US2719407A - Two temperature refrigeration apparatus - Google Patents

Description

Um, 4, 1955 E. w. ZEARFOSS, JR 2,719,407

TWO TEMPERATURE REFRGERATION APPARATUS Filed Aug. l2, 1955 2 Sheets-Sheet l mi., 4, 1955 E. W. ZEARFOSS, JR n WW TWO TEMPERATURE REFRIGERATION APPARATUS Filed Aug. l2, 1953 2 Sheets-Sheet 2 /f ///////l// /Q l N V EN TOR.

United States Patent O TWO TEMPERATURE REFRIGERATION APPARATUS Elmer W. Zeal-foss, Jr., Philadelphia, Pa., assigner to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania Application August 12, 1953, Serial No. 373,878

14 Claims. (Cl. 62-6) The present invention relates to refrigeration apparatus, the instant disclosure being a continuation-impart of my copending application, Serial No. 264,868, tiled January 4, 1952, now abandoned.

Particularly, the invention is concerned with domestic refrigerators of the general type having separate compartments, each of which is specially suited for a distinct refrigerating purpose. More specifically, the herein disclosed and claimed invention has to do with an improved refrigeration system adapted for association with a refrigerator of the above mentioned variety.

lt is a well recognized fact that unusual problems and dillculties are brought about by present-day demands for a household refrigerator which incorporates a plurality of distinct cooling zones, for example, a zone adapted to be cooled to above freezing temperatures for the preservation of fresh foods without freezing them, and another or second zone adapted to be maintained at sub-freezing temperatures for the preservation of frozen food over a long period of time. For that purpose, it is common practice to provide a two-evaporator system to effect cooling within a refrigerator of the above-mentioned kind. A disadvantage in the operation of such a system is brought about by the fact that variations in ambient or room air temperature so affect the pressure within the system that it becomes dilicult to control the ow of refrigerant so as to prevent either excessive cooling or warming up of the fresh food storage compartment. The problem becomes more acute when attempts are made to provide a refrigeration system of simplified construction which does not use complicated control circuitry and yet is capable of maintaining the desired temperature range within each zone or compartment, regardless of ambient temperature conditions.

Accordingly, it is a broad object of the invention to overcome the above-mentioned problems and difficulties and still provide a greatly simplified and inexpensive plural evaporator system which will produce and maintain the desired temperature condition within each of the refrigerator compartments even when an unpredictable rise or `drop in ambient or room air temperature occurs. In keeping with this broad objective, the system which is provided by this invention incorporates a simple conduit arrangement whereby the flow of liquid refrigerant to the evaporators can be automatically controlled to maintain desired temperature conditions within the several compartments without utilizing intricate valving means.

Another and more specific object of the invention has to do with the provision of a plural evaporator refrigerating system in which the ilow of refrigerant to the evaporator which is associated with the fresh food storage compartment is modulated in accordance with changes in ambient temperature. The system is such that said evaporator receives less liquid in the event of a drop yin ambient temperature, and more liquid in the event of a rise in ambient temperature. In this manner, the evaporator in heat exchange relation with the fresh food Z ,7 19,407 Patented ct. 4, 1955 'ice storage compartment, produces a lesser cooling effect when ambient conditions would normally cause freezingup of said compartment, and produces a greater cooling effect when ambient conditions would normally cause warming-up of said compartment.

It is also an object of the invention to provide a twoevaporator refrigeration system in which the ow of liquid refrigerant to one of the evaporators can be so controlled as to govern the temperature of said one evaporator without affecting the temperature of the other evaporator. In accordance with this object it is possible, at selected times, to allow the temperature of said one evaporator to rise suiciently high to effect quick defrosting thereof while the temperature of the other evaporator remains sufficiently low to maintain its normal refrigerating effect.

In achievement of the mentioned objectives and resulting advantages, the invention employs a refrigeration system having a pair of evaporators in series flow circuit with a compressor and a condenser, and the invention simplies the construct-ion and improves the operation of the system by incorporating a novel. iiow restricting or capillary tube arrangement in that part of the circuit which is adapted to feed refrigerant to the evaporators. This novel arrangement comprises conduit means provided with a capillary tube which is split or divided into two sections; one of said sections being coupled to the inlet of one evaporator, and the other of said sections being coupled to the inlet of the other evaporator. A refrigerant `distributing and ilow modulating chamber communicates with said capillary tube sections to supply refrigerant for feeding to said evaporators.

In `one for-m of the invention, one of the capillary tube sections is conveniently associated with heating means in such a manner that the heat supplied by said means produces a condition which interferes with the normal flow of liquid refrigerant to the one evaporator into which said one tube section discharges. The operation of the heating means is advantageously controlled in response to temperature condi-tions within that compartment which is subjected to the refrigerating effect of said one evaporator, and the association of the mentioned one capillary tube section with the heat generating means is such that the ow of liquid refrigerant to said one evaporator is modified in accordance with the refrigerating demand of said one compartment.

A feature of the system devised in accordance with the invention is that although the two evaporators are connected in series flow circuit, each evaporator can receive, directly, liquid refrigerant which flows out of the condenser. Because of this feature, it is possible to control the ow of liquid refrigerant to one evaporator without detrimentally affecting the flow of liquid refrigerant to the other evaporator. Another characteristic feature of the novel system resides in the fact that the flow of liquid refrigerant to the one evaporator which is designed to serve as a freezer, can be so controlled that, under most adverse operating conditions, a portion of the surface area of said evaporator can be maintained at very low freezing temperatures, with the result that water contained in the tray or trays in immediate contact with said portion, can be frozen solid in a relatively short period of time,

The novel features of the invention and the manner in which the above recited and other objects and advantages are best achieved, will clearly appear from the following description of the embodiments illustrated in the accompanying drawings, in which:

Figure l is a sectional view taken generally through the vertical mid-plane of a refrigerator embodying a preferred form of the invention, certain elements of the improved refrigeration system being diagrammatically shown; and,

Figure 2 is a sectional view taken generally through the vertical mid-plane of a refrigerator embodying another form of the invention, certain elements of the refrigerating system being diagrammatically shown.

With more particular reference to the drawings, it will be seen that in the form illustrated in Figure l, the invention is embodied in a domestic or household refrigerator which comprises a cabinet having an outer shell 11 and a pair of inner liners 12 and 13, said shell and liners being spaced and insulated from each other by means of suitable insulation 14. As is customary, breaker strips g 15 of low thermal conductivity extend about the forward edge of thecabinet and bridge the gaps between said shell and inner liners. These liners define two isolated zones which constitute a lower compartment 16 and an upper compartment 17. Insulated doors 18 and 19 of usual construction, including gasket strips 20, are employed to close the front access opening of each of said cornpartments, respectively.

The lower compartment 16 is utilized for the storage of food to be kept at cooling or non-freezing temperatures and, according to usual practice, is supplied with suitable shelves (not shown) for supporting the food. In the embodiment illustrated in Figure l, this lower cornpartment is effectively cooled and maintained at cooling or non-freezing temperatures by means of an evaporator, generally designated at 21, which advantageously consists of a generally rectangular metallic sheet 22, provided with conduit means 23 for circulation of refrigerant in heat exchange relation with said sheet. The plate evaporator 21 is conveniently mounted in a vertical position close to the rear wall and extends substantially from one to the other of the confronting side walls of said liner so as to present a comparatively large surface which is exposed to the air within said lower compartment.

The upper compartment encloses an evaporator gen erally designated at 24, which is in the convenient form of a freezer casing 25 having an open front and provided with conduit means 26 for circulation of refrigerant in heat exchange relation with said casing. The

the outlet side of the compressor is connected with the inlet end of the condenser 28 through conduit 39.

In accordance with the invention, a capillary tube arrangement having a main portion 40 and two subsidiary sections or branches 41 and 42, serves to connect the outlet end of the condenser with the inlet of the plate evaporator 21, as is shown at 43, and also with the conduit 35 at a point intermediate the outlet of the plate evaporator and the inlet of the freezer evaporator, as is illustrated at 44.

Furthermore, in accordance with the invention a refrigerant distributing and flow modulating chamber 45 serves to establish communication between the capillary tubing sections 41 and 42. As shown, the outlet end 46 of said main capillary tube 40 opens into an upper portion of said chamber, the inlet end of 47 of capillary tubing section 41 is disposed at a lower portion of said chamber, and the inlet end 48 of the other capillary tubing section 42 is disposed at an intermediate portion of said chamber and above said end 47 of the capillary tubing section 41. In practice, elements of the system including the accumulator, the conduit connecting the two evapo rators, the capillary tubing arrangement and the refrigerant distributing and flow modulating chamber, which elements are shown, for clarity of illustration, outside the refrigerator cabinet, would be located and enclosed within the insulation to protect said elements and to thermally insulate the same.

In operation of the above described system, refrigerant compressed in the motor-compressor 27 and liquied in the condenser 28 is fed into the distributing and modulating chamber 45 through the main capillary tube 40,

; which, as previously noted, opens in an upper portion of the level of the liquid in the chamber is normally up to freezer evaporator 24 is fitted within and occupies substantially the full space defined by the inner liner 13 and serves for the accommodation of ice trays and for the storage of frozen foods. For that purpose, the evaporator 24 is adapted to produce and to maintain sub-freezing temperatures within its casing 25.

As shown in Figure l, the lower plate evaporator 21 and the upper freezer evaporator 24 form parts of a refrigerating system which includes a motor-compressor 27 and a condenser 28. The onand-off cycling of the motor compressor is controlled by means of device 29 of the known bellows type, having a feeler bulb 30. As illustrated in Figure l, the feeler bulb is arranged in heat exchange relation with the plate evaporator 21 so the inlet 48 of the capillary tubing section 42 and well above the inlet 47 of the capillary tubing section 41 so that, during normal operating conditions at average ambient temperature, liquid refrigerant enters said section 41 and a mixture of liquid and flash gas enters the capillary tubing section 42.

At high ambient temperatures, the pressure drop between the condenser 28 and the plate evaporator 21 increases so that more liquid refrigerant is forced from the distributing or modulating chamber 45 through the capillary tube 41 and into said plate evaporator 21. As a result, the level of the liquid in said chamber drops so that, depending on the rise in ambient temperature, little or no liquid refrigerant passes through the capillary tube section y 42 into the freezer evaporator 24. In other Words, under that the temperature of the latter influences the operation of said device 29 to actuate a switch element 31 for opening and closing contacts 32 in the electrical circuit 33, which is adapted to supply electrical energy to the motor-compressor. The control device 29 is such that when the temperature of the plate evaporator reaches the lower end of its predetermined operating temperature range, the switch element 31 is moved to open the circuit 33 to deenergize the motor-compressor and, when the temperature of said evaporator reaches the upper end of said range, said switch element is actuated to close said circuit to energize the motor-compressor.

The two evaporators are connected in series ow circuit by means of a conduit 35, which leads from the outlet of the plate evaporator to the inlet of the freezer evaporator. The outlet of the freezer evaporator communicates through a conduit section 36 with an accumu` lator 37, which, in turn, communicates with the inlet side of the compressor 27 through a conduit section 38, and

high ambient temperature conditions, most or all of the liquid passes through the plate evaporator before reaching the freezer evaporator 24.

At low ambient temperatures, the pressure drop between the condenser and the plate evaporator decreases so that less liquid refrigerant is forced through the capillary tube 41 into plate evaporator 21. As a result, liquid refrigerant accumulates in chamber 45 so that a larger amount of liquid passes directly into the freezer evaporator 24, by-

passing said plate evaporator 21.

This refrigerant ilow modulation which occurs with changes in ambient or room air temperature, is a function of the restrictive effect of a split capillary tube arrangement and, because the rate of llow through a capillary tube can be determined by the internal diameter and length of capillary tubing used, it is possible to obtain the desired modulation by properly interrelating the size of the main capillary tube 40 and of the capillary tube sections 41 and 42. In practicing the invention, very satisfactory results were obtained by using eight feet six inches of .031 inch (ID) tubing for the main capillary 40, by using twenty-two' inches of .031 inch (ID) tubing for the capillary section 41 and by using ten inches of .060 inch (ID) tubing for the capillary section 42.

It will be noted that in the system of the invention, the restrictor or capillary tube section 41 has preference in liquid flow because said restrictor leads from the lower portion of chamber 4S. However, in accordance with the invention, this condition is controlled by so proportioning the restriction of the capillary section 41, with respect to the restriction of capillary section 42, that said section 41 does not pass all the available liquid refrigerant. In fact, in accordance with the invention, the restrictive value of the capillary section 41 is so increased with reference to the restrictive value of the capillary section 42 that the flow of refrigerant to said section 41 is practically nil at lower ambient air temperatures encountered for example at 65 F. Under such a condition, the plate evaporator 21, of course, produces little refrigeration within the compartment 16.

It Will be understood that with the relative restrictions of the capillary tube sections 41 and 42 adjusted, as above described, for a 65 F. ambient air temperature, a certain definite pressure drop will take place across the main capillary tube 40 as well as across the two capillary sections 41 and 42. For example, at the mentioned 65 F. ambient air temperature, the pressure drop across said main capillary tube may be sixty-live pounds per square inch, and the pressure drop across the capillary sections 41 and 42 may be twenty-tive pounds per square inch. As is well recognized in the art, a rise in ambient air temperature brings about a rise in condensing pressure. This rise in condensing pressure, of course, produces an increase in the pressure drop across the capillary tube and, in a system constructed in accordance with the invention, an increase in condensing pressure brought about by a rise in ambient air temperature, will not only produce an increase in the pressure drop across the main capillary tube 4t), but will also produce an increase in the pressure drop across the capillary sections 41 and 42. For instance, in the example hereinbefore given, the pressure drop of twenty-tive pounds per square inch across said sections at a 65 F. ambient air temperature may rise to ifty pounds per square inch at an 80 F. ambient air temperature. This increased pressure will force more liquid refrigerant through the capillary section 41, which, due to its connection at the lower portion of the chamber 45, has preference over the capillary section 42. Accordingly, the refrigerating effect of the plate evaporator 21 is increased at a time when high ambient air temperature requires more cooling within the compartment 16, so that the system provides compensation for the effects of raising ambient air temperature without requiring the use of control means, such as dampers or heaters, Within the cabinet.

It will be understood that the increased flow through the capillary section 41 at higher ambient air temperatures is relative to the flow through the capillary section 42. However, the refrigerant in the header or accumulator 37 at the outlet of the freezer evaporator 24 takes up the How variations without affecting the actual refrigerating areas of said evaporator. In other words, in a system constructed as above described, in the event of a rise in ambient air temperature, more refrigerant is shifted to the plate evaporator where it is most needed, and thus `the system provides said plate evaporator with a greater percentage of the refrigeration capacity of the compressor.

In the continued operation of the system, refrigerant from the upper evaporator 24 passes into the accumu lator 37 from which gas is drawn into the compressor through the conduit section 38 and is discharged into the condenser through the conduit 39, In the condenser, the compressed gas is liquilied for recirculation `through the system in the above-stated manner.

In the modified embodiment illustrated in Figure 2, the system is basically the same as that above described and shown in Figure 1. In this modified embodiment, heating means is associated with one section of the split capillary tube arrangement. This heating means is adapted, as will be hereinafter explained, to control the ow of refrigerant to one of the evaporators in accordance with the temperature of the air within the compartment with which said evaporator is associated.

As illustrated in Figure 2, the cabinet construction is generally similar to that hereinbefore described, but the compartments interiorly of said cabinet are so rearranged that the non-freezing compartment 16 which is defined by the inner liner 12, is located in the upper portion of the cabinet, and the freezing compartmenr which is provided by the boX-like evaporator 24, in located in the lower portion of the cabinet. Moreover, the non-freezing compartment is sub-divided by means of a partitioning member or bafe plate to provide a third compartment 51, which is disposed adjacent the inner top wall of the cabinet. The plate evaporator 21 is mounted in a substantially horizontal position within said third compartment and cooperates with adjacent wall portions of the liner 12 to form an enclosure for ice trays, one of which is shown at 52. Means including a gasket strip 53 and a door 54, serves normally to prevent free circulation of air into and out of said `er1- closure, although the partitioning bafiie plate 56 is arranged to permit air within the compartment 16 to circulate in heat exchange relationship with the plate evaporator 21, as is represented by the arrows in Fig- 'ure 2.

As was hereinbefore indicated, the refrigerant circulating system shown in Figure 2 and including the compressor 27, condenser 2S, main capillary tube 40, distributing chamber 45 and capillary tube sections 41 and 42, functions to feed refrigerant to the two evaporators in the manner described with reference to Figure 1. However, in the form illustrated in Figure 2, there is provided the additional feature that the flow restricting `effect of the capillary tube section 41 which feeds refrigerant to the plate evaporator 21, can be con` trolled in order further to insure maintenance of desired temperature conditions within the non-freezing compartment 16.

For that purpose, temperature controlling means in the form of an electrical heater is associated in heat exchange relationship with a tube portion adjacent the inlet end of the capillary tube section 41 so that the heat which is supplied upon energization of said heater, causes vaporization of liquid refrigerant being admitted to said tube section. Accordingly, so long as the heater is in operation, gas is present at the entrance portion of said section and thus creates a vapor-lock condition which interferes with the flow of liquid refrigerant to the evaporator 21. As a consequence, the ability of said evaporator to produce its maximum refrigerating effect is reduced with the ultimate result that the air which circulates within the storage compartment 16 is cooled to a lesser extent. It is to be noted that the condition which modifies the normal operation of the evaporator 21, does not affect the normal operation of the other evaporator 24. This is because the vaporloclc condition existing in the capillary tube section 41 due to operation of the heater, causes the liquid level in the distributing chamber 45 to rise so that more liquid is made available for passage through the other or second capillary tube section 42 to the lower evaporator 24. Thus, an additional amount of liquid is supplied through said second section to malte up for the loss of liquid in the refrigerant which normally would flow from the upper evaporator through the interconnecting conduit 35 and into the lower evaporator 24.

The operation of the heater 55 is advantageously controlled in response to temperature conditions which exist within the compartment 16. This kind. of control is conveniently obtained by means of a suitable known sylphon device 56, which has its feeler bulb 57 disposed within a compartment 16 and which is adapted to actuate a switch element 58 to make or break the electrical connection to said heater. The operation of the sylphon device is such that when the temperature within the compartment 16 reaches a predetermined high value, for example +38 F., the switch element is actuated to deenergize the heater, thus providing for normal operation of the evaporator 21 to cool the air in said compartment; and when the temperature in said compartrnent reaches a predetermined low value, for example +34 F., the switch element is actuated to energize the heater, thus modifying the operation of said evaporator so as to lessen its cooling effect on the air in said compartment.

During normal operation of the above described system, liquid refrigerant ows in the evaporator 21 in a quantity suficient to cool, to freezing temperatures, the effective surface area of said evaporator. However, it will be understood that should, during such normal operation, an excessive heat load be imposed upon said evaporator, as by introducing a full complement of trays of water in the ice-tray enclosure, then the supply of liquid refrigerant fed to said evaporator will become exhausted before passage through the entire evaporator is achieved. `Even under these conditions, the capillary tube section 41 continues to feed a full supply of liquid refrigerant directly into the evaporator 21 so that a substantial portion of the surface area of said evaporator is kept at freezing temperatures and, as a result, the Water in the tray or trays in contact with said portion of the evaporator can be rapidly frozen into solid ice cubes.

From the foregoing description, it will be appreciated that the invention provides a simple, yet effective system by means of which the temperature of each compartment of a plural compartment refrigerator, is adequately maintained within the desired range. It is to be noted that the system illustrated in Figure 2 of the drawings, has the advantage of readily lending itself to automatic defrosting of the plate evaporator without affecting the temperature of the frozen food evaporator. This advantage can be conveniently obtained by the simple expedient of incorporating suitable known switch control means in the electrical circuit of the heater. Such control means would operate to energize said heater for a time long enough to allow melting of frost off the ice-tray evaporator, during which time the system would continue to feed liquid refrigerant through the tube 42 to the other or frozen food evaporator.

I claim:

1. A refrigeration system comprising a pair of evaporators connected in series flow circuit, means including a condenser to supply refrigerant to said evaporators, a main capillary tube connected with the condenser to conduct refrigerant therefrom, a refrigerant distributing chamber into which said capillary tube discharges refrig erant from the condenser, and a pair of capillary tube sections leading from said distributing chamber, one of said sections feeding refrigerant from said chamber to the inlet end of one of said evaporators, the other of said sections feeding refrigerant from said distributing chamber to the inlet end of the other of said evaporators for mixing with refrigerant passing out of said one of said evaporators before passing into the inlet end of the other of said evaporators.

2. A refrigeration system comprising a pair of evaporators, passage means connecting the outlet of one of said evaporators with the inlet end of the other of said evaporators and providing for passage of refrigerant out of one of said evaporators into the inlet end of the other of said evaporators, means including a condenser to supply refrigerant for feeding to said evaporators, and conduit means communicating with the condenser and including a pair of flow restricting tube sections, means connecting said tube sections in open communication with said condenser to provide for iiow of refrigerant from said condenser through said sections simultaneously, one of said sections being connected with the inlet end of said one of said evaporators to feed refrigerant from the condenser to said inlet end of said one of said evaporators, the other of said sections being connected with said passage means to feed thereinto refrigerant from the condenser into the inlet end of said other of said evaporators for mixing with refrigerant passing out of said one of said evaporators and into the inlet end of said other of said evaporators prior to passing of the refrigerant from said one evaporator into said other of said evaporators.

3. A refrigeration system comprising a first evaporator, a second evaporator, the outlet of said first evaporator communicating with the inlet of said second evaporator and providing for passage of refrigerant out of said first evaporator into said second evaporator, means including a condenser to supply refrigerant for feeding to said evaporators, and conduit means communicating with the condenser and including a pair of refrigerant flow restricting tube sections, one section being connected with the inlet of said first evaporator to feed refrigerant supplied from said condenser to said first evaporator, the other of said sections being connected between the outlet of said first evaporator and the inlet of said second evaporator to feed refrigerant from the condenser for mixing with refrigerant passing out of said rst evaporator prior to passing into said second evaporator.

4. A refrigeration system comprising a pair of evaporators, passage means connecting the outlet of one of said evaporators with the inlet of the other of said evaporators and providing for passage of refrigerant out of one of said evaporators into the inlet end of the other of said evaporators, means including a condenser for supplying refrigerant for feeding to said evaporators, a conduit connected with the condenser to conduct refrigerant therefrom, a refrigerant distributing and flow modulating chamber into the upper end of which said conduit discharges refrigerant from the condenser, and a pair of flow-restricting tubing sections, one of said sections being connected with the lower end of said chamber and With said one of said evaporators to feed refrigerant from the lower end of said chamber to said one of said evaporators, the other of said sections being connected with an intermediate portion of said chamber and with said passage means to feed thereinto refrigerant from said intermediate portion of said chamber for mixing with refrigerant passing out of said one of said evaporators and into the inlet end of said other of said evaporators prior to passing of the refrigerant from said one evaporator into said other of said evaporators.

5. A refrigeration system comprising a first evaporator, a second evaporator, the outlet of said first evaporator communicating with the inlet of said second evaporator and providing for passage of refrigerant out of said first evaporator into said second evaporator, means including a condenser for supplying refrigerant for feeding to said evaporators, a conduit of capillary tubing connected with the condenser to conduct refrigerant therefrom, a refrigerant distributing chamber into which said conduit discharges refrigerant from the condenser, and a pair of capillary tubing sections, one of said sections having one of its ends connected with said chamber and having the other of its ends connected with the inlet of said first evaporator to feed refrigerant from said chamber to said first evaporator, the other of said sections having one of its ends connected with said chamber and having the other of its ends connected between the outlet of said first evaporator and the inlet of said second evaporator to feed refrigerant from said chamber for mixing with refrigerant passing out of said first evaporator prior to passing into said second evaporator.

6. In combination with .a refrigerator cabinet having a plurality of compartments, a first evaporator in heat exchange relation with one of said compartments to provide non-freezing temperatures therein, a second evaporator having its inlet and connected to the outlet end of said first evaporator whereby said second evaporator is in series flow circuit with said first evaporator and in heat exchange relation with another of said compartments to provide sub-freezing temperatures therein, and means for controlling the refrigerating effect of said first evaporator in accordance with variations in room air temperature without substantially interfering with the refrigerating effect of said second evaporator, said means including a refrigerant distributing and flow modulating chamber and a pair of fiow restrictors, one of said restrictors being connected with said chamber and with the inlet end of said first evaporator to feed refrigerant from said chamber to the inlet end of said first evaporator, the other of said restrictors being connected with said chamber and with the inlet end of said second evaporator to feed refrigerant from said chamber for mixing with refrigerant passing out of said first evaporator and into the inlet end of said second evaporator before passing of said refrigerant from said first evaporator into said second evaporator.

7. In combination with a refrigerator cabinet having a plurality of compartments, a first evaporator in heat exchange relation with one of said compartments to provide non-freezing temperatures therein, a second evaporator having its inlet end connected to the outlet end of said first evaporator whereby said second evaporator is in series flow circuit with said first evaporator and in heat exchange relation with another of said compartments to provide sub-freezing temperatures therein, and means in the refrigerant feeding circuit to said evaporators to modify the flow of refrigerant thereto in accordance with variations in room air temperature, said means including a refrigerant distributing and flow modulating chamber.

and a pair of capillary tube sections, one of said sections being connected with said chamber and with the inlet end of said first evaporator to feed refrigerant from said chamber to the inlet end of said first evaporator, the other of said sections being connected with said chamber and with the inlet end of said second evaporator to feed refrigerant from said chamber for mixing with refrigerant passing out of said first evaporator and into the inlet end of said second evaporator before passing of said refrigerant from said first evaporator into said second evaporator.

8. In combination with a refrigerator cabinet having a plurality of compartments, a refrigerating system comprising a first evaporator for cooling one of said compartments, a second evaporator for cooling another of said compartments, passage means between said evaporators providing for passage of refrigerant out of said first evaporator into the inlet end of said second evaporator, means including a condenser for supplying refrigerant for feeding to said evaporators, conduit means connected with the condenser and including a pair of refrigerant fiow restricting tube sections, one of said sections being connected with the inlet end of said first evaporator to feed refrigerant from the condenser to the inlet end of said first evaporator, and the other of said sections being connected with said passage means to feed thereinto refrigerant from the condenser into the inlet end of said second evaporator for mixing with the refrigerant passing out of the first evaporator and into the inlet end of said second evaporator prior to passing of said refrigerant from said evaporator into said second evaporator.

9. In combination with a refrigerator cabinet having an upper compartment and a lower compartment, a first evaporator mounted in one of said compartments, a second evaporator mounted in the other of said compartments, passage means connecting said evaporators and providing for passage of refrigerant out of said first evaporator into said second evaporator, means including a condenser for supplying refrigerant for feeding to said evaporators, conduit means connected with the condenser CJI Cir

and including a pair of refrigerant flow restricting tube sections, one of said sections being connected with the inlet of the first evaporator to feed refrigerant from said condenser to said first evaporator, and the other of said sections being connected with said passage means at a point beyond the outlet of the first evaporator and ahead of the inlet of said second evaporator to feed refrigerant from the condenser for mixing with refrigerant passing out of the first evaporator prior to passing into said second evaporator.

10. A refrigeration system comprising a first evaporator, a second evaporator, passage means between the outlet of said first evaporator and the inlet of said secn ond evaporator and providing for passage of refrigerant out of said first evaporator into the inlet of said second evaporator, means including a condenser for supplying refrigerant for feeding to said evaporators, conduit means connected with the condenser and including a pair of refrigerant fiow restricting tube sections, one of said sec tions being connected with the inlet end of said first evaporator to feed refrigerant from the condenser to said first evaporator, the other of said sections being connected with said passage means to feed thereinto refrigerant from the condenser into the inlet end of said second evaporator for mixing with refrigerant passing out of said rst evaporator and into the inlet end of said second evaporator prior to passing of' said refrigerant from said first evaporator into said second evaporator, and means arranged in association with said conduit means to vary the refrigerant fiow restricting effect in said one of said tube sections.

1l. A refrigeration system as set forth in claim 10, in which the last named means comprises an electrical resistance heater arranged in heat exchange relation with a tube portion adjacent the entrance of the last mentioned one of said sections.

l2. A refrigeration system comprising a pair of evaporators, means including a condenser for supplying refrigerant for feeding to said evaporators, a capillary tube arrangement including a flow restricting main section connected with said condenser and branched to provide a pair of refrigerant fiow restricting auxiliary sections, one of said auxiliary sections communicating with one of said evaporators, the other of said auxiliary sections communicating with the other of said evaporators, means including said main section connecting said auxiliary sections in open communication with said condenser to provide for flow of refrigerant from said condenser through said auxiliary sections simultaneously and heating means arranged in heat exchange relation with one of said auxiliary sections and operable to vary the refrigerant flow restricting effect in said last mentioned one of said auxiliary sections.

13. In combination with a refrigerator cabinet having a plurality of compartments, a refrigeration system comprising a first evaporator for cooling one of said compartments, a second evaporator for cooling another of said compartments, passage means between said evaporators and providing for passage of refrigerant out of said first evaporator into said second evaporator, means including a condenser for supplying refrigerant for feeding to` said evaporators, conduit means connected with the condenser and including a pair of refrigerant fiow restricting tube sections, one of said sections being connected with the first evaporator to feed refrigerant from the condenser to said first evaporator, the other of said sections being connected with said passage means to feed refrigerant from the condenser for mixing with refrigerant passing out of said first evaporator prior to passing into said second evaporator, and heating means arranged in heat exchange relation with a tube portion adjacent the entrance of said one of said sections and operable to vary the refrigerant flow restricting effect in said one of said sections in response to temperature conditions in one of said compartments.

14. In combination with a refrigerator cabinet having an upper compartment, an intermediate compartment and a lower compartment, a rst evaporator mounted in the upper compartment, a second evaporator mounted in the lower compartment, means between the upper and intermediate compartments to provide for circulation of air within said intermediate compartment in heat exchange with said rst evaporator, passage means connecting said evaporators and providing for passage of refrigerant out of said rst evaporator into said second evaporator, means including a condenser for supplying refrigerant for feeding to said evaporators, conduit means connected with the condenser and including a pair of refrigerant flow restricting tube sections, one of said sections being connected with the inlet of the first evaporator to feed refrigerant from said condenser to said irst evaporator, the other of said sections being connected with References Cited in the file of this patent UNITED STATES PATENTS 2,539,908 Jenkins Ian, 30, 1951 N. Naf, .c

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