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
  • F28F9/0282—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits by varying the geometry of conduit ends, e.g. by using inserts or attachments for modifying the pattern of flow at the conduit inlet or outlet
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B39/00—Evaporators; Condensers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B41/00—Fluid-circulation arrangements
  • F25B41/30—Expansion means; Dispositions thereof
  • F25B41/37—Capillary tubes
• • 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
  • F28D1/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators
  • F28D1/02—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid
  • F28D1/04—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits
  • F28D1/053—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits the conduits being straight
  • F28D1/0535—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits the conduits being straight the conduits having a non-circular cross-section
  • F28D1/05366—Assemblies of conduits connected to common headers, e.g. core type radiators
• • 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
  • F28F1/02—Tubular elements of cross-section which is non-circular
  • F28F1/025—Tubular elements of cross-section which is non-circular with variable shape, e.g. with modified tube ends, with different geometrical features
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2500/00—Problems to be solved
  • F25B2500/01—Geometry problems, e.g. for reducing size
• • 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
  • F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
  • F28D2021/0019—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for
  • F28D2021/0068—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for for refrigerant cycles
  • F28D2021/0071—Evaporators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F2260/00—Heat exchangers or heat exchange elements having special size, e.g. microstructures
  • F28F2260/02—Heat exchangers or heat exchange elements having special size, e.g. microstructures having microchannels

Definitions

• This invention relates generally to air conditioning, heat pump and refrigeration systems and, more particularly, to parallel flow evaporators thereof.
• a definition of a so-called parallel flow heat exchanger is widely used in the air conditioning and refrigeration industry and designates a heat exchanger with a plurality of parallel passages, among which refrigerant is distributed and flown in the orientation generally substantially perpendicular to the refrigerant flow direction in the inlet and outlet manifolds. This definition is well adapted within the technical community and will be used throughout the text.
• Refrigerant maldistribution in refrigerant system evaporators is a well-known phenomenon. It causes significant evaporator and overall system performance degradation over a wide range of operating conditions.
• Maldistribution of refrigerant may occur due to differences in flow impedances within evaporator channels, non-uniform airflow distribution over external heat transfer surfaces, improper heat exchanger orientation or poor manifold and distribution system design. Maldistribution is particularly pronounced in parallel flow evaporators due to their specific design with respect to refrigerant routing to each refrigerant circuit. Attempts to eliminate or reduce the effects of this phenomenon on the performance of parallel flow evaporators have been made with little or no success. The primary reasons for such failures have generally been related to complexity and inefficiency of the proposed technique or prohibitively high cost of the solution.
• the inlet and outlet manifolds or headers usually have a conventional cylindrical shape.
• the vapor phase is usually separated from the liquid phase. Since both phases flow independently, refrigerant maldistribution tends to occur.
• the liquid phase (droplets of liquid) is carried by the momentum of the flow further away from the manifold entrance to the remote portion of the header.
• the channels closest to the manifold entrance receive predominantly the vapor phase and the channels remote from the manifold entrance receive mostly the liquid phase.
• the velocity of the two-phase flow entering the manifold is low, there is not enough momentum to carry the liquid phase along the header.
• the liquid phase enters the channels closest to the inlet and the vapor phase proceeds to the most remote ones.
• the liquid and vapor phases in the inlet manifold can be separated by the gravity forces, causing similar maldistribution consequences. In either case, maldistribution phenomenon quickly surfaces and manifests itself in evaporator and overall system performance degradation. [0009] Moreover, maldistribution phenomenon may cause the two-phase
• the objective of the invention is to introduce a pressure drop control for the parallel flow evaporator that will essentially equalize pressure drop through the heat exchanger channels and therefore eliminate refrigerant maldistribution and the problems associated with it. Further, it is the objective of the present invention to provide refrigerant expansion at the entrance of each channel, thus eliminating a predominantly two-phase flow in the inlet manifold and preventing phase separation, which is one of the main causes for refrigerant maldistribution.
• each of the channels is crimped at or adjacent to their entrance location such that a desired restriction for each of the channels is provided.
• the restriction size may be varied from channel to channel, if desired, in order to accommodate other non-uniform factors (such as different heat transfer rates) affecting the maldistribution phenomenon.
• the channels may be crimped at the very end/entrance or some distance away from the entrance in order not to interfere with the brazing joint to the inlet manifold.
• internal rigidity (and/or heat transfer enhancement) fins can be simply compressed during crimping process or machined down prior to crimping.
• these restrictions can be used as primary (and the only) expansion devices for low-cost applications or as secondary expansion devices, in case precise superheat control is required, and another fixed area restriction device (such as a capillary tube or an orifice) or a thermostatic expansion valve (TXV) or an electronic expansion valve (EXV) is employed as a primary expansion device.
• another fixed area restriction device such as a capillary tube or an orifice
• TXV thermostatic expansion valve
• EXV electronic expansion valve
• the precision of crimping doesn't have to be of extremely high tolerance in a latter case.
• Any suitable means of crimping may be employed such as a crimping tool in the form of pliers having the desired crimping face geometry or the use of stamping die having the desired geometry.
• FIG. 1 is a schematic illustration of a parallel flow heat exchanger in accordance with the prior art.
• Fig. 2 is an enlarged partial side sectional view of a parallel flow heat exchanger illustrating one embodiment of the present invention.
• Fig. 3a is a view of Fig. 2 illustrating a second embodiment of the present invention.
• Fig. 3b is a view of Fig. 2 illustrating a third embodiment of the present invention.
• Fig. 3c is a view of Fig. 2 illustrating a fourth embodiment of the present invention.
• Fig. 3d is a view of Fig. 2 illustrating a fifth embodiment of the present invention.
• Fig. 4 is an end view of an uncrimped channel.
• Fig. 5 is a view of Fig. 4 after crimping to a predetermined configuration.
• Fig. 6 is a view of Fig.4 after crimping to a second configuration.
• Fig. 7 is an end view of a second uncrimped channel.
• Fig. 8 is a view of Fig. 7 after crimping to a predetermined configuration.
• a parallel flow (minichannel or microchannel) heat exchanger 10 which includes an inlet header or manifold 12, an outlet header or manifold 14 and a plurality of parallel disposed channels 16 fluidly interconnecting the inlet manifold 12 to the outlet manifold 14.
• the inlet and outlet headers 12 and 14 are cylindrical in shape, and the channels 16 are tubes (or extrusions) of flattened or round cross-section.
• Channels 16 normally have a plurality of internal and external heat transfer enhancement elements, such as fins. For instance, external fins 18, uniformly disposed therebetween for the enhancement of the heat exchange process and structural rigidity are typically furnace-brazed.
• Channels 16 may have internal heat transfer enhancements and structural elements as well (See Figs. 4-6).
• refrigerant flows into the inlet opening 20 and into the internal cavity 22 of the inlet header 12. From the internal cavity 22, the refrigerant, in the form of a liquid, a vapor or a mixture of liquid and vapor (the most typical scenario in the case of an evaporator with an expansion device located upstream) enters the channel openings 24 to pass through the channels 16 to the internal cavity
• the refrigerant which is now usually in the form of a vapor, in the case of evaporator applications, flows out of the outlet opening 28 and then to the compressor (not shown).
• air is circulated preferably uniformly over the channels 16 and associated fins 18 by an air-moving device, such as fan (not shown), so that heat transfer interaction occurs between the air flowing outside the channels and refrigerant within the channels.
• the channels 16 have been crimped at least at the entrance end 30 to provide for a restriction in each channel and to assure refrigerant expansion directly at each channel entrance which results in a pressure drop across the restriction and reduction and/or elimination of phase separation and refrigerant maldistribution in the system.
• the channels are crimped at the very end 32 and at a point 34, some distance away from the end and the attachment point to the manifold 12.
• the channels are crimped at a single location 36, a predetermined distance from the channel end and, once again, away form the attachment point to the manifold 12, in order not to interfere with the attachment process.
• the channels are crimped for a predetermined length or distance "L" near the channel ends but with less cross-section area alteration/reduction than in Fig. 2, 3a and 3b.
• the channels are crimped at multiple locations 38, 40 and 42 near the channel ends, forming a passage of alternating contractions and expansions, but, once again, with less cross-section area alteration/reduction than in Fig. 2, 3a and 3b.
• Fig. 4 illustrates a cross section of an uncrimped channel 50 having flattened shape and integral vertical support members 52.
• Fig. 5 illustrates channel 50 crimped to a predetermined configuration
• Fig. 6 illustrates channel 50 crimped to a more flattened configuration
• crimping occurs uniformly and alters support members 52 to a different shape and cross-section 72.
• different support members can be utilized within the scope of the present invention to divide channels 16 internally into multiple refrigerant passes of triangular, trapezoidal, circular or any other suitable cross- section. In all these cases, support members can be altered during the crimping process or left unchanged.
• Fig. 7 illustrates a cross section of an uncrimped channel 80 of a flattened shape (no internal support members are present in this design configuration).
• Fig. 8 illustrates channel 80 crimped to a more flattened configuration
• crimping doesn't have to be uniform throughout all the channels but instead can progressively change from one channel to another or from one channel section to another, for instance, to counter-balance other factors effecting refrigerant maldistribution.
• the crimping can be used in the condenser and evaporator applications at the channel entrance within intermediate manifolds as well.
• an intermediate manifold between inlet and outlet manifolds
• refrigerant is typically flown in a two-phase state, and such heat exchanger configurations can similarly benefit from the present invention by incorporating channel crimping at the entrance ends directly communicating with intermediate manifolds.
• the crimping can be done at the exit end of the channels 16 or at some intermediate location along the channel length providing only hydraulic resistance uniformity and pressure drop control and with less effect on overall heat exchanger performance.

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• 2005
  • 2005-12-29 CN CNA2005800475315A patent/CN101443621A/zh active Pending
  • 2005-12-29 US US11/794,921 patent/US20080105420A1/en not_active Abandoned
  • 2005-12-29 AU AU2005326710A patent/AU2005326710A1/en not_active Abandoned
  • 2005-12-29 BR BRPI0519905-0A patent/BRPI0519905A2/pt not_active IP Right Cessation
  • 2005-12-29 KR KR1020077017115A patent/KR20070091216A/ko not_active Application Discontinuation
  • 2005-12-29 EP EP05855808A patent/EP1859220A4/en not_active Withdrawn
  • 2005-12-29 WO PCT/US2005/047309 patent/WO2006083442A2/en active Application Filing
  • 2005-12-29 JP JP2007554086A patent/JP2008533415A/ja not_active Withdrawn
  • 2005-12-29 CA CA002596364A patent/CA2596364A1/en not_active Abandoned
  • 2005-12-29 MX MX2007009248A patent/MX2007009248A/es not_active Application Discontinuation

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