Classifications

• • 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
  • F28D1/05383—Assemblies of conduits connected to common headers, e.g. core type radiators with multiple rows of conduits or with multi-channel conduits
• • 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
  • F25B39/02—Evaporators
  • F25B39/028—Evaporators having distributing means
• • 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
  • F28F13/003—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by using permeable mass, perforated or porous materials
• • 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
  • F28F9/028—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits by using inserts for modifying the pattern of flow inside the header box, e.g. by using flow restrictors or permeable bodies or blocks with channels
• • 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
  • 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

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 present invention is to introduce a pressure drop control for the parallel flow (microchannel or minichannel) evaporator that will essentially equalize pressure drop through the heat exchanger circuits 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, which is one of the main causes for refrigerant maldistribution.
• porous media inserts can be brazed in each channel during furnace brazing of the entire heat exchanger, chemically bonded or mechanically fixed in place.
• these inserts 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 a thermostatic expansion valve (TXV) or an electronic expansion valve (EXV) is employed as a primary expansion device.
• TXV thermostatic expansion valve
• EXV electronic expansion valve
• Suitable and inexpensive porous inserts may be made of sintered metal, compressed metal, such as steel wool, specialty designed porous ceramics, etc.
• inexpensive porous media insert When inexpensive porous media insert is placed in each channel of the parallel flow evaporator, or at the entrance of each parallel flow evaporator channel, it represents a major resistance to the refrigerant flow within the evaporator. In such circumstances, the main pressure drop region will be across these inserts and the variations in the pressure drop in the channels or in the manifolds of the parallel flow evaporators will play a minor (insignificant) role.
• FIG. 1 is a schematic illustration of a parallel flow heat exchanger in accordance with the prior art.
• Fig. 2 is a partial side sectional view of one embodiment of the present invention.
• Fig. 3 is an end view of a porous insert positioned at the entrance to a channel of the present invention.
• Fig. 4 is a perspective view of the porous insert illustrated in Fig. 3.
• Fig. 5a is a side sectional view illustrating a further embodiment of the present invention.
• Fig. 5b is a side sectional view illustrating yet a further embodiment of the present invention.
• Fig. 6 is an end view of a plurality of channels in one embodiment of the invention.
• Fig. 7a is a perspective view which illustrates a porous cap embodiment of the invention.
• Fig. 7b is a perspective view which illustrates a second porous cap embodiment.
• Fig. 7c is a perspective view which illustrates a third porous cap embodiment.
• 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.
• refrigerant flows into the inlet opening 20 and into the internal cavity 22 of the inlet header 12.
• 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 26 of the outlet header 14.
• 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.
• a porous insert 30 is inserted at the entrance of each channel 16.
• the channels 16 have internal structural elements such as support members 16a (Fig. 3), usually included for structural rigidity and/or heat transfer enhancement purposes, the porous inserts
• inserts 30 incorporate slots 32 to accommodate the support members 16a when in position at the channel entrance (See Fig. 4). Further, in case a various degree of expansion and/or hydraulic impedance are desired to be provided by the inserts 30 or 32, for instance, to counter-balance other abovementioned factors effecting refrigerant distribution amongst the channels 16, characteristics such as porosity values or geometric dimensions (insert depth, insertion depth, etc.) of the inserts can be altered to achieved the desired result for each channel 16.
• FIG. 5a illustrates another embodiment in which all the entrances to the channels 16 are covered by a single porous member 34 positioned within a manifold 40. Further, a support member 36 may be used to assist in setting up a relative position of the porous member 34 and the channels 16 within the manifold
• porous member 34 and support member 36 can be manufactured from and combined in a single member made from porous material.
• Fig. 5b is a further embodiment of the structure of Fig. 5a in which the porous member is a composite of two different porous materials 34 and 34a.
• a number of composite materials within the porous member can be more than two.
• Fig. 6 illustrates a side view of Fig. 5a.
• Fig. 7a illustrates a unitized elongated porous member 34b which seals multiple channels 16 at a predetermined distance from the channel entrance.
• Fig. 7b illustrates an elongated porous member 34c which caps the ends of multiple channels 16.
• Fig. 7c a modification of the structure of Fig. 7b in which the porous member 34d is accurate in shape and caps the ends of the channels 16.
• the shape of the porous member 34d can be of any suitable configuration, rather than a rectangular in cross-section. Further, the porous member 34d is preferably positioned within the manifold 40 in such way that there is a gap between the inner wall of the manifold 40 and the porous member 34a allowing for more uniform refrigerant distribution prior to entering the porous member 34d and channels 16.
• any type of porous member and/or material which accomplishes the objectives of the present invention may be used. Similarly, as illustrated by Figs. 2-7, any design or configuration which accomplishes the objectives of the invention may be employed in the use of the present invention.
• the porous inserts can be used in the condenser and evaporator applications within intermediate manifolds as well. For instance, if a heat exchanger has more than one refrigerant pass, an intermediate manifold (between inlet and outlet manifolds) is incorporated in the heat exchanger design. In the intermediate manifold, refrigerant is typically in a two-phase state, and such heat exchanger configurations can similarly benefit from the present invention by incorporating the porous inserts into such intermediate manifolds. Further, the porous inserts can be placed into an inlet manifold of the condenser and an outlet manifold of the evaporator for providing only hydraulic resistance uniformity and pressure drop control and with less effect on overall heat exchanger performance.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Dispersion Chemistry (AREA)
• Chemical & Material Sciences (AREA)
• Geometry (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Micromachines (AREA)
• Details Of Heat-Exchange And Heat-Transfer (AREA)

Priority Applications (9)

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Publications (2)

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• 2005
  • 2005-12-29 BR BRPI0519907-7A patent/BRPI0519907A2/pt not_active IP Right Cessation
  • 2005-12-29 MX MX2007009252A patent/MX2007009252A/es unknown
  • 2005-12-29 CA CA002596365A patent/CA2596365A1/en not_active Abandoned
  • 2005-12-29 AU AU2005326711A patent/AU2005326711B2/en not_active Ceased
  • 2005-12-29 WO PCT/US2005/047310 patent/WO2006083443A2/en active Application Filing
  • 2005-12-29 US US11/794,970 patent/US20080099191A1/en not_active Abandoned
  • 2005-12-29 EP EP05857243A patent/EP1844290B1/de not_active Not-in-force
  • 2005-12-29 KR KR1020077017773A patent/KR20070100785A/ko not_active Application Discontinuation
  • 2005-12-29 CN CN2005800476873A patent/CN101111734B/zh not_active Expired - Fee Related
  • 2005-12-29 JP JP2007554087A patent/JP2008528938A/ja not_active Withdrawn
• 2008
  • 2008-07-10 HK HK08107627.8A patent/HK1117224A1/xx not_active IP Right Cessation

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