AU712817B2 - High efficiency, small volume evaporator for a refrigerant - Google Patents

Description

S F Ref: 312241D1

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT .1 I I. bq *1ee I I S *5

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ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Modine Manufacturing Company 1500 DeKoven Avenue Racine Wisconsin 53403 UNITED STATES OF AMERICA Mark G. Voss, Gregory G. Hughes, Scot T. Alley and Peter C. Kottal.

Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia High Efficiency, Small Volume Evaporator For a Refrigerant The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845 HIGH EFFICIENCY, SMALL VOLUME EVAPORATOR FOR A REFRIGERANT FIELD OF THE INVENTION This invention relates to evaporators for a refrigerant as LO used in air conditioning and/or refrigeration systems.

BACKGROUND OF THE INVENTION For many years, air conditioning and/or refrigeration systems (hereinafter collectively referred to as "refrigeration systems" or "air conditioning systems") operating on the vapor compression cycle and employed in vehicular applications utilized rather bulky and inefficient heat exchangers for both the system condenser and the system evaporator. For example, condensers were typically of the serpentine type having a single or occasionally two passes. In order to avoid excessive refrigerant side pressure drops because of the lengths of each run, the refrigerant confining tubing, typically a multi-passage extrusion, had a relatively large tube minor dimension. For any given facial area occupied by the core of the condenser, the relatively large tube minor dimension reduced the air free flow area through the core, thereby inhibiting heat transfer.

Refrigeration system evaporators were generally of three differing types. One type also was a serpentine tube construction using an extruded tube having a tube major dimension 3: that typically was on the order of four inches. The resulting S• evaporator cores were relatively deep and as a result, air side pressure drop across the evaporator was relatively high and that in turn reduced the amount of air that could be forced through the evaporator and/or required a larger fan and more energy to drive it. The relatively large tube minor dimension of the tubes used in these constructions also affected air side pressure drop adversely, exacerbating the problem. Furthermore, with such a -1 core depth, draining of condensate from the core was difficult.

As a result, condensate from the ambient air would further increase the air side pressure drop. In addition, the film of water forming on evaporator parts impeded heat transfer.

Still another type of evaporator more typically found in home refrigeration units as well as in vehicles was a so called round tube plate fin evaporator. These constructions were relatively bulky and because round tubes were utilized, the air side free flow area through the core was decreased considerably, adding to inefficiency of the unit.

Some of these difficulties were cured by resort to so called "drawn cup" evaporators. However, drawn cup evaporators still required a typical core depth of three inches and large minor dimension tubes, and as a consequence, air side pressure drop L, remained relatively high as did the inefficiencies associated therewith.

In the mid 1980's, so called "parallel flow" condensers began to reach the market for use in automotive air conditioning systems. A typical parallel flow condenser is illustrated in the SUnited States Letters Patent 4,998,580 to Guntly and assigned to the same assignee as the instant application. Parallel flow condensers utilize relatively small header and tank constructions that were highly pressure resistant and which had a plurality of flattened tubes extending between parallel headers. The flattened tubes could be either extruded or fabricated with inserts. In either event, each tube had several flow paths extending along the length thereof, each of which were of a ~relatively small hydraulic diameter, that is, up to about 0.07".

Hydraulic diameter is as conventionally defined, that is, four times the cross-sectional area of each flow path divided by the wetted perimeter of that flow path.

Substantial increases in efficiency were immediately noted.

Excellent heat transfer was obtained with units that occupied a significantly lesser volume than prior art condensers and which weighed substantially less.

It was surmised that these and other efficiencies might also be obtainable in parallel flow evaporators.

Consequently, work was performed on utilizing parallel flow type constructions with tubes having flow paths of relatively small hydraulic diameter. An example is shown in commonly assigned Hughes Patent 4,829,780, issued May 16, 1989.

This patent recognizes that whereas an efficient parallel flow condenser can be achieved using a single tube row core, to obtain a high efficiency evaporator, multiple tube rows may be required. It has also been determined that the multiple tube rows should be connected to provide a multi-pass arrangement such that the refrigerant passes two or more times across the path of air flow through the evaporator. As taught by Hughes in commonly assigned United States Letters Patent 5,205,347, issued April 27, i 1993, a counter-cross flow refrigerant flow is highly desirable.

In an example of one such evaporator, two tube rows are employed.

In the direction of air flow through the resulting core, refrigerant is inleted to the downstream most one of the tube rows to flow therethrough. After that is accomplished, the refrigerant is directed by a cross-over passage to the forward most one of the tube rows and then once again passed across the path of ambient air travel to be outleted.

9: These evaporators have worked very well for their intended purpose. For a given frontal area, the same heat transfer can be obtained with a far lesser air side pressure drop in a parallel flow evaporator than in either a serpentine evaporator or a drawn cup evaporator. Furthermore, when intended for use in vehicular 99 air conditioning systems, a parallel flow evaporator has a decided advantage because of its low volume. As is well known, an air conditioning evaporator in an automobile is typically housed under the dash. With increasing emphasis on equipping automobiles with air bags, under dash space is at a premium.

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typical parallel flow evaporator with the same efficiency as a drawn cup or serpentine evaporator and;having the same frontal area can be made with a core depth of about two inches whereas a typical serpentine evaporator would require a four inch core depth and a drawn cup evaporator would require a three inch core depth.

Not only does the parallel flow evaporator drastically reduce the volume required, leaving more space under the dash available for other equipment, the far lesser core depth translates to lesser air side pressure drop and increased efficiency either in terms of being able to have a given fan transfer more air through the core to provide greater efficiency, or in allowing a smaller fan to be used, thereby reducing energy requirements for the fan, or both.

Moreover, the lesser core depth of a parallel flow evaporator facilitates better drainage of condensate, thereby promoting efficiency on that score as well.

1 The lesser volume translates to lesser weight which is an advantage as far as vehicle fuel economy is concerned. It also translates to a lesser material cost, thereby providing a cost advantage over conventional evaporators.

While the evaporators of the Hughes patents identified above have been very successful,' they are not without their faults.

For example, distribution of refrigerant in an evaporator is extremely important if maximum efficiency is to be obtained.

Consequently, distributors are utilized on the inlet side. One such distributor is shown in the previously identified Hughes '347 patent and works well for its intended purpose. However, because it is a threaded fitting and basically requires machining of its internal passages, it is an expensive component that greatly adds to the cost of the evaporator.

Furthermore, refrigerant distribution in a cross over between the first and the second pass of the core is of substantial significance as well.

Also of importance is assuring that the incoming stream of refrigerant is uniform at the time it is delivered to the distributor. In a typical case, the refrigerant has already passed through an expansion valve or a capillary and is at a reduced pressure, and therefore, boiling. If uniformity in the incoming stream is not maintained at this time, the liquid refrigerant may tend to separate from the gaseous refrigerant and maldistribution, with accompanying inefficiency, will result.

Finally, it is highly desirable that such an evaporator be relatively simply made with a minimal number of parts so as to be of extremely economical construction to facilitate wide spread use thereof.

Summary of the Invention The present invention in one broad form provides in an evaporator for a refrigerant having at least two spaced elongated header and tank constructions, a plurality of flattened tubes extending in parallel between said header and tank constructions and in fluid communication with the interiors thereof, fins extending between adjacent ones of said flattened tubes, and a refrigerant inlet having an inlet port in one of said header and tank constructions and located intermediate the ends thereof and having oppositely directed ports aimed in the direction of elongation of the header 15 and tank construction, wherein said refrigerant inlet is defined by an inlet fixture e* S* including a piece of sheet stock including a dimple formed therein and sized to fit SeSwithin said inlet port, and two oppositely directed tabs formed in said dimple to define said oppositely directed ports, and a cover for said sheet stock fitted thereto and defining an inlet passage extending to said dimple.

The present invention in another broad form provides in an evaporator for a refrigerant having two adjacent cores, each made up of two elongated header and tank construction interconnected by flattened, parallel tubes with fins extending between adjacent fins in said cores, two adjacent header and tank constructions of said two cores :eoeI ee [N:\LIBLL]01 873:PVH comprising an inlet header and tank construction, and two other header and tank constructions being in fluid communication with one another, an inlet/outlet fixture comprising a planar metal sheet bridging said two adjacent header and tank constructions, inlet and outlet ports in said inlet and outlet header and tank constructions respectively, a dimple in said sheet and located within said inlet port, a pair of oppositely directed tabs formed in said dimple and directed generally toward respective ends of said inlet header and tank construction to define a refrigerant distributor, and an outlet port in said sheet and aligned with said outlet port.

The present invention in yet another broad form provides an evaporator for a refrigerant having at least two spaced, elongated header and tank constructions, a plurality of flattened tubes extending in parallel between said header and tank constructions and in fluid communication with the interiors thereof, fins extending between adjacent ones of said tubes, an inlet port in one of said header and tank constructions, a refrigerant distributor in said inlet port, an inlet passage having one end extending to said distributor and a connector at the end of said passage remote from said one end for connection to an incoming stream of refrigerant, said passage having a diminishing cross-section from said remote end toward said one end and a diverging cross-section at said one end.

Because of the identity of the headers, the tanks, the tubes, etc., the number of 20 parts required can be minimized. Furthermore, by locating the identical ports in central *.flats, the location of one core with respect to another can be readily interchanged S* without impeding assembly or resulting in an improperly assembled evaporator.

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o•* [N:\LIBLLlO1873:KEH 9 Description of the Drawings Preferred forms of the present invention will now be described by way of example only, with reference to the accompanying drawings, wherein: Fig. 1 is a front elevation of a parallel flow evaporator made according to the invention; Fig. 2 is a side elevation of the evaporator taken from the left of Fig. 1; Fig. 3 is a plan view of the evaporator; Fig. 4 is a view of a header and tank construction; Fig. 5 is a sectional view taken approximately along the line 5-5 in Fig. 4; Fig. 6 is a plan view of a cross-over fixture; Fig. 7 is a side elevation of the cross-over fixture; Fig. 8 is a plan view of part of a modified embodiment of a crossover fixture; Fig. 9 is a side elevation of the part of Fig. 8; Fig. 10 is an upwardly looking plan view of an inlet/outlet fixture; Fig. 11 is an inverted, side elevation of the inlet/outlet fixture; Fig. 12 is an enlarged, fragmentary view of a distributor; Fig. 13 is a plan view of the distributor; and Fig. 14 is a view of the distributor taken approximately 90° from the view illustrated in Fig. 12.

[N:\LIBLL]01873:PVH j Description of the Preferred Embodiment An evaporator made according to the invention is illustrated in the drawings and with reference to Figs. 1-3, inclusive, thereof, is seen to include two identical modules, generally designated 10 and 12 in side by side relation such that they are contacting or almost contacting. The two modules 10, 12 include a total of four header and tank constructions, generally a.

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designated 14, 16, 18 and 20. The header and tank constructions 14, 16, 18 and 20 are all identical one to the other. Elongated, flattened tubes 22 extend in parallel between the header and tank constructions 14, 16; 18, 20 of each module 10, 12 and are in fluid communication with the interiors thereof as will be seen.

The tubes 22 are identical one to another and typically will either be extruded tubes or fabricated tubes having multiple internal passages of relatively small hydraulic diameter, that is, up to about 0.07". Hydraulic diameter is as conventionally defined.

Identical side pieces 24 interconnect the header and tank constructions 14, 16 and 18, 20 of each module 10 and 12 of both sides thereof. Serpentine fins 26 extend between adjacent ones of the tubes 22 and between the side pieces 24 and an adjacent tube 22 and are bonded thereto.

A cross-over fixture, generally designated 30, interconnects and places the header and tank constructions 14 and 18 in fluid S communication with one another. The lower header and tank constructions 16 and 20 serve as inlet and outlet header and tank construction respectively. An inlet/outlet fixture, generally designated 32, is mounted on the header and tank constructions 16 ~and 20 and establishes a connection of a conduit 34 to the inlet header and tank construction 16. The conduit 34 is adapted to receive refrigerant from a source thereof. Typically, the conduit 34 will be connected to the outlet side of an expansion valve or capillary of a conventional construction as is typically employed in a refrigeration system.

The inlet/outlet fixture 32 also establishes fluid communication between a conduit 36 and the outlet header and tank construction 20. The conduit 36 will ultimately be connected to the suction side of the system compressor to deliver refrigerant in the vapor phase thereto. Typically, the vapor will be somewhat superheated.

Turning now to Figs. 4 and 5, the header and tank constructions 14, 16, 18 and 20 will be described. Firstly, it should be understood that each is identical to the other so as to minimize the number of parts required to make the evaporator.

Essentially, each header and tank construction 14, 16, 18 and 20 is made of two components. The first is an elongated header plate 40 and the second is a tank 42. The header plate includes a plurality of elongated slots 44 along its length as best seen in Fig. 4. The slots 44 sealingly receive the ends of the flattened tubes 22 as is well known.

As seen in Fig. 5, between each of the slots 44 there is located a pressure dome 46. As can be seen in Fig. 2, each header plate 40 has a curved appearance when viewed at right angles to the view taken in Fig. 5. Thus, each of the pressure domes 46 is formed as a compound curve to provide improved resistance to pressure caused deformation that might cause cracking or rupturing of the joints between the tubes 22 and the header plates 40. The construction is generally as described and commonly assigned United States Letters Patent 4,615,385 issued R0 October 7, 1986 to Saperstein, et al., the details of which are herein incorporated by reference.

Each header plate 40 includes a peripheral flange 48 and the tank 42 is nested within the flange 48. The tank 42 also includes a peripheral flange 50 which is sized to fit snugly within the flange 48 so that the interface of the two flanges 48 and 50 may be sealed by a brazing operation or the like.

Centrally of the tank 42, from the standpoint of both its sides and its ends, is a recessed flat surface 52. On either side of the flat surface 52, the tank 42 is somewhat crowned as can be seen at 54 in Fig. 2.

Exactly centrally of each of the recessed flat surfaces 52 is a port 60. The port 60 is circular in configuration and essentially lies in a plane that is parallel to the nominal plane of the header plate Figs. 6 and 7 illustrate the cross-over fixture 30 in greater detail. As can be seen in Fig. 7, the same includes a flat or planar plate 70 having a peripheral, upturned flange 72.

The plate 70 includes first and second identical openings 74, 76 which in turn are surrounded by peripheral flanges 78 and The opening 74, 76 are circular as are the flanges. The flanges 78 and 80 are used to locate the plate 70 in the ports 60 of the tanks 42. The fit is a loose one. The loose fit is such that conventional brazing of the outer surface of the plate 70 to the surface 52 of the tanks 42 will generate a seal thereat.

From Fig. 6, it can be appreciated that the plate 70 is symmetrical about a line drawn through the centers of the openings 74, 76.

The cross-over fixture 30 is completed by a second plate 82, which is nested within the upturned flange 72 of the plate 70 and sealed thereto by brazing. A downwardly facing, generally "0" shaped recess is formed in the plate 82 to define a cross-over S passage extending between the openings 74 and 76. As seen in 0000 S Fig. 6, the recess is generally designated 84 and includes an F26' arcuate upper segment 86 and an arcuate lower segment 88 which are connected to one another at respective ends by hemispherical formations 90 and 92 which are located so as to overlie the openings 74 and 76.

Thus, the cross-over passage defined by the recess 84 has two branches. The purpose of this configuration along with the purpose of recessing the flat surfaces 52 on each of the tanks 42 is to reduce the profile of the evaporator so as to minimize the 0 space required for it under the dash of an automobile or the ~like, or in any other installation where it may be used. More particularly, by utilizing two, low profile passage segments 86, 88, the same free flow area between the openings 74, 76 may be obtained with a recess 84 of lesser depth.

Figs. 8 and 9 show a part of a modified embodiment of a crossover fixture wherein the refrigerant crosses over as a single stream. A plate 90 corresponding to the plate 82 includes an elongated, semi-hemispherical recess 92 through which the refrigerant may flow. The plate 90 is sealed to the plate (Figs. 6 and 7) by brazing just as the plate 82.

As can be ascertained from the geometry of the components as described in Figs. 1-3, boiling refrigerant is first introduced into the header and tank construction 16 from which it flows through the tubes 22 to the header and tank construction 14. At that point, it will utilize the cross-over fixture 30, flow to the header and tank construction 18 and then return through tubes 22 of the module 12 to the inlet/outlet fixture 32 and the conduit 36. The configuration of the cross-over fixture illustrated ensures that the refrigerant, as it passes from the header and tank construction 14 to the header and tank construction 18, undergoes a change in direction of travel of a i. nominal 1800. It also insures that the incoming refrigerant directed into the header and tank construction 18 enters in the nominal direction of elongation of the tubes 22, that is, nominally at right angles to the plane of the header plate 40 of 0* the header and tank construction 18. It has been determined that greater uniformity of refrigerant flow, and thus, greater efficiency of the evaporator operation, can be achieved by directing incoming refrigerant between passes in the direction of elongation of the tubes 22; and this is a feature of the present invention.

rThe inlet/outlet fixture 32 is illustrated in Figs. 10 and 11 and is seen to include a generally flat or planar plate 100 provided with a peripheral flange 102. A cover plate 104 is nested within the flange 102 and is sealed thereto as by a e brazing operation.

The plate 104 has two downwardly opening recesses 106 and 108 stamped in it. Both of the recesses 106 and 108 are elongated and the recess 106 is of uniform cross-section along its length. Conversely, the recess 108 converges as shown in the area marked 110 as one progresses from -an end 112 of the recess 108 toward the opposite end 114. The recess 108 enlarges or has diverging walls at or approaching the end 114. The convergingdiverging configuration of the recess 108, minimize flow separation in the incoming refrigerant to improve efficiency.

It will also be appreciated that the recess 106 is straight while the recess 108 is curved.

The plate 100, at a location aligned with an end 116 of the recess 106, includes a circular opening 118 surrounded by a peripheral flange 120. The opening 118 is a connector adapted to receive an end of the conduit 36.

The opposite end 122 of the recess 106 overlies a circular opening 124 having a circular peripheral flange 126. The outer diameter of the flange 126 is about equal to the inner diameter of the port 60 so as to be receivable in the port 60 associated with the tank 42 in the header and tank construction 20 of the ib module 12 and be sealingly brazed thereto.

S. The plate 100, at a location underlying the end 112 of the recess 108, includes a circular opening 130 surrounded by a peripheral flange 132 (Fig. 1) which acts as a connector for receipt of the inlet conduit 34.

The plate 100, at a location underlying the opposite end 114 of the recess 108 includes a distributor, generally designated S 140.

a.The distributor 140 is illustrated in enlarged detail in Figs. 12, 13, and 14. The same is basically in the form of a hemispherical dimple 150 formed in the plate 100 by stamping.

Where the hemispherical dimple 150 merges with the plane of the plate 100, the diameter of the dimple 150 is slightly less than the inner diameter of the port 60 in a tank 42 so that the dimple *aa ~150 may freely enter the port 60 in the tank 42 forming part of the header and tank construction 16.

The dimple 150 may be formed by stamping. It is also provided with two oppositely directed tabs 152 and 154. The orientation of the tabs 152 and 154 is such that they are directed in the direction of elongationof the header and tank construction 16. As can be seen in Fig. 13, each of the tabs 152 and 154 has a pair of parallel side edges 156 and 158 connected by a curved edge 160. The dimple 150 is imperforate between the tabs 152 and 154. The result is to generate a relatively rectangular opening 162 beneath each tab 152 and 154. It will also be observed that the dimple 150 remains intact beneath the openings 162 in the area designated 164, generally for a distance equal approximately to the thickness of the tank 42.

In some instances, it may be desirable to not only employ the dimple 140 in the inlet to the module 10, but in the crossover inlet to the module 12 as well. In such a case the distributor 140 as described can be formed in the plate 70 (Fig.

7) at the appropriate one of the openings 74 or 76.

Preferably, all components are made of aluminum and where surfaces are to be joined and/or sealed, one or the other or both 1b of such surfaces will be braze clad. The evaporator lends itself to an assembly operation including brazing by the so called Nocolok® brazing process.

In the usual case, the assembled evaporator will have a core depth on the order of about two inches or less, considerably less than conventional evaporators, thereby providing a substantial volume savings. Moreover, the small size of the evaporator of the invention means a material savings and a weight savings as well. The latter, in automotive installations, translates to an energy saving by reason of weight reduction. Similarly, the relatively small core depth provides an energy savings and/or enables the use of a smaller fan and/or enables operation at an increased efficiency.

The use of identical components in many locations minimizes the number of different parts required. Thus, the evaporator requires one type of tank 42, one type of header plate 40, one type of tube 22, one type of serpentine fin 26, one type of side piece 24, a two piece cross-over fixture 30 and a two piece inlet/outlet fixture 32, for a total of only nine components of differing geometry.

j Furthermore, by locating the ports 60 at the center of the tanks 42, the various modules 10 and 12 may be assembled together in any orientation because the fixtures 30, 32 are configured to connect to any two adjacent tanks. This feature minimizes the possibility of human error in the assembly process because it is virtually impossible to improperly assemble the components together unless one omits a part altogether.

The unique cross-over fixture 30 provides an increase in efficiency by directing refrigerant from an upstream core or module to a downstream core or module such that the refrigerant enters the latter in a direction nominally parallel to the tubes for uniform distribution.

In addition, the dual passage configuration provides a reduction in profile of the entire apparatus.

The inlet/outlet fixture 32 provides a number of advantages.

The distributor formed by the tabs 152 and 154 in the dimple 150 provides an inexpensive, but highly efficient distributor to V. ~increase efficiency of the evaporation procedure. Because it is formed by stamping and punching in a sheet of metal, its cost is :ago. extremely low. Further, the configuration of the recess 108 which converges in the direction away from the connection to the source of refrigerant and then diverges at or approaching the distributor 140 assures that a highly uniform stream of refrigerant is directed to the distributor 140 in spite of the fact that the refrigerant is already boiling and is in part in the vapor phase and in part in the liquid phase.

Consequently, a highly efficient evaporator ideally suited for commercialization is provided.

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Claims (15)

1. An evaporator for a refrigerant having at least two spaced elongated header and tank constructions, a plurality of flattened tubes extending in parallel between said header and tank constructions and in fluid communication with the interiors thereof, fins extending between adjacent ones of said flattened tubes, and a refrigerant inlet having an inlet port in one of said header and tank constructions and located intermediate the ends thereof and having oppositely directed ports aimed in the direction of elongation of the header and tank construction, wherein said refrigerant inlet is defined by an inlet fixture including a piece of sheet stock including a dimple formed therein and sized to fit within said inlet port, and two oppositely directed tabs formed in said dimple to define said oppositely directed ports, and a cover for said sheet stock fitted thereto and defining an inlet passage extending to said dimple.

2. The evaporator of claim 1 wherein said dimple is. generally hemispherical and each said tab has a pair of spaced parallel edges extending toward a side of said dimple and a partial circular edge interconnecting said parallel edges.

3. The evaporator of claim 2 wherein said dimple is imperforate between said tabs.

4. The evaporator of claim 1 wherein said dimple is formed by stamping said sheet stock and said tabs are formed by punches acting on said dimple.

5. The evaporator of claim 1 wherein said one header and tank construction includes a flat surface in which said inlet port is located and said sheet stock piece is generally planar.

6. The evaporator of claim 1 having two adjacent cores, each core being made up of two said header and tank constructions and interconnected by said parallel, 25 flattened tubes with fins extending between adjacent tubes in each core, two adjacent header and tank constructions comprising inlet and outlet header and tank constructions and two other adjacent header and tank constructions being in fluid communication with each other, said inlet port being in said inlet header and tank construction and an outlet port in said outlet header and tank construction, said sheet stock being planar and further including an outlet port in said sheet stock and aligned with said outlet port.

7. The evaporator of claim 6 further including a cap fitted to and sealed against said sheet oppositely of said dimple, said fixture having means for receiving inlet and outlet lines and connecting them respectively to said dimple and said outlet port.

8. The evaporator of claim 7 wherein said cap is a stamped sheet and includes two recesses formed therein and facing said planar sheet, one of said recesses Sextending to said dimple and the other extending to said outlet port. [I:\DayLib\LIBLL]01873.doc:KEH I 19

9. The evaporator of claim 8 wherein said one recess has a relatively wide end at said dimple and an opposite wide end, and is of diminished cross-section between said ends. The evaporator of claim 6 wherein said other header and tank constructions are in fluid communication by means of a cross-over passage extending therebetween, said cross-over passage directing refrigerant into the core having said outlet header and tank construction in a direction generally parallel to said tubes.

11. The evaporator of claim 1 including an inlet passage having one end in fluid communication with said dimple and a connector at the end of said passage remote from said one end for connection to an incoming stream of refrigerant, said passage having a diminishing cross-section from said remote end toward said one end and a diverging cross-section at said one end.

12. The evaporator of claim 11 wherein said passage is curved intermediate its ends.

13. The evaporator of claim 11 wherein said passage is defined by two plates bonded and sealed to one another, one of said plates being generally planar and having said dimple, the other of said plates, on the side thereof facing said one plate, having a recess formed therein, said recess together with said one plate defining said passage. 20

14. The evaporator of claim 13 wherein said dimple is stamped in said one plate to extend from the side thereof opposite said other plate.

15. The evaporator of claim 14 wherein said dimple is stamped in said one .plate and with two oppositely directed tabs punched in said dimple. Dated 22 September, 1999 Modine Manufacturing Company ~Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON S• :go o•S [I:\DayLib\LIBLL]O1

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