US2005834A - Refrigeration - Google Patents

Description

June 25, 1935. H. M. WILLIAMS REFRIGERATION Filed Nov. 30, 1931 ATTORNEYS Patented June 25, 1935 UNITED STATE ATENT OFFICE REFRIGERATION Application November 30, 1931, Serial No. 577,940

5 Claims.

This invention relates to refrigeration and more. particularly to refrigeration systems in which refrigerants and lubricants completely miscible with each other are used.

Refrigeration systems using a miscible refrigerant and lubricant, as heretofore operated, have been provided with special means for insuring the return of lubricant from the evaporator to the compressor. It has always been considered to be a problem to return lubricant to the compressor when the lubricant which is scattered or held in solution throughout the entire body of liquid refrigerant contained in the evaporator. For this reason special means have been provided for introducing portions of the liquid from the evaporator into the gaseous discharge from the evaporator on its way to the compressor. For this purpose it has been customary to provide a submerged inlet from the liquid in the evaporator to the gaseous return line in order to introduce lubricant carrying liquid into the returning gaseous refrigerant. It has also been customary to provide means for raising the liquid level in the evaporator to a point where lubricant carrying liquid refrigerant is introduced into the gas return line. I have discovered that it is possible to insure the proper return of a miscible lubricant from the evaporator to the compressor without the necessity of using any such special means, and it is to this feature that my invention is directed.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing:

The figure is a diagrammatic representation of a system in which my invention may be practiced.

A refrigeration system embodying features of my invention includes, in general, a compressor [0, a condenser H and an evaporator l2 in refrigerant-lubricant circulating relationship. The compressor discharges compressed refrigerant through a line I3 to the condenser H. The condensed refrigerant is discharged from the condenser I I into a receiver [4, or may be directly discharged either from the condenser or receiver through the line IE to the evaporator l2. The evaporator I2 is provided with means for maintaining a predetermined fixed liquid level and is also provided with means for withdrawing gaseous refrigerant and returning the same to the compressor. To this end, the evaporator may be provided with a liquid refrigerant inlet valve fixture l6 provided with a float I! which controls the admission of liquid refrigerant from the line 15 and maintains a predetermined fixed liquid level at [8. The gaseous refrigerant may be removed from the evaporator [2 through the medium of a gas funnel I9 which discharges through a valve fixture 20 to the gaseous refrigerant line 2! which returns the gaseous refrigerant to the compressor [0. If 1 desired the apparatus may be automatically controlled, for instance, by a bellows 22 connected to the line 2i and which operates a snap switch 23 which in turn controls the operation of a motor 24 which drives the compressor It]. In 1 this manner the operation of the compressor is governed in accordance with pressure temperature conditions in the evaporator.

Apparatus similar to that heretofore described has been in common use, but it has been heretofore thought to be suitable only for a refrigerant-lubricant combination in which the refrigerant and lubricant are only slightly or almost negligibly miscible in each other. A mixture of S02 and oil has been used, and such a mixture forms two liquid phases in the evaporator, the upper one being very rich in lubricant and the, lower one being very rich in refrigerant. This natural separation into a rich upper lubricant layer has always been considered necessary for the successful operation of such an apparatus. I have discovered that such an apparatus can be successfully, and even more satisfactorily, operated with a lubricant-refrigerant mixture in which the constituents are completely miscible with each other while in the liquid phase at the normal evaporator operating temperature. Thus in an apparatus of the character heretofore described, for example, I have found that a mixture of methyl chloride and mineral oil can be successfully used with very satisfactory return of lubricant to the compressor. For a small domestic unit, a refrigerating system may be provided in which the evaporator has a boiler 30 with a diameter of 3 inches. The top of, or an opening into, the funnel [9 may be so arranged that it is at a suitable distance from the top of the liquid to insure return of lubricant, and such a distance may be substantially 1 inch above the fixed liquid level l8. If desired a bafile 3| may be interposed between the liquid and the funnel l9.

The boiler 30 may be provided with means for evaporating the liquid refrigerant in the evaporator and for bubbling it through the surface of the liquid in the evaporator. To this end, the

boiler 30 may be provided with depending pipes 32, these pipes being, for example, inches internal diameter copper tubes, and these copper tubes may have the central lines of their junctions with the boiler 3U substantially 1 inch below the fixed liquid level id. The pipes 32 may cool one or more ice cube tray sleeves 33 in the welllrnown manner.

The refrigerating system charged as described above, with a completely miscible mixture, such as a mixture of a halogen hydrocarbon derivative and a mineral oil, operates very satisfactorily and automatically maintains satisfactory concentrations wherever liquid bodies are maintained in the system. The solution in the evaporator l2 automatically remains very concentrated in refrigerant without an objectionable amount of lubricant. The solution 2 in the compressor automatically remains concentrated in lubricant and weak in v refrigerant, while the solution 25 in the receiver it automatically remains substantially of the same concentration as the discharge from the compressor. lhe exact reason for such successful operation is not fully understood, but i have discovered that by correctly calibrating'the dis.- tance between the outlet of the evaporator and the liquid level, such as by adjusting the float, a successful return of lubricant from the evaporator to the compressor is insured. This distance may, more conveniently, be a fixed distance above the liquid level and need not be changed after it has been calibrated. Such an apparatus when charged with a completely misciblerefrigerantlubricant mixture has proven to be superior from an efliciency standpoint. This superiority, E at present believe, is in no small measure due to the superior lubricant return from the evaporator to the compressor obtained by my invention.

While the form of embodiment as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow. 1 I

What is claimed is as follows: 1. In a refrigerating system wherein a compressor, condenser and evaporator are charged with a refrigerant and a lubricant. completely miscible with each other wherever they occur in the liquid phase in the system, the method of returning lubricant from the evaporator to the.

compressor which comprises maintaining a body of liquid refrigerant and lubricant in completely miscible condition in said evaporator at a predetermined fixed liquid level and withdrawing gaseous refrigerant to said compressor only from above said liquid level at a height to permit return of lubricant to the compressor along with said gaseous refrigerant without withdrawal of liquid below the surface of said fixed liquid level.

2. In a refrigerating system wherein a compressor, condenser and evaporator are charged with a refrigerant and a lubricant completelymiscible with each other wherever they occur in the liquid phase in the system, the method of returning lubricant from the evaporator to the compressor which comprises maintaining a body of liquid refrigerant and lubricant in .completely miscible condition in said evaporator at a predetermined fixed liquid level, evaporating'refrigerant from said body and bubbling it through the of liquid refrigerant and lubricant in completely miscible condition in said evaporator at a predetermined fixed liquid level and withdrawing gaseous refrigerant to said compressor only fromabove said liquid level at a fixed height to permit return of lubricant to the compressor along with said gaseous refrigerant without withdrawal of liquid below the surface of said fixed liquid level.

l. In a refrigerating system wherein a compressor, condenser and evaporator are charged with a refrigerant and a lubricant completely miscible with each other wherever they occur in the liquid phase in the system, the method of re turning lubricant from the evaporator to the compressor which comprises maintaining a body ofliquid refrigerant and lubricant in completely miscible condition in said evaporator at a predetermined fixed liquid level, evaporating refrigerant from said body and bubbling it through the surface of said liquid level and withdrawing gaseous refrigerant to said compressor only from above said liquid level at a fixed height to permit return of lubricant to the compressor along with said gaseous refrigerant without withdrawal of liquid below the surface of said fixed liquid level.

5. A refrigerating system. comprising a compressor, condenser and evaporator in refrigerantlubricant circulating relationship, said evaporator being provided with a liquid refrigerant inlet having a control automatically responsive to the liquid level in said evaporator and having a gaseous refrigerant outlet above the level of liquid refrigerant in said evaporator, said outlet having no connection below the liquid level, said system being charged with a refrigerant and a lubricant completely miscible with each other in the liquid 1 phase at the normal evaporator operating temperatures.

HARRY M. WILLIAMS.

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