of food services. Conventionally, these refrigerant vapor compression systems include a compressor, a condenser, an expansion device and an evaporator connected in refrigerant flow communication. The aforementioned basic components of the refrigerant system are interconnected by refrigerant lines in a closed refrigerant circuit and are arranged in accordance with the steam compression cycle employed. An expansion device, either an expansion valve or a fixed diameter measuring device, such as an orifice or a capillary tube, is arranged in the refrigerant line at a location in the upstream refrigerant circuit, with respect to the flow rate of the refrigerant. refrigerant, evaporator and downstream of the condenser. The expansion device operates to expand the liquid refrigerant that passes through the refrigerant line that coreates from the condenser to the evaporator at a lower pressure and temperature. By doing so, a portion of liquid refrigerant that crosses the expansion device expands into steam. As a result, in conventional refrigerant vapor compression systems of this type, the flow of refrigerant entering the evaporator constitutes a mixture of two phases. The particular percentages of liquid refrigerant and vapor refrigerant depend on the expansion device
particular employee and the refrigerant in use, for example, R12, R22, R134a, R404A, R410A, R407C, R717, R744 or Other compressible fluid. In some refrigerant value compression systems, the evaporator is a parallel tube heat exchanger. Such heat exchangers have a plurality of parallel coolant flow paths therethrough provided by a plurality of tubes extending in parallel relationship between an inlet manifold and an outlet manifold. The inlet manifold receives the refrigerant flow from the refrigerant circuit and distributes it among the plurality of flow paths through the heat exchanger. The outlet manifold serves to collect the flow of refrigerant as it leaves the respective flow paths and to direct the flow of refrigerant back to the refrigerant line for its return to the compressor in a single-pass heat exchanger or through a bank addition of heat exchange tubes in a multiple-pass heat exchanger Historically! E, parallel tube heat exchangers used in refrigerant compression systems have used round tubes, typically have a diameter of 1.27 cml (inch), 9.54 mm (3/8 inch) or 7 mm. More recently, channel pipes
multiple flat, rectangular or oval are being used in thermo exchangers for refrigerant vapor compressor systems. Each multi-channel tube has a plurality of longitudinally extending flow channels in parallel relation to the length of the tube, each channel providing a small cross-section flow area coolant path. In this way a heat exchanger with multiple channel tubes extending in parallel relation between the inlet and outlet manifolds of the heat exchanger will have a relatively large number of small cross-sectional flow area coolant paths extending between: both collectors. In contrast, a di5 parallel tube heat exchanger with conventional round tubes will have a relatively small number of large flow area flow paths that extend between the co-input and output readers, the non-uniform distribution, also referred to as maldistribution, The two-phase refrigerant flow is a pprroobblleemmaa ccoommúnn eenn parallel tube heat exchangers that adversely impacts the efficiency of the heat exchanger. The dual phase maldistribution problems are caused by the difference in intensity of the vapor phase refrigerant and the liquid phase refrigerant present in the inlet manifold due to the
expansion of refrigerant as it travels the upstream expansion device A solution for controlling the distribution of cooling flow through the parallel tubes in an evaporative heat exchanger is described in US Patent No. 6,5C 2,413, Repice et al. In the refrigerant vapor compression system described herein, the high pressure liquid refrigerant of the condenser expands partially er. a conventional in-line expansion device upstream of the heat exchanger inlet manifold in a lower pressure refrigerant.
Additionally, a re-friction, such as a simple narrowing in the tube or an internal orifice plate disposed within the tube, is provided in each tube connected to the inlet manifold downstream of the tube inlet to complete the expansion to a slurry mixture. liquid / vapor refrigerant under pressure after it enters the tube. Another solution for controlling the distribution of cooling flow through parallel tubes in an evaporative heat exchanger is described in Japanese Patent No. JP408057? , Kanzaki et al. In the refrigerant vapor compression system described herein, the high-pressure liquid refrigerant of the condenser is also partially expanded in a condenser device.
conventional line expansion to a lower pressure refrigerant upstream of a heat exchanger distribution chamber. A plate having a plurality of holes in the same extends through the chamber
The lower pressure refrigerant expands as it passes through the orifices to a low pressure liquid / vapor mixture downstream of the plate and upstream of the inlets to the respective tubes opening to the chamber. Japanese Patent No. 6241682, Massaki et al., Discloses a parallel flow tube heat exchanger for a heat pump where the inlet end of each multiple channel pipe which is connected to the inlet manifold is crushed to form a regulatory restriction partial in each tube just downstream of the tube inlet. Japanese Patent No. JP8233409, Hiroaki et al., Discloses a parallel flow tube heat exchanger where a plurality of flat multiple channel tubes are connected between a pair of coalescers, each of which has a decreasing interior: in flow area in the direction of the refrigerant flow as a means to uniformly distribute the refrigerant to the respective tubes. Japanese Patent No. JP2002022313, Yasushi, discloses a parallel tube heat exchanger where the refrigerant is provided to the collector through an inlet pipe that is
extends along the axis of the collector to end near the end of the collector so that the flow of refrigerant of two phases does not separate as it passes from the inlet tube to an annular channel between the outer surface of the inlet tube and 1. to the interior surface of the collector. The refrigerant flow c.e two phases therefore passes in each of the tubes opening to the annular channel. Obtaining the uniform coolant flow distribution between the relatively large number of small cross-sectional flow area coolant flow paths is even more difficult than in conventional round tube heat exchangers and can significantly reduce the heat exchanger efficiency. Its an object! It is a general aspect of the invention to reduce the maldistribution of fluid flow in a heat exchanger which has a plurality of multiple channel tubes extending between a first manifold and a second manifold. It is an object of one aspect of the invention to reduce the maldistribution of the refrigerant flow in a refrigerant vapor compression system heat exchanger having a plurality of multiple channel tubes extending between a first manifold and a second manifold.
It is an object of one aspect of the invention to distribute the refrigerant to the individual channels of an arrangement of your multiple channel DOS in a relatively uniform manner. It is an object of another aspect of the invention to provide refrigerant distribution and expansion in a refrigerant vapor compression system heat exchanger having a plurality of multiple channel tubes as the flow of refrigerant passes from a manifold to the individual channels of a multiple channel tube arrangement. In one aspect of the invention, there is provided a heat exchanger which: has a manifold defining a chamber for receiving a fluid and at least one heat exchange tube having a plurality of fluid flow through the device from one end of entrance to an exit end c.the tube and having an inlet opening to the plurality of fluid flow paths. A connector has an inlet end in fluid flow communication with the manifold chamber through a first opening and an outlet end in fluid communication with the inlet opening of at least one heat exchange tube through of a second opening. The connector defines a fluid flow path that extends from its inlet end to its end.
departure. In one embodiment, the flow path through the connector may be divergent in the direction of fluid flow therethrough. The first opening has a relatively small flow area to provide a flow restriction through which the fluid passes in flow from the collector chamber to the flow paths of the heat exchange tube, in another aspect of the flow. invention, a refrigerant vapor compression system includes a compressor, a condenser and an evaporative heat exchanger connected in refrigerant flow communication whereby the vapor of high pressure refrigerant passes from the compressor to the condenser, the cooling liquid High pressure passes from the condenser to the steam heat exchanger, and the low pressure refrigerant vapor passes from the evaporative heat exchanger to the compressor. The evaporative heat exchanger includes an inlet manifold and an outlet manifold and a plurality of exchange tubes. of heat that extend between the collectors. The inlet manifold defines a chamber for receiving liquid refrigerant from a refrigerant circuit. Each heat exchange tube has an inlet end, an outlet end, and a plurality of fluid flow paths extending from an entry opening at the entry end to a
outlet opening at the outlet end of the tube. A connector has an inlet end in fluid flow communication with the inlet manifold chamber through a first opening and has an outlet end in fluid flow communication through a second opening with the inlet opening of the fluid inlet. a heat exchange tube. The connector defines a fluid flow path that extends from its inlet end to its outlet end. In one embodiment, the flow path through the connector may be divergent in the direction of fluid flow therethrough. The first opening has a relatively small cross-sectional flow area to provide a flow restriction through which fluid passes in flow from the collector chamber to the flow path of the heat exchange tube. BRIEF DESCRIPTION OF THE DRAWINGS For a further understanding of these objects of the invention, reference will now be made to the following detailed description of the invention which will be read in conjunction with the accompanying drawings, wherein: Figure 1 is a perspective view of a embodiment of a heat exchanger according to the invention; The Figure is a perspective view,
partially in section, taken along line 2-2 of Figure 1; Figure 3 is a section elevation view taken along line 3-3 of Figure 2; Figure 4 is a sectional view taken along line 4-4 of Figure 3; Figure 5 e 3 a sectional view taken along line 5-5 of Figure 3; Figure 6 is a perspective view, partially in section, of another embodiment of a heat exchanger according to the invention; Figure 7 is a sectional view taken along line 7-7 of Figure 6; Figure 8 is a sectional view taken along line 8-8 of Figure 7; Figure 9 is a schematic illustration of a refrigerant vapor compression system incorporating the heat exchanger ie the invention; Figure 10 is a schematic illustration of another refrigerant vapor compression system incorporating the heat exchanger ie the invention; Figure 11 is an elevational view, partly in section, of an embodiment of a multistep evaporator according to the invention; and Figure 12 is an elevation view,
in some way radially and externally between the toroidal collectors. The heat exchange tubes may also be arranged in multi-pass, parallel tube modes, as will be discussed in further detail hereinafter with reference to Figures 11 and 12. Referring now to Figures 1-5 in particular, The heat exchanger 10 includes an inlet manifold 20, an outlet manifold 30, and a plurality of longitudinally extending multiple channel exchanger heat exchanger tubes 40 thereby providing a plurality of fluid flow paths between the manifold 20 entrance and the exit collector 30. Each heat exchange tube 40 has an inlet 43 at one end in fluid flow communication for the inlet manifold 20 through a connector 50 and an outlet at its other end in fluid flow communication for the manifold
30 departure. Each heat exchange tube 40 has a plurality of longitudinally extending parallel flow channels 42, that is, along the axis of the tube, the length of the tube therefore provides multiple parallel fiow trajectories, independent of the entrance of the tube. tube and the outlet of the tube. Each multi-channel heat exchange tube 40 is a "flat" tube of: rectangular or oval cross-section, which defines the interior which is subdivided to form a
side-by-side arrangement of independent flow channels 42. Flat multi-channel ducts DS 40, for example, can have a width of 50 millimeters or less, typically 12 to 25 millimeters and a height of about 2 millimeters or less when compared to conventional prior art round tubes having a width of 50 millimeters or less. diameter of 1.27 cm (% inch), 9.54 mm (3/8 inch) or 7 m. The tubes 40 are shown in the drawings of the Lsmos, for ease and clarity of illustration, as you can see 12 channels 42 defining flow paths having a circular cross section. However, it will be understood that in commercial applications, such as for example, refrigerant vapor compression systems, each multi-channel tube 40 will typically have approximately 10 to 20 flow channels 42, but may be powered. a greater or lesser plurality of channels, as desired Generally, each flow channel 42 will have a hydrau- lic diameter, defined as four times the flow area divided by the perimeter, in the range of about 200 mi roñes to about 3 millimeters. Although it is represented as having a circular cross section in the drawings > s, the channels 42 may have a cross-section of rectangular, triangular, trapezoidal or any other desired non-circular transeversal cut. Each one gives the plurality of tubes 40 of
Heat exchange of the heat exchanger 10 has its input end 43 inserted into a connector 50, instead of directly into the chamber 25 defined within the input manifold 20. Each cassette 50 has an inlet end 52 and an outlet end 54 and defines a fluid flow path 55 extending from the inlet end 52 to the exit end 54. The inlet end 52 is in fluid flow communication with the chamber
25 of the manifold 20 that enters through a first opening 51. The outlet end 54 is in fluid communication through a second opening 53 with the inlet openings 41 of the ceilings 42 at the inlet end of the tube 40. of associated thermal transfer received therein. The first opening 51 at the inlet end 52 of each connector 50 has a relatively small cross-sectional flow area. Therefore, the connectors 50 provide a plurality of flow restrictions, at least one associated with a pipe section. of heat transfer, which provide uniformity in pressure drop in the fluid flowing from the chamber 25 of the manifold 20 to the fluid flow path 55 within the connector 50, thus ensures a relatively uniform distribution of the fluid between the individual tubes 40 operatively associated with the manifold 20. In the embodiment shown in Figures 1, 2 and
3, the input manifold 20 comprises a closed-end, elongated longitudinally-hollow cylinder having a circular cross-section, The input end 52 of each connector 50 is joined with a corresponding slot 26 provided and extending through the same. the wall of the input manifold 20 with the input end 52 of the connector 50 inserted in its corresponding slot. Each connector can be welded, welded, soldered, bonded, linked by diffusion or otherwise secured in a corresponding correlation slot on the wall of the collect > 20. However, the input manifold 20 is not limited to the configuration shown. For example, the manifold 20 may comprise a hollow end cylinder, longitudinally elongated, having a transverse cut! elliptical a closed end, hollow, longitudinally elongated pipe having a square, rectangular, hexagonal, octagonal or other cross section. In the embodiment shown in Figures 6, 7 and 8, the collector 20 of eifitrada comprises a half cylinder longitudinally elongated, hollow closed end frame having a generally semicircular cross section and a block type insert 58 which is brazed, solder, s bond adhesively or otherwise secured to the averaged face of half the cylinder armor.
In this embodiment, instead of a plurality of connectors 50, the longitudinally extending block type insert 58 forms a single connector 50. A plurality of longitudinally spaced, parallel flow paths 55 are formed within the block-like structure of the connector 50. Each flow path 55 has an inlet end 52 having at least one relatively large flow area inlet opening 51. small in communication of £ '. With a fluid chamber 25 defined within the collet 20 and an outlet end 54 having an opening 53 adapted to receive the inlet end 42 of a heat exchange tube 40. Therefore, in this embodiment, a plurality of heat exchange tubes 40 are connected to a manifold by means of a single block type connector 50. The block type insert 58 provides a connector 50 having a plurality of flow restrictions with Mention is a relatively small flow area opening 51 in operative association with each heat transfer tube 40, which provides uniformity in pressure drop in the fluid flowing from the chamber 25 of the manifold 20 to the fluid flow path 55 within the connector 0, thus ensuring a relatively uniform distribution of the fluid between the individual tubes 3 operatively associated with the manifold 20.
In the embodiment shown in Figures 2, 3 and 5, only a first relatively small flow area opening 51 is provided at the input end 52 of each connector 50. However, it will be understood that, if desired, more than a first opening 51 of relatively small flow area can be provided at the input end 52 of the connector 50. For example, when the heat exchange tubes are relatively wide and / or have a relatively large number of channels, it may be desirable to have two, three or even more first relatively small flow area openings 51 disposed at spaced intervals at the input end 52 of the connector 50, as illustrated in Figures 6, 7 and 8, to ensure even flow distribution of fluid to the plurality of flow channels 42 of the tube 40 inserted into the outlet end 54 of the connector 50. The fluid flow path 55 extending from the aperture 51 of entering the inlet end 52 of the condenser 50 to the outlet opening 53 at the outlet end 54 of the connector 50, as best depicted in Fig. 3 and in Fig. 7, may deviate in the direction of fluid flow from the entrance opening 51 to the exit opening 53. A divergent flow path helps to distribute the fluid flowing through the flow path to 55 uniformly between the flow paths.
various flow channels 42 of the heat exchange tube 40 inserted into the outlet end 54 of the connector 50, particularly in coolant flow applications where the fluid is a mixture of liquid refrigerant and vapor refrigerant or is expanded to a mixture of liquid refrigerant / vapor refrigerant as the fluid passes through the opening or apertures 51 of relatively small flow area. Referring now to Figures 9 and 10, a refrigerant vapor compression system 100 is shown schematically having a compressor 60, the heat exchanger 10A, which functions as a condenser, and the heat exchanger 10B, which functions as a evaporator, connected in a closed loop refrigerant circuit by refrigerant lines 12, 14 and 16 As in conventional refrigerant vapor compression systems, the compressor 60 circulates high pressure refrigerant, hot through line 12 of the refrigerant. coolant to the inlet manifold 120, of the condenser 10A and therefore through the tubes 140 of the heat exchanger of the condenser 10A where the vapor of hot coolant condenses in a liquid as it passes in heat exchange relationship with a cooling fluid , such as ambient air the cuau. it is passed over the heat exchange tubes 140 by a condenser fan 70. He
The high-pressure liquid refrigerant collects in the outlet manifold 130 of the condenser 10A and therefore passes through the refrigerant line 14 to the inlet manifold 20 of the evaporator 10B. The refrigerant passes through the heat exchanger tubes 40 of the evaporator 10B where the refrigerant is heated as it passes in heat exchange relationship cpn the air which is to be cooled which is passed over the heat exchange tubes 40 by a fan 80 of evlaporador. The refrigerant vapor is collected in the collector 30 of the evaporator 10B and passes therefrom through the refrigerant line 16 to return the comparator 60 through the suction inlet to the same. Coolant vapor compression exemplary illustrated in Figures 9 and 10 are simplified air conditioning cycles, it will be understood that the heat exchanger of the invention can be employed in refrigerant vapor compression systems of various designs, including, without limitation, cycles of heat pump, cost savings and cooling cycles. In the embodiment shown in Figure 9, the condensed coolant passes from the condenser 10A directly to the evaporator 10B without crossing an expansion device. Thus, in this embodiment, the refrigerant typically enters the inlet manifold 20 of the
10E evaporative heat exchanger as a high pressure liquid refrigerant. , not as a refrigerant vapor / liquid mixture, fully expanded under pressure, as in conventional refrigerant compression systems. Thus, in this embodiment, the expansion of the coolant takes place within the evaporator 10B of the invention as the refrigerant passes through the opening or openings 5 of relatively small area at the inlet end 52 in the flow path 55 of the connector 50, therefore ensured that the expansion occurs only after the distribution has been achieved in a substantially uniform manner. In the modality shown in Figure 10, the condensed coolant passes through an associated expansion valve 50. operatively with the coolant line 14 as it travels from the condenser 10A to the evaporator 10B. In the expansion valve 50, the liquid refrigerant of: high pressure partially expands to the liquid refrigerant or liquid / vapor refrigerant mixture of lower pressure and lower temperature. In this embodiment, the final separation of the refrigerant is completed within the evaporator 10B as the refrigerant passes through the orifice or openings 51 of relatively small flow area at the inlet end 52 in the flow path 55 of the connector 50. The partial expansion
of the refrigerant in an expansion valve upstream of the inlet manifold 20 to the evaporator 10B can be advantageous when the cross-sectional flow area of the openings 51, can not be made small enough to ensure complete expansion as the liquid passes to the through the openings 51 or when an expansion valve is used as a flow control device, Referring now to Figure 11, the heat exchanger 10 of the invention is represented in a multistep evaporator mode. In the illustrated multipass embodiment, the input manifold 20 is divided into a first chamber 20A and a second chamber 20B, the outlet manifold is also divided into a first chamber
30A and a second chamber 30B, and the heat exchange tubes 40 are divided into banks 40A, 40B and 40C. The tubes of the first tube bank 40A have input ends inserted into the connector? 50A which open in the first chamber 20A of the inlet manifold 20 and the outlet ends open in the first chamber 30A of the outlet manifold 30. The tubes of the second tube bank 40B have input ends inserted into respective connectors 50B that open in the first chamber 30A of the output manifold 30 and the output ends open in the second chamber 20B of the input manifold 20. The tubes of the third tube bank 40C have input ends inserted in
respective connectors 50C opening in the second chamber 20B of the input manifold 20 and the outlet ends opening in the second chamber 30B of the outlet manifold 30. In this way, the refrigerant entering the heat exchanger from the refrigerant line 14 passes in heat exchange relation ccjn the air that passes over the outside of the heat intercap tube 40 three times, instead of once as in a one-step heat exchanger. According to the invention, the inlet end 43 of each of the tubes of the first, second and third tube banks 40A, 40B and 40C is inserted into the output end 54 of its associated connector 50 whereby the channels 42 of each of the tubes 40 will receive a relatively uniform distribution of liquid / vapor mixture of expanded refrigerant. The distribution and expansion of the refrigerant occurs as the refrigerant passes from the manifold to the connector through the relatively small cross-sectional flow area opening 51, not only as the refrigerant passes into the first tube bank 40A, but also as the refrigerant passes to the second bank
40B of pipe and to the third bank 40C of pipe, thus ensuring a more uniform distribution of the coolant liquid / vapor upon entering the flow channels of the pipes of each pipe bank. With reference now to Figure 12, the
heat exchanger 10 of the invention is represented in a multistep condenser mode. In the illustrated multipass mode, the input collector 120 is divided into a first chamber 1. 0A and a second chamber 120B, the salinity collector 130 is also divided into a first chamber 13 OA and one segi-nd, chamber 130B, and the heat exchange tubes 140 divided into three banks 140A, 140B and 140C. The tubes of the first tube bank 140A have inlet end openings in the first chamber 120A of the inlet manifold 120 and the outlet end openings in the first chamber 30A of the outlet manifold 130. The tubes of the second tube bank 140B have input ends inserted into respective connectors 50B that open in the first chamber 1 30A of the output connector 130 and the output ends that open in the second chamber 120B of the input collector 120. tubes of the third tube bank 140C have ends of: inlet inserted in respective connectors 50C that open in the second chamber 120B of the inlet manifold 120 and the outlet ends open in the second chamber 130B of the outlet manifold 130. In this way, the refrigerant entering the condenser from line 12 of refrigerant passes in heat exchange relationship with the air passing on the outside of the heat exchange tubes 140 - three times, instead of only once. as in a one-step heat exchanger. He
refrigerant that enters the first chamber 12 OA of the collector
Inlet 120 is vapor: of totally high-pressure refrigerant directed from the compressor outlet by line 14 of refrigerant. However, the refrigerant entering the second tube bank and the third tube bank will typically be a liquid / vapor mixture as the refrigerant partially condenses as it passes through the first and second tube banks. According to the invention, the inlet end of each of the tubes of the second and third banks 140B, 14 ?! C of tube is inserted into the outlet ends of its associated connectors 50B, 50C whereby channels 42 of each of the tubes will receive a relatively uniform distribution of the liquid / vapor mixture of expanded LR. Obviously, it will be observed that the pressure drop through the openings
51 must be limited so as not to exceed a predetermined threshold for condenser applications, so as not to compromise the efficiency of the heat exchanger. In addition, a person with ordinary skill in the art can understand that other multi-pass arrangements for condensers and evaporators are also within the scope of the invention. While the present invention has been shown and described particularly with reference to the preferred mode as illustrated in the drawing, it will be understood by someone of
experience in the art that various changes in detail can be made without departing from the spirit and scope of the invention as defined <; for the claims.