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
  • F28F9/02—Header boxes; End plates
  • F28F9/026—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits
  • F28F9/0265—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits by using guiding means or impingement means inside the header box
• • 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

Definitions

• the present invention relates to a plate heat exchanger.
• such an exchanger is composed of superimposed plates which, after brazing, welding or clamping, form two series of circulation channels, allowing respectively the flow of first and second fluids, which can be in the single-phase or two-phase state , at their entrance.
• the first fluid is for example a refrigerating fluid
• the second fluid can be a fluid to be cooled or to be heated.
• Mechanical means are also provided for making these two series of channels independent, so that the two aforementioned fluids do not come into mutual contact.
• a plate exchanger also includes first and second inlet manifolds, placed in communication with respective pipes for supplying each fluid.
• Each input collector supplies power to a corresponding series of channels. Downstream of the channels are provided outlet collectors, each of which is in communication with an outlet pipe allowing the evacuation of a corresponding fluid.
• the plate heat exchangers mentioned above have certain drawbacks. In fact, their performance increases in a roughly linear fashion with the number of plates which equip them, up to a threshold value which is between approximately 40 and 100 plates. Beyond this threshold value, which depends in particular on the nature of the fluids and their flow rate, the performance of the exchanger tends to stagnate or even decrease as the total number of plates is increased . Furthermore, the pressure drops occurring at these heat exchangers are relatively high. The phenomena described above are detrimental, in the sense that the exchanger is limited in its performance.
• the invention proposes to produce a plate heat exchanger whose performance is improved compared to the prior art, and in particular continues to increase beyond the threshold value of plates, which is mentioned above.
• the invention also proposes to produce such an exchanger, whose design is simple and whose associated pressure drops are reduced compared to the prior art.
• a plate heat exchanger comprising several plates, housed in the interior volume of the exchanger and defining first and second series of independent circulation channels, respectively for the circulation of first and second fluids.
• said exchanger further comprising first and second inlet manifolds, extending respectively upstream of the first and second channels, with reference to the flow of each fluid, as well as first and second outlet manifolds, extending downstream of said first and second channels, characterized in that at least one of the first and second outlet manifolds is provided with an attached member arranged in the internal volume of the collector, this added member extending from a bottom of the or each collector, and making it possible to reduce the cross-section substantially continuously passage of or each fluid in the or each outlet manifold, towards the bottom of this manifold.
• FIG. 1 is a partial sectional view of a plate heat exchanger according to l invention
• Figures 2 and 3 are views in partial section, illustrating the outlet manifold of the exchanger of Figure 1, provided with two alternative embodiments of an attached member allowing the reduction of the cross section of the fluid in this manifold.
• the plate heat exchanger illustrated in FIG. 1, which is generally designated by the reference 2, contains several plates 6 extending in parallel, so as to define first 8 and second 10 series of channels, arranged alternately.
• means are provided for preventing communication between two adjacent channels 8, 10. These means, which can for example be produced by stamping, then brazing or adding a joint, are shown schematically, for the sake of clarity, by dividing lines 12.
• the exchanger 2 also comprises a connection fitting 14 for a first fluid, which is for example a cooling fluid, intended to flow in the first channels 8.
• This fitting 14 is provided with a peripheral shoulder 16, against which abuts a tube 18 allowing the supply of this coolant.
• the inlet connector 14 opens into an inlet collection zone, or inlet manifold 20. The latter, which extends longitudinally in the direction of flow of the coolant, is thus disposed opposite of all the channels 8, 10, upstream of the latter in the direction of flow of the coolant.
• the channels 8 are placed in communication, opposite the inlet manifold 20, with an outlet collection zone, or outlet manifold 22.
• the latter which extends longitudinally in the direction of flow of the fluid, is arranged opposite the channels 8, 10, downstream of these, symmetrically with the inlet manifold 20.
• the outlet manifold 22 is placed in communication with a discharge connection 24, or outlet, of the refrigerant.
• This connector 24 is provided with a peripheral shoulder 26, against which abuts a tube 28 allowing the evacuation of the refrigerant.
• the exchanger 2 also comprises, in a known manner, connections for supplying and discharging a second fluid, which is for example a fluid to be cooled, as well as inlet and outlet manifolds for this fluid, arranged on either side of the circulation channels 10.
• a second fluid which is for example a fluid to be cooled
• inlet and outlet manifolds for this fluid arranged on either side of the circulation channels 10.
• An attached member which is a conical body 30, is housed in the interior volume of the outlet manifold 22.
• the main axis of this cone coincides with the median longitudinal axis A of the outlet manifold 22, while its base 32 is fixed, for example by brazing, on the bottom wall 34 of one exchanger 2, opposite the inlet fittings 14 and discharge 24 of the first fluid.
• the tip 36 of this cone 30 extends to the outlet of the downstream channel 8 ', adjacent to both the fittings 14 and 24.
• the transverse dimensions of the outlet manifold 22 are substantially constant. They are defined by the side wall 38, as well as by the outlets of all of the channels 8. Furthermore, the transverse dimensions of the cone 30 increase continuously in the direction of the bottom wall 34, namely opposite of the discharge connection 24, which corresponds upstream, with reference to the flow of the coolant in the outlet manifold 22.
• the cross section of the coolant which corresponds to the difference between the total cross section of the outlet manifold 22 and the cross section of the cone 30, therefore decreases continuously upstream, i.e. the bottom 34 of the collector.
• the fluid passage section, at the outlet of the upstream channel 8 ", adjacent to the bottom wall 34, is between 1 and 50%, preferably between 5 and 25%, of the total cross section of the outlet manifold 22.
• FIG. 2 illustrates a variant of the invention, in which the added member is a cone 80 whose longitudinal dimension, or length, is less than that of the cone 30 of the previous figure.
• This cone 80 extends over a length 1, equal to approximately 50% of the length L, or longitudinal dimension of the outlet manifold 22, corresponding to the distance separating the outlet of the downstream channel 8 'and the bottom wall 34.
• the cone 80 therefore extends only in the upstream region 40 of the outlet manifold 22, with reference to the flow of the fluid.
• the tip 86 of the cone is integral with a longitudinal rod 88 terminated by transverse wires 90 interposed between the tube 28 and the shoulder 26.
• the base 82 of the cone is then pressed against the bottom wall 34 and does not need to be brazed there.
• the means for reducing the cross section of the fluid are no longer formed by a cone, but by a member 130, the side walls 131 of which do not have a rectilinear profile, in axial section. These walls 131 have a concavity facing the median longitudinal axis A of the outlet manifold 22.
• the base 132 of this added member 130 is pressed against the bottom 34, while its tip 136 is integral with a rod 138 extended by wires 140, similar to those 88 and 90 in FIG. 2.
• the invention is not limited to the examples described and shown. Thus, provision can be made to have an insert member similar to those 30, 80 and 130, in the outlet manifold of the second fluid.
• Such an attached member can therefore equip the outlet manifold of the first fluid and / or the outlet manifold of the second fluid.
• the insert arranged in the interior volume of the collector, can be offset, in the sense that its main axis is distinct from that of the collector considered. Furthermore, this added member may have a roughly conical shape, in the sense that it is constituted by a deformed cone.
• the invention makes it possible to achieve the objectives mentioned above.
• the Applicant has found that the stagnation, or even the decrease in performance of a plate heat exchanger, occurring beyond a threshold value of plates, is in particular linked to a poor distribution of the fluid in the channels of circulation.
• This poor distribution implies in particular that the flow rate of fluid flowing in the channel adjacent to the supply and discharge connections is significantly higher than that of the fluid flowing in the opposite channel, adjacent to the bottom plate of the exchanger.
• this unsatisfactory distribution is linked to the fact that, towards the bottom of the exchanger, the difference between the static pressures of the fluid at the inlet and at the outlet of a channel considered is much less than the difference between the pressures static of the fluid at the inlet and outlet of a channel located towards the inlet and outlet fittings.
• providing an add-on member making it possible to reduce the cross section of the fluid, towards the bottom of the outlet manifold ensures an increase in the flow rate of the fluid, in this region upstream of the manifold. This induces an increase in the dynamic pressure of this fluid, in the aforementioned upstream region, as well as a corresponding decrease in its static pressure.
• the difference between the static pressures of the fluid at the inlet and at the outlet of the channels opening out in the vicinity of the bottom of the outlet manifold is notably greater than in the prior art. This contributes to homogenizing, along the outlet manifold, the differences in static pressures existing between the inlet and the outlet of the channels, and therefore ensures a satisfactory distribution of the fluid between these channels.
• the invention guarantees great simplicity in manufacturing the plate heat exchanger. Indeed, it only uses an add-on unit, the cost price of which is low, and which can be fixed easily on the walls of the collector.
• this added member making it possible to reduce the cross-section of the fluid passage towards the bottom of the manifold, has a satisfactory adaptability to the number of plates of the exchanger. Indeed, in the context of an increase in the length of the collector, linked to a higher number of plates, it is only necessary to modify the angle of revolution, as well as the length of one added member.
• the invention is particularly advantageous in the case of two-phase flows, formed of a gas loaded with oil. Since the presence of the added member makes it possible to increase the speed of the fluid towards the bottom of the collector, without however creating turbulence, any retention of this oil is substantially avoided, in the vicinity of this bottom.
• the added member has a main axis coincident with the median longitudinal axis of the outlet manifold.
• the fluid is able to flow in a regularly distributed manner around this member.

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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)

Applications Claiming Priority (3)

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• 2000
  • 2000-03-28 FR FR0003917A patent/FR2807152B1/fr not_active Expired - Fee Related
• 2001
  • 2001-03-27 WO PCT/FR2001/000931 patent/WO2001073366A1/fr not_active Application Discontinuation
  • 2001-03-27 AU AU2001246655A patent/AU2001246655A1/en not_active Abandoned
  • 2001-03-27 EP EP01919584A patent/EP1269100A1/de not_active Withdrawn

Non-Patent Citations (1)

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