US2625803A - Absorption refrigeration - Google Patents

Description

Jan. 20, 1953 w. M. SIMPSON ABSORPTION REFRIGERATION 2 SHEETSSHEET 1 Filed April '7, 1951 INVENTOR.

fie 4770/7/12? Jan. 20, 1953 w. M. SIMPSON ABSORPTION REFRIGERATION 2 SHEETS-SHEET 2 Filed April '7, 1951 INV NTOR. Z %ia W $4 arra/m sy Patented Jan. 20, 1953 ABSORPTION REFRIGERATION Walter M. Simpson, Evansville, Ind., assignor to Servel, Inc., New York, N. Y., a corporation of Delaware Application April 7, 1951, Serial No. 219,777

11 Claims.

The present invention relates to absorption refrigeration systems and more particularly to an improved heating arrangement for expelling refrigerant vapor from absorption solution in such systems.

One of the objects of the present invention is to provide a combined generator and vapor liquidlift in the form of a single upright conduit so constructed as to provide the necessary heat transfer surface and cross sectional area to expel vapor and lift liquid at any desired rate.

Another object is to provide a single upright conduit of the type indicated which is heated throughout its length and adapted for use with an absorption refrigeration system of any capac-'- ity.

Still another object is to provide a heated vapor liquid-lift conduit with a lower depending skirt portion having undulating folds to increase the heat transfer surface and an upper lift portion of reduced cross-sectional area correlated to the heat transfer surface to produce a'vapor velocity suflicient to lift liquid at the desired rate at any particular capacity.

These and other objects will become more apparent from the following description and drawings in which like reference characters denote like parts throughout 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 limits of the invention, reference being had for this purpose to the appended claims. In the drawings:

Fig. 1 is a diagrammatic view of an absorption refrigeration system incorporating the combined generator and vapor liquid-lift conduit of the present invention;

Fig. 2 is an enlarged view of the upright conduit showing its upper liquid-lift portion and lower pleated skirt and enclosed throughout its length by a heating jacket; I

Fig. 3 is a transverse sectional view taken on line 3-3 of Fig. 2 showing the radial folds in the lower skirt portion to provide an extended heating surface;

Fig. 4 is a view similar to Fig. 3 taken on line 4 of Fig. 2;

Fig. 5 is a sectional side elevational view of a vapor liquid-lift conduit of modified construction;

Fig. 6 is a transverse sectional View taken on line 66 of Fig. 5 and showing the wall of the lower portion folded to provide a series of laterally extending wings or pleats to increase the heat transfer surface; and

Fig. '7 is a sectional side elevational view of a vapor liquid-lift of still further modified construction showing the upper lift portion in the form of a cylindrical tube.

Referring to Fig. 1 of the drawings, the invention is shown applied to a vacuum type absorption refrigeration system of the type described and claimed in United States Letters Patent to Albert R. Thomas et a1., 2,282,503, issued May 12, 1942, which utilizes water as a refrigerant and a salt solution as an absorbent. The system as illustrated comprises a combined generator and vapor liquid-lift conduit Ill, constituting the subject matter of the present invention, a separating chamber II, a condenser |2, an evaporator l3, an absorber I4, and liquid heat exchanger I5 interconnected for the circulation of refrigerant and absorbent.

The combined generator and vapor liquid-lift conduit l0, later to be described in detail, receives absorption solution from the liquid heat exchanger I5 and utilizes expelled vapor to lift absorption solution into separating chamber II for gravity flow through the absorption solution circuit. The separating chamber surrounds the upper end of the vapor liquid-lift conduit II! and has a curved deflecting baffle I6 overlying the upper end of the lift and a plurality of other baffies H for separating liquid entrained in the vapor. The top of the separating chamber H is connected. to the condenser |2 by a conduit |8 and the outlet from the condenser is connected to the evaporator l3 by a conduit I having a device 26 therein for maintaining a pressure differential while permitting the flow of non-condensable gases as described and claimed in a copending application of Norton E. Berry, Serial No. 725,000 filed January 29, 1947.

The evaporator |3 comprises a plurality of horizontally arranged tubes 2| having their opposite ends projecting into laterally spaced head ers 22' and 23. Conduit l9 from condenser I2 is connected to one-end of the uppermost evaporator tube 2| in header 22. The end of the next lower tube 2| projecting into header 23 has a cup' 24 at its end underlying the end of the uppermost tube to receive liquid refrigerant flowing therefrom and direct it for flow through saidany suitable source of supply through a pipe 29 and header 3e. Cooling water from the, upper ends of coils 2? is delivered through a header 3! and conduit 32 to condenser 12 and cooling- Water from the condenser is discharged through a conduit 33. Thus, the same cooling water is used to cool the evaporator 13 and'condenser l2.

Absorption solution flows by gravity from the separating chamber H through the absorption solution circuit back to the base of the upright lift conduit [0. Absorption solution weak in refrigerant flows from the separating chamber H to the liquid distributor 28 ina path. of flow comprising conduit 34', inner passages 35' of the liquid heat exchanger I and conduit 36' connected to the liquid distributor. Absorption solution strong in refrigerant flows from the absorber 1-4 to the base of conduit ID in a path of flow comprising conduit 37, outer passages 38 of the liquid heat exchanger l5 and accumulates in the upper part of the liquid heat exchanger casingconstituting a leveling vessel 39 and from the-leveling vessel through a conduit 30. Leveling vessel 39 has a relativelylarge volume so that variations in liquid flow in the solution circuit will have a negligible effect on the liquid level a: in the vessel during operation of the system.

A purge device All as described and claimed in United States Patent to Charles C. Roswell Re. 23.,093' issued March 22, 1949, is provided which is in the form f an auxiliary absorber connected to the main absorber Id to withdraw non-conden-sable gases. from the system. The purge device 41 comprises a vessel connected to conduit to receive absorption solution weak in refrigerant, and has a suction pipe 42 extending to the bottom and center of the main absorber 1 3 where the gases accumulate. purge device M is connected to the cooling water conduits 29 and 32 and a fall tube 44 depends from the bottom of the vessel. The purge device 4.! solution flowing toward the. absorber It for producing a relative vacuum to withdraw non-con,- densable gases from the main absorber and deliver them through the fall tube. 4.4. to a riser 45 connected to conduit 37. at its lower endandv having astorage vessel lit. at its upper end. With. such a construction non-condensable gases are, withdrawn from the. system and delivered to the.

storage vessel 46, while the absorption solution is delivered to the conduit 31- flowing toward the base: of the upright lift conduit H].

A concentration controlof the type illustrated and described in United States Letters Patent of Lowell McNeely 2,465,904, issued March 29, 19.49, is provided for storing liquid refrigerant in accordance' with the difference. in pressure between the high and low pressure sides of the system. The concentration control comprises a vessel 41 having a conduit 48 connected to receive liquid refrigerant overflowing from the lowermost tube of the evaporator 13 and a conduit. 49 connecting A cooling coil 23 in the tiliaes a portionv of the absorptionv 4 the bottom of the vessel to the base of the upright lift conduit l0. A pressure equalizing conduit 50 is also connected between the top of the vessel and the side of the evaporator header 22.

The upright lift conduit I0 and condenser 12 operate at one pressure corresponding to the condensing temperature of, the condenser, for example, one pound per square inch absolute, and the evaporator l3 and absorber l4 operate at a lower pressure corresponding to the vapor pressure of refrigerant in the absorber, for example, one-tenth of a pound per square inch absolute, and the, pressure difference is maintained between the condenser and evaporator by the device 20 and between the genrator and absorberby liquid columns in conduits 35 and 31. The liquid heat exchanger I5 is located below absorber [-4 and during operation of the system solution will stand at a level :0 in leveling chamber. 39: to produce a hydrostatic reaction head It on solution in the uprightlift conduit l0 and solution will stand'at a level y in conduit 34 connected' to conduit 36. through liquid heat exchanger l5 and at a level 2: in conduit 37.

In accordance with the present invention, the combined generator and vaporliquid-lift l0 isso constructed and arranged asito provide the necessary heating surface and cross-sectional area in a single conduit to lift liquid at the desired rate at any particular capacity. While the present invention is intended to include an arrangement for heating only a portion of the conduit, the

, entire length of the conduit is heated in the--pree.- ferred' construction.

In the embodiment of the invention illustrated in Figs. 1 to 4, the combined generator and vapor liquid-lift conduit l0 comprises an upper liquidlifting portion and a lower depending skirt portion 56. The upper liquid-lifting portion 55 may take other forms but preferably comprises a conduit having a throat 51 with a progressively divergent cross-sectional area extending upwardly from the throat and formed as a tapered tube or by flattening the sides of a cylindrical tube as described and claimed in copending applications for United States Letters Patent of Eugene P. Whitlow Serial No. 220,002 filed April 9, 1951.

The lower depending skirt portion 56 is of generally conical form diverging outwardly from the throat 51 to the bottom. The depending skirt portion 56 is in the form of a sheet metal wall. pleated with radial outer and inner folds 59 and, 60 to form a fluted cone.

in the sheet. metal. Wall Of the skirt portion 56 arev arranged closely adjacent each other to pro.- vide. inner and outer undulating surfaces with each side 5| of the pleats between adjacent folds each other to. form an unimpeded circular opening 62 at the center and bottom of the skirt. In other words, the outer folds 59 taper outwardly to provide an outer conical contour and the. inner folds 6.0. taper inwardly to provide an As shown more. clearly in Figs. 3 and 4', the folds 5.9 and 60 in.

inverted conical contour. The bottom of the lower pleated skirt portion 56 is closed by a plate 63 having a depending well 64 in alignment with the opening 62 to which the conduits 45 and 49 are connected. With the construction as described above, it will be noted that the lower conical skirt portion 56 provides a passage converging toward the throat 51 and the upper portion 55 provides a passage diverging from the throat.

The combined generator and vapor liquid-lift conduit I is enclosed throughout its length by a jacket 65 providing a heating chamber 66 around the lower skirt portion 56 and upperlift portion 55. A conduit 61 at the lower end of jacket 65 is connected to a source of heating medium, such as steam, and a vent pipe 68 is connected to the upper end of the jacket to maintain the steam at atmospheric pressure. Steam supplied to the jacket 65 will contact both the lower skirt portion 56 including the sides BI and folds 59 and 50 and the lift portion 55 throughout its length. A condensate drain-pipe -59 is connected to the bottom of the jacket 65.

When designing a combined generator and vapor liquid-lift conduit ID, the total heat-transfersurface for expelling the amount of vapor required for the particular capacity and the cross-sectional area required to lift liquid at the desired rate with the amount of vapor expelled are determined. A lift conduit 55 is then selected having the required cross-sectional area and a lower depending skirt portion 56 folded to provide the heat transfer surface required in addition to the surface of the lift portion and attached to the latter below the throat 51. Thus, a conduit I0 is provided which correlates the cross-sectional area at the throat 51 with the heat-transfer surface to produce the desired rate of circulation with a single conduit at any particular capacity. One form of the invention having now been described in detail, the mode of operation is explained as follows.

To initiate operation of the refrigeration system, steam is supplied through conduit 61 to the heating chamber 66 between the jacket 55 and combined generator and liquid-lift conduit Ill. The heating steam contacts the walls of the conduit ID throughout its length including the undulating folds of the depending skirt portion 55. Heat is transmitted from the steam through the walls 6| between adjacent folds 59 and 50 to heat the solution in the radial wings between the walls and thereby expel refrigerant vapor from the solution. The vapor flows upwardly toward the throat 51 and because of the throttling effect of the throat will depress the liquid level to height 71. below the level as in leveling vessel 39. Due to the designed correlation of the heattransfer surface to the cross-sectional area of the throat 62, the vapor will flow upwardly through the throat and upper lift portion 55 of the conduit at a high velocity sufficient to lift droplets of liquid at the desired rate. Such droplets of liquid are formed by the violent expulsion of vapor from solution which probably produces a froth or foam which, in turn, is torn apart by the high velocity vapor and coalesces in small droplets. The frictional drag of the high velocity vapor on the surface of the droplets produces a force greater than the force of inertia and gravity of the droplets to impart momentum thereto. As the droplets rise through the upper lift portion 55 of the conduit I0, they are further heated to expel additional vapor. Such additional vapor would tend to increase the vapor velocity but the force required to lift the droplets becomes progressively less due to the initial momentum of the droplets and decreasing height. As it is desired to merely lift the droplets of liquid to the separating chamber H without any excess velocity, the upper lift portion 55 of the conduit has a progressively divergent passage designed to compensate for the additional vapor expelled there in and the decreased velocity required to lift the liquid into the separating chamber.

The droplets of liquid issuing from the upper end of the lift conduit l0 engage the baflle l6 and are separated from the vapor. The vapor continues to flow through the additional baffles I! where all of the liquid is removed from the vapor and the later then flows through the conduit l8 to the condenser l2 where it is condensed to a liquid. Liquid refrigerant flows from the condenser I2 through the restricting device 20 and conduit [9 to the top of the evaporator I3. The liquid refrigerant then flows by gravity through successive tubes 2| from the top to the bottom of the evaporator.

Simultaneously, the absorption solution weak in refrigerant flows by gravity through conduit 34, inner passages 35 of liquid heat exchanger l5 and conduit 36 to liquid distributor 28. The absorption solution is distributed for gravity flow over the serpentine coils 21 of the absorber I! by the liquid distributor 28 where it absorbs refrigerant vapor and reduces the pressure and temperature at which the refrigerant evaporates in the evaporator 13 to cool the air passing over the tubes 21 and between the fins 25. Absorption solution strong in refrigerant flows by gravity from absorber it through the conduit 31, outer passages 38 of liquid heat exchanger 15 and into the leveling vessel 39. From the leveling vessel 33 the solution flows through conduit dB to the inlet chamber or well 54. at the base of the combined. generator and vapor liquid-lift conduit In to complete the cycle of operation.

Non-condensable gases accumulating at the center and bottom of the absorber I4 are continuously withdrawn by the purging device 4| and transferred to the storage vessel 46. At the beginning of a period of operation of the refrigeration system, liquid refrigerant will overfiow from;

the lowermost tube 21 of evaporator l3 into the concentration vessel 41 which stores liquid refrigerant until the concentration of the solution has increased to produce an equilibrium condition at the desired evaporator temperature.

In Fig. 5 a modified construction is illustrated in which the lower depending portion 55 of the combined generator and vapor liquid-lift conduit 5i! is of rectangular form instead of conical form. As illustrated more clearly in Fig. 6, the depending portion 55 comprises a heat-transfer wall having plurality of adjacent laterally-extending wings 15 formed by opposite folds l5 and Ti and providing additional heat transfer surfaces t8 between adjacent folds. The top of the laterallyextending wings 15 are closed by a plate 19 preferably cut away between adjacent wings and having a central opening connected to the lower end of the lift portion 55 below the throat 51. The bottom of the laterally-extending wings 15 are also closed by a plate 8| having a centrally located well $2. The form of construction illustrated in Fig. 5 operates in substantially the same Way as the construction illustrated in Figs. 1 to 4.

In Fig. '7 a further modified form of construction is illustrated having a straight cylindrical tube 85 forming the upper lift portion of the conduit instead of a divergent conduit as illustrated in the previously-described constructions. While a combined generator and vapor lift conduit ll)- having an upper divergent lift portion 55 is preferred, a straight cylindrical lift portion can be used as illustrated in Fig. 7 but will require an additional reaction heat it to balance the increased forces. It is to be understood, also, that the straight cylindrical lift tube 85 illustrated in Fig. 7 may be used with a lower conical skirt portion es illustrated in Figs. 1 to 4. In the form of the invention illustrated in Fig. 7, the lower end of tube at its point of joinder with the depending skirt portion at constitutes the restriction or throat for 5- cducing the vapor velocity required.

It will now be observed that the present invention provides a combined generator and vapor liquid-lift so constructed as to adapt asingle lift conduit to circulate liquid at the desired rate at any capacity. It will also be observed that the present invention provides a single vapor liquidlift conduit adapted for an absorption refrigeration system of any particular capacity having an additional heating surface formed by a pleated heat-transfer wall depending from the lift porti'cn of the conduit. It will still further be observed that the present invention provides a single conduit heated throughout its length and having suihcient heat-transfer surface and cross-sectional area to produce the desired rate of circulation at any particular capacity.

While several forms of the invention have been illustrated and described herein, it will be understood that further changes 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.

What is claimed is:

1. In an absorption refrigeration system, an absorption solution circuit having an upright lift conduit for any particular capacity, the parts of said circuit being arranged to maintain a level of absorption solution above the bottom of said lift conduit, the wall of the lower portion of said lift conduit below said liquid level having a plurality of undulating folds to provide the heat transfer surface required to expel vapor in quantities sufiicient to continuously maintain a body of vapor above the liquid level therein, means for heating the lower portion of said lift conduit, and the conduit above the undulating fold having a throat for producing a vapor velocity sufficient to lift solution at a controlled rate of relative circulation of vapor and liquid.

2. In an absorption refrigeration system, an absorption solution circuit having an upright lift conduit for any particular capacity, the parts of said circuit being arranged to maintain absorption liquid in said circuit at a level above the bottom of said lift conduit, the lower portion of said lift conduit forming a chamber in said circuit below the liquid level and the wall of said chamber being folded to provide a plurality of adjacent pleats for increasing the heat transfer surface, a throat in the conduit above the lower pleated portion, and means for heating the pleated wall at the lower portion of said conduit to expel refrigerant vapor in quantities sufficient to continuously maintain a body of vapor between the liquid solution and throat.

3. In an absorption refrigeration system, an

absorption solution circuit having an upright conduit, said conduit having an upper lift portion and a depending heat transfer wall folded to provide vertically arranged pleats for increasing the heat transfer surface and directing expelled vapor upwardly toward the lift portion, a throat between the upper lift portion and lower depending wall, the parts of said circuit being arranged to maintain absorption liquid above the bottom of said conduit, means for heating the depending heat transfer wall to expel vapor at a rate to maintain a body of' vapor in the conduit below the throat, and the throat having a cross-sectional area to cause vapor to flow upwardly through the lift portion at a velocity sufiicient to lift liquid at the required rate.

4. In an absorption refrigeration system, an absorption solution circuit having a single upright conduit, the wall of the lower portion of said conduit being folded to provide a plurality of pleats to provide the heat transfer surface required to expel vapor in quantities sufiicient to continuously maintain a body of vapor in the conduit above the liquid level therein, a throat in the conduit above the pleats for producing a vapor velocity to lift liquid at the desired rate, a heating jacket enclosing the entire conduit throughout its length, andv means for supplying heating medium to the jacket.

5. In an absorption refrigeration system, an absorption solution circuit having a single upright conduit, said conduit having an upper lift portion and a depending generator portion, the wall of the depending generator portion being folded to provide a plurality ofvertically arranged pleats to provide the heat transfer surface required to expel vapor in quantities sufficient to continuously maintain a body of vapor in the conduit above the liquid level, a throat in the conduit above the pleats for producing a vapor velocity to lift liquid at the desired rate, a heating jacket enclosing the entire conduit throughout its length, and means for supplying a heating medium to the jacket.

6. An absorption refrigeration system in accordance with claim 1 in which said conduit has a converging vapor expelling portion and diverging liquid-lift portion with a throat therebetween, the walls of said converging portion being fluted to increase the heat transfer surface and direct expelled vapor toward the throat, a heating chamber surrounding the converging vapor expelling portion, and means for supplying a heating medium to the chamber.

'7. An absorption refrigeration system in accordance with claim 1 in which said conduit has an upper lift portion and a lower vapor expelling portion, the lower vapor expelling portion having lateral wings to increase the heat transfer surface, a jacket surrounding the conduit throughout its length to provide a heating chamber, and means for supplying a heating medium to the chamber.

8. An absorption refrigeration system in ac,- cordance with claim 1 in which said conduit has an upper lift portion and .a. depending conical skirt portion, the wall of said skirt portion having radial folds to increase the heat transfer surface, and a heating jacket enclosing the conduit throughout its length.

9. An absorption refrigeration system in accordance with claim 1 in. which said conduit has an upper divergent conical lift portion and a depending converging' conical. portion with a throat therebetween, the wall of the depending conical portion having radial folds to increase the heat transfer surface, and a heating jacket enclosing the conduit throughout its length.

10. An absorption refrigeration system in accordance with claim 1 in which said conduit has an upper lift portion and a lower vapor expelling portion, the lower vapor expelling portion extending laterally from the sides of the upper lift portion with its wall folded to provide a plurality of adjacent pleats, and a heating jacket enclosing the conduit throughout its length.

11. An absorption refrigeration system in accordance with claim 1 in which said conduit has an upper cylindrical liquid-lift portion and a 15 lower rectangular vapor expelling portion, the wall of the lower vapor expelling portion being folded to provide a plurality of laterally extending wings, and a, heating jacket enclosing the upright conduit throughout its length.

WALTER M. SIMPSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,417,522 Holbrook May 30, 1922 1,865,599 Warrick July 5, 1932 2,044,750 Bryant June 16, 1936 2,128,842 Morgan Aug. 30, 1938 2,282,504 Thomas May 12, 1942

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