US1878831A - Absorption refrigerating system - Google Patents

Description

Sept 20, 1932. s R CUMNHNGS ,878',83

ABSORPTION REFRIGERATING SYSTEM Filed Jan. 24. 1930 2 Sheets-Sheet l Sept. 20, '1932. s, R CUMM|NGS ,878,83l

ABSORPTION REFRIGERATING SYSTEM Filed Jan. 24. 1950 2 Sheets-Sheet 2 5 w22 I ILL Patented Sept. 20, 1932 UNITED .STATES P STANLEY B. CUMMINGS, OF CANTON, OHIO, ASSIGNOR TO THE HOOVER NORTH C ANTON, OHIO, .A CORPORATION OF OHIO nsonrrron REFBIGERATING- SYSTEM Applicationvled January 24,- 1930. Serial No. l1223,075.

This invention relates to the art ofV refrig-"l erating and more particularly ,to an absorption refrigerating system in which a plurality of refrigerants are simultaneously evaporated to produce a cooling efect.

` Continuousv absorption refrigerating systems employing a single refrigerant in combination with an inert or neutral gas are well known. "In such a systemv the inert gas is circulated between the evaporator and the absorber for the purpose of maintaining the tot'al pressure in these parts the same as that in the other parts of the system although the partial pressure of the refrigerant changes.

Anexample of such a system is found in the U. S. Patent to Geppert 662,690. As an improvement on this system is has previously been proposed to substitute a second refrigerating agent for the inert gas of the Geppert system so that both the main cooling agent and the auxiliary pressure.equalizing agent may be`condensed before they are introduced into the evaporator, the object being to increase the eiiiciency andthe cooling effect of the system. Perhaps the best substances suggested for this purposevare ammonia and propane, these two refrigerants being condensable at about the same temperature and pressure and being practically immiscible.

In attempting to operate a system having two refrigerants, one of the chief diuculties encountered has resulted from the fact that it is difficult if not impossible to completely separate the two so long as they remain in a gaseous or vapor phase. Unless effectively nseparated, the refrigerants get into the condensers in which they do not belong and prevent successful operation of the apparatus.

An object of the present inventionis to provide effectivemeans for separating the refrigerants of such a system so that each may be condensed independently at the pressure existing within the system and at temperatures which may be considerably above that prevailing inthe evaporator.

A further object of the invention is to provide a practical refigerating system employing a plurality of refrigerants and in which 60 all of the partsare in` opencommunicatiqn with one another so that nearly the same total pressure prevails throughout the system, the refrigerants-mutually cooperating to reduce .the partial pressure of each so that evaporation of both may take place to produce a cooling effect.

A further object is to provide a method of eectively separating the fluids of a refrigerating system so that they may be readily condensed. v

Other objects and advantages reside in certain novel arrangements and construction of parts'as will be apparent from the following description taken in connection with the accompanying drawings in .which Figure 1 is a diagram .of an absorption refrigerating system embodying certain novel features and illustrating one form of apparatus made in accordance with the principles of the invention and Figure 2 isa diagrammatic showing of a modified form of system illustrating the principles of the invention.

Referring to Figure l of the drawings, the system is there shown as'consisting of agenerator or boiler G, rectifiers .R1 and densers C1 and C2, evaporator E and an absorber-.separator S as essential elements, these vessels bein connected by suitable conduits, as shown.y ll-of these parts may be made of steel. In general, they are cylindrical in shape so thatordinaryseamless steel tubing may be used in manufacturing them.

The generator G comprises a hollow shell -10 having end closures or heads 11 and-12 at the top and bottom thereof. The lower end piece 12 is provided with an inverted cup 13 which is welded orotherwise secured to an opening therein and which is adapted to receive an electric cartridge heating element 14. Obviously a gas flame or other heating means may be employed in place of the electric heater. In normal operation, a solution of ammonia circulates through the generator. For conducting the solution into the generator a pipe 15 extends through the wall or shell 10 and is connected to a small coil of tubing 16 which is wrapped around the inverted cup 13. The upper end of the coil 16 is connected to al small vertically extending COMPANY, or

2, conpasses through the electric heater l14, bubbles of ammonia gas are generated in the coil 16 and as-they rise through the pipe' 17 lift or pump the solution into the main body .of the generator, this action being similar to that ound in certain types of household coffee percolators. A similar arrangement of a gas lift pump of this nature in a refri'gerating system is shown and described in U. S. Patent to Altenkirch 1,728,742. j

Aside from the ammonia gas generated inl the gas lift pump, an additlonal amountof gas may be driven oi by the application.` of heat from the electric heater to the main portion ofthe generator. The gas .passes upwardly through an openingin the closure 11 and into the rectifier R1 which is provided with suitable baiiles, as shown, for removing water vapor which is driven o with the ammonia.- vAn additional amount of waterwapor is removed in the rectifier R2. This deviee comprises the central pipe 19 to which fins for radiating heat are welded or otherwise secured. The upper end of rectifier R2 is connected to condenser C1 through the pipe 21. A valve 22is provided in the pipe 21- .which may be opened to charge the machine.

.As ammonia is driven off from the water, the weak ammonia solution -is conducted away from the generator through the conduit 23. The condensers C,L and. C2, referred to above, may be of any suitable construction. They are shown for the pur oses of illustration as consisting of coils o tubing, the coil C2 being the larger of the two. The lcoils are immersed in a tank 24 through which cooling water is adapted to circulate, inlet pipe 25 and outletpipe 26 being provided for this purpose. Since the condenser C2 i-s the larger of the two, the temperature thereinwill be more nearly that of the cooling water. The lower ends of the condensersC]L and C2 are connected to the evaporator E by plpes 27 and 28 each of which is provided withh a suitable valve.

The evaporator E' is so constructed that the liquids entering through the'pipes 27 and 28 do not mix so long as they are 1n the liquid phase but each liquid is exposed to .the vapor phase of the other. Fora full disclosure of this evaporator reference may be had to .the copending application of' Rudolph S. Nelson, Serial No. 423,125 filed Jan. 24, 1930, entitled Evaporators for rev frigeratin systemslwherei'n this evaporator is more ully disclosed and claimed. As herein shown it consists of a cylindrical shell 29 having'end" pieces or heads 30 and 31 at the upper and lower ends. The pipes 27 and 28 extend through the head piece 30 and terminate a short distance above the bottom of cups 32 which have overflow outletsnear their'upper ends.` Liquids enteringthroilghthrough the conduit 33 extending through` the lower end piece 31.

/An import-ant feature of the present invention resides in the `arrangement and construction of the absorber-separator vessel S together with means for cooling the lower por,- tion and heating the upper portion thereof.

Like the generator and evaporator the separator S is preferably composed of a` shell 35 provided with upper and lower end closures 36, 37. There are four conduits communi- 1eating with-the interior of this vessel. Conduit 33- passes through the wall of the shell j near its lower end for connecting the vessel tothe evaporator. Conduit 38 having a valve 22 therein similar to valve 22 4connects the upper end of the vessel to the condenser C2. Condits 39 and 41 terminating at the bottom and side of the vessel respectively connect it with a heat exchanger 40.

v This heat exchan er is of the conventional double coil type.

ne endof the inner coil is connected to the pipe 39. The other end is connected to the gas liftpump 16. The

outer tube of the heat exchanger. is connected to pipes 41 and 42. The pipe 42 is adapted to convey solution into the heat exchanger from a heating jacket 44 surrounding the up"- per portion of the separator, this jacket being supplied with solution by the pipe 23. By thls construction solution passing from the generator G through the conduit 23 may heat the upper -portion of the separator by convection from the generator. Since it is likely that some as may collect in the jacket 44, it may be a visable to provide a bleed lpipe for conveying it back to the generator.

A pipe for this purpose is shown at 43.

For coolin the lower portion of theaabsorber,`a jac et 45 is provided, this jacket having aconnection 46 for supplying cooling water thereto. From thejacket 45, the water goes through the pipe 25 to the tank 24.

For aiding inthe conduction of heat away from the lower portion of ythe separator andl for facilitating the absorption of ammonia, the separator may be partiallyy filled with steel wool-47 or other heat conducting material adaptedt'o break up gases entering through the pipe 33 from thev evaporator into small bubbles.v The steel wool may be held in place by perforated plates 48.

The liquid levels in the .various parts ofl .the apparatus are criticall to successful operation of the machine. For this reason itis necessary that the various parts be positioned approximately `as shown in the drawings.

i vThis will more a :has filled the same up to approximately the parent after considering the operation of the system.

The apparatus may ated as follows A quantity of ammonia solution is placed in the 'generator G and separator S through suitable valves, not shown; until the same level ofpipe 23. While the concentration of the ammonia solution may vary,` itgisv deemedadvisable to use one of relatively low concentration preferably not over 15% weight. As the'solutionis being placed -1n these vessels,

g phere so that air in the machine may escape.

A1nmonia the apparatus in the usual mannerto sweep out any remaining air. The valve 22may gas may thenbe forced through then beclosed and liquid-propane lfed into the conduit 38 through the valve 22 therein. This liquid propane collects in the separator and causes the solution level in the generator to rise slightly but since propane has a specific gravity much lower than that of the ammonia solution, it'loatson top of the solution in the separator. The quantity of propane placed into the system should besomewhat more than that necessary to occupy the portion of the separator opposite the heating jacket 44 plus that necessaryto lill one of thecups 32 andform a'column in the pipe 27, liquid propane normally being in these parts to this extent during operation of the system.

- After `the machine is so charged heat may be applied to the generator by causing current to pass through the electric heater. This causescirculation ofthe ammonia solution and since the heatvexchanger and other pipes offer some resistance to iow, the liquid levels in the generator and separator assume the position approximately as shown indotted lines.- Ammonia vapor -orgasis delivered to the condenser C1 and propane vapor is delivered to condenser C2. The heat necessary for the evaporation of propane whichhas collected inthe upper portion of the separator is supplied by the -warm ammonia solution circulating through the jacket 44. :Since the condensers C1 and C2 are maintained at a temperature considerably below that .of the boiler and upper, portion of the separator,

the two refrigerants condense in their re -vapor is much less. As evaporation takes be charged and operi valves 22 and 22 in the con! duits 21 and 38'should be open to the atmosplace heat is -taken up from the surroundfings to produce a cooling' effect. At this time. `the total s 1 pressure inthe 'evaporator becomes htly larger than elsewhere in the system an 'causesthe formation of liquid columns in the pipes :27 land 28 as the refrigerants continue to condense. Upon the pressure in the evaporatorv becoming large enough to overcome the slight excess vpressure due to vthe .liquid columnhead in theV separator bubbles of ammonia and propane are -forced into the lower portion of the separator through lthe pipe 33. As these bubbles mix with the weak solution coming to the separator through the'pipe 41 the ammonia content'issab'sorbed, this causing an increase in 'the percentage of gaseous propane in thev bubbles andsince the bottom portion'of the separator is maintained cold by the cooling jacket 454 the propane "condenses at this point. As the propane condenses it rises to the upper portion of the separatorwhere it is again driven oi by heatfrom the heating jacket 44 thus completing its cycle.

The ammonia whichis absorbed in the, solution in the lower portion of the separator is conducted through the pipes 39, the inner tube of. the heat exchanger 40` the plpe 15, gas lift pump 16 and pipe 17', back intothe generator where it lis again driven oil to complete its cycle.-

The solution thus deprived of ammonia returns to the separator vthroughthe pipe 23,

'jacket 44, pipe 42., outer tube of heatex'- changer 40 and pipe j41. Effective separa-v tion of the'refrig'erants results from the novel functioning of the separator'. Iln refrig'en `atingsyste'ms heretofore proposed employ ing-a plurality of refrigerants, extreme difficulty has been encountered in separatlng the refrigerante so that they lmay be agaln condensed andfed into the evaporator in liquid form. Unless the refrigerants-are separated,the'apparatus cannot function to produce refrigeration for it is obvious that it gaseous ammonia collects in .the propane conne 'A .denser C2 to the extent that thegasequsgmixture therein is the same as that inthe evaporator'E then the propane cannotcondense in condenser C2 at a temperature higher than it evaporates in the evaporator. To obviate this diiiculty itis proposed.' in accordance with the present linvention, to separate the Jtwo refrigerante by gravity and since they are practically immiscible inA their liquid phases very eflicient separation can be efcted in this manner. But before they can be separated by gravity however, it is first necessary to reduce them-to their liquid phases. This iat is accomplished in accordance with the inv vention, by causing lthe ammonia to be ab-` sorbed in a weak solution while at the'A same time the gas deprived of a large portion of its ammonia contentris maintained at a low enough temperature to condense the propane. Furthermore after the propane has been separated it must be again returned tov the evaporator. In the present case this is Adone by causing it to be vaporized and fed into the condenser C2. The separator S, together with the associated ackets thus provides a compact and unitary assembly for accomplishing all of these unctions.

Since the drawings is only diagrammatic in nature it is obvious that in constructing an apparatus in accordance with the principles of the invention, various expedients may be resorted to and various changes may be made in the arrangement and construction of the various parts without departing from the spirit of the invention. Various kinds of rectifiers, generators, condensers, etc., may be substituted for those shown and various types of pumps lor e'jectors substituted for the gas lift pump 16.

As illustrating a somewhatdi'erent con- ,struction for carrying out the principles of the invention reference may be -had to Figthe different absorber structure, the condensure 2 in whichV the general arrangement and construction of the various parts of the apparatus is similarto that of Figure lvbut in which a different form. of generator, separator and pumping means for the'absorption solution is illustrated. In this figure the rec- -tifiers, condensers and evaporator are identical with those of Figure 1 and need not be further described here. 'However,-because of the coil 29 and pipes 27 and 28 of Figure 1 of the copending apfplication of Altenkirch,

Serial No. 99,890, led April 5, '1926, for absorption machines. As this gas from the evaporator meets with the solution Ycoming through the lower portionvof pipe 141 connected with the outer tube of the heat exchanger 140, it causes this liquid tovrise through the coil 116 into the separator S2. From the separator the solution flows out through the pipe 139 through the inner tube` of the heat exchanger 140, into the boiler-` through the pipe 115 and from there back to the outer coil of the heat exchanger through the pipes 123, a heating coil 144 and the conduit 142. Since the direction` of circulation is upward both in the generator and in the separator the circulationk is aided by thermo- Siphon action and by the generation of bubbles which pass upwardly in the generator.

Essentially the separator S2 functions the same as separator S of Figure 1, its lower portion being cooled by the cooling tank 145 and its. upper portions being heated by the coil 144. The directions of ilow of the absorption solution through the separators are opposite in the two cases, however.

ince the pressure in the evaporator of Figure 2 must be somewhat higher than that necessaryvin Figure 1, because of the greater liquid head to be overcome in the separator, 4it is necessary that the pipes 27 and 28 be long enouglrtopermit columns of liquid to form therein of sulicient height to balance the head in the separator. For this reason the condensers of Figure 2 must be a greater distaice above theevaporator than that necessary in Figure 1.

It is also necessary to charge the apparatus of Figure 2 with more propane than that employed in the arrangement of Figure 1, since the separator S2 vshould atall times, have enough liquid propane therein to extend from a level just below the coil 144 to a level near the top of the separator.

.It will be obvious'to those skilled in the art that various other changes may be made without departing from the spiritof the invention or the scope of the annexed claims. For example the vessels may be made of diierent shapes and dimensions so long as they do not interfere with the intended circulation and liquid levels. It is also within the scope of the invention to control the circulation ofl the refrigerants or the absorption solution by providing suitable' regulating valves in the various conduits and to control the' application of heat to the generator and absorber. This may, for example, necessitate the provision of a conduit connected in parallel with the jacket 44 between the pipes 23 and 42 with suitable valves for regulating the amount of warm solution which flows through the jacket.

I claim 1 1. In a refrigerating system of the absorption type employing a plurality of refrigerants, the combination of a lgenerator for expelling one refrigerant from an absorption solution, an absorber-separator, means for feeding a vapor mixture .of said refrigerants into said absorber-separator, means for circulating the absorption solution between said generator and said absorber-separator to cause one refrigerant to absorbed and another-condensed in said absorber-separa- *torand a jacket surrounding a portion ofemploying two refrigerants,

- 2. In an absorption 'refrigerating one refrigerant to be absorbed and the other condensed in said vessel and means forcausing the solution to pass around a portion of said separating vessel before it is passed into the interior thereof to convey heat thereto from the generator and therebyvaporize the condensed refrigerant therein.

l3. In a refrigerating system having a generator and an absorber and employing two refrigerants, the method of vaporizing one refrigerant from an absorption solution in absorberseparator to vaporize the condensed refrigeranttherein. n

Signed at North'Canton, in the county of Stark, and State of Ohio, this 23rd dayof January, A. D., 1930.

STANLEY R. CUMMINGS.

said generator and another refrigerant from y its liquid phase in saidv absorber whichl includes the steps of applying heat directlyV to said generator, circulating absorption solution between said generator and said absorber and causing said absorption solution to give up heat to a portion of said absorber before mixing directly with the fluid therein. 4. The method of producing refrigeration including the steps of feeding two diffe/rent refrigerants in liquid phase into an evaporator, from the evaporator into a separating vessel, causing one refrigerant to be absorbed in an absorption liquid and the other tobe condensed in said vessel, separating the condensed'refrigerant from the absorption solution by gravity, conveying the enriched absorption solution to a generator, applying heat to said generator to drive olf the absorbed refrigerant and conveying the weakened absorption solution back to the absorber while causing a transfer of heat from the weakened absorption solution to the Huid in the Vabsorber as the weakened absorption solution passes on its way to the absorber to thereby vaporize the refrigerant which has been condensed in said absorber.

5. In an absorption refrigerating"system employing two refrigerants, the combination of an evaporator adapted to cause the two refrigerants to evaporate, an absorbeksepa; rator, a generator adapted to expel one of said refrigerants from an absorption solu.- tion and means for circulating absorption solution between said absorber-separator and said generator to cause one refrigerant to be absorbed and the other condensed in said absorber-separator, `said circulating means including a device for causing the absorption solution to pass in heat transfer rela-1 tion with a portion of said absorber-separator before it passes into direct contact with conducting thevaporized refrigerant A the iuids therein and thereby transfer heat from said generator to a portion of said

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