US2133954A - Refrigerating apparatus - Google Patents

Description

Oct. 25, 1938.- B. M. BUCHANAN REFRIGERATING APPARATUS Filed June 26, 1936 INVENTOR F 'a' Lssu: B.M.BucHn-/a-.

BY 7/ ATTORN Y WIT ESSES:

Patented Oct. 25, 1938 BEFBIGEBATIN G APPARATUS Leslie B. M. Buchanan, Springfield, Mala, as slgnor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., acorporation of Pennsylvania Application June 2c, 1936, Serial No. 81,424

19 Claims.

My invention relates to refrigerating apparatus of the type employing a plurality of'evaporator elements operated at dlflerent mean temperatures and has for an object to provide improved apparatus of this character.

A further object of the invention is to'provide I an improved domestic type refrigerator and method of refrigeration wherein fluids may be more rapidly congealed than in prior apparatus of this kind.

A still further object of the invention is to effect quick freezing of water or other fluids in a conventional refrigerator cabinet without depressing the temperature of the food storage com- 16 partment to an undesirable degree and without excessively dehydrating the air therein.

A further object of my invention is to refrigerate one element of. a refrigerating system to a relatively low temperature, prior to the refrigera- 20 tion of a second element at a higher temperature during each cycle of the system.

These and other objects are eifected by my in- :vention, as will be apparent from the following description and claims taken in connection with '25 the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a sectional view of a portion of a domestic refrigerator having my improved refrigerating apparatus applied thereto; 30 Fig. 2 is aview of a detail of Fig. 1 shown in a diii'erent operating position;

Fig. 3 is a section of the detail shown in Fig.2 and is taken along the line III--III of Fig. 1; and, Fig. 4 is a modified view of some of the details 35 shown in Fig. 1.

In prior refrigerating machines of the domestic type having a food storagecompartment and a common evaporator therein for cooling the air in the compartment and for freezing fluids, quick 40 freezing of the latter without excessively dehumidifying and cooling the air in the compartment has been difllcult. If the temperature of the evaporator is maintained at a desirable value for cooling the food in the compartment. then con- 45 gealing'of fluids is slow and, if the temperature of the evaporator is lowered to eii'ect quick congelatlon, then excessive cooling of the food and' dehydration of the same is experienced.

To obviate this undesirable condition, it has 50 been proposed to supply different compartments I for food cooling and for congealing of fluids or freezing of water. Separate evaporator elements are provided for the respective compartments, which evaporators operate at different tempera- 55 tures suitable for these purposes. construc- (Cllit-4) tion, while effective, is expensive. My invention may be applied to-a cabinet construction such as this, but may'a'lso be applied to the less expensive type of construction wherein a single insulated food storage compartment is employed 5 with a unitary refrigerating element for effecting the refrigeration of both the food products and the fluid to be congealed.

In practicing my invention, an evaporator structure may be disposed in a single compart- 10 ment of the refrigerator which structure may take the outward appearance of a conventional evaporator. The walls of the evaporator structure and freezing trays define relatively high and low temperature evaporator elements. The walls are arranged in heat exchanging relation with the air in the compartment and the shelves are disposed within the walls and are shielded thereby from the air within the compartment.

In accordance with my invention, a conventional refrigerant condensing unit circulates refrigerant through the evaporating elements, preferably in series, so that refrigerant flows through the shelves and thence through the walls. Va-

porized refrlgerantiis withdrawn from the walls.

A reservoir for the storage of condensed refrigerant is connected to the shelves and walls,'preferably between these elements. The purpose of the reservoir is to store more or less condensed refrigerant, so that it may or may not be delivso ered to the wall members for vaporization therein. A thermostatically operated device responsive to the temperature of the refrigerant d'elivered to the reservoir by the shelves or low temperature' evaporator element, controls the storage of refrigerant in the reservoir.

The circulation of refrigerant is preferably controlled in response to the temperature of the walls or high temperature element. When the walls attain a predetermined high temperature, 40 refrigerant is delivered to the shelves and thence to the reservoir. At this time, refrigerant is stored in the reservoir due to the relatively high temperature of the refrigerant therein. so that no refrigerant is delivered for vaporization in the wall members. when the shelves are depressed to a low temperature. the, thermostatic control in the reservoir discharges the stored refrigerant, to the walls for vaporization therein. As the temperature of the latter is depressedfto the desired value, thecondensin'g unit is stopped and refrigeration of both elements is terminated.

During the inactive periods of the condensing unit, the thermostatic device in the reservoir operates at a predetermined temperature to condition the reservoir for storage of refrigerant therein. Thereafter, when the condensing unit is started at a predetermined higher temperature, the cycle is repeated. Accordingly, when the condensing unit starts, the shelves are first refrigerated to a relatively low temperature and, thereafter, the walls are refrigerated to a relatively higher temperature.

Reference will now be had to Fig. 1 of the drawing which discloses refrigerating apparatus constructed in accordance with one form of my invention applied to a conventional cabinet ||l having a compartment for the storage of articles to be refrigerated. A refrigerant evaporating structure, generally indicated at I2, is disposed within the compartment for cooling the air therein and for fluid congealing purposes such as, for example, the freezing of water. The structure |2 includes side walls l3 and I4 that are provided with spaces l5 and I6, respectively, for refrigerant. A bottom wall |1 connects the bottoms of the side walls l3 and I4 and may or may not be refrigerated. A passage IB is disclosed in the bottom wall H for conducting refrigerant from the wall |3 to the wall M. The upper portion of the wall |4 includes a header l9 from which refrigerant vaporized in the structure I2 is withdrawn.

The evaporating structure |2 may be suspended in the compartment preferably by extensions 20 of the Walls l3 and H. The side and bottom walls define a chamber 2| therebetween which may be closed at the back by a rear wall 22. The rear wall 22-is connected to the side walls l3 and I4 and preferably extends from the bottom wall H to the top of the extensions 20.

The front of the chamber 2| may be closed by a door (not shown) in a well understood manner.

Arranged within the chamber 2| are shelves 23 and 24 having respective passages 25 and 26 formed therein for refrigerant. A conduit 21 is employed for conducting condensed refrigerant to the shelf passage 25 and a conduit 28 provides communication between the shelf passages 25 and 26. These connections provide for series flow of refrigerant through the shelves 23 and 24, but it will be understood that other methods of conducting refrigerant through the shelves may be employed. Trays 29 may be supported by the shelves for the fluid to be congealed or frozen.

The walls l3 and I4 define an evaporating element that is maintained at a mean temperature suitable for refrigerating the air within the compartment to a temperature value that is optimum for the storage of food. This value is sumciently low for proper cooling of the air and high enough to prevent excessive dehydration thereof. The shelves 23 and 24 define an evaporating element that is maintained at a lower mean temperature than the walls l3 and I4, so that faster freezing of fluid in the'trays 29 is obtained than would be obtained at the higher mean wall temperature.

and walls of the evaporating structure |2 by any suitable refrigerating machine such as, for example, a hermetically sealed mot r driven compressor mechanism 3|. The mechanism 3| withdraws vaporized refrigerant from the header l9 through a conduit 32 and compresses it to a relatively high value for delivery through a conduit 33 to a condenser shown diagrammatically at 34. Cooling of the condenser 34 is effected in any suitable manner for lique'fying the compressed vapor. Condensed refrigerant is delivered to the conduit 21 through a suitable pressure reducing device such as a conventional high side float valve 35. The operation of a system of the compressor-condenser-expander cycle is well known and no'description thereof is deemed necessary. e

The motor compressor mechanism 3| is energized by electrical line conductors L1 and La controlled by a thermostatic switch 36 preferably responsive to the temperature of the wall I4. I disclose a thermostatic switch 36 of the expansible gas type, but it will be understood any suitable thermostatically operated switch may be employed. As shown, the switch 36 includes a temperature-responsive element 31 secured to the wall |4 adjacent the header [9. As the operation of gas type thermostatic switches is well known, no detailed description of the operation will be given other than to state that the switch is closed at a relatively high temperature of the wall l4 and is opened at a relatively low temperature thereof.

In accordance with my invention, means are provided for reducing the temperature of the shelves 23 and 24 to a relatively low degree each time the compressor mechanism 3| is operated to effect cooling of the walls I3 and I4 and, therefore, the air within the compartment II. This operation is effected by, first, evaporating refrigerant in the shelves and. subsequently, effecting evaporation in the walls.

The means for accomplishing this operation includes a structure 40 that defines a reservoir 4| for storing variable quantities of condensed refrigerant (Figs. 1 to 3, inclusive). A conduit 42 is provided for conducting condensed and vaporous refrigerant from the shelf passage 28 to the reservoir 4| and a second conduit 43 provides communication between the reservoir 4| and the passage |5 of the wall l3. The latter conduit 43 defines an overflow device and may extend upwardly in the reservoir a predetermined distance for determining the maximum depth and quantity of refrigerant to be stored therein, as shown in Fig. 1.

An inverted cup 44 is disposed coaxially with the conduit in telescopic relation and is supported by a thermostatic member or disc 45. The latter may be of bi-metal construction with the high expansive metal on top, so that, when it is relatively warm, it is in the position shown in Fig. 1, and, when cooled, it snaps to a position in which it is curved in the opposite direction to that shown. Accordingly, the cup 44 is lowered into the refrigerant as shown in Fig. 2, whereby the depth and quantity of the refrigerant in the reservoir 4| is reduced as described hereinafter. The disc 45 may be supported in any suitable manner as by lugs 45 formed within the reservoir structure 40.

The discharge end of the conduit 42 is disposed adjacent the thermostatic disc 45 whereby refrigerant entering the reservoir structure 4|! flows in heat-exchanging relation over the disc 45 and then drops to the reservoir 4 The disc 45, therefore, is operated in response-to the temperature of the refrigerant entering the reservoir. 4|.

I tively small, the amount of heat abstracted from When this temperature is at a relatively high value, the disc 45' is in its upper position and the maximum quantity of refrigerant, as determined by the elevation of the open end of the overflow conduit 43, is stored in the reservoir 4|. When the temperature of the refrigerant entering the reservoir 4| is at a relatively low value, the disc 45 snaps downwardly to the position shown in Fig. 2 and the cup assumes a lowered position in which it is telescoped with the conduit 43. As the cup 44 is of larger inside diameter than the outside diameter of the conduit 43, an annular passage is defined therebetween, which passage provides communication between the reservoir 4| and the conduit 43.

The conduit 43 is connected to the suction of the compressor unit 3| through the walls l3 and I4, so that a lower-pressure prevails in the conduit 43 than in the reservoir 4|. Condensed refrigerant will, therefore, rise in the annular passage between the cup 44 and the conduit 43 and overflow into the latter until the level of the condensed refrigerant in the reservoir 4| is depressed slightly below the bottom of-the cup. This level determines the minimum depth and quantity of refrigerant stored in the reservoir 4|. At this time, the walls l3 and H are filled with refrigerant, the level of which is indicated by the dot and dash line in the header IS. (Fig. 1.)

When the maximum quantity of refrigerant is stored in the reservoir (Fig. 1) the walls l3 are devoid, substantially, of condensed refrigerant so that evaporation is efiected only within the shelves 23 and 24. When the reservoir contains its minimum quantity of refrigerant, the walls l3 and I4 contain condensed refrigerant in an amount represented by the difference in quantities of refrigerant stored by the reservoir and evaporation at this time is eifected in the wall members l3 and I4.

Operation closes for initiating operation of the motor compressor unit 3|.

Condensed refrigerant from the condenser passes to the shelves 23 and 24 through the float valve 35 and is vaporized in the shelves for abstracting heat from the material in the trays 29 in a well understood manner. Excess condensed refrigerant passed to the shelves, of course, passes through conduit 42 and, after contacting the disc.

45, collects in the reservoir 4|. Vaporous refrigerant from the shelf passages 25 and 26 passes through the conduit 42, the reservoir structure 40,

conduit 43, passages |3 .|8 and I6 of the walls to the header I9 and thence to the compressor unit 3| through conduit 32. Refrigeration is now effected in the shelf passages .25 and 26 by evaporation and no cooling is eifected by-evaporation in the wall passages l5 and I8. Some cooling of the walls l3 and I4 will befleflected but it is relathe walls being only that added to therei'rigerant vapor as superheat. j

Some evaporation is effected in the reservoir structure 40, but this may be reduced by covering the structure with heat insulation (not shown). I In any event, the cooling efiect of the evaporation in the reservoir 4| is confined to the air in the chamber 2| containing the trays 29. I

During this operation, the temperature of the shelves 23 and 25 is depressed with little reduction in temperature of the walls l3 and I4. As the temperature of the refrigerant contacting the bimetal disc 45 reaches a. low value of 10 degrees, for example, the disc 45 and cup 44 snap downwardly, as shown in Fig. 2, the refrigerant level in the reservoir descends; the outflowing condensed refrigerant filling the wall passages l5 and IE to a level shown in dotted lines in the header l9. Evaporation is immediately effected in the wall passages l5 and I6 for cooling the air in the food compartment As refrigeration of the walls is initiated, the pressure-and temperature of the refrigerant in the low side of the system rises due to the rapid evaporation obtaining in the wall passages; Ac-' cordingly, as the walls are cooled, the temperature of the refrigerant in the shelves rises to a storage of refrigerant when operation of the compressor unit 3| is started, which operation is effected when the temperature; of the wall |4 rises to 29 degrees. 1

From the foregoing, it will be apparent that the shelves are operated at a lower mean temperature than the wall members; the former operating in the example recited between 29 degrees and 10 degrees and the wall members between 29 degrees and 16 degrees. By reducing the shelves .to-the relative low temperature of 10'- degrees each time the system is cycled, fast freezing or congelation of substances in the trays is effected. As the walls are operated at a higher minimum temperature or 16 degrees, and since. the walls shield the shelves, it will be apparent less dehydration of 'the air in the compartment is obtained in my system than in conventional systems wherein the walls and shelves 'are operated at substantially the same lower temperatures.

Fig. 4 discloses a-second embodimentof the arrangement of the reservoir in the evaporator snaps upwardly to condition the reservoir for I structure. In this embodiment, the separate reservoir structure 4.0 of Fig. 1 is replacedby a structum-5t formed at the top of the wall |3.- The operation of the two embodiments is similar so that no further description is necessary and parts which may be common to both are indicated by like numerals in bothiflgures of the -drawing.

In Fig. 4, however, -I have shown heat insulation 5| disposed on the side of the reservoir 5 that is exposed to the air in the compartment H. The insulation is employed forvrestrictingithe flow of heat to the reservoir structure 50 from the air in the compartment I during periods when the shelves onlyare refrigerated, at which time the reservoir structure 50 would assume, substantially, the

relatively low temperature of the she was I lie I have disclosed my improved apparatus including a structure wherein the low temperature evaporating element is within and shielded by the higher temperature element,- it is tobe understood that these elements may be separated or disposed in separated compartments without departing from the spirit and scope of my invention.

While I have shown my invention in but two forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be plaeedthereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. In refrigerating apparatus, the combination of first and second evaporating elements, means for condensing refrigerant vaporized in said elements, means for conveying liquid refrigerant of refrigerant condensing means, an evaporator structure having first and second evaporating elements, means for conveying the condensed refrigerant to said evaporator structure, a reservoir for condensed refrigerant, and a thermostatically operated device arranged within the reservoir for varying the supply of refrigerant therein and movable, to a first position, wherein a relatively large amount of condensed-refrigerant isstored in the reservoir and substantially no condensed refrigerant is delivered to the second evaporating element and movable, to a second position, wherein a relatively small amount of refrigerant is stored in the reservoir and condensed refrigerant is delivered to both of said evaporating elements.

3. In a refrigerating systempthe combination of refrigerant-condensing means, an evaporator structure having first and second evaporating elements, means for conveying the condensed refrigerant to said evaporator structure, a reservoir carried by said evaporator structure for storing condensed refrigerant therein, a device disposed within the, reservoir for controlling the storage of refrigerant therein, thermostatically-operated means responsive to the temperature of the refrigerant in the reservoir for actuating said device to a first position, wherein condensed refrig- I erant is, stored in the reservoir and substantially no condensed refrigerant is delivered to said secnd evaporating element, and movable to a second I position,- wherein condensed refrigerant is discharged from the reservoir and is delivered to both of said evaporating elements, and means responsive to the temperature of thesecond evaporating element for-controlling the operation of the refrigerant condensing means.

4. In a refrigerating system, the combination of refrigerant condensingmesns, first and second refrigerant evaporating elements, means for conveying condensed refrigerant from the condensing means to said evaporating elements so that it flows to the first evaporating element in preference to the second evaporating element, a

reservoir for condensed refrigerant; thermostatic means responsive-to the temperature of the refrigerant in the reservoir for controlling the storage of condensed refrigerant therein, said thermostatic means being movable to a first position wherein condensed refrigerant collects in the reservoir and substantially no condensed re- 1 frigerant is delivered to the second evaporatingelement, said thermostatic means being movable to a second position wherein condensed refrigerant is passed through the reservoir to the second element for vaporization therein, and means I responsive to the temperature of the second ele ment for controlling the operation of the refrigerant condensing means.

5. In a refrigerating system, the combination of refrigerant condensing means, first and second refrigerant evaporating elements, means for consaid first-and second elements, a reservoir for condensed refrigerant disposed between said first and second elements, and a thermostatic device responsive to the temperature of the refrigerant entering the reservoir for .controlling the storage of refrigerant therein, said device being movable to a first position in response to a relatively high temperature for effecting storage of condensed refrigerant in the reservoir with substantially nocondensed refrigerant being delivered to the second evaporating element and movable to a second positionin response to a relatively low temperature for. passing condensed refrigerant through the reservoir to said second element for vaporization therein.

6. In. a refrigerating system, the combination of refrigerant condensing means, an evaporator structure including side wall members and shelves disposed therebetween, said sidewalls and shelves defining a pair of evaporating elements, a reserfrigerant entering the reservoir fromthe shelves and movable to a flrstposition in-response to a relatively high temperature of the refrigerant for effecting storage of refrigerant in the reservoir with substantially no condensed refrigerant being delivered to the sidewalls, and being movable to a second position in response to a relatively low temperature densed refrigerant to the sidewalls for vaporization therein.

.veying condensed refrigerant serially through of the refrigerant for passing con- '7. In a refrigerating system, the combination of refrigerant condensing means, an evaporator structure having first and second evaporating elements and a reservoir for the storage of condensed refrigerant, means for conveying condensed refrigerant from the condensing means through said first evaporating element, the reservoir, and the second evaporating elementin the order named, a thermostatically-operated device arranged within the reservoir for controlling the storage of condensed refrigerant therein and disposed in heat exchanging relation with the refrigerant entering the reservoir from the first evaporating element, said device being movable to a first-position in response to a relatively high temperature for effecting the storage of condensed refrigerant in the reservoir with substantially no condensed refrigerant being delivered through the reservoir to said second evaporating element for vaporization therein.

8. In refrigerating apparatus, the combination of refrigerant condensing means, first and second refrigerant evaporating elements, a reservoir for condensed refrigerant, means for conveying condensed refrigerant in series through said first element, the reservoir and said second element in the order named, means for conveying vaporized refrigerant from the second evaporating element to the condensing means, a thermostatically operated device responsive to the temperature of the refrigerant within the reservoir for controlling the storage of refrigerant therein, said device being responsive to a predetermined relatively high temperature for effecting storage of condensed refrigerant ln'the reservoir with substantially no condensed refrigerant being delivered to the second evaporating-element and being responsive to a predetermined relatively low temperature for effecting passage of condensed refrigerant through the reservoir to the second evapcrating element for vaporization therein.

"9. In refrigerating apparatus, the combination of a cabinet structure having a compartment therein, a plurality of wall members defining a refrigerant evaporating element and disposed in heat exchanging relation with the air in said compartment, a shelf disposed within said. wall members and defining a second evaporating element disposed within said wall members for congealing fiuids, means defining a chamber for storing condensed refrigerant, means for withdrawing vaporized refrigerant from said wall members, means for condensing the withdrawn refrigerant and for translating it in series through said shelf, the chamber and said wall members in the order named, thermostatically operated means disposed within said chamber in heat exchanging relation with the refrigerant contained therein for controlling the storage of refrigerant in the chamber, said thermostatically operated means being responsive to a .predetermined relative1y-high temperature for effecting storage of liquid refrigerant so. that substantially no liquid refrigerant is delivered to the wall members and being responsive to a relatively low temperature for passing liquid refrigerantthrough the chamber to said wall members for evaporation therein, and means responsive to the temperature of the wall members for controlling the operation of the condensing means.

10. In refrigerating apparatus, the combination of a refrigerant circulating system in which variable quantities of refrigerant are to be circulated, a structure connected in said system and defining a reservoir for storing variable quantities of liquid refrigerant, means for admitting refrigerant to the reservoir, an outlet conduit extending upwardly in the reservoir and open at its top for defining the maximum depth of refrigerant to be stored, an inverted cup telescopically arranged with respect" to the conduit, a thermostatic member responsive to the temperature of the refrigerant in the reservoir for supporting said cup and having upper and lower positions, said member, in its upper position, maintaining the cup elevated with respect to the conduit whereby the maximum quantity of refrigerant, as

determined by the open top conduit, is stored in the reservoir and,in its lower position, maintaining 'the cup telescoped oh the conduit so that the lower edge of the cup defines a. lower level of refrigerant in the reservoir.

fying refrigerant for the'evaporating elements in response to a predetermined high temperature of the high temperature element, effecting refrigeration of the low temperature element each time the high temperature element calls for refrigeration, substantially reducing refrigeration of the low temperature element and effecting refrigeration of the high temperature element when the low temperature element issatisfied in response to a predetermined low temperature of the low temperature element, and stopping liquefaction of refrigerant when the high temperature element is satisfied in response to a predetermined low temperature of the high temperature element.

12. The method of cycling a refrigerating machine having relatively high and low temperature evaporating elements which comprisesliquefying refrigerant for the evaporating elements-in response to a predetermined high temperature of the high temperature element, effecting refrigeration of the low temperature element each time the high temperature element calls for refrigeration, 'substantiallyreducing refrigeration of the low temperature element-and effecting refrigeration of the high temperature element when the low temperature element is satisfied in response to a predetermined low temperature of the low temperature element, and stopping liquefaction of refrigerant, when the high temperature element is satisfied in response to a predetermined low temperature of thehigh temperature element, which latter low temperature is of a highenvalue than the low temperature in response to which re-' frigeration of. o the low temperature element is stopped.

13'. The method of-cycling a refrigerating ma- Ehine having first and second evaporating elements which comprises. periodically circulating liquid refrigerant to the elements, delivering a portion of the circulated refrigerant to one of said elementsfor vaporizationand withholding a second portion of the refrigerant from circulation each time the machine is started, and subsequently releasingsaid withheld'refrigerant to the second evaporating element for vaporization therein when the temperature of the first evaporating element has been depressed to a predetermined value.

14. The method of cycling a refrigerating machine having relatively high and low temperature evaporating elements which comprises liquefying refrigerant for the evaporating elements in response to a predetermined high temperature of the high temperature element, delivering a portion of the liquefied refrigerant for vaporization in the low temperature element and withholding from circulation.' a second portion of the liquefied refrigerant each time the machine is cycled, subsequently releasing said portion of perature of the high temperature element, which latter low temperature is of a higher .value than said temperature at which the withheld reirig erant is released.

1 5. In refrigerating apparatus, the combination of a c'abinetstructure, an evaporator disposed within the cabinet structure and embodying wall members and a shelf enclosed therebyg said wall members and shelf defining separate refrigerant. evaporating elements, a refrigerant condensing unit, means for periodically operating the condensing unit, and means for automatically efiecting, during each operation of the condensing unit, vaporization of refrigerant in said shelf at relatively vlow temperature and, thereafter, in the wall members at a relatively higher temperature.

16. In refrigerating apparatus, the combination of a cabinet having a cooling compartment therein, an evaporator structure disposed within said compartment and including a pair of spaced wall members and a shelf disposed therebetween, said wall members defining a relatively high temperature evaporating element for cooling the air in said compartment and said shelf defining a relatively low temperature evaporating element for congealing fluids, a refrigerant condensing unit, means for periodically effectingoperation of the condensing unit, and means automatically actuated each time the condensing unit is operated, for effecting vaporization of refrigerant first in the shelf and, subsequently, in the wall members.

17. In refrigerating apparatus, the combination of a cabinet structure, an evaporator disposed within the cabinet structure, said evaporator structure embodying wall'members defining a relatively high temperature evaporating element and a shelf enclosed by the wall members and defining a relatively lowtemperature evaporating element, a mechanism for condensing refrigerant evaporated in the high and low temperature evaporating elements, means responsive to the temperature of the high temperature evaporating element for effecting periodic operation of the refrigerant condensing mechanism, and means for automatically effecting, during each operation of the condensing mechanism, vaporareas ization of refrigerant in the low temperature element first and, thereafter, vaporization of refrigerant in the high temperature element.

18. In a refrigerating system the combination of first and second evaporating elements, means for supplying liquid refrigerant preferentially to the first element and secondarily to the second element, and means responsive to a relatively low temperature of the refrigerant dlscharged from the first evaporating element for admitting liquid refrigerant to said second evaporating element and responsive to a relatively high temperature for passing refrigerant vaporized in the first element to said second element.

19. In a refrigerating system, the combination of first and second evaporating elements, means for condensing refrigerant vaporized in said element, means for supplying the condensed refrigerant to the evaporating elements so that it flows into the first evaporating element until a predetermined amount is contained therein and thence into the second evaporating element, means for storing a predetermined quantity of condensed refrigerant in a portion of the system other than the second element, and a thermostatic device exposed to the refrigerant discharged from the first element for controlling the storage of refrigerant in said storing means, said device being responsive to a relatively high temperature of the refrigerant for effecting storage of refrigerant whereby condensed refrigerant is delivered to the first evaporator elementfor vaporization and being responsive to a relatively low temperature of the refrigerant for rendering the storing means ineffective to store said quantity of refrigerant whereby condensed refrigerant is delivered to the second evaporating element I for vaporization.

LESLIE M. BUCHANAN.

CERTIFICATE OF CORRECTION. Patent No 2,I 5,95b,. October 25, 19

' LESLIE B. M. BUCHANANO It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column, line 11, after the'syllable "wardly" and before the comma insert the word and; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case. in I the Patent Office.

Signed and sealed this 6th day of December, Aa D, 1958.

Henry Van Arsdale (Seal) Acting Comniissioher of Patents.

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