US3701264A

US3701264A - Controls for multiple-phase ejector refrigeration systems

Info

Publication number: US3701264A
Application number: US113226A
Authority: US
Inventors: Alwin B Newton
Original assignee: Borg Warner Corp
Current assignee: York International Corp
Priority date: 1971-02-08
Filing date: 1971-02-08
Publication date: 1972-10-31
Anticipated expiration: 1989-10-31

Abstract

A multiple-phase ejector refrigeration system including capacity controls allowing part-load operation. The capacity is varied by controlling the flow of liquid refrigerant from a condenser into the nozzle of the multiple-phase ejector. This has the effect of increasing the suction pressure at a compressor, connected to an evaporator, above the pressure at the outlet of the cooling coil, thus reducing the compression ratio at which the compressor must operate, and regardless of the actual percentage of load at which the system may be operating at a given time and despite any changes in the speed of the compressor in response to compression ratio differences.

Description

I United vStates Patent [151 3,701,264 Newton Oct. 31, 1972 [54] CONTROLS FOR MULTIPLE-PHASE Primary Examiner-Meyer Perlin EJECTOR REFRIGERATION SYSTEMS Attorney-Donald W. Banner, William S. McCurry [72] Inventor: Alwin B. Newton, York, Pa. and John Butcher [73] Assignee: Borg-Warner Corporation, Chicago, [57] ABSTRACT A multiple-phaseejector refrigeration system includ- [22] F ilcd: Feb. 8, 1971 ing capacity controls allowing part-load operation. I The capacity is varied by controlling the flow of liquid [2]] Appl' 113226 refrigerant from a condenser into the nozzle of the multiple-phase ejector. This has the effect of increas- [52] US. Cl ..62/ 191, 62/500 mg the Suction P at a compressor, connected to 51 rm. Cl ..F25b 1/06 an evaporator above the Pressure at the Outlet of the [58] Field of Search ..62/11'6, 500, 191, 268 thus reducing the ratio at which the compressor must operate, and regardless of [56] References Cited the actual percentage of load at which the system may be operating at a given time and despite any changes UNITED STATES PATENTS in the speed of the compressor in response to compression ratio differences. 3,496,735 2/1970 Hersma ..62/500 14 Claims, 3 Drawing Figures PA'TENTEDnm 1 W 3. 701. 264

SHEEI 2 0F 2 INVENTOR AZW/IVE A/EWTOA/ ATTORNEY BACKGROUND AND SUMMARY OF TH INVENTION This invention relates to improved refrigeration systems and, more particularly, to a capacity control for refrigeration systems utilizing a multiple-phase ejector apparatus as one of the primary components in said refrigeration system.

US. Pat. No. 3,277,660 issued to Clarence A. Kemper et al. on Oct. 1 l, 1966, describes several novel refrigeration systems in which multiple-phase ejectors are employed in place of, or in combination with, a vapor compressor used in the conventional vapor cycle refrigeration system. In each of the systems described in the Kemper et al. patent a stream of high pressure liquid refrigerant is introduced into the inlet side of a nozzle which is adapted to accelerate the liquid refrigerant stream to form a supersonic velocity, twophase, vapor-liquid refrigerant stream. This two-phase, vapor-liquid refrigerant stream. This two-phase stream is then mixed with a low-pressure vapor refrigerant stream to provide a single refrigerant stream. Next, the velocity of the single refrigerant stream is decreased by expansion through a nozzle until the temperature and the pressure are greater than the temperature and pressure of the vapor .stream before it is increased in velocity.

One of the advantages of the refrigeration system described in the Kemper et al. patent, particularly the work input system illustrated in FIG. 3, is that it is extremely flexible and can be easily designed to meet specific requirements, such as condensing and evaporating temperatures, compressor capacity, etc. One of the reasons for this flexibility is that the system, contrary to the conventional refrigeration system, works at three different pressures. The high side pressure on the discharge side of the vapor compressor; an intermediate pressure, as measured on the suction side of the vapor compressor; and a low evaporating pressure, as measured in the evaporator or at the inlet side of the ejector. In effect, the ejector has the capability of significantly boosting the pressure on the suction side of the vapor compressor. This reduces the pressure difference against which the compressor has to work, so that a smaller compressor can be used to produce a given capacity, or alternatively, the same size compressor can be used with increased capacity.

The present invention may be considered generally as a refrigeration system which utilizes to the best advantage the unique features of the Kemper et al. multiple phase ejector. The Kemper et al. system does not disclose any mechanism by which the capacity may be conveniently controlled. The present invention proposes to utilize a stream of refrigerant liquid from the discharge side of a condenser by introducing the liquid in controlled quantities into the high pressure liquid nozzle of the ejector to control refrigerant vapor from an evaporator to raise its pressure and supply the pressurized vapor to the suction side of the compressor to reduce its compression ratio.

Accordingly, a principal object of the invention is to provide an improved capacity control for a multiplephase ejector refrigeration system.

Another object of the invention is to provide an improved capacity control for a multiple-phase ejector refrigeration system in which the capacity and effectiveness of the liquid nozzle of the ejector is varied by controlling the flow of refrigerant liquid from a condenser to the nozzle to induce flow of vapor from an evaporator and provide increased vapor suction pressure at the compressor.

Additional objects and advantages will be apparent from the following detailed description taken in conjunction with the drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic or diagrammatic view of a multiple-phase ejector refrigeration system illustrating a preferred embodiment of my improved control;

FIG. 2 is a modification of portions of the system of DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1, the refrigeration system of the present invention includes a vapor compressor VC, a condenser C, anevaporator E, a multiple-phase ejector M, and a vapor-liquid separator S. Refrigerant vapor of any suitable type, such as R-12 for example, is supplied to the suction side of compressor VC through conduit 10, compressed, and forwarded through conduit 12 to the condenser C. Heat is removed from the hot refrigerant vapor by the condenser heat exchanger 14 through which a coolant is circulated (usually water, but, in some cases, air). The hot vapor is caused to liquefy in the condenser and is delivered through conduits l6 and 17 to the multiple-phase ejector M which has means defining a tubular liquid chamber 19 having an inlet 20 for the introduction of the high pressure liquid stream from condenser C, said liquid-chamber l9 communicating with a first nozzle 22 discharging into a mixing chamber 24 having its flow axis substantially aligned with the longitudinal axis of the nozzle 22. The nozzle 22 is contoured by respective convergingdiverging

internal flow paths

25 and 26 in which the minimum cross-sectional area at 28 is sufficiently small, relative to the outlet area and other dimensions at 30, as to enable the production of a high-velocity, two-phase, liquid-vapor stream, which may be supersonic. A second input inlet 32 is provided for the introduction of a low-pressure vapor stream communicating through means defining a vapor chamber 33 with a second nozzle 36 located substantially concentric with the first nozzle 22 for introducing at 40 a highvelocity vapor refrigerant stream into the inlet opening of the mixing chamber 24 so as to be placed in intimate contact with the two-phase stream resulting at 30 from the first nozzle 22, thereby to combine the streams. The resulting mixed stream continues through the mixing section, and a section of 42 of substantially constant flow area, into a diverging chamber 44, the function of the latter being to decrease the velocity of the combined streams at 46 to a velocity at which the temperature and the pressure of the combined streams is greater than the temperature and pressure of the vapor refrigerant stream prior to passage through the second nozzle 36. The divergent chamber 44 has an outlet at 45 from which the ejector-exit stream is withdrawn and delivered into the vapor-liquid separator S. The latter comprises means defining a chamber 48 surrounding and in communication with the outlet portion of the ejector nozzle. Liquid refrigerant collects in the lower portion of chamber 48 and is supplied to the evaporator E through a conduit 50. For a more detailed disclosure and explanation of the above described refrigeration system including particularly the multiple-phase ejector M and its operation, reference is made to US. Pat. No. 3,227,660.

Conduit 50 is connected by means 52 for maintaining the pressure differential achieved at diffuser 45 relative to conduit 34 (or suction side of VC and evaporator E). Means 52 may take the form of an orifice, but is preferably a float valve designed to allow flow of liquid on an increase in level thereof and reduce or prevent such flow on a drop in level thereof. The main function of float valve 52 is to provide a control permitting liquid return to evaporator E to conduit 50, but preventing vapor residing in chamber 48 from entering the evaporator E through conduit 50. Novapor should enter conduit 50 and no liquid should enter conduit 10. The pressure loss in this action should not exceed the pressure rise between conduit 34 and chamber 48. Liquid, fed to the evaporator E, evaporates and the vapor is forwarded to the second nozzle 36 in the multiple-phase ejector M through conduit 34. In vaporizing, the refrigerant absorbs heat so that, in the conventional system, a second cooling coil is provided in the evaporator, such as in a conventional liquid chiller wherein water is circulated through a closed circuit including a tube bundle 56 (in the evaporator) and the load.

As pointed out in the preliminary remarks, the principal feature of the invention comprises a capacity control which affects the efficiency of the multiple-phase ejector unit M. In a preferred embodiment, ejector efficiency is controlled by providing means, in the form of a variable double orifice valve 58, operative to insure that all liquid, condensed in the condenser C, enters inlet 20 and flows into the chamber 19, thus almost completely preventing gas or vapor in condenser C entering the inlet 20 and chamber 19. Accordingly, all the condensed liquid passes into and through the nozzle 22 and thereby induces the flow of evaporated gas from the evaporator E, raising its pressure in the separator chamber 48 through its flow through diffuser 42. As a result, vapor is fed at a higher pressure to the suction conduit and to the compressor VC thus reducing the compression ratio at which the compressor must operate. At higher head pressures, the reduction in ratio is more effective than at low head pressures.

Valve 58 comprises a hollow T-shaped casing or fitting 59 providing aligned

tubular portions

60 and 61 having threaded engagement with

conduits

16 and 17 and defining entrance and exit passages 62 and 63. The casing 59 is divided into two chambers or compartments 64 and 65 by a central wall 66 extending upwardly into the annular leg 67 of the casing, the chambers 64 and 6S communicating respectively with the passages 62 and 63. A cap 68 is connected to leg 67, covers the open upper end of leg 67, and is positioned in spaced relation thereto to provide a chamber or compartment 69 containing a movable valve member in the form of a solid round disc 70. The disc 70 engages and can seat on the top of an outer annular seat 71 of leg 67 and on the top of central wall 66 so that the disc seals the chamber 69 from the chambers 64 and 65, and chamber 64 from chamber 65. However, the disc is raisable from the seat 71 to provide orifices between the chamber 69 and chambers 64 and 65.

in operation, the valve functions to allow condensed refrigerant liquid to flow into conduit 17 while almost completely preventing refrigerant gas or vapor entering conduit 17. More particularly, when a mixture of liquid and vapor, under pressure, enters conduit 16 from condenser C and .flows into passage 62 and chamber 64, the pressure raises the disc 70 allowing the liquid to flow radially across the underside of the disc. Since the velocity of the vapor or liquid is comparatively low, it exerts little influence on the disc which remains clear of the seat and allows free discharge. When the vapor reaches the trap or chamber 69, however, the velocity across the underside of the disc increases greatly and the disc is pulled toward the seat. At the same time, the radial vapor jet raises the pressure in chamber 69 by recompression, snapping the disc down to the seat. The downward force of the recompressed vapor in chamber 69, acting on the full area of the disc, is greater than the upward force of the inlet vapor acting on the smaller area of the inlet orifice provided between the valve disc and seat. The disc will remain seated, stopping all flow of the vapor, until the pressure in chamber 69 is reduced by condensation, and the cycle is repeated. A more complete and detailed description of the structure and operation of the valve is provided in US. Pat. No. 2,817,353. V

Since the valve allows condensed liquid to flow at a controlled rate to the conduit'17, chamber 19 and nozzle 22, and almost completely prevents gas entering conduit 17, all of the liquid, condensed in condenser C, passes into the nozzle 22 to induce flow from the evaporator E. A pressure, somewhat above the evaporator pressure, will be maintained in chamber 48 of separator S by the compressor. As liquid is intended to be separated from vapor in this chamber, the liquid returns to the evaporator E and may return at a greater rate than can be evaporated therein, in which case, it merely recycles again into the separator S. The head, produced by nozzle 22, serves to circulate the refrigerant liquid through the evaporator.

In the described refrigeration system, varying portions of the energy ordinarily lost in the expansion process will be useful to the system by increasing the suction pressure at the compressor above the pressure at the outlet of the coil, and thus reducing the compression ratio at which the compressor must operate. This characteristic will be realized regardless of the actual percentage of load at which the system may be operating at a given time, and would still be provided even if the speed of the compressor were changed in response to differences in compression ratio.

FIG. 2 discloses a modification of the refrigeration system of FIG. 1 and in which the compressor VCI is of the centrifugal type, and a controller 79 is connected between and to the

conduits

17 and 12 by

conduits

80 and 81 and is operative to sense the compression ratio, such as described in U.S. Pat. No. 3,355,906 for example, and vary the speed of the compressor motor 90.

FIG. 3 illustrates another embodiment of a multiplephase ejector refrigeration system. Certain portions of this system are identical in structure and operation to the system of FIG. 1, including a vapor compressor VC, a condenser C, a multiple-phase ejector M, a separator S, and evaporator E; compressor VC being connected by conduits 12 and to the condenser C and separator S,

conduits

34 and 50 connecting the evaporator E to the ejector M and separator S, and a float valve 52' between the separator S and conduit 50. A conduit 100 connects the condenser C to the ejector M. Portions of the ejector M that are identical to the ejector M of FIG. 1 are identified with the same reference numeral plus a suffix In FIG. 3, a feature of the system there shown comprises means 101 operative to control the flow of refrigerant liquid from the condenser C to the mixing chamber 24' of the ejector M in response to the absolute superheat of gas being delivered to the inlet side of the compressor VC. The control means 101 comprises a valve 102 including a movable member 103 having a conical head 104 positioned within the interior of the nozzle 22 in proximity to, and movable relative to the passage 105 in the nozzle defined by, the respective converging-diverging internal faces providing

flow paths

25 and 26 to meter the flow of refrigerant liquid flowing from the chamber 19' into the mixing chamber 24. The means 101 also comprises a thermal-sensing bulb 107 responsive to the temperature of the gas in the suction conduit 10' and which is operable, in a manner to be described, to control movement of the valve member 103 and thereby its conical head.104. More particularly, valve 102 further comprises a hollow casing 108 provided with a horizontal partition or wall 109 dividing the casing into an upper vapor-tight chamber 110 and a lower liquid-tight chamber 111. The lower chamber 111 contains the valve 102 and has a tubular guide 1 12 connected to the casing and movably supporting the valve stem 113 and its metering head 104. The chamber 111 also communicates with the liquid chamber 19 of the ejector M.

The upper chamber 110 contains a flexible diaphragm 114 provided to operate valve 102. Diaphragm 114 is supported by a flange 115 in sealed relation thereto to provide a fluid-tight compartment 116 connected to the thermal-sensing bulb 107 (normally containing a refrigerant charge) by a conduit 117 so that movement of the diaphragm will occur upon expansion and contraction of the fluid in compartment 116 in response to variations in temperature of the vapor in the bulb sensing the temperature of the gas in conduit 10. The upper chamber 110 is also connected by a conduit 118 to the conduit 10 so that this chamber is vented to suction in conduit 10'.

Actuating mechanism is connected to the valve stem 113 and to the diaphragm 114 to move the valve 103 in response to flexing of the diaphragm and comprises a lever 120 supported on the casing for rotation about a fixed pivot 121 and having its upper end pivotally con nected to a rod 122 having one end fixed to the diaphragm 114 and its other end connected to a springoperated device 123. The device 123 has a portion thereof positioned within a cylindrical projection 124 of casing 108 and extends into the chamber 110 of the casing. More particularly, the device 123 comprises a bellows 125 having one end encircling the opening defined by projection 124 and connected to the casing 108 and its other end secured to a disc 126 fixed to the rod 122 in a manner sealing the chamber from the interior of the bellows. A coil spring 127 has one end seated against the disc 126 and its other end engaging the head of an adjusting bolt 128 threaded into the casing projection 124, so that rotation of the bolt 128 causes variable pressures by the spring to be exerted on the diaphragm 114. The lever has a lower forked end receiving the upper end of a lever 129 rotatable about a pivot 130 mounted in sealing engagement with the wall 109 to prevent air or refrigerant flow between the

chambers

111 and 110. Lever 129 has its forked lower end receiving a pin 131 fixed to the valve rod 1 13 to move the rod upon actuation of the lever 120. In operation, the spring 127 will move the rod 122 in a direction to actuate

levers

120 and 129 and thereby valve stem 113 to move the valve head 104 in a' direction to close the passage 105 of nozzle '22, while expanding gas pressure in chamber 116 causes the levers to function to move the valve head 104 in a valve-opening direction. It will be noted that the

conduits

10 and 100 are in close proximity to provide heat exchange relationship so that the sensing bulb 107 of the thermostatic valve arrangement has a means of control even with saturated vapor leaving separator S and flowing through conduit 10 to the compressor VC.

In the embodiment of the invention of FIG. 3, it will be appreciated that no particular effort has been made, other than that provided with the shape and size of the nozzle and diffuser openings, to effect an exact conservation of energy in the mixing streams. Instead, it is intended as a practical approach to make useful gains throughout all load conditions, through utilization of a large part of the energy usually lost in expansion of the refrigerant. The percentage used will vary with load conditions and could be peaked at some frequently used partial load condition.

While this invention has been described in connection with specific embodiments thereof, it is to be understood that this is by way of illustration and not by way of limitation; and the scope of the appended claims should be construed as broadly as the prior art will permit.

What is claimed is:

1. A refrigeration system comprising an evaporator; a vapor compressor adapted to compress a refrigerant; a condenser receiving refrigerant vapor from said compressor, said condenser operating to liquefy said refrigerant vapor; a multiple-phase ejector comprising means defining a liquid chamber having a liquid inlet, means defining a vapor chamber having a vapor inlet, means defining a mixing chamber receiving liquid and vapor from said liquid and vapor chambers and having an outlet discharging a two-phase vapor-liquid stream, and a nozzle between and connecting said liquid chamber to said mixing chamber; means connecting said condenser and said ejector and supplying high pressure liquid from said condenser to said liquid inlet and chamber and thereby to said nozzle; a vapor-liquid separator receiving the two-phase refrigerant stream and adapted to separate said phases; means for transferring the liquid phase from said separator to said evaporator; means for connecting said evaporator to ble orifice valve providing for the flow of condensed liquid from said condenser to said nozzle while substantially preventing vapor flowing from said condenser to said nozzle. 4

3. A refrigeration system as defined in claim 2 in which said valve comprises a casing having first and pressor-connecting means comprises a second conduit in heat exchange relationship with said first conduit.

second compartments respectively communicating with said condenser and said liquid inlet and having a third compartment; and a valve member separating said third compartment from said first and second compartments and providing therewith said double orifice, said valve being movable in response to varying pressures and velocities of the liquid-vapor mixture from said condenser to said multiple-phase ejector.

4. A refrigeration system comprising an evaporator; a vapor compressor adapted to compress a refrigerant; a condenser receiving refrigerant vapor from said compressor, said condenser operating to liquefy said refrigerant vapor; a multiple-phase ejector'comprising means defining a liquid chamber having a liquid inlet, means defining a vapor chamber having a vapor inlet, means defining a mixing chamber receiving liquid and vapor from said liquid and vapor chambers and having an outlet discharging a two-phase vapor-liquid stream, and a nozzle between and connecting said liquid chamber to said mixing chamber; means connecting said condenser and said ejector and supplying high pressure liquid from said condenser to said liquid inlet and chamber and thereby to said nozzle; a vapor-liquid separator receiving the two-phase refrigerant stream and adapted to separate said phases; means for transferring the liquid phase from said separator to said evaporator; means for connecting said evaporator to said vapor inlet; means connecting said separator to said compressor to deliver refrigerant vapor to the suction side of said compressor; and means for controlling the flow of liquid between said nozzle and said condenser-ejector connecting means, said means for controlling the flow of liquid including a valve and means for operating said valve, said last-named means including means responsive to the varying temperature of the vapor flowing in said separator-compressor connecting means.

5. A refrigeration system as defined in claim 4 in which said valve-operating means includes means responsive to varying temperatures of the vapor flowing in said separator-compressor connecting means.

6. A refrigeration system as defined in claim 5 in which said condenser and ejector-connecting means comprises a first conduit, and said separator and com- 7. A-refrigeration system as defined in claim 4 in which said valve has a movable member within said nozzle and is operative to vary the quantity of refrigerant liquid flowing through said nozzle.

8. A refrigeration system as defined in claim 7 including means for moving said valve member, and means responsive to variations intemperature of the vapor delivered to the suction side of said compressor.

9. A refrigeration system as defined in claim 8 in which said condenser and ejector-connecting means comprises a first conduit, and said separator and compressor-connecting means comprises a second conduit in heat exchange relationship with said first conduit.

10. A refrigeration system as defined in claim 7 including means for moving said valve member and comprising a casing, a flexible diaphragm in said casing and defining a compartment, said diaphragm being connected to said valve member, a thermal-sensing member responsive to variations in the temperature of the refrigerant vapor in said separator-compressor connecting means, and in fluid communication with said compartment, to effect movement of said diaphragm and thereby move said valve member.

11. A refrigeration system as defined in claim 10 in which said valve member is moved toward one end of its valve-closing and opening positions by said diaphragm, and said moving means also includes spring means connected to said valve member and operative to move said valve member toward the other of its valve-closing and opening positions.

12. A refrigeration system as defined in claim 10 in which said casing is provided with a venting compartment spaced from said compartment by said diaphragm and connected to, and in communication with the vapor in, said separator-compressor connecting means.

13. A refrigeration system as defined in claim 10 in which said casing is providedwith a venting compartment spaced from said compartment by said diaphragm and connected to, and in communication with the vapor in, said separator-compressor connecting means, said moving means including lever means in said venting compartment and connected to said diaphragm and said valve member.

14. A refrigeration system as defined in claim 10 in which said valve member is moved toward one end of its valve-closing and opening positions by said diaphragm, and said moving means also includes spring means connected to said valve member and operative to move said valve member toward the other of its valve-closing and opening positions, and in which said casing is provided with a venting compartment spaced from said compartment by said diaphragm and connected to, and in communication with the vapor in, said separator-compressor connecting means, said moving means including lever means in said venting compartment and connected to said diaphragm, said spring means, and said valve means.

Claims

1. A refrigeration system comprising an evaporator; a vapor compressor adapted to compress a refrigerant; a condenser receiving refrigerant vapor from said compressor, said condenser operating to liquefy said refrigerant vapor; a multiple-phase ejector comprising means defining a liquid chamber having a liquid inlet, means defining a vapor chamber having a vapor inlet, means defining a mixing chamber receiving liquid and vapor from said liquid and vapor chambers and having an outlet discharging a two-phase vapor-liquid stream, and a nozzle between and connecting said liquid chamber to said mixing chamber; means connecting said condenser and said ejector and supplying high pressure liquid from said condenser to said liquid inlet and chamber and thereby to said nozzle; a vapor-liquid separator receiving the two-phase refrigerant stream and adapted to separate said phases; means for transferring the liquid phase from said separator to said evaporator; means for connecting said evaporator to said vapor inlet; means connecting said separator to said compressor to deliver refrigerant vapor to the suction side of said compressor; and means for controlling the flow of liquid between said nozzle and said condenser-ejector connecting means, said controlling means including means responsive to flow condition of the refrigerant in said system.

2. A refrigeration system as defined in claim 1 in which said controlling means includes a variable double orifice valve providing for the flow of condensed liquid from said condenser to said nozzle while substantially preventing vapor flowing from said condenser to said nozzle.

3. A refrigeration system as defined in claim 2 in which said valve comprises a casing having first and second compartments respectively communicating with said condenser and said liquid inlet and having a third compartment; and a valve member separating said third compartment from said first and second compartments and providing therewith said double orifice, said valve being movable in response to varying pressures and velocities of the liquid-vapor mixture from said condenser to said multiple-phase ejector.

4. A refrigeration system comprising an evaporator; a vapor compressor adapted to compress a refrigerant; a condenser receiving refrigerant vapor from said compressor, said condenser operating to liquefy said refrigerant vapor; a multiple-phase ejector comprising means defining a liquid chamber having a liquid inlet, means defining a vapor chamber having a vapor inlet, means defining a mixing chamber receiving liquid and vapor from said liquid and vapor chambers and having an outlet discharging a two-phase vapor-liquid stream, and a nozzle between and connecting said liquid chamber to said mixing chamber; means connecting said condenser and said ejector and supplying high pressure liquid from said condenser to said liquid inlet and chamber and thereby to said nozzle; a vapor-liquid separator receiving the two-phase refrigerant stream and adapted to separate said phases; means for transferring the liquid phase from said separator to said evaporator; means for connecting said evaporator to said vapor inlet; means connecting said separator to said compressor to deliver refrigerant vapor to the suction side of said compressor; and means for controlling the flow of liquid between said nozzle and said condenser-ejector connecting means, said means for controlling the flow of liquid including a valve and means for operating said valve, said last-named means including meAns responsive to the varying temperature of the vapor flowing in said separator-compressor connecting means.

6. A refrigeration system as defined in claim 5 in which said condenser and ejector-connecting means comprises a first conduit, and said separator and compressor-connecting means comprises a second conduit in heat exchange relationship with said first conduit.

7. A refrigeration system as defined in claim 4 in which said valve has a movable member within said nozzle and is operative to vary the quantity of refrigerant liquid flowing through said nozzle.

8. A refrigeration system as defined in claim 7 including means for moving said valve member, and means responsive to variations in temperature of the vapor delivered to the suction side of said compressor.

13. A refrigeration system as defined in claim 10 in which said casing is provided with a venting compartment spaced from said compartment by said diaphragm and connected to, and in communication with the vapor in, said separator-compressor connecting means, said moving means including lever means in said venting compartment and connected to said diaphragm and said valve member.