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
  • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
• • 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
  • F25B2600/00—Control issues
  • F25B2600/25—Control of valves
  • F25B2600/2513—Expansion valves
• • 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
  • F25B2700/2117—Temperatures of an evaporator
  • F25B2700/21174—Temperatures of an evaporator of the refrigerant at the inlet of 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
  • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
  • F25B2700/21—Temperatures
  • F25B2700/2117—Temperatures of an evaporator
  • F25B2700/21175—Temperatures of an evaporator of the refrigerant at the outlet of the evaporator

Definitions

• the present invention relates to a refrigerator and/or freezer having a cooled interior and having a refrigerant circuit designed to cool the cooled interior, wherein the refrigerant circuit comprises an evaporator, a compressor, a condenser and an adjustable expansion valve arranged between the condenser and the evaporator.
• Adjustable expansion valves have long been used in refrigeration circuits, especially for larger cooling capacities, in order to be able to respond to the highly fluctuating operating conditions caused by different temperature levels or speed-controlled components (fans, compressors) and to significantly improve the efficiency and performance of the refrigerant circuit.
• the refrigerant in the evaporator is evaporated as completely as possible, and, on the other hand, that the evaporator is filled predominantly with two-phase refrigerant. This means that both a two-phase leak of the refrigerant from the evaporator and overheating of large areas of the evaporator must be avoided simultaneously.
• superheat control which is used, for example, in the EP0147356 A2 and the CN1380963A
• the temperature at the evaporator outlet and the temperature at the evaporator inlet are measured for the purpose of superheat control.
• the degree of refrigerant superheat is determined from the difference between these two temperature values.
• Reliable measurement of the degree of superheat at the evaporator outlet is a challenge depending on the design and size of the refrigeration circuit.
• This value is determined using two temperature sensors, one at the evaporator inlet (to determine the boiling point) and one at the evaporator outlet. The difference between the two temperatures determines the refrigerant's superheat and is used as a control variable for controlling the expansion valve.
• a temperature sensor at the evaporator outlet detects the refrigerant temperature, and the control system regulates the refrigerant flow so that the refrigerant transition point (the transition between the liquid state and the superheated state) is close to this sensor.
• the control system regulates the refrigerant flow so that the refrigerant transition point (the transition between the liquid state and the superheated state) is close to this sensor.
• the present invention is therefore based on the object of developing a refrigerator and/or freezer of the type mentioned above in such a way that the refrigerant circuit can be operated with the highest possible efficiency.
• the refrigerant circuit further comprises a heat exchanger which is arranged and designed to enable heat transfer between the condenser outlet line and the evaporator outlet line, wherein a first temperature sensor for measuring the evaporation temperature and a second temperature sensor for measuring a second temperature are arranged in or on the heat exchanger and wherein a controller is provided which is designed to determine the difference between the two temperatures and to control or regulate the expansion valve based thereon.
• the invention is further directed to a refrigerator and/or freezer with a cooled interior and with a refrigerant circuit that is designed to cool the cooled interior, wherein the refrigerant circuit comprises an evaporator, a compressor, a condenser and an adjustable expansion valve that is arranged between the condenser and the evaporator, wherein the refrigerant circuit further comprises a heat exchanger that is arranged and designed to enable heat transfer between the condenser outlet line and the evaporator outlet line, wherein the evaporation temperature is derived from the information provided by the compressor and a temperature sensor for measuring a temperature is arranged in or on the heat exchanger and wherein a controller is provided that is designed to determine the temperature difference between the two temperatures and to control the expansion valve based thereon.
• the refrigerant circuit comprises an evaporator, a compressor, a condenser and an adjustable expansion valve that is arranged between the condenser and the evaporator
• the refrigerant circuit further comprises a
• the internal heat exchanger is arranged and configured to transfer heat from the refrigerant flowing from the condenser toward the evaporator to the refrigerant flowing from the evaporator to the compressor.
• the heat exchanger serves to superheat the refrigerant flowing out of the evaporator or to increase the degree of superheat of the refrigerant compared to the evaporator outlet.
• the present invention is therefore based on the idea that the amount of heat transferred in the internal heat exchanger additionally superheats the refrigerant flowing out of the evaporator.
• Measuring the temperature of this superheated refrigerant or a value correlated with it has the advantage that relatively low superheat levels at the evaporator outlet lead to significantly higher and thus more easily measurable superheat levels at the temperature measuring point in or on the heat exchanger.
• a correlation unit is present in which a correlation is stored between the said temperature difference and the degree of superheating of the refrigerant at the evaporator outlet.
• the degree of superheating can be determined from the temperature difference between the evaporation temperature and the temperature of the superheated refrigerant in the heat exchanger.
• the degree of superheating is calculated from the measured temperature difference.
• the temperature is measured in or on the heat exchanger line located between the evaporator outlet and the compressor inlet.
• Adjustable means that the free flow area for the refrigerant in the expansion valve can be changed. This can be achieved, for example, by an electric motor, such as a stepper motor, or by other suitable adjustment means.
• a temperature sensor on the suction line (in the internal heat exchanger) and information about the evaporation temperature are required.
• the state of the refrigerant at the evaporator outlet can be adjusted from two-phase (near vapor saturation) to significantly superheated. This allows for superheat levels that would otherwise be difficult or impossible to measure.
• the second temperature sensor may be arranged on the line of the heat exchanger which is in flow connection with the evaporator outlet line.
• the expansion valve is preferably arranged between the heat exchanger and the evaporator.
• the expansion valve can also be located between the condenser and the heat exchanger.
• the device has a memory in which the degree of superheating of the refrigerant at the evaporator outlet and/or the said temperature difference is stored as a setpoint and that the setting unit is connected to the controller, wherein the controller is designed to control or regulate the expansion valve based on the setpoint.
• the value stored in the memory cannot be changed by the user, but can only be changed by a service technician or at the factory.
• the refrigeration circuit of a refrigerator and/or freezer comprises at least one compressor 1, a condenser 2, an internal heat exchanger 3, a controllable expansion valve 4 and an evaporator 5, which serves to cool the cooled interior (not shown).
• the refrigerant flows from the compressor 1 to the condenser 2, is liquefied there, and then flows through the internal heat exchanger 3 into the expansion valve 4. From there, the refrigerant enters the evaporator 5, where it is partially or completely evaporated.
• the line section from the condenser outlet to the evaporator inlet is called the condenser outlet line.
• the refrigerant enters the internal heat exchanger 3, where it is heated and superheated by the liquid refrigerant from the condenser 2.
• the vaporous refrigerant heated in this way then returns to the compressor 1, forming a closed circuit.
• the line section between the evaporator outlet and the compressor inlet is called the evaporator outlet line.
• the heat exchanger 3 is designed to enable heat transfer between these lines.
• the refrigeration cycle according to Figure 1 is only exemplary in nature and can be extended as desired, e.g. by several condensers or the like.
• a temperature sensor 8 is provided, which is attached to the connecting line between the evaporator 5 and the compressor 1. The measuring point of this temperature sensor 8 is located inside the internal heat exchanger 3.
• the amount of heat transferred in the internal heat exchanger 3 additionally superheats the refrigerant flowing from the evaporator 5 to the compressor 1.
• a superheat value of 0 means that the refrigerant is not yet superheated.
• the black solid line represents the superheat at temperature measuring point 8 and the dashed line represents the superheat at the evaporator outlet 7.
• the hatched area indicates the condition at the evaporator outlet at which the refrigeration circuit operates most efficiently.

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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)

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Citations (3)

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• 2025
  • 2025-01-21 EP EP25153088.7A patent/EP4603766A3/fr active Pending

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