US2368374A - Refrigeration - Google Patents

Description

- Jan. 30, 1945. R. s. NELSON REFRIGERATION Filed March 22, 1939 8 Sheets-Sheet l Rudolph 6. Nelson I ATTORNEY Jan.30, 1945. 'R. s. NELSON 2,368,374

REFRIGERATION I Filed March 22, 1939 a Sheets-Sheet 2 4o 22 C Zl INVENTOR Rudolph s. JVelson MWSM ATTORNEY Jan. 30, 1945. R, s, NELSCQN 2,368,374

' REFRIGERATION Filed March 22, 1939 8 Sheets-Sheet 3 INVENTOR ATTORNEY Q Rudolph Nelson Jan. 30, 1945.

R. s. NELSON REFRIGERATION Filed March 22, 1939 8 Sheets-Sheet 4 '65 as"! C I 74 88 AL a4 65 I 8a INVENTOR ATTORNEY Jan. 30, 1945. R NELSON 2,368,374 I REFRIGERATION Filed Maxch 22, 1939 8 Sheets-Sheet 5 INVENTOR Rudolph 6. Ne lson ATTORNEY 1 R. S. NELSON Jan. 30, 1945.

REFRIGERATION Filed March 22, 19:59

8 Sheets-Sheet 6 lNVENTO R 6. jVelson ATTORNEY R. S. NELSON REFRIGERATION Jan. 30, 1945.

Filed March 22, 1933 8 Sheds-Sheet 7 Illllll lllllllj- I I l l l l II II [III I I] llllll llllll INVENTOR I 1 II It llIlll llllll I II lllllll Hill ATTORNEjY Jan. 30, 1945. R. s. NELSON 2,368,374

REFRIGERATION Filed March 22, 1939 8 SheetS Sheet 8 IOO' INVENTOR ATTORN EY Patented Jan. 30, 1945 REFRIGERATION Rudolph S. Nelson, Larchinont, N. Y., assignor'to The Hoover Company, North Canton, Ohio Application March 22, 1939, Serial No. 63,527

21 Claims. This invention relates to absorption refrigerating apparatus, and more particularly, to an ap-' paratus of the kind employing inert gas and in which the absorber as well as the condenser is constructed and arranged to be cooled directly by the surrounding air. The present application is a continuation-in-part of my abandoned copending application Serial #685,037, filed August 14, 1933, entitled Continuous absorption refrigerating apparatus.

Previous attempt to develop large capacity air-cooled absorption refrigeration apparatus operated solely by heat and utilizing an inert pressure equalizing medium have not been entlrely successful. The outstanding reason for this was the difliculty encountered in obtaining adequate circulation of the pressure equalizing medium through its circuit. Another very troublesome problem was the design and arrangement of the absorber within a cabinet .of a. household refrigerator in such a way as to obtain ade- For example, when using the surrounding air as the cooling medium it is necessary to provide a construction which will maintain a desired capacity and a maximum efliciency over a range of cooling air temperature varying between 60 and 130 F.

It is accordingly an object of the present invention to provide a three-fluid continuous refrigeration apparatus having an air cooled condenser and an air cooled absorber which is so constructed and arranged that an adequate circulation of the inert gas is always obtained, and such that the heat of absorption and the heat of condensation is dissipated to the surrounding air without curtailing capacity and regardless of the temperature of the available cooling air.

A further object is to so position the parts of the apparatus with respect to one another that the same may be constructed as a. unit, charged and tested, and then inserted directly into a refrigerator cabinet with the heat absorbing portion extending into the food storage compartment, and with a part of theheat dissipating portions of the apparatus underlying the storage compartment, and at least a portion of the remainder overlying this compartment.

Another object of the invention is to arrange the various major portions of the apparatus in superimposed planes in order to reduce the horizontal cross-sectional area of a refrigerator cabinet at the expense of the vertical height in order to increase the vertical length of the cooling air flue so as to obtain a maximum flow of cooling air.

Another object of the invention is to make the condenser and the absorber into a sinuous conduit, the various legs 'or branches of which are located in substantiallythe same plane, and then to so position such absorber or condenser element in the apparatus compartment of the refrigerator cabinet as to obtain the most compact assembly and at the same time to obtain a most efficient and maximumfiow of cooling air thereover.

Still another very important object of the invention is to provide means for increasing the flow of the inert gas through the absorber and evaporator notwithstanding the increased length of this circuit necessitated by the construction adopted in certain modifications of my invention. More specifically, it is an object to obtain an increased flow without introducing any moving parts within the system. Moreover, due to my novel arrangement of certain elements, I am enabled to obtain an increase in the flow of inert gas by making use of heat which was previously 25 a total loss, and while increasing the efliciency of the system in other respects, as will become apparent from the detailed description to follow.

Another object of the invention is to promote the circulation of the inert gas between the absorber and evaporator in two ways, both of which were unknown prior to my invention, and the efiect of each of which is additive to the efi'ect heretofore relied upon to circulate the inert gas. More specifically, it is an object of the invention to promote the circulation of the inert gas by adding heat to an ascending column thereof; and secondly, to cool another descending column thereoi to the same or greater extent than the ascending column is heated. The heating of the ascending column is preferably accomplished by transferring the heat of rectification thereto, while the cooling of the descending column may be obtained by passing the gas in heat exchange 1 5 of inert gas.

A still further object of the .invention i to so construct and 'locate both the absorber and the condenser in the path of the cooling air that a given portion of the air stream passes over each of the heat dissipating elements but a single time. Furthermore, these elements are so arranged that approximately the same amount of cooling air flows over all, portions of the same, and so that air at substantially the same temperature initially comes into contact with certain portions of these elements.

Still another important feature of the present invention is the provision of a multiple stage absorber such that the normal operating temperatures of the first and last stages is not much higher than the cooling air temperature passing thereover, while the temperature of the intermediate stage or stages is much higher. According to the present invention, this result is accomplished in part by cooling the inert gas out of contact with the absorption liquid as it passes from certain stages to others. By the first and last stages it will be understood that I mean those stages in which the inert gas first and last contacts the solution.

More particularly, it is an object of the invention to operate the first and last stages of the absorber at lower temperatures than an intermediate stage in order to obtain more efficient absorption. The temperature differential between the absorber stages is obtained in part by cooling the inert gas and refrigerant mixture out of contact with the absorption liquid as it is conducted from one stage to another stage.

Another object is to provide a system having a I very great capacity without employing large sized component element which are inherently inemcient. More particularly, it is an object to provide a system in which certain elements are employed in duplicate to avoid the losses incident to the use of large sized elements. ,It will thus be apparent that I am able to keep the weight and cost of the materials down to a minimum because the thickness of the tubing walls necessary to withstand the system pressures increases rapidlyprovided with heat radiating fins to increase the area of that portion of the apparatus without unduly increasing the length and the weight of the conduits.

A further object of the invention is the provision of a novel gas heat exchanger so conitructed as to serve as a part of the absorber, and as a solution reservoir. This reservoir functions not only to store the excess solution which should be present in other than the boiler or absorber of thesystem for efficient operation, but also to maintain a proper solution level in the boiler assembly. Moreover, the heat exchanger is so constructed that residue, unevaporated liquid from the evaporator is returned to the boiler assembly therethrough thus eliminating an independent drain connection as heretofore.

Another object is to improve the rectifier and to provide a construction whereby the heat of rectification is utilized for a useful purpose.

' tain novel features of the arrangement and construction of parts as will become apparent hereinafter from a consideration of the following detailed description taken in connection with the accompanying drawings in which:

Figure 1 is a rear elevational View with portions broken away for clarity and showing a large capacity refrigerator according to this invention.

Figure 2 is a side elevational view of'Figure l with the near side wall broken away to show the arrangement of the parts with respect to the cabinet and food compartment.

Figure 3 is a schematic representation of the apparatus shown in Figures 1 and 2.

Figure 4 is a side elevational viewpartly in section showing a second embodiment of the invention.

Figure 5 is a schematic representation of the apparatus shown in Figure 4.

Figure 6 is a side elevational view partly in section of a third embodiment of the invention.

Figure 7 is a schematic representation of the apparatus shown in Figure 6.

Figure 8 is a fragmentary elevational view on line 88 of Figure 6 showing in greater detail .how the various branches and the fins thereon are angularly related.

of a slightly modified embodiment of the form shown in Figs. 6 and 7.

Referring now to the embodiment shown in Figures 1 to 3, it will be observed that a refrigerator cabinet I is shown having an insulated food compartment ll closed at its front by a door l2. The sides of the food compartment extend downwardly as at 13 to enclose a refrigeration apparatus compartment and air fiue ll. of the cabinet also extend rearwardly to form a vertical air fllue I5. extending for the full width and full height of the cabinet. This air flue is preferably closed at its back by-a panel I 6 for utilitarian and appearance purposes. A removable panel or door 11 serve to close the front of the apparatus compartment. The cabinet is supported on a pedestal l8 having an air opening IS in its top, and cutaway portions at its side as shown to admit cooling air to compartment I 4.

The side walls of the cabinet also extend slightly above the food compartment, and are perforated as at 20 to admit additional cooling air to this compartment. The front, top portion of this compartment may be closed by an imperforate panel 2 I, while the rearmost portion is covered by a perforated panel 22 through which all the cooling air discharges back into the room.

In order that the drawings may not be unduly multiplied, it will be understood that the vertical air flue l5 has been shown to be considerably deeper than it would be made in practice, and certain of the conduits would be brought more nearly into a common plane.

Passing now to the schematic representation in Figure-3, the construction and mode of operation of my novel system will be described after which I will proceed to a description of the manner in which this apparatus is disposed within the cabinet.

As is suggested by a cursory inspection of Fi ure 3, a preferred arrangement of my system includes two duplicate systems joined by a common evaporator and gas heat exchanger. Thus Still other objects and advantages reside in certhere are two boiler assemblies, two absorber assemblies, and two condensers. The corresponding duplicate elements will be referred to The side walls principal elements, and an inert gas tween the absorber andthe evaporator.

- changer is provided with a central conduit 3| aseasvs v hereinafter by the same characters difiering only in the use of a prime on certain thereof.

Referring now to the lefthandhalf of Figure 3.

assembly A, gasheat exchanger H, and evaporator E. These vessels are connected in circuit by suitable conduits to provide a hermetically sealed system having an absorption circuit between the boiler assembly and the absorber assembly, a re-. frigerant circuit, including all of the aforesaid circuit be- The system may be charged with any suitab fluids as for example ammonia as a refrigerant, water as the absorption solution, and hydrogen as the inert gas.

The boiler assembly includes a main refrigerant distillation chamber 23 which may have a combustion chamber positioned centrally thereof and adapted tobe heated by a gas burner or other suitable source of heat. This chamberis provided with a vapor lift pump 24 of known form which extegnds upwardly above the chamber and discharges nto the gas separation chamber S. When heat is applied to the boiler, refrigerant vapor is liberated which collects at the base of the pump and serves to elevate absorp tion liquid from which refrigerant vapor has 7 been distilled therethrough. The liquid so elethree stages which are designated by the numerals 33, 34 and 85. Each stage is preferably constructed from tubular elements suitably secured together as by welding, and is provided with heat radiating fins extending in agenerallyvertical direction when positioned within the refrigerator cabinet. As will be noted from Figures 1 and 2, the branches of each absorber stage are located substantially parallel to one another and in the same plane. Each absorberstage is also preferably inclined slightly to the horizontal sufiiciently to allow the absorption solution to new downwardly therethrough by gravity,- and to this vated flows downwardly into the gas separation chamber while the refrigerant vapor passes directly into conduit 25, which leads into the uppermost end Bf condenser C. p t

The condenser comprises a series of conduits which are. provided with heat dissipating fins to facilitate the cooling of the same. As a result of this cooling action, the vapor' liquefies and flows by gravity through conduit 26 into the top of evaporator vessel E.

The evaporator may be made in any desired manner, but as herein illustrated, comprises a large diameter, tubular vessel 21 closed at its upper and lower ends, and provided interiorly with a series of staggered substantially horizontally positioned baftle members 28, and a central vertical partition 29. The liquid refrigerant. discharges onto the uppermost plate and gradually trickles from one plate to another while evaporating into the inert gas with which the vessel is filled, thus producing refrigeration.

The resultant mixture of inert gas and refrigerant vapor is led from the evaporator into the gas heat exchanger H through conduit 30. The heat exchanger preferably extends from the general level of the evaporator to a point intermediate the top and bottom of apparatus compartment M. The upper portion of the heat exof heat conducting material through which the vapor and inert gas mixture is conducted into the lower portion of the exchanger. The, outer shell of the exchanger is extended downwardly to a point adjacent the level of the boiler assembly. The lowermost portion serves as a solution reservoir 32, and also as a part of the absorber, as will be more fully explained presently. The reservoir is connected to the heat exchanger proper byconduit 32a which conducts the lean as from conduit 3| over the solution in reservoir 32 and into the first stages 33 and 33' ofthe absorbers.v Conduit 32a further serves to conduct residue liquid from the evaporator and the heat exchanger to the solution reservoir.

end, each branch of each stage may be individually inclined slightly downwardly.

Several stages of the absorber are connected in series so that the inert gas fiows first-through section 33, then through intermediate stage 34, and finally through stage 35.. Thus the inert gas laden with ammonia vapor passes from heat exchanger H through conduit 36 to the first absorber stage 33. The gas from which somerefrigerant vapor has been removed then passes through conduit 31 into intermediate stage 33 of the absorber. Conduit 31 may be provided with heat radiating fins to cool the gas mixture before it enters the intermediate stage.

The major portion of the refrigerant vapor is absorbed from the inert gas as it passes through the intermediate stage, and this stage may accordingly be made larger than the first and last stages. As a result of the large amount of absoxption taking lace in this stage, the same becomes so warm from the heat of absorption that complete absorption of the vapor cannot take place. his therefore desirable to cool the inert gas before the same enters the last stage in order that the remaining portion of the refrigerant vapor may be stripped from the inert gas.

To accomplish this expeditiously, I prefer to conduct the heated inert gas through an inverted U- shaped conduit 38, the opposite ends of which are connected to thedischarge end of stage 34 and the inlet end of stage 35. The inlet leg 39 may extend upwardly along one side portion of; air flue l5. At the top of the air fiue a horizontal order that the heat of condensation of the water vapor may be utilized for a useful purpose, I prefer to pass a portion 26 of vapor conduit 25 through a rising part of conduit 39 forming a part of the inert gas circuit. Inasmuch as the inert gas, though warm, is considerably cooler than the water vapor within conduit 26, the water vapor is cooled below the condensation temperature, and the inert gas is heated. The condensed water vapor flows back into the gas separation chamber S leaving substantially pure refrigerant vapor flowing to the condenser.

The heat of rectification serves to heat the inert gas considerably and thus causes the same to expand and rise rapidly in conduit 39. Since conduits 40 and 4! are positioned directly in the path of the cooling air in flue l5, and these con- As illustrated, absorber assembly A comprises duits are preferably provided with heat radiating fins, the heat of rectification, as well as the heat of absorption present in the inert gas, is dissipated to the atmosphere. Consequently the temperature of the gas as it enters stage 35 is slight above that of the cooling air.

Moreover, due to the increased specific gravity of the gas in conduit 4!, the gas tends to fall much faster than it would if it had not been cooled. By virtue of the use of inverted U-conduit 38, it is apparent that the inert gas flow is ,assisted to a considerable degree by the heating of the gas in a rising portion of the gas circuit and cooled in a descending portion. And of course this heating and cooling is in addition to the heating and cooling of different portions of the circuit elsewhere in the system heretofore relied upon to assist the circulation.

The very cool inert gas carrying a small amount of refrigerant vapor then flows through the last stage 35 in contact with the leanest absorption solution and in counterflow thereto, as will be explained presently. The substantially pure inert gas thus obtained then flows through conduit 42 into passage 43 of the gas heat exchanger. As the lean inert gas passes upwardly, it is cooled by the cold inert gas flowing downwardly through conduit 3|, after which the lean gas passes back into the bottom of evaporator E through conduit 44.

The lean absorption solution flows from gas.

separation chamber S through conduit 45 and into the top of absorber stage 35. This lean solution flows through stage 35 by gravity, and then into intermediate stage 34 through conduit 46, and finally through conduit 41 into the top of the last stage 33. After traversing stage 33 the solution flows to reservoir 32 through conduit 48. Conduit 49 leads the enriched solution back to the boiler and includes a solution heat exchanger 50 intermediate its ends. The lean solution conduit 45 also is connected to this heat exchanger, as illustrated.

It will now be understood that the rich inert gas first contacts absorption solution in the reservoir at the bottom of the gas heat exchanger.

In spite of the fact that the heat exchanger contains rich solution, a considerable amount of additional refrigerant is absorbed because the refrigerant vapor carried by the inert gas and flow-v idue liquid overlying from the evaporator to passthrough chamber 43 and to flow into reservoir 32 but prevents the passage of inert gas between the two passageways of the heat exchanger. By virtue of this construction, residue liquid not evaporated in the evaporator overflows through conduit 44, passes through chamber 43 of the heat exchanger, through gooseneck 5|, into the reservoir 32, and finally back to the boiler. This return of residue liquid is accomplished without employing an additional drain conduit and without affecting the operation of the absorber or other portions of the apparatus.

Since the righthand portion of the apparatus is identical in construction and functions with the corresponding portion of the apparatus shown on the left hand side of Figure 3, this part of is divided and part flows into the bottom stage of absorber A. After all of the refrigerant vapor has been absorbed, the resultant lean gas returns to the gas heat exchanger where it is mixed with the inert gas from the absorber in the other half of the apparatus and is conveyed back to the inlet of the evaporator.

Thus. it will be appreciated'that there are two parallel absorption solution circuits, two parallel refrigerant circuits, and two parallel inert gas circuits, and that each of these parallel circuits overlap with the other in part Passing now to a more careful consideration of Figures 1 and 2, it will be noted that the apparatus, when viewed from the side, has the general appearance of the letter E. The top leg of the E comprises the condensers C and C. The lower leg consists primarily of the several absorber stages, while the central portion of the letter is represented by the evaporator and the attached ice tray housing-5 l The condensers are L-shaped with one leg ex.- tending vertically downwardly into the rear air flue, while the other leg extends substantially horizontally above the food compartment. Each condenser consists of a plurality of horizontally positioned conduits .52 provided with heat radiating fins 53 extending transversely thereof. The

tubes are connected together at their ends by headers 54. The vertical leg of the condenser is cooled primarily by the air flowing through the air flue I 5, while the horizontal leg is cooled principally by air entering through perforations 20 which passes over the condenser legs and out through grille 22. Although the condensers have been shown as superimposed, it will be understood that each condenser could be arranged to extend only half way across the cabinet so that the one condenser might be placed on one side of the flue and the other on the opposite side.

It will be observed from Figure 1 that descend-.

ing legs 4| and 4i of the inert gas circuit are provided with inclined heat radiating fins 55 and 55'. Figure 2 also shows that the horizontal portions 40 and4ll' of this circuit are also provided with fins 56 and 56 respectively.

Figure 2 depicts the arrangement of the several stages of the absorber in the apparatus compartment and the manner in which the alternate stages are staggered with respect to one another to permit of a more compact arrangement as well as to reduce the resistance to the flow of cooling air. Each stage is made up of a sinuou conduit,

all branches of which are located in the same plane which is inclined to the horizontal only sufficiently to prevent .the absorption liquid from collecting in any substantial amount and in order to prevent the conduit from becoming locked due to a slightly unlevel setting of the refrigerator.

Each branch is provided with a large number of In operation the higher temperature of the heat thereof to the other.

. 2,868,374 ments. This air flows upwardly over all portions of theabsorber and upwardly through the air flue l and over the conduit therein, and finally over the condensers at the top of the flue. As will be noted from Figure 1, the boiler and solution heat exchangers are positioned to one side of the cabinet so as not to interfere with the air flow, and it will b understood that these elements are suitably encased in insulating material (not shown for purposes of clarity) to prevent loss of heat therefrom. This insulation casing includes the vapor lift pump and the gas separator, and may include vertical legs 39 and 39' of the inert gas circuit, or at least that portion thereof in which the rectifiers are housed.

Figures 4 and 5 show a simplified manner of constructing an absorption refrigeration apparatus in accordance with the broad principles of my invention. This system is best adapted for use in refrigerators of medium capacity, and differs primarily from the form shown in Figures 1 to 3 in having no duplicate principal vessels, and in employing a simplified two-stage absorber.

The refrigerator cabinet is substantially identical with that shown in Figure 1, and comprises an insulated food compartment 60 having a door 8l. This compartment is supported sufilciently above the notched base 62 to provide a combined air fine and apparatus compartment 63 which communicates at its rear with a vertical air flue 64 extending for the, full height of the cabinet. This latter flue also communicates with a third fine 65 located above the food compartment'and having air inlet openings 66 in its sides and air discharge openings 61 in its top. A panel 68 is removably secured to the back of the vertical air flue. a

The refrigeration apparatus proper comprises a boiler B, a gas separation chamber S, a condenser C, an evaporator E, a ga heat exchanger H, and a. two-stage absorber A. The boiler assembly, including a vapor lift pump 69 and gas separation chamber S, is identical with that shown in Figure 1, and will not be described in detail. A tube 10 passes centrally through the boiler and provides a combustion chamber for gas ,burner 1| positioned at the front end thereof. A

combustion gas flue 12 extend from the opposite end of the chamber and discharges the gases into air flue 64 adjacent the top thereof.

The refrigerant vapors generated in the boiler pass from the gas separation chamber through conduit '13 which leads into the top of the condenser. A co'nsiderable portion of conduit 13 is located interiorly of a part of the inert gas circuit to assist the circulation of the inert gas and to rectify the absorption solution vapors present in the refrigerant vapor.

Condenser C consists of a plurality of conduits secured together at their opposite ends to form a continuous fluid passageway from one end Each of the branches is parallel to the others, and all are located in substantially the same plane. Each branch is provided with fins 14. The condenser as a whole is located directly above the food compartment, and is inclined so that the inlet end is at a higher elevation than the discharge end. It will also be noted that this arrangement of the condenser serves to distribute the air rising through the air flue equitably over all portions of the condenser as it passes upwardly therethrough. Additional cooling air enters through openings 66 by reason of the convection currents set up by the condenser, as will be readily understood. A

conduit 15 conducts the condensate from the condenser to the box cooling col-l I6 of evaporator E.

By reason of the location of the-condenser above the food compartment, I am enabled to position the evaporator at the uppermost part of the food compartment and to supply liquid refrlgerant to the top thereof by gravity. Moreover, this arrangement permits the use of a condenser ofadequate size to condensate the refrigerant vapor at high room temperatures without obstructing the upper end of the vertical air flue and without lowering the evaporator.

The evaporator is preferably formed of tubing bent into an appropriate shape to cool a sharp freezing chamber formed by a casing 11 enclosing all ortions of the evaporator coil except the uppermost conduit 16. The casing completely surrounds portion 18 of the evaporator coil and air cooled absorber A in a closed inert gas circuit.

This circuit will be best understood by reference to Figure 5, and will be described by following the flow of the inert gas as it leaves the box cooling conduit 16 of the evaporator. Gas flows from the evaporator through conduit into the inner passage 8! of the gas heat exchanger H. From the bottom of the heat exchanger the inert gas enters the top of absorber A through conduit 82. The absorber comprises two sections or stages 83 and 84 which are similar in construction and arrangement.

. After the inert gas has passed downwardly through stage 83, it flows through the inverted U-shapedconduit 85 which extends up through the rear air flue and includes legs 86, 81, and a horizontal connecting conduit 88. The inert gas flows upwardly through leg 86, through conduit 88, and downwardly through leg 81 into the lowermost portion of section 84 of the absorber.

; After passing upwardly through this absorber section, the gas flows into the outer passage 89 of the gas heat exchanger through conduit 9|}, and back into the bottom of the evaporator through conduit 9|, thereby completing its circuit.

Each stage of the'absorber consists of a plurality of straight conduit sections 92 connected at their ends to provide a continuous fluid passageway provided on the exterior thereof with heat radiating fins 93. Each branch of the absorber is not only generally parallel to the others, but is preferably inclined slightly to the horizontal to provide a continuous downward path of flow for the absorption solution. From Figure 4 it will be seen that all branches are located in substantially the same plane, and that the entire absorber vessel is inclined slightly to the horizontal. At least a, portion of stage 83 is located directly in the vertical air flue while the remainder of I the absorber is positioned sufllciently below the bottom of the food compartment to permit a free flow of cooling air upwardly through all portions of the absorber and then laterally to the vertical air flue without again striking any part of the absorber.

Referring now to the absorption solution circuit, it willbe understood that the weak solution, after being elevated through pump 69 into the gas separation chamber, flows therefrom through conduit 92 into the solution heat exchanger 93,

part of absorber stage 83. The weak solution then flows downwardly by gravity in parallel with the inert gas, and through liquid seal .conduit 95 into the top of absorber stage 84. The

partially enriched absorption solution flows in counterflow to the inert gas through this stage. By the time the solution has reached the bottom of this stage, it has become saturated with refrigerant vapor, and returns to the boiler through conduit 94, solution reservoir 91, conduit 98, solution heat exchanger 93 and conduit 99.

From the foregoing it will be apparent that this embodiment functions in substantially the same manner as the preferred construction with the exception that there are no parallel fluid circuits in the same sense as in the preferred form, and the construction and mode of operation of the multi-stage absorber is somewhat difierent. It will be manifest however, that the rich inert gas and absorption solution flow in parallel in absorber stage 83 after which the warm gas is led upwardly through inverted U-shaped conduit 85 for identically the same reasons as have been explained in detail hereinabove in connection with Figures 1 to 3. The cooled inert gas then flows in counterflow with the absorption liquid through the last absorber stage 84 where-the remaining refrigerant is stripped from the inert gas.

A still more simplified embodiment of the invention is shown in Figures 6 and '7. Thi form has been found quite adequate for refrigerators of smaller capacity although it will be understood that this form is not limited to such small caacity, but rather that it has been found more efficient in the smaller sizes.

This embodiment is similar to that shown in Figures 4 and 5 but differs therefrom primarily in the use of a single stage air-cooled absorber in which there is no interstage cooling of the inrt gas out of contact with the absorption liquid. Thus, the inverted U-shaped conduit is eliminated together with its two principal functions of facilitating the circulation of the inert gas, and of rectifying the refrigerant vapors flowing to the condenser. In machines of smaller capacity, it is not necessary to employ an absorber having a large number of conduits. Therefore, the resistance to the gas flow is not nearly as great, and the difference in the specific gravity of the gases in the inner and outer passages of the gas heat exchanger and other portions of the gas circuit is sufficient to provide the required gas flow between the absorber and the evaporator.

The cabinet I is identical with that of Figure 4, and is provided with an insulated food compartment IOI, an apparatus compartment I02 therebelow, a rear vertical air flue I03 and an overlying ventilated condenser-compartment I04.

The refrigeration apparatus includes as principal vessels a boiler B, a gas separation chamber S, a condenser C, an evaporator E, a gas heat exchanger H, and a single stage air-cooled absorber A. The boiler assembly, condenser, evaporator, gas heat exchanger,- and solution reservoir are substantially identical with the corresponding elements of the second embodiment and therefore it will not benecessary to describe these elements in detail.

Absorber A consists of a plurality of parallel branches I05 which lie in the same general plane, and each of which is inclined slightly to the horizontal when in operative position. The absorber vessel as a whole is positioned beneath the food compartment with the rearmost branches in the vertical air flue and at a higher elevation than the remainingbranches. The absorber is located far enough below the food compartment to permil; thecooling air to rise vertically through the absorber and then pass laterally into the rear fiue Without again contacting the absorber.

The ammonia vapor produced in the boiler elevates lean absorption solution through vapor lift pump into the top of the gas separation chamber and then passes through conduit I06 into the top of the condenser. Conduit I06 is provided with fins I07 to provide a rectifier R which functions to prevent water vapor from flowing to the condenser.

After the refrigerant vapor has been liquefied, it flows through conduit I00 into the box cooling conduit I09 of evaporator E. As the refrigerant flows downwardly through the evaporator, it evaporates into the inert gas flowing upwardly therethrough, thereb producing refrigeration. The inert gas, which preferably is hydrogen or other like gas, laden with refrigerant vapor, passes through conduit H0 into the central passage III of the gas heat exchanger H, and from there into the lowermost portion of absorber A through conduit II2. As the gas passes upwardly through the absorber in counterflow with lean absorption solution, the refrigerant vapor is absorbed and the substantially pure hydrogen returns to the evaporator through conduit II3, outer passage N4 of the heat exchanger and conduit H5.

The lean absorption solution flows by gravity from the bottom of the gas separation chamber into the top of the absorber through conduit I I6, absorption solution heat exchanger III and conduit I I8. The lean solution then flows downwardly by gravity through the absorber and absorbs the refrigerant vapor. The enriched solution is returned to the boiler through conduit H9, and solution heat exchanger I I1.

It will be observed that all heat rejecting parts of this apparatus, including absorber A, rectifier R, and condenser C, are air-cooled. For this purpose, the branches of the absorber are provided with vertically disposed fins I22, the rectiher with inclined fins I01, and the condenser with fins I23. It will also be noted that the box cool-. ing portion I09 of the evaporator carries fins I24 to facilitate the transfer of heat from th box air to the refrigerant liquid.

A suitable heating means, such as gas burner I25, is properly positioned to heat the boiler. The

In order that the gas heat exchanger may not interfere with the uniform flow of cooling air over all parts of the absorber, this vessel may be located in one corner of the flue.

Figure 8 is a fragmentary view showing in greater detail the manner in which the absorber in any one of the embodiments heretofore described may be constructed. Although the straight portions of the absorber branches have been shown as positioned horizontally in Figures 1 to 7, it will be understood that each branch may be and preferably is inclined slightly to the horizontal, as is more clearly illustrated in Figure 8. From this figure it will be seen that absorber branches I30, I3I and I32 are inclined downwardly to insure that the absorption liquid will flow therethrough by gravity at a desired rate. The rate of solution flow may obviously be increased or decreased by modifying the angle of inclination of the branches.

asoas'n The branches are provided with a. plurality of heat radiating fins I33, I34 and I35. These fins are perpendicular to the axis of the absorber branches. Consequently, if the branches are inclined to the horizontal as shown in Figure 8, the fins will bei'nclined slightlyto the vertical. Since adjacent absorber branches are inclined to the horizontal in opposite directions, it follows that the fins on adjacent branches are inclined tothe vertical in opposite directions. This is indicated in Figure 8 wherein line I31 represents the plane of one of the fins I35 on branch I32 of the absorber. Line I38 represents the plane of one of the fins I34 on an adjacent absorber branch I3I, and line I36 is a vertical line drawn through the intersection of lines I31 and I38. It will now be apparent that fins I35 are inclined to the right from the vertical by the angle I39, while fins I34 are inclined to the left from the vertical by the angle I40.

This inclination of the fins to the vertical is desirable because the cooling air tends to'rise vertically between adjacent fins. The inclination of the fins causes the path of the air to be diverted slightly from the vertical, thereby resulting in more intimate wiping action of the cooling air across the surfaces of the fins.

Figure 9 represents a slightly modified arrangement of the upper part only of the apparatus illustrated in Figures 6 and '7. It will be understood that the remainder of the apparatus not illustrated in Figure 9 is identical with that shown in Figures 6 and 7.

The principal difference between the arrangement of Figure 9 and that shown vin Figures 6 and '7 is the location of a modifiedform of condenser in the vertical air flue. The same reference characters distinguished by a prime will be employed in describing Figure 9. The same reference characters as used in describing Figures 6 and '7, except that they are distinguished by a prime character, will be employed in describing the corresponding element in Figure 9.

Thus, a generally tubular evaporator E is shown as located in a food compartment IOI' of a conventional cabinet I. Box cooling conduit I09 of the evaporator is preferably provided with heat absorbing fins I24. A tubular, finned, aircooled condenser C is located in the topmost portion of the vertical air flue I03". The refrigerant vapor line I05 leads from the generator, not

. shown, to the top of the-condenser, and the vapor liquefied in the condenser is led into the box cooling portion I 09' of the evaporator through conduit I08.

The evaporator connects with the usual gas heat exchanger H, which may be located in the rear air flue. This heat exchanger is provided wi th an inner gas conduit III which is condenser.

substantially across the entire width of the air 75 nected to the box cooling portion of the evaporator, and the bottom of the evaporator communicates with the outer passage II4 of the heat exchanger.

The alternate, transversely extending branches of the condenser are located in two vertically extending banks I24 and I 25. It will be understood, of course, that banks I24 and I25 may be inclined slightly to the vertical, if desired, in order that the condenser will extend entirely across the depth 'of the vertical air fiue, and thereby prevent the passage of some of the air through the flue without passing over the con- Each branch of the condenser extends flue and is inclined slightly downwardly throughout its length. Each branch, is connected at its upper end to the lower end of a corresponding branch in the'other bank. It follows that when the branches are connected together, a continuous fluid passageway is provided which is inclined downwardly from its uppermost to its lowermost end.

Each condenser branch is provided with a plurality of perpendicular heat radiating fins I23. Since all the condenser branches in bank I 25 slope downwardly in one direction, and since all the condenser branches in bank I24 slope downwardly in the opposite direction, it will be obvious that all the fins I 23 in bank I25 are inclined slightly to the vertical in one direction, while the fins on bank I24 are inclined to the vertical in the opposite direction. It is therefore possible to extend all the branches in one bank through a plurality of elongated fins which are common to all the branches in that bank.

As has been seen hereinabove, all parts of the apparatus are constructed of small diameter tubing of iron, steel, or other suitable material. In larger machines, certain of the principal elements have been duplicated in order that the high efliciency of small sized elements may be taken advantage of and also to reduce the Weight of the apparatus and the cost of materials, as well as for other reasons explained in the foregoing description. If large sized vessels andtubing were employed, all portions of the fluids would not come in contact with the walls, as is desired for proper heat transfer, and the thickness of the walls would have to be increased very greatly in order to withstand the operating pressures of the system.

Another important result of my arrangement is that the various parts are arranged in superimposed relationship. This has the advantage of reducing the horizontal cross-sectional area of the cabinet and of increasing the vertical height in order to improve the flue action and the circulation of air over the apparatus. It will also be observed that by virtue of my novel arrangement the cooling air stream flows vertically over all parts of any given element at substantially the same time, and all parts of this air stream of my invention or the scope of the annexed claims.

I claim:

1. In an absorption refrigerating system having an absorber and an evaporator which operate at substantially the same total pressure and in which an auxiliary pressure equalizing medium is employed, an absorber having a plurality of sections, means connecting said sections to the evaporator and for causing the auxiliary pressure equalizing medium to pass through said sections in parallel circuits,,each of said sections having a plurality of stages and means for causing one of the stages of each section to operate at a higher temperature than another stage thereof.

2. In a continuous absorption refrigerating system having an absorber and an evaporator which operate at substantially the same total pressure and in which an' auxiliary pressure equalizing medium is employed, an absorber having a pluabsorption liquid through said absorber, the arrangement being such that the auxiliary medium and the absorption liquid flow in counter-current in certain of said stages and concurrently in others of said stages. I

8. In a continuous absorption refrigerating system, an evaporator, an absorber having a plurality of sections, each section having a plurality of stages, means for circulating absorption liquid through said sections in parallel and in series through the stages thereof and means forcausing an auxiliary pressure equalizing medium to circulate between the evaporator and through said sections of the absorber in parallel, means connecting said stages to direct the flow of the auxiliary medium therethrough in series and in different sequence than the flow of the absorption liquid therethrough.

4. That method of producing refrigeration by means of a refrigerant, an absorbent therefor and a pressure equalizing medium which includes evaporating liquid refrigerant in the presence of pressure equalizing medium to produce refrigeration, removing the resulting gaseous mixture by gravity action, dividing said gravity propelled mixture into a plurality of streams, passing one of said streams into intimate contact with and in counterflow to weak absorbent, passing another of said streams into intimate contact with and in counterfiow to an independent body of absorbent whereby the refrigerant is absorbed from said pressure equalizing medium, and returning said pressure equalizing medium back into the presence of refrigerant liquid to produce further refrigeration.

5. In an absorption refrigerating system having an absorber through which an absorbent medium flows and an evaporator which operates at substantially the same total pressure, and in which an auxiliary pressure equalizing medium is employed, said absorber having a plurality of vessels and means connecting said vessels in parallel with the evaporator and for causing the auxiliary pressure equalizing medium to pass through said evaporator and said vessels in parallel and similar circuits, and in counterflow to the absorption medium, the circuits having an identical path through the evaporator.

6. An absorption regfrigeration apparatus having a multiple stage absorber in circuit with an evaporator, means for passing an absorption solution through first one stage and then another stage of the absorber, means for circulating a pressure equalizin medium from said evaporator into intimate contact with said absorption solution, and means for conducting the pressure equalizing medium out of contact with the-absorption liquid and into heat exchange relation with a cooling medium before returning the same to another stage of said absorber.

'7. The method of operating an absorption rei'rigeration apparatus of the type having a boiler. an evaporator, a condenser and an absorber conasoasu nected in circuit and charged with a refrigerant. an absorbent therefor and a pressure equalizing medium, which method comprises bringing a gas-" the partially separated gaseous mixture out of contact with said stream and into heat exchange relation with a cooling medium external of said apparatus, and then returning the same into the presence of said stream in condition to give up additional vapor to said stream.

8. That method of producing refrigeration with apparatus of the absorption type having a boiler, a condenser, an evaporator and an absorber connected in circuit and charged with a refrigerant, an absorbent medium and a pressure equalizing medium, which method comprises passing a gaseous mixture of relatively cold refrigerant vapor and pressure equalizing medium into contact with a stream of relatively concentratedabsorbent medium for the purpose of further concentrating said medium, then passing the gaseous mixture into contact with a leaner portion of said absorbent medium stream where additional refrigerant is absorbed, then conducting the relatively warm partially separated gaseous mixture out of contact with said stream and into heat exchange relation with a cooling medium external to said apparatus to cool said gaseous mixture, and then passing the cooled gaseous mixture back into contact with absorbent medium to cause still further absorption of the refrigerant vapor.

9. That improvement in the art of refrigeration by means of an absorption system of the typ having a boiler, a condenser, an evaporator and an absorber connected in circuit, a refrigerant, an absorbent fluid and an inert gas with- 40 in said system, said circuit including a gas circuit between said absorber and evaporator, and an absorbent fluid circuit between said boiler and absorber, said last named circuit overlapping, in part, said gas circuit, said improvement comprising providing means in said gas circuit for passing a warm mixture of inert gas and refrigerant vapor out of contact with absorbent fluid and into heat exchange relation with a medium external to said system and at a lower temperature than said warm mixture of gas and vapor whereby the mixture of gas and vapor is cooled, and returning the cooled mixture to said overlapping portion of said gas and absorbent fluid circuits in condition to give up additional vapor to said absorbent fluid.

10. That improvementin the art of refrigeration by means of an absorption system of the type having a boiler, a condenser, an evaporator and a multiple stage absorber connected in circuit, said system being charged with a refrigerant, an absorbent medium therefor, and a pressure equalizing medium, said circuit including a pressure equalizing medium circuit and an-abs rbent medium circuit which overlap in part in said absorber, said improvement comprising means for conducting a warm mixture of pressure equalizing medium and refrigerant vapor from one stage of said absorber into heat exchange relation with a colder medium external to said system for the purpose of cooling said gaseous mixture and returning the same to another stage of said absorber in condition to give up refrigerant vapor to said absorbed medium.

11. That improvement in the art of refrigeration by means of an absorption system of the said absorber, said improvement comprising means for conducting a plurality of warm streams of pressure equalizing medium and refrigerant out of contact with liquid absorbent i certain stages of said absorber and into heat exchange relation with a colder medium and returning said cooled streams to other stages thereof whereby additional refrigerant vapor is absorbed.

12. That improvement in absorption refrigeration apparatus of the type having a boiler, a rectifier, an evaporator and a multi-stage absorber connected in circuit and including an inert gas circuit between said evaporator and absorber, which improvement comprises simultaneously transferring heat from said rectifier to said gas circuit at a point between two absorber stages to promote the circulation of gas therein by thermosyphonic action and condensing absorbent vapor in said rectifier for return to the boiler by gravity, and thereafter cooling said inert gas before it passes into the next absorber stage and into contact with absorption solution.

13. An absorption refrigeration apparatus of the type having a multi-stage absorber and an evaporator in circuit therewith, means for supplying absorption solution to each stage of said absorber for flow therethrough, means for conducting rich inert gas from the evaporator to the absorber and into contact with said absorption solution, and means for conducting inert gas from which a part of the refrigerant has been absorbed out of contact with said solution and into heat exchange relation with a cooling medium, and for returning said gas to the absorber for the removal of the remaining refrigerant by the absorption solution.

14. That improvement in the art of refrigeration by means of an absorptio system of the type having a boiler, acondenser, an evaporator and an absorber connected in circuit, a refrigerant, an absorbent fluid and an inert gas within said system, said circuit including a gas circuit between said absorber and evaporator, and an absorbent fluid circuit between said boiler and absorber, said last named circuit overlapping, in part, said gas circuit, said improvement comprising means for conducting the inert gas out of contact with a stream of absorbent fluid after it has passed through the major portion of the absorber and passing the same into heat exchange relation with a cooling medium external to said system and for returning the cooled gas back into contact with saidstream of absorbent fluid flowing through a minor portion of the absorber. l

15. In an absorption refrigerating apparatus, a vessel having one portion arranged to provide a gas heat exchanger and another portion to pro? vide a reservoir and gas conduit, an absorber coil including a plurality of finned directly air cooled conduit branches inclined for gravity flow of absorption solution therethrough, means connecting one end of said absorber coil to said gas heat exchanger portion of said vessel, and means connecting the other end of said absorber coil to said reservoir and gas conduit portion of said vessel.

16. In an absorption refrigerating apparatus, a

vessel, means in one portion of said vessel defining a plurality of gas paths in heat exchange relationship, the other portion of said vessel communicating with one of said gas paths and forming a solution reservoir, and an absorber coil including a plurality of directly air cooled finned conduit branches having one end connected to said vessel to communicate with a gas path not in communication with said reservoir and its other and connected to said vessel to communicats with said reservoir.

17. In an absorption refrigerating apparatus,

- an evaporator, an absorber comprising a tubular directly air cooled conduit, 8. generator, a vertically positioned vessel, means in the upper portion of said vessel providing a plurality of gas paths in heat exchange relation, the lower portion of said vesselforming a solution reservoir and being in open communication with-one of said gas paths, means connecting said evaporator to the upper portions of said gas paths, means connecting said generator, said reservoir and said absorber to form a solution circuit, one

end of said absorber being connected to the gas space of said reservoir and the other end being connected to the 'lower portion ofa gas path in said vessel not in open communication with said reservoir.

18. Absorption refrigeration apparatus including an'upper condenser comprising a tubular conduit having turns in a single substantially horizontal plane, a lower absorber comprising a tubular conduit coiled in a single substantially horizontal plane, and an evaporator comprising a tubular conduit above said absorber and below said condenser, conduit means arranged to convey a gaseous mixture of inert gas and refrigerant vapor from said evaporator to a first part of said absorber coil, conduit means arranged to convey an absorptionsolution to said first part of said absorber, conduit means arranged to convey said mixture. and said absorption solution from saidiirst part of said absorber to a second prising essentially a tubular conduit disposed in said apparatus compartment and having a plurality of heat-dissipating conduit branches in a single substantially horizontal plane, all of said branches being substantially in parallel with respect to air flow and each of said branches being exposed to cooling by air of entrance temperature, unheated by previous dissipation of heat of absorption, at least a major portion of said tubular absorber having its conduit portions nonoverlapping with respect to air flow, conduit means providing for circulation of an inert gas refrigerant vapor mixture through one part of said absorber in one direction and through another part of said absorber in another direction, and conduit means providing for flow of an absorption solution through said parts of said absorber in the same direction. 1

20, An absorption refrigeration system including a generator, a condenser, an evaporator, an absorber, and members connecting said parts for circulation of refrigerant through the parts, for circulation of absorption liquid between the generator and the absorber and circulation of inert gas between the absorber and the evaporator, said members being so constructed and arranged that the inert gas and absorption solution flow in the same direction through a portion of said absorber and in opposite directions in another portion or said absorber, said absorber having heat rejecting surface provided by a finned conduit having branches all of which are in a single substantially horizontal plane, and members forming a path for upward flow of air in cooling relation with said absorber so that all parts of the absorber are substantially in parallel with respect to the air flow, each of said branches being exposed to cooling by air of entrance temperature, unheated by previous dissipation of heat or absorption.

21. An absorption refrigeration-system including a generator, a condenser, an evaporator, an absorber, and members connecting said parts for circulation of refrigerant through the parts, for circulation of absorption liquid between the gen erator and the absorber and circulation of inert gas between the absorber and the evaporator, means for removing inert gas from contact with solution between said portions of said absorber and for conveying the inert gas through a path of flow in heat exchange relation with a cooling medium, said absorber including a finned conduit having branches all of which are in a single substantially horizontal plane, and members forming a path for upward flow of air in cooling thereof are .substantially'in parallel with respect to the air flow and each'ot said branches is exposed to cooling by air, unheated by previous dissipation of heat of absorption from said 0 branches.

RUDOLPH S. NELSON.

relation with said finned conduit so that all parts

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