US2513361A - Method and system for producing low-temperature refrigeration - Google Patents

Description

July 4, 1950 A. w. RAUSCH METHOD AND SYSTEM FOR PRODUCING LOW TEMPERATURE REFRIGERATION Filed Nov. 1, 1944 I INVEN TOR. A zza i ezr flffgawsc AT GRMFV Patented July 4, 1950 METHOD AND SYSTEM FOR PRODUCING LOW-TEMPERATURE REFRIGERATION Andrew W. Rausch, Ridgewood, N. J., assignor to Specialties Development Corporation, Bloomfield, N. J a corporation of New Jersey Application November 1, 1944, Serial No. 561,375

Claims.

The present invention relates to refrigeration, and more particularly to a method of and a system for producing low temperature refrigeration.

Heretofore, in the provision of refrigeration it has been customary to .recompress the expanded refrigerant vapor by utilizing one or more reciprocating piston type compressors. In producing low temperature refrigeration adapted to provide temperatures between about 100 F. and about 250 F., the refrigerant must be expanded to a very low pressure and the refrigerant so expanded has a very large specific volume, which increases greatly as the pressure of the refrigerant is reduced.

In providing temperatures within the foregoing range, it has been found that the compression means heretofore known can be utilized only with great difliculty, because the initial compressor is required to compress a large volume of tenuous low pressure and low temperature refrigerant. As the pressure of the refrigerant to be compressed approaches a low value, for example, about one pound per square inch absolute, the volumetric efficiency of the compressor is sharply decreased to such an extent that the compressor is unable to handle a practical load.

An object of the present invention is to provide an eflicient system and method of producing low temperature refrigeration within the temperature range specified herein.

Another object is to provide a system and method of the foregoing character wherein means are provided at the initial stage of compression which are capable of handling a large volume of tenuous, low pressure, low temperature refrigerant vapor in an efficient manner.

Another object resides in the utilization of a portion of compressed refrigerant to effect initial compression of refrigerant vapor having a very low temperature and pressure.

Another object is to provide a multi-stage compression system for producing low temperature refrigeration wherein a jet pump type compressor is utilized at the initial stage of compression.

A further object is to provide a system for producing low temperature refrigeration wherein a multistage jet pump type compressor is utilized.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and

2 various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

Preferred embodiments of the invention have been chosen for purposes of illustration and description and are shown in the accompanying drawing, forming a part of the specification, wherein: v

Figure 1 is a diagrammatic view of a low temperature refrigeration system, illustrating an embodiment of the invention.

Figure 2 is diagrammatic View of a low temperature refrigeration system, illustrating another embodiment of the invention.

Figure 3 is a fragmentary diagrammatic view of a portion of a system illustrating a further embodiment of the invention.

Referring to the drawing, there is shown a refrigerating system for removing heat from a fluid, such as air, to reduce the temperature of the fluid to between about F. and about 250 F. and to prepare the same for liquefaction. In general, the system comprises means for compressing a refrigerant in a plurality of stages, means for condensing the refrigerant, heat exchange means, such as an evaporator, wherein the refrigerant is expanded to a. low pressure and a correspondingly low temperature to effect removal of heat from the fluid to be refrigerated, and means operated by high pressure refrigerant for increasing the pressure and the temperature of the expanded refrigerant prior to compression thereof.

The refrigerant utilized, preferably, is of the fluorinated-halogenated hydrocarbon type adapted to expanded to provide the low temperatures desired.

With reference to Figure 1, the compressing means comprise a compressor III of the reciprocating piston type for receiving refrigerant having a low pressure and compressing the same to a higher pressure, and a second compressor II, also of the reciprocating piston type for receiving the refrigerant from the compressor I0 and compressing the same to the desired pressure.

A water cooled condenser I2 receives the refrigerant from the output side of the compressing means, that is, the output side of the compressor II and effects reduction in temperature and liquefaction of the refrigerant without reduction in pressure. A conduit or pipe I! conducts the refrigerant to an evaporator l5 wherein the refrigerant is expanded to a very low pressure by means of an expansion valve It in the conduit l4 and wherein a coil or heat exchange element I1 is located in heat exchange relationwith the refrigerant for circulating the fluid from which heat is to be removed by the cooled expanded refrigerant.

For purposes of illustration, but without any intention of limiting the invention to the pressures and temperatures specified herein, the re-' frigerant may be compressed to about 140 pounds per square inch absolute while attaining a temperature of about 220 F. The condenser may be designed to effect reduction of the temperature of the compressed refrigerant to about 70 F., at which temperature the refrigerant is expanded into the evaporator to a pressure of about one pound per square inch absolute while attaining a temperature of about -l20 F.

The refrigerant vapor having the foregoing characteristics can be readily handled by compressing means of the jet pump type adapted to compress the refrigerant vapor sufliciently to enable the same to be handled thereafter by multi-stage reciprocating piston type compressors or the like. For the foregoing purpose, a jet pump 20 is provided which comprises a suction chamber 2|, a nozzle 22 connected to a conduit 26 for supplying high pressure refrigerant as about to be described, an inlet conduit 25 through which the expanded refrigerant vapor from the evaporator is supplied to the suction chamber, a tube 26 wherein the expanded and high pressure refrigerant are mixed and then diffused, and a discharge conduit 21 connected to the tube 25 for conducting refrigerant to the intake side of the initial stage of compression, represented by the compressor Ill.

The present invention contemplates the use of high pressure refrigeration vapor as the motive fluid for the jet pump. In order to accomplish this, a conduit 30 connects the supply conduit 24 to the output side of the compressing means, at 3|, where high pressure refrigerant vapor is available. If desired, a valve 32 may be connected in the conduit 30 for regulating the flow of refrigerant to the jet pump 20.

A sufficient quantity of refrigerant is supplied to the nozzle of the jet pump which will produce a velocity to withdraw expanded refrigerant from the evaporator at a desired rate and to increase the pressure of the expanded refrigerant to supply refrigerant from the jet pump to the compressor l at a pressure of between 2 to pounds per square inch.

It will be appreciated that, by increasing the pressure of the expanded refrigerant from one pound to four pounds per square inch absolute, for example, the specific volume of the refrigerant is reduced to about one-quarter of its original volume whereby handling thereof by the compressor I0 is facilitated.

Also. by use of a jet pump wherein the motive fluid has a higher temperature than the expanded refrigerant leaving the evaporator, the temperature of the refrigerant supplied to the compressor I0 is considerably higher. For example, the temperature of the refrigerant supplied to the compressor III will be about -40 F. whereby freezing of the compressor, structural failure due to extreme cold, and lubricating problems are eliminated.

Referring more particularly to Figure 2, there is shown a low temperature refrigeration system which is similar to the system shown in Figure 1, except that multi-stage jet compression means are provided for supplying refrigerant from the evaporator to the initial stage compressor. The

' 20a and further increasing its pressure before delivering the same to the compressor l0.

Motive fluid is supplied to the jet pump 20a by a conduit 24c connected to the conduit 30 which is connected to the output side of the compressing means at 3|, and motive fluid is supplied to the jet pump 20b by a conduit 2411 connected to the conduit 30. The conduits 24a and 24b may be provided with valves 32a and 32b, respectively, for regulating the flow of refrigerant to the jet pumps.

The foregoing described system may be advantageously utilized where the refrigerant is expanded to a pressure of about A pound per square inch absolute to attain a temperature in the evaporator of about 155 F. The jet pump 20a serves to increase the pressure of the refrigerant to about one pound per square inch absolute, while the second jet pump 20b serves to increase the pressure of the refrigerant from about one to between about 2 and about 5 pounds per square inch absolute.

In Figure 3, modified compressing means are illustrated which may be utilized in connection with the systems shown in Figures 1 and 2. A rotary compressor or centrifugal pump 35 is substituted for the reciprocating piston-type compressor I0, which acts as a booster to increase the pressure of the refrigerant from about 3 to about 6 pounds per square inch absolute, thus conditioning the refrigerant to make it feasible to complete compression thereof by a single reciprocating piston type compressor The use of a rotary compressor is made feasible by reason of the fact that the refrigerant delivered from the jet pump is at a temperature which will not cause lubrication or freezing difficulties. A relatively small rotary compressor is adapted to handle a large volume of refri erant and is adapted to take the place of a more bulky reciprocating type ci mpressor.

From the foregoing description it will be seen that the present invention provides an improved system and method of operation thereof which renders feasible low temperature refrigeration, adapted to provide temperatures between about F. and 250 F. Such low temperature refrigeration is useful for many purposes. For example, in the processing of air preparatory to liquefaction and separation thereof into its constitutcs, low temperature refrigeration can be advantageously utilized to extract heat energy from the air. Also, low temperature refrigeration can be employed in dewaxing petroleum hydrocarbons and the like.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the'spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

It is also to be understood that the following claims are intended to cover all the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim:

refrigeration, comprising compressing refrigerant, condensing compressed refrigerant, expanding all of the condensed refrigerant to a low pressure, utilizing high pressure refrigerant for entraining all of the expanded refrigerant to increase the pressure of all of the refrigerant dircctly after expansion thereof, and directly recompressing the refrigerant.

directly 2. A method for producing low temperature refrigeration, comprising compressing refrigerant in a plurality of stages, condensing a portion of the compressed refrigerant, expanding all of the condensed refrigerant to a low pressure, utilizin the remainder of the compressed refrigerant for entraining all of the expanded refrigerant to increase the pressure of the refrigerant directly after expansion thereof, and directly recompressing the refrigerant.

3. A method for producing low temperature refrigeration, comprising compressing refrigerant, condensing compressed refrigerant, expanding the refrigerant to a pressure between about A, and about one pound per square inch absolute, utilizing high pressure refrigerant for entraining the expanded refrigerant to increase the pressure of the refrigerant after expansion thereof, and directly recompressing the refrigerant.

4. A method for producing low temperature refrigeration, comprising compressing refrigerant, condensing compressed refrigerant, expanding the refrigerant to a pressure between about and about one pound per square inch absolute to attain a temperature of between about 100 F. and about 250 F. utilizing high pressure refrigerant for entraining the expanded refrigerant to increase the pressure of the refrigerant after expansion thereof, and directly recompressing the refrigerant.

5. A method for producing low temperature refrigeration, comprising compressing refrigerant, condensing compressed refrigerant, expanding the refrigerant to a low pressure, utilizing high pressure refrigerant for entraining the expanded refrigerant to increase the pressure thereof to between about 2 and about 5 pounds per square inch absolute, and directly recompressing the refrigerant.

6. A method for producing low temperature refrigeration, comprising compressing refrigerant, condensing compressed refrigerant, expanding the refrigerant to a pressure between about /5 and about one pound per square inch absolute, utilizing high pressure refrigerant for entraining the expanded refrigerant to increase the pressure thereof to between about 2 and about 5 pounds per square inch absolute, and directly recompress ing the refrigerant.

7. A method for producing low temperature refrigeration, comprising compressing refrigerant, condensing compressed refrigerant, expanding the refrigerant to pressure between about /5 and about one pound p r quare inch absolute to attain a temperature of between about 100 F. and about 250 F., and utilizing high pressure refrigerant for entraining the expanded refrigerant to increase the pressure thereof to between about 2 and about 5 pounds per square inch absolute, and directly recompressing refrigerant.

8. A method for producing low temperature refrigeration, comprising compressing refrigerant, condensing a portion of the compressed refrigerant, expanding all of the condensed refrigerant to alow pressure, utilizing the remainder of the compressed refrigerant for successively entraining the expanded refrigerant in a plurality of stages to increase the pressure of the refrigerant directly after expansion thereof, and directly thereafter recompressing the refrigerant.

9. A method for producing low temperature refrigeration, comprising compressing refrigerant, condensing compressed refrigerant, expanding the condensed refrigerant to a low pressure, and utilizing high pressure refrigerant for successively entraining the expanded refrigerant in a plurality of stages to increase the pressure thereof to between about 2 and about 5 pounds per square inch absolute.

10. A method for producing low temperature refrigeration, comprising compressing refrigerant, condensing compressed refrigerant, expanding the condensed refrigerant to a pressure between about V and about one pound per square inch absolute to attain a temperature of between about -l00 F. and about -250 F., and utilizing high pressure refrigerant for successively entraining the expanded refrigerant in a plurality of stages to increase the pressure thereof to between about 2 and about 5 pounds per square inch absolute.

11. A system for producing low temperature refrigeration, comprising mechanical means for compressing refrigerant having an inlet and an outlet, a condenser having an inlet connected to the outlet of said compressing means and having an outlet, an evaporator having an inlet connected to said condenser outlet and having an outlet, means in heat exchange relation with said evaporator, an expansion valve between said exaporator inlet and said condenser outlet, jet pump means having an inlet connected to said evaporator outlet and having an outlet connected to the inlet of said compressing means, and a conduit connected to said .iet pump means and between the outlet of said compressing means and said condenser inlet for delivering refrigerant to said jet pump means serving as working fluid for operating the same.

12. A system for producing low temperature refrigeration, comprising a primary stage mechanical compressor having an inlet and an outlet, a secondary stage mechanical compressor having an inlet connected to said primary stage compressor outlet and having an outlet, a condenser having an inlet and an outlet, a conduit connecting said secondary stage compressor outlet and said condenser inlet, an evaporator having an inlet and an outlet, means in heat exchange relation with said evaporator, a conduit connecting said condenser outlet and said evaporator inlet, an expansion valve in said last mentioned conduit, a jet pump having an inlet connected to said evaporator outlet, an outlet connected to said primary stage compressor and a working fluid inlet, and a conduit connected to said first mentioned conduit and said working fluid inlet of said jet pump.

13. A system for producing low temperature refrigeration, comprising mechanical means for compressing refrigerant having an inlet and an outlet, a condenser having an inlet and an outlet, a conduit connecting said compressing means outlet and said condenser inlet, an evaporator having an inlet and an outlet, means in heat exchange relation with said evaporator, a conduit connecting said condenser outlet and said evaporator inlet, an expansion valve in said last mentioned conduit, a primary stage jet pump having an inlet connected to said evaporator outlet, an outlet, and a working fluid inlet, a, secondary stage jet pump having an inlet connected to said primary stage jet pump outlet, an outlet connected to said compressing means inlet, and a working fluid inlet, and conduit means connecting said working fluid inlets to said first mentioned conduit.

14. A system for producing low temperature refrigeration, comprising mechanical means for compressing refrigerant having an inlet and an outlet, a condenser having an inlet and an outlet, a conduit connecting said compressing means outlet and said condenser inlet, an evaporator having an inlet and an outlet, means in heat exchange relation with said evaporator, a, conduit connecting said condenser outlet and said evaporator inlet, an expansion valve in said last mentioned conduit, :1 primary stage jet pump having an inlet connected to said evaporator outlet, an outict, and a working fluid inlet, a secondary stage jet pump having an inlet connected to said primary stage jet pump outlet, an outlet connected to said compressing means inlet, and a working fluid inlet, conduit means connecting said working fluid inlets to said first mentioned conduit, and valve means in said conduit means for independently regulating the supply of working fluid to said working fluid inlets.

15. A system for producing low temperature refrigeration, comprising means for compressing refrigerant in a plurality of stages including a rotary compressor and a reciprocating compressor for compressing the refrigerant to a higher pressure having its intake side connected to the output side of said rotary compressor, refrigerant condensing means connected to the output side of said reciprocating compressor, evaporator means, conduit means connecting one side of said evaporator means to said condensing means'means in said conduit means for expanding the refrigerant to a low pressure, a jet pump having its intake side connected to the other side ofsaid evaporator means and having its output side connected directly to the intake .side of said rotary compressor thereby to withdraw low pressure refrigerant vapor from said evaporator means and deliver the vapor to said compressing means, and means for delivering high pressure refrigerant to said jet pump to serve as working fluid for operating the same.

ANDREW W. RAUSCH.

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

UNITED STATES PATENTS Number Name Date 7 1,570,995 Lony Jan. 26, 1926 2,014,701 Seligmann Sept. 17, 1935 2,172,408 Randel Sept. 12, 1939 2,200,138 Von Sauer a- May 7, 1940 2,344,215 Soling et al Mar. 14, 1944 2,363,273 Waterfill Nov. 21, 1944- FOREIGN PATENTS Number Country Date 396,878 Germany June 11, 1924

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