US20110146313A1 - Refrigeration circuit - Google Patents
Refrigeration circuit Download PDFInfo
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- US20110146313A1 US20110146313A1 US13/003,207 US200913003207A US2011146313A1 US 20110146313 A1 US20110146313 A1 US 20110146313A1 US 200913003207 A US200913003207 A US 200913003207A US 2011146313 A1 US2011146313 A1 US 2011146313A1
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- collecting container
- refrigeration circuit
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- medium pressure
- control valve
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- 238000005057 refrigeration Methods 0.000 title claims abstract description 102
- 239000003507 refrigerant Substances 0.000 claims abstract description 73
- 239000007788 liquid Substances 0.000 claims abstract description 45
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 18
- 230000003247 decreasing effect Effects 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims description 9
- 230000000694 effects Effects 0.000 claims description 4
- 238000000034 method Methods 0.000 description 9
- 238000001816 cooling Methods 0.000 description 4
- 230000008901 benefit Effects 0.000 description 2
- 239000003570 air Substances 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
- F25B49/027—Condenser control arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
- F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
- F25B1/10—Compression machines, plants or systems with non-reversible cycle with multi-stage compression
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2309/00—Gas cycle refrigeration machines
- F25B2309/06—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide
- F25B2309/061—Compression machines, plants or systems characterised by the refrigerant being carbon dioxide with cycle highest pressure above the supercritical pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/01—Heaters
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/04—Refrigeration circuit bypassing means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/22—Refrigeration systems for supermarkets
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/23—Separators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2500/00—Problems to be solved
- F25B2500/31—Low ambient temperatures
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/04—Refrigerant level
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2109—Temperatures of a separator
Definitions
- the invention relates to a refrigeration circuit and to a method of transcritical operation of a refrigeration circuit.
- Current CO 2 refrigeration circuits employ a two-stage expansion where the refrigerant is relieved from a high pressure level to a medium pressure level by a first stage expansion device, and where the expansion devices upstream of the evaporators further expand the refrigerant to a suction pressure level.
- Exemplary embodiments of the invention include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO 2 , circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line having a medium pressure holding valve arranged therein is provided connecting the line between the condenser/gascooler and the high pressure control valve to the line between the collecting container and the expansion device(s); and wherein a control unit is provided said control unit being configured to open the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO 2 , circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line is provided connecting the line after the high pressure control valve to the line between the collecting container and the expansion device(s); wherein a medium pressure holding valve is arranged in the line after the branch-off point of the bypass line and before the collecting container; and wherein a control unit is provided said control unit being configured to close the medium pressure holding valve when the temperature or
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO 2 , circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line having a medium pressure holding valve arranged therein is provided connecting the line after the high pressure control valve to the line between the collecting container and the expansion device(s); and wherein a control unit is provided said control unit being configured to open the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO 2 , circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line is provided connecting the line after the high pressure control valve to the line between the collecting container and the expansion device(s), wherein a medium pressure holding valve is arranged in the line after the collecting container and before the refeed point of the bypass line, and wherein a control unit is provided said control unit being configured to close the medium pressure holding valve when the temperature or
- Exemplary embodiments of the invention further include a Refrigeration circuit having a mono- or multi-component refrigerant, especially CO 2 , circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line having a medium pressure holding valve arranged therein is provided connecting the pressure line after the compressor unit to the line between the condenser/gascooler and the high pressure control valve, and wherein a control unit is provided said control unit being configured to open the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor falls below
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO 2 , circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line having a medium pressure holding valve arranged therein is provided connecting the pressure line to the collecting container or to the flashgas line before the medium pressure control valve, and wherein a control unit is provided said control unit being configured to open the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO 2 , circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a collecting container heating unit arranged in the collecting container, and wherein a control unit is provided said control unit being configured to effect heating operation of the collecting container heating unit when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO 2 , circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler with at least one fan leading air over its surface, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, and wherein a control unit is provided said control unit being configured to lower the performance of the fan(s) when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
- Exemplary embodiments of the invention further include a method for transcritical operation of a refrigeration circuit, in which the medium pressure holding valve is switched accordingly when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
- FIG. 1 shows a schematic view of a first refrigeration circuit according to an embodiment of the invention
- FIG. 2 shows a schematic view of a second refrigeration circuit according to an embodiment of the invention
- FIG. 3 shows a schematic view of a third refrigeration circuit according to an embodiment of the invention
- FIG. 4 shows a schematic view of a fourth refrigeration circuit according to an embodiment of the invention.
- FIG. 5 shows a schematic view of a fifth refrigeration circuit according to an embodiment of the invention.
- FIG. 6 shows a schematic view of a sixth refrigeration circuit according to an embodiment of the invention.
- FIG. 7 shows a schematic view of a seventh refrigeration circuit according to an embodiment of the invention.
- FIG. 8 shows a schematic view of an eighth refrigeration circuit according to an embodiment of the invention.
- FIG. 1 shows a schematic view of a first refrigeration circuit 2 .
- the first refrigeration circuit 2 and all other refrigeration circuits explained with respect to FIGS. 2-8 below, comprise the following corresponding elements that are designated with like reference numerals.
- the refrigeration circuits according to the embodiments of the invention as explained below comprise, in the direction of refrigerant flow, a compressor unit 4 having three compressors connected in parallel, a condenser/gas cooler 6 having two fans 8 and respective fan controls 10 for flowing ambient air over its surface, a high pressure control valve 12 , a collecting container/receiver 14 , where gaseous and liquid refrigerant are separated from each other and collected, and two evaporators 18 and 20 having a respective expansion valve 16 , 20 connected upstream thereof.
- the condenser/gas cooler 6 acts as a condenser when the refrigerant circuit is operating in a subcritical mode and as a gas cooler when the refrigerant circuit is operating in a transcritical mode.
- the gas cooler 6 normally works as a condenser/liquefier.
- the compressors of the compressor unit 4 can also be connected in series.
- a flashgas line 24 having a medium pressure control valve 26 arranged therein connects the gas space, especially a point in the upper portion of the collecting container 14 with the suction line of the compressor unit 4 . Further, a sensor 28 is provided in or at the collecting container 14 , especially in an upper portion thereof.
- the sensor 28 can be configured as temperature sensor measuring the temperature within the collecting container 14 , as pressure sensor sensing the pressure within the collecting container 14 , as liquid level sensor sensing the liquid level of liquid refrigerant in the collecting container 14 or as a combination thereof.
- the high pressure control valve 12 effects the phase change of the refrigerant and only a small temperature decrease in the order of 1° Celsius.
- the number of compressors of the compressor unit 4 the number of the fans 8 and fan controls 10 and the number of evaporators 18 and 22 is only exemplary, and different numbers of such elements can also be provided.
- All refrigeration circuits depicted in FIGS. 1-8 and explained with respect to these figures further comprise a control unit that effects the particular medium pressure control operation in case the sensor senses a too low pressure or temperature within the collecting container 14 or a too high level of liquid refrigerant within the collecting container 14 .
- This situation particularly occurs, when the refrigerant flowing from the high pressure control valve 12 into the collecting container 14 is colder than the refrigerant already collected within the collecting container 14 .
- a pressure and temperature decrease within the collecting container 14 can be avoided and an efficient medium pressure control can be provided that guarantees sufficient cooling performance of the evaporators 18 and 22 .
- Normal pressure levels of the refrigeration circuits depicted in FIGS. 1-8 are as follows: High pressure level between the compressor unit 4 and the high pressure control valve 12 : 100-125 bar approx., medium pressure level between the high pressure control valve 12 and the expansion valves 16 and 20 : 35-36 bar, and suction pressure level between the evaporators 18 and 22 and the compressor unit 4 : 10-26 bar.
- this first refrigeration circuit 2 further comprises a bypass line 30 having a medium pressure holding valve 32 arranged therein.
- This bypass line 30 connects the line between the condenser/gas cooler 6 and the high pressure control valve 12 to the line portion downstream the collecting container 14 at a position between the collecting container 14 and the expansion valves 16 and 20 .
- the medium pressure holding valve 32 which can be a solenoid valve, is connected in parallel with the high pressure control valve 12 and the collecting container 14 .
- the sensor 28 senses a too low pressure or temperature value within the collecting container 14 or a too high liquid level of the liquid refrigerant within the collecting container 14 it opens the medium pressure holding valve 32 such that liquid refrigerant bypasses the high pressure control valve 12 and the collecting container 14 and flows directly into the line portion downstream of the collecting container 14 . Thereby the medium pressure can reliably controlled and it is avoided that refrigerant being colder than the refrigerant collected in the collecting container 14 flows into the collecting container 14 .
- FIG. 2 shows a schematic view of a second refrigeration circuit 34 .
- the second refrigeration circuit 34 comprises, instead of the bypass line 30 and the medium pressure holding valve 32 , a bypass line 38 connecting the line after the high pressure control valve 12 to the line portion downstream the collecting container 14 at a position between the collecting container 14 and the expansion valves 16 and 20 , and a medium pressure holding valve 36 being arranged in the line after the branch off point of the bypass line 38 and before the collecting container 14 .
- a bypass line 38 bypasses the collecting container 14 and the medium pressure holding valve 36 is put in series after the high pressure control valve 12 and after the branch off point of the bypass line 38 .
- the control unit closes the medium pressure holding valve 36 such that the refrigerant bypasses the collecting container 14 over the bypass line 38 . In this way a temperature or pressure decrease in the collecting container 14 can be avoided and the medium pressure within the collecting container can be kept constant.
- bypass pipe needs to be located above the collecting container 14 .
- FIG. 3 shows a schematic view of a third refrigeration circuit 40 .
- the third refrigeration circuit 40 Compared to the second refrigeration circuit 34 , the third refrigeration circuit 40 lacks the medium pressure holding valve 36 and has a medium pressure holding valve 42 arranged in the bypass line 38 instead. In other words, the medium pressure holding valve 42 is incorporated to bypass the collecting container 42 .
- the control unit opens the medium pressure holding valve 42 and refrigerant bypasses the collecting container 14 .
- a temperature or pressure decrease in the collecting container 14 can be reliably avoided.
- a gas phase within the collecting container 14 can be maintained.
- bypass line 38 is placed below the collecting container 14 .
- FIG. 4 shows a schematic view of a fourth refrigeration circuit 44 .
- the medium pressure holding valve 36 upstream of the collecting container 14 is omitted, and a medium pressure holding valve 46 is provided in the line portion downstream of the collecting container 14 at a position after the collecting container 14 and before the refeed point of the bypass line 38 .
- control unit closes the medium pressure holding valve, and liquid refrigerant bypasses the receiver 14 via the bypass line 38 .
- phase change separator can be placed at the branch off point of the bypass line 38 before the collecting container 14 .
- FIG. 5 shows a schematic view of a fifth refrigeration circuit 48 .
- the fifth refrigeration circuit 48 provides a bypass line 50 in parallel to the condenser/gas cooler 6 .
- a medium pressure holding valve 52 is arranged in such bypass line 50 .
- control unit opens the medium pressure holding valve 52 such that hot pressurized refrigerant bypasses the condenser/gas cooler 6 and mixes with the refrigerant having passed the condenser/gas cooler 6 at or after the refeed point of the bypass line 50 .
- FIG. 6 shows a schematic view of a sixth refrigeration circuit 54 .
- the sixth refrigeration circuit 54 comprises a bypass line 56 connecting the pressure line after the compressor unit 4 with the flash gas line 24 at a position close to the collecting container 14 and before the medium pressure control valve 26 .
- the control unit actuates or opens the medium pressure holding valve 58 such that hot gaseous refrigerant flows from the pressure line into the gas space of the collecting container 14 .
- a temperature or pressure decrease in the collecting container 14 can be avoided, and a sufficient amount of gaseous refrigerant within the collecting container 14 can be provided.
- FIG. 7 shows a schematic view of a seventh refrigeration circuit 60 .
- the seventh refrigeration circuit 60 provides two medium pressure control embodiments, that can be employed independently from each other.
- the sixth refrigeration circuit 60 comprises a collecting container heating unit 62 , which in case the temperature or pressure within the collecting container 14 gets too low or the liquid level gets too high, is switched on by the control unit and heats the refrigerant within the collecting container 14 . In particular at high liquid level boiling of the refrigerant will supply sufficient refrigerant gas formation. Hence, a pressure or temperature decrease within the collecting container 14 can be avoided, and a sufficient amount of gaseous refrigerant in the collecting container 14 can be provided.
- the control unit lowers the performance of at least one of the fans 8 , when the temperature or pressure in the collecting container 14 gets too low or the liquid level gets too high.
- the efficiency of the condenser/gas cooler 6 is lowered such that the heat extraction within the condenser/gas cooler is reduced which will supply sufficient refrigerant in gaseous form to the collecting container 14 .
- Such lowered performance of the condenser/gas cooler 6 can either be achieved by switching off fans or stage-wise reduction of the fans running, or a variable speed drive can be provided or integrated in the control unit that continuously lowers the performance of the fans 8 .
- FIG. 8 shows a schematic view of an eighth refrigeration circuit 64 .
- the eighth refrigeration circuit 64 comprises, as an exemplary embodiment, all medium pressure control units of the first to seventh refrigeration circuits 2 , 34 , 40 , 44 , 48 , 54 and 60 , namely the collecting container bypass line 30 and the medium pressure holding valve 32 , the collecting container bypass line 38 and the medium pressure holding valves 36 , 42 and 46 , the condenser/gas cooler bypass line 50 and the medium pressure holding valve 52 , the bypass line 56 and the medium pressure holding valve 58 , the collecting container heating unit 62 and the fan performance control.
- At least one of a pressure sensor, a temperature sensor and a liquid level sensor is provided in or at the collecting container 14 , and the sensed values are transmitted to and used by the control unit which in turn actuates the respective medium pressure holding valves 32 , 36 , 42 , 46 , 52 and 58 , and/or the collecting container heating unit 62 and/or the fan(s) 8 .
- the refrigerant circuits of the invention can be operated with any conventional refrigerant.
- CO 2 can be circulated within the refrigerant circuits. More particularly, CO 2 can be used as refrigerant, and the refrigeration circuit can be operated in a transcritical mode.
- a reliable and energy efficient medium pressure control of transcritical refrigeration systems, especially transcritical CO 2 refrigeration systems within the collecting container in the event of low ambient temperatures is attained.
- All exemplary embodiments of the invention, as described herein, have one more benefit: they save on energy consumption.
- the high pressure control valve 12 which acts as a first stage expansion device and reduces the pressure of the cooled refrigerant before entering the refrigerant collecting container 14 to the medium pressure level high pressure refrigerant can be avoided from entering the supermarket.
- the liquid refrigerant from the collecting container 14 is sent to the evaporators 18 , 22 in the supermarket at the medium pressure level to be used in the individual cooling cabinets.
- the vapor from the collecting container 14 is expanded to the suction pressure return line by the medium pressure control valve 26 .
- the medium pressure control units are operated for a comparatively short time frame of a few seconds in order to avoid a temperature or pressure decrease within the collecting container 14 and to ensure that enough gaseous refrigerant is present within the collecting container 14 .
- the medium pressure holding valves 32 , 36 , 42 , 46 , 52 , and 58 can be configured as solenoid valves.
Abstract
A refrigeration circuit has a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line having a medium pressure holding valve arranged therein is provided connecting the line between the condenser/gascooler and the high pressure control valve to the line between the collecting container and the expansion device(s), and wherein a control unit is provided said control unit being configured to open the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
Description
- The invention relates to a refrigeration circuit and to a method of transcritical operation of a refrigeration circuit.
- Current CO2 refrigeration circuits employ a two-stage expansion where the refrigerant is relieved from a high pressure level to a medium pressure level by a first stage expansion device, and where the expansion devices upstream of the evaporators further expand the refrigerant to a suction pressure level.
- When operated at ambient temperatures of less than 10° C. such refrigeration circuits often face the problem of maintaining the medium pressure at a sufficiently high level in order that the evaporators downstream can provide adequate cooling performance. Sometimes the medium pressure collapses, and no refrigerant flow gets to the evaporators in the supermarket which can cause substantial damage to the goods to be sold, since they are no more kept in the necessary temperature range.
- Accordingly, it would be beneficial to provide a refrigeration circuit and a method for transcritical operation of a refrigeration circuit that enable a reliable and sufficient cooling performance even with low ambient temperatures.
- Exemplary embodiments of the invention include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line having a medium pressure holding valve arranged therein is provided connecting the line between the condenser/gascooler and the high pressure control valve to the line between the collecting container and the expansion device(s); and wherein a control unit is provided said control unit being configured to open the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line is provided connecting the line after the high pressure control valve to the line between the collecting container and the expansion device(s); wherein a medium pressure holding valve is arranged in the line after the branch-off point of the bypass line and before the collecting container; and wherein a control unit is provided said control unit being configured to close the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the refrigerant bypasses the collecting container and the medium pressure is prevented from decreasing.
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line having a medium pressure holding valve arranged therein is provided connecting the line after the high pressure control valve to the line between the collecting container and the expansion device(s); and wherein a control unit is provided said control unit being configured to open the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that that the refrigerant bypasses the collecting container and the medium pressure is prevented from decreasing.
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line is provided connecting the line after the high pressure control valve to the line between the collecting container and the expansion device(s), wherein a medium pressure holding valve is arranged in the line after the collecting container and before the refeed point of the bypass line, and wherein a control unit is provided said control unit being configured to close the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the refrigerant bypasses the collecting container and the medium pressure is prevented from decreasing.
- Exemplary embodiments of the invention further include a Refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line having a medium pressure holding valve arranged therein is provided connecting the pressure line after the compressor unit to the line between the condenser/gascooler and the high pressure control valve, and wherein a control unit is provided said control unit being configured to open the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a bypass line having a medium pressure holding valve arranged therein is provided connecting the pressure line to the collecting container or to the flashgas line before the medium pressure control valve, and wherein a control unit is provided said control unit being configured to open the medium pressure holding valve when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, wherein a collecting container heating unit arranged in the collecting container, and wherein a control unit is provided said control unit being configured to effect heating operation of the collecting container heating unit when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
- Exemplary embodiments of the invention further include a refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow, a compressor unit, a condenser/gascooler with at least one fan leading air over its surface, a high pressure control valve, a collecting container, and at least one evaporator having an expansion device connected upstream thereof, wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, wherein a temperature, pressure or liquid level sensor is provided in or at the collecting container, and wherein a control unit is provided said control unit being configured to lower the performance of the fan(s) when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
- Exemplary embodiments of the invention further include a method for transcritical operation of a refrigeration circuit, in which the medium pressure holding valve is switched accordingly when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
- Embodiments of the invention are described in greater detail below with reference to the figures, wherein
-
FIG. 1 shows a schematic view of a first refrigeration circuit according to an embodiment of the invention; -
FIG. 2 shows a schematic view of a second refrigeration circuit according to an embodiment of the invention; -
FIG. 3 shows a schematic view of a third refrigeration circuit according to an embodiment of the invention; -
FIG. 4 shows a schematic view of a fourth refrigeration circuit according to an embodiment of the invention; -
FIG. 5 shows a schematic view of a fifth refrigeration circuit according to an embodiment of the invention; -
FIG. 6 shows a schematic view of a sixth refrigeration circuit according to an embodiment of the invention; -
FIG. 7 shows a schematic view of a seventh refrigeration circuit according to an embodiment of the invention; and -
FIG. 8 shows a schematic view of an eighth refrigeration circuit according to an embodiment of the invention. -
FIG. 1 shows a schematic view of afirst refrigeration circuit 2. - The
first refrigeration circuit 2 and all other refrigeration circuits explained with respect toFIGS. 2-8 below, comprise the following corresponding elements that are designated with like reference numerals. The refrigeration circuits according to the embodiments of the invention as explained below comprise, in the direction of refrigerant flow, acompressor unit 4 having three compressors connected in parallel, a condenser/gas cooler 6 having twofans 8 and respective fan controls 10 for flowing ambient air over its surface, a highpressure control valve 12, a collecting container/receiver 14, where gaseous and liquid refrigerant are separated from each other and collected, and twoevaporators respective expansion valve - The condenser/
gas cooler 6 acts as a condenser when the refrigerant circuit is operating in a subcritical mode and as a gas cooler when the refrigerant circuit is operating in a transcritical mode. When the ambient temperatures are lower than 10° Celsius, thegas cooler 6 normally works as a condenser/liquefier. - The compressors of the
compressor unit 4 can also be connected in series. - A
flashgas line 24 having a mediumpressure control valve 26 arranged therein connects the gas space, especially a point in the upper portion of thecollecting container 14 with the suction line of thecompressor unit 4. Further, asensor 28 is provided in or at thecollecting container 14, especially in an upper portion thereof. - The
sensor 28 can be configured as temperature sensor measuring the temperature within thecollecting container 14, as pressure sensor sensing the pressure within thecollecting container 14, as liquid level sensor sensing the liquid level of liquid refrigerant in thecollecting container 14 or as a combination thereof. - It is further to be mentioned that the high
pressure control valve 12 effects the phase change of the refrigerant and only a small temperature decrease in the order of 1° Celsius. - As a matter of course the number of compressors of the
compressor unit 4, the number of thefans 8 andfan controls 10 and the number ofevaporators - All refrigeration circuits depicted in
FIGS. 1-8 and explained with respect to these figures further comprise a control unit that effects the particular medium pressure control operation in case the sensor senses a too low pressure or temperature within the collectingcontainer 14 or a too high level of liquid refrigerant within thecollecting container 14. This situation particularly occurs, when the refrigerant flowing from the highpressure control valve 12 into thecollecting container 14 is colder than the refrigerant already collected within thecollecting container 14. In this case a pressure and temperature decrease within the collectingcontainer 14 can be avoided and an efficient medium pressure control can be provided that guarantees sufficient cooling performance of theevaporators container 14, the pressure will collapse and the refrigerant circuit will stop operating. This problem is reliably avoided by the refrigeration circuits and the methods for transcritical operation of a refrigerant circuit, according to exemplary embodiments of the invention, as explained below. - Normal pressure levels of the refrigeration circuits depicted in
FIGS. 1-8 are as follows: High pressure level between thecompressor unit 4 and the high pressure control valve 12: 100-125 bar approx., medium pressure level between the highpressure control valve 12 and theexpansion valves 16 and 20: 35-36 bar, and suction pressure level between theevaporators - Reverting now to the
first refrigeration circuit 2, thisfirst refrigeration circuit 2 further comprises abypass line 30 having a mediumpressure holding valve 32 arranged therein. Thisbypass line 30 connects the line between the condenser/gas cooler 6 and the highpressure control valve 12 to the line portion downstream the collectingcontainer 14 at a position between thecollecting container 14 and theexpansion valves pressure holding valve 32, which can be a solenoid valve, is connected in parallel with the highpressure control valve 12 and thecollecting container 14. - If the
sensor 28 senses a too low pressure or temperature value within the collectingcontainer 14 or a too high liquid level of the liquid refrigerant within thecollecting container 14 it opens the mediumpressure holding valve 32 such that liquid refrigerant bypasses the highpressure control valve 12 and the collectingcontainer 14 and flows directly into the line portion downstream of thecollecting container 14. Thereby the medium pressure can reliably controlled and it is avoided that refrigerant being colder than the refrigerant collected in the collectingcontainer 14 flows into thecollecting container 14. -
FIG. 2 shows a schematic view of asecond refrigeration circuit 34. - The
second refrigeration circuit 34 comprises, instead of thebypass line 30 and the mediumpressure holding valve 32, abypass line 38 connecting the line after the highpressure control valve 12 to the line portion downstream the collectingcontainer 14 at a position between thecollecting container 14 and theexpansion valves pressure holding valve 36 being arranged in the line after the branch off point of thebypass line 38 and before thecollecting container 14. In other words, abypass line 38 bypasses thecollecting container 14 and the mediumpressure holding valve 36 is put in series after the highpressure control valve 12 and after the branch off point of thebypass line 38. - If the temperature or pressure in the collecting
container 14 sensed by thesensor 28 falls below a pre-determined threshold or the liquid level in the collecting container sensed by thesensor 28 exceeds a predetermined threshold, the control unit closes the mediumpressure holding valve 36 such that the refrigerant bypasses thecollecting container 14 over thebypass line 38. In this way a temperature or pressure decrease in the collectingcontainer 14 can be avoided and the medium pressure within the collecting container can be kept constant. - In particular the bypass pipe needs to be located above the collecting
container 14. -
FIG. 3 shows a schematic view of a third refrigeration circuit 40. - Compared to the
second refrigeration circuit 34, the third refrigeration circuit 40 lacks the mediumpressure holding valve 36 and has a mediumpressure holding valve 42 arranged in thebypass line 38 instead. In other words, the mediumpressure holding valve 42 is incorporated to bypass thecollecting container 42. - When the temperature or pressure in the collecting
container 14 gets too low or the liquid level gets too high, the control unit opens the mediumpressure holding valve 42 and refrigerant bypasses thecollecting container 14. By such operation a temperature or pressure decrease in the collectingcontainer 14 can be reliably avoided. Furthermore a gas phase within the collectingcontainer 14 can be maintained. - In particular the
bypass line 38 is placed below thecollecting container 14. -
FIG. 4 shows a schematic view of a fourth refrigeration circuit 44. - Compared to the
second refrigeration circuit 34, the mediumpressure holding valve 36 upstream of thecollecting container 14 is omitted, and a mediumpressure holding valve 46 is provided in the line portion downstream of the collectingcontainer 14 at a position after the collectingcontainer 14 and before the refeed point of thebypass line 38. - When the temperature or pressure in the collecting
container 14 gets too low or the liquid level gets too high, the control unit closes the medium pressure holding valve, and liquid refrigerant bypasses thereceiver 14 via thebypass line 38. - To ensure proper functionality during bypass and normal operation, a phase change separator can be placed at the branch off point of the
bypass line 38 before the collectingcontainer 14. -
FIG. 5 shows a schematic view of afifth refrigeration circuit 48. - Instead of bypassing the
collecting container 14 as realized by therefrigeration circuits FIGS. 1-4 , thefifth refrigeration circuit 48 provides abypass line 50 in parallel to the condenser/gas cooler 6. Insuch bypass line 50, a mediumpressure holding valve 52 is arranged. - When the temperature or pressure in the collecting
container 14 gets too low or the liquid level gets too high, the control unit opens the mediumpressure holding valve 52 such that hot pressurized refrigerant bypasses the condenser/gas cooler 6 and mixes with the refrigerant having passed the condenser/gas cooler 6 at or after the refeed point of thebypass line 50. - By this embodiment it is ensured that hot gaseous refrigerant reaches the collecting
container 14, and therefore the temperature and pressure in the collectingcontainer 14 can be increased or at least kept constant and a sufficient amount of gaseous refrigerant in the collectingcontainer 14 can be provided. -
FIG. 6 shows a schematic view of a sixth refrigeration circuit 54. - The sixth refrigeration circuit 54 comprises a
bypass line 56 connecting the pressure line after thecompressor unit 4 with theflash gas line 24 at a position close to the collectingcontainer 14 and before the mediumpressure control valve 26. - When the temperature or pressure within the collecting
container 14 gets too low or the liquid level gets too high, the control unit actuates or opens the mediumpressure holding valve 58 such that hot gaseous refrigerant flows from the pressure line into the gas space of the collectingcontainer 14. By this embodiment, a temperature or pressure decrease in the collectingcontainer 14 can be avoided, and a sufficient amount of gaseous refrigerant within the collectingcontainer 14 can be provided. -
FIG. 7 shows a schematic view of aseventh refrigeration circuit 60. - Instead of providing bypass lines and an additional medium pressure holding valve, the
seventh refrigeration circuit 60 provides two medium pressure control embodiments, that can be employed independently from each other. - As first embodiment, the
sixth refrigeration circuit 60 comprises a collectingcontainer heating unit 62, which in case the temperature or pressure within the collectingcontainer 14 gets too low or the liquid level gets too high, is switched on by the control unit and heats the refrigerant within the collectingcontainer 14. In particular at high liquid level boiling of the refrigerant will supply sufficient refrigerant gas formation. Hence, a pressure or temperature decrease within the collectingcontainer 14 can be avoided, and a sufficient amount of gaseous refrigerant in the collectingcontainer 14 can be provided. - According to a second, alternative embodiment, the control unit lowers the performance of at least one of the
fans 8, when the temperature or pressure in the collectingcontainer 14 gets too low or the liquid level gets too high. By such lowering of the fan performance, the efficiency of the condenser/gas cooler 6 is lowered such that the heat extraction within the condenser/gas cooler is reduced which will supply sufficient refrigerant in gaseous form to the collectingcontainer 14. Such lowered performance of the condenser/gas cooler 6 can either be achieved by switching off fans or stage-wise reduction of the fans running, or a variable speed drive can be provided or integrated in the control unit that continuously lowers the performance of thefans 8. -
FIG. 8 shows a schematic view of aneighth refrigeration circuit 64. - The
eighth refrigeration circuit 64 comprises, as an exemplary embodiment, all medium pressure control units of the first toseventh refrigeration circuits container bypass line 30 and the mediumpressure holding valve 32, the collectingcontainer bypass line 38 and the mediumpressure holding valves cooler bypass line 50 and the mediumpressure holding valve 52, thebypass line 56 and the mediumpressure holding valve 58, the collectingcontainer heating unit 62 and the fan performance control. - In the
eighth refrigeration circuit 64 one, two or more or even all of those medium pressure control units can be employed as appropriate. - It is explicitly disclosed therein, that the medium pressure control units described with respect to
FIGS. 1-7 can be combined in any fashion, and the right to direct claims on any of such combination of measurement units is explicitly reserved. - In all embodiments of the refrigeration circuit, as described herein, at least one of a pressure sensor, a temperature sensor and a liquid level sensor is provided in or at the collecting
container 14, and the sensed values are transmitted to and used by the control unit which in turn actuates the respective mediumpressure holding valves container heating unit 62 and/or the fan(s) 8. - In general, the refrigerant circuits of the invention, as described herein, can be operated with any conventional refrigerant. Particularly, CO2 can be circulated within the refrigerant circuits. More particularly, CO2 can be used as refrigerant, and the refrigeration circuit can be operated in a transcritical mode.
- According to exemplary embodiments of the invention, as described herein, a reliable and energy efficient medium pressure control of transcritical refrigeration systems, especially transcritical CO2 refrigeration systems within the collecting container in the event of low ambient temperatures is attained. All exemplary embodiments of the invention, as described herein, have one more benefit: they save on energy consumption.
- By the high
pressure control valve 12 which acts as a first stage expansion device and reduces the pressure of the cooled refrigerant before entering therefrigerant collecting container 14 to the medium pressure level high pressure refrigerant can be avoided from entering the supermarket. The liquid refrigerant from the collectingcontainer 14 is sent to theevaporators container 14 is expanded to the suction pressure return line by the mediumpressure control valve 26. - By the refrigerant circuits according to exemplary embodiments of the invention, as described herein, a reliable transcritical operation at ambient temperatures of less than 10° Celsius can be attained. Problems as occurring in other refrigeration circuits regarding a medium pressure decrease due to lack of vapor at the high
pressure control valve 12 can reliable avoided and a sufficient flow of refrigerant at an appropriate pressure to the cabinets in the supermarket is ensured. - Under normal conditions it suffices that the medium pressure control units, as described above, are operated for a comparatively short time frame of a few seconds in order to avoid a temperature or pressure decrease within the collecting
container 14 and to ensure that enough gaseous refrigerant is present within the collectingcontainer 14. For this purpose the mediumpressure holding valves - In the claims the features of the refrigeration circuit are defined in detail for the refrigeration circuit. As a matter of course, such features can also be present, as corresponding method steps for the respective methods for transcritical operation of a refrigeration circuit, and for such method claims the same advantages apply as for the respective refrigeration circuit. The right to add such method claims at a later stage of procedure is explicitly reserved.
- While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition many modifications may be made to adopt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention include all embodiments falling within the scope of the dependent claims.
Claims (18)
1. A refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow:
a compressor unit;
a condenser/gascooler;
a high pressure control valve;
a collecting container; and
at least one evaporator having an expansion device connected upstream thereof;
wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and a suction line leading to the compressor unit, characterized in that:
a temperature, pressure or liquid level sensor is provided in or at the collecting container;
a medium pressure holding valve is provided; and
a control unit is provided, said control unit being configured to open the medium pressure holding valve when the temperature or pressure in the collecting, container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
2. The refrigeration circuit of claim 1 , wherein the medium pressure holding valve is disposed in a bypass line connecting a line between the condenser/gascooler and the high pressure control valve to a line between the collecting container and the expansion device(s).
3. The refrigerant circuit of claim 1 further comprising a bypass line is provided connecting a line after the high pressure control valve to a line between the collecting container and the expansion device(s).
4. The refrigerant circuit of claim 3 wherein the medium pressure holding valve is arranged in the line after a branch-off point of the bypass line and before the collecting container.
5. The refrigeration circuit of claim 3 wherein the medium pressure holding valve is disposed in the bypass line.
6. The refrigeration circuit of claim 3 wherein the medium pressure holding valve is arranged in a line after the collecting container and before a refeed point of the bypass line.
7. The refrigeration circuit of claim 6 , wherein a phase-change separator is placed at the branch-off point of the bypass line.
8. The refrigeration circuit of claim 1 , further comprising:
a bypass line connecting the pressure line after the compressor unit to the line between the condenser/gascooler and the high pressure control valve;
wherein the medium pressure holding valve is arranged in the bypass line.
9. The refrigeration circuit of claim 1 , further comprising:
a bypass line having connecting a pressure line to the collecting container or to a flashgas line before the medium pressure control valve;
wherein the medium pressure holding valve is arranged in the bypass line.
10. The refrigeration circuit of claim 1 , wherein the compressor unit comprises a set of compressors.
11. The refrigeration circuit of claim 1 , wherein at least two evaporators having a respective expansion device connected upstream thereof are connected in parallel.
12. A refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow:
a compressor unit;
a condenser/gas cooler;
a high pressure control valve;
a collecting container; and
at least one evaporator having an expansion device connected upstream thereof;
wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and a suction line leading to the compressor unit, characterized in that:
a temperature, pressure or liquid level sensor is provided in or at the collecting container;
a collecting container heating unit arranged in the collecting container;
and a control unit is provided said control unit being configured to effect heating operation of the collecting container heating unit when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
13. The refrigeration circuit of claim 12 , wherein the compressor unit comprises a set of compressors.
14. The refrigeration circuit of claim 12 , wherein at least two evaporators having a respective expansion device connected upstream thereof are connected in parallel.
15. A refrigeration circuit having a mono- or multi-component refrigerant, especially CO2, circulating therein, said refrigeration circuit enabling an transcritical operation, said refrigeration circuit comprising, in the direction of refrigerant flow:
a compressor unit;
a condenser/gascooler with at least one fan leading air over its surface;
a high pressure control valve;
a collecting container; and
at least one evaporator having an expansion device connected upstream thereof;
wherein a flashgas line having a medium pressure control valve arranged therein is provided between an upper portion of the collecting container and the suction line leading to the compressor unit, characterized in that:
a temperature, pressure or liquid level sensor is provided in or at the collecting container;
and a control unit is provided said control unit being configured to lower the performance of the fan(s) when the temperature or pressure in the collecting container sensed by the sensor falls below a predetermined threshold or the liquid level in the collecting container sensed by the sensor exceeds a predetermined threshold, such that the medium pressure is prevented from decreasing.
16. The refrigeration circuit of claim 15 , wherein the control unit comprises a variable speed drive for the fan(s).
17. The refrigeration circuit of claim 15 , wherein the compressor unit comprises a set of compressors.
18. The refrigeration circuit of claim 15 , wherein at least two evaporators having a respective expansion device connected upstream thereof are connected in parallel.
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EP2008005524 | 2008-07-07 | ||
PCT/EP2009/004789 WO2010003590A2 (en) | 2008-07-07 | 2009-07-02 | Refrigeration circuit |
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US9625183B2 (en) * | 2013-01-25 | 2017-04-18 | Emerson Climate Technologies Retail Solutions, Inc. | System and method for control of a transcritical refrigeration system |
US20140208785A1 (en) * | 2013-01-25 | 2014-07-31 | Emerson Climate Technologies Retail Solutions, Inc . | System and method for control of a transcritical refrigeration system |
US10139143B2 (en) * | 2013-12-17 | 2018-11-27 | Lennox Industries Inc. | Air conditioner with multiple expansion devices |
US20150168041A1 (en) * | 2013-12-17 | 2015-06-18 | Lennox Industries Inc. | Air conditioner with multiple expansion devices |
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US9739200B2 (en) | 2013-12-30 | 2017-08-22 | Rolls-Royce Corporation | Cooling systems for high mach applications |
US10773818B2 (en) | 2013-12-30 | 2020-09-15 | Rolls Royce Corporation | Trans-critical CO2 cooling system for aerospace applications |
US10718553B2 (en) * | 2015-02-09 | 2020-07-21 | Carrier Corporation | Refrigeration and heating system |
US20180023867A1 (en) * | 2015-02-09 | 2018-01-25 | Christian Douven | Refrigeration and heating system |
US20180142927A1 (en) * | 2015-05-12 | 2018-05-24 | Carrier Corporation | Ejector refrigeration circuit |
US10724771B2 (en) * | 2015-05-12 | 2020-07-28 | Carrier Corporation | Ejector refrigeration circuit |
US20180252449A1 (en) * | 2015-10-08 | 2018-09-06 | Mitsubishi Electric Corporation | Refrigeration cycle apparatus |
US10767912B2 (en) * | 2015-10-08 | 2020-09-08 | Mitsubishi Electric Corporation | Refrigeration cycle apparatus |
CN108139119A (en) * | 2015-10-08 | 2018-06-08 | 三菱电机株式会社 | Refrigerating circulatory device |
CN105485951A (en) * | 2015-12-15 | 2016-04-13 | 昆明东启科技股份有限公司 | Carbon dioxide heat pump system for improving heating efficiency by utilizing gas-liquid two-phase separator |
US11215386B2 (en) * | 2016-03-31 | 2022-01-04 | Carrier Corporation | Refrigeration circuit |
US20190086130A1 (en) * | 2016-03-31 | 2019-03-21 | Carrier Corporation | Refrigeration circuit |
US10906150B2 (en) | 2018-04-11 | 2021-02-02 | Rolls-Royce North American Technologies Inc | Mechanically pumped system for direct control of two-phase isothermal evaporation |
US20200326114A1 (en) * | 2019-04-10 | 2020-10-15 | Rolls-Royce North American Technologies Inc. | Method for reducing condenser size and power on a heat rejection system |
US11022360B2 (en) * | 2019-04-10 | 2021-06-01 | Rolls-Royce North American Technologies Inc. | Method for reducing condenser size and power on a heat rejection system |
US10921042B2 (en) | 2019-04-10 | 2021-02-16 | Rolls-Royce North American Technologies Inc. | Method for reducing condenser size and power on a heat rejection system |
US20210095907A1 (en) * | 2019-09-30 | 2021-04-01 | Hill Phoenix, Inc. | Systems and methods for condenser diagnostics |
US11047606B2 (en) * | 2019-09-30 | 2021-06-29 | Hill Phoenix, Inc. | Systems and methods for condenser diagnostics |
Also Published As
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---|---|
DK2318782T3 (en) | 2019-04-23 |
WO2010003590A3 (en) | 2010-07-29 |
WO2010003590A2 (en) | 2010-01-14 |
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