A new type of regenerative heat exchanger and its design method

Abstract

This invention relates to the field of thermal energy storage technology, and discloses a novel regenerative heat exchanger and its design method. By dividing the heat storage unit into multiple series-connected temperature zone blocks and using a thermally conductive interlayer between adjacent heat storage units, the temperature difference between adjacent heat storage units can be balanced using the thermally conductive interlayer, avoiding excessive local temperature differences that could affect the heat storage and release efficiency. Simultaneously, by gradient-setting the heat transfer coefficient and equivalent diameter of the flow channels from the high-temperature end to the low-temperature end, the corresponding flow channel structure is matched to the heat transfer characteristics of different temperature ranges. This invention not only enhances heat absorption and suppresses high-temperature heat loss in the high-temperature zone, but also ensures heat transfer efficiency in the medium and low-temperature zones. It fully utilizes the latent heat of phase change materials in different temperature zones, significantly improving the overall heat storage volume utilization rate, and solving the problems of low heat transfer efficiency, large heat loss, and large temperature output fluctuations in traditional heat storage devices, thus balancing heat storage capacity and heat transfer stability.

Description

Technical Field

[0001] This invention relates to the field of thermal energy storage technology, and discloses a novel regenerative heat exchanger and its design method. Background Technology

[0002] Currently, most solid thermal accumulators on the market use a fixed type of magnesia brick (MgO brick) for their internal heat storage, resulting in a simple brick structure. The traditional heat storage structure consists of rectangular heat storage channels formed by stacking magnesia bricks, with each heat storage hole aligned horizontally and vertically. High-temperature fluid (or resistance wire) exchanges heat with the magnesia bricks through these rectangular channels, storing the heat within the bricks. This structure is currently the most traditional and mainstream construction method in the field of solid thermal accumulators. Its technology is relatively mature, its manufacturing cost is low, and it can meet basic heat storage and heat exchange requirements.

[0003] However, traditional magnesia brick accumulators have the following main drawbacks or require improvement:

[0004] 1) The brick-built flow channel structure results in high flow resistance and limited heat exchange area: Traditional heat accumulators use bricks to form the flow channel. The channel wall is made up of the sides of multiple bricks, and there are gaps and steps at the joints, which increases the frictional resistance and local resistance of the fluid flow. At the same time, the built-up structure restricts the flexible design of the flow channel shape and size, and makes it impossible to perform gradient optimization of the flow channel according to the fluid temperature and heat exchange requirements, making it difficult to further improve the heat exchange efficiency.

[0005] 2) The use of magnesia bricks as the sole heat storage medium results in low heat storage capacity and unstable heat release temperature: Traditional heat accumulators rely entirely on the sensible heat of magnesia bricks for heat storage. Magnesia bricks have a low specific heat capacity, resulting in limited heat storage per unit volume. Furthermore, as the heat release process progresses, the temperature of the magnesia bricks continuously decreases, making it impossible to maintain a stable output temperature. The lack of a latent heat compensation mechanism from phase change materials makes it difficult to achieve constant or near-constant temperature output during the heat release process.

[0006] 3) Lack of temperature gradient matching concept in structural design: Traditional heat accumulators do not divide the heat storage medium into temperature zones, and high-temperature fluids and low-temperature fluids share the same type of flow channel, failing to consider the different requirements for heat exchange and heat loss control in different temperature zones. No radiation heat loss suppression measures are taken in the high-temperature zone, and no heat exchange enhancement measures are taken in the low-temperature zone, making it difficult to balance overall heat exchange efficiency and heat loss control.

[0007] 4) Simple insulation structure and large heat loss: Traditional heat accumulators mostly use a single-layer insulation structure, and the heat storage body is in direct contact with the shell or conducts heat through the supporting structure. There is a significant thermal bridge effect, and heat is easily lost through conduction, resulting in limited insulation effect. Summary of the Invention

[0008] The purpose of this invention is to provide a novel regenerative heat exchanger and its design method, which can enhance heat absorption in the high-temperature zone, suppress high-temperature heat loss, and ensure heat exchange efficiency in the medium and low-temperature zones, thus solving the problems of low heat exchange efficiency, large heat loss, and large temperature output fluctuations in traditional regenerative heat exchangers.

[0009] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows: A novel regenerative heat exchanger includes a rectangular heat storage body, wherein the heat storage body includes multiple heat storage units arranged in parallel along the length of the heat storage body; Each of the heat storage units includes multiple temperature zone blocks arranged in series. Each temperature zone block is provided with a flow channel. The flow channels of adjacent temperature zone blocks in the heat storage unit are connected in series to form a fluid channel for the fluid medium to flow in the corresponding heat storage unit. A heat-conducting interlayer is provided between two adjacent heat storage units of the heat storage body; Each temperature zone block structure of each of the heat storage units is filled with phase change material for heat exchange with the fluid heat source flowing through the corresponding temperature zone block structure, so as to store or release heat. The fluid medium exchanges heat within multiple temperature-divided blocks connected in series, resulting in high-temperature and low-temperature ends at both ends of the fluid channel. The heat transfer coefficient of the flow channel in adjacent temperature-divided blocks in the heat storage unit decreases gradually from the high-temperature end to the low-temperature end, and the equivalent diameter of the flow channel in adjacent temperature-divided blocks in the heat storage unit increases gradually from the high-temperature end to the low-temperature end.

[0010] Furthermore, each of the temperature zone blocks is provided with a heat-conducting sleeve, and the phase change material is filled in the corresponding heat-conducting sleeve.

[0011] Furthermore, multiple heat-conducting sleeves are provided within the same temperature zone block structure. These multiple heat-conducting sleeves are connected in series via heat-conducting strips, and the heat-conducting strips are connected to the heat-conducting interlayers that are in contact with the corresponding temperature zone block structures.

[0012] Furthermore, each of the temperature zone block structures includes at least three porous heat storage blocks. A first semi-circular groove and a second semi-circular groove are respectively formed on two opposing surfaces of each porous heat storage block. The first semi-circular grooves of two adjacent porous heat storage blocks are used to splice together to form the flow channel of the corresponding temperature zone block structure. The second semi-circular grooves of two adjacent porous heat storage blocks are used to splice together to form the chamber structure of the corresponding temperature zone block structure that contains the phase change material.

[0013] Furthermore, it also includes an inner shell and an outer shell, the inner shell being fitted onto the outer wall of the heat storage body, the outer shell being disposed on the outer periphery of the inner shell, and a support plate being provided between the inner shell and the outer shell to form an air interlayer or vacuum interlayer between the inner shell and the outer shell.

[0014] Furthermore, the inner wall of the outer casing is provided with a heat-reflecting layer, which is installed on the inner wall of the outer casing through a heat-resistant layer or a heat-insulating layer.

[0015] To achieve the above-mentioned technical effects, the present invention also provides a design method for a novel regenerative heat exchanger, used to obtain the novel regenerative heat exchanger, comprising: Based on the dimensional parameters of each component of the regenerative heat exchanger and the material performance parameters of each temperature zone block structure in the heat storage body, a heat transfer analysis model of the regenerative heat exchanger is constructed. Using the flow channel opening ratio and equivalent diameter in each temperature zone block structure of a single heat storage unit as flow channel design variables, and the given temperature at the high-temperature end of the fluid channel when the fluid medium enters the heat storage body during heat storage as the simulation condition, the temperature distribution of all heat storage units after the fluid medium temperature at the low-temperature end of the flow channel stabilizes under different flow channel design variables is obtained through simulation. The heat transfer analysis model is then used to analyze and obtain the flow channel design variables that satisfy the given flow channel heat transfer coefficient of each temperature zone block structure. Based on the average temperature within the same temperature zone of the heat storage unit, the thermal conductivity of the material of the thermally conductive interlayer, and the contact thermal conductivity between the thermally conductive interlayer and the heat storage unit, the heat loss of the heat storage body under different thermally conductive interlayer thicknesses is analyzed. The thickness of the thermally conductive interlayer corresponding to the minimum heat conduction loss of the heat storage body is determined as the design dimension of the thermally conductive interlayer thickness in the heat storage body. The flow channel opening ratio and the equivalent diameter of the flow channel, which satisfy the given heat transfer coefficient of each temperature zone block structure, are the flow channel design dimensions of the corresponding temperature zone block structure.

[0016] Furthermore, the heat loss of the heat storage body under different thermally conductive interlayer thicknesses is based on... Analysis yielded, among which The thickness of the thermally conductive interlayer is Heat loss due to heat transfer from the heat storage body at that time The average temperature within the temperature-divided structure connected to the high-temperature end of the fluid channel. The average temperature within the temperature-divided block structure connected to the low-temperature end of the fluid channel. The thermal conductivity of the material in the thermally conductive interlayer is... This represents the total contact area between the thermally conductive interlayer and all temperature-zoned structural sections within the heat storage unit. The contact thermal conductivity is the coefficient between the thermally conductive interlayer and the thermal storage unit.

[0017] Compared with the prior art, the beneficial effects of this invention are: 1. During the heat storage stage, the heat storage body of the present invention can improve the heat storage capacity by setting the heat transfer coefficient and equivalent diameter of the flow channel in a gradient manner. This can effectively reduce radiative heat loss, enhance the thermal radiation absorption of the fluid medium in the high-temperature flow channel, achieve the synergy of heat transfer enhancement and heat loss suppression, ensure that the heat transfer coefficient in the high-temperature zone remains at a high level, and enable the temperature partition structure in the medium-temperature zone and low-temperature zone to quickly reach the peak heat storage capacity.

[0018] 2. The heat storage body of the present invention maintains a stable temperature in each temperature zone block structure for a relatively long time during the heat release process, and solves the problem of the temperature continuously decreasing with the heat output during the equilibrium heat release stage, ensuring that the heat release stage achieves constant or near-constant temperature output for a certain period of time.

[0019] 3. This invention designs the flow channel opening ratio and equivalent diameter of each temperature zone block structure to match the flow channel heat transfer coefficient with the temperature gradient of the heat storage and heat release process; by analyzing the heat transfer loss of the heat storage body under different thermally conductive interlayer thicknesses, the thickness of the thermally conductive interlayer is optimized to ensure the coordinated optimization of heat transfer efficiency and heat loss control of the heat storage body. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the novel regenerative heat exchanger structure in the embodiment; Figure 2 This is a schematic diagram of a single temperature zone block structure in the embodiment; Figure 3 This is a schematic diagram of the porous heat storage block structure in the embodiment; Figure 4 This is a schematic diagram of the connection structure between the heat-conducting sleeve and the heat-conducting strip in the embodiment; Figure 5 This is a schematic diagram of the heat storage body in the embodiment; Figure 6 This is a schematic diagram illustrating the dynamic working principle of the heat storage body in the embodiment; The components include: 1. Heat storage unit; 101. Temperature zone block structure; 102. Flow channel; 103. Phase change material; 104. Heat-conducting sleeve; 105. Heat-conducting strip; 106. Porous heat storage block; 1061. First semi-circular groove; 1062. Second semi-circular groove; 2. Heat-conducting jacket; 3. High-temperature end; 4. Low-temperature end; 5. Inner shell; 6. Outer shell; 7. Support plate; 8. Air jacket; 9. Heat reflective layer; 10. Heat-resistant layer; 11. Compressor; 12. Steam generator; 13. Fan. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0022] Example 1 See Figures 1 to 5 A novel regenerative heat exchanger includes a rectangular heat storage body, wherein the heat storage body includes a plurality of heat storage units 1 arranged in parallel along the length of the heat storage body; Each of the heat storage units 1 includes a plurality of temperature partition structures 101 arranged in series. Each temperature partition structure 101 is provided with a flow channel 102. The flow channels 102 of adjacent temperature partition structures 101 in the heat storage unit 1 are connected in series to form a fluid channel for the fluid medium to flow in the corresponding heat storage unit 1. A heat-conducting interlayer 2 is provided between two adjacent heat storage units 1 of the heat storage body; Each temperature zone block structure 101 of each heat storage unit 1 is filled with phase change material 103 for heat exchange with the fluid heat source flowing through the corresponding temperature zone block structure 101, so as to store or release heat. The fluid medium exchanges heat within multiple temperature-divided block structures 101 connected in series, resulting in high-temperature end 3 and low-temperature end 4 at both ends of the fluid channel, respectively. The heat transfer coefficient of the flow channel of adjacent temperature-divided block structures 101 in the heat storage unit 1 decreases in a gradient from high-temperature end 3 to low-temperature end 4, and the equivalent diameter of the flow channel 102 of adjacent temperature-divided block structures 101 in the heat storage unit 1 increases in a gradient from high-temperature end 3 to low-temperature end 4.

[0023] In this embodiment, the operation of the regenerative heat exchanger is divided into two parts: a heat storage process and a heat release process, wherein: During heat storage, a high-temperature fluid medium is introduced to the high-temperature end 3 of the fluid channel, where heat exchange occurs within the heat storage body, causing the phase change material 103 to absorb heat and store heat through a phase change. In this process, the temperature-dividing structure 101 near the high-temperature end 3 of the fluid channel has a higher temperature, constituting the high-temperature zone; the temperature-dividing structure 101 near the low-temperature end 4 of the fluid channel has a lower temperature, constituting the low-temperature zone; and the area between the high-temperature and low-temperature zones is the medium-temperature zone. Because the equivalent diameter of the flow channel 102 in the high-temperature zone is small, the material proportion in the medium-temperature zone is increased, thereby improving the heat storage capacity. Simultaneously, the small-aperture flow channel 102 wall has a shielding effect on high-temperature radiant heat, effectively reducing radiative heat loss and enhancing the absorption of thermal radiation by the fluid medium within the high-temperature flow channel 102. This achieves a synergistic effect of enhanced heat transfer and suppression of heat loss, ensuring that the heat transfer coefficient in the high-temperature zone remains at a high level. In the medium and low temperature zones, the temperature decreases after heat exchange by the fluid medium. By gradually increasing the equivalent diameter of the flow channel 102 to increase the heat exchange area and improve the heat exchange efficiency, the temperature partition structure 101 in the medium and low temperature zones can quickly reach the peak heat storage capacity.

[0024] During heat release, a low-temperature fluid medium is input from the low-temperature end 4. The fluid medium is first preheated in the temperature-dividing block structure 101 of the low-temperature zone. Then, the fluid medium enters the temperature-dividing block structure 101 of the medium-temperature zone and the high-temperature zone through the fluid channel to achieve stepped heating, gradually releasing the heat of the heat storage body, so that the fluid outlet reaches the corresponding temperature. During this process, the phase change material 103 set in each temperature-dividing block structure 101 compensates by releasing latent heat, so that the temperature of each temperature-dividing block structure 101 remains stable for a long time during the heat release process, balancing the problem that the temperature continues to drop with the heat output during the heat release stage, and ensuring that the heat release stage achieves constant or near-constant temperature output for a certain period of time.

[0025] In some other embodiments, each of the temperature zone block structures 101 is provided with a heat-conducting sleeve 104, and the phase change material 103 is filled in the corresponding heat-conducting sleeve 104. The fluid medium flows through the heat exchange channel 102 outside the heat-conducting sleeve 104 and exchanges heat with the phase change material 103 inside the sleeve. The heat-conducting sleeve 104 can be made of a metal material with a high thermal conductivity, which can not only encapsulate and confine the phase change material 103 within the corresponding temperature zone, avoiding flow displacement of the phase change material 103 during the solid-liquid transition, but also enhance the heat transfer efficiency between the phase change material 103 and the fluid medium, further improving the heat transfer stability of the overall heat storage and release process.

[0026] In some other embodiments, multiple heat-conducting sleeves 104 are provided within the same temperature zone block structure 101. These multiple heat-conducting sleeves 104 are connected in series via heat-conducting strips 105, and the heat-conducting strips 105 are connected to the heat-conducting interlayer 2 that contacts the corresponding temperature zone block structure 101. Through the coordinated operation of the heat-conducting strips 105 and the heat-conducting interlayer 2, the heat from the multiple heat-conducting sleeves 104 can be quickly conducted to the entire temperature zone block structure 101, avoiding uneven heat exchange and excessive local temperature differences at individual sleeve locations. This further enhances the heat conduction and temperature uniformity of the entire temperature zone block structure 101, improves the overall utilization rate of the phase change material 103, and ensures the stability of the heat exchange process.

[0027] In some other embodiments, each of the temperature zone block structures 101 includes at least three porous heat storage blocks 106. Each porous heat storage block 106 has a first semi-circular groove 1061 and a second semi-circular groove 1062 formed on two opposing surfaces. The first semi-circular grooves 1061 of two adjacent porous heat storage blocks 106 are used to splice together to form the flow channel 102 of the corresponding temperature zone block structure 101, and the second semi-circular grooves 1062 of two adjacent porous heat storage blocks 106 are used to splice together to form the chamber structure of the corresponding temperature zone block structure 101 that accommodates the phase change material 103. By using a modular splicing method with porous heat storage blocks 106, the heat exchange flow channel 102 and the phase change material 103 chamber can be integrated simultaneously without the need for additional independent encapsulation components, greatly simplifying the processing and assembly process of the heat exchanger. Furthermore, the overall size and number of blocks of the temperature zone block structure 101 can be flexibly adjusted according to the actual application scenario's requirements for heat storage and heat exchange power, adapting to different specifications of installation and use requirements.

[0028] In some other embodiments, an inner shell 5 and an outer shell 6 are also included. The inner shell 5 is sleeved on the outer wall of the heat storage body, and the outer shell 6 is disposed on the outer periphery of the inner shell 5. A support plate 7 is provided between the inner shell 5 and the outer shell 6 to form an air interlayer 8 or a vacuum interlayer between the inner shell 5 and the outer shell 6.

[0029] This sandwich structure effectively blocks heat transfer between the heat storage medium and the external environment, reduces unnecessary heat dissipation during heat storage, improves the insulation performance of the entire heat exchanger, and is more conducive to maintaining the temperature stability inside the heat storage medium. It is particularly suitable for long-term heat storage applications, further improving the energy utilization efficiency of the overall heat exchange system. The support plate 7 serves two purposes: firstly, it supports and shapes the inner shell 5 and outer shell 6, ensuring the structural strength and stability of the entire shell structure and preventing deformation of the inner shell 5 due to thermal expansion and contraction of the heat storage medium; secondly, it isolates and partitions the sandwich layer, preventing structural instability in large-area sandwich structures. Depending on the insulation performance requirements of the application scenario, an air sandwich 8 or a vacuum sandwich can be selected to flexibly adjust the insulation effect and adapt to different operating conditions.

[0030] In some other embodiments, a heat-reflecting layer 9 is further provided on the inner wall of the outer shell 6. The heat-reflecting layer 9 is installed on the inner wall of the outer shell 6 through a heat-resistant layer 10 or a heat-insulating layer. The heat-reflecting layer 9 can reflect the heat radiated outward by the heat storage body back to the heat storage body side, further reducing the heat loss caused by outward radiation. In conjunction with the inner air interlayer 8 or vacuum interlayer, multiple heat insulation can be achieved, further improving the overall heat insulation effect and strengthening the ability to maintain the temperature of the heat storage body. The setting of the heat-resistant layer 10 or the heat-insulating layer can, on the one hand, buffer the temperature stress between the outer shell 6 and the heat-reflecting layer 9, avoiding the problem of detachment and cracking during temperature changes due to the large difference in their thermal expansion coefficients. On the other hand, it can also further block the outward transfer of heat, improving the overall stability and heat insulation capacity of the structure.

[0031] In addition to aluminum foil and ceramic fiber, other high-reflectivity materials such as stainless steel foil and aluminized film can also be used for the heat reflective layer 9. Besides aluminum silicate refractory fiber felt, other heat-insulating materials with a temperature resistance of not less than 600℃, such as rock wool and aerogel felt, can also be used for the high-temperature resistant layer. The outer heat insulation layer can be made of phenolic foam, extruded polystyrene foam, etc. The thickness of the air interlayer 8 can be adjusted within the range of 3~8cm, and the specific value can be optimized through CFD simulation based on the heat radiation and convection suppression effects.

[0032] Based on the same inventive concept, this embodiment also provides a design method for a novel regenerative heat exchanger, used to obtain the novel regenerative heat exchanger, comprising: Based on the dimensional parameters of each component of the regenerative heat exchanger and the material performance parameters of each temperature zone block structure 101 in the heat storage body, a heat transfer analysis model of the regenerative heat exchanger is constructed. Using the opening ratio and equivalent diameter of the flow channel 102 in each temperature zone block structure 101 of a single heat storage unit 1 as the design variables of the flow channel 102, and taking the given temperature at the high-temperature end 3 of the fluid channel when the fluid medium enters the heat storage body during heat storage as the simulation condition, the temperature distribution of all heat storage units 1 after the fluid medium temperature at the low-temperature end 4 of the flow channel 102 stabilizes under different flow channel 102 design variables is obtained through simulation. The heat transfer analysis model is then used to analyze and obtain the flow channel 102 design variables that satisfy the given heat transfer coefficient of the flow channel 102 in each temperature zone block structure 101. Based on the average temperature within the same temperature zone block structure 101 of the heat storage unit 1, the thermal conductivity of the material of the thermally conductive interlayer 2, and the contact thermal conductivity between the thermally conductive interlayer 2 and the heat storage unit 1, the heat loss of the heat storage body under different thicknesses of the thermally conductive interlayer 2 is analyzed. The thickness of the thermally conductive interlayer 2 corresponding to the minimum heat transfer loss of the heat storage body is determined as the design size of the thermally conductive interlayer 2 in the heat storage body. The opening ratio of the flow channel 102 and the equivalent diameter of the flow channel 102, which satisfy the heat transfer coefficient of each temperature zone block structure 101, are the design size of the flow channel 102 of the corresponding temperature zone block structure 101.

[0033] This embodiment designs the flow channel 102 parameters differently to match the heat exchange requirements of the different temperature zones of the heat storage body's block structure 101. The average temperature of the corresponding temperature zone is then used to analyze the conduction heat loss. The thickness of the heat-conducting interlayer 2 is optimized with the goal of minimizing the conduction heat loss of the heat storage body. This can minimize the conduction heat loss inside the heat storage body while ensuring the overall heat exchange efficiency, solving the problem of high heat loss in traditional integrated heat storage bodies and achieving synergistic optimization of heat exchange efficiency and heat loss control.

[0034] Example 2 See Figures 1 to 6 This embodiment uses a temperature zone block structure 101 composed of magnesium brick blocks as an example to describe in detail the structure and design method of the novel regenerative heat exchanger of the present invention. The regenerative heat exchanger includes a rectangular heat storage body, a phase change material 103, a thermally conductive jacket 2, an inner shell 5, an outer shell 6, and a heat insulation layer. The heat storage body includes multiple heat storage units 1 arranged in parallel along the length of the heat storage body. Each heat storage unit 1 in this embodiment includes three parts arranged in series: a high-temperature zone, a medium-temperature zone, and a low-temperature zone. Each temperature zone block structure 101 is arranged in an S-shape (top, middle, bottom), and each block is composed of neatly arranged magnesia bricks. Each temperature zone block structure 101 is provided with a flow channel 102. The flow channels 102 of adjacent temperature zone block structures 101 in the heat storage unit 1 are connected in series to form a fluid channel for the fluid medium to flow within the corresponding heat storage unit 1. According to the heat storage body design requirements, the operating temperature range of the high-temperature zone is set to 450~600℃, the operating temperature range of the medium-temperature zone is set to 300~450℃, and the operating temperature range of the low-temperature zone is set to 150~300℃ along the direction of fluid medium flow during heat storage.

[0035] A thermally conductive interlayer 2 is provided between two adjacent heat storage units 1 of the heat storage body; in this embodiment, the thermally conductive interlayer 2 is made of a thin sheet of high thermal conductivity copper-based composite material, and a thin sheet of high thermal conductivity copper-based composite material is installed between two adjacent rows of magnesium bricks (heat storage units 1) to enhance the heat transfer efficiency between magnesium bricks.

[0036] Each temperature zone block structure 101 of each heat storage unit 1 is filled with phase change material 103 for heat exchange with the fluid heat source flowing through the corresponding temperature zone block structure 101, so as to store or release heat. In this embodiment, the phase change material 103 is filled in the internal cavity of a cylindrical heat-conducting sleeve 104 made of high thermal conductivity copper-based composite material, and is respectively arranged in the temperature zone block structures 101 corresponding to the high temperature zone, medium temperature zone, and low temperature zone. The heat storage temperature of the phase change material 103 in each temperature zone block structure 101 is higher than the heat storage temperature of the magnesium brick in the corresponding cavity. Wherein: The phase transition temperature in the high-temperature zone should be set at 500–650℃, and carbonates (such as the Li2CO3-K2CO3 system, with a melting point of about 500–550℃) can be used. The phase transition temperature in the intermediate temperature range is set to 350–500℃, and a mixed nitrate (such as the Ca(NO3)2-NaNO3-KNO3 system, with a melting point of approximately 350–450℃) is used. The phase transition temperature in the low-temperature region is set at 200–350℃. It is recommended to use a ternary mixed molten salt of KNO3-NaNO2-NaNO3 (solar salt system): the phase transition temperature is about 142–220℃, the latent heat of phase transition is about 100–160 kJ / kg, and the thermal stability is excellent.

[0037] The fluid medium exchanges heat within multiple temperature-divided block structures 101 connected in series, resulting in high-temperature end 3 and low-temperature end 4 at both ends of the fluid channel. The heat transfer coefficient of the flow channel 102 of adjacent temperature-divided block structures 101 in the heat storage unit 1 decreases gradually from the high-temperature end 3 to the low-temperature end 4, and the equivalent diameter of the flow channel 102 of adjacent temperature-divided block structures 101 in the heat storage unit 1 increases gradually from the high-temperature end 3 to the low-temperature end 4.

[0038] The heat storage body formed by magnesia bricks is encapsulated and surrounded by an inner shell 5, which is suspended in the outer shell 6 by a support plate 7 to ensure that the inner and outer shells 6 do not come into direct contact. The heat of the inner shell 5 is dissipated to the outside only through thermal radiation. The inner shell 5 and the outer shell 6 are arranged in a nested multi-layer insulation structure from the inside to the outside, consisting of an aluminum foil ceramic fiber reflective layer, an aluminum silicate refractory fiber felt (temperature resistance 1200℃), and a rigid polyurethane foam insulation layer. A 5cm air gap 8 is reserved between the insulation layer and the heat storage cavity, forming a nested insulation structure of "reflective layer - high temperature resistant layer - insulation layer".

[0039] The design method of the novel regenerative heat exchanger in this embodiment includes: Step 1: Based on the dimensional parameters of each component of the regenerative heat exchanger and the material performance parameters of each temperature zone block structure 101 in the heat storage body, construct the heat transfer analysis model of the regenerative heat exchanger. In this embodiment, the heat transfer analysis model for the regenerative heat exchanger is constructed as follows:

[0040]

[0041]

[0042] in, The overall heat transfer coefficient in the high-temperature region is... The overall heat transfer coefficient in the mid-temperature region is... The overall heat transfer coefficient in the low-temperature region is... The distance that heat is conducted within the flow channel 102 of the temperature zone block structure 101 (magnesia brick) in the high-temperature zone. The distance that heat is conducted within the flow channel 102 of the temperature zone block structure 101 (magnesia brick) in the intermediate temperature zone. The distance that heat is conducted within the flow channel 102 of the temperature-dividing block structure 101 (magnesia brick) in the low-temperature zone. The thermal conductivity of the temperature-divided block structure 101 (magnesia brick) material is given. For temperature variables, For fluid medium at temperature thermal conductivity at the following values, For fluid medium at temperature The kinematic viscosity at that point, For fluid medium at temperature The Prandtl number is given below, and the above three performance parameters can be obtained by looking up a table or interpolating. The apparent velocity of the fluid medium in the corresponding temperature zone block structure 101 is calculated based on the total cross-section of the flow channel 102 of the corresponding temperature zone block structure 101. The opening ratio of the flow channel 102 in the high-temperature zone. The equivalent diameter of the flow channel in the high-temperature zone is 102. The opening ratio of the flow channel 102 in the medium temperature range, The equivalent diameter of the flow channel in the intermediate temperature range is 102. The opening ratio of the flow channel 102 in the low temperature zone. The equivalent diameter of the flow channel 102 in the low-temperature zone.

[0043] Step 2: Using the opening ratio and equivalent diameter of the flow channel 102 in each temperature zone block structure 101 of a single heat storage unit 1 as the design variables of the flow channel 102, and taking the given temperature at the high-temperature end 3 of the fluid channel when the fluid medium enters the heat storage body during heat storage as the simulation condition, the temperature distribution of all heat storage units 1 after the fluid medium temperature at the low-temperature end 4 of the flow channel 102 stabilizes under different flow channel 102 design variables is simulated, and the heat transfer analysis model is used to analyze and obtain the flow channel 102 design variables that satisfy the given heat transfer coefficient of the flow channel 102 in each temperature zone block structure 101. In this embodiment, the heat transfer coefficient of the high-temperature zone flow channel 102 is designed to be 250 W / (m²).2 For temperatures above 102 K, the heat transfer coefficient of the given mid-temperature flow channel 102 is 120~140 W / (m²). 2 ·K), given a heat transfer coefficient of 90~105 W / (m²) for the low-temperature flow channel 102. 2 • K). After obtaining the temperature distribution of all heat storage units 1, when analyzing the design variables (opening ratio and equivalent diameter of the flow channel 102) of the block structure 101 of each temperature zone, The average temperature of the high-temperature zone at the low-temperature end 4 of flow channel 102 after the fluid medium temperature stabilizes is taken respectively. The average temperature of the medium temperature zone The average temperature of the high-temperature zone .

[0044] Step 3: Based on the average temperature within the same temperature zone block structure 101 of the heat storage unit 1, the thermal conductivity of the material of the thermally conductive interlayer 2, and the contact thermal conductivity between the thermally conductive interlayer 2 and the heat storage unit 1, analyze and obtain the heat conduction loss of the heat storage body under different thicknesses of the thermally conductive interlayer 2. In this embodiment, the heat loss of the heat storage body under different thicknesses of the thermally conductive interlayer 2 is based on... Analysis yielded, among which The thickness of the thermally conductive interlayer 2 is Heat loss due to heat transfer from the heat storage body at that time The average temperature within the temperature-divided block structure 101, which is connected to the high-temperature end 3 of the fluid channel, The average temperature within the temperature-dividing block structure 101, which is connected to the low-temperature end 4 of the fluid channel, The thermal conductivity of the material of the thermally conductive interlayer 2 is... The total contact area between the thermally conductive interlayer 2 and all temperature zone block structures 101 within the heat storage unit 1 is [missing information]. is the contact thermal conductivity between the thermally conductive interlayer 2 and the heat storage unit 1.

[0045] Step 4: Determine the thickness of the thermally conductive interlayer 2 corresponding to the minimum heat transfer loss of the heat storage body as the design size of the thermally conductive interlayer 2 in the heat storage body, and satisfy the design size of the flow channel 102 opening ratio and the equivalent diameter of the flow channel 102 of the given temperature zone block structure 101 flow channel 102 heat transfer coefficient.

[0046] like Figure 1As shown, based on the analysis and design process from step one to step four, the final open area ratio of the flow channel 102 in the high-temperature zone is 11.6%, using a transverse 8-channel design; the open area ratio of the flow channel 102 in the medium-temperature zone is 20.5%, using a transverse 5-channel design; and the open area ratio of the flow channel 102 in the low-temperature zone is 32.8%, using a transverse 4-channel design. Simultaneously, the diameter of the circular flow channel 102 is adjusted according to the temperature gradient. A small diameter of 20mm is used in the high-temperature zone to reduce high-temperature radiation heat loss and increase the proportion of the magnesia brick heat storage body in the high-temperature cavity, thereby increasing the heat storage capacity. The diameter of the flow channel 102 in the medium-temperature zone is 35mm, and the diameter of the flow channel 102 in the low-temperature zone is 50mm, increasing the heat exchange area and improving the heat exchange efficiency, allowing the magnesia brick heat storage body in the low-temperature cavity to quickly reach its peak heat storage capacity.

[0047] like Figure 6 As shown, during the heat storage stage, the heat storage body and compressor 11 are connected via electric valves A and B. During the heat release stage, the high-temperature end 3 and low-temperature end 4 of the heat storage body are connected to electric valves C and D, respectively. Cold fluid medium from fan 13 enters the heat storage body through electric valve C. After being heated, the fluid medium releases heat in steam generator 12 and then re-enters the heat storage body through fan 13, completing the heat release cycle. Electric valves A, B, C, and D are used to switch between heat storage and heat release conditions in real time.

[0048] 1. Heat storage process: During the heat storage stage, ensure the high-temperature fluid medium channel is unobstructed by opening electric valves A and B while simultaneously closing electric valves C and D. The high-temperature fluid medium from compressor 11 enters the flow channel 102 in the high-temperature zone via the high-temperature end 3 of the heat storage body. The high-temperature fluid medium stores heat in the magnesium brick heat storage body through thermal conduction, and the heat is further transferred through the magnesium brick heat storage body to the corresponding phase change material 103 for storage. Subsequently, the temperature of the heat-exchanged high-temperature fluid decreases, and it enters the flow channel 102 in the medium-temperature zone (a guide plate is installed between the two flow channels 102 to achieve a smooth fluid transition), storing heat in the magnesium brick and the phase change material 103 in the medium-temperature zone, further reducing the fluid temperature. Finally, it enters the flow channel 102 in the low-temperature zone. Since the fluid temperature is relatively low at this point, the flow channel 102 in the low-temperature zone uses a magnesium brick channel with a large opening ratio. This increases the heat exchange area and improves the heat exchange rate of the flow channel 102, and also brings the low-temperature phase change material 103 closer to the fluid channel interface, allowing the fluid heat to be transferred more quickly through the magnesium brick heat storage body to the low-temperature phase change material 103 for storage. After heat exchange, the low-temperature fluid flows out from the heat storage body outlet and returns to compressor group 11 for the next heat storage cycle.

[0049] 2. Heat release process: During the heat release phase, electric valves A and B are closed, while electric valves C and D are opened simultaneously. The fluid medium from the blower 13 first enters the low-temperature chamber through the low-temperature end 4 of the heat storage body to preheat the fluid; then the fluid medium enters the medium-temperature zone and high-temperature zone for stepped heating, gradually releasing the heat of the heat storage body, so that the fluid medium outlet reaches the design required temperature. Since the temperature of the phase change material 103 in each temperature zone block structure 101 is higher than that of the magnesia brick heat storage body, the phase change material 103 can balance the problem of the continuous decrease in the temperature of the magnesia brick with the heat output during the heat release phase, so that the temperature of each temperature zone block structure 101 is always kept within a certain range. Finally, the high-temperature fluid medium enters the steam generator 12 to heat the process water to produce steam, and the fluid after doing work enters the heat storage body again through the blower 13 to complete the next heat release cycle.

[0050] This embodiment overcomes the shortcomings of pure magnesia bricks, which have low specific heat capacity and low heat storage capacity, by embedding phase change heat storage materials between the magnesia bricks in each heat exchange section and adopting a sandwich structure of "magnesia brick heat storage layer - metal thermal conductivity + phase change heat storage layer - magnesia brick heat storage layer". In particular, the phase change temperature of the phase change material 103 in each temperature zone is higher than the operating temperature of the corresponding magnesia brick. During the heat release stage, when the temperature of the magnesia brick drops, the phase change material 103 releases latent heat to compensate, so that the temperature of each heat exchange section remains stable for a longer period of time, overcoming the problem of continuous drop in fluid outlet temperature during the heat release process of traditional heat accumulators.

[0051] It should be noted that: In addition to the S-shaped flow channel 102 layout, the temperature zone block structure 101 in the heat storage unit 1 can also adopt a U-shaped, spiral, or other layout form that can achieve sufficient heat exchange between the fluid medium and the heat storage body. As long as the purpose of temperature gradient matching heat exchange can be achieved, it is applicable to the present invention. In addition to copper-based composite materials, the thermally conductive interlayer 2 can also be made of aluminum-based composite materials, graphene composite materials, or other metal or non-metal materials with higher thermal conductivity than magnesium bricks. The thickness can be adjusted within the range of 0.5 to 3 mm. In addition to filling a cylindrical cavity (thermal conductive sleeve 104) made of high thermal conductivity copper-based composite material, the phase change material 103 can also be encapsulated in a rectangular cavity, annular cavity or other irregular cavity, as long as it can achieve tight bonding with magnesium brick and efficient heat transfer.

[0052] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A novel regenerative heat exchanger, characterized in that, The heat storage body includes a rectangular structure, wherein the heat storage body includes a plurality of heat storage units arranged in parallel along the length of the heat storage body; Each of the heat storage units includes multiple temperature zone blocks arranged in series. Each temperature zone block is provided with a flow channel. The flow channels of adjacent temperature zone blocks in the heat storage unit are connected in series to form a fluid channel for the fluid medium to flow in the corresponding heat storage unit. A heat-conducting interlayer is provided between two adjacent heat storage units of the heat storage body; Each temperature zone block structure of each of the heat storage units is filled with phase change material for heat exchange with the fluid heat source flowing through the corresponding temperature zone block structure, so as to store or release heat. The fluid medium exchanges heat within multiple temperature-divided blocks connected in series, resulting in high-temperature and low-temperature ends at both ends of the fluid channel. The heat transfer coefficient of the flow channel in adjacent temperature-divided blocks in the heat storage unit decreases gradually from the high-temperature end to the low-temperature end, and the equivalent diameter of the flow channel in adjacent temperature-divided blocks in the heat storage unit increases gradually from the high-temperature end to the low-temperature end.

2. The novel regenerative heat exchanger according to claim 1, characterized in that, Each of the temperature zone blocks is provided with a heat-conducting sleeve, and the phase change material is filled in the corresponding heat-conducting sleeve.

3. The novel regenerative heat exchanger according to claim 1, characterized in that, Multiple heat-conducting sleeves are provided within the same temperature zone block structure. The multiple heat-conducting sleeves within the same temperature zone block structure are connected in series by heat-conducting strips, and the heat-conducting strips are connected to the heat-conducting interlayers that are in contact with the corresponding temperature zone block structures.

4. The novel regenerative heat exchanger according to claim 1, characterized in that, Each of the temperature zone block structures includes at least three porous heat storage blocks. A first semi-circular groove and a second semi-circular groove are respectively formed on two opposite sides of each porous heat storage block. The first semi-circular grooves of two adjacent porous heat storage blocks are used to splice together to form the flow channel of the corresponding temperature zone block structure. The second semi-circular grooves of two adjacent porous heat storage blocks are used to splice together to form the chamber structure of the corresponding temperature zone block structure that contains the phase change material.

5. The novel regenerative heat exchanger according to claim 1, characterized in that, It also includes an inner shell and an outer shell. The inner shell is fitted onto the outer wall of the heat storage body, and the outer shell is disposed on the outer periphery of the inner shell. A support plate is provided between the inner shell and the outer shell to form an air interlayer or vacuum interlayer between the inner shell and the outer shell.

6. The novel regenerative heat exchanger according to claim 5, characterized in that, The inner wall of the outer casing is also provided with a heat-reflecting layer, which is installed on the inner wall of the outer casing through a heat-resistant layer or a heat-insulating layer.

7. A design method for a novel regenerative heat exchanger, used to obtain the novel regenerative heat exchanger as described in any one of claims 1-6, characterized in that, include: Based on the dimensional parameters of each component of the regenerative heat exchanger and the material performance parameters of each temperature zone block structure in the heat storage body, a heat transfer analysis model of the regenerative heat exchanger is constructed. Using the flow channel opening ratio and equivalent diameter in each temperature zone block structure of a single heat storage unit as flow channel design variables, and the given temperature at the high-temperature end of the fluid channel when the fluid medium enters the heat storage body during heat storage as the simulation condition, the temperature distribution of all heat storage units after the fluid medium temperature at the low-temperature end of the flow channel stabilizes under different flow channel design variables is obtained through simulation. The heat transfer analysis model is then used to analyze and obtain the flow channel design variables that satisfy the given flow channel heat transfer coefficient of each temperature zone block structure. Based on the average temperature within the same temperature zone of the heat storage unit, the thermal conductivity of the material of the thermally conductive interlayer, and the contact thermal conductivity between the thermally conductive interlayer and the heat storage unit, the heat loss of the heat storage body under different thermally conductive interlayer thicknesses is analyzed. The thickness of the thermally conductive interlayer corresponding to the minimum heat conduction loss of the heat storage body is determined as the design dimension of the thermally conductive interlayer thickness in the heat storage body. The flow channel opening ratio and the equivalent diameter of the flow channel, which satisfy the given heat transfer coefficient of each temperature zone block structure, are the flow channel design dimensions of the corresponding temperature zone block structure.

8. The novel regenerative heat exchanger and its design method according to claim 7, characterized in that, Heat loss of heat storage body under different thermally conductive interlayer thicknesses according to Analysis yielded, among which The thickness of the thermally conductive interlayer is Heat loss due to heat transfer from the heat storage body at that time The average temperature within the temperature-divided structure connected to the high-temperature end of the fluid channel. The average temperature within the temperature-divided block structure connected to the low-temperature end of the fluid channel. The thermal conductivity of the material in the thermally conductive interlayer is... This represents the total contact area between the thermally conductive interlayer and all temperature-zoned structural sections within the heat storage unit. The contact thermal conductivity is the coefficient between the thermally conductive interlayer and the thermal storage unit.

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