US2154136A - Fluid circulation system - Google Patents

Description

April 1939. M. P. PARCARO FLUID CIRCULATION SYSTEM Filed March 31, 1936 p W a B. W w/u F a a 40 W w m m g 5 9 m 6 lllil M w 8 2 w 5 y w 5 I L IN V EN TOR. M/CH/IEL R PARC/720 ATTORNEY.

Patented Apr. 1939 umreo'srArr-zs PATENT OFFICE Newark, N. 1., a corporation of Delaware tlon,

Application March :1, 1930, Serial No. use:

1 Claims. (01. 02- 15) This invention relates to fluid circulation, and more particularly to the .flow of fluid through refrigerating systems.

The general object of the invention is to provide an improved method of and means for controlling the capacity of fluid compressors.

Another object of the invention is to provide for the reduction of the capacity of a compressor in such manner that the power input to the compressor is correspondingly reduced. In the past, various devices and methods have been devised for reducing compressor capacity. However, they have quite generally proven unsatisfactory, either because-of high cost, me liability, or the setting up of ineflicient operating conditions. 5

It is another object oi the invention to provider a system of compressor capacity control which is inexpensive and reliable, and which results in eflicient operating aonditions, thus overcoming the shortcomings of devices heretofore known.

It is another object of the invention to provide a system of compressor capacity control which may be applied to the various cylinders of a' multi-cylinder compressor and/or to a plurality of compressors operating in parallel arrangement. A feature of the invention resides in reducin the capacity of a multicylinder compressorby recirculating throughthe compressor gas pass ing from one or more cylinders of the compressor, while gas passing from the remaining cylinder or cylinders is disposed of in the normal way. The cylinders or compressors from which gas is recirculated cease to deliver high pressure gas to the discharge reservoir of the apparatus, but

deliver gas at the suction pressure of the apparatus. 'I'hese'cylinders, therefore, do no work of compression. Accordingly, the power consumption of the entire apparatus varies very functioning in the normal way. Thus, for example, if one cylinder of a two cylinder conipressor is cut out of service (that is, if fluid from. one cylinder is recirculated through the com-. pressor), the power necessary'to drive'the compressor will approximate one-half of the power required when both of the cylinders are operating in the normal manner.

Another feature of the invention resides in 50.the provision of means for preventing the recirculation to the compressor intake of. high pressure gas delivered by a cylinder operating in the normal way, while lowpressure gas delivered by another cylinder is returned to the compressor intake. r a

e vi

A invention; and

:from cylinder 1 to line H, but does not permit flow in a reverse direction.

nearly in proportion to the number ot cylinders Another feature oi 'the invention resides in automatically controlling the reduction of the capacity of a compressor.- The control means may operate responsive to variations in the pressure or temperature or fluid supplied to the com- 6 pressor, or in any other suitable manner.

' Other'objects, features and advantages of the invention will be more apparent from the following description to be read in connection with the accompanying drawing in which: m

Fig. 1 illustrates a mechanical refrigeration system embodying the invention; V

Fig. 2 illustrates a modification of the invention; 7 r

Fig, 3 illustrates a further modification of the M Fig. 4 illustrates a modified ement of the invention.

. Referring now to the drawing, 5 designates a compressor having cylinders 6 and i. A suction line 8 provides communication between the compressor 5 and the evaporator 16 of a refrigeration system including the compressor 5, condenser I7 and expansion valve. It. Fluid passing from cylinder 6 flows through pipe 9, and 25 fluid passing from cylinder lilows through pipe l0. Pipes S'and I0 communicate with'line ii, leading to the condenser H. A bypass line I! connects pipe l0 and suction line 8. Bypass line I! is provided with a valve l3. Pipe III is provided with a check valve ll, disposed beyond the connection of bypass line I! in the line of normal fluid flow.- Check valve ll permits fluid to pass Under normal ioad'conditions, suction gas passes into cylinders! and I through suction line 8 and is discharged alternately into. discharge lines 9 and II, whence it passes to the condenser l1 through .line II. Under such conditions stop valve II in bypass line I2 is closed; check valve I! offers no appreciable resistance to' flow of gas through pipe II to line II; and.

the operation'of the apparatus is thatoi a conventional two-cylinder compressor.

. When the load on the refrigerating system is reduced,"thef gas pressure in suction-line I ialls. When the pressure has reached a predetermined low point, pressurestat ii in suction line I causes valve It to thus providing a free path for the gas discharged by each compression stroke of cylinder I to return .to suction line 8. Check valve 14, by its self closing action, prevents high pressure gas from discharge lines 9 and II from entering bypass line It. 55

Under low-load operating conditions, only cylinder 6 compresses gas from the suction presplaced at approximately the suction pressure prevailing in suction line 8. The cylinder 1 does practically no compression and therefore requires practically no power for its operation. Thus, while the capacity of the compression apparatus has been reduced by one-half, the

power input has also been reduced to approximately the same extent, or in direct proportion to the reduction in compressor capacity.

It will be observed that the recirculated gas is supplied to the-feed line'which. serves both of the cylindersof the compressor. same gas is not continuously recirculated, as would be they case if the gas discharged from a cylinder were re-supplied' to that cylinder only.

Accordingly, excessive heating of the compressor,

which would result'irom the continuous recirculation of the same gas, is avoided.

Although valve 83' is illustrated and described as being under the control of pressurestat .li, applicant does not restrict himself to this type of control. Valve I! may be controlled manually, by a thermostat responsive to the suction temperature oi the fluid to be compressed, by a thermostat responsive to temperatures created by the evaporator II, or in any manner. d

Although this description has been directed to a two cylinder compressor, it is to be understood that the invention may be-used in connection with a compressor having three, or more cylinother suitable ders. In such 'case, two or more bypass lines 12' wouldbe used, the valves in the difierent bypass lines .operating successively tounload diiterent cylinders of the compressor. Such an arrange! ment is illustrated in Fig. 4, m which a third cylinder designated la, is provided. Cylinder "la is provided with a discharge line "a, bypass line l2a,valve "a and mock valve a, respectively similar to the elements II, II, II and II associated with cylinder 1. The valves I! and lac operate successively, so that under different operating conditions different numbers of the cylinders will be functioning in the normaimanner. Irrespective of the number cylinders.

the power input to the compressor will vary approximately in proportion to the actual work of compression done by-the active cylinders. Ii. it is desired to completely unload the compressor without interrupting the operation pr the compressor driving means, each cylinder of the compressor may have a by-pass line associated therewith,

By the provision of by-pass lines and valves corresponding to elements l2, II and l4,the "capacity of compressor apparatus comprising two .or more compressors operating in. parallel arrangeinent may be varied in accordance with load requirements. v L

In the modification of the invention illustrated in Fig. 2, valves=13 and 14 are replaced by a three way valve 2|). Valve 20' is controlled by instrument I! in substantially the same wafythat valveii of Fig. l is controlled.by instrument Ii. Valve inder 1 into pipe I! or into pipe [0. When the valve delivers fluid from cylinder I to pipe 12, it

Thus the and H from entering into pipe l2. When valve 20 delivers fluid from cylinder 1 to pipes in and i i, it effectively prevents flow through pipe l2.

In operating air conditioning systems, it is sometimes desirable to cool or to cool and dehumidity air and then to reheat the air-before supplying it to the enclosure served by the system. Such operation is frequently adopted where precise control of relative humidity is important. In the modification of the invention illustrated in Fig. 3, applicant provides a method of and a systen: for reheating cooled air by heat exchange with hot gases passing from a refrigerant com-- ment of Fig. 1 may be substituted for-the three way valve 20. As in Fig. 2, the valve 2| is under the control of a suitable contFol instrument I5. .This may, for example, be a hygrostat or thermostat in the air stream, or in the enclosure served by the conditioningisystem, or any other instrument positioned at any pointin the air condition-' ing system, or in the enclosure served by the system. Unde certain operating conditions the valve 20 will ca fluid from cylinder 1 to pass to pipe H and thence to condenser l1. However, if the relative humidity of the air in thecasing or in the enclosure is too high, or its temperature is too low, control instrument I! will cause valve 26 to change its position so that fluid discharged from cylinder 1, instead of passing directly through pipes l0 and II, will be routed through reheating coils 23. Since the refrigerant passing from the cylinder Us at a relatively high temperature, it is a satisi'actory reheating medium. Fluid from heating coils 28 is returned to the main circuit at 24 and is then passed through the condenser in the normal. manner. Although heating coils 23, as illustrated, receive fluid from only cylinder I, it is apparent that fluid from both of the cylinders may be routed therethrough, ii desired. The passage of gas from the diii'erent cylinders to theheating coils may be controlled by the same control instrument, orby diflerent control instru-' ments; and in the latter case the instruments may have the same or diflferent settings. This system provides eflicient and elective reheating without any increase in the cost of operating the system, and at comparatively small. initial ex-.

, used in conjunction with liquid pumping systems,

gas engines and other types 01' displacement apparatus. Y i

The term compressor element" in theclaims.

shall be understood' to refer toindividual cylinders orthe like of compressorapumps or other displacement apparatus, and also to complete assemblages 'oi compressors,' pumps or displacement apparatus. Applicant does not restrict himself to compressors, MP or displacement also preventshigh pressure fluid from lines 0, ll apparatus of any particular type. and these may 75 Refrigerant gas is 1 be of the reciprocating, centrifugalor any other desired type.

Since many modifications may be made in the invention without departing from its scope, it-ia to be understood that the above description and accompanying drawing shall be interpreted as illustrative only, and not in a limiting sense, applicant limiting himself only as indicated inthe accompanying claims.

I claim:

1. In a refrigerating system of the character described, in combination-a plurality of compressor elements in parallel, feed means for supplying fluid to the elements, a plurality of discharge pipes for receiving fluid discharged by the compressor elements, a by-pass line connecting the feedmeans and at least one of the discharge pipes, a valve for controlling the flow of fluid through said by-pass line, said valve being nor:

mally closed, means for opening said valve when- 'ever the load on said apparatus falls below a predetermined point, and means for preventing .the flow of fluid from another of the, discharge pipes to said by-pass line.

2. In a refrigerating system of the character described, in combination a plurality of compressor elements in parallel, feed means for supply-,- ing fluid to said elements, a plurality of discharge pipes for receiving fluid discharged from said elements, and means for recirculating to said feed means from said discharge pipes fluid discharged from different numbers of said elements under different operating conditions, said 3. In a refrigerating system of the character described, a plurality of compressor elements connected in parallel arrangement, feed means for supplying fluid to said elements means for receiving fluid discharged by said elements, and

means for recirculating through at least one of said elements fluid discharged by at least one of said elements in response to decrease of the fluid pressure in said feed means below a predetermined point while delivering fluid discharged from at least another of the elements from the compressor in normal manner;

4. In a refrigerating system of the character described, a plurality of compressor elements connected in parallel arrangement, feed means for supplying fluid to said elements, means for receiving fluid discharged by said elements, means for recirculating through at least one of said elements fluid discharged by at least one of said elements whenever the fluid temperature in said feed means falls below a predetermined point, and means for preventing recirculation through said compressor of fluid discharged from at least another of said elements.

In a refrigerating system of the character described, in combination, compressor apparatus including a plurality of compressor elements, said elements being connected in parallel arrangement, feed means for supplying fluid to said apparatus, means for discharging fluid from said elements, means for delivering fluid discharged from at least one of said elements to the suction side of at least one of said elements in response to decrease of the load on the apparatus below a predetermined point, and mean's for directly discharging from said compressor apparatus fluid discharged from at least one of said elements.

6. The combination with a refrigerating system including an evaporator and a condenser,'of a compressor apparatus including a plurality oi compressor elements in parallel arrangement, feed means for supplying evaporated refrigerant from said evaporator to said compressor apparatus, means for discharging fluid from said elements, means for recirculating fluid dischaged from at least one ofsaid elements whenever the heat load on said evaporator falls below a predetermined point, and means delivering fluid discharged from at least another of said elements directly to said condenser from said compressor apparatus at all times during operation of said compressor apparatus, saidfluid recirculating means being arranged to supply fluid to at least one of said last-mentioned elements.

7. The combination with a refrigeratingsystem including an evaporator and a condensenvof a compressor apparatus including a plurality of compressor elements connected in parallelarrrangement, feed means for supplying evaporated refrigerant from said evaporator to said compressor apparatus; ,means for discharging compressed refrigerant fluid from said elements,-

means for recirculating through said compressor apparatus fluid discharged from at least one of said elements in response to decrease of the heat

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