Continuous spiral baffle heat exchanger

Abstract

To more quickly and efficiently heat a working fluid.SOLUTION: A heater assembly includes a continuous series of perforated helical members 18 and a plurality of heating elements 16. The perforated helical members cooperate to define a geometric helicoid disposed about a longitudinal axis of the heater assembly. Each perforated helical member defines opposed edges and a predetermined pattern of perforations 30. The perforations extend through each perforated helical member parallel to the longitudinal axis. The heating elements extend through the perforations.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to heating devices, and more particularly to heat exchangers for heating fluids. [Background technology]

[0002] The statements in this section are merely intended to provide background information related to the present disclosure and may not constitute prior art.

[0003] A heat exchanger typically includes a tubular conduit and multiple heating elements disposed within the tubular conduit. A working fluid enters one longitudinal end of the tubular conduit and exits at the other longitudinal end. The working fluid is heated by the multiple heating elements as the working fluid flows within the tubular conduit. In a fluid-to-fluid heat exchanger, the multiple heating elements are tubes through which the heating fluid flows. Heat is transferred from the heating fluid to the working fluid through the walls of the tubes. In an electrical heat exchanger, the heating elements are electrical heating elements (e.g., resistive heating elements).

[0004] To heat the working fluid faster and more efficiently, typical heat exchangers increase their heat output by increasing the total heat exchange area or by increasing the heat flux of the heating element. However, typical methods of increasing the total heat exchange area can take up more space in the heat exchanger that might otherwise be used to contain the working fluid, and typical methods of increasing the heat flux of the heating element can be limited by the material and design of the heating element, as well as other application-specific requirements. Summary of the Invention

[0005] In one form, a heater assembly is provided that includes a continuous series of helical members and a plurality of heating elements, each helical member defining opposing edges and a predetermined pattern of perforations extending through each helical member parallel to a longitudinal axis of the heater assembly, the plurality of heating elements extending through the perforations (and in one form through all of the perforations) of the continuous series of helical members, the continuous series of helical members defining a geometric helix.

[0006] In another form, an electric heat exchanger includes a body defining a cavity, a heater assembly disposed within the cavity, and a proximal flange configured to secure the heater assembly to the body. The heater assembly defines a longitudinal axis and includes a continuous series of helical members and a plurality of heating elements. Each helical member defines opposing edges and a predetermined pattern of perforations extending parallel to the longitudinal axis through each helical member. The plurality of heating elements extend through the perforations of the continuous series of helical members. The continuous series of helical members defines a geometric helix.

[0007] In yet another form of electric heat exchanger, an apparatus provides a consistent linear temperature rise along a length of the electric heat exchanger, the apparatus including a continuous series of helical members, each helical member defining opposing edges and a predetermined pattern of perforations extending parallel to a longitudinal axis of the electric heat exchanger through each helical member, the continuous series of helical members defining a geometric helix, the plurality of perforations configured to receive a plurality of heating elements.

[0008] In one form, the heater assembly includes a continuous series of perforated helical members and a plurality of heating elements. The perforated helical members cooperate to define a geometric helix disposed about a longitudinal axis of the heater assembly. Each perforated helical member defines opposing edges and a predetermined pattern of a plurality of perforations. The plurality of perforations extend through each perforated helical member parallel to the longitudinal axis. The heating elements extend through the plurality of perforations.

[0009] According to another aspect, each heating element includes a first segment, a second segment, and a bend connecting the first and second segments. The first segment extends through a first set of perforations. The second segment extends through a second set of perforations. The second set of perforations is parallel to and offset from the first set of perforations.

[0010] According to another aspect, multiple heating elements are arranged in a concentric pattern.

[0011] According to yet another aspect, the heater assembly further includes a central support member, each of the perforated helical members defining a central opening, the central support member extending through the central openings.

[0012] According to another aspect, the heater assembly further includes a temperature sensor extending through an interior of the central support member, the temperature sensor including a probe exterior to the central support member.

[0013] According to another aspect, the heater assembly further includes a proximal flange configured to secure the heater assembly to the heat exchanger body. The flange defines a plurality of flange openings and a central groove. The plurality of flange openings are aligned with the plurality of perforations of the plurality of perforated helical members. The plurality of heating elements extend through the plurality of flange openings. The central support member is received in the central groove.

[0014] According to another aspect, the heater assembly further includes a fluid port opening providing fluid communication between an exterior of the central support member and an interior of the central support member adjacent the flange.

[0015] According to another aspect, the central support member includes at least one additional heater.

[0016] According to another aspect, the heater assembly further includes a non-perforated helical member disposed at a distal end of the continuous series of perforated helical members, the non-perforated helical member forming an extension of the geometric helix.

[0017] According to another aspect, each of the heating elements is secured to at least a portion of each of the bores through which the respective heating element passes.

[0018] According to another aspect, an opposing edge from one helical member overlaps an opposing edge from an adjacent helical member.

[0019] According to another aspect, an opposing edge from one helical member is spaced from an opposing edge from an adjacent helical member and connected thereto by a bridging member.

[0020] According to another aspect, the heater assembly further includes a plurality of rods extending parallel to the longitudinal axis, the circumference of each perforated helical member defining a plurality of grooves, the plurality of rods being at least partially disposed within a corresponding set of the plurality of grooves.

[0021] According to another aspect, a rod extends outwardly from the groove beyond the periphery of each perforated helical member, the heater assembly being configured to be received within a cylindrical cavity of the body, the rod being configured to provide sliding contact with a wall of the body defining the cylindrical cavity.

[0022] According to another aspect, the heater assembly further includes a shroud disposed about at least a portion of the perforated helical member and coupled to the rod.

[0023] According to another aspect, the rods do not extend outwardly beyond the periphery of each perforated helical member.

[0024] According to another aspect, the shroud is a heat shield configured to reflect radiant energy radially inward relative to the longitudinal axis.

[0025] According to another aspect, the shroud includes at least one skirt defining a plurality of deformable flaps extending radially outwardly relative to the longitudinal axis.

[0026] According to another aspect, the at least one skirt is disposed adjacent a proximal or distal end of the heater assembly.

[0027] According to another aspect, the at least one skirt includes a first skirt and a second skirt, the first skirt disposed at a proximal end of the heater assembly and the second skirt disposed at a distal end of the heater assembly.

[0028] According to another aspect, a continuous series of perforated helical members defines a variable pitch.

[0029] According to another aspect, the continuous series of perforated helical members has a longer pitch near the inlet end of the heater assembly than near the outlet end of the heater assembly.

[0030] According to another aspect, the heating element is an electrical resistance heating element.

[0031] According to another aspect, the electrical resistance heating element is one of the group of a tubular heater, a cartridge heater, or a multi-cell heater.

[0032] According to another aspect, the plurality of heating elements includes a first heating element and a second heating element, the first heating element having a different length than the second heating element.

[0033] According to another aspect, the heater assembly further includes an alignment plate coaxially disposed about the longitudinal axis, the alignment plate defining a plurality of plate openings that align with the perforations of the perforated helical member.

[0034] In another form, a heat exchanger includes a body, a heater assembly, and a proximal flange. The body defines a cylindrical cavity. The heater assembly defines a longitudinal direction. The heater assembly includes a continuous series of perforated helical members and a plurality of heating elements. The perforated helical members are disposed within the cylindrical cavity and define a geometric helix. Each perforated helical member defines opposing edges and a predetermined pattern of perforations extending parallel to the longitudinal axis through each perforated helical member. The heating elements extend through the perforations in the perforated helical members. The proximal flange secures the heater assembly to the body.

[0035] According to another aspect, the heat exchanger further includes a plurality of rods extending longitudinally parallel to the longitudinal axis, the periphery of each perforated helical member defining a plurality of grooves, the plurality of rods being partially disposed within a corresponding set of grooves and having a thickness extending radially outward from the periphery of the perforated helical member, the rods in sliding contact with an inner wall of the body defining a cylindrical cavity.

[0036] According to another aspect, the heat exchanger further includes a skirt including a resiliently deformable flap extending radially between the perforated helical member and an inner wall of the body defining the cylindrical cavity.

[0037] According to another aspect, the body includes an inlet at a proximal end of the cylindrical cavity and an outlet at a distal end of the cylindrical cavity. The heater assembly further includes a non-perforated helical member connected to the last of the continuous series of perforated helical members. The non-perforated helical member forms an extension of the geometric helix and begins along the geometric helix at or short of the outlet.

[0038] According to another aspect, the non-perforated helical member has a pitch equal to the diameter of the outlet.

[0039] In another form, a heater assembly includes a continuous perforated spiral baffle and a plurality of heating elements, the baffle defining a geometric spiral about a longitudinal axis, the perforated spiral baffle defining a predetermined pattern of perforations extending parallel to the longitudinal axis through the perforated spiral baffle, and the heating elements passing through the perforations.

[0040] According to another embodiment, the geometric spiral has a pitch that varies along the longitudinal axis.

[0041] According to another embodiment, the pitch is continuously variable.

[0042] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. [Brief description of the drawings]

[0043] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0044] [Figure 1] FIG. 1 is a perspective view of a heater assembly constructed in accordance with the teachings of the present disclosure.

[0045] [Diagram 2] FIG. 2 is a perspective view of a continuous series of helical members of the heater assembly of FIG. 1.

[0046] [Diagram 3] FIG. 3 is a perspective view of the helical member of FIG. 2.

[0047] [Figure 4] FIG. 4 is a front view of the helical member of FIG. 3.

[0048] [Diagram 5] 2 is a perspective view of a continuous series of helical members and a central support member of FIG. 1.

[0049] [Figure 6] FIG. 2 is a partial perspective view of the helical member and the heating element of FIG.

[0050] [Figure 7] FIG. 13 is a diagram showing the connection between the heating element and the helical member.

[0051] [Figure 8] FIG. 2 is a partial perspective view of the helical member and the heating element of FIG.

[0052] [Figure 9] FIG. 2 is a front view of a heating element attached to a helical member.

[0053] [Figure 10] 11A-11C are front views of heating elements attached to a helical member showing different arrangements of the heating elements.

[0054] [Figure 11] FIG. 2 is a partial perspective view of the heater assembly of FIG. 1 with the shroud removed to show the non-perforated helix and support rods.

[0055] [Figure 12] FIG. 2 is a partial perspective view of the heater assembly of FIG. 1 with the shroud and non-perforated spiral member removed;

[0056] [Figure 13] FIG. 2 is an enlarged view of part A in FIG.

[0057] [Figure 14] FIG. 2 is an enlarged view of part B in FIG.

[0058] [Figure 15] FIG. 2 is a perspective view of the proximal mounting flange of FIG. 1.

[0059] [Figure 16] 1 is a cutaway perspective view of an electric heat exchanger constructed in accordance with the teachings of the present disclosure;

[0060] [Figure 17] FIG. 17 is a cutaway front view of the electric heat exchanger of FIG. 16.

[0061] [Figure 18] FIG. 2 illustrates the temperature distribution along the heater assembly of FIG.

[0062] [Figure 19] 19 is a graph showing the surface temperature of the heating element versus distance from the proximal mounting flange for a conventional heat exchanger and a heat exchanger with the heater assembly of FIG. 18.

[0063] [Figure 20] FIG. 2 is a left perspective view of a heater assembly of a second configuration according to the teachings of the present disclosure, shown with an optional shroud installed;

[0064] [Figure 21] FIG. 21 is a right side perspective view of the heater assembly of FIG. 20 shown without the optional shroud.

[0065] [Figure 22] FIG. 21 is a perspective view of a portion of the shroud of FIG. 20.

[0066] [Figure 23] FIG. 21 is a perspective view of the distal end of the heater assembly of FIG. 20.

[0067] [Figure 24] FIG. 21 is a perspective view of the center tube and mounting flange of the heater assembly of FIG. 20.

[0068] [Diagram 25] FIG. 25 is an exploded perspective view of the center tube and mounting flange of FIG. 24.

[0069] [Figure 26] FIG. 21 is a perspective view of a heat exchanger according to the teachings of the present disclosure including the heater assembly of FIG.

[0070] [Figure 27] FIG. 27 is a cross-sectional view of the proximal end of the heat exchanger of FIG. 26.

[0071] [Figure 28] FIG. 27 is a cross-sectional view of the distal end of the heat exchanger of FIG. 26.

[0072] [Figure 29] FIG. 13 is a perspective view of a heater assembly of a third configuration in accordance with the teachings of the present disclosure, showing a linear heating element.

[0073] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0074] The following description is merely exemplary in nature and is in no way intended to limit the disclosure, application, or uses.

[0075] 1, a heater assembly 10 constructed in accordance with the teachings of the present disclosure is configured to be disposed inside a tubular body 82 or shell of a heat exchanger 80 (shown in FIGS. 16 and 17) to heat a working fluid flowing through the heat exchanger 80. The heater assembly 10 may be attached to the tubular body 82 of the heat exchanger 80 by a proximal end plate or mounting flange 12. The heater assembly 10 includes a flow directing device 14 and a plurality of heating elements 16 extending within and fixed relative to the flow directing device 14. The heater assembly 10 defines a proximal end 20 and a distal end 21 that define a longitudinal axis X of the heater assembly 10. The mounting flange 12 is disposed at the proximal end of the heater assembly 10. The plurality of heating elements 16 extend along the longitudinal axis X of the heater assembly 10.

[0076] As shown in FIG. 2, the flow directing device 14 includes a plurality of perforated helical members 18 or helical baffles that are connected in a linear arrangement along the longitudinal axis X of the heater assembly 10 to define a continuous geometric helix. The continuous geometric helix is ​​such that each perforated helical member 18 defines a surface that follows a helical path about the longitudinal axis X. Optionally, the flow directing device 14 further includes a helical end baffle or a non-perforated helical member 23 disposed adjacent the distal end 21 of the heater assembly 10 and connected to adjacent perforated helical members 18 to form an extension of the continuous geometric helix. The plurality of perforated helical members 18 and the non-perforated helical member 23 define a continuous helical flow directing channel 22 that directs the working fluid to generate a helical flow within the tubular body 82 of the heat exchanger 80 (FIGS. 16 and 17).

[0077] As shown in Figures 3 and 4, each of the perforated helical members 18 is in the form of a metal sheet bent to make one complete helical turn. Although not shown in the drawings, it is understood that the metal sheet may be bent to form only one helical turn or two or more helical turns. Each of the perforated helical members 18 defines opposing edges 26 and 28 and a predetermined pattern of perforations 30 that extend through each perforated helical member 18. The opposing edges 26 or 28 of one perforated helical member 18 may be welded to the opposing edges 28 or 26 of an adjacent perforated helical member 18. In one form, as shown in Figure 8, the opposing edges 26 or 28 of one perforated helical member 18 may overlap the opposing edges 28 or 26 from an adjacent perforated helical member 18. In the example shown in Figure 8, this overlap is equal to approximately 1.01 turns, providing additional coverage. 6, the opposing edges 26 or 28 of one perforated helical member 18 can be adjacent and the opposing edges 28 or 26 of adjacent perforated helical members 18 can be welded together such that the surfaces of adjacent perforated helical members 18 form a continuous surface. In another example, the opposing edges 26 or 28 of one perforated helical member 18, not specifically shown, can be joined to the opposing edges 28 or 26 of adjacent perforated helical members 18 by a bridge member (not shown). The bridge member can be helical in shape or can be another shape, such as extending a short distance in a circular fashion.

[0078] Thus, the perforated helical members 18 are connected along the longitudinal axis X of the heater assembly 10 to form a linear array (continuous series) of perforated helical members 18. The perforations 30 of the plurality of perforated helical members 18 are aligned along a direction parallel to the longitudinal axis X of the heater assembly 10 or perpendicular to the radial direction, and thus at an angle to each face of the perforated helical member 18. A non-perforated helical member 23 is connected to the distal end of the continuous series of perforated helical members 18. The non-perforated helical member 23 is structurally similar to the perforated helical member 18, but is not perforated.

[0079] Each of the perforated helical members 18 and the non-perforated helical members 23 has an inner peripheral edge 32 that is contoured in such a manner that when viewed in a direction parallel to the longitudinal axis X of the heater assembly 10, the inner peripheral edge 32 defines a circular opening coaxial with the longitudinal axis X. In the example provided, the perforated helical members 18 each define a plurality of peripheral grooves 36 along the outer periphery of the perforated helical member 18. Similarly, the non-perforated helical member 23 defines a plurality of peripheral grooves 36 along its outer periphery. The peripheral grooves 36 of the plurality of perforated helical members 18 (and non-perforated helical members 23) are also aligned along a direction parallel to the longitudinal axis X of the heater assembly 10.

[0080] The helical pitch, the outer diameter of the perforated helical member 18, the diameter of the central opening 34 of the perforated helical member 18, and the thickness of the perforated helical member 18 may be appropriately selected depending on the desired flow rate and / or the desired volumetric flow rate of the working fluid. The number of heating elements 16 and the number of perforations 30 in the perforated helical member 18 may be appropriately selected depending on the desired heat output and thermal efficiency.

[0081] As shown in FIG. 5, the heater assembly 10 further includes a central support member 40 that extends through a central opening 34 of the perforated and non-perforated helical members 18 and 23 to connect the plurality of perforated and non-perforated helical members 18 and 23 and provide structural support for the heater assembly 10. The central support member 40 and the non-perforated helical members 23 may be configured to further heat the working fluid. In one form, the central support member 40 is an additional heating element (e.g., an electric heating element). When also used as an additional heating element, the central support member 40 may include one or more electrical resistance heating elements, such as cartridge heaters, tubular heaters, or any conventional heater having an elongated configuration, to provide both heating and structural support.

[0082] As shown in Figures 6 and 7, the heating elements 16 are inserted through the perforations 30. Although only a pair of heating elements 16 are shown in Figures 6 and 7 for clarity of illustration, when fully assembled, all of the perforations 30 receive the heating elements 16 and fluid travels along the helical flow directing channel 22 without passing through the perforations 30. In the example provided, the heating elements 16 each have a tongue-like configuration and include a pair of straight portions 42 that extend through the perforations 30 of the perforated helical member 18 and a bent portion 44 connecting the pair of straight portions 42. The heating elements 16 may be any suitable type of heating element, such as an electrical resistance heating element.

[0083] For example, electric tubular heaters, electric cartridge heaters, or multi-cell heaters can be used. When the heating elements 16 are electric heating elements, they can include resistive heating elements (e.g., heating coils, not specifically shown) and can be disposed within the straight portions 42 and, if included, the bent portions 44. In the example provided, the electric resistive heating coils can extend through the straight portions 42 and the bent portions 44 and have opposing leads (not specifically shown) extending from the proximal ends of each straight portion 42. Referring to FIG. 29, an example of a cartridge-type heater is shown. In this example, the heating element includes only straight portions 42. Each straight portion 42 is terminated at a distal end, and the heating element 16 is not bent to connect to the two straight portions 42. Instead, a resistive heating element (not shown) is disposed in each straight portion 42, with leads extending from the proximal ends of each straight portion 42.

[0084] 6 and 7, each heating element 16 is secured to at least a portion of each perforation 30 through which each heating element 16 extends. In the example provided, the heating elements 16 are secured by welding about halfway around each perforation 30, forming a weld joint 46 along half the circumference of the perforation 30.

[0085] As shown in FIG. 8 , the working fluid flows in a helical direction F, guided by the perforated helical member 18 of the flow guiding channel 22, and is continuously heated by the heating element 16. By using the flow guiding channel 22, the working fluid can be guided to flow across the heating surface of the heating element 16. Thus, the working fluid can be more efficiently heated by the heating element 16 within a given length of the heat exchanger 80, in contrast to a typical heat exchanger (not shown) in which the working fluid flows in a direction parallel to the longitudinal axis X of the heat exchanger. Since the working fluid is properly guided to flow across the heating surface of the heating element 16, dead zones in which the working fluid is not heated can be avoided. In conventional heat exchangers not specifically shown, dead zones cause the working fluid to break down, leading to fouling, in which materials accumulate and deposit on the heating element. Thus, the heat exchanger of the present teachings can reduce fouling and increase heat transfer efficiency by increasing the uniformity of the flow and reducing radiative heat loss to the shell or conduit (e.g., the body 82 shown in FIGS. 16 and 17 ).

[0086] As shown in Figures 9 and 10, the heating elements 16 may be inserted into the perforations 30 such that the bent portions 44 of the heating elements 16 form a concentric pattern around the central support member 40 (Figure 9) or a symmetrical pattern relative to the diameter of the perforated helical member 18 (Figure 10). Between the configurations shown in Figures 9 and 10, a concentric pattern can be used to fit a higher density of heating elements 16 into the same space, although other configurations and patterns can be used. Between the configurations shown in Figures 9 and 10, a concentric pattern generally has a tighter bend radius connecting the straight portions 42. Thus, the pattern can also be selected based on design criteria such as element density or bend radius. As best shown in Figure 12, the heating elements 16 can have different lengths such that some of the heating elements 16 extend further along the longitudinal axis X than others. The length of the heating elements 16 can be adjusted to fit a non-perforated helical member 18. 23In one configuration, one or more heating elements 16 can be a first set of heating elements all having a first length, while one or more different heating elements 16 can be a second set of heating elements all having a second length different from the first length. In this example, the heating elements 16 are not limited to only two sets having only two lengths, but can include additional sets and lengths.

[0087] As shown in Figures 11 and 12, the heater assembly 10 may further include a number of support rods 50 extending parallel to the longitudinal axis X of the heater assembly 10 through the peripheral groove 36 of the perforated helical member 18 and the non-perforated helical member 23. The support rods 50 may extend outward (i.e., radially relative to the longitudinal axis X) beyond the periphery of the peripheral groove 36 and may be configured as sliding rods for mounting the heater assembly 10 within the cylindrical cavity 84 of the tubular body 82 of the heat exchanger 80 (Figures 16 and 17). In other words, the support rods 50 reduce direct surface contact between the heater assembly 10 and the inner wall of the tubular body 82 to reduce friction (Figures 16 and 17), thus reducing the force required to slide the heater assembly 10 into the tubular body 82. Alternatively, the support rods 50 may not extend beyond the periphery of the peripheral groove 36 and may be configured to simply function as a structural support for the heater assembly 10. In the example provided, the support rods 50 are welded to the perforated helical member 18 and the non-perforated helical member 23 .

[0088] As shown in FIG. 1 , the heater assembly 10 may further include a pair of shrouds 52 provided at the proximal and distal ends 20, 21 for enclosing the perforated helical member 18, the non-perforated helical member 23, the heating element 16, and the support rod 50. At the proximal end, the shroud 52 is generally disposed between the non-heated portion 54 and the heated portion 56. Although FIG. 1 shows two shrouds 52, any number of shrouds 52, including one, may be provided for enclosing the perforated helical member 18, the heating element 16, and the support rod 50. If one shroud 52 is provided, the shroud 52 may be provided at the distal or proximal end 21 or 20.

[0089] As shown in Figures 13 and 14, each shroud 52 may define a cylindrical shroud member 51 and a plurality of deformable flaps 53 forming a skirt around the cylindrical shroud member 51. The cylindrical shroud member 51 may also encase a portion of the perforated or non-perforated helical member 18, 23. In the example provided, each cylindrical shroud member 51 extends along the longitudinal axis X for a length that is at least one full helical pitch of the corresponding perforated or non-perforated helical member 18, 23 that it encircles. The deformable flaps 53 are generally formed by cutting a radially outward flange portion of the shroud 52, and the flaps 53 may extend radially outward from the cylindrical shroud member 51. The contact with the inner wall of the tubular body 82 causes the flap 53 to elastically deform, urging the flap 53 into contact with the inner wall of the tubular body 82 and preventing flow from escaping between the tubular bodies 82 of the heat exchanger 80, thus mitigating blow-by. In the example provided, the flap 53 of the distal shroud 52 shown in FIG. 13 can be axially located near the distal end of the heater assembly 10, such as just before the outlet 88 of the tubular body 82 of the heat exchanger 80. For example, the flap 53 of the distal shroud 52 can be located approximately at the dashed line 92 shown in FIG. 17 before the outlet 88 of the tubular body 82. In the example provided, the flap 53 of the proximal shroud 52 shown in FIG. 14 can be axially located near the start of the perforated helical member 18, such as after the inlet 86 of the tubular body 82. For example, the flap 53 of the proximal shroud 52 can be positioned approximately at the dashed line 94 shown in FIG.

[0090] As shown in FIG. 15 , the proximal mounting flange 12 is configured to secure the heater assembly 10 to a tubular body 82 of a heat exchanger 80. The proximal mounting flange 12 includes a plate body 58, a plurality of apertures 60, and a plurality of bolt holes 62 extending through the plate body 58. The plurality of apertures 60 are aligned with the perforations 30 of the continuous series of perforated helical member 18 and are configured to pass the plurality of heating elements 16 through the proximal mounting flange 12. Although not specifically shown, the heating elements 16 can seal the apertures 60 to prevent fluid flow through the apertures 60. The plurality of bolt holes 62 are defined along the periphery of the plate body 58. The proximal mounting flange 12 is attached to the tubular body 82 of the heat exchanger by inserting bolts (not shown) through the bolt holes 62 and through bolt holes in a mating flange of the tubular body 82 (e.g., a mating flange 83 shown in FIG. 26 ). A gasket (not shown) or other sealing material may be used to form a fluid-tight seal between the mounting flange 12 and a mating flange (e.g., flange 83 shown in FIG. 26). In another configuration, not shown, the end plate or mounting flange 12 may be mechanically attached to the mating flange by different methods, such as welding, latches, clamps, etc.

[0091] The proximal mounting flange 12 may further define a circular central recess or groove 64 configured to align the central support member 40. The central groove 64 is coaxial with the longitudinal axis X, and the proximal end of the central support member 40 is configured to be received within the central groove 64. In the embodiment provided, the central support member 40 is welded to the proximal mounting flange 12.

[0092] 16 and 17, a heat exchanger 80 constructed in accordance with the teachings of the present disclosure includes a tubular body or shell 82 defining a cylindrical cavity 84, an inlet 86, an outlet 88, and a heater assembly 90 disposed inside the tubular body 82. The heater assembly 90 defines a proximal end 20 and a distal end 21. A proximal mounting flange 12 is configured to secure the heater assembly 90 to the body 82.

[0093] The heater assembly 90 is structurally similar to that of FIG. 1, except that a continuous series of perforated and non-perforated helical members 18 and 23 are connected such that the helix defined by the perforated and non-perforated helical members 18 and 23 has a variable pitch. Accordingly, like elements are designated with like reference numerals and detailed descriptions thereof are omitted herein for clarity. In the example provided, the outlet 88 is a radial outlet such that the flow passage 22 opens radially therethrough. In an alternative configuration not specifically shown, the outlet 88 can be an axial end outlet opening through the axial end 96 of the body 82.

[0094] Returning to the example provided, the helix defined by the perforated helical member 18 and the non-perforated helical member 23 may have a maximum pitch at the proximal end 20 (near the inlet 86 of the heat exchanger 80) and a minimum pitch at the distal end 21 (near the outlet 88 of the heat exchanger 80). In one form, the pitch is a continuously variable pitch, with the pitch gradually decreasing from the proximal end 20 to the distal end 21. Alternatively, as shown in FIG. 17, the heater assembly 90 may define multiple zones along the longitudinal axis X of the heater assembly 90. The pitch may be fixed within a particular zone, and different zones may have different pitches. For example, the heater assembly 90 may define three heating zones having a first fixed pitch P1 in the first zone, a second fixed pitch P2 in the second zone, and a third fixed pitch P3 in the third zone. The second fixed pitch P2 is greater than the third fixed pitch P3 and less than the first fixed pitch P1. The first pitch P1 is located at the proximal end 20. The third pitch P3 is located at the distal end 21. The second pitch P2 is located between the first pitch P1 and the third pitch P3. Although three zones are shown, more or fewer zones can be used. In one form, each perforated helical member 18, or group of perforated helical members 18, can have a constant helical pitch along a particular length thereof, while different perforated helical members 18, or different groups thereof, can have variable pitches forming a variable pitch geometric helix.

[0095] In another configuration not specifically shown, the perforated helix can be formed from a single continuous helical member that extends from the proximal end to the distal end of the heater assembly, rather than from individual pieces connected together. For example, the single helical member can be extruded, formed by feeding strip stock sheet metal through opposing conical dies, or 3D printed.

[0096] Referring to FIG. 18, the figure illustrates a temperature distribution of the heating element 16 along the longitudinal axis X for one particular configuration of the heater assembly 10, 90. The temperature of the portion of the heating element 16 adjacent the proximal end portion of the heater assembly is about 33.94° C. in the particular example. As the working fluid is guided by the flow directing channels 22 of the perforated helical member 18 and flows to the distal end of the heater assembly 10, 90, the temperature gradually increases to about 534.92° C. in the example provided. The example provided in FIG. 18 illustrates a temperature distribution for one particular inlet temperature, power load to the heating element 16, and mass flow rate of the fluid, other temperatures and distributions may result from different conditions or configurations. In general, a heater assembly configured according to the teachings of the present disclosure will have a reduced heating element temperature without dead zones where the working fluid would not be heated along its flow path.

[0097] 19, a graph illustrates the temperature of the heating element 16 versus distance from the proximal mounting flange 12. The proximal mounting flange 12 is positioned proximate to the inlet 86 of the heat exchanger 80. As the working fluid enters the inlet 86 and flows out of the proximal mounting flange 12, the temperature of the outer surface of the heating element 16 steadily and gradually increases, as shown by line 97. In contrast, the outer surface of the heating element in a typical heat exchanger (not shown) has a higher temperature that rises and falls, as shown by line 98, as the fluid flows away from the proximal flange (i.e., from inlet to outlet). Thus, the teachings of the present disclosure provide a heater assembly and heat exchanger that provides a consistent, lower linear temperature rise of the heating element along the length of the heat exchanger.

[0098] The heater assembly of the present disclosure is applicable to any heating device (e.g., electric heating device) for heating a working fluid. A continuous series of perforated helical members 18 guide the fluid to create a uniform helical cross-flow pattern. The helical flow passages 22 of the heater assembly 10, 90 can modify and increase the flow path of the working fluid without increasing the length of the heater assembly 10, 90. Thus, the heater assembly 10, 90 can improve the heat transfer from the heater assembly 10, 90 to the working fluid. The increased heat transfer efficiency can reduce the sheath temperature of the heating element 16 and the temperature of the shell (e.g., tubular body 82) of the heat exchanger, and can reduce the physical footprint of the heat exchanger.

[0099] Additionally, the perforated helical member 18 may be formed of a thermally conductive material. Because the perforated helical member 18 may be connected to the heating element 16 (e.g., via welds 46 shown in FIG. 7), they may be considered an extension of the heating element 16 and function as an extended heating surface or heat spreader or fins to distribute heat to the working fluid, thereby increasing heat transfer from the heating element 16 to the working fluid. The central support member 40 may take the form of a cylindrical electric heating device to further heat the working fluid in an electric heat exchanger.

[0100] Additionally, the heater assembly 10, 90 is more rigid than conventional heat exchangers due to the use of a continuous series of perforated helical members 18 and the use of a central support member 40 which is connected to the proximal mounting flange 12 which is connected to the body of the heat exchanger. This continuous construction improves the vibration characteristics of the heat exchanger, thereby increasing the stiffness and damping characteristics of the heater assembly. The support rods 50 can further increase the stiffness and damping characteristics.

[0101] Further shown in Figures 20-25 is a heater assembly 210, and in Figures 26-28 is a heat exchanger 80 including the heater assembly 210. The heat exchanger 80 and heater assembly 210 are similar to the heat exchanger 80 and heater assemblies 10, 90, except as specifically shown or described herein, and therefore like elements are indicated with like reference numerals and detailed descriptions thereof are omitted herein for clarity.

[0102] As shown in Figures 20 and 21, the heater assembly 210 can include a first lift member 214 and a second lift member 218. The first lift member 214 is fixedly coupled to the periphery of the mounting flange 12. In the example provided, the first lift member 214 extends from the top of the mounting flange 12 and defines an opening 222 through which a hook (not shown) or other lifting device can support the proximal end of the heater assembly 210. The second lift member 218 is fixedly coupled to a distal end of the central support member 40. In the example provided, the second lift member 218 extends from the top of the central support member 40 and is aligned with the first lift member 214. The second lift member 218 defines an opening 226 through which a hook (not shown) or other lifting device can support the distal end of the heater assembly 210. In the example provided, the second lift member 218 is disposed within the axial length of the non-perforated helical member 23, although it is possible for the second lift member 218 to extend beyond the non-perforated helical member 23. The first and second lift members 214, 218 are used to lift the heater assembly 210 so that the heater assembly 210 can be positioned within the tubular body 82 of the heat exchanger 80.

[0103] The heater assembly 210 may further include a shroud 230. The shroud 230 wraps around the perforated helical member 18, the heating element 16, and the support rods 50. The shroud 230 may be axially long to extend along the entire length of the heating section of the heater assembly 210 (e.g., including the shroud 52 shown in FIG. 1), or may be shorter than the entire heating section. Additionally, as shown in FIG. 22, the shroud 230 may include a plurality of thin-walled cylindrical shroud members 234. The shroud members 234 may prevent blow-through between the perforated helical member 18 and the tubular body 82. The shroud 234 may be formed from or coated with a heat-reflective material to form a heat shield that reflects heat radially inward toward the longitudinal axis X. Such a heat shield may further reduce heat loss to the body 82, lowering the temperature of the body 82. Adjacent cylindrical shroud members 234 can abut one another along longitudinal axis X. In one form, any of the cylindrical shroud members 234 of shroud 230 can optionally include a deformable flap 53 (FIGS. 13 and 14) to enable shroud 230 to function similarly to shroud 52 (FIGS. 1, 13 and 14).

[0104] In the example provided, the support rods 50 have a generally rectangular or cross-sectional shape, with each support rod 50 having an outer surface 238 that is flush with the outer circumference of the perforated and non-perforated helical members 18, 23. In one form, the outer surface 238 of each support rod 50 can have a curvature that matches the curvature of the outer circumference of the perforated and non-perforated helical members 18, 23. The shroud 230 is attached to the support rods 50. In the example provided, the support rods 50 include a plurality of holes 242, and each cylindrical shroud member 234 includes a plurality of holes 246 that align with the holes 242 in the support rods 50. Fasteners 250 (e.g., rivets, screws, etc.) or plug welds are received through the holes 242, 246 to attach the cylindrical shroud members 234 to the support rods 50.

[0105] With further reference to FIG. 23, the heater assembly 210 may further include an alignment plate 254. The alignment plate 254 is a flat circular disk including a plurality of apertures 256 and a peripheral groove 260. The apertures 256 are the same size and aligned with the perforations 30 of the perforated helical member 18. The peripheral grooves 260 are the same size and aligned with the peripheral grooves 36. The support rods 50 are received within the peripheral grooves 260 similar to the peripheral grooves 36. In the example provided, the alignment plate 254 defines a keyed central hole 262 having a diameter similar to that of the central support member 40 and a key 264 extending radially inward. In the example provided, the central support member 40 includes a key slot 266 opening through a distal end of the central support member 40. The key slot 266 extends through a wall of the central support member 40 and extends longitudinally parallel to the longitudinal axis X. The key slot 266 has a circumferential width of the central support member 40 that corresponds to the width of the key 264. The central support member 40 is received through the central bore 262 and the key 264 is received in the key slot 266 to restrain rotation of the alignment plate 254 relative to the central support member 40. In one form, the central bore 262 can include a plurality of keys 264 spaced circumferentially about the central bore 262 and the central support member 40 can include a corresponding number of key slots 266.

[0106] With continued reference to FIG. 23, the heater assembly 210 can further include one or more sensors (e.g., sensor 300). In the example provided, the sensor 300 is a thermocouple or other temperature sensor, although other types of sensors can be used. The sensor 300 includes a probe end 310 disposed within the flow directing channel 22. In the example provided, the probe end 310 is disposed proximate the outlet 88 (FIGS. 26 and 28) and is attached (e.g., welded or clamped) to one of the heating elements 16. The probe end 310 can be configured to detect the temperature of the heating element 16 to which it is attached. Similarly, additional sensors (not shown) can be attached to the other heating elements 16 to detect their temperatures. In an alternative configuration not shown, the probe end 310 can also be separate from the heating element 16 and configured to detect the temperature of the working fluid at the probe end 310.

[0107] The sensor 300 extends longitudinally from the probe end 310 toward the distal end of the central support member 40 generally along the outer longitudinal axis X of the central support member 40. In the example provided, the distal end of the central support member 40 includes a sensor slot 314 that penetrates the outer wall of the central support member 40 and is separate from the key slot 266. The sensor 300 has a bend that extends through the sensor slot 314 into the interior cavity of the central support member 40. The sensor 300 then extends within the central support member 40 toward the proximal end of the central support member 40. As shown in FIG. 25, the sensor 300 extends through a hole 318 in the mounting flange 12. The hole 318 is sealed around the periphery of the sensor 300 to prevent fluid from flowing through the hole 318. The hole 318 is within the radius of the groove 64. In this manner, the electrical connections for the sensor 300 can be on the back side of the mounting flange 12, along with the electrical connections for the heating element 16 if an electrical heating element is used.

[0108] In an alternative configuration, not shown, a set of a row of perforations 30 may not have a heating element 16, and a temperature sensor 300 may extend through that set of perforations 30 and the corresponding flange opening 60. In such a configuration, the probe may be located at any desired location along the longitudinal axis X. In an alternative configuration, one or more of the heating elements 16 may be used as a virtual sensor for detecting temperature.

[0109] 24 and 25, the opening 410 allows a small amount of fluid communication between the exterior and interior of the proximal end of the central support member 40. In the example provided, the central support member has a slot through its proximal end that cooperates with the mounting flange 12 to define the opening 410 when the central support member 40 is received in the groove 64 of the mounting flange 12. Unlike the groove 64 of FIG. 15, the groove 64 of FIG. 25 is an incomplete circle (i.e., does not extend completely around the longitudinal axis X). Instead, the groove 64 has a start portion 414 and an end portion 418 that align with the slot in the proximal end of the central support member 40. In the example provided, the groove 64 has a flat bottom adjacent to a central flat bottom surface. The start portion 414 and the end portion 418 also form a key that ensures proper rotational alignment of the central support member 40. In the example provided, the keys and alignment plate 254 between the central support member 40 and the mounting flange 12 cooperate to place the continuous helix in the correct rotational position where the perforations 30 are aligned with the openings 60, 256. In the example provided, the keys on both ends of the central support member 40 are aligned along the same line parallel to the longitudinal axis X, although other configurations can be used. In the example provided, the groove 64 extends radially outward a short distance at the beginning 414 and end 418 of the groove 64. In the example provided, the central support member 40 is welded to the mounting flange 12 from the beginning 414 to the end 418 of the groove 64. In other words, the central support member 40 is welded around its periphery except for the surrounding area where the slot defines the opening 410. The opening 410 can be aligned with the top of the mounting flange 12. In another form, the opening 410 can be a hole defined entirely by the central support member 40 near the proximal end.

[0110] 27, an edge 28 (i.e., near the proximal end) of the first perforated helical member 18 can be positioned along the longitudinal axis X at or before the inlet 86 so that flow from the inlet enters the flow passage 22. As shown in FIG. 28, an opposing edge 26 (i.e., near the distal end) of the last perforated helical member 18 can be positioned along the longitudinal axis X at or before the outlet 88. In the example provided, the longest of the heating elements 18 extends along the longitudinal axis X to a position that is partially within the area aligned with the outlet 88, although other configurations can be used. In the example provided, the last cylindrical shroud member 234 can extend along the longitudinal axis X to axially overlap the end of the longest of the heating elements 16, directing fluid from the last heating element 16 to the non-perforated helical member 23 before exiting the outlet 88, although other configurations can be used.

[0111] With further reference to FIG. 29, a heater assembly of a third construction 312 1 shows a portion of the heater assembly. 312 1. is similar to heater assemblies 10, 90, 210 except as specifically shown or described herein. Accordingly, like elements are indicated with like reference numerals and detailed descriptions thereof are omitted herein for clarity. In the example provided, heating element 16 is a closed-ended 316 26. In other words, the straight portions 42 are not connected by bends. In the example provided, the heating elements 16 are electrical resistance heating elements, such as cartridge heaters, that have all of their leads (not shown) extending from the same straight portion 42 on opposite sides of the mounting flange 12 (as shown in FIG. 26).

[0112] It should be noted that the present disclosure is not limited to the embodiments described and shown as examples. A wide variety of variants have been described and are part of the knowledge of the person skilled in the art. These and further variants, as well as substitutions by technical equivalents, can be added to the description and figures without departing from the scope of protection of the present disclosure and the present patent. [1] a continuous perforated helical baffle defining a geometric spiral about a longitudinal axis, said perforated helical baffle defining a predetermined pattern of a plurality of perforations extending parallel to the longitudinal axis through said perforated helical baffle; and a plurality of heating elements extending through said plurality of perforations; A heater assembly comprising: [2] The continuous perforated spiral baffle includes a continuous series of a plurality of perforated helical members that cooperate to define the geometric spiral disposed about the longitudinal axis of the heater assembly, each perforated helical member defining opposing edges and a predetermined pattern of the plurality of perforations, the plurality of perforations extending through each perforated helical member parallel to the longitudinal axis. [3] Each heating element includes a first segment, a second segment, and a bend connecting the first and second segments, the first segment extending through a first set of the plurality of perforations and the second segment extending through a second set of the plurality of perforations, the second set of the plurality of perforations being parallel to and offset from the first set of the plurality of perforations. [4] A heater assembly in which multiple heating elements are arranged in a concentric pattern [1]. [5] A heater assembly according to [1], further comprising a central support member, each of the spiral baffles defining a central opening, the central support member extending through the central openings. [6] The heater assembly according to [5], further comprising a temperature sensor extending through an interior of the central support member, the temperature sensor including a probe exterior to the central support member. [7] A heater assembly according to claim 5, further comprising a proximal flange configured to secure the heater assembly to a heat exchanger body, the flange defining a plurality of flange openings and a central groove, the plurality of flange openings aligned with the plurality of perforations in the spiral baffle, the plurality of heating elements extending through the plurality of flange openings, and the central support member being received in the central groove. [8] The heater assembly according to [7], further comprising an opening providing fluid communication between an exterior of the central support member and an interior of the central support member adjacent the flange. [9] The heater assembly according to [1], further comprising a non-perforated helical member disposed at a distal end of the perforated helical baffle, the non-perforated helical member forming an extension of the geometric helix.

[10] 10. A heater assembly according to claim 1, further comprising a plurality of rods extending parallel to the longitudinal axis, the periphery of the spiral baffle defining a plurality of grooves, the plurality of rods being at least partially disposed within corresponding sets of the plurality of grooves.

[11] The heater assembly according to

[10] , wherein the rod extends outwardly from the groove beyond a periphery of the spiral baffle, and the heater assembly is configured to be received within a cylindrical cavity of a body, the rod being configured to provide sliding contact with a wall of the body defining the cylindrical cavity.

[12] The heater assembly according to

[13] , further comprising a shroud disposed around at least a portion of the perforated spiral baffle and coupled to the rod.

[13] The heater assembly according to

[12] , wherein the shroud is a heat shield configured to reflect radiant energy radially inward relative to the longitudinal axis.

[14] The heater assembly according to

[14] , wherein the shroud includes at least one skirt defining a plurality of deformable flaps extending radially outward relative to the longitudinal axis.

[15] The heater assembly according to [1], wherein the geometric spiral defines a variable pitch.

Claims

1. A heater assembly configured to be received in a cylindrical cavity of a body having an inlet and an outlet, The heater assembly includes: a continuous perforated helical baffle defining a geometric spiral about a longitudinal axis, the perforated helical baffle defining a predetermined pattern of a plurality of perforations extending parallel to the longitudinal axis through the perforated helical baffle; a non-perforated helical member disposed at a distal end of the perforated helical baffle; a plurality of electrical resistance heating elements extending through the plurality of perforations; the perforated helical baffle having a variable pitch and the non-perforated helical member forming an extension of a geometric helix; Heater assembly.

2. the pitch of the geometric spiral is greatest at a proximal end of the geometric spiral configured near the inlet and the pitch of the geometric spiral is least at a distal end of the geometric spiral configured near the outlet. The heater assembly according to claim 1 .

3. the pitch is a continuously variable pitch that gradually decreases from the proximal end to the distal end. A heater assembly according to claim 2.

4. the geometric spiral defines a plurality of zones along the longitudinal axis, the pitch being fixed within certain zones and different zones having different pitches; The heater assembly according to claim 1 .

5. the geometric spiral has a first pitch in a first zone along the longitudinal axis and a second pitch in a second zone along the longitudinal axis, the second pitch being shorter than the first pitch; A heater assembly according to claim 4.

6. the geometric spiral has a third pitch in a third zone along the longitudinal axis, the third pitch being shorter than the second pitch, the second zone being located between the first zone and the third zone; A heater assembly according to claim 5.

7. the heater assembly further comprises a mounting flange, the electrical resistance heating element extending from the mounting flange past the inlet toward the outlet without axially overlapping the outlet along a longitudinal axis, and the third zone overlapping the outlet. A heater assembly according to claim 6.

8. the first zone is located closer to a proximal end of the geometric spiral than the second zone, the proximal end being configured closer to the inlet; A heater assembly according to any one of claims 5 to 7.

9. 8. A heater assembly according to claim 1, wherein each heating element includes a first segment, a second segment, and a bend connecting the first and second segments, the first segment extending through a first set of the plurality of perforations and the second segment extending through a second set of the plurality of perforations, the second set of the plurality of perforations being parallel to and offset from the first set of the plurality of perforations.

10. A heater assembly according to any of claims 1 to 7, further comprising a central support member, said spiral baffle defining a central opening, said central support member extending through said central opening.

11. the non-perforated helical member has a pitch equal to a diameter of the outlet; The heater assembly according to claim 1 .

12. 8. A heater assembly according to any of claims 1 to 7, wherein the continuous perforated spiral baffle includes a continuous series of a plurality of perforated helical members which cooperate to define the geometric spiral disposed about the longitudinal axis of the heater assembly, each perforated helical member defining opposing edges and a predetermined pattern of the plurality of perforations, the plurality of perforations extending through each perforated helical member parallel to the longitudinal axis.

13. 8. A heater assembly according to claim 1, further comprising a plurality of rods extending parallel to the longitudinal axis, the periphery of the spiral baffle defining a plurality of grooves, the plurality of rods being at least partially disposed within corresponding sets of the plurality of grooves.

14. 8. A heater assembly according to claim 1, further comprising a shroud disposed around at least a portion of said perforated spiral baffle and coupled to a rod.

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