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EP-4317891-B1 - HEAT EXCHANGER WITH HEAT TRANSFER AUGMENTATION FEATURES

EP4317891B1EP 4317891 B1EP4317891 B1EP 4317891B1EP-4317891-B1

Inventors

  • TURNEY, JOSEPH E.
  • KIRSCH, KATHRYN L.
  • DOLD, ROBERT H.
  • KENNEDY, Matthew B.

Dates

Publication Date
20260506
Application Date
20230530

Claims (7)

  1. A heat exchanger comprising; a plurality of first channels (12, 26) extending longitudinally, each first channel comprising: a plurality of external fins (18, 20, 32) extending from and integrally formed with an external wall (24, 36) of each first channel, wherein the plurality of external fins (18, 20) includes first external fins (18) and second external fins (20), wherein the first and second external fins have an undulating shape extending a length of each first channel and wherein the first external fins connect adjacent first channels (12); and a plurality of second channels (14, 28), each second channel defined by the external walls of the plurality of first channels and first external fins (18), wherein the plurality of second channels is fluidly isolated from the plurality of first channels and wherein the second external fins (20) protrude into the plurality of second channels (14), characterized in that it further comprises a plurality of first internal fins (16, 30) extending from and integrally formed with an internal wall (22, 34) of each first channel, wherein first internal fins of the plurality of internal fins are arranged in a spiralling orientation along the internal wall.
  2. The heat exchanger of claim 1, wherein the heat exchanger is additively manufactured.
  3. The heat exchanger of claim 1 or 2, wherein each first channel (12, 26) has a circular cross-section.
  4. The heat exchanger of claim 1, 2 or 3, wherein the first internal fins (16) extend less than a full width of each first channel (12); and/or, wherein the first internal fins (16) are circumferentially spaced about the internal wall (22) and extend the length of each first channel (12).
  5. The heat exchanger of claim any of claims 1 to 4, wherein each first channel (12) further comprises a twisted center fin (44); and optionally, wherein the twisted center fin is disposed between and is connected to the first internal fins (16).
  6. The heat exchanger of any of claims 1-5, wherein walls of the plurality of first channels (26) have a thickness greater than a thickness of the external fins (32).
  7. The heat exchanger of claim 5, wherein the twisted center fin (44) is disposed between and is connected to the first internal fins (32).

Description

BACKGROUND Heat exchangers are central to the functionality of numerous systems, including a variety of oil and air-cooling applications, recuperations, and waste heat harvesting for power cycles. These applications continually require increases in heat transfer performance, reductions in pressure loss, and reductions in size and weight. Current heat exchanger offerings are dominated by plate fin constructions, with tube shell and plate-type heat exchangers having niche applications. Heat transfer rates decrease as fluid flows down the length of a channel. There are several methods of augmenting heat transfer, one of which is to increase the surface area of a material that a flowing fluid contacts. Fins are used within channels to increase surface area without altering the external dimensions of the channel itself. However, traditional plate-fin construction imposes design constraints that inhibit performance, increase size and weight, results in structural reliability issues, make it unfeasible to meet future high temperature applications, and limit system integration opportunities. Other known enhancement techniques include twisted tapes and wire coils that are inserted into the channel and serve the same function as fins. Simply increasing fin size or number of fins to maximize surface area and augment heat transfer can result in designs that are too heavy and inefficient, and inserts suffer from similar shortcomings as well as increased wear and tear. There is a need for heat exchanger heat transfer augmentation features that are designed for and able to withstand high pressure and temperature applications using characteristics besides increased fin size, and for designs providing increased heat transfer performance, reduced pressure losses, and reduced size and weight. US 2016 / 0116218 discloses a heat exchanger with a plurality of first channels extending longitudinally, each first channel comprising: a plurality of first internal fins extending from and integrally formed with an internal wall of each first channel, and plurality of external fins extending from and integrally formed with an external wall of each first channel, wherein the plurality of external fins includes first external fins and second external fins having an undulating shape extending a length of each first channel and wherein the first external fins connect adjacent first channels; and a plurality of second channels, each second channel defined by the external walls of the plurality of first channels and first external fins, wherein the plurality of second channels is fluidly isolated from the plurality of first channels and wherein the second external fins protrude into the plurality of second channels. SUMMARY A heat exchanger includes a plurality of longitudinally-extending first channels and a plurality of second channels fluidly isolated from the plurality of first channels. Each first channel includes a plurality of internal fins and a plurality of external fins. The internal fins extend from and are integrally formed with the internal walls of the first channel. The internal fins have a spiraling orientation along the internal wall. The external fins connect adjacent first channels. The plurality of second channels is defined at least in part by external walls of the plurality of first channels and the plurality of external fins. The present summary is provided only by way of example, and not limitation. Other aspects of the present disclosure will be appreciated in view of the entirety of the present disclosure, including the entire text, claims and accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of one embodiment of a heat exchanger core.FIG. 2A is a perspective view of a segment of another embodiment of a heat exchanger core.FIG. 2B is a perspective view of a fluid flow in the heat exchanger core segment of FIG. 2A with a channel, internal fins, external fins, and an outer wall removed.FIG. 3A is a cutaway perspective view of a heat exchanger channel.FIG. 3B is a perspective view of internal fins of the heat exchanger channel of FIG. 3A.FIG. 3C is a cross-sectional view of the heat exchanger channel of FIG. 3A taken along the 3C-3C line of FIG. 3A. DETAILED DESCRIPTION The present disclosure is directed to an additively manufactured heat exchanger core with channel configurations having various internal and external fin arrangements designed to augment heat transfer. The disclosed heat exchanger core configurations are applicable to counterflow heat exchanger designs and are specifically suited for application in supercritical CO2 cycles, which operate at high pressure and depend heavily on heat transfer for cycle efficiency. Channel configurations and internal fins in each fluid channel can be additively manufactured in orientations, arrangements, and shapes to augment heat transfer. The present application discloses several embodiments of additively manufactured channel and interna