GB2086024A

GB2086024A - Dual economized refrigeration system

Info

Publication number: GB2086024A
Application number: GB8030791A
Authority: GB
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 1977-08-29
Filing date: 1978-08-29
Publication date: 1982-05-06
Also published as: JPS5490645A; FR2402169B1; JPS6022250B2; GB2003264A; DE2837695C2; FR2402169A1; GB2003264B; AU3934378A; AU523862B2; GB2086024B; DE2837695A1

Abstract

A vapor compression refrigeration system has a compressor (11), a main condenser (22), a condensing economizer (31), a thermal economizer (29) and a chiller or evaporator (36) connected to form a primary refrigerant loop, and a second compressor (17) connected to partially form a secondary refrigerant loop. Gaseous refrigerant from the thermal economizer is condensed by an economizer-condenser (58) and then flashed in the condensing economizer (31). The gaseous refrigerant from the condensing economizer is recompressed by the second compressor (17) and thereafter recondensed by the economizer-condenser (58). <IMAGE>

Description

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SPECIFICATION

Dual economized refrigeration system

The present invention relates to vapor compression refrigeration systems which are 5 adapted to cool a fluid for domestic or other uses. More particularly, the present invention relates to a vapor compression refrigeration system with two compressors, the second compressor receiving flashed gaseous refrigerant from a flash 10 economizer and recompressing the gaseous refrigerant so that it may be used within the refrigeration system for absorbing heat from the fluid to be cooled.

Refrigeration systems of vapor compression 15 type typically employ a compressor to increase the temperature and pressure of a gaseous refrigerant. Connected thereto is a condenser wherein the gaseous refrigerant is sufficiently cooled to change state to a liquid refrigerant. Thereafter the 20 refrigerant may be subcooled in a flash economizer wherein part of the refrigerant is vaporized absorbing heat from the remaining liquid refrigerant. The vaporized refrigerant has been typically drawn into the compressor for 25 recycling through the condenser and the liquid refrigerant which has now been cooled passes on to the evaporator or chiller. In the chiller, the refrigerant is evaporated absorbing heat from the fluid to be cooled, the now gaseous refrigerant 30 being drawn into the compressor to complete the cycle. In the above described refrigeration system, the compressor is a multi-stage compressor such that the flashed refrigerant from the flash economizer may be drawn into the compressor 35 between the stages allowing the flash economizer to be at an intermediate pressure to the condenser and the chiller.

There are two types of flash economizers, a condensing economizer having a compressor or 40 other means for physically removing the flashed gas from the economizer and a thermal economizer wherein the flashed gas is recondensed using a heat exchanger.

The basic patent dealing with a flash 45 economizer was issued in 1942. Therein the flash economizer was located between the condenser and the evaporator and the flashed gaseous refrigerant therefrom was drawn into the compressor between the first and second stages 50 and the liquid refrigerant which has been cooled in the flashing process is allowed to travel to the evaporator.

Other types of multi-stage compressors have been used with various economizers. There has 55 been disclosed a refrigerant system having an evaporator and a condenser wherein the flash economizer is located therebetween, the flash gas, being drawn into the second stage of a two stage compressor and the liquid refrigerant passing 60 through the condenser and to the machine for cooling of the electric motor.

An economizer has been used with a centrifugal compressor having a combination impeller blade such that the flashed gas from the

65 economizer may enter the centrifugal compressor in the middle of the blade thereby creating within a single compressor two separate pressure levels. It is also known to utilize an economizer with a single stage compressor such that liquid 70 refrigerant is allowed to flow from the condenser to the economizer wherein gaseous refrigerant is withdrawn into the compressor until such time as the economizer temperature reaches the desired level. At such time a valve opens allowing the 75 refrigerant to be drawn into the chiller from which the compressor removes the flashed refrigerant gas. The compressor runs continuously, however, the suction line to the compressor is cycled alternately between the economizer and 80 the condenser such that the compressor is always withdrawing refrigerant from either the economizer or the condenser and such that the refrigerant passing from the economizer to the condenser is always at the desired temperature. 85 in order to use a flash economizer in an existing single stage compressor vapor compression system a second compressor may be provided such that the flash gas can be compressed. Thereafter by providing an economizer-condenser 90 this recompressed flashed gas may be condensed to a liquid and may be reflashed to further cool itself and the liquid from the initial flashing process. This system is particularly applicable to refrigerants such as trichloromonofluoromethane 95 which are not adaptable to sensible heat subcooling. Consequently, latent heat cooling by means of a change of state is the only practical method to subcool trichloromonofluoromethane and other similar refrigerants.

100 Prior refrigeration systems utilizing a flash economizer have required a multiple stage compressor to provide varying pressure levels for the flashing to occur. Refrigeration systems with a single stage compressor have previously not been 105 adaptable for retrofit machinery to provide a flash economizing step since the pressure differential required has not been obtainable. The refrigeration system described hereafter is adaptable to be retrofitted to a single stage centrifugal compressor 110 system so that a second compressor may be provided to recompress the flashed gas from the flash economizer. The provision of an economizer-condenser which would condense the recompressed flashed gas aids the overall 115 efficiency of the system.

The present invention provides a vapor compression refrigeration system using a refrigerant for cooling a fluid which comprises a first compressor for increasing the temperature 120 and pressure of the gaseous refrigerant; a main condenser connected to the compressor wherein the refrigerant changes state from a gas to a liquid; a thermal economizer connected to the main condenser wherein liquid refrigerant is 125 flashed from a high pressure to a low pressure and part of said refrigerant changes state from a liquid to a gas, absorbing heat from the remaining liquid refrigerant; an economizer-condenser in communication with the gaseous refrigerant from

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the thermal economizer for cooling said gaseous refrigerant to change its state from a gas to a liquid; a condensing economizer connected to the thermal economizer to receive liquid refrigerant 5 therefrom, wherein said liquid refrigerant is flashed so that part of the refrigerant changes state from a liquid to a gas, absorbing heat from the remaining liquid refrigerant; a second compressor connected to the condensing 10 economizer so that the flashed refrigerant therefrom is drawn into the second compressor where the temperature and pressure of the flashed refrigerant is increased; connecting means between the second compressor and the thermal 15 economizer for delivering the gaseous refrigerant from the second compressor to the thermal economizer; and a chiller for cooling the fluid, said chiller being connected for receiving liquid refrigerant from the condensing economizer and 20 for discharging gaseous refrigerant to the first compressor.

The invention also provides a flash gas refrigeration loop for use in a refrigeration system having a thermal economizer and a condensing 25 economizer connected in series through which a refrigerant circulates, which loop comprises a compressor connected to receive gaseous refrigerant from the condensing economizer and an economizer-condenser, connected to receive 30 hot gaseous refrigerant from the compressor, where said refrigerant is cooled so that it changes state from a gas to a liquid.

The invention further provides a method of cooling a fluid with a refrigeration system utilizing 35 a refrigerant, which method comprises the steps of compressing the gaseous refrigerant to increase its temperature and pressure; condensing the gaseous refrigerant to a liquid refrigerant; flashing the refrigerant so that part of the liquid refrigerant 40 changes state from a liquid to a gas absorbing heat from the remaining liquid refrigerant; condensing gaseous refrigerant from the step of flashing to a liquid; reflashing the liquid refrigerant in a low temperature condensing economizer; 45 recompressing the flash gas from the step of reflashing; recondensing the gaseous refrigerant received from the step of recompressing simultaneously with the step of condensing gaseous refrigerant from the step of flashing; and 50 evaporating the liquid refrigerant in a heat exchanger to absorb heat from the fluid to be cooled, wherein the refrigerant changes state from a liquid to a gas so that the refrigerant may be cycled to the step of compressing. 55 The invention still further provides a method of cooling a fluid within a refrigeration system comprising a refrigerant loop including a thermal economizer and a condensing economizer wherein the pressure of the refrigerant is reduced in each 60 so that part of the liquid refrigerant changes state to a gas absorbing heat from the remaining liquid refrigerant, which method comprises the steps of compressing the gaseous refrigerant from the condensing economizer and condensing to a liquid 65 the gaseous refrigerant received from the compressing step, said condensing step taking place in the presence of both the gaseous refrigerant from the compressor and the flash gas from the thermal economizer so that both gases are simultaneously condensed to a liquid.

Figure 1 is a schematic diagram of a vapor compression refrigeration system utilizing the present invention.

Figure 2 is a pressure enthalpy graph showing the refrigeration cycle of the system depicted in Figure 1.

Figure 3 is a schematic diagram of a "piggyback" compressor for use with the refrigeration system of Figure 1.

The embodiment of the invention described below is adapted for use in a vapor compression refrigeration system having a single stage compressor, a condenser, and an evaporator or chiller. It is to be understood that the present invention finds applicability in refrigeration systems other than single stage vapor compression systems. The present invention is further adapted so that multiple condensers are available within a single refrigeration system. These multiple condensers may be used as disclosed herein or in other types of refrigeration systems.

Referring to Figure 1, a schematic drawing of a vapor compression refrigeration system, it can be seen that a dual channel compressor 10 is provided having two separate centrifugal compressors 11 and 17 located on a single axis driven by an electric motor 33. A primary compressor 11 has increased temperature and pressure refrigerant gas exiting therefrom at outlet 14 into line 20. From line 20 the gaseous refrigerant enters condenser 22 wherein it changes state to a liquid refrigerant. The liquid refrigerant is collected in the bottom of condenser 22 and then transported through line 24 to thermal economizer 29. In the thermal economizer liquid refrigerant is flashed through nozzles 26 such that part of the refrigerant changes state to a gas absorbing heat from the remaining liquid refrigerant. Liquid refrigerant then collects at the bottom of thermal economizer shown as reservoir 30. Therefrom via line 23, the liquid refrigerant is conducted to condensing economizer 31 wherein the liquid refrigerant is flashed through nozzles 25 such that part of the refrigerant changes state to a gas absorbing heat from the remaining liquid refrigerant. The liquid refrigerant from the condensing economizer collects in reservoir 44 and is therefrom conducted via line 32 to expansion control device 34. The pressure of the liquid refrigerant is reduced in the expansion control device and therefrom the liquid refrigerant travels to chiller 36 wherein the liquid changes state to a gas absorbing heat from the fluid to be cooled as it passes through the chiller. Line 40 then conducts the gaseous refrigerant from the chiller to inlet 12 of compressor 11 wherein the gaseous refrigerant is recompressed to commence the cycle again. Flashed refrigerant gas within the thermal economizer 29 is recondensed by

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economizer-condenser 58 mounted therein. This recondensed liquid refrigerant is collected in reservoir 30 and is conducted therefrom to the condensing economizer through conduit 23 with 5 the remaining liquid refrigerant within the thermal economizer from condenser 22. The flashed refrigerant in condensing economizer 31 is drawn into compressor 17 at inlet 16. Increased temperature and pressure refrigerant exits the 10 compressor at outlet 18 and is discharged through line 48 into the thermal economizer 29. Therein this recompressed refrigerant is recondensed by the economizer-condenser simultaneously with the flash gas from nozzles 26 being condensed 15 within the thermal economizer.

Within chiller 36 is located a coil 38 over which refrigerant flows. Water to be cooled enters chiller 36 through line 64 and then flows through the coil 38 in heat exchange relationship with the 20 refrigerant. The now cooled water exits through line 66 to the enclosure to be cooled.

Connected to the economizer-condenser coil 58 is line 52 for supplying entering condensing water thereto and line 54 for conducting the now 25 heated condensing water therefrom. Line 54 connects the discharge from economizer-condenser coil 58 with the inlet to coil 60 of condenser 22. The condensing water that enters the economizer-condenser is thus serially 30 connected to condenser coil 60 where it absorbs heat from the gaseous refrigerant from compressor 11 such that the refrigerant changes state from a gas to a liquid. The condensing water then exits from condenser coil 60 through 35 conduit 56. Additional condensing water may be supplied to condenser 22 depending upon the load requirements.

Compressor 11 increases the pressure of the gaseous refrigerant to Pv Thereafter the pressure 40 of the refrigerant is decreased in the thermal economizer to P2- The refrigerant is then flashed in the condensing economizer which operates at pressure P3. Therefrom flashed refrigerant is drawn into compressor 17 where its pressure is 45 increased to P2. Liquid refrigerant exits the condensing economizer at P3 and travels to the expansion control device wherein its pressure is reduced to P4. The refrigerant travels through the chiller and enters compressor 11 at P4 wherein its 50 pressure again is increased to Pv

Figure 2 is a graph of a pressure versus enthalpy for a typical refrigerant such as trichloromonofluoromethane which is used within the system shown in Figure 1. Starting at Point A 55 thereon it can be seen that the pressure and enthalpy of the refrigerant is increased from Point A to Point B, said distance representing the change in pressure and enthalpy due to the increase in pressure and temperature by 60 compressor 11 acting on the refrigerant. From Point B to C represents the change in enthalpy in condenser 22 as the gaseous refrigerant changes state to a liquid refrigerant. Thereafter in the thermal economizer the refrigerant travels from 65 Point C to Point D representing the pressure decrease as the refrigerant is flashed. From Point D the liquid refrigerant is cooled to Point E and the gaseous refrigerant is heated to Point J as it absorbs heat from the cooled liquid refrigerant. 70 The economizer-condenser acts to thermally cool the refrigerant at Point J such that the gaseous refrigerant from J becomes liquid refrigerant at Point E.

In the condensing economizer the liquid 75 refrigerant is decreased in pressure from Point E to Point G; during this drop in pressure part of the refrigerant vaporizes absorbing heat from the remaining liquid refrigerant, the liquid refrigerant going from Point G to Point K and the gaseous 80 refrigerant from Point G to Point H. Compressor 17 acting on the refrigerant at Point H increases its pressure and enthalpy to Point I. This recompressed refrigerant is then recondensed by the economizer-condenser travelling from Point I 85 to Point E. The recompressed refrigerant then travels to the condensing economizer wherein it is recycled to the pressure of Point G. Liquid refrigerant at Point K is decreased in pressure at the expansion control device to Point L. In the 90 chiller heat is absorbed from the fluid to be cooled and the amount of heat to be absorbed is proportionate to the distance from Point L to Point A, Point A being the starting point of the cycle. As can be seen in Figures 1 and 2, Pv P2, P3 95 and P4 are indicated on both showing the respective pressure relationships.

In order to obtain the most cooling work from a given amount of refrigerant it is desirable to cool the refrigerant as close as possible to the left side 100 of the curve such that when the refrigerant is flashed in the chiller, as much heat as possible indicated by the distance from L to A is absorbed from the refrigerant to be cooled. Without the dual stage condensing and thermal economizers it is 105 obvious that the heat available to be absorbed by the refrigerant is proportional to the distance represented in the graph by the line from X to A, Point X being the point to which the refrigerant would travel from Point C if the pressure were 110 decreased to P in one step. By the provision of the dual flash and condensing economizers the refrigerant is cooled to Point L allowing the heat to be absorbed from the refrigerant to be increased to be proportional to the distance indicated by the 115 line L to A. This increase in the length from distance XA to distance LA represents an overall efficiency increase in the amount of heat that may be absorbed within the refrigeration system.

The thermal economizer and the condensing 120 economizer are shown each mounted within half of a cylinder 42 in Figure 1. The cylinder 42 is divided by center plate 62 into a condensing economizer and a thermal economizer which operate at separate pressures. Refrigerant travels 125 through line 23 from the thermal economizer to the condensing economizer and also travels through the line 50, compressor 17 and line 48 from the condensing economizer to the thermal economizer. This physical arrangement is 130 described merely to indicate that the thermal

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economizer and the condensing economizer may be fitted within a portion of the conventional refrigeration machine utilizing cylindrical pressured compartments. Furthermore this 5 arrangement is described to indicate that the economizer-condenser may be physically located within the pressure vessel making up the thermal economizer.

Referring now to Figure 3, a schematic drawing 10 of a "piggyback" compressor, it can be seen that this "piggyback" compressor may be advantageously utilized within the above described vapor compression refrigeration system. A motor 33 is mounted to drive primary impeller 15 88 and secondary impeller 89. The secondary impeller is mounted to primary impeller 88 such that when the motor drives the primary impeller, the secondary impeller will also be driven. However, the secondary impeller is mounted on 20 the primary impeller in such a manner that the flow paths of the refrigerant being compressed by the primary impeller and the secondary impeller are separated by cover or shroud 91 of the primary impeller. The primary impeller is a closed type 25 impeller since shroud 91 is located thereon. The word "piggyback" in reference to this compressor refers to the fact that the secondary impeller is mounted to the primary impeller such that when one operates the other operates. The schematic 30 diagram shown in Figure 3 is designed to be compatible with the system shown in Figure 1 having the "piggyback" compressor of Figure 3 substituted for the dual compressors of Figure 1.

As shown in Figure 3, the primary impeller 88 35 receives refrigerant at pressure P4 through conduit 40 at inlet 12. The refrigerant then proceeds along the primary flow path 92 and has its temperature and pressure increased as it flows along said path. The now increased temperature and pressure 40 refrigerant is discharged at outlet 14 into conduit 20 at pressure P,. Simultaneously therewith, refrigerant is received through conduit 50 into inlet 16 at pressure P3. The refrigerant enters the secondary impeller through inlet 16 and travels 45 along secondary flow path 93. The refrigerant is then discharged from secondary impeller 89 through outlet 18 into conduit 48, the refrigerant pressure then being at P2.

Referring now to the combination of Figures 1 50 and 3, it can be seen that the refrigerant entering the primary impeller through conduit 40 is the flashed gaseous refrigerant coming from chiller 36. The refrigerant being discharged from primarv impeller 88 into conduit 20 travels to the 55 condenser 22. The refrigerant received from conduit 50 at pressure P3 is the flashed gaseous refrigerant from the condensing economizer 31. The refrigerant being discharged through outlet 18 into conduit 48 from the secondary impeller 60 travels to the thermal economizer 29. As can be seen from the above description, the "piggyback" compressor may be substituted for the dual channel compressor shown in Figure 1.

Claims

1. A vapor compression refrigeration system using a refrigerant for cooling a fluid which comprises a first compressor for increasing the temperature and pressure of the gaseous refrigerant; a main condenser connected to the compressor wherein the refrigerant changes state from a gas to a liquid; a thermal economizer connected to the main condenser wherein liquid refrigerant is flashed from a high pressure to a low pressure and part of said refrigerant changes state from a liquid to a gas, absorbing heat from the remaining liquid refrigerant; an economizer-condenser in communication with the gaseous refrigerant from the thermal economizer for cooling said gaseous refrigerant to change its state from a gas to a liquid; a condensing economizer connected to the thermal economizer to receive liquid refrigerant therefrom, wherein said liquid refrigerant is flashed so that part of the refrigerant changes state from a liquid to a gas, absorbing heat from the remaining liquid refrigerant; a second compressor connected to the condensing economizer so that the flashed refrigerant therefrom is drawn into the second compressor where the temperature and pressure of the flashed refrigerant is increased; connecting means between the second compressor and the thermal economizer for delivering the gaseous refrigerant from the second compressor to the thermal economizer; and a chiller for cooling the fluid, said chiller being connected for receiving liquid refrigerant from the condensing economizer and for discharging gaseous refrigerant to the first compressor.

2. The invention as set forth in claim 1 wherein the thermal economizer and the condensing economizer are contained in a single cylindrical shell divided by a center plate into two portions, one for the thermal economizer and one for the condensing economizer.

3. The invention as set forth in claim 1 or claim 2 wherein the economizer-condenser is mounted within the thermal economizer in communication with both the flashed gaseous refrigerant from the main condenser and the compressed gaseous refrigerant from the second compressor.

4. The invention as set forth in any one of the preceding claims wherein the first compressor is a primary channel of a dual channel centrifugal compressor and the second compressor is the secondary channel of the same dual channel centrifugal compressor.

5. The invention as set forth in any one of the preceding claims wherein the economizer-condenser and the main condenser are cooled by condenser water which is circulated in series through the economizer-condenser and then through the main condenser so that the economizer-condenser receives the lower temperature condensing water.

6. A vapor compression refrigeration system

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utilizing a refrigerant to cool a fluid which comprises a primary refrigerant loop having a first compressor for discharging refrigerant at increased temperature and pressure; a condenser 5 connected to receive the refrigerant from the first compressor wherein the refrigerant is converted from a gas to a liquid; a thermal economizer connected to the condenser wherein the liquid refrigerant is partially flashed to a gaseous 10 refrigerant absorbing heat from the remaining liquid refrigerant; a condensing economizer connected to the thermal economizer wherein the liquid refrigerant from the thermal economizer is partially reflashed to a gaseous refrigerant 15 absorbing heat from the remaining liquid refrigerant; an expansion control device connected to receive liquid refrigerant from the condensing economizer wherein the refrigerant pressure is reduced; and a chiller connected to receive 20 refrigerant from the expansion control device and to discharge refrigerant to the first compressor, wherein at least part of said refrigerant changes state from a liquid to a gas to absorb heat from the fluid to be cooled; and a secondary refrigerant 25 loop having a second compressor connected to receive flashed gaseous refrigerant from the condensing economizer; a thermal economizer connected to receive gaseous refrigerant from the second compressor wherein the state of the 30 refrigerant is changed from a gas to a liquid simultaneously with the gas from the thermal economizer being changed from a gas to a liquid, the liquid refrigerant both from the condenser and the second compressor then being connected to 35 the condensing economizer of the primary refrigerant loop.

7. The invention as set forth in claim 6 wherein the first compressor and the second compressor comprise a single centrifugal compressor having

40 dual channels, one channel for the primary refrigeration loop and one channel for the secondary refrigeration loop.

8. The invention as set forth in claim 6 or claim 7 wherein the thermal economizer and the

45 condenser are both cooled by cooling water, said cooling water flowing first to the thermal economizer and then to the condenser.

9. The invention as set forth in any one of claims 6 to 8 wherein the thermal economizer

50 comprises an economizer-condenser located within the thermal economizer and in communication with the gaseous refrigerant both from the main condenser and from the second compressor.

55 10. A flash gas refrigeration loop for use in a refrigeration system having a thermal economizer and a condensing economizer connected in series through which a refrigerant circulates, which loop comprises a compressor connected to receive 60 gaseous refrigerant from the condensing economizer and an economizer-condenser, connected to receive hot gaseous refrigerant from the compressor, wherein said refrigerant is cooled so that it changes state from a gas to a liquid. 65 11. A method of cooling a fluid within a refrigeration system utilizing a refrigerant, which method comprises the steps of compressing the gaseous refrigerant to increase its temperature and pressure; condensing the gaseous refrigerant 70 to a liquid refrigerant; flashing the refrigerant so that part of the liquid refrigerant changes state from a liquid to a gas absorbing heat from the remaining liquid refrigerant; condensing gaseous refrigerant from the step of flashing to a liquid; 75 reflashing the liquid refrigerant in a low temperature condensing economizer; recompressing the flash gas from the step of reflashing; recondensing the gaseous refrigerant received from the step of recompressing 80 simultaneously with the step of condensing gaseous refrigerant from the step of flashing; and evaporating the liquid refrigerant in a heat exchanger to absorb heat from the fluid to be cooled, wherein the refrigerant changes state from 85 a liquid to a gas so that the refrigerant may be cycled to the step of compressing.

12. A method of cooling a fluid within a refrigeration system comprising a refrigerant loop including a thermal economizer and a condensing

90 economizer wherein the pressure of the refrigerant is reduced in each so that part of the liquid refrigerant changes state to a gas absorbing heat from the remaining liquid refrigerant, which method comprises the steps of compressing the 95 gaseous refrigerant from the condensing economizer and condensing to a liquid the gaseous refrigerant received from the compressing step, said condensing step taking place in the presence of both the gaseous 100 refrigerant from the compressor and the flash gas from the thermal economizer so that both gases are simultaneously condensed to a liquid.

13. The method as set forth in claim 12 wherein the thermal economizer has located

105 therein an economizer-condenser.

14. A vapor compression refrigeration system using a refrigerant for cooling a fluid which comprises a compressor system having a primary impeller for increasing the temperature and

110 pressure of the refrigerant and a secondary impeller mounted to the primary impeller but having a separate flow path therefrom also for increasing the temperature and pressure of the refrigerant; a main condenser, connected to 115 receive increased temperature and pressure refrigerant from the primary impeller, wherein the refrigerant changes state from a gas to a liquid; a thermal economizer, connected to the main condenser, wherein liquid refrigerant is flashed 120 from a high pressure to a low pressure and part of said refrigerant changes state from a liquid to a gas, absorbing heat from the remajning liquid refrigerant; an economizer-condenser, in communication with the gaseous refrigerant of the 125 thermal economizer, for cooling said gaseous refrigerant to change its state from a gas to a liquid; a condensing economizer, connected to receive liquid refrigerant from the thermal economizer, wherein said liquid refrigerant is 130 flashed so that part of the refrigerant changes

6. A vapor compression refrigeration system utilizing a refrigerant to cool a fluid which 55 comprises a primary refrigerant loop having a first compressor for discharging refrigerant at increased temperature and pressure; a condenser connected to receive the refrigerant from the first compressor wherein the refrigerant is converted 60 from a gas to a liquid; a thermal economizer connected to the condenser wherein the liquid refrigerant is partially flashed to a gaseous refrigerant absorbing heat from the remaining liquid refrigerant; a condensing economizer 65 connected to the thermal economizer wherein the liquid refrigerant from the thermal economizer is partially reflashed to a gaseous refrigerant absorbing heat from the remaining liquid refrigerant; an expansion control device connected 70 to receive liquid refrigerant from the condensing economizer wherein the refrigerant pressure is reduced; and a chiller connected to receive refrigerant from the expansion control device and to discharge refrigerant to the first compressor, 75 wherein at least part of said refrigerant changes state from a liquid to a gas to absorb heat from the fluid to be cooled; and a secondary refrigerant loop having a second compressor connected to receive flashed gaseous refrigerant from the 80 condensing economizer; and the thermal economizer connected to receive gaseous refrigerant from the second compressor wherein the state of the refrigerant is changed from a gas to a liquid simultaneously with the flashed gas 85 from the thermal economizer.

-10. A flash gas refrigeration loop for use in a refrigeration system having a thermal economizer and a condensing economizer connected in series through which a liquid refrigerant circulates, 90 which loop comprises a compressor connected to receive gaseous refrigerant from the condensing economizer and an economizer-condenser mounted in the thermal-economizer, connected to receive hot gaseous refrigerant from the 95 compressor, wherein said refrigerant is cooled so that it changes state from a gas to a liquid simultaneously with the gaseous refrigerant present in the thermal-economizer.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1982. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.

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state from a liquid to a gas absorbing heat from the remaining liquid refrigerant; connecting means connecting the secondary impeller to the condensing economizer so that the flashed 5 refrigerant therefrom is drawn into the secondary impeller wherein the temperature and pressure of the flashed refrigerant is increased; conducting means between the secondary impeller and the thermal economizer for delivering the gaseous 10 refrigerant from the secondary impeller to the thermal economizer; and a chiller for cooling the fluid, said chiller being connected for receiving liquid refrigerant from the condensing economizer and for discharging gaseous refrigerant to the 15 primary impeller.

15. The invention as set forth in claim 14 wherein the thermal economizer and the condensing economizer are contained in a single cylindrical shell divided by a center plate into two

20 portions, one for the thermal economizer and one for the condensing economizer.

16. The invention as set forth in claim 14 or claim 15 wherein the economizer-condenser is mounted within the thermal economizer in

25 communication with both the flashed gaseous refrigerant from the condenser and the compressed gaseous refrigerant from the secondary impeller.

17. The invention as set forth in any one of 30 claims 14 to 16 wherein the primary impeller and the secondary impeller are powered by a single motor and wherein the primary impeller has a flow path of refrigerant entering therein and being discharged therefrom which is separate from the 35 refrigerant flow path of the secondary impeller.

18. The invention as set forth in any one of claims 14 to 17 wherein the economizer-condenser and the main condenser are cooled by water which is circulated in series through the

40 economizer-condenser and then through the main condenser so that the economizer-condenser receives the lower temperature water.

19. A vapor compression refrigeration system substantially as herein described with reference to

45 the accompanying drawings.

. 20. A method of cooling a fluid substantially as herein described with reference to the accompanying drawings.

New claims or amendments to claims filed on 50 26.11.81.

Superseded claims 6 and 10. New or amended claims:—