US2604761A

US2604761A - Two-temperature refrigerating system

Info

Publication number: US2604761A
Application number: US88708A
Authority: US
Inventors: Leonard W Atchison
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1949-04-21
Filing date: 1949-04-21
Publication date: 1952-07-29
Anticipated expiration: 1969-07-29

Description

Patented July 29, 1952 TWO-TEMPERATURE REFRIGERATING SYSTEM Leonard W. Atchison, Erie, Pa., assignor to General Electric Company, a. corporation of New York Application April 21, 1949, Serial No. 88,708

My invention relates to refrigerating systems and more particularly to refrigerating systems including a plurality of evaporators.

In many refrigerating systems it is desirable to employ a plurality of evaporators. For example, in combination refrigerators, which include a compartment for storing frozen food and a second compartment for storing fresh food, it may be necessary to provide two evaporators, one of which operates at a low temperaturefor refrigerating the frozen food compartment, and the other of which operates at a higher temperature for refrigerating the fresh food compartment. Where both evaporators are supplied with refrigerant from a common condensing unit, some arrangement may be utilized for selectively directing liquid refrigerant to one or the other of the evaporators. Also, it may be desirable in some instances to operate the higher temperature evaporator on a defrosting cycle so that any frost accumulated during the operating period of the higher temperature evaporator is melted and disposed of during the idle period of this evaporator.

Accordingly, it is an object of my invention to provide a refrigerating system including two evaporators and including an improved arrangement for directing refrigerant selectively to either evaporator.v

It is another object of my invention to provide an improved refrigerating system. including two evaporators operated at different temperatures and including an arrangement for making a substantial body of liquid refrigerant available to the higher temperature evaporator when refrigeration is called for by the higher temperature evaporator.

Further objects and advantages of my invention will become apparent as the following description proceeds and the.features of novelty which. characterize my invention will be pointed outwith particularlity in the claims annexed to. and forming; part of this specification.

In carrying out my invention a refrigerating system. is provided. which includes two. evaporators. A reservoir is provided for receiving 1 liquid refrigerant from the condensing. unit and discharging the refrigerant selectively to either evaporator. Where the two evaporators are operated at different temperatures, the conduits connecting the two evaporators to the reservoir are arranged so that a substantial body of liquid refrigerant is maintained in the reservoir during refrigeration of the low temperature evaporator and this refrigerant is immediately avail- 13 Claims. (01. 52-3) able for discharge to the higher temperature evaporator when that evaporator calls forrefrigeration. The vaporization of this body of liq'uid refrigerant in the higher temperature evaporator effects a rapid increase in the suction pressure of the system and hence the system rapidly reaches a more eflicient operating condition. during the time when refrigeration is supplied to the higher temperature evaporator. 4 A

For a better understanding of my invention reference may be had to the accompanyingdrawing in which Fig. l is a schematic illustration of av refrigerating system incorporating; my: invention; Fig. 2 shows a portion of the apparatus illustrated in Fig; 1 in a different positionyand Fig. 3 shows a modified form of a portionofthe refrigerating system; and Fig. 4 is a schematic illustration of a modified form of my invention.

Referring now to Figs. 1 and 2, there is illustrated a refrigerating system including a condensing unit I and two evaporators 2" and}. The condensing unit includes .a motor-compressor unit'positioned within. a hermetically-sealed case 4 and. a, condenser 5. Liquid refrigerant. is supplied from the condenser 5 through a restricted conduit, or capillary tube, 6.

In order to direct liquid refrigerant from:the condensing" unit selectively to either of the two evaporators. 2 and 3, an elongated reservoir lis provided. The conduit 6 is connected to' :the reservoir I at. the top central. portionthereofias indicated at 8. Refrigerantis supplied from: the reservoir 1 to the evaporator. 2 through. a: conduit 9, and refrigerant is similarly supplied. to'the evaporator 3v through a conduit ll]. As implied above, the term reservoir as used: in. this speci- 'fication and. the claims thereof is. intended. to

denote a storage container of appreciable size capable of storing a substantial body of refrigerant, and specifically capable of" storing suflicient liquid refrigerant to havea materialxeffect in rapidly raising the pressure of the higherutemperature evaporator when thisrefrigerant is discharged thereto. The specific manner' invwhich this is carried out. in the applicants: invention is pointed out in detail in-this: specification.

A common header II' is provided for the 'two evaporators 2 and 3'. The evaporator *Z i's connected to one end of the header: H by a conduit 12, the evaporator 3 is connected to the same end of the header by a conduit 13, these conduits primarily conducting vaporized refrigerant from the evaporators to the header. Vaporized refrigerant is discharged from the. header to the condensing unit I through a suction line I4 In order to minimize discharge of liquid refrigerant from the header I I to the compressor of the condensing unit I, a baffle I5 is provided within the header I I. To prevent reverse flow of refrigerant from the header I I to the evaporator 2 when the evaporator 3 is operating, a check valve I6 is provided in the conduit I2 between the evaporator 2 and the header I I.

In one application of this refrigerating system the evaporator 2 is operated at a low temperature, such as would be required for refrigerating a frozen food storage compartment, and the evaporator 3 is operated at a higher temperature,

1 such as would be required for refrigerating a fresh food storage compartment. By way of example, the evaporator 2 may be operated at a temperature in the neighborhood of 0 F., and the evaporator 3 may be operated over a temperature range from a minimum of 28 F. to a maximum of 35 F. The reservoir I is arranged to direct liquidrefrigerant from the condensing "unit. .to either the low'temperature evaporator 2 or the higher temperature evaporator 3. To accomplish this the reservoir I is pivotally supported at I! for movement "from the position shownin Fig. 1 tothe position shown in Fig, 2. In order to allow for-the above movement of the reservoir the conduits 6, 9, and IB-include flexible coiled portions I8, I 9, and 20, respectively. It

can be seen that when the reservoir occupies the position shown in Fig. 1, liquid refrigerant-is directed through the conduit 9 to the low temperature evaporator. 2. When the reservoir is tilted to the position shown in Fig. 2 liquid refrigerant is dircted'through the'conduit ID to the higher temperature evaporator 3.

" It'canbe seenby reference to Figs. 1 and 2 that when the reservoir '1 occupies the position shown in Fig. 1; liquid refrigerant is supplied through the conduit 9 and any flash vapor'in the reservoir I is passed through the conduit, I9 and the evaporator 3; when the reservoir'is in the position shown in Fig. 2, liquid refrigerant is'sup- 'plied to the evaporator 3 through the conduitIO and flash vapor passes through the conduit 9 and the evaporator 2. Thediameter and length of the conduits 9 and ID are chosen so that the pressure drop due to the flow of flash vapor through one conduit'is somewhat greaterv than the pressure drop due to the flow of liquid through the other.

Particularly, when the'liquid refrigerant is being supplied to the evaporator 3, it is im- 'portant that the resistance to passage of flash "vapor through the conduit 9 be greater than the resistance to the passage of liquid through the conduit I0, since the evaporator 2' operates at a somewhat lower temperature and pressure than the evaporator 3. I

r Axtension spring -2I' is connected to the free end of the reservoir I at 22-for normally biasing the'reservoir to the position shownin Fig. 1. In orderto shift the reservoir to; the position shown in-Fig. 2 when refrigeration is required by the higher temperature'evaporator 3, a solenoid 23 is'provided. This solenoid actuates an armature 24, which is hinged at 25 .to the reservoir, to move the reservoir to the position shown in Fig. 2.

evaporator 3 reaches a predetermined maximum temperature which causes an expansion of the bellows 28 to close the contacts 29, the solenoid 23 is energized and moves the reservoir I to the position shown in Fig. 2 to direct liquid refrigerant from the reservoir to the evapoator 3.

The operation of the motor-compressor unit within the case i is controlled bya temperatureresponsive bulb 32 which is positioned in contact with the low temperature evaporator 2. The bulb 32 is connected by a tube 33 to a bellows 34. The" expansion and contraction of the bellows closes and opens a circuit from the power lines 30, ii through contacts 35 to the motor of the motorcompressor unit. Hence, when the temperature of the evaporator 2 reaches a predetermined maximum the expansion of the bellows 34 under the control of the temperature-responsive bulb 32 closes the circuit to the motor to start operation of the condensing unit. Conversely, when the temperature of the evaporator 2 reaches a predetermined minimum, the circuit of the motor is interrupted to stop the operation of the condensing unit.

In order to operate the systemgmore efficiently, it is desirable to have a higher suction pressure during the time when the higher temperature evaporator is being refrigerated. Should the condensing apparatus withdraw refrigerant from the higher temperature evaporator at the same low pressure as is utilized for operating the low temperature evaporator 2, there would be a considerable sacrifice in emciency. In order to raise the suction pressure rapidlywhen refrigeration is shifted to the higher temperature evaporator 3, a particular arrangement of the conduits 9 and ID with respect to the reservoir 1 is provided. Thus, the conduit 9, which supplies liquid refrig" erant from the reservoir to the low temperature evaporator 2,is connected to the reservoir in the upper portion of one end. It can be seen by referring to Fig. 1 that this arrangement of the conduit 9 in communication with the reservoir 1 causes a substantial body of liquid refrigerant 36 to be retained within the reservoir during refrigeration of the low temperature evaporator. 0n the other hand, the conduit I0, through which liquid refrigerant is suplied from the reservoir. T to the evaporator 3, is connected to the reservoir in the lower portion thereof at the opposite end from the conduit 9. Therefore, when the reservoir is tilted to the position shown in Fig. 2, the body of liquid refrigerant 35 immediately becomes available for discharge to the higher temperature evaporator 3. The vaporization of this substantial body of liquid refrigerant in the evaporator 3 causes a rapid increase in the suction pressure and hence the system rapidly begins operation at the more efficient higher pressure. In the absence of the arrangement described above there would at best be a delay in achieving an increased suction pressure during the refrigeration by evaporator 3, and hence there would be an unnecessarily low efficiency at least during this period of delay.

In order to avoid the necessity of defrosting the fresh food evaporator 3. it may be desirable to operate this evaporator on a defrosting cycle. To accomplish this, the evaporator 3 may be operated over a temperature range above and below the freezing point of water such that any frost collecting during the time that the evaporator 3 is refrigerating is melted and dissipated during the time that the evaporator 3 is not refrigerating. For example, this evaporator might "beoperated overalrange of temperatures from'a minimum of 28 F to a maximum oft 5 .In Fig. 3 there ;is shown a modifiedrf-ormof a .portion ofthe trefrigeratingxsystem in which a rearrangement of the connectionof "the conduit 12 to .the header H is utilized to eliminate the check valve It. lEn this modification the conduit :2 isconnected in communication with the header 'H .at the bottom portion. thereof :sothat the :mouth 3'! of :the conduit 12 isiocatedhelow the level .38 .ofiliquidirefrigerant normally presentin theheader I l. Liquidtrefrigerant isz-forced from the header H :into -the evaporatortZ, but

since there is no pressure difference between the two evaporators in the form shown in Fig. :3.

The operation of the refrigerating systeinmay be summarized as follows. When the low temperature evaporator :2 reaches a predetermined maximum temperature, the condensing unit is started in operation by the. closing of the contacts 35. Liquid refrigerant is supplied through the capillary tube '6 to the reservoir'l. The reservoir I is normally-biased by the spring 2! to the tilted position shown in Fig. 1. Hence, assuming the evaporator 3 is below its predetermined maximum temperature, liquid refrigerant is supplied through the conduit 9 to the low temperature evaporator 2.

reservoir because of "the positioning of the con- 'd'uit S in communication with the reservoir at the upper portion of one end. Should the higher temperature evaporator 3 mined maximum temperature, the solenoid 23 is energized by the closing of the contacts '29 and the reservoir is tilted to the position shown in Fig. 2. In this position liquid refrigerant is supplied to the higher temperature evaporator 3. Also, the substantial body of liquid refrigerant 36 retained in the reservoir during "the operation of the low temperature evaporator 2 is immediately made available for the higher temperature evaporator 3 and is enabled to discharge to that evaporator because of the positioning of the conduit :0 in communication with the reser voir l at the lower portion o'f the reservoir. This supplying of a substantial 'bodyof liquidrefrigerant to the higher temperature evaporator 3 results in a rapid increase in the suction line pressure because of the vaporization of this refrigerant, and hence the refrigerating system rapidly begins to operate at a higher-efiiciency. During the operation of the higher temperature evaporator 3 vaporized refrigerant is prevented from backing up into the evaporatori through the conduit l2 either by the use of the check valve i6 or by connecting the conduit I2 to the header H beneath the normal level-of the liquid refrigerant therein.

In the modification shown in Fig. 4a solenoid valve arrangement is utilized in lieu 'of the tilting reservoir for selectively directing liquid refrigerant either to the low temperature evaporator 2 or to the higher temperature evaporator 3. The same numerals have-been used to designate corresponding parts in Figs. 1 and 4. Referring to Fig. 4, there is shown a solenoid-operated valve 39 whichin'oludes-a housing 40. .A partition 4| During this time a. body of liquid refrigerant 36 is retained in the reach its prede'terl conduit 16.. 'rected from the housing :41] either through the -:is"formedwithin the housing and this partition includes a valve seat 42 against which onewen'd -P5.3..0f 2.2'd011b16-6I1d6d valve element. may :be seated. .The housing 4!] further includes a sec- :ond valve seat "4'5 against which the other end 46 :of the td-ouble-ended'valve element 44 is adapted to seat. Liquid refrigerant is supplied to the housing 49 from the condensing -;unit through a ,"Liquidrefrigerant .is selectively dicondu'it 9 :to the .low temperature evaporator 2 or through thexconduit 10 to the :higher temperature evaporator 13.

?T0 cnntrol theiflow of refrigerant to the evaporators .2..and 31117118 valve element M is provided, and this :valve element is operated by a solenoid 41.

Whenthe ssolenoid x4! is energized it acts upon an armature 48 to lift the valve element 44 tosthe'position shown in Fig. 4 wherein liquid refrigerant is supplied through the conduit it to the evaporator 3 and flow of liquid refrigerant to the evaporatorZ isblockedby the engagement of :the .end 43 of the valve element 44 with the seat 42. When the solenoid 4! is deenergized, the valve element 44 falls by gravity into engagement with the seat 45 to block the'ilow of liquid refrigerant to the evaporatorS and at the same time to disengage the valve element from the seat 42 directing the refrigerant through the conduit 9 to the evaporator 2. The housing ti], or at least :a portion thereof adjacent thesolenoid 4'! .and the armature t8, is made of a nonmagnetic material.

As in the form previously described, a temperature-responsive bulb at is provided in contact with the evaporator'fi and this bulb is 'connected by the tube Z'l to the bellows 28. When the evaporator 3 reaches a predetermined maximum temperature, the bellows 28 expands to close the circuit to :the solenoid from the power lines 3i}; 3! through the contacts 29. This causes the lifting. of the valve element '54 to the position shown .inFig. 4 and the supplying of liquid refrigerant to thehigher temperature evaporator 3. When the evaporator .3 reaches a predetermined minimum temperature the circuit of the solenoid is interrupted by the contraction of the bellows 12:8 and the valve element 44 falls by gravity :into engagement with the valve seat 45,

blocking the flow of refrigerant to the higher temperature evaporator 3 and opening a path for flow of refrigerant past the valve seat and through the conduit 9 to the low temperature evaporator 2. The-starting. and stoppingof the motor compressor .unit .(not shown) may be controlled by a bulb "responsive to the temperature of the evaporator 2, as;in the form shown in Figs. 1 and 2.

inorder to make a body of liquid refrigerant available for discharge to the higher temperatureevaporatoras soonas the higher temperature evaporator calls for refrigeration, so that the system 'refrigerates the higher temperature evaporator at a higher efficiency, the housing 40 includes a reservoir 49 .at the lower portionthereof. "The conduit-1 5! is connected in communication with the reservoir ltil at the bottom of this reservoir. On the other hand, the conduit 9, through which liquid refrigerant 'is supplied to the low temperature evaporator, is positioned in c'ommunicationrwith the housing i!!- at the top of the reservoir. 49. It can be seen that when the valve elementsll is in its lower position the liquid refrigerant in the housing'dii must rise in the reservoir 49 to the level of the conduit 9 before liquid refrigerant can be supplied at the low temperature evaporator 2. Thus, a substantial body-of liquid refrigerant is maintained in the reservoir t9 while the low temperature evaporator is being refrigerated. When the higher temperature evaporator calls for refrigeration and hence when the valve element 44 is shifted to the position shown in Fig. 4, this body of liquid refrigerant within the reservoir 49 is immediately made available for discharge to the higher temperature evaporator 3. The vaporization of this substantial body of liquid refrigerant in the evaporator 3 causes a rapid increase in the suction pressure and hence the system rapidly begins to operate at the increased efficiency resulting from operation at a higher suction pressure, in the same manner as previously described in connection with Figs. 1 and 2.

While I have shown and described specific embodiments of my invention, I do not desire my invention to be limited to the particular constructions shown and described, and I intend by the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A refrigerating system comprising a condensing unit, a low temperature evaporator, a higher temperature evaporator and a tiltable reservoir connected in a closed refrigerant circuit, means for conducting liquid refrigerant from said condensing unit to said reservoir, means connected to the upper portion of said reservoir for conducting liquid refrigerant from said reservoir to said low temperature evaporator, and means connected to the lower portion of said reservoir for conducting liquid refrigerant from said reservoir to said higher tem perature evaporator, said reservoir being tilted in one direction for directing liquid refrigerant from said reservoir to said low temperature evaporator, sad reservoir being tilted in the opposite direction for directing liquid refrigenant from said reservoir to said higher temperature evaporator, said connecting means providing for retention of a substantial body of refrigerant in said reservoir when said reservoir is tilted in said one direction and making said substantial body of liquid refrigerant immediately avai1- able to said higher temperature evaporator when said reservoir is tilted in said opposite direction.

2. A refrigerating system comprising a condensing unit, a low temperature evaporator, a

higher temperature evaporator and a reservoir connected in a closed refrigerant circuit, means for conducting liquid refrigerant from said condensing unit to said reservoir, means for directing liquid refrigerant from said reservoir selectively to either of said evaporators, means communicating with the upper portion of said reservoir for conducting liquid refrigerant to said low temperature evaporator, said communicating means being effective to retain a substantial body of liquid refrigerant in said reservoir when said directing means directs refrigerant to said low temperature evaporator, and means communicating with the lower portion of said reservoir for conducting liquid refrigerant to said higher temperature evaporator whereby said substantial body of liquid refrigerant retained in said reservoir during refrigeration of said low temperature evaporator is immediately made available for said higher temperature evaporator when said directing means directs liquid refrigerant to said higher temperature evaporator.

3. A refrigerating system comprising a condensing unit, a low temperature evaporator, a higher temperature evaporator and a reservoir connected in a closed refrigerant circuit, means for conducting liquid refrigerant from said condensing unit to said reservoir, a solenoid-operated valve for directing liquid refrigerant from said reservoir selectively to either of said evaporators, means communicating with the upper portion of said reservoir for conducting liquid refrigerant to said low temperature evaporator, means communicating with the lower portion of said reservoir for conducting liquid refrigerant to said higher temperature evaporator whereby liquid refrigerant retained in said refrigerant during refrigeration of said low temperature evaporator is immediately made available to said higher temperature evaporator when said valve directs liquid refrigerant to said higher temperature evaporator.

4. A refrigerating system comprising a condensing unit, a low temperature evaporator, a higher temperature evaporator and a valve connected in a closed refrigerant circuit, said valve including a housing having a reservoir for liquid refrigerant therein, means for conducting liquid refrigerant from said condensing unit to said reservoir, said valve being normally biased to one position for directing liquid refrigerant from said reservoir to said low temperature evaporator, a solenoid positioned-adjacent said valve, means responsive to a condition of said higher temperature evaporator for energizing said solenoid to shift said valve to a second position for directing liquid refrigerant from said reservoir to said higher temperature evaporator, means communicating with the upper portion of said reservoir for conducting liquid refrigerant to said low temperature evaporator whereby a substantial body of liquid refrigerant is retained in said reservoir during operation of said low temperature evaporator, and means communicating with the lower portion of said reservoir for conducting liquid refrigerant from said reservoir to said higher tem perature evaporator whereby said substantial body of liquid refrigerant is immediately made available to said higher temperature evaporator when said valve is shifted to said second position to direct liquid refrigerant to said higher temperature evaporator.

5. A refrigerating system comprising a condensing unit, two evapcrators and a tiltable reservoir connected in a closed refrigerating circuit, means for conducting liquid refrigerant from said condensing unit to said reservoir, means for conducting liquid refrigerant from said reservoir to said evaporators, means normally biasing said reservoir in one direction for directing liquid refrigerant to one of said evaporators, and means for tilting said reservoir in the opposite direction for directing liquid refrigerant to the other of said evaporators.

6. A refrigerating system comprising a condensing unit, a low temperature evaporator, a higher temperature evaporator and a tiltable reservoir connected in a closed refrigerant circuit, means for conducting liquid refrigerant from'said condensing unit to said reservoir, means for ccnducting liquid refrigerant from said reservoir to said evaporators, means normally biasing said reservoir in one direction for directing liquid refrigerant from said reservoir to said low temperature evaporator, and means for tilting said reservoir "in the opposite direction for direct in'gfliqu'id-refrigerant from said reservoir to said higher temperature evaporator, I

7. A refrigerating system'pompnsing a con densing unit, a low temp rature evaporator, a higher temperature evaperatoranu a tiltable reservoir connected in a closed refrigerant circuit, means for conducting liquid ref-rige'rantfrom said condensing i'ihit to-said reservoir, means for conducting liquid refrigerant from said reservoir t's said eva erators; means normally biasing said reservoir in one direction'for directing liquidrefrige'rant' i r orn said reservoir tosaidlow' temperature evaporator, and a solenoid energized .in response to a condition of-saidhig'he'r temperature evaporator for tilting said reservoir in the: opposite dire'ction to direct liquid refrigerant froinsaid reservoir to said higher temperature evaporator.

8; A refrigerating system comprisingacondensiiig unit ia. lowtemperatdrie -evapo; .ator,,.,a higher temperature evaporator. ltiltable res'er voir,v connected in a closed. refrigerant. circuit, means for conducting liquid refrigerant from said condensing. unit ,to .said reservoir, a common header for said evaporat-ors, a suction line for conducting vaporized refrigerantfrom said header to saidcondensing. unit, a checkvalve for blocking reverse flow of refrigerant from said header to said low temperature evaporator, means normally biasing said reservoir inone direction for directingliquid refrigerant; from said reservoir to said low temperature evaporator, and a,:s o lenoid energized in response to a condition of :said h h r; t mp a ure .evap ra oa tiaa sa d reservoir in the opposite direction to direct liquid refrigerant from said reservoir to said higher temperature evaporator.

9. A refrigerating system comprising a condensing unit, a low temperature evaporator, a higher temperature evaporator and a tiltable reservoir connected in a closed refrigerant circuit, means for conducting liquid refrigerant from said condensing unit to said reservoir, a common header for said evaporators, a suction line for conducting vaporized refrigerant from said header to said condensing unit, a conduit for connecting said low temperature evaporator in communication with said header, said conduit being connected to said header beneath the normal level of liquid refrigerant therein whereby flow of vaporized refrigerant from said higher temperature evaporator through said header to said low temperature evaporator is blocked, means normally biasing said reservoir in one direction for directing liquid refrigerant from said reservoir to said low temperature evaporator, and a solenoid energized in response to a condition of said higher temperature evaporator for tilting said reservoir in theopposite direction to direct liquid refrigerant from said reservoir to said higher temperature evaporator.

10. A refrigerating system comprising a condensing unit, a low temperature evaporator, a higher temperature evaporator and an elongated reservoir connected in a closed refrigerant circuit, said reservoir being pivotally mounted for tilting movement to direct liquid refrigerant to one end or the other of said elongated reservoir, a conduit for conducting liquid refrigerant from said condensing unit to said reservoir, a second conduit communicating with said reservoir for conducting liquid refrigerant to said low temperature evaporator, said second conduit being connected to the upper portion of said reservoir at one end thereof, a third conduit communicatconnected to the lower portion of said reservoir at the opposite end thereof, means-for tiltin g said reservoir in one direction to direct liquid ife-- rrr eranr rromsaiureservuir 'tofsaid low tempera sure evaporator, the-'connectin'g-pf- "said secondconduit to the" up er portie'n of sa'id re'servoir eau g a-substantial body of liquid refrigerant to be retained in said reservoir when said reser voi'r is tuted insaiu one direction, and-means for tiltin'g said reservoir i'n t'h'e opposite 'ec'tio direct liquid refrigerant from saidreservoir to' saicl higher-temperatiire evaporatofisaid substanti'al body or liquid refrigerant being i iir'imediately made; available to :said highertemperatureevaporator opposite-xiii ction'." a y 11 n refrigerating system comprising "amen densing unit; a low temperature evaporatorp'a higher temperature "evaporator and an elongated reservoir connected in iaelosed refrigerant (Eir cult, said reservoir lfleing' piv'otally mounted for tilting movement to direct liquid re'frigrant to one :end or the otherbf *said elon-gat" d reservoir, a conduit :rereoudue'tiug liquid refri era-nt rrom said-condensing unit to said reservoir, a second conduit communicating with said reservoir for conducting "liquid refrigerant said iew: t "nipierature evaporator, said seconds duitconnected to the upper portion of said reservoir at one end thereof, a'thiid conduit communieatingwith said :r'es'e v'oirfor conducting liquidrefrigerant from said reservoir. to said -ihi'gheh temperature evaporator, said third conduit being connected to the lower portion of said reservoir at the opposite end thereof, means normally biasing said reservoir in one direction to direct liquid refrigerant from said reservoir to said low temperature evaporator, the connecting of said second conduit to the upper portion of said reservoir causing a substantial body of liquid refrigerant to be retained in said reservoir when said reservoir is tilted in said one direction, and a. solenoid energized in response to a condition of said higher temperature evaporator for tilting said reservoir in the opposite direction to direct liquid refrigerant from said reservoir to said higher temperature evaporator, said substantial body of liquid refrigerant being immediately made available to said higher temperature evaporator when said reservoir is tilted in said opposite direction.

12. A refrigerating system comprising a condensing unit, a low temperature evaporator, a higher temperature evaporator and an elongated reservoir connected in a closed refrigerant circuit, said reservoir being pivotally mounted for tilting movement to direct liquid refrigerant to one end or the other of said elongated reservoir, a. conduit for conducting liquid refrigerant from said condensing unit to said reservoir, a second conduit communicating with said reservoir for conducting liquid refrigerant to said low temperature evaporator, said second conduit being connected to the upper portion of said reservoir at one end thereof, a third conduit communicating with said reservoir for conducting liquid refrigerant from said reservoir to said higher temperature evaporator, said third conduit being connected to the lower portion of said reservoir to the opposite end thereof, a spring for tilting said reservoir in one direction to directliquid refrigerant from said reservoir to said low temhen said reservoir is ti-lted' -iifsai'd" perature evaporator, the connecting of said second conduit in the upper portion of said reservoir causing a substantial body of liquid refrigerant to be retained in said reservoir when said reservoir is tilted in said one direction, and a solenoid energized in response to a condition of said higher temperature evaporator for tilting said reservoir in the opposite direction to direct liquid refrigerant from said reservoir to said higher temperature evaporator, said substantial body of liquid refrigerant being immediatels made available to said higher temperature evaporator when said reservoir is tilted in said opposite direction.

13. A refrigerating system comprising a condensing unit, a low temperature evaporator, a higher temperature evaporator and an elongated reservoir connected in a closed refrigerant circuit, said reservoir being pivotally mounted for tilting movement to direct liquid refrigerant to one end or the other of said elongated reservoir, a conduit for conducting liquid refrigerant from said condensing unit to said reservoir, 2. second conduit communicating with said reservoir for conducting liquid refrigerant to said low temperature evaporator, said second conduitbeing connected to the upper portion of said reservoir at one end thereof, a third conduit communicating with said reservoir for conducting liquid refrigerant from said reservoir to said higher temperatureevaporator, said third conduit being connected to the lower portion of said reservoir at the opposite end thereof, a common header for said evaporators, a suction line for-conducting vaporized refrigerant from said header to 12 said condensing unit, a check valve for blocking reverse flow of refrigerant from said header to said low temperature evaporator, means for tilting said reservoir in one direction to direct liquid refrigerant from said reservoir to said low temperature evaporator, the connecting of said second conduit in the upper portion of said reservoir causing a substantial body of liquid refrigerant to be retained in said reservoir when said reservoir is tilted in said one direction, and means for tilting said reservoir in the opposite direction to direct liquid refrigerant from said reservoir to said higher temperature evaporator, said substantial body of liquid refrigerant being immediately made available to said higher temperature evaporator when said reservoir is tilted in said opposite direction whereby vaporization of said substantial body of liquid refrigerant rapdly raises the pressure of the vaporized refrigerant in said header and said suction line so that a more efficient operation of said refrigerating system is effected during refrigeration of said higher temperature evaporator.

LEONARD V7. ATCHISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,133,948 Buchanan Oct. 25, 1938 2,133,949 Buchanan Oct. 25, 1938 2,242,814 Coons May 20, 1941 2,250,971 Smellie July 29, 1941