JP2019535987A - Structural heat exchanger - Google Patents

Abstract

In some embodiments, a structural heat exchanger is provided that uses liquid fuel as a coolant as the liquid fuel moves around an area (eg, a chamber) of the engine. The shape of the coolant channel of the heat exchanger can be configured to change the pitch angle as it goes to the top of the region, taking into account the area of the region where higher cooling characteristics may be required. In some embodiments, the fuel diverter that allows for the first passage of fuel through the coolant channel can be configured to boost the passage of fluid through the coolant channel at a uniform pressure, and the volume of the fluid Fluid moves from the initial point of entry further away despite a decrease in. In some embodiments, this may be implemented as an annular shaped fuel diverter with a gradually decreasing radial cross section. [Selection diagram] FIG.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of US Provisional Patent Application No. 62 / 382,722, filed September 1, 2016 and entitled “STRUCTURE HEAT EXCHANGER”. To do. The disclosure is incorporated herein by reference in its entirety and for all purposes.

  The subject matter disclosed herein generally relates to coolant systems. More specifically, the present disclosure relates to structural heat exchangers having various industrial applicability.

  Traditionally, coolant systems for industrial applications are manufactured using a removable manufacturing method, which means that larger materials are used and are scraped in small increments until the desired structure is formed. Yes. Therefore, these designs are limited by the manufacturing method used. In addition, coolant systems are conventionally constructed with multiple parts and need to be welded and joined together. In order to facilitate manufacturing and replication, these designs therefore exhibit a number of breakage points or other high stress areas. Furthermore, the optimal shape and cooling design for heat transfer is not used in order to take advantage of more reliable ablation manufacturing methods. Therefore, it is desirable to develop new methods of making heat exchange coolant systems and their various components.

  Aspects of the present disclosure are presented for structural heat exchanger designs with optimal heat transfer and cooling characteristics that can be made using additive manufacturing techniques.

  In some embodiments, the heat exchanger includes a plurality of coolant channels that are each defined by a wall that at least partially surrounds a region that contains a large amount of heat relative to a surrounding amount, and an open channel space in the wall. And including a housing including a plurality of coolant channels configured to allow fluid to flow through the wall, the housing being fabricated using additive manufacturing.

  In some embodiments of the heat exchanger, each of the plurality of coolant channels has at least a portion of a bean-shaped cross-sectional area.

  In some embodiments of the heat exchanger, each of the plurality of coolant channels has at least a portion of a trapezoidal shaped cross-sectional area having rounded corners.

  In some embodiments of the heat exchanger, each of the plurality of coolant channels has at least a portion of a cross-sectional area having a shape with parallel concave curves, one of the concave curves being a high heat quantity region. The second concave curve is at a position closest to the outer wall side farthest from the high heat quantity region.

  In some embodiments of the heat exchanger, each of the plurality of coolant channels has a cross-sectional area of a shape defined by satisfying a plurality of boundary conditions that define one or more functional or structural properties of the wall. Have at least a portion. In some embodiments, the plurality of boundary conditions include: at least one thermal condition that the wall must satisfy; at least one structural condition that the wall must satisfy; at least one for the wall that the wall must satisfy One material property; and at least one material property of the coolant channel that the plurality of coolant channels must satisfy. In some embodiments, the plurality of boundary conditions is a first plurality of boundary conditions applied to a first location of the coolant channel, and each of the plurality of coolant channels includes a first plurality of boundary conditions. The second position has at least a part of the cross-sectional area of the second shape defined by satisfying a plurality of second boundary conditions different from the conditions.

  In some embodiments of the heat exchanger, the pitch angle of the plurality of coolant channels varies at different locations within the wall.

  In some embodiments of the heat exchanger, at least one of the plurality of coolant channels has a first cross-sectional area shaped in a first shape in a first position and in a second shape. The molded second cross-sectional area is included at the second position. In some embodiments, the first shape is a bean shape and the second shape is an ellipse.

  In some embodiments of the heat exchanger, the plurality of coolant channels vary in cross-sectional area size at different locations within the wall.

  In some embodiments of the heat exchanger, the wall is shaped as a cylinder.

  In some embodiments of the heat exchanger, the wall includes a flat plate that houses at least a portion of the plurality of coolant channels.

  In some embodiments of the heat exchanger, the housing is made as a single part using additive manufacturing.

  Some embodiments are shown by way of example and are not limited to the figures of the accompanying drawings.

Provide a description of a traditional coolant system that serves as a comparison point to highlight the novel and non-obvious features of the present disclosure. 1 shows a fuel diverter having a uniform annular radius. FIG. 6 illustrates a fuel diverter in the form of a decreasing radius annulus, according to some embodiments. FIG. 4 shows a diagram of fluid delivered through each channel from a fluid diverter. FIG. 4 shows a flow vector simulation diagram of liquid direction and magnitude as fluid enters a branch from a fluid diverter, according to some embodiments. FIG. 2 shows a translucent view of the bottom of an engine utilizing the heat exchanger of the present disclosure. FIG. 4 shows a close-up view of a fuel diverter with a much smaller radius to its end as it wraps around the periphery of the bottom of the engine. 8a-8b. A cross section of typical cooling channels and their heat transfer characteristics are shown. FIG. 6 shows a trapezoidal passage as a cross-sectional area of a cooling passage in some embodiments of the present disclosure and according to some embodiments of the present disclosure. FIG. 6 shows a trapezoidal passage as a cross-sectional area of a cooling passage in some embodiments of the present disclosure and according to some embodiments of the present disclosure. FIG. 6 shows a trapezoidal passage as a cross-sectional area of a cooling passage in some embodiments of the present disclosure and according to some embodiments of the present disclosure. FIG. 6 illustrates a bean shape as a cross-sectional area of a cooling passage according to some embodiments. FIG. It shows how the top of the cooling passage can be shaped more like a circle or an ellipse. FIG. 3 shows a top view of a regenerative cooling passage according to some embodiments. FIG. 4 shows different views of how the pitch, cross-sectional shape, and size of the cooling passages can change as the channel flows up along the chamber wall of the structure, according to some embodiments. FIG. 4 shows different views of how the pitch, cross-sectional shape, and size of the cooling passages can change as the channel flows up along the chamber wall of the structure, according to some embodiments. 2 shows an example of a cross-sectional area of a bean coolant channel. It shows how a cylinder wall with a rectangular coolant channel looks. An example of what a cylinder with a bean-shaped channel would look like is shown. The thermal contours for the results of the rectangular cross-section channel are shown. The thermal contours for the circular cross-section channel results are shown. The thermal contours for the bean section channel results are shown. Figure 5 shows an enlarged visual result of a rectangular cross-section portion to emphasize temperature zoning. Figure 5 shows an enlarged visual result of a circular cross-section portion to emphasize temperature zoning. Fig. 5 shows an enlarged visual result of a bean shaped cross section to emphasize temperature zoning. FIG. 4 illustrates an example of a flat plate with bean-shaped coolant channels from different angles, according to some embodiments. FIG. 4 illustrates an example of a flat plate with bean-shaped coolant channels from different angles, according to some embodiments. Fig. 5 shows a flat plate with bean-shaped coolant channels on the top, but with a corrugated surface at the bottom that matches the concave shape of the bean. Fig. 5 shows a flat plate with bean-shaped coolant channels on the top, but with a corrugated surface at the bottom that matches the concave shape of the bean. Develop structural heat exchanger with any number of coolant channels, with different cross-sectional shapes, constructed to meet different needs of different industrial applicability according to some embodiments The flowchart of the example of a method for doing is shown. FIG. 6 is a block diagram illustrating machine components that can read instructions from a machine-readable medium and execute any one or more of the methodologies discussed herein, according to some example embodiments. It is.

  Coolant systems for various industrial applications rely on traditional ablation manufacturing methods for their production. As a result, their design reflects the limitations of the manufacturing method used. High performance industrial devices are usually made of two or more parts and are welded or joined together using an O-ring or other gasket to seal the high pressure area. These designs exhibit a number of break points.

  The manufacture of coolant systems by additive manufacturing (AM) provides a number of improvements not previously seen. The ability to print a series of heat exchanger channels in a single part using AM technology increases durability and ease of use while reducing weight. The speed at which additive manufacturing can produce parts overtakes even the quickest traditional manufacturing operations. The ability to create new shapes that could not be achieved with conventional manufacturing methods has opened the door to countless performance improvements.

  In fact, additive manufacturing techniques make it possible to produce even the most complex shapes. This allows the designer to devise an optimized structure without the burden of designing for conventional manufacturing techniques.

  Aspects of the present disclosure are presented for structural heat exchanger designs with optimal heat transfer and cooling characteristics that can be created using additive manufacturing techniques. The heat exchanger can be made as a single piece without joints, couplings, or any other area that can present a risk of damage. The design described herein and the principles for deriving the design may reduce the weight of industrial equipment to eliminate the need for couplers and other external hardware. In general, the weight of industrial equipment can be optimized to also exclude the inclusion of external materials around the required structure. Industrial equipment can also be designed to be very energy efficient with optimal flow for fuel and other fluids with minimal head loss while maintaining higher pressures.

  In some embodiments, a structural heat exchanger is presented that utilizes liquid fuel as a coolant as the liquid fuel moves through the perimeter of the hot engine chamber. The shape of the coolant channel that begins at the fuel diverter and flows through the heat exchanger passage changes angle as it goes to the top of the hot engine chamber, taking into account the region of the chamber where higher cooling characteristics may be required It can be constituted as follows. In some embodiments, the fuel diverter that allows the first passage of fuel through the coolant channel can be configured to boost the passage of fluid through the coolant channel at a uniform pressure, and the volume of fluid Despite the decrease, fluid moves further from the initial input point. In some embodiments, this may be implemented as an annular shaped fuel diverter having a gradually decreasing radial cross section.

  In some embodiments, the cross-sectional area of the coolant channel may be specially shaped to meet a particular purpose or boundary condition. For example, the boundary condition may specify that the coolant channel should generate a uniform heat flux to reduce thermal distortion along and at any particular point in the industrial equipment wall. . In some embodiments, this may be accomplished by forming the coolant channel to have a trapezoidal shape, or else a bean-shaped cross-sectional area. In some embodiments, when the coolant channel approaches the fuel injector portion of the engine and fluid is about to be dispensed, the trapezoidal or bean shape of the coolant channel is elliptical along the channel path. It can be gradually converted into a shape or a circular shape.

  In some embodiments, a method is provided for deriving a coolant channel design based on meeting a plurality of boundary condition characteristics. These characteristics are that the inner wall meets certain heat flux conditions, the walls containing the channel meet certain heat capacities, and certain parts of the channel meet certain pressure conditions to meet different needs at specific locations. And changing these characteristics at various different points along the channel's path.

  In some embodiments, the structural heat exchanger includes a plurality of coolant channels having variable cross-sectional areas. Furthermore, for any single coolant channel, the cross-sectional regions can gradually change shape to meet changing boundary conditions at their locations. In some embodiments, the coolant channel layout may be in the shape of a cylinder, plate, corrugated plate, or other arrangement consistent with the principles of the present disclosure.

  Structural heat exchangers according to various embodiments described herein include gas generator turbomachines, power generation heat exchangers, automotive engines, HVAC units, server cooling modules, and power plant reactors and a variety of high power demands. It can be used in a wide variety of non-limiting industrial applications, including applications that require high performance heat exchange, such as modern vehicles.

  FIG. 4 provides a context for a coolant channel in a heat exchanger and provides a description of a traditional engine design that serves as a comparison point to highlight new and non-obvious features of the present disclosure. Here, the cross-sectional shape of a typical regenerative cooling channel using a conventional manufacturing method is shown. Traditional production of multi-materials tends to result in rectangular regenerative cooling channels.

  As mentioned above, aspects of the present disclosure provide a regenerative coolant channel that is typically housed within an engine designed and manufactured to address any and all of these problems found in typical engine design and manufacture. A structural heat exchanger is provided.

  With reference to FIGS. 2-7, embodiments of a fuel diverter that address some of the described problems according to some embodiments will be discussed.

  Referring to FIG. 2, a fuel diverter having a uniform annular radius is shown. A fuel diverter may be placed at the bottom of the engine to allow the fuel to flow upward along the engine wall and act as a coolant before it is injected at the top of the chamber. The gray scale gradation indicates a turbulent flow simulation of regenerative cooling by the additive manufacturing engine. The non-uniform turbulence present in this turning section of the engine indicates an invalid diverter design.

  With reference to FIG. 3, a fuel diverter in the form of a decreasing radius annulus according to some embodiments is presented. Use a decreasing radius annular fuel diverter to reduce turbulence and ensure equal mass flow fuel to each regenerative cooling channel (eg, 48 total cooling channels) supplied by the fuel diverter be able to. The annulus begins with a diameter equal to the diameter of the fuel inlet and decreases in proportion to the amount of fuel that branches into each branch channel. This provides a constant pressure annulus with equal mass flow supplied to each channel. This ensures uniform cooling of the chamber walls by regenerative cooling and then ensures proper distribution of the fuel injected by the attached fuel injector passage. The standard turning path does not take into account the pressure drop due to turbulence. This results in an unexpected and non-uniform distribution of mass flow among the various identical turning channels. Such non-uniform distribution of fluid can result in potentially destructive hot spots and instabilities.

  FIG. 4 shows a diagram of the fluid delivered through each channel from the fluid diverter. The grayscale tone indicates that the pressure drop in each passage is the same, partly due to a decrease in the radius of the annulus.

  FIG. 5 shows a flow vector simulation diagram of liquid direction and magnitude as fluid enters the branch from the fluid diverter, according to some embodiments. As shown, the direction of fluid branching is generally uniform in that the turbulent flow is generally evenly distributed as it enters the passage. In addition, the magnitude of each flow vector is generally the same length, indicating a generally uniform pressure. This figure may represent each passage because the radius of the fluid diverter is decreasing.

  In general, the diverter configuration shown in FIGS. 4 and 5 shows how a decreasing annular diverter can deliver the desired mass flow rate to any number of passages. It always maintains a directional flow of fuel where the flow direction and fluid path determined by the geometric domain are maximally uniform. This design can supply the desired mass flow rate to many orifices. If a specific non-uniform distribution of mass flow between the orifices is desired, the branch orifices may be the same or different in size. A decreasing annular diverter can maintain a desired mass flow rate over a wide range of input conditions such as pressure or mass flow rate. It can also be used to provide optimal flow rates for various fluid phases, reactive or unsteady flows by taking these changes into account when forming the constant pressure annulus.

  According to some embodiments, the diverter design of the present disclosure may be applied to other fluid passages. For example, the divertor annular design described herein of decreasing radius utilizes an injector orifice interface, or generally one or a few fluid entry points, and can provide a large number or multiple fluid passages with a substantially uniform pressure drop. Applicable to any set of fluid passages for supplying fluid to

  Referring to FIG. 6, a translucent view of the bottom of the engine is shown, according to some embodiments, showing the fuel diverter 610 in relation to other components. These include a fuel inlet 605 and a nozzle 615. Multiple coolant channels are also shown. As shown, and according to a closer view of FIG. 7, the fuel diverter 610 has a much smaller radius to its end as it wraps around the bottom of the engine. In some embodiments, the end of the fuel diverter may be connected to a starting point to form a closed loop, and in other cases the end is cut. FIG. 7 also shows how the fuel inlet is coupled to the fuel diverter inlet passage.

  With reference to FIGS. 8A-16, consider an embodiment of a regenerative cooling channel that addresses some of the problems discussed above, according to some embodiments.

  Regenerative (or regenerative) cooling is widely used as a means of removing heat from the inner wall of the engine chamber. The cooling channel resides in the inner wall, which may generally be included in the casing or housing structure as part of the entire engine or other structure. Pressurized fluid is supplied through a channel embedded in or wrapped around the chamber wall. This fluid is used as a relaxation fluid into which heat flows. This process cools the chamber walls: preventing material degradation, melting, undesirable phase transitions or particle transformations and extending the life of the part.

  Standard regenerative cooling schemes include wrapping the chamber with small fluid transport channels, forming a rectangular channel in the engine wall, and forming a circular channel in the engine wall. Additive manufacturing allows the implementation of many advanced channel designs that would not be possible to manufacture using traditional manufacturing methods.

  Referring to FIGS. 8A and 8B, typical cooling channel cross sections and their heat transfer characteristics are shown. Rectangular channels are commonly used because of their ease of manufacture and good heat transfer characteristics. The rectangular channel also provides a large gas sidewall surface area to increase heat transfer, as opposed to other geometric shapes. However, this method is not optimal because the temperature distribution is inferior due to the rectangle. The sharp edges of the rectangular channels cause stress concentrations at the corners of each individual channel, as evidenced by the uneven color gradation at the corners of FIG. 8B. Although stress concentrations caused by sharp edges are undesirable, this method is still commonly used because it is easy to manufacture.

  Circular channels are structurally preferred according to certain criteria because they distribute pressure in all directions and prevent stress concentration. Similarly, the maximum surface area of the circular channel increases the heat flow to the relaxation fluid. However, an array of circular channels distributed azimuthally around the chamber axis results in a non-uniform distribution of temperature along the inner wall away from the chamber material itself, resulting in significant thermal stress.

  Although more optimal from a pressurization and heat standpoint, non-circular and non-rectangular shapes for the coolant channels are much more difficult to create using traditional manufacturing techniques. The performance, durability, and long-life benefits they provide are less important than the increased manufacturing costs and additional parts or components required to form such advanced shapes. However, these shapes can be formed quickly and accurately at a very low cost by additive manufacturing.

  The trapezoidal passages shown in FIGS. 9, 10, and 11 and according to some embodiments of the present disclosure provide several advantages of both circular and rectangular passages. They can also be easily manufactured by additive manufacturing. A larger gas sidewall surface allows for better heat transfer to the relaxation fluid. A narrow cross-section closer to the rounded edges and outer walls results in higher pressure differentials caused by high fluid pressure in the channel, and improved stress management due to thermal considerations, which is due to thermal variations due to spatial variations in thermal expansion. Bring stress. FIG. 9 shows the thermal profile along the inner wall of the trapezoidal regenerative cooling channel during normal use. The trapezoidal channel reduces the temperature gradient along the inner wall. FIG. 10 shows a graphic simulation of the heat flux of the trapezoidal coolant channel. As shown, the temperature gradient around the coolant channel is more uniform throughout and reduces any stress points along any corner or edge. FIG. 11 shows another view of heat flux in the elongated portion of the trapezoidal coolant channel design. Even when the channel is curved, the heat flux characteristics remain constant along the same portion of each edge and corner.

  One novel idea for the regenerative cooling channel comes from the discovery that a uniform temperature profile can be achieved with non-constant channel cross sections. The new design method produced a cross section with a nearly uniform temperature profile. This shape is referred to as a “bean” shape, and one example of a coolant channel having this shape is shown in FIG. The pressure distribution is uniform within the bean channel. The distribution of equivalent stress is not uniform across the wall section, but according to some embodiments is minimally optimized by the bean channel for a given thermal structure boundary condition.

  According to the present disclosure herein, the edges of the inner and outer walls of the coolant channel are formed in a parallel concave pattern (similar to beans), but the sides are curved (like beans). Other variations to the bean shape are conceivable, such as a cross-sectional area having a “macaroni” shape that is less straight and looks like the contour of a bent macaroni piece. Laminated modeling can allow each cross-sectional layer to gradually change shape between each other, so that variations that gradually deform between these various shapes are also conceivable.

  To illustrate this, FIG. 13 shows how the top of the cooling passage can be shaped more like a circle or ellipse. Thus, in some embodiments, the cooling passages gradually move from a shape designed for cooling and better heat transfer (eg, trapezoidal or bean shape) to a more uniform shape before the fluid has finished moving. Designed to transition to. In addition, the shape of the passage toward the starting point of the passage, that is, the shape of the passage when the fuel is supplied from the fuel diverter to each cooling passage, may be closer to an ellipse, and then gradually becomes more optimal for cooling. It may change to. These transitions are described in more detail below.

  FIG. 14 illustrates a top view of a regenerative cooling passage according to some embodiments.

  15-16 illustrate different views of how the pitch, cross-sectional shape, and size of the cooling passages can change as the channel flows upward along the chamber wall, according to some embodiments. Typically, cooling channels using traditional manufacturing will never vary in any of these degrees. However, due to the properties available in additive manufacturing technology, these cooling channels can be adjusted in various ways to account for different needs at different points along the engine wall.

  In general, variations in channel cross-sectional shape, size, and pitch can be used to specifically tune turbulence and thus heat transfer. This can be used to control heat transfer and relaxation fluid temperature and pressure. This is particularly important to ensure that the temperature and pressure of the supercritical relaxation fluid exceeds the critical point and gasification or liquefaction is avoided. This is because they potentially damage the engine. By increasing or decreasing the cross-sectional area of the channel, it is possible to optimize the heat transfer to the fluid in the axial direction.

  FIG. 15 shows a bottom view of a cooling channel with their different pitch angles and shape changes in different parts, according to some embodiments. This figure shows only the portion that rises into the throat, since the remainder of the channel flowing out of the throat is enlarged and disappears (see FIG. 16). From this point of view, the changing angle along a single channel indicates a changing pitch. It can also be seen that the cross-sectional area of the single channel changes from a circular area to a bean shape.

  FIG. 16 shows a close-up view of the throat region of the cooling passage according to some embodiments. As shown, the cooling passages are arranged in a spiral, and at this junction, the pitch angles become more horizontal (i.e., increased), in addition to the passages approaching each other, as well as reducing the size of the channels. Changed). In general, none of these properties can be easily reproduced using traditional manufacturing techniques.

Details of the “bean” coolant channel

  This section considers various features inherent in the use of bean-shaped fluid channels in heat exchangers.

  As a background and in part, as described above, fluid heat exchangers use a coolant-filled channel to transfer heat from a solid to a cooler fluid. Traditionally, channels have been limited to rectangular and circular designs. Rectangular channels have a higher heat transfer rate than circular channels, but their corners are structural weaknesses due to stress concentrations. To avoid the choice between structural stability and efficient heat transfer, engineers will modify the rectangular geometry to achieve better structural features without sacrificing heat transfer However, the result was hardly profitable.

  Through research and development, an enhanced channel profile, or bean, was developed. As shown in FIG. 17, the beans are accurately shaped as their names indicate. This shape combines the structural curve of the circular channel with the large surface area of the rectangular channel to create a very efficient and structurally sound heat transfer channel. FIG. 17 shows an example of a cross-sectional area of a bean coolant channel.

  In addition to combining the structural advantages of both traditional shapes, the bean-shaped channel provides more uniform heat transfer across the wall length. It lacks the extreme peaks and valleys of temperature inherent in standard geometry. This uniform distribution reduces the thermal stress in the wall caused by large thermal gradients and non-uniform thermal expansion rates.

  Simulations were performed to compare the effectiveness of heat transfer between rectangular, round and bean shaped channels. A cylinder with an annular cross section and a cooling channel extending along the length was modeled for each shape. These channels were designed to have approximately equal individual channel cross sections, total fluid footprint, and minimum distance from the inner wall. The rectangular channel simulation shape of FIG. 18A serves as all three representative examples. FIG. 18A shows how a cylinder with a rectangular channel looks, while FIG. 18B shows an example of how a cylinder with a bean-shaped channel looks. Thus, one can similarly think about how circular and other shaped channels can be placed around the cylinder.

  In an example set of simulations, steady state coupled fluid-heat transfer simulations were performed using ANSYS 17.1 to capture both convective and conductive heat transfer effects. Nickel was used for the solid and liquid kerosene was used for the liquid. The inner wall of the shape was set at 726 ° C., but the outer wall was modeled as a heat insulator along with the top and bottom surfaces. The inlet was defined with a total mass flow rate of 0.2 kg / s and a temperature of 27 ° C.

Thermal contours for the results of each shape can be found in FIGS. 19, 20 and 21 and are described for a rectangular cross-sectional channel, a circular cross-sectional channel, and a bean-shaped cross-sectional channel, respectively. The thermal benefits of using a rectangular cooling channel over a circular cooling channel can also be seen from the lower temperature in addition to less heat penetration through the wall. Table 1 below confirms these visual indicators as both the average and minimum temperature of the rectangular channel are lower when compared to those of the circular channel. However, according to FIG. 21, the improvement in bean efficiency is evident. The beans effectively cool the chamber compared to both shapes while maintaining a structurally advantageous curve of circular shape. Table 1 demonstrates the superiority of the beans with minimum and average temperatures of 490.28 ° C and 561.36 ° C, respectively.

  Uniform distribution of heat transfer in the bean channel when the resulting visual is magnified and the temperature zone is emphasized, as shown in FIGS. 22, 23, and 24 for rectangular, circular, and bean cross-sectional channels, respectively. Is easily seen. The gray scale tone more clearly shows the respective band temperature contours of the various types of cross-sectional channels. Although rectangular channels can have an unusual shape with respect to heat transfer coefficient, they have a very non-uniform temperature gradient along their walls. The circular shape improves this non-uniform heat transfer but is below average in its cooling. Beans have been shown to be more effective in both important metrics.

  Recent advances in simulation and optimization software combined with additive manufacturing have enabled the creation of optimized bean-shaped fluid heat exchanger shapes. These bean-shaped fluid channels combine the best of both rectangular and circular cooling channels. They have the excellent heat exchange capability of rectangular channels while maintaining the strength characteristics of circular channels. In addition, this shape also allows for a more uniform extraction of heat, which helps to reduce the thermal stress in the wall that is then cooled. These properties allow the bean shape to be much better than previous circular and rectangular designs.

Additional exemplary embodiments of structural heat exchangers

Multi-channel implementation

  In some embodiments, the structural heat exchanger channels may be combined in a truss-like arrangement that includes trapezoidal or bean-shaped channel cross sections and may be combined to meet a specific set of advanced boundary conditions. Good. This can include large pressure fluctuations or thermal fluctuations across the plate, and the gas sidewalls can alternate from one side of the heat exchanger to the other. This embodiment is very practical for countercurrent heat exchanger flows where alternating channels are provided by the outgoing or returning coolant.

Flat plate

  The bean channel heat pipe can be mounted in a non-circular cross-sectional shape. These may include not only flat or curved plates but also more complex and predictably changing shapes. FIGS. 25 and 26 show examples of flat plates with bean-shaped coolant channels from different angles, according to some embodiments. As another example, FIGS. 27 and 28 show a flat plate having bean-shaped coolant channels on the top surface, but with a wavy surface on the bottom surface that matches the concave shape of the bean shape. In this exemplary embodiment, the thermal characteristics of the bottom surface allow for more uniform temperature loss along the bottom surface.

Uneven heat

  Structural heat exchangers can be easily implemented for the principal components of the coolant flow and thermal boundary conditions that vary along the channel direction. For thermal boundary conditions that vary spatially and / or temporally in the principal direction of the coolant flow or in a direction predominantly perpendicular to the channel direction, there must be additional processing of the channel shape. There is a need to resize the channel at the expense of pressure drop to increase flow velocity and thus turbulence. This is a smooth transition of each heat exchanger channel to a corresponding bean-like shape with reduced or increased cross-sectional area, resulting in a flow rate corresponding to the peak heat load across the heat exchanger surface at a particular location. Achieved by increasing or decreasing. Alternatively, an increased mass flow rate can be delivered to a channel having a heat load that varies spatially and / or temporally.

Uneven flow

  In an ideal heat exchanger, coolant can be supplied to the uniform channels so that each channel has the same mass flow rate or a specific flow rate distribution corresponding to the heat load. However, if it is not possible to distribute the coolant uniformly and stably across all channels, changes to the channel shape may be made to take this into account. These changes may take the form of resized and / or reshaped bean channels corresponding to available heat fluxes and flows.

Exemplary industrial applicability

  The following is a description of various types of heat exchanger applications of the present disclosure.

  Gas generator turbomachine: The coolant channel may be embedded in the cylindrical wall of the compressor or expander cycle (or inside the blade itself).

  Power generation heat exchange: Cylindrical heat exchangers with or without a compatible inner surface are ideal for transferring heat from the working fluid to the relaxation fluid (or coolant).

  Automotive engine: Cylindrical heat exchanger used in each combustion cylinder. The channel may have the same boundary conditions as the engine thruster. The fuel or coolant can be used to remove heat from the walls, allowing for higher operating temperatures and less heat loss.

  HVAC unit: Flat plates may be used in HVAC systems as opposed to standard fin and pipe heat exchangers.

  Server cooling: Bean cooling channels can be used in high performance computing environments to draw heat away from the chip instead of the fuel environment. A flat plate using coolant channels may also be used in this case.

  Other examples of structurally optimized heat exchangers of the present disclosure may be applied to jet engines, machine bits, mining bits, brake disk rotors, and injection molds.

Example method of forming a coolant channel

  This section discusses computer-implemented methods for forming and deriving various cross-sectional regions of the coolant channels described herein. As described above, the structure containing the channel may be layered, that is, accessing a CAD file having all the characteristics and specifications for placing solid material to form the structure having the channel. The structure may be configured layer by layer using known additive manufacturing techniques such as 3D printers. For example, developing the CAD file is an important task that the computer-implemented method of the present disclosure can develop. In addition, the method can gradually change the cross-sectional area of any and all channels from layer to layer to form different shapes at different locations along the same channel (see, eg, FIG. 15).

  Referring to FIG. 29, a flow chart 2900 illustrates a structural heat exchange with any number of coolant channels having different cross-sectional shapes, constructed to meet different needs of different industrial applicability. An example method for developing a vessel is provided. In some cases, computer-implemented methods for designing structural heat exchangers can be implemented by manually designing shapes and structures. However, in order for a structural heat exchanger to better fit to satisfy the desired cooling characteristics for a given use case, more accurate techniques should be employed. Flowchart 2900 provides an example of how a computer creates such a structural heat exchanger to meet specified needs.

  According to some embodiments, at block 2905, one or more boundary conditions are set and accessed by a computer configured to perform the method. These inputs can be provided by human engineers who may have calculated various needs or may follow specifications provided by other authorities. Various CAD or CAE (Computer Aided Engineering) tools can be used to calculate and determine these boundary conditions. The boundary conditions can include any number of the following non-limiting examples.

  Thermal: heat flux, ambient / initial temperature, coolant flow rate, surface roughness, radiant heating / cooling

  Structural: internal pressure, channel pressure, external pressure, structural load

  Structural material properties: density, tensile / yield strength, fracture toughness, thermal conductivity, thermal expansion, thermal diffusivity, emissivity, melting point / boiling point, internal stress, heat capacity, specific heat, gain morphology, and phase change information

  Coolant material properties: density, thermal conductivity, thermal diffusivity, emissivity, melting point / boiling point, heat capacity and specific heat

  Material properties can vary in temperature and / or pressure. Not all the listed properties are necessary. Accurate listing of these material properties that change with temperature and pressure gives simulation results that very well represent the physical environment as seen from the heat exchanger.

As an example, structural heat exchanger boundary conditions that create an optimal environment for bean channel implementation include the following:
High heat flux condition inside (gas side wall);
High heat capacity, low temperature coolant flows rapidly through the channel while maintaining liquid phase;
Pressure condition Pcc>Pw> Po,
here:
Pcc: pressure in the coolant channel;
Pw: pressure seen from the high heat flux wall;
Po: Ambient pressure outside the heat exchanger.

  The computer took advantage of these boundary conditions and implemented the methodology described herein to derive a bean shape that has proven to be a good coolant channel.

  In some embodiments, multiple boundary condition sets can be set for each different location of the heat exchanger to meet different cooling needs at various locations. Thus, the boundary conditions can be unique to various locations.

  According to some embodiments, at block 2910, an initial shape of the structural heat exchanger that houses the coolant channel may be created using CAD and CAE tools. This can be viewed as an initial seed start value, where an initial approximate estimate of what the best shape is can be input and received by the computer. A human developer may assist in creating an initial shape that approximately satisfies all boundary conditions. In some embodiments, the computer can provide suggestions using solutions that are known to be able to verify that the boundary conditions are approximately met by some threshold. Depending on the available coolant mass flow rate, the number and size of channels can be selected. This should be done not only to prevent edge cases such as supersonic flow, but also to minimize the boundary layer in the cooling channel.

  At block 2915, the overall channel shape can be set. Again, this may be set by a human engineer using input received by the computer, or the computer may be configured to suggest an appropriate shape based on the initial boundary conditions. Again, this can be reviewed as an initial seed start value, where an initial approximate estimate of what the best shape should be can be provided to the computer. For example, a common bean channel shape can be characterized and set by inner and outer edges, typically having different radii of curvature, and curved portions that connect these edges on both sides to form a closed channel.

  At block 2920, with the initial parameters and objectives set, the computer can immediately perform one or more optimization simulations for at least a subset of the heat exchanger shapes. In some cases, this involves performing a combined computational fluid dynamics and finite element analysis (CFD / FEA) simulation. To further set the boundary conditions and determine the heat load of the fluid, the computer can simulate either a representative subset or the overall heat exchanger geometry.

  At block 2925, the computer may then perform an optimization simulation on the slices of the decomposed heat exchanger shape. The entire shape may be first decomposed into slices by a computer running a simulation. These slices can represent a set of layers produced by additive manufacturing. For example, the slice can be the horizontal layer of the heat exchanger shown in either FIG. 18A or 18B. The computer can then take advantage of the macro boundary conditions from the previous step of block 2920 to perform geometric optimization of the internal channels and / or the wall structure in which they reside. In other words, the optimization technique can be separated into smaller parts of the shape of the heat exchanger. According to some embodiments, a combined CFD / FEA simulation may be performed for each slice.

  For example, in the case of a converging diffusion nozzle (see, eg, FIG. 16), this is represented by changes to the inner and outer diameters of the various slicing rings. It is important to optimize each slicing given that the thermostructural properties of the optimized beans vary with wall thickness and bean spacing. In addition, since the layer-by-layer method follows the fluid trajectory, it can take into account the heating of the coolant (the reduced thermal conductivity over distance).

  In the process of improving the channel shape and overall shape, the computer can create structures that change the cross-sectional area of the coolant channel at various locations. For example, in areas where the need for cooling properties is low but where there is a high need for uniform mass flow, or areas that feed into other more uniform shapes, the heat exchanger will have a cross-sectional area that is oval from the bean shape. It can have channels that gradually change in shape.

  Furthermore, the pitch angle of the coolant channel can be changed in consideration of boundary conditions. For example, as shown in FIG. 22, different portions of a single heat exchanger component have parallel channels that change their pitch angle flowing upward based on different cooling needs at different locations. When the pitch angle is made less steep (more horizontal), the surface area due to the aggregate coolant channel increases, thereby increasing the heat transfer rate.

During the simulation, the computer simulates the shape multiple times, each time a small change to the shape is made by the computer or with the assistance of a human operator to try to meet the set performance criteria. The simulation is then run again to see if the change was valid. The process repeats until the criteria are met. At block 2930, the computer can determine if there is convergence and the optimization goal has been met. Otherwise, the process can be repeated starting at block 2920. Convergence is achieved when the change in shape and channel shape stops after simulation is performed and adjustments are made. The computer can iteratively optimize each slice until one or more of the following optimization goals are met:
Conformity with the specified coefficient of safety standards;
Low stress concentration between channels;
Minimal divergence of the thermal gradient along the inner wall representing thermal stress; and symmetrical channel given symmetric flow and thermal conditions.

  At block 2935, the resulting heat exchanger is then analyzed, assuming that optimization goals have been achieved and structural convergence has been achieved. Analysis is performed to verify that performance criteria are met and operating conditions are set by testing or coupled system simulation. This helps to ensure that the resulting cross-section is smoothly assembled and that all components as well as the overall shape can be manufactured based on the unique resolution of the additive manufacturing device. In some cases, if this analysis reveals defects, simulation optimization is repeated as necessary.

  Embodiments of the present disclosure also include exemplary techniques for making any and all of the various components of the structural heat exchanger embodiments as described herein. Further, embodiments include any and all software or other computer readable media used to program a machine to create the components, and embodiments are not so limited.

  With reference to FIG. 30, a block diagram reads instructions 3024 from a machine-readable medium 3022 (eg, a non-transitory machine-readable medium, a machine-readable storage medium, a computer-readable storage medium, or any suitable combination thereof), and FIG. 9 illustrates components of a machine 3000 according to some exemplary embodiments that may perform, in whole or in part, any one or more of the methodologies discussed herein. In particular, FIG. 30 illustrates machine 3000 in the form of a computer system (eg, a computer) and any or more of the methodologies discussed herein may be wholly or partially machine 3000. Instructions 3024 (eg, software, programs, applications, applets, apps, or other executable code) may be executed therein.

  In alternative embodiments, the machine 3000 can operate as a stand-alone device or can be connected (eg, networked) to other machines. In a networked deployment, machine 3000 may operate at the capacity of a server machine or client machine in a server-client network environment or as a peer machine in a distributed (eg, peer-to-peer) network environment. The machine 3000 may include hardware, software, or a combination thereof, for example, server computer, client computer, personal computer (PC), tablet computer, laptop computer, netbook, mobile phone, smartphone, set top. A box (STB), personal digital assistant (PDA), web machine, network router, network switch, network bridge, or any instruction 3024 that specifies an operation to be performed on the machine, either sequentially or otherwise Or any other machine. Further, although only a single machine 3000 is shown, the term “machine” may also execute instructions 3024 individually or jointly to implement any one or more of the methodologies discussed herein. It should be construed to include any set of machines that perform all or part of it.

  The machine 3000 includes a processor 3002 (eg, a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a radio frequency integrated circuit (RFIC) or the like. Any combination), main memory 3004, and static memory 3006, which are configured to communicate with each other via bus 3008. The processor 3002 may be temporarily suspended by some or all of the instructions 3024 such that the processor 3002 may be configured to perform, in whole or in part, any one or more of the methodologies described herein. Or a microcircuit that can be configured permanently or permanently. For example, the set of one or more microcircuits of the processor 3002 may be configurable to execute one or more modules (eg, software modules) described herein.

  The machine 3000 may be a video display 3010 (eg, a plasma display panel (PDP), a light emitting diode (LED) display, a liquid crystal display (LCD), a projector, a cathode ray tube (CRT), or other capable of displaying graphics or video. Or any other display). The machine 3000 also includes an alphanumeric input device 3012 (eg, a keyboard or keypad), a cursor control device 3014 (eg, a mouse, touchpad, trackball, joystick, motion sensor, eye tracking device, or other pointing device), Storage device 3016, signal generator 3018 (eg, sound card, amplifier, speaker, headphone jack, or any suitable combination thereof) and network interface device 3020 may be included.

  The storage device 3016 stores machine readable media 3022 that stores instructions 3024 that perform any one or more of the methodologies or functions described herein, including, for example, any of the descriptions of FIGS. (Eg, a tangible non-transitory machine-readable storage medium). Instruction 3024 may also reside in main memory 3004, processor 3002 (eg, in the processor's cache memory), or both, completely or at least partially before or during execution by machine 3000. it can. Instruction 3024 may also reside in static memory 3006.

  Accordingly, main memory 3004 and processor 3002 can be viewed as machine-readable media 3022 (eg, a tangible non-transitory machine-readable medium). The instructions 3024 can be sent or received via the network 3026 via the network interface device 3020. For example, the network interface device 3020 can communicate the instructions 3024 using any one or more transfer protocols (eg, HTTP). Machine 3000 may also represent examples of means for performing any of the functions described herein, including the processes described in FIGS.

  In some exemplary embodiments, machine 3000 may be a portable computing device such as a smartphone or tablet computer that includes one or more additional input elements (eg, sensors or gauges) (not shown). Can have. Examples of such input elements include image input elements (eg, one or more cameras), audio input elements (eg, microphones), direction input elements (eg, compass), position input elements (eg, GPS receivers) ), An orientation element (eg, a gyroscope), a motion detection element (eg, one or more accelerometers), an altitude detection element (eg, an altimeter), and a gas detection element (eg, a gas sensor). Input collected by any one or more of these input elements may be accessible and usable by any of the modules described herein.

  As used herein, the term “memory” refers to a machine-readable medium 3022 that can store data temporarily or permanently, including but not limited to random access memory (RAM), It may be construed to include read only memory (ROM), buffer memory, flash memory, and cache memory. Although the machine-readable medium 3022 is shown as being a single medium in the exemplary embodiment, the term “machine-readable medium” refers to a single medium or multiple media that can store the instructions 3024 (eg, Centralized or distributed database 115, or associated cache and server). The term “machine-readable medium” shall also be construed to include any medium or combination of multiple media capable of storing instructions 3024 for execution by machine 3000, such that Instruction 3024 may be executed by one or more processors (eg, processor 3002) of machine 3000 to cause machine 3000 to execute any one or more of the methodologies described herein, in whole or Let it execute partially. Thus, a “machine-readable medium” refers to a single storage device or device as well as a storage network that includes a cloud-based storage system or multiple storage devices or devices. Thus, the term “machine-readable medium” includes, but is not limited to, one or more tangible (eg, non-transitory) forms of solid-state memory, optical media, magnetic media, or any combination thereof. It shall be interpreted to include a data repository.

  Further, the machine readable medium 3022 is non-transitory in that it does not embody a propagated signal. However, labeling a tangible machine-readable medium 3022 as “non-transitory” should not be construed to mean that the medium cannot be moved, and the medium is from one physical location to another. It should be interpreted as movable. Further, since machine-readable medium 3022 is tangible, the medium can be considered a machine-readable device.

  Throughout this specification, multiple instances may implement a component, operation, or structure that is described as a single instance. Although individual operations of one or more methods are illustrated and described as separate operations, one or more of the individual operations may be performed simultaneously and the operations need to be performed in the order shown. Absent. Structures and functions presented as separate components in the examples may be implemented as a combined structure or component. Similarly, structures and functions presented as a single component may be implemented as separate components. These and other variations, modifications, additions and improvements are included within the scope of the subject matter herein.

  Particular embodiments are described herein as including logic or several components, modules or mechanisms. A module may comprise a software module (eg, code stored on machine-readable medium 3022 or a transmission medium or otherwise embodied), a hardware module, or any suitable combination thereof. A “hardware module” is a tangible (eg, non-transitory) unit that can perform a specific operation and can be configured or arranged in a specific physical manner. In various exemplary embodiments, one or more computer systems (eg, stand-alone computer system, client computer system, or server computer system), or one or more hardware modules (eg, processor 3002 or computer system) of the computer system. The group of processors 3002) may be configured by software (eg, an application or application portion) as a hardware module that operates to perform a particular operation as described herein.

  In some embodiments, the hardware module may be implemented mechanically, electronically, or any suitable combination thereof. For example, a hardware module may include dedicated circuitry or logic that is permanently configured to perform a particular operation. For example, the hardware module can be a dedicated processor such as a field programmable gate array (FPGA) or ASIC. A hardware module may also include programmable logic or circuitry that is temporarily configured by software to perform a particular operation. For example, the hardware module may include software included within a general purpose processor 3002 or other programmable processor 3002. The decision to implement a hardware module mechanically, in a dedicated permanently configured circuit, or in a temporarily configured circuit (eg, configured by software) is a cost and time consideration It will be appreciated that can be driven by.

  A hardware module can provide information to other hardware modules or receive information from other hardware modules. Accordingly, the described hardware modules can be considered to be communicatively coupled. If multiple hardware modules are present at the same time, communication may be achieved between two or more hardware modules or via signal transmission between them (eg, via appropriate circuitry and bus 3008). In embodiments where multiple hardware modules are configured or instantiated at different times, communication between such hardware modules is through, for example, storage and retrieval of information in a memory structure accessed by the multiple hardware modules. Can be achieved. For example, one hardware module can perform an operation and store the output of that operation in a memory device to which it is communicatively coupled. Thereafter, additional hardware modules can later access the memory device to retrieve and process the stored output. A hardware module may also initiate communication with an input device or output device and may operate on a resource (eg, a collection of information).

  The various operations of the exemplary methods described herein are one or more processors configured temporarily (eg, by software) or permanently configured to perform related operations. 3002 can be performed at least in part. Such a processor 3002, whether configured temporarily or permanently, may constitute a processor execution module that operates to perform one or more operations or functions described herein. . As used herein, a “processor execution module” refers to a hardware module that is executed using one or more processors 3002.

  Similarly, the methods described herein may be performed at least in part by a processor, and processor 3002 is an example of hardware. For example, at least some of the method operations may be performed by one or more processors 3002 or processor execution modules. As used herein, “processor execution module” refers to a hardware module whose hardware includes one or more processors 3002. Further, the one or more processors 3002 may also operate to support the performance of related operations in a “cloud computing” environment or as “software as a service” (SaaS). For example, at least some of the operations may be performed by a group of computers (as an example of a machine 3000 that includes a processor 3002), and these operations may be performed over a network 3026 (eg, the Internet) and one or more suitable Accessible via an interface (eg, API).

  The performance of a particular operation may not only exist within a single machine 3000, but may be distributed among one or more processors 3002 deployed across multiple machines 3000. In some exemplary embodiments, one or more processors 3002 or processor execution modules may be located in a single geographic location (eg, in a home environment, office environment, or server farm). In other exemplary embodiments, one or more processors 3002 or processor execution modules may be distributed across several geographic locations.

  Unless otherwise stated, considerations in this specification that use words such as “process”, “calculate”, “calculate”, “determine”, “present”, “display” or the like Is one or more memories (eg, volatile memory, non-volatile memory, or any suitable combination thereof), registers, or other mechanical configuration that receives, stores, communicates, or displays information May refer to the operation or process of a machine 3000 (eg, a computer) that manipulates or transforms data represented as physical (eg, electronic, magnetic, or optical) quantities within an element. Further, unless otherwise specified, the term “a” or “an” is used herein to include one or more examples, as is common in patent documents. Finally, as used herein, the conjunction “or” refers to a non-exclusive “or” unless stated otherwise.

  This disclosure is illustrative and not restrictive. Further modifications will be apparent to those skilled in the art in light of this disclosure and are intended to fall within the scope of the appended claims.

Claims (20)

A wall that at least partially surrounds an area containing a large amount of heat relative to the surrounding volume;
A plurality of coolant channels, each defined by an open channel space in the wall and configured to allow fluid to flow through the wall;
Including a housing comprising,
The housing is made using additive manufacturing,
Heat exchanger.   The heat exchanger of claim 1, wherein each of the plurality of coolant channels has at least a portion of a bean-shaped cross-sectional area.   The heat exchanger of claim 1, wherein each of the plurality of coolant channels has at least a portion of a trapezoidal shaped cross-sectional area having rounded corners.   Each of the plurality of coolant channels has at least a portion of a cross-sectional area having a shape with parallel concave curves, and one of the concave curves is closest to the inner wall side closest to the high heat quantity region 2. The heat exchanger according to claim 1, wherein the second concave curve is located at a position closest to the outer wall side farthest from the high heat quantity region.   2. Each of the plurality of coolant channels has at least a portion of a cross-sectional area that is defined by satisfying a plurality of boundary conditions that define one or more functional or structural properties of the wall. The heat exchanger as described in. The plurality of boundary conditions are
At least one thermal condition that the wall must satisfy;
At least one structural condition that the wall must satisfy;
The heat exchanger of claim 5, comprising: at least one material property for the wall that the wall must satisfy; and at least one material property of the coolant channel that the plurality of coolant channels must satisfy. . The plurality of boundary conditions is a first plurality of boundary conditions applied to a first position of the coolant channel;
Each of the plurality of coolant channels has at least a part of a cross-sectional area of a second shape defined by satisfying a second plurality of boundary conditions different from the first plurality of boundary conditions at a second position. Have
The heat exchanger according to claim 5.   The heat exchanger of claim 1, wherein pitch angles of the plurality of coolant channels vary at different locations within the wall.   At least one of the plurality of coolant channels includes a first cross-sectional area formed in a first shape at a first position, and a second cross-sectional area formed in a second shape is a second. The heat exchanger according to claim 1, which is included in the position of   The heat exchanger according to claim 9, wherein the first shape is a bean shape and the second shape is an ellipse.   The heat exchanger of claim 1 wherein the size of the cross-sectional area of the plurality of coolant channels varies at different locations within the wall.   The heat exchanger of claim 1, wherein the wall is molded as a cylinder.   The heat exchanger of claim 1, wherein the wall includes a flat plate that houses at least a portion of the plurality of coolant channels.   The heat exchanger of claim 1, wherein the housing is made as a single part using additive manufacturing. A region that generates thermal energy; and
A housing surrounding the region,
A wall at least partially surrounding the region containing a large amount of heat relative to a surrounding quantity, and an open channel space in the wall, respectively, to allow fluid to flow in the wall Comprising a plurality of configured coolant channels;
A housing made as a single part using additive manufacturing,
A heat exchanger comprising:
With an engine.   The engine of claim 15, wherein each of the plurality of coolant channels has at least a portion of a bean-shaped cross-sectional area.   The engine of claim 15, wherein each of the plurality of coolant channels has at least a portion of a trapezoidal shaped cross-sectional area having rounded corners.   Each of the plurality of coolant channels has at least a portion of a cross-sectional area having a shape with parallel concave curves, and one of the concave curves is closest to the inner wall side closest to the high heat quantity region The engine according to claim 15, wherein the second concave curve is at a position closest to an outer wall side farthest from the high heat quantity region.   16. Each of the plurality of coolant channels has at least a portion of a cross-sectional region that is shaped by satisfying a plurality of boundary conditions that define one or more functional or structural properties of the wall. Engine described in. The plurality of boundary conditions are
At least one thermal condition that the wall must satisfy;
At least one structural condition that the wall must satisfy;
The engine of claim 15, comprising: at least one material property for the wall that the wall must satisfy; and at least one material property of the coolant channel that the plurality of coolant channels must satisfy.

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