WO2000075578A1

WO2000075578A1 - Cooling apparatus and method for increasing cooling capacity

Info

Publication number: WO2000075578A1
Application number: PCT/SE1999/002186
Authority: WO
Inventors: Henrik ÖHMAN
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-06-02
Filing date: 1999-11-25
Publication date: 2000-12-14
Anticipated expiration: 2001-12-02
Also published as: AU2012900A; SE9902024D0; EP1192394A1

Abstract

The present invention relates to a refrigerating plant that includes a compressor (2), a condenser (4), a phase separator (1, 101), an evaporator (17), connected in series with conduits (3, 5, 16 and 18 respectively) to form a closed refrigerant loop, and further comprising a high-pressure conduit (21, 21a, 21b) that connects a high-pressure outlet (21, 120) of the phase separator (1, 101) with the compressor (2). The phase separator (1, 101) has the form of a machine in which incoming refrigerant is subjected to pressure reduction and separation into an essentially gas-containing gas phase and an essentially liquid-containing liquid phase, wherein the liquid phase is discharged through a low-pressure outlet port (15, 115) whereas the gas phase is compressed and discharged through the high-pressure outlet (20, 120) of the phase separator. The invention also relates to a method of enhancing the refrigerating capacity of the refrigerating system wherein refrigerant entering the phase separator (1, 101) is subjected to pressure reduction and separation into an essentially gas containing gas phase and an essentially liquid-containing liquid phase. The liquid phase is discharged through a low-pressure outlet port (15, 115) and the gas phase is compressed and thereafter discharged to the closed loop.

Description

Cooling apparatus and method for increasing cooling capacity

The present invention relates to a refrigerating system of the kind that includes a compressor, a condenser, a phase separator, an evaporator connected by conduits in se- ries to form a closed refrigerant loop, and a high-pressure conduit that connects a high pressure outlet of the phase separator with the compressor or with the condenser inlet. The invention also relates to a method of increasing the refrigerating capacity with the aid of the present refrigerating system.

US-A1 5 816 055 teaches a refrigerating system that includes a screw rotor com- pressor, a condenser, a first pressure reducing device, an economiser, i.e. a phase separator, a second pressure reducing device, and an evaporator, said elements being interconnected by conduits in this order, wherewith the evaporator is connected by a conduit to the low-pressure inlet of the compressor to form a closed refrigerant circuit. The refrigerant circuit further includes a conduit that connects the phase separator with a closed working chamber in the compressor.

Requirements placed on refrigerant composition and on the sealing and effectiveness of refrigerating systems have accentuated the need for improvements in existing system components and also in maintaining satisfactory operation of such systems and in improved system efficiency. As is well known, refrigerating systems require the use of some type of expansions mechanism to maintain correct evaporator pressures and temperatures. In its ideal state, i.e. a state without losses, such an expansion mechanism may function as an isen- thalpic pressure reducer. However, entropy increases by definition and the entropy will increase still further with actual expansion mechanisms that suffer losses. In practice, the total increase in entropy is one of the most troublesome sources of efficiency losses that must be overcome. For instance, the losses can be reduced by replacing the isenthalpic expansion mechanism, for example a valve means, with an isenthropic expansion mechanism. Such replacement will result in increased refrigerating effect in the evaporator at a given mass flow and therewith a given compressor power requirement. This increases system efficiency. What is more, the expansion machine delivers work that corresponds to the enthalpy reduction in the refrigerant subtracted by any occurrent losses. System efficiency is further improved when this work can be utilised outside the refrigerant circuit. In order to achieve arrangements of this kind that can be used in practice, it is necessary to transfer the work from the expansion mechanism without the energy losses being of such high magnitude as to detract from the advantage afforded by the energy addition. Neither should the coupling between the expansion machine and a work consuming device impair the ability of the expansion machine to regulate the performance of the refrigerating system in keeping with variations in refrigeration requirements. Neither should the energy transfer be so complicated as to render practical use impossible due to the costs involved.

The object of the present invention is to provide a practicable advantageous and simple arrangement with which these requirements are fulfilled.

Another object is to provide a method of increasing the refrigerating capacity of refrigerator systems.

The inventive arrangement includes a phase separator in the form of a single rotor machine having a working chamber in which refrigerant is expanded and separated es- sentially in a liquid phase and thereafter delivered to the evaporator, and a gas phase which is compressed and returned to the compressor or to the conduit system downstream of the compressor, i.e. to the condenser. The rotor machine has a high-pressure inlet port for liquid refrigerant arriving from the condenser arrangement, a liquid outlet port for essentially liquid phase to the evaporator, and a high-pressure outlet port for es- sentially gas phase. The opening and closing edges of the liquid outlet port and the closing edge of the high-pressure inlet port and the opening edge of the high-pressure outlet can readily be varied to optimise efficiency and to control the refrigerator system in keeping with refrigeration requirements, in accordance with Claims 5-12 and Claims 16-23. This includes controlling the rotational speed of the rotor and therewith the throughflow of liquid, since energy taken-up in the compression phase is balanced by the energy delivered in the expansion phase. Alternatively, the rotor may simply be slowed down or braked mechanically or electrically, although this will result in an efficiency loss.

The compressor arrangement may comprise one or more compressors connected in series or in parallel, and the phase separator may have one or more rotors, which may be helical screw rotors or eccentrically rotating rotors and/or have the form of a rotor that includes chamber seals that separate two sub-chambers from the surroundings designed so that the volumetric capacity of the working chamber will first be expanded and then contracted. The screw rotor machine described in US Patent Specification 5 192 199 is an example of a phase separator that includes helical screw rotors.

The working medium leaving the high-pressure outlet port can be led to the con- denser arrangement or to a connecting conduit between the condenser arrangement or the compressor arrangement, or beneficially to an intermediate pressure inlet to the compressor arrangement.

The invention will now be described in more detail with reference to an exemplifying embodiment of an inventive arrangement and also with reference to the accompa- nying schematic drawings, in which

Figure 1 is a diagrammatic illustration of a refrigerating system that includes a phase separator according to the invention;

Figure 2 is a diagram corresponding to that of Figure 1, showing another embodiment of a refrigeration system and including another kind of phase separator; Figures 3a and 3b illustrate the manner of operation of the phase separator shown in Figure 1, in two different working phases; and

Figure 4 illustrates different control options with respect to phase separation in the phase separator of the kind shown in Figures 1 and 3.

Figure 1 illustrates an inventive refrigeration system in which a phase separator 1 is connected to a refrigerator circuit that includes a compressor 2 for compression of a gaseous refrigerant, a pressure conduit 3 which connects an outlet from the compressor 2 to an inlet of a condenser 4, and a pressure conduit 5 which connects an outlet from the condenser 4 to a high-pressure inlet port 6 of a phase separator 1. The phase separator 1 is a vane rotor machine housed in a housing that includes a working chamber A which has a cylindrical inner wall 7 and in which a cylindrical, eccentrically located rotor 8 is rotatably mounted, said rotor having radially extending slots 9 in which vanes 10, 11, 12, 13 are mounted for radial movement in said slots. When the rotor 8 rotates in the direction shown by arrow 14. the vanes 10, 11, 12, 13 are guided into abutment with the cylinder wall 7 in a known manner, through the medium of their outer axial edges. The phase separator 1 includes a radial liquid outlet port 15 which is generally diametrical in relation to the port 6 and which is connected by a low-pressure conduit 16 to the inlet of an evaporator 17. A suction conduit 18 extends from the outlet of the evaporator 17 to an inlet 19 of the compressor 2. The compressor 2 is driven by a motor M.

The phase separator 1 also includes a high-pressure outlet port 20. A high- pressure conduit 21, 21a connects the outlet port 20 to an intermediate pressure port 33 of the compressor 2. Extending from the conduit 21 is a branch conduit 21b that opens into the suction conduit 18 leading to the compressor 2. The high-pressure conduit 21a includes a regulating valve 24 downstream of the point at which the conduit 21 branches off from the conduits 21a and 21b. A further regulating valve 23 is provided in the conduit 21b. These valves 23, 24 function to control the distribution of gas supply to the in- termediate pressure port 33 and the inlet port 19 of said compressor. This control can be effected via regulating devices not shown. It is also feasible to allow the conduit 21 to open directly into either the intermediate pressure port 33 or the suction conduit 18. In this latter case, a valve may be provided in said conduit or the conduit may also lack a regulating valve. Four chambers I, II, III and IV are delimited between the vanes 10-13 of the phase separator 1 in the working chamber A, as marked in Figures 3a and 3b which illustrate the working cycle of the phase separator. Figure 3 a shows the state in which filling of the chamber I with liquid refrigerant through the high-pressure inlet 6 is about to be terminated. An expansion process has been terminated under partial evaporation in chamber II, and emptying of essentially the liquid phase takes place through the low- pressure outlet port 15 which is radially situated to facilitate emptying of the liquid phase with the aid of rotational forces. Emptying of the liquid phase is about to be terminated in chamber III, which contains essentially only gas phase. Compression of the gas phase and initial emptying through the high-pressure outlet port 20 takes place in cham- ber IV.

In Figure 3b the chambers I, II, III and IV have been rotated through an angle of about 45°. Expansion takes place in the chamber 1 while evaporating part of the liquid phase and giving-off energy. In chamber II the major part of the liquid phase is slung through the port 15 with the aid of the rotational forces, and in chamber III remaining gas and accompanying liquid residues are compressed while taking-up essentially the same amount of energy that was earlier delivered in the chamber I. Re-filling takes place in the front part of the chamber IV while the compressed gas is emptied through the port 20 in the rear part of said chamber.

For the purpose of controlling the absolute volume in the working chamber A when closing the low pressure outlet port 15, said port is conveniently provided with an adjustable closing edge (see Figure 4). This is readily achieved with the aid of slide valve 30 by means of which a plurality of openings 31 between the compression side of the working chamber and the low-pressure outlet port 15 can be kept covered and successively exposed by the closing edge 32 of the valve 30, beginning with the opening 13 located nearest the port 15, said opening 31 being shown partially exposed in Figure 4. Early closing of the outlet port 15 at the partially exposed opening 31 by means of the vane 12 in Figure 4 results in a large volume in chamber III and therewith a high torque requirement in compressing the gas to the pressure in chamber IV and therewith in the outlet port 20. Late closing of the outlet port 15 by exposing more openings 31 results in a smaller volume in the chamber III and therewith in a lower torque requirement for compressing the gas in the chamber IV. A higher compression requirement will result in the phase separator 1 rotating at a lower speed and therewith also in reduced liquid flow through the high-pressure inlet port 6 and the low-pressure outlet port 15. The capacity of the refrigeration system is therewith reduced because there is less liquid to evaporate. On the other hand, a lower compression torque will result in the phase separator rotating at a higher speed and therewith in a higher refrigerating capacity.

A corresponding effect can be achieved by braking the rotor 8 of the phase separator either mechanically or electrically, although this will result in losses in efficiency in the form of brake heat. An electrical brake B is indicated schematically in Figure 1.

The degree of compression in the phase separator 1 , and therewith the speed at which the separator rotor rotates, can alternatively be controlled to optimal efficiency by connecting the high-pressure conduit 21 in Figure 1 at an appropriate pressure to either the intermediate pressure inlet port 33 of the compressor 2 or to the inlet port of said compressor 2, or, alternatively, by supplying gas to both of these ports in an appropriate gas ratio. The pressure at the outlet port 20 can also be controlled or regulated by appro- priate adjustment of the port opening edge 38, conveniently by means of a valve.

The opening edge 34 of the low-pressure outlet port 15 of the phase separator 1 can also be adjusted with the aid of a slide valve 35 with fully or partially closed open- ings 36 that communicate with the port 15 and the expansion chamber. This enables the volumetric ratio in the expansion chamber II to be varied and optimised at each point of operation.

The stroke volume of the expansion chamber can be controlled by enabling the closing edge of the high-pressure inlet port 6 to be adjusted, suitably with the aid of a valve 39.

Control of the valves 30, 35, 38, 39 or corresponding devices is conveniently effected in a conventional manner, in response to a signal from a temperature sensor or pressure sensor 37 (Figure 1) provided in the suction line 18 between the evaporator 17 and the compressor inlet 19.

Alternatively, a temperature sensor may be arranged in the flow of medium cooled in the evaporator 17.

Figure 2 is a diagram corresponding to the diagram of Figure 1 and illustrating another embodiment of a refrigeration system that includes a phase separator of another kind. Those components in Figure 2 that find correspondence in Figure 1 have been identified with the same reference signs.

Figure 2 illustrates a refrigeration system according to the invention that includes a phase separator 101 connected in a refrigerating circuit that comprises a compressor 2 for compressing a refrigerant in gas phase, a pressure conduit 3 that connects an outlet from the compressor 2 to an inlet of a condenser 4, a pressure conduit 5 that connects an outlet from the condenser 4 to a high-pressure inlet port 106 of a phase separator 101, said separator being a helical screw rotor machine of the kind described in WO90/04107. The figure also illustrates schematically from one side one of two mutually co-acting rotors, for instance the male rotor 108. The outermost parts of the lobes of the rotor 108 form connecting lines with the surrounding barrel wall 107. A chamber C is formed between two connecting lines. This chamber C coacts with a similar chamber formed between the lobes of the female rotor and together form a V-shaped working chamber. It is only necessary to consider the part of the working chamber C shown in the figure in order to obtain an understanding of the method of operation described hereinafter. The phase separator 101 includes a liquid outlet port 115 which is connected by a low-pressure conduit 16 to the inlet of an evaporator 17. A suction conduit 18 extends from the outlet of the evaporator to a compressor inlet 19. The compressor 2 is driven by a motor M.

The phase separator 101 also includes a high-pressure outlet port 120. A high- pressure conduit 21, 121a connects the outlet port 120 with the conduit 3 that connects the compressor 2 outlet to the condenser 4. Extending from the conduit 21 is a branch conduit 21b which opens into the suction conduit 18 leading to the compressor 2. The high-pressure conduit 121a is provided with a regulating valve 124 downstream of the point at which the conduit 21 branches in the conduits 121a and 21b.

A further regulating valve 23 is provided in the conduit 21b. The distribution of gas supplied to the condenser 4 and to the compressor inlet port 19 is controlled by said valves 23, 124. This control can be effected through the medium of control devices not shown. The conduit 21 may alternatively be allowed to open directly into the condenser inlet port or in the suction line 18. In this latter case, a valve may be provided in said conduit or the conduit may alternatively lack a regulating valve. According to a further embodiment, the conduit 121a may open into the intermediate pressure port 33 of the compressor 2 instead of into the conduit 3. as shown in Figure 1.

The lobes of the rotor 108 move in the direction of the arrow 1 14 in the operation of the phase separator 101. The liquid phase from the condenser 4 passes through the conduit 5 and into the inlet port 106 of the phase separator 101 into a working chamber of relatively small volume. The volume of the working chamber is increased by rotation of the rotor 108 in the direction of arrow 114, wherewith separation in gas and liquid phase takes place. The liquid phase leaves the phase separator 101 through the outlet 1 15 subsequent to the front lobe of the working chamber having passed the opening edge of the outlet port 115. The major part of the gas phase remains in the phase separator, since the outlet port 115 is disposed in the lower part thereof, wherein the heavier liquid phase leaves the phase separator 115 with the assistance of the force of gravity and/or centrifugal forces. When the rear lobe of the working chamber has passed the closing edge of the liquid outlet port, further expansion of the gas phase can initially take place, and there- after compression. This compression will preferably take place immediately after the rear lobe has passed the closing edge of the outlet port. The compressed gas leaves the phase separator 101 through the outlet port 120 and is delivered to the conduit 21. Similar to the phase separator 1, the phase separator 101 is provided with a brake B. These separators can be driven by motors not shown. Adjustments to the arrangement shown in Figure 2 are effected in a similar manner to that described with reference to the arrangement shown in Figure 1. It will be understood that the invention is not restricted to the described and illustrated exemplifying embodiments thereof and that modifications can be made within the scope of the invention defined in the accompanying claims. For instance, the slide valves 30 and 35 and the slide valves at ports 6 and 20 may alternatively have the form of successively openable lift valves or like devices controlled by a microprocessor or some other control means.

Claims

1. Refrigerating plant comprising a compressor (2), a condenser (4), a phase separator (1, 101), an evaporator (17), connected in series with conduits (3, 6, 16 and 18 re- spectively) to form a closed refrigerant loop, and further comprising a high-pressure conduit (21, 21a, 21b) which connects a high-pressure outlet (20, 120) of the phase separator (1, 101) to the compressor (2), characterized in that the phase separator (1, 101) has the form of a machine in which incoming refrigerant is subjected to pressure reduction and separation into an essentially gas-containing gas phase and an essentially liquid- containing liquid phase, wherein the liquid phase is discharged through a low-pressure outlet port (15, 115), and the gas phase is compressed and discharged through the high- pressure outlet (20, 120) of the phase separator.

2. Refrigerating plant according to Claim 1, characterized in that the high-pressure conduit (21, 21a) connects the high-pressure outlet (20, 120) of the phase separator ( 1 ,

101) to an intermediate pressure port (33) of the compressor (2).

3. Refrigerating plant according to Claim 1 or 2, characterized by a regulating valve (24) disposed in the high-pressure conduit (21a).

4. Refrigerating plant according to Claim 3, characterized by a branch conduit

(21b) that connects the high-pressure conduit (21) upstream of the regulating valve (24) to the conduit (18) between the evaporator arrangement (17) and the compressor (2); and by a further regulating valve (23) in the branch conduit (21b).

5. Refrigerating plant according to one or more of Claims 1 - 4, characterized in that said machine has a housing (7) that houses at least one rotor (8) which forms between the housing (7) and the rotor (8) at least one working chamber (I - IV) that includes between a high-pressure inlet port (6) and a low-pressure outlet port (15) a sub- chamber that forms an expansion chamber, and between the low-pressure outlet port (15) and a high-pressure outlet (20) a further sub-chamber that forms a compression chamber, wherein the low-pressure outlet port (15) is disposed between the expansion chamber and the compression chamber and functions to output the liquid phase to the evaporator arrangement (17), and wherein the high-pressure outlet port (20) is adapted to output the gas phase to the compressor (2).

6. Refrigerating plant according to Claim 5, characterized in that the low pressure outlet port (15) is positioned so that the liquid refrigerant is separated from the gaseous refrigerant under the influence of rotor (8) rotation, and is discharged through the low- pressure outlet (15) by centrifugal force.

7. Refrigerating plant according to Claim 5 or 6, characterized in that the low- pressure outlet port (15) includes control means (35) for controlling adjustment of the opening edge (34) of the port (15) so as to adjust the volumetric ratio in the expansion chamber.

8. Refrigerating plant according to one or more of Claims 5 - 7, characterized in that the low-pressure outlet port (15) includes control means (30) for adjusting the closing edge (32) of the port (15) for regulating the absolute volume in the working chamber when closing the low-pressure outlet port (15).

9. Refrigerating plant according to one or more of Claims 5 - 8, characterized by mechanical or electrical brake means for controlling the rotational speed of the rotor (8).

10. Refrigerating plant according to one or more of Claims 5 - 9, characterized in that the high-pressure inlet port (6) includes control means (39) for adjusting the closing edge of the port (6) such as to regulate the stroke volume of the expansion chamber.

11. Refrigerating plant according to one or more of Claims 5 - 10, characterized in that the high-pressure outlet port (20) includes control means (38) for adjusting the opening edge of the port (20) such as to regulate the volumetric ratio in the compression chamber.

12. Refrigerating plant according to one or more of Claims 7-11, characterized in that one or more of said control means (30, 35, 38, 39) includes/include a slide valve or several successively actuatable lift valves under the control of a microprocessor or some other control means.

13. Refrigerating plant comprising a compressor (2), a condenser (4), a phase separator (1, 101), an evaporator arrangement (17) connected in series with conduits (3, 5, 16 and 18 respectively) to form a closed refrigerant loop, characterized by a high-pressure conduit (21, 121a) that connects a high-pressure outlet (20, 120) of the phase separator ( 1 , 101 ) to the condenser (4); and in that the phase separator ( 1 , 101) has the form of a machine in which incoming refrigerant is subjected to pressure reduction and separation into an essentially gas-containing gas phase and an essentially liquid-containing liquid phase, wherein the liquid phase is discharged through a low-pressure outlet (15) and the gas phase is compressed and discharged through the high-pressure outlet (20, 120) of the phase separator.

14. Refrigerating plant according to Claim 13, characterized in that the high- pressure conduit (121a) includes a control valve (124).

15. Refrigerating plant according to Claim 14, characterized by a branch conduit

(21b) that connects the high-pressure conduit (21) which, upstream of the control valve (121a), connects the high-pressure conduit (21) with the conduit (18) between the evaporator arrangement (17) and the compressor (2), and by a further control valve (23) in the branch conduit (121b).

16. Refrigerating plant according to Claim 15, characterized in that the machine includes a housing (7) which houses at least one rotor (8) that forms between the housing (7) and the rotor (8) at least one working chamber (I - IV) having between a high- pressure inlet port (6) and a low-pressure outlet port (15) a sub-chamber that forms an expansion chamber, and also having between the low-pressure outlet port (15) and a high-pressure outlet port (20) a sub-chamber that forms a compression chamber, wherein the low-pressure outlet port (15) is disposed between the expansion chamber and the compression chamber and functions to output the liquid phase to the evaporator arrangement (17), and wherein the high-pressure outlet port (20) is adapted to output the gas phase to the condenser (4).

17. Refrigerating plant according to Claim 16, characterized in that the low-pressure outlet port (15) is positioned so that the liquid refrigerant will be separated from the gaseous refrigerant under the influence of rotor rotation and discharged through the low- pressure outlet port (15) by centrifugal force.

18. Refrigerating plant according to Claim 16 or 17, characterized in that the low- pressure outlet port (15) includes a control device (35) for adjusting the opening edge

(34) of the port (15) such as to regulate the volumetric ratio in the expansion chamber.

19. Refrigerating plant according to one or more of Claims 16 - 18, characterized in that the low-pressure outlet port (15) includes a control device (30) for adjusting the closing edge (32) of the port (15) such as to regulate the absolute volume in the working chamber when closing the low-pressure outlet port (15).

20. Refrigerating plant according to one or more of Claims 16 - 19, characterized by mechanical or electrical brake means (B) for controlling the rotational speed of the rotor (8).

21. Refrigerating plant according to one or more of Claims 16 - 20, characterized in that the high-pressure inlet port (6) includes a control device (39) for adjusting the closing edge of the port (6) such as to regulate the stroke volume of the expansion chamber.

22. Refrigerating plant according to one or more of Claims 16 - 21, characterized in that the high-pressure outlet port (20) includes a control device (38) for adjusting the opening edge of the port (20) such as to regulate the volumetric ratio in the compression chamber.

23. Refrigerating plant according to one or more of Claims 18 - 22, characterized in that one or more of said control means (30, 35, 38, 39) includes/include a slide valve or several successively actuatable lift valves controlled by a microprocessor or some other control means.

24. A method of improving the refrigerating capacity of a refrigerating system that includes a compressor (2), a condenser (4), a phase separator (1, 101), an evaporator arrangement (17) connected in series by conduits (3, 5, 16 and 18 respectively) to form a closed refrigerant loop, characterized by subjecting refrigerant entering the phase separator (1, 101) to pressure reduction and separation into an essentially gas-containing gas phase and an essentially liquid-containing liquid phase, and discharging the liquid phase through a low-pressure outlet port (15, 115) and compressing the gas phase and thereafter discharging the gas phase to the closed loop.

25. A method according to Claim 24, characterized by delivering the gas phase to an intermediate pressure port (33) of the compressor (2).

26. A method according to Claim 24, characterized by delivering the gas phase to a compressor inlet port (19).

27. A method according to Claim 24, characterized by delivering the gas phase to the condenser (4).

28. A method according to Claim 24, characterized by delivering the gas phase both to an intermediate pressure port (33) of the compressor (2) and a compressor inlet port (19).

29. A method according to any one of Claims 24 - 27, characterized by controlling the flow of gas phase from the phase separator (1,101) with the aid of a control valve (24, 124). AMENDED CLAIMS

[received by the International Bureau on 02 October 2000 (02.10.00); original claims 1,13 and 24 amended; remaining claims unchanged

(5 pages)]

Claims

1. Refrigerating plant comprising a compressor (2), a condenser (4), a phase separator (1, 101), an evaporator (17), connected in series with conduits (3, 6, 16 and 18 re- spectively) to form a closed refrigerant loop, and further comprising a high-pressure conduit (21, 21a, 21b) which connects a high-pressure outlet (20, 120) of the phase separator (1, 101) to the compressor (2), the phase separator (1, 101) has the form of a machine in which incoming refrigerant is subjected to pressure reduction and separation into an essentially gas-containing gas phase and an essentially liquid-containing liquid phase, wherein the liquid phase is discharged through a low-pressure outlet port (15, 115), characterized in that the gas phase is compressed and discharged through the high-pressure outlet (20, 120) of the phase separator.

101) to an intermediate pressure port (33) of the compressor (2).

4. Refrigerating plant according to Claim 3, characterized by a branch conduit (21b) that connects the high-pressure conduit (21) upstream of the regulating valve (24) to the conduit (18) between the evaporator (17) and the compressor (2); and by a further regulating valve (23) in the branch conduit (21b).

5. Refrigerating plant according to one or more of Claims 1 - 4, characterized in that said machine has a housing (7) that houses at least one rotor (8) which forms between the housing (7) and the rotor (8) at least one working chamber (I - IV) that includes between a high-pressure inlet port (6) and a low-pressure outlet port (15) a sub- chamber that forms an expansion chamber, and between the low-pressure outlet port (15) and a high-pressure outlet (20) a further sub-chamber that forms a compression chamber, wherein the low-pressure outlet port (15) is disposed between the expansion chamber and the compression chamber and functions to output the liquid phase to the evaporator (17), and wherein the high-pressure outlet port (20) is adapted to output the gas phase to the compressor (2).

6. Refrigerating plant according to Claim 5, characterized in that the low pressure outlet port (15) is positioned so that the liquid refrigerant is separated from the gaseous ref igerant under the influence of rotor (8) rotation, and is discharged through the low- pressure outlet (15) by centrifugal force.

8. Refrigerating plant according to Claim 5 or 6, characterized in that the low- pressure outlet port (15) includes control means (30) for adjusting the closing edge (32) of the port (15) for regulating the absolute volume in the working chamber when closing the low-pressure outlet port (15).

9. Refrigerating plant according to Claim 5 or 6, characterized by mechanical or electrical brake means (B) for controlling the rotational speed of the rotor (8).

10. Refrigerating plant according to Claim 5 or 6, characterized in that the high- pressure inlet port (6) includes control means (39) for adjusting the closing edge of the port (6) such as to regulate the stroke volume of the expansion chamber.

11. Refrigerating plant according to Claim 5 or 6, characterized in that the high- pressure outlet port (20) includes control means (38) for adjusting the opening edge of the port (20) such as to regulate the volumetric ratio in the compression chamber.

12. Refrigerating plant according to Claim 7, characterized in that one or more of said control means (30, 35, 38, 39) includes/include a slide valve or several successively actuatable lift valves under the control of a microprocessor or some other control means.

13. Refrigerating plant comprising a compressor (2), a condenser (4), a phase separator (1, 101), an evaporator arrangement (17) connected in series with conduits (3, 5, 16 and 18 respectively) to form a closed refrigerant loop, and further comprising a high- pressure conduit (21, 121a) that connects a high-pressure outlet (20, 120) of the phase separator (1, 101) to the condenser (4); and in that the phase separator (1, 101) has the form of a machine in which incoming refrigerant is subjected to pressure reduction and separation into an essentially gas-containing gas phase and an essentially liquid- containing liquid phase, wherein the liquid phase is discharged through a low-pressure outlet (15), characterized in that the gas phase is compressed and discharged through the high-pressure outlet (20, 120) of the phase separator.

15. Refrigerating plant according to Claim 14, characterized by a branch conduit (21b) that connects the high-pressure conduit (21) which, upstream of the control valve (121a), connects the high-pressure conduit (21) with the conduit (18) between the evaporator arrangement (17) and the compressor (2), and by a further control valve (23) in the branch conduit (121b).

16. Refrigerating plant according to Claim 15, characterized in that the phase separator (1, 101) includes a housing (7) which houses at least one rotor (8) that forms between the housing (7) and the rotor (8) at least one working chamber (I - IN) having between a high-pressure inlet port (6) and a low-pressure outlet port (15) a sub-chamber that forms an expansion chamber, and also having between the low-pressure outlet port (15) and a high-pressure outlet port (20) a sub-chamber that forms a compression chamber, wherein the low-pressure outlet port (15) is disposed between the expansion chamber and the compression chamber and functions to output the liquid phase to the evapo-

AMEΝDED SHEET (ARTICLE 19) rator arrangement (17), and wherein the high-pressure outlet port (20) is adapted to output the gas phase to the condenser (4).

19. Refrigerating plant according to one or more of Claims 16 - 18, characterized in that the low-pressure outlet port (15) includes a control device (30) for adjusting the closing edge (32) of the port ( 15) such as to regulate the absolute volume in the working chamber when closing the low-pressure outlet port (15).

20. Refrigerating plant according to one or more of Claims 16 - 18, characterized by mechanical or electrical brake means (B) for controlling the rotational speed of the rotor (8).

21. Refrigerating plant according to one or more of Claims 16 - 18, characterized in that the high-pressure inlet port (6) includes a control device (39) for adjusting the closing edge of the port (6) such as to regulate the stroke volume of the expansion chamber.

22. Refrigerating plant according to one or more of Claims 16 - 18, characterized in that the high-pressure outlet port (20) includes a control device (38) for adjusting the opening edge of the port (20) such as to regulate the volumetric ratio in the compression chamber. 75578

23. Refrigerating plant according to Claims 18, characterized in that one or more of said control means (30, 35, 38, 39) includes/include a slide valve or several successively actuatable lift valves controlled by a microprocessor or some other control means.

24. A method of improving the refrigerating capacity of a refrigerating system that includes a compressor (2), a condenser (4), a phase separator (1, 101), an evaporator arrangement (17) connected in series by conduits (3, 5, 16 and 18 respectively) to form a closed refrigerant loop, said method comprising the steps of subjecting refrigerant entering the phase separator (1, 101) to pressure reduction and separation into an essen- tially gas-containing gas phase and an essentially liquid-containing liquid phase, and discharging the liquid phase through a low-pressure outlet port (15, 115), characterized by compressing the gas phase and thereafter discharging the gas phase to the compressor (2) and/or the condenser (4).

28. A method according to Claim 24, characterized by delivering the gas phase both to an intermediate pressure port (33) of the compressor (2) and a compressor inlet port

(19).

29. A method according to any one of Claims 24 - 27, characterized by controlling the flow of gas phase from the phase separator (1,101) with the aid of a control valve (24, 124).