CN111432514A

CN111432514A - Modular periodic loading microwave heating equipment

Info

Publication number: CN111432514A
Application number: CN202010208409.8A
Authority: CN
Inventors: 王清源
Original assignee: Chengdu Saina Microwave Technology Co ltd
Current assignee: Chengdu Saina Microwave Technology Co ltd
Priority date: 2020-03-23
Filing date: 2020-03-23
Publication date: 2020-07-17

Abstract

The invention provides a modularized periodic loading microwave heating device which comprises a plurality of feed-in modules, a loading module, a flat plate module and a side plate module. The loading body arranged on the loading module forms a two-dimensional array structure, and the broadband band-stop characteristic is realized near the working frequency in a channel, so that the isolation among different feed-in transmission lines is realized, and the heating efficiency can be greatly improved by matching each feed-in transmission line through the tuner. Through set up along the Z direction along X direction staggered multirow feed-in transmission line in proper order, realize the homogeneity of horizontal heating. At a certain working frequency, the modules can be used as standard parts to be produced in batches at low cost by adopting a die-sinking casting mode, and microwave heating equipment with various specifications can be assembled by splicing. The microwave heating device can realize microwave heating equipment with various functions and high cost performance, and is widely used for various heating, in particular to high-temperature and high-efficiency heating of low-humidity and low-absorption materials.

Description

Modular periodic loading microwave heating equipment

Technical Field

The invention relates to the field of low-cost uniform microwave heating, in particular to modular periodic loading microwave heating equipment.

Background

Microwave energy heating may be used in place of various conventional heating means. The microwave heating device heats various non-metallic materials including but not limited to wood, grains, seeds, herbs, spices, dairy products, etc. by using microwave energy. In the field of microwave chemistry, microwave energy is used to accelerate various chemical reactions. Microwave energy is also used in the production of new materials such as nanomaterials, synthetic diamonds, and the like.

In the traditional heating, because heat is conducted to the inside of the heated material through the outside, the surface heating is adopted, and the temperature inside and outside the heated material is not uniform. The microwave energy heating is characterized in that damping vibration of polar molecules in a heated material generates heat due to interaction between microwaves and the heated material, and belongs to body heating, wherein the heated material is heated inside and outside simultaneously. Thus, microwave energy heating may achieve more uniform heating.

However, in any cavity such as a heating cavity, electromagnetic waves will exist as resonant standing waves in the various natural modes of the cavity, resulting in the electric field being at a maximum magnitude at certain fixed locations in space and at a small magnitude at other fixed locations. The distance between these electric field concentrations is about half the operating wavelength of the microwaves. Thus, at a typical microwave energy application frequency of 2450MHz, the material being heated is very non-uniform on the order of 62 millimeters.

The size of a heating cavity of a common microwave oven is 3-5 times of the working wavelength. The size of a large heating cavity in the industrial microwave heating equipment is 20-300 times of the working wavelength. The number of resonant modes that can be excited in these heating cavities at a certain operating frequency is several to several hundred. Any superposition of numerous resonant modes may produce a much greater electric field strength at some locations of the heating chamber than at others, severely disrupting the uniformity of heating. Technical personnel in international and domestic fields make continuous efforts to solve the problem of uniformity of microwave energy heating. Attempts have been made to improve the uniformity of heating by increasing the number of microwave feeds, changing the shape of the feeds, changing the position of the microwave feeds on the external surface of the heating chamber, or changing the direction of polarization of the electric field in the microwave feeds, or both. However, to date, due to the high complexity of the microwave heating uniformity problem, the entire microwave world has been short of theoretical work in this field, and three-dimensional electromagnetic simulation is difficult to accomplish due to the large amount of computation. Therefore, the problem of uniformity of heating in microwave ovens, especially large microwave heating devices, has not been well solved.

Due to cost considerations, expensive high power solid state sources have only found small-scale, attempted use in certain high value-added microwave heating devices, and the primary microwave source in microwave energy applications remains the magnetron. At present, the market price of a single magnetron and a power supply thereof with the output power of about 1kW is about one thousand yuan at the frequency of 2450MHz, and the market price of a single magnetron in the same frequency band with the power of 10kW is about 5 ten thousand yuan. At 915MHz, the typical output power of a single magnetron is 75kW, and the market price of the whole set of energy system is about 100 ten thousand yuan. Therefore, a small magnetron is a significant advantage in terms of cost per unit power.

However, large microwave heating equipment typically requires a small magnetron of tens to hundreds of 1kW power. The application of a plurality of magnetrons to a large-sized microwave heating apparatus has a problem of low heating efficiency in addition to the aforementioned problem of poor uniformity. Since the microwaves are independent and independent from each other, at the feed-in port of a magnetron to the heating device, the energy generated by all other magnetrons may "back-fill" the magnetron through the heating cavity of the heating device and the feed-in port. Not only is this energy underutilized, but it can severely affect the operation of the magnetron and even burn it out. The low energy efficiency of microwave heating and damage to the magnetron are another significant problem in the current common microwave energy application equipment in addition to poor heating uniformity. This problem is even more pronounced in the heating of low loss, low moisture materials.

The volume of general industrial microwave heating equipment, especially industrial large-scale microwave heating equipment is relatively large, and large-scale processing equipment is required for manufacturing the industrial microwave heating equipment. Therefore, the manufacturing cost of the existing industrial microwave heating equipment is generally high, and the wide application of microwave energy in various industrial industries is further limited.

Disclosure of Invention

The invention aims to provide a modular periodic loading microwave heating device. In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a modular periodic loading microwave heating device comprises at least one feed-in module and at least one loading module; the feed-in module comprises at least one feed-in transmission line and at least one feed-in flat plate; the feed-in transmission line penetrates through the feed-in flat plate; the loading module comprises at least one loading flat plate, at least 3 columns and at least 3 rows of loading carriers, wherein the loading flat plate is arranged along the X direction and the Z direction; the loading body is contacted with the loading flat plate only in the Y direction or in the-Y direction; all the materials of the feed plate, the loading plate and the loading body are metal. The addition of carriers can be as many as 100 columns to 10000 rows, depending on the application.

Generally, the feeding transmission line is a rectangular waveguide in which the operation mode is TE10 mode, and the electric field direction of the microwave in the rectangular waveguide is parallel to the X direction. The design ensures that the microwave electric field fed into the modular periodically-loaded microwave heating equipment is uniformly distributed in the X direction near each feed opening. This arrangement is one of the keys to achieving uniform heating of the entire modular periodically loaded microwave heating apparatus.

The feed transmission line may also be a coaxial line or other type of transmission line, but a rectangular waveguide is the preferred choice for the feed transmission line in terms of heating uniformity.

In some cases, such as when the power of a microwave source is too large, it is desirable to properly reduce the power density at the feed port of the feed transmission line, a power divider is disposed between at least one of the feed plates and the feed transmission line; the power divider is a two-path power divider or a multi-path power divider. The more the number of the paths of the power divider is, the smaller the power density at the feed port is, and the larger the effective heating area of the microwave input by one feed transmission line on the XZ plane is.

In order to realize a wider bandwidth stop band near the operating frequency of the modular periodically-loaded microwave heating device and prevent microwave from propagating in the modular periodically-loaded microwave heating device, the distance between the axes of the loading bodies adjacent to each other in the X direction and the Z direction is 0.15-0.35 times of the operating wavelength. Meanwhile, the height of the loading body in the Y direction is 0.15-0.35 times of the working wavelength.

The loading body is a cylinder with the axis parallel to the Y direction and the cross section of the cylinder is circular or regular polygon; the number of sides of the regular polygon is greater than or equal to 3. Among them, a cylindrical body and a square cylindrical body are preferable.

Meanwhile, a groove can be arranged in the loading flat plate near the bottom end of the loading body; the groove 4B surrounds the loading body. Further, a loading head can be arranged at the top end of the loading body; the projection of the loading head in the Y direction comprises the projection of the loading body connected with the loading head in the Y direction; the material of the loading head is metal.

The modular periodically-loaded microwave heating apparatus may further comprise at least one flat-plate die; the flat plate module is a rectangular metal plate with a certain thickness.

In order to construct the tunnel type microwave heating furnace, the modularized periodic loading microwave heating equipment further comprises at least two side plate modules positioned in the X direction and the-X direction; the side plate module is connected with the feed-in module, the loading module or the flat plate module in the Y direction or the-Y direction. And the feeding modules, the loading modules, the flat plate modules and the side plate modules are spliced with one another to form the tunnel type microwave heating equipment which is closed up, down, left and right.

Sometimes, we also provide a loading body on the feeding module, so that the height of the channel of the modular periodically loaded microwave heating device can be increased: the feed module also comprises at least 20 loading bodies; the loading bodies are in contact with the feed plate only in the Y direction or in the-Y direction.

In order to realize the tunnel type microwave heating furnace, a channel is also arranged in the modularized periodic loading microwave heating equipment, and a heated material is arranged in the channel.

When we use a plurality of feeding modules to feed microwave energy into the heating device, the rows of feeding modules arranged in sequence along the Z direction need to be staggered in sequence by the same distance in the X direction. This arrangement results in a significant reduction in mutual coupling between the feed transmission lines of adjacent feed modules due to the band-stop effect of the two-dimensional additive carriers. The lower mutual coupling enables each feed-in transmission line to be independently allocated through the allocator, thereby greatly improving the heating efficiency of the microwaves in each microwave source.

In order to ensure that the microwave field in the channel in the vicinity of each feed transmission line is confined to the vicinity of the feed and is as uniform as possible in the X direction, the height of the channel in the Y direction is less than 0.5 times the operating wavelength. Since higher order modes are excited in the higher channels and disrupt the uniformity of the microwave field in the channels.

The volume of general microwave heating equipment, especially industrial large-scale microwave heating equipment is large, large-scale processing equipment is needed for processing, and the processing cost is high. In order to reduce the processing difficulty and the processing cost, the heating equipment can be disassembled into a plurality of modules which are respectively assembled after being processed. These modules mainly comprise: the device comprises a feed-in module, a loading module, a flat plate module and a side plate module. Wherein the feed module and the flat former are generally disposed in an upper position; the loading module is generally arranged at a lower position; the side panel modules are typically placed on the left and right. All the modules can be positioned and spliced by positioning pins and then tightened by a plurality of connecting screws to form a complete modularized periodic loading microwave heating device.

The invention provides a modularized periodic loading microwave heating device. The heating device is formed by splicing a plurality of modules. At a certain operating frequency, these modules can be mass produced as standard parts. According to different applications, different numbers of the modules can be conveniently selected to form modular periodically-loaded microwave heating equipment with different widths and different lengths. The sizes of the standard parts are much smaller than the size of equipment, and the standard parts can be processed by a numerical control milling machine and can also be processed by adopting a die-sinking casting mode so as to further greatly reduce the manufacturing cost.

Drawings

Fig. 1 is a schematic top view of the present invention and example 1.

Fig. 2 is a cross-sectional view in the direction AA of fig. 1.

Fig. 3 is a schematic top view of embodiment 2.

Fig. 4 is a cross-sectional view in the direction AA of fig. 3.

FIG. 5 is a schematic top view of embodiment 3.

Fig. 6 is a cross-sectional view in the direction AA of fig. 5.

FIG. 7 is a schematic top view of embodiment 4.

Fig. 8 is a cross-sectional view in the direction AA of fig. 7.

FIG. 9 is a schematic top view of example 5.

Fig. 10 is a cross-sectional view in the direction AA of fig. 9.

FIG. 11 is a schematic top view of example 6.

Fig. 12 is a cross-sectional view in the direction AA of fig. 11.

FIG. 13 is a schematic top view of example 7.

Fig. 14 is a cross-sectional view in the direction AA of fig. 13.

FIG. 15 is a schematic top view of example 8.

Fig. 16 is a cross-sectional view in the direction AA of fig. 15.

FIG. 17 is a schematic top view of example 9.

Fig. 18 is a cross-sectional view in the direction AA of fig. 17.

Fig. 19 is the energy leakage coefficient (dB) of the four sides of example 9.

FIG. 20 is a schematic top view of the preferred embodiment 10.

Fig. 21 is a cross-sectional view in the direction AA of fig. 20.

Fig. 22 is an energy leakage coefficient (dB) of four sides of example 10.

FIG. 23 is a schematic top view of example 11.

Fig. 24 is a cross-sectional view in the direction AA of fig. 23.

Fig. 25 is the energy leakage coefficient (dB) of the four sides of example 11.

Description of the reference numerals

The reference numbers in the drawings correspond to the names: 1-feeding module, 11-feeding transmission line, 12-feeding plate, 13-power divider, 2-loading module, 21-loading plate, 22-loading carrier, 23-loading head, 24-groove, 3-plate module, 4-side plate module, 5-channel, 6-heated material.

Some of the terms (see FIGS. 1-2) in this specification are defined as follows:

horizontal, i.e. any plane parallel to the XZ plane.

Upward, i.e., Y-direction, i.e., vertically upward from the horizontal.

The lower, i.e. -Y direction, i.e. the direction vertically downwards from the horizontal.

Left direction, refers to the X direction.

The right direction refers to the-X direction.

The bottom end of the loading body, i.e. the end of the loading body which is connected to the cover plate or the base plate.

The top end of the loading body, i.e. the end of the loading body remote from the top end thereof.

The working wavelength is the wavelength in the air corresponding to the working frequency of the microwave source of the microwave heating equipment.

And (4) row: a plurality of targets having the same Z-direction position arrayed in the X-direction constitute one row.

The method comprises the following steps: a plurality of targets having the same X-direction position arrayed in the Z-direction constitute one column.

Feeding: any feed transmission line 11 interfaces with any flat metal plate.

Detailed Description

Example 1

As shown in fig. 1 and 2.

A modular periodic loading microwave heating device comprises 5 rows of 25 feeding modules 1 with standard size at the upper part and 7 rows of 8 rows of 56 loading modules 2 with standard size at the lower part; the feed-in module 1 comprises a feed-in transmission line 11 and a feed-in flat plate 12; the feed transmission line 11 passes through the feed plate 12; the loading module 2 comprises a loading

flat plate

21, 7 columns of loading bodies 22 along the X direction and 7 rows of loading bodies along the Z direction; the loading body 22 contacts the loading plate 21 only in the-Y direction; all the materials of the loading plate 21, the loading body 22 and the feeding plate 12 are metals. All the standard-sized feeder modules 1 have the same structure. The construction of all the standard-sized loading modules 2 is also the same.

The modular periodic loading microwave heating equipment also comprises 8 standard-size flat plate modules 3 which are positioned in the 1 st row and the 7 th row along the Z direction, 2 standard-size flat plate modules 3 which are positioned on the two sides of the 2 nd row, and 18 standard-size flat plate modules 3 in total. These standard size flat modules 3 are of the same size. Meanwhile, the flat plate module 3 with 8 nonstandard sizes is also provided on the left side and the right side, wherein the sizes of the flat plate module are 4 different.

The modularized periodic loading microwave heating equipment also comprises 14 side plate modules 4 with standard sizes in the X direction and the-X direction; the side plate module 4 is connected with the flat plate module 3 in the Y direction and connected with the loading module 2 in the-Y direction. All standard size side panel modules 4 are of the same size. The feeding modules 1, the loading modules 2, the flat plate modules 3 and the side plate modules 4 are spliced with one another to form tunnel type microwave heating equipment which is closed up and down, left and right.

The loading bodies 22 are all cylinders with axes parallel to the Y direction.

The distance between the axes of the loading bodies 22 adjacent to each other in the X direction and the Z direction is 0.15-0.35 times of the working wavelength. Meanwhile, the height of the loading body 22 in the Y direction is 0.15-0.35 times of the working wavelength.

The feed transmission lines 11 are all rectangular waveguides, and the operating mode thereof is TE10 mode. The electric field direction of the microwaves in the rectangular waveguide is parallel to the X direction.

A channel 5 is provided in the modular cyclically loaded microwave heating apparatus, and a material 6 to be heated is provided in the channel 5.

As shown in fig. 1, a plurality of feed modules 1 are used to feed microwave energy into the heating apparatus. Each feed transmission line 11 is a rectangular waveguide with the broad side in the Z-direction and the narrow side in the X-direction, the narrow side having a dimension 2 times the dimension of the broad side. The side length of each of the standard-sized feeder module 1 and the standard-sized loading module 2 in the horizontal plane is 5 times larger than the narrow side of the rectangular waveguide. 5 rows of feed-in modules 1 which are sequentially arranged along the Z direction are sequentially staggered in the X direction by the same distance as the size of the narrow side of the rectangular waveguide. This arrangement results in a significant reduction of mutual coupling between the feed transmission lines 11 of adjacent feed modules 1 in any direction due to the band-stop effect of the two-dimensional additive carriers 22. The lower mutual coupling enables each feeding transmission line 11 to be independently allocated through the allocator, and greatly improves the utilization efficiency of the microwaves in each microwave source. This arrangement also ensures that the heated material 6 at different X-direction positions is heated by the microwaves fed from one feeding transmission line 11 of the first row to the 7 th row while the heated material 6 moves in the Z-direction in the passage 5, and the uniformity of heating is ensured in the X-direction. Meanwhile, as the heated materials 6 move along the Z direction, the heated materials 6 at the same X position but different Z-direction positions are heated by the microwaves fed by the same feed transmission line 11 from the first row to the 7 th row, and the heating uniformity is also ensured in the Z direction. Therefore, the heating uniformity of the heating apparatus in the XZ plane is significantly improved.

In order to ensure that the microwave field in the channel 5 in the vicinity of each feed transmission line 11 is confined to the vicinity of the feed and is as uniform as possible in the XZ plane, the height of the channel 5 in the Y direction is less than 0.5 times the operating wavelength.

Example 2

As shown in fig. 3 and 4.

Embodiment 2 is a feed-in module 1. The feed-in module 1 comprises a feed-in transmission line 11 and a feed-in flat plate 12; the feed transmission line 11 passes through the feed plate 12; the feed transmission line 11 is a rectangular waveguide; the operating mode is TE10 mode. The electric field direction of the microwaves in the rectangular waveguide is parallel to the X direction.

Example 3

As shown in fig. 5 and 6.

Embodiment 3 differs from embodiment 2 only in that we have 7 rows and 7 columns of loading bodies 22 arranged below the feeding plate 12 of the feeding module 1; the loading bodies 22 are in contact with the feed plate 12 only in the Y direction. The feed transmission line 11 passes through the feed plate 12 and has a lower end flush with the lower end of the loading body 22. In order to prevent the loading bodies 22 from interfering with the microwave field near the lower end of the feed transmission line 11, a total of 9 loading bodies 22 of 3 rows and 3 columns near the feed transmission line 11 are removed. Therefore, only 40 loading bodies 22 are arranged on the feed-in module 1.

Example 4

As shown in fig. 7 and 8.

Embodiment 4 is a loading module 2, the loading module 2 comprising a

loading plate

21, 7 columns in the X direction and 7 rows of loading bodies 22 in the Z direction; the loading body 22 contacts the loading plate 21 only in the-Y direction; all the materials of the loading plate 21, the loading body 22 and the feeding plate 12 are metals.

The loading body 22 is a cylinder with an axis parallel to the Y direction.

A groove 24 is provided in the loading plate 21 near the bottom end of each of the loading bodies 22; the groove 24 is disposed around the loading body 22 and has a hollow circular tube shape.

A loading head 23 is arranged at the top end of each loading body 22; the projection of the loading head 23 in the Y direction includes the projection of the loading body 22 connected thereto in the Y direction; the loading head 23 is made of metal and is in the shape of a metal round pipe. The inner diameter of the metal cylinder is the same as the outer diameter of the cylinder plus carrier 22.

Example 5

As shown in fig. 9 and 10.

Example 5 differs from example 4 only in that no recess 24 is provided.

Example 6

As shown in fig. 11 and as shown in fig. 12.

Embodiment 6 differs from embodiment 4 only in that no loading head 23 is provided.

Example 7

As shown in fig. 13 and 14.

Embodiment 7 differs from embodiment 4 only in that neither any loading head 23 nor any groove 24 is provided.

Example 8

As shown in fig. 15 and 16.

A modular periodic loading microwave heating device comprises a feed-in module 1 and a loading module 2; the feed-in module 1 comprises a feed-in transmission line 11 and a feed-in flat plate 12; the feed transmission line 11 is a rectangular waveguide; a two-way E-plane waveguide power divider is disposed between the rectangular waveguide feed transmission line 11 and the feed plate 12.

The loading module 2 comprises a loading

flat plate

21, 7 columns of loading bodies 22 in the X direction and 8 rows of loading bodies in the Z direction; the loading body 22 contacts the loading plate 21 only in the-Y direction; all the materials of the loading plate 21, the loading body 22 and the feeding plate 12 are metals.

The loading body 22 is a cylinder with an axis parallel to the Y direction.

The feed transmission line 11 is a rectangular waveguide; the operating mode is TE10 mode. The electric field direction of the microwaves in the rectangular waveguide is parallel to the X direction.

In order to facilitate the realization of the tunnel type microwave heating furnace, a channel 5 is arranged in the modularized periodic loading microwave heating device, and a heated material 6 is arranged in the channel 5.

The modular cycle-loading microwave heating apparatus is not provided with any side panel modules 4. The feeder module 1 may be fixed above the loading module 2 by a suspension device. This configuration allows the apparatus to be used for locally heating a quantity of the heated material 6 in the form of a sheet. The dimensions of the plate-like material in the X-direction and the Z-direction may be much larger than the dimensions of the loading module 2 in the same direction. One possibility is to first place the heated material 6 in the channel 5 between the feed module 1 and the loading module 2, to have the heated area of the heated material 6 directly below the feed transmission line 11, to turn on the microwave source and to deliver microwave energy to the heated material 6 through the feed transmission line 11. After the heating process is completed, the microwave source is turned off and the heated material 6 is removed.

In order to reduce the leakage of microwave energy to below a certain level through the four lateral sides in the front, rear, left and right directions when no sideboard module 4 is provided, the dimensions of the feeder module 1 and the loading module 2 in the XZ plane need to be increased accordingly, the spacing between the loading bodies 22 remains unchanged, but the number of loading bodies 22 needs to be increased. Such as increasing the number of carriers added to 21 rows 21 or more.

Example 9

As shown in fig. 17 to 19.

Example 9 differs from example 8 only in that, without providing any heated material 6, a groove 24 is provided in the loading flat plate 21 in the vicinity of the bottom end of each of the load bodies 22; the groove 24 is a hollow circular tube surrounding the loading body 22.

The specific structure size is as follows: the loading body 22 is a metal column with a diameter of 15.39 mm and a length of 21.82 mm. The distance between the axes of adjacent metal posts in the X-direction and in the Z-direction was 37.5 mm. The height of the channel 5 is 20 mm. The inner diameter of the groove 24 corresponds to the diameter of the loading body 22, and the width of the annular groove 24 in the radial direction is 4.51 mm and the depth thereof is 12.94 mm.

Fig. 19 is a graph of energy leakage coefficient (dB) with frequency for four sides of example 9 calculated by three-dimensional simulation. In the simulation calculation, microwave energy is fed from a rectangular waveguide into the transmission line 11 into the channel 5. The four sides of the channel 5 are all arranged to match the boundary conditions. All microwaves arriving from the feed transmission line 11 through the channel 5 to either side will be completely absorbed. The energy leakage coefficient curve will give how much microwave power entering the channel 5 from the feed transmission line 11 can propagate to the side and be absorbed over a range of frequencies.

It can be seen from fig. 19 that in the 2.1 GHz-3.1 GHz band, only about 1% of the energy of the microwaves entering the channel 5 can propagate along the channel to the side thereof. However, at many frequency points outside the above-mentioned frequency band, most of the energy will pass through the channel 5 to its side.

Example 10

As shown in fig. 20 to 22.

Example 10 is substantially the same in structure as example 9, except that: no recess 24 is provided. A heated material 6 is disposed in the channel 5.

The specific parameters are as follows: the loading body 22 was a metal column having a diameter of 10.04 mm and a length of 19.25 mm, and the distance between the axes of the adjacent metal columns in the X direction and in the Z direction was 24.51 mm. The height of the channel 5 is 20 mm. The heated material 6 had a dielectric constant of 9, a thickness of 5 mm in the Y direction, and a distance of 5 mm from the upper surface of the channel 5.

FIG. 22 is a graph of the energy leakage coefficient (dB) with frequency for four sides of example 10 calculated by three-dimensional simulation. It can be seen from fig. 22 that at many frequency points outside the 2.3GHz to 2.65GHz bandwidth, most of the energy will pass through the channels 5 to the sides. But in the 2.3 GHz-2.65 GHz band, only about 4% of the energy of the microwaves entering the channel 5 can propagate along the channel 5. Most of the microwave energy will be concentrated near the feed and heat the material 6 being heated, or reflected along the feed transmission line 11. If a coordinator is provided in the feed transmission line 11, it is possible to have almost all of the microwave energy used to heat the material 6 being heated. The absorption effect of the heated material 6 is not taken into account in the calculation. But taking this absorption effect into account, the energy leakage coefficient of the four sides will be further reduced due to the absorption of microwave energy.

Example 11

As shown in fig. 23 to 25.

Embodiment 11 is similar to embodiment 10, with the main difference that 7 rows and 7 columns of loading bodies 22 are arranged below the feeding plate 12 of the feeding module 1; the loading bodies 22 are in contact with the feed plate 12 only in the Y direction. The feed transmission line 11 passes through the feed plate 12 and has a lower end flush with the lower end of the loading body 22. In order to prevent the interference of the loading bodies 22 with the microwave field near the lower end of the feed transmission line 11, a total of 9 loading bodies 22 of 3 rows and 3 columns near the feed transmission line 11 are removed. Therefore, only 40 loading bodies 22 are arranged on the feed-in module 1.

Here, the loading body 22 is a metal column with a diameter of 14.3 mm and a length of 28.21 mm. The distance between the axes of adjacent metal posts in the X-direction and in the Z-direction was 29.98 mm. The height of the channel 5 is increased to 40 mm. The material 6 to be heated had a dielectric constant of 9 and a thickness of 10 mm, and its upper surface was spaced 5 mm from the upper surface of the channel 5.

FIG. 25 is a graph of the energy leakage coefficient (dB) with frequency for four sides of example 11 calculated by three-dimensional simulation. It can be seen from fig. 23 that at many frequency points outside the 2.2GHz to 2.8GHz bandwidth, most of the energy will pass through the channels 5 to the sides. But in the 2.2 GHz-2.8 GHz band, only about 4% of the energy of the microwaves entering the channel 5 can propagate along the channel 5. Most of the microwave energy will be concentrated near the feed and heat the material 6 being heated, or reflected along the feed transmission line 11. If a coordinator is provided in the feed line 11, it is possible to have almost all of the microwave energy used to heat the material 6 being heated.

Compared with embodiment 10, the structure of the apparatus is more complicated by providing the loading bodies 22 at the same time in the feeding module 1 and the loading module 2, respectively. However, the height of the channel 5 is doubled, and this structure can be used to heat a relatively thick material 6 to be heated.

The foregoing illustrates some embodiments of the invention. The actual implementation is far more extensive than listed here. The microwave heating equipment is generally processed by a numerical control milling machine. To facilitate the realization of the microwave heating apparatus, the inner corners of some portions thereof need to be chamfered. Such a chamfer must be incorporated into the modeling calculation. The specific design of each implementation mode needs specific calculation according to microwave transmission line theory, mode matching theory and the like. The invention provides a modularized periodic loading microwave heating device. The modular periodic loading microwave heating equipment has the advantages of simple structure and uniform heating. Since the dielectric parameters of the heated material (which depend primarily on the type, humidity and temperature of the material) are determined near the feed of one feed transmission line, and there is good isolation between the different feed transmission lines, we can adjust the tuner so that the microwaves output by each microwave source are fully absorbed. Therefore, the energy of each microwave source can be fully used for heating the heated material, and the energy efficiency of the heating device is remarkably improved. The modularized periodic loading microwave heating equipment can be assembled by splicing a plurality of standard modules according to different purposes, and the standard modules can be manufactured at low cost by die sinking casting. Therefore, the microwave heating device can realize microwave heating equipment with various functions and low cost, and can be widely used for heating and drying various materials, particularly low-cost, high-temperature and high-efficiency heating of low-humidity and low-absorption materials.

Claims

1. A modular periodically loaded microwave heating device, characterized by comprising at least one feed-in module (1) and at least one loading module (2); the feed-in module (1) comprises at least one feed-in transmission line (11) and at least one feed-in flat plate (12); the feed transmission line (11) passes through the feed flat plate (12); the loading module (2) comprises at least one loading flat plate (21), at least 3 columns and at least 3 rows of loading carriers (22) which are arranged along the X direction and the Z direction; the loading body (22) is in contact with the loading plate (21) only in the Y direction or in the-Y direction; all the materials of the loading flat plate (21), the loading body (22) and the feeding flat plate (12) are metal; x, Y and the Z direction form a rectangular coordinate system.

2. A modular periodically loaded microwave heating device according to claim 1, characterized in that said feeding transmission line (11) is a rectangular waveguide; the working mode of the rectangular waveguide is a TE10 mode; the electric field direction of the microwaves in the rectangular waveguide is parallel to the X direction.

3. A modular periodically loaded microwave heating device according to claim 1, characterized in that a power divider (13) is arranged between at least one of said feeding plates (12) and said feeding transmission line (11); the power divider (13) is a two-path power divider or a multi-path power divider.

4. A modular periodically-loaded microwave heating apparatus as in claim 1, wherein said loading body (22) is a cylinder having a cross-section parallel to the axis in the Y-direction which is circular or regular polygonal; the number of sides of the regular polygon is more than or equal to 3.

5. A modular periodically loaded microwave heating apparatus according to claim 1, characterized in that the spacing between the axes of adjacent load carriers (22) in the X-direction and in the Z-direction is 0.15 to 0.35 times the operating wavelength.

6. A modular periodically loaded microwave heating device according to any of claims 1 to 5, characterized in that a recess (24) is provided in the loading plate (21) near the bottom end of the loading body (22); the groove 24 surrounds the loading body (22); or a loading head (23) is arranged at the top end of the loading body (22); the projection of the loading head (23) in the Y direction comprises the projection of the loading body (22) connected with the loading head in the Y direction; the material of the loading head (23) is metal.

7. A modular periodically loaded microwave heating apparatus according to claim 1, characterized in that it further comprises at least one flat module (3); the flat plate module (3) is a rectangular metal plate with a certain thickness.

8. A modular periodically loaded microwave heating apparatus according to claim 1, characterized in that it further comprises at least two side panel modules (4) located in the X-direction and the-X-direction; the side plate module (4) is connected with the feed-in module (1), the loading module (2) or the flat plate module (3) in the Y direction or the-Y direction.

9. A modular periodically loaded microwave heating device according to claim 1, said infeed module (1) further comprising at least 20 load carriers (22); the loading bodies (22) are in contact with the feed plate (12) only in the Y direction or in the-Y direction.

10. A modular periodically loaded microwave heating apparatus as claimed in claim 1, wherein a channel (5) is provided, in which channel (5) the material (6) to be heated is provided.