Segmented Microtube Heat Exchanger

Abstract

The present disclosure provides a heat exchanger comprising a plurality of monolithic shell and mid-plate segments, each segment comprising a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece. The heat exchanger includes a plurality of clearance holes extending through the mid-plate portion of each segment and a plurality of microtubes extending through the clearance holes of the segments. The heat exchanger further comprises two tubesheets, wherein the microtubes and segments are joined to the tubesheets at both ends of the heat exchanger. The monolithic construction of each segment eliminates gaps between the shell and mid-plate portions that can cause flow maldistribution in conventional heat exchanger designs. The segments are assembled by stacking and joining adjacent segments together, with the microtubes passing through aligned clearance holes to create continuous fluid passages through the assembled heat exchanger structure.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to (1) U.S. Provisional Application No. 63 / 729,034, filed Dec. 6, 2024, entitled “Segmented Microtube Recuperator” and (2) U.S. Provisional Application No. 63 / 853,098, filed Jul. 29, 2025, entitled “Segmented Microtube Heat Exchanger.”

[0002] The contents of each of the above referenced applications are hereby incorporated by reference in their entirety.TECHNICAL FIELD

[0003] Various aspects of the present disclosure relate generally to systems and methods for a heat exchanger and, more particularly, to systems and methods for a segmented microtube heat exchanger.BACKGROUND

[0004] Heat exchangers are widely used in various industrial applications to transfer thermal energy between two or more fluid streams. These devices play a fundamental role in many systems, including power generation, refrigeration, chemical processing, and aerospace applications. The efficiency of heat transfer in these systems directly impacts overall system performance, energy consumption, and operational costs.

[0005] Shell and tube heat exchangers represent one of the most common configurations used in industrial applications. In these devices, one fluid flows through tubes while another fluid flows around the tubes within a shell. The heat transfer occurs through the tube walls, allowing thermal energy to be exchanged between the two fluid streams. To enhance heat transfer performance and maintain proper flow distribution, many shell and tube heat exchangers incorporate internal structures such as baffles or mid-plates that direct fluid flow.

[0006] Microtube heat exchangers, which utilize very small diameter tubes, offer advantages in applications requiring high heat transfer effectiveness in compact configurations. These devices can achieve high surface area to volume ratios, making them suitable for applications where space and weight constraints are considerations. The small tube diameters and tight tube spacing in microtube designs create challenges in manufacturing and assembly processes.

[0007] Flow distribution uniformity represents a significant factor affecting heat exchanger performance. Non-uniform flow distribution around the microtubes can result in reduced heat transfer effectiveness, and decreased overall system efficiency. In shell and tube configurations, achieving uniform shell-side flow distribution can be challenging due to the incongruous flow paths entering and exiting the tube bundle.

[0008] Manufacturing tolerances and assembly processes can introduce variations that affect the final performance of heat exchangers. Unwanted gaps between components, misalignment of internal structures, and dimensional variations can create flow bypassing or maldistribution that reduces heat transfer effectiveness. These manufacturing challenges become more pronounced as performance requirements increase and as heat exchangers are scaled to larger sizes.

[0009] In high-performance applications, small reductions in heat exchanger effectiveness can have disproportionately large impacts on overall system performance. This sensitivity to performance variations places increased demands on manufacturing precision and assembly quality, which can result in higher costs and longer production schedules.

[0010] The present disclosure is directed to overcoming one or more of these above-referenced challenges.SUMMARY OF THE DISCLOSURE

[0011] According to certain aspects of the disclosure, systems and methods are disclosed for a segmented microtube heat exchanger.

[0012] In some cases, a heat exchanger may include: a plurality of monolithic shell and mid-plate segments, each segment comprising a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece; a plurality of clearance holes extending through the mid-plate portion of each segment; a plurality of microtubes extending through the clearance holes of the segments; and two tubesheets, wherein the microtubes and segments are joined to the tubesheets at both ends of the heat exchanger.

[0013] In some cases, a method of manufacturing a heat exchanger may include: forming a plurality of monolithic shell-and-mid-plate segments, wherein each segment comprises a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece; joining adjacent shell-and-mid-plate segments to form a shell assembly; inserting a plurality of microtubes through clearance holes in the mid-plate portions of the joined segments; and joining the microtubes and segments to tubesheets at both ends of the heat exchanger.

[0014] In some cases, a method of manufacturing a heat exchanger may include: forming a plurality of monolithic shell and mid-plate segments, wherein each segment comprises a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece, and the mid-plate portion of each segment has a plurality of clearance holes; obtaining a plurality of microtubes; assembling the heat exchanger by combining the shell-and-mid-plate segments and the plurality of microtubes; joining adjacent shell-and-mid-plate segments of the heat exchanger; and joining the microtubes and shell-and-mid-plate segments to tubesheets at both ends of the heat exchanger.

[0015] Additional objects and advantages of the disclosed technology will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practice of the disclosed technology.

[0016] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosed technology, as claimed.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary aspects and together with the description, serve to explain the principles of the disclosed technology.

[0018] FIG. 1 illustrates a cross-sectional view of a conventional heat exchanger, according to aspects of the present disclosure.

[0019] FIG. 2 illustrates a section view of a heat exchanger showing flow distribution challenges, according to aspects of the present disclosure.

[0020] FIG. 3 illustrates an exploded view of a heat exchanger with shell-mid-plate segments, according to aspects of the present disclosure.

[0021] FIG. 4 illustrates an isometric view and cutaway view of the heat exchanger of FIG. 3, according to aspects of the present disclosure.

[0022] FIG. 5 illustrates a flowchart for a method of manufacturing a heat exchanger, according to aspects of the present disclosure.

[0023] FIG. 6 illustrates a flowchart for an alternative method of manufacturing the heat exchanger, according to aspects of the present disclosure.DETAILED DESCRIPTION

[0024] The present disclosure relates to heat exchangers, particularly microtube recuperators used in high-performance applications where effectiveness levels of greater than 97% may be achieved. Such heat exchangers may be employed in Brayton refrigeration cycle applications and other systems requiring precise thermal management at cryogenic temperatures, including applications operating at temperatures as low as 4 Kelvin.

[0025] Conventional heat exchanger designs typically comprise separate shell and mid-plate components that are assembled together during manufacturing. In such conventional designs, gaps may form between the shell and mid-plates due to manufacturing tolerances, thermal expansion differences, and assembly variations. These gaps can lead to flow maldistribution on the shell side, where fluid bypasses the intended heat transfer surfaces and reduces overall heat exchanger effectiveness. In high-performance applications where shell-side flow may involve heat transfer levels of approximately 10 to 10,000 watts, even small reductions in effectiveness can have substantial impacts on system performance.

[0026] The heat exchanger disclosed herein addresses these limitations through the use of monolithic shell-mid-plate segments. Each segment comprises a shell portion and a mid-plate portion that are permanently joined or integrally formed as a single piece. This monolithic construction eliminates the gaps that may occur between separate shell and mid-plate components in conventional designs. By eliminating such gaps, the disclosed heat exchanger may achieve improved flow distribution on the shell side, leading to enhanced heat transfer performance and higher effectiveness levels.

[0027] The monolithic construction approach may provide manufacturing advantages as well. Rather than requiring precise tolerances between separate components and complex assembly procedures to minimize gaps, the disclosed design allows each segment to be manufactured as a single unit with inherent dimensional consistency. Multiple segments may then be joined together to form the complete heat exchanger assembly, with the monolithic nature of each segment ensuring proper flow distribution characteristics throughout the device.

[0028] Referring to FIG. 1, a heat exchanger 100 may comprise a shell 102, mid plates 104, a tube 106, tube sheets 108, and a tube array 110. The shell 102 may form an outer cylindrical housing that contains the internal components of the heat exchanger 100. The mid plates 104 may be positioned at regular intervals along the axial length of the shell 102 and may extend radially inward from an inner wall of the shell 102. In some aspects, the heat exchanger 100 may have an annular configuration instead of a tubular shape. The shell 102 may comprise concentric inner and outer cylindrical walls, creating an annular space between them. The mid plates 104 may extend radially between these inner and outer walls, forming ring-shaped structures that divide the annular space into multiple sections along the axial length of the heat exchanger 100.

[0029] The tube array 110 may be arranged in various geometric patterns within the annular space. In some cases, the tubes 106 may be positioned in concentric circular rows between the inner and outer walls of the shell 102. Alternatively, the tubes 106 may be arranged in a radial pattern, extending from the inner wall towards the outer wall of the shell 102.

[0030] Furthermore, the general arrangement of tubes and other components in the heat exchanger 100 may not be limited to cylindrical or annular configurations. In some implementations, the heat exchanger 100 may have a square or rectangular cross-section. The shell 102 may form a box-like structure, with the mid plates 104 extending horizontally and vertically within this enclosure. The tube array 110 may be arranged in a square or rectangular grid pattern within this configuration.

[0031] In other aspects, the heat exchanger 100 may utilize any three-dimensional array of tubes with corresponding configurations of walls and mid plates to shape fluid flow. For example, the heat exchanger 100 may have a triangular, hexagonal, or other polygonal cross-section. The shell 102 and mid plates 104 may be shaped to conform to these geometries, creating flow paths that direct shell-side fluid around the tubes in the chosen configuration.

[0032] The tube array 110 may be adapted to various three-dimensional arrangements beyond simple linear or planar configurations. In some implementations, the tubes 106 may be arranged in a staggered pattern across multiple layers to enhance turbulence and heat transfer. The mid plates 104 may have complex shapes or perforations designed to create specific flow patterns around the three-dimensional tube array.

[0033] These various geometric configurations may allow the heat exchanger 100 to be optimized for different space constraints, flow requirements, or heat transfer characteristics. The flexibility in design may enable the heat exchanger 100 to be adapted to a wide range of applications and installation environments while maintaining the benefits of the segmented construction approach described in the present disclosure.

[0034] The tube 106 may represent one of many tubes that pass through the mid plates 104 and may be arranged in the tube array 110 configuration. In some cases, the tube array 110 may comprise thousands of microtubes, such as approximately 10,000 tubes, with approximately 1,000 tubes positioned around a perimeter region of the tube array 110. The tube sheets 108 may be located at both ends of the heat exchanger 100 and may provide mounting points and sealing interfaces for the tubes in the tube array 110.

[0035] The heat exchanger 100 may facilitate heat transfer between two fluid streams through counterflow or parallel flow arrangements. Shell flow 112 may enter the shell side of the heat exchanger 100 and may flow around exterior surfaces of the tubes in the tube array 110. Tube flow 114 may pass through interior passages of the tubes in the tube array 110, typically in a direction opposite to the shell flow 112 to maximize heat transfer effectiveness.

[0036] The mid plates 104 may serve to direct the shell flow 112 and may maintain flow distribution around the tubes in the tube array 110. The tube sheets 108 may provide structural support for the tube array 110 and may create sealed connections between the tubes and the shell 102, thereby separating the shell flow 112 from the tube flow 114 at inlet and outlet regions of the heat exchanger 100. In some cases, the mid plates 104 may generate pressure drop for the shell flow 112 to improve flow uniformity across the tube array 110.

[0037] Referring to FIG. 2, a heat exchanger 200 may illustrate flow distribution challenges that may occur in conventional microtube recuperator designs. The heat exchanger 200 may comprise a shell wall 202 that may form an outer boundary of the device. Within the heat exchanger 200, a midplate shell gap 204 may be positioned between a midplate and the shell wall 202. Additionally, a midplate tube gap 206 may be located around tube openings in the midplate.

[0038] The heat exchanger 200 may demonstrate two types of fluid flow patterns. Tube flow 208 may represent fluid movement through internal tubes of the system, while shell flow 210 may indicate fluid movement through gaps and spaces around the tubes on a shell side of the heat exchanger 200.

[0039] The midplate shell gap 204 may create flow distribution problems by allowing a portion of the shell flow 210 to bypass intended heat transfer surfaces. When the midplate shell gap 204 has dimensions comparable to the midplate tube gap 206, flow maldistribution may occur around a perimeter of a tube core. In such cases, tubes positioned around the perimeter may receive reduced shell flow 210 compared to tubes located in interior regions of the tube array.

[0040] The flow maldistribution may result in reduced heat transfer effectiveness for perimeter tubes. In some cases, where a heat exchanger may contain approximately 10,000 tubes with approximately 1,000 tubes positioned around the perimeter, the loss of effective heat transfer from perimeter tubes may represent a substantial reduction in overall heat exchanger performance. For heat exchangers targeting effectiveness levels of 99% or higher, such flow distribution issues may cause effectiveness to drop below target levels.

[0041] The midplate shell gap 204 and midplate tube gap 206 may arise from manufacturing tolerances, assembly variations, and thermal expansion differences between components. In some cases, segments may be designed with clearances to accommodate thermal expansion and contraction during operation. However, these clearances may contribute to flow maldistribution when the shell flow 210 encounters paths of reduced resistance through the gaps rather than flowing uniformly around the tubes as intended.

[0042] The shell wall 202 may provide structural support for the assembly and containment of the shell flow while allowing for designated flow patterns of both the tube flow 208 and shell flow 210 through their respective pathways. However, the presence of the midplate shell gap 204 may compromise the intended flow distribution by creating bypass paths that reduce the effectiveness of heat transfer between the tube flow 208 and shell flow 210 streams.

[0043] Referring to FIG. 3, a heat exchanger 300 may comprise a plurality of shell-mid-plate segments 302 that may be designed to be stacked together to form a complete heat exchanger structure. Each shell-mid-plate segment 302 may comprise a shell portion and a mid-plate portion that may be permanently joined or integrally formed as a single piece of material, thereby eliminating gaps that may occur between separate shell and mid-plate components in conventional designs.

[0044] Each shell-mid-plate segment 302 may include a segment wall 308 that may form an outer cylindrical boundary of the segment. The segment wall 308 may extend axially and may provide structural support for the heat exchanger 300 and containment of the shell flow. The shell portion of each segment may comprise a cylindrical segment wall section that may have an inner diameter sized to accommodate a plurality of microtubes 306.

[0045] A mid plate 314 may be positioned within each segment and may extend radially inward from the segment wall 308. The mid plate portion of each segment may extend radially inward from the shell portion and may comprise a disc-shaped section extending radially inward from the shell portion. The mid plate 314 may create a disc-like structure that may span an interior of the segment.

[0046] Multiple holes 304 may be formed through each mid plate 314, with the mid-plate portion of each segment having a plurality of clearance holes. The holes 304 may be arranged in a predetermined pattern to align with holes 304 in adjacent segments when joined. The holes 304 may accommodate the microtubes 306 that may extend through a length of the assembled heat exchanger 300. The microtubes 306 may pass through the holes 304 in each segment, creating continuous fluid passages through a stacked assembly.

[0047] The shell-mid-plate segments 302 may include alignment features to facilitate proper positioning during assembly. Each shell-mid-plate segment 302 may comprise a stacking alignment feature configured to mate with a corresponding stacking alignment feature on an adjacent segment. An alignment ledge 310 may be formed on one axial face of each segment, while a corresponding alignment protrusion 312 may be formed on an opposite axial face. The stacking alignment feature may comprise one of an alignment ledge 310 or an alignment protrusion 312 on an axial face of the segment. The alignment ledge 310 and alignment protrusion 312 may work together to provide proper rotational indexing and axial positioning when adjacent segments may be joined together.

[0048] Each segment may comprise hole alignment features configured to align the holes 304 with corresponding holes 304 in adjacent segments. The alignment feature may comprise a marking, an alignment protrusion 312, or a recess on one axial face or side face of the segment and a corresponding marking, alignment protrusion 312, or recess on an opposite axial face or side face of an adjacent segment. In some cases, the alignment feature may comprise a keyed interface between adjacent segments. In some cases, the alignment feature may comprise at least one alignment pin extending from an axial face of the segment.

[0049] In some cases, the alignment feature may comprise a tapered edge on the shell portion of each segment configured to mate with a corresponding tapered surface on an adjacent segment. In some cases, the alignment feature may comprise interlocking geometric shapes formed on mating surfaces of adjacent segments. In some cases, the alignment feature may comprise a series of circumferentially spaced notches along an edge of the segment.

[0050] In some cases, the alignment feature may comprise optical or visual markers on each segment to guide proper orientation during assembly. In some cases, clocking features may be positioned on each segment for alignment, with clocking features on segments comprising tabs or protrusions for rotational alignment. The clocking features may serve a similar purpose to alignment features found on conventional mid plates.

[0051] The monolithic construction of each segment 302, where the segment wall 308 and mid plate 314 may be formed as a single piece, may eliminate gaps that may cause flow maldistribution in the assembled heat exchanger 300. The alignment features may provide proper hole alignment for the microtubes 306 when the shell-mid-plate segments 302 may be stacked in sequence. The rotational position of one segment relative to another segment may be controlled through the alignment features to maintain proper indexing, as the holes 304 may have fairly tight clearances and may require precise alignment for the microtubes 306 to pass through the entire length of the assembled heat exchanger 300.

[0052] Referring to FIG. 4, a heat exchanger 400 may comprise a first tube flow port 402 and a second tube flow port 404 positioned at opposite ends of the device. The heat exchanger 400 may also feature a first shell flow port 406 and a second shell flow port 408 for shell-side fluid flow. The first tube flow port 402 and second tube flow port 404 may provide inlet and outlet connections for tube-side fluid, while the first shell flow port 406 and second shell flow port 408 may provide inlet and outlet connections for shell-side fluid.

[0053] The heat exchanger 400 may comprise a plurality of joined segments 410 that may be joined together to form an overall structure. The plurality of joined segments 410 may appear as cylindrical sections that may be welded or otherwise connected in series along a longitudinal axis of the heat exchanger 400. The shell-mid-plate segments 302 may be joined to adjacent segments by welding to form the plurality of joined segments 410. In some cases, the welding may comprise laser welding.

[0054] In some aspects, the monolithic shell-mid-plate segments may be formed using various manufacturing techniques to achieve the desired integrated structure. For example, the segments may be manufactured using additive manufacturing processes such as selective laser sintering, direct metal laser sintering, or electron beam melting. These additive techniques may allow for complex internal geometries and precise control of material properties throughout the segment.

[0055] In some cases, the shell-mid-plate segments may be formed through investment casting processes. This approach may enable the creation of intricate internal features and thin-walled structures while maintaining the monolithic nature of each segment. The casting process may be optimized to minimize porosity and ensure uniform material properties throughout the segment.

[0056] Some implementations may utilize powder metallurgy techniques to form the monolithic segments. This method may involve compacting metal powders into the desired shape and then sintering the compacted powder to create a solid, integrated structure. Powder metallurgy may allow for precise control of material composition and may be suitable for producing segments with specific thermal or mechanical properties.

[0057] In certain aspects, the shell-mid-plate segments may be manufactured through a combination of forging and machining processes. Initial forging operations may create a near-net shape blank, which may then be precision machined to achieve the final geometry, including the formation of holes and alignment features.

[0058] The joining of adjacent shell-mid-plate segments may be accomplished through various methods depending on the specific requirements of the application. In some cases, fusion welding techniques such as electron beam welding, laser welding, or tungsten inert gas (TIG) welding may be employed. These welding methods may create high-strength joints with minimal distortion, preserving the alignment between segments.

[0059] Some implementations may utilize brazing techniques to join the segments. Brazing may allow for the creation of strong, leak-tight joints while minimizing thermal distortion of the segments. In certain cases, vacuum brazing may be employed to ensure high-quality joints free from oxidation or contamination.

[0060] In some aspects, mechanical joining methods may be used to connect adjacent segments. This may include the use of high-strength bolts or specialized fasteners designed to maintain proper alignment and sealing between segments. Mechanical joining may allow for easier disassembly and maintenance of the heat exchanger in some applications.

[0061] Some implementations may employ a combination of welding and mechanical fastening. For example, tack welds may be used to initially position and align the segments, followed by the installation of mechanical fasteners to provide the primary structural connection.

[0062] In certain cases, adhesive bonding may be used to join the shell-mid-plate segments. High-performance structural adhesives may provide strong, uniform bonds while accommodating slight variations in thermal expansion between components. Adhesive bonding may be particularly suitable for applications involving dissimilar materials or where minimal joint thickness is desired.

[0063] Some aspects may utilize diffusion bonding techniques to join the segments. This solid-state joining process may create high-strength connections with minimal microstructural changes at the joint interface. Diffusion bonding may be particularly advantageous for heat exchangers operating at elevated temperatures or in corrosive environments.

[0064] In some implementations, the joining method may incorporate sealing elements to ensure leak-tight connections between segments. This may include the use of specialized gaskets, O-rings, or metal seals designed to maintain proper sealing under the operating conditions of the heat exchanger.

[0065] The selection of joining method may depend on factors such as the operating temperature range, pressure requirements, fluid compatibility, and expected thermal cycling of the heat exchanger. In some cases, a combination of joining techniques may be employed to optimize the performance and reliability of the assembled heat exchanger structure.

[0066] A plurality of tubes 412 may extend through a length of the heat exchanger 400, passing through the plurality of joined segments 410. The plurality of tubes 412 may correspond to the microtubes 306 described in relation to FIG. 3, and may provide a pathway for tube-side fluid flow between the first tube flow port 402 and the second tube flow port 404. The plurality of tubes 412 may pass through the holes 304 in each of the shell-mid-plate segments 302 that form the plurality of joined segments 410.

[0067] The heat exchanger 400 may comprise two tube sheets, wherein the microtubes 306 and shell-mid-plate segments 302 may be joined to the tube sheets at both ends of the heat exchanger 400. The tube sheets may be positioned at locations corresponding to the first tube flow port 402 and second tube flow port 404, providing structural support and sealing interfaces for the plurality of tubes 412.

[0068] The heat exchanger 400 may further comprise a shell-side fluid flow path through spaces between the microtubes 306 and the holes 304. Shell-side fluid may flow through spaces around the plurality of tubes 412 within the plurality of joined segments 410, entering and exiting through the first shell flow port 406 and second shell flow port 408. The shell-side fluid flow path may be contained within the fused / joined structure formed by joining the shell-mid-plate segments 302 together.

[0069] In some cases, laser welding may be performed at an angle to avoid direct line of sight to the plurality of tubes 412 near the segment wall 308. The angled laser welding approach may prevent direct energy deposition on tubes positioned close to outer regions of the tube array, particularly those tubes located near the segment wall 308 of each shell-mid-plate segment 302. By angling the laser, line of sight between the laser and the plurality of tubes 412 may be eliminated, thereby protecting the tubes from potential damage during the welding process.

[0070] In some cases, weld joints may include protruding features or lips to provide adequate weld cross-section between adjacent shell-mid-plate segments 302. The protruding features may extend from mating surfaces of the segments and may provide additional material for the welding process. The weld joints with protruding features may allow for proper penetration and adequate weld cross-section at joined segments while maintaining clearance from the plurality of tubes 412 positioned within the segments.

[0071] The segmented construction approach demonstrated by the heat exchanger 400 may allow individual segments to be manufactured separately and then assembled to create a complete heat exchanger structure. The plurality of joined segments 410 may provide precise control of internal geometry and may eliminate gaps that might occur between mid plates 104 and shell walls in conventional designs. The monolithic nature of each shell-mid-plate segment 302 within the plurality of joined segments 410 may maintain proper flow distribution characteristics throughout the assembled heat exchanger 400.

[0072] Referring to FIG. 5, a method 500 of manufacturing the heat exchanger 300 may comprise a series of sequential steps that may provide a structured approach to assembling the segmented heat exchanger design. The method 500 may begin with a step 502, where the shell-mid-plate segments 302 may be manufactured. The step 502 may involve forming a plurality of monolithic shell-and-mid-plate segments 302, wherein each segment may comprise a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece.

[0073] The method 500 may then proceed to a step 504, where a plurality of the microtubes 306 may be obtained. The step 504 may involve acquiring the microtubes 306 that may be sized and configured to pass through the holes 304 in the shell-mid-plate segments 302. In some cases, the microtubes 306 may be obtained from suppliers or may be manufactured to specific dimensional requirements for the heat exchanger 300 application.

[0074] Following the step 504, the method 500 may move to a step 506, where the heat exchanger 300 may be assembled by combining the shell-and-mid-plate segments 302 and the plurality of the microtubes 306. The step 506 may involve an assembly process where the microtubes 306 may be inserted first through the holes 304 in the shell-mid-plate segments 302. In some cases, the assembly process may involve positioning the shell-mid-plate segments 302 in a spaced configuration and inserting the microtubes 306 through the aligned holes 304 of all segments simultaneously.

[0075] The method 500 may conclude with a step 508, where adjacent shell-mid-plate segments 302 of the heat exchanger 300 may be joined together. The step 508 may involve joining adjacent shell-and-mid-plate segments 302 of the heat exchanger 300 through welding processes. In some cases, the step 508 may involve sliding the shell-mid-plate segments 302 together so that the segments may be in close contact, segment by segment, before welding operations commence.

[0076] In some cases, the step 508 may involve tack welding that may be used to temporarily hold the shell-mid-plate segments 302 in place during assembly. The tack welding may provide temporary positioning before final welding operations may be performed to permanently join the adjacent shell-mid-plate segments 302.

[0077] The method 500 may involve tube sheet installation and welding operations as part of the assembly process. In some cases, one tube sheet may be welded first to provide structural support for the microtubes 306, after which the shell-mid-plate segments 302 may be slid together and welded to each other. A final tube sheet may then be positioned and welded to complete the assembly.

[0078] In some cases, the final tube sheet may be positioned and shimmed or trimmed to achieve uniform tube alignment to the tube sheet surface. The microtubes 306 may protrude or be recessed from the tube sheet by a controlled amount, such as four to six thousandths of an inch, to facilitate uniform welding conditions. The controlled alignment may provide consistent welding parameters across all the microtubes 306 and may reduce variability in the welding process.

[0079] In some aspects, the microtubes 306 may be joined to the tube sheets using various techniques. One approach may involve expanding the ends of the microtubes 306 to create a tight mechanical fit within the tube sheet holes. This expansion process may be performed using hydraulic or mechanical tube expanders, which may apply controlled pressure to the interior of the microtubes 306, causing them to expand and form a seal against the tube sheet material.

[0080] In some implementations, the microtubes 306 may be welded to the tube sheets. This welding process may involve techniques such as orbital welding, where a specialized welding head rotates around each microtube 306 to create a continuous, high-quality weld. Alternatively, automated welding systems may be employed to simultaneously weld multiple microtubes 306 to the tube sheet, improving efficiency and consistency in the joining process.

[0081] Some aspects may utilize brazing techniques to join the microtubes 306 to the tube sheets. In this approach, a brazing alloy may be applied between the microtubes 306 and the tube sheet holes. The assembly may then be heated in a controlled environment, causing the brazing alloy to melt and flow, creating a strong metallurgical bond upon cooling. Vacuum brazing may be employed in some cases to ensure high-quality, oxide-free joints.

[0082] Some implementations may incorporate seal welding techniques to join the microtubes 306 to the tube sheets. This method may involve creating a small fillet weld around the circumference of each microtube 306 where it meets the tube sheet surface. Seal welding may provide both a structural connection and a leak-tight seal, which may be particularly important in high-pressure or corrosive environments.

[0083] In certain aspects, the joining process may include post-weld heat treatment to relieve residual stresses and optimize the metallurgical properties of the welded joints. This heat treatment process may be carefully controlled to maintain the dimensional stability of the assembly while enhancing the long-term reliability of the tube-to-tubesheet connections.

[0084] The method 500 may provide manufacturing advantages through the sequential approach to component fabrication and assembly. The monolithic construction of each shell-mid-plate segment 302 may eliminate the need for precise tolerances between separate shell and mid-plate components, while the sequential assembly process may allow for quality control at each stage of manufacturing.

[0085] Referring to FIG. 6, a method 600 of manufacturing a heat exchanger may comprise a series of sequential steps that may provide an alternative approach to the manufacturing process described in relation to the method 500. The method 600 may begin with a step 602, which may involve manufacturing the shell-mid-plate segments 302. The step 602 may involve forming a plurality of monolithic shell and mid-plate segments, wherein each segment may comprise a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece, and the mid-plate portion of each segment may have a plurality of the holes 304.

[0086] The method 600 may then proceed to a step 604, where a plurality of the microtubes 306 may be obtained. The step 604 may involve acquiring the microtubes 306 that may be sized and configured to pass through the holes 304 in the shell-mid-plate segments 302. In some cases, the microtubes 306 may be obtained from suppliers or may be manufactured to specific dimensional requirements for the heat exchanger application.

[0087] Following the step 604, the method 600 may move to a step 606, which may involve assembling and joining adjacent shell-mid-plate segments 302 together. The step 606 may represent a different sequence compared to the method 500, where the shell-mid-plate segments 302 may be joined to adjacent segments to form a shell assembly before the microtubes 306 may be inserted. In some cases, the step 606 may involve stacking the shell-mid-plate segments 302 in sequence and welding the segments together to create the plurality of joined segments 410.

[0088] The method 600 may conclude with a step 608, where the heat exchanger may be assembled by combining the fused / joined shell-mid-plate segments 302 and the plurality of the microtubes 306. The step 608 may involve inserting the plurality of the microtubes 306 through the holes 304 in the mid-plate portions of the joined segments after the shell assembly may be completed. In some cases, the step 608 may involve threading the microtubes 306 through the aligned holes 304 of the pre-assembled shell structure formed by the joined shell-mid-plate segments 302.

[0089] The method 600 may provide manufacturing flexibility by allowing the shell assembly to be completed and inspected before the microtubes 306 may be installed. In some cases, the pre-assembled shell structure may be tested for dimensional accuracy and alignment of the holes 304 before the microtubes 306 may be inserted. The method 600 may allow for quality control of the shell assembly independently from the microtube installation process.

[0090] In some cases, the method 600 may involve joining the microtubes 306 and the shell-mid-plate segments 302 to tubesheets at both ends of the heat exchanger after the step 608 may be completed. The tubesheets may be positioned and welded to the microtubes 306 and the shell-mid-plate segments 302 to provide structural support and sealing interfaces for the completed heat exchanger assembly.

[0091] The alternative sequence provided by the method 600 may accommodate different manufacturing constraints or equipment configurations compared to the method 500. In some cases, the method 600 may be selected when welding operations on the shell-mid-plate segments 302 may be performed more efficiently before the microtubes 306 may be installed, or when inspection of the shell assembly may be required before microtube installation may proceed.

[0092] The heat exchanger 300 may operate through functional integration of the shell-mid-plate segments 302 to eliminate flow maldistribution and achieve improved heat transfer effectiveness compared to conventional designs. The monolithic construction of each shell-mid-plate segment 302 may address flow distribution problems that may occur in conventional heat exchangers where separate shell and mid-plate components may create gaps.

[0093] In conventional designs such as the heat exchanger 200 shown in FIG. 2, the midplate shell gap 204 may allow the shell flow 210 to bypass intended heat transfer surfaces around the microtubes. The midplate shell gap 204 may create a path of reduced flow resistance that may divert the shell flow 210 away from the tube surfaces where heat transfer may occur. When the midplate shell gap 204 has dimensions comparable to the midplate tube gap 206, flow maldistribution may become pronounced, particularly affecting heat exchanged in tubes positioned around a perimeter of the tube array.

[0094] The heat exchanger 300 may eliminate such flow maldistribution through the monolithic construction of the shell-mid-plate segments 302. Each shell-mid-plate segment 302 may comprise a shell portion and a mid-plate portion that may be permanently joined or integrally formed as a single piece, thereby eliminating the midplate shell gap 204 that may occur between separate components. The segment wall 308 and the mid plate 314 may be formed as a continuous structure without gaps that may allow bypass flow.

[0095] The shell-mid-plate segments 302 may be manufactured using various techniques to achieve the monolithic construction. In some cases, the shell-mid-plate segments 302 may be manufactured by machining from solid pieces of material. The machining process may involve removing material from a solid block to create the segment wall 308, the mid plate 314, and the holes 304 in a single manufacturing operation. In some cases, the shell-mid-plate segments 302 may be manufactured by casting, where molten material may be poured into a mold that may define the shape of the segment wall 308, the mid plate 314, and the holes 304.

[0096] In some cases, each segment may be manufactured using at least machining, casting, or additive manufacturing techniques. The shell-mid-plate segments 302 may be manufactured by additive manufacturing, where material may be deposited layer by layer to build up the segment wall 308, the mid plate 314, and the holes 304 according to a digital model. The additive manufacturing process may allow for complex internal geometries and may provide design flexibility for optimizing flow characteristics.

[0097] In some aspects, the heat exchanger may be constructed using a hybrid approach where the shell segment and mid-plate segment are manufactured separately and then joined together. This method may offer certain advantages in terms of manufacturing flexibility and material selection.

[0098] The shell segment may be formed using techniques such as rolling and welding of sheet metal, extrusion, or centrifugal casting. These methods may allow for the creation of a cylindrical shell with precise dimensional control and surface finish. The shell segment may be manufactured from materials selected for their structural properties, corrosion resistance, or thermal characteristics.

[0099] Separately, the mid-plate segment may be fabricated using processes such as stamping, laser cutting, or water jet cutting. These techniques may enable the creation of complex hole patterns and flow distribution features in the mid-plate. The mid-plate segment may be made from materials chosen for their heat transfer properties or compatibility with the working fluids.

[0100] Once the shell segment and mid-plate segment are manufactured, they may be joined together using various methods. Welding may be employed to create a permanent bond between the segments. In some cases, electron beam welding or laser welding may be used to minimize heat input and distortion. Alternatively, brazing techniques may be utilized to join the segments, particularly when dissimilar materials are involved.

[0101] In some implementations, mechanical joining methods may be used to connect the shell and mid-plate segments. This may involve the use of flanges, bolts, or specialized fasteners designed to maintain proper alignment and sealing between the segments. Mechanical joining may allow for easier disassembly and maintenance of the heat exchanger in certain applications.

[0102] The joining process may incorporate alignment features to ensure proper positioning of the mid-plate within the shell. These features may include tabs, slots, or pins that correspond between the shell and mid-plate segments. In some cases, optical alignment systems or precision fixtures may be used during the joining operation to achieve the required tolerances.

[0103] After joining, the assembly may undergo inspection and testing to verify the integrity of the connection and ensure that no gaps or misalignments exist between the shell and mid-plate segments. Non-destructive testing methods such as ultrasonic inspection or helium leak testing may be employed to validate the quality of the joined assembly.

[0104] This hybrid approach of manufacturing separate shell and mid-plate segments before joining may provide benefits in terms of material optimization, manufacturing efficiency, and quality control. It may allow for the use of different materials or manufacturing processes for each component, tailored to their specific requirements. Additionally, this method may facilitate easier inspection and validation of individual components prior to final assembly.

[0105] The shell-mid-plate segments 302 may be made of a material selected from the group consisting of stainless steel, aluminum alloys, titanium alloys, and high-temperature resistant alloys. The material selection may depend on operating temperature requirements, corrosion resistance needs, and thermal expansion characteristics of the application. In some cases, stainless steel may be selected for cryogenic applications due to its low thermal conductivity and compatibility with welding processes.

[0106] The heat exchanger 400 may demonstrate the functional integration of multiple shell-mid-plate segments 302 joined together to form the plurality of joined segments 410. The shell flow may enter through the first shell flow port 406 and may flow through spaces around the plurality of tubes 412 within the plurality of joined segments 410. The monolithic construction of each segment within the plurality of joined segments 410 may maintain uniform flow distribution as the shell flow moves through the heat exchanger 400.

[0107] The tube flow may enter through the first tube flow port 402 and may pass through the plurality of tubes 412, exiting through the second tube flow port 404. Heat transfer may occur between the shell flow and the tube flow as the fluids move through the heat exchanger 400. The elimination of gaps between shell and mid-plate components may allow the shell flow to more effectively exchange heat with the plurality of tubes 412 throughout the length of the heat exchanger 400.

[0108] The alignment ledge 310 and the alignment protrusion 312 may provide proper positioning of adjacent shell-mid-plate segments 302 during assembly. The alignment features may maintain rotational indexing between segments to provide that the holes 304 in adjacent segments may align properly for the microtubes 306 to pass through the assembled structure. The proper alignment may maintain flow distribution characteristics by preventing misalignment that may create flow restrictions or bypass paths.

[0109] The functional integration of the shell-mid-plate segments 302 may provide improved effectiveness levels compared to conventional designs. By eliminating bypass flow through gaps, the shell flow may be directed uniformly around the microtubes 306, maximizing heat transfer between the shell flow and the tube flow. The monolithic construction may maintain flow distribution characteristics that may be designed into each segment, providing consistent performance throughout the assembled heat exchanger.Terminology

[0110] The terminology used above may be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific examples of the present disclosure. Indeed, certain terms may even be emphasized above; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section. Both the foregoing general description and the detailed description are exemplary and explanatory only and are not restrictive of the features, as claimed.

[0111] As used herein, the terms “comprises,”“comprising,”“having,” including,” or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, article, or apparatus.

[0112] In this disclosure, relative terms, such as, for example, “about,”“substantially,”“generally,” and “approximately” are used to indicate a possible variation of ±10% in a stated value.

[0113] As used herein, the terms “transmit,”“provide,”“receive,” and “obtain” may refer to the transfer or communication of data, information, or signals between various components or entities. This may include, but is not limited to, transmission over a network (such as a local area network, wide area network, or the Internet), transfer between devices (such as between computers, smartphones, or other electronic devices), communication between central processing units (CPUs) or graphics processing units (GPUs), exchange of information between microservices, transfer of data between software components within an environment, or any other form of data transfer or communication as indicated by the context in which the terms are used. The specific mode or medium of transmission or provision may vary depending on the particular implementation and system architecture.

[0114] As used herein, the term “module” may refer to software code, a software component, a software function, a software application, and firmware. As indicated by context, “module” may be logical, digital, analog, optical, electronic, or quantum implementations of operations or functions. A module may be implemented as a standalone unit or as part of a larger system. In some cases, a module may interact with other modules or components to perform specific tasks or operations within the system. As indicated by context or based on design preference, any two modules may be combined. As indicated by context or based on design preference, any module may be broken into two or more modules that provide some or all of the operations or functions of the single module. The specific implementation of module(s) may vary depending on the requirements of the system and the particular application.

[0115] The term “exemplary” is used in the sense of “example” rather than “ideal.” As used herein, the singular forms “a,”“an,” and “the” include plural reference unless the context dictates otherwise.EXAMPLES

[0116] Exemplary embodiments of the systems and methods disclosed herein are described in the numbered paragraphs below.

[0117] A1. A heat exchanger, comprising: a plurality of monolithic shell and mid-plate segments, each segment comprising a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece; a plurality of clearance holes extending through the mid-plate portion of each segment; a plurality of microtubes extending through the clearance holes of the segments; and two tubesheets, wherein the microtubes and segments are joined to the tubesheets at both ends of the heat exchanger.

[0118] A2. The heat exchanger of A1, wherein the segments are joined to adjacent segments by joining.

[0119] A3. The heat exchanger of A2, wherein the joining comprises laser welding.

[0120] A4. The heat exchanger of any of A1-A3, wherein the clearance holes in each segment are arranged in a predetermined pattern to align with clearance holes in adjacent segments when joined.

[0121] A5. The heat exchanger of any of A1-A4, wherein the shell portion of each segment has an inner diameter sized to accommodate the plurality of microtubes.

[0122] A6. The heat exchanger of any of A1-A5, wherein the mid-plate portion of each segment: in a case of a circular configuration, extends radially inward from the shell portion; in a case of an annular configuration, extends radially between the shell portion and an interior wall of the annular configuration; and, in a case of a non-circular configuration or non-annular configuration, extends from the shell portion towards an interior.

[0123] A7. The heat exchanger of any of A1-A6, further comprising a shell-side fluid flow path through spaces between the microtubes and clearance holes.

[0124] A8. The heat exchanger of any of A1-A7, wherein each shell and mid-plate segment comprises a stacking alignment feature configured to mate with a corresponding stacking alignment feature on an adjacent segment.

[0125] A9. The heat exchanger of A8, wherein the stacking alignment feature comprises one of a ledge or a protrusion on an axial face of the segment.

[0126] A10. The heat exchanger of any of A1-A9, wherein the shell portion and mid-plate portion of each segment are formed from a single piece of material.

[0127] A11. The heat exchanger of any of A1-A10, wherein the shell portion of each segment comprises a cylindrical wall section.

[0128] A12. The heat exchanger of any of A1-A11, wherein the mid-plate portion of each segment comprises a disc-shaped section extending radially inward from the shell portion.

[0129] A13. The heat exchanger of any of A1-A12, wherein each segment is manufactured using at least machining, casting, or additive manufacturing techniques.

[0130] A14. The heat exchanger of any of A1-A13, wherein the segments are made of a material selected from the group consisting of stainless steel, aluminum alloys, titanium alloys, and high-temperature resistant alloys.

[0131] A15. The heat exchanger of any of A1-A14, wherein each segment comprises hole alignment features configured to align the clearance holes with corresponding clearance holes in adjacent segments.

[0132] A16. The heat exchanger of A15, wherein the alignment feature comprises a marking, a protrusion, or a recess on one axial face or side face of the segment and a corresponding marking, protrusion, or recess on an opposite axial face or side face of an adjacent segment.

[0133] A17. The heat exchanger of A15, wherein the alignment feature comprises a keyed interface between adjacent segments.

[0134] A18. The heat exchanger of A15, wherein the alignment feature comprises at least one alignment pin extending from an axial face of the segment.

[0135] A19. The heat exchanger of A15, wherein the alignment feature comprises a series of circumferentially spaced notches along an edge of the segment.

[0136] A20. The heat exchanger of A15, wherein the alignment feature comprises optical or visual markers on each segment to guide proper orientation during assembly.

[0137] A21. The heat exchanger of A15, wherein the alignment feature comprises a tapered edge on the shell portion of each segment configured to mate with a corresponding tapered surface on an adjacent segment.

[0138] A22. The heat exchanger of A15, wherein the alignment feature comprises interlocking geometric shapes formed on mating surfaces of adjacent segments.

[0139] B1. A method of manufacturing a heat exchanger, comprising: forming a plurality of monolithic shell-and-mid-plate segments, wherein each segment comprises a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece; joining adjacent shell-and-mid-plate segments to form a shell assembly; inserting a plurality of microtubes through clearance holes in the mid-plate portions of the joined segments; and joining the microtubes and segments to tubesheets at both ends of the heat exchanger.

[0140] C1. A method of manufacturing a heat exchanger, comprising: forming a plurality of monolithic shell and mid-plate segments, wherein each segment comprises a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece, and the mid-plate portion of each segment has a plurality of clearance holes; obtaining a plurality of microtubes; assembling the heat exchanger by combining the shell-and-mid-plate segments and the plurality of microtubes; joining adjacent shell-and-mid-plate segments of the heat exchanger; and joining the microtubes and shell-and-mid-plate segments to tubesheets at both ends of the heat exchanger.

[0141] Other aspects of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Examples

examples

[0116]Exemplary embodiments of the systems and methods disclosed herein are described in the numbered paragraphs below.

[0117]A1. A heat exchanger, comprising: a plurality of monolithic shell and mid-plate segments, each segment comprising a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece; a plurality of clearance holes extending through the mid-plate portion of each segment; a plurality of microtubes extending through the clearance holes of the segments; and two tubesheets, wherein the microtubes and segments are joined to the tubesheets at both ends of the heat exchanger.

[0118]A2. The heat exchanger of A1, wherein the segments are joined to adjacent segments by joining.

[0119]A3. The heat exchanger of A2, wherein the joining comprises laser welding.

[0120]A4. The heat exchanger of any of A1-A3, wherein the clearance holes in each segment are arranged in a predetermined pattern to align with clearance holes in adjacent segments when join...

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to (1) U.S. Provisional Application No. 63 / 729,034, filed Dec. 6, 2024, entitled “Segmented Microtube Recuperator” and (2) U.S. Provisional Application No. 63 / 853,098, filed Jul. 29, 2025, entitled “Segmented Microtube Heat Exchanger.”

[0002] The contents of each of the above referenced applications are hereby incorporated by reference in their entirety.TECHNICAL FIELD

[0003] Various aspects of the present disclosure relate generally to systems and methods for a heat exchanger and, more particularly, to systems and methods for a segmented microtube heat exchanger.BACKGROUND

[0004] Heat exchangers are widely used in various industrial applications to transfer thermal energy between two or more fluid streams. These devices play a fundamental role in many systems, including power generation, refrigeration, chemical processing, and aerospace applications. The efficiency of heat transfer in these systems directly impacts overall system performance, energy consumption, and operational costs.

[0005] Shell and tube heat exchangers represent one of the most common configurations used in industrial applications. In these devices, one fluid flows through tubes while another fluid flows around the tubes within a shell. The heat transfer occurs through the tube walls, allowing thermal energy to be exchanged between the two fluid streams. To enhance heat transfer performance and maintain proper flow distribution, many shell and tube heat exchangers incorporate internal structures such as baffles or mid-plates that direct fluid flow.

[0006] Microtube heat exchangers, which utilize very small diameter tubes, offer advantages in applications requiring high heat transfer effectiveness in compact configurations. These devices can achieve high surface area to volume ratios, making them suitable for applications where space and weight constraints are considerations. The small tube diameters and tight tube spacing in microtube designs create challenges in manufacturing and assembly processes.

[0007] Flow distribution uniformity represents a significant factor affecting heat exchanger performance. Non-uniform flow distribution around the microtubes can result in reduced heat transfer effectiveness, and decreased overall system efficiency. In shell and tube configurations, achieving uniform shell-side flow distribution can be challenging due to the incongruous flow paths entering and exiting the tube bundle.

[0008] Manufacturing tolerances and assembly processes can introduce variations that affect the final performance of heat exchangers. Unwanted gaps between components, misalignment of internal structures, and dimensional variations can create flow bypassing or maldistribution that reduces heat transfer effectiveness. These manufacturing challenges become more pronounced as performance requirements increase and as heat exchangers are scaled to larger sizes.

[0009] In high-performance applications, small reductions in heat exchanger effectiveness can have disproportionately large impacts on overall system performance. This sensitivity to performance variations places increased demands on manufacturing precision and assembly quality, which can result in higher costs and longer production schedules.

[0010] The present disclosure is directed to overcoming one or more of these above-referenced challenges.SUMMARY OF THE DISCLOSURE

[0011] According to certain aspects of the disclosure, systems and methods are disclosed for a segmented microtube heat exchanger.

[0012] In some cases, a heat exchanger may include: a plurality of monolithic shell and mid-plate segments, each segment comprising a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece; a plurality of clearance holes extending through the mid-plate portion of each segment; a plurality of microtubes extending through the clearance holes of the segments; and two tubesheets, wherein the microtubes and segments are joined to the tubesheets at both ends of the heat exchanger.

[0013] In some cases, a method of manufacturing a heat exchanger may include: forming a plurality of monolithic shell-and-mid-plate segments, wherein each segment comprises a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece; joining adjacent shell-and-mid-plate segments to form a shell assembly; inserting a plurality of microtubes through clearance holes in the mid-plate portions of the joined segments; and joining the microtubes and segments to tubesheets at both ends of the heat exchanger.

[0014] In some cases, a method of manufacturing a heat exchanger may include: forming a plurality of monolithic shell and mid-plate segments, wherein each segment comprises a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece, and the mid-plate portion of each segment has a plurality of clearance holes; obtaining a plurality of microtubes; assembling the heat exchanger by combining the shell-and-mid-plate segments and the plurality of microtubes; joining adjacent shell-and-mid-plate segments of the heat exchanger; and joining the microtubes and shell-and-mid-plate segments to tubesheets at both ends of the heat exchanger.

[0015] Additional objects and advantages of the disclosed technology will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practice of the disclosed technology.

[0016] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosed technology, as claimed.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary aspects and together with the description, serve to explain the principles of the disclosed technology.

[0018] FIG. 1 illustrates a cross-sectional view of a conventional heat exchanger, according to aspects of the present disclosure.

[0019] FIG. 2 illustrates a section view of a heat exchanger showing flow distribution challenges, according to aspects of the present disclosure.

[0020] FIG. 3 illustrates an exploded view of a heat exchanger with shell-mid-plate segments, according to aspects of the present disclosure.

[0021] FIG. 4 illustrates an isometric view and cutaway view of the heat exchanger of FIG. 3, according to aspects of the present disclosure.

[0022] FIG. 5 illustrates a flowchart for a method of manufacturing a heat exchanger, according to aspects of the present disclosure.

[0023] FIG. 6 illustrates a flowchart for an alternative method of manufacturing the heat exchanger, according to aspects of the present disclosure.DETAILED DESCRIPTION

[0024] The present disclosure relates to heat exchangers, particularly microtube recuperators used in high-performance applications where effectiveness levels of greater than 97% may be achieved. Such heat exchangers may be employed in Brayton refrigeration cycle applications and other systems requiring precise thermal management at cryogenic temperatures, including applications operating at temperatures as low as 4 Kelvin.

[0025] Conventional heat exchanger designs typically comprise separate shell and mid-plate components that are assembled together during manufacturing. In such conventional designs, gaps may form between the shell and mid-plates due to manufacturing tolerances, thermal expansion differences, and assembly variations. These gaps can lead to flow maldistribution on the shell side, where fluid bypasses the intended heat transfer surfaces and reduces overall heat exchanger effectiveness. In high-performance applications where shell-side flow may involve heat transfer levels of approximately 10 to 10,000 watts, even small reductions in effectiveness can have substantial impacts on system performance.

[0026] The heat exchanger disclosed herein addresses these limitations through the use of monolithic shell-mid-plate segments. Each segment comprises a shell portion and a mid-plate portion that are permanently joined or integrally formed as a single piece. This monolithic construction eliminates the gaps that may occur between separate shell and mid-plate components in conventional designs. By eliminating such gaps, the disclosed heat exchanger may achieve improved flow distribution on the shell side, leading to enhanced heat transfer performance and higher effectiveness levels.

[0027] The monolithic construction approach may provide manufacturing advantages as well. Rather than requiring precise tolerances between separate components and complex assembly procedures to minimize gaps, the disclosed design allows each segment to be manufactured as a single unit with inherent dimensional consistency. Multiple segments may then be joined together to form the complete heat exchanger assembly, with the monolithic nature of each segment ensuring proper flow distribution characteristics throughout the device.

[0028] Referring to FIG. 1, a heat exchanger 100 may comprise a shell 102, mid plates 104, a tube 106, tube sheets 108, and a tube array 110. The shell 102 may form an outer cylindrical housing that contains the internal components of the heat exchanger 100. The mid plates 104 may be positioned at regular intervals along the axial length of the shell 102 and may extend radially inward from an inner wall of the shell 102. In some aspects, the heat exchanger 100 may have an annular configuration instead of a tubular shape. The shell 102 may comprise concentric inner and outer cylindrical walls, creating an annular space between them. The mid plates 104 may extend radially between these inner and outer walls, forming ring-shaped structures that divide the annular space into multiple sections along the axial length of the heat exchanger 100.

[0029] The tube array 110 may be arranged in various geometric patterns within the annular space. In some cases, the tubes 106 may be positioned in concentric circular rows between the inner and outer walls of the shell 102. Alternatively, the tubes 106 may be arranged in a radial pattern, extending from the inner wall towards the outer wall of the shell 102.

[0030] Furthermore, the general arrangement of tubes and other components in the heat exchanger 100 may not be limited to cylindrical or annular configurations. In some implementations, the heat exchanger 100 may have a square or rectangular cross-section. The shell 102 may form a box-like structure, with the mid plates 104 extending horizontally and vertically within this enclosure. The tube array 110 may be arranged in a square or rectangular grid pattern within this configuration.

[0031] In other aspects, the heat exchanger 100 may utilize any three-dimensional array of tubes with corresponding configurations of walls and mid plates to shape fluid flow. For example, the heat exchanger 100 may have a triangular, hexagonal, or other polygonal cross-section. The shell 102 and mid plates 104 may be shaped to conform to these geometries, creating flow paths that direct shell-side fluid around the tubes in the chosen configuration.

[0032] The tube array 110 may be adapted to various three-dimensional arrangements beyond simple linear or planar configurations. In some implementations, the tubes 106 may be arranged in a staggered pattern across multiple layers to enhance turbulence and heat transfer. The mid plates 104 may have complex shapes or perforations designed to create specific flow patterns around the three-dimensional tube array.

[0033] These various geometric configurations may allow the heat exchanger 100 to be optimized for different space constraints, flow requirements, or heat transfer characteristics. The flexibility in design may enable the heat exchanger 100 to be adapted to a wide range of applications and installation environments while maintaining the benefits of the segmented construction approach described in the present disclosure.

[0034] The tube 106 may represent one of many tubes that pass through the mid plates 104 and may be arranged in the tube array 110 configuration. In some cases, the tube array 110 may comprise thousands of microtubes, such as approximately 10,000 tubes, with approximately 1,000 tubes positioned around a perimeter region of the tube array 110. The tube sheets 108 may be located at both ends of the heat exchanger 100 and may provide mounting points and sealing interfaces for the tubes in the tube array 110.

[0035] The heat exchanger 100 may facilitate heat transfer between two fluid streams through counterflow or parallel flow arrangements. Shell flow 112 may enter the shell side of the heat exchanger 100 and may flow around exterior surfaces of the tubes in the tube array 110. Tube flow 114 may pass through interior passages of the tubes in the tube array 110, typically in a direction opposite to the shell flow 112 to maximize heat transfer effectiveness.

[0036] The mid plates 104 may serve to direct the shell flow 112 and may maintain flow distribution around the tubes in the tube array 110. The tube sheets 108 may provide structural support for the tube array 110 and may create sealed connections between the tubes and the shell 102, thereby separating the shell flow 112 from the tube flow 114 at inlet and outlet regions of the heat exchanger 100. In some cases, the mid plates 104 may generate pressure drop for the shell flow 112 to improve flow uniformity across the tube array 110.

[0037] Referring to FIG. 2, a heat exchanger 200 may illustrate flow distribution challenges that may occur in conventional microtube recuperator designs. The heat exchanger 200 may comprise a shell wall 202 that may form an outer boundary of the device. Within the heat exchanger 200, a midplate shell gap 204 may be positioned between a midplate and the shell wall 202. Additionally, a midplate tube gap 206 may be located around tube openings in the midplate.

[0038] The heat exchanger 200 may demonstrate two types of fluid flow patterns. Tube flow 208 may represent fluid movement through internal tubes of the system, while shell flow 210 may indicate fluid movement through gaps and spaces around the tubes on a shell side of the heat exchanger 200.

[0039] The midplate shell gap 204 may create flow distribution problems by allowing a portion of the shell flow 210 to bypass intended heat transfer surfaces. When the midplate shell gap 204 has dimensions comparable to the midplate tube gap 206, flow maldistribution may occur around a perimeter of a tube core. In such cases, tubes positioned around the perimeter may receive reduced shell flow 210 compared to tubes located in interior regions of the tube array.

[0040] The flow maldistribution may result in reduced heat transfer effectiveness for perimeter tubes. In some cases, where a heat exchanger may contain approximately 10,000 tubes with approximately 1,000 tubes positioned around the perimeter, the loss of effective heat transfer from perimeter tubes may represent a substantial reduction in overall heat exchanger performance. For heat exchangers targeting effectiveness levels of 99% or higher, such flow distribution issues may cause effectiveness to drop below target levels.

[0041] The midplate shell gap 204 and midplate tube gap 206 may arise from manufacturing tolerances, assembly variations, and thermal expansion differences between components. In some cases, segments may be designed with clearances to accommodate thermal expansion and contraction during operation. However, these clearances may contribute to flow maldistribution when the shell flow 210 encounters paths of reduced resistance through the gaps rather than flowing uniformly around the tubes as intended.

[0042] The shell wall 202 may provide structural support for the assembly and containment of the shell flow while allowing for designated flow patterns of both the tube flow 208 and shell flow 210 through their respective pathways. However, the presence of the midplate shell gap 204 may compromise the intended flow distribution by creating bypass paths that reduce the effectiveness of heat transfer between the tube flow 208 and shell flow 210 streams.

[0043] Referring to FIG. 3, a heat exchanger 300 may comprise a plurality of shell-mid-plate segments 302 that may be designed to be stacked together to form a complete heat exchanger structure. Each shell-mid-plate segment 302 may comprise a shell portion and a mid-plate portion that may be permanently joined or integrally formed as a single piece of material, thereby eliminating gaps that may occur between separate shell and mid-plate components in conventional designs.

[0044] Each shell-mid-plate segment 302 may include a segment wall 308 that may form an outer cylindrical boundary of the segment. The segment wall 308 may extend axially and may provide structural support for the heat exchanger 300 and containment of the shell flow. The shell portion of each segment may comprise a cylindrical segment wall section that may have an inner diameter sized to accommodate a plurality of microtubes 306.

[0045] A mid plate 314 may be positioned within each segment and may extend radially inward from the segment wall 308. The mid plate portion of each segment may extend radially inward from the shell portion and may comprise a disc-shaped section extending radially inward from the shell portion. The mid plate 314 may create a disc-like structure that may span an interior of the segment.

[0046] Multiple holes 304 may be formed through each mid plate 314, with the mid-plate portion of each segment having a plurality of clearance holes. The holes 304 may be arranged in a predetermined pattern to align with holes 304 in adjacent segments when joined. The holes 304 may accommodate the microtubes 306 that may extend through a length of the assembled heat exchanger 300. The microtubes 306 may pass through the holes 304 in each segment, creating continuous fluid passages through a stacked assembly.

[0047] The shell-mid-plate segments 302 may include alignment features to facilitate proper positioning during assembly. Each shell-mid-plate segment 302 may comprise a stacking alignment feature configured to mate with a corresponding stacking alignment feature on an adjacent segment. An alignment ledge 310 may be formed on one axial face of each segment, while a corresponding alignment protrusion 312 may be formed on an opposite axial face. The stacking alignment feature may comprise one of an alignment ledge 310 or an alignment protrusion 312 on an axial face of the segment. The alignment ledge 310 and alignment protrusion 312 may work together to provide proper rotational indexing and axial positioning when adjacent segments may be joined together.

[0048] Each segment may comprise hole alignment features configured to align the holes 304 with corresponding holes 304 in adjacent segments. The alignment feature may comprise a marking, an alignment protrusion 312, or a recess on one axial face or side face of the segment and a corresponding marking, alignment protrusion 312, or recess on an opposite axial face or side face of an adjacent segment. In some cases, the alignment feature may comprise a keyed interface between adjacent segments. In some cases, the alignment feature may comprise at least one alignment pin extending from an axial face of the segment.

[0049] In some cases, the alignment feature may comprise a tapered edge on the shell portion of each segment configured to mate with a corresponding tapered surface on an adjacent segment. In some cases, the alignment feature may comprise interlocking geometric shapes formed on mating surfaces of adjacent segments. In some cases, the alignment feature may comprise a series of circumferentially spaced notches along an edge of the segment.

[0050] In some cases, the alignment feature may comprise optical or visual markers on each segment to guide proper orientation during assembly. In some cases, clocking features may be positioned on each segment for alignment, with clocking features on segments comprising tabs or protrusions for rotational alignment. The clocking features may serve a similar purpose to alignment features found on conventional mid plates.

[0051] The monolithic construction of each segment 302, where the segment wall 308 and mid plate 314 may be formed as a single piece, may eliminate gaps that may cause flow maldistribution in the assembled heat exchanger 300. The alignment features may provide proper hole alignment for the microtubes 306 when the shell-mid-plate segments 302 may be stacked in sequence. The rotational position of one segment relative to another segment may be controlled through the alignment features to maintain proper indexing, as the holes 304 may have fairly tight clearances and may require precise alignment for the microtubes 306 to pass through the entire length of the assembled heat exchanger 300.

[0052] Referring to FIG. 4, a heat exchanger 400 may comprise a first tube flow port 402 and a second tube flow port 404 positioned at opposite ends of the device. The heat exchanger 400 may also feature a first shell flow port 406 and a second shell flow port 408 for shell-side fluid flow. The first tube flow port 402 and second tube flow port 404 may provide inlet and outlet connections for tube-side fluid, while the first shell flow port 406 and second shell flow port 408 may provide inlet and outlet connections for shell-side fluid.

[0053] The heat exchanger 400 may comprise a plurality of joined segments 410 that may be joined together to form an overall structure. The plurality of joined segments 410 may appear as cylindrical sections that may be welded or otherwise connected in series along a longitudinal axis of the heat exchanger 400. The shell-mid-plate segments 302 may be joined to adjacent segments by welding to form the plurality of joined segments 410. In some cases, the welding may comprise laser welding.

[0054] In some aspects, the monolithic shell-mid-plate segments may be formed using various manufacturing techniques to achieve the desired integrated structure. For example, the segments may be manufactured using additive manufacturing processes such as selective laser sintering, direct metal laser sintering, or electron beam melting. These additive techniques may allow for complex internal geometries and precise control of material properties throughout the segment.

[0055] In some cases, the shell-mid-plate segments may be formed through investment casting processes. This approach may enable the creation of intricate internal features and thin-walled structures while maintaining the monolithic nature of each segment. The casting process may be optimized to minimize porosity and ensure uniform material properties throughout the segment.

[0056] Some implementations may utilize powder metallurgy techniques to form the monolithic segments. This method may involve compacting metal powders into the desired shape and then sintering the compacted powder to create a solid, integrated structure. Powder metallurgy may allow for precise control of material composition and may be suitable for producing segments with specific thermal or mechanical properties.

[0057] In certain aspects, the shell-mid-plate segments may be manufactured through a combination of forging and machining processes. Initial forging operations may create a near-net shape blank, which may then be precision machined to achieve the final geometry, including the formation of holes and alignment features.

[0058] The joining of adjacent shell-mid-plate segments may be accomplished through various methods depending on the specific requirements of the application. In some cases, fusion welding techniques such as electron beam welding, laser welding, or tungsten inert gas (TIG) welding may be employed. These welding methods may create high-strength joints with minimal distortion, preserving the alignment between segments.

[0059] Some implementations may utilize brazing techniques to join the segments. Brazing may allow for the creation of strong, leak-tight joints while minimizing thermal distortion of the segments. In certain cases, vacuum brazing may be employed to ensure high-quality joints free from oxidation or contamination.

[0060] In some aspects, mechanical joining methods may be used to connect adjacent segments. This may include the use of high-strength bolts or specialized fasteners designed to maintain proper alignment and sealing between segments. Mechanical joining may allow for easier disassembly and maintenance of the heat exchanger in some applications.

[0061] Some implementations may employ a combination of welding and mechanical fastening. For example, tack welds may be used to initially position and align the segments, followed by the installation of mechanical fasteners to provide the primary structural connection.

[0062] In certain cases, adhesive bonding may be used to join the shell-mid-plate segments. High-performance structural adhesives may provide strong, uniform bonds while accommodating slight variations in thermal expansion between components. Adhesive bonding may be particularly suitable for applications involving dissimilar materials or where minimal joint thickness is desired.

[0063] Some aspects may utilize diffusion bonding techniques to join the segments. This solid-state joining process may create high-strength connections with minimal microstructural changes at the joint interface. Diffusion bonding may be particularly advantageous for heat exchangers operating at elevated temperatures or in corrosive environments.

[0064] In some implementations, the joining method may incorporate sealing elements to ensure leak-tight connections between segments. This may include the use of specialized gaskets, O-rings, or metal seals designed to maintain proper sealing under the operating conditions of the heat exchanger.

[0065] The selection of joining method may depend on factors such as the operating temperature range, pressure requirements, fluid compatibility, and expected thermal cycling of the heat exchanger. In some cases, a combination of joining techniques may be employed to optimize the performance and reliability of the assembled heat exchanger structure.

[0066] A plurality of tubes 412 may extend through a length of the heat exchanger 400, passing through the plurality of joined segments 410. The plurality of tubes 412 may correspond to the microtubes 306 described in relation to FIG. 3, and may provide a pathway for tube-side fluid flow between the first tube flow port 402 and the second tube flow port 404. The plurality of tubes 412 may pass through the holes 304 in each of the shell-mid-plate segments 302 that form the plurality of joined segments 410.

[0067] The heat exchanger 400 may comprise two tube sheets, wherein the microtubes 306 and shell-mid-plate segments 302 may be joined to the tube sheets at both ends of the heat exchanger 400. The tube sheets may be positioned at locations corresponding to the first tube flow port 402 and second tube flow port 404, providing structural support and sealing interfaces for the plurality of tubes 412.

[0068] The heat exchanger 400 may further comprise a shell-side fluid flow path through spaces between the microtubes 306 and the holes 304. Shell-side fluid may flow through spaces around the plurality of tubes 412 within the plurality of joined segments 410, entering and exiting through the first shell flow port 406 and second shell flow port 408. The shell-side fluid flow path may be contained within the fused / joined structure formed by joining the shell-mid-plate segments 302 together.

[0069] In some cases, laser welding may be performed at an angle to avoid direct line of sight to the plurality of tubes 412 near the segment wall 308. The angled laser welding approach may prevent direct energy deposition on tubes positioned close to outer regions of the tube array, particularly those tubes located near the segment wall 308 of each shell-mid-plate segment 302. By angling the laser, line of sight between the laser and the plurality of tubes 412 may be eliminated, thereby protecting the tubes from potential damage during the welding process.

[0070] In some cases, weld joints may include protruding features or lips to provide adequate weld cross-section between adjacent shell-mid-plate segments 302. The protruding features may extend from mating surfaces of the segments and may provide additional material for the welding process. The weld joints with protruding features may allow for proper penetration and adequate weld cross-section at joined segments while maintaining clearance from the plurality of tubes 412 positioned within the segments.

[0071] The segmented construction approach demonstrated by the heat exchanger 400 may allow individual segments to be manufactured separately and then assembled to create a complete heat exchanger structure. The plurality of joined segments 410 may provide precise control of internal geometry and may eliminate gaps that might occur between mid plates 104 and shell walls in conventional designs. The monolithic nature of each shell-mid-plate segment 302 within the plurality of joined segments 410 may maintain proper flow distribution characteristics throughout the assembled heat exchanger 400.

[0072] Referring to FIG. 5, a method 500 of manufacturing the heat exchanger 300 may comprise a series of sequential steps that may provide a structured approach to assembling the segmented heat exchanger design. The method 500 may begin with a step 502, where the shell-mid-plate segments 302 may be manufactured. The step 502 may involve forming a plurality of monolithic shell-and-mid-plate segments 302, wherein each segment may comprise a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece.

[0073] The method 500 may then proceed to a step 504, where a plurality of the microtubes 306 may be obtained. The step 504 may involve acquiring the microtubes 306 that may be sized and configured to pass through the holes 304 in the shell-mid-plate segments 302. In some cases, the microtubes 306 may be obtained from suppliers or may be manufactured to specific dimensional requirements for the heat exchanger 300 application.

[0074] Following the step 504, the method 500 may move to a step 506, where the heat exchanger 300 may be assembled by combining the shell-and-mid-plate segments 302 and the plurality of the microtubes 306. The step 506 may involve an assembly process where the microtubes 306 may be inserted first through the holes 304 in the shell-mid-plate segments 302. In some cases, the assembly process may involve positioning the shell-mid-plate segments 302 in a spaced configuration and inserting the microtubes 306 through the aligned holes 304 of all segments simultaneously.

[0075] The method 500 may conclude with a step 508, where adjacent shell-mid-plate segments 302 of the heat exchanger 300 may be joined together. The step 508 may involve joining adjacent shell-and-mid-plate segments 302 of the heat exchanger 300 through welding processes. In some cases, the step 508 may involve sliding the shell-mid-plate segments 302 together so that the segments may be in close contact, segment by segment, before welding operations commence.

[0076] In some cases, the step 508 may involve tack welding that may be used to temporarily hold the shell-mid-plate segments 302 in place during assembly. The tack welding may provide temporary positioning before final welding operations may be performed to permanently join the adjacent shell-mid-plate segments 302.

[0077] The method 500 may involve tube sheet installation and welding operations as part of the assembly process. In some cases, one tube sheet may be welded first to provide structural support for the microtubes 306, after which the shell-mid-plate segments 302 may be slid together and welded to each other. A final tube sheet may then be positioned and welded to complete the assembly.

[0078] In some cases, the final tube sheet may be positioned and shimmed or trimmed to achieve uniform tube alignment to the tube sheet surface. The microtubes 306 may protrude or be recessed from the tube sheet by a controlled amount, such as four to six thousandths of an inch, to facilitate uniform welding conditions. The controlled alignment may provide consistent welding parameters across all the microtubes 306 and may reduce variability in the welding process.

[0079] In some aspects, the microtubes 306 may be joined to the tube sheets using various techniques. One approach may involve expanding the ends of the microtubes 306 to create a tight mechanical fit within the tube sheet holes. This expansion process may be performed using hydraulic or mechanical tube expanders, which may apply controlled pressure to the interior of the microtubes 306, causing them to expand and form a seal against the tube sheet material.

[0080] In some implementations, the microtubes 306 may be welded to the tube sheets. This welding process may involve techniques such as orbital welding, where a specialized welding head rotates around each microtube 306 to create a continuous, high-quality weld. Alternatively, automated welding systems may be employed to simultaneously weld multiple microtubes 306 to the tube sheet, improving efficiency and consistency in the joining process.

[0081] Some aspects may utilize brazing techniques to join the microtubes 306 to the tube sheets. In this approach, a brazing alloy may be applied between the microtubes 306 and the tube sheet holes. The assembly may then be heated in a controlled environment, causing the brazing alloy to melt and flow, creating a strong metallurgical bond upon cooling. Vacuum brazing may be employed in some cases to ensure high-quality, oxide-free joints.

[0082] Some implementations may incorporate seal welding techniques to join the microtubes 306 to the tube sheets. This method may involve creating a small fillet weld around the circumference of each microtube 306 where it meets the tube sheet surface. Seal welding may provide both a structural connection and a leak-tight seal, which may be particularly important in high-pressure or corrosive environments.

[0083] In certain aspects, the joining process may include post-weld heat treatment to relieve residual stresses and optimize the metallurgical properties of the welded joints. This heat treatment process may be carefully controlled to maintain the dimensional stability of the assembly while enhancing the long-term reliability of the tube-to-tubesheet connections.

[0084] The method 500 may provide manufacturing advantages through the sequential approach to component fabrication and assembly. The monolithic construction of each shell-mid-plate segment 302 may eliminate the need for precise tolerances between separate shell and mid-plate components, while the sequential assembly process may allow for quality control at each stage of manufacturing.

[0085] Referring to FIG. 6, a method 600 of manufacturing a heat exchanger may comprise a series of sequential steps that may provide an alternative approach to the manufacturing process described in relation to the method 500. The method 600 may begin with a step 602, which may involve manufacturing the shell-mid-plate segments 302. The step 602 may involve forming a plurality of monolithic shell and mid-plate segments, wherein each segment may comprise a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece, and the mid-plate portion of each segment may have a plurality of the holes 304.

[0086] The method 600 may then proceed to a step 604, where a plurality of the microtubes 306 may be obtained. The step 604 may involve acquiring the microtubes 306 that may be sized and configured to pass through the holes 304 in the shell-mid-plate segments 302. In some cases, the microtubes 306 may be obtained from suppliers or may be manufactured to specific dimensional requirements for the heat exchanger application.

[0087] Following the step 604, the method 600 may move to a step 606, which may involve assembling and joining adjacent shell-mid-plate segments 302 together. The step 606 may represent a different sequence compared to the method 500, where the shell-mid-plate segments 302 may be joined to adjacent segments to form a shell assembly before the microtubes 306 may be inserted. In some cases, the step 606 may involve stacking the shell-mid-plate segments 302 in sequence and welding the segments together to create the plurality of joined segments 410.

[0088] The method 600 may conclude with a step 608, where the heat exchanger may be assembled by combining the fused / joined shell-mid-plate segments 302 and the plurality of the microtubes 306. The step 608 may involve inserting the plurality of the microtubes 306 through the holes 304 in the mid-plate portions of the joined segments after the shell assembly may be completed. In some cases, the step 608 may involve threading the microtubes 306 through the aligned holes 304 of the pre-assembled shell structure formed by the joined shell-mid-plate segments 302.

[0089] The method 600 may provide manufacturing flexibility by allowing the shell assembly to be completed and inspected before the microtubes 306 may be installed. In some cases, the pre-assembled shell structure may be tested for dimensional accuracy and alignment of the holes 304 before the microtubes 306 may be inserted. The method 600 may allow for quality control of the shell assembly independently from the microtube installation process.

[0090] In some cases, the method 600 may involve joining the microtubes 306 and the shell-mid-plate segments 302 to tubesheets at both ends of the heat exchanger after the step 608 may be completed. The tubesheets may be positioned and welded to the microtubes 306 and the shell-mid-plate segments 302 to provide structural support and sealing interfaces for the completed heat exchanger assembly.

[0091] The alternative sequence provided by the method 600 may accommodate different manufacturing constraints or equipment configurations compared to the method 500. In some cases, the method 600 may be selected when welding operations on the shell-mid-plate segments 302 may be performed more efficiently before the microtubes 306 may be installed, or when inspection of the shell assembly may be required before microtube installation may proceed.

[0092] The heat exchanger 300 may operate through functional integration of the shell-mid-plate segments 302 to eliminate flow maldistribution and achieve improved heat transfer effectiveness compared to conventional designs. The monolithic construction of each shell-mid-plate segment 302 may address flow distribution problems that may occur in conventional heat exchangers where separate shell and mid-plate components may create gaps.

[0093] In conventional designs such as the heat exchanger 200 shown in FIG. 2, the midplate shell gap 204 may allow the shell flow 210 to bypass intended heat transfer surfaces around the microtubes. The midplate shell gap 204 may create a path of reduced flow resistance that may divert the shell flow 210 away from the tube surfaces where heat transfer may occur. When the midplate shell gap 204 has dimensions comparable to the midplate tube gap 206, flow maldistribution may become pronounced, particularly affecting heat exchanged in tubes positioned around a perimeter of the tube array.

[0094] The heat exchanger 300 may eliminate such flow maldistribution through the monolithic construction of the shell-mid-plate segments 302. Each shell-mid-plate segment 302 may comprise a shell portion and a mid-plate portion that may be permanently joined or integrally formed as a single piece, thereby eliminating the midplate shell gap 204 that may occur between separate components. The segment wall 308 and the mid plate 314 may be formed as a continuous structure without gaps that may allow bypass flow.

[0095] The shell-mid-plate segments 302 may be manufactured using various techniques to achieve the monolithic construction. In some cases, the shell-mid-plate segments 302 may be manufactured by machining from solid pieces of material. The machining process may involve removing material from a solid block to create the segment wall 308, the mid plate 314, and the holes 304 in a single manufacturing operation. In some cases, the shell-mid-plate segments 302 may be manufactured by casting, where molten material may be poured into a mold that may define the shape of the segment wall 308, the mid plate 314, and the holes 304.

[0096] In some cases, each segment may be manufactured using at least machining, casting, or additive manufacturing techniques. The shell-mid-plate segments 302 may be manufactured by additive manufacturing, where material may be deposited layer by layer to build up the segment wall 308, the mid plate 314, and the holes 304 according to a digital model. The additive manufacturing process may allow for complex internal geometries and may provide design flexibility for optimizing flow characteristics.

[0097] In some aspects, the heat exchanger may be constructed using a hybrid approach where the shell segment and mid-plate segment are manufactured separately and then joined together. This method may offer certain advantages in terms of manufacturing flexibility and material selection.

[0098] The shell segment may be formed using techniques such as rolling and welding of sheet metal, extrusion, or centrifugal casting. These methods may allow for the creation of a cylindrical shell with precise dimensional control and surface finish. The shell segment may be manufactured from materials selected for their structural properties, corrosion resistance, or thermal characteristics.

[0099] Separately, the mid-plate segment may be fabricated using processes such as stamping, laser cutting, or water jet cutting. These techniques may enable the creation of complex hole patterns and flow distribution features in the mid-plate. The mid-plate segment may be made from materials chosen for their heat transfer properties or compatibility with the working fluids.

[0100] Once the shell segment and mid-plate segment are manufactured, they may be joined together using various methods. Welding may be employed to create a permanent bond between the segments. In some cases, electron beam welding or laser welding may be used to minimize heat input and distortion. Alternatively, brazing techniques may be utilized to join the segments, particularly when dissimilar materials are involved.

[0101] In some implementations, mechanical joining methods may be used to connect the shell and mid-plate segments. This may involve the use of flanges, bolts, or specialized fasteners designed to maintain proper alignment and sealing between the segments. Mechanical joining may allow for easier disassembly and maintenance of the heat exchanger in certain applications.

[0102] The joining process may incorporate alignment features to ensure proper positioning of the mid-plate within the shell. These features may include tabs, slots, or pins that correspond between the shell and mid-plate segments. In some cases, optical alignment systems or precision fixtures may be used during the joining operation to achieve the required tolerances.

[0103] After joining, the assembly may undergo inspection and testing to verify the integrity of the connection and ensure that no gaps or misalignments exist between the shell and mid-plate segments. Non-destructive testing methods such as ultrasonic inspection or helium leak testing may be employed to validate the quality of the joined assembly.

[0104] This hybrid approach of manufacturing separate shell and mid-plate segments before joining may provide benefits in terms of material optimization, manufacturing efficiency, and quality control. It may allow for the use of different materials or manufacturing processes for each component, tailored to their specific requirements. Additionally, this method may facilitate easier inspection and validation of individual components prior to final assembly.

[0105] The shell-mid-plate segments 302 may be made of a material selected from the group consisting of stainless steel, aluminum alloys, titanium alloys, and high-temperature resistant alloys. The material selection may depend on operating temperature requirements, corrosion resistance needs, and thermal expansion characteristics of the application. In some cases, stainless steel may be selected for cryogenic applications due to its low thermal conductivity and compatibility with welding processes.

[0106] The heat exchanger 400 may demonstrate the functional integration of multiple shell-mid-plate segments 302 joined together to form the plurality of joined segments 410. The shell flow may enter through the first shell flow port 406 and may flow through spaces around the plurality of tubes 412 within the plurality of joined segments 410. The monolithic construction of each segment within the plurality of joined segments 410 may maintain uniform flow distribution as the shell flow moves through the heat exchanger 400.

[0107] The tube flow may enter through the first tube flow port 402 and may pass through the plurality of tubes 412, exiting through the second tube flow port 404. Heat transfer may occur between the shell flow and the tube flow as the fluids move through the heat exchanger 400. The elimination of gaps between shell and mid-plate components may allow the shell flow to more effectively exchange heat with the plurality of tubes 412 throughout the length of the heat exchanger 400.

[0108] The alignment ledge 310 and the alignment protrusion 312 may provide proper positioning of adjacent shell-mid-plate segments 302 during assembly. The alignment features may maintain rotational indexing between segments to provide that the holes 304 in adjacent segments may align properly for the microtubes 306 to pass through the assembled structure. The proper alignment may maintain flow distribution characteristics by preventing misalignment that may create flow restrictions or bypass paths.

[0109] The functional integration of the shell-mid-plate segments 302 may provide improved effectiveness levels compared to conventional designs. By eliminating bypass flow through gaps, the shell flow may be directed uniformly around the microtubes 306, maximizing heat transfer between the shell flow and the tube flow. The monolithic construction may maintain flow distribution characteristics that may be designed into each segment, providing consistent performance throughout the assembled heat exchanger.Terminology

[0110] The terminology used above may be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific examples of the present disclosure. Indeed, certain terms may even be emphasized above; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section. Both the foregoing general description and the detailed description are exemplary and explanatory only and are not restrictive of the features, as claimed.

[0111] As used herein, the terms “comprises,”“comprising,”“having,” including,” or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, article, or apparatus.

[0112] In this disclosure, relative terms, such as, for example, “about,”“substantially,”“generally,” and “approximately” are used to indicate a possible variation of ±10% in a stated value.

[0113] As used herein, the terms “transmit,”“provide,”“receive,” and “obtain” may refer to the transfer or communication of data, information, or signals between various components or entities. This may include, but is not limited to, transmission over a network (such as a local area network, wide area network, or the Internet), transfer between devices (such as between computers, smartphones, or other electronic devices), communication between central processing units (CPUs) or graphics processing units (GPUs), exchange of information between microservices, transfer of data between software components within an environment, or any other form of data transfer or communication as indicated by the context in which the terms are used. The specific mode or medium of transmission or provision may vary depending on the particular implementation and system architecture.

[0114] As used herein, the term “module” may refer to software code, a software component, a software function, a software application, and firmware. As indicated by context, “module” may be logical, digital, analog, optical, electronic, or quantum implementations of operations or functions. A module may be implemented as a standalone unit or as part of a larger system. In some cases, a module may interact with other modules or components to perform specific tasks or operations within the system. As indicated by context or based on design preference, any two modules may be combined. As indicated by context or based on design preference, any module may be broken into two or more modules that provide some or all of the operations or functions of the single module. The specific implementation of module(s) may vary depending on the requirements of the system and the particular application.

[0115] The term “exemplary” is used in the sense of “example” rather than “ideal.” As used herein, the singular forms “a,”“an,” and “the” include plural reference unless the context dictates otherwise.EXAMPLES

[0116] Exemplary embodiments of the systems and methods disclosed herein are described in the numbered paragraphs below.

[0117] A1. A heat exchanger, comprising: a plurality of monolithic shell and mid-plate segments, each segment comprising a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece; a plurality of clearance holes extending through the mid-plate portion of each segment; a plurality of microtubes extending through the clearance holes of the segments; and two tubesheets, wherein the microtubes and segments are joined to the tubesheets at both ends of the heat exchanger.

[0118] A2. The heat exchanger of A1, wherein the segments are joined to adjacent segments by joining.

[0119] A3. The heat exchanger of A2, wherein the joining comprises laser welding.

[0120] A4. The heat exchanger of any of A1-A3, wherein the clearance holes in each segment are arranged in a predetermined pattern to align with clearance holes in adjacent segments when joined.

[0121] A5. The heat exchanger of any of A1-A4, wherein the shell portion of each segment has an inner diameter sized to accommodate the plurality of microtubes.

[0122] A6. The heat exchanger of any of A1-A5, wherein the mid-plate portion of each segment: in a case of a circular configuration, extends radially inward from the shell portion; in a case of an annular configuration, extends radially between the shell portion and an interior wall of the annular configuration; and, in a case of a non-circular configuration or non-annular configuration, extends from the shell portion towards an interior.

[0123] A7. The heat exchanger of any of A1-A6, further comprising a shell-side fluid flow path through spaces between the microtubes and clearance holes.

[0124] A8. The heat exchanger of any of A1-A7, wherein each shell and mid-plate segment comprises a stacking alignment feature configured to mate with a corresponding stacking alignment feature on an adjacent segment.

[0125] A9. The heat exchanger of A8, wherein the stacking alignment feature comprises one of a ledge or a protrusion on an axial face of the segment.

[0126] A10. The heat exchanger of any of A1-A9, wherein the shell portion and mid-plate portion of each segment are formed from a single piece of material.

[0127] A11. The heat exchanger of any of A1-A10, wherein the shell portion of each segment comprises a cylindrical wall section.

[0128] A12. The heat exchanger of any of A1-A11, wherein the mid-plate portion of each segment comprises a disc-shaped section extending radially inward from the shell portion.

[0129] A13. The heat exchanger of any of A1-A12, wherein each segment is manufactured using at least machining, casting, or additive manufacturing techniques.

[0130] A14. The heat exchanger of any of A1-A13, wherein the segments are made of a material selected from the group consisting of stainless steel, aluminum alloys, titanium alloys, and high-temperature resistant alloys.

[0131] A15. The heat exchanger of any of A1-A14, wherein each segment comprises hole alignment features configured to align the clearance holes with corresponding clearance holes in adjacent segments.

[0132] A16. The heat exchanger of A15, wherein the alignment feature comprises a marking, a protrusion, or a recess on one axial face or side face of the segment and a corresponding marking, protrusion, or recess on an opposite axial face or side face of an adjacent segment.

[0133] A17. The heat exchanger of A15, wherein the alignment feature comprises a keyed interface between adjacent segments.

[0134] A18. The heat exchanger of A15, wherein the alignment feature comprises at least one alignment pin extending from an axial face of the segment.

[0135] A19. The heat exchanger of A15, wherein the alignment feature comprises a series of circumferentially spaced notches along an edge of the segment.

[0136] A20. The heat exchanger of A15, wherein the alignment feature comprises optical or visual markers on each segment to guide proper orientation during assembly.

[0137] A21. The heat exchanger of A15, wherein the alignment feature comprises a tapered edge on the shell portion of each segment configured to mate with a corresponding tapered surface on an adjacent segment.

[0138] A22. The heat exchanger of A15, wherein the alignment feature comprises interlocking geometric shapes formed on mating surfaces of adjacent segments.

[0139] B1. A method of manufacturing a heat exchanger, comprising: forming a plurality of monolithic shell-and-mid-plate segments, wherein each segment comprises a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece; joining adjacent shell-and-mid-plate segments to form a shell assembly; inserting a plurality of microtubes through clearance holes in the mid-plate portions of the joined segments; and joining the microtubes and segments to tubesheets at both ends of the heat exchanger.

[0140] C1. A method of manufacturing a heat exchanger, comprising: forming a plurality of monolithic shell and mid-plate segments, wherein each segment comprises a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece, and the mid-plate portion of each segment has a plurality of clearance holes; obtaining a plurality of microtubes; assembling the heat exchanger by combining the shell-and-mid-plate segments and the plurality of microtubes; joining adjacent shell-and-mid-plate segments of the heat exchanger; and joining the microtubes and shell-and-mid-plate segments to tubesheets at both ends of the heat exchanger.

[0141] Other aspects of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Examples

examples

[0116]Exemplary embodiments of the systems and methods disclosed herein are described in the numbered paragraphs below.

[0117]A1. A heat exchanger, comprising: a plurality of monolithic shell and mid-plate segments, each segment comprising a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece; a plurality of clearance holes extending through the mid-plate portion of each segment; a plurality of microtubes extending through the clearance holes of the segments; and two tubesheets, wherein the microtubes and segments are joined to the tubesheets at both ends of the heat exchanger.

[0118]A2. The heat exchanger of A1, wherein the segments are joined to adjacent segments by joining.

[0119]A3. The heat exchanger of A2, wherein the joining comprises laser welding.

[0120]A4. The heat exchanger of any of A1-A3, wherein the clearance holes in each segment are arranged in a predetermined pattern to align with clearance holes in adjacent segments when join...

Claims

1. A heat exchanger, comprising:a plurality of monolithic shell and mid-plate segments, each segment comprising a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece;a plurality of clearance holes extending through the mid-plate portion of each segment;a plurality of microtubes extending through the clearance holes of the segments; andtwo tubesheets, wherein the microtubes and segments are joined to the tubesheets at both ends of the heat exchanger.

2. The heat exchanger of claim 1, wherein the segments are joined to adjacent segments by joining.

3. The heat exchanger of claim 2, wherein the joining comprises laser welding.

4. The heat exchanger of claim 1, wherein the clearance holes in each segment are arranged in a predetermined pattern to align with clearance holes in adjacent segments when joined.

5. The heat exchanger of claim 1, wherein the shell portion of each segment has an inner diameter sized to accommodate the plurality of microtubes.

6. The heat exchanger of claim 1, wherein the mid-plate portion of each segment: in a case of a circular configuration, extends radially inward from the shell portion; in a case of an annular configuration, extends radially between the shell portion and an interior wall of the annular configuration; and, in a case of a non-circular configuration or non-annular configuration, extends from the shell portion towards an interior.

7. The heat exchanger of claim 1, further comprising a shell-side fluid flow path through spaces between the microtubes and clearance holes.

8. The heat exchanger of claim 1, wherein each shell and mid-plate segment comprises a stacking alignment feature configured to mate with a corresponding stacking alignment feature on an adjacent segment.

9. The heat exchanger of claim 8, wherein the stacking alignment feature comprises one of a ledge or a protrusion on an axial face of the segment.

10. The heat exchanger of claim 1, wherein the shell portion and mid-plate portion of each segment are formed from a single piece of material.

11. The heat exchanger of claim 1, wherein the shell portion of each segment comprises a cylindrical wall section.

12. The heat exchanger of claim 1, wherein the mid-plate portion of each segment comprises a disc-shaped section extending radially inward from the shell portion.

13. The heat exchanger of claim 1, wherein each segment is manufactured using at least machining, casting, or additive manufacturing techniques.

14. The heat exchanger of claim 1, wherein the segments are made of a material selected from the group consisting of stainless steel, aluminum alloys, titanium alloys, and high-temperature resistant alloys.

15. The heat exchanger of claim 1, wherein each segment comprises hole alignment features configured to align the clearance holes with corresponding clearance holes in adjacent segments.

16. The heat exchanger of claim 15, wherein the alignment feature comprises a marking, a protrusion, or a recess on one axial face or side face of the segment and a corresponding marking, protrusion, or recess on an opposite axial face or side face of an adjacent segment.

17. The heat exchanger of claim 15, wherein the alignment feature comprises a keyed interface between adjacent segments.

18. The heat exchanger of claim 15, wherein the alignment feature comprises at least one alignment pin extending from an axial face of the segment.

19. The heat exchanger of claim 15, wherein the alignment feature comprises a series of circumferentially spaced notches along an edge of the segment.

20. The heat exchanger of claim 15, wherein the alignment feature comprises optical or visual markers on each segment to guide proper orientation during assembly.

21. The heat exchanger of claim 15, wherein the alignment feature comprises a tapered edge on the shell portion of each segment configured to mate with a corresponding tapered surface on an adjacent segment.

22. The heat exchanger of claim 15, wherein the alignment feature comprises interlocking geometric shapes formed on mating surfaces of adjacent segments.

23. A method of manufacturing a heat exchanger, comprising:forming a plurality of monolithic shell-and-mid-plate segments, wherein each segment comprises a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece;joining adjacent shell-and-mid-plate segments to form a shell assembly;inserting a plurality of microtubes through clearance holes in the mid-plate portions of the joined segments; andjoining the microtubes and segments to tubesheets at both ends of the heat exchanger.

24. A method of manufacturing a heat exchanger, comprising:forming a plurality of monolithic shell and mid-plate segments, wherein each segment comprises a shell portion and a mid-plate portion permanently joined or integrally formed as a single piece, and the mid-plate portion of each segment has a plurality of clearance holes;obtaining a plurality of microtubes;assembling the heat exchanger by combining the shell-and-mid-plate segments and the plurality of microtubes;joining adjacent shell-and-mid-plate segments of the heat exchanger; andjoining the microtubes and shell-and-mid-plate segments to tubesheets at both ends of the heat exchanger.

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