Patent Application
20230194182
The disclosure relates to heat exchangers and more particularly to a heat exchanger having fin pack structures to facilitate stacking.
Conventional plate fin heat exchangers use folded fins on one or both sides of a parting plate, with side bars to seal flows from one another. This structure involves numerous parts that are brazed together to form a cube structure.
Heat exchangers may also be cast. In this configuration, the cast plates define internal flow passages and external flow passages, and the plates are stacked with a fin pack positioned in the external flow passage defined between two cast plates.
Tolerance stackups when stacking such structures make it difficult to bond the fin pack to upper and lower sides of the two cast plates, where the fin pack either does not fit within the space, or does not reach both of the upper and lower sides to allow bonding to each surface.
In one disclosed non-limiting configuration, a heat exchanger comprises a plurality of plates having opposed surfaces and side walls extending beyond the opposed surfaces to a height (h); and a fin pack extending from one opposed surface toward an opposed surface of an adjacent plate, and having a fin height (f), wherein the fin height (f) is equal to or less than the height (h).
In another non-limiting configuration, the heat exchanger further comprises a second fin pack having a height (h) and extending from the opposed surface of the adjacent plate toward the one opposed surface and having a fin height (f) that is less than or equal to the height (h).
In still another non-limiting configuration, a gap is defined between the fin pack and the second fin pack.
In a further non-limiting configuration, the fin packs are a folded structure, and the gap is defined between crests of the folded structure.
In a still further non-limiting configuration, the gap is less than or equal to 0.020 inches (0.508 mm).
In another non-limiting configuration, the plurality of plates are stacked with side walls of adjacent plates bonded to each other.
In still another non-limiting configuration, the plurality of plates define an internal flow passage.
In a further non-limiting configuration, the opposed surfaces of adjacent plates of the plurality of plates define an external flow passage, and the fin pack comprises two fin packs in the external flow passage, with one of the two fin packs extending from each of the opposed surfaces toward the other of the two fin packs.
In a still further non-limiting configuration, the fin pack is diffusion bonded or brazed to one of the opposed surfaces.
In an additional non-limiting configuration, a heat exchanger subassembly comprises a plate having first and second opposed surfaces, and side walls extending transverse to the opposed surfaces to define a side wall height (h) relative to the opposed surfaces; at least one internal flow passage defined in the plate; and a first folded fin pack on the first opposed surface and a second folded fin pack on the second opposed surface, each folded fin pack having a fin height (f) that is less than or equal to the side wall height (h).
In another non-limiting configuration, the internal flow passage extends substantially transverse to flow passages defined along walls of the first folded fin pack and the second folded fin pack.
In still another non-limiting configuration, the first folded fin pack and the second folded fin pack are bonded to the first and second opposed surfaces.
In another non-limiting configuration, a method for making a heat exchanger comprises bonding a first folded fin pack and a second folded fin pack to opposed surfaces of a plate having side walls and an internal flow passage to form a heat exchanger subassembly; stacking the heat exchanger subassembly with a further heat exchanger subassembly with a gap defined between adjacent folded fin packs; and bonding the heat exchanger subassembly to the further heat exchanger subassembly at contacting surfaces of the side wall of each heat exchanger subassembly.
In a further non-limiting configuration, the bonding step comprises diffusion bonding.
In a still further non-limiting configuration, the bonding step comprises brazing.
In another non-limiting configuration, the side walls extend beyond the opposed surfaces to a height (h), and wherein the fin pack has a fin height (f), wherein the fin height (f) is equal to or less than the height (h).
A detailed description of preferred embodiments of the invention follows, with referenced to the attached drawings, wherein:
Like reference numbers and designations in the various drawings indicate like elements.
The present disclosure relates to heat exchangers and, more particularly, to cast heat exchangers defining external cooling passages when stacked, and having partial-height fin packs in the external cooling passages.
Turning to
Subassemblies 22 as shown in
Each side wall 36 extends beyond a surface 30, 32 by a height h, and when stacked, the height h of two adjacent plates 24 defines an external flow passage height H between surfaces 30, 32 of adjacent plates 24.
Fin packs 26, 28 are referred to herein as “partial-height” fin packs because they are configured to have a fin height (f) that can correspond to the height (h) defined by side wall 36. In this configuration, fin height (f) can be approximately the same or less than height (h) such that, when subassemblies 22 are stacked, fin packs 26, 28 of adjacent plates extend toward each other in external flow passage 38 with a small gap defined between them. This allows each fin pack 26, 28 to be bonded to a surface 30, 32 without issues caused by tolerance stackups. As shown in
The disclosed configuration is well suited to fabrication through casting but it should be appreciated that other methods of manufacturing could also be utilized to produce heat exchanger 20 and subassemblies 22 as disclosed.
Suitable materials for plate 24 include, but are not limited to: stainless steel, austenitic nickel-chromium-based superalloy such as that marketed under the trademark Inconel, nickel chromium superalloy such as that marketed under the trademark Rene 41, nickel based super-alloy such as that marketed under the trademark Mar-M, and other nickel based super-alloys.
Plate 24 can be flat, or can be shaped to suit specific uses. In one non-limiting example the plate can be curved.
Fin packs can be made using known techniques, and suitable materials for fin packs 26, 28 include, but are not limited to: stainless steel, nickel-chromium-based superalloy such as that marketed under the trademark Inconel and other nickel based super-alloys.
Fin packs 26, 28 can be bonded, for example diffusion bonded, or brazed, to plate 24, for example to both surfaces 30, 32 of plate 24, to produce subassembly 22 such as that illustrated in
Subassemblies 22 can then be stacked and joined at contacting sidewall surfaces 42, again for example by bonding or brazing, diffusion bonding, or other techniques that are known to persons skilled in the art.
Height (h) of sidewalls can be the same or different on opposite sides of plate 24. Having height (h) be the same is suitable from a uniformity standpoint, but in specialized configurations it may be desirable to have different heights (h) on different surfaces 30, 32.
Fin height of the fin packs 26, 28 can also be the same, and this matches up with the configuration wherein height (h) is the same on both surfaces 30, 32. It should be appreciated that in some configurations, it may be desirable to have fin heights be different on different surfaces 30, 32, and this can still be accomplished as long as the combined fin height is configured to match height H defined between surfaces 30, 32.
When height (h) is the same on both sides, then the same fin packs can be bonded to each surface 30, 32.
With the configuration as disclosed herein, gap 44 between fold ends 46 (
Fin packs having fin height (f) equal to or less than height (h) allow fabrication of a stacked heat exchanger where fin packs are brazed to both opposed surfaces that define the external flow passage, and therefore have the desired heat exchange properties with these surfaces, and at the same time the disclosed fin height allows stacking of the heat exchanger subassemblies without issues caused with a single fin pack in known heat exchangers such as that illustrated in
Partial height fin packs allow manufacture of heat exchanger subassemblies having the heat exchanger plate as disclosed, with a fin pack on each opposed surface, and brazed or diffusion bonded to the opposed surface. Heat exchanger subassemblies can then be stacked, and the height of the fins as compared to the side wall of the plate allows stacking with a small gap between the fin packs, thereby avoiding issues with respect to stack up tolerance mismatch and the like wherein a single fin pack would either be too large to fit in the space between plates, or would be too small and therefore difficult to bond to both surfaces.
Once the subassemblies are stacked as desired, they can then be brazed or diffusion bonded together at the contacting side wall surfaces to complete the heat exchanger.
One or more embodiments of the present disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention.
Accordingly, other embodiments are within the scope of the following claims.
