CN217591139U - Waveguide slot array heater - Google Patents
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Abstract
The utility model relates to a waveguide gap array heater belongs to microwave heating technical field. The utility model discloses a cylindrical cavity resonator and around cylindrical cavity resonator and opened curved surface waveguide and the waveguide feed in gap. The utility model discloses a microwave energy that well magnetron produced forms the standing wave in presenting a mouthful feed-in to the curved surface waveguide, and the energy passes through waveguide gap radiation and gets into cylindrical cavity the inside, is absorbed by the inside material of cylindrical cavity to reach the heating effect to the material. The heating method avoids the phenomena of ignition and scorching caused by overhigh heating energy of the magnetron; the gap array can make the electric field of feed-in cylindrical resonant cavity more even, and the material more can reach the effect of even heating. Therefore, the heating device has the characteristics of simple structure, low cost, high coupling efficiency between the feed port and the cylindrical cavity, large cavity volume, high Q value, greener microwave heating, high efficiency, energy conservation and the like.
Description
Technical Field
The utility model relates to a waveguide gap array heater belongs to microwave heating technical field.
Background
With the development of science and technology, in industrial production, people put forward higher requirements on energy conservation, emission reduction and clean and efficient production, the traditional heating cannot completely meet the requirements, and at the moment, the microwave heating technology with the characteristics of high efficiency, energy conservation, cleanliness and the like is developed. Starting from microwave ovens, this heating mode gradually goes into people's lives and exhibits great potential for development. The heat effect of the microwave is not limited to heating food at present, and the microwave has great development potential in other various fields. Microwave heating has wide application in medical treatment, new material preparation, material treatment and the like. These aspects have together driven the development of microwave heating systems.
Microwave heating is a heating mode which absorbs microwave energy by an object and converts the microwave energy into heat energy to heat the whole body of the object at the same time. Compared with microwave heating, the traditional heating mode is that heat is transferred to material heat from the outside according to heat conduction, convection and radiation principles, the heat is always transferred from the outside to the inside to heat materials, a temperature gradient inevitably exists in the materials, and therefore the heated materials are uneven, so that the materials are locally overheated. Therefore, compared with the traditional heating mode, the microwave heating mode has obvious advantages: the thermal inertia is small, selective heating can be carried out according to different wave-absorbing materials, and the wave-absorbing material is green and energy-saving and the like.
Although microwave heating has many advantages compared with traditional heating, in practical industrial production, when high-power microwaves are applied to microwave heating technology, because the electromagnetic field distribution in a heating cavity is not uniform and the microwave absorption capacity of each material can change along with the change of temperature, and meanwhile, because of the dielectric loss of a medium, the temperature of the medium can rise as long as the microwave acts on the medium, so that the microwave heating is easy to generate a hot spot and thermal runaway phenomenon, and the safety and effectiveness of microwave energy application are reduced.
At present, designers mainly study the uniformity of an electric field in a resonant cavity in the process of designing a microwave heater, and the size of the cavity and the position or the number of feed ports can influence the uniformity of the electric field. Designers often resort to HFSS software to optimize the electric field within the cavity and the feed-in reflection. The mode of simulating before processing experiment greatly reduces the research cost.
The microwave heater is designed to be used as a carrier for microwave heating, namely the design of a microwave resonant cavity becomes the key for converting microwave energy into heat energy. The shape of the microwave cavity has a great influence on the distribution of the electromagnetic field therein: the resonant cavity with the improper shape has poor heating effect, and even the resonant cavity cannot generate resonance at all. At present, the common microwave heating cavity mainly comprises a rectangular resonant cavity, a cylindrical resonant cavity and a spherical resonant cavity. Compared with rectangular and spherical resonant cavities, the cylindrical resonator has the advantages of low manufacturing cost, strong pressure resistance, larger and easily controlled geometric dimension, very high Q value, mature manufacturing process and the like. Is the most developed and widely applied microwave heater. However, due to the restriction of the cavity structure, the number of modes existing in the cavity is small, and the field distribution is not uniform.
Disclosure of Invention
The to-be-solved technical problem of the utility model is: the utility model provides a waveguide gap array heater, the device are on the basis of the various advantages of the cylindrical resonant cavity of full play for electric field distribution is more even in the cavity, and is more concentrated near the mode spectral line distribution of operating frequency 2.45GHz, and microwave heating's speed is faster, efficiency is higher, the cost is lower, has improved the inhomogeneous problem of electric field.
The utility model adopts the technical scheme that: a waveguide slot array heater comprises a cylindrical resonant cavity body 1, a curved surface waveguide 3 arranged on the side surface of the cylindrical resonant cavity body 1 and closely connected with the cylindrical resonant cavity body 1 in a closed manner, a magnetron feed port 2 arranged on one end surface of the curved surface waveguide 3, and a waveguide slot array 4 arranged on the curved surface waveguide 3 and coplanar with the cylindrical resonant cavity body 1; the curved surface waveguide 3 and the cylindrical resonant cavity body 1 are completely attached and tightly connected in a closed manner.
As a further proposal of the utility model, the curved waveguide 3 which is arranged on the side surface of the cylindrical resonant cavity body 1 and is closely connected with the cylindrical resonant cavity body 1 in a closed manner has the same curvature radius of the curved waveguide 3 as that of the cylindrical resonant cavity body 1 because the curved waveguide is completely attached to the cylindrical resonant cavity body 1; the transmission mode of the curved waveguide 3 is a main mode TE 10 And other higher-order modes are cut off, so the requirements on the section size of the curved waveguide 3, the length a of the wide side of the cross section and the length b of the narrow side of the cross section are as follows: b<a/2。
As a further aspect of the present invention, the cross-sectional dimension of the curved waveguide 3 is 86.4mm × 30.5mm.
As a further aspect of the present invention, the curved waveguide 3 disposed on the side of the cylindrical cavity body 1 and closely connected to the cylindrical cavity body 1 in a closed manner is a master mode TE as the transmission mode of the curved waveguide 3 10 Transmission frequency f =2.45GHz, wavelength λ in free space, waveguide wavelength λ g Wherein the relationship between the waveguide wavelength and the wavelength in free space is:
a is the length of the wide side of the cross section of the curved waveguide 3.
As a further aspect of the present invention, the curved waveguide 3 and the waveguide slot array 4 of the cylindrical resonant cavity 1 common coplanar are disposed, the number of the slots is N =10, and the distance between the central lines of the slots is λ g 2; the line in the first slot is at a distance λ from the load termination of the waveguide g And/4, the distance between the central line of the last slot and the waveguide feed source is lambda g /2，λ g Is the waveguide wavelength.
The beneficial effects of the utility model are that:
1. the utility model has simple structure, and can change the overall superposed electric field fed into the resonant cavity by changing the size and the offset of the gap, thereby improving the uneven problem of the electric field in the cavity of the existing microwave heating equipment;
2. the utility model discloses green, quick, high efficiency, energy-conservation, environmental protection. The microwave is an electromagnetic wave which can rapidly transmit energy in situ, is a novel energy source which is easy to automatically control, is a microwave heating technology, and has the characteristics of selectivity, instantaneity, integrity, safety, environmental friendliness, energy conservation, high efficiency and the like;
3. the utility model has the advantages that the microwave feed port and the cylindrical cavity have better microwave coupling efficiency, the cavity has larger volume, the region with stronger field intensity in the resonant cavity has high concentration, uniform distribution and high cavity quality factor, namely Q value;
4. the utility model discloses can be on the basis of the cylindrical microwave heating device's of full play various advantages for the field distribution is more even in the cavity, and is more concentrated near the mode spectral line distribution of operating frequency 2.45GHz, and microwave heating's speed is faster, efficiency is higher, the cost is lower.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a diagram of an electric field intensity distribution in an XOY plane (a field intensity distribution generated by high frequency electromagnetic simulation software HFSS) when the operating frequency of the microwave source is 2.45GHz according to the embodiment of the present invention;
fig. 3 is a diagram illustrating an electric field intensity distribution in the YOZ plane (a field intensity distribution generated by the high frequency electromagnetic simulation software HFSS) when the operating frequency of the microwave source is 2.45GHz according to the embodiment of the present invention;
the respective reference numerals in fig. 1: 1-cylindrical resonant cavity body, 2-magnetron feed port, 3-curved surface waveguide and 4-waveguide slot array.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific embodiments.
Example 1: as shown in fig. 1-3, a waveguide slot array heater includes a cylindrical resonant cavity body 1, a curved waveguide 3 disposed on a side surface of the cylindrical resonant cavity body 1 and closely connected to the cylindrical resonant cavity body 1 in a closed manner, a magnetron feed port 2 disposed on an end surface of the curved waveguide 3, and a waveguide slot array 4 disposed on the curved waveguide 3 and coplanar with the cylindrical resonant cavity body 1; the curved surface waveguide 3 and the cylindrical resonant cavity body 1 are completely attached and tightly connected in a closed manner. Wherein, the radius R of the cross section of the cylindrical resonant cavity 1 is 290mm, the height H of the resonator is 300mm, the thickness of the cavity wall is 1mm, the material is an ideal metal conductor, and the middle is air; the magnetron 2 is positioned on one end face of the curved waveguide 3, the distance from the end face of the curved waveguide 3 is 1.5mm, and a 2.45GHz microwave source is generated;
as a further scheme of the utility model, the curved waveguide 3 which is arranged on the side surface of the cylindrical resonant cavity main body 1 and closely connected with the cylindrical resonant cavity main body 1 in a closed manner is completely attached to the cylindrical resonant cavity main body 1, and the curvature radius of the curved waveguide 3 is the same as that of the cylindrical resonant cavity main body 1; the transmission mode of the curved waveguide 3 is a main mode TE 10 And other higher-order modes are cut off, so the requirements on the section size of the curved waveguide 3, the length a of the wide side of the cross section and the length b of the narrow side of the cross section are as follows: b<a/2。
Specifically, the curved waveguide 3 is obtained by optimizing the waveguide size on the basis of a standard BJ26 waveguide, the final length of the cavity on the wide side of the curved waveguide 3 is a =86.4mm, the length of the cavity on the narrow side is b =30.5mm, the thickness is 1mm, the curved waveguide 3 is completely attached and tightly connected with the cylindrical resonant cavity 1, the curvature radius of the common surface of the curved waveguide is the cross section radius R =290mm of the cylindrical resonant cavity 1, the total length of the curved waveguide 3 is half of the circumference of the cylindrical resonant cavity 1, the curved waveguide is made of an ideal metal conductor and is arranged in a hollow manner;
as a further aspect of the present invention, the curved waveguide 3 disposed on the side of the cylindrical cavity body 1 and closely connected to the cylindrical cavity body 1 in a closed manner is a master mode TE as the transmission mode of the curved waveguide 3 10 Transmission frequency f =2.45GHz, wavelength λ in free space, waveguide wavelength λ g Wherein the relationship between the waveguide wavelength and the wavelength in free space is:
a is the length of the wide side of the cross section of the curved waveguide 3.
As a further aspect of the present invention, the waveguide gap array 4 disposed on the common and coplanar surface of the curved waveguide 3 and the cylindrical resonant cavity main body 1 has a gap number of N =10, and the distance between the gap center lines is λ g 2; the line in the first slot is at a distance λ from the load termination of the waveguide g 4, the distance between the central line of the last slot and the waveguide feed source is lambda g /2，λ g Is the waveguide wavelength.
As a further aspect of the present invention, the waveguide slot array 4 can adopt a curved-surface wide-edge waveguide slot array, and the detailed process of its design can be as follows:
1) Firstly, determining the form, the number of gaps and the initial model preliminary size of a gap array according to given performance and practical application requirements;
firstly, determining the form of the slot array as a curved-surface wide-edge waveguide slot array according to given performance and practical application requirements, numbering the slot array 4 from the end face of the magnetron 2 as 4_1 to 4 \u10, the number of slots N =10, and the initial size: the initial spacing d between the slot centre lines is λ g (/ 2) =86.7mm, the distance of the line in the first slot from the load termination of the waveguide is λ g /4=43.35mm, the distance between the line in the last slot and the waveguide feed is λ g (/ 2=86.7 mm), the initial length L1=86.4mm of the slit, the initial width W =10mm of the slit;
2) Carrying out Taylor distribution comprehensive design on the array elements according to the requirement of selecting the side lobe level, and calculating the excitation level distribution amplitude of each gap;
setting the side lobe ratio of the slit array to be-40 dB, and finally obtaining the distribution amplitudes of the excitation levels of 10 slits by using a Taylor comprehensive distribution method, wherein the distribution amplitudes are respectively as follows: u1=1.8914, U2=1.4461, U3=0.8151, U4=0.3039, U5=0.0876, U6=0.0876, U7=0.3039, U8=0.8151, U9=1.4461, U10=1.8914;
3) Determining gap bias according to the conductance value determined by the excitation distribution;
3.1, normalizing the excitation level distribution amplitude of each gap:
calculating to obtain a parameter K value;
3.2, g is equivalent conductance m ＝KU m Calculating the equivalent conductance g of the mth gap m ；
3.3 according to equivalent conductance g m And the gap offset X:
calculating to obtain the initial offset of the slot array; wherein a is the cross-sectional broadside length, g ', of the curved waveguide (3)' 1 ＝2.09aλ g cos 2 (πλ/2λ g ) B is the length of the narrow side of the cross section of the curved waveguide (3), λ is the wavelength in free space, λ b is the length of the narrow side of the cross section of the curved waveguide g Is the waveguide wavelength;
offset X of initial slot array 1 ＝0.3956，X 2 ＝-1.3731，X 3 ＝3.6924，X 4 ＝-6.5941，X 5 ＝-8.6859，X 6 ＝-8.6859，X 7 ＝6.5941，X 8 ＝-3.6924，X 9 ＝1.3731，X 10 = 0.3956 in mm;
4) And obtaining the length of the gap by utilizing the optimization function of the HFSS, simulating and optimizing the initial model, and determining a final model.
Adjusting the offset of the slot array to be x1=0.4mm, x2= -1.4mm, x3=3.7mm, x4= -6.6mm, x5= -8.7mm, x6= -8.7mm, x7= -6.6mm, x8= -3.7mm, x9= -1.4mm, x10= -0.4mm according to the offset of the initial slot array; the length L2=58mm of the optimized slot, and the final simulation result shows that the return loss of the slot waveguide array is-10.68 dB, the electric field distribution in the resonant cavity is uniform, and the requirement of microwave heating can be basically met.
In the embodiment, a microwave source with the working frequency of 2.45GHz and the working wavelength of 122.4mm feeds microwave energy into the curved waveguide 3 through a microwave transmission system, namely a magnetron feed port 2, standing waves are formed in the curved waveguide 3, and the microwave energy is fed into the cylindrical resonant cavity 1 through the slot array 4 to heat an object. The microwave heating device designed based on the Taylor comprehensive distribution method can change the electric field distribution in the cylindrical resonant cavity by setting a proper gap position and bias, thereby realizing the temperature control of microwave heating.
Fig. 1 is a schematic structural diagram of a waveguide slot array heater according to the present invention; fig. 2 and 3 are field patterns formed inside the resonant cavity on the XOY plane and the YOZ plane after HFSS operation by using high-frequency electromagnetic simulation software;
the utility model relates to an utilize waveguide gap array to realize the heating of material in the cylindrical resonant cavity 1 as the feed, avoided the hotspot problem that the energy feed-in resonant cavity produced because of the magnetron high power, can feed in the electric field range of intracavity through every gap of size control that changes every gap again, and then improve the homogeneity problem of electric field in the resonant cavity.
While the present invention has been particularly shown and described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims (5)
1. A waveguide slot array heater, comprising: the magnetron type microwave oven comprises a cylindrical resonant cavity body (1), a curved surface waveguide (3) which is arranged on the side surface of the cylindrical resonant cavity body (1) and is in close connection with the cylindrical resonant cavity body (1) in a closed manner, a magnetron feed opening (2) which is arranged on one end surface of the curved surface waveguide (3), and a waveguide slot array (4) which is arranged on the curved surface waveguide (3) and is coplanar with the cylindrical resonant cavity body (1); the curved surface waveguide (3) and the cylindrical resonant cavity body (1) are completely attached, closed and tightly connected together.
2. The waveguide slot array heater of claim 1, wherein: the curved surface waveguide (3) which is arranged on the side surface of the cylindrical resonant cavity body (1) and is closely connected with the cylindrical resonant cavity body (1) in a closed way is arranged on the curved surface waveguideThe curved waveguide is completely attached to the cylindrical resonant cavity body (1), and the curvature radius of the curved waveguide (3) is the same as that of the cylindrical resonant cavity body (1); the transmission mode of the curved waveguide (3) is a main mode TE 10 And other higher-order modes are cut off, so the requirements on the section size of the curved surface waveguide (3), the length a of the wide side of the cross section and the length b of the narrow side of the cross section are as follows: b<a/2。
3. The waveguide slot array heater of claim 1, wherein: the cross section of the curved waveguide (3) is 86.4mm x 30.5mm.
4. The waveguide slot array heater of claim 1, wherein: the curved surface waveguide (3) is arranged on the side surface of the cylindrical resonant cavity main body (1) and is closely connected with the cylindrical resonant cavity main body (1) in a closed mode, and the transmission mode of the curved surface waveguide (3) is a main mode TE 10 Transmission frequency f =2.45GHz, wavelength λ in free space, waveguide wavelength λ g Wherein the relationship between the waveguide wavelength and the wavelength in free space is:
a is the length of the wide side of the cross section of the curved waveguide (3).
5. The waveguide slot array heater of claim 1, wherein: the waveguide slot array (4) arranged on the common plane of the curved surface waveguide (3) and the cylindrical resonant cavity body (1) has the slot number of N =10, and the distance between the slot central lines is lambda g 2; the line in the first slot is at a distance λ from the load termination of the waveguide g And/4, the distance between the central line of the last slot and the waveguide feed source is lambda g /2，λ g Is the waveguide wavelength.
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| CN202123423229.0U CN217591139U (en) | 2021-12-31 | 2021-12-31 | Waveguide slot array heater |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115665914A (en) * | 2022-12-22 | 2023-01-31 | 河北科技大学 | Multi-source microwave heating device |
| CN115978785A (en) * | 2022-12-19 | 2023-04-18 | 四川大学 | Coaxial slotted radiator, continuous flow liquid heating system and heating method |
-
2021
- 2021-12-31 CN CN202123423229.0U patent/CN217591139U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115978785A (en) * | 2022-12-19 | 2023-04-18 | 四川大学 | Coaxial slotted radiator, continuous flow liquid heating system and heating method |
| CN115978785B (en) * | 2022-12-19 | 2024-03-19 | 四川大学 | Coaxial slotting radiator, continuous flow liquid heating system and heating method |
| CN115665914A (en) * | 2022-12-22 | 2023-01-31 | 河北科技大学 | Multi-source microwave heating device |
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