Patent Application
20160231065
This disclosure relates to heat exchangers and, more particularly, to heat exchanger tubes that have internal features for enhancing thermal exchange.
A heat exchanger can include one or more tubes for transferring a first working fluid. A second working fluid can be passed around the outside of the tubes such that there is a thermal exchange between the two working fluids. The tube can include pins on the inside that are used to increase surface area and thus increase heat transfer between the fluids. The tubes and pins are typically fabricated by joining several pieces together using welding or brazing techniques.
A heat exchanger article according to an example of the present disclosure includes a hollow tube including a tube wall with an interior surface and an exterior surface, the interior surface defines a flow passage through the hollow tube, and a vane cluster in the flow passage. The vane cluster includes a plurality of vanes, and each of the vanes extends inwardly from the tube wall.
In a further embodiment of any of the foregoing embodiments, the vanes of the vane cluster extend inwardly toward a common central axis of the hollow tube.
In a further embodiment of any of the foregoing embodiments, each of the vanes has a twist from a vane leading edge to a vane trailing edge.
In a further embodiment of any of the foregoing embodiments, each of the vanes has an airfoil shape.
In a further embodiment of any of the foregoing embodiments, the vanes of the vane cluster meet at a central hub.
In a further embodiment of any of the foregoing embodiments, the hollow tube includes a plurality of protrusions extending outwardly from the exterior surface.
In a further embodiment of any of the foregoing embodiments, each of the vanes has a length from a vane leading edge to a vane trailing edge and a span from a vane outer side to a vane inner side, and a ratio of the length to the span is greater than 1:1.
In a further embodiment of any of the foregoing embodiments, the hollow tube is monolithic.
A heat exchanger article according to an example of the present disclosure includes a hollow tube including a tube wall with an interior surface and an exterior surface, the interior surface defines a flow passage through the hollow tube, and a series of vane clusters spaced apart in the flow passage. Each of the vane clusters includes a plurality of vanes, and each of the vanes extends inwardly from the tube wall.
In a further embodiment of any of the foregoing embodiments, at least one of the vane clusters has a clockwise twist and at least one other of the vane clusters has a counter-clockwise twist.
In a further embodiment of any of the foregoing embodiments, the series of vane clusters has an alternating arrangement of vane clusters with regard to clockwise twist and counter-clockwise twist.
In a further embodiment of any of the foregoing embodiments, each of the vane clusters has a twist, and the series of vane clusters has a progressively changing twist.
In a further embodiment of any of the foregoing embodiments, each of the vane clusters has a twist, and the series of vane clusters has a progressively changing twist between clockwise twist and counter-clockwise twist.
In a further embodiment of any of the foregoing embodiments, the flow passage is unobstructed between the vane clusters.
In a further embodiment of any of the foregoing embodiments, the hollow tube is monolithic.
A heat exchanger article according to an example of the present disclosure includes a hollow monolithic tube that has first and second ends. The monolithic tube includes a tube wall that circumscribes a flow passage that extends from the first end to the second end, and a plurality of vanes that are spaced from at least one of the first and second ends and that extend inwardly from the tube wall.
In a further embodiment of any of the foregoing embodiments, each of the vanes extends inwardly toward a common central axis of the monolithic tube.
In a further embodiment of any of the foregoing embodiments, each of the vanes has a twist from a vane leading edge to a vane trailing edge.
In a further embodiment of any of the foregoing embodiments, each of the vanes has an airfoil shape.
The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
Some heat exchanger tubes include internal pins that function to increase surface area for greater thermal exchange. However, manufacturing processes such as brazing and welding limit the type and geometry of internal features. In this regard, an alternative fabrication process, such as additive manufacturing, can be used to fabricate internal features that are not feasible using other manufacturing techniques.
In the illustrated example, the hollow tube 24 includes a tube wall 26 that has an interior surface 26a and an exterior surface 26b. The interior surface 26a defines a flow passage 28 through the hollow tube 24. The hollow tube 24 also includes a static vane cluster 30 in the flow passage 28. The vane cluster 30 includes a plurality of vanes 32, and each of the vanes 32 extends inwardly from the tube wall 26. For instance, the vanes 32 extend from the tube wall 26, rather than an intermediate structure.
Each of the vanes 32 includes a leading edge 34 and a trailing edge 36 that define a length dimension that is generally parallel to a central axis A of the hollow tube 24. The vanes 32 each also have a span dimension from a vane outer side 38 at the tube wall 26 to a vane inner side 40 that is spaced inwardly from the tube wall 26. In one example, the vanes 32 are longer than they are wide, and the vanes thus have a ratio of length to span that is greater than 1:1.
In this example, each of the vanes 32 also has a vane twist. That is, the body of each of the vanes 32 twists along the length direction. The twist of the vanes 32 serves to swirl working fluid that flows through the flow passage 28 over the vanes 32. Thus, the vanes 32 can have either a clockwise twist or a counterclockwise twist to cause, respectively, clockwise or counterclockwise swirl of the fluid. The swirl of the working fluid serves to promote a more uniform temperature distribution. Moreover, the vanes 32 increase surface area and, therefore, also promote heat transfer through the tube wall 26.
In this example, each of the vanes 32 extends radially inwardly toward the common central axis A of the hollow tube 24. The vanes 32 meet at a hub 42, which joins all of the vanes 32 and structurally supports the vanes 32 relative to the tube wall 26. In this example, the hub 42 is cylindrical, although the hub 42 could alternatively have a different geometry. In one modification, the hub 42 is excluded such that the vanes 32 either have free inner ides or the vanes 32 meet at a relatively smaller hub.
Additive manufacturing can be used to form the tube wall 26 and the vane cluster 30. Additive manufacturing involves building an article layer-by-layer from a powder material by consolidating selected portions of each successive layer of powder until the complete article is formed. For example, the powder is fed into a chamber, which may be under vacuum or inert cover gas. A machine deposits multiple layers of the powder onto one another. An energy beam, such as a laser, selectively heats and consolidates each layer with reference to a computer-aided design data to form solid structures that relate to a particular cross-section of the article. Other layers or portions of layers corresponding to negative features, such as cavities or openings, are not joined and thus remain as a powdered material. The unjoined powder material may later be removed using blown air, for example. With the layers built upon one another and joined to one another cross-section by cross-section, the article, or a portion thereof, such as for a repair, is produced. The article may be post-processed to provide desired structural characteristics. For example, the article may be heat treated to produce a desired microstructure. Additive manufacturing processes can include, but are not limited to, selective laser melting, direct metal laser sintering, electron beam melting, 3D printing, laser engineered net shaping, or laser powder forming
The additive manufacturing process can be used to form the hollow tube 24 as a monolithic tube. In this regard, the hollow tube 24 is seamless with regard to distinct boundaries that would otherwise be formed using techniques such as welding or brazing. Thus, the (monolithic) hollow tube 24, in one example, is free of seams such that there are no distinct boundaries or discontinuities in the hollow tube 24 that are visually or microscopically discernable.
The hollow tube 424 in
The hollow tube 524 in
Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.
