A design method for matching compressor and expander of Stirling refrigerator

Abstract

The invention discloses a design method for matching a compressor and an expander of a Stirling refrigerator, belongs to the technical field of Stirling refrigerators, and comprises the following steps: S1, establishing a thermal model: establishing a one-dimensional thermal model of a Stirling refrigerator; S2, setting boundary conditions: including the heat dissipation temperature of the hot end and the refrigeration capacity of the cold end; S3, performing thermal calculation: initializing thermal parameters, changing thermal parameters one by one, and selecting thermal design values; S4, gas load analysis: calculating gas damping and gas stiffness; S5, establishing a dynamic model: establishing a three-dimensional finite element model of a compressor motor; S6, performing dynamic calculation: initializing dynamic parameters, setting the mechanical stiffness and mechanical damping of a compression leaf spring, gas damping and gas stiffness, changing dynamic parameters one by one, and selecting dynamic design values. The invention makes up for the currently missing design method for efficiently matching a compressor and an expander of a Stirling refrigerator, and the designed Stirling refrigerator has high refrigeration efficiency and low energy consumption.

Description

Technical Field

[0001] The invention relates to the technical field of Stirling refrigerators, and in particular to a matching design method for a compressor and an expander of a Stirling refrigerator. Background Art

[0002] Stirling refrigerators are an important cooling method in the temperature range of 120K and below. They are currently used in aerospace projects such as infrared detector cooling, low-temperature optical system cooling, and low-temperature biological storage tank cooling. Stirling refrigerators mainly include Stirling pulse tube refrigerators and Stirling refrigerators. Stirling pulse tube refrigerators include two major components: compressors and cold fingers. Stirling refrigerators include two major components: compressors and expanders. Since the expeller of Stirling refrigerators has a work recovery function, Stirling refrigerators are more efficient than Stirling pulse tube refrigerators. They are an important cold source for micro-satellites with limited resources. Figure 4 As shown, the compressor 1 mainly includes a compression piston 11, a permanent magnet 12, a magnetizer 13, a coil 14, a compression leaf spring 15 and a first compression chamber 16, and the expander 2 mainly includes an expansion piston 21, a regenerator 22, an expansion leaf spring 23, a hot end 24, a cold end 25, an expansion chamber 26 and a second compression chamber 27. The first compression chamber 16 and the second compression chamber 27 are connected through a connecting pipe 3.

[0003] Due to the limited power consumption resources of aerospace projects, the efficiency of Stirling refrigerators is required to be high. Whether the design between the compressor and the expander, and between the compressor and the cold finger, will directly affect the efficiency of the Stirling refrigerator. The existing design scheme is mainly aimed at the matching design of the compressor and the cold finger in the Stirling pulse tube refrigerator, and cannot guide the matching design of the compressor and the expander of the Stirling refrigerator, such as the "Design method of inertial tube pulse tube cold finger optimally matched with linear compressor" disclosed in patent number "201510868765.1", "A linear compressor design method matched with pulse tube Stirling refrigerator" disclosed in patent number "201711219102.2" and "A system and method for obtaining the best matching of pulse tube cold finger and inertial tube gas reservoir phase adjustment" disclosed in "201910021594.7", etc. Therefore, there is an urgent need for a method for guiding the efficient matching design of the compressor and expander of the Stirling refrigerator, and realizing the efficient matching design of the two through the linkage calculation of the compressor and the expander. Summary of the invention

[0004] The purpose of the present invention is to solve the above-mentioned technical problems and provide a design method for matching the compressor and expander of a Stirling refrigerator, which makes up for the current lack of a design method for efficiently matching the compressor and expander of a Stirling refrigerator. Through the system's thermal and dynamic collaborative design strategy, the gas load characteristics of the expander are added to the compressor design, so that the compressor and the expander are efficiently matched. The designed Stirling refrigerator has high refrigeration efficiency and effectively controlled energy consumption.

[0005] To achieve the above object, the present invention provides the following solution: The present invention discloses a method for designing the matching of a compressor and an expander of a Stirling refrigerator, comprising the following steps:

[0006] S1. Establishing a thermal model: Based on the conservation of mass, momentum and energy, a one-dimensional thermal model of the Stirling refrigerator is established;

[0007] S2, setting boundary conditions: setting boundary conditions for the one-dimensional thermal model, wherein the boundary conditions include the heat dissipation temperature at the hot end and the cooling capacity at the cold end;

[0008] S3, performing thermal calculation: initializing the thermal parameters of the one-dimensional thermal model, the thermal parameters including the operating frequency of the Stirling refrigerator, the gas filling pressure and the size parameters of each component of the Stirling refrigerator, and then changing the thermal parameters one by one through the single variable method, and selecting a thermal parameter configuration set that meets the refrigeration temperature design requirements and has the highest expansion mechanism refrigeration efficiency as the thermal design value;

[0009] S4. Gas load analysis: Evaluate the gas dynamic characteristics of the compression piston end face of the compressor in the Stirling refrigerator, and calculate the gas damping and gas stiffness through the gas pressure wave amplitude, compression piston end face area, compression piston displacement amplitude, and the phase angle between the gas pressure wave and the compression piston displacement.

[0010] S5. Establishing a power model: establishing a three-dimensional finite element model of the compressor motor;

[0011] S6. Perform power calculation: initialize the power parameters of the three-dimensional finite element model of the compressor motor, the power parameters include the size values ​​of the various components of the compressor motor, set the mechanical stiffness and mechanical damping of the compression leaf spring of the compressor, set the gas damping and gas stiffness according to the result calculated in step S4, change the power parameters one by one, and select the power parameter configuration set with the minimum electric power that does not exceed the index requirements as the power design value.

[0012] Preferably, in step S1, a one-dimensional thermodynamic model of the Stirling refrigerator is established using a node method.

[0013] Preferably, in step S1, the Stirling refrigerator comprises a compressor, a connecting pipe and an expander.

[0014] Preferably, in step S2, the heat dissipation temperature of the hot end is preset to a given temperature value, and the cooling capacity of the cold end is preset to a given cooling capacity value.

[0015] Preferably, in step S2, in the process of changing the thermal parameters one by one, each time a thermal parameter value is changed, a set of refrigeration temperature and compression piston end face gas acoustic work is obtained, and then the expansion mechanism refrigeration efficiency is calculated according to the expansion mechanism refrigeration efficiency = expansion chamber refrigeration capacity / compression piston end face gas acoustic work, when the refrigeration temperature and the expansion mechanism refrigeration efficiency meet the design requirements, the parameter combination of the corresponding size parameter values ​​is recorded, and the parameter combination with the lowest expansion mechanism refrigeration efficiency is selected therefrom, and the variable values ​​in all the parameter combinations corresponding to the lowest expansion mechanism refrigeration efficiency are selected and combined into a thermal parameter configuration set as the thermal design value.

[0016] Preferably, in step S2, the dimensional parameters of the components of the Stirling refrigerator include the diameter and length of the expansion piston of the expander, the aperture / porosity of the regenerator of the expander, the diameter and length of the expansion chamber of the expander, the diameter and length of the second compression chamber of the expander, the diameter and stroke of the compression piston end face of the compressor, and the diameter and length of the connecting pipe.

[0017] Preferably, in step S3, the gas load on the end surface of the compression piston is calculated according to the following formula:

[0018] Gas Damping ;

[0019] Gas stiffness ;

[0020] in is the gas pressure wave amplitude at the compression piston end face, A is the compression piston end face area, is the phase angle between the gas pressure wave and the displacement, and X is the displacement amplitude.

[0021] Preferably, in step S5, the required motor structure is selected according to the requirements, and the three-dimensional finite element model of the compressor motor is established using Maxwell software. The three-dimensional finite element model of the compressor motor includes a magnetic conductor, a permanent magnet, a coil and a compression leaf spring.

[0022] Preferably, in step S5, the motor structure is a moving coil type, a moving magnet type or a moving iron type.

[0023] Preferably, in step S6, the dimensional parameters of the magnetic conductor, permanent magnet, coil and compression leaf spring are changed one by one, and an electric power is obtained each time a parameter value is changed, and the parameter combination with the minimum electric power is selected therefrom, and the variable values ​​in all parameter combinations corresponding to the minimum electric power are selected and combined into a power parameter configuration set, and the minimum electric power of the power parameter configuration set is compared with the index electric power. If the electric power does not exceed the index, it is confirmed that the current power design parameter combination is valid. Otherwise, it is necessary to return to step S6 and re-iterate the power parameters.

[0024] Compared with the prior art, the present invention has achieved the following technical effects:

[0025] The compressor and expander matching design method of the Stirling refrigerator of the present invention makes up for the currently missing design method for efficiently matching the compressor and expander of the Stirling refrigerator. Through the system's thermal and power collaborative design strategy and adding the gas load characteristics of the expander to the compressor design, the compressor and the expander are efficiently matched. The Stirling refrigerator designed by this method not only improves the efficiency of the refrigeration system, but also effectively controls energy consumption, and has significant technological advancement and practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a flow chart of a method for designing the matching between the compressor and the expander of a Stirling refrigerator in an embodiment;

[0028] Figure 2 for Figure 1 A partial enlarged view of the thermal design part;

[0029] Figure 3 for Figure 1 A partial enlarged view of the power design part;

[0030] Figure 4 Schematic diagram of the structure of the Stirling refrigerator in the embodiment.

[0031] Description of reference numerals:

[0032] 1. Compressor; 2. Expander; 3. Connecting pipe;

[0033] 11. Compression piston; 12. Permanent magnet; 13. Magnetic conductor; 14. Coil; 15. Compression leaf spring; 16. First compression chamber;

[0034] 21. Expansion piston; 22. Regenerator; 23. Expansion leaf spring; 24. Hot end; 25. Cold end; 26. Expansion chamber; 27. Second compression chamber. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] This embodiment provides a method for designing a compressor and an expander matching device of a Stirling refrigerator. Figures 1 to 4 As shown, the following steps are included:

[0037] S1. Establishing a thermal model: Based on the conservation of mass, momentum and energy, a one-dimensional thermal model of the Stirling refrigerator is established. Compared with the finite volume method of the two-dimensional model and the three-dimensional model, the calculation efficiency is high;

[0038] S2. Setting boundary conditions: Setting boundary conditions for the one-dimensional thermal model. The boundary conditions include the heat dissipation temperature at the hot end and the cooling capacity at the cold end.

[0039] S3. Perform thermal calculations: initialize the thermal parameters of the one-dimensional thermal model, including but not limited to the operating frequency of the Stirling refrigerator, the charging pressure, and the size parameters of each component of the Stirling refrigerator. Then, through the single variable method, change the thermal parameters one by one, and select the thermal parameter configuration set that meets the refrigeration temperature design requirements and has the highest expansion mechanism refrigeration efficiency as the thermal design value; Note: ① The initialization value of the thermal parameter is mainly the optimal thermal parameter set first based on experience; ② The charging pressure refers to the pressure of the gas charged into the Stirling refrigerator. The compressor 1 and the expander 2 are a gas connection domain, and their internal pressures are the same; ③ Refrigeration efficiency design requirements: The specific design requirements for various occasions are different. Some have high refrigeration efficiency requirements, but do not have high requirements on weight and volume. Some have high weight and volume requirements and cannot achieve high refrigeration efficiency.

[0040] S4, gas load analysis: evaluate the gas dynamic characteristics of the end face of the compression piston 11 of the compressor 1 in the Stirling refrigerator, calculate the gas damping and gas stiffness through the gas pressure wave amplitude of the end face of the compression piston 11, the end face area of ​​the compression piston 11, the displacement amplitude of the compression piston 11, and the phase angle between the gas pressure wave on the end face of the compression piston 11 and the displacement of the compression piston 11;

[0041] S5. Establishing a power model: establishing a three-dimensional finite element model of the compressor motor;

[0042] S6. Perform power calculation: initialize the power parameters of the three-dimensional finite element model of the compressor motor. The power parameters include the size values ​​of the various components of the compressor motor, set the mechanical stiffness and mechanical damping of the compression leaf spring 15 of the compressor 1, set the gas damping and gas stiffness according to the results calculated in step S4, change the power parameters one by one, and select the power parameter configuration set with the minimum electric power that does not exceed the index requirements as the power design value. Note: ① The initialization values ​​of the power parameters are mainly the optimal power parameters set first based on experience. ② Set the mechanical stiffness and mechanical damping of the compression leaf spring 15 according to the existing structural process.

[0043] This method makes up for the currently missing design method for efficiently matching the compressor 1 and the expander 2 of the Stirling refrigerator. Through the system's thermal and power collaborative design strategy, and adding the gas load characteristics of the expander 2 to the design of the compressor 1, the compressor 1 and the expander 2 are efficiently matched. The Stirling refrigerator designed by this method has high overall efficiency.

[0044] In one embodiment, if Figures 1 to 4 As shown, in step S1, a one-dimensional thermodynamic model of a Stirling refrigerator is established by using a node method. The node method can be used to divide each component of the Stirling refrigerator into a finite number of nodes, and the nodes are used to replace the continuous solution domain. The equations on the node boundary are discretized and reduced to a one-dimensional solution. Compared with the two-dimensional and three-dimensional finite volume methods, the calculation efficiency is high.

[0045] In one embodiment, if Figures 1 to 4 As shown, in step S1, the Stirling refrigerator includes a compressor 1, an expander 2 and a connecting pipe 3, wherein the compressor 1 includes a compression piston 11, a permanent magnet 12, a magnetic conductor 13, a coil 14, a compression leaf spring 15 and a first compression chamber 16, and the expander 2 includes an expansion piston 21, a regenerator 22, an expansion leaf spring 23, a hot end 24, a cold end 25, an expansion chamber 26 and a second compression chamber 27. The above-mentioned mechanisms are all existing parts, and the connection relationship and position relationship are not described in detail here. The one-dimensional model of the Stirling refrigerator should be detailed to the above-mentioned structures.

[0046] In one embodiment, if Figures 1 to 4 As shown, in step S2, the heat dissipation temperature of the hot end is preset to a given temperature value, such as 300 K. The cooling capacity of the cold end is preset to a given cooling capacity value, such as 10 W. The above two values ​​are usually preset values ​​and can be adjusted according to actual needs and corresponding working conditions.

[0047] In one embodiment, if Figures 1 to 4As shown, in step S2, during the process of changing the thermodynamic parameters one by one, each time a thermodynamic parameter value is changed, a set of refrigeration temperature and compression piston end face gas acoustic work is obtained, and then the expansion mechanism refrigeration efficiency is calculated according to the expansion mechanism refrigeration efficiency = expansion chamber refrigeration capacity / compression piston end face gas acoustic work, when the refrigeration temperature and the expansion mechanism refrigeration efficiency meet the design requirements, the corresponding parameter combination of the size parameter value is recorded, and the parameter combination with the lowest expansion mechanism refrigeration efficiency is selected from them, and the variable values ​​in all the parameter combinations corresponding to the lowest expansion mechanism refrigeration efficiency are selected and combined into a thermodynamic parameter configuration set as the thermodynamic design value. Among them: the refrigeration temperature refers to the temperature reached by the cold end 25, and the compression piston end face gas acoustic work refers to the work done by the end face of the compression piston 11 on the gas.

[0048] In one embodiment, if Figures 1 to 4 As shown, in step S2, the dimensional parameters of each component of the Stirling refrigerator include the diameter and length of the expansion piston 21 of the expander 2, the aperture / porosity of the regenerator 22 of the expander 2, the diameter and length of the expansion chamber 26 of the expander 2, the diameter and length of the second compression chamber 27 of the expander 2, the diameter and stroke of the end face of the compression piston 11 of the compressor 1, and the diameter and length of the connecting pipe 3. The dimensional parameters of each component must be changed one by one. When changing one by one, for example, the diameter of the expansion piston 21 is changed first, and then all other parameters are initialized parameters, and then the length of the expansion piston 21 is changed, and all other parameters are initialized parameters. The final selected thermal parameter configuration set includes the selected optimal diameter and length of the expansion piston 21, the optimal aperture / porosity of the regenerator 22, the optimal diameter and length of the expansion chamber 26, the optimal diameter and length of the second compression chamber 27, the optimal diameter and stroke of the end face of the compression piston 11, and the optimal diameter and length of the connecting pipe 3.

[0049] In one embodiment, if Figures 1 to 4 As shown, in step S3, the gas load on the end surface of the compression piston 11 is calculated according to the following formula:

[0050] Gas Damping ;

[0051] Gas stiffness ;

[0052] in is the gas pressure amplitude at the end face of the compression piston 11, A is the end face area of ​​the compression piston 11, is the phase angle between the gas pressure wave and the displacement, and X is the displacement amplitude.

[0053] In one embodiment, if Figures 1 to 4As shown, in step S5, the required motor structure is selected according to the demand, and the three-dimensional finite element model of the compressor motor is established using Maxwell software. The three-dimensional finite element model of the compressor motor includes a permanent magnet 12, a magnetizer 13, a coil 14, and a compression leaf spring 15. Of course, if there are other suitable software, other software can also be used to establish the three-dimensional finite element model of the compressor motor. According to experience, the size parameters of the permanent magnet 12, the magnetizer 13, and the coil 14 are assigned initial values, and the mechanical stiffness and mechanical damping of the compression leaf spring 15 are set according to the existing structural process.

[0054] In one embodiment, if Figures 1 to 4 As shown, in step S5, the motor structure is a moving coil type, a moving magnet type or a moving iron type. The moving coil type has a small vibration force, the moving magnet type has a high power density, and the moving iron type has a low cost. The specific motor structure can be selected according to the needs.

[0055] In one embodiment, if Figures 1 to 4 As shown, in step S6, the size parameters of the permanent magnet 12, the magnetizer 13, the coil 14 and the compression leaf spring 15 are changed one by one (the order of the structures can be reversed or disrupted, but they must be performed one by one), and each time a parameter value is changed, an electric power is obtained, and the parameter combination with the minimum electric power is selected, and the variable values ​​in all the parameter combinations corresponding to the minimum electric power are selected and combined into a power parameter configuration set, and the minimum electric power of the power parameter configuration set is compared with the index electric power. If the index electric power is not exceeded, it is confirmed that the current power design parameter combination is valid. Otherwise, it is necessary to return to step S6 and re-iterate the power parameters.

[0056] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for designing the matching of a compressor and an expander of a Stirling refrigerator, characterized in that: The following steps are involved: S1. Establishing a thermal model: Based on the conservation of mass, momentum and energy, a one-dimensional thermal model of the Stirling refrigerator is established; S2, setting boundary conditions: setting boundary conditions for the one-dimensional thermal model, wherein the boundary conditions include the heat dissipation temperature at the hot end and the cooling capacity at the cold end; S3, performing thermal calculation: initializing the thermal parameters of the one-dimensional thermal model, the thermal parameters including the operating frequency, the charging pressure and the size parameters of each component of the Stirling refrigerator, and then changing the thermal parameters one by one through the single variable method, and selecting a thermal parameter configuration set that meets the refrigeration temperature design requirements and has the highest expansion mechanism refrigeration efficiency as the thermal design value; S4. Gas load analysis: Evaluate the gas dynamic characteristics of the compression piston end face of the compressor in the Stirling refrigerator, and calculate the gas damping and gas stiffness through the gas pressure wave amplitude, compression piston end face area, compression piston displacement amplitude, and the phase angle between the gas pressure wave and the compression piston displacement. S5. Establishing a power model: establishing a three-dimensional finite element model of the compressor motor; S6. Perform power calculation: initialize the power parameters of the three-dimensional finite element model of the compressor motor, the power parameters include the size values ​​of the various components of the compressor motor, set the mechanical stiffness and mechanical damping of the compression leaf spring of the compressor, set the gas damping and gas stiffness according to the result calculated in step S4, change the power parameters one by one, and select the power parameter configuration set with the minimum electric power that does not exceed the index requirements as the power design value.

2. The method for designing the matching of the compressor and the expander of the Stirling refrigerator according to claim 1, characterized in that: In step S1, a one-dimensional thermodynamic model of a Stirling refrigerator is established using a node method.

3. The method for designing the matching of a compressor and an expander of a Stirling refrigerator according to claim 1, characterized in that: In step S1, the Stirling refrigerator includes a compressor, a connecting pipe and an expander.

4. According to the compressor and expander matching design method of the Stirling refrigerator according to claim 1, in step S2, the hot end heat dissipation temperature is preset to a given temperature value, and the cold end cooling capacity is preset to a given cooling capacity value.

5. According to the compressor and expander matching design method of a Stirling refrigerator according to claim 1, in step S2, in the process of changing the thermal parameters one by one, each time a thermal parameter value is changed, a set of refrigeration temperature and compression piston end face gas acoustic work is obtained, and then the expansion mechanism refrigeration efficiency is calculated according to the expansion mechanism refrigeration efficiency = expansion chamber refrigeration capacity / compression piston end face gas acoustic work, when the refrigeration temperature and the expansion mechanism refrigeration efficiency meet the design requirements, the parameter combination of the corresponding size parameter values ​​is recorded, and the parameter combination with the lowest expansion mechanism refrigeration efficiency is selected therefrom, and the variable values ​​in all the parameter combinations corresponding to the lowest expansion mechanism refrigeration efficiency are selected and combined into a thermal parameter configuration set as the thermal design value.

6. According to the compressor and expander matching design method of the Stirling refrigerator according to claim 1 or 5, in step S2, the size parameters of the components of the Stirling refrigerator include the diameter and length of the expansion piston of the expander, the aperture / porosity of the regenerator of the expander, the diameter and length of the expansion chamber of the expander, the diameter and length of the second compression chamber of the expander, the diameter and stroke of the compression piston end face of the compressor, and the diameter and length of the connecting pipe.

7. The method for designing the matching of a compressor and an expander of a Stirling refrigerator according to claim 1, wherein in step S3, the gas load on the end surface of the compression piston is calculated according to the following formula: Gas Damping ; Gas stiffness ; in is the gas pressure wave amplitude at the compression piston end face, A is the compression piston end face area, is the phase angle between the gas pressure wave and the compression piston displacement, and X is the compression piston displacement amplitude.

8. According to the compressor and expander matching design method of the Stirling refrigerator according to claim 1, in step S5, the required motor structure is selected according to the demand, and the compressor motor three-dimensional finite element model is established using Maxwell software, and the compressor motor three-dimensional finite element model includes a magnetic conductor, a permanent magnet, a coil and a compression leaf spring.

9. The method for designing matching between a compressor and an expander of a Stirling refrigerator according to claim 8, wherein in step S5, the motor structure is a moving coil type, a moving magnet type or a moving iron type.

10. According to the compressor and expander matching design method of a Stirling refrigerator as described in claim 8, in step S6, the size parameters of the magnetizer, permanent magnet, coil and compression leaf spring are changed one by one, and an electric power is obtained each time a parameter value is changed, and a parameter combination with the minimum electric power is selected therefrom, and the variable values ​​in all parameter combinations corresponding to the minimum electric power are selected and combined into a power parameter configuration set, and the minimum electric power of the power parameter configuration set is compared with the target electric power. If the target electric power is not exceeded, it is confirmed that the current power design parameter combination is valid. Otherwise, it is necessary to return to step S6 and re-iterate the power parameters.

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