Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
  • F28F9/007—Auxiliary supports for elements
  • F28F9/0075—Supports for plates or plate assemblies
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D9/00—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D9/0025—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being formed by zig-zag bend plates
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D9/00—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D9/0062—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits for one heat-exchange medium being formed by spaced plates with inserted elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F3/00—Plate-like or laminated elements; Assemblies of plate-like or laminated elements
  • F28F3/02—Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations
  • F28F3/022—Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations the means being wires or pins
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F2240/00—Spacing means

Definitions

• the invention relates to a wire spacer for a plate type heat exchanger, and to a heat exchanger provided with a plurality of such wire spacers. Furthermore, the invention relates to a method for upgrading existing plate type heat exchangers.
• a conventional plate type heat exchanger generally consists of a plurality of heat transfer plates, forming spatially separated but thermally connected fluid channels through which fluid streams with a different temperature are allowed to flow. This enables heat transfer to take place from the hotter fluid to the colder fluid.
• a yoke portion of a U- shape for abutting the first heat transfer plate along a first support line in the direction of the fluid fl ow
• second support segments e.g. a yoke portion of an inverted U-shape
• spacing segments e.g. legs of the U-shape
• the periodical wire spacers from US 2,595,457 have to be welded or brazed with their yoke portions to at least one of the heat transfer plates, in order to fix the orientation of the wire spacer with respect to the plates, and to provide sufficient thermal bonding for obtaining the increased effective heat transfer area.
• the required welding or brazing complicates manufacturing of such a heat exchanger.
• the wire spacer according to this aspect of the invention is formed by bending a stiff wire into a desired elongate shape.
• the mechanical stiffness (or rigidity) of the wire material is sufficient to maintain the predefined wire shape during use of the heat exchanger, to properly space (i.e. maintain the desired space between) the heat transfer plates.
• the minimally required stiffness is determined by th e allowed deformations of the wire spacers and the heat transfer plates under the typical thermal gradients and mechanical stresses occurring during heat exchanger operation.
• the wire portion perpendicular to the plates must be rigid with respect to the stresses imposed on the wire, and the wire thickness must be selected to meet this condition.
• the heat transfer plates are 1 - 2 millimeter thick, so that the wire cross-section (or diameter, in case of a cylindrical wire) typically needs to be in the range of 2 - 4 millimeter.
• height of the vertical portion must be 0.1 to 0.2 mm smaller than the spacing distance between the heat transfer plates, both in cold condition and during shop assembly, in order to accommodate the small deformation due to thermal gradients during operation.
• the material of the wire should be selected based on the expected heat exchanger operating temperature and thermal gradient forces.
• the possible wire materials are carbon steel wire (uncoated or aluminized or galvanized), various grades of austenitic stainless steel.
• a circular wire cross-section is preferred, but other wire cross- section shapes (e.g. polygonal) are possible.
• the wire paths jointly span the support plane parallel to and abutting the first (lower) heat transfer plate.
• “Spanning of the plane” refers herein to providing at least three points that are non-coinciding and not co-linear, and that together define the support plane.
• the term "wire path” refers herein to a continuous portion of the bent wire that traces out a curved or bent wire trajectory spanning at least a line but preferably spanning a portion of the support plane (e.g. by forming a semi-circular shape, a U-shape, an S-shape, or a W- shape, within the support plane). In any case, the wire paths are formed to at least jointly span the support plane comprising the first support line.
• the first support line forms a path along the first heat transfer plate, which path may for example be linear along a first direction corresponding to the main flow direction of the fluid within the channel enclosed by the adjacent heat transfer plates, e.g. in a cross-flow plate type heat exchanger with linear fluid channels.
• the first support line may be slightly curved, or even substantially curved so as to follow a more sophisticated trajectory, e.g. the trajectory defined by the curved fluid channels in a Z-type concurrent- or counter-flow plate type heat exchanger.
• Each wire path extends at its path ends into respective spacing segments.
• the spacing segments interconnect the first support segments and the second support segments in an alternating manner, and have a mechanical stiffness that is sufficiently large for keeping the first and second heat transfer plates at the desired spacing distance, as was described herein above.
• each wire path in the wire spacer functions as a base for supporting the wire spacer, and for fixing the orientation of the wire spacer with respect to the heat transfer plates.
• the spacing segments extend at least partially and preferably entirely along a second direction that is locally perpendicular to the first support line.
• the second direction is perpendicular to the first direction.
• this second direction will be perpendicular to the heat transfer surfaces of both heat transfer plates.
• the proposed wire spacer according to this aspect allows for easy placement between two adjacent heat transfer plates, without needing further means for holding the wire spacer in the correction upright orientation.
• the proposed wire spacers may be configured as relatively thin elongated structures, which do not occupy a significant volume.
• bar spacers e.g. known from patent document US 5,383,5166
• plate-embossing spacers e.g. known from patent document US 2,281,754 create large flow obstructions and corresponding pressure drops.
• the wire paths of the wire spacer jointly extend bi- directionally from the first support line and along a transversal direction, which is perpendicular to the first support line and is within in the support plane.
• the wire paths may comprise smoothly curved portions and/or connected linear segments, or various other shapes spanning the support plane.
• any of the wire paths may comprise interconnected linear path segments that are oriented in the support plane and perpendicular to the first support line.
• any wire path may be formed as a smoothly curved shape with its curvature spanning the support plane, e.g. a semi-circular wire path.
• each wire path extends to at least one side of the first support line along the transversal direction, which is oriented perpendicular to the first support line.
• the wire paths may extend toward opposite sides in an alternating manner along the wire spacer. For example, one particular wire path may extend to the positive transversal direction, while the preceding and subsequent wire paths extend to the negative (i.e. opposite) transversal direction. This alternating configuration allows fixing the orientation of the wire spacer between the heat transfer plates, while requiring a minimal amount of wire.
• each wire path may be individually bent to extend bi-directionally along both the positive and negative transversal directions from the first support line, to span a total base width.
• a wire path that by itself extends to both directions from the first support line allows stabilization of its orientation with respect to the first heat transfer plate.
• the wire spacer may be formed as a periodical structure of consecutive identical units that each comprise an interconnected quadruplet formed by a first support segment, a spacing segment, a second support segment, and a further spacing segment. This periodicity greatly simplifies the manufacturing process wherein the wire is bent to form the proposed wire spacer.
• the total base width equals the spacing distance.
• an incidental occurrence of local twisting of the wire spacer about an axis parallel to the support line i.e. a rotation of wire paths in the plane spanned by the spacing direction and transversal direction
• the rotated wire paths with a total base width matching the desired spacing distance will still locally provide a spacing function.
• the wire path may be formed by multiple interconnected linear path segments that are arranged with their long axes directed along the transversal direction. These linear path segments may be abutting as viewed along the support line, and interconnected by short curved portions at the respective segment end points.
• a length of the wire path viewed along the support line i.e. the first or fluid flow direction
• the support width in the transversal direction will be maximized.
• the wire path may be formed as one of a contracted U-shape, a contracted S-shape, or a contracted W-shape. Any one of these shapes is easily formed in a manufacturing process involving wire bending actions in the positive and negative transversal directions only. Hence, wire bending actions in the direction along the support line, which complicate the manufacturing process, are avoided.
• the wire path is smoothly curved in the support plane.
• the wire path forms one of a U-shape, an S-shape, or a curved W-shape.
• a smoothly curved wire path is easily formed by bending the wire into the desired shape, without creating sharp turns or folds. Smooth curves minimize the risk of breaking the wire during construction.
• the smoothly curved wire path provides a considerable structural support area in the support plane, while minimizing the thermal contact area between the wire spacer and the first heat transfer plate. Any one of a smoothly curved U-shape, an S-shape, or a curved W-shape, is easily formed in a manufacturing process involving wire bending actions in the transversal directions only. Hence, wire bending actions in the direction along the first support line, which would complicate the manufacturing process, are avoided.
• the second support segments are formed by linear support segments with support lengths along the first support line.
• the first support segments are effectively spaced along the first support line by the linear support segments.
• the preferred lengths of these linear support segments are determined by the expected differential pressures between the adjacent channels and the operating temperatures occurring in the heat exchanger.
• the wire spacer possesses a linear symmetry that will provide a nearly uniform linear supporting capability along the first support line.
• the wire spacer manufacturing process is greatly simplified.
• the support lengths are equal support lengths in the range of 100 mm - 200 mm.
• Support lengths in the range of 100 mm - 200 millimeter allow robust spacing in a heat exchanger having heat transfer plates o 1 2 millimeter thickness, and operating at a differential pressure of 500 - 1000 Pa in a temperature range of 100-300 C.
• the spacing segments are formed by perpendicular linear segments with spacing heights equal to the spacing distance.
• the wire could extend transversely at the end of the perpendicular linear segments in addition to or in alternative to support segments along the first support line.
• Spacing segments formed from linear segments that are oriented along the spacing direction provide maximal structural integrity and support.
• a cross-section of the bent wire is circular.
• a circular wire is easy and cheap to construct. Due to its cylindrical symmetry, the circular wire is easily bent into any desired elongated wire spacer shape. In addition, the isotropic bending resistance of the circular wire allows bending in the transversal and spacing directions required for forming the inherently three-dimensional configuration of the proposed wire spacer according to the first aspect.
• the circular cross section also minimizes the contact area between the wire spacer and the heat transfer plates, thereby avoiding excessive thermal gradients and resulting stresses occurring during operation of the heat exchanger (as is the case with pins or stud spacers welded to heat transfer plates, e.g. known from patent document WO96/19708). Furthermore, any thermal insulation coating can be applied to the smooth surface of the circular wire spacer in an easy and durable manner.
• a wire diameter of the bent wire is in a diameter range of 2 4 mm.
• this preferred diameter range yields a wire spacer that is sufficiently rigid to prevent deformation, while still allowing the wire to be manufactured without difficulty. A thicker wire would be difficult to process, while a thinner wire would not be able to prevent deformation.
• the bent wire has a first end and a second end, wherein each end is provided with attachment means for connecting the wire spacer to the first heat transfer plate and/or the second heat transfer plate.
• this connection could be through electrical resistance welding or through a pin welded to the first and/or second heat transfer plates.
• the wire spacer may be easily fixed with respect to the heat exchanger by attachment to externally accessible regions of the heat exchanger, for example to the plate edges near fluid channel apertures, or to flow guiding elements (ferrules) located at the plate edges.
• the first direction corresponding to the main flow direction of the fluid within the channel enclosed by the adjacent heat transfer plates may define a straight first support line along the first heat transfer plate (like in a cross-flow plate type heat exchanger with linear fluid channels).
• this first direction may also be construed as a local direction, which may change along the first support line. This allows the first support line to be curved along the fluid channel of the heat transfer plate (like in curved fluid channels in a Z-type concurrent- or counter- flow plate type heat exchanger).
• the at least one wire spacer of the plate type heat exchanger is releasably positioned between the adjacent heat transfer plates, and wherein the first end and second end of the wire spacer are fixed to respective outer edges of the heat transfer plates.
• this attachment can be made by electrical resistance welding or by welding a pin to the heat transfer plates.
• the method according to this aspect may also represent the reassembly phase after cleaning or repairing any heat exchanger provided with the wire spacers according to the first aspect of the invention.
• the initial phase comprises removing the wire spacers from the fluid channels of the plate type heat exchanger.
• the heat transfer plates having the wire spacers removed are easily cleaned or repaired by suitable methods without obstruction from the wire spacers.
• the original wire spacers or repaired substitutes are re- inserted into the fluid channels, as defined by this third aspect of the invention.
• FIG.1 schematically shows a heat exchanger according to an embodiment
• Fig.2 - 2d present perspective views of wire spacers according to embodiments
• Fig. 1 shows a perspective view of a plate type heat exchanger 1 for exchanging thermal energy between a first fluid 14 and a second fluid 16 having a different temperature.
• the shown heat exchanger 1 comprises a number of stacked heat transfer plates 2, 4.
• first fluid channels 6 and second fluid channels 8 are formed, for transporting the first fluid 14 and second fluid 16 respectively.
• the first and second fluid channels 6, 8 are oriented mutually perpendicular, along a first direction X and a transversal direction Z respectively.
• the first and second fluid channels 6, 8 are alternatingly provided in the heat exchanger 1 in a second (vertical) direction Y, which is perpendicular to the first direction X and the transversal direction Z.
• This plate configuration forms a so-called cross flow plate type heat exchanger.
• the adjacent heat transfer plates 2, 4 are spaced apart at a spacing height Ay in the second direction Y.
• Several of the first fluid channels 6 are provided with a plurality of wire spacers 20.
• the shown wire spacers 20 comprise first support segments 24, second support segments 26, and spacing segments 28 that interconnect the first support segments 24 and the second support segments 26.
• the first support segments 24 are formed so as to abut the first heat transfer plate 2 along a first support line C 1
• the second support segments 26 are formed so as to abut the second heat transfer plate 4 along a second support line C2.
• the first support segments 24 are curved into wire paths 32, which jointly define a first support plane S 1 that comprises the first support line C 1.
• each wire path 32 comprises three linear path segments 34a-c that are interconnected via sharply curved segments, jointly forming a contracted S-shape.
• the linear path segments 34a-c of each wire path 32 jointly extend
• each wire path 32 forms a support portion that spans a total base width ⁇ and effectively holds the wire spacer 20 steady between the heat transfer plates 2, 4, with the spacing wire segments 28 in an upright orientation.
• the total base widths ⁇ of the wire paths 32 equal the spacing distance Ay between the second support segments 26 and the first support line CI .
• the second support segments 26 are formed as linear wire segments with second support lengths along the second support line C2.
• the second support lengths ⁇ 2 of subsequent second support segments 26 are shown to be equal.
• a typical value for the second support lengths ⁇ 2 may be in the range of 100 mm - 200 mm.
• the spacing segments 28 interconnect the first support segments 24 and the second support segments 26 in an alternating manner.
• the spacing segments 28 in the shown embodiments are formed as linear wire segments that are perpendicular to the first support plane S 1 , and which hold the second support segments 26 at a spacing distance Ay from the first support line C 1.
• the spacing distance Ay is preferably 0.1 to 0.2 mm smaller than a plate distance between the heat transfer plates 2. 4 of a fluid channel 6, 8 in cold condition.
• the wire spacer 20 is manufactured from bending a wire 22 having a circular cross-section, into a periodical structure having a multiplicity of the described segments.
• a typical wire diameter 0 of the bent wire 22 (see Fig.2a) is in a diameter range of 2 4 mm.
• each bent wire 22 has a first wire end 6 located at one side of the first fluid channel 6.
• the bent wire 22 is provided with attachment means 44 for connecting the wire spacer 20 to the first heat transfer plate 2.
• the wire spacer 20 terminates in a second end (not shown), wherein also the second end is provided with similar plate attachment means 44.
• the wire spacers 20 are releasabiy positioned between the adjacent heat transfer plates 2, 4, by temporarily fixing each wire spacer 20 with its first and second ends via the attachment means 44 to respective outer edges of the first heat transfer plate 2.
• the attachment means 44 may also be provided on an upwardly bent portion of the wire spacer 20, so as to attach the wire spacer 20 to the second heat transfer plate (4).
• the attachment means 44 can include ends of wire being attached through electrical resistance welding or through a pin welded to the heat transfer plate 2 and/or 4.
• each wire path 32 comprises only two linear path segments 34a, 34b that is interconnected via one sharply curved segment, and which jointly form a contracted U -shape.
• each wire path 2 only extends in a single transversal direction Z within the first support plane S I from the first support line CI .
• Consecutive wire paths 32, 32 ' transversally extend in opposite transversal directions, so that the wire paths 32 jointly extend bidirectionally from the first support line CI .
• wire spacers 20 provided with wire paths 32 formed from linear path segments and sharply curved connection segments may be conceived.
• the wire path 32 may be formed from a contracted W-shape with four linear path segments joined by three sharply curved interconnection segments.
• F ig.2 c shows an alternative embodiment of the wire spacer 20, wherein the wire paths 32 are smoothly curved within the support plane S I, so as to form a smooth S-shape. Also in this embodiment, each wire path 32 extends bi-directionally from the first support line C I , and spans a total base width ⁇ .
• the wire spacer 20 in F ig.2c has a smoothly curved first support segment 24 with a first support length ⁇ that is considerably larger than in the previous embodiments.
• wire path 32 may be formed as a U-shape, or a curved W- shape.
• Fig. 2d shows a further alternative embodiment of wire spacer 20, wherein each wire path 32 comprises three linear path segments 34a-c that are interconnected via sharply curved segments, jointly forming a contracted S-shape, similar to the embodiment shown in Fig. 2 A.
• wire path 32 alternatingly forms first support segments 24 along line CI and C2, with second support segments 26 and spacing segments 28 between.
• wire spacer 20 is formed by bending the wire 22 using only bending operations in directions transversal to a main direction along the wire spacer 20, e.g. along the first direction X (or any of the support lines CI , C2).
• the wire path 32 may also be formed from backward or forward wire bending operations along this main direction along the wire spacer 20, although this will complicate the manufacturing process.
• a wire spacer 20 having a more complex wire path 32 configuration may be obtained.
• An example of such a complex wire path 32 is a (nearly) circular wire path (not shown) that starts at an end of a spacing wire 28, extends perpendicular along the transversal direction Z, curves backward along the negative first direction -X, toward the negative transversal direction Z, toward the positive first direction X, and back along the transversal direction Z to extend into a subsequent spacing wire.
• any combination of the wire paths 32 described above may be provided within a single wire spacer 20.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

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Applications Claiming Priority (2)

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Citations (6)

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• 2014
  • 2014-01-20 NL NL2012111A patent/NL2012111C2/en not_active IP Right Cessation
• 2015
  • 2015-01-20 WO PCT/EP2015/050954 patent/WO2015107209A1/en active Application Filing
  • 2015-01-20 RU RU2016133969A patent/RU2710457C2/ru active
  • 2015-01-20 EP EP15700713.9A patent/EP3097378B1/de active Active
  • 2015-01-20 US US15/112,719 patent/US20160341493A1/en not_active Abandoned
  • 2015-01-20 CA CA2937382A patent/CA2937382A1/en not_active Abandoned
  • 2015-01-20 KR KR1020167022767A patent/KR20160111979A/ko not_active Application Discontinuation

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