An energy consumption prediction and optimization method for a crop straw crusher considering the material crushing process

Abstract

The present invention discloses an energy consumption prediction and optimization method for a crop straw crushing and rubbing machine considering the material crushing process, including: establishing a power consumption prediction model for the crop straw crushing and rubbing machine; determining the parameters of the power consumption prediction model for the crop straw crushing and rubbing machine; substituting the parameters of the power consumption prediction model for the crop straw crushing and rubbing machine into the power consumption prediction model for the crop straw crushing and rubbing machine, calculating the energy consumption of the crop straw crushing and rubbing machine considering the material crushing process and verifying through experiments; calculating and analyzing the sensitivity of the influence of different structures and working parameters on the total energy consumption of the crop straw crushing and rubbing machine, obtaining the influence law of the structure and working parameters on the total energy consumption of the crop straw crushing and rubbing machine; conducting multi-objective optimization design on the crop straw crushing and rubbing machine to obtain the optimal combination of the structure and working parameters of the crop straw crushing and rubbing machine. The present invention provides guidance for the optimal design of low power consumption and high power output of the straw crusher / crusher.

Description

Technical Field

[0001] The present invention belongs to the field of performance prediction and analysis of crop straw harvesting and processing machinery, and particularly relates to an energy consumption prediction and optimization method for a crop straw crusher considering the material crushing process. Background Technique

[0002] The crop straw crusher with independent intellectual property rights in China can process materials such as crop straws into soft filamentous segments, which is convenient for livestock to eat and digest, and can improve the utilization rate of straws, promoting the resource utilization of straws. When the crop straw crusher works, there are problems such as high power consumption and low power generation per unit of electricity, which seriously restrict the development of such equipment towards high quality and low energy consumption.

[0003] At present, the energy consumption research of such machinery mostly adopts experimental methods. If the measured energy consumption is too high or the power generation per unit of electricity is too low and cannot meet the national standard requirements, it is necessary to adjust the structural parameters of the machine, re-develop the prototype and conduct multiple experiments to determine whether it meets the national standard requirements. There are problems such as long design and R & D cycles and high costs. Due to the limitations of the experimental research method, the energy consumption mechanism and main influencing factors of such machinery are not clear; the coupling effect of air flow - scattered materials - mechanical structure during the process of crushing materials by the crop straw crusher makes the analysis of the energy consumption and power generation per unit of electricity of the machine very complicated, and there is no reported exploration and research in this regard. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention proposes an energy consumption prediction and optimization method for a crop straw crusher considering the material crushing process. By using a method combining theoretical analysis, computational fluid dynamics (CFD) technology, discrete element method (DEM) technology and experiments, it can accurately, low-costly and quickly predict and optimize the energy consumption and power generation per unit of electricity during the process of crushing materials by the crop straw crusher. The corresponding prediction method provides a method reference for the low-energy consumption optimization design of crop straw processing machinery such as crop straw crushers / filament machines, crushers and chaff cutters, and has relatively important application value for the development of such machinery towards green and low energy consumption.

[0005] To achieve the above object, the present invention provides the following solution:

[0006] An energy consumption prediction and optimization method for a crop straw crusher considering the material crushing process, comprising the following steps:

[0007] S1: By using the method of theoretical derivation, combining the coupling effect of materials, air flow and mechanical structure and the material crushing mechanism, establish a power consumption prediction model for the crop straw crusher;

[0008] S2: Determine the parameters of the power consumption prediction model for the crop straw crusher;

[0009] S3: Substitute the parameters of the power consumption prediction model of the crop straw crusher into the power consumption prediction model of the crop straw crusher to calculate the energy consumption of the crop straw crusher considering the material crushing process;

[0010] S4: Use the verified power consumption prediction model of the crop straw crusher to calculate and analyze the sensitivity of the influence of different structures and working parameters on the total energy consumption of the crop straw crusher, and obtain the influence law of the structure and working parameters on the total energy consumption of the crop straw crusher;

[0011] S5: Based on the influence law of the structure and working parameters on the total energy consumption of the crop straw crusher, conduct multi-objective optimization design on the crop straw crusher to obtain the optimal combination of the structure and working parameters of the crop straw crusher.

[0012] Preferably, the power consumption prediction model of the crop straw crusher includes: the power consumption model of the chopping material process, the power consumption model of the hammer hitting and the tooth plate rubbing the material process, the power consumption model of the energy consumed to make the material have a certain mechanical energy, the power consumption model of the energy consumed to make the air have a certain static pressure and flow rate, and the power consumption model of the energy consumed by the vibration of the straw crusher body.

[0013] Preferably, the method for establishing the power consumption model of the chopping material process includes:

[0014] Through the force analysis of the straw during the chopping process by the chopper, derive the total resistance of the straw material on the chopper per unit cutting length in the chopping direction;

[0015] Based on the total resistance of the straw material on the chopper per unit cutting length in the chopping direction and the effective cutting length of the straw, obtain the total reaction force of the straw on the chopper along the chopping direction;

[0016] Based on the total reaction force of the straw on the chopper along the chopping direction, derive the energy consumed by the chopper to chop the material per unit time, and then establish the power consumption model of the chopping material process;

[0017] Among them,

[0018] In the formula, E c is the energy consumed by the chopper to chop the material per unit time, m in is the feeding amount of the straw within 1 s, m s is the mass of a section of chopped straw, R yL is the total reaction force of the straw on the chopper in the y direction, is the arc length rotated by the contact point between the chopper and the straw when chopping a section of straw, and is t 0 is the time required for the chopper from the start of chopping to the complete fracture of the straw, w is the rotational speed of the rotor where the chopper is located, a is the distance from the center of the straw to the center of rotation of the rotor, r is the radius of the radial cross-section of the straw, TK is the tip thickness, σ y is the compressive stress of the blade on the stalk along the y direction, E is the elastic modulus of the straw material, (θ + ξ) is the sum of the blade inclination angle and the cutter bar installation angle, u w is the internal friction coefficient of the extruded straw layer, v is the Poisson's ratio of the straw material, u is the friction coefficient between the straw and the blade surface material, w is the rotational speed of the rotor where the cutter bar is located, a is the distance from the straw center to the center of rotation of the rotor.

[0019] Preferably, the method for establishing the power consumption model of the process of the hammer hitting and the toothed plate rubbing the material includes:

[0020]

[0021] In the formula, E b is the energy consumed by the hammer hitting and the toothed plate rubbing to break the material per unit time, m in is the feeding amount of straw per second, m s is the mass of a section of straw cut, K 1 is the proportionality coefficient, that is, the work required for a new unit surface area, J / mm 2 , ΔS is the new surface area of the material, r st is the equivalent radius of the shredded filamentous straw after crushing, h st is the equivalent length of the shredded filamentous straw after crushing, ρ is the density of the straw, r is the radius of the radial cross-section of the straw, κ is the slip cutting rate of the cutter bar, v in is the feeding speed of the straw under actual working conditions, λ is the number of cutter bars, n is the rotational speed of the rotor.

[0022] Preferably, the method for establishing the power consumption model of the energy consumed to make the material have a certain mechanical energy includes:

[0023]

[0024] In the formula, E me is the energy consumed to make the straw material have a certain mechanical energy during the material crushing process per unit time, m in is the feeding amount of straw per second, H is the height of the material feeding position from the cross-section B at the outlet of the discharge pipe, is the average speed of the material at cross-section B, that is, the average speed of the material leaving the discharge pipe, v in is the feeding speed of the straw under actual working conditions, E ce is the energy loss due to the collision of the material with the material, the hammer, the toothed plate and the inner wall of the casing in the crushing chamber.

[0025] Preferably, the method for establishing the power consumption model of the energy consumed to make the air have a certain static pressure and flow rate includes:

[0026]

[0027] In the formula, E air is the energy consumed by the rotation of the rotor of the straw crusher per unit time to make the air have a certain static pressure and flow velocity, Q a is the air mass flow rate at section A per unit time, P a is the static pressure of the air flow at section B, ρ air is the density of the air flow, V a is the flow velocity of the air flow at section B.

[0028] Preferably, the method for establishing the power consumption model of the energy consumed by the vibration of the straw crusher body includes:

[0029] E v = E no-load - E air - E f ,

[0030] In the formula, E v is the energy consumed by the vibration of the straw crusher body per unit time, E no-loud is the energy consumed by the crusher per unit time under no-load conditions, E f is the energy consumed by the friction between the bearing and the rotor shaft per unit time, E air is the energy consumed by the rotation of the rotor of the crusher per unit time to make the air have a certain static pressure and flow velocity.

[0031] Preferably, based on the influence law of the above structure and working parameters on the total energy consumption of the crop straw crusher, the method for multi-objective optimization design of the crop straw crusher includes:

[0032] Taking the lowest total energy consumption and the highest power generation per degree of the crop straw crusher as the optimization objectives, taking the structure and working parameters that are sensitive to the optimization objectives as the optimization design variables, and taking meeting the quality of shredded silk and the machine structure size as the constraint conditions for multi-objective optimization design, the best combination of the structure and working parameters of the crop straw crusher is obtained.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] The present invention adopts a method combining theoretical analysis, computational fluid dynamics CFD technology, discrete element DEM technology and experiments, which can accurately, low-costly and quickly predict and optimize the energy consumption and power generation per degree in the process of crushing materials by the crop straw crusher. The corresponding prediction method provides a method reference for the low-energy consumption optimization design of crop straw processing machinery such as crop straw shredding / filament machines, crushers and hay cutters, and has relatively important application value for the development of such machinery towards green and low-energy consumption. Description of the Drawings

[0035] To more clearly illustrate the technical solutions of the present invention, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0036] Figure 1 Schematic diagram of the structure of the crop straw crusher according to an embodiment of the present invention;

[0037] Figure 2 Diagram of the movement position and force analysis during the process of the guillotine cutting straw according to an embodiment of the present invention;

[0038] Figure 3 Schematic diagram of the entire process of crushing movement according to an embodiment of the present invention;

[0039] Figure 4 Flow chart of the power consumption analysis of the crop straw crusher according to an embodiment of the present invention;

[0040] Figure 5 Diagram of the energy consumption proportion of the crop straw crusher according to an embodiment of the present invention;

[0041] Figure 6 Diagram comparing the crop energy consumption test results with the theoretical calculation according to an embodiment of the present invention;

[0042] Figure 7 Schematic diagram of the parameter sensitivity analysis according to an embodiment of the present invention.

[0043] Description of the accompanying drawings: 1. Feed chute; 2. Fixed knife; 3. Rotor system; 4. Tooth plate; 5. Lower housing; 6. Upper housing; 7. Discharge pipe; 8. Guillotine; 9. Hammer frame plate; 10. Main shaft; 11. Pin shaft; 12. Hammer piece; 13. Pin shaft; 14. Throwing leaf plate. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0045] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0046] Embodiment 1

[0047] The present invention provides a method for predicting and optimizing the energy consumption of a crop straw crushing machine considering the material crushing process, which includes the following steps:

[0048] In the first step, according to the working principle of the machine, the total energy consumed during the operation of the crop straw crushing machine is divided into five parts: the energy consumed by the cutter to cut the material, the energy consumed by the hammer to strike and the toothed plate to rub and crush the material, the energy consumed to give the material a certain mechanical energy, the energy consumed to give the air in the crushing machine a certain static pressure and flow rate, and the energy consumed by the whole machine vibration. By using the method of theoretical derivation, combined with the coupled action of materials, air flow and mechanical structure and the material crushing mechanism, mathematical models of the above five parts of energy consumption are established.

[0049] (1) Energy consumption model of the cutter cutting the material

[0050] To accurately predict the energy consumption of the crushing machine, it is necessary to analyze the energy consumed during the material cutting process. When the whole straw material is fed from the feeding port into the crushing chamber, the cutter at the feeding port acts on the material to make it deformed, and when the stress on the material exceeds its strength limit, it breaks. The energy consumed by the cutter to cut the straw material is the energy consumed by the reaction force of the straw on the cutter during the cutting process.

[0051] First of all, from the force analysis during the process of the cutter cutting the straw, the total resistance R of the straw material on the cutter per unit cutting length in the cutting direction (y direction, attached Figure 2 ) can be deduced as y For

[0052]

[0053] In the formula, the reaction force component F of the straw on the blade surface Ry , the friction force component F of the straw on the blade surface f1 cos(θ + ξ), the reaction force component F of the straw on the tip of the cutter Sy and the friction force F of the straw on the tip of the cutter f2 , r is the radius of the radial cross-section of the straw, T K is the tip thickness of the cutter, σ y is the compressive stress of the blade on the stem in the y direction, E is the elastic modulus of the straw material, (θ + ξ) is the sum of the blade inclination angle and the cutter installation angle, u w is the internal friction coefficient of the extruded straw layer, v is the Poisson's ratio of the straw material, and u is the friction coefficient between the straw and the blade surface material.

[0054] Secondly, when the effective cutting length of the straw is L(t), the total reaction force of the straw on the cutter in the y direction is

[0055] R yL = R y L(t) (2)

[0056] Among them, the effective cutting length L(t) of the straw during the cutting process by the guillotine is a quantity that varies with time (Appendix Figure 2 ), and it can be deduced as

[0057]

[0058] In the formula, w is the rotational speed of the rotor where the guillotine is located, and a is the distance from the center of the straw to the center of rotation of the rotor.

[0059] Finally, from formulas (1), (2), and (3), the energy E consumed by the guillotine to cut the material per unit time (1 s) can be deduced c as:

[0060]

[0061] In the formula, m in is the feeding amount of the straw within 1 s, m s is the mass of a section of cut straw, is the arc length rotated by the contact point between the guillotine and the straw when cutting a section of straw, and is t 0 is the time required for the guillotine from the start of cutting to the complete fracture of the straw, w is the rotational speed of the rotor where the guillotine is located, and a is the distance from the center of the straw to the center of rotation of the rotor.

[0062] (2) Energy model for the consumption of energy in crushing the straw material by the impact of the hammer blades and the rubbing of the toothed plates

[0063] After the straw cut into sections enters the crushing chamber, the impact method of the hammer blades, the rubbing method of the toothed plates, and the collision angle will all affect the consumed energy, and these factors are all random. For simplicity of calculation, the area theory proposed by Rittinger is adopted, that is, the work required for crushing is mainly used to increase the new surface area for calculation. Therefore, the energy consumed by the impact of the hammer blades and the rubbing of the toothed plates to crush the material is proportional to the newly added surface area of the material, and is

[0064] ΔE b = K 1 ΔS (5)

[0065] In the formula, ΔE b is the energy consumed by the newly added surface area ΔS of the material, J; K 1 is the proportionality coefficient, that is, the work required for adding a unit surface area, J / mm 2 .

[0066] Suppose the cut straw section is a cylinder with a radius r and a length L st , and the crushed filamentous straw section is an equivalent radius r st and an equivalent length h stFor a cylinder, the newly added surface area ΔS is

[0067]

[0068] In the formula, n st is the number of filamentous straw particles after a section of straw cut by the guillotine is crushed, S st is the surface area of a single filamentous straw segment after crushing, r st is the equivalent radius of the filamentous straw segment after crushing, h st is the equivalent length of the filamentous straw segment after crushing, ρ is the density of the straw, κ is the slip cutting rate of the guillotine, v in is the feeding speed of the straw under actual working conditions, λ is the number of guillotines, and n is the rotor speed. Among them, the equivalent radius and equivalent length of the filamentous straw particles, and the number of filamentous straw particles after a section of straw cut by the guillotine is crushed can all be obtained by numerically calculating the multi-coupled flow field of material-air-mechanical structure in the crop straw crusher considering the material crushing process by using the DEM-BPM-CFD coupling method.

[0069] From formulas (5) and (6), the energy E consumed by the hammer blade hitting and the tooth plate rubbing to break the material per unit time (1 s) can be deduced as b being

[0070]

[0071] (3) Energy model for consuming energy to make the material have a certain mechanical energy

[0072] The energy consumed to make the straw material have a certain mechanical energy during the material crushing process includes the kinetic energy and potential energy required for the material to leave the discharge pipe to meet the requirements that the material can be smoothly thrown out and have a certain throwing height and be connected with the transport vehicle. In addition, it also includes the energy consumed by the collision of the material with the material, the hammer blade, the tooth plate, and the inner wall of the machine shell. Let the energy consumed per unit time (1 s) be E me , then

[0073]

[0074] In the formula, H is the height of the material feeding position from the outlet of the discharge pipe (section B), is the average velocity of the material at section B, that is, the average velocity of the material leaving the discharge pipe (which can be measured by the high-speed camera test of the discharge pipe), and E ce is the energy loss of the material colliding with the material, the hammer blade, the tooth plate, and the inner wall of the machine shell in the crushing chamber.

[0075] (4) Energy model for consuming energy to make the air have a certain static pressure and flow velocity

[0076] The rotation of the rotor of the straw crusher disturbs the air, making it have a certain static pressure and flow velocity, which also consumes a certain amount of energy. The energy consumed per unit time (1 s) is E air 。

[0077]

[0078] In the formula, Q a is the air mass flow rate at section A per unit time (1 s), and P a is the static pressure of the air flow at section B (which can be obtained through actual measurement), ρ air is the density of the air flow, and V a is the flow velocity of the air flow at section B (which can be obtained through actual measurement).

[0079] (5) Energy consumption model of the vibration of the straw crusher body

[0080] When the crusher is working, the vibration of the casing will also consume a certain amount of energy. Let the energy consumed per unit time (1 s) be E v . Since in the case of the crusher running without load, the main energy consumption includes the energy consumed to make the air have a certain static pressure and flow velocity, the energy loss due to the vibration of the casing, and the energy consumed by the friction between the bearing and the rotor shaft, then per unit time (1 s), there is

[0081] E no-load =E v +E air +E f (10)

[0082] In the formula, E no-loud is the energy consumed by the crusher per unit time (1 s) under no-load conditions, and E f is the energy consumed by the friction between the bearing and the rotor shaft per unit time (1 s), which can be calculated by the Palmgren A bearing power consumption calculation formula.

[0083] Therefore, E v is

[0084] E v =E no-load -E air -E f (11)

[0085] Let the total energy consumed by the crusher per unit time (1 s) during stable operation be E 0 , then

[0086] E 0 =E c +E b +E me +E air +E v (12)

[0087] Then, according to the feeding rate, the electricity production per unit energy consumption can be further deduced, that is, the production (feeding rate) of unit energy consumption (converted to electricity per unit).

[0088]

[0089] In the second step, in order to calculate the energy consumption using the above-established mathematical model, methods such as experiments on the intrinsic parameters of crop straw, high-speed photography experiments, air flow velocity and static pressure experiments, etc. are adopted. Combining with the numerical calculation method of multi-coupled flow fields in the crop straw crusher considering the material crushing process, that is, the DEM-BPM-CFD coupling method, the undetermined parameters in the energy mathematical model of the five parts of the crusher are measured and calculated.

[0090] In the third step, the determined undetermined parameters are substituted into the established mathematical model for energy consumption calculation, and the established energy consumption prediction model is verified through the energy consumption experiment of the crusher.

[0091] In the fourth step, in order to match the structure and working parameters of the crop straw crusher to reduce the energy consumption during the material crushing process, it is necessary to explore the influence law of the structure and working parameters on the energy consumption of the crusher. Using the verified energy consumption mathematical model, calculate and analyze the sensitivity of the influence of different structures and working parameters on the total energy consumption of the crusher, and obtain the influence law of the structure and working parameters on the total energy consumption of the forage crusher.

[0092] In the fifth step, with the lowest total energy consumption and the highest electricity production per unit energy consumption of the crop straw crusher as the optimization objectives, the structures and working parameters that are more sensitive to the optimization objectives as the optimization design variables, and the silk quality, machine structure size, etc. as the constraint conditions, multi-objective optimization design is carried out to find the best combination of the structure and working parameters of the crusher, so as to reduce the total energy consumption of the crop straw crusher and improve its electricity production per unit energy consumption.

[0093] This method provides guidance for the optimization design of straw crushers / crushers with low power consumption and high electricity production per unit energy consumption, and has important application value for the development of such machinery towards the direction of green and low energy consumption.

[0094] Embodiment 2

[0095] As shown in the appendix Figure 1 It is composed of a feeding trough 1, a fixed knife 2, a rotor system 3, a tooth plate 4, a lower housing 5, an upper housing 6, a discharge pipe 7, etc. Among them, the rotor system 3 is composed of a chopping knife 8, a hammer frame plate 9, a main shaft 10, a pin shaft 11, a hammer piece 12, a sleeve 13 and a throwing vane 14. Its working principle is: when the machine is working, the straw is fed into the feeding trough 1, cut into sections by the fixed knife 2 and the chopping knife 8, and then enters the inner cavity of the crusher. Under the impact of the high-speed rotating hammer pieces 12 and the rubbing action of the tooth plate 4 on the inner walls of the upper housing 6 and the lower housing 5, it is crushed into filamentous sections. Under the combined action of the air flow and the throwing vane 14, it is thrown out of the forage crusher through the discharge pipe 7.

[0096] Taking the 9R-50A straw crusher developed by Inner Mongolia University of Technology as an example. The matching power of this crusher is 5.5 kW, the maximum working diameter of the rotor is 500 mm, the inner cavity diameter of the cylindrical casing is 630 mm and the width is 300 mm, and the height H of the discharge pipe d is 630 mm, the number of cutters λ is 4, and the number of hammer pieces H N is 24. The number of axial distribution groups G of the hammer pieces N is 4 groups, the thickness T of the cutter blade K is 6 mm, and the installation angle ξ and the blade inclination angle θ of the cutter are 10° and 30° respectively; the mass of the rotor is 19.765 kg, and the bearing is a 7006C type angular contact ball bearing; the material of the crusher casing is Q235, the material of the rotor is 45 steel, and the materials of the hammer pieces and cutters are 65Mn; the rotational speed of the straw crusher rotor is 2400 r / min, and the straw feeding amount m in is 0.3 kg / s, and the feeding speed v in is 2 m / s; the straw to be processed is the Meidan 337 yellow corn straw harvested in Inner Mongolia in the autumn of 2023.

[0097] Appendix Figure 4 is a flow chart of a method for analyzing the power consumption of a straw crusher considering the material crushing process provided by an embodiment of the present invention.

[0098] As Figure 4 shown, a method for analyzing the power consumption of a straw crusher considering the material crushing process provided by the present invention includes the following steps:

[0099] S1 Establishment of a power consumption prediction model for a crop straw crusher

[0100] S11 Establishment of a power consumption model for the process of cutting materials

[0101] To accurately establish the power consumption model for the process of cutting straw by the straw crusher, it is first necessary to analyze the force and motion process during the cutting of straw. The force and motion process can be seen in the appendix Figure 2 ; secondly, since the effective cutting length L(t) is not considered in the force analysis process, it is necessary to analyze the force considering the effective cutting length L(t); then, the work done by the resistance during the process of cutting straw once is calculated by the accumulation of force on displacement, and finally, the energy consumed during the cutting process is calculated by counting the mass of a section of cut straw and the feeding amount per unit time (1 s). The detailed process can be seen in step (1) of the first step of Embodiment 1.

[0102] S12 Establishment of a power consumption model for the process of hammer hitting and tooth plate rubbing materials

[0103] Due to the complexity of the movement of straw in the crushing chamber, and the main forms of straw crushing in the crushing chamber are hammer impact and tooth plate rubbing, the area theory proposed by Rittinger is adopted, that is, the work required for crushing is mainly used to increase the new surface area for calculation. Therefore, the energy consumed by hammer impact and tooth plate rubbing to break the material is proportional to the newly increased surface area of the material. For the detailed process, see step (2) in the first step of Embodiment 1.

[0104] Establishment of the power consumption model for the energy consumed to give the material a certain mechanical energy

[0105] Since the straw material needs a certain kinetic energy and potential energy to leave the discharge pipe, and at the same time the straw material belongs to a viscoelastic material, the collision between the material and the material, the rotor and the casing needs to consume a certain amount of energy. Therefore, the energy in this process is mainly composed of three parts. For the detailed process, see step (3) in the first step of Embodiment 1.

[0106] Establishment of the power consumption model for the energy consumed to give the air a certain static pressure and flow rate

[0107] The rotation of the rotor will disturb the flow field in the crushing chamber, making the flow field in the crushing chamber have a certain amount of energy. For the detailed process, see step (4) in the first step of Embodiment 1.

[0108] Establishment of the power consumption model for the energy consumed by the vibration of the straw crusher body

[0109] Since the vibration of the crop straw crusher will be affected by many factors, in this patent, the energy consumed by the vibration of the crusher body is indirectly calculated by measuring the energy consumed under no-load conditions (the energy consumed by the crusher under no-load is equal to the sum of the energy consumed by the vibration of the body, the energy consumed to give the material a certain mechanical energy, and the energy consumed by bearing friction). For the detailed process, see step (5) in the first step of Embodiment 1.

[0110] S2. Determination of the undetermined parameters of the power consumption prediction model of the crop straw crusher

[0111] S21. Determination of the parameters of the power consumption model in the process of cutting materials

[0112] In order to determine the parameters of the power consumption model in the process of cutting straw by the straw crusher, it is necessary to measure the intrinsic parameters of the cut straw, the structural parameters and the motion parameters of the straw crusher. In order to eliminate the difference in material properties between the inner core and the outer skin of the straw, the area method adopted by Xu Huanhuan et al. in the article "Tensile Stiffness of Hybrid Fiber Composites" is used to correct the intrinsic parameters of the straw. The intrinsic parameters of the straw required for cutting are as follows: the compressive stress σ of the straw segment along the y direction y is 0.2369 MPa, the corrected elastic modulus E of the straw segment is 371.3004 MPa, the corrected Poisson's ratio v is 0.3584, and the corrected internal friction coefficient u wis 0.7289, and the corrected friction coefficient μ between the straw and the cutter material is 0.6472; among them, the operating parameters of the straw crusher are: the distance a from the center of the cross-section of the straw to the center of rotation of the cutter is 180 mm, and the cutter rotates approximately 8° when cutting a section of straw, and the time t 0 is 5.56×10 -4 s, and the average mass m of a single section of straw after cutting s is 3.2815×10 -3 kg.

[0113] S22. Determination of parameters of the power consumption model for the process of the hammer hitting and the toothed plate rubbing the material

[0114] It can be known from the actual measurement that the average length of the corn straw entering the rubbing chamber after being cut by the fixed and moving knives at the feed inlet is 12.5 mm (the slip cutting rate κ is 0). However, due to the large differences in the mechanical properties of different positions of the straw, by selecting medium-thick straws, the measurement and calculation of the intrinsic parameters such as density, elastic modulus, and Poisson's ratio, and the bonding bond parameters such as the normal stiffness coefficient and the normal critical stress are carried out, and the discrete element models of breakable corn straws with lengths of 12.5 mm, diameters of 25 mm, 12.5 mm, diameters of 20 mm, and 12.5 mm, and diameters of 15 mm at the root, middle, and end sections are established respectively.

[0115] The DEM-BPM-CFD coupling method is used to numerically simulate the movement of straw particles in the crusher. Among them, the root, middle, and end sections of the straw are respectively composed of 883 inner core particles and 1132 outer skin particles, 638 inner core particles and 965 outer skin particles, and 566 inner core particles and 576 outer skin particles. The newly increased surface areas ΔS after the breakage of the root, middle, and end sections of the straw are 8494.2948 mm 2 、7080.5681 mm 2 and 5419.1217 mm 2 . The torque of its breakage is exported through the post-processing of the discrete element software EDEM.

[0116] S23. Determination of parameters of the power consumption model to make the material have a certain mechanical energy

[0117] By using high-speed imaging technology to measure the movement speed of the material particles at the middle cross-section B in Figure 3 , the result is 37.5 m / s. The height H from the measured material feeding position to the outlet of the discharge pipe is 367.50 mm.

[0118] To determine the energy consumed by material collisions, it is necessary to numerically simulate the internal coupled flow field of the rub pulverizer during the straw crushing process. The DEM-CFD-BPM coupling method is used to numerically simulate the coupled flow field of air flow - straw particles - mechanical structure in the rub pulverizer. Based on the BPM models that can be broken for the root, middle, and tip sections of the straw established in S21, the discrete element DEM method is used to calculate the movement of straw particles under the action of contact forces, air flow field forces, and inertial forces of the hammer blades, tooth plates, and other particles. First, a three-dimensional model of the forage rub pulverizer is established using the three-dimensional modeling software Solidworks, and the model is appropriately simplified on the premise of ensuring calculation accuracy and mesh quality. The processed internal flow channel model of the rub pulverizer is imported into ICEM for mesh generation. Secondly, the internal flow channel mesh file of the rub chamber is imported into the CFD software FLUENT for setting fluid simulation parameters to calculate the air flow field. Among them, the Reliable k-ε turbulence model is used for the turbulence model. The material of the fluid region is air, the sliding mesh model is used for the rotating region, and the rotational speed of the rotating region is 2400 r / min. The measured average air flow velocity at the inlet is used as the velocity inlet boundary condition, which is 1.567 m / s; the standard atmospheric condition is given at the outlet as the pressure boundary value. Finally, the rub pulverizer model is imported into the discrete element software EDEM for setting solid-phase simulation parameters. Among them, the rotor speed is set to be the same as that in the CFD calculation. Particle factories for the root, middle, and tip sections are built on the inner surface of the cutter. The generation rate and direction of the straw sections are set according to the actual feeding amount of 0.3 kg / s and the actual direction. The position of the particle factory is shown in the appendix Figure 3 as shown in the middle cross-section A. Through the post-processing of the EDEM software, the average collision energy E ce per unit time (1 s) can be calculated to be 226.2107 J.

[0119] S24. Determination of the parameters of the power consumption model for making the air have a certain static pressure and flow velocity

[0120] By using a wireless hot-wire anemometer to measure the internal flow field data of the forage rub pulverizer during no-load operation, where the air density is 1.225 kg / m 3 , through the simulation calculation of the air flow field during no-load in S32, the average air mass flow rate Q Figure 3 of the cross-section A as shown in the appendix per unit time can be obtained a to be 0.3015 kg / s, the average flow velocity of cross-section B is 9.04 m / s, and the average static pressure is 5262.86 Pa.

[0121] S25. Determination of the parameters of the power consumption model for the vibration of the machine body

[0122] By using the torque and rotational speed measurement method, the energy E no-loudMeasurements were carried out. Among them, the rotational speed of the shredder rotor was adjusted to 2400 r / min. After the machine stabilized, torque data was collected for 15 s. The experiment was repeated multiple times, and a set of the three measured values with the closest results was selected to calculate the average torque, which was 7.0333 N·m; the energy consumption E per unit time of the shredder under no-load conditions no-loud was 1767.5309 J. The energy consumed by friction of the 7006C angular contact ball bearing was calculated to be 9.5430 J through the bearing power consumption calculation formula Palmgren A.

[0123] S3 Power consumption calculation and experimental verification of crop straw shredder

[0124] S31 Power consumption calculation of crop straw shredder

[0125] Substitute the working parameters and structural parameters of the crop straw shredder determined in S21 into Equation (4), and the energy E consumed by cutting straw per unit time (1 s) can be calculated C to be 242.3404 J; substitute the crushing energy consumption of the straw determined by numerical simulation in S22 into Equation (7), and the energy E consumed by the hammer hitting and the tooth plate kneading the material per unit time (1 s) can be calculated b to be 2301.2421 J; substitute the speed and collision loss energy E of the straw leaving the discharge pipe determined by high-speed camera experiment and DEM-CFD-BPM numerical simulation in S23 ce , and calculate the collision loss energy E ce to be 226.2107 J. The energy E consumed to make the material have a certain mechanical energy during the entire crushing process per unit time (1 s) can be calculated through Equation (8) me to be 438.2298 J; substitute the average air mass flow rate Q of cross-section A determined by no-load flow field experiment in S24 a , the average flow velocity and average static pressure of cross-section B into Equation (9), and the energy E consumed to make the air have a certain static pressure and flow velocity per unit time (1 s) can be calculated air to be 1307.6275 J; substitute the energy consumed by the crop straw shredder under no-load determined by no-load torque experiment in S25 and the energy consumed by friction of the 7006C angular contact ball bearing obtained through Palmgren A into Equation (11), and the energy E consumed by the shredder vibration per unit time (1 s) can be calculated v to be 450.3604 J. The energy consumption ratio diagram of the shredder can be seen in the appendix Figure 5 .

[0126] S32 Power consumption test of crop straw shredder

[0127] Using the torque measurement method, the shredder was at a rotor speed of 2400 r / min, and the straw feeding rate m in was 0.3 kg / s, and the feeding speed vin When the speed is 2m / s, conduct repeated load tests for 15s multiple times, and select a set of the three measured values with the closest results as the measured result. Its average energy consumption within 1s is 4974.5377J, and the average power generation per degree of electricity is 217.1056kg / (kW·h); the energy consumption results are shown in the appendix Figure 6 . By substituting E C , E b , E me , E air and E v into Equation (12) and Equation (13), calculate that the average energy consumption of the shredder power consumption model within 1s is E 0 is 4739.8002J, and the average power generation per degree of electricity E u is 227.8596kg / (kW·h), and its relative error is 4.95%. Considering the inhomogeneity of its rheological properties and the anisotropy of the material, generally, when the relative error is within 10%, the model is considered accurate. Therefore, the calculation result of the model is credible.

[0128] Influence of S4 structure and working parameters on the power consumption of the shredder

[0129] Selection of S41 structure and working parameters

[0130] As can be seen from Equation (4), the parameters affecting the energy consumed by the guillotine knife for cutting materials are the sum of the blade inclination angle and the guillotine knife installation angle, the rotor speed, and the tip thickness of the knife tip; from the simulation of the material crushing process, it can be known that the number of crushed straws and the newly added surface area are related to parameters such as the rotor speed, the number of axial hammer pieces, and the number of circumferential hammer piece distribution groups. Combining Equations (5) to (7), it can be seen that the parameters affecting the energy consumed by the hammer pieces hitting and the tooth plate kneading the materials are the rotor speed, the number of axial hammer piece groups, the number of circumferential hammer pieces, the number of guillotine knives, and the material feeding speed. Among them, the material feeding speed directly affects the material feeding volume. When the cross-sectional size of the feeding port is determined, the material feeding speed that satisfies the optimal feeding volume is also a fixed value. Therefore, its influence on the power consumption is not considered; from the simulation analysis of the material crushing process, it can be seen that the energy consumption of the materials colliding with each other, the hammer pieces, the tooth plate, and the inner wall of the machine shell in the crushing chamber is mainly related to the rotor speed. Combining Equation (8), it can be seen that the parameters affecting the energy consumed by the materials having mechanical energy during the crushing process are the height of the discharge pipe and the average speed of the materials leaving the discharge pipe. Among them, the average speed of the materials leaving the discharge pipe is not the structure and working parameters of the crusher. It can be known from the simulation calculation of the material crushing that its value is mainly related to the rotor speed; from the simulation of the air flow field in the crusher and Equation (9), it can be seen that the parameters affecting the energy consumed by the air in the crusher having a certain static pressure and flow rate are the rotor speed and the number of circumferential hammer piece distribution groups; analyzing Equation (10), it can be seen that the energy consumed by the crusher during no-load operation and the energy consumed by bearing friction are both related to the rotor speed, and the energy consumed to make the air have a certain static pressure and flow rate is related to the rotor speed and the number of circumferential hammer piece distribution groups. Therefore, the parameters affecting the energy consumed by the whole machine vibration are the rotor speed and the number of circumferential hammer piece distribution groups.

[0131] Calculation of power consumption results for S42 structure and working parameters

[0132] Select different parameters within the range of the crusher structure and working parameter values determined in S41 to analyze the influence law of parameter changes on the consumed energy. Among the three factors affecting the energy consumed by the guillotine knife for cutting materials, the rotor speed n has the greatest influence. When the value increases from 2200 r / min to 2400 r / min and 2600 r / min in sequence, the consumed energy increases from 183.8402 J to 197.2803 J and 210.7203 J in sequence; the sum of the blade inclination angle and the guillotine knife installation angle (θ + ξ) has the second greatest influence. When the value increases from 30° to 40° and 50° in sequence, the consumed energy increases from 196.3395 J to 197.2803 J and 201.8141 J in sequence; the tip thickness Tx of the guillotine knife has the least influence. When the value increases from 5 mm to 6 mm and 7 mm in sequence, the consumed energy increases from 197.2794 J to 197.2803 J and 197.2812 J in sequence. Among the four factors affecting the energy consumed by the hammer pieces hitting and the tooth plate kneading the materials, the number of circumferential hammer piece distribution groups G NThe influence is the greatest. When the value increases from 3 groups to 4 groups and 5 groups, the energy consumed decreases from 2494.7623 J to 2301.2421 J and 2192.4301 J in sequence; the number of axial hammer blades H N The influence is the second greatest. When the value increases from 16 to 24 and 32, the energy consumed decreases from 2417.6547 J to 2301.2421 J and 2157.4682 J in sequence; Next is the rotor speed n. When the value increases from 2200 r / min to 2400 r / min and 2600 r / min in sequence, the energy consumed increases from 2178.3162 J to 2301.2421 J and 2406.6774 J in sequence; the number of guillotine knives C N The influence is the smallest. When the value increases from 2 to 3 and 4 in sequence, the energy consumed decreases from 2514.7631 J to 2418.6932 J and 2301.2421 J in sequence. Among the two factors that affect the energy consumed to make the material have a certain mechanical energy, the rotor speed n has the greatest influence. When the value increases from 2200 r / min to 2400 r / min and 2600 r / min in sequence, the energy consumed increases from 394.7165 J to 438.2298 J and 484.7489 J in sequence; the height of the discharge pipe H d The influence is the second greatest. When the value increases from 330 mm to 630 mm and 930 mm in sequence, the energy consumed decreases from 471.5482 J to 438.2298 J and 406.3264 J in sequence. Among the two factors that affect the energy consumed to make the air in the shredder have a certain static pressure and flow rate, the number of circumferential hammer blade distribution groups G N The influence is the greatest. When the value increases from 3 groups to 4 groups and 5 groups in sequence, the energy consumed increases from 1089.7362 J to 1307.6275 J and 1557.4628 J in sequence; the rotor speed n has the second greatest influence. When the value increases from 2200 r / min to 2400 r / min and 2600 r / min in sequence, the energy consumed increases from 1196.6585 J to 1307.6275 J and 1428.5964 J in sequence. Among the two factors that affect the energy consumed by the overall vibration of the machine, the number of circumferential hammer blade distribution groups G N The influence is the greatest. When the value increases from 3 groups to 4 groups and 5 groups in sequence, the energy consumed increases from 260.5148 J to 450.3604 J and 626.7426 J in sequence; the rotor speed n has the second greatest influence. When the value increases from 2200 r / min to 2400 r / min and 2600 r / min in sequence, the energy consumed increases from 316.7649 J to 450.3604 J and 559.2437 J in sequence.

[0133] Sensitivity analysis of the S43 structure and working parameters

[0134] To analyze the influence law of structure and working parameters on the total power consumption of the forage crusher, it is necessary to calculate the sensitivity of different structural parameters and working parameters to the total power consumption of the crusher. The calculation results are shown in the appendix Figure 7 . Among them, the rotor speed n has the greatest influence; the number of circumferential hammer distribution groups G N comes second; then followed by the number of axial hammer pieces H N , the number of choppers C N and the height H of the discharge pipe d . Among them, the sum of the blade inclination angle and the chopper installation angle (θ + ξ) and the chopper tip thickness T k have less influence on the total power consumption. This is mainly because the sum of the chopper installation angles and the blade inclination angle only affect the energy consumed by the chopper to cut the material, and the energy consumed by the chopper to cut the material accounts for a very small proportion in the total energy. Therefore, its influence can be ignored. Among them, the rotor speed n, the number of circumferential hammer distribution groups G N are positively correlated with the total power consumption of the crusher, and the number of axial hammer pieces H N , the number of choppers C N and the height H of the discharge pipe d are negatively correlated with the total power consumption of the crusher.

[0135] Multi-objective optimization design of S5 crop straw crusher

[0136] Taking the factors with greater sensitivity to the energy consumption and power generation per degree of the crusher determined by S43 as the optimization design variables, and taking the lowest total energy consumption and the highest power generation per degree of the crop straw crusher as the optimization objectives, multi-objective optimization is carried out on it by using the multi-island genetic algorithm through Isight software. Its optimization objectives are:

[0137] Min E 0 (X), Min E u (X)

[0138] Its constraint conditions are:

[0139]

[0140] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for predicting and optimizing energy consumption of a crop straw crusher considering the material crushing process, characterized in that: The following steps are involved: S1: The power consumption prediction model of crop straw crusher is established by using theoretical derivation method, combining the coupling effect of materials, airflow and mechanical structure and material crushing mechanism; S2: Determine the parameters of the power consumption prediction model of the crop straw crusher; S3: Substituting the power consumption prediction model parameters of the crop straw crusher into the power consumption prediction model of the crop straw crusher to calculate the energy consumption of the crop straw crusher considering the material crushing process; S4: using the verified power consumption prediction model of the crop straw crusher, calculating and analyzing the sensitivity of different structures and working parameters to the total energy consumption of the crop straw crusher, and obtaining the influence of the structure and working parameters on the total energy consumption of the crop straw crusher; S5: Based on the influence of the structure and working parameters on the total energy consumption of the crop straw crusher, a multi-objective optimization design of the crop straw crusher is performed to obtain the best combination of the structure and working parameters of the crop straw crusher; The power consumption prediction model of the crop straw shredder includes: a power consumption model of the material chopping process, a power consumption model of the hammer striking and the tooth plate rubbing the material process, a power consumption model of the energy consumed by making the material have a certain mechanical energy, a power consumption model of the energy consumed by making the air have a certain static pressure and flow rate, and a power consumption model of the energy consumed by the vibration of the straw shredder body; The method of establishing the power consumption model of the material cutting process includes: The total resistance of the guillotine per unit cutting length in the cutting direction to the straw material is deduced from the force analysis of the guillotine in the process of cutting the straw. Based on the total resistance of the straw material to the cutter per unit cutting length in the cutting direction and the effective cutting length of the straw, the total reaction force of the straw on the cutter along the cutting direction is obtained; Based on the total reaction force of the straw on the cutter along the cutting direction, the energy consumed by the cutter in cutting materials per unit time is derived, and then the power consumption model of the cutting process is established. in, In the formula, E c is the energy consumed by the guillotine to cut the material per unit time, m in is the amount of straw fed in 1s, m s is the mass of a cut section of straw, R yL is the total reaction force of the straw on the guillotine along the y direction, is the arc length of the contact point between the guillotine and the straw when cutting a section of straw, t0 is the time required for the guillotine to completely break the straw from the start of cutting, w is the rotation speed of the rotor where the guillotine is located, a is the distance from the center of the straw to the center of rotation of the rotor, r is the radius of the radial section of the straw, T K is the tip thickness, σ y is the compressive stress of the blade on the stem along the y direction, E is the elastic modulus of the straw material, (θ+ξ) is the sum of the blade inclination angle and the guillotine installation angle, u w is the internal friction coefficient of the squeezed straw layer, v is the Poisson's ratio of the straw material, u is the friction coefficient between the straw and the blade surface material, w is the rotation speed of the rotor where the guillotine is located, and a is the distance from the center of the straw to the center of rotation of the rotor; The methods for establishing the power consumption model of the hammer striking and tooth plate kneading material process include: In the formula, E b The energy consumed by the hammer striking and the tooth plate rubbing to break the material per unit time, m in is the amount of straw fed in 1s, m s is the mass of a section of chopped straw, K1 is the proportionality coefficient, i.e. the work required per unit surface area, J / mm 2 , ΔS is the new surface area of ​​the material, r st is the equivalent radius of the broken filamentous straw, h st is the equivalent length of the broken filamentous straw, ρ is the density of the straw, r is the radius of the radial section of the straw, κ is the sliding rate of the guillotine, and v in is the straw feeding speed under actual working conditions, λ is the number of guillotines, and n is the rotor speed; Methods for establishing a power consumption model for the energy consumed to give materials a certain amount of mechanical energy include: In the formula, E me The energy consumed in the material crushing process to make the straw material have a certain mechanical energy per unit time, m in is the feeding amount of straw in 1s, H is the height of the material feeding position from the section B at the outlet of the discharge pipe, is the average velocity of the material at section B, that is, the average velocity of the material leaving the discharge pipe, v in is the straw feeding speed under actual working conditions, E ce Energy loss caused by collision between materials, hammers, tooth plates and the inner wall of the casing in the crushing chamber; Methods for establishing a power consumption model for the energy consumed to provide air with a certain static pressure and flow rate include: In the formula, E air Q is the energy consumed per unit time by the rotor of the kneading machine to rotate so that the air has a certain static pressure and flow rate, a is the air flow mass flow rate per unit time in section A, P a is the static pressure of the airflow at section B, ρ air is the density of the airflow, V a is the velocity of the airflow at section B; The method for establishing a power consumption model of energy consumed by the vibration of the straw crushing machine body includes: AND v =And no-load -AND air -AND f , In the formula, E v is the energy consumed by the vibration of the straw crusher per unit time, E no-loud E is the energy consumed per unit time by the crusher under no-load conditions, f E is the energy consumed by the friction between the bearing and the rotor shaft per unit time, air It is the energy consumed per unit time for the rotor of the kneading machine to rotate so that the air has a certain static pressure and flow rate.

2. The method for predicting and optimizing the energy consumption of a crop straw crusher considering the material crushing process according to claim 1 is characterized in that: Based on the influence of the structure and working parameters on the total energy consumption of the crop straw crusher, the method for multi-objective optimization design of the crop straw crusher includes: The optimization objectives are to minimize the total energy consumption and maximize the electricity output of the crop straw crusher, the structure and working parameters that have a sensitive impact on the optimization objectives are used as optimization design variables, and the crushing quality and machine structure size are used as constraints to carry out multi-objective optimization design to obtain the best combination of the structure and working parameters of the crop straw crusher.

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