US1549990A - Refrigerating apparatus - Google Patents

Description

Aug. 18, 1925,

p, F. KEITH assamrmnne APPARATUS II ilm m1 4 Sheets-Shem: 1

INVENTOR Aug. 18,- 1925. I 'D. F. KEITH REFRIGEI'IATING APPARATUS Patented Aug.. 8, 1925. I r 1,549,990 Y UNITED. STATES PATENT OFFICE.

DAVID FORBES KEITH, OF TORONTO, ONTARIO, CANADA, ASSIGNOR TO KEITHS LIMITED, 01 TORONTO, CANADA, A CORPORATION O'F ONTARIO.

REFRIGERATING APPARATUS. Application iiled January 19, 1921. I Serial- No. 438,389.

To all whom it may concern: generator-absorberany "absorbent liquid Be it known that I, DAVID Fonuns KEITH, which has for any reason-accumulated in a subject of the King of Great Britain, residany other part of the apparatus. ing at Toronto, in the county of York and Still another object of the invention is to 5 Province of Ontario, Canada, have invented provide a refrigerating apparatus of the certain new and useful Improvements in Retype described, in which the starting of the frigerating Apparatus,of which the followgeneration of refrigerant gas is controlled ing is a specification. by the temperature of the cold or storage- This invention relates torefrigerating apchamber.

} paratus and more particularly to refrigerat-' A further object of the invention is to ing apparatus of the intermittent-absorpprovide in a refrigerating apparatus comtion type in which a refrigerant solution pletely housed Within a cabinet containing 1 contained within a generator-absorber tank the cold chamber, an arrangement of parts is heated'to generate refrigerant gas which whlch reduces to a minimumthe passage of 15 passes through a circulation system to a heat into said cold chamber.

condenser-evaporator tank where the refrig- A further object is to provide in a refrigerant is liquefied owing to the pressure and cra ing, apparatus of the type described to the application of cooling means operatpositive means for preventing a dangerous ing on the, condenser. When a predeterincrease of pressure within the system in I 2 mined amount of liquid refrigerant has-acc e t e means for discontinuing the applicumulated in the condenser-evaporator the cation of heat to the generator-absorber do application of heat to the generator-abinot operate to discontinue such heating at sorber ceases and the resulting decrease of the proper time. pressure evaporates the liquid refrigerant Other objects Will be pointed out as the accumulated in the condenser-evaporator description progresses.

the latent heat of vaporization being ,ab- In the present embodiment of the invenstracted from the surrounding air contained tion there is provided a refrigerating apwithin a cold or st0rage-chamber, which is paratuspf the intermittent-absorption type, further chilled in consequence, while the vacomprising a generator-absorber and a conpor passes back and becomes again absorbed denser-evaporator mounted on opposite by the liquid within the generator-absorber. arms of a rocking-frame which passes The principal object of the invention is to through an aperture in the heat-insulating provide a simple, compact refrigerating apwall of a cold or storage-chamber, the conparatus which may be constructed in small denser-evaporator being located within said 35 it it bl f s f example, in th chamber, means actuated in response to the home, is entirely automatic in operation, and rocking of said frame in one direction for 5 iniwhich heat is directly removed from the allowing the refrigerating cycle of operation cold or storage-chamber by the air-circulato proceed, and means controlled by the temtion set up by the vaporization of the reperature of said cold or storage-chamber for 40, frigerant contained ,within the condenserpreventing such movement of said frame evaporator situated within said chamber. while said temperature is below a predeter- Another object of the invention is to promined figure. e r

vide, in a refrigerating apparatus having In the drawings illustrating one embodia circulationsystem for the refrigerant, a ment of the invention: i

45 gravity operated mercury valve to alternate- Figure 1 is a diagrammatic front'elevaly open and close a portion of said system to tion, showing the position of the aiprparatus control the circulatlon therein. during the generation of the re lgerant A further object 'of the invention-is to gas; provide positive means for returning to the Fig. 2 is a front sectional elevation, with certain parts broken away, of the refrigerating apparatus in the position occupied during the absorption of the refrigerant gas;

Fig. 3 is a sectional plan view taken on the line 33 of Figure 2; and

Fig. 4 is a sectional end view taken on the line 4-4 of Fig. 2.

In the drawings, 1 designates the outside wall of a cabinet which is divided by the walls 2, of heat-insulating material, into a cold or storage-chamber3 and an appara tus-chamber 4. The'floor'of the apparatuschamber is covered by a metallic drip-pan 5 provided on the three outer sides with a low vertical wall 6, and on the side adjacent the storage-chamber with a higher extension 7 having two marginal flanges which support the moving parts of the refrigerating apparatus.

Supported by the front and rear mar ginal flanges aforesaid is a shaft 8, on which are pivotally mounted one or more supporting-brackets 9, 'of which two are employed in the present embodiment. Suitably secured to the outer ends of the brackets 9 is a generator-absorber 10, here shown as a drum. A flanged conduit 11 is secured at one end to the drum 10 and forms one arm of a rocking-frame, the other. arm of which comprises a similar flanged conduit 12 which supports condenser-evaporator 13. The adjacent flanged ends 14 and 15 of the two conduits (constituting the arms of the rocking-frame) are separated by' a disk 16, of fibre or other suitable heat-insulating material, andare held together as by" bolts 17, which are'insulated from the flange 14 by washers 18 of suitable heat-insulating materiaL'thus obviating any metallic contact between the two arms of the frame, and thereby minimizing the conduction of heat along said frame. The lowering of the generator-absorber 10, by the rocking movement of the frame, is limited by the abutment of a bracket 19, carriedby said generator-absorber, against an upward extension'20 of the upright flange 6' of the drip-pan 5; and the rocking movement in the opposite direction (to raise the generator-absorber and lower the condenser-evaporator) is limited by the abutment of the fibre disk 16 against an annular shoulder 21 provided on the extension 7 When the frame is in this latter position, the disk 16 closes the aperture between the apparatus chamber and the storage-chamber (occupied by the conduit 12), so that heat can pass but slowly therebetween.

The condenser-evaporator, while essent1al1y but a closed container, most desirably takes the form of a number of horizontally disposed tubes 22, closed at their inner ends,

and supported by the flanged portions 23 of the arm 12 of the rocking-frame. These tubes are covered by a fluted cover 24 or suitable f heat-conducting material. The outer ends of the tubes 22 discharge into a closed header 25, the sloping bottom 26 of which allows any liquid within the header to flow to the end of the return pipe 27.

Referring now to the water-circulation system, a trough 29, separated into two compartments by a vertical partition 30, is supported by pipes 31 and 37 to move with the rocking-frame. A constant stream of cooling water is supplied from any suitable exterior supply of water through the fixed pipe 28, which stream discharges into either the right or left-hand compartment of the trough 29 in accordance with the position into which the trough has been shifted by its supporting frame.

During the generation of refrigerant vapor when the apparatus is in the position shown in Fig. 1, water flows from the pipe 28 into the right-hand compartment of the trough 29 through pipe 31 to the transverse pipe 32, which is provided with perforations 47 through which the water is discharged upon the cover 24, and flows down the length of the cover in channels between the corrugations which cover the 'condensing tubes 22, and over the edge 33 into the collecting trough 34. The trough 34-is cut away at a convenient point to allow the water to flow into the drain-conduit 35 from the lower end of which it flows through the pipe 36 into the pan 5. The pan 5 is provided with a suitable discharge-drain, not-shown.

When the apparatus is in the position shown in Fig. 2, water fiows from the pi e 28 into the left-hand compartment of t e trough 29 and through the pipe 37 into a water jacket 38 surrounding the lower portion of the generator-absorber 10 from which it passes through the pipe 39 into the suitable insulating material, which is se cured to the flange 43 of the wall 6 of the drip-pan. Two conductors 44 connected to a suitable source of electrical power, not shown, may be connected to the cups 41, as by binding screws 45. When the tank 10 is in its lowermost position (as in Fig. 1) the ends of the terminals 40 enter the. mercury 46 in the cups 41, thereby closing the circuit of the electric stove to heat the solution contained within the tank. When the apparatus is in the p siti n sho n in 2, however, the terminals 40 are removed from the mercury 46 and the circuit of the stove is broken.

condensed. The contents of the generatorabsorber are then cooled, causing decreased pressure, so that the refrigerant liquld 1n the condenser-evaporator is evaporated and passes back to the generator-absorber where it is absorbed in the solution therein contained.

. .Since the gas generated Within the gen erator-absorber is lighter than the solution and rises; an exhaust pipe 52 is connected near the top of the tanklO to carry off the generated vapor. To effect eflicient absorption of the returning vapor, however, 1t must be introduced below the. -level of the solution, which would not occur if 1t were allowed to return through the exhaust pipe 52. There is therefore provided an absorption pipe 57 which terminates below the level of the liquid within the absorber 10, so that returning vapor bubbles up through the liquid and is absorbed. a

Means must thei'eforebe supplied to allow vapor to pass freely from the exhaust pipe 52 to the condenser-evaporator, but to pre vent returning vapor from passing through said pipe. In previously knownrefrigerating apparatus of the intermittent-absorptlon type Various mechanical valves have been employed, but without satisfactorily solv- 7 ing the problem. A trap filled with liquid to a definite height, through which the exhaust vapor bubbles on its way to the condenser has also been employed, but this arrangement has many disadvantages, such as causing surging-ofthe trap liquid into the vcondenser pipe.

There is therefore provided by this inven tion a trapv 48, mounted to rock with the containers carried by the rocking frame, and

filled to a suitable level (as shown by the dotted lines in Figs. 1 and 2) with mercury or any suitable heavy-liquid having a high boiling point" and unattacked by boiling refrigerant. Thus while the apparatus is in the position shown in Fig. l refrigerant vapor passes freely from exhaust pipe 52 through trap 48 into rectifying pipe 53 which leads to the condenser. When, however, the apparatus has rocked to the position shown in Fig. 2, the end of exhaust pipe 52 in trap 48 is sealed'by the liquid therein, so that refrigerant vapor returning through pipe 53'cannot enter pipe 52 butfmustpass through absorption pipe 57 .to be re-absorbed.

The remainder of the structure will be described in connection with the operation of the refrigerating apparatus, which is as follows: through the port 49 the apparatus 'is first exhausted of air, and the generatortrap, the best results have been obtained by.

the employment of mercury. Upon the con- I nectiono'f the conductors 44 to a source of electric power, the apparatus being in the position indicated in Fig-l, the' cycle of With the ammonia sooperations begins. lution in the generator-absorber 10, that side (the left-hand side) @of the apparatus'is heavier than the other (right-hand), so that the bracket 19 rests on theside-wall 20, as seen in Figure 1, in which position the circuit for thestove within the generator is complete and heating of the solution begins.

As the temperature is raised, ammonia is vaporized from the solution in the generator-absorber, and passes through perforations 50 in the baflie-plate 51, through the exhaust pipe 52 into the trap 48 and thence through the rectifying pipe 53 (which is jacketed, as has been described, by the water pipe 35) into .the distributing pipe 54, through the transverse pipe 55 and its ver-- tical branches 56, whence the ammonia vapor is discharged into the tubes 22; Owing to the gradually increasing pressure inv the tubes 22 and the flow of cooling water from the pipe 32, the ammonia gas is gradually cooled and liquefied.

' While the bafiie-plate 51 prevents surging of the solution into the exhaust pipe 52,

some water-vapor will, nevertheless, be carried with the generated ammonia vapor, but

' a large part of this water-vapor will be condensed while passing through the rectifying pipe 53 and will flow back into the gen- .erator by gravity throughthe return pipe 57.

As the generation of ammonia progresses,

the weight of the generator (or left-hand) side of the system is decreased and the con densed refrigerant in the tubes 22 gradually increases the weight-of the other (or'righthand) side of the system,- until at the time that substantially all'the ammonia has been driven off from the solution in the generator the shifting of the weight is suflicient to rock the frame to lower the condenser-evaporator and raise the generator-absorber until the disk 16 engages (and rests against) its seat 21. The condensate which is' accumulated in the condenser fills the ower left end of the: same. As this end 'is closed, the con densate is unable to return by gravity to the generator. From the configuration of the parts, it will be noted'that most of the condensate is accumulated so as to have a short moment arm. It is only after con siderable condensate has been accumulated and when the added increments are dieposited at a considerable distance fromthepivot, that the condenser side may be automatically lowered.

The apparatus is now in the position shown in Fig. 2. The cover 24 of the condenser-evaporator is nowhorizontal so that the-cooling water trapped in the pipe 31 drips over the right-hand edge of the cover, down the face of the header 25 and over the sloping bottom 58 into the collector 59. A portion of this water runs down a depending stud 60, carried by the condenser-evaporator, so as to fill a suitably-supported stationary cup 61. The collector 59 is drained through the tube 62which exhausts through the trap 63 into the drip-pan 5.

The cooling water, now flows through the pipe 37 and fills the water jacket 38 around the generator-absorber 10. The addition of this cooling water does not, however, rock the frame, as the condensate is now in a more remote part of the condenser-evaporator and has a longer moment arm sufficient to maintain the rockingframe in the evaporating position. The cooling water in the jacket lowers the temperature and consequently the pressure within the drum, thereby causing the liquid refrigerant in the tubes 22 and the header 25 to again vaporize and pass back, through the distributing pipe 54,

into the rectifying pipe 53, and then it passes through the absorbing pipe 57, the open end of which is submerged in the solution in the generator-absorber 10, where the ammonia vapor is again absorbed.

As it is desired that the returning refrigerant shall be absorbed in the solution, it is necessary to prevent any vapor from flowing through the trap 48 and the pipe 52. Such flow is effectively prevented'by the liquid in the trap 48. which seals the open end of the pipe 52 when the apparatus is in this position.

v i The evaporation of the refrigerant within the condenser-evaporator absorbs heat which can only be supplied from within the storagechamber 3. The air immediately surrounding the condenser-evaporator thus becomes very cold and, owing to its increased density, "passes downwardly through the aperture in the bottom 58, around the collector 59 and through the central aperture in the baflie G4 to the upper portion of the chamber, 3. The Warm air from near the insulating walls 2 passes upward, preferably through a conduit provided by partition 65, which extends from near the top of the insulated chamber down into the storage compartment 3, and being cooled by contact with the evaporator descends, as just described. Thus the entire contents of the cold chamber 3 are cooled by convection. In order to increase the conducting surface-of the evaporator, depending fins 66 may be carried by the tubes 22. -The bottom 58, collector 59, and baffle 64 are most desirably made of heat-insulating material, such as fibre-board or the like'so that the heat given off during the condensing of the refrigerant will not be radiated to the chamber 3, but will be carried off by the cooling water flowing through theoutlet pipe 35.

As the air circulates about in the refrigerator, moisture is condensed by and frozen onto the cold evaporator thereby drying the entire contents of the refrigerating chamber. This frost which is collected on the evaporator is melted off during the condensation stage and it drains down into the collector 59 and thence is discharged from the refrigerator. In each succeeding cycle in the operation of the refrigerator more of the moisture is condensed out thereby maintaining the dry condition in the refrigerator.

When the temperature of the water in the cup 61 is sufficiently lowered by the evaporation of refrigerant within the evaporator, the contents of the cup freezes, thereby looking the stud 60 within the cup 61, which is rigidly secured to the bottom 58 in any desired manner. Thus, although the weight of the left-hand side of the apparatus becomes greater than that of the right-hand side, and tends to rock the supporting-frame to raise the condenser-evaporator (so as to again commence the heating operation), such mo vement will be prevented until sufiicient external heat has leaked into the storage-chamber to melt the ice in the cup 61, thereby releasing the stud 60 and permit-ting the apparatus to rock back to its original position, as shown in Fig. 1.

Upon the occurrence of this movement there may remain in the condenser-evaporator a small amount of liquid, consisting of condensed watervap0r from the generatorabsorber mixed with liquid ammonia; but such liquid, when present, will be in the lower corner of the header 25, whence it will flow by gravity through the return pipe 27,

'be noted, approximately directly over the pivot 8; hence as the frame rocks, the elevation of this point does not appreciably change. When, however, the apparatus is and the pipes 54 and 57, back into the lower and baflies.

in the position shown in Fig. 1, the pipe 27 j slopes downwardly to the left, andhence liquid can drain by gravity.

' During the condensation stage the con-.

the-condenser-evaporator in the condensing stage rises to the top of the chamber and stays there excepting the small quantity leaking out through theaperture. It is impossible for convectioncurrents to beset up between the lower part of the storage cham- The hot air which surrounds her and the topof the partition 65. This follows from thefact that the hot air in the chamber 'is unable to drop down and mix with the. cold air. Hence, the hot condenser has no appreciable effect on the temperature of the storage chamber, neither doesit vaporize the water extracted by the cold evaporator; On the lowering of the condenser-evaporator, and the chilling of the surroundings upon the evaporation of the refrigerant, the cold air is able to drop down from the condenser-evaporator and set up the air currents indicated in Figs. 2, 3 and 4.

If for any reason during the heating of the solution in the generator-absorber the condensing-tubes 22 should become filled too full of liquid refrigerant (so as to tend to cause a dangerously high pressure within the system), the refrigerant liquid would everflow from the upper end of the tubes 22 into the header 25, whence it would flow,-as just described, back into the generator-absorber 10. As additional vapor is generated in the generator-absorber and passes into the condenser-evaporator to be liquefied, an equivalent amount of the liquid .o-verflows into the header and flows'back (as before) into the lower part of the generator-absorber. So that a condition of equilibrium would soon be reached, under which a stream of vapor the scope of the invention as defined bythe annexed claims. The invention having been thus fully described, what is claimed is:

- 1. A refrigerating apparatus of the intermittent absorption type, comprising a rocking frame carrying upon its opposite arn'is two containers, the one a generator-absorbor and the other a condenser-evaporator, and means associated with the containers and frame whereby a refrigerating cycle maybe performed, said means "including av casing moving with said frame and having an in-.

let and an outlet, and containing enough mercury ,to seal said outlet in oneposition only of said frame andcasing while leaving it free in the other position, the mouth of said inlet being at all times above'the level of the mercury. I i i 2. A refrigerating apparatusof the intermittent absorption type, comprising a rocking .frame' carrying upon its opposite arms two containers, the one a generator-absorber and the other a condenser-evaporator, and means associated with the containers and frame whereby a refrigerating cycle may be performed, said means including an approximately horizontal casing carried by the rocking-frame and elongated in a direction transverse to the pivot of the frame, an outlet-pipe passing through the roof of the casing to the condenser-absorber and having its mouth located within the casing in proxlmity to its floor and nearer that end thereof leaves the top of the generator-absorber,

while its place is being constantly supplied by an equivalent stream of liquid flowing back into the bottom of said generatorabsorber. Inasmuch as high pressure willattend the filling of the condenser-evaporator with liquid, this arrangement places a definite limit to the high pressure.

While the preferred embodiment ofthe invention has been described with great detail, it is. to be understood that this is for the sake of clearness only, and doesnot limit which :becomes thev relatively lower end when,

the frame has been rockedinto absorptionposition, an inlet-pipe passing from the generator-absorber through the fioor of said casing and having its mouth'located within the casing substantially above said floor, and Within said casing a body of mercury whose level is always below said inlet-mouth in'either position of the'rockingframe and casing, said body of-mercury being enough to seal said outlet-mouth so long only as the absorber is in its elevated absorption-position witlrsaid outlet-mouth relatively lowered,said mercury leaving said outlet-mouth 1 free in the other position.

8. In a refrigerating apparatus of the in-- termittent absorption type, the combination with a rocking-frame, of a generator-absorber on one arm thereof and a condenserevaporator on the other arm thereof, 3. casing between and connecting ,said generatorabsorber and condenser-evaporator and moving with said frame, said casing 'havin an inlet and outlet projecting therein an containing sufficient fluid to seal the outlet in one position of the frame while leaving it free'in the other position, the mouth of the inlet being at all times free ofand-above the-level of the fluid in the casing.

4. In a refrigerating apparatus of the intermittent absorption type, the ebmbination with a rocking-frame, of e generator-ab sorber and condenser-evaperator at bpposite ends thereof, a casing having fluid therein 5 and moving wlth-sald frame, said casing being interposed between said generator-absorber and condenser-evaporator, conduits extending from said generatonabsorber and condenser-evaporator and terminating in said casing, one of said conduits being immersed in the fluid in one position of the frame and free'of 'said fluid in the other position, and the other condfiit being at all

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