Fan built-in granary local precise ventilation system and control method

Abstract

The invention discloses a local precise ventilation system with a built-in fan for a granary and a control method, and belongs to the technical field of mechanical ventilation in a grain postpartum warehousing system. A fan assembly in the ventilation system is located in a single ventilation cage of a ventilation cage set, and front and rear driving wheel pairs of a fan assembly are in sliding connection with a sliding groove of the single ventilation cage of the ventilation cage set; the fan built-in granary local precise ventilation system is arranged in a granary, the ventilation control system is installed at a remote control end, and operation parameters such as starting and stopping, the rotating speed and the working position of the built-in fan can be automatically adjusted according to grain condition data. By means of the ventilation system, low-temperature airflow can be fed into a grain pile from the position closest to the operation requirement, accurate ventilation and on-demand ventilation of a certain local area of the grain pile can be achieved, disturbance of the ventilation operation process to grains in a normal and safe storage state is minimized, the ventilation quality and efficiency are improved, and the ventilation efficiency is improved. And an efficient, energy-saving and high-cost-effectiveness local ventilation operation technical scheme can be provided for grain postpartum warehouse management.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechanical ventilation in a post-harvest grain storage system, and specifically relates to a local precision ventilation system for a grain silo with a built-in fan and a control method. Background Art

[0002] Grain piles are artificial loose-grain ecosystems composed mainly of grains, with unique physical and chemical properties and storage characteristics. In this ecosystem, there are both biological factors and non-biological factors. During the storage process, complex mutual coupling and influence will occur between the various factors, which may lead to abnormal grain conditions such as condensation, mildew, fever, and insect pests in severe cases, which can easily cause serious grain storage losses and endanger grain storage safety. Therefore, effective measures must be taken to reduce grain storage losses and ensure a stable and safe supply of grain.

[0003] Mechanical ventilation technology for grain storage is the most basic and important grain storage technology to ensure the safe storage of grain for a long period of time. At present, in the process of mechanical ventilation for grain storage, whether it is horizontal ventilation or vertical ventilation, the fan is installed externally on both sides of the eaves wall of the grain silo, and the fan drives multiple sets of ventilation pipes in the silo through the pre-installed air duct openings on the eaves wall for ventilation. In this way, the grain pile is often used as a whole to carry out full warehouse ventilation, or a large local area of ​​the grain pile (half warehouse, quarter warehouse, etc.) is partitioned for ventilation, which is not only easy to cause uneven distribution of wind force and escape of cold, but also the grain pile area close to the air duct opening is often over-ventilated, while the heating area far away cannot get sufficient ventilation; at the same time, it is also easy to cause rapid changes in temperature and humidity in a large range of the grain pile, destroying the moisture and heat balance of the grain microenvironment that is already in a safe state, causing a series of chain reactions such as water loss and quality deterioration in the grain. Therefore, it is particularly important to carry out targeted local on-demand ventilation and precise ventilation according to the grain state of the grain pile during storage. Summary of the invention

[0004] The purpose of the present invention is to provide a local precision ventilation operation system and control method for a grain silo with a built-in fan. By designing and developing a ground ventilation cage and its matching built-in fan, the fan is directly integrated and placed inside the ventilation duct. By integrating grain condition monitoring and ventilation operation control systems, the operation parameters such as the start and stop, speed and position of the built-in fan can be adjusted according to real-time grain condition data, and the low-temperature airflow is sent into the grain pile from the position closest to the operation requirements. It can achieve precise ventilation and on-demand ventilation of a local area or a local hot spot in the grain pile, minimize the interference of the ventilation process on the grain in the normal storage state, improve the quality and efficiency of ventilation operations, and provide an efficient, energy-saving and cost-effective local ventilation operation technical solution for grain post-harvest storage management.

[0005] The invention discloses a local precise ventilation system for a granary with a built-in fan, which is composed of a ventilation cage group A, a fan assembly B, a temperature detection cable group C and a ventilation control system D. The fan assembly B is located in a single ventilation cage of the ventilation cage group A, and a driving wheel pair I8c of a rear driving wheel assembly 8 and a driving wheel pair II10c of a front driving wheel assembly 10 in the fan assembly B are slidably connected to a slide groove 5 of a single ventilation cage of the ventilation cage group A. The local precise ventilation system for a granary with a built-in fan is arranged in a granary 1, and the assemblies of the ventilation cage group A and the fan assembly B are evenly distributed in parallel in the length direction of the ground of the granary 1, and the spacing between two adjacent assemblies of the ventilation cage group A and the fan assembly B is 2-6m; the temperature detection cable group C is arranged according to GB / T 26882.1-2024 national standard, arranged in a grid in the granary 1, and communicated with the data acquisition module 23 of the ventilation control system D; the frequency conversion control box 22 of the ventilation control system D is communicated with the motor 6 of the fan assembly B; the control execution module 27 of the ventilation control system D is communicated with the rear drive wheel assembly 8 and the front drive wheel assembly 10 of the impeller group B1 in the fan assembly B.

[0006] The ventilation cage group A is composed of ventilation cages with exactly the same structure. Each ventilation cage is composed of a cylindrical main body 2 and a pair of support plates 4. A slide groove 5 is provided in the front and rear longitudinal directions of the lower part of the cylindrical main body 2. The two support plates of the support plate pair 4 are fixedly connected to the bottom of the cylindrical main body 2 and are symmetrical to the two sides of the slide groove 5. A long hole group 3 is provided on the wall of the cylindrical main body 2, which is evenly arranged at equal intervals.

[0007] The fan assembly B is composed of an impeller group B1, a motor 6, a rear shield 7, a rear drive wheel group 8, a support rod group 9, a front drive wheel group 10 and a front shield 11. The rear shield 7 is provided with a spoke group 12, a bolt hole group 13 and a fan-shaped hole group I 14; the front shield 11 is provided with a fan-shaped hole group II 15 and a bearing 16; the impeller group B1 is composed of a crossflow impeller B2 and an axial flow impeller B3, the crossflow impeller B2 is composed of a blade group I 17 and an annular plate group 18, the blade group I 17 is composed of 4-5 layers of blades, each layer of blades is 32, and is evenly distributed on the annular surface of the annular plate; the annular plate group 18 is composed of 5-6 annular plate groups The 4th and 5th layers of blades of blade group I 17 are respectively located between every two layers of 5th and 6th annular plates of annular plate group 18, and the blades of each layer are evenly distributed and fixed on the annular surface of the annular plate, and the corresponding blades of the 4th and 5th layers are on a straight line; the cross-sectional shape of the blades in blade group I 17 is an arc shape, and the angle between the tangent line of the arc midpoint and the line connecting the lower end of the blade and the center of the annular plate is 30°; the axial flow impeller B3 is composed of blade group II 19, wheel disc 20 and main shaft 21, and the center of wheel disc 20 is fixed to the near front end of main shaft 21; the inner ends of 32 blades of blade group II 19 are evenly distributed and fixed on the circumferential surface of wheel disc 20 ; The blades in the blade group II 19 are in the shape of a curved S-curve, and the cross-sectional shape of the blades is wing-shaped; the motor 6, the rear guard 7, the impeller group B1 and the front guard 11 are arranged in order from back to front; the support rod group 9 is composed of 5 support rods, the rear ends of the 5 support rods are fixedly connected to the rear guard 7, and the front ends of the 5 support rods are fixedly connected to the front guard 11; the rear drive wheel assembly 8 is composed of a stepper motor I8a, a transmission box I8b and a drive wheel pair I8c, the rear end of the transmission box I8b is connected to the output end of the stepper motor I8a, and the left and right sides of the transmission box I8b are movably connected to the two drive wheels of the drive wheel pair I8c; the transmission box I8b is fixed to the support rod The rear ends of the two support rods at the bottom of the group 9 are below; the front drive wheel assembly 10 is composed of a stepper motor Ⅱ10a, a transmission box Ⅱ10b and a drive wheel pair Ⅱ10c, the rear end of the transmission box Ⅱ10b is connected to the output end of the stepper motor Ⅱ10a, and the left and right sides of the transmission box Ⅱ10b are movably connected to the two drive wheels of the drive wheel pair Ⅱ10c; the top of the transmission box Ⅱ10b is fixedly connected to the front ends of the two support rods at the bottom of the support rod group 9; the front part of the motor 6 is bolted to the rear shield 7, the output end of the motor 6 is fixedly connected to the rear end of the main shaft 21 in the axial impeller B3, and the front end of the main shaft 21 is interference connected to the inner ring of the bearing 16 of the front shield 11.

[0008] The ventilation control system D is composed of a temperature detection cable group C, a frequency conversion control box 22, a data acquisition module 23, a cloud map generation module 24, a data processing module 25, a data storage module 26 and a control execution module 27, wherein the temperature detection cable group C, the data acquisition module 23, the cloud map generation module 24, the data processing module 25, the control execution module 27 and the frequency conversion control box 22 are communicatively connected in sequence; the data acquisition module 23, the cloud map generation module 24 and the data processing module 25 are communicatively connected with the data storage module 26 respectively; the frequency conversion control box 22 is communicatively connected with the motor 6; the control execution module 27 is communicatively connected with the rear drive wheel group 8 and the front drive wheel group 10 of the fan assembly B.

[0009] A control method for a local precision ventilation system of a granary based on a built-in fan includes the following steps:

[0010] 1) Using the data acquisition module 23 and the temperature detection cable group C to collect grain temperature data in the granary 1;

[0011] 2) According to the measured grain temperature data, the statistical temperature is higher than the ventilation critical temperature T 0 The coordinates of the temperature measurement points are recorded as set A:

[0012] A={(x1,y1,z1),(x2,y2,z2),...};

[0013] 3) Based on the statistical set A, these temperature measurement points are spatially classified and divided to find the number of heat cores in the grain pile and the approximate spatial range of the heat cores. The cloud map generation module 24 is used to generate the temperature distribution cloud map of the XY, XZ and YZ planes of each heat core. The mathematical interpolation model used is as follows:

[0014]

[0015] Where: S n x is the interpolation function; x i is a given point, and its function value fx i It is known that f is a deterministic continuous function; x∈R d ;||xx i || is the Euclidean norm; λ i ∈R; n and b∈R d ; a∈R; φ is the radial basis function;

[0016] 4) The temperature distribution cloud diagrams of the three planes XY, XZ and YZ of each heat core are processed by the data processing module 25, and the process is as follows:

[0017] 4.1 Image Processing to Extract the Temperature Distribution Cloud Map of the Three Planes of the Heat Core The temperature is higher than T 0, recorded as set B, and then calculate the areas and coordinates of the center points of these three regions, recorded as set S and set C respectively:

[0018] B={B xy , B xz ,B yz},

[0019] S={S xy ,S xz , S yz},

[0020] C={(i1,j1),(i2,k1),(j2,k2)};

[0021] 4.2 Set the temperature of the hot core space to T 0 The isothermal surface is equivalent to an ellipsoid, and its projection in the XY, XZ and YZ planes is regarded as an ellipse, and the area of ​​the ellipse is equal to S xy , S xz and S yz , the lengths of the three main semi-axes of the ellipsoid, a, b and c, are calculated according to the following formulas:

[0022]

[0023] 4.3 The energy accumulated in the hot core area (heat Q) is calculated according to the following formula:

[0024]

[0025] Where: b is the bulk density of grain, T ave is the average temperature of region set B, C ave is the average temperature T ave The specific heat capacity of the lower grain;

[0026] 4.4 Given the expected ventilation time t, estimate the time required to reduce the core temperature to the critical temperature T according to the following formula: 0 Required air volume per unit time M;

[0027]

[0028] Where: T a is the inlet temperature of air; C a is the temperature T a The specific heat capacity of air at constant pressure is ρa is the temperature T a The density of the air below;

[0029] 4.5 Based on the center coordinate set C, estimate the center coordinate O of the hot core in three-dimensional space:

[0030] O=(i0,j0,k0).

[0031] 4.6 Repeat steps 4.1 to 4.5 for the remaining hot cores to calculate the required air volume per unit time and center coordinates for each hot core;

[0032] 5) The control execution module 27 is based on the hot core center coordinate i 0 and j 0 , control the rear drive wheel set 8 and the front drive wheel set 10 of the fan assembly B closest to it, drive the fan assembly B to move to the corresponding position, and at the same time, according to the air volume M per unit time required by the hot core, adjust the speed of the motor 6 of the fan assembly B through the frequency conversion control box 22 to perform local cooling and ventilation operations;

[0033] 6) After an interval of Δt, repeat steps 1) to 5) to calculate the number of heat cores, spatial position, residual heat, residual time, required air volume, etc., and adjust the start and stop, position and motor speed of the fan accordingly until the heat core disappears completely and the grain temperature drops to the critical temperature T 0 , the local cooling and ventilation operation is completed;

[0034] 7) The data storage module 26 automatically saves the original data, temperature distribution cloud map, heat accumulation of the heat core, spatial position, required air volume per unit time and other data in the above steps for subsequent query and use.

[0035] The beneficial effects of the present invention are:

[0036] 1. The present invention provides a local precision ventilation system for a grain silo with a built-in fan. By designing and developing a ventilation cage and a matching built-in fan assembly, the fan is placed inside a ventilation duct, so that ventilation operations can be performed on a local area of ​​a grain pile or a local heating area. The low-temperature airflow can enter the grain pile from the area closest to the operation demand area, which can reduce the impact of ventilation operations on grain in a normal storage state and greatly improve the quality and efficiency of ventilation operations.

[0037] 2. The control method of a local precise ventilation system of a granary with a built-in fan of the present invention integrates grain condition detection and ventilation operation control. According to the changes in the spatial position, volume and accumulated heat of the local heating area during the ventilation operation, the start and stop, speed and working position of the built-in fan are automatically adjusted online in real time. While achieving reasonable and precise ventilation and effectively controlling the grain temperature, it can reduce manpower and material input, reduce energy consumption and save the cost of ventilation operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a structural schematic diagram of a local precision ventilation system for a granary with a built-in fan;

[0039] Figure 2Schematic diagram of the relative positions of the ventilation cage and the fan assembly B;

[0040] Figure 3 It is a structural schematic diagram of ventilation cage group A;

[0041] Figure 4 It is a structural schematic diagram of the fan component B;

[0042] Figure 5 is a schematic structural diagram of a rear drive wheel assembly 8;

[0043] Figure 6 is a schematic structural diagram of the front drive wheel assembly 10;

[0044] Figure 7 It is a schematic diagram of the connection relationship between the rear shield 7, the front shield 11 and the support rod group 9;

[0045] Figure 8 It is a structural schematic diagram of the impeller group B1;

[0046] Fig. 9 It is a schematic diagram of the module structure of the ventilation control system D;

[0047] Fig.10 It is a flow chart of a control method of a local precision ventilation system for a granary with a built-in fan;

[0048] Among them: A. Ventilation cage group B. Fan assembly B1. Impeller group B2. Crossflow impeller B3. Axial flow impeller C. Temperature detection cable group D. Ventilation control system 1. Granary 2. Cylindrical body 3. Long hole group 4. Bracket pair 5. Slide 6. Motor 7. Rear guard 8. Rear drive wheel assembly 8a. Stepper motor I 8b. Transmission box I 8c. Drive wheel I 9. Support rod group 10. Front drive wheel assembly 10a. Stepper motor II 10b. Transmission box II 10c. Drive wheel II 11. Front guard 12. Spoke group 13. Bolt hole group 14. Fan-shaped hole group I 15. Fan-shaped hole group II 16. Bearing 17. Blade group 18. Ring plate group 19. Fan blade 20. Wheel disc 21. Main shaft 22. Frequency conversion control box 23. Data acquisition module 24. Cloud map generation module 25. Data processing module 26. Data storage module 27. Control execution module DETAILED DESCRIPTION

[0049] The present invention is described below with reference to the accompanying drawings.

[0050] like Figure 1 and Figure 2As shown, a local precision ventilation system for a granary with a built-in fan of the present invention is composed of a ventilation cage group A, a fan assembly B, a temperature detection cable group C and a ventilation control system D. The fan assembly B is located in a single ventilation cage of the ventilation cage group A. The single ventilation cage serves as both a component of the ventilation cage group A and a protective shell of the fan assembly B. The driving wheel pair Ⅰ8c of the rear driving wheel group 8 and the driving wheel pair Ⅱ10c of the front driving wheel group 10 to which the lower end support rod of the support rod group 9 in the fan assembly B are fixed are slidably connected to the slide groove 5 of the single ventilation cage of the ventilation cage group A. The fan-built-in granary local precision ventilation system is installed in the granary 1. The assembly of ventilation cage group A and fan assembly B is evenly distributed in parallel in the length direction of the granary 1 floor, and the spacing between two adjacent ones is 2-6m. In actual use, the number of ventilation cage groups A and the number of ventilation cages A in each group can be flexibly set according to the span and length of the granary 1; the temperature detection cable group C is arranged in a grid shape in the granary 1 according to the national standard GB / T 26882.1-2024, and is communicatively connected with the data acquisition module 23 of the ventilation control system D.

[0051] like Figure 3 As shown, the ventilation cage group A is composed of a plurality of ventilation cages with exactly the same structure, each of which is composed of a cylindrical body 2 and a pair of support plates 4. A slide groove 5 is longitudinally arranged in the front and rear directions of the lower part of the cylindrical body 2, in which the driving wheel pair Ⅰ8c of the rear driving wheel group 8 and the driving wheel pair Ⅱ10c of the front driving wheel group 10 can slide forward and backward, thereby changing the position of the fan assembly B in the ventilation cage group A; the two support plates of the support plate pair 4 are fixedly connected to the bottom of the cylindrical body 2 and are symmetrical to both sides of the slide groove 5 to prevent tipping and rolling during the grain feeding process; a long hole group 3 is provided on the wall of the cylindrical body 2, which is evenly arranged at equal intervals, and the low-temperature airflow can pass through these long strip holes and be sent into the grain pile.

[0052] like Figures 4 to 8As shown in the figure, the fan assembly B is composed of an impeller group B1, a motor 6, a rear shroud 7, a rear drive wheel group 8, a support rod group 9, a front drive wheel group 10, and a front shroud 11; the rear shroud 7 is provided with a spoke group 12, a bolt hole group 13, and a fan-shaped hole group I 14; the front shroud 11 is provided with a fan-shaped hole group II 15 and a bearing 16; the impeller group B1 is composed of a cross-flow impeller B2 and an axial-flow impeller B3. The cross-flow impeller B2 is composed of a blade group I 17 and an annular plate group 18. The blade group I 17 is composed of 4 - 5 layers of blades, with 32 blades in each layer, and they are evenly distributed on the circular ring surface of the annular plate; the annular plate group 18 is composed of 5 - 6 annular plates. The 4 - 5 layers of blades in the blade group I 17 are respectively located between every two of the 5 - 6 annular plates in the annular plate group 18. The blades in each layer are evenly distributed and fixedly connected on the annular surface of the annular plate, and the 4 - 5 layers of corresponding front and rear blades are on a straight line; the cross-sectional shape of the blades in the blade group I 17 is an arc shape, and the included angle between the tangent line of the midpoint of the arc and the connection line between the lower end of the blade and the center of the annular plate is 30°; the axial-flow impeller B3 is composed of a blade group II 19, a wheel disc 20, and a main shaft 21. The center of the wheel disc 20 is fixedly connected to the near front end of the main shaft 21; the inner ends of the 32 blades in the blade group II 19 are evenly distributed and fixedly connected to the circumferential surface of the wheel disc 20; the shape of the blades in the blade group II 19 is a curved S-shaped curve, and the cross-sectional shape of the blades is an airfoil shape; the motor 6, the rear shroud 7, the impeller group B1, and the front shroud 11 are arranged in sequence from the rear to the front; the rear drive wheel group 8 and the front drive wheel group 10 are respectively fixedly connected to the rear end and the front end of the lower support rods of the support rod group 9; the rear drive wheel assembly 8 is composed of a stepping motor I 8a, a transmission box I 8b, and a drive wheel pair I 8c. The rear end of the transmission box I 8b is connected to the output end of the stepping motor I 8a, and the left and right sides of the transmission box I 8b are movably connected to the two drive wheels of the drive wheel pair I 8c. The structural composition of the front drive wheel group 10 is exactly the same as that of the rear drive wheel group 8; the front part of the motor 6 is bolted to the rear shroud 7, the output end of the motor 6 is fixedly connected to the rear end of the main shaft 21 in the axial-flow impeller B3, and the front end of the main shaft 21 is in interference fit with the inner ring of the bearing 16 on the front shroud 11; the rear ends of the 5 support rods of the support rod group 9 are fixedly connected to the rear shroud 7, and the 5 support rods of the support rod group 9 are fixedly connected to the front shroud 11.

[0053] As Fig. 9 shown, the ventilation control system D is composed of a temperature detection cable group C, a frequency conversion control box 22, a data acquisition module 23, a cloud map generation module 24, a data processing module 25, a data storage module 26, and a control execution module 27. Among them, the temperature detection cable group C, the data acquisition module 23, the cloud map generation module 24, the data processing module 25, the control execution module 27, and the frequency conversion control box 22 are communicatively connected in sequence; the data acquisition module 23, the cloud map generation module 24, and the data processing module 25 are respectively communicatively connected to the data storage module 26. The frequency conversion control box 22 is communicatively connected to the motor 6; the control execution module 27 is communicatively connected to the rear drive wheel group 8 and the front drive wheel group 10 of the fan assembly B.

[0054] The control method of the fan built-in grain silo local precision ventilation system is as follows: Fig.10 As shown, the following steps are included:

[0055] 1) Using the data acquisition module 23 and the temperature detection cable group C to collect grain temperature data in the granary 1;

[0056] 2) According to the measured grain temperature data, the statistical temperature is higher than the ventilation critical temperature T 0 The coordinates of the temperature measurement points are recorded as set A:

[0057] A={(x1,y1,z1),(x2,y2,z2),...};

[0058] 3) Based on the statistical set A, these temperature measurement points are spatially classified and divided to find the number of heat cores in the grain pile and the approximate spatial range of the heat cores. The cloud map generation module 24 is used to generate the temperature distribution cloud map of the XY, XZ and YZ planes of each heat core. The mathematical interpolation model used is as follows:

[0059]

[0060] Where: S n x is the interpolation function; x i is a given point, and its function value fx i It is known that f is a deterministic continuous function; x∈R d ;||xx i || is the Euclidean norm; λ i ∈R; n and b∈R d ; a∈R; φ is the radial basis function;

[0061] 4) The temperature distribution cloud diagrams of the three planes XY, XZ and YZ of each heat core are processed by the data processing module 25, and the process is as follows:

[0062] 4.1 Image Processing to Extract the Temperature Distribution Cloud Map of the Three Planes of the Heat Core The temperature is higher than T 0 , recorded as set B, and then calculate the areas and coordinates of the center points of these three regions, recorded as set S and set C respectively:

[0063] B={B xy ,B xz , B yz},

[0064] S={S xy ,S xz , S yz},

[0065] C={(i1,j1), (i2,k1), (j2,k2)};

[0066] 4.2 Set the temperature of the hot core space to T 0 The isothermal surface is equivalent to an ellipsoid, and its projection in the XY, XZ and YZ planes is regarded as an ellipse, and the area of ​​the ellipse is equal to S xy , S xz and S yz , the lengths of the three main semi-axes of the ellipsoid, a, b and c, are calculated according to the following formulas:

[0067]

[0068] 4.3 The energy accumulated in the hot core area (heat Q) is calculated according to the following formula:

[0069]

[0070] Where: b is the bulk density of grain, T ave is the average temperature of region set B, C ave is the average temperature T ave The specific heat capacity of the lower grain;

[0071] 4.4 Given the expected ventilation time t, estimate the time required to reduce the core temperature to the critical temperature T according to the following formula: 0 Required air volume per unit time M;

[0072]

[0073] Where: T a is the inlet temperature of air; C a is the temperature T a The specific heat capacity of air at constant pressure, ρ a is the temperature T a The density of the air below;

[0074] 4.5 Based on the center coordinate set C, estimate the center coordinate O of the hot core in three-dimensional space:

[0075] O=(i0,j0,k0)

[0076] 4.6 Repeat steps 4.1 to 4.5 for the remaining hot cores to calculate the required air volume per unit time and center coordinates for each hot core;

[0077] 5) The control execution module 27 is based on the hot core center coordinate i 0 and j 0 , control the rear drive wheel set 8 and the front drive wheel set 10 of the fan assembly B closest to it, drive the fan assembly B to move to the corresponding position, and at the same time, according to the air volume M per unit time required by the hot core, adjust the speed of the motor 6 of the fan assembly B through the frequency conversion control box 22 to perform local cooling and ventilation operations;

[0078] 6) After an interval of Δt, repeat steps 1) to 5) to calculate the number of heat cores, spatial position, residual heat, residual time, required air volume, etc., and adjust the start and stop, position and motor speed of the fan accordingly until the heat core disappears completely and the grain temperature drops to the critical temperature T 0 , the local cooling and ventilation operation is completed;

[0079] 7) The data storage module 26 automatically saves the original data, temperature distribution cloud map, heat accumulation of the heat core, spatial position, required air volume per unit time and other data in the above steps for subsequent query and use.

Claims

1. A local precision ventilation system for granary with built-in fan, characterized by: The invention comprises a ventilation cage group (A), a fan assembly (B), a temperature detection cable group (C) and a ventilation control system (D), wherein the fan assembly (B) comprises an impeller group (B1), a motor (6), a rear guard (7), a rear drive wheel group (8), a support rod group (9), a front drive wheel group (10) and a front guard (11); the rear guard (7) is provided with a spoke group (12), a bolt hole group (13) and a fan-shaped hole group I (14); the front guard (11) is provided with a fan-shaped hole group II (15) and a bearing (16); the impeller group (B1) comprises a cross-flow impeller (B2) and an axial flow impeller (B3); the cross-flow impeller (B2) comprises a blade group I (17) and an annular plate group (18); the blade group I (17 ) is composed of 4-5 layers of blades, each layer has 32 blades, and the blades are evenly distributed on the annular surface of the annular plate; the annular plate group (18) is composed of 5-6 annular plates, the 4-5 layers of blades of the blade group I (17) are respectively located between every two layers of the 5-6 annular plates of the annular plate group (18), the blades of each layer are evenly distributed and fixed on the annular surface of the annular plate, and the front and rear corresponding blades of the 4-5 layers are on a straight line; the cross-sectional shape of the blades in the blade group I (17) is an arc shape, and the angle between the tangent line of the arc midpoint and the line connecting the lower end of the blade and the center of the annular plate is 30°; the axial flow impeller (B3) is composed of the blade group II (19), the wheel disk (20) and the main shaft (21), and the center of the wheel disk (20) is fixed to the near front end of the main shaft (21); The inner ends of the 32 blades of the blade group II (19) are evenly distributed and fixedly connected to the circumferential surface of the wheel disc (20); the blades in the blade group II (19) are in the shape of a curved S-curve, and the cross-sectional shape of the blades is in the shape of a wing; the motor (6), the rear guard (7), the impeller group (B1) and the front guard (11) are arranged in sequence from back to front; the support rod group (9) is composed of 5 support rods, the rear ends of the 5 support rods are fixedly connected to the rear guard (7), and the front ends of the 5 support rods are fixedly connected to the front guard (11); the rear driving wheel assembly (8) is composed of a stepping motor I (8a), a transmission The transmission box I (8b) is composed of a transmission box I (8b) and a driving wheel pair I (8c), the rear end of the transmission box I (8b) is connected to the output end of the stepper motor I (8a), and the left and right sides of the transmission box I (8b) are movably connected to the two driving wheels of the driving wheel pair I (8c); the upper surface of the transmission box I (8b) is fixedly connected to the lower rear ends of the two support rods at the lower part of the support rod group (9); the front driving wheel assembly (10) is composed of a stepper motor II (10a), a transmission box II (10b) and a driving wheel pair II (10c), the rear end of the transmission box II (10b) is connected to the output end of the stepper motor II (10 ... The output end is connected, and the left and right sides of the transmission box II (10b) are movably connected to the two driving wheels of the driving wheel pair II (10c); the upper side of the transmission box II (10b) is fixedly connected to the lower side of the front ends of the two supporting rods at the lower part of the supporting rod group (9); the front part of the motor (6) is bolted to the rear shield (7), the output end of the motor (6) is fixedly connected to the rear end of the main shaft (21) in the axial flow impeller (B3), and the front end of the main shaft (21) is interference-connected with the inner ring of the bearing (16) of the front shield (11); the fan assembly (B) is located at a single ventilation cage group (A) In the cage, the driving wheel pair I (8c) of the rear driving wheel assembly (8) and the driving wheel pair II (10c) of the front driving wheel assembly (10) in the fan assembly (B) are slidably connected to the slide groove (5) of the ventilation cage; the fan built-in grain silo local precision ventilation system is arranged in the grain silo (1), the assembly of the ventilation cage group (A) and the fan assembly (B) is evenly distributed in parallel in the length direction of the grain silo (1) floor, and the distance between two adjacent assemblies of the ventilation cage group (A) and the fan assembly (B) is 2-6m; the temperature detection cable group (C) is arranged according to GB / T 26882.1-2024 National Standard, arranged in a grid in the granary (1), and communicatively connected to the data acquisition module (23) of the ventilation control system (D); the frequency conversion control box (22) of the ventilation control system (D) is communicatively connected to the motor (6) of the fan assembly (B); the control execution module (27) of the ventilation control system (D) is communicatively connected to the rear drive wheel assembly (8) and the front drive wheel assembly (10) of the impeller assembly (B1) in the fan assembly (B).

2. The fan-built-in granary local precision ventilation system according to claim 1 is characterized by: The ventilation cage group (A) is composed of ventilation cages with completely identical structures. Each ventilation cage is composed of a cylindrical body (2) and a pair of support plates (4). A slide groove (5) is longitudinally arranged in the front and rear directions of the lower part of the cylindrical body (2). The two support plates of the pair of support plates (4) are fixedly connected to the bottom of the cylindrical body (2) and are symmetrical to the two sides of the slide groove (5). The wall of the cylindrical body (2) is provided with a group of long holes (3) which are evenly arranged at equal intervals.

3. The fan-built-in granary local precision ventilation system according to claim 1 is characterized by: The ventilation control system (D) is composed of a temperature detection cable group (C), a frequency conversion control box (22), a data acquisition module (23), a cloud map generation module (24), a data processing module (25), a data storage module (26) and a control execution module (27), wherein the temperature detection cable group (C), the data acquisition module (23), the cloud map generation module (24), the data processing module (25), the control execution module (27) and the frequency conversion control box (22) are sequentially connected in communication; the data acquisition module (23), the cloud map generation module (24) and the data processing module (25) are respectively connected in communication with the data storage module (26); the frequency conversion control box (22) is connected in communication with the motor (6); and the control execution module (27) is connected in communication with the rear drive wheel group (8) and the front drive wheel group (10) of the fan assembly (B).

4. A control method for the local precision ventilation system of a granary with built-in fans according to claim 1, characterized in that it comprises the following steps: 1) using a data acquisition module (23) and a temperature detection cable group (C) to collect grain temperature data in a granary (1); 2) According to the measured grain temperature data, the coordinates of the temperature measurement points whose temperature is higher than the ventilation critical temperature T0 are counted and recorded as set A: A={(x1, y1, z1), (x2, y2, z2),...}; 3) Based on the statistical set A, these temperature measurement points are spatially classified and divided to find the number of heat cores in the grain pile and the approximate spatial range of the heat cores. The cloud map generation module (24) is used to generate the temperature distribution cloud map of the XY, XZ and YZ planes of each heat core. The mathematical interpolation model used is as follows: Where: S n (x) is the interpolation function; x i is a given point, and its function value f(x i ) It is known that f is a deterministic continuous function; x∈R d ;||xx i || is the Euclidean norm; λ i ∈R; n and b∈R d ; a∈R; φ is the radial basis function; 4) The temperature distribution cloud diagrams of the three planes XY, XZ and YZ of each heat core are processed by using the data processing module (25), and the process is as follows: 4.1 Image Processing Extract the areas with temperature higher than T0 in the three plane temperature distribution cloud maps of the heat core, record them as set B, then calculate the areas and coordinates of the center points of these three areas, record them as set S and set C respectively: B={B xy ,B xz ,B yz }, S={S xy ,S xz ,S yz }, C=(i1, j1), (i2, k1), (j2, k2)}; 4.2 The isothermal surface with temperature T0 in the hot core space is equivalent to an ellipsoid, and its projection in the XY, XZ and YZ planes is regarded as an ellipse, and the area of ​​the ellipse is equal to S xy , S xz and S yz , the lengths of the three main semi-axes of the ellipsoid, a, b and c, are calculated according to the following formulas: 4.3 The energy (heat) Q accumulated in the hot core area is calculated according to the following formula: Where: b is the bulk density of grain, T ave is the average temperature of region set B, C ave is the average temperature T ave The specific heat capacity of the lower grain; 4.4 Given the expected ventilation time t, estimate the air volume per unit time M required to reduce the heat core temperature to the critical temperature T0 according to the following formula; Where: T a is the inlet temperature of air; C a is the temperature T a The specific heat capacity of air at constant pressure, ρ a is the temperature T a The density of the air below; 4.5 Based on the center coordinate set C, estimate the center coordinate O of the hot core in three-dimensional space: O = (i0, j0, k0); 4.6 Repeat steps 4.1 to 4.5 for the remaining hot cores to calculate the required air volume per unit time and center coordinates for each hot core; 5) The control execution module (27) controls the rear drive wheel group (8) and the front drive wheel group (10) of the fan assembly (B) closest to the hot core according to the center coordinates i0 and j0 of the hot core, drives the fan assembly (B) to move to the corresponding position, and at the same time, according to the air volume M per unit time required by the hot core, adjusts the speed of the motor (6) of the fan assembly (B) through the frequency conversion control box 22 to perform local cooling and ventilation operations; 6) At an interval of Δt, repeat steps 1) to 5) to calculate the number of heat cores, spatial position, residual heat, residual time, required air volume, etc., and adjust the start and stop, position and motor speed of the fan accordingly, until the heat core completely disappears and the grain temperature drops to the critical temperature T0, and the local cooling and ventilation operation is completed; 7) The data storage module (26) automatically saves the original data, temperature distribution cloud map, heat accumulation of the heat core, spatial position, required air volume per unit time and other data in the above steps for subsequent query and use.

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