Solid heat storage device

Abstract

The utility model discloses a solid heat storage device, which belongs to the technical field of heat storage, and comprises a heat storage body, a heating device and a heat taking medium, the heat storage body is provided with a heat storage channel and a heat taking channel which are not communicated with each other, and the heat storage channel and the heat taking channel are arranged in a mutually crossed manner; the heating device is arranged in the heat storage channel; and the heat removal medium is filled in the heat removal channel. The heat storage channel and the heat taking channel which are crossed but not communicated with each other are arranged on the heat storage body, the heating device is used for transferring heat to the heat storage body for storage, the heat taking medium is used for leading out the heat of the heat storage body, and the heat storage efficiency and the heat taking efficiency can be improved.

Description

Technical Field

[0001] This utility model relates to the field of thermal storage technology, and in particular to a solid thermal storage device. Background Technology

[0002] In the field of thermal energy storage and release technology, traditional solid thermal energy storage devices have long held a dominant position. Among them, MgO bricks, as a classic thermal energy storage material, are widely used due to their good chemical stability and certain heat capacity. These devices typically rely on resistance wires as a heat source, converting electrical energy into heat energy through thermal conduction and radiation, and storing it in the MgO bricks. When heat needs to be released, the convective heat transfer effect of hot air is utilized to transfer the heat energy stored in the MgO bricks to the external environment or a specific working medium.

[0003] However, although traditional solid-state thermal energy storage devices meet the basic requirements for thermal energy storage and conversion to a certain extent, their inherent technical limitations are becoming increasingly prominent, becoming a bottleneck restricting further development in this field. Specifically, the following problems exist: the thermal conductivity of traditional thermal energy storage materials such as MgO bricks is relatively low. This means that during the thermal storage process, the heat generated by the resistance wire is difficult to transfer quickly and evenly throughout the entire storage body. Similarly, during the heat release process, the heat stored in the MgO bricks is difficult to release efficiently to the heat extraction medium. This low thermal conductivity not only prolongs the thermal storage and release time period and reduces overall efficiency, but also increases energy consumption.

[0004] In view of the above problems, how to improve the structure to enhance the heat transfer efficiency of solid thermal storage devices is a technical problem that needs to be solved. Utility Model Content

[0005] The purpose of this invention is to provide a solid thermal storage device to solve the problems existing in the prior art. By setting intersecting but non-interconnected thermal storage channels and thermal extraction channels on the thermal storage body, heat is transferred to the thermal storage body for storage using a heating device, and the heat is extracted from the thermal storage body using a thermal extraction medium, thereby improving the efficiency of thermal storage and extraction.

[0006] To achieve the above objectives, this utility model provides the following solution:

[0007] This utility model provides a solid thermal storage device, including a thermal storage body, a heating device, and a heat extraction medium. The thermal storage body is provided with non-communicating thermal storage channels and heat extraction channels, which are arranged intersectingly. The heating device is disposed inside the thermal storage channels, and the heat extraction medium fills the inside of the heat extraction channels.

[0008] In one embodiment, the heat storage channel is located in the middle of the heat storage body, and the heat extraction channels are arranged parallel to each other on both sides of the heat storage channel.

[0009] In one embodiment, the heat storage body is a cuboid structure, the heat extraction channel penetrates a set of heat extraction surfaces in the cuboid structure, the heat storage channel penetrates a set of heat storage surfaces in the cuboid structure, and the heat extraction channel is perpendicular to the heat storage channel.

[0010] In one embodiment, the top surface of the cuboid structure is provided with a positioning groove, and the bottom surface of the cuboid structure is provided with a positioning protrusion. The positioning groove and the positioning protrusion of different cuboid structures can be connected in a cooperative manner.

[0011] In one embodiment, both the positioning groove and the positioning protrusion are arranged in a cross shape.

[0012] In one embodiment, the distances between the heat extraction channels, between the heat extraction channels and the heat storage channels, and between the heat extraction channels and the walls of the heat storage body are equal.

[0013] In one embodiment, the heat extraction channel is disposed in the middle of the heat storage body, and the heat storage channel is disposed on both sides of the heat extraction channel.

[0014] In one embodiment, the heat extraction medium is carbon dioxide gas.

[0015] In one embodiment, the heating device is an electromagnetic heater.

[0016] In one embodiment, the heat storage body is made of cast iron.

[0017] The present invention achieves the following technical advantages over the prior art:

[0018] This invention improves the efficiency of heat storage and extraction by setting up intersecting but non-interconnected heat storage channels and heat extraction channels on the heat storage body. Heat is transferred to the heat storage body for storage using a heating device, and the heat is extracted from the heat storage body using a heat extraction medium. The heat storage channels and heat extraction channels do not interfere with each other. The heat storage channels facilitate the storage of heat in the heat storage body, and the heat extraction channels facilitate the extraction of heat from the heat storage body.

[0019] Other technical solutions included in this utility model can also achieve the following technical effects:

[0020] Materials such as MgO bricks have poor thermal stability and are prone to changes in physical or chemical properties when working in high-temperature environments for a long time, such as thermal expansion, cracking, or chemical decomposition. This not only shortens the service life of the heat storage material but may also cause safety hazards, such as material detachment and equipment leakage, which seriously restricts the application range and reliability of solid heat storage devices. This utility model uses cast iron with high thermal conductivity as the main material of the heat storage body, which can ensure the thermal stability of the material and the safety of the device. The heat extraction medium is carbon dioxide gas, which has the advantages of low cost, stable chemical properties, high thermal stability, and large enthalpy difference. The combination of cast iron and carbon dioxide gas can realize heat transfer with a small temperature difference between the heat storage body and the heat extraction medium, resulting in fast heat storage and release rates and high efficiency. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the solid thermal storage device in the embodiments of this utility model;

[0023] Figure 2 for Figure 1 Another angle diagram;

[0024] Figure 3 This is a schematic diagram of the heat extraction cross section in an embodiment of this utility model;

[0025] Among them, 1. heat storage body; 2. heat storage channel; 3. heat extraction channel; 4. positioning groove; 5. positioning protrusion. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] The purpose of this invention is to provide a solid thermal storage device to solve the problems existing in the prior art. By setting up intersecting but non-interconnected thermal storage channels and thermal extraction channels on the thermal storage body, heat is transferred to the thermal storage body for storage using a heating device, and the heat is extracted from the thermal storage body using a thermal extraction medium, thereby improving the efficiency of thermal storage and extraction.

[0028] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figures 1-3 As shown, this utility model provides a solid thermal storage device, including a thermal storage body 1, a heating device, and a heat extraction medium. The thermal storage body 1 is generally a block structure, with at least one block, or multiple blocks can be combined to form a solid thermal storage device. The thermal storage body 1 can adopt a rectangular, spherical, or pyramidal structure, or other irregular shapes. Simultaneously, the thermal storage material of the thermal storage body 1 possesses advantages such as high temperature resistance, corrosion resistance, and oxidation resistance. The device is suitable for long-term start-stop operations and frequent heat storage and release, and has a long service life while ensuring safe and stable operation. The thermal storage body 1 is provided with non-interconnected thermal storage channels 2 and heat extraction channels 3. The thermal storage channels 2 and 3 can be pipes passing through the thermal storage body 1, or they can be directly formed by openings in the thermal storage body 1. The cross-sections of the thermal storage channels 2 and 3 can be circular, rectangular, or triangular, with a circular shape being preferred. A circular shape allows for more uniform heat exchange between the thermal storage channel 2 or heat extraction channel 3 and the thermal storage body 1. Generally, the number of heat extraction channels 3 is greater than the number of heat storage channels 2, facilitating efficient heat extraction. The heat storage channels 2 and heat extraction channels 3 are arranged intersectingly, at right angles or acute angles, and are not parallel. This arrangement allows the heat storage channels 2 to effectively store heat in the heat storage body 1, and when the heat extraction channels 3 extract heat, they can extract heat from various parts of the heat storage body 1, further improving the efficiency of heat storage and extraction. A heating device is installed inside the heat storage channels 2 to transfer heat to the heat storage body 1 within the channels 2. A heat extraction medium fills the inside of the heat extraction channels 3, used to exchange heat with the heat storage body 1 within the channels 3 to remove heat from the heat storage body 1. The heat extraction medium can be a gas or a liquid.

[0030] This invention utilizes intersecting but non-interconnected heat storage channels 2 and heat extraction channels 3 on a heat storage body 1. A heating device transfers heat to the heat storage body 1 for storage, while a heat extraction medium removes the heat from the heat storage body 1. The heat storage channels 2 and heat extraction channels 3 do not interfere with each other. The heat storage channels 2 facilitate heat storage in the heat storage body 1, while the heat extraction channels 3 facilitate heat extraction from the heat storage body 1, thereby improving the efficiency of heat storage and extraction. This solid heat storage device can be applied in heating, industrial steam, and power plant peak shaving and frequency regulation.

[0031] In one embodiment, the heat storage channel 2 is located in the middle of the heat storage body 1. When heated by a heating device, it can better store heat in all parts of the heat storage body 1, avoiding uneven temperature that would reduce the heat storage capacity of the heat storage body 1. The heat extraction channels 3 are arranged parallel to each other on both sides of the heat storage channel 2, so as to better utilize the heat extraction channels 3 to extract the heat stored around the heat storage channel 2.

[0032] In one embodiment, the heat storage body 1 has a cuboid structure with six faces. One set of opposite faces serves as the heat extraction face, another set serves as the heat storage face, and a third set serves as the top or bottom face. A heat extraction channel 3 penetrates one set of heat extraction faces in the cuboid structure, and a heat storage channel 2 penetrates one set of heat storage faces. The heat extraction and heat storage faces are perpendicular to each other. This effectively avoids interference between the heat extraction pipes and heat storage lines when installing heat extraction pipes into the heat extraction channel 3 or heat storage lines into the heat storage channel 2, improving the ease of use of the solid heat storage device. The heat extraction channel 3 is perpendicular to the heat storage channel 2. Based on the cuboid structure of the heat storage body 1, the heat storage channel 2 and the heat extraction channel 3 can extend along the edges of the cuboid structure, and a greater number of heat extraction channels 3 can be arranged, further improving heat storage and extraction efficiency.

[0033] In one embodiment, a positioning groove 4 is provided on the top surface of the cuboid structure, and a positioning protrusion 5 is provided on the bottom surface of the cuboid structure. It should be noted that the top surface and bottom surface mentioned here refer only to the positioning groove 4. Figure 1 The distinction is made based on the shown states; that is, the top surface can be placed at the bottom, and the bottom surface can be placed at the top (e.g., ...). Figure 2 As shown in the diagram, the top and bottom surfaces should not be used as limitations on the specific installation location and method of the cuboid structure. The positioning grooves 4 and positioning protrusions 5 of different cuboid structures can be connected in conjunction, that is, multiple heat storage bodies 1 can be arranged together, and positioning can be achieved by using the positioning grooves 4 and positioning protrusions 5, thereby improving the convenience of installation and the accuracy of the installation position.

[0034] In one embodiment, both the positioning groove 4 and the positioning protrusion 5 are arranged in a cross shape, which can position the heat storage body 1 in both the lateral and longitudinal directions, ensuring that after positioning and connection, the heat-extracting surface of the heat storage body 1 is flush with the heat-extracting surface, and the heat-storing surface is flush with the heat-storing surface. In addition, the cross-section of both the positioning groove 4 and the positioning protrusion 5 can be set as triangular, and the triangular positioning protrusion 5 cooperates with the triangular positioning groove 4, which facilitates the positioning protrusion 5 to enter the positioning groove 4.

[0035] In one embodiment, the spacing between the heat extraction channels 3, between the heat extraction channel 3 and the heat storage channel 2, and between the heat extraction channel 3 and the wall of the heat storage body 1 are equal, which facilitates heat transfer and also makes the design easier.

[0036] In one embodiment, the heat extraction channel 3 is located in the middle of the heat storage body 1, and the heat storage channel 2 is located on both sides of the heat extraction channel 3. During heat storage, heat is transferred to the middle of the heat storage body 1 through the heat storage channel 2. During heat extraction, the heat in the middle of the heat storage body 1 is extracted through the heat extraction channel 3. This method can also ensure the smooth operation of heat storage and heat extraction. However, compared with the method of setting the heat storage channel 2 in the middle, more heat storage channels 2 need to be set, which may occupy the actual heat storage volume of the heat storage body 1 and reduce the overall heat storage capacity.

[0037] In one embodiment, carbon dioxide gas is used as the heat extraction medium, and cast iron is used as the heat storage body 1. The heat storage body 1, made of cast iron, possesses excellent heat storage and heat transfer performance, with a thermal conductivity above 40 W / (m·K) and a specific heat capacity above 0.5 kJ / (kg·K). By using cast iron with high thermal conductivity as the main material of the heat storage body 1, the thermal stability of the material and the safety of the device can be ensured. Carbon dioxide gas is used as the heat extraction medium, and its flow within the heat extraction channel 3 carries away the heat from the heat storage body 1. Carbon dioxide gas has advantages such as low cost, stable chemical properties, high thermal stability, and large enthalpy difference. The combination of cast iron and carbon dioxide gas enables small temperature difference heat transfer between the heat storage body 1 and the heat extraction medium, resulting in a fast heat storage and release rate and high efficiency.

[0038] In one embodiment, the heating device in the heat storage channel 2 is an electromagnetic heater, which uses electromagnetic eddy currents and radiation heat transfer to heat the heat storage body 1, so that the temperature of the heat storage body 1 reaches above 700°C.

[0039] This utility model also provides an optimized design method, applied to the solid thermal storage device as described above, including the following:

[0040] Given that the operating temperature range of the heat storage body 1 is T1~T2, the operating temperature range of the heat extraction medium is t1~t2, the diameter of the heat extraction channel 3 is d, the number of heat extraction channels 3 is n, and the heat storage body 1 adopts a cuboid structure, determine the length L of the heat extraction channel 3, the width W of the heat extraction cross section, and the height H of the heat extraction cross section;

[0041] Determine the length of heat extraction channel 3:

[0042]

[0043] Where S is the heat exchange area;

[0044] Determine the height of the heat extraction section:

[0045] H = D + 2 × (d + 2δ);

[0046] Determine the width of the heat extraction section:

[0047] W = (n / 2 + 1)δ + (n / 2)d;

[0048] Wherein, δ is the distance between the heat extraction channels 3, between the heat extraction channel 3 and the heat storage channel 2, and between the heat extraction channel 3 and the wall of the heat storage body 1.

[0049] In one implementation, the design parameters are checked:

[0050] Actual volume:

[0051] V 实 =L×W×HV 取热 -V 储热 ;

[0052] In the above formula, V 取热 To measure the volume of heat channel 3, V 储热 The volume of heat storage channel 2 is calculated using the following formulas:

[0053] V 取热 = nπ(d / 2) 2 L;

[0054] V 储热 =π(D / 2) 2 W;

[0055] Actual heat storage:

[0056] P 实 =ρV 实 (C p1 T1-C p2 T2);

[0057] In the above formula, ρ is the density of heat storage body 1, and C p1 and C p2 These are the specific heat capacities of heat storage 1 at operating temperatures T1 and T2, respectively;

[0058] Design margin calculation:

[0059] ε=(P 实 -P) / P.

[0060] The present invention provides an embodiment for determining the heat storage material used in a solid heat storage device, as follows:

[0061] The chemical composition, mechanical properties, and physical properties of the thermal storage materials are shown in Tables 1 to 3:

[0062] Table 1 Mechanical Properties of Cast Iron

[0063]

[0064]

[0065] Table 2 Chemical composition of cast iron

[0066] chemical composition C Mn Si S≤ P≤ Cr≤ Mo≤ <![CDATA[SCSiMn2H]]> 0.4-0.47 0.7-1.4 0.3-0.8 0.035 0.035 0.03 0.03

[0067] Table 3 Physical properties of cast iron

[0068] <![CDATA[Density g / cm 3 > Coefficient of thermal expansion / ℃ Thermal conductivity W / (m·K) Specific heat capacity (kJ / (kg·K)) 6.9～7.3 <![CDATA[1.1×10 -5 ~1.8×10 -5 ]]> 40～60 0.528～0.687

[0069] The present invention provides an embodiment for determining the heat extraction gas used in a solid thermal storage device, as follows:

[0070] The physical properties of common gases are shown in Table 4. As can be seen from the table, after removing combustible gases, oxidizing gases, rare gases, and relatively expensive gases, only water vapor, carbon dioxide, and nitrogen can be used as heat transfer media. Among them, carbon dioxide has the largest enthalpy difference per unit volume, and therefore has the largest heat carrying capacity under the same conditions. Through comparative analysis of common gases, carbon dioxide has advantages such as low cost, stable chemical properties, high thermal stability, and large enthalpy difference. Therefore, carbon dioxide gas was ultimately selected as the heat transfer gas for the solid-state thermal storage device.

[0071] Table 4 Gas List

[0072]

[0073]

[0074] This utility model also provides an optimized implementation method for the structural design of the heat storage body 1, as follows:

[0075] Mathematical model of components:

[0076] In this embodiment, the heat storage body 1 adopts a cuboid structure, with the length of its heat extraction channel 3 being L, the width of its heat extraction cross-section being W, and the height of its heat extraction cross-section being H. The operating temperature range of the heat storage body 1 is T1~T2 (T1>T2), the operating temperature range of the heat extraction medium is t1~t2 (t1>t2), the diameter of the heat extraction channel 3 is d, and the number of heat extraction channels 3 is n.

[0077] ① Determination of the length of heat channel 3

[0078] Mass flow rate q of heat extraction medium m

[0079]

[0080] Where P is the design heat storage capacity of heat storage body 1, in kW; h high and h low These are the enthalpy values ​​corresponding to the working temperatures t1 and t2 of the heat extraction medium, respectively, in kJ / kg;

[0081] Volumetric flow rate q v

[0082]

[0083] In the formula, q v The volumetric flow rate of the heat extraction medium, in m³ / s. 3 / h;ρ high and ρ low These are the densities of the heat extraction medium at operating temperatures t1 and t2, respectively, in kg / m³. 3 ;

[0084] Heat extraction medium flow rate V

[0085]

[0086] In the formula, V is the flow velocity of the heat extraction medium, in m / s; d is the diameter of the heat extraction channel 3; and n is the number of heat extraction channels 3.

[0087] Reynolds number Re

[0088]

[0089] In the formula, ν is the dynamic viscosity coefficient of the fluid.

[0090] Prandtl number Pr

[0091]

[0092] In the formula, Pr is the average Prandtl number of the heat exchange medium; Prhigh and Prlow are the Prandtl numbers corresponding to the working temperatures t1 and t2 of the heat exchange medium, respectively.

[0093] Nusselt number

[0094] Nu=0.021Re0.8Pp0.43(6)

[0095] Thermal conductivity λ

[0096]

[0097] In the formula, λ is the average thermal conductivity of the heat extraction medium; λhigh and λlow are the thermal conductivity of the heat extraction medium at operating temperatures t1 and t2, respectively.

[0098] convective heat transfer coefficient h

[0099]

[0100] Logarithmic mean temperature difference Δt

[0101]

[0102] Heat exchange area S

[0103]

[0104] The length L of the heat extraction channel 3

[0105]

[0106] In the formula, L is the length L of the heat extraction channel 3.

[0107] ② Determining the heat extraction cross-sectional dimensions of the thermal storage device

[0108] The heat extraction cross-sectional structure of heat storage body 1 is as follows: Figure 2 As shown, let the number of heat extraction channels 3 be n, the diameter be d, the distance between heat extraction channels 3, the distance between heat extraction channels 3 and the edge of heat storage body 1, and the distance between heat extraction channels 3 and heat storage channel 2 be δ (δ≥5mm), and the diameter of heat storage channel 2 be D. Based on this, the height H and width W of the heat extraction cross-section can be expressed as:

[0109] H=D+2×(d+2δ) (12)

[0110] W=(n / 2+1)δ+(n / 2)d (13)

[0111] ③ Design parameter verification

[0112] After the preliminary design of the external shape of the thermal storage body 1 and the structural dimensions of the thermal storage channel 2 and the heat extraction channel 3, the actual heat storage capacity of the thermal storage body 1 needs to be verified:

[0113] Actual volume:

[0114] V 实 =L×W×HV 取热 -V 储热 (14)

[0115] In the above formula, V 取热 To measure the volume of heat channel 3, V 储热 The volume of heat storage channel 2 is calculated using the following formulas:

[0116] V 取热 = nπ(d / 2) 2 L (15)

[0117] V 储热 =π(D / 2) 2 W (16)

[0118] Actual heat storage:

[0119] P 实 =ρV 实 (C p1 T1-C p2 T2) (17)

[0120] In the above formula, ρ is the density of heat storage body 1, and Cp1 and C p2 These are the specific heat capacities of heat storage body 1 at operating temperatures T1 and T2, respectively.

[0121] Design margin calculation:

[0122] ε=(P 实 -P) / P (18)

[0123] In the above formula, ε represents the design margin.

[0124] This utility model uses specific examples to illustrate its principles and implementation methods. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the idea of ​​this utility model. In summary, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A solid thermal storage device, characterized in that, include: A heat storage body is provided with non-interconnected heat storage channels and heat extraction channels, which are arranged in a crisscrossing manner. Heating device, wherein the heating device is disposed inside the heat storage channel; and a heat-extracting medium, which fills the interior of the heat-extracting channel; The heat extraction medium is carbon dioxide gas, and the heat storage body is made of cast iron.

2. The solid thermal energy storage device according to claim 1, characterized in that: The heat storage channel is located in the middle of the heat storage body, and the heat extraction channels are arranged parallel to each other on both sides of the heat storage channel.

3. The solid thermal energy storage device according to claim 2, characterized in that: The heat storage body has a cuboid structure, the heat extraction channel passes through a set of heat extraction surfaces in the cuboid structure, the heat storage channel passes through a set of heat storage surfaces in the cuboid structure, and the heat extraction channel is perpendicular to the heat storage channel.

4. The solid thermal energy storage device according to claim 3, characterized in that: The top surface of the cuboid structure is provided with a positioning groove, and the bottom surface of the cuboid structure is provided with a positioning protrusion. The positioning groove and the positioning protrusion of different cuboid structures can be connected in conjunction.

5. The solid thermal energy storage device according to claim 4, characterized in that: Both the positioning groove and the positioning protrusion are arranged in a cross shape.

6. The solid thermal energy storage device according to claim 3, characterized in that: The distances between the heat extraction channels, between the heat extraction channel and the heat storage channel, and between the heat extraction channel and the wall of the heat storage body are equal.

7. The solid thermal energy storage device according to claim 3, characterized in that: The heat extraction channel is located in the middle of the heat storage body, and the heat storage channel is located on both sides of the heat extraction channel.

8. The solid thermal energy storage device according to claim 3, characterized in that: The heating device is an electromagnetic heater.

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