Patent Description:
Heat exchangers are often used to transfer heat between two fluids. For example, in aircraft environmental control systems, heat exchangers may be used to transfer heat between a relatively hot air source (e.g., bleed air from a gas turbine engine) and a relatively cool air source (e.g., ram air).

In one example, a heat exchanger includes a heat exchanger core. The heat exchanger core includes a plurality of tubes. Each tube of the plurality of tubes includes a first end and a second end and extends from the first end to the second end in a lengthwise direction. Each tube of the plurality of tubes is spaced from adjacent tubes in a height-wise direction and a widthwise direction. The plurality of tubes is stacked to create a concave profile in the height-wise direction and widthwise direction. The concave profile extends in the lengthwise direction.

In another example, a heat exchanger includes a first header, a second header, and a core. The first header includes an inlet and an outlet. The outlet is fluidically connected to the inlet. The second header includes an inlet and an outlet. The outlet of the second header is fluidically connected to the inlet of the second header. The core includes a plurality of tubes and each tube of the plurality of tubes extends in a lengthwise direction from a first end to a second end. The first end of each tube of the plurality of tubes is fluidically connected to the outlet of the first header, and the second end of each tube of the plurality of tubes is fluidically connected to the inlet of the second header. The plurality of tubes is stacked to create a concave profile in the height-wise direction and the widthwise direction, and the concave profile extends in the lengthwise direction.

Persons of ordinary skill in the art will recognize that other aspects and embodiments of the present invention are possible in view of the entirety of the present disclosure, including the accompanying figures.

While the above-identified drawing figures set forth one or more embodiments of the invention, other embodiments are also contemplated. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features and components not specifically shown in the drawings. Like reference numerals identify similar structural elements.

This disclosure relates to an additively manufactured heat exchanger with plenum headers or with fractal headers that utilizes a non-rectangular core as a means of capturing and retaining the external flow. The heat exchanger includes a first header, a second header (hereinafter first header and second header can be referred to together as "headers"), and a core. The first header includes an inlet and an outlet. The second header includes an inlet and an outlet. The core includes a plurality of tubes that extends from a first end to a second end in a lengthwise direction. Each tube of the plurality of tubes is spaced from adjacent tubes in a height-wise direction and a widthwise direction. The plurality of tubes is stacked to create a concave profile in the height-wise direction and the widthwise direction. The concave profile extends in the lengthwise direction. In one example, each tube of the plurality of tubes can also include a bend between the first end and the second end. The first end of each tube of the plurality of tubes is fluidically connected to the outlet of the first header. The second end of each tube of the plurality of tubes is fluidically connected to the inlet of the second header.

As discussed above, the heat exchanger can include non-fractal headers. In another example, the heat exchanger can include fractal headers. Fractal headers include an inlet, a primary flow duct, a plurality of secondary flow ducts, and a multiplicity of tertiary flow ducts. The primary flow duct is fluidically connected to the inlet of the header. The plurality of secondary flow ducts is fluidically connected to the inlet by the primary flow duct. The primary flow duct splits to form the plurality of secondary flow ducts. The multiplicity of tertiary flow ducts is fluidically connected to the inlet by the plurality of secondary flow ducts and the primary flow ducts. Each of the plurality of secondary flow ducts splits to form the multiplicity of tertiary flow ducts. When the heat exchanger includes fractal headers, the first end of each tube of the plurality of tubes is connected to one flow duct of the multiplicity of tertiary flow ducts of the first header. The second end of each tube of the plurality of tubes is connected to one flow duct of the multiplicity of tertiary flow ducts of the second header.

The heat exchangers as discussed above can be surrounded by a flow housing that includes an inlet and an outlet. The inlet of the flow housing is fluidically connected to the outlet of the flow housing. The first header, the core, and the second header form a primary flow path and the flow housing forms a secondary flow path. At least the plurality of tubes are disposes inside the flow housing. The primary flow path is fluidically isolated from the secondary flow path. The concave profile of the plurality of tubes faces an upstream direction of the secondary path. In another example, the plurality of tubes can be stacked to include a second concave profile. Together the first concave profile and the second concave profile form a sinusoidal profile. The sinusoidal profile can extend the entire length of the plurality of tubes in the lengthwise direction. Similar to the concave profile, the sinusoidal profile faces the upstream direction of the secondary flow path. Both the concave profile and the sinusoidal profile help direct a secondary flow as the secondary flow traverses the plurality of tubes. The concave profiles and the sinusoidal profile help distribute the secondary flow across the plurality of tubes to improve the heat transfer capabilities of the heat exchanger. In another example, the plurality of tubes can include a bend that increases the surface area of the plurality of tubes, which increases the heat transfer capabilities of the heat exchanger. The bend in the plurality of tubes also helps customize the shape of the heat exchanger so that the heat exchanger can fit in tight and/or customized envelopes.

Heat exchangers often utilize a rectangular core with shrouding or ducting to direct the external flow over the heat exchanger surface. In high-performance heat exchangers, this shrouding can face several challenges: the shrouding adds weight to the heat exchanger system, the shrouding can be susceptible to failure due to vibrational forces and, the shrouding can capture heat that generates thermal stresses and result in thermal expansion of the heat exchanger. The heat exchanger as discussed above addresses these concerns by changing the shape of the heat exchanger core and reducing the effects of external flow loss without using shrouds. The heat exchanger will be discussed below with reference to the figures.

<FIG> is a perspective view of heat exchanger <NUM>. Heat exchanger <NUM> includes first header <NUM>, second header <NUM>, and core <NUM>. As shown in <FIG>, first header <NUM> includes first header inlet <NUM>, primary flow duct <NUM>, plurality of secondary flow ducts <NUM> (referred to as "secondary flow ducts <NUM>"), and multiplicity of tertiary flow ducts <NUM> (referred to as tertiary flow ducts <NUM>"). As also shown in <FIG>, second header <NUM> includes second header outlet <NUM>, primary flow duct <NUM>, plurality of secondary flow ducts <NUM> (referred to as "secondary flow ducts <NUM>"), and multiplicity of tertiary flow ducts <NUM> (referred to as tertiary flow ducts <NUM>"). Core <NUM> includes plurality of tubes <NUM> (referred to as "tubes <NUM>"). Each tube of tubes <NUM> includes first end <NUM> and second end <NUM>. Flow housing <NUM>, as shown in <FIG>, includes flow housing inlet <NUM> and flow housing outlet <NUM>. Heat exchanger <NUM> also includes lengthwise direction L, widthwise direction W, and height-wise direction H. Tubes <NUM> form concave profile C.

As shown in <FIG>, first header <NUM> is a header with fractal geometry. Primary flow duct <NUM> of first header <NUM> is fluidically connected to first header inlet <NUM>. Primary flow duct <NUM> of first header <NUM> splits to form secondary flow ducts <NUM> of first header <NUM>. Secondary flow ducts <NUM> of first header <NUM> are fluidically connected to first header inlet <NUM> by primary flow duct <NUM> of first header <NUM>. Each flow duct of secondary flow ducts <NUM> of first header <NUM> splits to form tertiary flow ducts <NUM> of first header <NUM>. Tertiary flow ducts <NUM> are fluidically connected to first header inlet <NUM> by secondary flow ducts <NUM> of first header <NUM> and primary flow duct <NUM> of first header <NUM>.

As also shown in <FIG>, second header <NUM> is a header with fractal geometry. Primary flow duct <NUM> of second header <NUM> is fluidically connected to second header outlet <NUM>. Primary flow duct <NUM> of second header <NUM> splits to form secondary flow ducts <NUM> of second header <NUM>. Secondary flow ducts <NUM> of second header <NUM> are fluidically connected to second header outlet <NUM> by primary flow duct <NUM> of second header <NUM>. Each flow duct of secondary flow ducts <NUM> of second header <NUM> splits to form tertiary flow ducts <NUM> of second header <NUM>. Tertiary flow ducts <NUM> are fluidically connected to second header outlet <NUM> by secondary flow ducts <NUM> of second header <NUM> and primary flow duct <NUM> of second header <NUM>.

Each tube of tubes <NUM> extends from first end <NUM> to second end <NUM> in lengthwise direction L. Each tube of tubes <NUM> is spaced from adjacent tubes in height-wise direction H and widthwise direction W. Tubes <NUM> are stacked to create concave profile C in height-wise direction H and widthwise direction W. Concave profile C extends in lengthwise direction L. In the example shown in <FIG>, concave profile C extends the entire length of tubes <NUM> in lengthwise direction L. In another example, concave profile C can extend a portion of the length of tubes <NUM> in lengthwise direction L. First end <NUM> of each tube of tubes <NUM> is connected to one of tertiary flow ducts <NUM> of first header <NUM>. Second end <NUM> of each tube of tubes <NUM> is connected to one of tertiary flow ducts <NUM> of second header <NUM>.

<FIG> is a schematic of a cross-sectional view of heat exchanger <NUM> taken at line A-A. Heat exchanger <NUM> includes flow housing <NUM>. Flow housing <NUM> includes flow housing inlet <NUM> and housing outlet <NUM>. Flow housing <NUM> can be a duct, an envelope, shroud, or a manifold. As shown in <FIG>, primary flow path P flows through tubes <NUM> either into or out of the page. In the example shown in <FIG>, flow housing <NUM> surrounds first header <NUM>, second header <NUM>, and core <NUM>. In another example, flow housing <NUM> can surround just core <NUM>. Flow housing inlet <NUM> is fluidically connected to flow housing outlet <NUM>. First header <NUM>, second header <NUM>, and core <NUM> form primary flow path P. Flow housing <NUM> forms secondary flow path S with secondary flow path S passing through the spaces between tubes <NUM>. Primary fluid path P is fluidically isolated from secondary fluid path S.

In one example, secondary flow path S flows transverse to primary flow path P and between tubes <NUM>. In another example, secondary flow path S flows parallel to primary flow path P and between tubes <NUM>. In yet another example, tubes <NUM> are curved such that secondary flow path S flows transverse to primary flow path P at some portion of tubes <NUM>, and secondary flow path S flows parallel to primary flow path P at some portion of tubes <NUM>. Concave profile C faces an upstream direction of secondary flow path S. Because concave profile C faces the upstream direction of secondary flow path S, concave profile C has a greater surface area in contact with secondary flow path S as secondary flow path S enters between tubes <NUM>. The increased surface area in contact between concave profile C and secondary flow path S helps mitigate losses as secondary flow path S flows between tubes <NUM>. Because there are reduced losses as secondary flow path S travels through tubes <NUM>, secondary flow path S is better distributed across tubes <NUM>. Thus, as a result of concave profile C, secondary flow path S contacts more surface area of tubes <NUM>. The increase of contact between secondary flow path S and tubes <NUM> results in greater heat transfer of a fluid in primary flow path P and a fluid in secondary flow path S. In one example, the fluid in primary flow path P can be a hot fluid, (e.g., bleed air from a gas turbine engine) and the fluid in secondary flow path S can be a cold fluid (e.g., ram air). In another example, the fluid in primary flow path P can be a cold fluid (e.g., ram air) and the fluid in secondary flow path S can be a hot fluid, (e.g., bleed air from a gas turbine engine).

In the example of <FIG>, tubes <NUM> are stacked to form concave profile C. In another example, as shown in <FIG>, tubes <NUM> can be stacked to create second concave profile C2 in height-wise direction H and widthwise direction W. Together second concave profile C2 extends in the lengthwise direction. Concave profile C and second concave profile C2 form sinusoidal profile SP. Sinusoidal profile SP extends an entire length of tubes <NUM> in lengthwise direction L. Sinusoidal profile SP faces an upstream direction of secondary flow path S. Because sinusoidal profile SP faces the upstream direction of secondary flow path S, sinusoidal profile SP has a greater surface area in contact with secondary flow path S as secondary flow path S enters between tubes <NUM>. The increased surface area in contact between sinusoidal profile SP and secondary flow path S helps mitigate losses as secondary flow path S navigates between tubes <NUM>. Because there are reduced losses as secondary flow path S travels through tubes <NUM>, secondary flow path S is better distributed across tubes <NUM>. Thus, as a result of sinusoidal profile SP, secondary flow path S contacts more surface area of tubes <NUM>. The increase of contact between secondary flow path S and tubes <NUM> results in greater heat transfer of a fluid in primary flow path P and a fluid in secondary flow path S. In yet another example, tubes <NUM> can be stacked to create a U-shaped, V-shaped, repeating wave, parabolic, square wave, convex, hemispherical, dished, semi-elliptical, torispherical, toriconical, conical, semi-cylindrical, and/or any other profile shape that can help guide secondary flow S through tubes <NUM>.

<FIG> is a perspective view of an alternative embodiment of heat exchanger <NUM>. As shown in <FIG>, each tube of tubes <NUM> can include bend <NUM> between first end <NUM> and second end <NUM>. Bend <NUM> in tubes <NUM> between first end <NUM> and second end <NUM> allows core <NUM> to have an increased length and be packed in the same linear distance in longitudinal direction L. As a result of core <NUM> having an increased length, heat exchanger <NUM> has an increased surface area of tubes <NUM>. The increased surface area of tubes <NUM> increases the heat transfer capabilities of heat exchanger <NUM>. Further, bend <NUM> can be altered to fit heat exchanger <NUM> within a tight or custom envelop, while maintaining heat exchanger capabilities as compared to traditional heat exchangers, which are generally box-shaped.

<FIG> is a perspective view of an alternative embodiment of core <NUM> of heat exchanger <NUM>. As shown in <FIG>, core <NUM> includes first panel <NUM> and second panel <NUM>. First panel <NUM> extends in height-wise direction H1 and extends widthwise direction W1. Second <NUM> extends in height-wise direction H2 and extends in widthwise direction W2. First end <NUM> of each tube of tubes <NUM> extends through first panel <NUM>. Second end <NUM> of each tube of tubes <NUM> extends through second panel <NUM>. First panel <NUM> and second panel <NUM> help support core <NUM> and improve the durability of heat exchanger <NUM>. Additionally, first panel <NUM> and second panel <NUM> support core <NUM> so that core <NUM> can be additively manufactured without first header <NUM> or second header <NUM>.

As shown in <FIG>, heat exchanger <NUM> first header <NUM> and second header <NUM> can be plenum headers. First header <NUM> includes first header inlet <NUM>, first header outlet <NUM>, and first header plenum <NUM>, which fluidically connects first header inlet <NUM> to first header outlet <NUM>. Second header <NUM> includes second header outlet <NUM>, second header inlet <NUM>, and second header plenum <NUM>, which fluidically connects second header outlet <NUM> and second header inlet <NUM>. First header <NUM> can be welded or brazed to first panel <NUM> and second header <NUM> can be welded or brazed to second panel <NUM>.

As shown in <FIG>, each tube of tubes <NUM> is stacked in concave profile C in height-wise direction H and widthwise direction W. Concave profile C of tubes <NUM> extends in lengthwise direction L. As discussed above, tubes <NUM> with concave profile C have a greater surface area between secondary flow path S and tubes <NUM> than traditional heat exchangers, which are typically box-shaped. The increase of surface area between secondary flow path S and tubes <NUM> results in greater heat transfer capabilities. In addition to concave profile C, in the example of <FIG>, tubes <NUM> of core <NUM> includes bend <NUM> between first end <NUM> and second end <NUM>. As discussed above, bend <NUM> also increases the heat transfer of heat exchanger <NUM>. Therefore, as shown in <FIG>, heat exchanger <NUM> has the benefit of having tubes <NUM> with concave profile C and tubes <NUM> having bend <NUM> between first end <NUM> and second end <NUM> of tubes <NUM>. Thus, heat exchanger <NUM> as shown in <FIG> has improved heat transfer capabilities over traditional heat exchangers.

To obtain these complex geometries, heat exchanger <NUM> can be made using additive manufacturing. In one example, first header <NUM>, second header <NUM>, and core <NUM> can be additively manufactured a single monolithic part in a single additive manufacturing process. In another example, first header <NUM> and core <NUM> can be additively manufactured as a single monolithic part in a single additive manufacturing process. When first header <NUM> and core <NUM> are a single monolithic part second header <NUM> can be brazed or welded to first header <NUM> and core <NUM>. In another example, second header <NUM> and core <NUM> can be additively manufactured in as a single monolithic part in a single additive manufacturing process. When second header <NUM> and core <NUM> are a single monolithic part first header <NUM> can be brazed or welded to second header <NUM> and core <NUM>. In yet another example, first header <NUM> and second header <NUM> can be additively manufactured, core <NUM> can be additively manufactured in a second process, and first header <NUM> and second header <NUM> can be brazed or welded to core <NUM>. Another benefit of the bend in tubes <NUM> is that the bend in tubes <NUM> allows a heat exchanger of greater heat exchange properties (longer surface area of tubes <NUM>) to be built on an additively manufacturing machine with a smaller build platform.

A heat exchanger includes a heat exchanger core. The heat exchanger core includes a plurality of tubes. Each tube of the plurality of tubes includes a first end and a second end and extends from the first end to the second end in a lengthwise direction. Each tube of the plurality of tubes is spaced from adjacent tubes in a height-wise direction and a widthwise direction. The plurality of tubes is stacked to create a concave profile in the height-wise direction and widthwise direction. The concave profile extends in the lengthwise direction.

The heat exchanger of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:.

Claim 1:
A heat exchanger (<NUM>) comprising:
a heat exchanger core (<NUM>), wherein the heat exchanger core comprises:
a plurality of tubes (<NUM>) comprising:
a first end (<NUM>); and
a second end (<NUM>), wherein each tube of the plurality of tubes (<NUM>) extends from the first end (<NUM>) to the second end (<NUM>) in a lengthwise direction, and wherein each tube of the plurality of tubes (<NUM>) is spaced from adjacent tubes in a height-wise direction and a widthwise direction, the heat exchanger being characterized in that the plurality of tubes (<NUM>) is stacked to create a concave profile in the height-wise direction and widthwise direction, and wherein the concave profile extends an entire length of the plurality of tubes in the lengthwise direction.