Classifications

• • 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
  • F25B49/005—Arrangement or mounting of control or safety devices of safety devices
• • 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
  • F25B2400/0409—Refrigeration circuit bypassing means for the evaporator
• • 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
  • F25B2400/16—Receivers
• • 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
  • F25B2400/19—Pumping down refrigerant from one part of the cycle to another part of the cycle, e.g. when the cycle is changed from cooling to heating, or before a defrost cycle is started
• • 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
  • F25B2500/22—Preventing, detecting or repairing leaks of refrigeration fluids
  • F25B2500/222—Detecting refrigerant leaks
• • 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
• • 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
  • F25B40/00—Subcoolers, desuperheaters or superheaters
  • F25B40/02—Subcoolers
• • 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
  • F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit

Definitions

• the invention is directed to a refrigerating system, and to a method for operating a refrigerating system.
• refrigerating systems include a refrigerating cycle having a compressor, a condenser, a collecting container, an expansion valve, an evaporator and refrigerating circuits circulating a refrigerant like fluorocarbon or chloro- fluorocarbon therethrough.
• refrigerants are often harmful to the environment, and thus it has become obligatory to monitor the amount of such refrigerants in refrigerating systems in predetermined intervals in order to document the leak tightness of such refrigerating systems and to detect existing leaks at an early stage.
• the amount of refrigerant contained in the collecting container can be measured, but such measurements are often inaccurate, and the deviation of the measured amount of refrigerant from the actual amount is often about 3% - 6% which is too much having regard that according to the so-called "F-Gase Verix" leakage ratios of 2% per year may not exceeded.
• Exemplary embodiments of the invention include a refrigerating system comprising a refrigerating cycle having a compressor, a condenser, a collecting container, an expansion device, an evaporator and refrigerating circuits circulating a refrigerant therethrough; a by-pass line comprising a by-pass valve, the by-pass line connecting the gas space of the collecting container with the suction line of the compressor; and a control unit that in operation allows switching between normal operation of the refrigerating cycle and refrigerant col-
• a refrigerating system comprising a refrigerating cycle having a compressor, a condenser, a collecting container, an expansion device, an evaporator and refrigerating circuits circulating a refrigerant therethrough; a liquefying set connected to the collecting con- tainer; a control unit that in operation allows switching between normal operation of the refrigerating cycle and refrigerant collecting operation in which the liquefying set cools the collecting container and reduces the temperature in the condenser below the ambient temperature thereby evaporating the remaining liquid refrigerant in the condenser and leading it into the collecting container.
• Figure 1 shows a schematic diagram of a first refrigerating system according to a first embodiment of the invention
• Figure 2 shows a second refrigerating system according to a second embodiment of the invention.
• Figure 3 shows a third refrigerating system according to a third embodiment of the invention.
• Figure 1 shows a first refrigerating system 2 comprising a main refrigerating cycle and a by-pass line 20 having a by-pass valve 22 arranged therein.
• the main refrigerating cycle comprises, in flowing direction of the refrigerant, a compressor 4, a condenser 6, an optional nonreturn valve 8, a collecting container 10 provided with a capacitive refrigerant fill level measuring unit 12, a solenoid valve 14, an expansion valve 16, an evaporator 18 and refrigerating circuits connecting these elements and circulating a refrigerant therethrough.
• the condenser 6 is provided with two fans flowing air over the surface of the condenser for effecting heat exchange between the air and the refrigerant flowing through the condenser 6.
• the condenser 6 can be supplied with at least one fan or an arbitrary number of fans.
• the air flowing over the surface of the condenser 6 is heated, wherein the refrigerant flowing through the condenser 6 is condensed/liquefied.
• the evaporator 18 is provided with a fan for effecting heat exchange between the refrigerant flowing through the evaporator 18 and the air flowing over the surface of the evaporator 18.
• the evaporator 18 can be supplied with at least one fan or an arbitrary number of fans. In particular, the air flowing over the surface of the evaporator 18 is cooled whereas the refrigerant flowing through the evaporator 18 is heated and evaporated.
• condensed liquid refrigerant collects in the lower part thereof, wherein gaseous refrigerant is present in its upper part, which is also referenced as gas space of the collecting container 10.
• the bypass line 20 connects the gas space of the collecting container 10, parti- cularly the top of the collecting container 10 with the suction line of the compressor 4.
• the bypass valve 22 which can be a solenoid valve or any other appropriate valve, the bypass line 20 can be opened or closed.
• the compressor 4, the valves 14 and 22 and preferably also the fans of the con- denser 6 and the evaporator 18 are controlled by a control unit (not shown).
• control unit switches the refrigerating system 2 from normal operation to refrigerant collecting operation as follows:
• the solenoid valve 14 is closed and the compressor 4 sucks off the refrigerant remaining in the portion of the first refrigerating cycle 2 between the solenoid valve 14 and the compressor 4, especially in the expansion valve 16, in the evaporator 18 and in the refrigerant conduits between the solenoid valve 14 and the compressor 4, until no liquid refrigerant remains in this portion.
• the high-pressure portion of the first refrigerat- ing cycle 2 is formed by the portion between the compressor 4 and the expansion device 16. It is a physical phenomenon applied by the inventor to the re- frigating system and method according to the invention that refrigerant is always led to the coldest place within the cycle.
• the performance of the compressor 4 can be reduced.
• the fill level of the refrigerant in the collecting container 10 can be measured by the capacitive refrigerant fill level measuring unit 12 and such measurement produces a very precise and reliable result.
• the capacitive refrigerant fill level measuring unit 12 is especially pressure and temperature compensated.
• the collecting container 10 could be set to a defined pressure or temperature as well.
• the refrigerant fill level measuring unit 12 is of capacitive kind.
• other methods and devices for measuring the refrigerant fill level within the collecting container 10 can also be provided.
• the deviation of the actual amount of refrigerant contained in the first refrig- erating system 2 from the measured amount of refrigerant collected in the collecting container 10, especially the amount of gaseous refrigerant that remains in the refrigerant conduits and in the condenser 6 is negligible and can be calculated.
• control unit switches the first refrigerant system 2 into the normal operation mode again by closing the bypass valve 22 and by opening the shut off valve 14 again. In case the performance of the compressor 4 has been reduced, it is again increased to normal performance.
• Fig. 1 only one compressor 4, one condenser 6 and one evaporator 18 are depicted.
• a set of compressors, a plurality of condensers, a plurality of expansion valves and a plurality of evaporators can be provided.
• Fig. 2 shows a schematic diagram of a second refrigerating system 24 comprising the main refrigerant cycle according to the first refrigerant system 2 and further comprising a liquefying set 34 for cooling gaseous refrigerant from the collecting container 10.
• the liquefying set 34 comprises an additional compressor 36, an additional condenser 38, an additional expansion device 40 and a heat exchanger 28 being connected to a gaseous refrigerant line 26 coming from the gas space of the collecting container 10 and to a liquid refrigerant return line 30 connecting
• a siphon 32 can be arranged within the liquid refrigerant return line 30.
• the collecting container 10 is cooled in order to become the coldest place on the high-pressure side of the second refrigerating system 24.
• the solenoid valve 14 In normal operation of the second refrigerating system 24, the solenoid valve 14 is open, the compressor 4, the condenser 6 and the evaporator 18 are run- ning, and the liquefying set 34 stands still.
• the compressor 4, the condenser 6, the solenoid valve 14, the evaporator 18, the additional compressor 36 and the additional condenser 38 are controlled by a control unit (not shown).
• control unit switches the refrigerating system 24 from normal operation to refrigerant collecting operation as follows:
• the solenoid valve 14 is closed and the compressor 4 sucks off the refrigerant remaining in the portion of the refrigerating cycle between the solenoid valve 14 and the compressor 4, especially in the expansion valve 16, in the evaporator 18 and in the refrigerant conduits between the solenoid valve 14 and the compressor 4, until no liquid refrigerant remains in this portion.
• the compressor 4 and the condenser 6 are stopped and the liquefying set 34, particularly its additional compressor 36 and its additional condenser 38, is/are started.
• the liquefying set 34 can also be started during suck-off operation of the refrigerant remaining in the portion of the re- frigerating cycle between the solenoid valve 14 and the compressor 4.
• the refrigerant in the liquefying set 34 is compressed by the additional compressor 36, condensed by the additional condenser 38 and expanded and
• Gaseous refrigerant is sucked from the gas space of the collecting container 10 through the gaseous refrigerant line 26 into the heat exchanger 28.
• the refrigerant of the main cycle is cooled down against the refrigerant of the liquefying set 34 and thus condensed.
• a liquid fill level is formed, particularly in an upper portion of the siphon 32.
• the collecting container 10 becomes the coldest place on the high-pressure side, the evaporating pressure and, respectively, temperature of the refrigerant within the condenser 6 is reduced significantly below the ambient temperature thus the remaining portion of liquid refrigerant within the condenser 6 is evaporated and led completely into the collecting container 10.
• the fill level of the refrigerant in the collecting container 10 can be measured by the capacitive refrigerant fill level measuring unit 12, and such measurement produces a very precise and reliable result.
• the amount of gaseous refrigerant remaining in the rest of the second refrigerating system 24 is negligible and can be determined by calculation.
• the control unit stops the operation of the liq- uefying set 34 and switches the second refrigerating system 24 into the normal operation mode again by opening the solenoid valve 14 and by starting the compressor 4, the condenser 6 and the evaporator 18 again.
• FIG. 3 shows a schematic diagram of a third refrigerating system 42 comprising the main refrigerating cycle according to the first refrigerating system 2 and further comprising a liquefying set 44.
• the liquefying set 44 of Fig. 3 is connected directly to the collecting container 10 without the provision of a heat exchanger.
• a gaseous refrigerant line 46 connects the gas space of the collecting container 10, particularly the top portion of the collecting container 10 with the additional compressor 48 and forms its suction line
• the liquid refrigerant return line 54 connects the expansion device 52 to the collecting container 10.
• the liquid refrigerant return line 54 also comprises a siphon 56 arranged therein.
• the input lines of both siphons 32 and 56 of Figs. 2 and 3 are on a higher level as compared to their output lines.
• control unit switches it from normal operation into refrigerant collecting operation as follows:
• the solenoid valve 14 is closed and the compressor 4 sucks off the remaining refrigerant in the portion between the solenoid valve 14 and the compressor 4. Subsequently, the compressor 4 is stopped and the liquefying set 44 is started. Gaseous refrigerant is sucked from the gas space of the collecting container 10 through the gaseous refrigerant line 46 into the compressor 48, compressed therein, condensed against ambient air in the condenser 50 and expanded in the expansion device 52, and the cooled refrigerant is fed back into the collecting container 10. Consequently, the collecting container 10 is cooled and becomes the coldest place on the high-pressure side, the evaporating pressure and, respectively, temperature of the refrigerant in the condenser
• the fill level of the refrigerant in the collecting container 10 can be mea- sured by the capacitive refrigerant fill level measuring unit 12 and the amount of gaseous refrigerant in the remaining portions of the third refrigerating system 42, which is negligible, can be determined by calculation. Such measurement and calculation produce very precise and results.
• control unit stops the operation of the liquefying set 34 and switches the third refrigerating system 42 into normal operation mode again by opening the solenoid valve 14, by starting the compressor 4, the condenser 6 and the evaporator 18 again.
• valves 14 and 16 can be formed as a respective common valve 14, for example as electronic expansion valve. In this case the valve 16 can be omitted.
• the methods for collecting refrigerant in the refrigerating systems as described with respect to Fig. 1, 2 and 3 can be combined as well.
• the collect- ing container 10 can be placed close to the condenser 6 and also outside.
• Exemplary embodiments of the invention allow for a precise measurement of the refrigerant actually contained in the refrigerating system.
• the refrigerating systems according to the embodiments of the invention, as described above, are suitable for use with any refrigerant, especially with flu- orocarbon or chlorofluorocarbon refrigerants.
• the automated monitoring can be effected easily and reliably by the refrigerating system. According to embodiments of the invention, as described above, the efforts needed for such monitoring are substantially reduced, and leakages in the refrigerating cycle can be detected at an early stage. The switching between normal operation and refrigerant collecting operation and the actual measurement can be effected very fast.
• the elements of the refrigerating system may be positioned in an arbitrary environment, in one embodiment of the invention, the collecting container can be positioned near the condenser, especially outdoor.
• the control unit can by any kind of control or computer being capable of controlling the above mentioned elements.
• the collecting container becomes the coldest place within the high-pressure portion of the refrigerating system, and the evaporating pressure and, respectively, temperature within the condenser is controlled such that the re-
• the refrigerant collecting operation is effected by a bypass line having a bypass valve arranged therein.
• a separate liquefying set is coupled to the collecting container in order to cool the collecting container and to reduce the temperature in the condenser below the ambient temperature thereby evaporating the remaining liquid refrigerant in the condenser and leading it into the collecting container.
• the liquefying set comprising an additional compressor, an additional condenser and an additional expansion device is connected directly to the collecting container.
• the liquefying set comprising an additional compressor, an additional condenser and an additional expansion device is coupled to the collecting container, in particular to a cycle line of the collecting container, by means of a heat exchanger.
• shut off valves For switching between normal operation and refrigerant collecting operation at least one shut off valve, especially a solenoid valve can be provided.
• Such shut off valves can be solenoid valves or any other valves having an arbitrary control or drive and being capable of interrupting and reassuming refrigerant flow within a refrigerant conduit.
• pass valve can be formed as shut off valve.
• the switching operation of the shut off valve or the shut off valves is controlled by the control unit. Particularly such control unit controls all existing shut off valves.
• the collecting container is provided with a refrigerant fill level measuring unit, which can be formed as capac- itive measuring unit measuring a floater swimming at the surface of the liquid refrigerant collecting in the collecting container.
• a refrigerant fill level measuring unit which can be formed as capac- itive measuring unit measuring a floater swimming at the surface of the liquid refrigerant collecting in the collecting container.
• Other refrigerant fill level measuring units can be employed as well.
• Exemplary embodiments of the method for operating a refrigerating system in a refrigerant collecting operation allow for a reliable collection of the whole amount of liquid refrigerant in the collecting container and for a precise measurement of such liquid refrigerant.
• the compressor When employing a bypass line, the compressor is running, the gas space of the collecting container is connected with a suction line of the compressor via a bypass valve, and the liquefying pressure in the condenser is kept so low that no condensation is effected in the condenser and thereby any liquid refrigerant in the condenser is evaporated and led into the collecting container.
• This method is easy to carry out and produces reliable results.
• the collecting container When employing a liquefying set, the collecting container is cooled and the temperature in the condenser is reduced below the ambient temperature such that the remaining liquid refrigerant in the condenser is evaporated and led into the collecting container.
• the temperature in the condenser is reduced below the ambient temperature such that the remaining liquid refrigerant in the condenser is evaporated and led into the collecting container.
• the compressor can be switched off during refrigerant collecting operation.
• the refrigerating system and the method for its operation according to embodiments of the invention, as described above, are suitable in combination with any compression cycle effecting refrigeration of the evaporator/cold consumers at temperatures of above 0 degrees Celsius and freezing temperatures of below 0 degrees Celsius.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Devices That Are Associated With Refrigeration Equipment (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Publications (2)

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Cited By (8)

Families Citing this family (1)

• 2009
  • 2009-02-16 EP EP09713379.7A patent/EP2257749B1/de not_active Not-in-force

Non-Patent Citations (1)

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