US2133963A - Refrigerating apparatus and method - Google Patents

Description

Oct. 25, 1938. G, a MCCLOY v 2,133,963

REFRIGERATING APPARATUS AND METHOD Original Filed Dec. 31, 1936 WITNESSES: ,INVENTOR Gavan/3m SME-CLaY 48 BY v} D ATTOR Y Patented Oct. 25, 1938 UNITED STATES PATENT OFFICE REFRIGERATING APPARATUS AND I METHOD tion of Pennsylvania Application December 31, 1936, Serial No. 118,447 Renewed April 5, 1938 8 Claims.

My invention relates to refrigeration and has for an object to provide an improved method and apparatus for refrigerating different zones of a refrigerator.

5 A further object of the invention is to vary the effective cooling area of a refrigerant evaporator by controlling admission of refrigerant thereto in response to a predetermined value of thesuperheat of the vapor within different selected por- 10 tions of the evaporator.

A still further object of .the invention is to provide an improved two temperature refrigerator that is reliable in operation and inexpensive to construct.

A still further object of my invention is to provide improved means for selectively effecting refrigeration of different zones of a refrigerator.

These and other objects are effected by my invention, as will be apparent from the following description and claims taken in connection with the accompanying drawing forming .a part of this application, in which:

Fig. 1 is a diagrammatic view of a refrigerating system constructed and arranged in accordance 2.5 with my invention; and

Fig. 2 is an enlarged sectional view of some of the elements employed in the system shown in Fig. 1.

Reference will now be had to the drawing wherein I disclose a refrigerator cabinet structure l having relatively low and high temperature chambers II and I2 formed therein and cooled by respective evaporator elements l3 and 35 I4. Refrigerant is circulated through the evaporators l3 and i l by a condensing unit, generally indicated at l5, and including a compressor 16,

amotor I! for driving the compressor, and a condenser l8, the latter being cooled in any suit- 40 able manner, such as, for example, by a fan IS.

A liquid refrigerant reservoir, shown at 2|, may

be connected to the condenser l8 for storing refrigerant condenser thereby.

Condensed refrigerant is conveyed to the evap- 45 orators l3 and M from the reservoir 2| by means of a conduit 22. Refrigerant vaporized in the evaporators I 3 and [4 passes to the compressor l6 through a conduit 23. An expansion device so 24, preferably a thermostatic expansion valve, is

arranged for controlling the fiow of condensed refrigerant to the evaporators l3 and I4 and for reducing the pressure of the refrigerant. The valve 24 will be referred to more in detail hereinafter. The refrigerating apparatus described in the foregoing is of the well-known compressorcondenser-expander type.

Liquid refrigerant is passed from the conduit 22 to the valve 24 through one or the other of a pair of conduits 26 and 21 and under the control of a two way valve structure shown generally at 28. The valve structure 24 and a header 25 are connected for the flow of refrigerant therebetween in any suitable manner as by a conduit 29.

A conduit 3| provides free communication between the header 25 and an inlet header 32 formed in the evaporator I4,;.the latterincluding an outlet header 33 having the suction conduit 23 connected thereto. Refrigerant vaporized in both evaporators l3 and I4 is withdrawn through the conduit 23 by the compressor [6. Shelf portions 34 may be provided on the evaporator l3 for the support of trays 35 in which fluid to be congealed may be disposed. The evaporator l3, therefore, congeals fluid and refrigerates the air in the chamber I I to a relatively low degree. The evaporator l4 may be finned, as shown at 36, and cools the air in the chamber or zone I2 to a temperature somewhat higher than that maintained in the chamber or zone ll.

- It will be apparent from the foregoing that refrigerant conveyed by the conduit 29 will pass into the evaporator l3 and will flow through the conduit 3| to the evaporator l4 oniy after the evaporator I3 is filled with liquid. Accordingly, the low temperature evaporator l3 receives condensed refrigerant in preference to the evaporator l4.

The amount of condensed refrigerant in the low side of the system during periods when the low temperature zone H is refrigerated is such that it fills, substantially, the evaporator l3 only. At this time, the evaporator l4 contains only refrigerant which wasvaporized at low pressure in the evaporator [3, which vaporous refrigerant is passed to the suction conduit 23 by the evaporator I4. During periods when the high temperature zone I2 is refrigerated, the amount of condensed refrigerant in the low side is increased so that it fills the evaporator 13 and a substantial portion of the evaporator l4. At this time the refrigerant in the evaporator I4 is vaporized at relatively high pressure for cooling the zone l2 and vaporization in the low temperature evaporator l3 ceases due to the fact that its temperature is below the temperature of vaporization corresponding to the prevailing pressure. The evaporator I3 is filled with liquid refrigerant at this time so that a liquid seal is provided for preventing vaporous refrigerant from entering the evaporator l3 and condensing therein, whereby undesirable heating of the evaporator I3 is precluded.

The'means for transferring refrigeration from one evaporator to the other will now be described. The expansion valve structure 24 controls the admission of refrigerant to the evaporators l3 and M in accordance with the superheat of the refrigerant vaporized in either evaporator. The valve structure 24 is shown in section in Fig. 2 to which reference will now be had.

The valve structure 24 includes a casing '31 having an inlet chamber 38 formed therein that receives refrigerant from the conduits 26 and 21.

A second or outlet chamber 39'formed in the casing 32communicates with the conduit 23 and a valve 4| controls communication between the chambers 38 and 39. The valve4| is preferably.

actuated by a diaphragm 42 that is carried by the casing 31 and which is subjected on its under side to the pressure of the refrigerant within the chamber 38, which pressure corresponds to the pressure of the refrigerant vaporized in the evaporator 13 or l4. A chamber 43 is formed in the casing above the diaphragm 42 and is connected to a plurality of bulbs or reservoirs 44 and 45 by means of a tube 46 (Fig. 1).

A volatile fluid, preferably the same fluid that is employed as the refrigerant, is contained in the bulbs 44 and 45 and the pressure in the tube 46 and chamber 43 is determined by the temperature of the bulb 44 or 45. The bulb 44 is connectedv in heat transfer relation with the conduit 3| and reflects the temperature of the refrigerant therein and the bulb 45 is preferably connected to the suction conduit 23 adjacent the outlet of the evaporator l4 for reflecting the temperature of the refrigerant passed therethrough.

The expansion valve structure 24 described in the foregoing operates in the same manner as a conventional thermostatic expansion valve in that therefore, the pressure of the fluid in the bulbs will be determined by the temperature of the lower temperature bulb.

The bulb 44 is connected to the conduit 3| of the low temperature evaporator I3 and normally is colder than the bulb 45. .Accordingly, the valve structure 24 functions to maintain a predetermined amount of superheat in the vapor in the conduit 3|, whereby vaporization is effected in the low temperature evaporator only. If the bulb 44 is heated to a temperature in excess of the temperature of the bulb 45, the latter will then function to control the valve 24. Accordingly, the downward pressure on the diaphragm is increased and the valve 4| is biased in an opening direction tively high pressure and the valve structure 24 controls the flow of refrigerant in accordance with the superheat of the refrigerant vaporized in the high temperature evaporator H.

A spring 4'! is employed for biasing the valve 44 and diaphragm 42 in opposition to the pressure in the chamber 43. The value of the superheat to which the structure 24 responds is determined bythe bias of the spring 41 and may be adjusted in any suitable manner such as, for example, by means of the screw shown at 48.

A refrigerating system having evaporating means controlled-in accordance with the foregoing description forms the subject matter of a copending application of Leslie B. M. Buchanan, Serial No. 108,516, filed October 31, 1936, and assigned to Westinghouse Electric 8; Manufacturing Company. In accordance with my invention, im-

proved means is provided for effecting the transfer of refrigeration from one evaporator to the other and a description thereof will now be given. As best shown in Fig. 2, the two-way valve structure 28 includes a casing having an inlet chamber 52 and outlet chambers 53 and 54 formed therein. The inlet chamber 52 receives condensed refrigerant from the conduit 22 and the outlet chambers 53 and 54 are connected to the conduits '26 and 21, respectively. A valve member 55 controls the, flow of refrigerant between the chambers 52 and 53 or 54, and, when in its upper position, establishes communication between the chambers 52 and 54 and, when in its lower position provides communication between the chambers 52 and 53. A solenoid, shown at 56, actuates the valve member 55 in such manner that the valve 55 is raised when the solenoid 56 is energized and is lowered when the solenoid is deenergized.

The conduit 26 leads directly from the chamber- 53 to the inlet chamber 38 of the valve structure 24. The conduit 21 is secured in heat transfer relation with the bulb 44 and conduit 3| so that the condensed refrigerant conveyed by the conduit 21 warms the bulb 44 prior to its admission to the valve structure 24. Preferably, the bulb 44 is secured to the conduit 21 and the latter is secured to the conduit 3| as shown.

During periods when the low temperature evaporator I3 is active, the solenoid 56 is deenergized and the condensed refrigerant is passed by the valve 28 to the expansion valve 24 through conduit 26. As the bulb 44 reflects the temperature of the relatively cold conduit 3| and iscolder than the bulb 45, the expansion valve 24 admits refrigerant to the evaporator l3 in suificient quantities to maintain a predetermined degree of superheat in the conduit 3|. At this time, the evaporator l4 functions to convey the vaporous refrigerant to the suction conduit 23 and is not active to cool the zone I2 to any material degree.

Duringperiods when the higher temperature evaporator I4 is active, the' solenoid 56 is energized and condensed refrigerant is passed by the two way valve 28 through conduit 21 to the expansion valve 24. The condensed refrigerant warms the bulb -44 above the temperature of the bulb 45 so'that -the latter assumes control and the valve 24 admits refrigerant in such quantities that the predetermined degree of superheat is maintained in the conduit 23. Accordingly, vaporization is effected in the higher temperature evaporator l4.

Automatic means may be provided for controlling the operation of the condensing unit l5 and the two-way valve 23 in accordance with temperature conditions in the zones II and I2. Ac-

cordingly, thermostats 51 and 58 may be disposed for reflecting the temperature within the respective chambers I I and I2. When the thermostat 51 calls for cooling, the motor I1 is energized and the solenoid 55 is deenergized so that refrigerant is circulated for vaporization in the evaporator l3. During periods when the thermostat 58 calls for cooling, the condensing unit. [5 is operated and the solenoid 58 is energized whereby refrigerant is circulated for vaporization in the higher temperature evaporator l4.

The source of energy for the motor I1 and solenoid 56 is represented by line conductors Li andergized as the conductor 59 forms a shunt therearound. Therefore, the low temperature thermostat 51 is given preference over the thermostat 58 when both demand cooling. It will be understood that the high temperature thermostat 58 may be given preference, if desired.

Operation The position of the apparatus shown in the drawing indicates that the temperatures in the chambers II and I2 below values at which their respective thermostats 51 and 58 close, and, therefore, the condensing unit I 5 is inactive and the solenoid 56 is deenergized.

Assume that the temperature within the chamber H rises to the value at which the thermostat- 51 closes. The motor I1 is energized and the condensing unit l5 operates to circulate refrigerant. As the solenoid 56 is deenergized, the condensed refrigerant is passed to the expansion valve 24 through the conduit 26. The bulb 44, being at a lower temperature than'the bulb 45, controls superheat in the conduit 3| and, as described heretofore, the evaporator' I3 is active. Operation of the condensing unit I5 continues until the temperature within the chamber H is depressed to the desired value at which time the thermostat 51 operates to deenergize the motor l1.

Assume a rise in temperature within the chamber 12 to the value at which the thermostat 58 closes to energize the motor l1 and solenoid 56. Circulation of refrigerant is initiated and, as the valve member 55 of the two-way valve 28 is raised, condensed refrigerant is passed through the conduit 21. Heating of the bulb 44 as described heretofore, transfers control of the valve 24 to the bulb 45, and the valve 24 operates to maintain the proper degree of superheat in the conduit 23. The condensed refrigerant passed to the evaporator 14 is vaporized at relatively high pressure and temperature by the heat of the chamber l2. Operation of the condensing unit l5 continues until the temperature within the chamber I2 is depressed to the value at which the thermostat 58. opens.

During the inactive periods of the condensing unit I5, or periods when the transfer of heat from thercondensed refrigerant to the bulb 44 is terminated, the conduit 21 and bulb are maintained cooler than the conduit 23 and bulb 45 so that the valve 24 is under control of the bulb 44. When operation is initiated by the thermostat 58, the bulb 44 may control the valve 24 momentarily or until the flow of refrigerant has proceeded sumciently to heat thebulb 44 above the temperature of the bulb 45.

The showings of the valves 24 and 28 are more or less diagrammatic for the sake of clearness; certain refinements usually found in structures such as these being omitted. It is to be understood that other forms of devices may be employed in lieu of the valves 24 and 28 without departing from the spirit of my invention.

From the foregoing, it will be apparent that I have provided an improved refrigerating system employing one or more evaporator structures and a common device for controlling the admission of refrigerant thereto, wherein the efiective cooling area of the evaporator or evaporators may be readily varied.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore. that only such limitations shall be placed thereupon 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 evaporators, refrigerant condensing means, means for conveying the condensed refrigerant to theevaporators for vaporization, a device common to the evaporators for controlling the vaporization of refrigerant in the evaporators, first and second temperature responsive elements associated with the respective evaporators for controlling the device, and means for selecting the element which is to control the device, said selecting means including means for transferring heat from said refrigerant conveying means to one of said temperature responsive elements.

2. In refrigerating apparatus, the combinattion of relatively high and low temperature evaporators, means for conveying condensed refrigerant to the evaporators in such manner that it flows into the low temperature evaporator in 4 preference to the higher temperature evaporator, a'valve common to the evaporators for controlling the admission of refrigerant thereto, first and second elements responsive, respectively, to the temperatures of the low and high temperature evaporators for selectively controlling the valve and means for selecting the element which is to control the valve including means for transferring heat from the condensed refrigerant to the element associated with the low temperature evaporator.

3. In refrigerating apparatus, the combination of relatively low and higher temperature evaporators so connected that condensed refrigerant admitted thereto flows into the first evaporator until filled and thence into the second evaporator, means for condensing refrigerant for the evaporators, a device common to the evaporators for controlling the admission of condensed refrigerant thereto, first and second thermally responsive elements associated, respectively, with the low and higher temperature evaporators for controlling said device, means for conveying condensed refrigerant to said device and including parallel connected conduits, one of which is disposed in-heat transfer relation with the thermally responsive element associated with the low temperature evaporator, and means for selecting the conduit which is to convey the condensed refrigerant, whereby vaporization of refrigerant is effected in one or the other of said evaporators under control of its respective thermally responsive element.

4. The combination as claimed in claim 7.3 wherein said conduit selecting means includes thermostats responsive to the temperatures produced by the low and higher temperature evaporators.

5. In a refrigerating system, the combination of an evaporator having a plurality of portions thereof serially arranged with respect to the flow of refrigerant, refrigerant circulating means for withdrawing vaporous refrigerant from the evaporator and for delivering condensed refrigerant thereto, a device for controlling the admission of condensed refrigerant to the evaporator, a plurality of means responsive to the superheat of the vaporous refrigerant in the respective evaporator portions for controlling said device and means for selecting the superheat responsive means that is effective to control the device, whereby the area of the evaporator that is effected for cooling is varied, said selecting means including means for transferring heat from the condensed refrigerant to one of said superheat responsive means.

6.- In a refrigerating system, the combination of an evaporator having first and second portions arranged for the flow of refrigerant in series therethrough, refrigerant condensing means, a valve for controlling the fiow of condensed refrigerant from the last-named means to the evaporators, a pair of conduits connected in parallel for conducting condensed refrigerant to said valve, means for selecting the conduit to convey the refrigerant, and first and second temperature responsive elements associated with the respective evaporator for controlling said valve, one of said parallel connected conduits being disposed in heat transfer relation with the first temperature responsive element.

7. In refrigerating apparatus, the combination of a structure defining relatively low and higher temperature zones to be refrigerated, relatively r low and higher temperature evaporators disposed for cooling said zones and so connected that con densed refrigerant admitted to the evaporators flows into the low temperature evaporator until filled and thence into the higher temperature evaporator, means for condensing refrigerant for the evaporators, avalve for controlling the flow of condensed refrigerant to said evaporators, first and second elements for controlling said valve and responsive to the temperatures of low and higher temperature evaporators, respectively, a pair of parallel connected conduits for conveying the condensed refrigerant to the valve, one of said parallel connected conduits being disposed in heat transfer relation with said first temperature responsive element, means for selecting the conduit which is to convey the condensed refrigerant, said means being adjustable to a first position wherein said one conduit conveys the refrigerant and being normally disposed in a second position wherein the other of the conduits conveys the refrigerant, means responsive to'a predetermined temperature condition within said higher temperature zone for effecting operation of the condensing means and for actuating the. selecting means to said first position and means responsive 'to,a predetermined temperature within the low temperature zone for effecting operation of the condensing means, at which time the selecting means is disposed in its secondor normal position. 4

8. The method of operating multi-temperature refrigerating systems in which refrigerant is compressed, condensed, and expanded in repeated cycles and embodying a plurality of evaporators for refrigerating a plurality of respective zones at different temperatures, which comprises controlling thevaporization of refrigerant in each evaporator in response to the superheat of the refrigerant vapor from it, and selecting which of the evaporators is to be active by selectively adding heat from the condensed refrigerant to the heat from the superheated vapor from one of said evaporators.

GRAHAM S. McCLOY.

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