Double-acting Stirling cryocooler / heat pump

Abstract

The utility model discloses a double-acting Stirling cryocooler / heat pump which comprises a refrigeration / heat pump loop, an air cylinder assembly, a machine body assembly, a piston assembly and a driving system. The air cylinder assembly comprises a first air cylinder body and a second air cylinder body. The machine body assembly comprises a crankshaft which is provided with a cold end piston connecting rod neck and a hot end piston connecting rod neck. The piston assembly comprises a cold end piston and a hot end piston. The cold-end piston first cylinder body is divided into an upper cold cavity and a lower cold cavity; the hot end piston divides the second cylinder body into an upper hot cavity and a lower hot cavity; the cold and hot end pistons are connected with cold and hot end piston connecting rod necks through piston rods; in the refrigeration / heat pump loop, a first loop comprises an upper cold cavity, a first cold end heat exchanger, a first heat regenerator, a first hot end heat exchanger and an upper hot cavity which are communicated in sequence; and the second loop comprises a lower cold cavity, a second cold end heat exchanger, a second heat regenerator, a second hot end heat exchanger and a lower hot cavity which are communicated in sequence. The Stirling cryocooler / heat pump can solve the problems that an existing Stirling cryocooler / heat pump is low in refrigerating / heating efficiency and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of Stirling, in particular to a double-acting Stirling refrigerator / heat pump. Background Art

[0002] Stirling technology has made tremendous progress since its development in 1816. It is well-known for its advantages such as wide heat source and stable operation in the positive cycle, wide operating temperature range and high efficiency in the reverse cycle, and has broad room for development.

[0003] A Stirling refrigerator and a Stirling heat pump are different names for the same device, operating based on a reverse Stirling cycle, consuming mechanical energy to transfer heat. When heat is removed from the cold side to cool an object, it's called a Stirling refrigerator; when heat is absorbed from the hot side to heat an object, it's called a Stirling heat pump. Stirling heat pumps typically use the inert gas helium as a working fluid, which has zero global warming potential and zero ozone depletion potential, making them environmentally friendly. Research shows that compared to gas and oil-fired boilers, Stirling heat pumps can reduce environmental impact by over 10%, and up to 40%. Due to helium's extremely low liquefaction temperature and excellent thermal conductivity, no phase change occurs during refrigeration / heat pump operation, resulting in a wide operating temperature range. As a heat pump, they can provide high temperatures up to 200°C for industries such as food, chemicals, textiles, and mechanical processing, with a COP of 1.5-2.0.

[0004] For example, Chinese patent publication CN107560212A discloses a double-effect free-piston Stirling heat-driven refrigerator / heat pump system, comprising a double-effect free-piston Stirling refrigerator circuit and a reciprocating resonator. The double-effect free-piston Stirling refrigerator circuit includes an engine intermediate-temperature radiator, an engine regenerator, an engine heater, an engine heat buffer tube, a refrigerator intermediate-temperature radiator, a refrigerator regenerator, a refrigerator cold-end heat exchanger, and a refrigerator discharger, all connected end-to-end. The reciprocating resonator is connected to the engine intermediate-temperature radiator and the refrigerator discharger.

[0005] Chinese patent publication number CN103890365A discloses a reverse piston gamma-type free piston Stirling engine with improved stability, efficiency, and controllability, comprising a displacer, a power piston, a displacer rod, an electromagnetic linear transducer, and an electronic controller. The displacer is mounted in a displacer cylinder and reciprocates along a reciprocating displacer axis to periodically vary the distribution ratio of the working gas between the expansion space and the compression space. The power piston is mounted in the piston cylinder, oppositely arranged around the reciprocating displacer axis, adapted to reciprocate along the reciprocating piston axis. The displacer rod is fixed to the displacer between the pistons and extends from the displacer beyond the reciprocating piston axis. The electromagnetic linear transducer is drivingly connected to the displacer rod on the opposite side of the reciprocating piston axis from the displacer. The output of the electronic controller is connected to the linear transducer, and controls the displacer so that the amplitude of its reciprocating motion is a function of acquired data and its operating parameters.

[0006] However, the free-piston Stirling heat engines that currently use a mass-spring-damper resonant system have problems such as complex structure, high control difficulty, and immature technology. Utility Model Content

[0007] The utility model provides a double-acting Stirling refrigerator / heat pump, which adopts a double-acting arrangement structure and a crank-connecting rod transmission mechanism, has few parts, high system efficiency, low cost, and a compact structure, and can solve the problem of low cooling / heating efficiency in existing Stirling refrigerators / heat pumps.

[0008] A double-acting Stirling refrigerator / heat pump comprising a refrigeration / heat pump circuit, a cylinder assembly, a body assembly, a piston assembly, and a drive system;

[0009] The cylinder assembly includes a first cylinder body and a second cylinder body;

[0010] The fuselage assembly includes a fuselage and a crankshaft rotatably disposed within the fuselage, one end of the crankshaft being connected to a drive system; a cold-end piston connecting rod neck and a hot-end piston connecting rod neck are disposed on the crankshaft at positions corresponding to the first cylinder block and the second cylinder block; the cold-end piston connecting rod neck is ahead of the hot-end piston connecting rod neck in phase;

[0011] The piston assembly includes a cold end piston and a hot end piston; the cold end piston is arranged in the first cylinder body, dividing the first cylinder body into an upper cold chamber and a lower cold chamber; the hot end piston is arranged in the second cylinder body, dividing the second cylinder body into an upper hot chamber and a lower hot chamber;

[0012] The cold end piston is connected to the cold end piston connecting rod neck through the piston rod, and the hot end piston is connected to the hot end piston connecting rod neck through the piston rod, and a bearing mechanism is provided at the connection part;

[0013] The refrigeration / heat pump circuit includes a first circuit and a second circuit; the first circuit includes an upper cold chamber, a first cold-end heat exchanger, a first heat regenerator, a first hot-end heat exchanger and an upper hot chamber connected in sequence through pipelines; the second circuit includes a lower cold chamber, a second cold-end heat exchanger, a second heat regenerator, a second hot-end heat exchanger and a lower hot chamber connected in sequence through pipelines.

[0014] Furthermore, the first cylinder block and the second cylinder block are respectively provided with a first water cooling jacket and a second water cooling jacket.

[0015] Further preferably, the first water cooling jacket and the second water cooling jacket are connected to each other for passing cooling water to cool the first cylinder block and the second cylinder block. The cooling principle is as follows:

[0016] The cooling water enters the first water-cooling jacket and the second water-cooling jacket in sequence through the cylinder water channel inlet pipe to cool the first cylinder body and the second cylinder body, and the cooling water temperature increases; after flowing out of the second water-cooling jacket, the cooling water flows into the second cold-end heat exchanger and the first cold-end heat exchanger in sequence through the connecting pipe, exchanges heat with the low-temperature working medium gas in the heat exchange pipe, and the cooling water temperature decreases; finally, it flows out through the cylinder water channel outlet pipe; the heat medium flows into the second hot-end heat exchanger through the hot-end inlet pipe, then flows through the first hot-end heat exchanger, and flows out from the hot-end outlet pipe.

[0017] Furthermore, piston rings are provided on the outer circumferential surfaces of the cold-end piston and the hot-end piston; guide sleeves are provided at the lower parts of the first cylinder block and the second cylinder block, and the piston rod passes through the inner hole of the guide sleeve to transmit the mechanical work of the crankshaft to the cold-end piston and the hot-end piston.

[0018] Furthermore, the drive system includes a power unit, and the output shaft of the power unit is connected to one end of the crankshaft through a coupling and a flywheel.

[0019] Preferably, the cold-end piston connecting rod neck leads the hot-end piston connecting rod neck by 80 to 100 degrees in phase.

[0020] Furthermore, the hot-end piston reciprocates in the second cylinder body, compressing the working fluid gas in the upper hot chamber and the lower hot chamber to perform work; the cold-end piston reciprocates in the first cylinder body, changing the volume of the upper cold chamber and the lower cold chamber, and adjusting the working fluid gas to flow back and forth between the upper cold chamber and the upper hot chamber, and the lower cold chamber and the lower hot chamber.

[0021] Furthermore, the cold-end piston and the hot-end piston reciprocate once in the cylinder body, and both participate in the reverse Stirling cycle of the first circuit and the second circuit respectively, that is, the double-acting cycle described in the present invention.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This utility model adopts a double-acting structure. Compared with conventional single-acting Stirling refrigerators / heat pumps, the number of pistons and cylinders is reduced by 50%. Two pistons and two cylinders can realize two reverse Stirling cycles, with high power density, a small number of parts and a compact system structure.

[0024] 2. The utility model utilizes a crank-connecting rod mechanism drive solution, with mature component technology, low cost, and easy maintenance; the crank-connecting rod mechanism ensures that the pistons operate with a constant phase difference and are not affected by the operating temperature, making the utility model have the advantages of high efficiency, wide operating temperature range, and stable variable load operation.

[0025] 3. This double-acting Stirling refrigerator / heat pump can be assembled into multiple functional modules to form a multi-cylinder double-acting Stirling refrigerator / heat pump, further enhancing its advantages of high cooling / heating capacity and low vibration and noise during operation. The cold-end heat exchanger, regenerator, and hot-end heat exchanger can be independently arranged without coupling to the cylinder assembly, simplifying processing and simplifying the system structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of a double-acting Stirling refrigerator / heat pump according to the present invention;

[0027] Figure 2 This is a water connection diagram of a double-acting Stirling refrigerator / heat pump of the utility model;

[0028] Figure 3 This is a solution for assembling a double-acting Stirling refrigerator / heat pump in the utility model;

[0029] Figure 4 This is another assembly scheme of a double-acting Stirling refrigerator / heat pump of the utility model.

[0030] In the figure: 1-refrigeration / heat pump circuit; 101-first circuit; 102-second circuit; 103-first cold-end heat exchanger; 104-first regenerator; 105-first hot-end heat exchanger; 106, 107-pipeline; 108-second cold-end heat exchanger; 109-second regenerator; 110-second hot-end heat exchanger; 111, 112-pipeline; 113-cylinder waterway inlet pipe; 114-cylinder waterway outlet pipe; 115-hot-end inlet pipe; 116-hot-end outlet pipe; 2-cylinder assembly; 201-first cylinder unit; 202-second cylinder unit; 203-first 1-cylinder block; 204-second cylinder block; 205-upper cold chamber; 206-lower cold chamber; 207-upper hot chamber; 208-lower hot chamber; 209-first water-cooling jacket; 210-second water-cooling jacket; 3-body assembly; 301-crankshaft; 302-cold-end piston connecting rod neck; 303-hot-end piston connecting rod neck; 304-body; 305-base; 4-piston assembly; 401-cold-end piston; 402-hot-end piston; 403-piston rod; 404-piston ring; 405-guide sleeve; 5-drive system; 501-power unit; 502-coupling; 503-flywheel. DETAILED DESCRIPTION

[0031] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate understanding of the present invention and do not have any limiting effect on the present invention.

[0032] like Figure 1 As shown, a double-acting Stirling refrigerator / heat pump includes a refrigeration / heat pump circuit 1, a cylinder assembly 2, a body assembly 3, a piston assembly 4 and a drive system 5.

[0033] The cylinder assembly 2 includes a first cylinder unit 201 composed of a first cylinder block 203 and a second cylinder unit 202 composed of a second cylinder block 204 .

[0034] The fuselage assembly 3 includes a fuselage 304 and a crankshaft 301 rotatably arranged inside the fuselage 304. The fuselage 304 is fixed on a base 305, and one end of the crankshaft 301 is connected to the drive system 5. A cold-end piston connecting rod neck 302 and a hot-end piston connecting rod neck 303 are provided on the crankshaft 301 at positions corresponding to the first cylinder block 203 and the second cylinder block 204. The cold-end piston connecting rod neck 302 is ahead of the hot-end piston connecting rod neck 303 in phase by approximately 80 to 100 degrees.

[0035] The piston assembly 4 includes a cold-end piston 401 , a hot-end piston 402 , a piston rod 403 , a piston ring 404 and a guide sleeve 405 .

[0036] The cold-end piston 401 is disposed within the first cylinder block 203, dividing the first cylinder block 203 into an upper cold chamber 205 and a lower cold chamber 206. The hot-end piston 402 is disposed within the second cylinder block 204, dividing the second cylinder block 204 into an upper hot chamber 207 and a lower hot chamber 208. The cold-end piston 401 and the hot-end piston 402 are connected to the cold-end piston connecting rod neck 302 and the hot-end piston connecting rod neck 303, respectively, via corresponding piston rods 403. Bearing mechanisms are provided at these connections.

[0037] The outer circumferences of the cold-end piston 401 and the hot-end piston 402 are provided with piston rings 404. These are made of a wear-resistant polymer non-metallic material and are used to seal the high-pressure working fluid within the upper and lower hot chambers 207 and 208, and the upper and lower cold chambers 205 and 206. Guide sleeves 405 are installed at the mating surfaces of the piston rod 403 and the first and second cylinder blocks 203 and 204, respectively. These sleeves are mounted on the first and second cylinder blocks 203 and 204 and serve both sealing and guiding functions. These sleeves are made of a wear-resistant polymer non-metallic material. The piston rod 403 passes through the inner bore of the guide sleeves 405, transmitting the mechanical work of the crankshaft 301 to the cold-end piston 401 and the hot-end piston 402.

[0038] The driving system 5 includes a power unit 501, a coupling 502 and a flywheel 503. The power unit 501 can be a power device such as an electric motor, a gas or oil engine, etc.

[0039] The refrigeration / heat pump circuit 1 includes a first circuit 101 and a second circuit 102 (i.e., a Stirling refrigeration / heat pump unit). The first circuit 101 includes an upper cold chamber 205, a pipeline 106, a first cold-end heat exchanger 103, a first regenerator 104, a first hot-end heat exchanger 105, a pipeline 107, and an upper hot chamber 207, which are connected in sequence. The second circuit 102 includes a lower cold chamber 206, a pipeline 111, a second cold-end heat exchanger 108, a second regenerator 109, a second hot-end heat exchanger 110, a pipeline 112, and a lower hot chamber 208, which are connected in sequence.

[0040] Among them, the first cold end heat exchanger 103 and the second cold end heat exchanger 108, the first hot end heat exchanger 105 and the second hot end heat exchanger 110 are all shell and tube heat exchangers, and the first regenerator 104 and the second regenerator 109 are located between the cold end heat exchanger and the hot end heat exchanger, and are made of stacked metal woven wire mesh.

[0041] The first cylinder block 203 and the second cylinder block 204 are respectively provided with a first water-cooling jacket 209 and a second water-cooling jacket 210 , and are connected to each other through pipelines.

[0042] like Figure 2As shown, the cooling water enters the first water-cooling jacket 209 and the second water-cooling jacket 210 in sequence through the cylinder waterway inlet pipe 113 to cool the first cylinder block 203 and the second cylinder block 204, thereby preventing the piston ring 404 from failing due to high temperature and increasing the cooling water temperature. After flowing out of the second water-cooling jacket 210, the cooling water flows through the connecting pipe in sequence into the second cold-end heat exchanger 108 and the first cold-end heat exchanger 103, exchanging heat with the low-temperature working fluid gas in the heat exchange tube, thereby reducing the cooling water temperature. Finally, the cooling water flows out through the cylinder waterway outlet pipe 114. With this design, for a heat pump, the cooling water can not only cool the first cylinder block 203 and the second cylinder block 204, but also reduce the heat input to the second cold-end heat exchanger 108 and the first cold-end heat exchanger 103, thereby improving the system's heating COP.

[0043] like Figure 2 As shown, the heat medium flows into the second hot-end heat exchanger 110 through the hot-end inlet pipe 115, then flows through the first hot-end heat exchanger 105, and flows out of the hot-end outlet pipe 116. With this design, for the heat pump, when the initial temperature of the heat medium is low, the second hot-end heat exchanger 110 preheats it, and then the first hot-end heat exchanger 105 heats it to the required high temperature, reducing the heat exchange temperature difference between the heat medium and the hot-end heat exchanger, further improving the system heating COP.

[0044] In order to increase the output power of the refrigerator / heat pump, the number of cylinder assemblies 2 can be increased by integer multiples to assemble the machine, such as Figure 3 The L-shaped arrangement shown, Figure 4 The V-shaped arrangement shown makes the structure more compact and can reduce vibration and noise during equipment operation.

[0045] During operation of the double-acting Stirling refrigeration / heat pump of the present invention, the power unit 501 stably transmits mechanical energy to the crankshaft 301 through the coupling 502 and the flywheel 503. The cold-end piston connecting rod neck 302 and the hot-end piston connecting rod neck 303 on the crankshaft 301 drive the cold-end piston 401 and the hot-end piston 402 to reciprocate in the first cylinder block 203 and the second cylinder block 204 respectively through the piston rod 403. Because the cold-end piston connecting rod neck 302 is ahead of the hot-end piston connecting rod neck 303 in phase, the cold-end piston 401 and the hot-end piston 402 indirectly connected thereto operate according to the designed phase difference. The working fluid gas flows back and forth between the upper cold chamber 205 and the upper hot chamber 207 of the first circuit 101 and between the lower cold chamber 206 and the lower hot chamber 208 of the second circuit 102. The crankshaft 301 participates in two Stirling reverse cycles during one rotation. Each circuit completes four thermodynamic processes: isothermal compression, constant volume heat release, isothermal expansion, and constant volume heat absorption. Taking the first circuit 101 (i.e., the Stirling refrigeration / heat pump unit) as an example:

[0046] Isothermal compression: The cold-end piston 401 runs upward to the top dead center, and the hot-end piston 402 runs upward from the bottom dead center. The volume of the upper hot chamber 207 decreases, and the pressure of the working gas increases. It flows out of the upper hot chamber 207 and enters the first hot-end heat exchanger 105 to exchange heat with the heat medium in the first hot-end heat exchanger 105. The temperature of the heat medium increases, while the temperature of the working gas remains unchanged. The volume decreases and the pressure increases, thereby achieving isothermal compression.

[0047] Constant volume heat release: The cold end piston 401 moves downward from the top dead center, and the hot end piston 402 continues to move upward and reaches the top dead center. The upper cold cavity 205 increases, and the upper hot cavity 207 decreases. The working fluid gas flows out of the first hot end heat exchanger 105 and flows into the first cold end heat exchanger 103 and the upper cold cavity 205 through the first regenerator 104. It is cooled when flowing through the first regenerator 104. The gas volume remains unchanged, and the temperature and pressure decrease, thereby achieving constant volume heat release.

[0048] Isothermal expansion: The cold-end piston 401 continues to move downward and reaches the bottom dead center, and the hot-end piston 402 moves downward from the top dead center. The volume of the upper cold cavity 205 increases, and the working fluid gas flows out of the first regenerator 104 and enters the first cold-end heat exchanger 103 for heat exchange. After absorbing heat, it flows into the upper cold cavity 205. The temperature of the first cold-end heat exchanger 103 decreases, the gas temperature remains unchanged, the volume increases, and the pressure decreases.

[0049] Constant volume heat absorption: the cold end piston 401 moves upward from the bottom dead center to reach the initial position, the hot end piston 402 continues to move downward and reaches the bottom dead center, the upper cold chamber 205 decreases, the upper hot chamber 207 increases, and the working fluid gas flows out of the first cold end heat exchanger 103 and enters the first hot end heat exchanger 105 and the upper hot chamber 207 through the first regenerator 104. It is heated when flowing through the first regenerator 104, the gas volume remains unchanged, and the temperature and pressure increase.

[0050] In this way, the temperature of the first hot end heat exchanger 105 gradually increases, and the second hot end heat exchanger 110 also works in this way until the temperature of the heat medium is heated to the required high temperature.

[0051] The utility model adopts a double-acting and crank-connecting rod structure, and has the advantages of high power density, high efficiency, a small number of parts, a simple structure, a wide operating temperature range and stable variable load operation. It has broad application prospects in food and beverage processing, chemical industry, papermaking and textile industries, and the COP can reach 1.5-2.0, which is energy-saving and efficient.

[0052] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A double-acting Stirling refrigerator / heat pump, characterized in that: It includes a refrigeration / heat pump circuit (1), a cylinder assembly (2), a body assembly (3), a piston assembly (4) and a drive system (5); The cylinder assembly (2) comprises a first cylinder body (203) and a second cylinder body (204); The body assembly (3) includes a body (304) and a crankshaft (301) rotatably arranged inside the body (304), one end of the crankshaft (301) being connected to a drive system (5); a cold-end piston connecting rod neck (302) and a hot-end piston connecting rod neck (303) are provided on the crankshaft (301) at positions corresponding to the first cylinder block (203) and the second cylinder block (204); the cold-end piston connecting rod neck (302) is ahead of the hot-end piston connecting rod neck (303) in phase; The piston assembly (4) comprises a cold-end piston (401) and a hot-end piston (402); the cold-end piston (401) is arranged in the first cylinder body (203), dividing the first cylinder body (203) into an upper cold chamber (205) and a lower cold chamber (206); the hot-end piston (402) is arranged in the second cylinder body (204), dividing the second cylinder body (204) into an upper hot chamber (207) and a lower hot chamber (208); The cold end piston (401) is connected to the cold end piston connecting rod neck (302) through a piston rod, and the hot end piston (402) is connected to the hot end piston connecting rod neck (303) through a piston rod; The refrigeration / heat pump circuit (1) comprises a first circuit (101) and a second circuit (102); the first circuit (101) comprises an upper cold chamber (205), a first cold-end heat exchanger (103), a first regenerator (104), a first hot-end heat exchanger (105) and an upper hot chamber (207) which are connected in sequence; the second circuit (102) comprises a lower cold chamber (206), a second cold-end heat exchanger (108), a second regenerator (109), a second hot-end heat exchanger (110) and a lower hot chamber (208) which are connected in sequence.

2. The double-acting Stirling refrigerator / heat pump according to claim 1, characterized in that: The first cylinder block (203) and the second cylinder block (204) are respectively provided with a first water-cooling jacket (209) and a second water-cooling jacket (210).

3. The double-acting Stirling refrigerator / heat pump according to claim 2, characterized in that: The first water-cooling jacket (209) and the second water-cooling jacket (210) are connected to each other.

4. The double-acting Stirling refrigerator / heat pump according to claim 1, characterized in that: The outer circumferential surfaces of the cold-end piston (401) and the hot-end piston (402) are provided with piston rings (404); the lower parts of the first cylinder body (203) and the second cylinder body (204) are both provided with guide sleeves (405); the piston rod passes through the inner hole of the guide sleeve (405) to transmit the mechanical work of the crankshaft (301) to the cold-end piston (401) and the hot-end piston (402).

5. The double-acting Stirling refrigerator / heat pump according to claim 1, characterized in that: The driving system (5) comprises a power unit (501), and the output shaft of the power unit (501) is connected to one end of the crankshaft (301) through a coupling (502) and a flywheel (503).

6. The double-acting Stirling refrigerator / heat pump according to claim 1, characterized in that: The cold end piston connecting rod neck (302) leads the hot end piston connecting rod neck (303) by 80 to 100 degrees in phase.

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