Hollow reactor with semi-open sound insulation device and noise reduction and heat dissipation optimization method thereof

Abstract

A kind of hollow reactor with half-open type sound insulation device and its noise reduction and heat dissipation optimization method, according to the design parameters and electrical parameters of the stacked hollow reactor, a three-dimensional model is established, the magnetic flux density, electromagnetic force, vibration displacement and sound field distribution of the reactor coil with / without sound insulation device are obtained by simulation calculation;According to the obtained current and magnetic flux density distribution of the reactor, combined with the current and basic structure of the reactor coil, the loss of the coil and the star frame is calculated;The electromagnetic field-flow field-temperature field simulation model of the hollow reactor is constructed, the temperature of the coil and the surrounding fluid flow velocity distribution characteristics with / without sound insulation device are calculated;The influence law of each parameter of the sound insulation device on the sound pressure level and the highest temperature of the reactor measuring point is calculated;According to the constructed approximate model, sensitivity analysis and weight coefficient calculation results, the optimal parameters of the reactor sound insulation device are obtained. The optimization method has important reference significance for the parameter optimization of the reactor sound insulation device.

Description

Technical Field

[0001] This invention relates to the field of reactor optimization technology, specifically to a hollow reactor with a semi-open sound insulation device and its noise reduction and heat dissipation optimization method. Background Technology

[0002] Dry-type air-core reactors, as important reactive power compensation devices in high-voltage power transmission, play a crucial role in improving power quality, filtering high-order harmonics, and compensating for reactive power, and are widely used in power systems. However, with the increase in transmission voltage levels and grid capacity, noise generated by air-core reactors, the primary noise source, is becoming increasingly severe during the actual operation of converter stations. Currently, to reduce noise around reactors, fully enclosed or semi-open sound insulation devices are often installed around them. However, while these devices reduce noise, they also impede the flow of fluids around the reactor, significantly reducing the heat dissipation capacity of the reactor's encapsulated coils and significantly increasing temperature rise, which can easily lead to serious accidents such as reactor overheating and burnout. Furthermore, current research on reactor sound insulation devices focuses only on local optimizations such as noise suppression or temperature rise reduction, failing to achieve global optimization. Therefore, in order to reduce noise and improve the heat dissipation capacity of reactors, it is necessary to propose a structural form of sound insulation device. At the same time, it is crucial to conduct optimization research on the structural parameters of the sound insulation device based on accurate calculation of the noise and temperature rise of the hollow reactor. Summary of the Invention

[0003] This invention provides a hollow reactor with a semi-open sound insulation device and its noise reduction and heat dissipation optimization method. This method is applicable to natural air-cooled conditions. Based on the sound field and temperature field distribution characteristics of the reactor with the semi-open sound insulation device, it combines multi-physics field coupled finite element simulation and optimal Latin square experiment with a relatively small number of data samples to fit the response relationship between the structural parameters of the sound insulation device and the sound pressure level and the highest temperature at the reactor measurement point. Then, based on the weight relationship between the two and the algorithm, the structural parameters of the sound insulation device are optimized to achieve the purpose of balanced noise suppression and heat dissipation of the reactor with the sound insulation device.

[0004] The technical solution adopted in this invention is as follows:

[0005] A hollow reactor with a semi-open sound insulation device includes a reactor body, and a sound insulation device is provided outside the reactor body. The sound insulation device has openings at both the top and bottom for fluid flow. A silencer is installed at the top of the reactor body.

[0006] The reactor body is connected to a star-shaped frame at both the top and bottom, and a support column is provided between adjacent phases.

[0007] The soundproofing device is fitted with a rain cap at the top.

[0008] The muffler is equipped with sound-insulating material.

[0009] A method for optimizing noise reduction and heat dissipation of a hollow reactor with a semi-open sound insulation device includes the following steps:

[0010] Step 1: Obtain the initial design parameters of the air-core reactor, calculate the inductance matrix of the reactor, and obtain the current of each encapsulated coil by combining the rated current flowing through the reactor;

[0011] Step 2: Construct a simulation model of the hollow reactor circuit-magnetic field-structural field-sound field. Through material properties, mesh generation and boundary condition settings, calculate and obtain the magnetic flux density, vibration displacement and sound field distribution characteristics of the reactor. According to GB / T25092-2010 standard, obtain the total sound pressure level of the reactor at the measuring points with and without sound insulation devices.

[0012] Step 3: Based on the flux density distribution of the reactor obtained in Step 2, and combined with the current and basic structure of the reactor encapsulation coil, calculate the losses of the encapsulation coil and the star frame.

[0013] Step 4: Considering the influence of temperature on the physical properties of materials and surrounding fluids, construct a circuit-magnetic field-flow field-temperature field simulation model of the reactor. By applying heat source loading, material parameters such as thermal conductivity and thermal conductivity coefficient, as well as mesh generation and boundary condition settings, calculate the temperature distribution characteristics of the reactor encapsulation coil and the surrounding fluid velocity distribution under conditions with and without sound insulation devices.

[0014] Step 5: Select the parameters that affect the structure of the sound insulation device, and use the optimal Latin square test method to design an experiment with the sound pressure level and maximum temperature at the reactor measuring point under the sound insulation device as the optimization target. Record the sound pressure level and maximum temperature at the reactor measuring point under the sound insulation device. Calculate the influence of each parameter of the sound insulation device on the sound pressure level and maximum temperature at the reactor measuring point based on sensitivity analysis technology.

[0015] Step Six: Establish the Kriging approximation model using the optimal Latin square experimental simulation data from Step Five; calculate the weighting coefficients of reactor noise and maximum temperature using SPSS principal hierarchical analysis; obtain the optimal structural parameters of the sound insulation device under constraints using the NSGA-II algorithm in MATLAB software, thereby obtaining the balanced solution for noise suppression and heat dissipation of the reactor with the sound insulation device installed.

[0016] In step one, the inductance matrix of the reactor is calculated. The specific expression of the inductance matrix and the current of each encapsulated coil are as follows:

[0017] For the analysis of electromagnetic field problems, based on the equivalent model of field-circuit coupling of the reactor, the branch voltage equation satisfied by the reactor is:

[0018]

[0019] In the formula: This refers to the rated voltage of each encapsulated coil. For the current of each encapsulated coil, Let be the inductance of each encapsulated coil.

[0020] By analyzing the reactor structure and parameters, the inductance matrix M can be calculated, and the magnitude of each encapsulated current of the reactor can be obtained and applied to the model.

[0021] In step two, the specific expression for the simulation model of the hollow reactor circuit-magnetic field-structural field-acoustic field is as follows:

[0022] The electromagnetic field of a dry-type air-core reactor is time-varying and satisfies Maxwell's equations for three-dimensional electromagnetic fields. Based on the vector magnetic potential obtained through path coupling calculation, the electromagnetic force on the encapsulated coil is calculated using the principle of virtual displacement.

[0023] The vibration of the reactor satisfies the dynamic equation of simple harmonic motion:

[0024] Ma(t) + Cv(t) + Kx(t) = F(t) (2)

[0025] Where M, C, and K are the mass, damping, and stiffness matrices, respectively; a(t), v(t), and x(t) are the acceleration, velocity, and displacement vectors, respectively; and F(t) is the force vector.

[0026] Select the pressure acoustic module and use acoustic-solid coupling to solve the sound pressure fluctuation equation of the reactor sound field, as shown in equation (3) below:

[0027]

[0028] In the formula, c is the speed of sound, in m / s; p is the sound pressure, in Pa.

[0029] Step two includes the following steps:

[0030] S2.1: First, by combining the structural characteristics and inductance matrix of the reactor encapsulated coil with the finite element method, the magnetic flux density and electromagnetic force distribution of the encapsulated coil are calculated.

[0031] The electromagnetic field calculation of the stacked air-core reactor of this invention adopts a field-circuit coupling calculation method, and the magnetic field distribution is shown in Figures 1(a), 1(b), and 1(c). As can be seen from Figures 1(a), 1(b), and 1(c), the maximum magnetic flux density of the reactor is located in the middle of the innermost layer of the intermediate layer, with a maximum value of 0.14T. The magnetic flux density of the encapsulated coil of each reactor gradually decreases radially outwards, and the magnetic flux density on both sides along the axial direction shows a basically symmetrical decreasing trend.

[0032] As shown in Figures 2(a) and 2(b), the net axial electromagnetic force of each reactor is zero at the midpoint of the arc length. The electromagnetic force along the axial direction from the center outwards generally exhibits a symmetrical and gradually increasing trend, reaching its maximum at the top and bottom. Overall, the axial electromagnetic force is greatest at the bottom, followed by the middle, and smallest at the top. The radial electromagnetic force, however, is opposite to the axial force. It reaches its maximum at the midpoint of the coil encapsulation of each reactor, then gradually decreases towards both ends, while the radial electromagnetic force of the outermost coil is essentially zero.

[0033] S2.2: Secondly, the electromagnetic force generated by the encapsulated coil is used as the corresponding body load condition of the structural field. The upper surface of the uppermost star-shaped frame and the bottom surface of the support column of the lowermost encapsulated coil are used as fixed constraints. Then, through material properties such as elastic modulus and Poisson's ratio, mesh generation and boundary condition settings, the stress, strain and vibration acceleration, velocity and displacement distribution characteristics of the reactor are calculated.

[0034] (1) Material property settings:

[0035] The star-shaped frame and the encapsulated coil of the stacked dry-type air-core reactor are made of aluminum, the soundproof cover is made of porous dielectric material, the rain cap is made of polyester material, and the silencer is made of polyester material with sound-absorbing cotton attached.

[0036] (2) Boundary condition settings:

[0037] The boundary conditions of the sound field model are set as follows: the sound field adopts four modules: magnetic field, circuit, solid mechanics, and pressure acoustics-frequency domain; the electromagnetic force on the encapsulation coil of each reactor is used as the body load condition; the bottom surface of the support column of the lowest encapsulation coil is set as fixed constraint, and other parts vibrate freely; the outer boundary of the computational domain is set as a perfectly matched layer.

[0038] (3) Mesh generation:

[0039] To balance computational speed and accuracy, a custom mesh was used. The mesh was denser at the reactor body, slightly denser at the semi-open soundproof enclosure, muffler, and rain cap, and a standard mesh was used for the air domain. The mesh generation results are shown below. Figure 3 As shown, the number of mesh elements in the free tetrahedron is 6,257,695.

[0040] As shown in Figures 4(a) and 4(b), the stress on the encapsulated coil is relatively small, while the stress at the connection between the encapsulation and the support column is relatively large. This is because, under the condition of free vibration of the reactor encapsulated coil, the stress is applied to the star-shaped frame and the support column, resulting in a larger stress at the connection. Regarding vibration displacement, since the bottom surface of the support column is constrained and cannot deform freely, the deformation of the lowest surface of the support column in the bottommost encapsulation is 0. The overall vibration displacement of the encapsulated coil shows a trend of the largest displacement in the topmost encapsulation, followed by the middle layer, and the smallest displacement in the bottommost layer. This is because the support column is fixedly constrained and cannot deform freely, thus transmitting the vibration to the middle layer through the star-shaped frame and the support column. Similarly, the middle layer can also transmit the vibration to the upper layer, therefore the upper layer has no constraints and thus has the largest vibration displacement.

[0041] As shown in Figures 5(a) and 5(b), regarding vibration velocity, the bottom surface of the support column is constrained and cannot deform freely. Therefore, the vibration velocity of the bottommost encapsulated support column is essentially zero. The overall vibration velocity of the encapsulated coils of each reactor shows a trend of high velocity in the upper and middle layers and low velocity in the bottom layer. This is because the support column is fixed and cannot deform freely, thus transmitting the vibration through the star-shaped frame and support column to the middle and upper layers. Regarding vibration acceleration, the bottom surface of the support column is constrained and cannot deform freely, resulting in an essentially zero vibration acceleration in the bottommost encapsulated support column. However, this leads to increased vibration transmitted to the upper encapsulated layers. Therefore, the vibration acceleration of the bottommost reactor is relatively high, followed by the middle layer, and lowest in the top layer. The vibration acceleration is mainly concentrated at the position of the coils inside each reactor. The contact surfaces between the star-shaped frame and the encapsulation, and the contact parts between the support column and the star-shaped frame, experience higher vibration acceleration due to the transmissibility of electromagnetic force vibration.

[0042] S2.3: Finally, the vibration acceleration of the encapsulated coil is used as the source of noise propagation. Air is used as the propagation medium. The boundary condition of the reactor noise calculation domain is set as a perfectly matched layer to absorb the sound waves on the boundary. By using material properties such as sound velocity and combining the sound pressure wave equation, the sound field distribution characteristics of the reactor are obtained. According to the GB / T25092-2010 standard, a sound pressure measurement point of the reactor is selected at a distance of 3m from the outside of the sound insulation device and in the middle of the encapsulated coil. The total sound pressure level of the reactor with and without the sound insulation device can be obtained.

[0043] This invention obtains the total sound pressure level of the reactor with and without a sound insulation device based on the fundamental electromagnetic-structure-sound field theory, as shown in Figures 6(a) and 6(b). Analysis of Figures 6(a) and 6(b) shows that without a sound insulation device, the noise generated by the reactor's encapsulated coil propagates from the inside out, with obvious points of sound pressure enhancement and reduction. The highest sound pressure level is located in the innermost encapsulation layer, with a maximum value of 85.2 dB. After adding a sound insulation device, due to the sound wave interference phenomenon and the reflection and refraction effect of the sound insulation device, the internal sound pressure level is significantly enhanced, reaching a maximum value of 98.5 dB. However, due to the sound insulation effect of the device, the sound pressure level outside the device is significantly reduced, lower than the external sound pressure level without the device. Therefore, the sound insulation device has a certain sound insulation effect.

[0044] In step three, the resistance loss of each turn of conductor is proportional to the current and resistance of the conductor. The conductor resistance can be calculated from the conductor resistivity, conductor length and cross-sectional area. The resistance loss of the conductor can be calculated by the formula.

[0045] A reactor generates a large amount of heat during operation. The heat generated by the encapsulated winding is mainly reflected in the coil losses, which include resistance losses and eddy current losses. Combining formula (4), and according to Joule's law, the resistance loss of the reactor's encapsulated winding is:

[0046]

[0047] In the formula, P 0,i I represents the resistive loss of the i-th package. i W i D i ,κ,S i These are the encapsulation current, number of turns, coil diameter, coil conductor conductivity, and encapsulation coil cross-sectional area, respectively.

[0048] Based on the magnetic flux density distribution of the reactor encapsulation coil obtained in step two, the radial and axial magnetic flux distribution of the conductor can be obtained. Combined with the structural parameters of the conductor, the eddy current loss of the conductor can be calculated according to the eddy current loss formula. The total loss of the encapsulation coil is obtained by adding the calculated resistance loss and eddy current loss of the reactor encapsulation coil.

[0049] Eddy current loss: Ignore the demagnetizing effect of the eddy currents themselves in the conductor, and assume that the eddy currents are active currents.

[0050] Considering that each encapsulated coil of the air-core reactor is coaxially wound with a single flat conductor, the eddy current loss of a single turn of conductor can be expressed by equation (5):

[0051]

[0052] Among them, Pc,i Let ω be the eddy current loss of the single-turn conductor in the i-th envelope, and ω be the angular velocity (rated frequency 50Hz). i b i Let B be the radial width of the i-th encapsulation and the axial height of a single turn. z,i B r,i Let be the axial and radial components of the magnetic induction intensity at the i-th encapsulation position of that turn.

[0053] Total loss: The total loss of the reactor is the sum of the resistance loss and the eddy current loss. The total loss of any one turn of the enclosure can be expressed by equation (6). Considering that the sum of the losses of each turn is the total loss of the enclosure, the total loss of each enclosure of the reactor can be calculated.

[0054]

[0055] In the formula, the conductivity of the metal conductor changes with the encapsulation temperature. In order to reduce the complexity of the temperature field simulation calculation and take into account the accuracy of the calculation, κ is taken as the conductivity of the metal conductor corresponding to the average temperature rise of the reactor coil.

[0056] The star frame loss can be calculated by combining the radial and axial magnetic fields of the star frame arms with structural parameters;

[0057] The eddy current loss of the star-shaped support arm is shown in equation (7):

[0058]

[0059] In the formula, P s The root mean square loss is given by ρ, where ρ is the material resistivity. V represents the total current density, and V represents the volume of the star-shaped frame.

[0060] In step four, the simulation model of the reactor's circuit-magnetic field-flow field-temperature field is specifically as follows:

[0061] Stacked air-core reactors mainly transfer heat to the surrounding environment through three methods: heat conduction, heat convection, and heat radiation.

[0062] Heat conduction: Some of the heat generated by the dry air-core reactor is conducted through the solid components of the encapsulated coil, star-shaped frame, and sound insulation device via a temperature gradient from high to low.

[0063] Thermal convection: Between the surfaces of the encapsulated coils of the reactor, and between the encapsulated coils and the sound insulation device, heat is mainly exchanged with the surrounding fluid through thermal convection, satisfying the equations of continuity, momentum conservation, and energy conservation.

[0064] Thermal radiation: Heat is mainly dissipated through thermal radiation on the inner surface of the innermost encapsulated coil, the outer surface of the outermost encapsulated coil, the surface of the star-shaped frame, and the surface of the sound insulation device.

[0065] In step four, considering the influence of temperature on the material and surrounding fluid properties, the total loss of the encapsulated coil and the loss of the star frame are applied to the encapsulated coil as average heat sources. The reactor encapsulated coil, star frame, and soundproof cover are set as stationary walls with zero velocity in all directions. The bottom surface of the entire model is set as the inlet, and the front and rear sides, left and right sides, and top surface are set as the outlets. Environmental thermal radiation is considered as boundary conditions. Through material parameters such as thermal conductivity, constant pressure heat capacity, and mesh generation, the temperature distribution of the encapsulated coil and the velocity distribution of the surrounding fluid with and without soundproofing can be calculated.

[0066] (1) Material parameter settings:

[0067] The star-shaped frame and the encapsulated coil of the stacked dry-type air-core reactor are made of aluminum, the soundproof cover is made of porous dielectric material, the rain cap is made of polyester material, and the silencer is made of polyester material with sound-absorbing cotton attached.

[0068] (2) Boundary condition settings:

[0069] The temperature field employs two modules: laminar flow and fluid heat transfer. The reactor encapsulation coil, star-shaped frame, rain cap, and sound insulation device are stationary walls. The bottom surface of the entire model's air domain is set as the fluid inlet with a velocity of 0.05 m / s; other surfaces are set as outlets with a velocity of 0. The emissivity of the thermal radiation solid surface is set to 0.9. The ambient temperature is set to 20℃.

[0070] (3) Mesh generation:

[0071] The mesh generation settings are as described above. Figure 3 As shown.

[0072] Characteristics of temperature and surrounding fluid velocity distribution in the encapsulated coil: such as Figures 7(a) to 7(b) The simulation results of the flow field and temperature field are shown without and without sound insulation devices.

[0073] Based on the temperature field analysis in Figure 7(a) without sound insulation, the stacked reactor exhibits the following temperature pattern: the lowest temperature is found in the bottom layer, followed by the middle layer, and the highest temperature is found in the top layer. The highest temperature is located at the top of the fifth encapsulation of the top layer reactor, reaching a maximum of 52.63℃. This is because the stacked reactors create a "chimney effect," resulting in a lower maximum temperature compared to single-phase reactors. The lower layer reactors transfer heat to the upper layer via conduction and convection, thus lowering their temperature. Furthermore, the outermost coil dissipates heat to the air, while the innermost coil dissipates heat outwards through the central hole, providing better heat dissipation conditions than the middle coils, resulting in a lower external temperature. Figure 7(c) shows that with sound insulation installed, the reactor's maximum temperature significantly increases, reaching a maximum of 88.53℃, an increase of 35.9℃ compared to Figure 7(a). According to the flow field distribution without a sound insulation device in Figure 7(b), the maximum flow velocity is in the upper part of the air domain, with a maximum value of 1.62 m / s, and the flow velocity in the lower layer is lower than that in the upper layer. Combined with the analysis of Figure 7(d), with the sound insulation device installed, the maximum flow velocity is located at the upper opening of the sound insulation device, with a maximum value of 1.28 m / s. This is because the sound insulation device impedes the fluid flow velocity, thus affecting the convective heat transfer of the surrounding fluid, resulting in a significant increase in the reactor's maximum temperature rise. Therefore, optimizing the structural parameters of the reactor's sound insulation device is essential.

[0074] In step five, according to Figure 11 The parameters affecting the structure of the sound insulation device were selected, and the optimal Latin square test method was adopted, as follows:

[0075] Latin hypercube design can perform "space filling," the principle of which is to fill each coordinate interval in m-dimensional space. k∈[1,m] is divided into n equal intervals. Each subinterval can be denoted as . i∈[1,n]. Randomly select n points to ensure that each factor is studied only once at each level, thus forming an m-dimensional space and a Latin hypercube design with n samples.

[0076] The advantages of the Latin hypercube design are:

[0077] ① Effective space-filling ability

[0078] ② It can fit nonlinear responses well.

[0079] ③ Compared to the Latin hypercube experimental design method, the total factorial design requires the most experimental data and is less efficient; compared with the orthogonal experimental design method, the Latin hypercube design can study more combinations with the same number of points and can also control the number of trials; the central combination method is prone to dead zones when designing experiments, resulting in missing data at the edges and corners.

[0080] The sound pressure level and maximum temperature at the reactor measuring point with the sound insulation device installed were used as optimization targets for raw data collection, and the sound pressure level and maximum temperature at the reactor measuring point with the sound insulation device installed were recorded. The influence of each parameter of the sound insulation device on the sound pressure level and maximum temperature at the reactor measuring point was calculated based on sensitivity analysis technology.

[0081] This invention employs sensitivity analysis technology to analyze the influence of the structural parameters of the sound insulation device on the optimization target of the reactor. The sensitivity index is defined as follows:

[0082]

[0083] In the formula: Xi is the design variable; Y is the state variable of each system, Var(E(Y|X)) i E(Y|X) i The unconditional variance of Y is given by Var(Y).

[0084] In step 5, to balance the accuracy and speed of the calculation, an optimal Latin square experimental design is combined with the finite element method. Compared with the comprehensive experimental method, it greatly reduces the number of simulations and the workload of simulation calculation. Compared with the orthogonal experimental method, it can effectively fill the space, studying more combinations with fewer data points. The specific implementation is as follows: based on the DOE in the Isight software design, 50 sets of optimal Latin square experimental design tables can be obtained according to the range of parameters and the number of points to be studied. Then, combined with the COMSOL finite element simulation software, the simulation results of the sound field and temperature field of the reactor with sound insulation device under different structural parameters can be obtained. These 50 experimental samples can comprehensively analyze the influence of various parameters of the sound insulation device on the noise and temperature of the reactor.

[0085] In step six, based on the simulation data from step five, ten points are selected as error analysis points. A Kriging approximation model is established using the original data, and a goodness of fit higher than 0.9 satisfies the fitting accuracy requirement. This model reflects the response relationship between the reactor's sound pressure level and maximum temperature and the structural parameters of the sound insulation device. It also reveals the influence of various factors on the reactor's sound pressure level and maximum temperature. The weighting coefficients for reactor noise and maximum temperature are calculated using SPSS principal hierarchical analysis. The target weights for noise and temperature are 0.33 and 0.67, respectively. Based on the approximation model constructed from the above data, the sensitivity analysis, and the weighting coefficient calculation results, the optimal parameters of the reactor's sound insulation device are obtained using MATLAB software combined with the NSGA-II algorithm.

[0086] In step 6, based on the simulation data above, 10 points are selected as error analysis points. A Kriging approximation model is established by setting evaluation criteria for average error, absolute maximum error, root mean square error, and goodness of fit.

[0087] This model reflects the response relationship between the reactor's maximum temperature and the structural parameters of the sound insulation device. Among them, the Kriging method, also known as the spatial local interpolation method, is a method for making unbiased optimal estimates of unknown data points based on known data points. The estimated value of the unmeasured points is obtained by weighted summation of adjacent measured points, as shown in equation (9).

[0088]

[0089] Where x0 is the valuation point, x1, x2, ..., x m Given the data points, the corresponding sample values ​​are T(x1), T(x2), and T(x... m The estimated value for the unmeasured points is T(x0), μ i These are the weighting coefficients.

[0090] The advantages of using an approximation model are: it has a strong ability to approximate complex nonlinear functions, requires no mathematical assumptions, and has black-box characteristics. It can fit the relationship between input and output relatively well.

[0091] The present invention provides an air-core reactor with a semi-open sound insulation device, the technical effects of which are as follows:

[0092] 1) Considering the limitations of noise suppression and heat dissipation of dry-type air-core reactors, this invention designs a structural form of a stacked air-core reactor sound insulation device, providing a premise for optimizing the structural parameters of the sound insulation device;

[0093] 2) Based on the electromagnetic-structure-sound field coupling simulation method of hollow reactors, this invention obtains the characteristics of magnetic flux density, electromagnetic force, vibration displacement and sound field distribution of hollow reactors with and without sound insulation devices;

[0094] 3) Based on the electromagnetic-flow-temperature field coupling simulation method of hollow reactors, this invention obtains the temperature field and flow field distribution characteristics of hollow reactors with and without sound insulation devices;

[0095] 4) This invention combines the optimal Latin square test method with the finite element method, which can obtain the influence law of each parameter of the reactor sound insulation device on the sound pressure level and the highest temperature at the measuring point with less raw data, and obtain the sensitivity value of each structural parameter to the two optimization targets through sensitivity analysis technology.

[0096] 5) This invention obtains the optimal structural parameters of the sound insulation device under constraints by establishing a Kriging approximation model using the original data mentioned above and combining it with the NSGA-Ⅱ algorithm in MATLAB. While keeping the reactor body structure and electrical parameters unchanged, it achieves a balance between the noise suppression and heat dissipation performance of the reactor with the sound insulation device installed. This optimization method has important reference significance for the parameter optimization of reactor sound insulation devices. Attached Figure Description

[0097] Figure 1(a) shows the magnetic flux density distribution.

[0098] Figure 1(b) shows the magnetic flux density distribution of the XOY cross section;

[0099] Figure 1(c) shows the magnetic flux density distribution of the YOZ cross section.

[0100] Figure 2(a) shows the axial electromagnetic force distribution of the reactor;

[0101] Figure 2(b) shows the radial electromagnetic force distribution of the reactor.

[0102] Figure 3 This is a diagram showing the mesh generation results.

[0103] Figure 4(a) shows the stress distribution of the reactor;

[0104] Figure 4(b) shows the vibration displacement distribution of the reactor.

[0105] Figure 5(a) shows the vibration velocity distribution of the reactor;

[0106] Figure 5(b) shows the vibration acceleration distribution of the reactor.

[0107] Figure 6(a) shows the sound field distribution of the reactor without sound insulation device;

[0108] Figure 6(b) shows the sound field distribution of the reactor after the addition of a sound insulation device.

[0109] Figure 7(a) shows the temperature field distribution without sound insulation.

[0110] Figure 7(b) shows the flow field distribution without sound insulation devices;

[0111] Figure 7(c) shows the temperature field distribution after the sound insulation device is installed;

[0112] Figure 7(d) shows the flow field distribution after the addition of a sound insulation device.

[0113] Figure 8(a) is a three-dimensional schematic diagram (top view) of the stacked dry-type air-core reactor structure;

[0114] Figure 8(b) is a three-dimensional schematic diagram (front view) of the stacked dry-type air-core reactor structure.

[0115] Figure 9(a) is a three-dimensional structural diagram of the sound insulation device;

[0116] Figure 9(b) is a cross-sectional schematic diagram of the sound insulation device.

[0117] Figure 10 A flowchart illustrating the design process for optimizing the structural parameters of a sound insulation device for a stacked dry-type air-core reactor.

[0118] Figure 11 A two-dimensional schematic diagram is used to select the structural parameters of the sound insulation device;

[0119] Figure 11 In the diagram, x1 is the distance from the top of the rain cover to the top of the soundproof cover, x2 is the length of the rain cover, x3 is the height of the rain cover itself, x4 is the radius of the opening at the top of the soundproof cover, x5 is the tilt angle of the soundproof cover, x6 is the distance from the soundproof cover to the rightmost end of the reactor encapsulation coil, x7 is the distance from the bottom of the star-shaped frame to the soundproofing device, and x8 is the radius of the opening at the bottom of the soundproof cover. Detailed Implementation

[0120] A hollow reactor with a semi-open sound insulation device is a three-phase stacked dry-type hollow reactor. The upper and lower ends of the reactor body 1 are connected to star-shaped frames 6, which serve as current-carrying buses and structural components. Support columns 7 support and separate the phases, and the three-phase stacked arrangement is shown in Figures 8(a) and 8(b). This arrangement has advantages such as a small footprint. In terms of heat dissipation, since the three phases are separated by support columns 7, the star-shaped frames 6 and support columns 7 have little impact on heat dissipation. The stacked arrangement of the three-phase reactors creates a "chimney" effect in the axial direction, resulting in better heat dissipation. Regarding the sound insulation device 2, this invention employs a semi-open cylindrical sound insulation device 2. The sound insulation device 2 includes a sound insulation cover, with sound-absorbing cotton and other sound-insulating materials attached to the cover arms. Openings 3 are provided at the top and bottom of the cover arms for fluid flow. To enhance the sound insulation effect, a silencer 4 is installed on the top of the reactor body 1. Sound-absorbing panels and sound-absorbing cotton and other sound-insulating materials are installed on the silencer 4, resulting in better sound insulation. This invention also considers the influence of the external environment on the reactor's operating conditions. A rain cap 5 is installed on the top of the sound insulation cover to resist changes in the external environment, delay the aging of the reactor, and reduce accidents during normal operation of the reactor, as shown in Figures 9(a) and 9(b).

[0121] The noise reduction and heat dissipation optimization method based on the above-mentioned hollow reactor includes the following steps:

[0122] Step 1: Based on the design and electrical parameters of the stacked air-core reactor, establish a three-dimensional model; combine the material properties of the star frame 6, encapsulated coil 8 and support column 7 of the stacked iron-core reactor in practice, and set the corresponding material property parameters, such as relative permeability and relative permittivity.

[0123] Boundary conditions were set according to normal operating conditions. Through electromagnetic-structural-sound field simulation, the magnetic flux density, electromagnetic force, vibration displacement, and sound field distribution of the reactor encapsulation coil with and without sound insulation device 2 were calculated. The simulation results are shown in Figure 6(a) and Figure 6(b). Figures 7(a) to 7(d) As shown.

[0124] Specifically as follows:

[0125] First, by combining the structural characteristics and inductance matrix of the reactor encapsulated coil with the finite element method, the magnetic flux density and electromagnetic force distribution of the encapsulated coil are calculated.

[0126] Secondly, the electromagnetic force generated by the encapsulation coil is used as the corresponding body load condition of the structural field, and the lower surface of the lowest support column is used as a fixed constraint. Then, through material properties (elastic modulus and Poisson's ratio, etc.), mesh generation and boundary condition settings, the stress, strain and vibration acceleration, velocity and displacement distribution characteristics of the reactor are calculated.

[0127] Finally, the vibration acceleration of the encapsulated coil is used as the source of noise propagation, and air is used as the propagation medium. The boundary condition of the reactor noise calculation domain is set as a perfectly matched layer (to absorb sound waves on the boundary). The sound field distribution characteristics of the reactor are obtained by combining material properties (sound velocity, etc.) with the sound wave propagation mechanism and following the sound pressure wave equation.

[0128] According to the GB / T25092-2010 standard, the sound pressure measurement point of the reactor was selected at a distance of 3m from the outside of the sound insulation device and in the middle of the encapsulated coil. The total sound pressure level of the reactor with and without the sound insulation device can be obtained. The sound field simulation results are shown in Figure 6(a) and Figure 6(b).

[0129] Step 2: Based on the reactor current and magnetic flux density distribution obtained in Step 1, combined with the current and basic structure of the reactor encapsulated coil, the losses of the encapsulated coil 8 and the star frame 6 can be calculated.

[0130] The resistance loss of each conductor turn is proportional to the conductor current and resistance. The conductor resistance can be calculated from the conductor resistivity, conductor length, and cross-sectional area. The resistance loss of the conductor can be calculated using the formula. Based on the magnetic flux density distribution of the reactor encapsulation coil obtained in step 1, the radial and axial magnetic flux distribution of the conductor can be obtained. Combined with the structural parameters of the conductor, the eddy current loss of the conductor can be calculated according to the eddy current loss formula. The calculated resistance loss and eddy current loss of the reactor encapsulation coil are added together to obtain the total loss of the encapsulation coil. The loss of the star frame 6 can be calculated by combining the radial and axial magnetic fields of the star frame arm with the structural parameters. See formulas (1) to (6) for details.

[0131] Step 3: Based on the losses of the encapsulated coil and star frame obtained in Step 2, construct an electromagnetic field-flow field-temperature field simulation model of the dry-type air-core reactor. The temperature distribution characteristics of the encapsulated coil and the surrounding fluid velocity distribution under the conditions of adding / not adding the sound insulation device 2 can be calculated. Among them, considering the influence of temperature on the material and surrounding fluid properties, the total loss of the encapsulated coil 8 and the loss of the star frame 6 are used as average heat sources and applied to the encapsulated coil 8. The reactor encapsulated coil 8, star frame 6 and sound insulation cover are set as stationary walls with zero velocity in all directions. The bottom surface of the entire model is set as the inlet, and the front and rear sides, left and right sides and the top surface are set as the outlet. Considering the environmental thermal radiation as boundary conditions, the temperature distribution characteristics of the encapsulated coil and the surrounding fluid velocity distribution under the conditions of adding / not adding the sound insulation device 2 can be calculated through material parameter properties, such as thermal conductivity, constant pressure heat capacity, etc., and mesh generation. The temperature field simulation results are shown in Figure 6(a).

[0132] Step 4: According to Figure 11 Various parameters affecting the structure of the sound insulation device were selected, and the optimal Latin square test method was adopted. The sound pressure level and maximum temperature at the reactor measuring point under the sound insulation device 2 were used as the optimization targets for raw data collection. The sound pressure level and maximum temperature at the reactor measuring point under the sound insulation device 2 were recorded. The influence of each parameter of the sound insulation device 2 on the sound pressure level and maximum temperature at the reactor measuring point was calculated based on the sensitivity analysis technology.

[0133] In step 4, to balance computational accuracy and speed, an optimal Latin square experimental design is combined with the finite element method. Compared to the full experimental method, this significantly reduces the number of simulations and the workload of simulation calculations. Compared to the orthogonal experimental method, it can effectively fill the space, studying more combinations with fewer data points. Specifically, based on the DOE (Design of Experiments) function in Isight software, 50 optimal Latin square experimental design tables can be obtained according to the parameter range and the number of points to be studied.

[0134] Based on the equivalent model of the sound insulation device for stacked hollow reactors, the main structural parameters and their ranges of the reactor sound insulation device are determined, such as... Figure 11As shown, there are a total of 8 influencing factors. x1 is the distance from the top of the rain cover to the top of the soundproof enclosure; x2 is the length of the rain cover; x3 is the height of the rain cover itself; x4 is the radius of the opening at the top of the soundproof enclosure; x5 is the tilt angle of the soundproof enclosure; x6 is the distance from the soundproof enclosure to the rightmost end of the reactor's encapsulation coil; x7 is the distance from the bottom of the star-shaped frame to the soundproofing device; and x8 is the radius of the opening at the bottom of the soundproof enclosure. Considering the actual soundproofing effect of the reactor and in accordance with engineering practice, the ranges for each parameter are as follows: x1 ranges from 0.1m to 0.3m, x2 ranges from 1.1m to 1.3m, x3 ranges from 0.1m to 0.2m, x4 ranges from 0.4m to 0.6m, x5 ranges from 0.1m to 0.2m, x6 ranges from 0.1m to 0.4m, x7 ranges from 0.1m to 0.3m, and x8 ranges from 0.4m to 0.6m.

[0135] Fifty sets of design variables for the sound insulation device of dry-type air-core reactors were sampled using the central composite experimental design method, as shown in Table 1.

[0136] Table 1 Optimal Latin Square Experimental Design

[0137]

[0138]

[0139]

[0140] Then, by combining the COMSOL finite element simulation software, simulation results of the acoustic field and temperature field of the reactor with sound insulation device 2 installed can be obtained under different structural parameters.

[0141] The simulation results of the sound field and temperature field of the reactor with sound insulation device 2 installed under different structural parameters were obtained. These 50 test samples can comprehensively analyze the influence of various parameters of the sound insulation device on the noise and temperature of the reactor.

[0142] Step 5: Based on the simulation data from Step 4, take 10 points as error analysis points, establish a Kriging approximation model using the original data, and the fitting degree is higher than 0.9 to meet the fitting accuracy requirements; this model reflects the response relationship between the reactor sound pressure level and maximum temperature and the structural parameters of the sound insulation device, and can also obtain the influence law of each factor on the reactor sound pressure level and maximum temperature.

[0143] Using SPSS principal hierarchical analysis, the weighting coefficients of reactor noise and maximum temperature were calculated; the target weights for noise and temperature were 0.33 and 0.67, respectively. Based on the approximate model constructed from the above data, sensitivity analysis, and weighting coefficient calculation results, the optimal parameters of the reactor sound insulation device were obtained using MATLAB software combined with the NSGA-II algorithm.

[0144] In the multi-objective optimization of NSGA-II, the present invention uses a weighted normalization method. The importance of the two indicators, noise and temperature, is calculated by the analytic hierarchy process (AHP) with weight coefficients of 0.33 and 0.67, respectively, and the scaling factor is 1 for both.

[0145] The importance of the two indicators was calculated using the Analytic Hierarchy Process (AHP), which involves three steps: establishing the hierarchical structure, constructing the judgment matrix, hierarchical single ranking, and consistency testing. The specific calculation results are as follows:

[0146] a: Establish a hierarchical structure. Since the optimization indicators of this invention are only the sound pressure level at the measuring point and the highest temperature, which belong to the same hierarchical structure, there is no need to divide them.

[0147] b: Construct the judgment matrix. The scale used to construct the judgment matrix is ​​shown in Table 2.

[0148] Table 2 shows the scale of the judgment matrix.

[0149]

[0150]

[0151] Based on the scaling method established by the above matrix, the importance judgment matrix of the measuring point sound pressure level and the highest temperature established by this invention is shown in Table 3.

[0152] Table 3. Importance Judgment Matrix of Indicators

[0153]

[0154] c. Hierarchical single sorting and consistency check. Since there are no corresponding logical errors between the two indicators, a consistency check is not required. The weights of each indicator are solved using the square root method, as shown in equation (25).

[0155]

[0156] Among them, a ij To determine the elements in a matrix, where n is the order of the matrix and w i To determine the nth root of the i-th row of a matrix.

[0157] Finally, the weights of the solved indicators are normalized, and the weight coefficients for sound pressure level and temperature are calculated to be 0.33 and 0.67, respectively.

[0158] In step 5, based on the simulation data above, 10 points are selected as error analysis points. A Kriging approximation model is established by setting evaluation criteria for average error, absolute maximum error, root mean square error, and goodness of fit. This model reflects the response relationship between the reactor's maximum temperature and the structural parameters of the rain cap 5 and the sound insulation device 2.

[0159] Among them, the Kriging method, also known as the spatial local interpolation method, is a method for making unbiased optimal estimates of unknown data points based on known data points. The estimated value of the unmeasured point is obtained by weighted summation of adjacent measured points, as shown in Equation (11).

[0160]

[0161] Where x0 is the valuation point, x1, x2, ..., x m Given data points, x i Let m be the number of sample points, and T(x1), T(x2), and T(x3) be the corresponding sample values. m The estimated value for the unmeasured points is T(x0), μ i These are the weighting coefficients.

[0162] The advantages of this approximation model are: it has a strong ability to approximate complex nonlinear functions, requires no mathematical assumptions, and has black-box characteristics. It can fit the relationship between input and output relatively well.

Claims

1. A method for optimizing noise reduction and heat dissipation of a hollow reactor with a semi-open design and sound insulation device, characterized in that... Includes the following steps: Step 1: Obtain the initial design parameters of the air-core reactor, calculate the inductance matrix of the reactor, and obtain the current of each encapsulated coil (8) by combining the rated current flowing through the reactor; Step 2: Construct a simulation model of the hollow reactor circuit-magnetic field-structural field-sound field. Calculate and obtain the magnetic flux density, vibration displacement and sound field distribution characteristics of the reactor by setting material properties, mesh generation and boundary conditions, and obtain the total sound pressure level of the reactor at the measuring point with / without sound insulation device (2). Step 3: Based on the flux density distribution of the reactor obtained in Step 2, combined with the current and basic structure of the reactor encapsulation coil (8), calculate the losses of the encapsulation coil (8) and the star frame (6); Step 4: Construct a circuit-magnetic field-flow field-temperature field simulation model of the reactor. By applying heat source, material parameters thermal conductivity and thermal conductivity coefficient, as well as mesh generation and boundary condition settings, calculate the temperature and surrounding fluid velocity distribution characteristics of the reactor encapsulated coil (8) with and without sound insulation device (2). Step 5: Select the parameters that affect the structure of the sound insulation device (2), adopt the optimal Latin square test method, and use the sound pressure level and maximum temperature of the reactor measuring point under the sound insulation device (2) as the optimization target to carry out the test design, and record the sound pressure level and maximum temperature of the reactor measuring point under the sound insulation device (2). The influence of each parameter of the sound insulation device (2) on the sound pressure level and maximum temperature at the reactor measuring point was calculated based on sensitivity analysis technology. Step 6: Establish the Kriging approximation model using the optimal Latin square experimental simulation data from Step 5; calculate the weighting coefficients of reactor noise and maximum temperature using SPSS principal hierarchical analysis method; obtain the optimal structural parameters of the sound insulation device (2) under constraints using MATLAB software and the NSGA-Ⅱ algorithm, thereby obtaining the balanced solution of noise suppression and heat dissipation of the reactor with the sound insulation device (2) installed.

2. The method for optimizing noise reduction and heat dissipation of a hollow reactor according to claim 1, characterized in that: In step one, the inductance matrix of the reactor is calculated. The specific expression of the inductance matrix and the current of each encapsulated coil (8) are as follows: The branch voltage equation satisfied by the reactor is: （1）； In the formula: This refers to the rated voltage of each encapsulated coil. For the current of each encapsulated coil, For the inductance of each encapsulated coil; Calculate the inductance matrix using the reactor structure and parameters. M Then, the magnitude of each encapsulated current of the reactor can be obtained and applied to the model.

3. The method for noise reduction and heat dissipation optimization of hollow reactors according to claim 1, characterized in that: Step two includes the following steps: S2.1: First, the magnetic flux density and electromagnetic force distribution of the encapsulated coil (8) are calculated by combining the structural characteristics and inductance matrix of the reactor-encapsulated coil (8) with the finite element method. The maximum magnetic flux density of the reactor is located in the middle of the innermost layer of the intermediate layer; The magnetic flux density of the encapsulated coil of each reactor gradually decreases outward along the radial direction, and the magnetic flux density on both sides along the axial direction basically shows a symmetrical decreasing trend. The axial electromagnetic force of each reactor is zero at the middle of the arc length, and the electromagnetic force along the axial direction from the middle to both sides is generally symmetrical and gradually increases, reaching its maximum at the top and bottom. Overall, the axial electromagnetic force is the largest at the bottom, followed by the middle, and the smallest at the top. The radial electromagnetic force is the opposite of the axial force. It reaches its maximum at the middle of each reactor coil and then gradually decreases towards both ends, while the radial electromagnetic force of the outermost coil is basically zero. S2.2: Secondly, the electromagnetic force generated by the encapsulated coil (8) is used as the corresponding body load condition of the structural field. The upper surface of the uppermost star frame and the bottom surface of the support column of the lowermost encapsulated coil are used as fixed constraints. Then, through material properties, meshing and boundary condition settings, the stress, strain and vibration acceleration, velocity and displacement distribution characteristics of the reactor are calculated. (1) Material property settings: The star-shaped frame and the encapsulated coil of the stacked dry air reactor are made of aluminum, the soundproof cover is made of porous dielectric material, the rain cap is made of polyester material, and the silencer is made of polyester material with sound-absorbing cotton attached. (2) Boundary condition settings: The boundary conditions of the sound field model are set as follows: the sound field adopts four modules: magnetic field, circuit, solid mechanics, and pressure acoustics-frequency domain; the electromagnetic force on the encapsulation coil of each reactor is used as the body load condition; the bottom surface of the support column of the lowest encapsulation coil is set as fixed constraint, and other parts vibrate freely; the outer boundary of the computational domain is set as a perfect matching layer. (3) Mesh generation: A custom mesh is used, with a denser mesh at the reactor body location, a slightly denser mesh at the semi-open soundproof enclosure, silencer, and rain cap, and a conventional mesh for the air zone. In terms of stress, the stress on the encapsulated coil (8) is smaller, while the stress at the connection between the encapsulation and the support column is larger. Regarding vibration displacement, since the bottom surface of the support column is constrained and cannot deform freely, the deformation of the lowest surface of the lowest enclosed support column is 0. The vibration displacement of the overall encapsulated coil shows a trend of the largest vibration displacement at the top layer, followed by the middle layer, and the smallest at the bottom layer. This is because the support column has fixed constraints and cannot deform freely. Therefore, the vibration is transmitted to the middle layer through the star frame and support column. Similarly, the middle layer can also transmit the vibration to the upper layer. Therefore, the upper layer has no constraints and has the largest vibration displacement. Regarding vibration velocity, since the bottom surface of the support column is constrained and cannot deform freely, the vibration velocity of the support column enclosed at the bottom layer is basically 0. The overall vibration velocity of the encapsulated coils of each reactor shows a trend of being higher in the upper and middle layers and lower in the bottom layer. This is because the support columns are fixed and cannot deform freely, so the vibration is transmitted to the middle and upper layers through the star-shaped frame and the support columns. In terms of vibration acceleration, since the bottom surface of the support columns is constrained and cannot deform freely, the vibration acceleration of the support columns of the bottom layer is basically 0, but this will cause the vibration transmitted to the upper layers to intensify. Therefore, the vibration acceleration of the bottom layer reactors is larger, followed by the middle layer, and the smallest in the top layer. The vibration acceleration is concentrated at the position of the coil inside each reactor, while the contact surface between the star frame and the enclosure, and the contact part between the support column and the star frame have larger vibration acceleration due to the transmissibility of electromagnetic force vibration. S2.3: Finally, the vibration acceleration of the encapsulated coil (8) is used as the source of noise propagation. Air is used as the propagation medium. The boundary condition of the reactor noise calculation domain is set as a perfectly matched layer to absorb the sound waves on the boundary. Through material properties and combined with the sound pressure wave equation, the sound field distribution characteristics of the reactor are obtained. According to the GB / T25092-2010 standard, the sound pressure measurement point of the reactor is selected at a position 3m away from the sound insulation device (2) and in the middle of the encapsulated coil (8). The total sound pressure level of the reactor with or without the sound insulation device (2) can be obtained.

4. The method for optimizing noise reduction and heat dissipation of a hollow reactor according to claim 1, characterized in that: In step three, the resistance loss of each turn of conductor is proportional to the conductor's current and resistance. The conductor resistance can be calculated from the conductor resistivity, conductor length, and cross-sectional area. The resistance loss of the conductor can be calculated using the following formula: The heat generated by the encapsulated winding manifests in the coil losses, which include resistance losses and eddy current losses. Combining formula (4) and Joule's law, the resistance loss of the reactor's encapsulated winding is: （4）； In the formula, For the first i The resistive loss of the encapsulated component; I i 、W i 、D i 、 、S i The first i Number of encapsulation current, number of turns, coil diameter, coil conductor conductivity, and encapsulation coil cross-sectional area.

5. The method for optimizing noise reduction and heat dissipation of a hollow reactor according to claim 4, characterized in that: In step three Based on the magnetic flux density distribution of the reactor encapsulation coil obtained in step two, the radial and axial magnetic flux distribution of the conductor can be obtained. Combined with the structural parameters of the conductor, the eddy current loss of the conductor can be calculated according to the eddy current loss formula. The total loss of the encapsulation coil is obtained by adding the calculated resistance loss and eddy current loss of the reactor encapsulation coil. Considering that each encapsulated coil of the air-core reactor is coaxially wound with a single flat conductor, the eddy current loss of a single turn of conductor is expressed by equation (5): （5）； in, For the first Eddy current loss of a single-turn encapsulated conductor Angular velocity, , For the first The radial width and axial height of a single turn of the package. , For the first The axial and radial components of the magnetic induction intensity at the location of the encapsulation; The total loss of the reactor is the sum of the resistance loss and the eddy current loss. The total loss of any one turn of the enclosure is expressed by equation (6). Considering that the sum of the losses of each turn is the total loss of the enclosure, the total loss of each enclosure of the reactor can be calculated. （6）； In equation (6), the conductivity of the metallic conductor changes with the encapsulation temperature. To reduce the complexity of the temperature field simulation calculation while maintaining the accuracy of the calculation, Take the conductivity of the metal conductor corresponding to the average temperature rise of the reactor coil; The star-shaped frame loss can be calculated by combining the radial and axial magnetic fields of the star-shaped frame arms with structural parameters: The eddy current loss of the star-shaped frame arm is shown in equation (7): （7）； In the formula, For root mean square loss, The resistivity of the material The total current density, The volume of the star-shaped frame.

6. The method for optimizing noise reduction and heat dissipation of a hollow reactor according to claim 1, characterized in that: In step four, considering the influence of temperature on the material and surrounding fluid properties, the total loss of the encapsulated coil and the loss of the star frame are applied to the encapsulated coil as average heat sources. The reactor encapsulated coil, star frame and soundproof cover are set as stationary walls with zero velocity in all directions. The bottom surface of the entire model is set as the inlet, and the front and rear sides, left and right sides and the top surface are set as the outlet. Considering environmental thermal radiation as boundary conditions, the temperature distribution of the encapsulated coil and the velocity distribution of the surrounding fluid with and without soundproofing device can be calculated through material parameter properties and mesh generation.

7. The method for optimizing noise reduction and heat dissipation of a hollow reactor according to claim 1, characterized in that: In step five, various parameters affecting the structure of the sound insulation device are selected. The optimal Latin square test method is used to collect raw data with the sound pressure level and maximum temperature at the reactor measuring point under the sound insulation device (2) as the optimization target. The sound pressure level and maximum temperature at the reactor measuring point under the sound insulation device (2) are recorded. The influence of each parameter of the sound insulation device (2) on the sound pressure level and maximum temperature at the reactor measuring point is calculated based on the sensitivity analysis technology. The sensitivity index is defined as: (8) ； In the formula: X i For design variables; Y For each system state variable, for The unconditional variance for The unconditional variance.

8. The method for optimizing noise reduction and heat dissipation of a hollow reactor according to claim 1, characterized in that: In step six, a Kriging approximation model is established by setting evaluation criteria for average error, absolute maximum error, root mean square error, and goodness of fit. This model reflects the response relationship between the reactor's maximum temperature and the structural parameters of the sound insulation device. The Kriging method is a method for making unbiased optimal estimates of unknown data points based on known data points. The estimated values ​​of unmeasured points are obtained by weighted summation of adjacent measured points, as shown in equation (9). (9) ； in, x 0 is the valuation point. x 1, x 2, ..., x m Given the data points, the corresponding sample values ​​are: T ( x 1), T ( x 2), ..., T ( x m The estimated value for unmeasured points is... T ( x 0), μ i These are the weighting coefficients.

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