EP2187148A1 - Refrigeration system - Google Patents

Abstract

The refrigeration system (1) has an air impinged condenser, a collector (9), an expansion device (11,13), an evaporator (2,3) and a compressor unit (5, 6) comprising a closed cooling circuit in flow direction of a refrigerant. A heat exchanger (7) recovers heat, where other evaporator is provided with upstream expansion device (15) in the circuit of a heat pump set-up which is integrated in the refrigeration system. An independent claim is included for a method for operating a refrigeration system.

Description

The invention relates to a refrigeration system with integrated heat pump circuit for cooling, air conditioning and heating. A strand of the refrigerant circuit is formed in connection with components of the refrigeration system as a heat pump system. Furthermore, the invention relates to a method for operating a refrigeration system with integrated heat pump circuit.

Refrigeration systems with a variety of evaporators are known as composite refrigeration systems. These systems are used for example in supermarkets in which the evaporators in so-called consumers, such as refrigerators, refrigerators and freezers, are integrated. In this case, cooling capacities are provided at different temperature levels. The different temperature levels cause different pressures during the evaporation of the refrigerant. A conventional composite refrigeration system is based on Fig. 1 explained in more detail.
The refrigeration plant 1 consists of a closed system consisting essentially of the components evaporator 2, 3, compressor 5, 6, condenser 8 and expansion element 11, 13. The evaporating in the evaporator 2, 3 refrigerant at a constant temperature heat, for example in the case of Cooling furniture from the air, which is located inside the furniture. The air cools, heat from the outside is dissipated. After overheating of the vaporized refrigerant this is sucked through a suction line 19, 20 as a connection between the evaporator 2, 3 and compressor 5, 6 from the compressor 5, 6 and compressed to a higher pressure. In addition to the pressure, the temperature of the vaporous refrigerant also increases. The so-called hot gas, also referred to as superheated steam, is fed to the condenser 8 via a pressure line 17, cooled in the condenser 8 to the condensation temperature and then liquefied at a constant temperature. The cooling to condensation temperature will also designated as a dehairing. The liquefaction of the refrigerant starts when the dew line is reached.
When using the refrigeration system 1 within a supermarket, the condenser 8 is outside the market surrounded by outside air. The refrigerant releases the heat absorbed in the evaporator 2, 3 and supplied to the ambient air during the compression. After exiting the condenser 8, the pressure of the liquid refrigerant within an expansion element 11, 13 is lowered to evaporation pressure. As a connection between the condenser 8 and expansion element 11, 13 is a liquid line 18, which branches to feed the individual evaporator 2, 3. The flow of the refrigerant to the individual evaporators is controlled by solenoid valves 10, 12. Following the expansion process, the refrigerant is present as a liquid-vapor mixture and is in turn fed to the evaporator 2, 3. The cycle is closed.
Within such a refrigerant circuit, the arrangement of a refrigerant accumulator 9 is also known, which compensates for the differences in refrigerant quantity during operation within the refrigeration system 1. In particular, in composite refrigeration systems in which a plurality of evaporators 2, 3 are operated in parallel, the use of the refrigerant collector 9 is necessary. Sufficient amount of refrigerant must be made available within the refrigerant circuit of a composite refrigeration system so that all evaporators 2, 3 can be adequately supplied even with maximum refrigeration demand. On the other hand, in the case of low refrigeration requirement, in which individual evaporators 2, 3 are only partially filled or are not even supplied with refrigerant, excess refrigerant must be stored.
In composite refrigeration systems upstream of each evaporator 2, 3, an expansion valve 11, 13 upstream, in which the above-mentioned relaxation or expansion process is realized. In the Fig. 1 shown combinations of evaporator 2, 3 and expansion valve 11, 13 provide merely by way of example in each case represents such a combination, but in each case a multiplicity of combinations can be operated in parallel. The evaporation within the evaporator 2, 3 can take place at different temperature levels or pressure levels.
In addition, instead of individual compressors 5, 6 usually compressor units consisting of several parallel operated compressors used. Depending on the pressures applied to the respective suction side, the compressors 5, 6 operate at different pressure ratios. The outlet pressure of the compressor 5, 6, which essentially corresponds to the condensation pressure is dependent on the condensation temperature and thus the external conditions of the refrigerant circuit and thus corresponds to the same value for all compressors 5, 6 or their circuit in compressor units. For this reason, all the compressors 5, 6 compress the refrigerant into a common pressure line 17.

A similar to the one in Fig. 1 described composite refrigeration system goes out of DE 10 2004 038 640 A1 out. In addition to several compressors grouped into units, the system has evaporators that can be operated in parallel and that provide cooling capacities at different temperature levels. The operation of the evaporator at different temperature levels and thus pressure levels is realized by means of cascade connection of different refrigerant circuits or by means of multi-stage compression processes.

The prior art further includes refrigeration systems with a system for heat recovery. It is not the complete, resulting from high pressure heat in the condenser transferred to the ambient air. Rather, an additional heat exchanger is arranged in the flow direction of the refrigerant upstream of the original condenser. Within the additional heat exchanger, the refrigerant, which emerges as hot gas from the compressor, cooled or re-heated. The resulting heat is transferred to the system of heat recovery and in this used for example for heating a medium within a heating system. Depending on the transferred heat, the refrigerant in the heat exchanger of the system of heat recovery can be completely de-icing and at least partially already liquefied. In the original condenser, the refrigerant is further de-oiled and / or liquefied, depending on the state of entry.

From the DE 298 10 584 U1 is a temperature-controlled control of a combined heat pump refrigeration system out. The principle of the system is based on the simultaneous generation or provision of cold at low pressure level and the output of useful heat to, for example, a heating system at high pressure level of a closed refrigerant circuit. The system consists of several heat exchangers, which are used as evaporators or condensers.

A method for using the liquefaction heat of a refrigeration system is also in the DE 36 09 313 C2 described. The liquefaction heat of the refrigerant circuit is discharged to heat recovery in a first heat exchanger to a liquid heat carrier. If there is no need for heating heat with simultaneous need for useful cooling, a second heat exchanger is acted upon by a coolant, for example air, and the condensing heat is transferred to the ambient air.

Depending on the season and / or time of day, different cooling capacities of the consumers are needed and transferred to the refrigerant within the evaporator. The available power of the system of heat recovery is thus dependent on the total heat absorbed in the evaporators and thus also subject to the variable cooling capacities of the consumers. In relation to Fig. 1 represent the evaporator 2, 3, the heat-absorbing components, which is discharged again at high pressure prevailing in the condenser 8 pressure.

Due to the variable cooling capacities of the consumers, certain operating conditions may occur in which the total amount of heat to be delivered at high pressure is insufficient to meet the heat demand of the heat recovery system. In this case, it is necessary, in addition to the refrigeration system, which also serves to generate heat, to install an additional heat generating unit, for example, a boiler to be fired. This additional installation disadvantageously adds additional investment and operational costs.

In the WO 01/20234 A1 a combined refrigerant heat pump cycle is disclosed with components for heat recovery, in which the liquefaction heat of the refrigerant circuit can be used to heat water of a heating circuit. If necessary, an evaporator of a heat pump circuit installed parallel to the evaporator of the refrigerant circuit also absorbs heat from the ambient air, which is transferred to the circuit of the heat recovery after the compression process of the refrigerant.

The object of the present invention is to provide a refrigeration system and a method for operating a refrigeration system, with which, on the one hand, the demand for refrigeration capacities at different temperature levels and, on the other hand, the need for heat output of a system of heat recovery are provided. The installation should be less expensive to install and operate than the systems known in the art.

The object is achieved by a refrigeration system with a closed refrigeration cycle having in the flow direction of the refrigerant at least one compressor unit, a heat exchanger, which serves for heat recovery, a luftbeaufschlagten capacitor, a collector, an expansion element and an evaporator. In the cycle the refrigeration system is also an evaporator integrated heat pump circuit integrated with an upstream expansion element, which is designed according to the concept luftbeaufschlagt. The evaporator of the heat pump circuit according to the invention with the condenser of the refrigeration system coupled thermally conductive. This double-acting heat exchanger is also referred to below as an integrated condenser-evaporator.

According to a preferred embodiment of the invention, the evaporator of the heat pump circuit is integrated in the refrigerant circuit, that it is connected in parallel to another evaporator.

The operation of the system depends, among other things, on the ambient temperature and thus on the services to be provided for heating and cooling. The evaporator of the heat pump circuit is to operate in the external conditions in which the total amount of heat to be discharged at high pressure is insufficient to meet the heat demand of the heat recovery system. The amount of heat to be dispensed at high pressure results from the entirety of the cooling capacities taken up in the conventional refrigerant circuit plus the quantities of heat introduced via the compression processes.
The heat generation units, such as boilers to be fired, which are required extra in conventional systems under the aforementioned operating conditions, are replaced according to the invention by only one heat exchanger additionally integrated in the refrigeration system. Since this heat exchanger is also connected in parallel to a conventional refrigeration unit associated evaporator and thus no additional need for other components, such as a compressor exists, the cost of the cost of expanding the refrigeration system is very low.

Conceptually, the integrated condenser-evaporator is designed as a tube bundle heat exchanger with fins. The lamellae advantageously comprise both the tubes of the evaporator of the heat pump circuit and the tubes of the condenser of the refrigeration system. By the additionally arranged tubes, on the one hand, the evaporator for the condenser and the other of the condenser for the evaporator and the associated fins, which also thermally contact the different tubes, the area for heat transfer is increased. The fins are thermally conductively coupled to the tubes of the evaporator and the condenser. The outside air or ambient air flows through the spaces between the slats on the outside of the tubes. The refrigerant flows in each case within the tubes in the case of the evaporator of the heat pump circuit under evaporation pressure and in the case of the condenser under condensation pressure of the refrigeration system. Due to the increased area advantageously lower temperature differences result in the process of heat transfer. The process of evaporation takes place at a higher vaporization temperature and higher vapor pressure than when using a single heat exchanger with a smaller area. The pressure ratio and thus the power supplied to the compressor are lower. The coefficient of performance of the system is advantageously larger. The system works more efficiently.

The integration of evaporator and condenser within one component of the system, in addition to the lower temperature differences and thus higher energy efficiency of the entire system resulting in further advantages. Since only one integrated condenser-evaporator is used instead of two heat exchangers, all belonging to each heat exchanger peripheral equipment, such as fans and installation elements, saved. This Savings are associated with significantly lower costs than when using two separate heat exchangers.
Both the evaporator of the heat pump circuit and the condenser of the refrigeration system are luftbeaufschlagte heat exchanger, both of which are each in contact with the outside air, wherein the evaporator absorbs heat from the ambient air and the condenser emits heat to the ambient air. When using the refrigeration system, for example in a supermarket, both heat exchangers would be placed independently on the outside of the building, for example on the roof or on one side of the exterior wall of the building. The conceptional merging of the heat exchangers in a single integrated condenser-evaporator can save additional space.
When operating the heat pump circuit and operating conditions with temperatures of the outside air around 0 ° C and thus evaporation temperatures below 0 ° C it comes to icing of the heat exchanger surface and an increasing deterioration of heat transfer. The surfaces must be defrosted at regular intervals. The larger the area and the higher the evaporation temperature, the slower is the process of icing. Since, according to the conception, both criteria are fulfilled by the invention, the icing of the heat transfer surface is delayed. In addition, the temperature level of the heat exchanger is in operation as a condenser of the refrigeration system at values above ambient temperature, so that the icy surfaces can be thawed without additional facilities, such as are necessary for hot gas defrosting or defrosting. For this purpose, the integrated heat exchanger is advantageous to switch to the mode as a capacitor. The heat dissipated during condensation serves to melt the ice and evaporate the water. By dispensing with additional devices for defrosting the heat exchanger surface further costs of material and installation costs can be saved. The operation of the system also causes less costs.

Depending on the need for cooling capacities within the group of evaporators at the respective temperature levels, the control of the compressor capacities is simplified in that a first group of evaporators are connected via suction lines to a first compressor unit and a second group of evaporators via suction lines to a second compressor unit. Compressor units are each one or more compressors to understand, which are connected in parallel with each other. The parallel connection advantageously allows the switching on and off of compressors to adapt the mass flows of the refrigerant and thus the cooling capacities to the needs of consumers. Damaged compressors can be changed during operation of the system.

In the method according to the invention for operating a refrigeration system, wherein a first compressor unit sucks the refrigerant from the first group of evaporators via suction lines and a second compressor unit sucks the refrigerant from the second group of evaporators via suction lines, the refrigerant is compressed into a common pressure line. The evaporator of the integrated heat pump circuit is operated parallel to an evaporator of the refrigeration system.

The evaporators of the first group and the evaporators of the second group advantageously have different temperature levels or pressure levels.
According to the concept, one group of evaporators provides the cooling capacity for the components of the standard cooling and the second group of evaporators the cooling capacity for the components of the indoor air climate, wherein the evaporator of the integrated heat pump circuit is connected in parallel to the group of compressors, the cooling capacity for the components of the indoor air provides.

The evaporators of the part of the refrigeration system used for normal cooling produce the cooling capacity at a temperature level between -5 ° C and -15 ° C. The evaporators, which provide the cooling capacity of the indoor climate, operate at a temperature level between 0 ° C and 10 ° C.

According to a preferred embodiment of the invention, the refrigerant is de-pressurized and / or liquefied after compression within a heat exchanger of the system of heat recovery. If vaporous refrigerant is present at the outlet of the heat exchanger, the vaporous component in the condenser of the refrigeration system is completely liquefied.

Depending on the heat demand of the system of heat recovery and the operating conditions of the evaporator for the normal cooling and the indoor climate, the evaporator of the integrated heat pump circuit can be switched.
According to an advantageous embodiment of the invention, the integrated condenser-evaporator is designed switchable as needed. Thus, the evaporator of the integrated heat pump circuit by switching to operation as a condenser of the refrigeration system is advantageous without additional expenditure of components and thus costs abtaubar.

The refrigeration system with additional evaporator of a heat pump circuit can also be designed as a cascade circuit. Also in this case, the evaporator of the heat pump circuit can be integrated within the condenser of the refrigeration system.

• weniger kostenintensiv und energetisch effektiver zu betreiben ist, da
  1. a) der Vorgang der Wärmeübertragung bei der Verdampfung des Kältemittels im Verdampfer der Wärmepumpenschaltung bei geringeren Temperaturdifferenzen und bei höherer Verdampfungstemperatur und höherem Verdampfungsdruck abläuft, was wiederum ein geringeres Druckverhältnis und damit eine geringere zuzuführende Leistung am Verdichter bewirkt,
  2. b) die Vereisung der Wärmeübertragerfläche im Verdampferbetrieb des integrierten Kondensator-Verdampfers verzögert wird sowie die vereisten Flächen ohne zusätzliche Einrichtungen und Energie abgetaut werden können,
• platzsparend und mit weniger Installationsaufwand verbunden ist, da auf eine große Anzahl zusätzlicher Komponenten verzichtet wird.

In summary, it is advantageous for the system with integrated condenser-evaporator over the systems known in the prior art to determine that the system

• less costly and energetically more effective to operate, since
  1. a) the process of heat transfer during the evaporation of the refrigerant in the evaporator of the heat pump circuit runs at lower temperature differences and at higher evaporation temperature and higher evaporation pressure, which in turn causes a lower pressure ratio and thus a lower power to be supplied to the compressor,
  2. b) the icing of the heat transfer surface in the evaporator operation of the integrated condenser-evaporator is delayed and the icy surfaces can be defrosted without additional facilities and energy,
• saves space and requires less installation effort, because it dispenses with a large number of additional components.

• Fig. 2: Fließbild der Kälteanlage mit integriertem Wärmepumpenkreislauf und
• Fig. 3: Fließbild der Kälteanlage mit integrierten Kondensator-Verdampfer.

Further details, features and advantages of the invention will become apparent from the following description with reference to the accompanying drawings. Show it:

• Fig. 2 Flow diagram of the refrigeration system with integrated heat pump cycle and
• Fig. 3 : Flow diagram of the refrigeration system with integrated condenser-evaporator.

In Fig. 2 the flow diagram of the refrigeration system 1 is shown with integrated heat pump circuit. When using the refrigeration system 1, for example as a supermarket refrigeration system with different consumers at different temperature levels, this has one or more compressors 5, 6, the compressor 5 of the normal refrigeration cycle and the compressor 6 of the air conditioning circuit and the heat pump circuit due to different inlet pressures are connected separately. The heat pump compressor works reversibly and, with appropriate design, can cover the entire climate requirement of the building. The compressor 5 of the normal cooling circuit are connected in parallel and form a compressor unit.

A non-illustrated development of the system is that a freezing circuit is connected to the composite.
The compressors 5, 6 compress the refrigerant due to a uniform condensation temperature or a uniform condensation pressure in a common pressure line 17, which connects the compressor unit or compressor 5, 6 with the heat exchanger of the heat recovery 7. The superheated present as hot gas refrigerant is cooled in the heat exchanger 7 of the heat recovery or deprived and condensed at large dissipating heat output of the heat recovery at least partially. Depending on the transferred heat, the refrigerant is thus partially or completely deprived and / or partially or completely liquefied. The heat transferred to the heat recovery system can be used, for example, to heat a medium within a heating system.
In the condenser 8, which is designed as luftbeaufschlagter heat exchanger, the refrigerant is completely condensed and then stored in the collector 9. If the refrigerant from the heat exchanger 7 of the heat recovery already completely liquefied, the liquid is passed through a bypass (not shown) to the condenser 8 directly into the collector 9.
The decom- missioning ends on reaching the dew line, where the process of condensation begins. At complete condensation or liquefaction, the refrigerant is at the outlet of each heat exchanger completely as a liquid. If the condensation takes place only partially, the refrigerant exits as a liquid-vapor mixture.
The liquid refrigerant is distributed via the liquid line 18, which connects the collector 9 with the consumers, on the different evaporators 2, 3, 4 and before entering the evaporator 2, 3, 4 by means of expansion valves 11, 13, 15 on the desired pressure level is relaxed. The process of evaporation to provide the cooling capacity of the normal cooling takes place at a different pressure level than the Process of evaporation for providing the cooling capacity for air conditioning and the heat absorption in the heat pump cycle. In the Fig. 2 Evaporators 2, 3, 4 shown as individual components can also be arranged as composites of a plurality of evaporators, which are each connected in series. The cooling capacity of the standard cooling system is provided at a temperature level between -5 ° C and -15 ° C and the cooling capacity for air conditioning at a temperature level between 0 ° C and 10 ° C. In the specific application, the evaporator 2 of the normal cooling at an evaporation temperature of -8 ° C and the evaporator 3, 4 for air conditioning and the integrated heat pump circuit operated at an evaporation temperature of +8 ° C. The individual evaporators 2, 3, 4 are connected via solenoid valves 10, 12, 14 switched on and off.
The vaporized, gaseous refrigerant passes back via suction lines 19, 20 to the compressors 5, 6. The cycle is closed.
The circuit may additionally be designed with internal heat exchangers as thermal connections between the liquid line 18 and the suction line 19, 20 (not shown). The inner heat exchangers are each in the flow direction on the high pressure side or within the liquid line 18 between the solenoid valve 10, 12, 14 and the expansion valve 11, 13, 15 and within the suction line 19, 20 between the evaporator 2, 3, 4 and the compressor 5, 6 arranged. The heat is transferred from the liquid refrigerant after the outlet of the collector 9 to the gaseous refrigerant before entering the compressor 5, 6. The refrigerant is on the one hand supercooled on the high pressure side and on the other hand overheated before entering the compressor 5, 6.

The cooling capacities of the evaporators 2, 3, 4 vary depending on the time of day and the season. Depending on the need for heat output within the system of heat recovery, this is the power consumed in the evaporators 2, 3, 4 plus the refrigerant during the Compressor operations supplied heat covered. If the required heat output and the sum of the supplied powers deviate from one another such that the heat output within the system of heat recovery can not be covered, the evaporator 4 of the circuit of the heat pump is switched on. The heat absorbed and heat supplied during the compression process are available as additional services to the heat recovery system. The evaporator 4 of the circuit of the heat pump is as well as the condenser 8 subjected to air.

The evaporators 2, 3 can be operated either as a direct evaporator. In this case, the evaporators 2, 3 are arranged directly in the refrigerator. However, it is also possible to use the evaporator with an additional brine. The cooling capacities are made available to the individual consumers by means of a brine circulation system. As brine cooling brines, such as ethylene glycol, or carbon dioxide are used as fluid.

Fig. 3 shows the flow diagram of the refrigeration system with integrated heat pump circuit and integrated condenser-evaporator 16 as a heat exchanger, the conceptually the condenser 8 of the refrigeration system 1 and the evaporator 4 of the integrated heat pump circuit with respect to in Fig. 2 connected circuit as an integral component connects.
The integrated condenser-evaporator 16 may be formed, for example, as a tube bundle heat exchanger with fins, the fins are advantageously thermally conductively connected both to the tubes of the evaporator 4 of the heat pump circuit and with the tubes of the condenser 8 of the refrigeration system. This increases the area of heat transfer during condensation and evaporation. The ambient air flows through the interstices of the fins and on the outside of the tubes. The refrigerant flows in each case within the tubes in Case of the evaporator 4 of the heat pump circuit under evaporation pressure and in the case of the condenser 8 under condensation pressure of the refrigeration system. 1
By interleaving the circuits of the integrated condenser-evaporator 16, also referred to as condenser with integrated evaporator coil, one another results in significant advantages in the operation of the refrigeration system. 1
Due to the dual use of the integrated condenser-evaporator 16, the operation is possible even at temperatures around 0 ° C, without the need for an additional system for defrosting the evaporator 4 of the heat pump. By switching off the evaporator 4 and connecting the capacitor 8, with optionally reduced heat output of the system of heat recovery, the defrosting is realized by the heat transfer of the refrigerant during the condensation.
The integration of the evaporator 4 of the heat pump circuit and the condenser 8 of the refrigeration system results in a large area for heat transfer, which in turn advantageously changes the process of heat transfer to lower temperature differences. As a result, the evaporation of the refrigerant in the circulation of the heat pump at a higher temperature and the condensation of the refrigerant at a lower temperature, which leads to a reduction in the supplied compressor power.
Furthermore, the space requirement is reduced by the integration of two heat exchangers in one component.

The present invention can be used anywhere where refrigeration systems are needed for cooling and at the same time there is a heat demand. Any conventional, even combustible, refrigerant can be used. In particular, halogenated fluorohydrocarbons HFCs and fluorinated hydrocarbons HFCs such as R134a are used.

Likewise, the use of natural refrigerants such as R717, R723, R744 and other refrigerants is possible.

LIST OF REFERENCE SIGNS

1

refrigeration plant

2

Evaporator (normal cooling)

3

Evaporator (climate cooling)

4

Evaporator (heat pump)

5

Compressor / compressor unit (normal cooling)

6

Compressor / compressor unit (air conditioning / heat pump)

7

Heat exchanger (heat recovery)

8th

capacitor

9

collector

10, 12, 14

solenoid valves

11, 13, 15

Expansion organ / expansion valve

16

integrated condenser-evaporator

17

pressure line

18

liquid line

19, 20

suction

Claims (15)

Refrigeration system (1) with a closed refrigeration cycle having in the flow direction of the refrigerant at least one compressor unit (5, 6), a heat exchanger (7), which serves for heat recovery, an air-charged capacitor (8), a collector (9), an expansion element (11 , 13) and an evaporator (2, 3), characterized in that in addition an evaporator (4) with upstream expansion element (15) in the circuit of a refrigeration system (1) integrated heat pump circuit is provided, wherein the evaporator (4) of the heat pump circuit is thermally conductively coupled to the capacitor (8), so that the evaporator (4) and the capacitor (8) as an integrated condenser-evaporator (16) are formed. Refrigeration system (1) according to claim 1, characterized in that the evaporator (4) of the heat pump circuit is subjected to air. Refrigeration system (1) according to one of claims 1 or 2, characterized in that the evaporator (4) of the heat pump circuit is connected in parallel to a further evaporator (2, 3). Refrigeration system (1) according to one of claims 1 to 3, characterized in that the integrated condenser-evaporator (16) is designed as a tube bundle heat exchanger. Refrigeration plant (1) according to one of claims 1 to 4, characterized in that the integrated condenser-evaporator (16) is designed as a plate heat exchanger, wherein the lamellae both the tubes of the evaporator (4) of the heat pump circuit and the tubes of the capacitor (8 ) of the refrigeration system. Refrigeration plant (1) according to one of claims 1 to 5, characterized in that a first group of evaporators (2, 3) via suction lines (19, 20) with a first compressor unit (5, 6) and a second group of evaporators (2 , 3) via suction lines (19, 20) with a second compressor unit (5, 6) are connected. Refrigeration system (1) according to one of claims 1 to 6, characterized in that the compressor units (5, 6) consist of a plurality of compressors (5, 6). Method for operating a refrigeration system (1) according to one of the preceding claims, wherein a first compressor unit (5, 6) sucks the refrigerant out of the first group of evaporators (2, 3) via suction lines (19, 20) and a second compressor unit (5 , 6) via suction lines (19, 20), the refrigerant from the second group of evaporators (2, 3) sucks and compresses the refrigerant in a common pressure line (17), characterized in that an evaporator (4) of an integrated heat pump circuit in parallel to an evaporator (2, 3) of the refrigeration system (1) is operated. Method for operating a refrigeration system (1) according to claim 8, characterized in that the evaporators (2, 3, 4) are operated at different temperature levels or pressure levels. Method for operating a refrigeration system (1) according to one of claims 8 or 9, characterized in that one group of evaporators (2) the cooling capacity for the components of the normal cooling and the second group of evaporators (3) the cooling capacity for the components of the indoor air provides. Method for operating a refrigeration system (1) according to one of claims 9 to 10, characterized in that the evaporator (4) of the integrated heat pump circuit is connected in parallel to the group of evaporators (3), which provides the cooling capacity for the components of the indoor air. Method for operating a refrigeration system (1) according to one of claims 9 to 11, characterized in that the evaporator (2) the cooling capacity of the normal cooling at a temperature level between -5 ° C and -15 ° C and the evaporator (3) the cooling capacity provide the indoor climate at a temperature level between 0 ° C and 10 ° C. Method for operating a refrigeration system (1) according to one of claims 9 to 12, characterized in that the refrigerant after compression within a heat exchanger (7) of the system of heat recovery is deprived and / or liquefied, wherein at the outlet of the heat exchanger (7) vapor refrigerant present in the condenser (8) is completely liquefied. Method for operating a refrigeration system (1) according to one of claims 9 to 13, characterized in that the evaporator (4) of the integrated heat pump circuit is switched on according to the heat demand of the system of heat recovery. Method for operating a refrigeration system (1) according to one of claims 9 to 14, characterized in that the evaporator (4) of the integrated heat pump circuit can be defrosted as required by switching to operation as a condenser (8) of the refrigeration system.

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