US3670519A

US3670519A - Capacity control for multiple-phase ejector refrigeration systems

Info

Publication number: US3670519A
Application number: US113224A
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: 1972-06-20
Anticipated expiration: 1989-06-20

Abstract

A multiple-phase ejector refrigeration system including a capacity control allowing part-load operation. The capacity is varied by bleeding a stream of hot gas from the discharge side of a vapor compressor and introducing it in a controlled manner into the liquid nozzle of the multiple-phase ejector. This has the effect of first increasing and then reducing the efficiency of the nozzle as the bleed rate increases, thereby affecting the efficiency and flow capacity of the ejector unit.

Description

United States Patent Newton June 20, 1972 54 CAPACITY CONTROL FOR MULTIPLE. 3,276,216 10/1966 Papapanu ..62/soo 3,496,735 2/1970 l-laisma.... ..62/500 PHASE EJECTOR REFRIGERATION SYSTEMS Primary Examiner-Meyer Perlin Attomey-Donald W. Banner, William S. McCurry and John Inventor: Alwin B. Newton, York, Pa.

W. Butcher Assignee: Borg-Warner Corporation, Chicago, Ill.

Filed: Feb. 8, 1971 ABSTRACT Appl' l 13224 A multiple-phase ejector refrigeration system including a capacity control allowing part-load operation. The capacity is us. Cl ..62/l16, 62/191, 62/500 varied by bleeding a stream gas dischalge Side of a vapor compressor and introducing it in a controlled Int. Cl ..F25b 1/00 manner into the liquid nozzle of the multiple-phase e ector. Field of Search 116, 1 has Lhe efiect offirst increasing and then reducing the ficiency of the nozzle as the bleed rate increases, thereby af- Refelences Ciied fecting the efficiency and flow capacity of the ejector unit.

UNITED STATES PATENTS 28 Claims, 5 Drawing Figures 2,852,922 9/1958 Neumann ..62/500 4o 24 44 45 19 25 a0 28 30 .9 20 A 48 LOAD PNENTEBJUHZO I972 3,570,519

sv WZM ATTORNEY PHTEMTEMmo 1972 3579.519 sum 2 or 2 I T f) LOAD \J 5 5 INVENTOR AAW/A A/VEWTO/V ATTORNEY CAPACITY CONTROL FOR MULTIPLE-PHASE EJECTOR REFRIGERATION SYSTEMS BACKGROUND AND SUMMARY OF THE 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.

U. S. Pat. No. 3,277,660 issued to Clarence A. Kemper et al. on Oct. ll, 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, 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 nonle 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; and 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 hot gas from the discharge side of a vapor compressor to be introduced in controlled quantities into the high pressure liquid nozzle to change the character and efficiency of the flow of said liquid during its acceleration to a supersonic velocity, two-phase, vapor-liquid stream.

Accordingly, a principal object of the invention is to provide an improved capacity control for a multiple-phase 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 feeding hot gas from a compressor to the nozzle.

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 refrigeration system embodying my improved control including a thermostatically-operated valve;

FIG. 2 is a detailed cross-sectional view of the valve;

FIG. 3 is a schematic or diagrammatic view of a modification of the refrigeration system shown in FIGS. 1 and 2;

FIG. 4 is a modification of portions of the refrigeration systems shown in FIGS. 1 and 3; and

FIG. 5 is another modification of portions of the refrigeration system shown in FIGS. 1 and 3.

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, an evaporator 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 conduit 16 to the multiple-phase ejector M which has means defining a liquid chamber 19, in the form of a tube, having an inlet 20 for the introduction of the high-pressure liquid stream, said liquid chamber 19 communicating with a first nozzle 22 provided at one end of the tube, 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 converging-diverging

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, liquidvapor 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 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 stream is greater than the temperature and the 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

conduits

50 and 52. 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 U. S. Pat. No. 3,277,660.

Conduits

50 and 52 are connected by means 54 for maintaining the pressure differential achieved at various loads between the diffuser outlet 45 and conduit 34. The pressure at 45 is essentially the same pressure existing at the suction side of the vapor compressor VC, while the pressure at 34 is essentially the pressure within the evaporator E. Means 54 may take the form of a float valve or orifice, but is preferably a liquid dropleg designed to accommodate a suitable pressure differential, say 5-10 p.s.i. at full load for refrigerants such as R-22. The main function of liquid dropleg 54 is to provide an interface between liquid returning to the evaporator through conduit 52, and vapor residing in chamber 48 and entering the evaporator B through conduit 50. No vapor should enter conduit 52 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 efiiciency is controlled by bleeding off a portion of the vapor from hot vapor conduit 12 through conduit 60 to the inlet nozzle 22 receiving the liquid from the condenser. The vapor, as it mixes with the liquid stream, disrupts the flow through the nozzle so that the efficiency of the nozzle flow may be conveniently and accurately controlled.

Control of the flow of hot gas is preferably in response to the absolute superheat of the gas being delivered to the inlet side of vapor compressor VC. Accordingly, a pressure tap 62 and a thermal-sensing bulb 64 are respectively responsive to the pressure and temperature of the gas in the suction conduit and which are operable to control a valve 66 in the bleed conduit between the hot gas conduit and the inlet nonle 22. More particularly and referring to FIG. 2, valve 66 comprises a hollow casing 67 provided with a flexible diaphragm 68 dividing the easing into an upper compartment 69 and a lower compartment 70 and supporting a vertically-movable valve member 71 having its lower cone-shaped end 72 disposed adjacent a circular opening 73 of the valve seat located between and connecting

conduits

60 and 61 so that movement of the valve member will control the quantity of gas flowing from conduit 12 to the conduit 67 and the inlet nozzle 22. The compartment 69 is connected to the refrigerant filled, pressureresponsive thermal-sensing bulb 64 by a conduit 74 so that movement of the diaphragm 68 will occur upon expansion and contraction of the vapor in compartment 69 in response to variations in temperature of the refrigerant in the bulb sensing the temperature of the gas in conduit 10. The vapor compartment 70 is sealed from communication with the gas flowing in

conduits

60 and 67 by a seal 75 connected to the casing 67 and in sealing engagement with valve member 71, which is biased open by spring 79. As vapor compartment 70 is connected by conduit 62 to the conduit 10, any variations in the pressure of the gas in conduit 10 will cause the diaphragm to be moved in response thereto.

The operation of the control mechanism may be described as follows: (1) a rise in the absolute superheat of gas entering the vapor compressor would indicate an increase in the load requiring additional capacity. The joint action of the pressure tap and the bulb would thus tend to close valve 66 to throttle any flow of gas into the nozzle and thereby increase the efficiency of the same; (2) a drop in the absolute superheat would indicate that a reduction in capacity is required; the bulb and the pressure tap would cooperate to open the valve to bleed additional gas into the nozzle, thus reducing the efficiency of the fluid flow into the multiple-phase ejector M and producing a corresponding reduction in capacity for the entire system.

Accordingly, the control of the present invention causes the capacity of the refrigeration system to be varied by bleeding a stream of hot gas from the discharge side of the vapor compressor and introducing it in a controlled manner into the liquid nozzle of the ejector. Introduction of a small amount of vapor into the nozzle inlet stream improves the efficiency of the nozzle but normally reduces the total flow rate through the nozzle. Introduction of an increased amount of vapor into the nozzle inlet stream may reduce the efficiency of the noule, but more importantly always reduces the total mass flow rate. The introduction of the high pressure gas bleed controls the amount of refrigerant passing through the nozzle and causes the nozzle to meter the flow, similarly to the operation of a thermostatic expansion valve in a conventional refrigeration system.

A secondary efi'ect occurs by the action of the vapor flow into the inlet region of the nozzle. More particularly the hot uncondensed gas has a higher enthalpy than the liquid which could enter through conduit 16. Accordingly, when the temperature of the vapor in conduit 10, sensed by bulb 64,

reduces with no change in pressure of the vapor in conduit 62, there is provided an indication of reduction in superheat and a need to reduce the total supply of refrigerant to the evaporator circuit. In this invention, reduction of the total supply of refrigerant to the evaporator conduit occurs by valve 66 opening more widely, allowing a higher flow rate of vapor and consequent reduction in the total mass flow through the nonle 22. Thus, liquid entering through conduit 16 is reduced similarly to the operation of a conventional expansion valve located in conduit 16 if the valve was somewhat closed in response to the reduction in superheat. Another effect of the entrance of hot gas is the equivalent of the hot gas bypass in conventional systems, but with the added advantage that the hot gas assists in compressing the vapor from evaporator 34 and thus both the vapor and hot gas flow itself enters the compressor at a higher pressure than would otherwise be the case.

The embodiment of the invention illustrated in FIG. 3 is an improvement of the refrigeration system of FIG. 1 and 2, like parts being similarly identified numerically or alphabetically in the several views. As in FIGS. 1 and 2, FIG. 3 also discloses a refrigeration system having a multiple-phase ejector M, a vapor compressor VC, a condenser C, an evaporator E, and

vapor-liquid separator S, connected together and arranged in a refrigerant flow pattern. In addition, as in FIG. I, valve 66 connects the hot vapor conduit 60 to the liquid chamber 19 and senses the pressure and temperature of the vapor in the suction conduit 10 to the compressor to open the valve 66 and thereby reduce capacity requirements of the refrigeration system when the superheated vapor drops below a normal level. One improvement disclosed in FIG. 3 is the provision of a valve 76 between and connecting conduit 60 and valve 66 and closable to override valve 66 by discontinuing vapor flow to the inlet nozzle 22 when valve 66 is open. Valve 76 may be connected, as shown by dotted lines, to a controlling timer on a float (not shown) in compressor crankcase 9 to cause liquid flood-back and, therefore, oil return at periodic intervals. Another improvement is valve 77 in conduit 78 between and directly connecting conduit 60 and conduit 61 and, thereby, bypassing

valves

66 and 76. Accordingly, valve 77 can override the effect of

valve

66 and 76 by feeding vapor to the inlet nozzle 22 to reduce capacity even though

valves

66 and 76 are closed. Valve 77 can be connected to a safety control such as a high or low pressure sensor, or low water temperature sensor. It will be apparent that

valves

66, 76 and 77 control the flow of hot refrigerant vapor or gas from the compressor VC to the liquid chamber 19 and thereby to the inlet nozzle 22 of the ejector M. By thus introducing the gas into the nozzle 22, these valves reduce the capacity of the ejector M and thereby of the refrigeration system.

As shown in FIGS. 4 and 5, conduit 61 may be alternately connected to the diffuser section (FIG. 4), or to the eductor section (FIG. 5) of the ejector and similar results achieved with varying flow levels in conduit 61.

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:

l. A refrigeration system comprising an evaporator; a vapor compressor adapted to compress a refrigerant; a condenser receiving hot refrigerant vapor from said compressor, said condenser operating to liquefy said refrigerant; a multiplephase ejector comprising means defining a liquid chamber having a liquid inlet, means defining a vapor chamber having a vapor inlet, and an outlet discharging a two-phase vapor-liquid refrigerant stream; means for supplying high pressure liquid from the condenser to said liquid inlet; 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 refi'igerant vapor to the suction side of said compressor; and means for supplying a portion of the hot vapor, flowing from said compressor to said condenser, to one of said ejector chambers.

2. A system as defined in claim 1 in which said hot vaporsupplying means supplies said hot vapor portion to said ejector liquid chamber.

3. A system as defined in claim 2 in which said hot vaporsupplying means is operative to supply said hot vapor portion to said ejector liquid chamber at a controlled rate in response to the capacity requirements of said system.

4. A system as defined in claim 2 in which said hot vaporsupplying means includes a conduit conducting said hot vapor portion to said liquid chamber, means controlling vapor flow in said conduit and including a valve, and means for operating said valve.

5. A system as defined in claim 4 in which said valve-operating means includes means for sensing the absolute superheat of vapor delivered to the suction side of said vapor compressor.

6. A system as defined in claim 4 in which said valve operating means includes means responsive to variations in pressure of the vapor delivered to the suction side of said compressor.

7. A system as defined in claim 4 in which said valve-operating means includes means responsive to variations in pressure and temperature of the vapor delivered to the suction side of said compressor.

8. A system as defined in claim 4 in which said valve includes a movable valve member operative to control the flow of vapor through said conduit; and said valve-operating means includes 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 delivered to the suction side of said compressor and connected to said compartment to effect movement of said diaphragm and thereby move said valve member.

9. A system as defined in claim 4 in which said valve includes a movable valve member operative to control the flow of vapor through said conduit; and said valve-operating means includes a casing, a flexible diaphragm in said casing and defining a vapor compartment, said diaphragm being connected to said valve member, passage means connected to said separator-and compressor-connecting means and to said vapor compartment for providing refrigerant vapor to said vapor compartment to effect movement of said diaphragm, in response to variations in the pressure of the refrigerant vapor, to move said valve member.

10. A system as defined in claim 4 in which said valve includes a movable valve member operative to control the flow of vapor through said conduit; and said valve-operating means includes a casing having a flexible diaphragm in said casing and dividing said casing to provide spaced first and second compartments, said diaphragm being connected to said valve member, a thermal-sensing bulb responsive to variations in the temperature of the refrigerant vapor delivered to the suction side of said compressor and connected to said first compartment to effect movement of said diaphragm and thereby move said valve member, said valve-operating means further including passage means connecting said second compartment and said separator-and compressor-connecting means for providing refrigerant vapor to said vapor compartment to effect movement of said diaphragm, in response to variations of the pressure of the refrigerant vapor, to move said valve member in cooperation with movement of said valve member by the variations in pressure in said first compartment controlled by said bulb.

11. A system as defined in claim 3 in which said hot vaporsupplying means includes a first conduit conducting said hot vapor portion to said liquid chamber; a first valve in said first conduit; means for operating said first valve to supply said hot vapor portion to said liquid chamber at a controlled rate in response to the capacity requirement of said system, and a second conduit in parallel with said first conduit and bypassing said first valve to conduct said hot vapor portion to said liquid chamber, and a second valve in said second conduit.

12. A system as defined in claim 11 in which said first valveoperating means includes means for sensingthe absolute superheat of vapor delivered to the suction side of said vapor compressor.

13. A system as defined in claim 1 1 in which said first valveoperating means includes means for sensing variations in the pressure of the vapor delivered to the suction side of said vapor compressor.

14. A system as defined in claim 11 in which said first valveoperating means includes means for sensing variations in pres sure and temperature of the vapor delivered to the suction side of said vapor compressor.

15. A system as defined in claim 3 in which said hot vaporsupplying means includes a conduit conducting said hot vapor portion to said liquid chamber; a first valve in said conduit; means for operating said first valve to supply said hot vapor portion to said liquid chamber at a controlled rate in response to the capacity requirements of said system, and a second valve in series with said first valve in said conduit.

16. A system as defined in claim 3 in which said hot vaporsupplying means includes a conduit conducting said hot vapor portion to said liquid chamber; a first valve in said conduit; means for operating said first valve to supply said hot vapor portion to said liquid chamber at a controlled rate in response to the capacity requirements of said system, and a second valve in series with said first valve in said conduit and controlling the supply of said hot vapor portion to said first valve.

17. A system as defined in claim 15 in which said first valveoperating means includes means for sensing the absolute superheat of vapor delivered to the suction side of said vapor compressor.

18. A system as defined in claim 15 in which said first valveoperating means includes means for sensing variations in the pressure of the vapor delivered to the suction side of said vapor compressor.

19. A system as defined in claim 15 in which said first valveoperating means includes means for sensing variations in pressure and temperature of the vapor delivered to the suction side of said vapor compressor.

20. A system as defined in claim 3 in which said hot vaporsupplying means includes a first conduit conducting said hot vapor portion to said liquid chamber; a first valve in said first conduit; means for operating said first valve to supply said hot vapor portion to said liquid chamber at a controlled rate in response to the capacity requirements of said system, and a second valve disposed in said first conduit and in series with said first valve, a second conduit disposed in parallel with said first conduit and bypassing said first valve and said second valve to conduct said hot vapor portion to said liquid chamber, and a third valve in said second conduit.

21. A system as defined in claim 20 in which said first valveoperating means includes means for sensing the absolute superheat of vapor delivered to the suction side of said vapor compressor.

22. A system as defined in claim 20 in which said first valveoperating means includes means for sensing variations in the pressure of the vapor delivered to the suction side of said vapor compressor.

23. A system as defined in claim 20 in which said first valveoperating means includes means for sensing variations in pressure and temperature of the vapor delivered to the suction side of said vapor compressor.

24. A system as defined in claim 1 in which said vapor chamber of said ejector comprises an educator section and a diffuser section, and said hot vapor supply means is connected to, and provides said hot vapor portion to, one of said eductor and diffuser sections.

25. A system as defined in claim 24 in which said hot vapor supply means provides said hot vapor portion to said eductor section. v

sion of said vapor in response to the capacity requirements of 10 said system, such that increased vapor is supplied during reduced capacity demand.

28. In a vapor cycle refrigerant system including a compressor, a condenser and an evaporator connected to provide a closed refrigeration circuit; a multiple-phase ejector connected in said circuit to boost the suction pressure of vapor supplied to said compressor, said ejector being driven by highpressure liquid refrigerant; means for separating the twophase stream leaving said ejector and returning the vapor phase to said compressor and delivering a liquid phase to said evaporator, the improvement comprising means for disrupting the efficiency of the pressure boosting capacity of said ejector by admitting vapor to the substantially liquid driving stream from said condenser.

4 t I I i UNITED STATES PATENT @FFIQE I QERTHEQAEE @F QQRREQHQN Patent No. 3,67%519 Dated June 20, 1972 Inventor(s) Alwin Bo Newton It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 69, educator should read eductor Signed and sealed this 19th day of December 19720 (SEAL) Attest:

EDWARD B LFLE'iCI-IER ,JRe ROBERT GOTTSCHALK Attescing Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 60376-P69 w u.s. sovznumzm' PRINTING OFFICE: 1959 0-366-334.

Claims

1. A refrigeration system comprising an evaporator; a vapor compressor adapted to compress a refrigerant; a condenser receiving hot refrigerant vapor from said compressor, said condenser operating to liquefy said refrigerant; a multiple-phase ejector comprising means defining a liquid chamber having a liquid inlet, means defining a vapor chamber having a vapor inlet, and an outlet discharging a two-phase vapor-liquid refrigerant stream; means for supplying high pressure liquid from the condenser to said liquid inlet; 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 supplying a portion of the hot vapor, flowing from said compressor to said condenser, to one of said ejector chambers.

2. A system as defined in claim 1 in which said hot vapor-supplying means supplies said hot vapor portion to said ejector liquid chamber.

3. A system as defined in claim 2 in which said hot vapor-supplying means is operative to supply said hot vapor portion to said ejector liquid chamber at a controlled rate in response to the capacity requirements of said system.

4. A system as defined in claim 2 in which said hot vapor-supplying means includes a conduit conducting said hot vapor portion to said liquid chamber, means controlling vapor flow in said conduit and including a valve, and means for operating said valve.

6. A system as defined in claim 4 in which said valve-operating means includes means responsive to variations in pressure of the vapor delivered to the suction side of said compressor.

11. A system as defined in claim 3 in which said hot vapor-supplying means includes a first conduit conducting said hot vapor portion to said liquid chamber; a first valve in said first conduit; means for operating said first valve to supply said hot vapor portion to said liquid chamber at a controlled rate in response to the capacity requirement of said system, and a second conduit in parallel with said first conduit and bypassing said first valve to conduct said hot vapor portion to said liquid chamber, and a second valve in said second conduit.

12. A system as defined in claim 11 in which said first valve-operating means includes means for sensing the absolute superheat of vapor delivered to the suction side of said vapor compressor.

13. A system as defined in claim 11 in which said first valve-operating means includes means for sensing variations in the pressure of the vapor delivered to the suction side of said vapor compressor.

14. A system as defined in claim 11 in which said first valve-operating means includes means for sensing variations in pressure and temperature of the vapor delivered to the suction side of said vapor compressor.

15. A system as defined in claim 3 in which said hot vapor-supplying means includes a conduit conducting said hot vapor portion to said liquid chamber; a first valve in said conduit; means for operating said first valve to supply said hot vapor portion to said liquid chamber at a controlled rate in response to the capacity requirements of said system, and a second valve in series with said first valve in said conduit.

16. A system as defined in claim 3 in which said hot vapor-supplying means includes a conduit conducting said hot vapor portion to said liquid chamber; a first valve in said conduit; means for operating said first valve to supply said hot vapor portion to said liquid chamber at a controlled rate in response to the capacity requirements of said system, and a second valve in series with said first valve in said conduit and controlling the supply of said hot vapor portion to said first valve.

17. A system as defined in claim 15 in which said first valve-operating means includes means for sensing the absolute superheat of vapor delivered to the suction side of said vapor compressor.

18. A system as defined in claim 15 in which said first valve-operating means includes means for seNsing variations in the pressure of the vapor delivered to the suction side of said vapor compressor.

19. A system as defined in claim 15 in which said first valve-operating means includes means for sensing variations in pressure and temperature of the vapor delivered to the suction side of said vapor compressor.

20. A system as defined in claim 3 in which said hot vapor-supplying means includes a first conduit conducting said hot vapor portion to said liquid chamber; a first valve in said first conduit; means for operating said first valve to supply said hot vapor portion to said liquid chamber at a controlled rate in response to the capacity requirements of said system, and a second valve disposed in said first conduit and in series with said first valve, a second conduit disposed in parallel with said first conduit and bypassing said first valve and said second valve to conduct said hot vapor portion to said liquid chamber, and a third valve in said second conduit.

21. A system as defined in claim 20 in which said first valve-operating means includes means for sensing the absolute superheat of vapor delivered to the suction side of said vapor compressor.

22. A system as defined in claim 20 in which said first valve-operating means includes means for sensing variations in the pressure of the vapor delivered to the suction side of said vapor compressor.

23. A system as defined in claim 20 in which said first valve-operating means includes means for sensing variations in pressure and temperature of the vapor delivered to the suction side of said vapor compressor.

24. A system as defined in claim 1 in which said vapor chamber of said ejector comprises an eductor section and a diffuser section, and said hot vapor supply means is connected to, and provides said hot vapor portion to, one of said eductor and diffuser sections.

25. A system as defined in claim 24 in which said hot vapor supply means provides said hot vapor portion to said eductor section.

26. A system as defined in claim 24 in which said hot vapor supply means provides said hot vapor portion to said diffuser section.

27. A method of controlling the capacity of a multiple-phase ejector comprising the steps of delivering high-pressure liquid into said multiple-phase ejector to produce a supersonic, mixed-phase refrigerant stream; introducing vapor into the inlet side of a nozzle during acceleration of said stream to reduce the efficiency of said nozzle; and controlling the admission of said vapor in response to the capacity requirements of said system, such that increased vapor is supplied during reduced capacity demand.

28. In a vapor cycle refrigerant system including a compressor, a condenser and an evaporator connected to provide a closed refrigeration circuit; a multiple-phase ejector connected in said circuit to boost the suction pressure of vapor supplied to said compressor, said ejector being driven by high-pressure liquid refrigerant; means for separating the two-phase stream leaving said ejector and returning the vapor phase to said compressor and delivering a liquid phase to said evaporator, the improvement comprising means for disrupting the efficiency of the pressure boosting capacity of said ejector by admitting vapor to the substantially liquid driving stream from said condenser.