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
  • F28F9/027—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits in the form of distribution pipes
• • 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
  • 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
  • F28D9/0031—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 the conduits for one heat-exchange medium being formed by paired plates touching each other
  • F28D9/0043—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 the conduits for one heat-exchange medium being formed by paired plates touching each other the plates having openings therein for circulation of at least one heat-exchange medium from one conduit to another
• • 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
  • F28D9/0031—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 the conduits for one heat-exchange medium being formed by paired plates touching each other
  • F28D9/0043—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 the conduits for one heat-exchange medium being formed by paired plates touching each other the plates having openings therein for circulation of at least one heat-exchange medium from one conduit to another
  • F28D9/0056—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 the conduits for one heat-exchange medium being formed by paired plates touching each other the plates having openings therein for circulation of at least one heat-exchange medium from one conduit to another with U-flow or serpentine-flow inside conduits; with centrally arranged openings on the 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
  • 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
  • F28F9/027—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits in the form of distribution pipes
  • F28F9/0273—Header boxes; End plates with static flow control means, e.g. with means for uniformly distributing heat exchange media into conduits in the form of distribution pipes with multiple holes
• • 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
  • F25B39/022—Evaporators with plate-like or laminated elements
• • 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

Definitions

• This invention relates to improvements in plate heat exchangers and relates particularly to improvements in such heat exchangers used as evaporators in refrigeration systems.
• Plate heat exchangers have been developed for use in refrigeration systems and are extremely effective and efficient in transferring heat from a heat-exchange fluid, such as water, to the refrigerant.
• Such heat exchangers comprise an assembly of a plurality of metal plates which are formed, by stamping, with a series of ridges and troughs.
• the ridges and troughs, in the assembly constitute pathways for refrigerant and a heat-exchange fluid.
• the refrigerant and heat-exchange fluid pass through the heat exchanger on opposite sides of each plate, there being refrigerant inlet and heat-exchange fluid outlet openings at one end of the heat exchanger and corresponding outlet and inlet openings at the other end of the heat exchanger.
• Expansion ratios of 50:1 may be experienced giving rise of up to 2%, or more, of the liquid vaporizing during the expansion or pressure reduction phase.
• the vapor can account for 50% or more of the volumetric area occupied by the liquid and vapor refrigerant mixture, and as the liquid and gas refrigerant have differing densities giving rise to variable flow patterns, some passageways within a plate system of heat-exchange plates will receive more liquid refrigerant than others. This, therefore, gives rise to unevenness in the relative amounts of liquid and vapor passing through the various refrigerant passageways thus resulting in variations in vapor temperature at the outlet.
• the temperature of the heat- exchange fluid flowing through the fluid passageways of the heat exchanger may therefore be lower in some passageways than in others.
• the passageways between some plates may also have a tendency to freeze if those plates are subject to a greater percentage of liquid refrigerant than others. This can lead to some of the heat-exchange fluid circuits freezing up whilst others continue to flow thus aggravating the difficulty and possibly leading to failure of the heat exchanger.
• a plate heat exchanger comprising an assembly of a plurality of plates which separate and define passage means for the flow of refrigerant and a heat-exchange fluid, refrigerant inlet means communicating with the refrigerant passage means, heat-exchange fluid inlet means communicating with the heat-exchange fluid passage means, respective outlet means for the refrigerant and heat-exchange fluid, refrigerant distribution means associated with the refrigerant inlet means and including flow control means to regulate and direct the refrigerant into the respective refrigerant passage means.
• the refrigerant distribution means may comprise a tube located in the refrigerant inlet means the tube having a plurality of holes creating a row of orifices lined up to direct refrigerant to the respective refrigerant passages.
• the number of and size of holes may be determined in accordance with the size of plates, the number of plates forming the heat exchanger, the capacity of the heat exchanger, the type of refrigerant used and the refrigerant and system pressures, and other operating parameters. It will be understood that the number of holes does not necessarily correspond with the number of refrigerant passages, although this would generally be preferred.
• the sizes of the individual orifices may be varied to take account of loss of refrigerant pressure along the tube.
• the orifices may also be variable in size to vary the capacity of the heat exchanger in accordance with design considerations or operating parameters.
• a tube with the holes or orifices, or other openings is used as the expansion device, or pressure reduction device, thus obviating the need for an external expansion valve or other expansion or pressure reduction means.
• the size of the holes or orifices may increase gradually from an inlet end of the tube thus providing even distribution of liquid to each of the refrigerant passages.
• a tube with the holes, orifices or other openings is used as a partial expansion or pressure reduction device in conjunction with an external expansion valve or other expansion or pressure reduction means.
• an auxiliary external expansion valve or other expansion or pressure reduction means is used in conjunction with the refrigerant distribution means.
• a second refrigerant distributor is provided in parallel with the first refrigerant distribution means. The temperature of refrigerant after expansion through the first refrigerant distribution means is monitored in conjunction with outlet refrigerant temperature and/or pressure , heat- exchange fluid inlet and outlet temperatures and/or pressures and ambient temperature, and the external expansion valve is selectively operated as required to maintain predetermined temperature and/or pressure parameters.
• holes provided in the second distributor are of a relatively large size to allow relatively low pressure refrigerant to be distributed to the passages.
• a further feature of the present invention is the provision of partial blanking means to partially close the communication between the refrigerant inlet means and the refrigerant passage means.
• An opening or hole in the blanking means acts to direct the liquid refrigerant in a predetermined direction, preferably towards the centre of the refrigerant passage means, i.e., towards the centre line of the plate assembly.
• the blanking means may constitute the refrigerant distribution means while in another form of the invention, the blanking means is provided to work in conjunction with the refrigerant distribution means.
• the blanking means comprises a generally C-shaped wire member disposed about the refrigerant inlet means between each pair of plates defining the refrigerant passage means.
• Fig. 1 is a sectional, schematic view of a standard plate heat exchanger showing the refrigerant path therethrough;
• Fig. 2 is a view similar to that of Fig. 1 but showing the heat-exchange fluid path;
• Fig. 3 is a view similar to that of Fig. 1 illustrating one embodiment of the present invention
• Fig. 4 is an enlarged sectional view of the base of the heat exchanger of Fig. 3;
• Fig. 5 is a view taken along the lines 5-5 of Fig. 4;
• Fig. 6 is a part exploded, schematic perspective view of the heat exchanger of Fig. 3 but also showing a modification to the invention
• Fig. 7 is a cross-sectional view illustrating the modification of Fig. 6;
• Fig. 8 is a view similar to that of Fig. 4 but illustrating a further form of the present invention;
• Fig. 9 is a sectional view along the lines 9-9 of Fig. 8; and
• Fig. 10 is a view similar to Fig. 9 illustrating a still further embodiment of the invention. DESCRIPTION OF PREFERRED EMBODIMENTS
• Figs. 1 and 2 illustrate a plate heat exchanger 12 which is an assembly of a plurality, for example, thirty (30), ribbed plates 10, the ribs of adjacent plates interengaging and adjacent plates defining passages 14 and 16 for refrigerant and a heat-exchange fluid, respectively.
• a plate heat exchanger 12 which is an assembly of a plurality, for example, thirty (30), ribbed plates 10, the ribs of adjacent plates interengaging and adjacent plates defining passages 14 and 16 for refrigerant and a heat-exchange fluid, respectively.
• water is commonly used as the heat-exchange fluid
• future reference to such fluid will be made by reference to water.
• the drawings illustrate a counter-flow heat exchanger, it will be understood the invention also applies to a parallel flow heat exchanger.
• each plate 10 is formed with two holes 15 at each end, the holes 15, in an assembly of plates 10, forming inlets and outlets for the refrigerant and water.
• the plates 10 separate the refrigerant passages 14 from the water passages 16, and the plates are so formed, interengaged and sealed together, as by brazing or the like, such that fluid introduced into one of the lower holes 15 will pass through one set of the refrigerant and water passages 14 and 16 to exit from a corresponding upper hole while fluid introduced into the other of the lower holes 15 will pass through the other set of passages.
• a refrigerant inlet manifold 17 communicates with the openings 15 which interconnect the refrigerant passages 14 and a refrigerant outlet manifold 18 at the upper end of the heat exchanger enables refrigerant to exit from the heat exchanger. Similar water inlet and outlet manifolds 19 and 21, respectively, enable water to be circulated through the water passages 16.
• the refrigerant inlet manifold 17 is connected to a high pressure liquid refrigerant supply 22 through an expansion valve 23 which reduces the refrigerant pressure. As the refrigerant passes through this valve 23, some refrigerant flashes to vapor and mixes with the liquid refrigerant.
• Line 24 is the "completion of phase change" line and the graph is indicative of the temperature of refrigerant exiting the several refrigerant passages 14. These temperatures may vary from 2°C to 11°C, depending on the proportion of vapor in the refrigerant entering the individual refrigerant passages 14.
• the variation in temperature of the refrigerant vapor exiting the passages 14 results in a similar variation in temperature of water exiting the water passages 16.
• the temperature of the water exiting the water passages 16 can vary from between 2°C to 10°C. If the water temperature in any one water passage 16 becomes so low as to cause the water to freeze, additional loads are placed on other parts of the heat exchanger and the efficiency of the heat exchanger falls dramatically. Such freezing may also lead to failure of the heat exchanger.
• liquid refrigerant at high pressure is supplied directly to a distribution tube 26 mounted in the refrigerant inlet manifold 17 and extending through the plate holes 15 which communication with the refrigerant passages 14.
• the distribution tube 26 has a number of small holes or orifices 27 corresponding in number to and carefully lined up with the refrigerant passages 14.
• the holes or orifices 27 may be of varying sizes increasing progressively from the manifold 17 to the rear of the heat exchanger 12 so that even distribution of liquid refrigerant is achieved to each of the refrigerant passages 14 notwithstanding the pressure drop along the tube 26.
• the holes or orifices 27 provide the required pressure reduction, and accompanying expansion, of the high pressure liquid refrigerant directly into the passages 14 so that there is an even distribution of liquid refrigerant throughout the length of the heat exchanger 12.
• an external thermal expansion valve may be used in conjunction with the distribution tube 26 to provide a desired drop in refrigerant pressure.
• C-shaped washers 29 are mounted in the refrigerant passages 14 to substantially surround the respective plate holes 15 and blank off direct access to the passages 14.
• the opening 25 between the ends of each C-shaped washer 29 directs the liquid refrigerant downwardly and towards the centre of the passages 14 to thereby cause the liquid refrigerant to evenly disperse across the full width of the passages 14.
• a raised land 30 in the plates 16 defining the passages 14 also assists in guiding the refrigerant towards the centre of the respective passages 14.
• the holes 27 in the tube 26 may be varied in size to take account or differing operating parameters in different refrigerant and air conditioning systems giving rise to different refrigerant requirements.
• the tube 26 has a sleeve 26a thereon which is r ⁇ tatable relative to the tube 26 so as to close off or open up the holes 27 as desired.
• the sleeve 26a may be fixed in position by any suitable means.
• a second liquid refrigerant distribution tube 31 extends through the plate holes 15 which communicate with the refrigerant passages 14 substantially parallel to the first liquid refrigerant distribution tube 26.
• the second tube 31 is provided with holes corresponding in number to and substantially aligned with the holes or orifices 27 in the distribution tube 26, the holes 32 being of substantially larger size than the holes or orifices 27.
• the second refrigerant tube 31 is connected, externally of the heat exchanger
• the second liquid refrigerant tube 31 provides additional refrigerant expansion capacity for the heat exchanger 12 such as may be required during start ⁇ up and during operation in low ambient temperature conditions, particularly using air-cooled condensers in the refrigerant circuit.
• the inlet manifold 17 also carries a temperature sensing probe 36, and other sensors (not shown) are used to determine the temperature and/or pressure at the refrigerant outlet as well as water inlet and outlet temperatures to regulate operation of the expansion valve 34.
• the provision of the second liquid refrigerant tube 31 improves the operating capacity of the heat exchanger 12 during a range of operating conditions thereby increasing the efficiency of the system in which the heat exchanger is installed.
• the C-shaped washers 29 are also used in this embodiment and both sets of holes 27 and 32 are directed towards the opening 25 between the ends of the washer.
• the orientation of the holes relative to the orientation of the tubes is arranged to ensure that the holes 32 are directed away from the tube 26.
• Fig. 10 there is illustrated a further embodiment of the invention of the invention in which the refrigerant distribution is carried out by a tapered tube 37 extending through the plate holes 15 which communicate with the refrigerant passages 14.
• the tube 37 is similar to the tube 26 in the embodiments illustrated in Figs. 3 to 7 except that its cross-sectional area decreases from the refrigerant manifold end to the opposite end of the tube 37.
• the holes 38 in the tapered tube 37, which correspond to the holes 27 in the tube 26, are each of identical size and it is the tapering of the tube which ensures even distribution of liquid refrigerant through the holes 38.
• the refrigerant passages 14 can be partially blanked off using
• Fig. 10 which comprises a blanking tube having a slot 41 along one side.
• the blanking tube 39 is inserted through the plate holes 15 (those holes communicating with the refrigerant passageways 14) so that the slot 41 faces generally inwardly and downwardly, similar to the location of the opening between the ends of the C-shaped washers 29 in the previous embodiments.
• the blanking tube may be formed of a material which can be brazed to the plates 16 around the holes 15, in which case the blanking tube 39 is inserted prior to the final brazing step in construction of the heat exchanger 12.
• the blanking tube 39 may be inserted after the final brazing step in which case the blanking tube may be formed of any suitable material, including plastics. If the material of the blanking tube is a resilient material, the tube 39 may be formed with an outer diameter larger than the diameter of the plate holes 15 whereby insertion is effected by compressing the tube so that the slot 41 along the one side is closed thereby reducing the tube diameter sufficiently to enable it to be inserted through the plate holes 15. If desired, circumferential grooves may be formed in the blanking tube 39 so that, when correctly located in place, the edges of the plate holes 15 are seated in the circumferential grooves. Sealing materials or adhesives may be used, if desired, to locate and seal the blanking tube 39 in its desired position.
• modifications of the invention may include other means for throttling the flow of liquid refrigerant from the refrigerant inlet manifold 17 to the individual passages 14. Provided such throttling is variable to even out the flow of liquid and vapor refrigerant to each passage 14, similar efficiencies could be expected to those of the particular embodiments described above.
• the present invention also allows for the elimination of the normal expansion valve or other types of expansion or refrigerant pressure reduction devices thus allowing for reduced manufacturing costs whilst giving a marked increase in performance of the heat exchanger.

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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)

Publications (2)

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ID=3776580

Family Applications (1)

Country Status (11)

Families Citing this family (82)

Citations (5)

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• 1993
  • 1993-12-02 IL IL10785093A patent/IL107850A0/xx unknown
  • 1993-12-06 TW TW082110281A patent/TW232049B/zh active
  • 1993-12-06 MX MX9307692A patent/MX9307692A/es not_active Application Discontinuation
  • 1993-12-06 JP JP6513559A patent/JPH08504027A/ja active Pending
  • 1993-12-06 CA CA002151129A patent/CA2151129A1/en not_active Abandoned
  • 1993-12-06 EP EP94901695A patent/EP0670988A4/de not_active Withdrawn
  • 1993-12-06 PT PT101421A patent/PT101421A/pt not_active Application Discontinuation
  • 1993-12-06 WO PCT/AU1993/000627 patent/WO1994014021A1/en not_active Application Discontinuation
  • 1993-12-06 AU AU56195/94A patent/AU686582B2/en not_active Ceased
  • 1993-12-07 ZA ZA939173A patent/ZA939173B/xx unknown
  • 1993-12-07 CN CN93121143A patent/CN1065624C/zh not_active Expired - Fee Related

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