Common core multi-flow microtube heat exchanger

Abstract

A microtube heat exchanger of an aerospace heat transfer system including a plurality of microtubes substantially aligned to form a microtube stack for carrying working fluid, the microtube stack including a working fluid inlet and a working fluid outlet; an inlet header fluidly coupled with the working fluid inlet and an outlet header fluidly coupled with the working fluid outlet; and a shell substantially surrounding the microtube stack. Where the shell is configured to allow for carrying shell-side fluid past an outside of the plurality of microtubes. Where at least one of (i) the shell is segregated by an inner barrier to allow for the flow of two segregated shell- side fluid flow paths, and (ii) the inlet header is sectioned to allow for two segregated working fluid flow paths through the microtube stack.

Description

Common Core Multi-Flow Microtube Heat Exchanger Inventors: Tony Ho, Nathan A. Lord, and Cole SorensonCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of the filing date of U.S. Provisional Application Serial No. 63 / 382,315, filed on November 4, 2022, entitled “Common Core MultiFlow Microtube Heat Exchanger”, the entire disclosure of which is hereby incorporated by reference into the present disclosure.FIELD OF THE INVENTION

[0002] The present invention relates generally to heat exchangers, and more particularly to microtube heat exchangers having multiple tube-side and / or shell-side flow channels each defining a distinct and separate fluid flow path.BACKGROUND OF THE INVENTION

[0003] Heat management has long-been a critical issue in the aerospace industry and has only grown more complex in recent years as new innovations in the industry have increased the need for efficient and dependable heat exchange systems. Traditionally, designing improved heat exchangers capable of handling the increased capacity and efficiency demands has often required building larger and heavier heat exchangers. Of course, in aerospace systems where available space and payload is limited, incorporating bigger and heavier heat exchangers is undesirable, or even impossible, based on the fixed size constraints.

[0004] Accordingly, there has been a long-felt need in the aerospace industry for heat exchangers that efficiently manage the increased thermal load demands of new aerospaceinnovations that are also reduced in size and weight when compared to traditional heat exchangers.BRIEF SUMMARY OF THE INVENTION

[0005] To address the above-discussed need for heat exchangers with improved efficiency and thermal load capabilities at a reduced size and weight, various embodiments of the inventions herein are related to a multi-flow common core microtube heat exchanger for use in aerospace systems. The heat exchanger includes a tube stack comprising a plurality of microtubes for carrying working fluid through the heat exchanger. The heat exchanger further includes a shell through which shell-side fluid flows through the shell outside of the tube stack. According to various embodiments of the disclosure, at least one of the shell and tube stack is adapted to provide for multiple distinct and fluidly segregated flow paths of shell-side fluid or working fluid. According to some embodiments of the disclosure, the shell comprises a barrier separating the shell into two separate volumes, each volume completely segregated from the other by the barrier and each configured to facilitate the flow of a different shell-side fluid. According to some embodiments, the tube stack can be coupled with two separate and fluidly segregated inlets to form two segregated working fluid flow paths through the tube stack to facilitate the flow of a different working fluid through each flow path.

[0006] According to various embodiments of this disclosure is a microtube heat exchanger, including a plurality of microtubes substantially aligned to form a microtube stack for carrying working fluid, the microtube stack including a working fluid inlet and a working fluid outlet; an inlet header fluidly coupled with the working fluid inlet and an outlet header fluidly coupled with the working fluid outlet; and a shell substantially surrounding the microtube stack and configured to allow for carrying shell-side fluid past an outside of the plurality ofmicrotubes. Where at least one of: (i) the shell is segregated by an inner barrier to allow for a first shell-side passageway and a second shell-side passageway fluidly segregated from the first shell-side passageway, an (ii) the inlet header is sectioned to allow for two segregated working fluid flow paths through the microtube stack.

[0007] According to various embodiments of this disclosure, the microtube heat exchanger is part of an environmental control system (ECS) of an aerospace vehicle. According to various embodiments of this disclosure, the microtube heat exchanger is configured to perform the function of a reheater and a condenser of a traditional ECS such that a fluid inlet of the first shell-side fluid passageway (the “condenser”) is coupled with an outlet of a turbine of an air cycle machine of the ECS; and an outlet of the first shell-side fluid passageway (the “condenser”) is coupled with a mixing manifold or an air-conditioned cabin of the aerospace vehicle.

[0008] According to various embodiments of this disclosure is a microtube heat exchanger in which each of the first and second shell-side passageways includes a shell-side fluid inlet and a shell-side fluid outlet to allow for fluidly segregated flows of a first shell-side fluid through the first shell-side passageway and a second shell-side fluid through the second shell-side passageway. According to various embodiments of this disclosure is a microtube heat exchanger in which the barrier is a plate with a first side defining part of the first shell-side passageway and a second side defining part of the second shell-side passageway. According to various embodiment of this disclosure is a microtube heat exchanger in which the microtube stack further includes a stack first section disposed in the first shell-side passageway and a stack second section disposed in the second shell-side passageway; and the barrier includes an innervolume fluidly coupled with the stack first section and stack second section so as to communicate working fluid between the stack first and second sections.

[0009] According to various embodiments of this disclosure, the microtube heat exchanger is configured to perform the function of a primary and a secondary heat exchanger of a traditional Air Cycle ECS of an aerospace vehicle such that an inlet of one of the two segregated working fluid flow paths of the tube stack is configured to receive engine bleed from an engine of the aerospace vehicle; and an inlet of the other of the two segregated working fluid flow paths of the tube stack is configured to receive air discharged from a compressor of an air cycle machine of the ECS. The working fluid flow path of the shell side of the heat exchanger is configured to receive ram air. According to various embodiments of this disclosure is a microtube heat exchanger in which the outlet header is sectioned analogously to the inlet header in order to maintain the segregation of the two segregated working fluid flow paths through the outlet header. According to various embodiments of this disclosure is a microtube heat exchanger in which the outlet header is configured to act as a mixer and combine the working fluids that traveled through the two segregated working fluid flow paths before discharging the working fluids from an outlet port of the outlet header. According to various embodiments of this disclosure is a microtube heat exchanger in which the inlet header includes a first fluid inlet for accepting a first working fluid and fluidly coupled with a first flow path of the two fluidly segregated working fluid flow paths; and a second fluid inlet for accepting a second working fluid and fluidly coupled with a second flow path of the two fluidly segregated working fluid flow paths. According to various embodiments of this disclosure is a microtube heat exchanger in which the outlet header includes a first fluid outlet for accepting the first working fluid of thefirst flow path; and a second fluid outlet for accepting the second working fluid of the second flow path.

[0010] According to various embodiments of this disclosure is a microtube heat exchanger further including an inlet stack end plate coupled with an inlet end of each of the plurality of microtubes; and an outlet stack end plate coupled with an outlet end of each of the plurality of microtubes, wherein the inlet header is mounted to the inlet stack end plate and the outlet header is mounted to the outlet stack end plate. According to various embodiments of this disclosure is a microtube heat exchanger in which each of the plurality of microtubes is coupled to the inlet stack end plate and outlet stack end plate by laser welding. According to various embodiments of this disclosure is a microtube heat exchanger in which each of the plurality of microtubes is coupled with the barrier by laser welding.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 illustrates a perspective view of an aerospace vehicle including microtube heat exchangers with multiple shell-side and / or tube-side flow paths, according to an embodiment of this disclosure.

[0012] Fig. 2 illustrates a cutaway view of a microtube heat exchanger with multiple shell-side flow paths for multiple distinct shell-side fluids, according to an embodiment of the disclosure.

[0013] Fig. 3 illustrates a cutaway view of a microtube heat exchanger with multiple shell-side flow paths for multiple distinct shell-side fluids, according to another embodiment of the disclosure.

[0014] Fig. 4 illustrates a cutaway view of a microtube heat exchanger with multiple tube-side flow paths for multiple distinct tube-side fluids, according to an embodiment of this disclosure.

[0015] Fig. 5 illustrates a cutaway view of a microtube heat exchanger with multiple tube-side flow paths for multiple distinct tube-side fluids, according to another embodiment of this disclosure.

[0016] Fig. 6 is a schematic illustrating a traditional water separation system of an environmental control system (ECS) of an aerospace vehicle, according to known embodiments in the art.

[0017] Fig. 7 is a schematic illustrating a water separation system of an ECS of an aerospace vehicle, according to an embodiment of this disclosure.

[0018] Fig. 8 is a schematic illustrating a subcooler-condenser heat exchange system, according to an embodiment of this disclosure.

[0019] Fig. 9 is a flowchart illustrating a method of providing heat transfer for multiple distinct fluid flow paths with a heat exchanger, according to an embodiment of this disclosure.DETAILED DESCRIPTION OF THE INVENTION

[0020] The following descriptions relate to presently preferred embodiments and are not to be construed as describing limits to the invention, whereas the broader scope of the invention should instead be considered with reference to the claims, which may be now appended or may later be added or amended in this or related applications. Unless indicated otherwise, it is to be understood that terms used in these descriptions generally have the same meanings as those that would be understood by persons of ordinary skill in the art. It should also be understood that terms used are generally intended to have the ordinary meanings that would be understood withinthe context of the related art, and they generally should not be restricted to formal or ideal definitions, conceptually encompassing equivalents, unless and only to the extent that a particular context clearly requires otherwise.

[0021] For purposes of these descriptions, a few wording simplifications should also be understood as universal, except to the extent otherwise clarified in a particular context either in the specification or in particular claims. The use of the term “or” should be understood as referring to alternatives, although it is generally used to mean “and / or” unless explicitly indicated to refer to alternatives only, or unless the alternatives are inherently mutually exclusive. When referencing values, the term “about” may be used to indicate an approximate value, generally one that could be read as being that value plus or minus half of the value. “A” or “an” and the like may mean one or more, unless clearly indicated otherwise. Such “one or more” meanings are most especially intended when references are made in conjunction with open-ended words such as “having,” “comprising” or “including.” Likewise, “another” object may mean at least a second object or more.

[0022] The following descriptions relate principally to preferred embodiments while a few alternative embodiments may also be referenced on occasion, although it should be understood that many other alternative embodiments would also fall within the scope of the invention. It should be appreciated by those of ordinary skill in the art that the techniques disclosed in these examples are thought to represent techniques that function well in the practice of various embodiments, and thus can be considered to constitute preferred modes for their practice. However, in light of the present disclosure, those of ordinary skill in the art should also appreciate that many changes can be made relative to the disclosed embodiments while stillobtaining a comparable function or result without departing from the spirit and scope of the invention.

[0023] Fig 1 illustrates an aircraft 10 including microtube heat exchangers 100, 200, 300, 400 according to various embodiments of this disclosure. As will be discussed in greater detail below, heat exchangers 100, 200, 300, 400 incorporate multiple shell-side fluid and / or working fluid flow paths, which enables a single heat exchanger 100, 200, 300, 400 to be used in place what would traditionally require multiple heat exchangers. As will be discussed in greater detail below, heat exchangers 100, 200, 300, 400 can be used in various and widespread heat exchange systems of aircraft 10. Although Fig. 1 depicts an aircraft 10, those with skill in the art will understand that, according to various embodiments of this disclosure, heat exchangers 100, 200, 300, 400 are incorporated into various aerospace systems and vehicles, including systems of both aircraft and spacecraft.

[0024] Fig. 2 illustrates a cutaway view of a microtube heat exchanger 100 according to an embodiment of this disclosure. Heat exchanger 100 includes an outer shell 102 with two shellside fluid flow inlet ports 104, 106 and two shell-side fluid flow outlet ports 108, 110. Those with skill in the art will understand that, although ports 104, 106 are described as “inlets” and ports 108, 110 are described as “outlets”, each of the ports 104, 106, 108, 110 can be used as either a fluid inlet or a fluid outlet. Heat exchanger 100 further includes a leak-tight barrier 112 which fluidly segregates an interior of shell 102 into two separate, fluidly distinct shell-side fluid volumes 114, 116. Heat exchanger 100 further includes a microtube tube stack 118 comprising a plurality of microtubes 120 for carrying a working fluid of the heat exchanger 100. Heat exchanger 100 further includes an inlet header 122 coupled with an inlet side of tube stack 118 and configured to provide the working fluid to be carried within the microtubes 120 of the tubestack 1 18, and an outlet header 124 coupled with an outlet side of the tube stack 118 and configured to discharge processed working fluid from tube stack 118 to an exterior of heat exchanger 100.

[0025] Tube stack 118 contains a plurality of microtubes 120, and, in some embodiments, even contains dozens, hundreds, thousands or even tens of thousands of microtubes 120. An external fluid flows past an outer surface of the plurality of microtubes 120 (“shell-side”) to cool or heat the working fluid flowing internally through the plurality of microtubes 120 (“tube-side”). In liquid-cooled / heated heat exchangers, the external fluid is a liquid, such as for example water or a coolant in some embodiments. In gas-cooled / heated heat exchangers, the external fluid is a gas, such as for example air in some embodiments. Microtubes 120 each have an inner diameter (ID) that are measurable on a microinch or micrometer scale. For example, in some preferred embodiments, each microtube 120 has an ID of substantially 0.003-0.10 inch, an outer diameter (OD) of 0.01-0.15 inch, and / or a wall thickness of 0.0018- 0.01 inches. Those with skill in the art will understand that microtubes 120 can have IDs, ODs, and wall thicknesses less or greater than what has been described without departing from the scope of this disclosure. As previously discussed, in some embodiments of the disclosure, there are several thousand microtubes 120 in tube stack 118. For example, in one embodiment, the tube stack 118 has 6,700 microtubes 120. Other embodiments of this disclosure include tube stacks 118 ranging anywhere from 500 to 55,000 microtubes 120. In some embodiments, microtubes 120 are bundled to have a tube density of 700 - 1,100 microtubes 120 per square inch. Each tube 120 can be made using any of a number of commonly used methods, such as by being rolled and seam-welded, extruded, electroformed, or centerless ground. In some embodiments, tubes 120 are made from stainless steel alloys, such as 304 stainless steel or 316stainless steel, for example. However, microtubes 120 can be made from any of a number of materials, such as, for example, super alloys (such as Inconel), titanium, or aluminum.

[0026] Tube stack 118 further comprises an inlet endplate 121 and an outlet endplate 123 which are coupled with each of the plurality of tubes 120, the shell, inlet header 122 and outlet header 124. Each endplate 121, 123 has a plurality of through holes each aligned with one of the plurality of microtubes 120 so that tube-side fluid can pass between the headers 122, 124 and the plurality of microtubes 120. The endplates 122, 124 are coupled with each of the plurality of microtubes 120 by welding, laser welding, brazing, epoxying, soldering, or any of numerous other leak-tight coupling method. Each header 122, 124 is coupled to its corresponding endplate 121, 123 by any of a number of methods, such as, for example, by fasteners or by welding.

[0027] The working fluid used with heat exchanger 100 can be any working fluid typically used in heat exchangers. For example, according to various embodiments, heat exchanger 100 can be part of a vapor-compression system and the working fluid can be a refrigerant, such a R134a or R1233zd(E) refrigerant, for example. In other embodiments, heat exchanger 100 can be part of a non-compressive heating or cooling system where the working fluid is any of a number of liquids, such as a coolant liquid (such as Polyethylene-Glycol or Ethylene-Glycol water mixture or oils such as Polyalphaolefin) or water, for example. Still in other embodiments, heat exchanger 100 can be used in a system where the working fluid is gaseous, such as in system that incorporates air, ram air, or another gas as the working fluid.

[0028] The shell-side fluid that passes from shell inlets 104, 106 to shell outlet 108, 1 10 shell-side of tube stack 118 can be any of a number of gasses or liquids typically used in heat exchange operations. For example, the shell-side fluid can be water, a liquid coolant, or air that is drawn past the shell-side of tube stack 118 for heat exchange with the working fluid flowingtube-side of the tube stack 118. Tn some embodiments, heat exchanger 100 is configured to act as a cooler or an evaporator in which heat is transferred from the shell-side fluid to the working fluid on the tube-side and thus the shell-side fluid is cooled by the tube stack 118. In some embodiments, the heat exchanger 100 is configured to act as a heater or a condenser in which heat is transferred from the working fluid on the tube-side to the shell-side fluid and thus the shell-side fluid is heated by the tube stack 118.

[0029] As previously discussed, a primary implementation of heat exchanger 100 is in aerospace and aircraft systems. Accordingly, many aspects of the invention herein are best understood within aerospace systems. For example, according to various embodiments of the current disclosure, the shell-side fluid is ram air from a ram air system of the aircraft 10.

[0030] As previously mentioned, barrier 112 fluidly segregates the interior of shell 102 into two separate volumes 114, 116. First volume 114 is fluidly coupled with inlet 104 and outlet 108, and second volume 116 is fluidly coupled with inlet 106 and outlet 110. Accordingly, in some embodiments, two different shell-side fluids can be used in heat exchanger 100: a first shell-side fluid passing through volume 114 and a second shell-side fluid passing through volume 116. Due to barrier 112 being a leak-tight seal, there is no concern of intermingling of the two shell-side fluids. In some embodiments, barrier 112 can be a plate with holes through which each of the plurality of microtubes 120 passes, and the holes of the barrier 112 can be sealed around the microtubes 120 by welding, laser welding, brazing, epoxying, soldering, or any other leak -tight sealing method between the plurality of microtubes 120 and the barrier 1 12. In other embodiments, the tube stack can comprise of two separate pieces; a first piece disposed in first volume 114 and a second piece disposed in volume 116. Each microtube 120 of each piece of the tube stack 118 can be welded directly to the holes of the barrier 112 to be fluidly coupledwith a corresponding microtube tube 120 of the other piece. Further, although the present disclosure illustrates a single barrier creating two volumes 114, 116 for two shell-side flow paths, other embodiments of the disclosure include heat exchangers with multiple barriers and thus more than two volumes to allow for more than two shell-side flow paths.

[0031] Fig. 3 illustrates a cutaway view of heat exchanger 200. Those with skill in the art will understand that, in many respects, heat exchanger 200 is substantially the same as heat exchanger 100 previously described. Heat exchanger 200 includes a shell 202 (substantially the same as shell 102) with inlet ports 204, 206 and outlet ports 208, 210 (substantially the same as inlet ports 104, 106 and outlet ports 108, 110). Heat exchanger 200 further includes an inlet header 222 and an outlet header 224 (substantially the same as inlet header 122 and outlet header 124) fluidly coupled with a tube stack 218 comprising endplates 221, 223 and a plurality of microtubes 220 (substantially the same as tube stack 118, endplates 121, 123, and microtubes 120). Heat exchanger also includes two segregated shell-side volumes 214, 216 (substantially the same as volumes 114, 116).

[0032] However, different from heat exchanger 100, to create the volumes 214, 216, heat exchanger 200 employs a leak-tight compartment 212. Unlike barrier 112, which was a plate separating volumes 114, 116, compartment 212 includes an internal volume that is fluidly coupled with inner ends of each of a first tube stack section 218a disposed in first volume 214 and a second tube stack section 218b disposed in second volume 216. Thus, an inner end of each microtube 220 of first tube stack section 218a is fluidly coupled to compartment 212 by any of a number of leak tight methods, such as welding. An inner end of each microtube 220 of second tube stack section 218b is fluidly coupled to compartment 212 by any of a number of leak tight methods, such as welding. As working fluid flows through the tube stack 218, it first flowsthrough microtubes 220 of first tube stack 218a and is discharged into the internal volume of compartment 212 where the working fluid can flow freely within the compartment 212. The working fluid then travels from compartment 212 through microtubes 220 of second tube stack section 218b and is discharged from outlet header 224.

[0033] Those with skill in the art will understand that, according to some embodiments, heat exchanger 100 may be preferred over heat exchanger 200 for any of a number of reasons. For example, when heat exchanger 200 is used, there likely will be some additional fluid pressure losses due to sudden expansion and contraction of the fluid into and out of the volume within compartment 212 that may be undesirable. These sudden contraction and expansion losses are due to recirculating zones near the sharp corners as opposed to slow, gradual diffusion that would mitigate these dynamic losses. Heat exchanger 100 uses barrier 112 rather than compartment 212, and thus refrigerant going through tube stack 118 is not subjected to any sudden expansion or contraction type losses. In addition, in some embodiments, compartment 212 requires a larger installation footprint as well as weight impact compared to the barrier plate 112 option.

[0034] Those with skill in the art will understand that, according to some embodiments, heat exchanger 200 may be preferred over heat exchanger 100 for any of a number of reasons. For example, in some scenarios, heat exchanger 200 may provide benefits when contemplating engineering and manufacturing considerations. Because compartment 212 is used to separate two separate sections of the tube stack 218a, 218b, it may be easier to ensure leak-tight sealing between the compartment and the tube stack 218. Further, heat exchanger 200 allows for more flexibility in the tube stack sections 218a, 218b utilized. For example, in some embodiments, section 218a may incorporate microtubes 220 that are different in size, number, concentration,spacing, or orientation of the microtubes 220 of section 218b. Thus, sections 218a and 218b are capable of being “mixed and matched” depending on the heat transfer requirements with the shell-side fluid flowing through each volume 214, 216.

[0035] Fig. 4 illustrates a heat exchanger 300 according to another embodiment of this disclosure. Different from the heat exchangers previously discussed, instead of allowing for multiple shell-side flow paths, heat exchanger 300 allows for multiple tube-side working fluid flow paths through the heat exchanger 300 that transfer heat with a common shell-side fluid.

[0036] Heat exchanger 300 includes a shell 302 with a shell-side fluid inlet 304 and a shell-side fluid outlet 306. Heat exchanger 300 further includes an inlet header 308 with a first fluid inlet 310, a second fluid inlet 312, and coupled with a tube stack endplate 314. Endplate 314 is coupled with header 308 and the plurality of microtubes 318, 322 in substantially the same way as endplates 121 discussed above. First inlet 310 is configured to receive a working fluid from a first source and second inlet 312 is configured to receive a working fluid from a second source. First inlet 310 and 312 are completely fluidly segregated from each other to ensure no intermingling of different working fluids within the header 308.

[0037] First inlet 310 is fluidly coupled with a first section of end plate 314 aligned with a first tube stack 316 which contains a plurality of microtubes 318. End plate 314 has a plurality of through holes, and an inlet end of each microtube 318 is fluidly coupled with one of the plurality of through holes so that working fluid can flow from inlet 310 into the plurality of microtubes 318. Similarly, second inlet 312 is fluidly coupled with a second section of end plate 314 aligned with a second tube stack 320 which contains a plurality of microtubes 322. End plate 314 has a plurality of through holes, and an inlet end of each microtube 322 is fluidly coupled with one of the plurality of through holes so that working fluid can flow from inlet 312 into theplurality of microtubes 322. As previously discussed, inlets 310 and 312 are fluidly segregated from each other, so, accordingly, holes of end plate 314 coupled with microtubes 318 are only fluidly coupled with inlet 310, and holes of end plate 314 coupled with microtubes 322 are only fluidly coupled with inlet 312. Although a single inlet header 308 is depicted and described in Fig. 4, those with skill in the art will understand that, according to other embodiments of this disclosure, header inlets 310 and 312 are completely separate from one another and not combined in a single header. Microtubes 318, 322 are substantially the same as microtubes 120 previously described.

[0038] Heat exchanger 300 further includes an outlet header 324. Those with skill in the art will understand that outlet header 324 is substantially the same as inlet header 308 previously described, but is instead used to discharge first and second working fluid flows from the heat exchanger. Specifically, header 324 includes a first outlet 328 configured to receive and discharge the first working fluid flowing through tube stack 316, and a second outlet 330 configured to receive and discharge the second working fluid flowing through tube stack 320. Similar to inlets 310, 312 previously described, outlets 328 and 330 are coupled to end plate 332 to be fluidly segregated from one another to prevent any intermingling between the first and second working fluids. Those with skill in the art will understand that a first working fluid flow path 334 can be defined as comprising inlet 310, tube stack 316, and outlet 328; and that a second working fluid flow path 336 can be as comprising inlet 312, tube stack 320, and outlet 330. Those with skill in the art will understand that, although ports 310, 312 are described as “inlets” and ports 328, 330 are described as “outlets”, each of the ports 310, 312, 328, 330 can be used as either a fluid inlet or a fluid outlet.

[0039] Heat exchanger 300 allows for two separate and segregated working fluid flow paths 334, 336 through a single shell 302. Thus, heat exchanger 300 allows for two separate working fluids to exchange heat with a common shell-side fluid. Those with skill in the art will recognize the many benefits afforded by this configuration, especially in the aerospace industry. For example, many heat exchangers in aircraft systems utilize ram air for shell-side fluid. However, access to ram air inlets or the amount or ram air ducting are often limited. Accordingly, heat exchanger 300 is beneficial in that a single ram air inlet can be coupled with inlet 304 and be easily provided for heat exchange with two different working fluids of two different heat exchange systems.

[0040] Working fluid used for heat exchanger 300 can be any of the working fluids that have been previously described. Heat exchanger 300 can allow for working fluid of different types. For example, a refrigerant working fluid of a vapor-compression system can flow through flow path 334, and a coolant fluid of a different system can flow through flow path 336. Further, in some embodiments, a gaseous working fluid flows through one of the flow paths 334, 336 and a liquid working fluid flows through the other flow path 334, 336.

[0041] Although heat exchanger 300 is depicted as providing heat exchange for two different flow paths 334, 336, those with skill in the art will understand that other embodiments of this disclosure incorporate more than two flow paths, and thus provide heat exchange for more than two heat exchange systems with a common shell-side fluid.

[0042] According to various embodiments, and as illustrated, each header 308, 324 has multiple inlets 310, 312 or outlets 328, 330 that are fluidly segregated from each other according to a sealing strategy of its respective header 308, 324. However, those with skill in the art will understand that other embodiments fall within the scope of this disclosure. For example,according to some embodiments, there is a separate inlet header for each inlet fluid 310, 312 and / or a separate outlet header for each fluid outlet 328, 330. Those with skill in the art will recognize that having multiple inlet and / or outlet headers for each working fluid may be desirable for various reasons. For example, in some embodiments, when dealing with working fluids at extreme temperatures, it may be desirable for each inlet 310, 312 to have its own header mounted to the heat exchanger 300 for reasons related to thermal growth and expansion. In other embodiments, maintaining a desired temperature of the tube-side working fluids at the inlet of the tube stack 316, 320 may be critical, and potential heat transfer between the two working fluids in a shared, segregated header 308 may be undesirable. In these embodiments, it may be desirable for each inlet 310, 312 to have its own header mounted to the heat exchanger 300 to limit any potential heat transfer of the working fluids.

[0043] Fig. 5 illustrates heat exchanger 400 according to another embodiment of this disclosure. Heat exchanger 400 is substantially similar to heat exchanger 300 previously described, as heat exchanger 400 also allows for two separate and segregated working-fluid flow paths through a single shell volume. Similar to heat exchanger 300, heat exchanger 400 has a shell 402 with a shell-side flow inlet 404 and outlet 406. Similar to heat exchanger 300, heat exchanger 400 has an inlet header 408 with two tube-side flow inlets 410, 412 fluidly segregated from each other to provide for a segregated flow paths 434, 436 through tube stacks 416, 420 comprised of microtubes 418, 422. Additionally, header 408 is coupled with an endplate 414 of the tube stacks 416, 420.

[0044] However, different from heat exchanger 300, the outlet header 424 of heat exchanger 400 has a single outlet 428. Thus, outlet header 424, which is coupled with an outlet end plate 432 according to any of the methods previously discussed, acts as a mixer to combinethe working fluid carried in flow paths 434 and 436 after being subjected to heat exchange with the shell-side fluid in shell 402. Those with skill in the art will understand that there are various aerospace systems in which mixing of the fluid of flow paths 434, 436 by header 424 is desirable. For example, in some embodiments, an aerospace heat transfer system may circulate a working fluid through the system using multiple compressors disposed in series upstream of heat exchanger 400. In some embodiments, it may be desirable for various reasons (such as, for example, reasons related to system pressure drops, heat transfer rates, and overall system efficiency) to combine the discharged fluid from the multiple compressors after the working fluid has been subjected to heat exchange by heat exchanger 400. In these embodiments, the fluid discharge port of each compressor can be coupled with its own dedicated flow path 434, 436 of heat exchanger 400, and the multiple discharged flows can then be combined in outlet header 424 after being subjected to heat exchange within shell 402. Thus, heat exchanger 400 provides for an efficient means for combining the multiple flow paths in a way that reduces weight and space when compared to traditional methods and systems.

[0045] Various embodiments of this disclosure include heat exchangers that combine various features of heat exchangers 100, 200, 300, 400 described herein. For example, according to various embodiments of this disclosure is a heat exchanger including a shell substantially the same as shell 102 or 202 to allow for multiple segregated shell-side flow paths, and a tube stack assembly that allows for multiple segregated working fluid flow paths, substantially the same as flow paths 334 and 336. Additionally, those with skill in the art will understand that various embodiments in this disclosure will include heat exchangers with more than two distinct working and / or shell-side fluid flow paths. Specifically, for example, although heat exchangers 100, 200 are shown as having two shell-side volumes 114, 116 and 214, 216, respectively, according toother embodiments, heat exchangers have three or more shell-side volumes to allow for three or more segregated shell-side fluid flow paths without departing from the scope of this disclosure. Additionally, for example, although heat exchangers 300, 400 are shown as having two workingfluid flow paths 334, 336 and 434, 436, respectively, according to other embodiments, heat exchangers have three or more working-fluid flow paths without departing from the scope of this disclosure.

[0046] The heat exchangers 100, 200, 300, 400 can be used in various and widespread aerospace applications. Heat exchanger 100, 200, which both allow for multiple shell-side flow paths, can be used in various aircraft heat management systems. For example, heat exchanger 100, 200 can be used as an evaporator where cooled refrigerant passes through the tube stack and is used to cool two different shell-side flow paths and, since the flow paths are segregated, one shell-side flow path can be air used to cool an occupant cabin of aircraft 10, for example, and the other shell-side flow path can be liquid coolant fluid used to cool a liquid cooled system of aircraft 10, such as an electronics system or an engine of aircraft 10, for example. Traditionally, to achieve cooling like this, two heat exchangers would be required, and even if the two heat exchangers were connected in series, the refrigerant would be subjected to sudden expansi on / contracti on as it enters / leaves the heat exchangers. Accordingly, heat exchangers 100, 200 not only reduce the size, weight, and cost of adding additional heat exchangers to thermal management systems, but also offer performance enhancements in eliminating locations of refrigerant expansion / contraction. Those with skill in the art will understand that the application described above is just one of many applications in which heat exchanger 100, 200 can be used, and that heat exchanger 100, 200 can be used in various other evaporator, passive-cooling, condenser, passive-heating, and radiator applications according to various embodiments of thisdisclosure. One such example of an aerospace system incorporating heat exchanger 100, 200 is discussed in greater detail below in describing Fig. 7

[0047] Similarly, heat exchanger 300, 400 can be used in various aerospace heat management systems. Heat exchanger 300 could be used in passive cooling or radiator-type applications. For example, liquid coolant of a first heat exchange system can flow through flow path 334, and engine oil of a second heat exchange system can flow through flow path 336, both of which are cooled by shell-side ram air. In some embodiments, both flow paths 324, 326 are used to carry a same fluid (such as for example, liquid coolant, engine oil, etc.) to be cooled by ram air, and the heat transfer system associated with the heat exchanger which of the flow paths 334, 336 to use in operation. In other words, flow paths 334, 336 can be considered redundant flow paths, and the flow path 334, 336 used by the associated system can be chosen based on any of a number of reasons, such as if one of the flow paths is inoperable or damaged, for example. Those with skill in the art will understand that the applications described above are just some of the many applications in which heat exchanger 300 can be used, and that heat exchanger 300 can be used in various other evaporator, passive-cooling, condenser, passive-heating, and radiator applications according to various embodiments of this disclosure. Examples of aerospace systems incorporating heat exchanger 300 are discussed in greater detail below in describing Figs. 7 and 8.

[0048] Although heat exchangers 100, 200, 300, 400 have largely been described in applications in which a liquid or refrigerant is used as the working fluid, heat exchangers 100, 200, 300, 400 can also be used in application in which gas or air is the working fluid. For example, bleed air from an engine of aircraft 10 or even ram air can be used as the working fluid for 100, 200, 300, 400 for various applications. Further, those with skill in the art will understandthat, according to various embodiments of this disclosure, each heat exchanger 100, 200, 300, 400 can be implemented as a liquid-to-liquid, liquid-to-air, air-to-liquid, air-to-air, refrigerant-to- liquid, or refrigerant-to-air type heat exchanger.

[0049] Fig. 6 is a schematic illustrating a traditional environmental control system (ECS) 500 of an aerospace vehicle. As indicated in Fig. 6, ECS 500 is known in the art, can be considered prior art, and is included herein primarily as a reference for understanding the inventive features of ECS 600, discussed in greater detail below with reference to Fig. 7. For ease of understanding, the solid-line arrows of Fig. 6 represent hot air of the ECS 500, while the broken-line arrows represent cold air.

[0050] As shown, hot air 502, such as engine bleed air, enters the ECS 500 by first entering a primary heat exchanger 504, which is cooled by ram air traveling through a ram air system 506, where the ram air is moved through system 506 by a fan 508 of an air cycle machine 510. The hot air is then processed by a compressor 512 of machine 510 and is passed through a secondary heat exchanger 514 which is also cooled by the ram air of system 506. The air then passes through a reheater 516 where it is cooled before entering condenser 518. The air then enters a water extractor 520 before passing again through reheater 516, this time to be reheated before it enters a turbine 522 of machine 510. The air is then discharged from turbine 522 and is cooled by condenser 518. The cold air is then sent to a mixing manifold 524, where it is mixed with already-treated air, and the then combined cold air is ultimately delivered to a cabin 526 of the aerospace vehicle for cooling the cabin 526.

[0051] Fig. 7 is a schematic illustrating an ECS 600 of an aerospace vehicle, such as vehicle 10, for example. Those with skill in the art will recognize that system 600 has many components substantially similar to the components of system. ECS 600 processes engine bleedair 602 (substantially similar to air 502); includes a ram air system 606 (substantially similar to system 506); includes an air cycle machine 610 with a fan 608, compressor 612, and turbine 622 (substantially similar to machine 510, fan 508, compressor 512, and turbine 522); includes a water extractor 620 (substantially similar to extractor 520); and includes a mixing chamber 624 and cabin 626 (substantially similar to chamber 524 and cabin 526).

[0052] However, ECS 600 has a number of differences from ECS 500 that make ECS 600 favorable over ECS 500 in many respects. First, instead of the traditional primary and secondary heat exchangers 504, 514, ECS 600 can incorporate heat exchanger 300, which performs the same functionality within the system as both of the traditional primary and secondary heat exchangers 504, 514. Referencing Figs. 4 and 7, the ram air acts as the shell-side fluid through heat exchanger 300, and ram air of system 606 enters shell 302 at shell inlet 304, travels past the tube stacks 316, 320, and exits shell 302 at shell outlet 304. As shown, in some embodiments, instead of bleed air entering primary heat exchanger 504, bleed air 602 enters flow path 336 by being coupled with the second tube-side inlet 312, passing through tubes 322 of tube stack 320 where it exchanges heat with the shell-side ram air, and exits the heat exchanger 300 at the second tube-side outlet 330 where it then travels to compressor 612. Thus, flow path 336 is configured to act in the same capacity as a traditional primary heat exchanger in this system. Instead of the air being sent from the compressor to secondary heat exchanger 514, the air from compressor 612 enters flow path 334 by entering first tube-side inlet 310, passing through tubes 318 of tube stack 316 where it exchanges heat with the shell-side ram air, and exiting heat exchanger 300 at first tube-side outlet 328. Thus, flow path 334 is configured to act in the same capacity as a traditional secondary heat exchanger in this system. Those with skill in the art will understand that other embodiments fall within the scope of this disclosure. For example, in someembodiments, the ECS 600 is plumbed such that flow path 334 is configured to act as the traditional primary heat exchanger and flow path 336 is configured to act as the traditional secondary heat exchanger.

[0053] Additionally, instead of a traditional reheater 516 and condenser 518, ECS 600 can incorporate heat exchanger 100 or 200, which performs the same functionality of both reheater 516 and condenser 518. Fig. 7 illustrates ECS 600 incorporating heat exchanger 100, however, those with skill in the art will understand that heat exchanger 200 can be positioned in the same position in ECS 600 as heat exchanger 100. Referencing Figs. 2 and 7, the tube-side fluid of heat exchanger is provided from outlet 328 of heat exchanger 300. As previously discussed, air is discharged from outlet 328 of heat exchanger 300, and is then supplied to tube stack inlet header 122. From there, the air passes through tubes 120 of tube stack 118 and is discharged from outlet header 124. After passing through water extractor 620, the air enters first shell-side volume 114 by an outlet of water extractor 620 being coupled with first shell-side inlet 104. The air then travels through the first volume 114, past the tube stack 118, and is then discharged from outlet 108, which is coupled with turbine 622. Thus, air passing through the first volume 114 is configured to serve the same functionality as a reheater in this system. The air then travels through second volume 116 by an outlet of turbine 622 being coupled with second volume inlet 106. The air travels through the second volume 116, is cooled by traveling past tube stack 120, and is discharged from second volume outlet 110, where it then ultimately travels to cabin 626 for cooling the cabin. Thus, air passing through the second volume 116 is configured to serve the functionality as a condenser in this system. Those with skill in the art will understand that other embodiments fall within the scope of this disclosure. For example, in someembodiments, the ECS 600 is plumbed such that first volume 114 is configured to act as the traditional condenser and second volume 116 is configured to act as the traditional reheater.

[0054] Those with skill in the art will recognize the various advantages presented by ECS 600 over a traditional ECS, such as ECS 500. For example, as has been previously discussed, in aerospace systems, any reductions that can be made to the overall payload and footprint of its internal systems is generally desirable. ECS 600 presents many advantages over traditional systems in terms of weight and space / footprint savings. Instead of having two separate components for the primary and secondary heat exchangers 504, 514, ECS 600 incorporates a single heat exchanger 300 to perform the same functionality. Similarly, instead of having two separate components for the reheater 516 and condenser 518, ECS 600 incorporates a single heat exchanger 100 or 200 to perform the same functionality. By reducing the number of separate components of the system, the weight of the system and space required for the system is reduced. Additionally, the reduction in components can bring other benefits, such as benefits in the system’s efficiency and various benefits related to engineering considerations for the components and the system.

[0055] Fig. 8 illustrates another system of this disclosure incorporating a heat exchanger disclosed herein. Specifically, heat exchanger 300 can be used in a subcooler-condenser heat exchange system 700. In such a system, ram air could be the shell-side fluid and can enter the shell 302 at inlet 304 and be discharged from the shell at outlet 306. For example, according to various embodiments, inlet 304 and outlet 306 can be incorporated with a ram air system substantially similar to system 606 previously discussed. However other types of shell-side fluid could also be used in system 700 such as, for example, a coolant liquid. As shown, refrigerant is cycled by a compressor 704 of the system 700 and, after leaving the compressor 704, passesthrough flow path 336 of heat exchanger 300, which acts as a condenser cooled by the shell-side ram air. Specifically, after exiting compressor 704, the refrigerant enters second tube-side inlet 312, passes through tubes 322 of tube stack 320, and exits the heat exchanger 300 at second tube-side outlet 330. After leaving condenser outlet 330, refrigerant passes through flow-path 334 of heat exchanger 300, which acts as a subcooler cooled by the shell-side ram air. Specifically, after exiting outlet 330, the refrigerant enters first tube-side inlet 310, passes through tubes 318 of tube stack 316, and exits the heat exchanger at first tube-side outlet 328. From there, the refrigerant passes through a throttling valve 701 and an evaporator 702 of the system 700, and returns to compressor 704. Traditionally, a subcooler-condenser heat exchange system would require one heat exchanger to be used as the subcooler and another heat exchanger to be used as the condenser. Accordingly, in system 700, heat exchanger 300 eliminates the need for two separate heat exchanger units and only requires a single shell-side fluid source.

[0056] Fig. 9 is a flowchart illustrating a method of providing heat transfer for multiple distinct fluid flow paths with a heat exchanger of an aerospace heat transfer system, such as with heat exchangers 100, 200, 300, 400. Method 800 can start at block 802 by aligning a plurality of microtubes to form a microtube stack, such as microtube stack 118, 218, 316 & 320, 416 & 420. Method 800 can continue to block 804 by coupling inlet and outlet headers with inlet and outlet ends of the tube stack, such as headers 122 & 124, 222 & 224, 308 & 324, 408 & 424. Method 800 can continue to block 806 by substantially surrounding the microtube stack with a shell for carrying shell-side fluid, such as shell 102, 202, 302, 402. From block 806, method 800 can optionally continue at block 808 by providing a barrier 112, 212 to fluidly segregate the shell to allow for two fluidly segregated shell-side flow paths 114 & 116, 214 & 216. Method 800 can continue at block 810 by passing a first shell-side fluid through the first shell-side fluid path 114,214 and passing a second shell-side fluid through the second shell-side fluid flow path 116, 216 for heat transfer with the working fluid, such as, for example, as described in ECS 600. From block 806, method 800 can optionally continue at block 812 by sectioning the inlet header to provide for two fluidly segregated working fluid flow paths through the tube stack, such header 308 with flow paths 334, 336 and header 408 with flow paths 434, 436. Method 800 can continue to block 814 by passing a first working fluid through the first working fluid flow path 334, 434 and passing a second working fluid through the second working fluid flow path 336, 436 for heat exchange with the shell-side fluid, such as, for example, as described in systems 600, 700.

[0057] Those with skill in the art will understand that, according to various embodiment blocks 808, 810 along with blocks 812, 814 are performed together following blocks 802-806. In other embodiments, only block 808, 810 are performed following blocks 802-806. Still, in other embodiments, only blocks 812, 814 are performed flowing blocks 802-806. Although Fig. 9 depicts blocks 802-814 occurring according to a certain order, those with skill in the art will understand that blocks 802-814 can be performed in any of a number of orders without departing from the scope of this disclosure. Additionally, according to various embodiments, certain blocks or steps are removed or added to method 800 without departing from the scope of this disclosure.

[0058] Although the present invention has been described in terms of the foregoing disclosed embodiments, this description has been provided by way of explanation only and is not intended to be construed as a limitation of the invention. Indeed, even though the foregoing descriptions refer to numerous components and other embodiments that are presently contemplated, those of ordinary skill in the art will recognize many possible alternatives exist that have not been expressly referenced or even suggested here. While the foregoing written descriptions should enable one of ordinary skill in the pertinent arts to make and use what arepresently considered the best modes of the invention, those of ordinary skill will also understand and appreciate the existence of numerous variations, combinations, and equivalents of the various aspects of the specific embodiments, methods, and examples referenced herein.

[0059] Hence the drawings and detailed descriptions herein should be considered illustrative, not exhaustive. They do not limit the invention to the particular forms and examples disclosed. To the contrary, the invention includes many further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments apparent to those of ordinary skill in the art, without departing from the spirit and scope of this invention.

[0060] Accordingly, in all respects, it should be understood that the drawings and detailed descriptions herein are to be regarded in an illustrative rather than a restrictive manner and are not intended to limit the invention to the particular forms and examples disclosed. In any case, all substantially equivalent systems, articles, and methods should be considered within the scope of the invention and, absent express indication otherwise, all structural or functional equivalents are anticipated to remain within the spirit and scope of the presently disclosed systems and methods.

Claims

CLAIMSWHAT IS CLAIMED IS:

1. A microtube heat exchanger comprising: a plurality of microtubes substantially aligned to form a microtube stack for carrying working fluid, the microtube stack including a working fluid inlet and a working fluid outlet; an inlet header fluidly coupled with the working fluid inlet and an outlet header fluidly coupled with the working fluid outlet; and a shell substantially surrounding the microtube stack and configured to allow for carrying shell-side fluid past an outside of the plurality of microtubes, wherein, at least one of: the shell is segregated by an inner barrier to allow for a first shell-side passageway and a second shell-side passageway fluidly segregated from the first shell-side passageway, and the inlet header is sectioned to allow for two segregated working fluid flow paths through the microtube stack.

2. The microtube heat exchanger of Claim 1, wherein the microtube heat exchanger is part of an environmental control system (ECS) of an aerospace vehicle.

3. The microtube heat exchanger of Claim 1, wherein the microtube heat exchanger is configured to perform the function of a reheater and a condenser of a traditional ECS of an aerospace vehicle such that:a fluid inlet of the first shell-side fluid passageway is coupled with an outlet of a turbine of an air cycle machine of the ECS; and an outlet of the first shell-side fluid passageway is coupled with an air-conditioned cabin of the aerospace vehicle.

4. The microtube heat exchanger of Claim 1, wherein each of the first and second shell-side passageways includes a shell-side fluid inlet and a shell-side fluid outlet to allow for fluidly segregated flows of a first shell-side fluid through the first shell-side passageway and a second shell-side fluid through the second shell-side passageway.

5. The microtube heat exchanger of Claim 1, wherein the barrier is a plate with a first side defining part of the first shell-side passageway and a second side defining part of the second shell-side passageway.

6. The microtube heat exchanger of Claim 1, wherein: the microtube stack further comprises a stack first section disposed in the first shell-side passageway and a stack second section disposed in the second shell-side passageway; and the barrier comprises an inner volume fluidly coupled with the stack first section and stack second section so as to communicate working fluid between the stack first and second sections.

7. The microtube heat exchanger of Claim 1, wherein the microtube heat exchanger is configured to perform the function of a primary and a secondary heat exchanger of a traditional ECS of an aerospace vehicle such that: an inlet of one of the two segregated working fluid flow paths of the tube stack is configured to receive engine bleed from an engine of the aerospace vehicle; and an inlet of the other of the two segregated working fluid flow paths of the tube stack is configured to receive air discharged from a compressor of an air cycle machine of the ECS.

8. The microtube heat exchanger of Claim 1, wherein the outlet header is sectioned analogously to the inlet header in order to maintain the segregation of the two segregated working fluid flow paths through the outlet header.

9. The microtube heat exchanger of Claim 1, wherein the outlet header is configured to act as a mixer and combine the working fluids that traveled through the two segregated working fluid flow paths before discharging the working fluids from an outlet port of the outlet header.

10. The microtube heat exchanger of Claim 1, wherein the inlet header comprises: a first fluid inlet for accepting a first working fluid and fluidly coupled with a first flow path of the two fluidly segregated working fluid flow paths; and a second fluid inlet for accepting a second working fluid and fluidly coupled with a second flow path of the two fluidly segregated working fluid flow paths.

11. The microtube heat exchanger of Claim 10, wherein the outlet header comprises:a first fluid outlet for accepting the first working fluid of the first flow path; and a second fluid outlet for accepting the second working fluid of the second flow path.

12. The microtube heat exchanger of Claim 1, further comprising: an inlet stack end plate coupled with an inlet end of each of the plurality of microtubes by laser welding; and an outlet stack end plate coupled with an outlet end of each of the plurality of microtubes by laser welding, wherein the inlet header is mounted to the inlet stack end plate and the outlet header is mounted to the outlet stack end plate.

13. A method of providing heat transfer for multiple distinct fluid flow paths with a heat exchanger of an aerospace heat transfer system, comprising: aligning a plurality of microtubes to form a microtube stack for carrying working fluid of the heat exchanger, the microtube stack including a working fluid inlet and a working fluid outlet; coupling an inlet header with the working fluid inlet and an outlet header with the working fluid outlet; and substantially surrounding the microtube stack within a shell configured to allow for carrying shell-side fluid past an outside of the plurality of microtubes; wherein, at least one of: the shell is segregated by an inner barrier to allow for a first shell-side passageway and a second shell-side passageway fluidly segregated from the first shell-side passageway, and the inlet header is sectioned to allow for two segregated working fluid flow paths through the microtube stack.

14. The method of Claim 13, further comprising: passing a first shell-side fluid through the first shell-side passageway for heat exchange with the working fluid; and passing a second shell-side fluid through the second shell-side passageway for heat exchange with the working fluid.

15. The method of Claim 13, further comprising:passing a first working-fluid through a first of the two fluidly segregated working fluid flow paths for heat exchange with the shell-side fluid; and passing a second working-fluid through a second of the two fluidly segregated workingfluid flow paths for heat exchange with the shell-side fluid.

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