US3013403A

US3013403A - Refrigeration system embodying aircooled condensers

Info

Publication number: US3013403A
Application number: US815039A
Authority: US
Inventors: Whitney I Grant; Erich J Kocher
Original assignee: Vilter Manufacturing LLC
Current assignee: Copeland Industrial LP
Priority date: 1959-05-22
Filing date: 1959-05-22
Publication date: 1961-12-19
Anticipated expiration: 1978-12-19

Description

Dec. 19, 1961 w, 1. GRANT ET AL 3,013,403

REFRIGERATION SYSTEM EMBODYING AIR-COOLED CONDENSERS i Filed May 22, 1959 2 Sheets-Sheet 1 INVENTORS W I. Gen N E. J. Koch' e BY Wmwwzw Dec. 19, 1961 w. GRANT ET AL 3,013,403

REFRIGERATION SYSTEM EMBODYING AIR-COOLED CONDENSERS Filed May 22, 1959 2 Sheets-Sheet 2 INVENTORS' W I. Gen/v7- E. J. KocA-nsz BY [and consin Filed May 22, 1959, Ser. No. 815,039 6 Claims. (Cl. 62-475) This invention relates generally to improvements in the art of refrigeration, and it relates more specifically to improvements in the construction and operation of compound compression refrigerating systems preferably embodying air-cooled condensers operable by air derived from the ambient atmosphere.

The primary object of the present invention is to provide an improved refrigerating system comprising several stages each having a compressor and a cooperating condenser, and which are automatically cooperable with a common receiver for supplying refrigerant to the evaporators so as to maintain a predetermined receiver discharge pressure.

Because of the shortage and resultant high cost of water in various localities it has heretofore been customary to utilize condenser units for the volatile refrigerant being which function independently of atmospheric conditions have heretofore been utilized. While these special devices which are necessarily relatively sensitive, complicated and costly appear to perform their intended function, they utterly fail to take advantage of low temperatures prevailing the ambient atmosphere during certain seasons of the year. i

A system which is in fact capable of automatically taking full advantage of such low air temperatures will obviously operate at considerably lower cost than is possible with these prior installations embodying air-cooled condensers, and may also operate more economically than refrigeration systems utilizing water-cooled condensers. This is especially true is vicinities such as the northern portions of the Mid-West and Eastern areas of the United States, where in spite of the fact that relatively cool water is constantly available from the Great Lakes the winter air temperatures are still far below that of the lake water. For example, the average mean temperature in the vicinity of Milwaukee throughout the year is only 46.8 F. which is considerably below the average lake and well water temperatures, so that any refrigeration installation embodying air-cooled condensers and which is capable of taking advantage of low seasonable temperatures will function most economically.

It is therefore an important object of this invention to provide a simple and automatically functioning refrigerating system utilizing air-cooled condensers, and which takes full advantage of variations in out of doors temperatures. I

Another important object of the present invention is to provide an improved refrigeration installation having two stages each comprising a compressor and an air-cooled condenser, both cooperating with a common receiver for delivering refrigerant to one or more evaporators, and

wherein one stage alone is operable when ambient air temperatures are low but both stages function when said temperatures rise.

A further important object of the invention is to provide a compound compression refrigerating system embodying several condensers operable by atmospheric air, and wherein the initial condenser is capable of completely condensing all of the refrigerant being circulated through the system during cold weather periods, but is automatically assisted in thus condensing said refrigerant whenever warmer Weather conditions prevent the initial condenser from effecting such complete condensation.

Still another important object of this invention is to provide an improved refrigeration installation involving relatively low and high pressure compression stages each including a condenser operable by atmospheric air, and in which the initial low pressure stage functions alone to maintain proper pressures in the receiver which supplies the cooling coils with volatile refrigerant during cold Weather, while the subsequent higher pressure stage functions only when the initial stage fails to properly maintain such receiver pressures due to increases in atmospheric temperatures.

An additional object of the invention is to provide an improved refrigerating system embodying air-cooled condensers, which is easy to install and to maintain, and which functions automatically and economically by taking maximum advantage of cold weather temperatures.

These and other more specific objects and advantages of the invention will be apparent from the following description.

A clear conception of the features constituting the present improvement and of the construction and operation of a typical commercial refrigeration installation embodying the invention, may be had by referring to the drawings accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

FIG. 1 is a diagram illustrating a commercial installation embodying our improved compound compression refrigerating system operable with air-cooled condensers;

FIG. 2 is a central longitudinal vertical section through the intercooler and receiver unit constituting part of the system shown diagrammatically in FIG. 1; and

FIG. 3 is a similar section through the special float actuated valve installed in the second compression stage of the same refrigeration system.

While the invention has been shown and described herein as having been embodied in a two-stage compression refrigerating system operable by air-cooled condensers to cool an insulated storage space, itis not intended to confine its application to such systems; and it is also contemplated that specific descriptive terms employed herein be given the broadest possible interpretation consistent with the disclosure.

' Referring to the drawings, the two-stage compression system shown therein is especially adapted to take full advantage of out-door temperatures, and comprises'in general an evaporator or cooling coil 5; a receiver 6; a main compressor 7 cooperable with an initial air-cooled condenser 8 constituting an initial stage adapted to compress and condense all of the refrigerant gas delivered from the evaporator 5 to the receiver at the proper pressure when the ambient atmospheric temperature is sufficiently low; and an auxiliary compressor 9. cooperable with a second air-cooled condenser 10 and constituting a secondary stage adapted to automatically further compress and condense any excess gaseous refrigerant which the initial stagehas failed to liquefy whenever the ambient atmospheric temperature has risen.

' The'cooling coil 5 is located within an insulated chamber or cooler 12 and is provided in its liquid refrigerant supply line 13 with a thermostatic expansion valve 14 and in its air inlet with an electric motor driven blower 15 for circulating the cold air around the coil; and the upper gaseous refrigerant outlet of this coil is connected to the suction line 16 of the main electrically driven compressor 7. The discharge line 17 of this compressor is provided with a non-return check valve 18 and communicates with the inlet of the initial air-cooled condenser 8 preferably located in the ambient atmosphere as upon the roof 19 of the building in which the cooler 12 is confined. The air-cooled condenser 8 is provided with an electric motor driven fan 20 for drawing ambient air over its heat transfer surfaces and around its propelling motor, and the discharge line 21 of the condenser 8 is adapted to deliver refrigerant by gravity into the bottom of the receiver 6 through a perforated distributing tube 22 extending throughout the length of the receiver shell, as shown in FIG. 2.

The receiver 6 which normally functions merely to confine an abundant supply of liquid refrigerant at a predetermined pressure also functions as an inter-cooler during certain periods as will be later explained, is adapted to deliver liquid refrigerant through an outlet pipe 24 at its bottom and past a valve 25 into the line 13 leading to the evaporator 5, and the line 13 is also provided with a charging and drainage valve 26 which is normally closed, see FIGS. 1 and 2. The receiver 6 is also provided with a liquid level indicating gauge 27, and is additionally provided with an outlet pipe line 28 for gaseous refrigerant at the top of its end remote from the condenser discharge line 21 and with a liquid refrigerant return pipe line 29 intermediate its ends, but these two

pipe lines

28, 29 are active only when the initial air-cooled condenser 8 fails to completely condense the gaseous refrigerant passing therethrough.

The gaseous refrigerant outlet line 23 constitutes the suction line of the auxiliary compressor 9 which is also electrically driven and adapted to deliver refrigerant at considerably higher pressure than prevails in the receiver 6, through its discharge line 31 and past a non-return check valve 32 into the secondary condenser 10. This condenser is also preferably located in the ambient atmosphere on the building roof 19 and is likewise provided with an electric motor driven fan 33 for drawing atmospheric air over its heat transfer surfaces and around its driving motor, and the discharge line 34 of the condenser 10 is connected to the upper portion of the casing 35 of a special float valve assemblage having a liquid refrigerant discharge pipe 36 communicating past a solenoid actuated valve 37 with the refrigerant return line 29 of the receiver 6, see FIG. 3. Located within the casing 35 is a needle valve 38 operable by a float 39 which rides upon liquid refrigerant confined within the casing but shuts off communication with the receiver 6 when the second compression stage is idle. The receiver 6 is also provided with a pressure actuated switch 46 which is automatically operable to start the compressor 9 and the condenser fan 33 and to open the valve 37 so as to cause the second stage to function under certain conditions to be later explained.

When the improved refrigeration system has been constructed and installed as hereinabove described, its operation is substantially as follows: Whenever the outside temperature is low and it is desired to cool the chamber 12, it is only necessary to operate blower and the fan and the main compressor 7 thereby causing the latter to withdraw low pressure refrigerant gas from the evaporator 5 through the suction line 16 and to compress and deliver the gaseous refrigerant to the initial air-cooled condenser 8 through the discharge line 17. The fan 20 of this condenser will then circulate the cold atmospheric air' around the heat transfer surfaces to condense the refrigerant and the resultant liquid refrigerant will gravitate through the line 21 and will enter the receiver 6 through the perforations in the tube 22 which is immersed in an abundant supply of liquid refrigerant initially admitted to the receiver past the valve 26. The pressure within the receiver 6 may be maintained at a predetermined desired value by proper operation of the main compressor 7, and the expansion valve 14 will then function to meter the liquid refrigerant delivered under pressure from the receiver 6 to the evaporator 5 through the line 13, thus causing the initial stage alone to function as a complete refrigeration system as long as the ambient air temperature is sufficiently low to effect substantially complete condensation of all refrigerant being circulated through the evaporator.

During such operation of the system, the auxiliary compressor 9 and the secondary condenser 10 will remain idle, but if the outside air temperature rises sufficiently so that the initial condenser 8 is incapable of condensing all of the gaseous refrigerant delivered thereto by the main compressor '7, then the uncondensed refrigerant gas delivered into the receiver 6 through the perforations in the pipe 22 will bubble up through the liquid refrigerant in the receiver 6 in a manner similar to the action which takes place in an intercooler. The refrigerant gas thus admitted to the receiver 6 accumulates above the liquid and promptly increases the receiver pressure sufficiently to actuate the pressure switch 40 and to thereby start the auxiliary compressor 9 and the fan 33 and to open the solenoid valve 37, whereupon the compressor 9 withdraws the refrigerant vapor through its suction line 28 and further compresses the excess gaseous refrigerant while also increasing its temperature sufficiently to enable the secondary condenser 10 which receives the compressed gas through the compressor discharge line 31, to condense this high temperature gas even when the ambient air temperature is at its highest value. The condensate from the secondary condenser 10 gravitates through the line 34 past the float valve 35 and through the pipe line 29 into the receiver 6, and the installation thus functions as a two-stage compression system except that the liquid refrigerant fed to the evaporator 5 is at an intermediate pressure.

From the foregoing detailed description of the functioning of the improved system, it will be apparent that the present invention in fact provides a simple and effective refrigeration installation preferably embodying air-cooled condensers and which automatically converts from a single stage compression system into a two-stage compression system, and vice versa, dependent only upon changes in atmospheric air conditions. It differs from the ordinary two-stage compression system wherein both stages are constantly active, and is primarily adapted for use in locations where the cost of water for actuating the condensers is high or the use of such Water is restricted, and where the average out-door temperature is low.

The present improved system has the advantages of simplicity and low cost of installation and maintenance, and it also eliminates the necessity of providing complicated water supply and sewer connections. It also functions automatically with minimum attention after being initially properly installed and adjusted, and the improved receiver 6 operates merely as an accumulator or liquid refrigerant storage drum during normal operation under low temperature atmospheric conditions, and as an intercooler Whenever the ambient air temperature rises and the second stage becomes active.

It should be understood that it is not desired to limit this invention to the exact details of construction and operation of the compound compression refrigeration system embodying air-cooled condensers, herein specifically shown and described, since various modifications within the scope of the appended claims may occur to persons skilled in the art.

We claim:

1. In a refrigeration system, an evaporator, a main compressor for withdrawing low pressure gaseous refrigerant from said evaporator, an initial condenser for receiving compressed gaseous refrigerant from said compressor, a receiver for refrigerant delivered from said condenser, an auxiliary compressor operable to withdraw from said receiver only gaseous refrigerant which said initial condenser fails to condense, operation of the auxiliary compressor being responsive to receiver pressure, a secondary condenser for receiving compressed gaseous refrigerant from said auxiliary compressor and for returning said refrigerant in condensed condition to said receiver, and means for delivering liquid refrigerant from said receiver to said evaporator, said auxiliary compressor and said secondary condenser being operable only when gaseous refrigerant is available in said receiver to condense such refrigerant and to return the condensate directly to the receiver.

2. In a refrigeration system, an evaporator, a main compressor for withdrawing low pressure gaseous refrigerant from said evaporator, an initial atmospherical- 1y air cooled condenser for receiving compressed gaseous refrigerant from said compressor, a receiver for refrigerant delivered from said condenser, an auxiliary compressor operable to withdraw from said receiver only gaseous refrigerant which said initial condenser fails to condense, operation of the auxiliary compressor being responsive to receiver pressure, a secondary atmospherically air cooled condenser for receiving compressed gaseous refrigerant from said auxiliary compressor and for returning said refrigerant in condensed condition to said receiver, and means for delivering liquid refrigerant from said receiver to said evaporator, said auxiliary compressor and said secondary condenser being operable only when gaseous refrigerant is available in said receiver to condense such refrigerant and to return the condensate directly to the receiver.

3. In a refrigeration system, an evaporator, a relatively low pressure compressor for withdrawing spent gaseous refrigerant from said evaporator, an initial condenser for receiving compressed gaseous refrigerant from said compressor, a receiver for refrigerant delivered from said condenser, a higher pressure compressor operable in response to receiver pressure to withdraw from said receiver only gaseous refrigerant which said initial condenser fails to condense, a secondary condenser for receiving compressed gaseous refrigerant from said higher pressure compressor and for returning said refrigerant in condensed condition to said receiver, and means for delivering liquid refrigerant from said receiver to said evaporator, said higher pressure compressor and said secondary condenser being operable only when gaseous refrigerant is available in said receiver to condense such refrigerant and to return the condensate directly to the receiver.

4. In a refrigeration system, an evaporator, a relatively low pressure compressor for withdrawing spent gaseous refrigerant from said evaporator, an initial atmospherically air-cooled condenser for receiving compressed gaseous refrigerant from said compressor, a receiver for refrigerant delivered from said condenser, a higher pres sure compressor operable in response to receiver pressure to withdraw from said receiver only gaseous refrigerant which said condenser fails to condense, a secondary atmospherically air-cooled condenser for receiving compressed gaseous refrigerant from said higher pressure compressor and for returning said refrigerant to said receiver, and means for delivering liquid refrigerant from said receiver to said evaporator, said higher pressure compressor and said secondary condenser being operable only when gaseous refrigerant is available in said receiver to condense such refrigerant and to return the condensate directly to the receiver.

5. In a refrigeration system, an evaporator, a receiver, main and auxiliary independently operable refrigerant compressors each communicating with an independent air-cooled condenser both of which communicate with said receiver, means for conducting spent gaseous refrigerant from said evaporator into said main compressor, means for conducting from said receiver into said auxiliary compressor gaseous refrigerant which the communicating condenser of said main compressor fails to condense, and means for delivering liquid refrigerant from said receiver to said evaporator, said auxiliary compressor being operable in response to receiver pressure only when gaseous refrigerant is available in said receiver to condense such refrigerant and to return the condensate directly to the receiver.

6. In a refrigeration system, an evaporator, an intercooler receiver, rnain and auxiliary refrigerant compressors each communicating with an independent atmospherically air-cooled condenser both of which communicate with said receiver, operation of said auxiliary compressor being responsive to receiver pressure, a conduit for conducting low pressure gaseous refrigerant from said evaporator into said main compressor, a conduit for conducting from said receiver into said auxiliary compressor gaseous refrigerant which the communicating condenser of said main compressor head fails to condense, means for delivering liquid refrigerant from said receiver to said evaporator, and means for effecting actuation of said auxiliary compressor only when gaseous refrigerant is available in said receiver to condense such refrigerant and to return the condensate directly to the receiver.

References Iited in the file of this patent UNITED STATES PATENTS