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
  • F28F9/013—Auxiliary supports for elements for tubes or tube-assemblies
  • F28F9/0131—Auxiliary supports for elements for tubes or tube-assemblies formed by plates
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F1/00—Tubular elements; Assemblies of tubular elements
  • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
  • F28F1/12—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element
  • F28F1/24—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending transversely
  • F28F1/32—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending transversely the means having portions engaging further tubular elements
  • F28F1/325—Fins with openings

Definitions

• the present invention relates to a heat exchanger provided with a housing having a core, comprising a series of plate-shaped fins placed at least almost parallel to each other, in which each fin is provided with pipe openings, and a bundle of pipes for passing a first heat exchange medium, in which each of the pipes extends through respective pipe openings of respective fins, in which the housing is provided with an inlet and an outlet for passing a second heat exchange medium through the housing.
• Such a heat exchanger is known from Dutch patent application 9500633.
• the efficiency of the heat exchanger may not be optimal depending on the second heat exchange medium.
• the heat exchanger is used as oil cooler, so in cases in which the second heat exchange medium is oil, the oil can supposedly "freeze to" the plate-shaped fins and the pipes, which have a lower temperature than the oil.
• oil flowing between the fins and pipes does not optimally contact the fins and the pipes because a layer of oil is "frozen” on them.
• the degree of "freezing” strongly depends on the kind of second heat exchange medium, but causes a blockage for the second heat exchange medium, which leads to a high drop in pressure and a low heat exchange.
• a heat exchanger with which an improved efficiency of the heat exchange can be obtained. It is noted here that a heat exchanger is not only suitable to be used as oil cooler for for instance generators, motors and the like, but that the heat exchanger may for instance also be used for indeed heating the second heat exchange medium.
• a heat exchanger of the kind described above according to the present invention is characterized in that at least one of the fins is further provided with mix openings. Because the second heat exchange medium during use flows past the mix openings, said flow in comparison to the flow over the locations of the fins where no mix openings have been arranged, is disturbed such that the flow can reach the plate-shaped fins and the pipes, thus improving the efficiency of the heat exchanger. So although the arranging of mix openings reduces the effective surface of the fins, and therefore a lower efficiency would be expected, it appears that the efficiency is indeed improved.
• the pipe openings are situated in rows next to each other.
• each of the mix openings are situated between respective adjacent pipe openings.
• the mix openings may have different shapes, but depending on the second heat exchange medium it is preferred that the mix openings are semicircular, circular or oval.
• Preferably around a mix opening the respective plate-shaped fin is provided with a torsion.
• the torsion is such that a flow of second heat exchange medium is directed at a pipe and to a plate-shaped fin, respectively. As a result it is ensured that the "frozen" layer of second heat exchange medium on the pipe and the fins is accurately broken through.
• a further disturbance of the flow which benefits the efficiency, is provided because at least one of the fins is further provided with local elevations.
• at least one of the elevations is provided with a groove, which is able to give a certain direction to the disturbance. Said direction may be adjusted depending on the wanted effect and the second heat exchange medium.
• the thread is located near the circumferential edge of the respective fins.
• a strip has been arranged between the core and the housing.
• the strip is made of springy material. Because of the strip the leakage length of the second heat exchange medium is increased. Moreover the strip may be of such a shape that the path the second heat exchange medium has to traverse is complicated, so that the leakage resistance is increased. Said strip also gives plate-shaped fins without mix openings a good leakage reduction. This is contrary to Dutch patent ap- plication 9500633, in which between the housing and the core a sleeve is arranged.
• Figure 1 schematically shows a longitudinal cross-section of a heat exchanger according to the invention
• Figure 2 schematically shows a top view of a part of a fin according to the present invention, to be used in a heat exchanger according to the present invention
• Figure 3 and 4 schematically show the torsion of a fin around respective mix openings
• Figures 5A and 5B schematically show alternative embodiments of a local elevation in a fin in cross-section
• Figure 6 and 7 show a cross-section and a view, respectively, of a strip for reducing leakage between housing and core.
• the heat exchanger 1 as shown in the drawing comprises a substantially cylindrical housing 2 having a core 3 accommodated in there. At the top side near a first end 4, the housing 2 has an inlet 5 and at the opposite side 6 an outlet 7.
• the inlet 5 and the outlet 7 can be connected to a supply and return lead for a second heat exchange medium, for instance oil to be cooled.
• a second heat exchange medium for instance oil to be cooled.
• the inlet and the outlet may for that matter also be differently positioned and several inlets and/or outlets may be arranged.
• the core 3 comprises a bundle of pipes 8 extending almost parallel to each other and in longitudinal direction of the housing 2.
• an end plate 9 On both ends of the core 3 an end plate 9 has been arranged which can fittingly be accommodated in or against the housing 2.
• the pipes 8 extend through the end plates, as a result of which the ends of the pipes are open and may be connected to a supply and discharge, respectively, of a first heat exchange medium, for instance water or another cooling fluid.
• a large number of fins 1 0 have been arranged which extend almost parallel to the end plates and to each other, through which fins the pipes extend.
• the fins 1 0 therefore extend almost at right angles to the longitudinal direction of the pipes 8 and are placed at a little distance from each other.
• the fins 10 and the pipes 8 contact each other closely, for instance because the pipes 8 are somewhat flared within the fins 1 0, as a result of which good heat conductance between the fins 1 0 and the pipes 8 is guaranteed.
• the fins 1 0 and the pipes 8 may of course for that matter also be connected one to the other in a conducting manner in other ways.
• the fins 1 0 are all almost identical and are made of relatively thin plate.
• Each fin 10 has an almost circular cross-section with flattened top side 1 1 and a bottom side 1 2. Over the surface a number of holes 1 3 corresponding to the number of pipes has been arranged in a regular distribution, through which holes the pipes 8 can be arranged. For simple assembly the holes 1 3 are a little larger that the cross-section of the pipes 8 in the outlet shape.
• a strip 14 Around the core and between the end plates 9 a strip 14 (see figures 6 and 7) has been arranged.
• the strip 14 increases the leakage resistance for oil, so that a considerable reduction of oil leakage arises.
• the strip 14 is made of springy material so that a good fitting is realised.
• a good fitting in a certain housing may also be obtained by correct dimensioning of the strip.
• the reduction of leakage is also obtained with plate- shaped fins without mix openings.
• leakage resistance may further be increased.
• FIG. 2 schematically shows a top view of a part of a fin 1 0 according to the present invention, to be used in a heat exchanger according to the present invention.
• the fin 10 is further provided with mix openings 20. Because the second heat exchange medium, for instance oil, during use flows past the mix openings 20, said flow in comparison with the flow over places of the fin 10 where no mix openings 20 have been arranged, will be disturbed such that the flow can reach the pipes 8 or the adjacent fins, thus improving the efficiency of the heat exchanger.
• the second heat exchange medium for instance oil
• the mix openings 20 can be arranged on various places on the fin 1 0, it is preferred that the mix openings 20 are placed there where a rate of flow of the second heat exchange medium is high in comparison to the rate of flow on other locations. The highest rate of flow appears to be present between two adjacent pipes, so that preferably each of the mix openings 20 is situated between respective adjacent pipe openings 1 3, as shown in figure 2.
• centres 30, 31 of two adjacent pipe openings 1 3 may be connected by an imaginary connecting line 32.
• mix openings are substantially circular, other shapes may be suitable depending on the kind of second heat exchange medium. Semi-circular and oval mix openings should particularly be kept in mind here.
• the respective plate-shaped fin 10 is provided with a torsion. Because of such a torsion the flow of the second heat exchange medium is further disturbed as a result of which the efficiency of the heat exchange is further improved. Although any given disturbance will result in improvements, excellent results can be obtained when the torsion is such that a flow of second heat exchange medium is directed to a pipe 8 or an adjacent plate-shaped fin.
• An attempt to show said torsion in a drawing, is made in figures 3 and 4.
• a channel through the area between the pipe openings 1 3 is indicated, through which channel the flow takes place.
• the triangular area 22 (figure 2) indicates a local bulge as a result from the torsion which causes further efficiency- improving disturbance of the flow.
• the fin 10 may be provided with local elevations 23, 23' (see figure 2, and figures 5A and 5B).
• the elevation 23, 23' is provided with a groove 24, 24' which can give a certain direction to the disturbance. Said direction can be adjusted depending on the wanted effect and the second heat exchange medium.
• the direc- tion is approximately 45 ° with respect to the general flow direction, indicated by arrow S.
• the distance between the fins is several mm. Reducing said distance is not possible there, because as a result larger laminar flow between the fins is generated, which would lower the efficiency, because of the fact that said laminar flow would even be less capable to contact the pipes in a heat exchanging manner.
• this distance it is possible, however, to reduce this distance in a range of 0.5 mm to 2.0 mm, for instance 0.6 mm, 0.8 mm or 1 .1 mm, which in practice is easy to realize. As a result the number of fins per cm is considerably increased which enlarges the heat exchanging capacity considerably.
• a heat exchanger according to the present invention was capable to efficiently cool down oil of a temperature of 90° with cooling water of 20°C.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Geometry (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Power Steering Mechanism (AREA)
• Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
• Separation By Low-Temperature Treatments (AREA)

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Citations (7)

• 1999
  • 1999-05-11 NL NL1012029A patent/NL1012029C2/nl not_active IP Right Cessation
• 2000
  • 2000-05-03 AT AT00927950T patent/ATE310222T1/de not_active IP Right Cessation
  • 2000-05-03 DE DE60024078T patent/DE60024078T2/de not_active Expired - Lifetime
  • 2000-05-03 DK DK00927950T patent/DK1180232T3/da active
  • 2000-05-03 AU AU46253/00A patent/AU4625300A/en not_active Abandoned
  • 2000-05-03 WO PCT/NL2000/000288 patent/WO2000068629A1/en active IP Right Grant
  • 2000-05-03 EP EP00927950A patent/EP1180232B1/en not_active Expired - Lifetime
• 2001
  • 2001-11-08 US US10/010,445 patent/US20020046829A1/en not_active Abandoned

Patent Citations (7)

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