BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to heat exchangers, and more particularly to plate-stack heat exchangers.

2. Description of Related Art

Heat exchangers such as, for example, tube-shell heat exchangers, are typically used in aerospace turbine engines. These heat exchangers are used to transfer thermal energy between two fluids without direct contact between the two fluids. In particular, a primary fluid is typically directed through a fluid passageway of the heat exchanger, while a cooling or heating fluid is brought into external contact with the fluid passageway. In this manner, heat may be conducted through walls of the fluid passageway to thereby transfer energy between the two fluids. One typical application of a heat exchanger is related to an engine and involves the cooling of air drawn into the engine and/or exhausted from the engine.

However, typical tube shell design heat exchangers have structural issues when their cantilevered tube bundles are exposed to typical aerospace vibration environments. In addition, there can be significant bypass of flow around the tubes on the low pressure side of the heat exchanger, resulting in reduced thermal effectiveness as well as other adverse system impacts such as excessive low pressure flow. Subsequently, the heat exchangers either fail, or are heavy, expensive, and difficult to manufacture.

Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved heat exchangers. The present disclosure provides a solution for this need.

SUMMARY OF THE INVENTION

A heat exchange device includes a first section and a second section. Each of the first and second sections includes flow passages configured for heat exchange between heat exchange fluid within the flow passages and fluid external of the flow passages. A center manifold is disposed between the first and second sections. Heat exchange fluid enters the manifold at one end, passes through the first and second sections and exits the manifold at the opposing end.

Each of the flow passages can have a bend at an outer edge of the heat exchange device configured to return high pressure fluid to the center manifold. Each of the bends can be equal in radius to allow for uniform distribution of fluid flow. Each of the flow passages can be dimensionally the same to create uniform flow throughout each of the first and second sections. Each of the flow passages can define an external air inlet and an external air outlet.

The center manifold can include a first plenum at one end configured to allow air to enter the center manifold and a second plenum on the opposing side configured to allow air to exit the center manifold. Fluid can flow through the first plenum into an air inlet of a respective flow passage within the first and second sections and enter the center manifold through and air outlet of the respective flow passage. The fluid can exit the center manifold through the second plenum.

Each of the first and second sections can include plate-fin core sections in a stacked arrangement. Each of the flow passages can include structures such as fins, pins or vanes within the flow passage extending from the passage configured to act as secondary heat transfer and structural elements. The secondary heat transfer and structural elements can form a solid matrix configured to limit wear of the device due to relative motion within the device. The device can further include a housing surrounding the heat exchange device to provide a tight seal and configured to prevent air from flowing around the flow passages. The first and second sections and the center manifold can be created through the use of additive manufacturing.

These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein:

FIG. 1 is a perspective view of an exemplary embodiment of a heat exchange device constructed in accordance with the present disclosure, showing first and section sections and a center manifold;

FIG. 2 is a detailed cross-sectional perspective view of the flow passage of each of the first and second sections of FIG. 1, showing hot and cold fins running in directions perpendicular to one another;

FIG. 3 is a detailed perspective view of the flow passage of each of the first and section sections of FIG. 1, showing angled separators and the flow direction for hot fluid through the flow passages;

FIG. 4a is a cross-sectional view of the center manifold of FIG. 1, showing a plurality of sheets spanning the width of the center manifold, structurally connecting inner loops of the first and second sections and separating the flows at flow passage inlet and outlet; and

FIG. 4b is an alternate cross-sectional view of the center manifold of FIG. 1, showing a plurality of sheets spanning the width of the center manifold connecting outer sheets of the flow passages of the first and second section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of a heat exchange device in accordance with the disclosure is shown in FIG. 1 and is designated generally by reference character 100. Other embodiments of the heat exchange device in accordance with the disclosure, or aspects thereof, are provided in FIG. 2-4b, as will be described. The systems and methods described herein can be used in turbine engines exposed to high pressure and high temperatures, for example in aerospace application.

With reference to FIG. 1, a heat exchange device 100 in accordance with the present disclosure is shown. The device includes a first section 102 and a second section 104. The first and second sections 102, 104 are two identical plate-fin core sections each made up of flow passages 110 configured for heat exchange between heat exchange fluid within the flow passages 110 and fluid external of the fluid passages 110. The first and second sections 102, 104 are separated by a center manifold 106 configured to allow high pressure fluid to enter the manifold 106 at one end 112, pass into the flow passages 102, 104 on either side of the manifold 106, and return to the manifold 106 to exit the manifold 106 at the opposite end 114. More specifically, the center manifold 106 includes a first plenum 112a at one end and a second plenum 114a on an opposing end. Each of the flow passages 110 includes an air inlet 120 and a separate air outlet 122 (see FIG. 2) leading to and from the center manifold 106, respectively. Fluid flows into the first plenum 112a of the center manifold 106, passes through a respective air inlet 120 of a flow passage 110, follows a bend/loop 130 of the flow passage 110, enters the center manifold 106 again through the air outlet 122 and then exits the center manifold 106 through the second plenum 114a. The design for the first and second sections 102, 104 and the center manifold 106 facilitates installation of the proposed heat exchange device 100 in place of an existing tube-shell unit.

With continued reference to FIGS. 1 and 2, each of the flow passages 110 includes a bend or loop 130 at the outer edges of the device 100 to return the fluid to the center manifold 106. The bulk of the heat transfer occurs within the flow passages 110 of the first and section sections 102, 104. The bends 130 of each flow passage 110 are equal in radius and each flow passage 110 is dimensionally the same to achieve uniform distribution of fluid flow within the first and second sections 102, 104 and achieve optimal thermal effectiveness. This similarity in structure also facilitates quick and accurate prediction of thermal performance. In further embodiment, the flow passages may vary in length so as to fit into designated spaces with opposing sides that are not perpendicular to one another.

The flow passages 110 are in stacked arrangement such that the air flow direction loops back to the center manifold 106. In one embodiment, heat transfer elements, such as fins 132, 134 (see FIG. 2a) are included within each of the flow passages 110. The fins 132, 134 can be either hot fins 132 or cold fins 134 that form a solid matrix to provide thermal and structural connection. Fins 132 can run parallel to fins 134 when the fins 132 have openings to allow flow through the flow passage. Therefore, the device 100 does not have fretting or other wear issues associated with relative motion between tubes and supporting structure of typical tube-shell heat exchange designs.

As shown in FIG. 3, a cross-sectional view of the center manifold 100 illustrating angled center manifold plates 138. The flow rate of the hot fluid flowing (illustrated with arrows) within the center manifold 106 varies as a function of a distance along a flow length of the manifold in both the inlet and outlet sections of the center manifold 106. The cross-sectional area increases with increased flow in regions of both the inlet and outlet manifolds to reduce pressure drop as well as to achieve a more uniform static pressure distribution along the flow length of the manifold 106 that helps to achieve more uniform distribution of flow among each flow passage bend 130. This in turn improves the overall thermal effectiveness of the device relative to a manifold configuration with nearly uniform manifold inlet and outlet cross-sectional flow areas.

FIGS. 4a and 4b illustrate two embodiments of a cross-section of the center manifold 106. In both embodiments continuous sheets 124 span across the center manifold. In both embodiments shown in FIGS. 4a and 4b, the sheets provide load paths to react against pressure forces pulling the first and second core sections 102 and 104 apart. The sheets also separate the hot inlet and outlet flows. In FIG. 4a, the sheets extend from inner loops of cold fluid between the first and second sections 102 and 104. In FIG. 4b the sheets extend straight across from outer sheets of the flow passages. The tight radius of each flow passage 110 at the outer edges of the heat exchanger 100 reduces hoop stress, reducing the amount of material required to contain the high pressure fluid compared to traditional heat exchanger fluid turning methods such as external headers or internal miter sections with thick closure bars.

The device 100 as a whole is stiffer than a typical tube-shell heat exchanger, which typically drives critical mode frequencies above regions of concern, due to the fins 130 and 132 and parting sheets forming a solid matrix. In further embodiments, a housing can be included which tightly surrounds the device to provide a tight seal and prevent air from flowing around or outside of the air passages. In this embodiment, bends/loops of the flow passages can be modified to tightly align with the housing. In addition, the secondary heat transfer and structural elements can extend from the outermost flow passages to the housing containing the low pressure fluid to create the tight seal around the heat exchange device. The bends and loops are created during manufacturing therefore the tightness of the loops or exact shapes can be modified as needed. The first and section sections 102, 104 and the center manifold 106 as shown and described can be formed using the techniques of additive manufacturing.

The methods and systems of the present disclosure, as described above and shown in the drawings, provide for a heat exchange device with superior properties including a center manifold to provide improved structural integrity. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.