Integrated Structure and Processing Technology of Heat Exchanger and Pressure Shell for Stirling Device

Abstract

The present invention discloses an integrated structure of a heat exchanger and a pressure shell for a Stirling device, which includes a pressure shell body. The upper part of the pressure shell body is a hollowed heat exchange structure formed by multiple groups of columnar parts. The columnar parts are evenly distributed along the circumferential direction of the pressure shell body. Each group of columnar parts includes two inner and outer columnar monomers. A slender hole flow channel is arranged along the length direction inside the columnar monomer. One ends of the two slender hole flow channels of each group of columnar monomers are connected at the top inside the pressure shell body. The other end of the inner circumferential slender hole flow channel is connected to the expansion cavity formed by the lower part of the pressure shell body and the displacer. The other end of the outer circumferential slender hole flow channel is adjacent to the end face of the regenerator. This integrated structure of the heat exchanger and the pressure shell can be formed by two methods: machining and casting. The casting forming scheme does not require welding, has excellent airtightness, low large-scale production cost, can significantly improve the reliability and service life of the Stirling device, and is especially suitable for the application of medium and large Stirling devices.

Description

Technical Field

[0001] The present invention relates to the technical field of Stirling devices, and in particular to an integrated structure and processing technology of a heat exchanger and a pressure shell for a Stirling device. Background Art

[0002] The Stirling device operates on the Stirling cycle and is a closed-cycle machine based on the temperature difference of a heat source; the working medium is usually helium, which is environmentally friendly. It is divided into two categories according to its use: the one using the forward Stirling cycle is called a Stirling engine. The working medium in the device absorbs heat and expands at high temperature and releases heat and compresses at normal temperature. The obtained expansion work is greater than the compression work, so as to convert thermal energy into mechanical energy; the one using the reverse Stirling cycle is called a Stirling refrigerator. The device needs to consume mechanical energy to realize the heat release and compression of the working medium at normal temperature and the heat absorption and expansion at low temperature to produce a refrigeration effect. The heat exchange between the Stirling device and the external heat source is of the partition type. Therefore, the engine can be adapted to various heat source types such as gas, liquid, and solid fuels, medium and high temperature waste heat, solar thermal energy, and nuclear reactor thermal energy, and is suitable for applications in scenarios such as underwater power, space power, solar dish power generation, and cogeneration. The refrigerator is used in fields such as infrared and superconducting device cooling, and biological and medical cold chain refrigeration.

[0003] At least two movers are required inside the Stirling machine to realize the volume change of the expansion chamber and the compression chamber. The mover adjacent to the compression chamber at the end is called a power piston or a compression piston, and the mover adjacent to the expansion chamber at the end is called a displacer or a distribution piston; the reciprocating motion of the two movers will drive the working medium to reciprocate between the expansion chamber and the compression chamber through the adjacent heat exchanger, regenerator, and cooler channels. The pressure of the working medium will experience a periodic change that is not synchronized with the displacement of the mover during this process, thereby generating heat-work conversion. The cooler is arranged between the compression chamber and the normal temperature end face of the regenerator, and the common types are partition fin type or shell and tube type, and the compression heat generated by the working medium during the compression process is carried and released by the external air flow or water flow.

[0004] The heat exchanger is arranged between the expansion chamber and the non-constant temperature end face of the regenerator. In a small Stirling refrigerator, due to the small load of the heat exchanger, generally, a fin structure or a copper foil is folded and then brazed to the inner wall of the pressure shell to meet the application requirements. For large machines, especially high-power Stirling engines, the heat exchanger has a very large heat transfer load, and the heat transfer amount can reach dozens or even hundreds of kilowatts. Only by allowing the working fluid flowing out of the regenerator to be fully heated before entering the expansion chamber for expansion can an efficiency index with engineering significance be achieved. Therefore, a tube bundle type heat exchanger is generally used in medium and large Stirling devices. The advantage of the tube bundle type structure is that the internal free volume is small, but the external heat transfer surface area is large, and the flow distance of the working fluid in the tube is long, so the heat transfer is sufficient. Its disadvantage is that both ends of each tube in the tube bundle need to be welded to the corresponding positions on the pressure shell, usually there are dozens to hundreds of welding points, resulting in complex assembly and welding processes; moreover, under the dual action of thermal stress and internal alternating air pressure, the welding points are prone to cracking and failure. Therefore, it is not suitable for applications in scenarios requiring high reliability, long life, and maintenance-free requirements. Summary of the Invention

[0005] In view of the above technical problems, the present invention proposes a heat exchanger and pressure shell integrated structure and processing technology for Stirling devices. This heat exchanger and pressure shell integrated structure combines the heat exchanger and the pressure shell, two separate components, into one, processes the heat exchanger into a part of the pressure shell, retains the advantages of the tube bundle type heat exchanger, and avoids its disadvantages. The heat exchanger and pressure shell integrated structure can be formed by two methods: machining and casting. The casting forming scheme does not require welding, has excellent airtightness, high reliability, and low mass production cost, and can effectively improve the service life and cost performance of Stirling devices; the machining forming scheme has a short processing cycle and easy parameter adjustment, and is suitable for prototype development and small batch production.

[0006] A heat exchanger and pressure shell integrated structure for Stirling devices, including a pressure shell body. The upper part of the pressure shell body is a hollow heat exchange structure formed by multiple groups of columnar parts. The columnar parts are evenly distributed along the circumferential direction of the pressure shell body. Each group of columnar parts includes two inner and outer columnar monomers. A slender hole flow channel is arranged along the length direction inside the columnar monomer. One ends of the two slender hole flow channels of each group of columnar monomers are connected at the top inside the pressure shell body. The other end of the inner circumferential slender hole flow channel is connected to the expansion chamber formed by the lower part of the pressure shell body and the displacer, and the other end of the outer circumferential slender hole flow channel is adjacent to the end face of the regenerator.

[0007] As a preference of the above technical solution, the diameter of the slender hole flow channel is 2-4 mm.

[0008] As an optimization of the above technical solution, it further includes a ring-shaped embedded part, which is arranged at the top inside the pressure shell body. The ring-shaped embedded part includes a ring-shaped base and a 180° elbow pipe. One side of the ring-shaped base is evenly provided with semi-circular grooves along the circumference for cooperating with the 180° elbow pipe. The 180° elbow pipe is clamped in the semi-circular groove, and both ends of the 180° elbow pipe are communicated with two slender hole channels in the same group of columnar monomers.

[0009] As an optimization of the above technical solution, the melting point of the ring-shaped embedded part is higher than that of the pressure shell body.

[0010] A processing technology for manufacturing the above-mentioned integrated structure of heat exchanger and pressure shell, and the specific processing steps are as follows:

[0011] Step 1, perform turning and milling compound processing to prepare the ring-shaped base of the ring-shaped embedded part;

[0012] Step 2, assemble the 180° elbow pipe, and sequentially and evenly clamp the 180° elbow pipe in the semi-circular grooves of the ring-shaped embedded part;

[0013] Step 3, assemble the ring-shaped embedded part in Step 2 with the casting mold of the pressure shell body, use ceramic cores to occupy the middle hollow part and the slender hole channels, and perform one-time casting to complete the processing of the integrated structure of the heat exchanger and the pressure shell.

[0014] As an optimization of the above technical solution, the pressure shell body includes a top cover and a pressure shell main body. The top cover is welded to the top of the pressure shell main body. The columnar part is located on the pressure shell main body. One side of the top cover facing the pressure shell main body is evenly provided with strip-shaped grooves along the circumference. The hole channels formed by the strip-shaped grooves and the pressure shell main body are used to communicate the two slender hole channels in each group of columnar monomers.

[0015] As an optimization of the above technical solution, a ring-shaped reinforcing rib is arranged in the middle of the columnar part parallel to the top cover.

[0016] As an optimization of the above technical solution, the columnar monomer is an irregular pentagon.

[0017] A processing technology for manufacturing the above-mentioned integrated structure of heat exchanger and pressure shell, and the specific processing steps are as follows:

[0018] Step 1, perform turning processing to manufacture the outer shape of the pressure shell main body;

[0019] Step 2, use a deep-hole machine tool to process the slender hole channels in the columnar monomers;

[0020] Step 3: Milling process to manufacture columnar monomers. The specific milling steps are as follows: First step, cut downward along the diameter of the pressure shell body to mill the gap between two adjacent groups of columnar parts and mill out a plate-shaped hollow part. Second step, parallel to the cross-section of the pressure shell body, cut obliquely downward in sequence along the outer circumference of the pressure shell body to penetrate two adjacent groups of plate-shaped hollow parts. Third step, cut symmetrically in sequence relative to the second step to form a columnar monomer with an irregular pentagon shape.

[0021] Step 4: Turn-milling composite machining to manufacture the top cover.

[0022] Step 5: Weld the top cover and the pressure shell body, thus completing the processing of the integrated structure of the heat exchanger and the pressure shell.

[0023] As an optimization of the above technical solution, in Step 3, the included angle between the cutting in the second and third steps and the cutting in the first step during milling is 25° - 35°.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The integrated structure of the heat exchanger and the pressure shell combines the heat exchanger and the pressure shell, two separate components, into one, and processes the heat exchanger into a part of the pressure shell. While retaining the advantages of traditional tube bundle heat exchangers, it avoids the deficiency of being prone to failure.

[0026] 2. For two different types of integrated structures of the heat exchanger and the pressure shell, machining and casting can be respectively used for production. Since casting requires mold opening, the trial production cycle is long, and the cost of mold modification and repair is high. In order to reduce the potential risks of upfront development costs and poor parameters, the machining structure type can be used for development and matching first to optimize the structural parameters of the pressure shell body and the hollow heat exchange structure, providing data support for the structural type processed by the casting method. After ensuring that the integrated structure type of the heat exchanger and the pressure shell can meet the actual application requirements, the casting type is used for mass production. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of Embodiment 1.

[0028] Figure 2 It is a longitudinal sectional view of Embodiment 1.

[0029] Figure 3 It is a schematic structural diagram of the annular embedded part in Embodiment 1.

[0030] Figure 4 It is a schematic structural diagram of Embodiment 2.

[0031] Figure 5 It is a longitudinal sectional view of Embodiment 2.

[0032] Figure 6It is a transverse sectional view of the second embodiment.

[0033] Figure 7 It is a schematic diagram of the first-step milling cross-section in the third processing step of the second embodiment.

[0034] Figure 8 It is a schematic diagram of the second-step milling cross-section in the third processing step of the second embodiment.

[0035] Figure 9 It is a schematic diagram of the third-step milling cross-section in the third processing step of the second embodiment.

[0036] The reference numerals are as follows: 1 - pressure shell body, 101 - top cover, 102 - pressure shell main body, 2 - columnar monomer, 3 - slender hole flow channel, 4 - annular embedded part, 401 - annular base, 402 - 180° elbow pipe, 5 - semi-circular groove, 6 - strip groove, 7 - annular reinforcing rib, 8 - plate-shaped hollow part, α - included angle. Specific Embodiment

[0037] Next, in conjunction with the drawings of the present invention, the technical solutions of the present invention will be clearly and completely described. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0038] Embodiment One

[0039] As Figures 1 to 3 shown, a heat exchanger and pressure shell integrated structure for a Stirling device includes a pressure shell body 1. The upper part of the pressure shell body 1 is a hollow heat exchange structure formed by multiple groups of columnar parts. The columnar parts are evenly distributed along the circumferential direction of the pressure shell body 1. Each group of columnar parts includes two inner and outer columnar monomers 2. A slender hole flow channel 3 is arranged along the length direction inside the columnar monomer 2. One end of the two slender hole flow channels 3 of each group of columnar monomers 2 is communicated at the inner top of the pressure shell body 1. The other end of the inner circumferential slender hole flow channel 3 is communicated with the expansion chamber formed by the lower part of the pressure shell body 1 and the displacer. The other end of the outer circumferential slender hole flow channel 3 is adjacent to the end face of the regenerator.

[0040] In this embodiment, the diameter of the slender hole flow channel 3 is 2 - 4 mm.

[0041] In this embodiment, it further includes an annular embedded part 4. The annular embedded part 4 is arranged at the inner top of the pressure shell body 1. The annular embedded part 4 includes an annular base 401 and a 180° elbow pipe 402. One side of the annular base 401 is evenly provided with semi-circular grooves 5 for cooperating with the 180° elbow pipe 402. The 180° elbow pipe 402 is clamped in the semi-circular groove 5, and both ends of the 180° elbow pipe 402 are communicated with the two slender hole flow channels 3 inside the same group of columnar monomers 2.

[0042] In this embodiment, the melting point of the annular embedded part 4 is higher than that of the pressure shell body 1.

[0043] A processing technology for manufacturing the above-mentioned integrated structure of the heat exchanger and the pressure shell, and the specific processing steps are as follows:

[0044] Step 1, perform turning and milling compound processing to prepare the annular base 401 of the annular embedded part 4;

[0045] Step 2, assemble the 180° elbow pipe 402, and sequentially and evenly snap the 180° elbow pipe 402 into the semi-circular groove 5 of the annular embedded part 4;

[0046] Step 3, assemble the annular embedded part 4 in Step 2 with the casting mold of the pressure shell body. The ceramic core is used to occupy the middle hollow part and the slender hole flow channel 3, and one-time casting is performed to complete the processing of the integrated structure of the heat exchanger and the pressure shell.

[0047] This embodiment is used as a mass production model of the integrated structure of the heat exchanger and the pressure shell. Through the innovative design of combining the embedded part with the hollow heat exchange structure, the integrated casting of the heat exchanger and the pressure shell is realized, without welding, with excellent airtightness, which can effectively improve the service life of the Stirling device, reduce the manufacturing cost, and has extremely high application value.

[0048] Embodiment 2

[0049] As Figures 4 to 6 shown, the difference between this embodiment and Embodiment 1 is that the pressure shell body 1 includes a top cover 101 and a pressure shell main body 102. The top cover 101 is welded to the top of the pressure shell main body 102. The columnar part is located on the pressure shell main body 102. A strip-shaped groove 6 is evenly arranged along the circumference on the side of the top cover 101 facing the pressure shell main body 102. The hole formed by the strip-shaped groove 6 and the pressure shell main body 102 is used to connect the two slender hole flow channels 3 in each columnar monomer 2.

[0050] In this embodiment, an annular reinforcing rib 7 is arranged parallel to the top cover in the middle of the columnar part.

[0051] In this embodiment, the columnar monomer 2 is an irregular pentagon.

[0052] A processing technology for manufacturing the above-mentioned integrated structure of the heat exchanger and the pressure shell, as Figures 7 to 9 shown, the specific processing steps are as follows:

[0053] Step 1, perform turning processing to manufacture the outer shape of the pressure shell main body 102;

[0054] Step 2, use a deep hole machine tool to process the slender hole flow channel in the columnar monomer;

[0055] Step 3: Milling process to manufacture the columnar monomer 2. The specific milling steps are as follows: First step, plunge cut along the diameter of the pressure shell body 102 to mill the gap between two adjacent groups of columnar parts, and mill out the plate-shaped hollow part 8. Second step, parallel to the cross-section of the pressure shell body 102, plunge cut obliquely downward in sequence along the outer circumference of the pressure shell body 102 to penetrate two adjacent groups of plate-shaped hollow parts 8. Third step, plunge cut symmetrically in sequence relative to the second step to form the columnar monomer 2 with an irregular pentagon shape.

[0056] Step 4: Turning-milling composite process to manufacture the top cover 101.

[0057] Step 5: Weld the top cover 101 and the pressure shell body 102, and thus complete the processing of the integrated structure of the heat exchanger and the pressure shell.

[0058] In this embodiment, in Step 3, the included angle between the plunge cuts in the second and third steps and the plunge cut in the first step is 25° - 35°.

[0059] For the integrated structure of the heat exchanger and the pressure shell manufactured by the solution of this embodiment, the processing cycle is short and the parameters are easy to adjust, which is suitable for the prototype development process and small-batch production. Since casting requires mold opening, the trial production cycle is long and the costs of mold modification and repair are high. In order to reduce the potential risks of early development costs and poor parameters, this embodiment can be first used for development and matching to optimize the structural parameters of the pressure shell body and the hollow heat exchange structure, providing data support for the structural types processed by the casting method. After ensuring that the integrated structure type of the heat exchanger and the pressure shell can meet the actual application requirements, the casting type is adopted for mass production. For the top cover 101 and the pressure shell body 102 of this embodiment, welding is required, and the welds are two circular welds on the inner and outer circumferences. Compared with the welding process of traditional tube bundle heat exchangers, the number of welding points is small, the working space of the welding torch is spacious, and leak detection is also easy to implement, and the process quality is easy to ensure.

[0060] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various modifications and changes can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A processing technology for an integrated structure of a heat exchanger and a pressure shell for a Stirling device, characterized in that: The integrated structure includes a pressure shell body. The upper part of the pressure shell body is a hollow heat exchange structure formed by multiple groups of columnar parts. The columnar parts are evenly distributed along the circumferential direction of the pressure shell body. Each group of columnar parts includes two inner and outer columnar monomers. A slender hole flow channel is arranged along the length direction inside the columnar monomer. One ends of the two slender hole flow channels of each group of columnar monomers are connected at the top inside the pressure shell body. The other end of the inner circumferential slender hole flow channel is connected to the expansion cavity formed by the lower part of the pressure shell body and the ejector. The other end of the outer circumferential slender hole flow channel is adjacent to the end face of the regenerator. It also includes an annular embedded part. The annular embedded part is arranged at the top inside the pressure shell body. The annular embedded part includes an annular base and a 180° elbow pipe. One side of the annular base is evenly provided with semi-circular grooves along the circumference for cooperating with the 180° elbow pipe. The 180° elbow pipe is clamped in the semi-circular groove. The two ends of the 180° elbow pipe are connected to the two slender hole flow channels inside the same group of columnar monomers. The specific processing steps are as follows: Step 1, perform turning-milling compound machining to prepare the annular base of the annular embedded part; Step 2, assemble the 180° elbow pipe and sequentially and evenly clamp the 180° elbow pipe in the semi-circular grooves of the annular embedded part; Step 3, assemble the annular embedded part in Step 2 with the pressure shell body casting mold. The middle hollow part and the slender hole flow channels are occupied by ceramic cores and are cast in one time to complete the processing of the integrated structure of the heat exchanger and the pressure shell.

2. The processing technology of the integrated structure of the heat exchanger and the pressure shell according to claim 1, characterized in that: The diameter of the slender hole flow channel is 2-4 mm.

3. The processing technology of the integrated structure of the heat exchanger and the pressure shell according to claim 1, characterized in that: The melting point of the annular embedded part is higher than that of the pressure shell body.

4. A processing technology for an integrated structure of a heat exchanger and a pressure shell for a Stirling device, characterized in that: The integrated structure includes a pressure shell body. The upper part of the pressure shell body is a hollow heat exchange structure formed by multiple groups of columnar parts. The columnar parts are evenly distributed along the circumferential direction of the pressure shell body. Each group of columnar parts includes two inner and outer columnar monomers. A slender hole flow channel is arranged along the length direction inside the columnar monomer. One ends of the two slender hole flow channels of each group of columnar monomers are connected at the top inside the pressure shell body. The other end of the inner circumferential slender hole flow channel is connected to the expansion cavity formed by the lower part of the pressure shell body and the ejector. The other end of the outer circumferential slender hole flow channel is adjacent to the end face of the regenerator. The pressure shell body includes a top cover and a pressure shell main body. The top cover is welded to the top of the pressure shell main body. The columnar parts are located on the pressure shell main body. On the side of the top cover facing the pressure shell main body, strip-shaped grooves are evenly arranged along the circumference. The holes formed by the strip-shaped grooves and the pressure shell main body are used to connect the two slender hole flow channels inside each group of columnar monomers. The specific processing steps are as follows: Step 1, perform turning machining to manufacture the outer shape of the pressure shell main body; Step 2, use a deep-hole machine tool to process the slender hole flow channels inside the columnar monomers; Step 3, perform milling machining to manufacture the columnar monomers. The specific milling steps are as follows: First step, cut downward along the diameter of the pressure shell main body to mill the gap between adjacent two groups of columnar parts and mill out a plate-shaped hollow part. Second step, parallel to the cross-section of the pressure shell main body, cut obliquely downward in sequence along the outer circumference of the pressure shell main body to penetrate adjacent two groups of plate-shaped hollow parts. Third step, cut symmetrically in sequence relative to the second step to form an irregular pentagon-shaped columnar monomer; Step 4, perform turning-milling compound machining to manufacture the top cover; Step 5: Weld the top cover and the main body of the pressure shell, and the processing of the integrated structure of the heat exchanger and the pressure shell is completed.

5. The processing technology of the integrated structure of the heat exchanger and the pressure shell according to claim 4, characterized in that: An annular reinforcing rib is provided in the middle of the columnar part parallel to the top cover.

6. The processing technology of the integrated structure of the heat exchanger and the pressure shell according to claim 4, characterized in that: The columnar monomer is an irregular pentagon.

7. The processing technology of the integrated structure of the heat exchanger and the pressure shell according to claim 4, characterized in that: In Step 3, the angle between the tool feed in the second and third milling operations and the tool feed in the first milling operation is 25° - 35°.

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