WO2019243662A1

WO2019243662A1 - Mechanical interface

Info

Publication number: WO2019243662A1
Application number: PCT/FI2019/050452
Authority: WO
Inventors: Petteri Kokkonen; Aku KARVINEN; Lars KJÄLDMAN; Satu TUURNA; Hannu Martikainen; Mikko Savolainen; Juha Virtanen; Kimmo RUUSUVUORI; Satu ILVONEN; Erin KOMI
Original assignee: Teknologian Tutkimuskeskus Vtt Oy
Priority date: 2018-06-21
Filing date: 2019-06-12
Publication date: 2019-12-26
Also published as: FI20185568A1

Abstract

According to an example aspect of the present invention, there is provided a mechanical interface (10) comprising a first periodic substructure (21) and a second periodic substructure (22) at a distance from the first substructure (21) for providing a volume for a medium, wherein the first substructure (21) and the second substructure (22) are configured to be movable in respect to and in physical contact with each other for mechanical cleaning of deposits of the medium (30) through agitation.

Description

MECHANICAL INTERFACE

FIELD

[0001] The invention relates to a mechanical interface and in particular to a mechanical interface which can be cleaned during operation. BACKGROUND

[0002] Mechanical interfaces are generally used in devices of process industry. The mechanical interfaces may be adapted for example, in heat exchangers, devices of chemical industry, vibration isolators, or ionizing filters. During operation, deposits and other dirt will form on a surface of the mechanical interface. Fouling and build-up of deposit and dirt on the surfaces decrease operation efficiency of the mechanical interface. It may for example, reduce heat transfer of a heat exchanger.

[0003] US20140014493 discloses mass transfer packing with a minimal surface or a triply periodic minimal surface which enables significantly improved performance for separation and mixing applications particularly with respect to distillation, liquid-liquid contacting, and heat exchange applications. A minimal surface is one that locally minimizes its area and this is equivalent to having a mean curvature of zero.

[0004] Therefore, in order to maintain efficient operation, it is necessary periodically clean the surfaces. Cleaning of the surfaces may require disassembling of the mechanical interface. Moreover, it may cause interruptions in the operation of a device, because the device has usually to shut down during the cleaning. Thus, there is need for improve cleaning of the mechanical interface.

SUMMARY OF THE INVENTION

[0005] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims. [0006] According to a first aspect of the present invention, there is provided a mechanical interface comprising a first periodic substructure and a second periodic substructure at a distance from the first substructure for providing a volume for a medium, wherein the first substructure and the second substructure are configured to be movable in respect to and in physical contact with each other for mechanical cleaning of deposits of the medium through agitation.

[0007] According to a second aspect of the present invention, there is provided a method for cleaning a mechanical interface, the method comprising moving a first periodic substructure in respect to and in physical contact with a second periodic substructure so as to create agitation for the release of build-up on either or both substructure(s).

[000S] The present invention provides several advantages. It provides the mechanical interface, which can be cleaned during the operation. The invention decreases need for the shut downs and provides more efficient operation of the mechanical interface, for example the heat exchanger. In addition, it may decrease maintenance costs, because the cleaning may be conducted automatically and during the operation. In addition, the self-cleaning property may decrease need for replacing the mechanical interface. Moreover, the mechanical interface of the present invention has large surface area and induces turbulence for effective heat transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIGURE 1 illustrates substructures of a mechanical interface in central position in normal operation in accordance with at least some embodiments of the present invention;

[0010] FIGURE 2 illustrates a side view of substructures of a mechanical interface in central position in normal operation in accordance with at least some embodiments of the present invention;

[0011] FIGURE 3 illustrates substructures of a mechanical interface in central position in normal operation in accordance with at least some embodiments of the present invention; [0012] FIGURE 4 illustrates a side view of substructures of a mechanical interface in central position in normal operation in accordance with at least some embodiments of the present invention;

[0013] FIGURE 5 illustrates a single periodic minimal surface structure in accordance with at least some embodiments of the present invention; [0014] FIGURE 6 illustrates two periodic minimal surface structures built within each other in accordance with at least some embodiments of the present invention;

[0015] FIGURE 7 illustrates three pipe like substructures built within each other in accordance with at least some embodiments of the present invention; [0016] FIGURE 8 illustrates three pipe like substructures built within each other in accordance with at least some embodiments of the present invention;

[0017] FIGURE 9 illustrates an actuator with at least some embodiments of the present invention;

[0018] FIGURE 10 illustrates starting position of cleaning bottom surfaces of transversal pipes of a mechanical interface in accordance with at least some embodiments of the present invention;

[0019] FIGURE 11 illustrates intermediate position of cleaning bottom surfaces of transversal of a mechanical interface pipes in accordance with at least some embodiments of the present invention; [0020] FIGURE 12 illustrates end position of cleaning bottom surfaces of transversal pipes of a mechanical interface in accordance with at least some embodiments of the present invention;

[0021] FIGURE 13 illustrates intermediate position of cleaning two surfaces of vertical pipes of a mechanical interface in accordance with at least some embodiments of the present invention;

[0022] FIGURE 14 illustrates a side view of starting position of cleaning bottom surfaces of transversal pipes of a mechanical interface in accordance with at least some embodiments of the present invention;

[0023] FIGURE 15 illustrates a side view of intermediate position of cleaning bottom surfaces of transversal of a mechanical interface pipes in accordance with at least some embodiments of the present invention;

[0024] FIGURE 16 illustrates a side view of end position of cleaning bottom surfaces of transversal pipes of a mechanical interface in accordance with at least some embodiments of the present invention; [0025] FIGURE 17 illustrates a side view of intermediate position of cleaning two surfaces of vertical pipes of a mechanical interface in accordance with at least some embodiments of the present invention; and

[0026] FIGURE 18 illustrates cleaning of pipe like substructures built within each other in accordance with at least some embodiments of the present invention.

EMBODIMENTS

[0027] In the present context, the term“fluid” refers to a substance that continually deforms (flows) under an applied shear stress. The term includes but is not limited to gas and liquid.

[0028] In the present context, the term“substructure” refers to interface component or counterpart of a mechanical interface.

[0029] In the present context, the term“conductor” refers to a hollow tube, pipe or conduit. In addition, the term includes a solid structure. The conductor can conduct heat and/or convey a fluid medium.

[0030] Mechanical interfaces are generally used in devices of process industry. In order to maintain efficient operation, it is necessary periodically clean the mechanical interface. Cleaning of the mechanical interface cause interruptions in the operation of the device, because the device has to shut down during the cleaning. The invention discloses a mechanical interface which can be cleaned during the operation.

[0031] According to a first aspect of the present invention, there is provided a mechanical interface 10, which comprises a first periodic substructure 21 and a second periodic substructure 22 at a distance from the first substructure 21 for providing a volume for a medium 30. The first substructure and the second substructure are configured to be movable in respect to and in physical contact with each other for mechanical cleaning of deposits of the medium through agitation. Regions, parts or whole first and second substructure may be configured to become in physical contact with one another to create agitation for the release of build-up on either or both substructure(s). The cleaning can be carried out during the operation of the mechanical interface.

[0032] Structure of the mechanical interface 10 can be simulated and optimized to achieve preferred properties. Suitable material distribution (e.g. wall thickness of the substructures) by which surface pressure is preferably at all surfaces, structure is dense and bears pressure load, and is feasible for flow and heat transfer, can be selected on the basis of the application. In addition, inner shape of the substructures can be selected on the basis of the application. It can be shaped to achieve preferably properties and constant surface pressure to the surfaces to be cleaned. FIGURES 1-6 illustrates examples of the structures in accordance with at least some embodiments of the present invention.

[0033] The mechanical interface 10 may comprise two substructures, in between which the fluid is flowing. On the other hand, the fluid may be flowing in either or both of the substructures. The mechanical interface may be designed to have large surface area and to induce turbulence for effective heat transfer. In turbulence, fluid does not flow in smooth layers but is agitated. Heat transfer occurs at the channel wall of the substructure. Due to the agitation, turbulent flow does not develop an insulating blanket, which restricts heat transfer, around the channel wall. Thus, heat is transferred very rapidly. In turbulent flow, fluid particles exhibit also transverse motion due to turbulence, which enhances heat transfer.

[0034] According to some embodiments, the contacting surfaces of the first periodic substructure 21 and the second periodic substructure 22 are substantially conformal. The substructures may be mathematically conformal and conformal within normal manufacturing tolerances. Alternatively, the substructures may be seen as conformal if, upon agitation, the contacting surfaces engage enough to discard 50 % or more of the loose buildup on the surfaces. Operation of the device, such as heat exchange of a heat exchanger, may be more efficient if at least some of the buildup is discarded upon agitation. One of the substructures may be convex while the other is concave. On the other hand, the both substructures may be planar or gyroid. A gyroid is an infinitely connected triply periodic minimal surface. The gyroid contains neither straight lines nor planar symmetries. The gyroid separates space into two oppositely congruent labyrinths of passages. The gyroid has large surface area. Thus, efficient heat transfer is achieved with small total volume, because surface area per volume is high.

[0035] According to some embodiments, the first substructure 21 and the second substructure 22 are overlapping. The substructures are movable in line contact with each other. The substructures may not be substantially mutually conformal. In this case, the substructures may be round pipe like structures as illustrates in FIGURE 7-8. Then, the cleaning may be carried out for example, by moving other substructure to touch or around another substructure while the substructures are in physical contact as disclosed below in more detail. Thus, the substructures may be cleaned for example, from three sides.

[0036] According to some embodiments, the first substructure 21 and the second substructure 22 may be a conductor. The substructure may be a solid structure that conducts heat. On the other hand, it may have channels for carrying the fluid medium.

[0037] Either or both of the first substructure 21 and the second substructure 22 may be hollow for conveying the fluid medium 30 therein. The substructure may have a channel or a space within for carrying the fluid medium. The fluid medium may be for example, liquid or gas.

[0038] According to some embodiments, the first substructure 21 and the second substructure 22 may be at least partly intersectioned, as illustrated in FIGURES 1-6. The first substructure and the second substructure may be at least partly within each other. In addition, the structures may be around each other. There is a space between the substructures for providing a volume for the medium 30.

[0039] According to some embodiments, the first substructure 21 and the second substructure 22 may share a similar shape on regions or parts that are configured to become in physical agitating contact with one another. For example, the both substructures may be planar, pipe like or gyroid. It is preferred that the substructures share a similar shape in the heat exchanger application for higher amount of contacting surfaces.

[0040] According to some embodiments, the first substructure 21 and the second substructure 22 may exhibit a grid shape. The grid is a structure made up of a series of intersecting straight (vertical, horizontal, and angular) or curved parts. The substructures may comprise, for example, rectangular tubes which are connected to each other and form a three dimensional (3D) continuous grid structure as illustrated in FIGURES 1-4. The fluid may be flowing between the substructures, or either or both of the substructures may be hollow for conveying a fluid medium therein.

[0041] The first substructure and the second substructure may be shaped on the basis of the application. Cleaning can be directed to preferred surfaces by the shape of the substructures. For example, the substructures may be shaped in that way, that only higher areas of the substructures can be made in the physical contact and can be cleaned by the cleaning process. Thus, the substructures can be shaped to achieve for example, preferred flow of fluids, heat exchange, efficiency, and price. FIGURE 1-2 presents the position of the substructures when a heat exchanger is in use. Then, the fluid medium is able to flow around the pipes and the heat is normally transferred.

[0042] As illustrated in FIGURES 5-6, the first substructure 21 and the second substructure 22 may exhibit a periodic minimal surface according to some embodiments.

The periodic minimal surface provides 3D form. The periodic minimal surface may be for example, gyroid. Either or both of the periodic minimal surfaces may be hollow for conveying a fluid medium 30 therein or the fluid may be flowing between the periodic minimal surfaces. The periodic minimal surface has large surface area, which provides efficient heat transfer.

[0043] According to some embodiments, the mechanical interface may be manufactured by additive manufacturing (AMF). Additive manufacturing builds a three- dimensional object from computer-aided design (CAD) model or AMF file, usually by successively adding material layer by layer. It may produce complex, precisely designed shapes. It may be used for forming products from different kind of materials for example, metal.

[0044] According to some embodiments, the mechanical interface may be manufactured by welding. The substructures may be manufactured by joining tube like parts and connection nodes manufactured by casting or forming. Welding may be carried out by robots, for example, by two robots. Then, other of the robots holds a part of the structure and puts it in the right place and another of the robots welds the part to the structure. This process is continued until welding of the structure is finished.

[0045] According to some embodiments, the first substructure 21 and the second substructure 22 may be manufactured by simultaneously. This may be possible with additive manufacturing and is preferably with at least partly intersectional structures. The simultaneous manufacturing enables of forming complex intersectional structures.

[0046] The first substructure 21 and the second substructure 22 are configured to be movable in respect to and in physical contact with each other. Thus, according to some embodiments, the mechanical interface 10 comprises an actuator 40, 41 for moving the substructures for mechanical cleaning of deposits. The actuator may also support the structure. The actuator may comprise a drive unit. On the other hand, moving of the substructures may be provided by hand by maintenance worker.

[0047] FIGURE 9 illustrates an actuator 40, 41 with at least some embodiments of the present invention. According to some embodiments, the actuator comprises two hollow conductors, for example tubes. Cross section of the tubes may be for example, circular or rectangular. One of the conductors is connected to the first substructure and other of the conductors is connected to the second substructure. Moreover, the conductors may be connected to bypass manifolds at other ends of tubes. The actuator enables controlled moving of the substructures and efficient cleaning of the surfaces of the substructures.

[0048] According to some embodiments, the actuator 40, 41 is connected to the first substructure 21 and the second substructure 22 via joints. The joints allow moving of the first substructure and the second substructure for cleaning the surfaces of the substructures. The joint may be for example, a telescopic tube, a bellow, or elastic joint. Moving in the horizontal direction of the plane may be provided for example, by the telescopic tubes, and in the vertical direction for example, by bellows.

[0049] According to some embodiments, the actuator 40, 41 can be used by a single controlling apparatus. The controlling apparatus comprises a user interface, such as a display and input means, such as one or more of a keyboard, a touch screen, a mouse, a gesture input device or other type input/output device, through which user control commands can be received to control the actuator manually. The actuator may be adapted to carry out at least part of the work steps automatically and/or periodically. The controlling apparatus may comprise a control unit comprising one or more processors which performs computer program code stored in memory which, when executed in the processor, provides control commands to the operating devices, such as for controlling the actuator and the drive unit. The control functionality can be programmable and/or at least partially implemented as a hardware solution. This may decrease maintenance costs, because the cleaning may be conducted automatically and during the operation.

[0050] The first substructure 21 and the second substructure 22 may be manufactured from material which exhibit high thermal conductivity and sufficient abrasion resistance. The substructures may be manufactured from metal, for example steel or aluminium. [0051] According to some embodiments, the mechanical interface is a heat exchanger. The heat exchanger may be used for example, in air conditioning, chemical plants and power stations. The present invention may be adapted to cleaning of the mechanical interface of a heat exchanger during operation. The invention decreases need for the shut downs and provides more efficient operation of the heat exchanger. However, the mechanical interface may also be adapted for example, in devices of chemical or process industry, a vibration isolator, an ionizing filter, or grinding starting materials.

[0052] A method for cleaning a mechanical interface 10 comprise moving the first periodic substructure 21 in respect to and in physical contact with the second periodic substructure 22 so as to create agitation for the release of build-up on either or both substructure(s) according to some embodiments. Surface pressure is provided between the mating substructures. The first substructure is moved in the direction of the surface of the second substructure. Cleaning may be provided by mechanical cleaning by abrasion, wherein the substructures move in physical contact with each other. Then, deposit and dirt is scuffed or rubbed away from the surfaces of the substructures. Deposit or dirt may act as abrasive between the surfaces and assist in cleaning.

[0053] Cleaning can be made more efficient by using chemicals or additives. For example, a detergent may be provided for more efficient cleaning. The detergent may be provided into the fluid flowing between the substructures before the cleaning of the substructures.

[0054] FIGURES 10-17 illustrates of moving grid like substructures in respect to and in physical contact with each other in accordance with at least some embodiments of the present invention. Horizontal parts of the grid like structure are referred as transversal pipes, and vertical parts of the pipes are referred as vertical pipes. A fluid medium 30 may be flowing between the grid like substructures, or either/both of the substructures may be hollow for conveying a fluid medium therein.

[0055] FIGURES 10 and 14 illustrate a starting position of cleaning the bottom surfaces of the transversal pipes when the first substructure 21 is moved horizontally to the direction of the arrow 50 from the central position (FIGURES 1 and 2) in respect to and in physical contact with the second substructure 22. FIGURES 11 and 15 presents an intermediate position of cleaning the bottom surfaces of the transversal pipes when the first substructure is moved further to the direction of the arrow 50 from the starting position. FIGURES 12 and 16 presents an end position of cleaning the bottom surfaces of the transversal pipes, when the first substructure is moved to the furthest position from the starting position wherein the transversal pipes are in contact.

[0056] Cleaning of the surfaces of the vertical pipes can be made respectively as described in the case of the transversal pipes. Then, the first substructure 21 is moved vertically to the direction of the arrow 60. FIGURES 13 and 17 presents an intermediate position of cleaning the two surfaces of the vertical pipes.

[0057] Above there is only disclosed embodiments, wherein two substructures, the first substructure and the second substructure, are used. However, more than two substructures can be provided. In addition, the substructures can be divided into several regions, sections or parts which can be used for different functions and can be cleaned at different times.

[0058] In the case of mutually non-conformal structures, for example, round pipe like structures, the cleaning may be carried out by moving one substructure to touch or around another substructure while the substructures are in physical contact as illustrated in FIGURE 18. At the first stage, the first substructure 71, the second substructure72, and the third substructure 73 are in the initial position. At the second and the third stage, the third substructure moves 73 in the contact with the second substructure 72, and the lower surface of the third substructure 73 cleans left surface of the second substructure 72. After that, the third substructure 73 moves back to the initial position as illustrated in fourth stage. At the fifth and sixth stage, the third substructure 73 moves in the contact with the second substructure 72, and the lower surface of the third substructure 73 cleans right surface of the second substructure 72. After that, the third substructure 73 moves again back to the initial position as illustrated in seventh stage. At the eighth and ninth stage, the first substructure moves 71 in the contact with the second substructure 72, and the upper surface of the first substructure 71 cleans right surface of the second substructure. After that, the first substructure 71 moves again back to the initial position as illustrated in tenth stage. At the eleventh and twelfth stage, the first substructure moves 71 in the contact with the second substructure 72, the upper surface of the first substructure 71 cleans left surface of the second substructure 72. Finally, the first substructure 71 moves again back to the initial position. The preceding cleaning process provides cleaning of the second substructure at all four sides and the three contact surfaces of the first substructure and the third substructure.

[0059] The present invention provides several advantages. It provides the mechanical interface, which can be cleaned during the operation. The invention decreases need for the shut downs and provides more efficient operation of the mechanical interface, for example the heat exchanger. In addition, it may decrease maintenance costs, because the cleaning may be conducted automatically and during the operation. In addition, the self-cleaning property may decrease need for replacing the mechanical interface. Moreover, the mechanical interface of the present invention has large surface area and induces turbulence for effective heat transfer.

[0060] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0061] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases“in one embodiment” or“in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

[0062] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention. [0063] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0064] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below. [0065] The verbs“to comprise” and“to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality.

INDUSTRIAL APPLICABILITY

[0066] At least some embodiments are feasible in mechanical interfaces.

ACRONYMS LIST

3D three dimensional

AMF additive manufacturing

CAD computer-aided design

REFERENCE SIGNS LIST

10-13 mechanical interface

21 first substructure

22 second substructure

30 medium 40-41 actuator

50 moving direction

60 moving direction

71 first substructure

72 second substructure

73 third substructure

CITATION LIST

Patent Literature US20140014493

Claims

1. A mechanical interface (10) comprising:

- a first periodic substructure (21) and

- a second periodic substructure (22) at a distance from the first substructure (21) for providing a volume for a medium (30),

wherein the first substructure (21) and the second substructure (22) are configured to be movable in respect to and in physical contact with each other for mechanical cleaning of deposits of the medium (30) through agitation.

2. The mechanical interface (10) of claim 1, wherein contacting surfaces of the first substructure (21) and the second substructure (22) are mutually conformal.

3. The mechanical interface (10) of claim 1, wherein the first substructure (21) and the second substructure (22) are overlapping.

4. The mechanical interface (10) of any one of the preceding claims, wherein the first substructure (21) and the second substructure (22) are conductors.

5. The mechanical interface (10) of any one of the preceding claims, wherein either or both of the first substructure (21) and the second substructure (22) is/are hollow for conveying a fluid medium therein.

6. The mechanical interface (10) of any one of the preceding claims, wherein the first substructure (21) and the second substructure (22) are at least partly intersectioned.

7. The mechanical interface (10) of any one of the preceding claims, wherein the first substructure (21) and the second substructure (22) share a similar shape on regions that are configured to become in physical agitating contact with one another.

8. The mechanical interface (10) of any one of the preceding claims, wherein the first substructure (21) and the second substructure (22) exhibit a grid shape.

9. The mechanical interface (10) of any one of the preceding claims 1 to 6, wherein the first substructure (21) and the second substructure (22) exhibit a periodic minimal surface.

10. The mechanical interface (10) of any one of the preceding claims, wherein the mechanical interface is manufactured by additive manufacturing.

11. The mechanical interface (10) of claim 1-9, wherein the mechanical interface is manufactured by welding.

12. The mechanical interface (10) of any one of the preceding claims, wherein the first substructure (21) and the second substructure (22) are manufactured simultaneously.

13. The mechanical interface (10) of any one of the preceding claims, wherein the mechanical interface is a heat exchanger.

14. The mechanical interface (10) of any one of the preceding claims, wherein the mechanical interface comprises an actuator (40, 41).

15. The mechanical interface (10) of any one of the preceding claims, wherein the actuator (40, 41) comprises two hollow conductors, one of the conductors being connected to the first substructure (21) and other of the conductors being connected to the second substructure (22).

16. The mechanical interface (10) of any one of the preceding claims, wherein the actuator (40, 41) is connected to the first substructure (21) and the second substructure (22) via joints, which allow moving of the first substructure (21) and the second substructure (22) in respect to the respective conductors for cleaning the surfaces of the first substructure (21) and the second substructure (22).

17. The mechanical interface (10) of any one of the preceding claims, wherein the actuator (40, 41) comprises or is adapted to be used by a single control device.

18. A method for cleaning a mechanical interface (10), the method comprising moving a first periodic substructure (21) and a second periodic substructure (22) in respect to and in physical contact with each other so as to create agitation for the release of build-up on either or both substructure(s).

19. The method of claim 18, wherein the mechanical interface (10) is a heat exchanger.