Compact heat exchangers for gas purification heat recovery systems

Abstract

A heat exchanger includes an enclosure with distinct inlets and outlets for hot and cold fluids. The enclosure also houses a heat exchanger core, which includes a partition defining sets, of hot and cold fluid channels. This partition features a common boundary between a cold fluid channel and a hot fluid channel facilitating heat exchange between the hot and cold fluids. The partition is designed such that at least some cold fluid channels exhibit variations in the common boundary's area per unit length along their extensions. These changes are designed to promote a predetermined and optimized heat exchange between the cold and hot fluids, increasing heat exchanger's efficiency and offering enhanced thermal performance in a compact and well-structured configuration.

Description

COMPACT HEAT EXCHANGERS FOR GAS PURIFICATION HEAT RECOVERYSYSTEMSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This Application claims the benefit of and priority to United States Provisional Application No. 63 / 670,438, filed on July 12, 2024, the contents of which are incorporated herein by reference in their entirety for all purposes.TECHNICAL FIELD

[0002] This disclosure relates to compact heat exchangers and more particularly to compact heat exchangers for gas purification heat recovery systems that can be manufactured using additive manufacturing processes.BACKGROUND

[0003] Compact heat exchangers have emerged as important components in the field of gas purification, addressing the need for efficient thermal management and space optimization within purification processes. The utilization of compact heat exchangers is particularly advantageous in applications where spatial constraints and thermal efficiency are important considerations. Compact heat exchangers are designed to maximize the surface area available for heat transfer while minimizing the overall size and weight of the heat exchangers.

[0004] In the context of gas purification, compact heat exchangers are commonly used to enhance the efficiency of thermal processes. For example, in gas purification processes, where precise temperature control and thermal efficiency are crucial, compact heat exchangers play a pivotal role. These heat exchangers are instrumental in optimizing temperature profiles during adsorption, desorption, and various chemical reactions integral to gas purification.

[0005] Compact heat exchangers can employ innovative designs such as plate-fin, printed circuit, and microchannel configurations to enhance heat transfer efficiency. The compact nature of these designs facilitates a significant increase in surface area for heat exchange within a confined volume, ensuring effective thermal regulation. The compact heat exchangers employ cold and hot fluid channels, which are the pathways through which the fluids, typically gases, flow for thepurpose of a heat exchange. These channels play a crucial role in facilitating the efficient transfer of heat between the two fluid streams. The cold channel in a compact heat exchanger is the pathway through which the cold fluid travels. This fluid, also often referred to as the “working fluid.” As the cold fluid flows through the cold channel, it exchanges heat with the hot fluid. The cold fluid absorbs heat from the hot fluid, leading to a temperature reduction of the hot fluid. The hot channel in a compact heat exchanger is the pathway through which the hot fluid travels.

[0006] In some compact heat exchanger configurations, the cold and hot fluid channels may be arranged in either counterflow or parallel flow patterns. In counterflow, the fluids flow in opposite directions, maximizing the temperature difference across the length of the heat exchanger. In parallel flow, the fluids move in the same direction, and heat transfer occurs along the length of the channels.SUMMARY[00071 Embodiments described herein relate to a compact heat exchanger, as well as a gas purification system including a compact heat exchanger.

[0008] According to some embodiments of the disclosure, a heat exchanger includes an enclosure with a hot inlet for inflow of a hot fluid, a hot outlet for outflow of the hot fluid, a cold inlet for inflow of a cold fluid, and a cold outlet for outflow of the cold fluid. The heat exchanger also includes a heat exchanger core with a plurality of partitions forming a set of hot fluid channels and a set of cold fluid channels. Each of the partitions is defined by a wall common to adjacent hot and cold fluid channels, with the wall defining a continuous, thermally conductive boundary between the channels to facilitate heat exchange. The partitions and channels define a three- dimensional lattice structure with multiple cells having a Y:X aspect ratio.

[0009] Some embodiments of the disclosure relate a gas purification system comprising a feed gas inlet, a purified gas outlet, a heater, a purifier, and at least one heat exchanger. The heat exchanger can include a heat exchanger core with a plurality of partitions forming a set of hot fluid channels and a set of cold fluid channels. Each of the partitions is defined by a wall common to adjacent hot and cold fluid channels, with the wall defining a continuous, thermally conductive boundary between the channels to facilitate heat exchange. The partitions and channels define a three-dimensional lattice structure with multiple cells having a Y:X aspect ratio. In some embodiments, a gas purification can include two or more heat exchangers, as described hereinaccording to the various embodiments, where the heat exchangers are arranged in series or in parallel.

[0010] Additional embodiments of the disclosure relate to a method of manufacturing a heat exchanger comprising forming an enclosure and a heat exchanger core by an additive manufacturing process. The heat exchanger core includes a plurality of partitions forming sets of hot and cold fluid channels, where each partition is defined by a wall common to adjacent hot and cold fluid channels. The wall defines a continuous, thermally conductive boundary. The partitions and sets of hot and cold fluid channels define a three-dimensional lattice structure having multiple cells with a Y:X aspect ratio. The aspect ratio of the multiple cells in at least one region of the heat exchanger core is controlled during the additive manufacturing process to achieve a predetermined pressure drop for at least one of a hot fluid outlet or a cold fluid outlet of the heat exchanger.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] References are made to the accompanying drawings that form a part of this disclosure, and which illustrate embodiments in which the embodiments described in this specification can be practiced.

[0012] FIG. 1: A schematic block diagram of a heat exchanger (100) with a core (120) housed within a shell (105) and featuring inlets and outlets.

[0013] FIG. 2A: Illustrates a counter-flow heat exchanger with a corresponding graph showing the change in temperature difference (AT) and channel area (A_CH) along the flow path.

[0014] FIG. 2B: Depicts a cross-flow arrangement of two fluid channels (232, 237).

[0015] FIG. 2C: Depicts an angled-flow arrangement between two fluid channels (232, 237).

[0016] FIG. 3A: A perspective view of a first type of uniform lattice structure (320A).

[0017] FIG. 3B: A perspective view of a second type of uniform lattice structure (333A), indicating hot (dH) and cold (dC) channel diameters.

[0018] FIG. 3C: A perspective view of another uniform lattice structure (320B).

[0019] FIG. 3D: A perspective view of yet another uniform lattice structure (333B), indicating hot (dH) and cold (dC) channel diameters.

[0020] FIG. 3E: A perspective view of a uniform lattice structure (320C).

[0021] FIG. 3F: A perspective view of a uniform lattice structure (333C) with indicated hot (dH) and cold (dC) channel diameters.

[0022] FIG. 4A: A cross-sectional view of a heat exchanger channel (400) having a 1 : 1 aspect ratio.

[0023] FIG. 4B: A cross-sectional view of a heat exchanger channel (401) having a 2:1 aspect ratio.

[0024] FIG. 4C: Illustrates four variations of a lattice structure, each with a different ratio of its Y dimension to its X dimension (1:1, 2:1, 3:1, 4:1).

[0025] FIG. 4D: Displays a cross-section of a structure (420) with a functionally graded lattice, featuring different lattice structures in its central (426) and outer (424A, 424B) regions.

[0026] FIG. 4E: A bar chart comparing the pressure drop for hot and cold fluids in two different heat exchanger concepts to show the effect of aspect ratio.

[0027] FIG. 5: A schematic block diagram of a multi-stream heat exchanger (500) having a core (520) with two distinct heat exchange regions (521, 523).

[0028] FIG. 6: A perspective schematic of the heat exchanger core (520) from FIG. 5, illustrating two distinct regions of heat exchange with different thermal -hydraulic properties.

[0029] FIG. 7A is a perspective view of a shell-and-tube type heat exchanger (700A).

[0030] FIG. 7B is a cutaway view of the heat exchanger (700A), revealing its internal lattice structure.

[0031] FIG. 7C provides perspective and cutaway views of a compact, U-bend heat exchanger (700B) with an internal lattice structure.

[0032] FIG. 7D illustrates the fluid flow path and a cross-sectional view of the U-bend heat exchanger (700B).

[0033] FIG. 7E is a perspective view of a multi-lobed, compact heat exchanger (700C).

[0034] FIG. 7F is a cross-sectional view of the heat exchanger (700C), showing its three distinct internal flow regions filled with lattice structures.

[0035] FIG. 7G is a side view of a multi-stream heat exchanger (700D) with a central core and two external channels.

[0036] FIG. 7H is a cross-sectional view of the heat exchanger (700D), showing the lattice structures within its different flow paths.

[0037] FIG. 71 is a perspective view of a tube-in-tube heat exchanger (700E).

[0038] FIG. 7J is a cross-sectional view of the heat exchanger (700E), revealing a lattice structure within its inner flow path.

[0039] FIGS. 8A and 8B are graphs showing the comparative outlet temperatures and pressure drops for the heat exchangers shown in FIGS. 7A-7F, in accordance with disclosed embodiments.

[0040] FIGS. 9 A and 9B show periodic lattice structures representing hot and cold fluid channels of a heat exchanger having different volume fractions for the cold fluid channels and the hot fluid channels, in accordance with disclosed embodiments.

[0041] FIG. 9C is a graph comparing cold and hot outlet temperatures for periodic lattice structures representing hot and cold fluid channels of a heat exchanger having different volume fractions for cold fluid channels and hot fluid channels, in accordance with disclosed embodiments.

[0042] FIG. 10 is an exemplary channel having branches, in accordance with disclosed embodiments.

[0043] FIG. 11 is an exemplary heat exchanger with at least some cold fluid channels having branches, in accordance with disclosed embodiments.

[0044] FIG. 12 is an exemplary fluid channel with multiple branches, in accordance with disclosed embodiments.

[0045] FIGS 13A and 13B show an exemplary fluid channel having branches with a variable cross-section, in accordance with disclosed embodiments.

[0046] FIGS. 14A and 14B show an exemplary heat exchanger with a cold fluid inflow manifold being part of a heat exchanger core of the heat exchanger, in accordance with disclosed embodiments.

[0047] FIGS. 15 A and 15B show that inclusion of manifold sections can be used for temperature control at the inflow / outflow, in accordance with disclosed embodiments.

[0048] FIGS. 15C and 15D show examples of heat exchangers with a plurality of partitions defining cold fluid channels having a variable aspect ratio and geometry, in accordance with disclosed embodiments.

[0049] FIG. 16 is a schematic block diagram of a gas purification system including a heat exchanger in accordance with embodiments of the disclosure.

[0050] While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit aspects of the disclosure to the particular illustrative embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.DETAILED DESCRIPTION

[0051] In the following description, for the purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the present disclosure. It will be apparent, however, that embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known structures and devices are shown in schematic form to avoid unnecessarily obscuring the description of the present disclosure.

[0052] The text in conjunction with the accompanying drawings aims to articulate the designs and methods at a level of detail consistent with the communication standards among skilled individuals in the relevant arts. This level of detail mirrors the customary communication among those with expertise in the field, effectively expressing the structure and function of the various designs outlined in this disclosure.

[0053] Various embodiments may be described in this disclosure to illustrate various aspects. Other embodiments may be utilized and structural, logical, software, and other changes may be made without departing from the scope of the embodiments that are specifically described. Various modifications and alterations are possible and expected. Some features may be described with reference to one or more embodiments or drawing figures, but such features are not limited to usage in the one or more embodiments or figures with reference to which they are described. Thus, the present disclosure is neither a literal description of all embodiments nor a listing of features that must be present in all embodiments.

[0054] Headings of sections and the title are provided for convenience but are not intended as limiting the disclosure in any way or as a basis for interpreting the claims.

[0055] A description of an embodiment with several components present does not necessary imply that all such components are required. Optional components may be described to illustrate a variety of possible embodiments and to illustrate one or more aspects of the present disclosure more fully. Similarly, although process steps, method steps, algorithms, or the like may be described in sequential order, such processes, methods, and algorithms may generally be configured to work in different orders, unless specifically stated to the contrary. Any sequence or order of steps described in this disclosure is not a required sequence or order. The steps of the described processes may be performed in any order practical. Further, some steps may be performed simultaneously. The illustration of a process in a drawing does not exclude variationsand modifications, does not imply that the process or any of its steps are necessary, and does not imply that the illustrated process is preferred. The steps may be described once per embodiment but need not occur only once. Some steps may be omitted in some embodiments or some occurrences, or some steps may be executed more than once in each embodiment or occurrence. When a single device or article is described, more than one device or article may be used in place of a single device or article. Where more than one device or article is described, a single device or article may be used in place of more than one device or article.

[0056] The functionality or features of a device may be alternatively embodied by one or more other devices that are not explicitly described as having such functionality or features. Thus, other embodiments need not include the device itself. Techniques and mechanisms described or referenced herein will sometimes be described in singular form for clarity. However, it should be noted that embodiments include multiple iterations of a technique or multiple manifestations of a mechanism unless noted otherwise.

[0057] In various embodiments of the disclosure, terms such as “approximate,” “about,” “similar,” “equal,” “equivalent” or “the same as” are used to indicate a degree of flexibility or tolerance in numerical values, measurements, and characteristics disclosed. The scope of the disclosure should not be limited to strict numerical precision, and these terms are employed to allow for variations within acceptable limits.

[0058] The terms “approximate,” “about,” and “similar” are used interchangeably to convey that a given value, parameter, or characteristic may deviate within a reasonable range from the stated value. This range may encompass slight variations that do not materially affect the functionality or performance of the systems and methods described in this disclosure. For example, the terms “approximate,” “about,” and “similar” may refer to a variation of ten percent from a specific value.

[0059] The terms “equal,” “equivalent,” or “the same as” is used to indicate that values, parameters, or characteristics described as such are substantially identical or sufficiently close in magnitude, without necessarily requiring absolute precision. For example, such terms may be referred to a deviation of a few percent from a specific value such as one or two percent.

[0060] Further, the term “similar” may be employed to denote a likeness or resemblance between two or more elements, aspects, or features, allowing for variations that do not compromise the fundamental nature or purpose of the disclosure.

[0061] In various embodiments of the disclosure, the term "set" is employed to denote a grouping or collection of objects, elements, components, or entities. The flexibility in the interpretation of the term “set” allows for adaptability and practical application in situations where a singular object satisfies the intended functionality or purpose of the disclosure. Thus, the disclosure is not limited to instances where a “set” must consist of multiple objects but rather contemplates scenarios where a “set” may include one object.

[0062] This disclosure relates to compact heat exchangers and more particularly to compact heat exchangers for gas purification heat recovery systems using additive manufacturing.

[0063] When implementing compact heat exchangers in gas purification, several issues need careful consideration such as pressure drop, thermal stress, material compatibility, manufacturing complexity, and cost considerations. For example, the compact design of a heat exchanger may lead to higher pressure drops, potentially affecting gas flow efficiency, particularly in microchannel configurations. Also, the surface area through which the heat is exchanged between cold and hot fluid channels of a compact heat exchanger can result in uneven temperature distribution, leading to thermal stresses which can adversely affect the performance and lifetime of the compact heat exchanger. Further, intricate designs of compact heat exchangers may pose challenges in fabrication, requiring specialized manufacturing techniques and potentially impacting production costs.

[0064] The present disclosure addresses various challenges of manufacturing compact heat exchangers, including the ability to create complex geometries, customize designs, optimize internal structures, reduce material waste, enable rapid prototyping, support diverse material selection, integrate components seamlessly, and achieve weight reduction. These advantages collectively contribute to the enhanced performance and versatility of compact heat exchangers in various applications.

[0065] These challenges can be addressed with improved designs for a heat exchanger. In some embodiments, the compact heat exchangers are produced using a three-dimensional (3D) manufacturing, also known as additive manufacturing or 3D printing. Such manufacturing technique offers several advantages for the compact heat exchangers as it can allow for complex geometries, customizable internal structure, and rapid prototyping of the compact heat exchangers. Further, 3D printing can lead to reduced material waste when manufacturing compact heat exchangers.

[0066] The compact heat exchangers can be digitally printed using a suitable digital 3D model of the heat exchanger designed using a Computer-Aided Design (CAD) software. Such digital (CAD) model can define the intricate geometry and an internal structure of a compact heat exchanger. The 3D printing device interprets the CAD model and builds the physical object layer by layer. Such layer-by-layer additive process allows for the creation of complex geometries that may be challenging or impossible with traditional manufacturing methods. For 3D printing any suitable approach can be used. For example, a metal 3D printing may be used and can include laser power bed fusion (LPBF) or direct metal laser sintering (DMLS). Using LPBF and DMLS 3D printing methods, compact heat exchangers can be produced from a large range of metals and metal alloys including aluminum, copper, stainless steel, titanium, cobalt chrome, nickelchromium-based alloys such as, for example, INCONEL® (INCONEL® is a registered trademark of Huntington Alloys Corporation), and the like. In one embodiment, compact heat exchangers, as described herein are formed from stainless steel.

[0067] In other embodiments, the compact heat exchangers may be manufactured using any other suitable approaches besides 3D manufacturing. For example, the compact heat exchangers can be manufactured using a combination of traditional and advanced manufacturing approaches such as metal fabrication that includes welding, brazing, soldering, molding, casting, rolling, or extruding. Further, laser cutting, and laser welding may be employed for creating suitable shapes, geometries, or structures. In some cases, hydroforming can be used, that utilizes fluid pressure to shape metal into complex structures. Additionally, hybrid approaches may be used such as traditional methods in combination with 3D printing to manufacture compact heat exchangers.

[0068] In an example embodiment, a heat exchanger includes an enclosure. The enclosure includes a hot inlet for inflow of a hot fluid and a hot outlet for outflow of the hot fluid. Further the enclosure includes a cold inlet for inflow of a cold fluid and a cold outlet for outflow of the cold fluid. Additionally, the heat exchanger includes a heat exchanger core that, in turn, includes at least one partition and, in some cases a plurality of partitions, defining a set of hot fluid channels and a set of cold fluid channels. The partition(s) further includes at least one wall common to both the hot and the cold fluid channels. Such a common wall is configured to facilitate a heat exchange between the hot fluid and the cold fluid flowing within adjacent hot and cold fluid channels, and herein is referred to as continuous, thermally conductive boundary.

[0069] An illustrative embodiment of a heat exchanger 100 is shown in FTG. 1. The heat exchanger 100 includes a cold inlet 110 and a cold outlet 114. The cold inlet 110 is configured to deliver the cold fluid to the heat exchanger 100. More particularly, the cold inlet 110 is fluidly connected to a heat exchanger core 120, which includes a partition defining a set of cold fluid channels 122 and a set of hot fluid channels 124. Specifically, the cold inlet 110 is fluidly connected to the set of cold fluid channels 122. In some cases, the cold inlet 110 may be connected to a single cold fluid channel from the set of cold fluid channels 122, and that cold fluid channel may then be connected to several other cold fluid channels (e.g., to two, three, four, five, six, and the like fluid channels). In some cases, a single cold fluid channel can be connected to a large number of other cold fluid channels, such as ten or more cold fluid channels. In some cases, the single cold fluid channel may be connected to ten, twenty, thirty, forty, fifty or more cold fluid channels). In some other implementations, the cold inlet 110 may be connected to multiple cold fluid channels. For example, the cold inlet 110 may be connected to one, two, three, four, five, six, and the like fluid channels). In some cases, the cold inlet 110 may be connected to a large number of cold fluid channels, such as ten or more cold fluid channels.

[0070] In various implementations, the cold inlet 110 is configured to inflow cold fluid into the heat exchanger 100. The cold fluid can be any appropriate gas chosen for heat exchange. This may encompass, by way of illustration but not limitation, gases such as air, carbon dioxide (CO2), ammonia, hydrogen, helium, argon, fluorocarbon gases, natural gas, nitrogen, propane, butane, or inert gases like krypton or xenon. In some implementations, the inflow cold fluid may be a liquid such as water, oil-based fluids (e.g., a thermal oil), glycol-water mixtures, refrigerants, coolants, liquid metals, brines, or hydraulic fluids.

[0071] The cold inlet 110 may have any suitable shape and size. In some cases, the cross- sectional area of the cold inlet 110 can be different than a combined cross-sectional area of the cold fluid channels with which the cold inlet 110 is connecting. For example, in some implementations such a difference in cross-sectional area may allow for temperature control of the cold fluid at the inflow, as further explained below in reference to FIGS 15A and 15B.

[0072] The cold outlet 114 is configured to outflow the cold fluid. The cold outlet 114 is fluidly connected to the set of cold fluid channels such that there is a continuous flow from the cold inlet 110, the set of cold fluid channels 122 and the cold outlet 114. In various implementations, as the cold fluid passes through the heat exchanger core 120 (e.g., when the cold fluid passes through thecold fluid channels), it is configured to heat up due to the heat exchange with a hot fluid flown in hot fluid channels.

[0073] The cold outlet 114 may have any suitable shape and size. In some cases, the cross- sectional area of the cold outlet 114 can be different than a combined cross-sectional area of the cold fluid channels with which the cold outlet 114 is connecting. For example, in some implementations such a difference in cross-sectional area may allow for temperature control of the cold fluid at the outflow, as further explained below in reference to FIGS 15A and 15B.

[0074] Further, the heat exchanger 100 includes a hot inlet 112 and a hot outlet 116. The hot inlet 112 is configured to deliver the hot fluid to the heat exchanger 100. More particularly, the hot inlet 112 is fluidly connected to a heat exchanger core 120, and specifically, the hot inlet 112 is fluidly connected to the set of hot fluid channels 124. In some cases, the hot inlet 112 may be connected to a single hot fluid channel from the set of hot fluid channels 124, and that hot fluid channel may then be connected to several other hot fluid channels (e.g., to two, three, four, five, six, and the like fluid channels). In some cases, a single hot fluid channel can be connected to a large number of other hot fluid channels, such as ten or more cold fluid channels. In some cases, the single hot fluid channel may be connected to ten, twenty, thirty, forty, fifty or more hot fluid channels). In some other implementations, the hot inlet 110 may be connected to multiple hot fluid channels. For example, the hot inlet 112 may be connected to one, two, three, four, five, six, and the like fluid channels). In some cases, the cold inlet 110 may be connected to a large number of hot fluid channels, such as ten or more hot fluid channels.

[0075] In various implementations, the hot inlet 112 is configured to inflow hot fluid into the heat exchanger 100. The hot fluid can be any appropriate gas chosen for heat exchange. This may encompass, by way of illustration but not limitation, gases such as air, steam, carbon dioxide (CO2), ammonia, hydrogen, helium, argon, fluorocarbon gases, natural gas, nitrogen, propane, butane, or inert gases like krypton or xenon. In some implementations, the inflow hot fluid may be a liquid such as water, oil-based fluids (e.g., a thermal oil), glycol- water mixtures, refrigerants, coolants, liquid metals, brines, or hydraulic fluids.

[0076] The hot inlet 112 may have any suitable shape and size. In some cases, the cross- sectional area of the hot inlet 112 can be different than a combined cross-sectional area of the hot fluid channels with which the hot inlet 112 is connecting. For example, in some implementationssuch a difference in cross-sectional area may allow for temperature control of the hot fluid at the inflow, as further explained below in reference to FIGS 15A and 15B.

[0077] The hot outlet 116 is configured to outflow the hot fluid. The hot outlet 114 is fluidly connected to the set of hot fluid channels 124 such that there is a continuous flow from the hot inlet 112, the set of hot fluid channels 124 and the hot outlet 116. In various implementations as the hot fluid passes through the heat exchanger core 120 (e.g., when the hot fluid passes through the hot fluid channels), it is configured to cool off due to the heat exchange with a cold fluid flown in cold fluid channels 122.

[0078] The hot outlet 116 may have any suitable shape and size. In some cases, the cross- sectional area of the hot outlet 116 can be different than a combined cross-sectional area of the hot fluid channels 124 with which the hot outlet 116 is connecting. For example, in some implementations such a difference in cross-sectional area may allow for temperature control of the hot fluid at the outflow, as further explained below in reference to FIGS 15A and 15B.

[0079] The heat exchanger 100 includes the heat exchanger core 120 that facilitates heat exchange between the set of hot fluid channels 124 and the set of cold fluid channels 122 within the heat exchanger core 120. In some implementations, the heat exchanger core 120 is manufactured using 3D printing.

[0080] The hot fluid channels 124 are configured to be separated from the cold fluid channels 122 by one or more continuous, thermally conductive boundaries that are configured to conduct heat from the hot fluid flown in the hot fluid channels 124 towards the cold fluid flown in the cold fluid channels 122. In some implementations, each hot fluid channel of the set of hot fluid channels 124 includes a continuous wall being a continuous, thermally conductive boundary surrounding the hot fluid flown within the individual hot fluid channel. While such continuous, thermally conductive boundary is wetted at a first side (the first side being internal side of the hot fluid channel) by the hot fluid flown in the hot fluid channel, it is also configured to be wetted at a second side (the second side being external side of the hot fluid channel) by the cold fluid flown within one or more cold fluid channels 122 adjacent to the one or more hot fluid channels 124. In some implementations, the wall defining the continuous, thermally conductive boundary is separates the cold fluid from the hot fluid through a large portion of a heat exchanger core. In some cases, this separation extends along a length of the heat exchanger core, maximizing heat transfer efficiency.

[0081] FIG. 2A shows is a high-level, schematic representation of a cold fluid channel 231 and a hot fluid channel 233 separated by a continuous, thermally conductive boundary 232 (also referred to as boundary 232 for brevity). In some implementations, over at least some extension of the boundary 232, the cold fluid may be flown in an opposite direction to the hot fluid as indicated by cold fluid velocity vector Vcand a hot fluid velocity vector VH. Alternatively, in some implementations, the cold fluid velocity vector may be directed in the same direction as the hot fluid velocity vector over at least some portion of the boundary 232. In some implementations, as shown, for example, in FIGS. 2B and 2C, the cold fluid channel 235 and the hot fluid channels 237 may be oriented in any suitable way relative to each other resulting in a direction of the cold fluid velocity vector Vcbeing at any suitable angle with respect to the hot fluid velocity vector VH, over a portion of the boundary 232. FIGS. 2B and 2C shows cold fluid channels 235 and hot fluid channels 237 oriented in a few possible ways with respect to each other. For example, cold fluid channels 235 may extend vertically, as shown in FIG. 2B and hot fluid channels 237 may extend in-and-out of a horizontal plane. In FIG. 2C the cold fluid channels 235 extend at an angle 0 relative hot fluid channels 237, over a portion of the boundary separating the cold fluid channels 235 and the hot fluid channels 237. It should be noted that a cold fluid channel can be adjacent to multiple hot fluid channels over the extension of the cold fluid channel and separated by a continuous thermally conductive boundary from these hot fluid channels. Similarly, a hot fluid channel can be adjacent to multiple cold fluid channels over the extension of the hot fluid channel and separated by a continuous thermally conductive boundary from these cold fluid channels.

[0082] In various embodiments, the fluid velocity within both hot and cold fluid channels is dynamically influenced by their respective cross-sectional areas. This is achieved through the implementation of variable cross-sections along the extension of these channels. By adjusting a channel cross-sectional area, fluid velocity can be precisely controlled to optimize heat transfer and fluid dynamics within the channel.

[0083] In various embodiments, the wall defining the continuous, thermally conductive boundary may be configured to conduct heat but prevent the transfer of fluids between cold fluid channels and hot fluid channels. Such a wall may be manufactured from any suitable heat conductive material such as a metal, which can include, aluminum, stainless steel, titanium, cobalt chrome, INCONEL, copper, and the like. In some cases, thermally conductive plastics can be used, such as graphite filled plastics, metal-plastic composite materials, thermally conductivepolyimides, thermally conductive elastomers, or any other suitable thermally conductive materials (c.g., materials that include diamond powder, such as diamond composites). The wall defining the continuous, thermally conductive boundary may be further coated with suitable thermally conductive films to allow for increase in lateral thermal conductivity along the conductive boundary. In various embodiments, the walls forming the continuous thermally conductive boundaries between the hot and cold fluid channels can be fabricated using a 3D printing manufacturing process.

[0084] The rate of heat transfer between a hot fluid within a hot fluid channel and a cold fluid within a cold fluid channel adjacent to the hot fluid channel via a common boundary (e.g., the continuous thermally conductive boundary) is proportional to a temperature difference between the hot fluid and the cold fluid at a location of the heat transfer, and an area of the common boundary through which the heat transfer is conducted. As the cold fluid flows from the cold inlet to the cold outlet, the temperature of the cold fluid increases. Similarly, when the hot fluid flows from the hot inlet to the hot outlet the temperature of the hot fluid decreases.

[0085] As illustrated in FIG. 2A, the temperature difference AT between the hot and cold fluids may vary along the extension of the continuous, thermally conductive boundary. To maintain a relatively constant heat exchange rate between the hot and cold fluids, the area of this boundary may undergo a predetermined adjustment. In the depicted embodiment of FIG. 2A, area ACH— the area of continuous thermally conductive boundary between the cold and the hot fluid increases as AT decreases, effectively compensating for the temperature difference and ensuring consistent heat exchange between the hot fluid channel 233 and the cold fluid channel 231.

[0086] In certain embodiments, a heat exchanger features a plurality of dynamically variable continuous thermally conductive boundaries between multiple cold fluid channels and their adjacent hot fluid channels present within the heat exchanger core. This adaptable design enables precise control of heat exchange rates along the length of the continuous thermally conductive boundaries. By adjusting the boundary area per unit length of the heat exchanger core, the system can achieve a predetermined heat exchange profile, optimizing thermal performance for the heat exchanger.

[0087] In various embodiments, an area per unit length along the extension of a continuous, thermally conductive boundary or plurality of continuous, thermally conductive boundaries may change in any suitable way. In some cases, an area of the common boundary per unit length of atleast some cold fluid channels (e.g., the area of the internal surface of walls surrounding the one or more cold fluid channels) from the set of cold fluid channels 122 is configured to change along extensions of the at least some cold fluid channels and the change in the area is selected to cause a predetermined heat exchange between the cold fluid and the hot fluid along the extensions of the at least some cold fluid channels. In an example embodiment, the area is configured to increase when the temperature difference between at least some hot fluid channels and at least some cold fluid channels decreases.

[0088] In some cases, an area of the common boundary per unit length of at least some hot fluid channels (e.g., the area of the internal surface of walls surrounding the one or more hot fluid channels) from the set of hot fluid channels 124 is configured to change along extensions of the at least some hot fluid channels and the change in the area is selected to cause a predetermined heat exchange between the hot fluid and the cold fluid along the extensions of the at least some hot fluid channels. In an example embodiment, the area is configured to increase when the temperature difference between at least some hot fluid channels and at least some cold fluid channels decreases.

[0089] In some cases, an area of the continuous, thermally conductive boundary per unit volume of one or more cold or hot fluid channels as a function of location (e.g., within a particular region) within the heat exchanger core 120 is selected to cause a predetermined heat exchange between the cold fluid and the hot fluid along an length of the heat exchanger core 120. For example, the area may be selected such that it is inversely proportional to a temperature difference between the cold fluid and the hot fluid within cold fluid and hot fluid channels 122 and 124 at that location.

[0090] In addition, changes to the area of the continuous, thermally conductive boundary along an extension of this boundary for one or more cold or hot fluid channels, or as an alternative to such changes, in some implementations of the heat exchanger 100, a ratio of an overall cross- sectional area corresponding to cold fluid channels within a selected region of the heat exchanger core 120, and an overall cross-sectional area corresponding to hot fluid channels located within the selected region is selected to cause a predetermined heat exchange between the hot fluid channels and the cold fluid channels in that region. In some cases, such region corresponds to a selected volume of the heat exchanger core 120. In some cases, the region can be selected such that it includes cross-sections of a portion of all of the cold fluid channels 122. In some cases, the region can be selected such that it includes cross- sections of a portion of all of the hot fluidchannels 124. In some cases, the region can be selected such that it includes cross-sections of all of the cold fluid channels 122. Additionally, or alternatively, the region can be selected such that it includes cross-sections of all of the hot fluid channels 124. In some cases, a ratio of the total cross-sectional area corresponding to the set of cold fluid channels 122 and the set of hot fluid channels 124 is selected to cause a predetermined heat exchange between the cold fluid and the hot fluid along a length of the heat exchanger core 120.

[0091] In various cases, the changes of the ratio between cross-sectional area of cold fluid channels and hot fluid channels within a region causes a change in a relative flow velocity between a cold fluid in the cold fluid channels and a hot fluid within the hot fluid channels. For example, an increase in the ratio between cross-sectional area of cold fluid channels and hot fluid channels within a region causes a relative decrease in overall velocity of cold fluid within cold fluid channels 122 relative to the overall velocity of the hot fluid within the hot fluid channels. Herein, the overall velocity can be calculated as VC H— QC,H / C,H, where VC,His an overall (or average) velocity of the cold (Pc) hot (PH)fluid, QC His a flow rate of the cold / hot fluid in the cold / hot fluid inlet, and AC His a cross-sectional area of the cold / hot fluid channels within the region. Conversely, a decrease in the ratio causes a relative increase in the overall velocity of cold fluid within the cold fluid channels relative to the overall velocity of the hot fluid within the hot fluid channels.

[0092] In some cases, the ratio between a cross-sectional area of cold fluid channels and hot fluid channels may be fixed over a length of a region of the heat exchanger core or can increase or decrease. In some cases, the increase or decrease of the ratio can be gradual, or the ratio can change abruptly. In some cases, even when the ratio is kept relatively constant, the cross-sectional area of the cold fluid channels can increase in the same proportion as the cross-sectional area of the hot fluid channels, causing a decrease in overall Vcand VH. In some cases, the cross-sectional area of the cold fluid channels can decrease in the same proportion as the cross-sectional area of the hot fluid channels, causing an increase in overall Vcand VH.

[0093] In an example embodiment, the decrease of a velocity of any one of the cold fluid or the hot fluid at a particular region of the heat exchanger core affects the heat transfer rate at that region. For example, the decrease in velocity of the cold / hot fluids allows for a longer time for exchanging heat between the fluids, thereby leading to an increase in heat transfer rates.

[0094] In various cases, a turbulent flow of cold / hot fluid within respective cold / hot fluid channels allows for an increased heat transfer. To ensure the turbulent fluid flow, the wettedsurfaces of the continuous, thermally conductive boundary may include roughness. The roughness is configured to create a turbulent flow in a fluid channel adjacent to the continuous thermally conductive boundary. The size of the roughness may be is selected based on a Reynolds number associated with the cold / hot fluid channel and a fluid flow within the fluid channel.

[0095] Furthermore, a heat transfer from hot fluid to cold fluid via a continuous, thermally conductive boundary may be influenced by a variation in in thickness of the boundary and / or a variation in material of the boundary along an extension of the boundary within a heat exchanger core. For example, the thickness of the continuous, thermally conductive boundary may be configured to decrease in certain regions resulting in higher heat transfer rates, or the material of the boundary may be configured to change (e.g., an alloy composition of a metallic material forming the continuous thermally conductive boundary may be configured to change) resulting in a change in the heat transfer rates. For example, changing a material from aluminum to copper may result in increased heat transfer rates. In some cases, both the thickness and the material for the continuous, thermally conductive boundary can be changed to influence the heat transfer rate.

[0096] In various embodiments, the plurality of partitions of the heat exchanger core defining the set of hot fluid channels and the set of cold fluid channels forms a semi-periodic, three- dimensional lattice structure. Such a structure can form a repetitive arrangement of units or cells within the three-dimensional space defined by the heat exchanger core. In some cases, each unit or element within the lattice may have a substantially constant curvature. The curvature may refer to the amount by which surfaces of the walls defining the partitions deviate from being flat. In this context, constant curvature means that the curvature of each lattice cell or unit remains about the same throughout the lattice structure. In some possible implementations, the periodic lattice structure may include Triply Periodic Minimal Surfaces (TPMSs). The TPMSs are surfaces that exhibit minimal surface area within a repeating unit cell. Example of possible TPMSs may include Schwartz P or H surfaces, gyroid surfaces, such as Schoen’s gyroid surfaces, diamond surfaces, Neovis surfaces, F-RD Surfaces, and the like.

[0097] One of the advantages of TPMSs are their intricate and interconnected structures, characterized by a large surface area per unit volume. These structures maximize the contact area between the continuous thermally conductive boundary and the fluids (hot or cold) flowing through adjacent to it, thereby facilitating efficient heat exchange. Furthermore, the complex geometries of TPMSs can promote turbulence and mixing within the flowing fluids. Such mixingcan disrupt boundary layers and stagnant zones, effectively bringing more fluid in contact with the heat transfer surface, further boosting heat exchange efficiency. Additionally, compared to traditional heat sinks with solid bulk structures, TPMSs offer the potential for lighter and more compact designs. TPMSs can be formed from various materials, including metals, polymers, and ceramics, each with unique thermal properties. Choosing the optimal material based on the application and desired heat transfer characteristics allows for further optimization.

[0098] FIGS. 3A-3F show example gyroid periodic lattice structures formed by the plurality of partitions defining the cold and hot fluid channels that can be used for forming a heat exchanger core. FIG. 3A shows an example periodic lattice structure 321 A forming a heat exchanger core 320A, and FIG. 3B shows cold fluid channels 331A and hot fluid channels 333A. In an example implementation, the cross-sectional areas of the cold fluid channels 331 A and the hot fluid channels 333A are configured to be the same as indicated by a diameter dHof a cross-sectional area AHfor hot fluid channels, and by a diameter dcof a cross-sectional area Acfor the cold fluid channels being the same as diameter dH. FIGS. 3C and 3D show and example periodic lattice structure 32 IB forming a heat exchanger core 320B such that the cross-sectional areas of the hot fluid channels 333B are configured to be larger than the cross-sectional areas of the cold fluid channels 33 IB as indicated by the diameter dHbeing larger than the diameter dc. Similarly, FIGS. 3E and 3F show an example periodic lattice structure 321C forming a heat exchanger core 320C such that the cross-sectional areas of the cold fluid channels 331C are configured to be larger than the cross-sectional areas of the hot fluid channels 333C as indicated by the diameter dcbeing larger than the diameter dH.

[0099] In various embodiments, the partitions of a heat exchanger core that defines the cold and hot fluid channels includes a plurality of partitions between adjacent hot and cold fluid channels. Each partition includes a wall that defines a continuous, thermally conductive boundary between adjacent hot and cold fluid channels. Additionally, each wall can have a curvature, as illustrated, for example, in FIGS. 3A-F. In certain cases, such curvature may vary throughout the length of the heat exchanger core. For instance, there might be configurations where the curvature changes from one region of the heat exchanger core to another. In some instances, the curvature could increase gradually or abruptly in a direction from the cold inlet to the cold outlet. Similarly, there may be cases where the curvature increases along the extension from the hot inlet to the hot outlet. These changes in curvature of the walls defining the continuous, thermally conductiveboundary(ies) have a direct impact on the flow characteristics of the cold and / or hot fluids flowing within the fluid channels heat exchanger core. Additionally, as shown in FIGS. 3A-3F, the adjacent hot and cold fluid channels together with the curvature of the individual walls defining the continuous, thermally conductive boundaries between such channel define a periodic lattice structure.

[0100] In some cases, fluid channels, defined within the heat exchanger core by the plurality of partitions and featuring increased curvature and a larger cross-sectional area may induce a slower flow of the cold and / or hot fluids. While this deliberate slowing of flow may enhance the heat transfer between the fluids, it comes at the expense of increased resistance to the flow of cold and / or hot fluids flowing within the fluid channels. This increased resistance is manifested as a rise in pressure drop across the heat exchanger core for the cold and / or hot fluids.

[0101] The alterations in curvature of the partitions between adjacent hot and cold fluid channels within the heat exchanger core can be achieved by modifying the topology of the periodic lattice structure. This modification encompasses various transformations, such as morphing from a gyroid periodic structure to a diamond periodic structure, transitioning Schwarz P surfaces into Schwarz D, G, or I-WP surfaces, or transforming any other periodic lattice structures in a suitable manner. One approach to transition the periodic lattice structure involves continuous transformations, including stretching and compressing the periodic lattice structure, while preserving the overall topology of the structure.

[0102] For instance, FIGS. 4A-4B illustrate cross sections of heat exchangers 400 and 401, respectively, with their respective heat exchanger cores 400A, 401B represented as a Triply Periodic Minimal Surface (TPMS) gyroid structure. In FIG. 4A, the heat exchanger core 400A of heat exchanger 400 features an “unstretched” TPMS gyroid structure, where the characteristic dimension of a periodic cell in the x-direction equals that in the y-direction, resulting in a 1:1 y:x aspect ratio. Alternatively, in FIG. 4B, the heat exchanger core 401B of heat exchanger 401 incorporates a “stretched” TPMS gyroid structure, where the characteristic dimension of a periodic cell in the y-direction is twice as large as that in the x-direction, leading to a 2:1 y:x aspect ratio.

[0103] FIG. 4C shows exemplary periodic lattice structures that can be employed within a heat exchanger core with periodic cells having aspect ratios of 1:1, 2:1, 3:1, and 4:1 y:x, respectively.

[0104] FIG. 4D shows a periodic lattice structure 420 including multiple cells 422 having different aspect ratios in different regions of the lattice structure. As shown in FIG. 4D, the periodiclattice structure 420 includes first and second regions 424A, 424B with cells 422 having a first aspect ratio and a transition region 426 disposed between the first and second regions 424A, 424B having a second aspect ratio. In some embodiments, the second aspect ratio can be greater than the first aspect ratio. For example, an aspect ratio of cells 422 in the first and second regions 424A, 424B can be 1:1, 2:1, or 3:1 and the aspect ratio cells 422 in the transition region 426 can be 2:1, 3:1., or 4:1. Other aspect ratios for cells in each region are contemplated. The change in aspect ratio from the first region 424A to the transition region 426 and, similarly, from the transition region 426 to the second region 424B can be abrupt or the change can be gradual.

[0105] In some embodiments, the aspect ratio can be adjusted gradually along a length or extent of the heat exchanger core, causing a gradual change in heat transfer and pressure drop characteristics for the periodic structure. A gradual change in aspect ratio facilitates a corresponding gradual adjustment in the heat transfer and pressure drop characteristics of the periodic structure. In instances where the characteristics of the periodic lattice structures undergo rapid changes, a transitioning region may be employed between regions of the periodic lattice structures having different characteristics. This ensures a smoother transition and mitigates abrupt variations in heat transfer and pressure drop within the heat exchanger core. Notably, this gradual change in aspect ratio of the cells of the periodic lattice structure within a heat exchanger core of a heat exchanger can be controlled and facilitated by using additive manufacturing processes to produce the heat exchanger including the heat exchanger core.

[0106] FIG. 4E illustrates an effect of cell aspect ratio on a pressure drop for hot and cold fluids within the heat exchangers 400 and 401. The heat exchanger core 400A has a period lattice structure with a y:x cell aspect ratio of 1:1, and exhibits a larger pressure drop for both hot and cold fluids compared to heat exchanger core 400B with a y:x cell aspect ratio of 2:1. For instance, the pressure drop in heat exchanger 400 could be approximately two or more times greater for both hot and cold fluids in comparison to heat exchanger 401. In a specific implementation, a pressure drop in heat exchanger 400 might be around 14 PSI for hot fluid and about 12 PSI for cold fluid. In contrast, the pressure drop in heat exchanger 401 may be approximately 5 PSI for hot fluid and 3 PSI for cold fluid. This signifies a substantial reduction in the pressure drop within the heat exchanger core, exceeding a twofold decrease, facilitated by adjustments in the aspect ratio. Such alterations in the aspect ratio of the periodic cells in the lattice structure may play a significant role in diminishing the pressure drop within the heat exchanger core.

[0107] In various cases, heat exchangers with lattice geometry variations can be used to leverage tradeoff between attaining a lower pressure drop and maximizing heat transfer by increasing surface area for heat transfer between hot and cold fluid channels of the heat exchangers.

[0108] FIG. 5 shows another example embodiment of a heat exchanger 500. The heat exchanger 500 includes an enclosure 505. The enclosure 505 includes a hot inlet 512 for inflow of a hot fluid, and a hot outlet 516 for outflow of the hot fluid. Further, the enclosure 505 includes a cold inlet 510 for inflow of a cold fluid and a cold outlet 514 for outflow of the cold fluid. Additionally, the enclosure 505 includes a heat exchanger core 520. The heat exchanger core 520 includes a first region 521 defining a first set of hot fluid channels 524A and a first set of cold fluid channels 522A. The first region 521 includes a first partition 525 A defined by a wall common to both the first set of hot fluid channels 524A and the first set of cold fluid channels 522A. The first partition 525A is a continuous thermally conductive boundary configured to facilitate a first heat exchange between the hot fluid and the cold fluid. For example, the first heat exchange may be characterized by a first heat exchange rate between the hot fluid within the hot fluid channels 524A and the cold fluid within the cold fluid channels 522A. Additionally, or alternatively, the first heat exchange rate may be characterized by a predetermined volumetric distribution of heat exchange rates throughout the first region 521.

[0109] Further, the enclosure 505 includes a second region523 defining a second set of hot fluid channels 524B and a second set of cold fluid channels 522B. The second region 523 includes a second partition 525B common to both the second set of hot fluid channels 524B and the second set of cold fluid channels 522B. The second partition525B is continuous, thermally conductive boundary configured to facilitate a second heat exchange between the hot fluid and the cold fluid. Similarly, to the first heat exchange, the second heat exchange may be characterized by a second heat exchange rate between the hot fluid within the hot fluid channels 524B and the cold fluid within the cold fluid channels 522B. Additionally, or alternatively, the second heat exchange rate may be characterized by a predetermined volumetric distribution of heat exchange rates throughout the second partition 523. In various implementations, the first set of hot fluid channels 524A is configured to fluidly connect to the second set of hot fluid channels 524B, and the first set of cold fluid channels 522A is configured to fluidly connect to the second set of cold fluid channels 522B.

[0110] In various implementations, distinguishing factors between the first region 521 and the second region 523 exhibit differences in heat exchange rates and their associated pressure drops.These differences contribute to a degree of control over the overall heat exchange rate and pressure drop within the heat exchanger 500. For instance, in certain implementations, the area of the second partition 525B may be selected to be larger than the area of the first partition525A. The magnitude of this area difference can be determined to ensure an approximate equality between the first and second heat exchanges.

[0111] In some cases, the curvature of the wall defining the first partition 525A is selected to such that the hot and cold fluid channels in the first region 521 exhibit a specific (first) volumetric distribution, while the curvature of the second partition 525B is chosen to impart another (second) distinct volumetric distribution on the hot and cold fluid channels in the second region 523. This selection ensures that the overall pressure drop through both the first region 521 and the second region 523 can be below a predetermined threshold. In an example implementation the pressure drop within the first region 521 may be about the same as the pressure drop within the second region 523, even when the area of the second partition 525B surpasses that of the first partition 525A. This deliberate configuration maintains a balanced pressure drop while allowing for variations in boundary areas, offering a way of regulating heat exchange within the heat exchanger 500.

[0112] In some cases, a measure of a curvature of the wall defining the second partition 525B may be different (e.g., larger) than a measure of a curvature of the wall defining the first partition 525A. In an example embodiment, the measure of the curvature of the first partition 525A or the second partition 525B may be calculated as an integral of the curvature over an area of the corresponding first partition 525 A or the second partition 525B.

[0113] Similar to the implementations shown in FIGS. 3A-3F related to heat exchange cores 320A-320C, cold fluid channels 522A / B may have different cross-sectional areas than hot fluid channels 524A / B in the first region 521 or the second region 523. Further, the cross-sectional areas of the cold fluid channels 522A may be different from the cross-sectional areas of the cold fluid channels 522B. For example, cross-sectional areas of the cold fluid channels 522B may be larger or smaller than cross-sectional areas of the cold fluid channels 522A. Similarly, cross-sectional areas of the of the hot fluid channels 524A may be different from the cross-sectional areas of the hot fluid channels 524B. For example, cross-sectional areas of the hot fluid channels 524B may be larger or smaller than cross-sectional areas of the hot fluid channels 524A.

[0114] Alternatively, in some implementations the cross-sectional areas of the cold fluid channels 522A may be the same as the cross-sectional areas of the hot fluid channels 524A. Further, in some implementations, the cross-sectional areas of the cold fluid channels 522B may be the same as the cross-sectional areas of the hot fluid channels 524B.

[0115] In some implementations, the cross-sectional areas of the cold fluid channels 522A may be the same as the cross-sectional areas of the cold fluid channels 522B, while the cross-sectional areas of the hot fluid channels 524A may be different than cross-sectional areas of the hot fluid channels 524B. Similarly, in some implementations, the cross-sectional areas of the hot fluid channels 524A may be the same as the cross-sectional areas of the hot fluid channels 524B, while the cross-sectional areas of the cold fluid channels 522A may be different than cross-sectional areas of the cold fluid channels 522B.

[0116] In some implementations, a ratio of a volume occupied by the cold fluid channels 522A to a volume occupied by the hot fluid channels 524A may be different (e.g., larger, or smaller) than a ratio of a volume occupied by the cold fluid channels 522B to a volume occupied by the hot fluid channels 524B. In some implementations, a ratio of a volume occupied by the cold fluid channels 522A to a volume occupied by the cold fluid channels 522B may be different (e.g., larger, or smaller) than a ratio of a volume occupied by the hot fluid channels 524A to a volume occupied by the hot fluid channels 524B.

[0117] It should be noted that the specific structure of the first boundary 525A is selected to optimize the heat transfer between the hot fluid in the hot fluid channels 524A and the cold fluid in the cold fluid channels 522A. This optimization process involves adjusting various structural features within the first region 521, including: the volume distribution of hot and cold fluid channels 524A and 522A at different locations within the first region 521, the cross-sectional areas, number, topology, and curvature of the hot and cold fluid channels 524A and 522A, and the curvature of partition 525A at different points within the first region 521. Similar optimization techniques can be applied to the second partition region 523 and its partition 525B to achieve optimal thermal performance throughout the entire heat exchanger core 520.

[0118] In various embodiments, the first region 521 and the second region 523 can be linked through a transitional region 527, as depicted in FIG. 5. This transitional region 527 facilitates the fluid connection between the first set of hot fluid channels 524A and the second set of hot fluid channels 524A, as well as between the first set of cold fluid channels 522A and the second set ofcold fluid channels 522A, without inducing a significant pressure drop at the transition point. Moreover, the design of the transition region 527 ensures a continuous connection between the first partition 525A and the second partition 525B, preventing abrupt changes in the boundary surfaces.

[0119] FIG. 6 is another schematic representation of the first region 521 and the second region 523 connected together by a transitional region 527. The first region 521 may occupy a first physical volume (e.g., region 1) of the heat exchanger core 520, and the second region 523 may occupy a second physical volume (e.g., region 2) of the heat exchanger core 520. In an example embodiment, based on a volumetric distribution of a temperature difference A7j between the hot fluid channels 524A and the cold fluid channels 522A, as well as a volumetric distribution of a boundary area ACH1of the partition 525A between these channels, the first heat exchange rate may be determined for the first region 521. Further, based on a volumetric distribution of a temperature difference AT2between the hot fluid channels 524B and the cold fluid channels 522B, as well as a volumetric distribution of a boundary area ACH2of the common boundary 525B between these channels, the second heat exchange rate may be determined. In various embodiments, the volumetric distribution of areasand ACH2may be determined based on the volumetric distributions for A7j and AT2to cause the first heat exchange rate being about the same as the second heat exchange rate.

[0120] It should be noted that although FIG. 6 illustrates two regions, 521 and 523, in certain implementations, more than two regions can be employed within a heat exchanger core, interconnected by multiple transitional regions. For instance, three or more regions may be utilized, and their arrangement within the heat exchanger core 520 can vary. These regions might be positioned adjacent to each other, overlapping, implemented within one another, aligned along a flow line connecting a cold inlet with a cold outlet, situated along a flow line connecting a hot inlet with a hot outlet, or positioned relative to one another in any suitable configuration.

[0121] The heat exchangers described herein can be implemented in various ways, employing diverse structural shapes and configurations, while generally adhering to the elements illustrated in FIG. 1 by the heat exchanger 100 and in FIG. 5 by the heat exchanger 500. FIGS. 7A-7L show several implementations of such heat exchangers. In the instances depicted in FIGS. 7A-7L, heat exchanger cores are manufactured utilizing a semi-periodic three-dimensional lattice structure. For instance, in the embodiment of a heat exchanger employing first and second partitions (e.g., theheat exchanger 500), both the first and second partitions may be constructed using a semi-periodic three-dimensional lattice structure.

[0122] In an exemplary implementation of a heat exchanger 700A, as depicted in FIG. 7A, the core is designed to be a compact three-dimensional structure. This configuration features a hot inlet 712A for the inflow of hot fluid and a hot outlet 716A for the outflow of hot fluid. Additionally, the heat exchanger 700A is equipped with a cold inlet 710A for the inflow of cold fluid and a cold outlet 714A for the outflow of cold fluid. The heat exchanger 700A is constructed employing a heat exchanger core having a gyroid periodic lattice structure that undergoes modifications along its entire extension (these adjustments may not be distinctly visible in FIGS. 7A-7B). These alterations are made to customize the heat exchange and pressure drop characteristics specific to the heat exchanger 700A.

[0123] FIGS. 7C-7D show another implementation of a heat exchanger 700B including a hot inlet 712B, a hot outlet 716B, a cold inlet 71 OB, and a cold outlet 714B. The heat exchanger 700B is constructed employing a heat exchanger core having a gyroid periodic lattice structure. The directional flow of fluids within the heat exchanger 700B is illustrated with arrows in FIG. 7D. FIG. 7E-7F shows another implementation of a heat exchanger 700C. Correspondingly, the heat exchanger 700C features a hot inlet 712C, a hot outlet 716C, a cold inlet 710C, and a cold outlet 714C. Heat exchanger 700C is a variation of heat exchanger 700B in that its cross-sectional geometry and volume capacity has been altered. However, heat exchanger 700C is still capable of achieving the same heat exchange and pressure characteristics as heat exchanger 700B. Heat exchanger 700C also has a heat exchanger core having a periodic lattice structure.

[0124] FIGS. 7G and 7H show yet another implementation of a heat exchanger 700D. The heat exchanger 700D includes a bifurcated cold inlet 710D, a bifurcated cold outlet 714D, a hot inlet 712D and a hot outlet 716D. In the example implementation, heat exchanger 700D includes bifurcated main body 720D, each leg 725D and 725D’ of the bifurcated main body 720D including a heat exchanger core having a semi-periodic lattice structure similar to previous implementations as shown and described herein. In some implementations, heat exchanger 700D can be fluidly coupled in series or in parallel with one or more additional heat exchangers having the same configuration. In some cases, the cross-sectional geometry and / or volume capacity of each heat exchanger 700D can be varied to achieve optimal heat transfer efficiency.

[0125] FIGS. 71 and 7J shows another implementation of a heat exchanger 700E. The heat exchanger 700E includes a cold inlet 710E, a cold outlet 714E, a hot inlet 712E and a hot outlet 716E. Similar to the heat exchanger 700A-700D, the heat exchanger 700E includes a heat exchanger core having a semi-periodic lattice structure.

[0126] Heat exchangers 700A-700F as shown in FIGS. 7A-7J have different characteristics for the temperatures measured at the cold and hot outlets as well as pressure drop characteristics across the heat exchanger cores for these heat exchangers. FIG. 8A shows the temperatures at the cold and hot outlets for heat exchangers 700A-700F and FIG. 8B shows the pressure drop performance at both the cold and hot outlets for heat exchangers 700A-700F. The heat exchanger 700E has a smallest hot outlet temperature of about 43 degrees C measured at the hot outlet among heat exchangers 700A-700F, while heat exchanger 700A has a smallest cold outlet temperature of about 167 degrees C measured at the cold outlet among the heat exchangers 700A-700E. Further, due to a relatively straight structure of the heat exchanger 700C a pressure drop for this heat exchanger is significantly smaller for both the hot fluid channels and the cold fluid channels as compared to the other heat exchangers 700A-700D, and 700F. The pressure drop for heat exchanger 700C is only a few psi for both heat and cold fluid channels, while the pressure drop for heat exchanger 700E is significantly higher (-five orders of magnitude) and can reach up to about 161 psi for hot fluid channels and about 100 psi for cold fluid channels. Note that heat exchanger 700E has a more compact design than 700A which results in the increased pressure drop for heat 700Cexchanger as compared to heat exchanger 700A.

[0127] FIGS. 9A-9C are collectively used to show the effect of changing a volume fraction of cold fluid channels relative to a volume fraction of hot fluid channels. The volume fraction indicates a volume fraction of cold fluid channels relative to the volume of hot fluid channels. Example structures of heat exchanger cores 920A and 920B are shown in FIG. 9A. The heat exchanger core 920A includes hot fluid channels 924A and cold fluid channels 922A, while the heat exchanger core 920B includes hot fluid channels 924B and cold fluid channels 922B. As shown in FIG. 9A, the hot fluid channels 924A have a smaller cross-sectional area than cold fluid channels 922A, with a corresponding cold / hot volume fraction of 2.7:1. On the other hand, heat exchanger core 920B includes hot fluid channels 924B with the same cross-sectional area as the cold fluid channels 922B, thus, resulting in the cold / hot volume fraction of 1:1. FIG 9B shows schematically various other heat exchanger core structures 920B-920E having corresponding coldfluid channels 922B-922E and hot fluid channels 924B-924E, with respective cold / hot volume fractions of 1:1 2:1, 4:1, and 6:1. It should be noted that any other volume fraction can be used as needed to optimize heat transfer between the hot fluid within hot fluid channels and the cold fluid within the cold fluid channels. FIG. 9C shows average temperatures at the hot and the cold outlets for heat exchanger cores 920A having a volume fraction ration of 2.7 : 1 and 920B having a volume fraction ration of 1:1. As shown in FIG. 9C, the heat exchanger core 920B has the temperature at the hot outlet than is about 40% less than the temperature at the hot outlet of the heat exchanger core 920A. The temperature TBat the cold outlet for the heat exchanger core 920B (TBis 160 °C) is slightly larger than the temperature TAat the cold outlet for the heat exchanger core 920A (TAis 139 °C).

[0128] In various embodiments of the heat exchangers discussed herein, some cold and / or hot fluid channels can include branches. An example channel 1040 with branches 1042 and 1043 is shown in FIG. 10. The channel 1040 includes a root segment 1041, a first branch segment 1042 (also referred to as a first branch 1042) and a second branch segment 1043 (also referred to as a second branch 1043). Note that multiple branches 1042 and 1043, as well as the root segment 1041 are forming a single channel 1040. The root segment 1041 may have a crosssection 1051, while branches 1042 and 1043 have corresponding cross-sections 1052 and 1053. In example implementations, channels are configured to be split into branches to allow for increased area of the boundary surrounding the channels 1040, thereby allowing for a control of the heat transfer between the channel 1040 and adjacent channels. The branching of the channel 1040 can lead to increased pressure drop within the channel 1040 due to a head loss associated with the curvature of the channel 1040 at a split location 1046 as well as the head loss due to increased wetted boundary of the channel 1040 due to additional boundary for the channel at branches 1042 and 1043. To minimize the increase in the pressure drop within the channel 1040, the root segment 1041 may gradually split into branches 1042 and 1043. Furthermore, the crosssections for branches 1042 and 1043 may be selected to minimize the pressure drop within the channel 1040. For example, in some implementations, for a channel cross-sectional area Acof cross-section 1051, a first branch cross-sectional area Ablfor the cross-section 1052 and a second branch cross-sectional area Ab2for the cross-section 1053 can be selected such that the channel cross-sectional area Acraised in a preset power p is about equal to a sum of the first branch cross-sectional area Ablraised in the preset power and the second branch cross-sectionalarea Ab2raised in the preset power. That is Ap= Apbl+ A^2. In an example embodiment the power p may be selected to have a value of about three. It should be noted that while two branches are shown in FIG. 10, more than two branches can be formed. Furthermore, the branches may be arranged in any suitable way relative to each other. When more than two branches are present at a branch junction point (e.g., at the split location 1046), the areas for the channel cross-sectional area and branches may be related as Ap—In some embodiments, the ratio of the channel cross-sectional area to its respective branches may follow the “Golden Rule”. The Golden Rule is an approximate mathematical ratio found in various natural structures and patterns whose value is approximately 1.618.

[0129] FIG. 11 shows an example embodiment of a heat exchanger 1100 that includes at least some channels containing branches. The heat exchanger 1100 includes an enclosure 1105, which, in turn, includes a hot inlet 1112 for inflow of a hot fluid, a hot outlet 1116 for outflow of the hot fluid, a cold inlet 1110 for inflow of a cold fluid, and a cold outlet 1114 for outflow of the cold fluid. Further, the heat exchanger 1100 includes a heat exchanger core 1120. The heat exchanger core 1120 includes a partition defining a set of hot fluid channels 1124 and a set of cold fluid channels 1122. The partition includes a boundary common (e.g., continuous thermally conductive boundary) to both the hot and the cold fluid channels 1124 and 1122, the common boundary being configured to facilitate a heat exchange between the hot fluid and the cold fluid. In the example embodiment, a cold fluid channel 1123 from the set of cold fluid channels 1122 forms a set of branches, such as branches 1125 and 1127, as shown in FIG. 11. The branches 1125 and 1127 can be formed within a selected region of the heat exchanger core 1120. In the example implementation, the number of the branches of the cold fluid channel 1123 is selected to be proportional to a decrease in a temperature difference between the cold fluid and the hot fluid within the region containing branches as compared to a temperature difference between the cold fluid at the cold inlet 1110 and the hot fluid at the hot outlet 1116.

[0130] Additionally, or alternatively, at least one hot fluid channel from the set of hot fluid channels forms a set of branches within a selected region of the heat exchanger core. In the example implementation, the number of the branches of the hot fluid channel is selected to be proportional to a decrease in a temperature difference between the cold fluid and the hot fluid within the region containing branches as compared to a temperature difference between the cold fluid at the cold inlet 1110 and the hot fluid at the hot outlet 1116. In some cases, the region that contains branchesfor the cold fluid channels 1 122 is the same region that contains branches for the hot fluid channels 1124. Additionally, or alternatively hot fluid channels 1224 may include regions in which hot fluid channels 12224 are split into branches, while the cold fluid channels 1122 may not split into branches in those regions. Similarly, there can be some regions in which cold fluid channels 1222 are split into branches, while the hot fluid channels 1124 may not split into branches in those regions.

[0131] In some cases, the number of branches of the cold fluid channels 1122 may be about the same as the number of branches of hot fluid channels 1124, and in other implementations the number of branches for cold fluid channels 1122 may be different than the number of branches for hot fluid channels 1124.

[0132] It should be noted that the number of branches may be dependent on a cold / hot volume ratio the cold fluid channels and the hot fluid channels. For example, adding branches to channels occupying a larger volume (e.g., cold fluid channels) may result in increase of the heat transfer between the hot fluid channels and the cold fluid channels, without significantly affecting a pressure drop for these cold fluid channels.

[0133] Additionally, when introducing branches to cold / hot fluid channels, these channels can undergo simultaneous geometric transformations, such as stretching, ensuring that the overall curvature remains relatively unaffected. This approach prevents a substantial rise in pressure drop within these channels. In a specific implementation, the y:x aspect ratio (illustrated in FIGS. 4A- 4D) may be chosen to avoid a significant increase in pressure drop, especially in the channels containing branches. For instance, for the pressure drop measured per unit length of a heat exchanger core extension, the channels may be configured to maintain such pressure drop per unit length to be approximately uniform (e.g., not differing by more than about 20%).

[0134] In certain embodiments, each branch of a cold fluid channel within the set of cold fluid channels 1122 defines a segment. Illustrated in FIG. 12, for instance, is a channel 1250 featuring branch segments S1-S9. An exemplary implementation involves an increase in the number of segments along the extension of the cold fluid channel 1250, following the direction from the cold inlet to the cold outlet, as depicted by arrow D in FIG. 12. Correspondingly, in the case of a hot fluid channel within the set of hot fluid channels 1124, each branch also defines a segment. Furthermore, the number of segments for the hot fluid channel may be configured to increase along its extension from the hot inlet to the hot outlet.

[0135] FIGS. 13A and 13B show an example split of a segment SI of a channel 1350 into branch segments S2 and S3. In the example implementation, segments S2 and S3 have a variable cross-sectional area that is configured to increase away from the split region and along the extension of the segments S2 and S3. Near the split region the cross-sectional areas A±, A21, and A22may be selected to satisfy: A = A^ + A2. In an example implementation the cross-sectional areas for segments S2 and S3 are increased such that area ri31for segment S3 is about the same size as area ri32for segment S2, and these areas are larger than area A for segment SI. FIG. 13B shows an effect of the area increase on the flow of fluids within branch segments S2 and S3.

[0136] FIG. 14A and 14B show an example embodiment of a heat exchanger 1400 that can be in form and / or in function similar or identical to the heat exchanger 700A, as shown in FIGS. 7A and 7B. The heat exchanger 1400 includes a hot inlet 1412, a hot outlet 1416, a cold inlet 1410, and a cold outlet 1414. The heat exchanger 1400 includes a heat exchanger core 1420 having a gyroid periodic lattice structure. The cold inlet 1410 is configured to be fluidly connected to a cold fluid inflow manifold 1451 for fluidly coupling the cold inlet to cold fluid channels of the heat exchanger 1400. As shown in FIG. 14B, the cold fluid inflow manifold 1451 is a cavity extending at least partially through the heat exchange core 1420, the cavity having a plurality of openings such as openings 1452A and 1452B. These openings are configured to connect the cold fluid inflow manifold 1451 with the cold fluid channels of the heat exchanger 1400. The cold fluid inflow manifold 1451 may be used evenly distribute the cold air to the cold fluid channels of the heat exchanger 1400 through openings 1452A and 1452B.

[0137] In various embodiments of heat exchangers discussed herein, various inflow outflow manifolds for inflow of cold fluid or hot fluid for cold and hot fluid channels may be employed to control temperature distribution within such cold or hot fluid channels.

[0138] FIGS. 15A-15B show examples of such inflow outflow manifolds. For example, in an implementation of a heat exchanger 1500, as shown in FIGS. 15A and 15B, a cold outlet 1514 may include a contraction section following a manifold section 1513 that has a cross-sectional area A1greater than the cross-sectional area A2. Such a change in the cross-sectional area result in a decrease in temperature of cold fluid in the cold outlet 1514 as compared to the cold fluid within the manifold section 1513.

[0139] For example, temperature T2in the cold outlet 1514 may be substantially less than temperature T in the manifold section 1513. In an example implementation the change of diameterfrom about 20 millimeters (mm) for area A1to diameter of about 8 mm for area d2may result in more than twofold decrease in temperature. In an example implementation T2may be about 45 °C and T) may be about 150 °C. The temperature change due to cross-sectional area contraction / expansion between a first section 1513 and a second section 1514 is given by T2= T + Vi2 / (2cp) •where T2is the temperature in the second section, is the temperature in the first section, v is a velocity in the first section, cpis a specific heat at a constant pressure in the first section, p, and p2are gas densities in the first and the second section respectively, and A±and A2are cross-sectional areas of the first and the second section respectively. If A1is greater than d2and densities p, and p2are nearly equal (typically applicable to a substantially incompressible flow corresponding to a Mach number generally less than about 0.3), it follows that T2is lower than T . Conversely, when A^ is less than A2, while densities p and p2are nearly equal, T2is higher than 7^ .

[0140] In some implementations, a heat exchanger may include a hot fluid outflow manifold fluidly coupling the set of hot fluid channels and the hot outlet. The hot fluid outflow manifold is located between hot fluid channels and the hot outlet. The hot fluid outflow manifold configured to have a cross-sectional area larger than a cross-sectional area of the hot outlet, thereby causing a temperature decrease of the hot fluid within the hot outlet.

[0141] Further, FIGS 15C and 15D show heat exchangers with two example configurations for cold fluid channels. FIG. 15C shows a heat exchanger 1501 having a cold inlet 1523A, a heat exchanger core 1537 A, a first transitional region 1533A and a second transitional region 1535A, both transitional regions 1533A and 1535A are configured to fluidly couple heat exchanger core 1537A with cold inlet 1523A. As shown in FIG. 15C first transitional region couples cold inlet 1523A and second transitional region 1535A, and second transitional region 1535A is located between first transitional region 1533A and heat exchanger core 1537A. Similarly, FIG. 15D shows a heat exchanger 1501B having a cold inlet 1523B, a heat exchanger core 1537B, a first transitional region 1533B and a second transitional region 1535B, both configured to fluidly couple heat exchanger core 1537B with cold inlet 1523B.

[0142] Note, that heat exchanger core 1537A may be similar in structure and / or in function to heat exchanger core 1537B. However, as shown in FIGS. 15C and 15D, second transitional regions 1535A and 1535B may have different geometrical design. For example, vacancies 1536A have elongated shape comparing to vacancies 1536B resulting in different geometric structure of coldfluid channels forming second transitional regions 1535A and 1535B. Such differences in the heat exchanger core structure can affect the fluid flow within such cold fluid channels. For example, fluid flow within cold fluid channels in second transitional regions 1535A is less uniform resulting in faster fluid flow in the center of second transitional region 1535A and slower fluid flow at the peripheral portion of second transitional region 1535A (as indicated by shading of FIG. 15C).

[0143] Contrary to the design of fluid channels depicted in FIG. 15C, the geometry of channels in the second transitional region 1535B results in a substantially uniform fluid flow throughout the second transitional region 1535B, as indicated by the substantially uniform shading in FIG. 15D. Furthermore, such uniform flow within the second transitional region 1535B leads to a more consistent flow within the heat exchanger core 1537B compared to the fluid flow within the heat exchanger core 1537A, as indicated by the shading in FIG. 15C and 15D.

[0144] It should be noted that various changes in the geometry of cold fluid channels can be utilized, as well as corresponding changes in hot fluid channels. These changes may involve adjustments in the cross-sectional area of the cold fluid channels, alterations in the aspect ratio of such cold fluid channels relative to hot fluid channels (see, for example, FIG. 4C), branching of such channels, and similar modifications. In some instances, the overall cross-sectional area of cold fluid channels may vary. For instance, the overall cross-sectional area of channels within the first transitional region 1533B may be smaller than the overall cross-sectional area of cold fluid channels within the second transitional region 1535B, resulting in a ratio of such cross-sectional areas greater than one. Such variations in cross-sectional area ratio can influence the temperature of the cold fluid.

[0145] In some implementations, the specific geometry of channels can be optimized to enhance the flow of fluid within such channels. For example, the geometry can be optimized to ensure a relatively uniform fluid flow within the channels. This optimization may involve configuring the flow to change by no more than 10%, 20%, 30%, 40%, or any other predetermined flow-related threshold among different channels at a particular cross-section of the heat exchanger core 1537B and / or transition regions 1533B and 1535B. Alternatively, or additionally, the geometry of channels can be optimized to minimize pressure drop within such channels.

[0146] FIG. 16 is a simplified schematic block diagram of an exemplary gas purification system 1600 including a feed gas inlet 1602, a purified gas outlet 1604, a heat exchanger 1606, a heater 1608, and a purifier 1610. The heat exchanger 1606 can be a heat exchanger as describedherein according to the various embodiments. In some cases, the gas purification system 1600 can include two or more heat exchangers 1606 arranged in scries or in parallel to one another.

[0147] Herein, “or” is inclusive and not exclusive, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A or B” means “A, B, or both,” unless expressly indicated otherwise or indicated otherwise by context. Moreover, “and” is both joint and several, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A and B” means “A and B, jointly or severally,” unless expressly indicated otherwise or indicated otherwise by context.ASPECTS

[0148] Aspect 1 relates to a heat exchanger including an enclosure, the enclosure comprising: a hot inlet for inflow of a hot fluid; a hot outlet for outflow of the hot fluid; a cold inlet for inflow of a cold fluid; a cold outlet for outflow of the cold fluid; and a heat exchanger core including a partition defining a set of hot fluid channels and a set of cold fluid channels, the partition including at least a boundary common to both the hot and the cold fluid channels, the common boundary being configured to facilitate a heat exchange between the hot fluid and the cold fluid flowing within the hot and cold fluid channels, wherein: an area of the common boundary per unit length of at least some cold fluid channels from the set of cold fluid channels is configured to change along extensions of the at least some cold fluid channels; and the change in the area is selected to cause a predetermined heat exchange between the cold fluid and the hot fluid along the extensions of the at least some cold fluid channels.

[0149] Aspect 2 includes the heat exchanger of aspect 1, wherein the partition forms a semiperiodic three-dimensional lattice structure.

[0150] Aspect 3 includes the heat exchanger of any of aspects 1-2, wherein a ratio of a total cross-sectional area corresponding to the set of cold fluid channels to a total cross-sectional area corresponding to the set of hot fluid channels is selected to cause a predetermined heat exchange between the cold fluid and the hot fluid along an length of the heat exchanger core.

[0151] Aspect 4 includes the heat exchanger of any of aspects 1-3, wherein a curvature corresponding to boundaries forming the partition increases along a length of the heat exchanger core in a direction from the cold inlet to the cold outlet.

[0152] Aspect 5 includes the heat exchanger of any of aspects 1-4, wherein an area of the common boundary per unit volume as a function of a location within the heat exchanger core isselected to cause a predetermined heat exchange between the cold fluid and the hot fluid along a length of the heat exchanger core.

[0153] Aspect 6 includes the heat exchanger of aspect 5, wherein an area of the common boundary per unit volume as a function of location within the heat exchanger core is configured to be inversely proportional to a temperature difference between the cold fluid and the hot fluid at that location.

[0154] Aspect 7 includes the heat exchanger of any of aspects 1-6, wherein the common boundary includes roughness configured to create a turbulent flow in a fluid channel adjacent to the common boundary, and wherein a size of the roughness is selected based on a Reynolds number associated with the fluid channel and a fluid flow within the fluid channel.

[0155] Aspect 8 includes the heat exchanger of any of aspects 1-7, wherein the common boundary includes at least one of: a variation in thickness or a variation in material along a length of the heat exchange.

[0156] Aspect 9 includes the heat exchanger of any of aspects 1-8, further comprising a hot fluid outflow manifold for fluidly coupling the set of hot fluid channels and the hot outlet, the hot fluid outflow manifold configured to have a cross-sectional area larger than a cross-sectional area of the hot outlet causing a temperature decrease of the hot fluid within the hot outlet.

[0157] Aspect 10 relates to a heat exchanger including an enclosure, the enclosure comprising: a hot inlet for inflow of a hot fluid; a hot outlet for outflow of the hot fluid; a cold inlet for inflow of a cold fluid; a cold outlet for outflow of the cold fluid; and a heat exchanger core including: a first partition defining a first set of hot fluid channels and a first set of cold fluid channels, the first partition including at least a first boundary common to both the first set of hot fluid channels and the first set of cold fluid channels, the first common boundary being configured to facilitate a first heat exchange between the hot fluid and the cold fluid; a second partition defining a second set of hot fluid channels and a second set of cold fluid channels, the second partition including at least a second boundary common to both the second set of hot fluid channels and the second set of cold fluid channels, the second common boundary being configured to facilitate a second heat exchange between the hot fluid and the cold fluid, and wherein: the first set of hot fluid channels is fluidly connected to the second set of hot fluid channels; the first set of cold fluid channels is fluidly connected to the second set of cold fluid channels; and an area of the second boundary is selectedto be larger than an area of the first boundary, which causes the first heat exchange being about equal to the second heat exchange.

[0158] Aspect 11 includes the heat exchanger of any of aspects 10, wherein both the first partition and the second partition form a semi-periodic three-dimensional lattice structure.

[0159] Aspect 12 includes the heat exchanger of any of aspects 10-11, further comprising a hot fluid inflow manifold for fluidly coupling the hot inlet to the set of hot fluid channels, the hot fluid inflow manifold configured to have a cross-sectional area larger than a cross-sectional area of the hot inlet causing a temperature decrease of the hot fluid within the hot fluid inflow manifold.

[0160] Aspect 13 includes the heat exchanger of any of aspects 10-12, wherein a measure of a curvature of the second partition is larger than a measure of a curvature of the first partition.

[0161] Aspect 14 includes the heat exchanger of any of aspects 10-13, wherein: a first ratio of a volume occupied by the first set of cold fluid channels to a volume occupied by the first set of hot fluid channels is smaller than a second ratio of a volume occupied by the second set of cold fluid channels to a volume occupied by the second set of hot fluid channels.

[0162] Aspect 15 includes the heat exchanger of any of aspects 10-14, wherein a ratio of a cross-sectional area occupied by the first set of cold fluid channels to a cross-sectional area occupied by the second set of cold fluid channels is greater than one.

[0163] Aspect 16 relates to a heat exchanger including an enclosure, the enclosure comprising: a hot inlet for inflow of a hot fluid; a hot outlet for outflow of the hot fluid; a cold inlet for inflow of a cold fluid; a cold outlet for outflow of the cold fluid; and a heat exchanger core including a partition defining a set of hot fluid channels and a set of cold fluid channels, the partition including at least a boundary common to both the hot and the cold fluid channels, the common boundary being configured to facilitate a heat exchange between the hot fluid and the cold fluid, and wherein: at least one cold fluid channel from the set of cold fluid channels forms a set of branches within a region of the heat exchanger core; and a number of the branches of the at least one cold fluid channel is proportional to a decrease in a temperature difference between the cold fluid and the hot fluid within that region as compared to a temperature difference between the cold fluid at the cold fluid inlet and the hot fluid at the hot fluid outlet.

[0164] Aspect 17 includes the heat exchanger of any of aspects 16, wherein each one of the set of branches defines a segment of the at least one cold fluid channel, and wherein a number ofsegments of the at least one cold fluid channel increases along an extension of the at least one cold fluid channel in a direction from the cold inlet to the cold outlet.

[0165] Aspect 18 includes the heat exchanger of any of aspects 16-17, wherein at least one hot fluid channel from the set of hot fluid channels includes branches, each branch defining a segment of the at least one hot fluid channel, and wherein a number of segments of the at least one hot fluid channel increases along an length of the at least one hot fluid channel in a direction from the hot inlet to the hot outlet.

[0166] Aspect 19 includes the heat exchanger of any of aspects 16-18, further comprising a cold fluid inflow manifold for fluidly coupling the cold inlet to the set of cold fluid channels, the cold fluid inflow manifold comprising a cavity extending at least partially through the heat exchange core, the cavity having a plurality of openings each one connecting the cavity with a corresponding one of the cold fluid channels.

[0167] Aspect 20 includes the heat exchange of any of aspects 16-19, wherein a cold fluid channel from the set of cold fluid channels, having a channel cross-sectional area, is configured to split into a first branch having a first branch cross-sectional area and a second branch having a second branch cross-sectional area, and wherein the channel cross-sectional area raised in a preset power is about equal to a sum of the first branch cross-sectional area raised in the preset power and the second branch cross-sectional area raised in the preset power.

[0168] Aspect 21 includes the heat exchange of any of aspects 16-20, wherein the preset power has a value of about three.

[0169] Aspect 22 includes the heat exchanger of any of aspects 16-21, further comprising a cold fluid outflow manifold for fluidly coupling the set of cold fluid channels to the cold inlet, the cold fluid outflow manifold configured to have a cross-sectional area larger than a cross-sectional area of the cold outlet, causing a temperature decrease of the cold fluid within the cold outlet.

[0170] Regarding the preceding description, it is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the shape, size, and arrangement of parts without departing from the scope of the present disclosure. This specification and the embodiments described are exemplary only, with the true scope and spirit of the disclosure indicated by the claims that follow.

Claims

CLAIMSWhat is claimed is:

1. A heat exchanger comprising: an enclosure including a hot inlet for inflow of a hot fluid, a hot outlet for outflow of the hot fluid, a cold inlet for inflow of a cold fluid, and a cold outlet for outflow of the cold fluid; and a heat exchanger core including a plurality of partitions forming a set of hot fluid channels and a set of cold fluid channels, wherein each of the partitions is defined by a wall common to adjacent hot and cold fluid channels, the wall defining a continuous, thermally conductive boundary between adjacent hot and cold fluid channels to facilitate a heat exchange between a hot fluid and a cold fluid flowing within adjacent hot and cold fluid channels, and wherein the plurality of partitions and the sets of hot and cold fluid channels define a three-dimensional lattice structure including multiple cells having a Y:X aspect ratio.

2. The heat exchanger of claim 1, wherein the walls defining the partitions have a constant curvature along a length of the heat exchanger core.

3. The heat exchanger of claim 2, wherein a curvature of the walls defining the partitions increases along a length of the heat exchanger core in a direction from the cold inlet to the cold outlet.

4. The heat exchanger of claim 1 , wherein a ratio between a cross-sectional area of the set of cold fluid channels and the set hot fluid channels is fixed along a length of the heat exchanger core.

5. The heat exchange of claim 1, wherein a ratio between a cross-sectional area of the set of cold fluid channels and the set hot fluid channels changes along a length of the heat exchanger core.

6. The heat exchanger of claim 1, wherein the cross-sectional area of the hot fluid channels is greater than the cross-sectional areas of the cold fluid channels.

7. The heat exchanger of claim 1, wherein a Y:X aspect ratio of the multiple cells ranges from 1:1 to 4:1.

8. The heat exchanger of claim 1, wherein a Y:X aspect ratio of the multiple cells increases along an extension of the heat exchanger core.

9. The heat exchanger of claim 1, further comprising first and second regions including multiple cells having a first Y:X aspect ratio and a transition region disposed between the first and second regions, the transition region including multiple cells having a second Y:X aspect ratio.

10. The heat exchanger of claim 9, wherein the second Y :X aspect ratio is greater than the first Y:X aspect ratio.

11. The heat exchanger of claim 1, wherein the walls defining the plurality of partitions includes a roughness, wherein the roughness creates a turbulent flow within a fluid channel adjacent to the wall.

12. The heat exchanger of claim 1 , wherein the walls defining the plurality of partitions vary in at least one of a thickness and a material along a length of the heat exchanger.

13. The heat exchanger of claim 1, further comprising a cold fluid outflow manifold for fluidly coupling the set of cold fluid channels and the cold outlet, the cold fluid outflow manifold having a cross-sectional area that is greater than a cross-sectional area of the cold outlet causing a temperature decrease of the cold fluid flowing within the cold fluid outlet.

14. A gas purification system comprising a feed gas inlet, a purified gas outlet, a heater, a purifier, and at least one heat exchanger according to claim 1.

15. The gas purification system of claim 14, including two or more heat exchangers, wherein the two or more heat exchangers are arranged in parallel.

16. The gas purification system of claim 14, including two or more heat exchangers, wherein the two or more heat exchangers are arranged in series.

17. A method of manufacturing a heat exchanger comprising: forming an enclosure and a heat exchanger core by an additive manufacturing process, the heat exchanger core including a plurality of partitions forming a set of hot fluid channels and a set of cold fluid channels, wherein each of the partitions is defined by a wall common to adjacent hot and cold fluid channels, the wall defining a continuous, thermally conductive boundary between adjacent hot and cold fluid channels to facilitate a heat exchange between a hot fluid and a cold fluid flowing within adjacent hot and cold fluid channels, andwherein the plurality of partitions and the sets of hot and cold fluid channels define a three-dimensional lattice structure including multiple cells having a Y:X aspect ratio, and wherein an aspect ratio of the multiple cells in at least one region of the heat exchanger core is controlled during the additive manufacturing process to achieve a predetermined pressure drop for at least one of a hot fluid outlet or a cold fluid outlet of the heat exchanger.

18. A heat exchanger including an enclosure, the enclosure comprising: a hot inlet for inflow of a hot fluid; a hot outlet for outflow of the hot fluid; a cold inlet for inflow of a cold fluid; a cold outlet for outflow of the cold fluid; and a heat exchanger core including a partition defining a set of hot fluid channels and a set of cold fluid channels, the partition including at least a boundary common to both the hot and the cold fluid channels, the common boundary being configured to facilitate a heat exchange between the hot fluid and the cold fluid, wherein at least one cold fluid channel from the set of cold fluid channels forms a set of branches within a region of the heat exchanger core and a number of the branches of the at least one cold fluid channel is proportional to a decrease in a temperature difference between the cold fluid and the hot fluid within that region as compared to a temperature difference between the cold fluid at the cold inlet and the hot fluid at the hot outlet.

19. The heat exchanger of claim 18, wherein at least one hot fluid channel from the set of hot fluid channels includes branches, each branch defining a segment of the at least one hot fluid channel, and wherein a number of segments of the at least one hot fluid channel increases along an length of the at least one hot fluid channel in a direction from the hot inlet to the hot outlet.

20. The heat exchange of claim 18, wherein a cold fluid channel from the set of cold fluid channels, having a channel cross-sectional area, is configured to split into a first branch having a first branch cross-sectional area and a second branch having a second branch cross-sectional area, and wherein the channel cross-sectional area raised in a preset power is about equal to a sum of the first branch cross-sectional area raised in the preset power and the second branch cross- sectional area raised in the preset power.

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