US2148412A - Refrigerating apparatus - Google Patents

Description

Feb. '21, 1939. F. CONRAD 2,143,412

REFRIGERATING APPARATUS Filed Jan. 19, 1933 V mvENTok G :3 Fmmx Comma.

BY C515,.M

A'ITORNEY Patented Feb. 21, 1939 UNITED STATES PATENT OFFICE,

2,148,412 REFRIGERATING APPARATUS Frank Conrad, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company,

East Pittsburgh, Pa., a. corporation of Pennsylvania Application January 19, 1933, Serial No. 652,535

18 Claims.

My invention relates to refrigerating apparatus,

" statically-controlled expansion valves. These valves, however, are open to the objection that they are complicated and expensive, and require a separate connection from the refrigerant line to each evaporator.

I have found that capillary tubes are very satisfactory to distribute refrigerant to a plurality of evaporators connected in parallel, the capillary tubes also acting as fixed resistance expansion valves. Where the" evaporators are not equally loaded, the capillary tubes efiectively tend, as

compared with conduits or other connections having only negligible resistance to flow, to prevent the least loaded evaporator from starving the others since the largest pressure diife'rence between an inlet of the capillary tubes and the evaporatorsoccurs at the least'loaded evaporator due to the low pressure of the refrigerant therein, As the pressure difference between the ends of a tube conveying a. liquid increases, the flow through the tube increases only as the square root of the increase in pressure difference, and,therefore, there 'is a tendency to prevent starvingof the other evaporators.

A' regulating valve is disposed in the supply conduit adjacent to the capillary tubes to modify the action of the capillary tubes by either manual or automatic means, thereby regulating the amount of refrigerant delivered to the cooling unit. The aforesaid automatic and manual means are also adapted to completely shut oil? the flow ofrefriger'ant under certain conditions. I I

The capillary tubes, however, being of constant orifice, allow liquid refrigerant to be iorced'to the low pressure evaporators from the highpressurc condenserwhen the compressor stops pumpine'ajwith a resultantpressure rise in the evaporators, so that the compressor may pump liquid on starting with resultant overload thereon, which may result in breaking of the combodiment ofmy invention;

pressor valves. In addition to this, if the pressure in the condenser rises unduly, more refrigerant is forced to the evaporator than the compressor can pump away with resultant overload of the compressor. To prevent overloading from these and other causes, the aforementioned regulating valve is connected in the system in such a manner that it responds to a temperature or pressure condition thereofto automatically control the flow of refrigerant to the evaporator by partially or completely stopping the flow substantlally independently of the manual or automatic temperature-regulating means.

It is an object of my invention, therefore, to provide a novel control means for a. plurality of evaporators connected in parallel to a common supply line.

It is another object of my invention to prevent overloading of the compressor of refrigerating apparatus.

It is a further object of my invention to provide ,a refrigerating system having a plurality of evaporators connected in parallel with a common supply line in which the temperatures of the evaporators are controlled without the use of complicated and expensive devices.

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

Fig. 1 is a. diagrammatic view of a compression refrigerating system containingone preferred em- Fig. 2 is-an enlarged diagrammatic view-of the distributing and overload valve shown in Fig. 1; and,

Fig. 3 is an enlarged view of a second embodiment of the distributing and overload valve shown in Fig. 1.

Referring specifically to the drawing for a detailed description of my invention,v numeral- 1- designates an electric motor which drives a compressor 2 which, in turn, pumps refrigerant to a condenser 3." As refrigerant is condensed, it'flows through a conduit 4 to a receiving tank 5.- Refrigerant flows'irom the receiving tank 5 through 1 supply conduit 6 to an'expansion device generallyv designated at I and then to a cooling. device 8.,

wherein the refrigerant absorbs heat and is drawnback to the compressor 2 through a con-' duit 9; *A- fan II, also drivenby the motor I, forces a draft of cooling air over the compressor 2 and condenser}. The motor is supplied with energy through conductors Ita and Ill), and a switch I0 is provided for starting and stopping the operation of compressor 2.

The cooling device 8 is preferably of such dimensions that, as more or less refrigerant is supplied thereto, its eifective cooling area is increased or decreased, and is arranged so that the full cooling area will be presented when the maximum expected load is handled by the cooling device. The cooling effect of the cooling device 8, therefore, is not dependent on the temperature thereof but is dependent on the pounds of refrigerant pumped thereto and evaporated therein per unit of time.

The cooling device 8 is comprised of a plurality of evaporators or coils 12, each having a capillary tube 13 connected to the supply conduit 6, whereby the evaporators are connected in parallel to the supply conduit. Since these tubes have constant lengths and bore diameters, the amount of refrigerant pumped to each coil l2 and, there fore, the refrigerating effect, depends on the resistance of the capillary tubes l3, and the pressure-difference between the supply line 6 and the coils l2, which pressure-difference may be varied in many ways. The capillary tubes I! also act as expansion valves to supply low-pressure refrigerant to the cooling coils i2.

In order to modify the expansion qualities of the capillary tubes l3, a throttle valve I4 is disposed between them and the supply line. It will be noted from Fig.2 that the inlet ends of the capillary tubes are connected to the fitting at the outlet side of the valve ll at points which are spaced closely to each other and which are equally advanced with respect to the flow of refrigerant. It will also be noted from the drawing that the mixture of liquid and vaporous refrigerant discharged from the valve I4 is sub-divided'before the liquid and vapor have appreciable opportunity for separation. This arrangement provides for uniformity of the mixture of liquid and vaporous refrigerant received by the several tubes. The valve includes an orifice IS, a" seat It and a needle II which coacts with the seat l6 and opens and closes the orifice ii. The valve is normally operated by a handle l8 attached by suitable linkage H to the needle II as shown in Fig. 2 By varying the adjustment of the valve ll, the

amount of refrigerant delivered to and distributed by the capillary tubes is changed, or the refrigerant is entirely out off, and the eflective area of the cooling device I is, therefore, also changed.

In order to operate the valve I4 automatically in response to unduly high-pressure in the cooling device I, which may occur therein due to stopping of the compressor and other causes, and thusly prevent overloading of the compressor, a safety device including a Sylphon bellows 2| is connected by a conduit 22 to the interior of the cooling device 8. The closed end of the bellows is connected to. the needle ll so that, when the pressure in the cooling device I rises, the Bylphon 2| expands and forces the needle I! into the valve orifice ll, thus closing or partly closing the valve N and allowing the pump 2 to lower the pressure in the coils l2. Also, when the compressor 2 stops V operating, the high-pressure prevailing in the condenser 8 will force liquid refrigerant into the cooling device 8 through the unrestricted passages of the capillary tubes II. The pressure in' the cooling device I thereupon rises, and the valve I is then closed. Liquid refrigerant in the lowside of the system then vaporize as the temperature thereof rises during the oif-cycle period of the machine; the compressor. therefore, upon starting pumps only gasand breaking of valves due to pumping liquid is prevented.

In a second embodiment of my invention, a second Sylphon bellows 23 replaces the manual adjustment i8, the remainder of the apparatus being the same. The bellows is filled with a suitable expansible liquid such as ethyl chloride and is connected by a conduit 24 to a bulb 25 which is positioned in an enclosure 26 which is to be cooled. The closed end of the bellows 23 is connected through suitable linkage 21 to the needle I! so that, as the temperature in the enclosure 26 is lowered the bellows 23 contracts and forces the needle I! into the orifice l5, thus closing, or partly closing, the valve l4 and thus decreasing or stopping flow of refrigerant delivered to the cooling device.

From the foregoing description, it will be apparent that I have provided a novel control means for a plurality of refrigerating evaporators which are connected in parallel to a common supply conduit, without the use of expensive and complicated devices. It is obvious that the various coils of the evaporator need not be disposed together, and that the bore and length of the capillary tube,,for each coil may vary so that the refrigerating effect of each coil is varied. The capillary tubes provide for distribution and expansion of the compressed refrigerant into a plurality of evaporating coils, and the valve it provides for modifying the expansion action of the capillary tubes, either manually or in response to the temperature of an enclosure to be cooled. The valve It also prevents overloading of the compressor on starting, or when running due to other causes which raise the temperature and pressure of the evaporator to a point where the compressor cannot handle the media to be exhausted therefrom without danger of breaking the compressor valves and otherwise straining the compressor.

While I have shown my invention in two forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be 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 a refrigerating system, a common rei'rigerant supply conduit, a plurality of evaporators, and a plurality of capillary tubes con necting the evaporators in parallel to said capillary tubes for distributing and expanding refrigerant from said common supply conduit to each of said evaporators, and a valve disposed between said supply conduit and said capillary tubes, means for adjusting the valve and means independent of the adjusting means responsive to a characteristic of pressure and temperature of said system for operating the valve.

2. In a refrigerating system, a common reirigerant supply conduit, a plurality of evaporators, a plurality of capillary tubes connecting said evaporators in parallel to said capillary tubes for distributing and expanding refrigerant from said common supply conduit to each of said evaporators, and a valve disposed between said supply conduit and said capillary tubes, means for adjusting the valve and means independent of the adjusting means responsive to the pressure of said evaporator to operate the valve.

3. In a refrigerating system, a common refrigerant supply conduit, a plurality of evaporators, a plurality of capillary tubes connecting the evaporators in parallel to said refrigerant supply conduit for distributing and expanding refrigerant to each of said evaporators, and a manually adjustable valve disposed between said supply conduit and said tubes to modify the action of said tubes, said valve also being provided with'means responsive to a characteristic of pressure and temperature of said system for operating said adjustable valve.

4. In a refrigerating system in which a refrigerant is successively compressed, condensed and evaporated, an evaporator comprising a plurality of coils having separate inlets, an expansion device of constant length and orifice con.- nected to the inlet of each evaporator coil, an adjustable valve for controlling the flow of refrigerant to said expansion devices, and means for adjusting said valve'in response to the pressure of the evaporator.

5. In a refrigerating system in which a refrigerant is successively compressed, condensed and evaporated, an evaporator comprising a plurality of coils having separate inlets, an expansion means of constant length and orifice connected to the inlet of each evaporator coil and an adjustable valve for controlling the flow of refrigerant to said expansion devices, said valve being adjustable both manually and in response to the pressure of the evaporator.

6. In a. refrigerating system in which a refrigerant is successively compressed, condensed and evaporated, an enclosure to be cooled by said system, an evaporator in heat exchange relation with said enclosure, said evaporator comprising a plurality of coils having separate inlets, an expansion means of constant length and orifice connected to the inlet of each evaporator coil,- and an adjustable valve responsive to the temperature of said enclosure for controlling the flow of refrigerant to said expansion devices.

7. In a refrigerating system in which a refrigerant is successively compressed condensed and evaporated, an enclosure to be cooled by said system, an evaporator in heat exchange relation with saidenclosure, said evaporator comprising a plurality of coils having separate inlets, an expansion means of constant length and orifice connected to the inlet of each evaporator coil, and an adjustable valve responsive to the temperature of said enclosure for controlling the flow of refrigerant to said expansion devices, said valve being also manually adjustable.

8. In a refrigerating system in which a refrigerant is successively compressed, condensed and evaporated, an enclosure to be cooled by said system, an evaporator inheat exchange relation with said enclosure, said evaporator comprising a plurality of coils having separate inlets, an expansion means of constant len th and orifice connected to the inlet of each evaporator coil, an adjustable valve responsive to the temperature of said enclosure for controlling the flow of refrigerant to said expansion devices, and mean's'responsive to a pressure-temperature characteristicof said system for also operating said valve.

9. In a refrigerating systemin which a refrigerant is successively compressed, condensed and evaporated, an evaporator comprising a plurality of coils having separate refrigerant inlets, a capillary tube connected to the inlet, of each evaporator 'coil forexpanding refrigerant into the coil, 9. shut-off valve for stopping the flow cf refrigerant through the capillary tubes to the coils, and means responsive to a pressure condition in the coils for operating the shut-off valve.

10. In. a refrigerating system comprising a condenser, a liquid receiver, a plurality of evaporators of the'dry type, a compressor, means for driving the compressonand means for starting and stopping the compressor driving means; the combination of a common refrigerant supply conduit for delivering refrigerant to said evaporators from the liquid receiver, a plurality of capillary tubes connecting the evaporators in parallel to said conduit for distributing and expanding refrigerant into each evaporator, and an automatically operable valve for shutting off the flow of refrigerant from the supply conduit to the evaporators when the compressor is stopped.

11. In a refrigerating system comprising a condenser, a liquid receiver, a plurality of evaporators of the dry type, a compressor, means for driving the compressor, and means for starting and stopping the compressor driving means; the combination of a ,common refrigerant supply conduit for delivering refrigerant to said evaporators from the liquid receiver, a plurality of capillary tubes connecting the evaporators in parallel to said conduit for distributing and expanding refrigerant into each evaporator, and a valve for shutting off the flow of refrigerant from the supply conduit to the evaporators in response to a condition resulting from stopping of the compressor.

12. In refrigerating apparatus, the combination of a compressor, means for driving the compressor, means for starting and stopping the compressor and its driving means, a condenser connected to the outlet of the compressor, a liquid receiver connected to the outlet of the condenser, a plurality of evaporators of the dry type connected to the inlet of the compressor, conduit means for conveying refrigerant from the liquid receiver to the evaporators and inant to the evaporators, and means for shutting off fiow of refrigerant through said conveying means in response to a condition in the apparatus substantially concurrent with stopping of the compressor for preventing accumulation of liquid refrigerant between the capillary tubes and the inlet of the compressor while the latter is stopped.

13. Refrigerating apparatus comprising the combination of a plurality of evaporator elements of the dry type; a common liquid refrigerant supply conduit therefor; and means for expanding liquid refrigerant supplied from said conduit to said evaporator elements, for regulating said expansion and for distributing the same to the several evaporator elements comprising an expansion v'alve anda group of restricted flow-resistance passages, through which valve and group of passages the refrigerant flows in series and in each of which it is partially expanded, and means responsive to anoperating condition of the evaporator elements for controlling said valve, whereby saidvalve and flowresistance'passages together effect expansion of the refrigerant, said valve regulates said .expansion, and saidilow-resistance passages distribute the refrigerant among the evaporator elements, said passages having their entrant ends closely spaced for proper division of refrigerant therebetween.

l4. Refrigerating apparatus comprising the combination of a plurality of evaporator elements arranged to efiect a common cooling action, common liquid refrigerant supply means therefor, and means for distributing refrigerant from said supply means to said evaporator elements and for effecting expansion and regulating the flow thereof, said last-mentioned means including a plurality of fixed restricted passages or orifices connected respectively to the inlet ends of the several evaporator elements for distributing refrigerant thereto, a valve connected between said supply means and said restricted passages or orifices for regulating the flow of the refrigerant, and means operable automatically in response to pressure of the refrigerant in said evaporator elements for regulating said valve.

15. Refrigerating apparatus comprising the combination of a plurality of evaporator elements of the dry type arranged to effect a common cooling action, common liquid refrigerant supply means therefor, and means for distributing refrigerant from said supply means to said evaporator elements and for effecting expansion and regulating the flow thereof, said last-mentioned means including a plurality of fixed elongated passages of restricted flow area connected respectively to the inlet ends of the several evaporator elements for distributing refrigerant thereto, a valve connected between said simply means and said restricted passages for regulating the flow of the refrigerant, and means operable automatically in response to an operating condition of the evaporator elements for regulating said valve, said restricted passages having their entrant ends closely spaced for proper distribution of refrigerant thereto.

16. Refrigerating apparatus comprising the combination of a plurality of evaporator elements arranged to effect a common cooling action, common liquid refrigerant supply means therefor, and means for distributing refrigerant from said supply means to said evaporator elements and for effecting expansion and regulat ing the flow thereof, said last-mentioned means including a plurality of tubes of restricted flow area connected respectively to the inlet ends of the several evaporator elements for distributing refrigerant thereto, a valve connected between said supply means and said restricted tubes for regulating the flow oi' the refrigerant, and means operable automatically in response to pressure of the refrigerant in said evaporator elements for regulating said valve.

1'7. In refrigerating apparatus having a plurality of evaporator elements, an expansion mechanism for said evaporator elements comprising an expansion valve, means for operating said valve in response to an operating condition of the refrigerating apparatus, a distributor fitting connected to the output side of said valve, said fitting having a plurality -of orifice outlets grouped closely together and disposed at points which are equally advanced with respect to the flow of the refrigerant, said outlets communicating respectively with said evaporator elements for distributing refrigerant thereto, the

expansion mechanism being constructed and arranged so that the mixture of liquid and vaporous refrigerant is subdividedby the outlets before the liquid and vapor have appreciable opportunity for separation.

18. In refrigerating apparatus, the combination of a plurality of evaporator elements arranged to effect a common cooling action, common liquid refrigerant supply means therefor, and means for distributing refrigerant from said supply means to said evaporator elements and for effecting expansion and regulating the flow thereof, said last-mentioned means including an expansion valve, means for operating said valve in response to an operating condition of the refrigerating apparatus, a distributor head connected to the outlet side of said valve, a plurality of tubes of restricted flow area extending from said dstributor head to said evaporator elements, the inlet ends of said tubes being connected to said distributor head and arranged in a cluster and at points which are equally advanced with respect to flow of the refrigerant, the distributing and regulating means being constructed and arranged so that the mixture of liquid and vaporous refrigerant is subdivided by the tubes before the liquid and vapor have appreciable opportunity for separation,

FRANK CONRAD.

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