Experiments showed that the unloaded metal foam did not exhibit a temperature plateau phenomenon. Therefore, the temperature plateau phenomenon in the composite heat storage body is due to the endothermic decomposition of calcium hydroxide, not a limitation of the foam itself. The decomposed water is lost as steam, enhancing air convection heat dissipation and further stabilizing the temperature plateau. When the decomposition reaction weakens, the absorption term decreases, and the input power exceeds the sum of the endothermic heat and heat loss, resulting in a partial temperature rise. The metal foam conversion rate reaches approximately 30%, requiring about 20 minutes of heating time.

[0056] Example 3

[0057] The difference between this embodiment and Embodiment 1 is that the heating carrier is a graphite crucible with multiple axial circular blind holes at one end. Figure 4 This is a schematic diagram of a circular blind-hole graphite crucible. Figure 5 This is a photograph of a circular blind-hole graphite crucible. Figure 6 This is a photograph of a circular blind-hole graphite crucible filled with heat storage material. The volume of the graphite crucible accounts for 50% of the volume of the induction coil. The circular blind hole includes a central blind hole and four surrounding radii. The radius of the central blind hole is 10 mm, the radius of the surrounding blind holes is 8 mm, and the depth of the hole is 65% of the axial length of the graphite crucible.

[0058] The thermochemical heat storage material is CaO / Ca(OH)2. The composite heat storage body is prepared by filling CaO / Ca(OH)2 into the circular blind holes of a graphite crucible.

[0059] The thermal storage device in this embodiment uses electromagnetic heating for thermochemical energy storage. It uses a graphite crucible with an optimized blind hole structure as the electromagnetic heating medium to convert electrical energy into thermal energy and heat the thermal storage material. This improved heating structure solves the problems of slow energy storage speed and poor thermal conductivity of traditional non-magnetic thermal storage media, resulting in better thermal storage effect.

[0060] Test Example 2

[0061] The thermal storage device of Example 3 was tested by heating the filled thermal storage composite with electromagnetic heating frequencies of 960W and 700W for 20 minutes.

[0062] Figure 7 The temperature changes of the thermal storage material under heating powers of 960W and 700W are shown. The temperature trends are almost identical at both 960W and 700W. At 700W, the sample conversion rate is 71.26% and the thermal efficiency is 59.2%; at 960W, the sample conversion rate is 89% and the thermal efficiency is 81.9%, requiring 7 minutes.

[0063] For circular blind holes, within a certain range, power increase can quickly cross the low temperature range, reducing heat dissipation time. The larger circular blind holes have less impact on graphite, higher eddy current utilization, and the larger volume of the circular blind holes results in stronger thermal inertia, buffering temperature fluctuations and making it less likely for the generated steam to overflow.

[0064] Example 4

[0065] The difference between this embodiment and Embodiment 1 is that the heating carrier is a graphite crucible with multiple axial honeycomb-shaped blind holes at one end, and the volume of the graphite crucible accounts for 60% of the volume of the induction coil. The inscribed circle diameter of the honeycomb-shaped blind holes is 6 mm, and the hole depth is 65% of the axial length of the graphite crucible. Figure 8 This is a cross-sectional view of a honeycomb-shaped blind-hole graphite crucible.

[0066] The thermochemical heat storage material is CaO / Ca(OH)2. The composite heat storage body is prepared by filling CaO / Ca(OH)2 into the honeycomb-shaped blind holes of a graphite crucible.

[0067] Test Example 3

[0068] A thermal storage test was conducted on the thermal storage device of Example 4. The filled thermal storage composite was heated by an electromagnetic heating frequency of 560W for 20 minutes. Figure 9The temperature change of the heat storage material under a heating power of 560W is shown. It can be seen that after 6 minutes of heating, residual heat continues to heat the material. Heating the honeycomb graphite crucible at 560W power achieves a conversion rate of 89% and a thermal efficiency of 63.859%, requiring a heating time of 6 minutes. The thick bottom of the crucible optimizes heat distribution and electromagnetic coupling, but at high conversion rates, the reaction endothermics approach saturation, resulting in some heat waste and lower thermal efficiency.

[0069] Comparative Example 1

[0070] According to the article on the preparation and thermal storage performance of CaO / Ca(OH)2 core-shell structured particles published by Mo Yachao et al. in the journal *Energy Storage Science and Technology*, a resistance heater was used to heat the thermal storage material, CaO / Ca(OH)2, which was directly filled into a container without a porous carrier or blind-pore structure. The thermal storage material mass was 150 mg, and the conversion rate was low within 30 minutes of heating. The electromagnetic heating device of this invention is significantly superior to the traditional wall-conducting heating method in terms of heating speed, conversion rate, and thermal efficiency.

[0071] Comparative Example 2

[0072] The graphite blind-hole crucible, the sensible heat of the crucible, the sensible heat and latent heat of the heat storage material (CaO / Ca(OH)2), and the total heat flow of the composite heat storage body after heat capacity calculation are 147.1 kJ. Using a traditional wall-mounted heat conduction device as a comparison, the heat storage material is heated for 30 minutes with a conversion rate of 25%. The calculated mass of heat storage material required for the same heat flow is 0.198 g. In contrast, the graphite blind-hole crucible in this invention requires approximately 0.058 kg of material, and only 0.0587 kg of Ca(OH)2, a 69% reduction compared to the traditional wall-mounted heat conduction device (0.189 kg). Furthermore, the heating time is less than 10 minutes, only one-third that of the traditional wall-mounted heat conduction device.

[0073] In summary, the entire heating device and its heating effect are affected by the heating structure, heating time, and heating quality. This invention heats chemical heat storage materials by electromagnetic heating and improves the heat storage effect of the heat storage materials by using metal foam, graphite crucibles, etc. In Example 3, the conversion rate and thermal efficiency of calcium hydroxide are good when heated at 960W for 5 minutes, which fully utilizes the advantages of electromagnetic induction heating, such as high efficiency, low energy consumption, and fast speed.

[0074] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A thermochemical thermal storage device based on electromagnetic heating, characterized in that, include: An electromagnetic heater includes a power generating module and an induction coil electrically connected to the power generating module; A composite thermal storage body includes a heat carrier and a thermochemical thermal storage material, wherein the heat carrier is a three-dimensional porous conductive material or a ferromagnetic material, and the thermochemical thermal storage material is filled in the heat carrier; The induction coil surrounds the composite thermal storage body.

2. The thermochemical thermal storage device based on electromagnetic heating according to claim 1, characterized in that, The heating carrier is metal foam.

3. The thermochemical thermal storage device based on electromagnetic heating according to claim 2, characterized in that, The metal foam is one of iron-based metal foam, nickel-based metal foam, and copper-based metal foam.

4. The thermochemical thermal storage device based on electromagnetic heating according to claim 2, characterized in that, The porosity of the metal foam is 20ppi to 30ppi.

5. The thermochemical thermal storage device based on electromagnetic heating according to claim 2, characterized in that, The thermochemical thermal storage material is mixed with water and then impregnated onto the metal foam to form a composite thermal storage body.

6. The thermochemical thermal storage device based on electromagnetic heating according to claim 2, characterized in that, The volume of the composite heat storage body accounts for 50% to 75% of the volume of the induction coil.

7. The thermochemical thermal storage device based on electromagnetic heating according to claim 1, characterized in that, The heating carrier is a graphite crucible, and one end of the graphite crucible is provided with multiple axial circular blind holes or honeycomb blind holes, and the thermochemical heat storage material is filled in the graphite crucible.

8. The thermochemical thermal storage device based on electromagnetic heating according to claim 7, characterized in that, The volume of the graphite crucible accounts for 50% to 60% of the volume of the induction coil.

9. The thermochemical thermal storage device based on electromagnetic heating according to claim 7, characterized in that, The circular blind hole includes a central blind hole and four surrounding radii. The radius of the central blind hole is 9-11 mm, the radius of the surrounding blind holes is 7-9 mm, and the hole depth is 60%-70% of the axial length of the graphite crucible.

10. The thermochemical thermal storage device based on electromagnetic heating according to claim 7, characterized in that, The inscribed circle diameter of the honeycomb-shaped blind hole is 5-7 mm, and the hole depth is 60%-70% of the axial length of the graphite crucible.

11. The thermochemical thermal storage device based on electromagnetic heating according to claim 1, characterized in that, The thermochemical heat storage material is one of CaO / Ca(OH)2, MgO / Mg(OH)2, CaO / CaCO3, and MgO / MgCO3.

12. The thermochemical thermal storage device based on electromagnetic heating according to claim 1, characterized in that, Also includes: A cooling module, which is connected to the power generation module.

13. The thermochemical thermal storage device based on electromagnetic heating according to claim 1, characterized in that, Also includes: A thermocouple, which is connected to the composite thermal storage body.

14. A thermochemical heat storage method based on electromagnetic heating, characterized in that, The thermal storage device based on electromagnetic heating according to any one of claims 1 to 13 is used for thermal storage, comprising: The induction coil is powered by a power generation module. The heating carrier is heated by an induction coil; The thermochemical heat storage material is heated by the heating carrier; The thermochemical heat storage material undergoes a reversible chemical reaction to store thermal energy.

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