Lattice and microcapillary structures for flow paths in laminated metal parts

Abstract

Methods and configurations for high performance heat exchangers and cold plates, some with internal lattice structures and microcapillaries. Some embodiments include manufacture via laminated object manufacturing methods, which includes patterning a plurality of metal sheets so that at least one metal sheet contains at least one void space of a plurality of void spaces, each metal sheet comprising a self-supporting layer; assembling the plurality of metal sheets so that the plurality of void spaces forms at least one channel; and bonding the plurality of assembled metal sheets to form a heat exchanger with at least one flow path formed from the at least one channel, the heat exchanger having a geometry that is continuously self-supporting through each assembled metal sheet.

Description

LATTICE AND MICROCAPILLARY STRUCTURES FOR FLOW PATHS IN LAMINATED METAL PARTSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of and priority to United States Provisional Application No. 63 / 658,830, filed on June 11, 2024, and United States Provisional Application No. 63 / 791,225, filed on April 18, 2025, the entire disclosures of each of which are hereby incorporated by reference as if set forth in their entirety herein.TECHNICAL FIELD

[0002] Embodiments described herein generally relate to methods and apparatus for fabricating metal laminated object parts, and more specifically to the manufacture of laminated object parts with internal flow paths.BACKGROUND

[0003] Effective thermal management is essential for high-performance electronics, power devices, photonics, and other systems where excess heat can damage components and / or degrade performance. Heat exchangers, such as cold plates and heat sinks, are often used to transfer heat from a source to a working fluid. Such heat exchangers may be manufactured using a variety of manufacturing processes, such as laminated object manufacturing (LOM), and may include internal flow paths that allow a cooling gas, fluid, and / or vacuum force to flow therein. LOM involves assembling complex 3D structures by sequentially depositing layers of material. Each successive layer may be bonded to and / or deposited on the previous layer to gradually assemble the 3D structure.

[0004] The efficiency of heat transfer within a heat exchanger is dependent on factors such as the flow path geometry, surface area, material properties, and surface characteristics of the channel network through which the coolant flows. In systems with laminar flow, typically characterized by low Reynolds numbers, the relationship between the Nusselt number (a dimensionless measure of convective heat transfer relative to conduction) and flow velocity becomes negligible. Specifically, for turbulent flow, the Nusselt number (Nu) scales with the Reynolds number (Re)whereas for laminar flow, the Nusselt number becomes independent of velocity (Alt oc Re0). This indicates that in laminar flow scenarios, increasing the velocity or number of parallel flow paths does not substantially enhance convective heat transfer.

[0005] Nonetheless, increasing the number of parallel flow paths provides several other benefits for heat exchangers. These include an increased surface area, increased heat transfer, increased thermal uniformity, and a reduction in pressure drop, which can contribute to improved overall thermal performance. These benefits may be realized by decreasing the hydraulic diameter of the flow channels, decreasing channel length, and enabling lower velocity flow. The hydraulic diameter (D / J is defined by the cross-sectional flow area (A) and wetted perimeter (S): (Dh= 4A / S). The pressure drop AP along a channel is proportional to the square of the flow velocity and the channel length (L) divided by the hydraulic diameter (Dh): AP oc v2( — ). Increasing the number of channels necessarily reduces the channel length and the average fluid velocity. The convective heat transfer coefficient (h) is also inversely correlated with the hydraulic diameter (h oc Nu / Db). By introducing more parallel channels within the same volume, the hydraulic diameter is reduced, which in turn increases the convective heat transfer coefficient, assuming other variables are held constant. By utilizing smaller channels with correspondingly low hydraulic diameters, millimeter (millichannel) or micrometer (microchannel) in scale, excellent heat transfer properties can be attained.

[0006] Designing a heat exchanger which balances the above tradeoffs, factoring in the characteristics of the heat source and installed configuration is a challenge for an engineer skilled in the state of the art without accounting for manufacturing constraints. Conventional machining techniques are unable to form, arrange, and bond many micro-scale features in a cost-effective manner for mass manufacture. Powder-based additive manufacturing can produce intricate millimeter-scale geometries, such as walls, but cannot practically produce numerous parallelized micro-scale gaps, such as channels, due to surface tension effects during fusion, which can cause the channels to close, and powder removal post-printing. Other subtractive techniques, such as skiving, are restricted to planar, two-dimensional channel formations and cannot create three- dimensional or contoured flow paths within a heat exchanger. Skived microchannel arrays have challenges directing flow to the bottom of the microchannel, high pressure drop, and can easily collapse because the fins are cantilevered and unsupported on the top.

[0007] Skived, or similarly manufactured, microchannel heat exchangers are made from fins which are bonded to, or a part of, the heated surface and attached to a larger heat exchanger component. These traditional microchannel devices are not typically bonded to the rest of the component at the top of the fins due to issues with wicking during brazing and force transmission during bonding. This disconnect between the tops of microchannel fins and the rest of thecomponent may adversely affect performance via leakage across the fin tips, or collapse of the long, thin, and cantilevered fin structure.

[0008] Taller fins have more surface area for heat transfer than shorter fins. Without arterioles, traditional microchannels with tall fins that are fed from the top have most of the coolant flowing along the tops of the fins, the farthest away from the heated surface. Without a continuous fin structure, microchannels quickly become weaker as they become taller.

[0009] Designing flow paths with millichannel and microchannel features for laminated metal parts also presents unique challenges for manufacturing processes. In LOM, for example, each individual layer must form a contiguous, self-supporting stencil prior to assembly. Specifically, internal channels must be configured so that each layer maintains structural integrity during manufacturing. At the same time, the channel geometry must be selected to maximize mixing, turning, impingement, and / or surface area to promote heat transfer between the flow material and the part.

[0010] This manufacturing constraint restricts the possible geometries of internal channels. For example, common thermal-fluid channel designs such as networks of simple tubes in two- dimensional arrays, while functional for heat transfer in metal parts, are often unsuitable for LOM. Simple tube designs can sever a part into disconnected regions, rendering the layers non-selfsupporting. Similarly, gyroid structures typically contain long, thin unsupported sections that are prone to collapse or deformation during manufacturing. Furthermore, many LOM processes involve the application of force during layer bonding. Therefore, LOM parts must not only accommodate fluidic designs but also transmit bonding forces uniformly throughout their structure. This requirement further limits the possible geometries for internal channels.

[0011] Accordingly, a need exists for improved designs for metal heat exchangers and cold plates with flow paths, particularly for designs that utilize improved methods and systems of manufacturing.SUMMARY

[0012] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description section. This summary is not intended to identify or exclude key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0013] In some aspects, the techniques described herein relate to a method to produce a heat exchanger via laminated object manufacturing, the method including patterning a plurality of metalsheets so that at least one metal sheet contains at least one void space of a plurality of void spaces, each metal sheet including a self-supporting layer; assembling the plurality of metal sheets so that the plurality of void spaces forms at least one channel; and bonding the plurality of assembled metal sheets to form a heat exchanger with at least one flow path formed from the at least one channel, the heat exchanger having a geometry that is continuously self-supporting through each assembled metal sheet.

[0014] In some aspects, the geometry includes a plurality of peanut-shaped volumes. In some aspects, the peanut-shaped volumes are tessellated at an angle from each other and offset in at least two layers.

[0015] In some aspects, the geometry includes at least one of an ellipsoid geometry, a doubleellipsoid geometry, or a Cassini geometry.

[0016] In some aspects, the at least one flow path is fluidically connected in three dimensions.

[0017] In some aspects, the geometry includes a tessellated structure of ellipses alternating in orientation.

[0018] In some aspects, the geometry includes neighboring flow paths having ellipses offset in the opposite direction.

[0019] In some aspects, the geometry includes a triply periodic minimal surface structure.

[0020] In some aspects, the geometry is arranged in at least one of a spiral configuration, anS-configuration, or a periodic mixing configuration.

[0021] In some aspects, at least one metal sheet contains a plurality of void spaces that form the same channel.

[0022] In some aspects, at least one metal sheet includes a feature with a resolution less than 500 microns.

[0023] In some aspects, the geometry is arranged to optimize packing density within the heat exchanger.

[0024] In some aspects, the techniques described herein relate to a heat exchanger, the heat exchanger having a bonded plurality of metal sheets so that at least one metal sheet contains at least one void space of a plurality of void spaces, each metal sheet including a self-supporting layer, wherein the plurality of void spaces forms at least one channel; and wherein the heat exchanger has a geometry that is continuously self-supporting through each metal sheet.

[0025] In some aspects, the geometry includes a plurality of peanut-shaped volumes.

[0026] In some aspects, the geometry includes at least one of an ellipsoid geometry, a doubleellipsoid geometry, or a Cassini geometry.

[0027] In some aspects, the at least one channel is fluidically connected in three dimensions.

[0028] In some aspects, the geometry includes a tessellated structure of ellipses alternating in orientation.

[0029] In some aspects, the geometry includes neighboring channels having ellipses offset in the opposite direction.

[0030] In some aspects, the geometry includes a triply periodic minimal surface structure.

[0031] In some aspects, the techniques described herein relate to a heat exchanger formed via a laminated object manufacturing process, the process including patterning a plurality of metal sheets so that at least one metal sheet contains at least one void space of a plurality of void spaces, each metal sheet including a self-supporting layer; assembling the plurality of metal sheets so that the plurality of void spaces forms at least one channel; and bonding the plurality of assembled metal sheets to form the heat exchanger with at least one flow path formed from the at least one channel, the heat exchanger having a geometry that is continuously self-supporting through each assembled metal sheet.

[0032] In some aspects, the techniques described herein relate to a heat exchanger including at least one inlet manifold; at least one outlet manifold; and a plurality of microcapillaries fluidically connected to the at least one inlet manifold and the at least one outlet manifold to define at least one flow path through the heat exchanger.

[0033] In some aspects, the heat exchanger is formed via at least one of diffusion bonding, electroplating, electrodeposition, or etching.

[0034] In some aspects, the heat exchanger is formed from a plurality of metal sheets via laminated object manufacturing. In some aspects, the plurality of microcapillaries is formed via a cut through at least one metal sheet using a cutting tool. In some aspects, a dimension of the cut is a single kerf cutting width of the cutting tool.

[0035] In some aspects, the height of at least one microcapillary is the thickness of a metal sheet forming the at least one microcapillary.

[0036] In some aspects, at least one of the cross-sectional dimensions of at least one microcapillary are less than 1 mm.

[0037] In some aspects, at least one of the cross-sectional height and width of at least one microcapillary are between 10 and 1000 microns.

[0038] In some aspects, at least one microcapillary is contoured in three dimensions.

[0039] In some aspects, at least one microcapillary is formed using pin-like or fin-like obstructions that at least partially obstruct the flow within the microcapillary.

[0040] In some aspects, the plurality of microcapillaries is spatially arranged such that regions of the microcapillaries with colder fluid are near regions of the microcapillaries with warmer fluid while the heat exchanger transfers heat.

[0041] In some aspects, the plurality of microcapillaries includes at least 1000 microcapillaries arranged in a parallel fashion.

[0042] In some aspects, the at least one inlet manifold and the at least one outlet manifold are on different faces of the heat exchanger.

[0043] In some aspects, the techniques described herein relate to a method to produce a heat exchanger via laminated object manufacturing, the method including assembling a plurality of patterned metal sheets; and bonding the plurality of assembled metal sheets to form the heat exchanger, the heat exchanger including at least one inlet manifold, at least one outlet manifold, and a plurality of microcapillaries fluidically connected to the at least one inlet manifold and the at least one outlet manifold to define at least one flow path through the heat exchanger.

[0044] In some aspects, the method further includes forming a cut through at least one metal sheet to form the plurality of microcapillaries using a cutting tool prior to the assembly of the plurality of patterned metal sheets.

[0045] In some aspects, a dimension of the cut is a single kerf cutting width of the cutting tool.

[0046] In some aspects, the height of at least one microcapillary is the thickness of a metal sheet forming the at least one microcapillary.

[0047] In some aspects, at least one of the cross-sectional height and width of at least one microcapillary are between 10 and 1000 microns.

[0048] In some aspects, the techniques described herein relate to a system for manufacturing a laminated object heat exchanger, the system including a laminated object manufacturing device configured to assemble a plurality of patterned metal sheets; and a pressor configured to bond the plurality of assembled metal sheets to form the heat exchanger, the heat exchanger including at least one inlet manifold, at least one outlet manifold, and a plurality of microcapillaries fluidicallyconnected to the at least one inlet manifold and the at least one outlet manifold to define at least one flow path through the heat exchanger.

[0049] In some aspects, the system further includes a cutting tool configured to form a cut through at least one metal sheet to form the plurality of microcapillaries prior to the assembly of the plurality of patterned metal sheets.

[0050] In some aspects, the techniques described herein relate to a heat exchanger having an array of microcapillary fluid channels disposed in a tessellated pattern along a heated surface, each channel being between 10 pm and 1000 pm in width; and an array of arterioles configured to convey fluid towards the regions of the microcapillary fluid channel array closest to the heated surface, wherein the hydraulic diameters of the arterioles are greater than the hydraulic diameters of the microcapillaries, and wherein the primary direction of flow in the arterioles is approximately orthogonal to the primary direction of flow in the microcapillaries.BRIEF DESCRIPTION OF DRAWINGS

[0051] Non-limiting and non-exhaustive embodiments of this disclosure are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified:

[0052] Figure 1 illustrates a conventional geometry for internal flow paths;

[0053] Figure 2 illustrates a cross section of a gyroid geometry for internal flow paths;

[0054] Figure 3 illustrates a cross section of another gyroid geometry for internal flow paths;

[0055] Figure 4A illustrates a peanut-type geometry for internal flow paths;

[0056] Figure 4B illustrates cross sections of the peanut-type geometry of Figure 4A;

[0057] Figure 5A illustrates another peanut-type geometry for internal flow paths;

[0058] Figure 5B illustrates cross sections of the peanut-type geometry of Figure 5 A;

[0059] Figure 6A illustrates a tumbling ellipse geometry for internal flow paths;

[0060] Figure 6B illustrates cross sections of the tumbling ellipse geometry of Figure 6A;

[0061] Figure 7 illustrates a bimodal diamond TPMS geometry for internal flow paths;

[0062] Figure 8 is a transparent view of the bimodal diamond TPMS geometry of Figure 7;

[0063] Figure 9 illustrates the bimodal diamond TPMS geometry of Figure 7 with bridging regions;

[0064] Figure 10A illustrates a filled unit cell volume used in the creation of a bimodal diamond TPMS geometry;

[0065] Figure 10B illustrates a cross-section of the filled unit cell volume used in the creation of a bimodal diamond TPMS geometry depicted in Figure 10A;

[0066] Figure 10C presents an embodiment of a rotated gyroid TPMS unit cell;

[0067] Figure 11 A illustrates a spiral geometry for internal flow paths;

[0068] Figure 1 IB illustrates cross sections of the spiral geometry of Figure 11 A;

[0069] Figure 12A illustrates an S-configuration geometry for internal flow paths;

[0070] Figure 12B illustrates cross sections of the S-configuration geometry of Figure 12A;

[0071] Figure 13A illustrates a geometry for internal flow paths;

[0072] Figure 13B illustrates cross sections of the geometry of Figure 13 A;

[0073] Figure 14A depicts a heat exchanger with a flow path comprising manifolds and microcapillaries;

[0074] Figure 14B is a close-up isometric view of the heat exchanger depicted in Figure 14A;

[0075] Figure 15 depicts a part containing a contoured microcapillary;

[0076] Figure 16 depicts cross-sections of microcapillaries with bridging pins;

[0077] Figure 17 depicts a cutting pattern for forming channel networks;

[0078] Figure 18 depicts a high-density channel network;

[0079] Figure 19 is an isometric view of another high-density channel network;

[0080] Figure 20A is a side view of another high-density channel network;

[0081] Figure 20B is an isometric view of the high-density channel network depicted in Figure20A;

[0082] Figure 21 depicts a side view of a flow path with two arterioles connected via a network of microcapillaries; and

[0083] Figure 22 depicts a side view of another flow path with two arterioles connected via a network of microcapillaries.DETAILED DESCRIPTION

[0084] Various embodiments are described more fully below with reference to the accompanying drawings, which form a part hereof, and which show specific exemplary embodiments. However, the concepts of the present disclosure may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided as part of a thorough and complete disclosure, to fully convey the scope of the concepts, techniques and implementations of the present disclosure to those skilled in the art. Embodiments may be practiced as methods, systems or devices. The following detailed description is, therefore, not to be taken in a limiting sense.

[0085] Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one example implementation or technique in accordance with the present disclosure. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

[0086] In addition, the language used in the specification has been principally selected for readability and instructional purposes and may not have been selected to delineate or circumscribe the disclosed subject matter. Accordingly, the present disclosure is intended to be illustrative, and not limiting, of the scope of the concepts discussed herein.Definitions

[0087] Unless otherwise specified, the following terms as used herein shall have the meanings as provided below:

[0088] The term “laminated object manufacturing” (LOM) refers to a method of manufacturing a part, containing additive and subtractive steps, beginning with contiguous sheets of material, and processing sheets sequentially to form a part.

[0089] The term “bonding” refers to the process through which the contiguous sheets of material are formed into a part. The workpiece is subjected to a combination of heat and applied force which form covalent and / or metallic bonds between the sheets of material, forming an object.

[0090] The term “build volume” refers to the geometric volume enclosed by the external faces of the stack of patterned metal sheets.

[0091] The term “layer” refers to an individual sheet in the stack of patterned metal sheets.

[0092] The term “part” refers to the cold plate, heat exchanger, or other object manufactured with internal flow paths through LOM.

[0093] The term “workpiece” refers to a stack of metal sheets to be bonded into at least one part and at least one corresponding support structure.

[0094] The term “metal sheet” refers to a metal sheet or foil that is stacked in the workpiece. Each metal sheet may be patterned to contain part regions and support structure regions. In some embodiments, the metal sheet may comprise at least one of aluminum, copper, magnesium, titanium, aluminum alloy, magnesium alloy, and / or titanium alloy.

[0095] The term “sheet” refers generally to a metallic layer between 25 pm and 10 cm in thickness.

[0096] The term “void” refers to a volume cut out of a metal sheet in the support or part region which is fully enclosed and not fluidically connected to any other internal channel or port within the workpiece.

[0097] The term “void space” refers to a pattern of voids intentionally cut in a given volume or region.

[0098] The term “heated surface” refers to the surface of the heat exchanger that is directly in contact with the heat source and includes the internal surfaces that are immediately opposite the heat source.

[0099] The term “flow path” refers to a traceable path of void space through internal channels in the part from at least one external port to at least a second external port.

[0100] The term “channel” refers to at least a portion of the void space in the flow path.

[0101] The term “fin” refers to a positive geometric feature in a heat exchanger that conducts heat from the heat source away from the heated surface into the heat exchanger so it may be convected away by fluid in the channel. Fins may be planar, curved or otherwise shaped to facilitate the exchange of heat.

[0102] The term “microchannel” refers to a channel with at least one sub -millimeter dimensional characteristic, such as channel width, channel depth, or effective channel diameter. Microchannels are typically arrayed in a regular pattern along one axis and flow parallel to other microchannels.

[0103] The term “microcapillary” refers to a channel having at least one sub -millimeter dimensional characteristic, such as a channel width, channel depth, or effective channel diameter.Whereas microchannels are arrayed in one or two rows, microcapillaries are arrayed several to hundreds of times in orthogonal directions, and may be nonplanar.

[0104] The term “self-supporting” refers to any structure, such as a region of a part or a region of a layer, that maintains its structural integrity after being stacked, lifted or handled in some manner.

[0105] The term “triply periodic minimum surface” (TPMS) structure refers to a three- dimensional geometry with a repeating unit structure which has zero mean curvature.

[0106] The term “heat exchanger” refers to a part configured to transfer heat between a heat source and at least one fluid. In some cases, the heat source may be a fluid and a heat exchanger may transfer heat between two or more fluids.

[0107] The term “cold plate” is understood to describe a subset of heat exchangers which are particularly configured to remove heat from an adjacent heat source and using at least one fluid as a coolant. The cold plate may be configured to interact with a second remote heat exchanger to regenerate the coolant, and a balance of plant to flow the coolant through the cold plate.Embodiments

[0108] Embodiments of this invention include configurations of lattice structures, microchannels, and microcapillaries for use in internal structures of heat exchangers such as cold plates. In embodiments of this invention, the configurations may include the placement of channels within a part to form fluidically connected flow paths for gasses and fluids. In some embodiments, the configurations may include a heat exchanger comprising a network of microcapillaries fluidically connected to at least one inlet manifold and at least one outlet manifold to define at least one flow path. The configurations may include embodiments of channel geometries that are self-supporting and enable the formation of channels in a part assembled using laminated object manufacturing (LOM). Non-limiting examples of these embodiments are further discussed below.Heat Exchangers

[0109] In embodiments of this invention, a heat exchanger such as a cold plate may be assembled via at least one additive or subtractive manufacturing technique. Suitable techniques may include LOM, diffusion bonding, brazing, friction stir welding, transient liquid phase bonding, electroplating, electrodeposition, etching, computer numerical control (CNC) micromachining, laser cutting, stereolithography (SLA), and / or powder bed fusion.

[0110] In embodiments of this invention, at least one flow path may be traced through the part. A complete flow path traced through the part may be defined as a fluidically connected void within the part which is connected to at least two externally accessible ports on the part, such as an inlet port and an outlet port. The flow path may be formed from at least one channel within the part. The flow path may connect to more than two externally accessible ports. The ports may allow for the introduction of a gas and / or fluid through the flow path. At least one of the ports may be an inlet port and / or an outlet port.[OHl] In some embodiments, the ports may be placed on different faces of the part. In other embodiments, the ports may be placed on a single face of the part. In yet other embodiments, the multiple flow paths may be configured through the part in a cross-flow pattern, with, for example, horizontal flow paths and vertical flow paths with ports on multiple faces of the part.

[0112] In some embodiments, a pump system may pump gas and / or fluid through the flow path. In some embodiments, inlet ports and / or outlet ports may be fluidically connected to the ambient atmosphere via the pump system.

[0113] In some embodiments, each port may be connected to at least one manifold. The manifold may be a region of the part, such as a cavity, chamber, channel or plenum, that functions to distribute or collect coolant gas and / or fluid through the network of flow paths within the part. The flow path may thus include the following sequence: fluid enters an inlet port, passes through an inlet manifold, is distributed across one or more internal flow paths, is collected through an outlet manifold, and ultimately exits through an outlet port.

[0114] In some embodiments, the manifold may include flow-directing features such as baffles, diffusers, flow restrictors, and / or plenums. The features may modulate the velocity and uniformity of gas and / or fluid entering or exiting the part.

[0115] In some embodiments, a flow path may include multiple channels that are fluidly connected. In some embodiments, the flow path may consist of multiple channels in parallel. Multiple channels may merge into one or more flow paths in at least a portion of the part. A single channel may split into multiple channels in at least a portion of the part, creating branching flow paths. Flow paths may be merged or split so that one inlet or outlet port may service multiple complementary ports.

[0116] In some embodiments, the part may include multiple flow paths. The flow paths may be arranged in a parallel fashion through the part. In other embodiments, the flow paths may cross each other (e.g., in a zig-zag fashion) along a plane of the part.LOM Part

[0117] In LOM, a workpiece consisting of a plurality of metal sheets may be assembled and bonded. The workpiece may be assembled in a laminated fashion with the metal sheets. In this manner, the workpiece may be a layered workpiece assembled by depositing the metal sheets. The metal sheets may be patterned such that the pattern of the metal sheets partitions the workpiece into at least one support region and at least one part region. The metal sheets may be bonded in a heated press, a more complicated bonding machine comprising a heated press and a vacuum chamber, and / or a bonding machine of any configuration appropriate for laminated object manufacturing of metal parts, such as but not limited to a metal heat exchanger. The metal sheets may be bonded by applying a mechanical force along at least one axial direction of the metal sheets.

[0118] In embodiments of this invention, channels and lattice structures may be formed in a stack of patterned metal sheets (e.g., prior to bonding). For example, the metal sheets may be patterned so that material is removed from at least one part region of each metal sheet. This may create a pattern of void spaces within the workpiece. The channels and lattice structures may be formed from the void spaces after stacking the metal sheets.

[0119] In some embodiments, the part regions may be assembled within a build volume of the workpiece. The build volume may be defined as the geometric volume enclosed by the external faces of the stack of patterned metal sheets.

[0120] In some embodiments, the part regions may be configured to sit at some arbitrary orientation or angle with respect to at least one of the external faces of the build volume. This angle may be selected to reduce or minimize the length of channels or other internal geometric features within a single patterned sheet.

[0121] In some embodiments, each metal sheet may have a unique pattern which comprises a cross-sectional slice of the final part. The pattern on each metal sheet (e.g., a pattern of void spaces) may be configured to transmit force through the metal sheets.

[0122] In some embodiments, the metal sheets may be patterned so that material is removed from at least one part region of each metal sheet. This may create a pattern of void spaces within the workpiece. The void spaces may be formed via any appropriate cutting technique, such as drag knife cutting, laser cutting, and / or etching. The void spaces may be formed from regular, geometric patterns and / or random distributions within the workpiece.

[0123] In some embodiments, at least some of the metal sheets may be between 100 m and 500 pm in order to create smooth and contoured channels with low pressure drop and sufficient circulation to transfer heat effectively. Thin sheets may become weakened during subtractive manufacturing steps such as the material removal part of LOM. A design constraint on the metal sheet patterning requires that the removal process (such as laser cutting with an assist gas) and / or subsequent handling must not damage or alter the layer in excess of desired part tolerances.Channel and Lattice Geometries

[0124] In some embodiments, specific channel geometries may be patterned into the stack of metal sheets prior to bonding. There may be more than one channel geometry within the part, with some embodiments containing multiple channel geometries. In some embodiments, a single channel geometry may be used for a flow path. In some embodiments, the channel geometry may vary along a single flow path.

[0125] Figure 1 illustrates a conventional geometry 100 for internal flow paths. The geometry 100 includes a simple tubular channel 102. While capable of fluid conveyance and heat exchange in traditional manufacturing methods, this configuration presents significant limitations for LOM. Specifically, the channel in the geometry 100 may sever the part into two separate regions, preventing the formation of a continuous, self-supporting stencil within each layer. Such disconnection may undermine the structural integrity required during cutting, assembly, and bonding, leading to deformation, collapse, and / or improper bonding.

[0126] Figure 2 illustrates a cross section of a gyroid geometry 200 with unshaded flow paths 202 and channel walls 204. Gyroid geometries are often adopted in conventional manufacturing techniques for their superior thermal-fluid performance and high surface area-to-volume ratio. However, in the context of LOM, the geometry 200 contains elongated, thin features and lacks sufficient mechanical connectivity across the layer plane, rendering the layer plane non-selfsupporting and prone to similar risks as the geometry 100.

[0127] Figure 3 illustrates another cross section of the same gyroid geometry 200 with flow paths 202. Unlike the gyroid section shown 200, the section 302 may be interconnected, thus creating structurally stable layers. Consequently, the geometry on this layer 300 may be used for manufacturing laminated metal parts with internal flow paths.

[0128] In some embodiments, additional and / or alternate considerations may be used to select the geometry for laminated metal parts with internal flow paths. For example, the thermal performance of internal flow paths may be determined by four interrelated factors: the internalwall surface area exposed to the flowing material, the convective heat transfer effectiveness of the internal surface area, the conductive heat transfer effectiveness of the walls, and the fluidic volume available for flow. A large surface area may enhance convective heat transfer between the flowing material and the solid structure, while sufficient fluidic volume may ensure that pressure drop across the flow network remains manageable at a given flow rate. Channel geometries configured to promote secondary flow and / or impingement improve thermal performance but increase the pressure drop compared to a similar channel geometry without these features. Similarly, channels with a smaller hydraulic diameter exhibit improved thermal performance but increased pressure drop. Geometries with high surface area and open volume to flow may have desirable pressure drop properties, but insufficient heat transfer from the heated surface to the fluid through the internal walls. Optimizing these factors may result in high-efficiency metal parts capable of supporting substantial thermal loads. Trivial attempts to produce self-supporting thermal-fluid geometries, however, may yield solutions with unremarkable performance.

[0129] Accordingly, described herein are embodiments of geometries that may exhibit desirable characteristics for heat exchangers and / or other laminated parts, such as being self- supporting on each layer, fluidically connected in three dimensions, and / or packed appropriately to yield desirable heat transfer performance. In embodiments with laminated metal parts, it is to be appreciated that any of the laminated parts described herein may have features cut into at least some layers with a resolution under 500 micrometers. In some embodiments, the regions may vary in shape so minimally that thicker layers may be appropriate.

[0130] Figure 4A illustrates a Cassini or peanut-type geometry 400 for internal flow paths. Figure 4B illustrates cross sections of the peanut-type geometry 400. The flow paths may be formed using a periodic tessellation of peanut-shaped voids 402. Each void 402 may be rotated approximately 90 degrees (and / or any other suitable angle, such as 45 to 135 degrees) relative to the preceding void. The voids 402 may be offset in at least two layers. This configuration may ensure continuous fluidic interconnection throughout the volume and the formation of self- supporting stencils.

[0131] In some embodiments, the voids 402 may include any suitable geometry, such as ellipsoidal, double-ellipsoid, super-ellipsoid, spheroid, and / or Cassini geometries.

[0132] In some embodiments, the voids 402 may be adjusted based on the desired properties of the metal part. For example, larger peanut-shaped voids may be used to accommodate higher flow rates where lower flow resistance and greater volumetric throughput are desired. Smallerpeanut-shaped voids may be used to achieve higher convective heat transfer coefficients, thereby enhancing heat transfer performance in applications requiring dense cooling configurations.

[0133] In some embodiments, the shape of the voids 402 may be stretched and / or compressed along at least one axis. By elongating the void shapes, for example, the effective flow path length can be increased, thereby enhancing surface area exposure and promoting heat transfer. Compressing the voids 402 may reduce flow resistance and facilitate higher fluid flow rates through the metal part. In some examples, the major axis of the voids 402 may be no more than 3 times the length of the minor axis. In some examples, the major axis of the voids 402 may be at least 1.5 times the length of the minor axis.

[0134] Figure 5 A illustrates another peanut-type geometry 500 for internal flow paths. Figure 5B illustrates cross sections of the peanut-type geometry 500. The geometry 500 may include smaller peanut-shaped voids 502 to create a micro-lattice pattern of capillary flow paths. Flow in the micro-lattices is parallelized via the arteries 504 which serve as inlet manifolds. This parallelization of the flow in the lattice reduces average fluid velocity for a given flow rate and shortens the flow path. This design obviates a high pressure drop across the small hydraulic diameter features by reducing the fluid velocity with little to no impact on thermal performance. Furthermore, this geometry improves on the performance of microchannel arrays by directing the fluid to impinge on the walls adjacent to the heat source and thus increases heat transfer to the fluid. In this manner, the geometry 500 may be suitable for precise fluid control, fine cooling, and / or dissipating large amounts of heat. In some embodiments, the dimensions of the voids 502 may be no more than 500 micrometers.

[0135] Figure 6A illustrates a tumbling ellipse geometry 600 for internal flow paths. Figure 6B illustrates cross sections of the tumbling ellipse geometry 600. In this configuration, the internal flow paths may be formed using a tessellated structure comprising alternating elliptical voids 602 oriented at differing angles and offsets relative to the flow path. For example, the geometry 600 may comprise a first section with a first vertical ellipse and a second section with a second ellipse that is laterally offset from the center and rotated approximately 90 degrees (and / or other suitable angles) relative to the first ellipse, thus adopting a horizontal orientation. The tumbling pattern of the elliptical voids 602 along the flow path may induce a controlled variation in channel cross-section and flow direction, thus promoting flow mixing and increasing convective heat transfer efficiency.

[0136] In some embodiments, the neighboring fluid paths may be formed from horizontal ellipses that are offset in the opposite direction to maximize volumetric packing density andminimize unused space between paths. In some embodiments, at most 60% of the volume of the metal part may comprise the elliptical voids 602.

[0137] In some embodiments, the minimum size of the offset may be at least the minor axis dimension of the horizontal ellipses. This may ensure that the layers of the workpiece are continuous and self-supporting during LOM without any isolated and / or unstable regions.

[0138] In some embodiments, the ellipse geometry 600 may be adjusted based on the desired properties of the metal part. For example, increasing the offset may create more rapid changes in flow direction, and decreasing the offset may result in more gradual flow transitions. In some examples, larger ellipses may be used near the ports to accommodate greater flow volumes. The ellipses may get progressively smaller downstream through the flow path as flow may be directed to parallel channels.

[0139] Figures 7, 8 and 9 illustrate embodiments of hybrid lattice structures for internal flow paths. The embodiments may be based on triply periodic minimal surface (TPMS) geometries that are adapted for LOM. In conventional TPMS geometries, continuous minimal surfaces produce efficient fluidic networks with excellent surface area-to-volume ratios. However, when used in LOM, conventional gyroidal or Schwarz-diamond structures often suffer from the formation of long, thin, unsupported regions within individual layers. These long and thin regions may compromise the mechanical stability of each layer. The embodiments described herein may be compatible with LOM by using modified hybrid structures.

[0140] Figure 7 illustrates a bimodal diamond TPMS geometry 700. The geometry 700 may exhibit well interconnected cross sections using interwoven minimal surface networks. Figure 8 illustrates a transparent view of the geometry 700 to show flow volume 802 across a continuous flow path 804. Figure 9 illustrates the geometry 700 but with bridging regions 902 at sections that are not sufficiently interconnected for LOM. The bridging regions 902 may allow for enhanced stencil integrity for LOM compatibility.

[0141] In some embodiments, a bimodal diamond TPMS 700 may be designed by first starting with a unit cell with a diamond TPMS structure matching the unit cell. Then the TPMS structure may be mirrored across a line of symmetry 90° relative to the center of the unit cell (Z-axis), and merged to form a lattice structure. The resulting geometry contains several parallel paths traversing one face of the unit cell to the other face of the unit cell. To ensure the flow path is fluidically connected between unit cells, the geometry may be split in half along the XZ plane and mirrored about the same plane to create a tesselatable unit cell of a bimodal diamond TPMS lattice. Thebimodal diamond TPMS lattice may be created by configuring a single void space with multiple unit cells to fill the void space within a part.

[0142] Figure 10A illustrates a bimodal diamond TPMS structure 1000 created with this method. The part region 1002 is mirrored in the XZ plane. The void space 1004 is fluidically connected throughout the unit cell volume. Figure 10B illustrates this fluidically connected void space 1004 without the solid part region present.

[0143] Another modified TPMS for LOM may be designed by re-orienting the cardinal axes of a gyroid unit cell 45 degrees relative to the cardinal axes of the build volume, i.e. its normalvector being [— , — ] as opposed to [1,0,0], [0,1,0], etc. This rotated gyroid creates continuous self-supporting structures of every layer of a LOM. When this geometry is used to design cold plates with heated surfaces in the XY plane, the resulting cold plate has shown superior thermal resistance and pressure drop compared to cold plates fabricated with gyroids oriented in the cardinal directions. Figure 10C presents one such example of a rotated gyroid TPMS unit cell created using nTop.

[0144] Figure 11 A illustrates a geometry 1100 for internal flow paths. Figure 1 IB illustrates cross sections of a geometry 1100. The geometry 1100 may include flow paths that are curved and looped in alternating directions. The geometry 1100 allows for self-supporting stencils and may distribute forces evenly through the looped structures.

[0145] Figure 12A illustrates another geometry 1200 for internal flow paths. Figure 12B illustrates cross sections of another geometry 1200. The geometry 1200 may include serpentine pathways that meander back and forth across the build volume. The continuous curved pattern of the flow paths may facilitate structural support within each layer and enhance mixing of the flowing material to promote heat transfer.

[0146] Figure 13A illustrates a geometry 1300 for internal flow paths. Figure 12B illustrates cross sections of the geometry 1300. The geometry 1300 may include support features 1302 that are incorporated into the flow path. The features 1302 may reinforce the flow paths and ensure that each layer of the part forms a continuous, self-supporting stencil. The features 1302 may promote periodic mixing while minimally disrupting flow. In some embodiments, the features 1302 may be placed at regular intervals along the flow path, such as every 1 to 5 millimeters in smaller channels, or more widely spaced out for larger flow volumes.Microcapillaries

[0147] In embodiments of this invention, the flow paths of a part (e.g., a cold plate) may be formed from a network of microcapillaries arranged between accessible ports. These microcapillaries may be arranged in a similar pattern to the microlattice depicted in Figure 5. The microcapillaries may serve as conduits for heat exchange within the part. The microcapillaries may have at least one characteristic dimension less than 1 mm, such as channel width, channel height, and / or hydraulic diameter. The microcapillaries may have dimensions significantly smaller than other regions of the flow path, such as the manifolds. The microcapillaries may be of uniform or variable length, and may be straight, curved, or contoured, depending on the manufacturing technique employed and the functional requirements of the part. Microcapillary heat exchangers may be monolithic in construction to increase the strength of the fins, enabling taller channels with increased surface area.

[0148] With reference to Figure 15, microcapillary flow structures have arteriole-like feeder channels 1504 that bring the cold inlet fluid directly to the heated surface prior to flowing through the highly convective microcapillaries 1502. The feeder channels may have hydraulic diameters between 1.5 and 10 times larger than the microcapillary hydraulic diameter to promote flow to the heated surface. Because heat transfer is the product of thermal gradient and convection, the arteriole structures in microcapillary lattices can substantially reduce their thermal resistance compared to a microchannel structure of similar characteristic lengths.

[0149] In some embodiments, arterioles may carry flow approximately orthogonally to the direction of flow in a microcapillary to facilitate density of wetted, highly convective surface area near the heated surface.

[0150] In some embodiments, arterioles may be connected to the microcapillary along more than half of the length of the arteriole. The lower flow resistance of the arteriole (due to the higher hydraulic diameter) allows for more even distribution of flow into the microcapillary. If the arteriole is arranged with the microcapillary in this manner, the arteriole may be tapered, reducing in cross-section as it approaches the heated surface to maximize microcapillary surface area near the heated surface.

[0151] In some embodiments, microcapillaries may be arranged in a tessellated two- dimensional pattern relative to a heated surface of a heat exchanger. Figures 14A, 14B, 17, 18, 19, 20 A, and 20B all illustrate possible tessellation patterns. Tessellations may be uniform, but uniformity is not required. The feeder channel and microcapillary length, hydraulic diameter, and density may vary according to the nature and uniformity of the heat load from the heat source. In some embodiments, it may be advantageous to concentrate channels in close proximity to regionswhere more heat is generated, i.e., a localized region on the heat source where the temperature is greater than the average temperature across the heat source.

[0152] In some embodiments, the microcapillaries may be formed by cutting through at least one layer of a laminated object during LOM using a cutting tool, such as laser cutters, wateijet cutters, mills, and / or electrical discharge machining tools. At least one dimension of a microcapillary (e.g., a minimum dimension) may be a kerf width of the cutting tool used, such as a laser beam width. The kerf width may be as small as 10 microns to 250 microns. Wider channels may be created through multiple adjacent cuts or by using broader kerf widths, with the resulting channel dimensions ranging from 10 microns up to 1,000 microns.

[0153] In some embodiments, where the cutting tool penetrates the full thickness of a layer, the height of the resulting microcapillary may correspond to the thickness of the layer. By stacking such sheets, multi-layer channel structures may be created. By stacking varied shapes on adjacent layers, non-planar channels may be created.

[0154] In some embodiments, a channel may have a tapered cross section. For example, in embodiments where laser cutting techniques are used, the tapered cross section may be due to the sheet properties (thickness, laser absorptivity, thermal conductivity, etc.) and laser cutting parameters (e.g., cutting power, cutting speed, focal depth, pulse frequency, pulse duration, etc.). The tapered cross sections, when layered, may result in complex channel geometries such as hourglass geometries, polygonal geometries (e.g., hexagonal), trapezoidal geometries, and / or other sloped wall geometries.

[0155] In some embodiments, the microcapillaries may include varying cross-sectional geometries. For instance, a channel may transition from an elliptical cross-section at the inlet port to a circular or arched cross-section at the outlet port. Alternatively, a channel may decrease in cross-sectional area, i.e. converge, suppressing the thickness of the boundary layer and increasing convective diffusion. The variations may be gradual or segmented and may occur in one or more spatial dimensions. The variations may be achieved through modifications to the cutting parameters in a cutting tool, differential layer stacking in LOM, and / or by incorporating non- uniform deposition or ablation profiles during other additive or subtractive processes.

[0156] In some embodiments, the surface of a layer may be ablated to form shallow microcapillaries. The shallow microcapillaries may have a channel height less than the full thickness of the layer. The microcapillaries may be used to form fluid paths while maintaining material continuity in the layer. The ablation may be performed using any of the cutting toolsdescribed herein and / or using other suitable subtractive techniques. In some embodiments, the shallow microcapillaries may be located near ports and / or manifolds to form shallow inlet or outlet zones.

[0157] In some embodiments, the microcapillaries may be formed with three-dimensional contours that extend across multiple layers of a part (e.g., along the z-axis). The channels may be arbitrarily curved or shaped within a single xy-plane. Such three-dimensional structuring of the flow paths may increase the wetted surface area and promote enhanced fluid mixing, thereby improving thermal performance and uniformity of heat transfer.

[0158] In some embodiments, the channels may be arranged to partially lap with channels on adjacent layers, creating a network with many possible paths for fluids to flow. The interconnection points may also create impingement or secondary flows to increase convective heat transfer.

[0159] In some embodiments, the microcapillaries may include internal features such as pinlike or fin-like obstructions that partially occlude or redirect fluid flow. The obstructions may be formed by selectively leaving bridging elements or segments of material within channels during the manufacturing process. For example, a channel spanning multiple layers may include one or more intermediate layers in which material remains in place to form bridging elements, such as bridging pins. These elements may be staggered across the layers to preserve fluid connectivity. This fin-and-pin configuration may increase the wetted surface area and reduce the wetted volume within the part, thus decreasing the effective hydraulic diameter of the flow path and improving heat transfer.

[0160] In some embodiments, the obstructions may be limited to a single layer of the part and not be mechanically load-bearing. In some embodiments, the density of the obstructions may be between 15% and 85% of the cross-sectional area of a channel. Higher densities may be used for greater improvements in heat transfer, while lower densities may be used to avoid high pressure drop across the channel.

[0161] In some embodiments, the obstructions may have non-uniform or non-cylindrical cross-sectional geometries, such as tapered cones or ellipsoidal shapes. This may further improve heat transfer and / or promote fluid mixing.

[0162] In some embodiments, the manifolds and arterioles may be arranged such that channels carrying colder fluid are adjacent to those carrying warmer fluid. Such configurations may be arranged by alternating flow directions, staggering inlet and outlet manifolds, and / or usinginterweaving channel patterns. Such configurations minimize pressure drop by reducing the distance between the high resistance microcapillaries and the low resistance arterioles and manifolds. Reducing the aforementioned distance also delivers cold inlet fluid uniformly across the part, helping with heat transfer. This may be particularly advantageous in applications requiring low pressure drops or high thermal uniformity.

[0163] In some embodiments, regions that are expected to experience higher thermal loads, such as directly under high-power electronic components, may contain higher densities of microcapillaries. Conversely, regions expected to experience lower thermal loads, may contain lower densities of microcapillaries.

[0164] In some embodiments, the internal surfaces of the microcapillaries may be textured to include patterns such as dimples, nodules, and / or ridges. The patterns may be introduced using chemical etching, sandblasting, laser texturing, laser pulsing, and / or application of deposited materials.

[0165] Figure 14A depicts a heat exchanger 1400 with a flow path between an inlet manifold 1402 and an outlet manifold 1404. The flow path may include microcapillaries 1406 between the two manifolds. The flow path may also include arterioles 1408 to distribute fluid into and out of the microcapillaries. As shown, the microcapillaries 1406 may be arranged in a dense, parallel fashion.

[0166] Figure 14B is a close-up isometric view of the heat exchanger 1400. The microcapillaries 1406 are shown in a fin-and-pin configuration between an inlet arteriole 1408 and an outlet arteriole 1410, which are connected to the inlet manifold 1402 and the outlet manifold 1404 respectively.

[0167] Figure 15 depicts a part 1500 containing a contoured microcapillary 1502. The microcapillary 1502 may be formed from a cut that spans multiple layers of the part along the z- axis. The microcapillary 1502 may follow a sinusoidal or wavy path in the xy -plane. The microcapillary 1502 may define a flow path from an inlet port 1504 to an outlet port 1506.

[0168] Figure 16 depicts cross-sections of various microcapillaries 1600. Each microcapillary 1600 may be contoured in the xy -plane and span multiple layers along the z-axis, such as 6 layers. As shown, the embodiments may include various densities of bridging pins 1602 (e.g., from 0% density to 85% density). Each bridging pin 1602 may be contained within a single layer along the z-axis. The bridging pins 1602 may be arranged in a staggered formation to allow the volume of the microcapillary 1600 to remain fluidically connected.

[0169] Figure 17 depicts an overlay of cutting patterns 1700 for forming a channel network. As shown, the pattern 1700 may include an upper row of teardrop-shaped cutouts corresponding to inlet arterioles 1704, and a lower row of cutouts corresponding to outlet arterioles 1706. The manifolds 1704 and 1706 may be fluidically connected to an array of microcapillaries 1702, as shown by the diamond-shaped pattern. The diamond-shaped pattern may correspond to single kerfwidth cuts to form the microcapillaries 1702. The pattern 1700 may use cross-cuts to remove material from the channels more easily. The inlet manifolds 1704, the outlet manifolds 1706, and the microcapillaries 1702 together may form a dense network of highly parallelized flow paths through the part.

[0170] Figure 18 depicts a high-density channel network 1800 composed of the patterns shown in Figure 17. The network 1800 may include arrays of microcapillaries 1802 formed by repeating a cutting pattern, such as the cutting pattern 1800. Each array may be similar to the array depicted in Figure 4. The network 1800 may include multiple layers of arrays stacked on top of each other (e.g., along the z-axis).

[0171] Figure 19 is an isometric view 1900 of another high-density channel network depicted in figure 18. The network 1900 may include arrays of microcapillaries 1902 stacked on top of each other. The arrays may be fluidically connected to each other across the layers, forming three- dimensional flow paths. The arrays may be formed by repeating a cutting pattern, such as the cutting pattern 1700. As shown, each array may be a mirrored or inverted version of an adjacent array. This configuration may form adjacent flow paths that are offset from each other, thus supporting higher packing densities.

[0172] Figure 20A is a side view of another high-density channel network 2000. The network 2000 may include microcapillaries 2002. The microcapillaries 2002 may be fluidically connected to micro-scale inlet and outlet arterioles 2004, which are depicted by the square block sections. The inlet and outlet manifolds are not depicted for simplicity of visualization. The network may be constructed via LOM by cutting the profile of each microcapillary 2002 into layers and bonding them together as a stack. The fins of the resulting heat exchanger would be composed of uncut regions on a layer.

[0173] Figure 20B is an isometric view of the network 2000. As shown, the microcapillaries 2002 may vary in dimensions (e.g., width) along the network 2000.

[0174] Figure 21 depicts a side view of a flow path configuration 2100 with two arterioles connected via microcapillaries. The inlet manifold 2102 is fluidically connected to a taperedfeeder arteriole 2104. The feeder arteriole is fluidically connected to an array of microcapillaries 2106. The microcapillaries are fluidically connected to an outlet arteriole 2108 which connects to the outlet manifold 2110.

[0175] Figure 22 depicts a side view of another flow path configuration 2200 with two arterioles connected via a network of microcapillaries. The flow path follows the same pattern as described in Figure 21. The shape of the tapered arterioles channels 2202 is altered to improve the stability of layers used in the LOM fabrication process.Equivalents

[0176] The methods, systems, and devices discussed above are examples. Various configurations may omit, substitute, or add various procedures or components as appropriate. For instance, in alternative configurations, the methods may be performed in an order different from that described, and that various steps may be added, omitted, or combined. Also, features described with respect to certain configurations may be combined in various other configurations. Different aspects and elements of the configurations may be combined in a similar manner. Also, technology evolves and, thus, many of the elements are examples and do not limit the scope of the disclosure or claims.

[0177] Embodiments of the present disclosure, for example, are described above with reference to block diagrams and / or operational illustrations of methods, systems, and computer program products according to embodiments of the present disclosure. The functions / acts noted in the blocks may occur out of the order as shown in any flowchart. For example, two blocks shown in succession may in fact be executed substantially concurrent or the blocks may sometimes be executed in the reverse order, depending upon the functionality / acts involved. Additionally, or alternatively, not all of the blocks shown in any flowchart need to be performed and / or executed. For example, if a given flowchart has five blocks containing functions / acts, it may be the case that only three of the five blocks are performed and / or executed. In this example, any of the three of the five blocks may be performed and / or executed.

[0178] A statement that a value exceeds (or is more than) a first threshold value is equivalent to a statement that the value meets or exceeds a second threshold value that is slightly greater than the first threshold value, e.g., the second threshold value being one value higher than the first threshold value in the resolution of a relevant system. A statement that a value is less than (or is within) a first threshold value is equivalent to a statement that the value is less than or equal to a second threshold value that is slightly lower than the first threshold value, e.g., the secondthreshold value being one value lower than the first threshold value in the resolution of the relevant system.

[0179] Specific details are given in the description to provide a thorough understanding of example configurations (including implementations). However, configurations may be practiced without these specific details. This description provides example configurations only, and does not limit the scope, applicability, or configurations of the claims. Rather, the preceding description of the configurations will provide those skilled in the art with an enabling description for implementing described techniques. Various changes may be made in the function and arrangement of elements without departing from the spirit or scope of the disclosure.

[0180] Having described several example configurations, various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the disclosure. For example, the above elements may be components of a larger system, wherein other rules may take precedence over or otherwise modify the application of various implementations or techniques of the present disclosure. Also, a number of steps may be undertaken before, during, or after the above elements are considered.

Claims

CLAIMSWhat is claimed is:

1. A method to produce a heat exchanger via laminated object manufacturing, the method comprising: patterning a plurality of metal sheets so that at least one metal sheet contains at least one void space of a plurality of void spaces, each metal sheet comprising a self-supporting layer; assembling the plurality of metal sheets so that the plurality of void spaces forms at least one channel; and bonding the plurality of assembled metal sheets to form a heat exchanger with at least one flow path formed from the at least one channel, the heat exchanger having a geometry that is continuously self-supporting through each assembled metal sheet.

2. The method of claim 1 wherein the geometry comprises a plurality of peanut-shaped volumes.

3. The method of claim 2 wherein the peanut-shaped volumes are tessellated at an angle from each other and offset in at least two layers.

4. The method of claim 1 wherein the geometry comprises at least one of an ellipsoid geometry, a double-ellipsoid geometry, or a Cassini geometry.

5. The method of claim 1 wherein the at least one flow path is fluidically connected in three dimensions.

6. The method of claim 1 wherein the geometry comprises a tessellated structure of ellipses alternating in orientation.

7. The method of claim 1 wherein the geometry comprises neighboring flow paths having ellipses offset in the opposite direction.

8. The method of claim 1 wherein the geometry comprises a triply periodic minimal surface structure.

9. The method of claim 1 wherein the geometry is arranged in at least one of a spiral configuration, an S-configuration, or a periodic mixing configuration.

10. The method of claim 1 wherein at least one metal sheet contains a plurality of void spaces that form the same channel.

11. The method of claim 1 wherein at least one metal sheet comprises a feature with a resolution less than 500 microns.

12. The method of claim 1 wherein the geometry is arranged to optimize packing density within the heat exchanger.

13. A heat exchanger comprising: a bonded plurality of metal sheets, at least one metal sheet containing at least one void space of a plurality of void spaces, each metal sheet comprising a self-supporting layer, wherein the plurality of void spaces forms at least one channel, and wherein the heat exchanger has a geometry that is continuously self-supporting through each metal sheet.

14. The heat exchanger of claim 13 wherein the geometry comprises a plurality of peanutshaped volumes.

15. The heat exchanger of claim 13 wherein the geometry comprises at least one of an ellipsoid geometry, a double-ellipsoid geometry, or a Cassini geometry.

16. The heat exchanger of claim 13 wherein the at least one channel is fluidically connected in three dimensions.

17. The heat exchanger of claim 13 wherein the geometry comprises a tessellated structure of ellipses alternating in orientation.

18. The heat exchanger of claim 13 wherein the geometry comprises neighboring channels having ellipses offset in the opposite direction.

19. The heat exchanger of claim 13 wherein the geometry comprises a triply periodic minimal surface structure.

20. A heat exchanger formed via a laminated object manufacturing process, the process comprising: patterning a plurality of metal sheets so that at least one metal sheet contains at least one void space of a plurality of void spaces, each metal sheet comprising a self-supporting layer; assembling the plurality of metal sheets so that the plurality of void spaces forms at least one channel; and bonding the plurality of assembled metal sheets to form the heat exchanger with at least one flow path formed from the at least one channel, the heat exchanger having a geometry that is continuously self-supporting through each assembled metal sheet.

21. A heat exchanger comprising: at least one inlet manifold; at least one outlet manifold; and a plurality of microcapillaries fluidically connected to the at least one inlet manifold and the at least one outlet manifold to define at least one flow path through the heat exchanger.

22. The heat exchanger of claim 21 wherein the heat exchanger is formed via at least one of diffusion bonding, electroplating, electrodeposition, or etching.

23. The heat exchanger of claim 21 wherein the heat exchanger is formed from a plurality of metal sheets via laminated object manufacturing.

24. The heat exchanger of claim 23 wherein the plurality of microcapillaries is formed via a cut through at least one metal sheet using a cutting tool.

25. The heat exchanger of claim 24 wherein a dimension of the cut is a single kerf cutting width of the cutting tool.

26. The heat exchanger of claim 23 wherein the height of at least one microcapillary is the thickness of a metal sheet forming the at least one microcapillary.

27. The heat exchanger of claim 21 wherein at least one of the cross-sectional dimensions of at least one microcapillary are less than 1 mm.

28. The heat exchanger of claim 21 wherein at least one of the cross-sectional height and width of at least one microcapillary are between 10 and 1000 microns.

29. The heat exchanger of claim 21 wherein at least one microcapillary is contoured in three dimensions.

30. The heat exchanger of claim 21 wherein at least one microcapillary is formed using pinlike or fin-like obstructions that at least partially obstruct the flow within the microcapillary.

31. The heat exchanger of claim 21 wherein the plurality of microcapillaries is spatially arranged such that regions of the microcapillaries with colder fluid are near regions of the microcapillaries with warmer fluid while the heat exchanger transfers heat.

32. The heat exchanger of claim 21 where the plurality of microcapillaries comprises at least 1000 microcapillaries arranged in a parallel fashion.

33. The heat exchanger of claim 21 wherein the at least one inlet manifold and the at least one outlet manifold are on different faces of the heat exchanger.

34. A method to produce a heat exchanger via laminated object manufacturing, the method comprising: assembling a plurality of patterned metal sheets; and bonding the plurality of assembled metal sheets to form the heat exchanger, the heat exchanger comprising at least one inlet manifold, at least one outlet manifold, and a plurality of microcapillaries fluidically connected to the at least one inlet manifold and the at least one outlet manifold to define at least one flow path through the heat exchanger.

35. The method of claim 34 further comprising forming a cut through at least one metal sheet to form the plurality of microcapillaries using a cutting tool prior to the assembly of the plurality of patterned metal sheets.

36. The method of claim 35 wherein a dimension of the cut is a single kerf cutting width of the cutting tool.

37. The method of claim 34 wherein the height of at least one microcapillary is the thickness of a metal sheet forming the at least one microcapillary.

38. The method of claim 34 wherein at least one of the cross-sectional height and width of at least one microcapillary are between 10 and 1000 microns.

39. A system for manufacturing a laminated object heat exchanger, the system comprising: a laminated object manufacturing device configured to assemble a plurality of patterned metal sheets; and a pressor configured to bond the plurality of assembled metal sheets to form the heat exchanger, the heat exchanger comprising at least one inlet manifold, at least one outlet manifold, and a plurality of microcapillaries fluidically connected to the at least one inlet manifold and the at least one outlet manifold to define at least one flow path through the heat exchanger.

40. The system of claim 39 further comprising a cutting tool configured to form a cut through at least one metal sheet to form the plurality of microcapillaries prior to the assembly of the plurality of patterned metal sheets.

41. A heat exchanger comprising: an array of microcapillary fluid channels disposed in a tessellated pattern along a heated surface, each channel being between 10 pm and 1000 pm in width; an array of arterioles configured to convey fluid towards the regions of the microcapillary fluid channel array closest to the heated surface, wherein the hydraulic diameters of the arterioles are greater than the hydraulic diameters of the microcapillaries, and wherein the primary direction of flow in the arterioles is approximately orthogonal to the primary direction of flow in the microcapillaries.

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