US2290506A

US2290506A - Refrigeration

Info

Publication number: US2290506A
Application number: US238781A
Authority: US
Inventors: Albert R Thomas
Original assignee: Servel Inc
Current assignee: Servel Inc
Priority date: 1938-11-04
Filing date: 1938-11-04
Publication date: 1942-07-21
Anticipated expiration: 1959-07-21

Description

July 21, 1942.

A. R. THOMAS REFRIGERATION Filed Nov. 4, 1938 '5 Sheets-Sheet l ICCCICCZ INVENTOR ATTORNEY.

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Patented July 21, 1942 Servel, -Inc., Delaware New York, N. Y., a corporation of Application November 4, 1938,'Serial No. 238,781

31 Claims. (01. 62-1195) My invention relates to refrigeration produced by evaporation of refrigerant fluid in the presence of auxiliary pressure equalizing fluid, and it is an object of the invention to 'provide method and apparatus whereby evaporation is more efliciently carried out. It is another object of the invention to provide more efiicient cooling of a refrigeration system of this type utilizing evaporation of a plurality of fluids in the presence of each other. A further object is to effect a more efficient separation of the vapors produced by evaporation of a plurality of fluids in the presence of each other. Another object is to cool air for more satisfactory comfort conditions with the aid of refrigeration produced by fluid evaporation, more particularly, to automatically maintain a cooled air condition at a given differential with respect to atmospheric air.

The above, together with other objects and advantages of the invention, are more fully explained in the following description. The accompanying drawings to which reference is made in the description show in Fig. l a more or less diagrammatic view of a refrigeration system embodying the invention. Fig. 2 shows more or less diagrammatically a refrigeration system incorporating another embodiment of the invention. Fig. 3 shows more or less diagrammatically a further embodiment of the invention. Fig. 4 shows in vertical section apparatus for use in Fig. 3.

Fig. 5 is a sectional view on line 55 of another part of the apparatus in Fig. 3; Fig. 6 is a detail sectional view on line 6-6 in Fig. 3; and Fig. 7 shows more or less diagrammatically another refrigeration system embodying the invention.

Referring to Fig. 1 a boiler or generator I is heated by an internal steam coil I I. Any suitable heater may be used. A circulation vessel I2 below the generator. I0 is heated by a steam coil I3. The bottom of generator I0 is connected to the bottom of vessel I 2 by a downward looped conduit I4. Above the generator tion vessel I5. The top nected to the upper'part of generator Ill is conof vessel I by a conduit I6. Lower vessel I2 is connected to upper vessel f The lower end of conduit:

I5 by a conduit I I. V I1 projects downward into vessel I2. One endiof a generally horizontal conduit I8 is connected to the upper part of generator I0, andthe other end of'conduit I8 is connected to a vessel I9. Conduit I8 and vessel I9 together will be referred to as ananalyzer.

Theupper end of vessel I9 is connected by a conduit 2| to one end of a condenser 22. A part of conduit 2] sloping back toward the analyzer I0 is an upper circula-.

is provided with heat radiation fins 23 forming an air cooled rectifier. Condenser 22 is illustrated as a water jacket around a part of conduit 2|. A water inlet conduit 24 is connectedto the lower end of the condenser jacket, and an outlet conduit 25 is connected to the upper end of the condenser jacket.

An evaporator 26 is shown as a finned pipe coil located in a thermally insulated compartment 21. The lower end of evaporator 26 is connected by a downward looped conduit 28 to the outlet end of condenser 22. The upper end of evaporator 26 is connected by a conduit 29 to the lower part of an absorber 3!.

The absorber is shown as comprising an. upright cylindrical vessel within which is a cylindrically wound cooling coil 32. Coil 32 is located in an annular space formed between the outer absorber shell and an inner cylindrical form 33. A water inlet conduit 34 is connected to the lower end of coil 32.' The upper end of coil 32 is connected to conduit 24. which is the inlet conduit to condenser 22. On the upper end of the cylindrical form 33 is a circular trough or tray 35. The edge of tray 35 is directly above the upper end of coil 32. A capillary syphon formed by wire mesh 36 extends from within the tray over the upper edge of the tray and downward above the coil 32. A liquid inlet conduit 31 discharges into tray 35. A liquid outlet conduit 38 is connected to the bottom of the absorber 3|. A vent conduit 39is connected from the upper part of absorber 3| to the upper end of conduit 28. A

vapor outlet conduit 4! is connected to the top of absorber 3!.

A second condenser 42 comprises a water cooling jacket around a conduit 43. This condenser jacket is provided with a water inlet connection 44 and a discharge conduit 45. The lower end of conduit 43 is connected to the upper part of a jacket 46. The jacket 46 is located around the open upper end of a conduit 41. Conduit 41 is looped downward and the other end is connected to the conduit 28 just below the lower end of evaporator 26. The absorber liquid inlet conduit-31 is connected to the lower part of jacket 45. The absorber vapor outlet conduit M is connected to the top of jacket 46.

The lower part of the upper circulation vessel I5 is connected by a conduit 48, the inner passage of a liquid heat exchanger 49 and a conduit 50 to the upper end of condenser 42. About a part of conduit 50 is located a water cooling jacket 5|. The water outlet conduit from condenser 42 is connected to jacket BI. A discharge conduit52 is vessel I9.

through conduit 2| to condenser 22. Ammoniaconnected to the other end of jacket 5|. The absorber liquid outlet conduit 38 is connected to theouter passage of liquid heat exchanger 49 which is in turn connected by conduit 53 to the bottom of analyzer vessel l9.

The above described system is preferably formed of steel parts suitably welded together forming a system in which all parts are in open communication. By means of a suitable charging-plug, not shown, in the absorber 3| there is introduced into the system a plurality of refrigerant fluids which are chemically inert with respect to each other. There is also introduced into the system a liquid absorbent for one of the refrigerant fluids. For instance, there may be introduced ammonia, propane and water. ammonia and water are introduced in the form of a solution. The system is then hermetically sealed. Liquid will seek its own level in the lower parts of the apparatus and vapors of the liquids will fill the upper parts of the apparatus above the surface levels of liquid therein.

In operation, generator l and circulation vessel l2 are heated by steam in coils H and I3. Any liquid propane in these vessels will be caused to vaporize and the vapor will rise into the upper part of the apparatus. Ammonia which is dissolved in the water will be expelled from solution by heating. Vapor expelled from solution in vessel l2 accumulates in the upper part thereof, forcing the surface level of liquid therein downward until liquid is caused to flow upward through conduit |1 into upper vessel H) by thermosyphon or vapor liquid lift action. This action may be improved by providing a small hole 20 in conduit [1 just above the lower end thereof in vessel l2.

Vapor expelled from solution in generator l0 accumulates in the upper end of the generator, in conduit l6, and in the upper part of vessel l5. When sufficient vapor has been expelled, it bubbles through liquid in analyzer conduit l8 and The vapor flows from the analyzer vapor is condensed to liquid in condenser 22. The liquid flows downward into conduit 28 and accuigulates in this conduit and in evaporator coil During operation oLthe system, cooling water flows through conduit 34, absorber cooling coil 32, conduit 24, condenser 22, and conduit 25. Cooling water also flows through-conduit 44, condenser 42, conduit 45, liquid cooler 5|,and conduit 52.

Weakened absorption liquid flows from vessel l5 through conduit 48, liquid heat exchanger 49 and conduit 50 into condenser 42. Ammonia vapor in condenser 42 is absorbed into the weakened solution so that propane vapor therein ap- "proaches the total pressure in the system and condenses to liquid. Ammonia solution and liquid propane flow from condenser 42 into jacket ,46-an'd accumulate therein around the upper end 1 I ofconduit 41. The liquid propane and ammonia solution are immiscible and the propane -is lighter so that these liquids stratify with the propane on top. The jacket 46 and the absorber liquid inlet 31 7 form a U-tube liquid trap of which the jacket 46 is one leg and conduit 31 is the other leg. .The lower part of the jacket 46' and conduit 31 icontain accumulated ammonia solution.

The upper part of jacket 46 contains liquid propane; The column of liquid in jacket 46 comprising duit 31 into tray 35.

.31 into absorber 3|, and liquid propane overflows from jacket 46 into the upper end of conduit 41.

Liquid propane accumulates in the downward looped conduit 41. The other end of conduit 41 is connected to conduit 28 just below the evaporator 26 so-that liquid propane and liquid ammonia mix and enter evaporator 26 together. In evaporator 26, the propane and ammonia evaporate in the presence of each other. This evaporation produces a refrigeration efiect for cooling compartment 21. The mixture of ammonia and propane vapors flows from the evaporator through conduit 29 into absorber 3|.

Absorption solution discharges from inlet con- The liquid is withdrawn from trayr35 .by the capillary syphon screen 36 and deposited onto the upper end of absorber cooling coil 32. The liquid flows downward over the outer surface of coil 32. Ammonia vapor is absorbed out of the mixture into solution in the absorption liquid. Resulting enriched solution accumulates in the bottom of absorber 3| and from there flows through conduit 38, liquid heat exchanger 49, and conduit 53 into the analyzer' l8, l9 and thence back to the generator I0.

Propane vapor flows from the upper end of absorber 3| through conduit 4| into the upper end of jacket 46 and thence into condenser 42. Condenser 42 may be referred to as the propane condenser. Condenser 22 may be referred to as fier 23 is to minimize the amount of water vapor in the ammonia-propane vapors. y In the absorber 3|, as ammonia vapor is absorbed into solution out of the mixture of ammonia and propane vapors, the partial pressure of the propane vapor increases. The vapors flowing through the absorber toward the propane condenser contain ammonia equal to or higher than the partial pressure of ammonia from the solution with which thevapors are in contact. This ammonia gas acts as an inert gas in the propane condenser and affects the condensation temperature of propane. As propane is condensed the partial pressure of the ammonia will increase, further lowering the condenser temperature. However, by flowing weak absorption solution through the propane condenser, as previously described, absorption of ammonia is carried out at or near the point of condensation, preventing increase in partial pressure of the ammonia and its effect on necessary condenser temperature.

Referringto Fig. 2, there is shown a system generally like that described in connection with Fig. 1. However, in this system there is provided a dual absorber and a'modifled form of propane solution and liquid propane is lighter than an A generator 54 is heated by a burner condenser.

55'. The

generator comprises an upright cylindrical casing through which extend a plurality of heating fiues' 56. The burner 55 is located below the lower ends of fiues 58 in a heating chamber 51. From the lower part of generator 54 there extends downward a conduit 58. To the lower end of conduit 58 is connected the lower end of a conduit 59 having a coiled portion 80 located in the heating chamber 51. The upper end of conduit 59 is connected to the upper part of a circulation vessel 6|. The upper part Of generator 54 is connected by a conduit 82 to the upper part of vessel 6|. to the upper part of generator 54. Analyzer 63 is connected by a conduit 84, an air cooled rectifier 85 and a conduit 65 to an ammonia condenser 61. The ammonia condenser is connected by a conduit 68 to the lower header 89 of an evaporator or cooling element I0. The evaporator comprises a plurality of finned pipe coils connected between the lower header 89 and an upper header II.

The absorber comprises a first part I2 and a second part I3. The absorber part 12 is like the absorber 3| described in connection with Fig. 1. The absorber coil I4 is connected by a conduit I5 to a coil I6 in the absorber part I3. Coil I8 is connected to. water inletconduit I1, and coil I4 is connected to a water outlet conduit I8. Above the coil I4 is a'liquid distributor I9 into which discharges a liquid inlet conduit 8|. The inlet conduit 8| is connected to the lower end of a depending conduit 82 of which the upper end is connected to the upper part Of -absorber I3. The top of absorber I2 is connected by an upward looped conduit 83 to the lower part of absorber I3. In the lower part of absorber I3 above the open endof conduit 83 is a distributing plat or shell 84 which is an inverted perforated tray. The outlet end. of ammonia condenser 61 is vented to the top of absorber I3 by a conduit 85.

The propane condenser 86 comprises a plural- An analyzer 83 is connected q 3 absorber coil I4, and conduit I8. The ammonia condenser 61 and the propane condenser 86 may be provided with fins (not shown) for cooling by ity of vertical tubes 8! connected between an upper header 88 and a lower header 89. The upper header 88 is connected to the top of an absorber vessel 9|. The lower header 89 is connected to a conduit 92 which projects upward into the lower part of absorber vessel 9|. The upper end of conduit 92 is protected by a spaced cover 93. In the upper part Of absorber vessel 9!. is a perforated liquid distributing plate 94. The absorber vessel 9| below the distributing plate 94 is filled with small particles such as Raschig rings 95. The bottom of absorber 9| is connected by a conduit 96 to the bottom .of absorber 73. The lower header 89 is connected by a conduit 91 to the lower header 69 of the evaporator Ill.

The circulation vessel 8| conduit 98, inner passage of changer 99 and a conduit IM to the upper part of absorber 9|. The upper end of conduit IOI discharges in the absorber above the distributing plate 94. The bottom of absorber I2 is connected by a conduit I02, outer passage of the liquid heat exchanger 99 and conduit I03 to the analyzer 83.

The apparatus is constructed of-steel parts welded together and is charged and hermetically sealed as described in connection with the ap paratus shown in Fig. 1,

In operation, the burner 55 heats the coil 60 and generator 54. Cooling water is circulated through conduit 11, absorber coil I6, conduit I5,

is connected by a a liquid heat exlation vessel 8| air, or with jackets (not shown) for water cool- Ammonia vapor is expelled from solution in the generator and in coil 88. Vapor expelled in coil causes upward flow of liquidfrom the lower part of generator 54 into, the circulation vessel 6| by vapor lift action. More than one conduit 59 and coil 68 maybe provided. In larger systems it will be found desirable to provide two or more vapor lift conduits for carrying out the upward flow of weakened absorption solution.

Vapor expelled from solution in the generator 54 accumulates in the upper end of the generator, in conduit 62, and the upper part of vessel 8|. The vapor escapes from the upper end of generator 54 by bubbling through liquid in the analyzer 83. Ammonia vapor flows from the analyzer through conduit 64, rectifier 65, and conduit 66 to the condenser 61. Ammonia vapor is condensed to liquid in condenser 67. The liquid ammonia flows from condenser 57 through conduit 88 into the evaporator I0.

Liquid propane flows from the propane condenser 86 through conduit 9! into the evaporator I0. In the lower header 69 and in the coils I0 the liquid ammonia and liquid propane mix together and evaporate in the presence of each other. The resulting mixture of ammonia and propane vapors flows from the upper header 1| through conduit 80 into the lower part of absorber I2.

Weakened absorption liquid flows from circu through conduit 98, heat exchanger 99, and conduit |0I into the propane condenser-absorber 9|. The weak solution is distributed by perforated plate 94 and flows downward over the Raschig rings or other suitable particles 95 keeping these particles wet. In the lower part ofabsorber 9| absorption solution flows through conduit 98 into absorber I3. The liquid fills absorber I3 to the point of overflow into conduit 82. Liquid overflows from absorber I3 into conduit 82 and flows from the lower end of conduit 82 through conduit 8| into the distributor I9 and the upper part of absorber I2. Absorption liquid is distributed onto the ab sorber cOil I4 and flows downward over the outer surface of this coil.

In absorber I2, ammonia vapor is absorbed out of the vapor mixture into solution flowing downward on coil 74. The enriched solution accumulates in the lower part of absorber I2 and flows from there through conduit I02, liquid heat exchanger 99, conduit I03, and the generator 59.

Vapor pas from the top of absorber I2 through conduit 83 into the lower part Of absorber I3. Vapors issuing from the open end of conduit 83 spread beneath the distributing plateanalyzer 63 back to.

the vapors pass over the wet A local circulation occurs in absorber vessel the propane condenser. circulation'is upward in tubes 91 in the absorber 9| and conduit 92. Vapor becomes less dense in the tubes 81 due to condensation of propane and heavier in absorber 9| due to removal of ammonia vapor. This circulation of vapor from the propane condenser through the absorber 9I keeps the partial pressure of am,- monia in the propane condenser close to equilibrim with the partial pressure of ammonia from the weakened solution in the absorber 9 I.

In Fig. 3 is shown an air cooled system. A generator I is heated by a burner I06. The lower part of the generator is provided with a downward conduit I01. One or more vapor lift conduits I08 is connected from the lower end of conduit IN to the upper part of a. circulation The direction of this vessel I09. Each vapor lift conduit is formed with a coil portion IIO heated by burner I06. The top of generator I05 is connected by a conduit III to the upper part of circulation vessel I09. An analyzer H2 is connected to the upper part of generator I05.

The analyzer H2 is connected by a conduit II 3 to an air cooled rectifier II4 which is in turn connected by a conduit I I5 to the upper end of acondenser H6. The lowerend of condenser H6 is connected by a vessel III and a conduit II8 to a lower header I I9 of an evaporator I20.

Referring to Figs. 3, 5 and 6, the evaporator I' consists of the lower header III! and an upper header I2I between which are connected a plurality of fiat pipe coils I22. The pipe coils I22 are provided with heat transfer fins. The lower part of header I2I is connected to'the upper part of header IIB by a conduit I23. The lower end of each of the pipe coils I22 extends downward into the lower header H9 and is provided with an upright slot I24.

The upper part of header I2I is connected by a conduit I25 to the upper part of an absorber vessel I26. The upper part of vessel I26 is connected by a conduit I21 to the lower end of an absorber coil I26. The coil I28 is provided with heat transfer fins. The upper end of absorber coil I28 is connected by a conduit I29 to the upper end of a condenser I30. The lower end of condenser I30 is connected to the upper part of jacket I3I which is arranged around the upper end of a conduit I33 is connected to the lower evaporator header H9. The lower part of jacket I3I is connected by a conduit I34 to conduit I29. The connection of conduit I34 to conduit I29 is made at a level which is slightly lower than the level of the opening in the upper end of conduit I33 in jacket I3I. The purpose of this is explained below.

The top of vessel II! at the lower end of condenser H6 is connected by a vent conduit I35 to the upper part of absorber vessel I26. I

The lower part of circulation vessel I09 is connected by a conduit I36, the inner passage of a liquid heat exchanger I31, and conduit I38v to the upper part of condenser I30. The bottom of I26 is connected by' a conduit I39, outer passage of the liquid heat exchanger I31, and conduit I40 to the analyzer I I2.

The system is charged with propane, ammonia, and water, or other suitable fiuids as previously set forth. Provision is 'made for causing atmospheric air to fiow in a path that includes first condenser II6, then condenser I30, next absorber I28, and then rectifier I I4. In order not to oomplicate the drawing, this provision is indicated in dotted outline and direction arrows in Fig. 3.

and downward I33. The lower end of conduit .tween the condenser coil I30a The dotted outline indicates an air tunnel and a blower for causing flow of air through the tunnel. Provision is also made for spraying water onto the condensers H6 and I30. These water sprays are indicated at I4I in Fig. 3.

In Fig. 4 there is shown mostly in vertical secon an actual arrangement of parts for use in the dotted outline section of Fig. 3. Referring to Fig. 4, pipes II6a constitute a first condenser. Pipes I30a constitute a second condenser. These condensers are arranged in the order mentioned in an air passage I42 between the air inlet end I43 and the connection of the other end of the passage to the intake of a blower I44. Be-

and blower I44 are zig-zag bafile plates I45. Above the condenser coils H60. and I30a are water spray heads I4Ia having a water supply conduit I46. Below the condenser coils II6a and I30a and the baffles I45 is a trough or sump I4'I having a discharge conduit I48. A liquid pump, not shown, may

be provided for pumping water from conduit I48 v into conduit I46. Make-up water, the connection for which is not shown, is also supplied to conduit I46.

The discharge side of blower I44 is connected to one end of an air passage I49. A finned pipe coil I28a and a smaller finned pipe coil 411 are located in air passage I49 in series respectively between the discharge side of blower air exit I50.

Referring to Figs. 3 an 4, coil I30a may be connected in the system shown in Fig. 3 in the place of coil I30. Coil H60. may be connected in the system in the place of coil II6. Coil I28a may be connected in the system in the place of absorber coil I28. Coil I I4a may be connected in the system in the place of rectifier coil II4.

In operation of the system, burner I06 is turned on and heats the coil or coils H0 and generator I05. Blower I44 is operated to cause air to flow' in series respectively over condenser coil I I6, I I6a, condenser coil I30, I30a, absorber coil I28, I28a, and rectifier coil II4, II4a. Water is discharged fromspray heads I4I, I4Ia to wet the condenser coils'. Free water is disentrained from the air stream by bafiies I45. Excess water accumulates in sump I41 and is drawn from there through conduit I40 and preferably returned to the spray heads. 1

Water on the outer surfaces of the condenser coils evaporates and diffuses into the air causing cooling of the condenser coils toward the wet bulb temperatures of the air. The absorber coil I28, I28a, is cooled toward the dry bulb temperature of air from the blower I44. The rectifier coil II4, M411. is cooled toward the dry bulb temperature of air coming from the absorber.

Heat from the burner I06 causes expulsion of ammonia vapor from-solution in water in the coil or coils H0 and generator I05. Vapor expelled er part of generator I05 Vapor expelled from solution in generator I05 accumulates in the upper part of the generator, in -conduit III and in the upper part of vessel I09. This accumulated vapor presses liquid downward in generator I05 until the vapor bubbles through liquid in analyzer I I2.

Ammonia vapor flows from analyzer II2 through conduit H3 and rectifier II4 to condenser II6. Condenser II6 will be referred to as the ammonia condenser. Due to the previously I44 and the and thence down intermixture of monia, overcoming the tendency of these liquids vapor to that of vapor at the temperature of I30. The absorption liquid flows This reduces the par-' the condenser I30. Decrease in the partial pres sure of ammonia is accompanied by increase in partial pressure of propane vapor toward the total pressure in the system so that the propane vapor condenses to liquid due to the previously described cooling of condenser I30.

Absorption solution and liquid propane flow from the lower end of condenser I30 into the jacket I3I and accumulate in this jacket and in conduit I 34. Liquid propane and the water solution of ammonia are immiscible so that they separate and stratify in jacket I3I with the liquid propane floating on the surface of the solution. Liquid propane is lighter than the water solution of ammonia so that a column of liquid comprising both is lighter than a column of liquid comprising only solution. For this reason the column of liquid in jacket I3I is lighter than the column of liquid in conduit I34 and therefore stands to a higher level. The surface level of liquid increasesin both jacket I3! and conduit I34 until solution overflows from conduit I30 into the upper end of absorber coil I20, and liquid propane overflows into the upper end of conduit I33. The liquid propane flows through conduit I33 into the evaporator I20.

The ammonia feed conduit II 8 and the propane feed conduit I33 form with the evaporator I two liquid traps of which the evaporator is a common leg. Liquid propane accumulates in conduit I 33. Liquid ammonia accumulates in conduit H8. Both ammonia and propane accumulate in the evaporator I 20, filling the lower header II9. the coils I22, andconduit I23. In the evaporator I20, the liquid propane and liquid ammonia come into contact with each other first in'the lower header II9. In the presence of each other, the -ammonia and propaneevaporate, producing a precooling of liquid in the header before it enters the pipe coils I22. In the coils I22, ammonia and propane evaporate in the presence of each other, producing a refrigeration effect for cooling of air in chamber I32 in which the evaporator is situated. A blower, not shown, or other suitable for causing a forced flow of air over the evaporator coils. Vapors formed in the header H9 and in the pipe coils I22 rise through the pipe coils into the upper header I 2I. This upward flow of vapor causes circulation of liquid in the evaporator from the lower header II9 upward through the coils I22 into the upperheader I 2I through conduit I23 back to the lower header II9. More than one conduit facial contact and short diffusion distance. The purpose of the slots I24 in the lower ends of coils I22, as best seen in Figs. 5 and 6, is to provide for introduction of liquid from the header II9 into the tubes I22 from all levels in the header II 9 so that if propane stratifles and floats in the upper part of header II9 it will be nevertheless carried into the coils I22 along with liquid ammonia by vapors formed in the header H9 and escaping therefrom through the slots I24 into the tubes I22.

The mixture of propane and ammonia vapors flows from the upper header I2I through conduit I25 into the' absorber vessel I26 and thence through conduit I21 into the absorber coil I28. Ammonia vapor is absorbed into solution flowing downward in coil I28. Propane vapor flows from the upper end of coil I28 through conduit I I29 into the propane condenser I30. Enriched solution flows from absorber coil I28 through conduit I2'I into absorber vessel I26. Solution flows from vessel I26 through conduit I30, outer passage of the liquid heat exchanger I31 and conduit I40to the analyzer H2 and thence into the generator I05.

The condensation temperature in the propane condenser I30 is somewhat above that in the ammonia condenser II 0. For instance, with a temperature of the condensation temperature in the propane condenser is about 7 about that in the ammonia condenser, the ammonia condensation temperature being about 90 F. and the propane condensation temperature being about 97 F. At this evaporator temperature the absorber and rectifier heat can be rejected at higher temperatures. For these reasons, .the stream of cooling air is caused to flow, as previously described, over first the ammonia condenser H0, then the propane condenser I30, next the absorber I28.

and then the rectifier IM.

I23 may be provided. This circulation of liquid keeps the inside surfaces of the evaporator coils wet, resulting in good heat transfer to the liquid. This liquid circulation also maintains a fine liquid propane and liquid amto stratify into separate layers.

The fine inter mixture of the two fluids results in large inter- It has been found temperature 10 ture of the air condenser. Fig. 3, water ward over the condenser coils II6 and I30 to keep the outer surfaces of these coils wet so that the condenser temperature is dependent upon the wet bulb temperature 'of the cooling air. Due to the available temperature forheat rejection at the condensers, the evaporator temperature will be about 40 F. below the temperature of the ammonia condenser. This characteristic of the system is advantageous in air conditioning, in satisfying inherently the present trend toward maintaining inside air conditions at a certain differential below the conditions of the outside air. The wet bulb temperature represents more than any other single factor the comfort condition of atmospheric air, and with this system it is possible to automatically obtain an inside condition at a given differential below the outside wet bulb temperature. Heretofore this has only been accomplished by differential thermostats .or other complicated controls.

Referring to Fig. 7, the two identical generators burners I54- and I55. Each generator has an analyzer I56 and I51 and arectifier I58 and I59. Each generator also has associated thereand I 6| connected, to circulation vessels I02 and I63.

possible to condense at a F. above the wet bulb tempera- As illustrated diagrammatically in system is providedwith I52 and I53 heated by The upper parts of the generators are connected F. in the evaporator I20,

by using a so-called evaporativefrom nozzles MI is sprayed downand conduit 204 to analyzer I 51.

I65. A liquid heat exchanger has a portion I66 coiled about generator I52. A liquid heat exchanger I61 has a portion coiled about generator I53. There are two weak liquid cooling coils I68 and I69. There are two ammonia condensers I10 and HI. There is an absorber-liquid heat exchanger I12. The liquid heat exchangers, the ammonia condensers, and the weak liquid coolers are formed by coiled concentric tubes.

Circulation vessels I62 and I63 are connected by conduits I13 and I14 respectively to liquid heat exchangers I66 and I61, which in turn are respectively connected by conduits I15 and I16 to weak liquid coolers I68 and I69. Rectifiers I58 and I59 are provided with water cooling coils I11 and I18. The rectifiers are connected by conduits. I19 and I80 to a vessel I8I which is in turn connected by conduits I82 and I83 .to ammonia condensers I10 and HI.

The lower ,ends of condensers I10 and HI are connected by conduits I84 and I85 to a vessel I86 which is in turn connected by conduit I81 to a vessel I88. The'bottom of vessel I88 is connected by a conduit I89 to the lower header I90 of an evaporator I8I.

The evaporator I9I comprises a lower header I90 and an upper header I92 between which is connected one or more finned pipe coils I93.

The upper header I92 is connected by a conduit .I94 to a vessel I95. The bottom of vessel I95 is connected by a conduit I98 to a lower header I90. The top of vessel I95 is connected by an upward looped conduit I91 to the lower part of an absorber I98.

Absorber I98 comprises a vessel containing water cooling coils I99. In the lower part of the vessel Isa perforated distributing plate 200. The end of conduit I91 projects into absorber I98 and is open beneath the center of plate 200. The bottom of absorber I98 is connected by a conduit 20I, outer passage of liquid heat exchanger I66, and conduit 202 to analyzer I56. The bottom of absorber I98 is connected by a conduit 203, outer passage of liquid heat exchanger I61, The top of absorber I98 is connected by an upward looped conduit 205 to the lower part of a second absorber 206. The bottom of absorber 208 is connected through a conduit 201, a cooler 208, and a conduit 209 to an intermediate part ofabsorber I98.

Absorber 206 is filled nearly to thetop with small particles such as Raschig rings. Above thelmass of particles is a perforated distributing plate 2I0. One end of a weak liquid line 2 is connected to the upper part of absorber 206 and discharges onto thedistributing plate 2").

-

duits

229 and 230 to one end of the water jackets.

to the circulation vessels by conduits I64 and 220. The bottom of conduit 22I is connected by aconduit 222 to the lower evaporator header I90.

Vessel 2I8 is connected from a point Just below the connection thereto of conduit 220 by a downward looped conduit 223 to the bottom of condenser 2I4.

Condenser 2l4 is a closed vessel containing water cooling coils 224. Above the coils 224 is a liquid distributingtray 225. The upper part of condenser 2I4 is connected by a conduit 226 to weak liquid cooler I68. The end of conduit 226 projects into the upper part of condenser 2I4 and discharges into the distributing tray 225. The endof conduit 2I3 projects into the lower part of condenser 2 I4 and is provided with open ings below the cooling coil 224.

A water inlet conduit 228 is connected by conof weak liquid coolers I28 and I29.

Water pipes

23I, 232, 233, 234 and 235 connect the liquid coolers I68 and I69 to the ammonia condensers I10 and HI.

Water pipes

236, 231 and 238 connect the ammonia condensers I10 and HI to the lower end of cooling coil 224 in the propane condenser 2I4. The upper end of cooling coil 224 is connected by a conduit 239 to the lower end of cooling coil I99 in absorber I98. The upper end of cooling coil I99 is connected by a conduit 240 to one end of the intermediate absorber cooler 208. The other end of cooler 208 is connected by a water pipe 2 to the upper ends of the rectifier cooling coils I11 and I18.

The lower ends-oi coils I11 and I18 are connected by

conduits

242 and 243 to a water discharge conduit 245.

The system is charged with propane, ammonia, and water; A, charging valve, not shown, may be provided in the absorber I98 at the surface level of liquid shown therein so that the liquid can be adjusted to this level.

In operation of the system, burners I54 and I55 heat generators I52 and I53. Water entering through conduit 228 flows through-the previously described pipe \connections respectively through weak liquid coolers I68 and I69, ammonia condensers I10 and HI, propane condenser cooling coil 224, absorber cooling coil I99, intermediate absorber liquid cooler 208, and rectiiier cooling coils I11 and I18.

Ammonia vapor is expelled from solution in generators I52 and I53 and in the coiled portions of conduits I and I6I. Vapor expelled in conduits I 60 and I6I causes upward flow of *liquid through these conduits from the gener- The other end of conduit 2" is connected to' weak liquid cooler I69. A vent line 2I2 is connected from the top of absorber 206 to the top of vessel I88. The top of absorber 206 is connected by a conduit 2I3 to the lower part of a condenser 2I4. An intermediate part of absorber 206 is connected by a downward looped conduit 2I5 to the bottom of a vessel 2I6.

The upper part of vessel 2I6 is connected by a downward looped conduit 2I1 to the bottom of a vessel 2I8. The top of vessel 2I6 is connected by an upward looped conduit 2I9 tothe top of vessel 2I8. The upper part of vessel 2I8 is connected by aconduit 220 to the upper part of condenser 2 I4. A closed end conduit 22I is connected to the upper part of vessel 2I8'at the same level as the connection thereto of conduit ators into the circulation vessels I62 and I63.

Vapor expelled from solution in the generators I52 and I53 bubbles throughliquid in the analyzers I66 and I51 and then flows through rectifiers I58 and I 59, conduits I19 and I80, vessel I8I, and conduits I82 and I83 to the ammonia condensers I10 and HI. Ammonia vapor is condensed toliquid in the condensers I10 and HI. Liquid ammonia flows from the condensers through conduits I84 and I85, vessel I86, conduit I81, vessel I88, and conduit I89 into the evaporator .I9I.

weakened absorption liquid flows lation vessel I62 through conduit I13, inner passage of liquid heat exchanger I66, conduit I15, weak liquid cooler I68, and conduit 226 into the distributing tray 225 in the upper part of propane condenser 2I4.

weakened absorption liquid flows from circulation vessel I63 through conduit I14, inner passage of liquid heat exchanger I61, conduit I16,

from circu-' overflows tray 225 and'descends on the surfaces of the cooling coils 224. Ammonia vapor is.absorbed into solution in the descending. absorption liquid, reducing and maintaining the partial pressure of ammonia in the propane condenser so that it is at a value which is substantially the partial pressure of ammonia vapor from the weak solution at the propane condenser temperature. The liquid accumulates in condenser 2M and conduit 223 and the surface level rises to the overflow points in vessels 2I8 and 2I6. Due to the reduction in partial pressure of ammonia in condenser 2M, the partial pressure of propane increases toward the total pressure in the system and then condenses to liquid. The liquid propane is immiscible and separates from the solution and 2c floats on the surface in the condenser 2M. Liquid overflows from condenser 2I4- through conduits 220 and 223 into vessel 2I8. Liquid over-' flows from vessel 2I8 through conduit 2I'I into vessel 2I6. through conduit HI and conduit 222. Conduits 223 and 2I1 are connected to the bottoms of condenser 2M and vessel 2I8 so that liquid flowing through these conduits is solution from which liquid propane is separated by stratification. Liquid which overflows from condenser 224 through conduit 220 into vessel 2I8 and which overflows from vessel 2I8 through conduits 22! and 222 is liquid propane floating on the surface of solution.

Separation by Stratification occurs in both the propane condenser 214 and vessel 2l8. Stratiflcation in vessel 2I8 separates from solution any liquid propane that may enter vessel 2I8 through conduit 223 from the condenser.

Liquid propane which overflows into conduit 222 enters evaporator I 9I and there joins liquid ammonia. The liquid propane and liquid am monia mix in header I90 and coils I93 and evaporate in the presence of each other, producing a refrigeration effect, as previously described in connection with other modifications of this system. The vapor causes upward flow of liquid from lower header I90 through coils I93 to upper header I92. Liquid returns from the upper header through conduit I94, vessel I95 and conduit I96 to the lower header I90. This circulation of' liquid keeps the evaporator coils wet inward for efficient heat transfer, and the ebullition due to formation of gas below the surface thereof keeps the propane and ammonia liquids intimately mixed, producing large interfacial contact and small diffusion distance.

A mixture of vapors from the evaporator I9! flows through conduit I97 into the lower part of the bubble type absorber I98. Vapors issuing from the open end of conduit I91 spread beneath the perforated plate 200 and pass upward through the plate in the form of bubbles which rise to the surface of the liquid and enter the top of In the bubble absorber I 98, the

this absorber. strongest vapors meet the strongest solution at the highest temperature in the absorber system. Most of the ammonia Vapor is absorbed in the bubble absorber I98. About to 80% of the absorption that takes place occurs in this bubble 70 absorber. I

The vapor mixture, with the partial pressure of ammonia greatly reduced, flows from the bubble absorber I98 through conduit 205 into the lower end of the packed absorber tower 206. The

Liquid also overflows from vessel 2I8 25 place. Vapor containing only a very small amount of ammonia, 5% or less, flows from the upper end of absorber tower 206 through conduit 2I3 into the lower part of propane condenser 2M. The vapor issues through the holes in the end of conduit 2I-3 and bubbles upward through liquid in the condenser 2M. The bubbles rising through the cooling liquid in condenser 2M collapse due to the condensation of propane and the absorption of the residual ammonia. The propane condensed to liquid stratifles and is separated from the solution as previously described.

Absorption liquid flows from the bottom of the absorber tower 206 through conduit 201, cooler 208, and conduit 209 into the bubble'absorber I98. Solution flows from the bubble absorber I98 through conduits 20I and 203, outer passages of liquid heat exchangers I66 and I61, and

conduits

202 and 204 into the analyzers I56 and I51, and thence back into the generatbrs I52 and I53.

During operation of this. system, the pressure from the evaporator I9I is higher than that in the upper part of condenser 2 by the hydrostatic head of liquid standing to the levels shown in absorber I98 and condenser 2M. In returning the propane condensate from the condenser 2| 4 to the higher pressure of evaporator I9I an overbalancing column of liquid is formed to the level indicated in conduit 222. The pressure from evaporator I 9| is also higher than that in the condensers I10 and IN by the hydrostatic head of liquid in the absorber I98. In returning the ammonia condensate from the condensers I10 and III to the higher pressure of evaporator I 9|, an overbalancing column of liquid is formed to the level indicated in vessel I88 and conduit I89.

What is claimed is:

1. A method of refrigeration which includes evaporating a plurality of refrigerant fluids in the presence of each other, separating one refrigerant fluid from another in the resulting vapor mixture by absorption into a-liquid. separating said first refrigerant fluid from solution by distillation, condensing said second refrigerant fluid to liquid, bringing said absorption liquid into the presence of said second refrigerant fluid while the latter is undergoing condensation, and dissipating the heat of said condensation at a temperature lower than that at which the heat of saidabsorption is dissipated by first transferring heat of condensation to a body of cooling fluid and then transferring heat of absorption to said body of cooling fluid.

2. A method of refrigeration as set forth in claim 1 in which heat of condensation from said I distillation step is first transferred to said body 8 monia and propane respectively and said absorption liquid is water.

5. A refrigeration system having a first circuit comprising a generator, condenser, evaporator, and absorber, and a second circuit comprising said evaporator, said absorber, and a second condenser, said system containing a plurality of refrigerant fluids such as ammonia and propane, and a liquid absorbent for one of said refrigerants such as water, said circuits being connected.

so that absorption liquid flowing toward the absorber in said first circuit flows through the condenser in said second circuit, and means for separating liquid refrigerant condensed in said second condenser from the absorption liquid.

6. A refrigeration system as set forth in claim in which said first circuit includes a plurality of absorbers connected in series.

'7. A refrigeration system as set forth in claim 5 in which said first circuit includes a plurality of absorbers connected in series, one of said absorbers being of a type in which vapors bubble through liquid.

-8. A refrigeration system as set forth in claim 5 in which said first circuit includes a plurality of absorbers, and the circuits are connected and arranged so that only a portion of said absorption liquid flows through the condenser in said second circuit.

9. A refrigeration system as set forth in claim 5 in which vapor bubbles through liquid in the condenser in said second circuit.

10. In a method of refrigeration which inevaporator comprising upper and lower headers connected by one or more pipes or pipe coils arranged for upward flow of vapor and liquid cludes evaporation of a plurality of fluids inthe presence of each other, that improvement which consists in bringing the fluids together in liquid phase and forming thereof one or more bodies having relatively small horizontal cross-sectional area so that ebullition due to formation of vapors below the surface level of the liquid will keep the several liquids thoroughly mixed and thereby have large interfacial contact surfaces and short vapor diffusion distances.

11. Apparatus for carrying out the method of refrigeration as set forth in claim 10 including an evaporator having one or more pipes or pipe coils of relatively small diameter for forming said body or bodies of liquid, and constructed and arranged for continuous upward flow of vapor therein.

12. In a method of refrigeration which includes evaporation of a plurality of fluids in the presence of each other, that improvement which consists in mixing the fluids together in liquid phase to effect evaporation thereof, .and utilizing the resulting vapors to cause ebullition and further thorough mixing of the liquids and also to cause upward flow of the liquids by vapor lift action to effect good heat transfer to the liquid.

13. Apparatus for carrying out the method of refrigeration set forth in claim 12 including an evaporator comprising one or more pipes or pipe coils having a relatively small internal diameter and arranged for continuous upward flow of vapor and liquid therein.

14. Apparatus for carrying out the method of refrigeration set forth in claim 12 including an evaporator having upper and lower headers connected by one or more pipes or pipe coils, the lower ends of said pipes or pipe coils extending downward into the lower header and having upright slotstherein so that liquid may enter from different levels in the lower header.

15. Apparatus for carrying out the method of refrigeration as set forth in claim 12 including an therethrough from the lower header to the upper header, and one or more conduits for return flow of liquid from the upper header to the lower header.

16. An evaporator for use in a refrigeration system utilizing evaporation of several fluids in the presence of each other, and including a vessel, connections for admitting several fluids in liquid phase to said vessel, and a conduit extending upward from said vessel, the lower end of said'conduit communicating with said vessel at a plurality of levels therein.

1'7. An evaporator as set forth in claim 16 which also includes a conduit for return of liquid from the upper end of said upward extending conduit to said vessel.

18. An evaporator as set forth in claim 16 which also includes aseparating vessel for vapor and liquid at the upper end of said upward extending conduit, and a further conduit for flow of liquid from said separating vessel to said lower vessel.

19. In a method of refrigeration which includes evaporation of a plurality of fluids in the presence of each other, that improvement which consists in bringing the fluids together in liquid phase to effect evaporation thereof, and utilizing the resulting vapor to cause upward flow of the liquids in the presence of each other.

20. A method of refrigeration which includes bringing together a plurality of fluids in liquid phase to effect evaporation of the liquids in the presence of each other to produce a refrigeration effect, and causing upward flow of the liquids in one place and downward flow of the liquids in another place, and withdrawing vapor from the presence of the liquid intermediate said places.

21. A method of refrigeration which includes condensing refrigerant fluid to liquid at a certain pressure, evaporating said liquid refrigerant in the presence of another fluid at substantially the same total pressure as said condensing pressure,

causing the liquid refrigerant to flow upward in one place and downward in another place, and

withdrawing vapor from the presence of the.

liquid intermediate said places.

22. A refrigeration system having a place of condensation, a place of evaporation, means for conducting liquid refrigerant from said place of condensation to said place of evaporation, means for conducting a pressure equalizing fluid to said place of evaporation to equalize the pressure at said place of evaporation and said place of condensation, means for causing liquid refrigerant to circulate in a' definite orbit in said place of evaporation, and means to 'withdraw vapor from the presence of liquid in said orbit.

23. Refrigeration apparatus including a condenser, an evaporator having one or more conduits providing one or more definite orbits for fluid circulation, a conduit for conducting liquid refrigerant from saidcondenser to said evaporator, a conduit for admitting an auxiliary pressure equalizing fluid to said evaporator to equalize the pressures in said evaporator and said con.- denser, and a conduit for withdrawing vapor from said evaporator, the one or more orbit forming conduits being sufllciently narrow so that vapor formed by evaporation of liquid causes circulation of liquidtherein.

24. A refrigeration system comprising a generator, a condenser, an evaporator, an absorber,

said generator and absorber being connected for circulation of absorption liquid therethrough and therebetween, said condenser being connected to receive vapor from said generator and deliver liquid to said evaporator, and said absorber beand comprising an evaporator arranged for coolliquid from said generator to said absorber, said system containing ammonia, water, and propane.

25. A refrigeration system comprising a generator, two condensers, an evaporator and two absorbers, one of said condensers being connected to receive vapor from said generator and deliver liquid to said evaporator, said generator being connectedfor circulation of'liquid therefrom through said absorbers in series, one of said absorbers being connected with the other of said condensers for circulation of vapor therethrough and therebetween, said second condenser being connected for delivery of liquid to said evaporator, connections for flow of vapor from said evaporator to the other of said absorbers and thence to said first absorber, and said system containing ammonia, water and propane.

26. In a refrigeration system having a stillevaporator-absorber circuit for ammonia and a condenser-evaporator-absorber circuit for propane, a second absorber connected to receive weakened absorption liquid flowing in said first circuit and connected with the condenser in said second circuit for circulation of vapor therethrough and therebetween.

27. A refrigeration system including anevaporator, a plurality of condensers, an absorber, and a generator interconnected to form a stillevaporator-absorber circuit and a condenser! evaporator-absorber 'circuit, means for flowing atmospheric air first in heat transfer relation withsaid condensers and then in heat transfer relation with said absorber, said condensers being cooled by evaporation of water in the presence of said air sothat said evaporator will be automatically maintained at a temperature which is at a certain value below that of the wet bulb temperature of the atmosphere.

28, A refrigeratiton system as set forth claim .27 also including a rectifier connected said still circuit and arranged to be cooled last by said air. I

ing of air to be conditioned, an absorber,said evaporator and absorber being included in both a still-evaporator-absorber circuit and a condenser-evaporator-absorber circuit, said system containing propane and ammonia which evaporate in the presence of each other in said evaporator at a temperature which is directly proportional to the temperature of the condensing portion of said still-evaporator-absorber circuit, and coolers for the heat rejecting parts of said system, the cooler for said condensing portion utilizing evaporation of water in the presence of atmospheric air so. that said evaporator will be automatically maintained at a temperature which is' directly proportional to the wet bulb temperature of the atmosphere.

30. A refrigeration system for conditioning air and comprising a first circuit having a generator, a first condenser, an evaporator, and an absorber, a second circuit having a second condenser and-including said evaporator and absorber, said system containing a plurality of re: frigerant fluids which evaporate in the presence of each other in said evaporator at a temperature which is directly proportional to the temperature of said first condenser, and coolers for the heat rejecting parts of the system, the cooler for said first condenser utilizing evaporation of water in the presence of atmospheric air so that said evaporator will be automatically maintained at a temperature which is directly proportional to the wet bulb temperature of the atmosphere.

31. A method of refrigeration which includes evaporating a plurality of refrigerant liquids in the presence of each other, utilizing the refrigcrating effects thus produced to cool air to be conditioned, absorbing one of said refrigerants out of the resulting vapor mixture, condensing another of said refrigerant vapors to liquid state for re-use in said evaporation step, expelling the absorbed refrigerant from the absorbent, condensing the expelled refrigerant from vaporous to liquid state for re-use in said-evaporation step, said evaporation taking place at a temperature which is directly proportional to the temperature at which said expelled refrigerant is condensed, and carrying out condensation of the expelled refrigerant'by heat transfer to water evaporating in the presence of atmospheric air so that the evaporation step will take place at a temperature .which is directly proportional to the wet bulb temperature of the atmosphere.

ALBERT R. "THOMAS.

29. A refrigeration system for conditioning air