US2689465A - Evaporator and absorber unit for absorption refrigeration systems - Google Patents

Description

Sept. 21, 1954 L. M NEELY 2,539,465 EVAPORATOR AND ABSORBER UNIT FOR ABSORPTION REFRIGERATION SYSTEMS Filed June 30, 1951 3 Sheets-$heet 1 4&4 4770/?[7 ENTOR.

Sept. 21, 1954 L. MCNEELY 2,689,465

EVAPORATOR AND ABSORBER UNIT FOR ABSORPTION REFRIGERATION SYSTEMS Filed June 30, 1951 3 Sheets-Sheet 2 000mm nmemnmsa Q99 93 84 m 83 I 0C I INVENTOR. W F M% I L I 50a BY Sept. 21, 1954 MCNEELY 2,689,465

L. EVAPORATOR AND ABSORBER UNIT FOR ABSORPTION REFRIGERATION SYSTEMS Filed June 30, 1951 3 Sheets-Sheet 3 IN VEN TOR.

Patented Sept. 2}, 1954 EVAPORATOR AND ABSORBER UNIT FOR ABSORPTION REFRIGERATION SYSTEMS Lowell McNeely, Evansville, Ind., assignor to Serve], Inc., New York, N. Y., a corporation of Delaware Application June 30, 1951, Serial No. 234,515

8 Claims.

The present invention relates to refrigeration and more particularly to an evaporator and absorber construction for absorption refrigeration systems. 7

When small refrigerationunits are used for air conditioning, the refrigerant may be evaporated at the interior of a finned coil and the "air to be cooled passed over the exterior of the transfer coils at different locations where the air is to be cooled. One of the objects of the present invention is to provide an evaporator in the form of spaced tubes over which a primary refrigerant trickles by gravity and through which a secondary refrigerant is circulated.

Another object is to provide a combined evaporator and absorber for absorption refrigeration.

systems having tubes arranged in side-by-side open communication with each other in an enclosing shell with one group. of tubes connected to provide an evaporator and another group of tubes connected to provide an absorber.

Another object is to arrange the tubes in vertical rows with means to distribute liquid refrigerant and absorbent onto the uppermost tubes of different rows and so forming the tubes as to cause the liquid to drip at selected points from each tube onto the next lowermost tube from the top to the bottom of the. rows to produce an equal distribution of liquid over the entire surface of the tubes of each row.

Another object is to drip liquid refrigerant from the top to the bottom of a row of evaporator I tubes and automatically lift refrigerant liquid upwardly from the bottom of theevaporator and distribute it overthe surface of the lower tubes of the row.

Still another object of the invention is to provide a combined evaporator and absorber of simple and compact construction comprising banks of tubes in an enclosing shell connected to provide a central evaporator section andabsorber sections at either side of the evaporator section.

These and other objects will become more apparent from the following description and drawings in which like reference characters denote like parts through the several views. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and not a definition of the limitation of the invention, reference being had for this purpose to the appended claims. In the drawings:

Fig. 1 is a diagrammatic view of an air conditioning system having a vacuum type absorption refrigeration unit incorporating the evaporator and absorber construction of the present invention;

Fi 2 is a transverse sectional view showing one end of the combined evaporator and absorber in detail and the arrangement of the banks of tubes constituting a centrally located evaporator and absorber sections at opposite sides of the evaporator;

Fig. 3 is a sectional view of a portion of the opposite end of the evaporator from that illustrated in Fig. 2 and showing the sectional arrangement of the tubes and connecting means for delivering secondary refrigerant thereto;

' Fig. 4 is a side elevational view partly in section showing one vertical row of tubes, the liquid distributing means overlying the row and the spaced drip formers at the bottom of each tube;

Fig. 5 is a side elevational view of the lower portion of a vertical row of tubes constituting the evaporator and showing the capillary grooving on the lower two tubes and the pans under lying the grooved tubes;

Fig. 6 is a plan view partly in section of the liquid distributor for supplying refrigerant to the bank of evaporator tubes; and V Fig. '7 is a sectional plan view of the lower portion of the evaporator and showing the plurality of grooved tubes overlying each pan.

Referring to Fig. 1 of the drawings, the air conditioner comprises a primary vacuum type absorption refrigeration system Ill, an auxiliary cooling system H containing a secondary refrigerant for removing heat from the air to be conditioned and transferring it to the primary refrigeration system at a relatively low temperature, and a tertiary cooling system I2 for removing heat from the primary refrigeration system at relatively high temperature. y

The primary vacuum type absorption refrigeration system as illustrated in the drawings comprises. in general a combined generator and vapor liquid-lift l3, a condenser I 4, a combined evaporator and absorber I5 constituting the subject matter of the present invention, and. a liquid heat exchanger I5 interconnected for the circulation of refrigerant and absorbent. The combined generator and vapor liquid-lift I3 is described and claimed in a copending application for United States Letters Patent of Walter M. Simpson Serial No. 219,777, filed April 7, 1951. Suffice it to state herein that the element I3 comprises a single conduit having an upper vapor liquid-lift portion l1 and a depending portion |8 with an extended wall for increasing the heat transfer surface. The vapor liquid-lift I7 and depending portion l8 are enclosed in a jacket l9 providing a heating chamber 20 therebetween. A steam supply conduit 2| is connected to the bottom of the jacket H] to supply the required amount of steam to operate the refrigeration system at full capacity. Steam supplied to the heating chamber 2 "is maintained at atmospheric pressure by a vent tube 22 at the upper end "of the jacket I9 and a .condensate drain 23 is provided at the lower end of the jacket.

A separating chamber 24 surrounds the upper end of the lift conduit I! and has suitable .baflies 25 for separating refrigerant vapor from absorption solution delivered from the lift conduit. A vapor pipe 25 connects the separating chamber 24 to the condenser I4 and a liquid pipe 27 connects the outlet from the condenser to a flash chamber 28. Condenser l4 may be of any known type which hermetically seals the refrigerant from the cooling medium and in the illustrated embodiment comprises a chamber 29 with tubes 30 extending therethrough from an inlet header 3| to an outlet header The liquid refrigerant pipe 21 is in the form of a U-tube to provide a liquid trap for maintaining a liquid column to balance the difference in pressure between the condenser I4 and combined evaporator and absorber l5.

Flash chamber 28 is a vessel which receives liquid refrigerant .from the liquid pipe 27 at the high temperature of the condenser I4 and flashes a portion of the refrigerant to cool the remainder to a low temperature corresponding to the boiling point of the refrigerant .at the low pressure in .the combined evaporator and absorber I5. Such flashing is a violent boiling and is performed prior to the introduction of the refrigerant into the evaporator to prevent agitation and splashing. A vapor pipe 34 connects the flash chamber 28 above the liquid level therein to the top of the combined evaporator and absorber l and a liquid pipe 35 connects the bottom of the flash chamber to a liquid distributor 35, later to be described in detail.

The combined evaporator and absorber I5 is shown in detail in Figs. 2 through 7 but for purposes of illustrating its relationship in the refrigeration system it is shown diagrammatically in Fig. 1. As illustrated diagrammatically, the combined evaporator and absorber I5 comprises a closed vessel or shell 31 having .an evaporator coil 38 and an absorber coil 39 in open communication with each other. The evaporator coil 38 is of serpentine form and arranged vertically with straight tube sections located one above the other. Liquid refrigerant is distributed by the liquid distributor 36 onto the top of the uppermost straight sec.- tion .of the evaporator coil .38 and drips from each section to the next lowermost section from the top to the bottom of the coil. The absorber standing at some level a: in U-tube 21, at level '4 coil 39 also is of serpentine form having straight sections arranged one over the other and a liquid distributor 40 delivers absorption solution for gravity flow over the exterior of the coil from each straight section to the next lowermost section throughout the height of the coil. Absorption solutionweak in refrigerant flows by gravity from the separating chamber 24 to the liquid distributing means 40 for the absorber coil 39 in a path of flow comprising conduit 4|, inner passage 42 of the liquid heat exchanger l6 and conduit 43 connected to the liquid distributor. Absorption solution strong in refrigerant flows by gravity from the shell 31 to the base of the combined generator and vapor liquidlift H5 in a path of flow comprising conduit 44, outer passage 45 of the liquid heat exchanger l6, conduit 46, leveling vessel 41 and conduit 48. Leveling vessel 41 is for the purpose of maintaining a substantially constant liquid level of solution and is connected by a vent pipe 49 to the separating chamber 24. The combined generator and vapor liquid-lift l3 and condenser I4 operate at a pressure corresponding to the vapor pressure of the refrigerants at its condensing temperature and the combined evaporator and absorber I5 operates at a lower pressure corresponding to the vapor pressure of the refrigerant in the absorber. During operation of the refrigeration system, liquid columns will stand in U-tube 21 and conduits '43 and 44 to balance the difference in pressure, the liquid 1 in conduit 4| connectedto conduit 43 through heat exchanger H5, at level a in conduit 44., and at a level to in the reservoir vessel 47.

Underlying the evaporator coil 38 .is a tray 50 for collecting any excess unevaporated liquid refrigerant and delivering'it toa concentration control vessel 5|. The bottom of the concentration control vessel 5| is connected to the base of the combined generator and vapor liquidlift .|3 by a conduit 52 and the top of the vessel is connected to the evaporator by a vent pipe 53. Unevaporated liquid refrigerant accumulates in the concentration control vessel 5| to increase the concentration of the absorption solution until an equilibrium is reached at which all of the refrigerant is evaporated in the evaporator, the height of the liquid column and amount of liquid refrigerant stored in the concentration vessel being controlled by the difference in pressure between the high and low pressure sides of the system.

A secondary refrigerant is circulated in the auxiliarycooling system H in heat exchange relation with the evaporator and air in an enclosure R to be cooled. The auxiliary cooling system comprises the evaporator coil 38 and a heat exchange coil 54 in the room or rooms R to be cooled. A conduit 55 connects the upper end of the evaporator coil 38 to one end of the heat exchange coil 54, a conduit 56 connects the opposite end of coil 54 to. a circulating pump 51 and a conduit 58 connects the outlet from the pump to the lower end of the evaporator coil to complete a circuit. Pump 51 is driven by an electric motor 53 for circulating the secondary refrigerant through the evaporator coil 38 and heat exchange coil 54, successively.

The tertiary cooling system l2 for removing heat from the refrigeration apparatus comprises the absorber coil 39 and tubes 30 of the condenser l4. A source of cooling medium such as cooling tower 60 delivers cooling water for flow through a cooling water through the cooling system and a fan 65 at the top of the tower circulates air in contact with the cooling water flowing there- .through to reduce its temperature by evaporative cooling. A by-pass 66, as described and claimed in an application forLetters Patent of Harry C. Shagalofi, filed concurrently herewith, is connected between the inlet and outlet conduits 6| and 62 leading to and from the absorber coil 39 .to shunt the absorber at the beginning of a period of operation as controlled by a valve 61.

A purging device 68 is provided for continuously withdrawing non-condensable gases from the shell 31 of the combined evaporator and absorber I and a restricting conduit 68a continuously passes gases from the condenser to the shell while limiting the amount of vapor flowing, therethrough. The purge device 68 is in the form of a vessel connected to the combined evaporator and absorber shell 31 by a suction tube 69. Absorption solution weak in refrigerant is supplied to the purge vessel 68 from conduit 43 through a connecting pipe 18 and a fall tube H connects the .bottom of the vessel to a separating chamber I2.

A riser "I3 connects the separating vessel I2 adjacent the top thereof to a gas storage vessel 14 and aliquid line I5 connects the separating vessel to conduit 48 leading to the base of the combined generator and vapor liquid-lift I3.

In accordance with the present invention the combined evaporator and absorber I5 shown diagrammatically in Fig. l'comprises a plurality of tubes arranged in vertical rows in closely adjacent side-by-side relationship with the rows in open communication with each other. At least one of therows of tubes constitutes an evaporator while one or more of the other rows constitutes the absorber. Alternate tube rows or alternate pairs of tube rows may constitute the evaporator v and absorber, respectively, within the scope of .the present invention.

In the preferred embodiment of the invention illustrated in detail in Figs. 2 to '7, the combined evaporator and absorber I5 comprises banks 88, 8| and 8 2 of tubes 83. The bank of tubes 88 constitutes the evaporator, illustrated diagrammatically as a single coil 38 in Fig. 1, located centrally of the shell 31 while the banks of tubes 8| and 82 constitute separate absorber sections, illustrated diagrammatically as a single coil 39 in Fig. 1, lo-

cated at each side of the evaporator tube bank 88, closely adjacent thereto and in open communication therewith. The tubes 83 of each of the banks .88, .8I and 82 are all arranged in generally the same way, that is, one over the other in vertical rows, see Figs. 2 and 4, and the ends of adjacent tubes in each row are connected by U-shaped couplings 84 to provide a continuous serpentine coil.

The tubes of each bank 88, 8| or 82 are supported in a frame having spaced angle-iron side rails 85 at the bottom and upright rectangular plates 96 welded to the ends and middle of the bottom rails, see Fig. 4. The rectangular plates 86 extend throughout the width and height of therespective banks 88, 8| and 82, see Fig. 2, and have right angular flanges 81 at each side, see Figs. 4 and 7, right angular flanges 88 at the top and aligned perforations 89, see Figsg5 and'f.

6 In assembling a bank of tubes 88, 8| or 82, tubes 83 are inserted throughout the aligned perforations 89 in the plates 86 of the frame and the U-shaped couplings 84 inserted in the ends of adjacent tubes alternately at opposite ends thereof and brazed or welded thereto to form a continuous serpentine coil 38 or 39 of each vertical row of tubes. The inlet ends of the plurality of serpentine coils of the bank are connected by a header 98 having a supply pipe 9| and the outlet ends of the coils are connected by a header 92 having a discharge pipe 93. Mounted on the V flanges 88 at the top of the plates is a liquid distributor 36 or 48 as illustrated in Figs. 2, 4 and 6. The liquid distributor comprises a plurality of parallel troughs 94 connected by transverse end troughs 95. Each trough 94 is of a width corresponding to the distance between the rows of tubes 83 and has walls 96 overlying the center of adjacent rows of tubes throughout their length. A U-shaped syphon plate 91 overlies each wall 96 of the liquid distributor 36 or 48 and has spaced capillary grooves 98 for feeding liquid onto the top of the uppermost tube 83 of a row at spaced points therealong. Thus, if there are six vertical rows of tubes in a bank, three troughs as illustrated in Fig. 6 will provide six walls for delivering liquid onto the respective rows of tubes. Extending transversely of the troughs 94 is a closed tube or vessel 99 having an orifice I88 for each trough 94 at opposite sides of the vessel 99 to feed liquid thereto. Preferably, bafiles I8I are provided in the troughs 94 adjacent the orifice I88 to dampen the flow of liquid and prevent agitation. Liquid may be supplied to the closed tube or vessel 99 from a laterally extending feed pipe I 82 used onthe tube banks 8| and 82 constituting absorber sections as illustrated in Fig. 4 or by a vertical feed pipe 35 used on the tube bank constituting the evaporator, as illustrated in Figs. 2 and 6. I

Each of the tubes 83 of the banks 88, 8| and 82 has depending drip formers I84 at spaced points along its bottom as illustrated in Fig. 4. Preferably such drip formers are formed by striking one side of the tube with a straight tool in a direction at right angles to the axis of the tube, as described and claimed in a copending application for Letters Patent of Eugene P. W'hitlow, Serial No. 102,863, filed July 2, 1949.

The tubes 63 of bank 88 constituting the evaporator are arranged in vertical rows from the top to the bottom of the bank, but are connected at their ends to provide separate groups or sections I85, four of such sections being illustrated in Fig. 2 of the drawings. The inlet and outlet headers 98 and 92 for each section I are illustrated in Fig. 3 and the supply pipes 9| for the plurality of inlet headers 98 are connected together by a main conduit 9 Ia while the discharge pipes 93 from outlet headers 92 for the sections I85 are connected together by a discharge conduit 93a so that secondary refrigerant will flow in parallel through the separate sections to reduce the pressure drop in the coils. While the majority of the tubes 83 are provided with spaced depending drip formers I84, several of the lower tubes 83a of each row of the evaporator bank 88 are formed with peripheral capillary grooves as described and claimed in United States Letters Patent to John G. Reid, Jr.,

No. 2,485,844, issued October 25, 1949. As illus- 7 in the preferred embodiment, one 50a underlying the next to the bottom tube of all of the rows and a second 501) underlying the lowermost tubes of all of the rows. The upper pan 50a has side walls on three sides and the bottom of the pan at its open end overlies the lower pan 50b to deliver liquid thereto. The lowermost pan 50b has side walls around its entire periphery. The pans 50a and 50b are so arranged with respect to tubes 830, that liquid will be lifted from the pans by capillary action in the grooves 83b and distributed over the surface of the tubes. A drain tube |08 projects a predetermined distance above the bottom of the pan 50b and constitutes an overflow pipe connected to the concentration control vessel The banks of absorber tube sections 8| and 82 have tubes 83 with depending drip formers I04 arranged in vertical rows and alternately connected at opposite ends to provide a plurality of vertically arranged serpentine coils extending throughout their height. The absorber tube banks 8| and 82 are supported on spaced brackets l 09 and H0, see Fig. 2, at each end of the shell 31, the bottom rails 05 and cross plates 80 of the frames resting on the top of the brackets. The evaporator tube bank 80 is supported between the tube banks 8| and 82 by angle iron rails III on the flanges 81 resting on rails l |2 projecting from the upright legs of brackets |09 and I Hi. It will be understood that the evaporator tube bank 80 and absorber tube banks 8| and 82 are completely fabricated as sub-assemblies and mounted in the shell 3? as separate units with the supply and discharge conduits 9| and 93 for the coils and the absorbent and refrigerant feed pipes I02 and 35 projecting outwardly from the shell before the end plates of the shell are assembled and the joints welded or brazed to hermetically seal the combined evaporator and absorber l5. The absorbent feed pipes I02 are preferably connected to supply conduit 43 and the chilled water supply and exhaust pipes 9| and 93 are connected to mains 9m and 93a at the exterior of the shell 31. One form of the invention having now been described in detail, the mode of operation of the air conditioner is explained as follows.

To initiate operation of the complete air conditioning apparatus illustrated in Fig. 1, steam is supplied through the conduit 2| to the heating chamber of the combined generator and vapor liquid-lift l3 to heat the solution therein. Refrigerant vapor expelled from absorption solution lifts the latter in the lift tube I! at a controlled rate into the separating chamber 24. Vapor flows through the baffles and vapor pipe 26 into the condenser l4 and absorption solution weak in refrigerant flows by gravity to the liquid distributor 40 in a path including the'conduit 4|, inner passage 42 of heat exchanger l6 and conduit 43.

Simultaneously with the supply of steam to the combined generator and vapor liquid-lift [3, cooling water is supplied from the cooling tower 00 through the conduit 6|, by-pass 60, and conduit 62-to the header 3| of condenser Ml. Cooling water flows from header 9| through the tubes 30 to header 32 and from the header through the conduit 63 back to the cooling tower 60. The flow of cooling water through the tubes 30 of condenser 14 removes the heat of vaporization and condenses the refrigerant vapor to a liquid. The liquid refrigerant flows from the condenser l4 through the U-shaped liquid pipe 21 to the flash chamber 28 and from the flash chamber through 8 the liquid pipe 35 to the refrigerant distributor 36.

Liquid refrigerant and absorbent is siphoned from the distributors 36 and 40 through the spaced capillary grooves 98 of syphon plates 91, see Fig. 6, onto the uppermost tubes 83 of the respective banks 80, 8| and 82 and drips over successive tubes from the top to the bottom of the evaporator and absorber simultaneously. Due to the affinity of the refrigerant, Water, for the absorbent, lithium bromide solution, the refrigerant evaporates at a low pressure and temperature and the vapor is absorbed in the absorption solution. Any unevaporated liquid refrigerant drips into the lower pan 5% and flows into the concentration control vessel 5| to adjust the concentration of the absorbent until an equilibrium condition reached at which all of the refrigerant will evaporate as it drips from coil section to coil section from the top to the bottom of the evaporator coil 38. Absorption solution strong in refrigerant flows from the combined evaporator and absorber shell 31 back to the base of the combined generator and vapor liquid-lift |3 in a path of flow including the conduit 44, outer passage 45 of liquid heat exchanger l0, conduit 46, leveling vessel 41 and conduit 48.

Simultaneously with the initiation of the primary absorption refrigeration system ID the pump 51 in the auxiliary cooling system M will be initiated to circulate a secondary refrigerant through the evaporator coil 38. The heat exchange coil 54 in room R will remove'heat from the air and transfer it through the walls of the evaporator coil 38 to the primary refrigerant on the outside surface thereof. Thus, the auxiliary cooling system l of the air conditioner operates to remove heat from the air in a room or rooms R and transfer it to the refrigerant in the primary refrigeration system H] and the primary refrigeration system then transfers the heat to the tertiary cooling system [2. After the primary refrigeration system has been operating for a period of time sufficient to insure a full loading of the evaporator both internally and externally, the valve 61 in the by-pass 66 will be closed to cause the cooling water to flow through the absorber coil 39 and condenser l4 successively.

Referring to Figs. 2 to 7, the liquid refrigerant supplied to the liquid distributor 36 through the supply pipe 35 enters the closed vessel 99 and is distributed through the orifices I00 into the troughs 94 overlying the centrally located bank of evaporator tubes 83. The liquid refrigerant continuously siphons from the troughs 94 through the capillary grooves 98 in the distributing plates 91 onto the uppermost tubes of each of the rows of tubes constituting the evaporator. The liquid refrigerant spreads over the upper smooth surface of the tubes and then accumulates on the depending drip formers I04 from which it drips onto the next lowermost tube from the top to the bottom of the evaporator. Any liquid refrigerant dripping from the next to the bottom tube 83a of the rows of tubes is caught by the upper pan 50a which directs it into the lower pan 50b. The upper and lower pans 50a and 5012 contact the bottom of the grooved tubes 83a and the capillary grooves 831) lift the liquid from the pans and saturate the surfaces of the tubes above the liquid level to insure maximum evaporation of the refrigerant. However, when the level of the liquid refrigerant in the lower pan 50b rises above the end of the drain tube I08 the liquid refrigerant will overflow into the concentration control vessel 5|.

9' 3 Absorption liquid delivered to the liquid distributor 40 for each absorber section 8| and 82 l is distributed by the closed vessel 99 into the troughs '94 overlying the rows of the absorber tubes and is distributed along the uppermost tubes of each row in the same way refrigerant is distributed over the bank of evaporator tubes 80. Liquid absorbent drips from each tube 83 onto the top of the next lowermost tube from the top to the bottom of the absorber sections 8| and 82. Refrigerant vapor from the evaporator 88 is absorbed in absorption liquid as it flows over the tubes and at the lowermost tubes the absorption liquid drips into the enclosing shell 31 and flows to the outlet conduit 44.

It will now be observed that the present invention provides a novel construction of combined evaporator and absorber comprising vertical rows of tubes arranged in side-by-side relation and in open communication witheach other in a single hermetically sealed, enclosing shell. It will further be observed that the present invention provides for connecting the tubes to provide a centrally located evaporator section with absorber sections on either side thereof. It will stilljfurther be observed that the present invention provides a combined arrangement of tubes in the evaporator section having drip formers for uniformly distributing refrigerant over all except the lowermosttubes and capillary grooves on the periphery of the lowermost tubes to lift refrigerant over their surface.

While a single embodiment of the invention is herein illustrated and described, it will be understood that modifications may be made in the construction and arrangement of the elements without departing from the spirit or scope of the invention. Therefore, without limitation in this respect, the invention is defined by the following claims.

Iclaim:

1. In an absorption refrigeration system, an hermetically sealed shell enclosing both the evaporator and absorber at substantially the same level, said combined evaporator and absorber comprising a plurality of tubes in said shell and arranged in vertical rows, said rows being in, closely adjacent side-by-side relation and in open communication with each other,

means to deliver liquid refrigerant onto the ex-' terior of the uppermost tube of at least one row, means to deliver liquid absorbent onto the exterior of the uppermost tube of at least one of the other rows of tubes, the liquid dripping from each tube onto the next lowermost tube from the top to the bottom of its respective row, means for flowing a medium to be cooled through the interior of the row of tubes over which the liquid refrigerant is distributed, and means for flowing a cooling medium through the interior of a row of tubes over which the absorbent is distributed.

2. In a two-pressure absorption refrigeration system of the type in which the difference in pressure is maintained by pressure balancing liquid columns, a combined evaporator and absorber for reducing the overall height f the system comprisin an hermeticallysealed shell, a plurality of coils arranged vertically in sideby-side relation in open communication with each other in said shell, each of said coils having sections arranged one over the other, means to deliverliquid refrigerant onto the exterior of the uppermost section of at least one of the coils, means to deliver liquid absorbent onto the exterior of the uppermost section of at least one of the other coils, the liquid on the respective coils dripping from each section onto the next lowermost section from the top to the bottom of the coil, means for deliverin a medium to be cooled for flow through the interior of the refrigerant coil, and means for delivering a cooling medium for flow through the interior of the absorbent coil.

3. In an absorption refrigeration system, a combined evaporator and absorber comprising an hermetically sealed shell, an evaporator arranged centrally in said shell, an absorber having sections at each side of the. evaporator and in open communication therewith, said evapora tor and absorber sections comprising tubes connected to provide separate paths of flow, means for distributing liquid refrigerant and absorbent on the tubes of the evaporator and absorber, respectively, to wet the exterior surfaces thereof,

.means for flowing a fluid to be cooled through the interior of the evaporator tubes, and means for flowing a cooling medium through the interior of the absorber tubes.

4. In an absorption refrigeration system, a combined evaporator and absorber comprising a single hermetically sealed cylindrical shell, a plurality of tubes in said shell connected to provide a central evaporator section and absorber sections at each' side of the evaporator section, the tubes of said evaporator and absorber sections being arranged one over the other in vertically aligned rows in closely adjacent side-byside relationship and in open communication with each other, means for supplying liquid refrigerant and absorbent to the uppermost tubes of the evaporator and absorber, respectively, which drips from each tube to the next lowermost tube from the top to the bottom of the rows, means for flowing a medium to be cooled through the tubes constituting the evaporator, and means for flowing a cooling medium through the rows of tubes constituting the absorber.

5. In an absorption refrigeration system, a combined evaporator and absorber comprising an hermetically sealed shell having spaced brackets, an evaporator comprising a frame located between the brackets and secured thereto, said frame mounting a bank of tubes arranged one over the other in vertical alignment,

absorber sections at either side of the evaporator with each section comprising a frame resting on the brackets and mounting a bank of tubes arranged one over the other in vertical alignment, a liquid distributor mounted on the top of each of the evaporator and absorber section frames and having means for delivering liquid refrigerant and absorbent onto the upper tube of each row of the respective banks of tubes, said liquid dripping from each tube to the next lowermost tube from the top to the bottom of each row, means for flowing a medium to be cooled through the bank of evaporator tubes, and means for flowing a cooling medium through the banks of tubes of the absorber sections.

6. In a refrigeration system, an evaporator comprising an hermetically sealed shell, a bank of tubes arranged one over the other in vertically aligned rows and connected to provide separate paths of flow, liquid distributing means for supplying liquid refrigerant uniformly along the top of the uppermost tube of each row which drips from the bottom of each tube onto the top of the next lowermost tube from the top to the bot tom of the evaporator, a pan underlying the evaporator to receive any surplus liquid refrigcomprising an hermetically sealed shell, a bank of tubes arranged one over the other in vertically aligned rows and connected to provide parallel paths of flow, the lower tubes of each row having peripheral capillary grooves, the remainder of the tubes of each row having a plain upper surface and spaced depending drip formers, a liquid distributor for delivering liquid refrigerant onto the uppermost tube of each row uniformly throughout its length, said liquid refrigerant flowing over the plain surface off each tube and dripping from the drip formers onto the next lowermost tube from the top to the bottom of the row; a pan underlying the bank of tubes to receive liquid refrigerant, and the capillary grooves on the lower tubes lifting liquid refrigerant from the pan to wet their surface above the liquid level.

8,. In a refrigeration system, an evaporator comprising an hermetically sealed shell, a plurality of serpentine coils arranged one over the other in vertical rows in said shell, the corresponding coils in each row being connected to provide a plurality of separate coil sections, each of the coils having longitudinal tube portions 12 arranged one over the other from the. top to the bottom of a row, a plurality of the lower tubes of. each row having peripheral capillary grooves. the remainder of the tubes of each row having a plain upper surface and spaced depending drip; formers. a liquid distributor for delivering. liquid refrigerant onto the uppermost tube of each. row uniformly throughout. its length, said liquid refrigerant flowing over the plain surface of each tube and dripping from the drip formersv onto the next lowermost tube from the top to the. bottom of the row, a pan underlying each horizontallayer of corresponding grooved tubes of adjacent coilsl the upper pan having means for directing.

liquid refrigerant into the next lowermost panv and the capillary grooves lifting liquid from the pans. over the surface of the tubes above the liquid level.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,031,885 Stratton July 9, 1912 1,526,605 Mather Feb. 17, 1925 2,323,186 Andersen June 29, 1943. 2,399,916 Edberg May '7, 1946 2,485,844 Reid Oct. 25, 1949 2,565,943 Berestneif Aug. 28, 1951 2,568,891 I Kals Sept. 25, 1951

Images