US2035499A - Absorption refrigerating apparatus - Google Patents

Description

March 31, 1936. R s NELSNON 2,035,499

ABSORPTION REFRIGERATING APPARATUS Filed July 17, 1933 4 Sheets-Sheet l fig].

fflMe aifi Map/b of 726mm March 31, 1936. R. s. NELSON ABSORPTION REFRIGERATING APPARATUS Filed July 17, 1933 4 Sheets-Sheet 2 March 31, 1936. R. s. NELSON ABSORPTION REFRIGERATING APPARATUS Filed July 17, 1933 4Sheets-Sheet 5 Dw/M' March 31, 1936.

R. s. NELSON 2,035,499 ABSORPTION REFRIGERATING APPARATUS Filed July 1'7, 1933 4 Sheets-Sheet 4 r; m w -I\ 1 l w Patented Mar. 31, 1936 UNITED STATES:

PATENT OFFICE Rudolph S. Nelson, Rockford, 111.,

assignor to The Hoover Company, North Canton, Ohio, a

corporation of Ohio Application July 17, 1933, Serial No. 680,749

Claims. (01. zen-21) This invention relates to absorption refrigerating apparatus and more particularly ,to the construction of the absorber and the manner of cooling the same to adapt it for use in household re- 5 frigerating cabinets or the like.

The present application is a continuation in part of the co-pending application of Rudolph S. Nelson, Serial No. 539,450 filed May 23, 1931 for Absorption refrigeration. The present applilo cation contains claims drawn to the absorber per se disclosed in the parent application in accordance with the requirement for division in the parent application. The present case also contains claims generic to the co-pending applil5 cations of Rudolph S. Nelson, Serial No.'680,750, filed July 17, 1933; Serial No. 680,751, filed July 17, 1933 and which has now become Pat. #l,993,378, issued Aug. 10, 680,752, filed July 17, 1933 and which hasnow 2o become Pat. #l,993,379, issued Aug. 10, 1934'.

An object of the invention is to promote more effective absorption in an absorber by providing means for discharging heat rapidlyand at the same time providing means for reducing the 25 vapor pressure of therefrigerant to a minimum possible at the temperature of the cooling medium. The realization of this object is particularly advantageous when used in air cooled upper ratuses of the type in which an inert gas is em- ,30 ployed as illustrated below, but the invention is not limited to such apparatuses.

Other objects and advantages reside in the novel arrangement and construction of various parts together with the methods or processes ef- 35 fected therein as will be pointed out hereinafter in connection with the following description, taken in connection with the accompanying drawings in which:

Figure 1 is a schematic diagram of a complete 40 refrigerating system illustrating the principles of the invention and in which the parts are spread out to permit a better understanding of the mode of operation.

Figure 2 is a view in elevation of the absorber 45 and its connected parts of an actual refrigerating apparatus operating in accordance wit h'lthe principles of the diagrammatic showing of Figurel. Figure 3 is a cross sectional view of a part of the absorber shown in Figure 2, and of a system 50 for indirectly cooling the same, certain parts of the cooling system being broken away or shown in cross section.

Figure 4 is a cross-sectional view of the absorber vessel of Figure 3, being taken on the line 55 4-4 thereof.

1934; Serial No.'

" ments together with minor devices constituting end in the boiler, since it causes Figure 5 is a view in elevation of a modified form of refrigerating apparatus constructed in accordance with the principles of the invention, certain of the conduits being cut away for convenience in illustrating. 5

Figure 6 is a diagram illustrating the manner in which the various conduits of the apparatus of Figure 5 are connected.

Figure 7 is a view in elevation of a further modification of the invention, certain condults lO having. been broken for purpose of illustration, and Figure 8 is a diagram of the absorber and associated parts of the apparatus of Figure 7.

Referring first to Figure 1 of the drawings, 5 wherein the invention is schematically illustrated as embodied in an air cooled system employing inert gas, the apparatus is shown as consisting of a boiler B, a gas separatingchamber S, a rectifier 'R, a main condenser C, an evaporator E and an absorber A as essential parts, these being connected by a number of conduits, some of which are in heat exchange relation, these elethe complete refrigerating unit.

The boiler B consists of a. horizontally disposed cylindrical vessel l0 having the cylindrical dome H mounted thereon. Provision is made for heating the boiler by passing heat through the tube ii in the lower portion of the cylinder 10, the tube being adapted to receive an electric cartridge heater l3 or other heating means. Ahsorption liquid is supplied to the boiler through the conduit 14 which enters the cylinder Ill above the tube 12 and extends nearly the entire distance across the cylinder I'D in close proximity with the tube I 2 so as to warm'the entering absorption liquid as it enters the boiler. This arra'igement also prevents the formation of a dead the entering 40 liquid to stir or agitate that already in the vessel and produce an eddy current.

A small conduit 15, preferably of about A, inch inside diameter functions as a gas lift pump to convey both the vaporized refrigerant and the weakened absorption solution to the top of the separator S. 'The liquid is lifted by the passage of bubblesof gas through the conduit l5 as is now well known in the absorption refrigerating art.

The gas separating chamber S is merely a vertically disposed pipe which may be of about 1 inch in diameter. As will be described later, it is provided with a jacket 50. At thebottom of the gas separating chamber S, a conduit l6 provides sump at the lower end thereof,

2 for the flow of absorption solution downwardly through to the outer jacket I! of a liquid heat exchanger consisting of the jacket l1 and the conduit l4. From the jacket I! a conduit l8 conveys liquid to the absorber. Near its lower end the conduit I8 is coiled or reversely bent as shown at l9 to provide means for discharging heat from the liquid to the atmosphere. This coil as well as all the heat dissipating elements of the unit may be provided with heat radiating fins, if desired.

The absorber itself is made of three parts designated 2|, 22, and 23. The upper part 2| and the lower part 23 are made of pieces of pipe of an inch or an inch and one-quarter in diameter welded or otherwise secured to each other so as to form a tortuous path. The actual construction of these parts is best shown in Figure 2 wherein the vessels 2| and 23 are shown as made of horizontal pieces of pipe having beveled ends connected by similar but shorter vertical sections, while the vessel 22, like that of previously known absorbers, consists of a closed vertically disposed cylinder having a series of staggered baflle plates 24 therein (see Figs. 1 and 3).

The absorption liquid flows sorber merely by gravity, passing first across the horizontal pieces of pipe in the part 2| into a then through a pipe 26 which is provided with a U-bend to prevent the passage of gas therethrough into the part 22. A second U-pipe 2! is connected to the bottom of part 22 for draining liquid into the part 23. After flowing across the pieces of pipe in the lower part, the absorption solution drains into a reservoir 28 from which it flows back to the boiler B.

The refrigerant vapors generated in the boiler B after being conveyed through the gas lift pump conduit I5 as mentioned above, pass through the rectifier R which may be an integral part of the separator S provided with a series of rectifier cups or plates 29 on the inside thereof and a series of heat radiating fins 30 on the outside. From the rectifier the vapor passes through the conduit 3| into the condenser C. If the condenser is air cooled it must have a larger heat discharging area than would be required were the condenser water cooled. Small size tubing ,4; or inch inside diameter) provided with heat radiating fins is now extensively used in the art and may be used in the present case for the condenser. The condenser is preferably located on the top of the refrigerator cabinet so as to be freely exposed to the air.

As the refrigerant condenses in the condenser it passes into a small chamber 32, the upper end of which may be connected by conduit 34 to the gas conduit 5|, as shown, or to the conduit 52 or heat exchanger 33. The conduit 34 provides for the removal of any inert gas which might otherwise accumulate in the vessel 32. A conduit 35, the upper end of which is beveled, connects the lower portion of the chamber 32 to the evaporator E for conveying condensate to the latter. The conduit 35 first passes downwardly to a point below the gas heat exchanger 33 and then upwardly through the same as shown.

The evaporator may be of the usual type, consisting of a cylinder closed at the top and bottom and provided with a series of baiiie plates 36 arranged in staggered relation to provide sufficient surface to bring the refrigerant into intimate relation with the inert gas therein so as to promote through the ab- I evaporation thereof. A gas conduit 31 connects the upper portion of the evaporator to the upper part of the gas heat exchanger 33 while a gas conduit 38 connects the lower portion of the evaporator to the central part of the gas heat exchanger 33:

The gas heat exchanger itself, consists of a vertically disposed outer cylinder provided with end pieces 40 and 4| and two inner partitions designated 42 and 43, each disposed a short distance from the end pieces 40 and 4|. A plurality of tubes 44 connect the chambers formed by the end pieces 48 and 4| and the partitions 42 and 43 so that the gas may flow downwardly from the upper chamber to the lower. Thus the gas enters the heat exchanger from the evaporator through the conduit 31 and is discharged through the conduit 45 By providing bafiies such as illustrated at 46 heat may be effectively transferred from one gas stream to the other. As is shown in Figure l the upper of these baflles is connected to and extends inwardly and upwardly from the outer cylindrical wall of the heat exchanger from a point just below that where the conduit 38 is connected thereto. This baflle together with those arranged in staggered relation in the lower part have the effect of lengthening the heat exchanger in that they cause gas which enters the central part of the heat exchanger from the absorber through a conduit 41 to fiow back and forth across the pipes 44 as indicated by the arrows, as they pass to the top of the central portion of the heat exchanger and then downwardly to the left of the upper baflie 46, and out through the conduit 38 to the evaporator.

In order to prevent the accumulation of liquids in the evaporator and in the gas heat exchanger the lower portion of the baffle is provided with an opening as indicated at 48 while the lower portions of the gas heat exchanger are provided with drain pipes 49 provided with U- bends for draining liquid into the reservoir 28. Coming from the heat exchanger through the conduit 45, the inert gas flows to a jacket 50 surrounding the gas separating chamber S. In passing upwardly through this jacket, it is heated by the separator so as to facilitate circulation. It then passes through a short horizontal conduit 5| into a conduit 52, the upper end of which is provided with a venturi 53 and a nozzle or jet 54 fed by refrigerant gas from the boiler B through a conduit 55. This imparts a further driving impulse to the gases.

The lower end of the conduit 52 is connected to the absorber. It will be seen that not only is the absorber of an unusual construction but the inert gas flows therethrough in a very peculiar manner. The gas first passes from conduit 52 to the bottom of the part 22 of the absorber. In the construction shown, a large portion of the absorption takes place in part 22 and this vessel may be regarded as the main part of the absorber, the parts 2| and 23 being in a way only auxiliary thereto. The inert gas passes upwardly through the vessel 22 then out at the top through a conduit 53 which conveys it to the lower portion of the part 23. After flowing upwardly therethrough it passes upwardly through a conduit 54 and into the lower end of the part 2|, from which it passes back to the gas heat exchanger through the conduit 41 and then back to the evaporator.

The main part or section 22 of the absorber opcrates at a high temperature and discharges a considerable quantity of heat due to the fact that it is in this section that the greater amount of absorption takes place, the absorption of course generating heat. It is thus possible to provide for a. large heat discharge from the absorber vessel 22 so that it may be directly air cooled and at the same time limit the dimensions to the small space provided in an ordinary refrigerator cabinet. When so constructed improved operation over that of an ordinary absorber results from the fact that the vessel 22,, being relatively warm dissipates a large amount of heat while the parts 2! and 22 dissipate a lesser amount of heat but operate tofurther reduce the vapor pressure of the refrigerant than is possible in the vessel-22 due to the fact that they operate at a temperature very near that of the cooling medium, which in this case is the air. Thus it is advantageous to provide an arrangement in which the part 22 is thermally isolated from the other parts to prevent it from warming the latter.

In accordance with the present disclosure means is provided not only for thermally isolating the part 22 from the other parts, to a large extent, but also for transferring the point of ultimate heat discharge for the part 22 to a location where the air may freely circulate. This is accomplished by a novel indirect cooling system now to be described and on which a transfer of heat is effected partly by flow of a cooling medium in heat transfer relation with the absorber vessel 22 and partly by vaporization of a portion of this cooling medium. In Figure 1 this indirect cooling system is indicatedas consisting of a jacket 60 surrounding a portion of the absorber vessel 22, a small vertically disposed conduit 6| which functions as a gas lift pipe, a gas separating chamber or vessel 62, a condenser 63 connected to the separator 62 by the conduit 64 and a return conduit 65, and a smallhorizontal conduit 66 connecting the lower portion of the gas separating chamber to the mid-point of the conduit 65. The conduit 65 before making connection with the jacket 66 extends to a point well below that vessel and is provided with a number of heat radiating fins as indicated.

The actual construction of the indirect cooling system is shown in detail in Figures 3 and 4. As .will be seen a series of small. pipes 61 are used instead of the jacket 66 of Figure 1, these pipes being brought into communication with eachother at the top and bottom by means of headers 68. The conduits themselves are sufficiently small to function as gas lift pumps so that a conduit such as indicated at 6| in. Figure 1 is unnecessary. Aside from this the arrangement is the same as indic ated in Figure 1, the system acting to dissipate heat frcm the absorber vessel 22 by causing the transfer of heat to the condenser coil 63 and to the heat radiating fins on the lower portion of the conduit 65. It will be seen that with this arrangement, the coolingsystem is not connected to the remainder of the apparatus for the fiow of fluids. Certain features of the invention are not limited to this cooling system, however, andmight be used with other arrangements.

This cooling system may be filled with a liquid such as ammonia to approximately the central portion of the separating chamber 62. Upon heat being transferred from the vessel 22, to the pipes 61 a portion of the refrigerant will be vaporized and will pass upwardly through these conduits and in so doing carry the remainder of the liquid with it into the gas separating chamber 62. From the gas separating chamber the liquid will flow through the conduit 66 into the lower portion of the conduit 65 and return to the gas lift pumps 61. The generated vapor conveyed to the gas separating chamber 62 will pass through the condenser coils 63 wherein it will condense and then return to the conduits 61 through the return pipe 65. In this way the absorber vessel 22 is cooled to some extent by the convection of the liquid refrigerant which circulates through the conduit 66 and the lower portion 65 but mainly by vaporization of refrigerant which circulates through the conduits 61, condenser 63 and the return conduit 65. Some heat is also discharged directly to the atmosphere from the vessel 22 but this quantity is small compared to that discharged through the condenser 63.

Figure 2 illustrates one way of assembling the apparatus diagrammatically shown in Figure 1 at the side or back of a refrigerating cabinet. To avoid complications in illustrating, the indirect cooling system for the absorber vessel 22 is not shown in Figure 2. The manner in which this cooling system is incorporated into the apparatus will be apparent however, from an inspection of Figure 3. In Figure 2,- the parts corresponding to those of Figure 1 are similarly designated and a detailed description is deemed unnecessary.

As shown, the parts 2| and 23 of the main absorber are preferably provided with a number of heat radiating fins so as to cause these parts to operate at as low a temperature as is possible with air cooling.

The apparatus disclosed may be charged and operated as follows, using ammonia, water and hydrogen as the refrigerant, absorption liquid and the inert gasrespectively, although of course the invention is not limited to the use of these fluids.

Ammonia solution of 25 to 30% concentration may be supplied to the unit through a valve on the reservoir 28. While the boiler is being heated by passing two or three hundred watts through the electric cartridge heater so as'to cause circulation of the solution, the unit should be swept free of insoluble gas by means of ammonia gas. Hydrogen may then be introduced up to 250 to 350 pounds gage pressure. The hydrogen is. of course, introduced at some point either in the evaporator or the absorber by means of a valve not shown. After the hydrogen is introduced the heat input may be increased to 400 watts. After the unit is so charged it may be necessary to trim theunit,thatis, remove a certain excess of solution or hydrogen depending on the operating conditions. The solution should, of course, not stand above the gas inlet to the absorber. level of the solution is too high the solution may circulate too fast.

The indirect cooling system for the absorber vessel may then becharged and put into operation. It should first be evacuated to remove as much air as possible and then swept out with a stream of ammonia gas. Liquid anhydrous-ammonia may then be added to a level above the gas separating chamber of this system. By putting in an excess of liquid ammonia and then purging the condenser from time to time after the unit has been in operation a little while the last traces of foreign gases may be finally removed.

From the above description it will be apparent that the absorption solution will circulate as follows: From the boiler B through the gas lift pump I5, gas separating chamber S, conduit l6, heat exchanger IT and conduit IE to the absorber,

Also, if the after being precooled by passing through the reversely bent pipe l9. After passing downwardly through the absorber into the reservoir 28 it flows back to the boiler through conduit I4.

The circuit for the refrigerant is from the boiler B through the gas lift pump |5, rectifier R, conduit 3|, condenser C, vessel 32, conduit 35 into the evaporator where the ammonia evaporates. It is then carried by the inert gas through the conduit 31 into the heat exchanger, passes from the top to the bottom through the tubes 44 and leaves through the conduit 45. It then flows upwardly through the jacket 5|) around the gas separating chamber, passes through conduits 5| and 52 and into the absorber where the refrigerant is absorbed by the absorption solution and carried back to the boiler through the reservoir 28 and conduit H.

The inert gas circuit, particularly the manner in which the gas passes through the absorber constitutes an important feature of the invention. Starting with the evaporator the gas flows through the conduit 31, then through the tubes 44 of the heat exchanger, conduit 45, jacket 50, conduit 5| into the conduit 52 where the nozzle 55 imparts a driving force thereto, then into the lower part of absorber vessel 22, upwardly through this vessel, out through the conduit 53 into the bottom of the lower absorber vessel 23, upwardly through the vessel 23, then by the conduit 54 to the bottom of the absorber vessel 2|, upwardly through the absorber vessel 2| and back to the evaporator through the conduit 41, central parts of the heat exchanger and the conduit 38. This particular arrangement of the gas conduits and the absorber is such that it is possiblev to materially reduce the heat radiating surface of the absorber from that which would otherwise be required of an air cooled unit. The arrangement operates upon a novel principle which will now be described.

The problem of air cooling is one of increasing the capacity of the unit and decreasing the size by improved means of discharging heat to the atmosphere. It has been observed that the installation of an air cooled unit in a cabinet affected the capacity adversely. This is attributed to the restricted air circulation where the cabinet partly surrounds the absorber. Means was discovered for air cooling the absorber indirectly as for example, the arrangement shown in Figure 4 but this only partly solves the problem of air cooling because although it provides effective means for heat discharge, the element so cooled operates at a temperature some 30 to 40 degrees F. above the atmosphere andthis is a condition unfavorable to complete or nearly complete absorption. Accordingly auxiliary means for discharging the heat of absorption is provided in order to permit some absorption at a temperature approximately the same as that of the air.

The hottest point (where the arrangement is such that one part of the absorber is warmer than another) is that at which the gas from the evaporator first contacts with the absorption solution. This point is thus the most desirable location for the indirect cooling system. Next, in order to return the circulating gas mixture to the evaporator with the lowest possible ammonia content, its last contact with the absorption solution should be with the weakest solution available at the lowest possible temperature, i. e. that of the air. This is accomplished-by having a directly air cooled vessel 2| above the indirectly air cooled absorber part 22.

In order for the absorber part 2| to operate at very nearly the temperature of the air the weak absorption liquid entering through the conduit l9 mustbe nearly at air temperature. To assist in attaining this result it is desirable that the concentrated solution leaving the absorber and passing in heat exchange relation with the weak solutio in the jacket ll of the heat exchanger be broug t to as low a temperature as possible before it enters the conduit I 4. If it is nearly air temperature before it enters conduit II, it will reduce the temperture of the liquid in the jacket II more nearly to air temperature. During the time that it is being cooled down asit leaves the main absorber vessel 22, however, it is desirable that further refrigerant be absorbed. It is for this reason that the absorber part 23 is provided.

Accordingly the absorption process consists of the following three distinct steps:

First, the absorption of the greater part of the refrigerant from the inert gas at a relatively high temperature so that the heat may be rapidly dissipated, this being accomplished with relatively weak solution in the vessel 22 where the mixture of the inert and the refrigerant gas first enters the absorber; next, the absorption of more refrigerant at a lower temperature but with a more concentrated solution, this step taking place in the absorber vessel 23; and finally, the absorption of still more refrigerant at the lowest pos-- sible temperature (very nearly air temperature) and with the weakest possible solution, which is just entering the absorber from the boiler and which has been brought to nearly air temperature by the heat transfer in the exchanger l1 and the precooling in the precooler Is, this last step taking place in the absorption vessel 2|. It is to be noted that all of these steps occur while the absorption liquid and inert gas are flowing in opposite directions through the respective parts of the absorber.

The advantages of this arrangement of absorber and conduit will now be apparent. Since the absorber vessel 2| is operating at very nearly air temperature, the efi'ective absorption temperature has been reduced to the ideal limiting case regardless of the temperature prevailing in the main part of the absorber 22 where the greater amount of heat is discharged. Due to the fact that the absorber vessel 22 is at such a high temperature the heat flow from it is much more rapid than; would ordinarily be the case. In other words, by maintaining one part of the absorber relatively warm and the other part relatively cold heat is discharged more rapidly with less heat radiating surface and absorption takes place to a greater degree than would be possible if the whole absorber were at the average temperature of the parts.

Apparently the best results are obtained when the part 22 has a larger liquid-gas contact surface than the parts 2| and 23 and for this reason it may be designated the main part. It is to be understood, however, that the invention is not limited in this respect and in some of the following claims, the words main and auxiliary are used merely for definiteness and are not intended as limitations as to relative sizes.

As stated above, the embodiment of the invention disclosed in Figures 1 to 4 inclusive, is so arranged that the absorber may occupy the space along the rear of the cabinet.

In accordance with a modified "form of the invention it is possible to locate the entire absorber in'the lower part of the cabinet so as to leave most of the upper portion of the cabinet available for use as a food storage compartment. At the same time an absorber construction is provided which has a large radiating surface so that it may be properly air cooled.

One such modification of the invention is shown in Figures and 6. As in the embodiment of Figures 1 to 4, the system of Figures 5 and 6 includes a boiler B, a condenser C, an absorber A, an evaporator E and a gas separating chamber S as essential elements. The boiler, gas separating chamber, condenser and evaporator and the gas heat exchanger and the liquid heat exchanger may be similar to that indicated and described in connection with Figures 1 to 4.

The absorber of Figures 5 and 6 has three parts designated 1 I, 12, and 13respectively. The parts H and 13 are similar and are made up of sections of pipe welded together so as to form a number of reverse bends, the pipes being arranged nearly in a horizontal plane instead of in a vertical one, as in the arrangement of Figures 1 to 4, but with each pipe inclined very slightly downwardly to permit liquid to flow by gravity from one end of the absorber section to the other. The part 12 is merely a vertically disposed cylinder having baffles in the upper portions as indicated in Figure 6. The lower portion of the part [2 acts as a reservoir to take the place of the additional vessels 28 of the arrangement of Figures 1 to 4.

Although not shown in Figures 5 and 6, it is obvious that an indirect cooling system for the absorber section 12 may be provided and may take the form of the arrangement shown in Figures 3 and 4 for example. In this case the condenser for the indirect cooling system may be located just below that of the condenser marked C in Figure 5, there being adequate space at the rear of the cabinet for this purpose.

In Figures 5 and 6 the parts corresponding to those of Figures 1 to 4 are similarly designated so that a description thereof will not be repeated here in detail.

The flow of the inert gas between the boiler and absorber of Figures 5 and 6 difiers from that of Figures 1 to 4 as will now be pointed out. The gas flowing downwardly from the evaporator through the gas heat exchanger 33 flows through the conduit 14 directly to the absorber section 12. After passing upwardly across the baflie plate 15 in the upper portion of the tank 12, the gas flows through the conduit 16 which is in the form of an inverted U. In this conduit the gas is brought into heat exchange relation with the small conduit 11 conveying refrigerant gas from the gasseparating chamber S. This causes the portion of the conduit 11 in proximity with the right hand leg (as viewed in Figure 6) of the conduit 16 to act as a rectifier, while at the same time the gases in the conduit 16 are heated so as to promote the circulation, the gases in the right hand leg of the conduit 16 passing upwardly. It is also to be noted that the conduit 16 passes nearly to the top of the entire refrigerating unit as shown in Figure 5, and provides excellent mechanical means for supporting the condenser or condensers as well as various other parts of the refrigerating unit.

The lower left hand leg of the conduit '16 is' connected with the part 13 of the absorber. The gases flow downwardly through the part 13 the lower end of which is connected by means of a vertical conduit to the upper section II of the absorber. A sump 18 is provided at the lower end of the part II, where the vertical conduit joins this part. The gas flows upwardly through the part II the upper end of which is connected to the gas heat exchanger 33 which conveys the gas back to the evaporator.

In the arrangement of Figures 5 and 6 the absorption solution being lifted upwardly in the conduit 15 from the boiler B flows downwardly through the gas separating chamber S through the conduit IS, the heat exchanger l1 and the conduit l8 to the top of the absorber section ll. After trickling downwardly through the section II, the absorption solution is conveyed by means of conduit 19 from the sump 18 into the top of the cylinder 12. It'trickles downwardly over the baffles 15 and is conveyed by a second U- shaped conduit 80 into the top conduit of the absorber section 1'3. A conduit 8| provides means for conveying the absorption solution out of the lower piece of pipe of the section 13 back into the part 12, the lower portion of which acts as a reservoir. From this point, the absorption liquid flows back to the boiler through the conduit l4.

The refrigerant vapor expelled in the boiler B passes upwardly through the conduit l5 into the gas separating chamber S, thence upwardly through the conduit 11 where the absorption solution, absorption liquid vapor is rectified and into' the condenser C. After condensing there the refrigerant flows into the vent chamber 32 and then through the U-shaped conduit 35 into the evaporator. As will be readily understood by those skilled in the art, the refrigerant evaporates in the evaporator and is conveyed from there tothe absorber by the inert gas and from the absorber back into the boiler by the absorption liquid.

It is to be noted that in the arrangement of Figures 5 and 6 no jet is employedfor circulating the inert gas. Gravity-is relied upon for circulation of the gas under the influence of the changes in density resulting from the addition or removal of refrigerant gas to the inert gas and to the heating and cooling efiect on various conduits.

Figures '7 and 8 disclose an arrangement simil-ar to that of Figures 5 and 6 except for the particular construction of the absorber and the related conduits. Inasmuch as the general features-of assembly are the same as that of Figures 5, 6, the diagram of Figure 8 is limited to the details of the inert gas circuit. The parts corresponding to those of Figures 5 and 6 are similarly designated.

It will be seen from inspecting the drawings that the inert gas leaves the lower portion of the gas heat exchanger 33 and flows through the conduit 14 into the top of the tank 12 whereas in Figure 5 it flows into the central portion thereof. As shown in Figure 8 the gas then flows downwardly over the bafiie plates 15 whereas in Figure 6 it flowed upwardly across the corresponding bafiles. The central portion of the tank '15 is connected with the lower section 13 of the absorber which is in turn connected to the right hand leg (so viewed in the drawings) of the inverted U-shaped conduit 16. The left hand leg of the inverted U-shaped conduit 16 is connected to the lower portion of the upper section H of the absorber, the upper end of which is, in turn, connected to the gas heat exchanger 33.

Absorption liquid is supplied to the upper sec tion H by means of conduit i8 and after flowing downwardly through the section ll passes by means of a U-conduit 19 into the upper part of the absorber section 12 and after trickling downwardly over the baffle 15 therein is caught by the lower baflle and conveyed into the lower section '13 of the absorber. From the lower end of the section 13 absorption liquid passes by means of the conduit 8| back into the lower reservoir portion of the section 12.

It will thus be seen that whereas in the arrangement of Figures 5 and 6 the gases pass in counterflow with the absorption liquid in the sections 'II and 12, and in parallel flow in the section 13, in the arrangement of Figures 7 and 8, the gases and liquids pass in parallel flow in the sections 12 and I3 and in counter-flow in the section H. It will thus be seen that in each of these cases the flow is different from that of Figures 1 to 4 in which the gases of liquid flow through each section of the absorber in counter flow. It is, of course, possible to provide further modifications of the invention in which parallel flow is used in one section and counter fiow in the others, or in which parallel fiow is used in all the sections without departing from the spirit-of the invention.

While certain advantages result in certain circumstances from the particular flow in the individual section the importance of the invention does not reside in this so much as in the arrangement of flows through the absorber as a whole. It is well known that where parallel flow is employed in the entire absorber a disadvantage results from the fact that weak absorption liquid does not meet and strip the inert gas leaving the absorber of the maximum amount of refrigerant. Where counter flow is used through the entire absorber, on the other hand, a disadvantage results from the fact that a high temperature is generated at the point where the liquid leaves the absorber so that the liquid can not reach the maximum concentration. In accordance with the present invention both of these disadvantages are overcome in all of the forms illustrated. The

weakest absorption liquid meets the inert gas weakest in refrigerant gas at a point where the temperature is maintained low so that the inert gas passing back to the evaporator is as free from refrigerant gas as it is possible to make it. Like wise the absorption liquid leaving the absorber may be brought to its maximum concentration because it is brought to a low temperature in the lower section of the absorber and again subjected to the refrigerant gas after it has absorbed a large portion of the refrigerant at the higher temperature in the central part of the absorber.

It will be seen that while only a few embodiments of the invention are disclosed van'ous others might be devised without departing fromthe spirit of the invention. The indirect cooling system illustrated in Figures 3 and 4 may be advantageously used for cooling the section I2 of the absorbers of Figures 5 and 6, or 7 and 8, or other indirect cooling systems may be employed for this purpose. Various other changes may be made without departing from the spirit of the invention or the scope of the annexed claims.

I claim:

1. In an absorption refrigerating system, an absorber, means for supplying refrigerant vapor to said absorber and means for circulating absorption liquid through said absorber, said absorber having a main part having a small heat radiating area and provided with an extensive surface for retaining absorption liquid in exposed relation to the refrigerant vapor, an auxiliary part having additionalliquidretaining surface and a large heat radiating area and means for conveying absorption liquid and a portion of the refrigerant vapor from said main part to said auxiliary part, the ratio of surfaces and the ratio of areas causing more refrigerant to be absorbed in said main part than in said auxiliary part and more heat generated therein whereby the main part operates at a relatively high temperature to discharge heat rapidly and the auxiliary part operates at a relatively low temperature and reduces the vapor pressure of the refrigerant further than that possible at the high temperature prevailing in the main part.

2. An absorber for use in a refrigerating system comprising a main part, a first auxiliary part and a second auxiliary part, the main part having means for providing a greater surface of contact between gas and liquid therein than the surface of contact in said auxiliary parts, means for causing refrigerant vapor to flow to the main part, then to the second auxiliary part and then to the first auxiliary part and means for causing absorption liquid to flow to the first auxiliary part,

then to the main part and then to the second auxiliary part.

3. In a refrigerating system, an absorber comprising a plurality of parts, each part having means providing for surface contact between a gas and a liquid to enable the liquid to absorb the gas,'heat discharge means for cooling the parts so arranged as to cause one part to operate at a relatively high temperature to cause a rapid heat discharge per unit of area of heat discharge surface and another part to operate at a relatively low temperature to permit absorption of refrigerant which is not absorbed at the higher temperature prevailing in the first mentioned part and means for conducting gas and liquid from said first mentioned part to said second mentioned part.

4. The method of absorbing refrigerant in an absorption liquid which consists in first passing the refrigerant into contact with a relatively large surface of the liquid to thereby cause the greater portion of the absorption to occur at a relatively high temperature, accompanied by the generation of a relatively large quantity of heat, then lowering the temperature of the liquid which has absorbed the refrigerant and again passing the refrigerant into contact therewith to cause additional absorption and finally passing the remainder of the refrigerant into contact with weak absorption liquid at a relatively low temperature to cause still additional absorption.

5. The method of absorbing refrigerant in an absorption liquid by bringing the refrigerant and the liquid into contact with each other, which consists in passing the refrigerant through a main vessel, then through one auxiliary vessel and then through another auxiliary vessel while passing the liquid through the last mentioned auxiliary vessel, then through the main vessel and then through the other auxiliary vessel.

6. In a refrigerating system, an absorber having three parts, means for causing refrigerant to flow through the first part, then the second part and then the third part, means for causing absorption liquid to fiow through the third part, then through the first part and then through the second part, means for directly air cooling the second and third parts and means for indirectly air cooling the first part.

'7. In an absorption refrigerating system, an absorber, means for supplying refrigerant vapor to said absorber and means for circulating absorption liquid through said absorber, said absorber having a plurality of parts having different areas of heat radiating surfaces so as to cause the parts to operate at different temperatures whereby one part may operate at a relatively high temperature to discharge a large amount of heat per unit of area of its heat radiating surface and another part may operate at a relatively low temperature to absorb refrigerant which is not absorbed at the higher temperature prevailing in said first mentioned part, the arrangement being such that absorption liquid and gas to be absorbed flow from said first mentioned part to said second mentioned part.

8. In an absorption refrigerating system, an absorber having a plurality of parts arranged in close proximity, one above the other, means for supplying refrigerant vapor to said absorber, means for circulating absorption liquid through said absorber, means for causing one part of said absorber to operate at a different temperature than another part, means for transferring absorption liquid and refrigerant vapor from said one part to said other part whereby the part operating at the higher temperature may discharge heat rapidly and the part operating at the lower temperature may absorb refrigerant which is not absorbed at the higher temperature prevailing in said first mentioned part and means for preventing the heat discharged from one part from materially affecting the operation of another part of the absorber.

9. An absorber for an absorption refrigerating system using an inert gas, said absorber having at least three parts, means for circulating an absorption liquid in series through said parts in a definite sequence, means for circulating said inert gas and a refrigerant gas in series through said parts in a definite sequence, the gases flowing first to the part which is second in said liquid flow sequence.

10. An absorber for an absorption refrigerating system using an inert gas, said absorber having at least three parts, means for circulating an absorption liquid in series through said parts in a definite sequence, means for circulating said inert gas and a refrigerant gas through said parts in a definite sequence, the gases flowing first to a part intermediate in the liquid flow sequence.

11. In a continuous absorption refrigeration process, the method of absorbing a refrigerant gas in an absorption solution which includes the steps of causing the absorption solution to flow through a series of absorption stages bringing the gas into contact with the solution at a point where the solution has a medium concentration, withdrawing the gas from contact with the solution bringing thegas into contact with the solution at a point-where the solution has a high concentration 'withdrawing the gas from contact with the solution and bringing the gas in contact with the solution at a point where the solution is at a low concentration.

12. In an absorption refrigerating system, an absorber, means for supplying refrigerant vapor to said absorber and means for circulating absorption liquid through said absorber, said absorber.

having a main part provided with a relatively small heat radiating surface, an auxiliary part provided with an extensive heat radiating surface and means for conveying absorption liquid and a portion of the refrigerant vapor from said main part to said auxiliary part, the ratio of said surfaces causing more refrigerant to be absorbed in said main part than in said auxiliary part and causing more heat to be generated in said main part than in said auxiliary part whereby the main part operates at relatively high temperature to discharge heat rapidly and the auxiliary part operates at a relatively low temperature and reduces the vapor pressure of the refrigerant further than that possible at thehigh temperature prevailing in the main part.

13. An absorber for use in a refrigerating system comprising a main part, a first auxiliary part and a second auxiliary part, the main part having a relatively small heat radiating surface, and the auxiliary parts each having relatively large heat radating surfaces, means for causing refrigerant vapor to fiow to the main part, then to the second auxiliary part and then to the first auxiliary part and means for causing absorption liquid to flow to the first auxiliary part, then to the main part and then to the second auxiliary part, whereby the heat of absorption is dissipated rapidly and the absorption liquid is caused to absorb a, large amount of refrigerant vapor.

14. An absorber for use in a refrigerating system comprising a main part, a first auxiliary part and a second auxiliary part, the main part having a relatively small heat-radiating surface and having means for providing a relatively'large surface of contact between gas and liquid therein, and the auxiliary parts each having a relatively large heat radiating surface and each having means for providing a relatively small surface of contact between gas and liquid therein, means for causing refrigerant vapor to flow to the main part, then to the second auxiliary part and then to the first auxiliary part and means for causing absorption liquid to flow to the first auxiliary part, then to the main part and then to the second auxiliary part, whereby the heat of absorption is dissipated rapidly and the absorption liquid is caused to absorb a large amount of refrigerant vapor.

15. An absorber for use in a refrigerating system comprising a main part, a first auxiliary part and a second auxiliary part, said parts being so constructed and arranged as to cause said main part to operate at a higher temperature than said auxiliary parts, means for indirectly air cooling said, main part, and means for directly air cooling said auxiliary parts.

16. An absorber for use in a refrigerating system comprising a main part, a first auxiliary part and a second auxiliary part, said parts being so constructed and arranged as to cause said main part to operate at a higher temperature than said auxiliary parts, means for air cooling said auxiliary parts and means for conveying heat away from said main part to a point where it will not appreciably affect the discharge of heat from said auxiliary parts.

RUDOLPH S. NELSON.

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