EP1203195B1 - Enhanced crossflow heat transfer - Google Patents
Enhanced crossflow heat transfer Download PDFInfo
- Publication number
- EP1203195B1 EP1203195B1 EP00958015A EP00958015A EP1203195B1 EP 1203195 B1 EP1203195 B1 EP 1203195B1 EP 00958015 A EP00958015 A EP 00958015A EP 00958015 A EP00958015 A EP 00958015A EP 1203195 B1 EP1203195 B1 EP 1203195B1
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- EP
- European Patent Office
- Prior art keywords
- conduits
- heat exchange
- fluid flow
- conduit
- heat transfer
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 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
- F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
- F28F13/06—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by affecting the pattern of flow of the heat-exchange media
Definitions
- the present invention relates generally to methods and related apparatus for enhancing heat transfer to or from a fluid flowing cross-wise in contact with the outer thermally-conductive shells of a plurality of axially-oriented heat exchange conduits capable of acting as heat sources or heat sinks.
- a fluid flowing cross-wise in contact with the outer thermally-conductive shells of a plurality of axially-oriented heat exchange conduits capable of acting as heat sources or heat sinks By channeling cross-wise fluid flow, flowing generally orthogonal to the axes of the heat exchange conduits, and contouring it around the heat exchange conduits utilizing surrounding sleeve-like elements, a surprisingly more effective and efficient heat transfer between the flowing fluid and the thermally conductive surface is realized.
- thermal-transfer surface that acts as a heat source or heat sink is the exterior of a thermally-conductive shell of a thermal-transfer tube or pipe, for example, which is heated or cooled by means of a liquid flowing axially through the interior of the tube or pipe.
- heat may be supplied directly inside a heat exchange conduit by means of flameless combustion of fuel gas (such as hydrogen or a hydrocarbon) as taught, for example, by U.S. Patent Nos. 5,255,742 and 5,404,952 .
- fuel gas such as hydrogen or a hydrocarbon
- reactor designs embodying at least in part a radial, crossflow of process fluid relative to a plurality of axially-disposed heat-transfer tubes are shown in U. S. Patent Nos. 4,230,669 ; 4,321,234 ; 4,594,227 ; 4,714,592 ; 4,909,808 ; 5,250,270 ; an 5,585,074 .
- cross-flow contact of a process fluid with a heat-transfer surface can be an attractive option for many applications, the utility of cross-flow contact for industrial applications has been limited by certain heat transfer inefficiencies which have been experienced in practice.
- a given portion of the process fluid is in contact with the heat-transfer surface for a shorter time than with a comparable axial flow design.
- the contact between the cross-flowing process fluid and the heat-transfer surface is uneven due to process fluid separation and recirculation. Short surface contact time, uneven contact, and limited fluid mixing can lead to inefficient, insufficient, and/or non-uniform thermal energy transfer.
- the present invention provides fluid flow contouring apparatus having the features set out in claim 1 of the accompanying claims.
- a fluid flow contouring apparatus having the features defined in the preamble of claim 1 is disclosed for instance in US 3616 849 .
- the invention also provides a method for enhancing heat transfer to or from a fluid flowing cross-wise in contact with the outer surfaces of a plurality of heat exchange conduits, said method having the features set out in claim 13 of the accompanying claims.
- the fluid flow constriction structure is a larger, generally concentric sleeve-like structure at least partially surrounding each conduit in an array of tubular heat exchange conduits, each such sleeve structure having apertures upstream and downstream of the centrally-located heat exchange tube.
- Apertured sleeves of this type at least partially surrounding individual heat exchange conduits in an array of such conduits have been found to enhance heat transfer by a factor of about five times or more.
- Embodiments of the invention may provide heat-transfer conduit arrays of varying sizes and configurations wherein each conduit of the array is associated with its own fluid flow-constriction means upstream, downstream and/or around or alongside of the conduit so as to preferentially contour the portion of the fluid stream flowing crosswise past the outside of the conduit to realize improved heat transfer.
- the apparatus is designed so as to substantially restrict the bypassing of fluid flow such that a predominant portion of the process fluid is forced to flow past the heat-transfer surface.
- the heat transfer surface will typically be one or a configured array of heat exchange conduits, oriented to have parallel axes disposed in an axial direction which is generally orthogonal to the direction of fluid flow, and having a thermally-conductive shell.
- each such conduit is maintained at a temperature different from that of the upstream process fluid so that thermal energy is transferred to or from the process fluid by means of conduction, convection, radiation or some combination thereof, as the fluid flows past and contacts the exterior surfaces of the heat exchange conduits.
- the heat exchange conduits or ducts of this invention may broadly comprise tubes, pipes, or any other enclosures with heat sources or heat sinks.
- the exterior surfaces of the heat exchange conduits may be bare or, as discussed below, may be finned or any combination of the two.
- the cross-section of the conduits or ducts may be circular, elliptical, or any other closed shapes. Where a plurality of such heat exchange conduits are used, they will typically be arrayed in some predetermined configuration such as in a triangular array, a square array, a circular array, an annular array, or other such patterns depending on design choice and/or the requirements of a particular application. Relative to the direction of fluid flow, adjacent conduits may be aligned, staggered or otherwise positioned, again depending on design choice and/or application requirements.
- the size of the heat exchange conduits will be dictated, at least in part, by process requirements for the rate of heat transfer.
- conduits having larger cross sections will provide larger surface areas and therefore more heat transfer capacity.
- Fin elements, baffles or other heat-transfer enhancing structures may be provided on the outside surface of some or all of the heat exchange conduits to further increase surface area and improve heat transfer characteristics.
- a preferred embodiment utilizes closely spaced circumferential fins applied in a spiral along the exterior length of the conduit. This arrangement increases the heat-transfer surface area exposed to the crossflow without impeding the flow. It will be understood that the nature and flow rate of the process fluid, and the desired temperature change in the fluid between upstream of the heat exchange conduits and downstream of the conduits, will also affect these design choices.
- the apertures in the fluid flow constriction structure preferably comprise any combination of perforated holes or axial slots (i.e. elongated apertures having a longer axis generally parallel to the axial orientation of the heat exchange conduits).
- the holes or slots in different portions of the apparatus may be the same or differ in curvature, size and shape.
- the edges around the inlets and outlets may be straight, rounded, jagged, or some combination thereof.
- the fluid flow constriction structure is preferably positioned relative to an associated heat exchange conduit such that the distance between the centerline of an upstream or downstream aperture and the associated heat exchange conduit centroid ranges from about 0 to about 2.0, preferably from about 0.50 to about 1.00, times the outer diameter (or largest cross-sectional dimension of a non-circular conduit) of the conduit. In any case, the spacing between aperture and conduit must be sufficiently close to realize substantially enhanced heat transfer.
- the width (shortest side) of an elongated flow constriction aperture or the diameter of a generally circular hole constriction aperture may preferably range from about 0.02 to about 1.5, preferably from about 0.05 to about 0.25, times the outside diameter (or largest cross-sectional dimension of a noncircular conduit) of the conduit.
- the fluid flow constriction structure is preferably positioned relative to an associated heat exchange conduit such that the offset between the center of the aperture and the centroid of the heat exchange conduit ranges from 0 to 0.5, preferably 0, times the outside diameter (or largest cross-sectional dimension of a noncircular conduit) of the conduit.
- the enhanced crossflow heat exchange apparatus of this invention enhances heat transfer between the cross-flowing fluid and the plurality of heat exchange conduits by one or more of the following mechanisms:
- Fig.1 shows a crossflow heat exchange apparatus 10 according to this invention having a generally circular array of axially-disposed heat exchange conduits 12 distributed around the interior of an annular region 28 defined by an inner cylindrical wall 20 and an outer cylindrical wall 22, each having a common centerpoint 14.
- conduits 12 are of substantially the same diameter, which is less than the radial width of the annular region, and spaced substantially equidistant from one another.
- each heat exchange conduit 12 Associated with each heat exchange conduit 12 is an upstream aperture 24 in inner wall 20 and a downstream aperture 26 in outer wall 22. As shown in Fig.1 , respective pairs of upstream apertures 24 and downstream apertures 26 are substantially in radial alignment with the associated conduit 12 and with each other.
- a process fluid 30 is flowed axially into the inner cylindrical region 16 of the heat exchange apparatus 10 and then directed radially outward through upstream apertures 24, flowing cross-wise into contact with the heat exchange conduits 12, as denoted by the fluid flow arrows in Fig.1 , thereby heating or cooling the process stream to form a thermally conditioned fluid stream 32 which exits annular region 28 through downstream apertures 26.
- FIG.1 illustrates a radially-outward fluid flow path
- the same apparatus could be utilized for thermally treating a process stream flowing radially inward to center region 16 and thereafter being axially withdrawn from region 16.
- apertures 26 in the outer wall 22 would be the upstream apertures and apertures 24 in inner wall 20 would be the downstream apertures.
- Figs. 2A and 2B show a particularly preferred crossflow heat exchange apparatus 110 according to this invention having a generally circular array of axially-disposed heat exchange conduits 112, each surrounded by an apertured sleeve 120 having either (i) an upstream aperture 124 and a downstream aperture 126 or (ii) offset aperture pairs 174,176 and 184.186 as described below.
- the individual sleeves 120 are joined together into a larger ring-like or cylindrical structure by connecting walls 122.
- Apertures 124 and 126 may comprise columns of axially-oriented perforation holes or elongated slots which are radially aligned with the conduits 112. Alternatively, in a preferred embodiment also illustrated in one portion of Fig.
- aperture pairs 174, 176 and184, 186 are slightly offset from radial alignment in a staggered slot arrangement.
- the staggered slot arrangement for aperture pairs 174, 176 and 184, 186 is illustrated in Fig. 2A , with additional detail in Fig. 2B , where offset slot pairs 174, 176 and 184, 186 (replacing apertures pairs 124, 126) are staggered in elevation and offset slightly from the radial line from centerpoint 114 by equal angles 9.
- Fig. 2B shows a side view taken along the line 2B-2B in Fig. 2A of a heat exchange conduit 112 having a cylindrical sleeve 120 with the preferred staggered slot arrangement.
- FIG. 2A The plan view of this staggered slot conduit/sleeve combination as shown in Fig. 2A is taken along the line 2A-2A in Fig. 2B .
- the ends of the slots from alternating offset slot pairs can be slightly overlapped or at equal elevation so there is no interruption of flow along the axial direction of the heat exchange apparatus.
- This design with separation and overlap of the offset slots also leaves connection regions between the axially overlapped portions of adjacent offset slots, indicated generally by the reference numeral 190 in Fig. 2B , to provide the sleeves 120 with better circumferential mechanical integrity without blocking any fluid flow.
- Fig. 2A shows one apertured sleeve 120 having the two-pair offset aperture configuration while the other sleeves have the one-pair aligned aperture configuration. In practice, however, all of the apertured sleeves for a particular apparatus 110 will typically have the same aperture configuration.
- a process fluid 130 is flowed axially into the inner cylindrical region 116 having centerpoint 114 of the heat exchange apparatus 110 and then directed radially outward through upstream apertures 124, flowing cross-wise into contact with the heat exchange conduits 112, as denoted by the fluid flow arrows in Fig. 2A , thereby heating or cooling the process stream to form a thermally-conditioned fluid stream 132 which exits the interior regions defined by the sleeves 120 through downstream apertures 126.
- fluid flowing radially outward would either flow through upstream aperture 174, into contact with conduit 112, and exit through downstream aperture 176, or, depending on the axial elevation, instead flow through aperture pair 184,186.
- FIG. 2A illustrates a radially outward fluid flow path
- the same apparatus could be utilized for thermally treating a process stream flowing radially inward to center region 116 and thereafter being axially withdrawn from region 116.
- apertures 126 or 176 and 186
- apertures 124 or 174 and 184
- FIG. 3 shows a crossflow heat exchange apparatus 160 which is a variation of the crossflow heat exchange apparatus 110 shown in Fig. 2 .
- Apparatus 160 differs from apparatus 110 in the use of a double, concentric circular array of heat exchange conduits instead of the single circular array of Fig. 2 .
- there is a second circular array of heat exchange conduits 142 each in radial alignment with a corresponding conduit 112 of the first circular array.
- Each conduit 142 is surrounded by an apertured sleeve 150 having an upstream aperture 164 and a downstream aperture 166.
- Apertures 164 and 166 for a given sleeve 150 associated with a particular conduit 142 are shown substantially in radial alignment with the apertures 124 and 126 in the sleeve 120 of the corresponding radially adjacent conduit 112.
- the individual sleeves 150 are joined together into a larger ring-like or cylindrical structure by walls 152.
- Fig. 3 shows only a single conduit 142 of the second circular array of heat exchange conduits, it will be understood that each conduit 112 of the first circular array is associated with a corresponding conduit 142 of the second circular array.
- a partially thermally-conditioned fluid stream 132 exiting first downstream apertures 126 in sleeves 120 is directed radially outward through second upstream apertures 164, flowing cross-wise into contact with the second array of heat exchange conduits 142, thereby further heating or cooling the process stream to form a fully thermally-conditioned fluid stream 162 which exits the interior region defined by the sleeves 150 through second downstream apertures 166.
- Fig. 3 illustrates a radially-outward fluid flow path
- the same apparatus could be utilized for thermally treating a process stream flowing radially inward to center region 116 and thereafter being axially withdrawn from region 116.
- apertures 166 and 126 would be respectively the first and second upstream apertures
- apertures 164 and 124 would be respectively the first and second downstream apertures.
- Fig. 4 shows a portion of another crossflow heat exchange apparatus 210 according to this invention.
- a double row of axially-disposed heat exchange conduits comprising a first upstream row of conduits 212 and second downstream row of conduits 216, are disposed in a generally rectangular array in conjunction with: a first, upstream apertured plate 220 having apertures 226; a second, intermediate apertured plate 222 having apertures 228, plate 222 separating the first and second rows of conduits; and, a third, downstream apertured plate 224 having apertures 230.
- Each set of apertures 226, 228 and 230 associated with an upstream-downstream adjacent pair of conduits 212 and 216 is shown substantially in linear alignment with each other and with the associated pair of upstream and downstream conduits 212 and 216 respectively.
- a process fluid 232 is directed, as denoted by the fluid flow arrows in Fig. 4 , through apertures 226 and flowed cross-wise into contact with first, upstream heat exchange conduits 212, thereby partially heating or cooling the process stream to form a partially thermally-conditioned fluid stream 234.
- Stream 234 is then directed through apertures 228 and flowed cross-wise into contact with second, downstream heat exchange conduits 216 thereby further heating or cooling the process stream to form a fully thermally-conditioned fluid stream 236 which is flowed out of the apparatus 210 through exit apertures 230.
- Fig. 5 illustrates two alternative possible fluid flow paths through a multi-row set of heat exchange conduits 312 arranged in an offset or triangular array in accordance with another embodiment of a crossflow heat exchange apparatus 310 according to this invention.
- alternate rows of heat exchange conduits are offset from adjacent rows instead of having conduits in adjacent rows substantially in linear alignment as shown in Figs. 4 and 6 .
- the centerpoints of three adjacent conduits in two adjacent rows form an equilateral triangle 340.
- the apparatus of Fig. 5 includes upstream and downstream apertured plates respectively located before the after the last row of conduits, as well as intermediate apertured plates separating adjacent rows of conduits.
- each conduit 312 may be surrounded with an apertured sleeve-like structure as previously described for other figures.
- Fluid flow arrows 332 in Fig. 5 illustrate a first possible fluid flow orientation which can be utilized with the triangular conduit array of apparatus 310.
- Fluid flow arrows 334 in Fig. 5 illustrate a second possible fluid flow orientation which can be utilized with the triangular conduit array of apparatus 310.
- Fig. 5 shows four rows of heat exchange conduits in the triangular array, a smaller or larger number of conduit rows in this configuration may be utilized as appropriate.
- FIG. 6 illustrates two alternative possible fluid flow paths through a multi-row set of heat exchange conduits 412 arranged in a square array in accordance with still another embodiment of a crossflow heat exchange apparatus 410 according to this invention.
- conduits 412 in adjacent rows are substantially in linear alignment.
- the centerpoint of four adjacent conduits in two adjacent rows form a square 440.
- the apparatus of Fig. 6 includes upstream and downstream apertured plates respectively located before the first row of conduits and after the last row of conduits, as well as intermediate apertured plates separating adjacent rows of conduits.
- each conduit 412 may be surrounded with an apertured sleeve as previously described.
- Fluid flow arrows 432 in Fig. 6 illustrate a first possible fluid flow orientation which can be utilized with the square conduit array of apparatus 410.
- Fluid flow arrows 434 in Fig. 6 illustrate a second possible fluid flow orientation which can be utilized with the square conduit array of apparatus 410.
- Fig. 6 shows five rows of heat exchange conduits in the square array, a smaller or larger number of conduit rows in this configuration may be utilized as appropriate.
- FIG. 7 illustrates still another variation of an enhanced crossflow heat transfer apparatus 510 according to this invention.
- each heat exchange conduit512 is associated with one or more lateral flow-constriction plates 520, 522, 524, 526, and 528 positioned alongside conduit 512 and oriented generally orthogonal to the direction of fluid flow, as indicated by arrows 530 and 532.
- the edges of the lateral plates 520, 522, 524, 526 and 528 closest to conduit 512 are spaced apart from the exterior walls of conduit 512 so as to create two fluid openings or channels between the plate edges and the conduit wall, one along each side of each conduit 512.
- the spacing between the plate edges and the conduit wall may be adjusted by routine experimentation to optimize the contouring of the fluid flow path to maximize heat transfer. Where two or more lateral flow-constriction plates are utilized for each conduit 512, the spacing between the plate edges and the conduit wall may be the same or different in order to optimally contour the fluid flow path.
- the lateral flow-constriction plates may be positioned alongside conduit 512 such that the plane of the plate passes through the centroid 518 of conduit 512 (such as plate 524), or else be positioned such that the planes of the plates intersect conduit 512 upstream (such as plates 520 and 526) of centroid 518, or downstream (such as plates 522 and 528) of centroid 518, or any combination thereof.
- the distance 542 between the aperture and the conduit centroid 518 may be less than one-half of the diameter 544 as shown, with a distance approaching zero as a limit, for example plate 524.
- lateral plate positioned alongside a heat exchange conduit is meant to refer to plates such as 520, 522, 524, 526 and 528 in Fig. 7 , oriented generally orthogonal to the direction of fluid flow, wherein the plane of the plate intersects any part of the heat exchange conduit.
- FIG. 8 illustrates another variation of an enhanced crossflow heat transfer apparatus610 according to this invention showing a variation of the apertured sleeve configuration shown in Fig. 2 .
- each heat exchange conduit 612 is partially surrounded by a pair of oppositely curved plates 620 generally conforming to the curvature of the outer wall of conduit 612 in a clam-shell configuration.
- Each curved plate 620 is joined to a wall or lateral plate 622 positioned generally orthogonal to the direction of fluid flow, as indicated by arrows 630 and 632.
- the pair of curved plates 620 around either side of a given conduit 612 do not touch each other and do not extend either upstream or downstream of the outer wall of conduit 612.
- a line or plane connecting the upstream or downstream edges of a pair of curved plates 620 would intersect conduit 612.
- the upstream and downstream openings between the pairs of curved plates 620 are the apertures through which the process fluid stream is directed to realize preferential contouring of the fluid stream.
- the distance 642 between the aperture and the conduit centroid 618 may be less than one-half of the diameter 644 as shown, with a distance approaching zero as a limit, for example, as the lengths of curved plates 620 approach zero leaving only lateral plate 622, a configuration corresponding to Fig. 7 with a single plate 524. This differs from the baffle structures shown in Figs.1 and 4 where the distance between the apertures and the conduit centroid is greater than one-half the diameter of the conduit.
- the clam-shell configuration of Fig. 8 with each pair of curved plates 620 around the sides of each conduit 612 differs from the slotted sleeve configuration of Fig. 2 in that in Fig. 8 a line or plane connecting the edges of the upstream and downstream fluid openings intersects the conduit 612, which is not the case for the slotted sleeves shown in Fig. 2A .
- the embodiment of Fig. 8 may be viewed as an extreme version of the embodiment of Fig. 7 wherein the individual lateral plates positioned alongside the heat exchange conduit are not spaced apart, as seen in Fig. 7 , but instead are positioned face to-face with one another such that their conduit-side edges form the curved plates 620 of Fig. 8 .
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Abstract
Description
- The present invention relates generally to methods and related apparatus for enhancing heat transfer to or from a fluid flowing cross-wise in contact with the outer thermally-conductive shells of a plurality of axially-oriented heat exchange conduits capable of acting as heat sources or heat sinks. By channeling cross-wise fluid flow, flowing generally orthogonal to the axes of the heat exchange conduits, and contouring it around the heat exchange conduits utilizing surrounding sleeve-like elements, a surprisingly more effective and efficient heat transfer between the flowing fluid and the thermally conductive surface is realized.
- It is well known to heat or cool process fluids, which may be liquids or gases, by flowing them into contact with a thermal-transfer surface that is maintained at a temperature which is different from that of the upstream process fluid thereby resulting in heat transfer either to or from the process fluid (depending on whether the thermal transfer surface is maintained at a higher or lower temperature than the fluid). In one familiar version of this technology, the thermal-transfer surface that acts as a heat source or heat sink is the exterior of a thermally-conductive shell of a thermal-transfer tube or pipe, for example, which is heated or cooled by means of a liquid flowing axially through the interior of the tube or pipe. In a variation of this technology, heat may be supplied directly inside a heat exchange conduit by means of flameless combustion of fuel gas (such as hydrogen or a hydrocarbon) as taught, for example, by
U.S. Patent Nos. 5,255,742 and5,404,952 . - It is also known in the art to flow a process fluid axially along a thermal-transfer surface, either concurrently or counter-currently relative to the direction of liquid flow inside the thermal-transfer tube, or to crossflow the process fluid relative to the axis of the thermal-transfer tube, or some combination of the two. Typical applications of heat transfer between cross-flowing fluid and heat exchanging conduits are found in air coolers, economizers associated with fired heaters or furnaces, and in shell and tube exchangers. Various types of so-called radial or axial/radial flow reactor designs are known for various applications whereby at least a part of a fluid process stream moves, at some point, through the reactor in a radial, cross-flow direction (i.e. inward-to-out or outward-to-in), as contrasted with the more familiar axial flow (i.e. end-to-end) reactor designs. Examples of reactor designs embodying at least in part a radial, crossflow of process fluid relative to a plurality of axially-disposed heat-transfer tubes are shown in
U. S. Patent Nos. 4,230,669 ;4,321,234 ;4,594,227 ;4,714,592 ;4,909,808 ;5,250,270 ; an5,585,074 . - Although cross-flow contact of a process fluid with a heat-transfer surface can be an attractive option for many applications, the utility of cross-flow contact for industrial applications has been limited by certain heat transfer inefficiencies which have been experienced in practice. Typically in cross-flow designs, a given portion of the process fluid is in contact with the heat-transfer surface for a shorter time than with a comparable axial flow design. In addition, the contact between the cross-flowing process fluid and the heat-transfer surface is uneven due to process fluid separation and recirculation. Short surface contact time, uneven contact, and limited fluid mixing can lead to inefficient, insufficient, and/or non-uniform thermal energy transfer.
- Thus, in an article entitled "Impingement heat transfer at a circular cylinder due to an offset of non-offset slot jet," appearing in Int. J. Heat Mass Transfer, Vol. 27, No. 12, pp. 2297-2306 (1984), the authors Sparrow and Alhomoud report experimental efforts to vary the heat transfer coefficients associated with crossflow of a process gas relative to a heat-transfer tube by positioning a slotted surface some distance upstream of the heat transfer tube to create a gas jet. Sparrow and Alhomoud varied the width of the jet inducing slot, the distance between the slot and the tube, the Reynolds number (degree of fluid turbulence), and whether the slot jet was aligned with or offset from the tube. The authors concluded that the heat transfer coefficient increased with slot width and Reynolds number, but decreased with slot-to-tube separation distance and offset.
- Because the Sparrow and Alhomoud study concluded that the heat transfer coefficient increased with slot width, the general utility of an upstream slot to increase heat transfer is at best ambiguous based on these results. It can only be concluded that, in the experimental design used by Sparrow and Alhomoud, a relatively wider slot led to a higher heat transfer coefficient than a relatively narrower slot, and no upstream slot at all might yield the highest value. No testing was performed utilizing a plurality of heat transfer tubes, or using upstream and downstream pairs, or around or alongside flow constriction means to preferentially contour crossflow fluid paths in contact with the outer surface of each of a plurality of heat-transfer tubes, and no reasonable extrapolations can be made to such very different alternative designs and configurations based on the extremely limited data presented.
- These and other drawbacks with and limitations of the prior art crossflow heat exchanged designs are overcome in whole or in part with the enhanced crossflow heat transfer methods and designs of this invention.
- The present invention provides fluid flow contouring apparatus having the features set out in claim 1 of the accompanying claims. A fluid flow contouring apparatus having the features defined in the preamble of claim 1 is disclosed for instance in
US 3616 849 . - The invention also provides a method for enhancing heat transfer to or from a fluid flowing cross-wise in contact with the outer surfaces of a plurality of heat exchange conduits, said method having the features set out in claim 13 of the accompanying claims.
- Other preferred features to which attention is directed are set out in the accompanying claims.
- In the above defined apparatus and method, the fluid flow constriction structure is a larger, generally concentric sleeve-like structure at least partially surrounding each conduit in an array of tubular heat exchange conduits, each such sleeve structure having apertures upstream and downstream of the centrally-located heat exchange tube. Apertured sleeves of this type at least partially surrounding individual heat exchange conduits in an array of such conduits have been found to enhance heat transfer by a factor of about five times or more.
- Embodiments of the invention may provide heat-transfer conduit arrays of varying sizes and configurations wherein each conduit of the array is associated with its own fluid flow-constriction means upstream, downstream and/or around or alongside of the conduit so as to preferentially contour the portion of the fluid stream flowing crosswise past the outside of the conduit to realize improved heat transfer. The apparatus is designed so as to substantially restrict the bypassing of fluid flow such that a predominant portion of the process fluid is forced to flow past the heat-transfer surface. The heat transfer surface will typically be one or a configured array of heat exchange conduits, oriented to have parallel axes disposed in an axial direction which is generally orthogonal to the direction of fluid flow, and having a thermally-conductive shell. The exterior surface of the shell of each such conduit is maintained at a temperature different from that of the upstream process fluid so that thermal energy is transferred to or from the process fluid by means of conduction, convection, radiation or some combination thereof, as the fluid flows past and contacts the exterior surfaces of the heat exchange conduits.
- The heat exchange conduits or ducts of this invention may broadly comprise tubes, pipes, or any other enclosures with heat sources or heat sinks. The exterior surfaces of the heat exchange conduits may be bare or, as discussed below, may be finned or any combination of the two. The cross-section of the conduits or ducts may be circular, elliptical, or any other closed shapes. Where a plurality of such heat exchange conduits are used, they will typically be arrayed in some predetermined configuration such as in a triangular array, a square array, a circular array, an annular array, or other such patterns depending on design choice and/or the requirements of a particular application. Relative to the direction of fluid flow, adjacent conduits may be aligned, staggered or otherwise positioned, again depending on design choice and/or application requirements.
- The size of the heat exchange conduits will be dictated, at least in part, by process requirements for the rate of heat transfer. In general, conduits having larger cross sections (for any given conduit geometry) will provide larger surface areas and therefore more heat transfer capacity. Fin elements, baffles or other heat-transfer enhancing structures may be provided on the outside surface of some or all of the heat exchange conduits to further increase surface area and improve heat transfer characteristics. A preferred embodiment utilizes closely spaced circumferential fins applied in a spiral along the exterior length of the conduit. This arrangement increases the heat-transfer surface area exposed to the crossflow without impeding the flow. It will be understood that the nature and flow rate of the process fluid, and the desired temperature change in the fluid between upstream of the heat exchange conduits and downstream of the conduits, will also affect these design choices.
- The apertures in the fluid flow constriction structure preferably comprise any combination of perforated holes or axial slots (i.e. elongated apertures having a longer axis generally parallel to the axial orientation of the heat exchange conduits). The holes or slots in different portions of the apparatus may be the same or differ in curvature, size and shape. The edges around the inlets and outlets may be straight, rounded, jagged, or some combination thereof.
- The fluid flow constriction structure is preferably positioned relative to an associated heat exchange conduit such that the distance between the centerline of an upstream or downstream aperture and the associated heat exchange conduit centroid ranges from about 0 to about 2.0, preferably from about 0.50 to about 1.00, times the outer diameter (or largest cross-sectional dimension of a non-circular conduit) of the conduit. In any case, the spacing between aperture and conduit must be sufficiently close to realize substantially enhanced heat transfer. The width (shortest side) of an elongated flow constriction aperture or the diameter of a generally circular hole constriction aperture may preferably range from about 0.02 to about 1.5, preferably from about 0.05 to about 0.25, times the outside diameter (or largest cross-sectional dimension of a noncircular conduit) of the conduit. The fluid flow constriction structure is preferably positioned relative to an associated heat exchange conduit such that the offset between the center of the aperture and the centroid of the heat exchange conduit ranges from 0 to 0.5, preferably 0, times the outside diameter (or largest cross-sectional dimension of a noncircular conduit) of the conduit.
- The enhanced crossflow heat exchange apparatus of this invention enhances heat transfer between the cross-flowing fluid and the plurality of heat exchange conduits by one or more of the following mechanisms:
- (a) increasing the fluid velocity around the heat exchange conduits;
- (b) preferentially directing the fluid to closely follow the outer surface of the heat exchange conduits;
- (c)restricting the fluid from flowing into or through areas that are distant from the outer surface of a heat exchange conduit;
- (d) reducing "dead" regions and flow recirculation around heat exchange conduits;
- (e) enhancing fluid turbulence; and(
- f) enhancing mixing between colder and hotter portions of the fluid.
- How the invention may be put into effect will now be described, by way of example only, with reference to the accompanying drawings, in which:
-
Fig.1 (reference) is a schematic top sectional view of a first embodiment of a crossflow heat exchange apparatus, with heat transfer enhancement according to the present invention, wherein a substantially circular array of axially-disposed heat exchange conduits is positioned inside a fluid flow-constricted annulus. -
Fig. 2A (invention) is a schematic plan view of a second embodiment of a crossflow heat exchange apparatus, with heat transfer enhancement according to the present invention, showing a substantially circular array of axially-disposed heat exchange conduits, each surrounded by a substantially concentric, fluid flow-constricted tubular sleeve, and also showing the several fluid flow-constricted sleeves joined together in a first ring-like structure. -
Fig. 2B is a side view of one conduit-sleeve combination illustrating a preferred staggered offset slot configuration. -
Fig. 3 (invention) illustrates a variation of the structure ofFig. 2 showing a double, concentric circular array of heat exchange conduits with radially adjacent conduits shown in alignment such that the fluid flow-restriction apertures of the respective flow-restricted sleeves associated with these radially aligned conduits are also in radial alignment. -
Fig. 4 (reference) is a schematic top sectional view of another embodiment of a crossflow heat exchange apparatus, with heat transfer enhancement according to the present invention, showing a double row of axially-disposed heat exchange conduits arranged in a substantially rectangular array with a first, upstream fluid flow-restricted baffle, a second, intermediate fluid flow-restricted baffle separating the first and second rows of conduits, and a third, downstream fluid flow-restricted baffle following the second row of conduits, with the corresponding apertures of the first, second and third baffles shown substantially in alignment with the respective conduits and with each other. -
Fig. 5 (invention) illustrates still another embodiment of an enhanced crossflow heat transfer apparatus according to this invention showing an array of multiple (i. e., three or more) rows of heat exchange conduits arranged in a triangular pitch and showing two alternative fluid flow paths through the array. -
Fig. 6 (invention) illustrates another embodiment of an enhanced crossflow heat transfer apparatus according to this invention showing an array of multiple (i.e.. three or more) rows of heat exchange conduits arranged in a square pitch and showing two alternative fluid flow paths through the array. -
Fig. 7 (invention) illustrates still another embodiment of an enhanced crossflow heat transfer apparatus according to this invention showing how one or a plurality of plates can be positioned alongside two sides of each heat exchange conduit to cause preferential contouring of a cross-flowing fluid stream to achieve enhanced heat transfer characteristics. -
Fig. 8 (invention) illustrates yet another embodiment of an enhanced crossflow heat transfer apparatus according to this invention showing an alternative type of sleeve structure formed by positioning curved plates having a contour corresponding to two sides of a conduit around two sides of each heat exchange conduit to cause preferential contouring of a cross-flowing fluid stream to achieve enhanced heat transfer characteristics. -
Fig.1 (reference) shows a crossflowheat exchange apparatus 10 according to this invention having a generally circular array of axially-disposedheat exchange conduits 12 distributed around the interior of anannular region 28 defined by an innercylindrical wall 20 and an outercylindrical wall 22, each having acommon centerpoint 14. As shown inFig. 1 ,conduits 12 are of substantially the same diameter, which is less than the radial width of the annular region, and spaced substantially equidistant from one another. - Associated with each
heat exchange conduit 12 is anupstream aperture 24 ininner wall 20 and adownstream aperture 26 inouter wall 22. As shown inFig.1 , respective pairs ofupstream apertures 24 anddownstream apertures 26 are substantially in radial alignment with the associatedconduit 12 and with each other. Thus, inFig. 1 , aprocess fluid 30 is flowed axially into the innercylindrical region 16 of theheat exchange apparatus 10 and then directed radially outward throughupstream apertures 24, flowing cross-wise into contact with theheat exchange conduits 12, as denoted by the fluid flow arrows inFig.1 , thereby heating or cooling the process stream to form a thermally conditionedfluid stream 32 which exitsannular region 28 throughdownstream apertures 26. - It will be understood that whereas
Fig.1 illustrates a radially-outward fluid flow path, the same apparatus could be utilized for thermally treating a process stream flowing radially inward to centerregion 16 and thereafter being axially withdrawn fromregion 16. In this variation,apertures 26 in theouter wall 22 would be the upstream apertures andapertures 24 ininner wall 20 would be the downstream apertures. -
Figs. 2A and2B show a particularly preferred crossflowheat exchange apparatus 110 according to this invention having a generally circular array of axially-disposedheat exchange conduits 112, each surrounded by anapertured sleeve 120 having either (i) anupstream aperture 124 and adownstream aperture 126 or (ii) offset aperture pairs 174,176 and 184.186 as described below. Theindividual sleeves 120 are joined together into a larger ring-like or cylindrical structure by connectingwalls 122.Apertures conduits 112. Alternatively, in a preferred embodiment also illustrated in one portion ofFig. 2A , aperture pairs 174, 176 and184, 186 are slightly offset from radial alignment in a staggered slot arrangement. The staggered slot arrangement for aperture pairs 174, 176 and 184, 186 is illustrated inFig. 2A , with additional detail inFig. 2B , where offset slot pairs 174, 176 and 184, 186 (replacing apertures pairs 124, 126) are staggered in elevation and offset slightly from the radial line fromcenterpoint 114 by equal angles 9.Fig. 2B shows a side view taken along theline 2B-2B inFig. 2A of aheat exchange conduit 112 having acylindrical sleeve 120 with the preferred staggered slot arrangement. The plan view of this staggered slot conduit/sleeve combination as shown inFig. 2A is taken along theline 2A-2A inFig. 2B . The ends of the slots from alternating offset slot pairs can be slightly overlapped or at equal elevation so there is no interruption of flow along the axial direction of the heat exchange apparatus. This design with separation and overlap of the offset slots also leaves connection regions between the axially overlapped portions of adjacent offset slots, indicated generally by thereference numeral 190 inFig. 2B , to provide thesleeves 120 with better circumferential mechanical integrity without blocking any fluid flow. For simplified illustration,Fig. 2A shows oneapertured sleeve 120 having the two-pair offset aperture configuration while the other sleeves have the one-pair aligned aperture configuration. In practice, however, all of the apertured sleeves for aparticular apparatus 110 will typically have the same aperture configuration. - Thus, in
Fig. 2A , aprocess fluid 130 is flowed axially into the innercylindrical region 116 having centerpoint 114 of theheat exchange apparatus 110 and then directed radially outward throughupstream apertures 124, flowing cross-wise into contact with theheat exchange conduits 112, as denoted by the fluid flow arrows inFig. 2A , thereby heating or cooling the process stream to form a thermally-conditionedfluid stream 132 which exits the interior regions defined by thesleeves 120 throughdownstream apertures 126. In the staggered slot embodiment, fluid flowing radially outward would either flow throughupstream aperture 174, into contact withconduit 112, and exit throughdownstream aperture 176, or, depending on the axial elevation, instead flow through aperture pair 184,186. It will be understood that whereasFig. 2A illustrates a radially outward fluid flow path, the same apparatus could be utilized for thermally treating a process stream flowing radially inward to centerregion 116 and thereafter being axially withdrawn fromregion 116. In this variation, apertures 126 (or 176 and 186) would be the upstream apertures, and apertures 124 (or 174 and 184) would be the downstream apertures. -
Fig. 3 shows a crossflowheat exchange apparatus 160 which is a variation of the crossflowheat exchange apparatus 110 shown inFig. 2 .Apparatus 160 differs fromapparatus 110 in the use of a double, concentric circular array of heat exchange conduits instead of the single circular array ofFig. 2 . As seen inFig. 3 , there is a second circular array ofheat exchange conduits 142, each in radial alignment with acorresponding conduit 112 of the first circular array. Eachconduit 142 is surrounded by anapertured sleeve 150 having anupstream aperture 164 and adownstream aperture 166.Apertures sleeve 150 associated with aparticular conduit 142 are shown substantially in radial alignment with theapertures sleeve 120 of the corresponding radiallyadjacent conduit 112. Theindividual sleeves 150 are joined together into a larger ring-like or cylindrical structure bywalls 152. AlthoughFig. 3 shows only asingle conduit 142 of the second circular array of heat exchange conduits, it will be understood that eachconduit 112 of the first circular array is associated with acorresponding conduit 142 of the second circular array. - Thus, in
Fig. 3 , a partially thermally-conditionedfluid stream 132 exiting firstdownstream apertures 126 insleeves 120 is directed radially outward through secondupstream apertures 164, flowing cross-wise into contact with the second array ofheat exchange conduits 142, thereby further heating or cooling the process stream to form a fully thermally-conditionedfluid stream 162 which exits the interior region defined by thesleeves 150 through seconddownstream apertures 166. It will be understood that whereasFig. 3 illustrates a radially-outward fluid flow path, the same apparatus could be utilized for thermally treating a process stream flowing radially inward to centerregion 116 and thereafter being axially withdrawn fromregion 116. In this variation,apertures apertures -
Fig. 4 (reference) shows a portion of another crossflowheat exchange apparatus 210 according to this invention. InFig. 4 a double row of axially-disposed heat exchange conduits, comprising a first upstream row ofconduits 212 and second downstream row ofconduits 216, are disposed in a generally rectangular array in conjunction with: a first, upstreamapertured plate 220 havingapertures 226; a second, intermediateapertured plate 222 havingapertures 228,plate 222 separating the first and second rows of conduits; and, a third, downstreamapertured plate 224 havingapertures 230. Each set ofapertures conduits downstream conduits - Thus, in
Fig. 4 , aprocess fluid 232 is directed, as denoted by the fluid flow arrows inFig. 4 , throughapertures 226 and flowed cross-wise into contact with first, upstreamheat exchange conduits 212, thereby partially heating or cooling the process stream to form a partially thermally-conditionedfluid stream 234.Stream 234 is then directed throughapertures 228 and flowed cross-wise into contact with second, downstreamheat exchange conduits 216 thereby further heating or cooling the process stream to form a fully thermally-conditionedfluid stream 236 which is flowed out of theapparatus 210 throughexit apertures 230. -
Fig. 5 illustrates two alternative possible fluid flow paths through a multi-row set ofheat exchange conduits 312 arranged in an offset or triangular array in accordance with another embodiment of a crossflowheat exchange apparatus 310 according to this invention. Thus, inFig. 5 , alternate rows of heat exchange conduits are offset from adjacent rows instead of having conduits in adjacent rows substantially in linear alignment as shown inFigs. 4 and6 . In this configuration, the centerpoints of three adjacent conduits in two adjacent rows form anequilateral triangle 340. Although not shown inFig. 5 , it is understood that the apparatus ofFig. 5 includes upstream and downstream apertured plates respectively located before the after the last row of conduits, as well as intermediate apertured plates separating adjacent rows of conduits. Alternatively, eachconduit 312 may be surrounded with an apertured sleeve-like structure as previously described for other figures. -
Fluid flow arrows 332 inFig. 5 illustrate a first possible fluid flow orientation which can be utilized with the triangular conduit array ofapparatus 310.Fluid flow arrows 334 inFig. 5 illustrate a second possible fluid flow orientation which can be utilized with the triangular conduit array ofapparatus 310. AlthoughFig. 5 shows four rows of heat exchange conduits in the triangular array, a smaller or larger number of conduit rows in this configuration may be utilized as appropriate. -
Fig. 6 illustrates two alternative possible fluid flow paths through a multi-row set ofheat exchange conduits 412 arranged in a square array in accordance with still another embodiment of a crossflowheat exchange apparatus 410 according to this invention. Thus, inFig. 6 ,conduits 412 in adjacent rows are substantially in linear alignment. In this configuration, the centerpoint of four adjacent conduits in two adjacent rows form a square 440. Although not shown inFig. 6 , it is understood that the apparatus ofFig. 6 includes upstream and downstream apertured plates respectively located before the first row of conduits and after the last row of conduits, as well as intermediate apertured plates separating adjacent rows of conduits. Alternatively, eachconduit 412 may be surrounded with an apertured sleeve as previously described. -
Fluid flow arrows 432 inFig. 6 illustrate a first possible fluid flow orientation which can be utilized with the square conduit array ofapparatus 410.Fluid flow arrows 434 inFig. 6 illustrate a second possible fluid flow orientation which can be utilized with the square conduit array ofapparatus 410. AlthoughFig. 6 shows five rows of heat exchange conduits in the square array, a smaller or larger number of conduit rows in this configuration may be utilized as appropriate. -
Fig. 7 illustrates still another variation of an enhanced crossflowheat transfer apparatus 510 according to this invention. InFig. 7 , each heat exchange conduit512 is associated with one or more lateral flow-constriction plates conduit 512 and oriented generally orthogonal to the direction of fluid flow, as indicated byarrows lateral plates conduit 512 are spaced apart from the exterior walls ofconduit 512 so as to create two fluid openings or channels between the plate edges and the conduit wall, one along each side of eachconduit 512. The spacing between the plate edges and the conduit wall may be adjusted by routine experimentation to optimize the contouring of the fluid flow path to maximize heat transfer. Where two or more lateral flow-constriction plates are utilized for eachconduit 512, the spacing between the plate edges and the conduit wall may be the same or different in order to optimally contour the fluid flow path. - As seen in
Fig. 7 , the lateral flow-constriction plates may be positioned alongsideconduit 512 such that the plane of the plate passes through thecentroid 518 of conduit 512 (such as plate 524), or else be positioned such that the planes of the plates intersectconduit 512 upstream (such asplates 520 and 526) ofcentroid 518, or downstream (such asplates 522 and 528) ofcentroid 518, or any combination thereof. Thedistance 542 between the aperture and theconduit centroid 518 may be less than one-half of thediameter 544 as shown, with a distance approaching zero as a limit, forexample plate 524. This differs from the baffle structures shown inFigs.1 and4 where the distance between the apertures and the conduit centroid is greater than one-half the diameter of the conduit. As used herein, the phrase "lateral plate positioned alongside a heat exchange conduit" is meant to refer to plates such as 520, 522, 524, 526 and 528 inFig. 7 , oriented generally orthogonal to the direction of fluid flow, wherein the plane of the plate intersects any part of the heat exchange conduit. -
Fig. 8 illustrates another variation of an enhanced crossflow heat transfer apparatus610 according to this invention showing a variation of the apertured sleeve configuration shown inFig. 2 . InFig. 8 , eachheat exchange conduit 612 is partially surrounded by a pair of oppositelycurved plates 620 generally conforming to the curvature of the outer wall ofconduit 612 in a clam-shell configuration. Eachcurved plate 620 is joined to a wall orlateral plate 622 positioned generally orthogonal to the direction of fluid flow, as indicated byarrows - The pair of
curved plates 620 around either side of a givenconduit 612 do not touch each other and do not extend either upstream or downstream of the outer wall ofconduit 612. Thus, as shown for illustration purposes inFig. 8 , a line or plane connecting the upstream or downstream edges of a pair ofcurved plates 620 would intersectconduit 612. The upstream and downstream openings between the pairs ofcurved plates 620 are the apertures through which the process fluid stream is directed to realize preferential contouring of the fluid stream. Thedistance 642 between the aperture and theconduit centroid 618 may be less than one-half of thediameter 644 as shown, with a distance approaching zero as a limit, for example, as the lengths ofcurved plates 620 approach zero leaving onlylateral plate 622, a configuration corresponding toFig. 7 with asingle plate 524. This differs from the baffle structures shown inFigs.1 and4 where the distance between the apertures and the conduit centroid is greater than one-half the diameter of the conduit. - The clam-shell configuration of
Fig. 8 with each pair ofcurved plates 620 around the sides of eachconduit 612, differs from the slotted sleeve configuration ofFig. 2 in that inFig. 8 a line or plane connecting the edges of the upstream and downstream fluid openings intersects theconduit 612, which is not the case for the slotted sleeves shown inFig. 2A . In a sense, the embodiment ofFig. 8 may be viewed as an extreme version of the embodiment ofFig. 7 wherein the individual lateral plates positioned alongside the heat exchange conduit are not spaced apart, as seen inFig. 7 , but instead are positioned face to-face with one another such that their conduit-side edges form thecurved plates 620 ofFig. 8 . - It will be apparent to those skilled in the art that other changes and modifications may be made in the above-described apparatus and methods for enhancing crossflow heat transfer without departing from the scope of the invention herein, and it is intended that all matter contained in the above description shall be interpreted in an illustrative and not a limiting sense.
Claims (22)
- Fluid flow contouring apparatus for preferentially contouring the fluid path of a process fluid (130) flowing cross-wise across and contacting a plurality of spaced-apart heat transfer conduits (112), said apparatus comprising a plurality of longitudinally continuous, sleeve-shaped baffle structures (120), each baffle structure comprising at least a paired set of fluid flow apertures (124, 126) which constitute the only upstream-to-downstream fluid passage through the fluid flow contouring apparatus, characterised by each of said baffle structures (120) substantially symmetrically surrounding a heat transfer conduit (112) to define an annular-shaped fluid flow region thereby isolating cross-wise fluid flow around that associated heat transfer conduit from cross-wise fluid flow around adjacent heat transfer conduits located transversely to the direction of fluid flow, and wherein the fluid flow apertures (124, 126) of a baffle structure are symmetrically located respectively upstream and downstream of the associated heat transfer conduit (112) in at least partial upstream and downstream alignment with each other and with the associated heat transfer conduit, whereby each said baffle structure (120) contours the flow path of said process fluid around the contour of the associated heat transfer conduit.
- The apparatus of claim 1, wherein at least two of said baffle structures (120) are interconnected (122) into a larger flow contouring apparatus for contouring fluid flow around a plurality of heat transfer conduits (112).
- The apparatus of claim 2, wherein said heat transfer conduits (112) are arranged in a generally circular array and further wherein the individual baffle structures (120) associated with the heat transfer conduits are interconnected to form a larger, cylindrical-shaped flow contouring apparatus (110).
- The apparatus of any of claims 1, 2 or 3, wherein pairs of fluid flow apertures (124, 126) comprise radially-aligned upstream and downstream apertures in the individual baffle structures.
- The apparatus of any of claims 1, 2 or 3, wherein pairs of fluid flow apertures comprise upstream and downstream apertures (176, 186) in the individual baffle structures which are offset from the radial line.
- The apparatus of claim 1, wherein said heat transfer conduits (112) comprise at least one generally circular array of axially aligned cylindrical heat transfer conduits, at least some of which are substantially surrounded by a substantially concentric apertured sleeve-shaped structure having upstream and downstream aperture pairs (184, 176; 174, 186) in columns parallel to the axis of the associated conduit, further wherein a sleeve-shaped structure (120) is secured by a plate member (122) to an adjacent sleeve-shaped structure to form a larger cylindrical structure.
- The apparatus of claim 6, wherein the aperture pairs comprise elongated slots (184, 176; 174, 186), each slot having a long axis generally parallel to the axes of the heat transfer conduits.
- The apparatus of claim 7, wherein a heat transfer conduit is associated with two pairs of elongated slots (184, 176; 174, 186), each slot pair being offset (θ) from radial alignment with the axis (114) of the larger cylindrical structure.
- The apparatus of claim 6 or 7, wherein said heat transfer conduits comprise at least two generally circular arrays of cylindrical heat transfer conduits (112, 142) oriented to have parallel axes, one array being concentric relative to the other.
- The apparatus of claim 9, wherein the baffle structures (120, 150) of adjacent pairs of radially-aligned heat transfer conduits (112, 142) are interconnected such that an aperture (164) between the baffle structures serves as the downstream fluid flow aperture for one of the conduits and the upstream fluid flow aperture for the other.
- The apparatus of any of claims 1, 2 or 3, wherein the baffle structure associated with a heat transfer conduit (216) comprises a set of substantially flat plate members (220, 222, 224) positioned in pairs edgewise alongside two sides of a heat transfer surface in proximity to without touching the surface, the planes of said plate members being oriented generally orthogonal to the fluid path of the process fluid (232, 234, 236), so as to define generally annular-shaped fluid flow regions having upstream and downstream aperture pairs around said heat transfer conduits.
- The apparatus of any of claims 1, 2 or 3, wherein the baffle structure associated with a heat transfer conduit comprises contoured plate members (620) positioned in pairs alongside two sides of the heat transfer conduit (612) in proximity to without touching the surface of the conduit, said plate members having a contour corresponding respectively to the two sides of the heat transfer conduit so as to define generally annular-shaped fluid flow regions having upstream and downstream openings around said heat transfer conduits, said plate members being joined (622) to other plate members associated with adjacent heat transfer conduits.
- A method for enhancing heat transfer to or from a fluid (130) flowing cross-wise in contact with the outer surfaces of a plurality of heat exchange conduits (112) comprising the step of preferentially contouring cross-wise fluid flow across the heat exchange conduits by flowing the fluid through at least a paired set of fluid flow constrictors (124, 126) in a longitudinally continuous, sleeve-shaped baffle structure (120) associated with a heat exchange conduit, said baffle structure being part of an array of such baffle structures, characterised by each baffle structure substantially symmetrically surrounds its associated heat exchange conduit to isolate cross-wise fluid flow around that associated heat exchange conduit from cross-wise fluid flow around adjacent heat exchange conduits located transversely to the direction of fluid flow, wherein the fluid flow constrictors (124, 126) of each baffle structure constitute the only upstream-to-downstream fluid passage through the baffle structure array and are symmetrically located respectively upstream and downstream of the associated heat exchange surface in at least partial upstream and downstream alignment with each other and with the associated heat exchange conduit (112), and whereby each baffle structure contours the flow path of said fluid around the contour of the associated heat exchange conduit.
- The method of claim 13, wherein at least two of said baffle structures (120) are interconnected into a larger flow contouring apparatus (122) for contouring fluid flow around a plurality of heat exchange conduits (112).
- The method of claim 13, wherein said heat exchange conduits (112) comprise at least one generally circular array of axially aligned cylindrical heat exchange conduits, at least some of which are substantially surrounded by a substantially concentric apertured sleeve-shaped structure having upstream and downstream aperture pairs (184, 176; 174, 186) in columns parallel to the axis of the associated conduit, further wherein a sleeve-shaped structure (120) is secured by a plate member (122) to an adjacent sleeve-shaped structure to form a larger cylindrical structure.
- The method of claim 15, wherein the aperture pairs (184, 176; 174, 186) comprise elongated slots, each slot having a long axis generally parallel to the axes of the heat exchange conduits.
- The method of claim 16, wherein a heat exchange conduit is associated with two pairs of elongated slots (184, 176; 174, 186), each slot pair being offset (θ) from radial alignment with the axis of the larger cylindrical structure.
- The method of claim 15 or 16, wherein said heat exchange conduits comprise at least two generally circular arrays of cylindrical heat exchange conduits (112, 142) oriented to have parallel axes, one array being concentric relative to the other.
- The method of claim 18 wherein the baffle structures (120, 150) of adjacent pairs of radially-aligned heat exchange conduits (112, 142) are interconnected such that an aperture (164) between the baffle structures serves as the downstream fluid flow constrictor for one of the conduits and the upstream fluid flow constrictor for the other.
- The method of claim 13 or 14, wherein the baffle structure associated with a heat exchange conduit (216) comprises a set of substantially flat plate members (220, 222, 224) positioned in pairs edgewise alongside two sides of a heat exchange conduit in proximity to without touching the surface, the planes of said plate members being oriented generally orthogonal to the fluid path of the process fluid (232, 234, 236), so as to define generally annular-shaped fluid flow regions having upstream and downstream aperture pairs around said heat exchange conduits.
- The method of claim 13 or 14, wherein the baffle structure associated with a heat exchange conduit comprises contoured plate members (620) positioned in pairs alongside two sides of the heat exchange conduit (612) in proximity to without touching the surface, said plate members having a contour corresponding respectively to the two sides of the heat exchange conduit so as to define generally annular-shaped fluid flow regions having upstream and downstream openings around said heat exchange conduits, said plate members being joined (622) to other plate members associated with adjacent heat exchange conduits.
- A heat exchanger comprising the fluid flow contouring apparatus of any of claims 1-12.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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US14494899P | 1999-07-21 | 1999-07-21 | |
US144948P | 1999-07-21 | ||
PCT/US2000/040401 WO2001007857A1 (en) | 1999-07-21 | 2000-07-18 | Enhanced crossflow heat transfer |
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EP1203195A1 EP1203195A1 (en) | 2002-05-08 |
EP1203195A4 EP1203195A4 (en) | 2005-09-28 |
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EP00958015A Expired - Lifetime EP1203195B1 (en) | 1999-07-21 | 2000-07-18 | Enhanced crossflow heat transfer |
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EP (1) | EP1203195B1 (en) |
JP (1) | JP2003509650A (en) |
KR (1) | KR100768763B1 (en) |
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JP5612749B1 (en) * | 2013-10-25 | 2014-10-22 | 増山 征男 | Gas cooling device |
FR3048769B1 (en) | 2016-03-14 | 2019-05-17 | Commissariat A L'energie Atomique Et Aux Energies Alternatives | PROCESS FOR MANUFACTURING AT LEAST ONE PLATE HEAT EXCHANGER BY PLATE SUPERPOSITION WITH ALIGNMENT PATTERNS |
CN106247824A (en) * | 2016-07-29 | 2016-12-21 | 太仓英达锅炉设备有限公司 | A kind of heat-exchanger rig and combinations thereof heat exchanger fin |
JP6950921B2 (en) * | 2017-03-09 | 2021-10-13 | 株式会社サムソン | Boiler with water supply preheating device |
CN107008206A (en) * | 2017-06-12 | 2017-08-04 | 上海理工大学 | A kind of heat pipe-type gas hydrate quickly generates device |
CN107726905A (en) * | 2017-09-27 | 2018-02-23 | 北京工业大学 | Horizontal-type high temperature storage heating equipment and application method |
JP2020051671A (en) * | 2018-09-26 | 2020-04-02 | 株式会社ノーリツ | Water heater |
CN112122616A (en) * | 2020-08-24 | 2020-12-25 | 武汉汉维新材料科技有限责任公司 | Directional microchannel and disordered hole composite heat sink and preparation method thereof |
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FR436949A (en) | ||||
GB550145A (en) * | 1941-07-29 | 1942-12-24 | Briggs & Co Ltd S | Improved construction of apparatus for heating liquids |
US3616849A (en) * | 1970-02-24 | 1971-11-02 | Johannes C Dijt | Heat exchange means |
US3908628A (en) * | 1973-10-16 | 1975-09-30 | Thermo Electron Corp | Jet impingement recuperator |
FR2340524A1 (en) * | 1976-02-09 | 1977-09-02 | Commissariat Energie Atomique | Shell-and-tube heat exchanger partic. for evapn. - has partitions defining inlet, reheat, evapn. and distribution spaces and flow-directing tubes |
US4284133A (en) * | 1979-09-19 | 1981-08-18 | Dunham-Bush, Inc. | Concentric tube heat exchange assembly with improved internal fin structure |
JPS5915796A (en) | 1982-07-20 | 1984-01-26 | Ishikawajima Harima Heavy Ind Co Ltd | Multi-tubular heat exchanger |
JPS5959242A (en) * | 1982-09-28 | 1984-04-05 | Toyo Eng Corp | Reaction method and reactor therefor |
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2000
- 2000-07-18 WO PCT/US2000/040401 patent/WO2001007857A1/en active Application Filing
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- 2000-07-18 DE DE60043227T patent/DE60043227D1/en not_active Expired - Lifetime
- 2000-07-18 PT PT00958015T patent/PT1203195E/en unknown
- 2000-07-18 ES ES00958015T patent/ES2331405T3/en not_active Expired - Lifetime
- 2000-07-18 EP EP00958015A patent/EP1203195B1/en not_active Expired - Lifetime
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- 2000-07-18 AU AU69550/00A patent/AU6955000A/en not_active Abandoned
- 2000-07-18 JP JP2001512242A patent/JP2003509650A/en active Pending
- 2000-07-18 MX MXPA02000709A patent/MXPA02000709A/en active IP Right Grant
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CZ2002250A3 (en) | 2002-09-11 |
MXPA02000709A (en) | 2003-01-28 |
BR0012680B1 (en) | 2008-11-18 |
DE60043227D1 (en) | 2009-12-10 |
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KR100768763B1 (en) | 2007-10-19 |
JP2003509650A (en) | 2003-03-11 |
TW512219B (en) | 2002-12-01 |
CA2379283A1 (en) | 2001-02-01 |
AU6955000A (en) | 2001-02-13 |
ATE447154T1 (en) | 2009-11-15 |
CN1292221C (en) | 2006-12-27 |
WO2001007857A1 (en) | 2001-02-01 |
BR0012680A (en) | 2002-10-22 |
KR20020073327A (en) | 2002-09-23 |
CN1361856A (en) | 2002-07-31 |
EP1203195A4 (en) | 2005-09-28 |
CA2379283C (en) | 2009-02-03 |
ES2331405T3 (en) | 2010-01-04 |
WO2001007857A8 (en) | 2001-09-13 |
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