EP1921401A2 - Method for heat recovery - Google Patents

Abstract

The method involves arranging an evaporator in an inner space of a building and acts as cooling position and has an external heat exchanger (44) arranged outside the building. A part of the heat of the cooling agent carried in the pressure line (24,24') by an internal heat exchanger (26) is used for heating the inner space of the building. The internal heat exchanger is connected with the pressure line and arranged before the condenser (36) relative to the flow direction of the cooling agent. An independent claim is also included for a refrigerating plant with heat recovery.

Description

The invention relates to a method for heat recovery in a refrigeration system and a refrigeration system with heat recovery.

The extensive range of goods of modern supermarkets includes goods that need to be refrigerated throughout. For this purpose, refrigerated cabinets are provided which can be subdivided into refrigeration units for normal refrigeration for a temperature range of +2 to + 6 ° C and refrigerated cabinets for freezing for temperatures around -18 ° C. The refrigerated cabinets are often part of a refrigeration system. In such refrigeration systems, the individual refrigeration units or cooling points are supplied via a pipe network with refrigerant. The systems are designed as composite systems in which a pressure line and a condenser for the cooling points of both the normal cooling and the deep-freezing are provided.

Such refrigeration systems have a high energy consumption, which causes considerable costs. In addition, the cooling system itself represents a significant cost factor, since it must necessarily be designed so that even at high summer temperatures, the cooling of the goods is ensured at all times. For this purpose, several compressors for both normal cooling and deep freezing are often provided in order to be able to react flexibly to the variable power requirements of the refrigeration system.

To reduce the operating costs of a supermarket, modern refrigeration systems often have systems for heat recovery. These systems allow the use of waste heat from the refrigeration system to heat the interior of the supermarket.

However, known methods for heat recovery in a refrigeration system are still complex and expensive. In addition, they require compressor devices that have to cover a wide range of performance.

It is therefore an object of the invention to provide a method for improved heat recovery in a refrigeration system, which also allows efficient heating of an interior of a building. In addition, a corresponding refrigeration system to be created.

The object is achieved by a method having the features of claim 1 or a refrigeration system having the features of claim 11.

The inventive method for heat recovery in a refrigeration system uses a portion of the heat of the guided in a pressure line coolant for heating the interior of a building. The refrigeration system comprises a compressor device, a condenser connected thereto via the refrigerant pressure line and equipped with a ventilation device, at least one evaporator arranged in the interior of the building and serving as a cooling point, and an outside heat exchanger arranged outside the building. The provision of the heat takes place by means of an interior heat exchanger, which is connected to the pressure line and arranged with respect to the flow direction of the refrigerant in front of the condenser.

The inventive method is characterized in that depending on at least the outside temperature, a part of the guided in the pressure line refrigerant is passed through the outdoor heat exchanger to the compressor device and thereby absorbs heat from the ambient air of the outer space.

In other words, the ambient air of the outer space is extracted by a heat exchanger arranged outside the building heat and fed to the refrigerant. The ambient air is thus withdrawn under energy expense heat that is used to heat the building interior. The outdoor heat exchanger is connected in parallel to the cooling points of the refrigeration system and ultimately acts as another cooling point or heat pump, which introduces additional heat output into the refrigerant circuit. However, this heat is not taken from the building interior, as is the case with an indoor cooling point. The commissioning of the outdoor heat exchanger as a heat pump takes place at least as a function of the outside temperature, for example, when a predetermined outdoor temperature is reached.

In a suitably designed refrigeration system can even be completely dispensed with due to the method according to the invention for heat recovery by the additional heat input to a conventional heating system. This significantly reduces the investment costs. The variable use of the heat pump function can also reduce operating costs. The provision of an air heat exchanger outside the building also causes only low cost and is easy to do.

Further advantageous embodiments of the invention are specified in the subclaims, the description and the drawings.

It can be provided that the ventilation device of the capacitor is at least partially deactivated as a function of at least the interior temperature of the building. In other words, the ventilation device is completely or partially switched off or down depending on the heat request, thereby ultimately reducing the effective capacitor area and slightly increasing the temperature and pressure levels inside the condenser. As a result, the refrigerant condenses in the indoor heat exchanger at least partially, whereby an adjustable additional heat output can be dissipated in the building interior and therefore is no longer discharged on the capacitor as pure heat loss.

In one embodiment of the method according to the invention, the effective opening cross-section of a pressure regulating throttle arranged in the pressure line is changed as a function of at least the interior temperature in order to allow additional heat dissipation into the building interior. The pressure regulating throttle is arranged behind the interior heat exchanger with respect to the flow direction of the refrigerant, wherein it may be located in front of or behind the condenser. When reducing the opening area of the pressure regulating throttle, a back pressure is generated, whereby the condensation of the refrigerant in the indoor heat exchanger is assisted. Controlled throttling makes it possible to provide additional heat output for heating the building interior.

The part of the refrigerant that is guided as a function of at least the outside temperature by the outside heat exchanger can be supplied to at least one of a plurality of compressors of the compressor device. This compressor can be decoupled from the suction side of the other compressor of the compressor device. This compressor is then available for heat pump operation of the outdoor heat exchanger. The use of a compressor of the compressor device to provide additional heat output allows efficient utilization of the installed compressor capacity.

The compressor capacity is necessarily designed for high summer outdoor temperatures where high cooling capacities have to be provided. In winter, on the other hand, only part of the capacity is used. This power reserve is utilized by the method according to the invention for the building heating required in winter.

The control and regulation method according to the invention preferably takes place in several stages:

The ventilation device of the condenser can be partially deactivated when the outside temperature falls below a first outside temperature threshold. As a result, it is achieved that the refrigerant in the interior heat exchanger at least partially condenses. The resulting heat is dissipated to the interior of the building.

If an indoor temperature set point or a set flow temperature setpoint of a building heater is not reached and the outdoor temperature falls below a second outdoor temperature threshold that is lower than the first outdoor temperature threshold, may be in an optional further step, the effective opening area of the pressure regulating throttle to be changed.

In other words, by the pressure regulating throttle, the pressure in the indoor heat exchanger can be raised when additional heat needs to be provided for heating. This pressure increase leads to increased condensation of the coolant in the interior heat exchanger.

Should an internal temperature setpoint or a setpoint temperature setpoint of a heating water not be reached by the measure and the outside temperature below a third outside temperature threshold, which is lower than the first or the optional second outside temperature threshold, as an additional measure, a part of the guided in the pressure line refrigerant through the outdoor heat exchanger to be passed. For this purpose, the suction side of the at least one compressor of the compressor device is decoupled from the suction side of the other compressor and connected to the outdoor heat exchanger. The outdoor heat exchanger is then used as described above as an additional evaporator which extracts heat from the ambient air of the outdoor space.

The heat pump operation of the outdoor heat exchanger can also be done independently of the pressure control by the pressure control throttle.

It may additionally be provided that electrical heating means for heating the interior of the building or a buffer memory are switched on when the indoor temperature setpoint or the flow temperature setpoint is not reached and the outdoor temperature fourth outside temperature threshold, which is lower than the third outside temperature threshold.

According to a particularly advantageous embodiment of the method according to the invention, a hot gas defrosting of the outdoor heat exchanger is provided. For this purpose, the refrigerant pressure line is removed at a point in front of the condenser refrigerant and passed through the outdoor heat exchanger. After completion of the de-icing, the refrigerant contained in the outdoor heat exchanger is exhausted from the compressor device via a throttle line. The throttle line has a smaller cross-section than a refrigerant suction line connecting the outdoor heat exchanger with the suction line of the compressor device in the heat pump operation of the outdoor heat exchanger.

The branched hot gas is thus directed against the direction selected in the heat pump mode by the outdoor heat exchanger and ultimately fed to the refrigerant circuit on the pressure side again. Upon completion of the de-icing, refrigerant is at an unknown temperature level in the outdoor heat exchanger. In a transition to the heat pump operation could therefore be caused in the outer space heat exchanger associated compressor liquid hammer, whereby the compressor would be damaged. By the throttle line, however, the pressure level of the refrigerant is lowered and prevents further liquefaction of the refrigerant.

According to one embodiment of the method according to the invention, the sucked into the throttle line refrigerant is fed into a refrigerant suction line, which serves at least one serving as a cooling evaporator - In particular, an evaporator for deep freezing - connects to the compressor device. The extracted refrigerant is thus fed into a refrigerant flow, which comes from the cooling points, and mixed with this, so that at most a metered supply of liquid residues to the compressor takes place and the risk of liquid blows is virtually eliminated.

The invention further relates to a refrigeration system with heat recovery, which has a compressor device, a connected thereto via a refrigerant pressure line and equipped with a ventilation device condenser and at least one serving as a cooling evaporator, which is arranged in an interior of a building and a refrigerant suction line connected to the compressor device. The refrigerant pressure line is coupled to an indoor heat exchanger for dissipating heat to the interior. Serving as a cooling evaporator in the interior of the building arranged outside the building exterior heat exchanger is connected in parallel, is supplied by the heat from the ambient air to the guided in the suction refrigerant. Furthermore, the refrigeration system according to the invention has a control device which is designed to guide a portion of the refrigerant guided in the pressure line through the outer space heat exchanger as a function of at least the outside temperature.

According to one embodiment of the refrigeration system, a pressure regulating throttle is arranged in the pressure line, whose effective opening cross section is variably adjustable.

It may be provided that a refrigerant suction line of the outdoor heat exchanger through a throttle line with a refrigerant suction line is coupled, which connects at least one serving as a cooling evaporator - in particular an evaporator for deep freezing - with the compressor device.

The compressor device may comprise a plurality of compressors, wherein at least one compressor is selectively connectable to the refrigerant suction line of the at least one evaporator or to the refrigerant suction line of the outdoor heat exchanger.

Preferably, the control device is also designed such that, depending on at least the interior temperature, the ventilation device of the condenser is at least partially deactivatable and / or the effective opening cross section of the pressure control throttle is controllable.

Fig. 1

eine schematische Darstellung einer Ausführungsform der erfindungsgemäßen Kälteanlage;

Fig. 2

ein Flussdiagramm einer Ausführungsform des erfindungsgemäßen Verfahrens;

Fig. 3

ein Flussdiagramm des Wärmepumpenbetriebs des Außenraum-Wärmetauschers.

The invention will now be described by way of example only with reference to the drawings. Show it:

Fig. 1

a schematic representation of an embodiment of the refrigeration system according to the invention;

Fig. 2

a flowchart of an embodiment of the method according to the invention;

Fig. 3

a flow chart of the heat pump operation of the outdoor heat exchanger.

1 illustrates a refrigeration system 10 with an exemplary freezer 12 and an exemplary standard refrigeration unit 14, which are arranged in an interior of a building. Basically, any number be provided by normal and deep freezing points 14, 12. The refrigeration system 10 comprises a compressor device 16 which has five compressors 18a, 18a ', 18b, 18b' and 18c. The compressors 18a and 18a 'are connected to a deep-freeze suction line 20 and assigned to the deep-freezing point 12. The compressors 18b and 18b 'are connected by a normal cooling suction line 22 to the normal cooling point 14. The compressor 18c is also connected to the normal cooling suction line 22, but can be separated from it by the controllable solenoid valve MV1.

The refrigerant supplied via the suction lines 20, 22 of the compressor device 16 in a gaseous state is compressed by the compressors 18a, 18a ', 18b, 18b' and 18c and passed through the pressure line 24 to an indoor heat exchanger 26.

The indoor heat exchanger communicates via a buffer storage line 28 with a buffer memory 30 in connection. The buffer tank 30 contains water that can be used for heating the interior of the building in which the cooling points 12, 14 are installed. In the buffer memory 30, a heating cartridge 32 is arranged. However, it is also possible to provide a plurality of heating cartridges 32.

In the flow direction of the refrigerant behind the indoor heat exchanger 26, a pressure regulating throttle 34 is arranged in a second pressure line 24 '. The pressure regulating throttle 34 allows the regulation of the pressure level of the refrigerant in the pressure line 24 '.

The pressure line 24 'establishes a connection between the interior heat exchanger 26 and a condenser 36 with a ventilation device 38. The pressure and temperature level in the condenser 36 can be influenced by the ventilation device 38.

An increase in the pressure level - and thus the temperature level - leads to a partial condensation of the refrigerant in the interior heat exchanger 26. The heat emitted thereby can be discharged via the heating water of the buffer memory 30 to the interior. It is preferred that the regulation of the pressure level initially be effected by a partial deactivation of the ventilation device 38. If this measure is not sufficient, the pressure control throttle 34 can additionally be actuated.

In the flow direction of the coolant behind the condenser 36, a refrigerant collector 40 is provided. The refrigerant collector 40 is in turn connected by a refrigerant line 42 to the cooling points 12, 14.

The refrigerant line 42 has a connection to an outside of the building arranged outdoor heat exchanger 44, which can be interrupted by a valve V. The dashed rectangle around the exterior heat exchanger 44 makes it clear that this is not in the interior of the building in which the cooling points 12, 14 are installed. The outdoor heat exchanger 44 communicates with the compressor 18c via a heat exchanger suction line 46. The heat exchanger suction line 46 has a solenoid valve MV2, through which the connection between the outdoor heat exchanger 44 and the compressor 18c can be interrupted.

Between the heat exchanger suction line 46 and the normal cooling suction line 20 is a compound which is formed by a throttle line 48, wherein the cross section of the throttle line 48 is smaller than the cross section of the heat exchanger suction line 46. Further, there is between the heat exchanger suction line 46 and the pressure line 24 a hot gas connection 50. Solenoid valves MV3 and MV4 allow the throttle line 48 and the hot gas connection 50 to close.

The operation of the refrigeration system 10 will be explained in detail below.

For example, if no heating power is required to heat the interior of the building during midsummer, the compressors 18a and 18a 'and the compressors 18b, 18b' and 18c form two groups of compressors. Since the cooling points 12, 14 operate at different temperature levels, there are also different pressures in the suction lines 20, 22. This circumstance is taken into account by the formation of the separate compressor groups.

Below a certain outside temperature T _A , a heater pump, not shown, is turned on, so that heating water of the buffer memory 30 flows through the indoor heat exchanger 26. In this case, 26 heat of dissipation of the refrigerant is discharged to the heating water in the indoor heat exchanger.

In the event that the heating power must be increased, the ventilation device 38 is down-regulated or completely deactivated, whereby the effective capacitor area is reduced and the temperature level and the pressure level in the pressure line 24 'are slightly increased. As a result, the refrigerant in the indoor heat exchanger 26 at least partially condenses. The resulting heat benefits the heating of the building.

In a next optional step, the regulation of the condensation pressure by the pressure regulating throttle 34 takes place to an even greater Allow heat to the building interior. Although the compressors must work against this increased pressure, but this disadvantage can be taken into account, since an increased heating power is only necessary if a lower cooling capacity is needed. Thus, free compressor capacities are used to heat the building interior.

The next step in increasing the heat output is to extract heat in a heat pump operation from the ambient air in the exterior of the building and supply it to the refrigerant circuit. For this purpose, the solenoid valve MV 1 are closed and the solenoid valve MV2 and the valve V open. In this state, the refrigeration system ultimately comprises three evaporators, wherein the outdoor heat exchanger 44, in contrast to the cooling points 12, 14 takes heat from the outer space of the building and supplies the refrigerant circuit. The three different temperature and pressure levels of the suction lines 20, 22, 46 are each associated with their own compressor 18c or compressor groups 18a, 18a 'and 18b, 18b'. The compressor capacity not required at low outside temperatures T _A is thus used in this stage in a heat pump operation for heating the building. On a conventional building heating can therefore be dispensed with.

If the heating power provided by the heat pump operation is no longer required, the solenoid valve MV2 and the valve V are closed and the solenoid valve MV1 is opened. The compressor 18c then works again in conjunction with the compressors 18b and 18b '.

The outdoor heat exchanger 44 may be de-iced by hot gas as needed or at fixed intervals, particularly prior to its use in heat pump operation. For this purpose, the solenoid valves MV1 and MV2 closed and the compressor 18c thus dissolved out of the normal cooling point 14 associated compressor group. In addition, the solenoid valve MV4 in the hot gas connection 50 and the valve V are opened, whereby now hot gas from the pressure line 24 is directed against the flow direction in heat pump operation by the outdoor heat exchanger 44 until an end of the defrosting process is reached. Preferably, the valve V is formed by an electrically controllable solenoid valve and a check valve connected in parallel in a bypass line, wherein the check valve opens against the flow direction in the heat pump mode, ie, the check valve opens passively.

Upon completion of defrost, solenoid valve MV4 and valve V are closed, and solenoid valve MV3 in choke line 48 is opened, thereby establishing communication with vacuum refrigeration line 20. As a result, the refrigerant used for deicing is sucked off and the pressure in the outdoor heat exchanger 44 is lowered to a desired value. During the suction process, the fans of the outdoor heat exchanger 44 run. When the desired pressure is reached, the suction is stopped and the solenoid valve MV3 is closed. For a heat pump operation, the solenoid valve MV2 and the valve V are then opened. The compressor 18c starts its work and compresses the refrigerant coming from the outdoor heat exchanger.

In the following, a concrete embodiment of the method according to the invention is explained with reference to FIG. 2, wherein only the successive activation of the individual stages is illustrated. Deactivation is done in the reverse order. The mentioned temperature thresholds and / or setpoint values can be adapted to the respective circumstances and requirements.

After the start of the control in step 100, a query is made in step 110 as to whether the outside temperature T _{A is} lower than 18 ° C. If this is not the case (N), the system returns to step 100.

At temperatures below 18 ° C (J), a heating pump is turned on in step 120. The indoor heat exchanger 26 now outputs heat of enhancement to the heating water. A target condensation temperature T _K is automatically raised from 28 ° C (summer operation) to 32 ° C (transitional period) in step 125. As a result, the operation of the ventilation device 38 of the capacitor 36 is influenced.

Which flow temperature Tv of the heating water is achieved by these measures, at this time has no influence on the control of the refrigeration system. If the internal heat loads in the interior of the building are so high that heating at the prevailing outside temperature T _{A is} not required, the setpoint condensation temperature T _{K can} be lowered.

In step 130 it is queried whether the outside temperature T _A falls below a second threshold value of 15 ° C. If the outside temperature T _{A is} higher, it is returned to step 110, that is, it is again checked whether the outside temperature T _{A is} less than 18 ° C. If appropriate, the heating pump remains switched on (step 120), and the target condensation temperature T _K remains at the raised value (32 ° C., step 125). On the other hand, if it is determined in step 130 that the outside temperature T _{A is} lower than 15 ° C, the target condensing temperature T _{K is raised} to 38 ° C. A control device the cooling system 10 attempts in step 135 by raising the nominal condensation temperature T _K to reach a flow temperature Tv of 35 ° C. If an interior temperature T _I at 22 ° C, the desired flow temperature Tv is slid by up to 3 K slidably.

In step 140, it is checked whether the outside temperature T _{A is} smaller than 10 ° C, returning to step 130, if not, that is, the state of step 135 is maintained if necessary. If the outside temperature T _{A is} below, the control device tries in step 145, depending on the interior temperature T _I and the outside temperature T _A, the required flow temperature Tv of 35 ° C to 45 ° C by controlling the pressure control throttle 34 and by raising the target condensation temperature T _K to reach.

At outside temperatures of below 0 ° C (step 150) and failure to reach the desired flow temperature Tv or interior temperature T _I (step 155), a compressor 18c is cold-separated from the compressor unit associated with the normal refrigeration units 14 of the refrigeration system 10. This compressor then operates in step 160 in heat pump operation in conjunction with the outdoor heat exchanger 44. For this purpose, the solenoid valve MV 1 are closed and the solenoid valve MV2 and the valve V open. The heat pump operation and the hot gas defrost of the outdoor heat exchanger 44 will be explained below with reference to FIG.

For an optional hot gas defrost, the solenoid valves MV1 and MV2 are closed in step 200, and the solenoid valve MV4 and the valve V are opened. Heated refrigerant can now be passed through the outdoor heat exchanger 44 until a defrost end temperature Tw of about + 8 ° C is reached, which is queried in step 210.

After reaching the defrost end temperature Tw, the solenoid valves MV4 and V are closed and the solenoid valve MV3 is opened in step 220, which leads to a suction of the refrigerant contained in the outdoor heat exchanger 44. Suction is continued until a pressure threshold P of about 1.8 bar in the heat exchanger suction line 46 coming from the outdoor heat exchanger 44 is reached (step 225). As already explained above, when the pressure threshold value is reached, the suction process is ended in step 230, i. H. the solenoid valve MV3 is closed, the solenoid valves MV2 and V are opened, and the compressor 18c connectable to the outdoor heat exchanger 44 is released. This completes the hot gas defrost.

As long as the desired flow temperature Tv of the heating water and / or the interior temperature T _{I of} the building are not reached, the heat pump operation is continued, as indicated in step 240. Otherwise, in step 250, the compressor 18c is briefly turned off while the solenoid valve MV2 closed and the solenoid valve MV1 are opened, whereby the compressor 18c is again associated with the normal cooling point 14.

Referring again to Fig. 2, it is checked in step 170 whether the outside temperature T _A is lower than -10 ° C. If the outside temperature T _A falls below this value and the desired flow temperature Tv or the interior temperature T _{I is} not reached (step 180), the heat pump operation is continued in step 185, ie the state according to step 230 of FIG. 3 is maintained, and time-delayed in step 190, a heating cartridge 32 is switched on to heat the heating water. It can be provided that several heating cartridges can be switched on as needed.

The connection of the outdoor heat exchanger 44 can also be done without the prior regulation of the condensation temperature by the ventilation device 38 and / or the dynamic pressure control by means of the pressure control throttle 34.

LIST OF REFERENCE NUMBERS

10

refrigeration plant

12

Frozen site

14

Normal cooling point

16

compressor means

18a, 18a ', 18b, 18b', 18c

compressor

20

Frozen suction line

22

Normal cooling suction line

24.24 '

pressure line

26

Indoor heat exchanger

28

Buffer line

30

buffer memory

32

Cartridge Heater

34

Pressure control throttle

36

capacitor

38

ventilation device

40

Refrigerant collector

42

Refrigerant line

44

Outdoor heat exchanger

46

Suction line heat exchanger

48

choke line

50

Hot gas connection

MV1, MV2, MV3, MV4

magnetic valve

T _A

outside temperature

tv

flow temperature

T _K

Target condensation temperature

T _I

Interior temperature

T _w

defrost termination

P

pressure threshold

V

Valve

Claims (16)

Method for heat recovery in a refrigeration system, comprising a compressor device (16), a hereby connected via a refrigerant pressure line (24, 24 ') and connected to a ventilation device (38) equipped condenser (36), at least one arranged in an interior of a building and comprising evaporator (12, 14) serving as a cooling point and an outside heat exchanger (44) arranged outside the building,
wherein, by means of an interior heat exchanger (26), which is connected to the pressure line (24, 24 ') and with respect to the flow direction of the refrigerant in front of the condenser (36), a portion of the heat in the pressure line (24, 24') guided refrigerant is used to heat the interior of the building, and
wherein, depending on at least the outside temperature (T _A ), a part of the refrigerant in the pressure line (24, 24 ') guided by the outdoor heat exchanger (44) to the compressor device (16) and thereby absorbs heat from the ambient air of the outer space , Method according to claim 1,
characterized in that
as a function of at least the interior temperature (T _I ), the ventilation device (38) of the condenser (36) is at least partially deactivated. Method according to claim 1 or 2,
characterized in that
the effective opening cross section of a pressure regulating throttle (34) arranged in the pressure line (24, 24 ') is changed as a function of at least the interior temperature (T _I ), the pressure regulating throttle (34) being located behind the interior heat exchanger (26) with respect to the flow direction of the refrigerant. is arranged. Method according to at least one of the preceding claims,
characterized in that
the part of the refrigerant supplied as a function of at least the outside temperature (T _A ) through the exterior heat exchanger (44) is fed to at least one of a plurality of compressors (18a, 18a ', 18b, 18b', 18c) of the compressor device (16) this compressor (18c) from the suction side of the other compressor (18a, 18a ', 18b, 18b') of the compressor device (16) is decoupled. Method according to at least one of the preceding claims,
characterized in that
the ventilation device (38) of the condenser (36) is partially deactivated when the outside temperature (T _A ) falls below a first outside temperature threshold for the refrigerant in the interior heat exchanger (26) to at least partially condense, thereby dissipating heat from the refrigerant the interior of the building is dissipated. Method according to claims 3 and 5,
characterized in that
the effective opening area of the pressure regulating throttle (34) is changed when an indoor temperature set point or a set flow temperature target value of a building heater is not reached and the outdoor temperature (T _A ) falls below a second outdoor temperature threshold lower than the first outdoor temperature threshold, whereby the condensation of the refrigerant in the indoor space Heat exchanger (26) is supported. Method according to claim 4 and claim 5 or 6,
characterized in that
the suction side of the at least one compressor (18c) is decoupled from the suction side of the other compressors and connected to the outdoor heat exchanger (44) when an indoor temperature setpoint or flow temperature set point is not reached and the outdoor temperature (T _A ) falls below a third outdoor temperature threshold is lower than the first or the second outside temperature threshold, and that a portion of the refrigerant in the pressure line (24, 24 ') is passed through the outdoor heat exchanger (44) to thereby absorb heat from the ambient air of the outdoor space. Method according to claim 7,
characterized in that
electric heating means (32) for heating the interior of the building or a buffer memory (30) are switched on when the indoor temperature setpoint or the flow temperature setpoint is not reached and the outdoor temperature (T _A ) a fourth Outside temperature threshold is lower than the third outside temperature threshold. Method according to at least one of the preceding claims,
characterized in that
for hot gas defrosting of the outdoor heat exchanger (44) of the refrigerant pressure line (24, 24 ') at a location upstream of the condenser (36), refrigerant is withdrawn and passed through the outdoor heat exchanger (44), in the outdoor space Heat exchanger (44) is exhausted after completion of the defrosting of the compressor device (16) via a throttle line (48) having a smaller cross-section than a refrigerant suction line (46) in the heat pump operation of the outdoor heat exchanger (44) the outdoor heat exchanger (44) connects to the compressor device (16). Method according to claim 9,
characterized in that
the refrigerant drawn off via the throttling line (48) is fed into a refrigerant suction line (20, 22) which has at least one evaporator (12, 14) serving as a cooling point - in particular an evaporator (12) for deep-freezing - with the compressor device (16 ) connects. Refrigeration plant with heat recovery, a compressor device (16), a hereby via a refrigerant pressure line (24, 24 ') connected and equipped with a ventilation device (38) condenser (36) and at least one serving as a cooling point evaporator (12, 14) standing in an interior of a Building is arranged and via a refrigerant suction line (20, 22) is connected to the compressor device,
wherein with the refrigerant pressure line (24, 24 '), an indoor heat exchanger (26) is coupled to dissipate heat to the interior, and
wherein the interior serving as a cooling point evaporator (12, 14) arranged outside the building exterior heat exchanger (44) is connected in parallel by the heat from the ambient air of the outer space to the in the suction line (20, 22) guided refrigerant can be fed and
wherein the refrigeration system has a control device which is designed to guide a portion of the refrigerant in the pressure line (24, 24 ') through the outdoor heat exchanger (44) as a function of at least the outside temperature (T _A ). Refrigeration system according to claim 11,
characterized in that
in the pressure line (24, 24 ') a pressure regulating throttle (34) is arranged, whose effective opening cross-section is variably adjustable. Refrigeration system according to claim 11 or 12,
characterized in that
a refrigerant suction line (46) of the outer space heat exchanger (44) is coupled by a throttle line (48) to a refrigerant suction line (20, 22) which comprises at least one evaporator (12, 14) serving as a cooling point - in particular an evaporator ( 12) for freezing - connects to the compressor device. Refrigeration system according to claim 13,
characterized in that
the cross section of the throttle line (48) is smaller than the cross section of the refrigerant suction line (46) of the outdoor heat exchanger (44). Refrigeration system according to at least one of claims 11 to 13,
characterized in that
the compressor device (16) comprises a plurality of compressors (18a, 18a ', 18b, 18b', 18c), wherein at least one compressor (18c) optionally with the refrigerant suction line (20, 22) of the at least one evaporator (12, 14) or with the refrigerant suction line (46) of the outdoor heat exchanger (44) is connectable. Refrigeration system according to at least one of claims 11 to 15,
characterized in that
the control device is designed to at least partially deactivate the ventilation device (38) of the condenser (36) as a function of at least the interior temperature (T _I ) and / or to control the effective opening cross section of the pressure control throttle (34).

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