US2341132A - Mechanical refrigerating system - Google Patents

Description

1944- R. w. wA'rERFlLL MECHANICAL REFRIGERATING SYSTEM Filed Aug. 3/ 1940 4 Sheets-Sheet 1 INVENTOR W MMM 2M, 21 w ATTORNEYS.

Feb. 8, 1944. R. w. WATERFILL MECHANICAL BEFRIGERATING SYSTEM Filed Aug. 5, '1940' 4 Sheets-Sheet 2 INVENTOR ATTORNEYS.

Feb. 8, 1944.

R. W. WATERFILL MECHANICAL REFRIGERATING SYSTEM Filed Aug. 3, 1-940 4 Sheets-Sheet 3 w ooooooo/oomwp 0 0 o $0 0M Q.ww ooo oo o o a? r, i wwz w w fi ,O J 1 0 1 01% 600000 00 EU o hwo o o m ooooii w m m m 0 o 0 0 o 0 0 0 0 9 iw-WJ IP 0o oooooooQo N M O o o oooo oo ooo w A INVENTOR WM M fig 7 3? ATTORNEYS.

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4 Sheets-Sheet 4 @N O MW O JO O O O R. W. WATERFILL Filed Aug. 3, 1940 ATTOR N EYS o0 aooqoo o o m OO 30m 0 0 0 000 om OOOOOAYQO OO 000; o o 0 0 0 o ooo O o w MECHANICAL REFRIGERATING SYSTEM Feb; 8, 1944.

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Patented Feb. 8, 1944 rQM EDh T PATENT E,

v I 2,341,132 MECHANICAL nnrmemmrme SYSTEM Robert W. Waterfill, Montclair, N.- J., assignor to Buensod-Stacey, Incorporated, a corporation of Delaware Application August a, 1940, Serial No. 350,785

13 Claims.

This invention relates to improvements in mechanical refrigerating equipment.

The principal object of the invention is to simpllfythe construction and operation of mechanical refrigerating systems, particularly those of the low-pressure class, to render such systems more compact and of lesser weight as compared with prior structures of equal refrigerating capacity, to arrange the components of such systems in a way which will facilitate manufacture as well as servicing of the equipment after it has been installed, to. minimize the quantity compression, and a driving motor, which is adapted to be housed in one end of a casing whichalso serves as the shell of the evaporator end of a casing which serves as the shell .of a

shell-and-tube evaporator. for the system, and the other in a casing which serves as a part of the condenser of the system.

Yet anotherobject of the invention is to do away with troublesome and expensive pumping units and other accessories such as are commonly employed at the present time in lowpressure refrigerating systems for withdrawing [liquid refrigerant from the base of the shell and for showering it over the tube bank of the evap- "A further object of the invention is to pro- [vide a shell-and-tube evaporator of the nonfiooded type, that is to say,one wherein the tube It is a still more specific object of the lnven tion .to. provide an evaporatorof' the foregoin character with means which serve to confine vapor generated in the lower part of the tube bank in such a way as to cause that vapor to assist in the general circulation of t refrigerant throughout the tube bank. v

The foregoing and otherobjects, as well as various features of the invention, will be more fully understood from a. consideration of the,

following description whenread in the light of the accompanying drawings, in which- Figure l is an elevational view of the complete mechanical refrigerating system of the-present 5 invention, certain parts thereof being broken away better to show' underlying ones;

Fig. 2 is an elevational view, partly illzSGCtiO and on an enlarged scale, of the compressorevaporator unit of Fig. 1, and particularly illus-z trating the construction of the evaporator;

, Fig. 3 is a sectional view, on an enlarged scale, of a fragment of the first stage of the first compressor unit of Fig. l; v

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 2, and on an enlarged scale, to-show certain details of the evaporator construction;

Fig. 5 is a plan view, again on an enlargedevaporator of Fig.2; and

Fig. 6 is a cross-sectional view of a modified scale, of a fragment of'the, tube bank: of the form of evaporator adapted to be used asa'p'art of the system of Fig. l. v

In the drawings, and referring first to Fig. l, numeral l0 designates a casing which preferably is of cylindrical form having legs ll adapted to rest upon any appropriate foundation-sonnet the casing may serve as the effective ba e of the machine. One end portion of this casing (Fig; 2) houses a bank of tubes I2 which, asmay be seen, are provided with a'large number of surface extending fins l3, and are interconnected with a water-box I4. This end portion of casing it accordingly serves as the shell ofthe evaporator of the system in which refrigerant liquidmay be vaporized to abstract heat from water or any other desired medium circulated through the tube bank. p

The first compressor unit l5, comprising com pressor stages A and 13, their common driving In the preferred construction, a second casing l8, again of cylindrical form, is mounted atop 55.

second casing having legs l9 welded or otherwise secured to its underside and resting upon similar legs 20 aflixed to the upper part of casing Ill. The second compressor unit 2| of the system, 0 including compressor'stages C and D, their commotor [6 and accessories, is housed in the other the combination evaporator-compressor unit, the

mon driving motor 22 and accessories, is housed in one end of casing 18 immediately above the first compressor unit l5 in casing lflfand the end of casing i8 is. covered by a manifold 23. When the system is operating, the partially compressed refrigerant vapor discharged from stage B of the first compressor unit passes through manifold M, fitting 24, and manifold 23 into stage C, is further compressed therein, and is then discharged over and through the motor 22 to cool that element. The last stage, D, withdraws partially compressed vapor from that part of casing I! which serves as a housing for the second compressor unit, raises the pressure of the vapor to a desired final value, and discharges it into the remaining portion of easing [8.

The last-mentioned casing portion is adapted to serve as the shell of the condenser of the system, and in it is housed a bank of tubes 21 which carry a large number of surface extending fins 23 and have their ends interconnected with the water-box 29. Accordingly, the compressed vapor discharged from stage D passes over the bank of tubes, gives up its heat to water circulating through the bank, and is condensed, the resulting refrigerant collecting in the base of the shell (casing l8), whence it may be returned to the evaporator through conduit 3! for re-use.

The refrigerating machine which has been generally described above is primarily designed to operate with one of the so-called low-pressure refrigerants, such as trichloro-trifiuoro-ethane or the like. These substances, as is well recognized in the art, are almost ideally suited to centrifugal compression. Accordingly, each of the compressor units l5 and M includes two stages of centrifugal compression each comprising an impeller adapted to be driven directly by the motor of the unit, and a diffuser surrounding the impeller,

the latter element serving in the well-understood manner to convert the velocity pressure of vapor issuing from the impeller into a static head. These two units are so nearly identical in basic design that a consideration of one of them will sumce to bring out the features of both and the manner in which they are mounted in their respective casings. For this purpose the first compressor unit I5 and its mounting in the evaporator casing Ill will be described in detail.

In assembling the unit I5, and starting with stage A, the inner half 32 of the diffuser (generally designated 33) is slipped over the shaft 34 of motor l5, and its flange 35 is bolted at 35 to a flange 31 of the motor casing. It will be seen that the flange 35 is formed at the rear end of a spider 38 which comprises an integral part of the diffuser, element 32, and that this spider has a series of openings 33 through which some vapor may pass from the outlet 40 of the diffuser through and over the windings of the motor I to cool those parts. If it has not already been set in place, the gland 42 (Fig. 3) is slipped over the shaft 34 and is bolted at 43 to the difluser element 32 to provide a labyrinth packing around the shaft at this point.

The impeller 44 is next fitted and keyed to the shaft,'and a spanner nut 45 is applied to the end of the shaft to hold the impeller in place. It will be noted (Fig. 3) that this nut has smoothly rounded surfaces which complement those of the impeller, whereby friction between the refrigerant vapor and the impeller may be minimized. After the impeller has been mounted, the outer half 45 of the diffuser 33 can be fitted in place, and bolted to the inner half 32 at 41.

Finally, the inlet guard 48 is bolted or otherwise secured to the diffuser element 45. It will be noted at this point (Fig. 3) that the surface of the inlet guard is smoothly rounded, and is so designed as to complement the adjacentsurfaces of the inlet of the impeller-all to the end that friction between the refrigerant vapor and the parts of the machine may be kept as low as possible. While the inlet guard must not touch the impeller, the clearance between these parts is small, and the guard is provided with a series of labyrinths 49 which effectively prevent the shorteircuiting of any substantial volume of vapor from the discharge of the impeller 44 around the inlet guard to its inlet.

The assembly of stage 13 of the unit is quite,

similar to that of stage A. Specifically, and referring to Fig. 1, the inlet guard 5| is first applied to the inner half 52 of the diffuser (generally designated 53), that inner half is slipped over the motor shaft 34, and its flange 54 is bolted at 55 to the flange 56 of the motor casing. Here, again, it will be noted that the flange 54 is spaced from the main body of the diffuser by a spider, the spaces between the arms 51 of the spider again allowing for the flow of vapor through the motor windings and into the second stage impeller. The impeller 58 is then fitted and keyed to the shaft 34, and a nut 59 is applied to secure the impeller in place. When this has been done, some adjustment of the inlet guard 5| may be needed to insure that the guard and the impeller do not touch. Here, again, the outer surface of the guard is smoothly rounded to complement the surface of the impeller inlet; and the guard is provided with labyrinths to restrict the flow of vapor between that guard and the adjacent surface of the impeller. The assembly of the compressor unit I5 is completed by the application of the outer half 60 of the diffuser, this element being bolted at 5| to the inner half 52 (Fig. 1).

It is evident that the first compressor stage A must handle a larger volume of refrigerant vapor than the second stage B, the volumetric difference being accounted for by the fact that the vapor is partially compressed in the first stage before it is delivered to the second stage. Accordingly, and as is shown in Fig. 1, the diffuser 33 and the impeller 44 of stage A are somewhat larger than the like parts of stage B.

It will be noted that the two impellers are mounted directly upon the motor shaft and are supported by the bearings for that shaft (not shown). Each of these bearings is provided with an independent lubricating system 52, which may be constructed in accordance with the disclosure of copending application Serial No. 232,580, filed September 30, 1938 (now patent No. 2,266,107, dated December 16, 1941). Reference may be had to that application for more complete details of the lubricating system and its manner of operation. The prime difference between the system there disclosed and the one here shown lies in the fact that the oil-settling chambers 53 are mounted directly upon the frame of the motor l6, rather than upon the casing of the unit.

The assembled compressor unit i5 is of such size and shape that it may readily. be passed through the open end of easing Ill, and he slipped along rails 54 which serve both to guide and to support it until the marginal flange 55 of the diffuser element 32 of, stage A (Fig. 3) forces a packing ring 55 into engagement with an annular flange 61 formed on the inside of casing H). The

. to": form a leaktight joint between the compressor Qunit 'and that part of casing III which serves as hell of the evaporator of the system. Finally, the? manifold I! may be bolted in place, as indicated at 1I, to cover the end of the casing.

The manhole I2 (Fig. 2) gives access to the inside of the casing III after the compressor unit has been inserted for making the necessary electric'alconnections of the motor I6, and for connecting pipes 13 and "leading from the settling chambers 63 of the oiling systems to the bull's- :eyes 15which are mounted on casing I0. These 'b ills-eyes give a visual indication of the quantity of oil in the lubricating systems. This oil may be supplied in the, first instance, or more may be added, through filling cups I6 which are connected with the bulls-eyes through pipes 11, and, accordingly, with the lubricating systems through the above-mentioned pipes 14. Whenall of the internalconnections have been made, the cover 18 may be applied to the casing over the manhole 12 to seal the unit at this point.

The basic design of the second compressor unitZI is quite similar to that of the first unit l5, as has already been pointed out. These differences, however, should be noted. 'Stage ,0 of the second unit is assembled in substantially the same manner as stage A of the first unit; and the assembly of stage D follows that of stage B. Here, again, it will be evident thatthe stages are of progressively decreasing volumetric capacity, the impeller I9 andthe diffuser 30 of the third stage C being of somewhat lesser diameter than the comparable parts of the second stage B, and the.

impeller ill and the diffuser 82 of the fourth stage D being of lesser diameter than the comparable parts of the third stage C. c The completely assembled unit 2| may be insorted through the open end of easing I3, and the procedure is much like that followed in mounting the first compressor. unit IS in the evaporator casing I0. The diifuser 890i stage C has a flange 83, which is comparible in function to the flange 930i stage B, whereby it may be bolted to an end flange 84' of the casing l8, and the diffuser B2 of stage D has a right-angle flange 85 at its edge which is'cornparableIto the flange 65 of diffuser element 32 of stage A. Accordingly, the bolts 86 serve to drive the entire unit into the casing, and to cause flange 86 to compress a gasket 81 against an annular internal flange 88 formedlon the casing I8 to form a leak-tight joint at that point. The manifold 23 may then be,

b01ted;-:'at 90 to the end of casing I8.

When the foregoing steps have been completed, 60 I the electrical connections may be made to the nor the manhole and its cover are shown in the drawings, but these parts-may be identical with the comparable ones shownv in Fig. 2, and furtherillustration and description are unnecessary.

The various constructional differences between the two compressor units and their individual stages are well illustrated in the drawings and need not be further described.

45 which lies inside of bend I00.

which the manifolds I1 and 23 are bolted in' place. The manifolds may then be connected by the fitting 24, which preferably comprises a section of copper or brass tubing having flanges at its ends for connection to the flanges of the caps l1 and 23, and a peripheral fold at some point between its ends. The fitting is thus adapted to serve as an expansion point between the two compressor units, the fold collapsing or extending to take up an expansion or contraction of the various parts.

The details of the evaporator are well illustrated in Figs. 2, 4 and 5. In that structure the tube bank I2 includes a bundle of tubes 93 having plate fins I3 applied at closely spaced intergo vals to increase their heat-transfer surfaces. It

is evident, however, that spiral-finned tubing, or any form of extended heat-transfer surface, may

be used in building up the bank.

The individual tubes 93 are interconnected by 25 return bends at one end of the bank I2 whereby -all supply and discharge connections may be made from the other end of the bank. These bends may be applied to the tubes in such a way as to define two or several liquidpasses, according to the needs of the case.

" 96. -The fifth and eighth tubes of this row are connected by return bend 98; and the sixth, and seventh tubes by band 99. A specific description of the interconnection of the remaining tubes of the first row is unnecessary since. it is readily evident from Fig. 5.

, The tubes of the second row lie between those of the first (see Fig. 4) In this row, return bend IIlIljolns the firstzand fourth tubes; and the sec- 0nd and third tubes are connected by bend IIII, The fifth and sixth tubes are connected by bend I02; and the remaining tubes of the second row are similarly a joined together. The application of return bends to the third, fifth, seventh, etc., rows follows that of the first row; and the tubes of the fourth,

sixthf**eighth, etc., rows are interconnected precisely-as are those of the second. It is of course evident that other forms of interconnection of the tubes may be employed if desired.

It will be noted (Figs. 4 and 5) that the tubes 93 are so arranged as to divide the bank I2 into two distinct sections, and to leave a passageway- IM extending vertically and longitudinally through its center. In the illustrated embodiment the two sections are spaced apart by the channels I05, and by a pair of plates I03 which are disposed along the edges of the fins adjacent the bottom of the bank. It is through the peasageway I04 that liquid refrigerant is introduced 55 into the bank and is distributed over its surfaces in a manner later to be considered.

- Zilrof the tubes, their fins, the channels, plates,

etc., are bound together by the end plates I01, the intermediate supporting plates I08, and the tube sheet I09 (Figs. 2 and 5). The bank I2 may,

accordingly, be slipped as a unit through the opening in the end wall III of easing Ill along rails II2 which serve both to guide the bank and to support it; and the bank is secured in place It is the usual practice in assembling a refrigby the bolting-on of' the water-box I4.

The other constructional details of the evaporator may best be understcod from a consideration of the operation of that device. Thus. and referring to Figs. 2 and 4, liquid refrigerant returning from the condenser of the system through line 3I passes into a conduit II3 which, in the illustrated structure, is welded to the underside of the casing I0, and, through a series of orifices I I4, into the base of the casing. These orifices are located immediately beneath the passageway I04 through the tube bank I2. The introduced liquid is thus directed through the pool of refrigerant already in the base of the shell and into the passageway I04. Its flash gas generates a froth of the liquid in the pool, which, being lighter than the liquid, rises into the passageway. There the vapor is confined by the channels I05 and the plates I08 so that it be-- comes most effective in lifting the liquid.

When the froth passes over the edges of the plates I06,'it begins to spread sidewise. Immediately some of its liquid component is evaporated by heat transfer with the water flowing through tubes 93. At this point it will be noted that the plates 95 are arranged along the outer sides of the bottom portion of the bank. These plates serve primarily to confine the vapor generated in the lower portion of the bank, and to prevent its immediate escape through the sides of the bank. Some of the vapor finds a path for escape by flowing back toward the central passageway I04, where it augments the vapor already present and assists in lifting the froth through the passageway; the ramainder flows up through the bank and assists in the circulation of liquid therethrough.

A portion of the liquid and vapor, which rises all of the way tothe top of the passageway I04, blows against baffle H5 and is directed .by that element to the sides of the tube bank, so that its liquid content may flow downwardly over the outer tubes to keep them thoroughly wetted.

Excess liquid drains from the tubes and their flns into the pool in the base of the casing, whence it may be recirculated through the bank in the manner just described. In this connection it will be noted that the vertical parts of the plates 95 extend almost, but not quite, to the surface of the casing I0, so that excess liquid may fiow under their edges whenever necessary.

Refrigerant vapor passes off through the top and the upper sides of the bank, and flows through an eliminator IIB (Fig. 2) which is supend of the evaporator proper, and a second crossplate IIO which depends from the top of the easing. This eliminator is of more or less usual construction and, of course, serves the conventional function of separating vapor from any entrained droplets of liquid, allowing the former to pass to the inlet of impellent 44 of stage A of the first compressor unit, and the droplets of liquid to fall back into the base of the shell on the evaporator side of the partition II.

The system may be charged with refrigerant through valve I34 and. pipe I35 (Fig. 2). In order that these elements may also be used for draining the system, whenever that becomes necessary, the pipe has its lower end disposed in a sump I30 which is formed on conduit ,,I I3, ,the lowest point in the system.

A modified form of evaporator, constructed and designed to operate in accordance with the principles of the invention, is illustrated in Fig.

ported between a cross-plate II'I, defining the two vertical passageways I22 extending for its full length and height, and beneath each of them is a series of orifices I23 formed in the deckplate I24 which defines the effective base of the shell I25. In operation, liquid refrigerant returning from the condenser through conduits I28 is directed upwardly from these orifices through the pool of refrigerant collecting on the deck-plate, and into the passageways I22.

Here,'again, the incoming refrigerant provides an initial volume of flash gas to generate a froth of the liquid in the pool, and to start circulation of liquid and vapor through the passageways I22. Some of the liquid and vapor will rise all of the way to the top of the bank and strike against the baflles I2I which break up the froth and throw the liquid to the sides of the bank where it may flow downwardly over the tubes I28 and fins I29, while other portions of the froth spread sidewise over the edges of the confining plates I30 and through the bank; Any vapor generated in the lower portions of the bank is confined by side plates I3 I. Since it cannot immediately escape through the sides of the bank, it must pass upwardly to assist in the circulation process.

The construction of the condenser tube bank 21 need not be considered in great detail. Sufllce it to say that the various tubes are assembled with their plate fins 23 (other forms of the extended surface may, of course, be employed, if desired), and the individual tubes are interconnected at one end of the bank by return bends I3I so that all outside supply and discharge connections may be made from the other end of the I bank; and. the tubes, fins, etc. are bound together by appropriate end plates I38, intervening supporting sheets (not shown) and by the tube sheet I32. The entire bank is of such size and shape that it may be slipped as a unit through the end of easing I8 along rails I33 which serve both to guide and support it; and the bank may be secured in place to the casing I8 by the bolting-on of the water-box 29.

Since certain changes may be made in the construction of the refrigerating unit as a whole, the arrangement of its constituent parts, and in its operation, the foregoing is intended to be construed in a descriptive rather than in a limiting sense.

What I claim is:

l. A shell-and-tube refrigerant evaporator of the type wherein the tube bank is not submerged in liquid refrigerant, such evaporator compris-.

ing a shell adapted to serve as a part of a closed path for a refrigerating fluid, a bank of tubes adapted to serve as apath for a fluid to be cooled, some of said tubes being spaced apart to leave a substantially clear passageway extending vertically and longitudinally through the bank, and means for introducing liquid refrigerant into the base of said shell, said means being adapted to distribute the introduced refrigerant lengthwise of said bank and to direct liquid refrigerant and flash gas upwardly into the passageway of the bank, said passageway being of such proportions as to confine tneflash gas laterally whereby to cause it to lift liquid refrigerant through said passageway and to distribute it over said tubes.

2. A shell-and-tube evaporator according to I claim 1, further characterized by the provision of means for confining laterally vapor which is 6. In this arrangement the tube bank I2I has 7 generated in the 10We1 Part of the bank whereby to cause that vapor to rise through the bank and through said passageway.

33. A shell-and-tube evaporator according to claiml, further characterized by the provision of fins on said tubes, and plates extending along the sides of the tube bank, said plates serving to confine any vapor which is generated in the lower part of the bank whereby to constrain that vapor to fiow upwardly through said bank and through said passageway.

4. A shell-and-tube evaporator according to claim 1, further characterized by the provision of a pair of plates arranged along the sides of said passageway near the bottom of said bank, said plates serving to confine laterally flash gas which is directed into the passageway whereby such gas may serve to lift liquid through the passageway; and by the provision of other plates extending along the sides of the tube bank, said other plates serving to confine laterally vapor which is generated in the lower part of the bank whereby to constrain it to pass upwardly through said bank and said passageway.

5. A shell-and-tube evaporatorv according to claim 1, further characterized by the provision of fins on said tubes, and plates extending along the sides of the tube bank from its bottom to a point below its top, said plates serving to confine any vapor generated in the lower part of the bank whereby to constrain that vapor to fiow upwardly through said bank and through said passageway, and a baille arranged above said tube bank and over the upper end of said passageway therein, said baifie serving to break up any froth of liquid refrigerant and vapor issuing from the upper end of said passageway and to direct the liquid portion thereof outwardly to the sides of the bank so I that it may fiow downwardly over said tubes.

6. A shell-and-tube refrigerant evaporator comprising a shell, a bank of tubes having fins applied to their outer surfaces disposed in said shell, said tubes being so arranged as to leave a substantially clear passageway extending lengthwise and vertically through the bank and having its lower open end located adjacent to but spaced from the base of the shell, a conduit having a series of orifices therein for discharging liquid refrigerant into the base of the shell through the small pool of liquid refrigerant which accumulates therein and for directing the introduced liquid and its flash gas into the lower open end of said passageway, such passageway serving to confine the fiash gas laterally whereby it may serve to lift liquid refrigerant through said passageway for distribution over the tubes and their fins.

'7. A shell-and-tube refrigerant evaporator according to claim 6, further characterized in that the said orifices are formed in the base of said shell, and in that said shell comprises a part of said conduit,

8. A shell-and-tube refrigerant evaporator according to claim 6, further characterized by the provision of a bafile disposed above the upper end of said passageway, said bame being of generally- V-shaped cross section with its legs curved outwardly whereby it may serve to break up any froth of refrigerant liquid and vapor striking against its under surfaces and to direct the liquid to the sides of the bank so that it may flow downwardly over said tubes and their fins.

9. A shell-and-tube refrigerant evaporator according to claim 15, further characterized by the provision of means at the sides of said tube bank for confining refrigerant vapor generated in the lower portion of the bank whereby to constrain it to fiow upwardly through said bank and said passageway.

10. A shell-and-tube refrigerant evaporator, according to claim 6, further characterized by the provision of a pair of substantially parallel plates disposed at the sides of said passageway and extending from a point near the bottom of the bank upwardly past the first few rows of tubes of the bank; and additional plates at the outer sides of the bank serving to confine laterally vapor which is generated in the lower portion of the bank whereby to constrain it to fiow upwardly through said bank and through said passageway.

11. A shell-and-tube refrigerant evaporator according to claim 6, further characterized by the provision of means along the lower side portions of the bank serving to confine laterally vapor which is generated in the lower part of the bank whereby to constrain it to fiow up throughthe bank and said passageway; and by the provision of a baflie disposed above said bank of tubes and over the upper end of said passageway, said baffle being of generally V-shaped cross section whereby it may serve to break up any froth of refrigerant liquid and vapor issuing from the upper end of said passageway and to direct the liquid to the outer sides of the bank whence it may fiow over the tubes and return to the base of the shell.

12. A shell-and-tube evaporator according to claim 6, further characterized in that said tubes i are so arranged as to leave a plurality of such passageways through the bank, and in that there is a conduit having a series of distributing orifices therein disposed beneath each of such passageways to direct refrigerant liquid and vapor thereinto.

13. A shell-and-tube refrigerant evaporator comprising a shell, 9. bank of tubes having fins applied to their outer surfaces disposed in said shell, said tubes being arranged to leave two substantially clear passageways extending lengthwise and vertically through the bank and having their lower open ends located adjacent the base of said shell, a conduit having a series of distributing orifices therein disposed beneath each such passageway, said orifices serving to introduce liquid refrigerant into the base of the shell through the small pool of liquid accumulating therein and to direct refrigerant liquid and vapor into the lower ends of said passageways, said passageways being of such size as to confine such refrigerant vapor laterally, thus causing the vapor to generate a. froth with the liquid, which froth will rise through the passageways, a baiile disposed above the upper open end of each of said passageways, said baiiles serving to break up any froth of refrigerant liquid and vapor issuing from the upper ends of said passageways and to direct the liquid sidewise so that it may flow downwardly over the tubes and their fins, and means at the sides of such tub bank for confining vapor generated in the lower portions of the bank whereby to constrain it to flow upwardly through said bank.

ROBERT w. WATERFILL.

CERTIFICATE OF CORRECTION. Patent No. 2,l{.1,152. Februery 19%.

ROBERT w. WATERFILL.

It. is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, secondcolumn, line 2, for the claim reference numeral "15" read "--6"-; and

that-the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

si ned and sealed this 11th day of April, A. 1;. 191m.

Leslie Frazer .(Seal) Acting Commissioner of Patents.

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