A plate fin heat exchanger includes adjacent flow paths that transfer heat from a hot flow to a cooling flow. The flow paths are defined by a combination of plates and fins that are arranged to transfer heat from one flow to another flow. The plates and fins are created from sheet metal material brazed together to define the different flow paths. Thermal gradients present in the sheet material create stresses that can be very high in certain locations. The stresses are typically largest in one corner where the hot side flow first meets the coldest portion of the cooling flow. In an opposite corner where the coldest hot side flow meets the hottest cold side flow, the temperature difference is much less resulting in unbalanced stresses across the heat exchanger structure. Increasing temperatures and pressures can result in stresses on the structure that can exceed material and assembly joint capabilities.
Turbine engine manufactures utilize heat exchangers throughout the engine to cool and condition airflow for cooling and other operational needs. Improvements to turbine engines have enabled increases in operational temperatures and pressures. The increases in temperatures and pressures improve engine efficiency but also increase demands on all engine components including heat exchangers. Improved heat exchanger designs can require alternate construction techniques that can reduce the feasible practicality of implementation.
Turbine engine manufacturers continue to seek further improvements to engine performance including improvements to thermal, transfer and propulsive efficiencies.
In a featured embodiment, a method of forming a cast heat exchanger plate includes forming at least one hot core plate defining internal features of a one piece heat exchanger plate and at least one first set of interlocking features. At least one cold core plate is formed defining external features of the heat exchanger plate and at least one second set of interlocking features. A core assembly is assembled wherein each hot core plate is directly interlocked to the at least one cold core plate. A wax pattern is formed with the core assembly. An external shell is formed over the wax pattern. The wax pattern is removed to form a space between the core assembly and the external shell. The space is filled with a molten material and cures the molten material. The external shell is removed. The core assembly is removed.
In another embodiment according to the previous embodiment, a top half cold plate is formed defining top surface external features of the one piece heat exchanger plate and a bottom half core plate is formed defining bottom surface external features of the one piece heat exchanger plate and the core assembly is assembled including assembling the top half cold plate and the bottom half core plate to corresponding one of the at least one hot core plates to define top and bottom external features of a completed one piece heat exchanger plate.
In another embodiment according to any of the previous embodiments, structures are formed defining top surface external features and bottom surface external features with wax as part of the wax pattern.
In another embodiment according to any of the previous embodiments, the external features defined by the cold core plate include fin portions extending from top and bottom surfaces of a plate portion of a completed one piece heat exchanger.
In another embodiment according to any of the previous embodiments, the external features are defined by the cold core plate include thermal transfer augmentation features.
In another embodiment according to any of the previous embodiments, the external features defined by the cold core plate include an open cooling channel disposed between at least two plate portions of the completed one piece heat exchanger.
In another embodiment according to any of the previous embodiments, the cold core plate includes a top, a bottom, a lock side and a slip side. Forming the cold plate includes forming the at least one second set of interlocking features to include at least two pedestals on the top of the slip side and two pedestals on the bottom of the lock side and forming at two indentations on a bottom of the slip side and two indentations on the top of the lock side.
In another embodiment according to any of the previous embodiments, the internal features defined by the hot core plate include internal passages extending through a plate portion of a completed one piece heat exchanger plate.
In another embodiment according to any of the previous embodiments, each of the hot core plates includes a top, a bottom, a lock side and a slip side. Forming the hot core plate includes forming the at least one first set of interlocking features as at least two tabs on the bottom of both the lock side and the slip side and forming at least two slots on both the lock side and the slip side.
In another embodiment according to any of the previous embodiments, forming each of the hot core plates includes defining an inlet face and a plurality of inlets corresponding to the internal passages and the slip side defines an outlet face and a plurality of outlets corresponding to the internal passages.
In another embodiment according to any of the previous embodiments, the hot core plates are placed relative to the cold core plates such that the external features defined by the cold core plates are transverse to the internal features defined by the hot core plates.
In another embodiment according to any of the previous embodiments, interlocking one of the at least one first interlocking features and at least one of the second interlocking features with a portion of the wax pattern to secure an orientation between the two hot core plates and the cold core plate.
In another embodiment according to any of the previous embodiments, the cold core plates are spaced apart from the hot core plates and held in a spaced apart orientation by the wax pattern.
In another featured embodiment, a core assembly for a cast heat exchanger includes at least one hot core plate defining internal features of a heat exchanger plate in the cast heat exchanger and at least one first set of interlocking features. At least one cold core plate that includes structures defining external features of the heat exchanger plate and at least one second set of interlocking features. The at least one cold core plate is interlocked with the at least one hot core plate.
In another embodiment according to the previous embodiment, a top half cold plate defines top surface external features of the heat exchanger plate. A bottom half core plate defines bottom surface external features of the heat exchanger plate. The top half cold plate and the bottom half core plate are interlocked to a corresponding one of the at least one hot core plates to define top and bottom external features of a completed one piece heat exchanger plate.
In another embodiment according to any of the previous embodiments, the external features are defined by the cold core plate includes at least one of fin portions and augmentation structures disposed on top and bottom surfaces of the completed heat exchanger plate.
In another embodiment according to any of the previous embodiments, the external features defined by the at least one cold core plate include an open cooling channel disposed between at least two plate portions of the heat exchanger plate.
In another embodiment according to any of the previous embodiments, the at least one cold core plate includes a top, a bottom, a lock side and a slip side. The at least one second set of interlocking features includes pedestals disposed on the top of the slip side and the bottom of the lock side and indentations on the bottom of the slip side and the top of the lock side.
In another embodiment according to any of the previous embodiments, the internal features defined by the at least one hot core plate include internal passages extending through the plate portion in the case heat exchanger.
In another embodiment according to any of the previous embodiments, at least one hot core plate includes a top, a bottom, a lock side and a slip side. The at least one first set of interlocking features includes tabs on the bottom of both the lock side and the slip side and slots on the top of both the lock side and the slip side.
In another embodiment according to any of the previous embodiments, the at least one hot core plate includes features defining an inlet face, an outlet face and a plurality of inlets and outlets corresponding to the internal passages.
In another embodiment according to any of the previous embodiments, the at least one cold core plate is disposed within the core assembly such that the defined external features are transverse to the internal features defined by the at least one hot core plate.
In another embodiment according to any of the previous embodiments, at least two cold core plates are interlocked together and at least three hot core plates interlocked together.
Although the different examples have the specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples.
These and other features disclosed herein can be best understood from the following specification and drawings, the following of which is a brief description.
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The example cast plate 12 is a single piece unitary cast item that includes plate portions 22 that define the plurality of passages 32. Each of the passages 32 extend between an outlet face 28 and an inlet face 34. The inlet face 34 includes the inlets 36 that correspond with the passages 32 through the plate portions 22. The outlets 30 are defined on the outlet face 28. Cooling channels 26 are defined between each of the plate portions 22 and include the fin portions 24 that extend from top and bottom surfaces 38, 40. Moreover, fin portions 24 extend from top and bottom surfaces 38, 40 of the plate portions 22 within the cooling channels 26 such that each of the plate portions 22 include substantially uniform features.
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The cast plate 44 illustrated in
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Each of the cast plates 12, 42, 44 and 46 is formed as a single unitary structure using a casting process. The casting processes utilizes a core assembly to define the internal and external features and structures. Molten material is introduced into a mold supporting the core assembly and defining internal and external features according to known molding processes. The core assembly is removed once the molten material has solidified to provide the single piece unitary cast plate. As appreciated, a core assembly including multiple plate portions 22 can be complex. A core assembly according to a disclosed embodiment simplifies assembly and enables scalability with common components.
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The top plate 86 and the bottom plate 88 are similarly configured to the cold plates 52 but include structures for forming external features such as the fins on one surface of a single plate portion.
Each of the cold core plates 52, top plate 86 and bottom plate 88 include a second set of interlocking features. In one disclosed example, the second set of interlocking features include pedestals 58 that are receivable within indentations 60. The plate 52 includes a slip side 62 and a lock side 64. In this example, the pedestals 58 extend from a top surface 76 on the slip side 62 and from the bottom surface 78 on the lock side 64. Similarly, indentations 60 are provided on the top surface 76 on the lock side 64 and on a bottom surface 78 on the slip side 62. In this example, there are two pedestals 58 and two corresponding indentations 60 provided on both sides of the cold core plates 52. The placement of pedestals 58 and indentations 60, are provided to enable stacking of the cold core plates 52 in a manner that defines the required spacing and that enables stacking of corresponding hot core plates 54 between the cold core plates 52. The pedestals 58 therefore includes a height that corresponds with a depth of the indentation 60 that maintains the spacing while also preventing lateral movement between linked cold core plates 52.
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The core assembly 50 is assembled by interlocking corresponding cold core plates 52 and hot core plates 54 in a configuration determined to provide a cast plate including a desired number of plate portions 22, channel portions 26 and fin portions 24.
Once the core assembly 50 is assembled another step indicated at 114 is performed that includes forming a wax pattern shown at 100. The wax pattern 100 surrounds the surfaces of the core plates 52 and 54 and locks the core assembly 50 within a desired orientation. Each of the core plates 52 and 54 are spaced apart from each other and held in the spaced apart orientation by the wax pattern 100. The wax used for the wax pattern 100 interlocks features of the core assembly 50 on a slip side 102 and a lock side 104 to hold it within a desired orientation.
In this example, interlocking is provided by the pedestals 58 of the cold core plates 52 extending through a surface of the wax pattern 100. Additionally, the wax of the wax pattern fills the indentations as is indicated at 108 as well as the open slots 72 on the top surface of the corresponding hot core plates 54 as is indicated at 106. Accordingly, each of the core plates 52 and 54 include features that interlock within the wax pattern 100 to maintain a desired position and orientation of the plates 52, 54 relative to each other.
The method includes the further step indicated at 116 of forming a shell around the wax pattern 100. The example molding method utilizes the wax pattern 100 as a base that is coated with a ceramic slurry material to create a shell with a defined thickness. Once the ceramic slurry has coated the wax pattern 100 to a desired thickness, the wax is removed to form a ceramic shell 110. The ceramic shell 110 includes the core assembly 50. The ceramic shell 110 is utilized for forming the completed cast part. The ceramic shell 110 interlocks with the core assembly 50 to maintain the position of the core plates 52 and 54 during molding operation.
A casting operation as is schematically indicated at 118 is performed using the ceramic shell 110. In one example casting operation, the ceramic shell 110 is mounted within a casting furnace 122 and molten material is introduced into the ceramic shell 110. The molten material is allowed to solidify for a defined time.
Once solidified, the ceramic shell 110, is removed from the casting furnace 122 and the ceramic shell 110 is removed along with the core assembly 50 as is indicated at 120. The ceramic shell 110 and core assembly 50 are removed using known methods and processes. It should be understood, that although an example molding process is disclosed and explained by way of example, other molding and casting processes are within the contemplation of this disclosure.
The example identical cold and hot plates enable construction of different core assemblies for forming different cast plate structures of varying sizes and thermal transfer capabilities.
Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the scope and content of this disclosure.
This application is a divisional of U.S. application Ser. No. 16/271,308 filed on Feb. 8, 2019 which claims priority to U.S. Provisional Application No. 62/647,091 filed on Mar. 23, 2018.
Number | Date | Country | |
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62647091 | Mar 2018 | US |
Number | Date | Country | |
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Parent | 16271308 | Feb 2019 | US |
Child | 17902352 | US |