A microwave heating device for pipeline flow heating
By employing a mode converter and dielectric extension region design in the microwave heating device, efficient and uniform heating of loads with varying dielectric constants and volumes is achieved, solving the flexibility and efficiency problems of traditional microwave heating devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHENGDU FENYU ELECTRONIC TECH CO LTD
- Filing Date
- 2025-06-23
- Publication Date
- 2026-06-23
AI Technical Summary
Traditional microwave heating devices are limited by the shape and size of the cavity, resulting in inflexible heating and low efficiency, and making it difficult to adapt to load changes with different dielectric constants and volumes.
Design a microwave heating device for heating pipe flow. Use a mode converter to convert the coaxial TEM mode to the TM01 mode. Combine this with the insertion of the dielectric extension region into the object being heated to achieve efficient heating of materials with a real part of dielectric constant between 5 and 80 and a loss tangent between 0.1 and 1.
It achieves flexible and efficient heating for different loads. Simulation results show that the heating efficiency is stable at over 90%, with strong robustness and uniformity, and adapts to load changes of different volumes and shapes.
Smart Images
Figure CN224401700U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of microwave heating technology, and more specifically to the field of microwave heating device for heating pipeline flow. Background Technology
[0002] Microwave energy has attracted widespread attention due to its advantages such as rapid heating, volumetric heating, ease of control, high selectivity, and environmental friendliness. Currently, microwave heating is widely used in food, chemical, pharmaceutical, and materials industries. However, traditional microwave heating requires placing the object to be heated within a cavity, which limits the object's shape and size, resulting in limited and inflexible application scenarios. Furthermore, the varying dielectric constants, volumes, and shapes of the heated object lead to unstable heating efficiency during microwave heating. Therefore, these drawbacks significantly restrict the development of industrial applications of microwave energy. Meanwhile, the problem of low microwave heating efficiency persists.
[0003] To improve the efficiency of microwave heating, scholars have proposed various methods. In industrial applications of microwave energy, circulators and three-stub tuners are widely used in microwave heating systems to protect microwave generators and improve efficiency. Circulators rely on ferrite devices to achieve asymmetric microwave propagation; reflected microwave energy is absorbed by the load at the isolation port, resulting in energy waste. Three-stub tuners can improve efficiency, but must be dynamically adjusted according to changes in the load dielectric constant. Some literature proposes a matching algorithm for three-stub tuners, achieving continuous, automatic, and real-time impedance matching. However, mismatches still occur during adjustment. Therefore, circulator protection is still necessary. Furthermore, there are many other methods to improve microwave heating efficiency. Other literature proposes an electronic adaptive coupling technique for microwave microstrip resonators, using power dividers and phase shifters to control the input phase for efficient liquid heating. Some literature also suggests improving heating efficiency by designing system cavity geometry and optimizing process variables for continuous flow microwave processing.
[0004] Most of the methods described above achieve high efficiency by constraining the electric field and adjusting impedance matching, but these methods are overly dependent on the load. They may fail if the load changes significantly. Therefore, there is a need to develop a microwave heating system capable of efficiently heating different loads. Utility Model Content
[0005] The purpose of this utility model is to provide a microwave heating device for heating pipeline flow in order to solve the above-mentioned technical problems.
[0006] To achieve the above objectives, this utility model specifically adopts the following technical solution:
[0007] This utility model provides a microwave heating device for heating pipeline flow, including a metal shell, a medium filled inside the metal shell, a coaxial port disposed at one end of the metal shell, an outer conductor disposed at the coaxial port, an inner conductor extending through the outer conductor into the metal shell, and a mode converter disposed inside the metal shell and connected to the inner conductor. An insulating medium is disposed between the outer conductor and the inner conductor. The mode converter serves as a matching network between the input impedance of the coaxial feed line and the waveguide impedance. A medium extension area is provided at the bottom of the metal shell for inserting the heated object during the heating process.
[0008] Specifically, in the subsequent heating simulation, this extended dielectric section is inserted into the object being heated to achieve an insertion heating effect. This enables efficient heating of materials with a real part of dielectric constant between 5 and 80 and a loss tangent between 0.1 and 1, while also achieving uniform heating of the load. This solution can provide flexible and efficient heating for different loads.
[0009] The TM01 mode exhibits axisymmetry in a circular waveguide, with a uniform field distribution along the circumference, no polarization degeneracy issues, and, compared to the TEM mode, directional transmission, enabling directional propagation and improving transmission efficiency. However, directly exciting the TM01 mode within a circular waveguide is problematic. 01 Creating a mode is not easy; it requires designing complex feeding structures (such as annular gaps, probe excitation, etc.) and strictly suppressing other modes (such as TM). 01 (The text abruptly shifts to a discussion of mode conversion and TEM mode excitation.) Otherwise, multimode interference is likely to occur. In a coaxial line, the TEM mode lacks longitudinal electric and magnetic field components to constrain the wave's propagation direction, making it prone to divergence, leading to energy loss and signal attenuation. However, it is easily excited in a coaxial line. Therefore, this mode converter combines the advantages of both, achieving a balance between performance and feasibility.
[0010] In one embodiment, the mode converter consists of three concentric aluminum disks stacked together, namely an upper aluminum disk, a middle aluminum disk, and a lower aluminum disk, with the diameters of the upper aluminum disk, the middle aluminum disk, and the lower aluminum disk increasing in size. The inner conductor extends out of the outer conductor and connects to the center of the bottom of the upper aluminum disk.
[0011] In one embodiment, the insulating medium between the outer conductor and the inner conductor is air.
[0012] In one embodiment, the medium filling the interior of the metal casing is aluminum oxide.
[0013] In one embodiment, the metal casing is a cylindrical structure with a diameter d of 40 mm and a length l1 of 120 mm, and the coaxial port is located at one end of the cylindrical structure.
[0014] In one embodiment, the outer conductor is a copper tube welded inside the coaxial port, the outer wall diameter of the outer conductor is d2, and the inner conductor is a copper column with a diameter of d1.
[0015] In one embodiment, the outer conductor and the inner conductor extend together into the metal casing for a length of l2, and the inner conductor extends out of the outer conductor by a dimension of l3.
[0016] In one embodiment, the upper aluminum disk, the middle aluminum disk, and the lower aluminum disk have the same thickness, x, and the diameters of the upper aluminum disk, the middle aluminum disk, and the lower aluminum disk are 2y, 3y, and 4y, respectively.
[0017] In one embodiment, the length of the dielectric extension region is l, and the diameter of the dielectric extension region is d.
[0018] The beneficial effects of this utility model are as follows:
[0019] 1. In the subsequent heating simulation, the dielectric extension region of this utility model is inserted into the object being heated to achieve the effect of insertion heating. It can achieve efficient heating of materials with a real part of dielectric constant between 5 and 80 and a loss tangent between 0.1 and 1, while also achieving uniform heating of the load.
[0020] 2. This invention provides flexible and efficient heating for different loads. Multiphysics simulation analysis was performed using COMSOL software based on the finite element method. A coaxial TEM-to-TM converter was implemented. 01 A metal casing was constructed for the model, and a heating device was designed based on this casing. Simulation results verified the effectiveness of the microwave heating device for heating pipe flow in heating large dynamic dielectric loads, with a heating efficiency consistently above 90% and exhibiting strong robustness.
[0021] 3. The effects of load volume and shape on heating efficiency were studied. The results show that the microwave heating efficiency can be maintained at a high level regardless of the load volume and shape. This demonstrates the flexibility of the microwave heating device for pipe flow heating, achieving efficient heating without being limited by the type and shape of the load.
[0022] 4. The uniformity of the microwave heating device used for pipe flow heating was analyzed. Simulation results showed excellent uniformity for loads of different volumes and shapes. This technology can be widely used in the field of industrial microwave heating and may significantly improve the efficiency of traditional microwave heating methods. Attached Figure Description
[0023] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.
[0024] Figure 1 This is a plan view of the mode converter.
[0025] Figure 2 yes Figure 1 A partial structural diagram.
[0026] Figure 3 The diagram shows the relationship between the mode converter frequency and S11, where (a) is the relationship between the mode converter frequency and S11 under different y values, and (b) is the relationship between the mode converter frequency and S11 under different x values.
[0027] Figure 4 This is a schematic diagram of the structure of a microwave heating device for heating pipeline flow according to this utility model.
[0028] Figure 5 It is S 11 A graph showing the relationship between the length of the medium extending into the water and the depth of the medium.
[0029] Figure 6 This is a heating model diagram of a circular load.
[0030] Figure 7 This is a graph showing the variation of heating efficiency with the real part of the dielectric and the loss tangent.
[0031] Figure 8 These are heating diagrams for cylindrical loads of different volumes.
[0032] Figure 9 These are heating efficiency diagrams for loads of different volumes, where (a) is the heating efficiency diagram for a load with a radius of 50 mm, and (b) is the heating efficiency diagram for a load with a radius of 100 mm.
[0033] Figure 10 These are heating model diagrams of a square load, where (a) is a heating model diagram of a square load with dimensions of 100mm*100mm*100mm and (b) is a heating model diagram of a square load with dimensions of 120mm*120mm*100mm.
[0034] Figure 11Heating efficiency of loads of different shapes: (a) heating efficiency of a square load with length, width and height of 100mm*100mm*100mm, (b) heating efficiency of a square load with length, width and height of 120mm*120mm*100mm.
[0035] Figure 12 These are temperature distribution diagrams. (a) shows the temperature distribution diagram for a cylindrical load, and (b) shows the temperature distribution diagram for a cube load.
[0036] Figure 13 This is a schematic diagram of heating an annular liquid channel.
[0037] Figure 14 This is a schematic diagram of the heating efficiency of the pipeline flow.
[0038] Figure 15 This is a temperature diagram of pipe flow heating. Detailed Implementation
[0039] To make the technical problems, technical solutions, and technical effects of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0041] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0042] In the description of the embodiments of this utility model, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0043] Example 1
[0044] This embodiment provides a microwave heating device for heating pipeline flow, including a metal shell, a medium filled inside the metal shell, a coaxial port disposed at one end of the metal shell, an outer conductor disposed at the coaxial port, an inner conductor extending through the outer conductor into the metal shell, and a mode converter disposed inside the metal shell and connected to the inner conductor. An insulating medium is disposed between the outer conductor and the inner conductor. The mode converter serves as a matching network between the input impedance of the coaxial feed line and the waveguide impedance. A medium extension area is provided at the bottom of the metal shell for inserting the heated object during the heating process.
[0045] The mode converter consists of three concentric aluminum disks stacked together: an upper aluminum disk, a middle aluminum disk, and a lower aluminum disk. The diameters of the upper, middle, and lower aluminum disks increase in that order. The inner conductor extends out to the outer conductor, which connects to the center of the bottom of the upper aluminum disk.
[0046] The insulating medium between the outer conductor and the inner conductor is air.
[0047] The medium inside the metal casing is aluminum oxide.
[0048] The metal casing is a cylindrical structure with a diameter d of 40 mm and a length l1 of 120 mm. The coaxial port is located at one end of the cylindrical structure.
[0049] The outer conductor is a copper tube welded inside the coaxial port, with an outer wall diameter of d2, and the inner conductor is a copper column with a diameter of d1.
[0050] The length by which the outer conductor and the inner conductor extend into the metal casing together is l2, and the length by which the inner conductor extends out of the outer conductor is l3.
[0051] The upper, middle, and lower aluminum discs have the same thickness, x, and their diameters are 2y, 3y, and 4y, respectively.
[0052] The length of the extended medium region is l, and the diameter of the extended medium region is d.
[0053] Specifically, in the subsequent heating simulation, this extended dielectric section is inserted into the object being heated to achieve an insertion-type heating effect. This enables efficient heating of materials with a real part of dielectric constant between 5 and 80 and a loss tangent between 0.1 and 1, while also achieving uniform heating of the load. This solution provides flexible and efficient heating for different loads. Multiphysics simulation analysis was performed using COMSOL software based on the finite element method. A coaxial TEM-to-TM converter was implemented. 01A metal casing was constructed for the model, and a heating device was designed based on this casing. Simulation results verified the effectiveness of the microwave heating device for pipe flow heating when heating large dynamic dielectric loads, with a heating efficiency consistently above 90% and exhibiting strong robustness. Furthermore, the effects of load volume and shape on heating efficiency were investigated, showing that the microwave heating efficiency remained high regardless of load volume or shape. This demonstrates the flexibility of the microwave heating device for pipe flow heating, achieving efficient heating without being limited by the type or shape of the load. Finally, the uniformity of the microwave heating device for pipe flow heating was analyzed; simulation results showed excellent uniformity for loads of different volumes and shapes. This technology can be widely applied in the field of industrial microwave heating and may significantly improve the efficiency of traditional microwave heating methods.
[0054] The TM01 mode exhibits axisymmetry in a circular waveguide, with a uniform field distribution along the circumference, no polarization degeneracy issues, and, compared to the TEM mode, directional transmission, enabling directional propagation and improving transmission efficiency. However, directly exciting the TM01 mode within a circular waveguide is problematic. 01 Creating a mode is not easy; it requires designing complex feeding structures (such as annular gaps, probe excitation, etc.) and strictly suppressing other modes (such as TM). 01 (The text abruptly shifts to a discussion of mode conversion and TEM mode excitation.) Otherwise, multimode interference is likely to occur. In a coaxial line, the TEM mode lacks longitudinal electric and magnetic field components to constrain the wave's propagation direction, making it prone to divergence, leading to energy loss and signal attenuation. However, it is easily excited in a coaxial line. Therefore, this mode converter combines the advantages of both, achieving a balance between performance and feasibility.
[0055] Example 2
[0056] This embodiment is based on Embodiment 1, and is illustrated through specific data and simulation. The specific content is as follows:
[0057] Figure 1 A plan view of the metal casing is shown, with the internal filling medium being alumina. The diameter of the medium is d = 40 mm, and the length of the metal casing is l1 = 120 mm.
[0058] Figure 2 The details of the coaxial port and metal casing are shown. The inner conductor of the coaxial port has a diameter of d1 = 7 mm and is made of copper. The inner diameter of the outer conductor is d2 = 16 mm. The insulating material is air. The combined length of the inner and outer conductors extending into the dielectric is l2 = 8 mm, with the inner conductor extending an additional 5 mm (l3 = 5 mm). Three aluminum metal discs, each with a thickness of x, are then connected, and their diameters are successively two, three, and four times the length of y.
[0059] Considering the requirement for a wide frequency range in high-power microwave generation, a broadband metal enclosure was designed. The selection process for the x and y values was carried out by... Figure 3 It is given that when x = 3mm and y = 5mm, a relatively low reflection coefficient can be guaranteed over a large range, resulting in high transmission efficiency. At 2.45GHz, the efficiency can reach over 98%. When S 11 At a voltage level <10dB, the achieved bandwidth is 900MHz, ranging from 1.94GHz to 2.84GHz. The main reason for achieving high-efficiency transmission is impedance matching, with three aluminum discs serving as a matching network between the coaxial feed input impedance and the waveguide impedance.
[0060] like Figure 4 As shown, the length of the medium extension area below the metal shell is l, and the outer metal shell is not extended. In the subsequent heating simulation, this medium extension area is inserted into the object being heated to achieve the effect of insertion heating.
[0061] The length l of the extended medium region is determined by comparing the efficiency when it is submerged in water, such as... Figure 5 As shown, the simulation results were obtained when the length l extending into the water ranged from 5 mm to 80 mm. 11 To improve detection efficiency. 11 The relationship between P and efficiency is shown in equation (1), where P r and P i These are the reflected power and the incident power, respectively.
[0062]
[0063] It can be seen that when l = 50 mm, S 11 Less than -30dB, meaning a heating efficiency of over 99.9%. Meanwhile... Figure 5 All lengths l corresponding to S can be seen in the table. 11 All values are less than -10dB, meaning the heating efficiency is above 90%, indicating that the heater has strong stability and its efficiency will not drop drastically due to changes in the length of the medium. In the simulations below, the l value corresponding to the highest efficiency, i.e., l = 50mm, will be used.
[0064] Multiphysics heating analysis:
[0065] Model settings:
[0066] Figure 6The complete heater device in simulation is shown, with a cylindrical load shape of 70 mm radius and 100 mm height, and a total volume of 1539.38 cm², capable of holding 1539.38 mL of liquid. The coaxial port is excited in TEM mode, with an operating frequency of 2.45 GHz, an input power of 1000 W, a heating time of 60 s, and an initial temperature of 293.15 K.
[0067] Governing equations:
[0068] In this scheme, electromagnetic field and heat transfer are coupled, and the electromagnetic field distribution is calculated using the Helmholtz equations:
[0069]
[0070] In the formula, μ r It is the relative permeability. ε is the electric field strength, ε0 is the relative permittivity of vacuum, and σ is the conductivity;
[0071] The temperature distribution is calculated using the thermodynamic equation, which is:
[0072]
[0073] In the formula, ρ and C ρ T, Q and K t These represent material density, heat capacity, thermodynamic temperature, heat source, and thermal conductivity, respectively; t is time.
[0074] The electromagnetic field and the heat transfer field are connected through electromagnetic losses.
[0075]
[0076] In the formula, ε0, ε″ and Q e =Q represents the dielectric constant of vacuum, the imaginary part of the dielectric constant, and the electromagnetic power loss, respectively;
[0077] Boundary conditions:
[0078] Two boundary conditions must be considered in the calculation: electromagnetic boundary conditions and thermal boundary conditions. When electromagnetic waves propagate in the medium, the coaxial port is set as a TEM mode port, and the other walls are set as PECs with boundary conditions.
[0079]
[0080] In the formula It is the unit normal vector of the corresponding surface.
[0081] Except for the portion in contact with the extending medium, the walls of the heating chamber are configured as adiabatic boundaries, as shown in the following equation:
[0082]
[0083] This means that there is no heat exchange between the load and the outside air during the heating process.
[0084] Input parameters:
[0085] The input parameters for the heating system model are shown in Table 1.
[0086] Table 1 Material Parameters
[0087]
[0088]
[0089] The effect of load dielectric on microwave heating efficiency:
[0090] To verify the heating performance of the insertion-type microwave heating system on large dynamic dielectric loads, this study set the real part of the load's dielectric constant to vary in the range of 5-80, and the loss tangent to vary in the range of 0.1-1. The heating efficiency was measured by S... 11 The conclusion is as follows. Figure 7 As shown in this range, S 11 All values are less than -10dB, meaning the heating efficiency remains consistently above 90%, and can reach 99% for materials with high dielectric constants. The heating efficiency of this device increases with the real part of the dielectric constant and decreases slightly with the increase of the loss tangent. Furthermore, the device exhibits good stability under loads with high loss tangents. 11 The changes were relatively gradual.
[0091] The effect of load volume on microwave heating efficiency:
[0092] To verify the universality of the proposed heating system, such as Figure 8 As shown, keeping the height of the cylindrical load constant at 100mm, the radius was changed to 50mm and 100mm respectively, i.e., loads of 785mL and 3141mL were placed for simulation.
[0093] Similarly, the real part of the dielectric constant of the load is set to vary in the range of 5-80, and the loss tangent is set to vary in the range of 0.1-1. The heating efficiency is determined by S. 11 The conclusion is as follows. Figure 9 As shown, the heating efficiency remains high even with varying load volumes. Overall, the heating efficiency of this device increases with the real part of the dielectric constant and decreases slightly with the increase of the loss tangent. The heating device exhibits better stability when handling larger loads, especially when heating loads with smaller loss tangents, compared to… Figure 7 and Figure 9 As the load volume increases, S 11 The curve becomes increasingly flat, and when heating a load with a relatively small loss tangent, its S... 11 The curve will not exhibit drastic fluctuations.
[0094] The effect of load shape on microwave heating efficiency:
[0095] To further verify the universality of the proposed heating system, such as Figure 10 As shown, the load is changed from a cylinder to two different cuboids. One is a cube with a side length of 100mm, which can hold a load of 1000mL. The other load is a cuboid with a height of 100mm and the other two sides having a side length of 120mm, which can hold a load of 1440mL.
[0096] The load dielectric constant was still set to vary in the range of 5-80, and the loss tangent was set to vary in the range of 0.1-1. The heating efficiency was controlled by S. 11 The conclusion is as follows. Figure 11 As shown, the heating efficiency remains high even with loads of varying dielectric constants, regardless of their shape. Furthermore, the efficiency of the heating device continues to increase with the real part of the dielectric constant, but decreases slightly with the increase of the loss tangent. The conclusions in Section 3.2 also hold true when dealing with loads of different shapes: as the load volume increases, the heating device exhibits greater stability, especially with loads of lower loss tangents.
[0097] Microwave heating uniformity analysis:
[0098] To verify the uniformity of the heating device, water was used as the load. Two loads were used: a cylindrical load with a radius of 70 mm and a height of 100 mm, and a cubic load with a side length of 100 mm. The heating time was 60 seconds. Figure 12 As shown, a circular area with a length and width of 10 mm was selected, and its temperature change was monitored. Meanwhile, the average body temperature and COV value shown in Table 2 indicate that the heating device has good axial heating uniformity.
[0099] Table 2. Body Mean Temperature and COV
[0100]
[0101] This heating device utilizes a mode converter to convert the TEM mode to the TM mode. 01 The heating device can utilize TM 01 Axial uniformity during transmission of the medium ensures uniform axial heating of the load in contact with the medium.
[0102] Waveguide flow heating method is as follows:
[0103] The microwave heating device used for pipe flow heating is considered as a single module. This paper introduces the use of multiple modules for high-power, high-efficiency microwave heating of pipe flow and discusses the effects of dielectric constant and flow rate on heating efficiency.
[0104] Pipeline flow heating system such as Figure 13 As shown, three modules are evenly placed above the annular liquid channel, with the protruding ceramic media inserted into the pipe, flowing in and out in the direction of the arrows. The flow velocity in the pipe is set to 0.02 m / s, and the input power of each module remains 1000 W.
[0105] The real part of the load dielectric constant varies from 5 to 80° within the annular liquid channel, and the loss tangent varies from 0.1 to 1. The heating efficiency is obtained by calculating the electromagnetic power loss density within the pipe, as shown in the figure. Figure 14 As shown, the heating efficiency remains above 90% even under loads with a wide range of dielectric constants. Furthermore, the efficiency of this heating device still increases with the increase of the real part of the dielectric constant, but the correlation with the loss tangent decreases. When the loss tangent changes, it does not significantly affect the heating efficiency, demonstrating higher stability.
[0106] The load within the annular liquid channel is water, such as Figure 15 The image shows the temperature distribution after 60 seconds of heating. It can be seen that the heating within the pipe flow exhibits good uniformity, thus achieving efficient heating for loads that are not in direct contact with the heating device.
[0107] in conclusion:
[0108] This embodiment proposes a direct insertion heating device and performs multiphysics simulation analysis using COMSOL software based on the finite element method. It realizes a device that converts a coaxial TEM module to a TM module. 01 A mode converter was developed, and a heating device was designed based on this converter. Simulation results verified the effectiveness of the system in heating large dynamic dielectric loads, with a heating efficiency consistently above 90% and exhibiting strong robustness. Furthermore, the effects of load volume and shape on heating efficiency were investigated. The results show that the microwave heating efficiency remains high regardless of the load volume or shape. This demonstrates the flexibility of the heating device, achieving efficient heating without being limited by the type or shape of the load. Finally, the uniformity of microwave heating was analyzed. Simulation results show excellent uniformity for loads of different volumes and shapes. This technology is expected to be widely used in industrial microwave heating and may significantly improve the efficiency of traditional microwave heating methods.
Claims
1. A microwave heating apparatus for in-line heating, characterized by, The application relates to a coaxial-to-waveguide mode converter, comprising a metal shell, a medium filled in the metal shell, a coaxial port arranged at one end of the metal shell, an outer conductor arranged at the coaxial port, an inner conductor extending into the metal shell through the outer conductor, a mode converter arranged in the metal shell and connected with the inner conductor, and an insulating medium arranged between the outer conductor and the inner conductor, wherein the mode converter serves as a matching network between the input impedance of the coaxial feeder and the wave impedance of the waveguide, and the bottom of the metal shell is provided with a medium extension area for inserting an object to be heated during heating.
2. A microwave heating apparatus for heating a pipe flow according to claim 1, wherein The mode converter is composed of three concentric aluminum discs, i.e. an upper aluminum disc, a middle aluminum disc and a lower aluminum disc, wherein the diameters of the upper aluminum disc, the middle aluminum disc and the lower aluminum disc increase in sequence, and the inner conductor extends out of the outer conductor and is connected to the center of the bottom of the upper aluminum disc.
3. A microwave heating apparatus for in-line heating according to claim 2, wherein The insulating medium between the outer conductor and the inner conductor is air.
4. A microwave heating apparatus for heating a pipe flow according to claim 3, wherein The medium filled in the metal shell is alumina.
5. A microwave heating apparatus for heating a pipe flow according to claim 2, wherein The metal shell is in a cylindrical structure, the diameter d of the metal shell is 40 mm, the length l1 of the metal shell is 120 mm, and the coaxial port is arranged at one end of the cylindrical structure.
6. A microwave heating apparatus for in-line heating according to claim 5, wherein The outer conductor is a copper pipe welded in the coaxial port, the outer wall of the outer conductor has a diameter d2, and the inner conductor is a copper column with a diameter d1.
7. A microwave heating apparatus for in-line heating according to claim 6, wherein The length of the outer conductor and the inner conductor extending into the metal shell is l2, and the size of the inner conductor extending out of the outer conductor is l3.
8. A microwave heating apparatus for in-line heating according to claim 7, wherein The thicknesses of the upper aluminum disc, the middle aluminum disc and the lower aluminum disc are the same, and are x, and the diameters of the upper aluminum disc, the middle aluminum disc and the lower aluminum disc are 2y, 3y and 4y respectively.
9. A microwave heating apparatus for heating a pipe flow according to claim 1, wherein The length of the medium extension area is l, and the diameter of the medium extension area is d.