Heat-driven Stirling refrigeration system

Abstract

This invention provides a heat-driven Stirling refrigeration system, comprising multiple Stirling units connected in sequence. Each Stirling unit includes a Stirling engine and a Stirling refrigerator arranged opposite each other. The Stirling engine has an engine piston, and the Stirling refrigerator has a refrigerator piston. The engine piston and the refrigerator piston are located at opposite ends of a piston rod, which transmits mechanical work. Adjacent Stirling engines are connected to each other by a connecting pipe, and adjacent Stirling refrigerators are also connected to each other by the connecting pipe; alternatively, adjacent Stirling engines are connected to each other by the connecting pipe. The heat-driven Stirling refrigeration system provided by this invention aims to solve the problems of existing double-effect free-piston Stirling heat engine systems, such as numerous moving parts, complex structure, volume redundancy, and low power density.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and more particularly to a heat-driven Stirling refrigeration system. Background Technology

[0002] Thermoacoustic effect mainly refers to the process by which compressible gas oscillates back and forth under heat, achieving the interconversion between sound energy and thermal energy. This effect can be roughly divided into two categories: the first is the thermoacoustic effect, which amplifies the sound work through the temperature difference of the regenerator, thus converting thermal energy into sound energy; the second is the acoustic cooling effect, which generates a temperature difference in the regenerator through gas oscillation. The Stirling engine can provide sound work for the Stirling refrigerator, thereby realizing the conversion of thermal energy into sound energy, and further into cooling energy.

[0003] Stirling engine technology, after its early development and evolution from the crankshaft and connecting rod tradition, has now evolved into a technology dominated by free-piston Stirling engines. The core concept of a double-effect free-piston Stirling engine is to use a free-piston Stirling engine to provide acoustic power to the refrigeration engine. A resonant oscillator couples the engine and refrigeration engine, providing phase adjustment. In this system, the regenerator in the engine subsystem generates acoustic power, which is transferred from the engine to the refrigeration engine via the resonant oscillator. This acoustic power is then consumed in the regenerator of the refrigeration engine subsystem, ultimately generating cooling capacity at the cryogenic heat exchanger of the refrigeration engine.

[0004] In addition, there is also a free piston type double-effect Stirling engine structure with resonant tube and resonant motor coupling for double-effect structure, but the system has problems such as complex structure, volume redundancy and low power density, which limit the practical application of this type of heat engine. Summary of the Invention

[0005] This invention provides a heat-driven Stirling refrigeration system to solve the problems of traditional double-effect free piston Stirling heat engine systems, such as numerous moving parts, complex structure, volume redundancy, and low power density.

[0006] To address the problems existing in the prior art, this invention provides a heat-driven Stirling refrigeration system, comprising a plurality of Stirling units connected in sequence. Each Stirling unit includes a Stirling engine and a Stirling refrigerator arranged opposite to each other. The Stirling engine has an engine piston, and the Stirling refrigerator has a refrigerator piston. The engine piston and the refrigerator piston are respectively disposed at both ends of a piston rod, and the piston rod is used to transmit mechanical work.

[0007] Wherein, two adjacent Stirling engines are connected to each other by a connecting pipe, and two adjacent Stirling refrigerators are connected to each other by the connecting pipe, or two adjacent Stirling engines are connected to each other by the connecting pipe.

[0008] According to a heat-driven Stirling refrigeration system provided by the present invention, each Stirling engine includes engine components arranged in sequence: an engine left connecting pipe, an engine buffer chamber, an engine room temperature heat exchanger, an engine regenerator, an engine high temperature heat exchanger, an engine expansion chamber, an engine piston, an engine compression chamber, and an engine right connecting pipe. The engine left connecting pipe is connected to the engine buffer chamber, and the engine right connecting pipe is connected to the engine compression chamber.

[0009] The right connecting pipe of each Stirling engine is connected to the left connecting pipe of the adjacent Stirling engine.

[0010] According to a heat-driven Stirling refrigeration system provided by the present invention, each Stirling refrigerator includes refrigerator components arranged sequentially: a left connecting pipe for the refrigerator, a buffer chamber for the refrigerator, a low-temperature heat exchanger for the refrigerator, a regenerator for the refrigerator, a room-temperature heat exchanger for the refrigerator, a compression chamber for the refrigerator, a piston for the refrigerator, an expansion chamber for the refrigerator, and a right connecting pipe for the refrigerator. The left connecting pipe for the refrigerator is connected to the buffer chamber for the refrigerator, and the right connecting pipe for the refrigerator is connected to the expansion chamber for the refrigerator.

[0011] When two adjacent Stirling refrigerators are connected to each other, the right connecting pipe of each Stirling refrigerator is connected to the left connecting pipe of the adjacent Stirling refrigerator.

[0012] According to a heat-driven Stirling refrigeration system provided by the present invention, the number n of the Stirling units satisfies the following relationship: n≥3.

[0013] According to the present invention, a heat-driven Stirling refrigeration system is provided in which the phase difference between each Stirling unit is 120 degrees when the number of Stirling units n is 3; the phase difference between each Stirling unit is 90 degrees when the number of Stirling units n is 4; and the phase difference between each Stirling unit is 60 degrees when the number of Stirling units n is 6.

[0014] According to a heat-driven Stirling refrigeration system provided by the present invention, a back cavity is provided between the Stirling engine and the Stirling refrigerator placed opposite each other, and the back cavity is spaced apart from the Stirling engine and the Stirling refrigerator;

[0015] The piston rod is movably inserted through the gap in the back cavity, and the heat-driven Stirling refrigeration system also includes a linear motor disposed in the back cavity, the piston rod being used to drive the linear motor.

[0016] According to a heat-driven Stirling refrigeration system provided by the present invention, the linear motor includes a stator and a mover. The stator is disposed on the inner wall surface of the back cavity, and the mover is connected to the piston rod to move under the drive of the piston rod.

[0017] Existing double-effect free-piston Stirling engine systems suffer from numerous moving parts, complex structures, volume redundancy, and low power density, all of which limit their reliability and stability, further restricting the practical application of this type of heat engine. The heat-driven Stirling refrigeration system provided by this invention has a simple overall system structure, allowing a single Stirling unit to perform both engine and refrigeration functions, while also possessing high power density. Furthermore, the interconnected Stirling units provide phase-adjusting functionality for individual Stirling units, facilitating stable system operation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a cross-sectional view of the first embodiment of the heat-driven Stirling refrigeration system provided by the present invention.

[0020] Figure 2 This is a cross-sectional view of the second embodiment of the heat-driven Stirling refrigeration system provided by the present invention.

[0021] Figure 3 This is a cross-sectional view of the third embodiment of the heat-driven Stirling refrigeration system provided by the present invention.

[0022] Figure label:

[0023] 1: Heat-driven Stirling refrigeration; 2: Stirling unit; 3: Stirling engine; system;

[0024] 4: Stirling refrigerator; 5: Linear motor; 6: Piston rod;

[0025] 7: Back cavity; 8: Left engine connecting pipe; 9: Engine buffer cavity;

[0026] 10: Engine room temperature heat exchanger; 11: Engine regenerator; 12: Engine high temperature heat exchanger;

[0027] 13: Engine expansion chamber; 14: Engine piston; 15: Engine compression chamber;

[0028] 16: Right connecting pipe for engine; 17: Left connecting pipe for refrigeration unit; 18: Refrigeration unit buffer chamber;

[0029] 19: Low-temperature heat exchanger for refrigeration unit; 20: Regenerator for refrigeration unit; 21: Room temperature heat exchanger for refrigeration unit;

[0030] 22: Compression chamber of the refrigeration unit; 23: Piston of the refrigeration unit; 24: Expansion chamber of the refrigeration unit;

[0031] 25: Right connecting pipe of the refrigeration unit; 26: Stator; 27: Mover. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0033] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0035] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0037] The following is combined with Figures 1-3 The present invention describes a heat-driven Stirling refrigeration system 1.

[0038] A double-acting Stirling engine connects three or more Stirling engines end-to-end in a loop, with pistons in the middle for resonant phase adjustment. This replaces the traditional thermoacoustic method of using resonant tubes / resonant oscillators / resonant motors for phase adjustment, resulting in a more compact structure and increased acoustic power output. Each piston can act as both a compression piston in the previous unit's compression chamber and an expansion piston in the next unit's expansion chamber, reducing the average number of pistons per Stirling unit to one. Therefore, this structure has a higher power density and can achieve greater acoustic power within a limited volume.

[0039] Considering the problems of complex structure, volume redundancy and low power density of the double-effect Stirling engine system, if the double-effect Stirling engine is coupled with a double-acting Stirling engine, the system stability can be improved by the inherent structural characteristics of the double-acting Stirling engine. Moreover, this engine has the characteristics of high power density, which can provide sufficient acoustic power for the refrigeration unit.

[0040] Therefore, this embodiment of the invention provides a heat-driven Stirling refrigeration system 1, including a plurality of Stirling units 2 connected in sequence. Each Stirling unit 2 includes a Stirling engine 3 and a Stirling refrigerator 4 arranged opposite to each other. The Stirling engine 3 has an engine piston 14, and the Stirling refrigerator 4 has a refrigerator piston 23. The engine piston 14 and the refrigerator piston 23 are respectively disposed at both ends of a piston rod 6, and the piston rod 6 is used to transmit mechanical work. Adjacent Stirling engines 3 are connected to each other by a connecting pipe, and adjacent Stirling refrigerators 4 are connected to each other by a connecting pipe, or adjacent Stirling engines 3 are connected to each other by a connecting pipe.

[0041] Specifically, the Stirling engine 3 includes engine components arranged in sequence (not labeled in the attached drawings): engine left connecting pipe 8, engine buffer chamber 9, engine room temperature heat exchanger 10, engine regenerator 11, engine high temperature heat exchanger 12, engine expansion chamber 13, engine piston 14, engine compression chamber 15, and engine right connecting pipe 16. The engine left connecting pipe 8 is connected to the engine buffer chamber 9, and the engine right connecting pipe 16 is connected to the engine compression chamber 15. The Stirling refrigerator 4 includes refrigerator components arranged in sequence (not labeled in the attached drawings): refrigerator left connecting pipe 17, refrigerator buffer chamber 18, refrigerator low temperature heat exchanger 19, refrigerator regenerator 20, refrigerator room temperature heat exchanger 21, refrigerator compression chamber 22, refrigerator piston 23, refrigerator expansion chamber 24, and refrigerator right connecting pipe 25. The refrigerator left connecting pipe 17 is connected to the refrigerator buffer chamber 18, and the refrigerator right connecting pipe 25 is connected to the refrigerator expansion chamber 24.

[0042] This invention provides two embodiments of a heat-driven Stirling refrigeration system 1; please refer to [link / reference]. Figure 1 One type is a free piston type thermally driven double-acting Stirling refrigeration system, in which the engine compression chamber 15 of the Stirling engine 3 is connected to the engine buffer chamber 9 of the adjacent Stirling engine 3, and the refrigeration expansion chamber 24 of the Stirling refrigeration machine 4 is connected to the refrigeration buffer chamber 18 of the adjacent Stirling refrigeration machine 4. That is, the engine left connecting pipe 8 of the Stirling engine 3 is connected to the engine right connecting pipe 16 of the adjacent Stirling engine 3, and the refrigeration left connecting pipe 17 of the Stirling refrigeration machine 4 is connected to the refrigeration right connecting pipe 25 of the adjacent Stirling refrigeration machine 4.

[0043] Specifically, in the Stirling engine 3 section, a double-acting Stirling engine 3 structure is adopted. Each stage of the Stirling engine 3 is connected to form a loop. Each engine piston 14 is a free piston and can function as both a compression piston and an expansion piston. In the technical solution provided by this invention, the engine piston 14 mainly plays the role of gas distribution and phasing, while also transmitting acoustic power to supply energy to the Stirling refrigerator 4. The Stirling refrigerator 4 consumes the acoustic power transmitted by the piston, obtains a cooling effect in the refrigerator regenerator 20, and absorbs heat from the outside at the refrigerator low-temperature heat exchanger 19 to obtain cooling capacity. The Stirling engines 3 or the Stirling refrigerator 4 together form a complete Alpha-type Stirling core unit.

[0044] The free-piston type heat-driven double-acting Stirling refrigeration system increases the number of double-effect Stirling heat engines and provides energy to the Stirling refrigerator 4 through the double-acting Stirling engine 3 structure, thereby enabling the entire system to achieve a larger cooling capacity and making it more suitable for applications with high requirements for cooling capacity and specific power. Furthermore, from the perspective of the double-acting engine, this structure improves the traditional moving-part type double-acting Stirling engine 3 into a free-piston type, eliminating oil lubrication and lateral friction losses, significantly improving the system's lifespan and reliability. The engine piston 14, as the resonant mechanism of the double-acting Stirling engine 3, plays a crucial role in phase adjustment, and its coupling with the Stirling refrigerator 4 also effectively solves this problem. It should also be noted that if the cold and hot temperature zones of the Stirling refrigerator 4 are adjusted to room temperature and high temperature respectively, the entire system can constitute a heat pump system; if the heating temperatures of each Stirling engine 3 or the cooling temperatures of each refrigerator are inconsistent, it can also constitute a variable-temperature utilization heat engine system, realizing multiple applications of this system.

[0045] Further, please refer to Figure 2 Another implementation is a heat-driven, double-effect, double-acting coupled Stirling refrigeration system. In this system, only the engine buffer chamber 9 of the Stirling engine 3 is connected to the engine compression chamber 15 of the adjacent Stirling engine 3; that is, the left connecting pipe 8 of the Stirling engine 3 is connected to the right connecting pipe 16 of the adjacent Stirling engine 3. Because the connections between the Stirling refrigeration units 4 are eliminated, the double-effect Stirling engines 3 are directly coupled throughout the system. Each Stirling unit 2 is a double-effect free-piston Stirling heat engine, and each Stirling unit 2 can meet the corresponding cooling or heat pumping requirements in different temperature zones.

[0046] It should be noted that the number of units in the two implementation methods described above needs to be adjusted according to the specific application scenario. Generally, the number of Stirling units 2 needs to exceed three units (phase difference 120 degrees), or it can be four units (phase difference 90 degrees), six units (phase difference 60 degrees) or more units. This invention does not limit this.

[0047] Specifically, a back cavity 7 is provided between the corresponding Stirling engine 3 and Stirling refrigerator 4, and the back cavity 7 is spaced apart from the Stirling engine 3 and Stirling refrigerator 4; the piston rod 6 is movably inserted through the gap in the back cavity 7. Based on the above two embodiments, please refer to... Figure 3 The heat-driven Stirling refrigeration system 1 also includes a linear motor 5 located in the back cavity 7, with a piston rod 6 driving the linear motor 5. The linear motor 5 includes a stator 26 and a mover 27. The stator 26 is located on the inner wall of the back cavity 7, and the mover 27 is connected to the piston rod 6 to move under the drive of the piston rod 6. During the reciprocating motion of the piston rod 6, it drives the mover 27, causing alternating magnetic flux to be generated inside the stator 26, thereby generating current. Thus, the system can both refrigerate and generate electricity, achieving combined cooling and power generation (CCHP). If the temperature range of the Stirling refrigerator 4 is changed to use it as a heat pump, combined heat and power (CHP) can also be achieved.

[0048] This invention provides a heat-driven Stirling refrigeration system 1. The overall system structure is simple, and a single Stirling unit 2 can realize the dual functions of a Stirling engine 3 and a Stirling refrigerator 4, while also featuring high power density. Furthermore, the double-acting structure provides phase adjustment functionality for a single double-effect structure, facilitating stable system operation. This structure reduces traditional lateral friction losses, significantly improving the lifespan and reliability of the refrigeration system, while also increasing the system's cooling capacity and power density, enabling the system to be applied in a wider range of fields.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A thermally driven Stirling refrigeration system, characterized in that, The heat-driven Stirling refrigeration system comprises a plurality of Stirling units connected in sequence, each of the Stirling units comprising oppositely arranged one Stirling engine and one Stirling refrigerator, the Stirling engine having an engine piston, the Stirling refrigerator having a refrigerator piston, the engine piston and the refrigerator piston being arranged at two ends of a piston rod for transmitting mechanical work; wherein two adjacent Stirling engines are connected to each other, and two adjacent Stirling refrigerators are connected to each other, or two adjacent Stirling engines are connected to each other, and each of the Stirling refrigerators is not connected to each other; each of the Stirling engines comprises an engine left connecting pipe, an engine buffer cavity, an engine room temperature heat exchanger, an engine regenerator, an engine high temperature heat exchanger, an engine expansion cavity, an engine piston, an engine compression cavity and an engine right connecting pipe, the engine left connecting pipe being in communication with the engine buffer cavity, and the engine right connecting pipe being in communication with the engine compression cavity; the engine right connecting pipe of each of the Stirling engines is in communication with the engine left connecting pipe of the right adjacent Stirling engine; each of the Stirling refrigerators comprises a refrigerator left connecting pipe, a refrigerator buffer cavity, a refrigerator low temperature heat exchanger, a refrigerator regenerator, a refrigerator room temperature heat exchanger, a refrigerator compression cavity, a refrigerator piston, a refrigerator expansion cavity and a refrigerator right connecting pipe, the refrigerator left connecting pipe being in communication with the refrigerator buffer cavity, and the refrigerator right connecting pipe being in communication with the refrigerator expansion cavity; in the case that two adjacent Stirling refrigerators are connected to each other, the refrigerator right connecting pipe of each of the Stirling refrigerators is in communication with the refrigerator left connecting pipe of the right adjacent Stirling refrigerator.

2. The thermodynamically driven Stirling refrigeration system of claim 1, wherein, The number n of the Stirling units satisfies the following relationship: n≥3.

3. The thermodynamically driven Stirling refrigeration system of claim 2, wherein, When the number n of the Stirling units is 3, the phase difference of each of the Stirling units is 120 degrees; when the number n of the Stirling units is 4, the phase difference of each of the Stirling units is 90 degrees; and when the number n of the Stirling units is 6, the phase difference of each of the Stirling units is 60 degrees.

4. The thermodynamically driven Stirling refrigeration system of claim 1, wherein, The oppositely arranged Stirling engine and Stirling refrigerator have a back cavity, and the back cavity is arranged in space apart from the Stirling engine and the Stirling refrigerator; the piston rod movably penetrates the internal space of the back cavity, and the heat-driven Stirling refrigeration system further comprises a linear motor arranged in the back cavity, and the piston rod is used for driving the linear motor.

5. The thermodynamically driven Stirling refrigeration system of claim 4, wherein, The linear motor comprises a stator and a mover, the stator is arranged on the inner wall surface of the back cavity, and the mover is connected with the piston rod to move under the driving of the piston rod.

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