CN113767021B

CN113767021B - Method for operating a vehicle refrigeration system combining refrigeration system operation and heat pump operation

Info

Publication number: CN113767021B
Application number: CN202080030233.XA
Authority: CN
Inventors: D·施罗德; C·雷宾格尔; H·罗腾科尔布
Original assignee: Audi AG
Current assignee: Audi AG
Priority date: 2019-04-25
Filing date: 2020-03-31
Publication date: 2024-05-03
Anticipated expiration: 2040-03-31
Also published as: DE102019205901B4; CN113767021A; DE102019205901A1; WO2020216586A1

Abstract

The invention relates to a method for operating a refrigeration system (1) for a vehicle, comprising a refrigeration circuit (2) which can be used for both refrigeration system operation and heat pump operation and which has at least one branching section (VZ 1, VZ2, VZ 3) for introducing a refrigerant into a first guide branch for executing a first operating mode or into a second guide branch for executing a second operating mode, wherein, in order to switch the refrigeration circuit (2) between the first and the second operating modes, a first valve means for a first refrigerant flow into the first guiding section and a second valve means for a second refrigerant flow into the second guiding section are provided, wherein the first valve means and the second valve means are designed with a variably controllable cross section, and in order to switch from the first operating mode into the second operating mode, the second valve means are first opened to a predetermined target cross section and, in response to reaching the predetermined target cross section of the second valve means, the first valve means are closed by reducing the cross section.

Description

Method for operating a vehicle refrigeration system combining refrigeration system operation and heat pump operation

Technical Field

The invention relates to a method for operating a refrigeration system for a vehicle, having a refrigerant circuit which can be used for both refrigeration system operation and heat pump operation.

Background

Vehicle air conditioning systems with heat pump function are known, which have a high complexity at the same time, due to the wide variety of alternative connection schemes. Thus, different modes of operation, such as refrigeration plant operation by one or more evaporators, different reheat operation, air heat pump operation, water heat pump operation, and delta operation as another heat pump operation (where the refrigerant compressor is the sole heat source), have certain basic actions. In addition, there are also mixed and combined operations, for example consisting of an air heat pump operation and a water heat pump operation, and at least one deicing function.

The switching of the circuit between the different operating modes is achieved by actuating individual shut-off valves, switching valves, multi-way valves and/or expansion valves which can be controlled electrically and have a variably adjustable cross section. The valves are movable between closed and open states, but may also stay in an intermediate position.

In such a loop change, there is a risk that the heating and/or cooling power must be temporarily interrupted or the plant operation must be interrupted and thus the system needs to be restarted in a new configuration. Thereby, the loss of comfort for the vehicle occupants is not precluded.

In such a circuit change, it is necessary to shut down the refrigerant compressor of the refrigerant circuit when interrupting the operation of the device to prevent possible "lock-up" of the system. This may also result in a temporary interruption of heating and/or cooling power, while causing a loss of comfort for the vehicle occupants.

The DE10 2016 005 782a1 describes a method which has been used for operating a vehicle air-conditioning system having a refrigerant circuit, in which the heat flow is regulated by adapting the valve cross section at a minimum compressor speed. By adjusting the cross section at the expansion mechanism, the refrigerant compressor of the refrigerant circuit is not operated in a 2-point adjustment operation, but is continuously operated.

An air conditioning system for a vehicle is known from DE 11 2014 006 077 T5, which can be operated in a heat pump mode. Known air conditioning systems comprise a plurality of valves which can be electrically regulated independently of one another and a refrigerant compressor, the rotational speed of which is limited to a maximum value.

Finally, DE 10 2016 001 096 A1 describes a method for operating a vehicle refrigeration system, in which the target air temperature is set by means of a compressor speed regulation of the refrigerant compressor and a variable expansion mechanism section.

Disclosure of Invention

The object of the present invention is to provide a method for operating a refrigeration system for a vehicle, which refrigeration system has a refrigerant circuit which can be used for both refrigeration system operation and heat pump operation, with which the refrigeration system can be switched between different operating modes without the disadvantages described above occurring, or at least only to a limited extent.

This object is achieved by the method according to the invention.

According to the invention, a method for operating a refrigeration system for a vehicle is proposed, which refrigeration system has a refrigerant circuit which can be used for both refrigeration system operation and heat pump operation, which refrigerant circuit has at least one branching section for directing refrigerant either into a first guide branch for executing a first operating mode; or into a second guide branch for executing a second operating mode, wherein,

In order to switch the refrigerant circuit between the first operating mode and the second operating mode, a first valve means for realizing a first refrigerant flow into the first guide section and a second valve means for realizing a second refrigerant flow into the second guide section are provided, wherein the first valve means and the second valve means are configured with a variably controllable cross section, and

In order to switch from the first operating mode to the second operating mode, the second valve means is first opened to a preset target cross-section, and the first valve means is closed by reducing the cross-section as the preset target cross-section of the second valve means is reached.

In this switching strategy between the first and second modes of operation, the second valve mechanism that would otherwise cause the blockage has been opened to a preset target cross-section prior to closing the first valve mechanism for controlling the flow of refrigerant for the first mode of operation. When the target cross section is reached, the first valve mechanism is moved in the fully closed direction.

For this purpose, the valve means can be adjusted electrically steplessly, that is to say the valve means can be controlled variably for the flow cross section of the refrigerant, wherein an arbitrary intermediate position between 0% of the cross section opening and 100% of the cross section opening can be adjusted and maintained. The valve is thus embodied as lockable, so that an automatic closing or abrupt adjustment is prevented.

By means of this switching strategy, the risk of "locking" of the refrigeration equipment is avoided, but at least reduced. Substantially no interruption of the heating and/or cooling power occurs, so that the loss of comfort for the vehicle occupants is precluded, but at least kept low.

According to an advantageous development of the invention,

By means of a third valve mechanism, a flow through the second refrigerant flow through the second guide branch can be caused, and

-Closing the first valve means and opening the third valve means in synchronization with the first valve means cross section.

This third valve mechanism prevents that refrigerant can flow into the second guide branch during the first operating mode.

The first and third valve means are functionally connected in such a way that they are moved in opposite directions synchronously, so that, for example, between the closed first valve means and the open third valve means, the cross-sectional area through which free flow can pass is always equal to the initial maximum cross-sectional area. This can be done simultaneously or time-staggered with respect to each other.

According to a further preferred embodiment of the invention, the flow of refrigerant through the first guide branch is prevented by means of a fourth valve mechanism. The first and fourth valve mechanisms are closed in section synchronization with each other during switching from the first mode of operation to the second mode of operation. This can be done simultaneously or time-staggered with respect to each other.

By means of such a fourth valve mechanism, it is prevented that during the second operating mode refrigerant can flow into the first guide branch.

The first and fourth valve means are functionally associated in such a way that they move synchronously in the same direction, i.e. the sections close synchronously. This can be done simultaneously or time-staggered with respect to each other.

Further advantageous embodiments of the method according to the invention relate to switching between the refrigeration system operation and the heat pump operation, and between the air heat pump operation and the water heat pump operation. In addition, it relates to switching between the first and second reheating operations and switching between the refrigeration appliance operation and the first reheating operation.

According to a final preferred development of the invention, it is particularly advantageous if the refrigerant compressor of the refrigerant circuit is set to a predetermined rotational speed value during the switching between the two operating modes. Thus, during the valve switching period that causes the switching from the first operation mode to the second operation mode, no increase in rotational speed should be made on the refrigerant compressor. For this purpose, the actuating signal for the electric refrigerant compressor is "fixed" at a predetermined rotational speed value. For safety reasons, the rotational speed is of course also allowed to drop.

The predefined rotational speed value corresponds to either the rotational speed value before switching from the first operating mode to the second operating mode or the rotational speed value calculated from the characteristic map or according to a suitable formula.

Drawings

Further advantages, features and details of the invention emerge from the following description of a preferred embodiment and from the sole figure 1. Fig. 1 shows a circuit diagram of a refrigeration appliance for a vehicle with a refrigerant circuit that can be used for both refrigeration appliance operation and heat pump operation.

Detailed Description

The refrigeration system 1 according to fig. 1 can be operated both in the refrigeration system operation (AC operation for short) and in the heat pump operation (WP operation for short), wherein a heating operation is performed by means of the heat pump function and for this purpose a heat exchanger 4 in the form of an air-refrigerant heat exchanger is arranged in the heating branch 2.2 as a heating regulator. The heat exchanger 4 is installed together with the evaporator 3 in the air conditioning system 1.1, wherein for regulating the cabin feed air flow L that is guided into the vehicle interior, the cabin feed air flow is first guided through the evaporator 3 and then through the heat exchanger 4 and, if necessary, through the electrical heating element 7. The heating element 7 is embodied, for example, as a high-voltage PTC heating element. In addition to the air conditioning system 1.1, the refrigeration system 1 has a water chiller 9, which is thermally connected to the cooling medium circuit 9.0 for cooling, for example, a high-voltage battery.

The refrigerant circuit 2 includes:

An air conditioning system 1.1 having an evaporator 3 (for example a front evaporator) and a heat exchanger 4 (also referred to as a heating regulator), wherein the evaporator 3 is arranged in the evaporator branch 3.1 and the heat exchanger 4 is arranged in the heating regulator branch 4.1,

A refrigerant compressor 5 which is arranged to compress the refrigerant,

An external air-refrigerant heat exchanger 6 embodied as a condenser or gas cooler, which has a heat pump expansion mechanism AE3, which is associated with the external air-refrigerant heat exchanger in its function as a heat pump evaporator for heating operation;

an internal heat exchanger 11,

An accumulator 10 on the low pressure side,

An evaporator expansion mechanism AE2 arranged in the evaporator branch 3.1 and connected upstream to the evaporator 3,

A non-return valve R1 connected downstream of the evaporator branch 3.1, which is in fluid communication with the inlet side of the refrigerant compressor 5 via the accumulator 10 and a low-pressure-side section of the internal heat exchanger 11,

A chiller branch 9.1 having a chiller 9 and a chiller expansion mechanism AE1 connected upstream of the chiller, wherein, in addition to cooling an electrical component, for example a vehicle, the chiller 9 is also used to perform a water heat pump function using the waste heat of at least one electrical component,

An AC and heat pump branch 2.1 with an external air refrigerant heat exchanger 6 and a heat pump expansion mechanism AE3, wherein, in air heat pump operation, the AC and heat pump branch 2.1 can be in fluid communication upstream with the evaporator branch 3.1 via the heat pump expansion mechanism AE3 in the formation of a branching point Ab1 and downstream with the low-pressure input of the refrigerant compressor 5 via a shut-off mechanism A2, and in AC operation, the AC and heat pump branch 2.1 can be in fluid communication upstream with the high-pressure output of the refrigerant compressor 5 via A4,

A heating branch 2.2 having a heat exchanger 4, wherein the heating branch 2.2 can be in fluid communication upstream with the high-pressure output of the refrigerant compressor 5 via a shut-off means A3 and downstream with a branching point Ab1 via a shut-off means A1 and further with an evaporator branch 3.1 and a chiller branch 9.1,

A reheat branch 2.3 having a reheat expansion mechanism AE4 configured as an expansion valve, wherein the reheat branch 2.3 is fluidly communicable downstream with an external air refrigerant heat exchanger 6 in the case of forming a branching point Ab2, and upstream with the heat exchanger 4,

A heat pump recirculation branch 2.4 with a shut-off means A2 and a check valve R2, wherein the heat pump recirculation branch 2.4 is upstream fluidically connectable to an external air-refrigerant heat exchanger 6 via a branching point Ab2 and downstream fluidically connectable to an accumulator 10, and

A suction branch 2.5 with a shut-off valve A5, wherein the suction branch 2.5 can be in fluid communication downstream with the shut-off valve A2 and the check valve R2 of the heat pump recirculation branch 2.4 via a branching point Ab 3.

For controlling and regulating the system, as sensors, a plurality of pressure temperature sensors are provided in the refrigerant circuit 2.

Therefore, the refrigerant compressor 5 is assigned a first pressure temperature sensor pT1 at a high-pressure output, in addition, a second pressure temperature sensor pT2 is arranged at an output of the accumulator 10, a third pressure temperature sensor pT3 is arranged at an output of the external air-refrigerant heat exchanger 6, a fourth pressure temperature sensor pT4 is arranged at an output of the heat exchanger 4, and a fifth pressure temperature sensor pT5 is arranged at an output of the low-pressure side of the water chiller 8. Since the corresponding functions of these pressure temperature sensors are known to the person skilled in the art, they are not explained in detail.

The AC operation and the heating operation of the refrigeration apparatus 1 are explained next.

With the shut-off mechanisms A3 and A4 arranged in the first branching section VZ1, depending on the state of these two shut-off mechanisms A3 and A4, from the high-pressure side of the refrigerant compressor 5, the refrigerant flow is either guided into the AC and heat pump branch 2.1 for performing AC operation when the shut-off mechanism A4 is opened and the shut-off mechanism A3 is blocked, or flows into the heating branch 2.2 to perform heating operation by means of the heat pump function when the shut-off mechanism A3 is opened and the shut-off mechanism A4 is closed.

In AC operation of the refrigerant circuit 1, from the refrigerant compressor 5, the refrigerant compressed to a high pressure flows into the external air-refrigerant heat exchanger 6 when the shutoff mechanism A4 is opened, into the high-pressure section of the internal heat exchanger 11, into the evaporator 3 by means of the evaporator expansion mechanism AE2 and/or into the water chiller 9 by means of the water chiller expansion mechanism AE1 by means of the fully opened heat pump expansion mechanism AE 3. The refrigerant flows back from the chiller branch 9.1 through the accumulator 10 and the low-pressure section of the internal heat exchanger 11 to the refrigerant compressor 5, while the refrigerant flows out of the evaporator branch 3.1 through the check valve R1 and then flows back to the refrigerant compressor 5 through the accumulator 10 and the low-pressure section of the internal heat exchanger 11 as well.

In AC operation, the heating branch 2.2 is blocked by means of the shut-off means A3. In order to withdraw refrigerant from the deactivated/deactivated heating branch 2.2, the shut-off means A5 is opened and the refrigerant can flow through the shut-off means A5 and the check valve R2 in the direction of the accumulator 10 while closing the shut-off means A2.

The heating operation of the refrigerant circuit 2 of the refrigeration apparatus 1 is described next. For this purpose, a heat pump operation is carried out by means of at least one heat source. In the heat pump operation of the refrigerant circuit 2, the cabin feed air flow L supplied to the vehicle interior is heated by means of the heat exchanger 4 before the cabin feed air flow L can flow into the vehicle interior, and if necessary is guided through the heating element.

In the case of using the water chiller 9 for realizing a water heat pump or in the case of using the air refrigerant heat exchanger 6 as the outside of the heat pump evaporator for realizing an air heat pump, in the heating operation of the refrigerant circuit 2, the shut-off mechanism A4 of the first branching section VZ1 is closed and the shut-off mechanism A3 of the first branching section VZ1 is opened, so that hot refrigerant, for example R744, can flow into the heating branch 2.2.

In order to perform a water heat pump operation by means of the water chiller 9, the refrigerant compressed by means of the refrigerant compressor 5 flows into the heat exchanger 4 via the heating branch 2.2 for outputting heat to the cabin feed air flow L and is then expanded into the water chiller 9 by means of the water chiller expansion mechanism AE1 by means of the opened shut-off mechanism A1 for absorbing waste heat of the electrical and/or electronic components arranged in the cooling medium circuit 9.0. In this heating function, the expansion mechanisms AE3 and AE4 and the shutoff mechanism AE5 are closed. By opening the shut-off means A2, the refrigerant discharged during the water heat pump operation is drawn from the AC and heat pump branch 2.1 and fed to the refrigerant compressor 5 via the non-return valve R2.

In addition to direct condensation or gas cooling as described herein, the heat exchanger 4 may also be implemented as a refrigerant heat rejection fluid heat exchanger that indirectly heats an air stream, wherein the heat rejection fluid may be, for example, a water glycol mixture.

In order to perform an air heat pump operation by means of the external air refrigerant heat exchanger 6 as a heat pump evaporator, the refrigerant flows from the heat exchanger 4 into the AC and heat pump branch 2.1 via the opened shut-off means A1 and is expanded by means of the heat pump expansion means AE3 into the external air refrigerant heat exchanger 6 for absorbing heat from the ambient air and then flows back to the refrigerant compressor 5 via the heat pump recirculation branch 2.4. At this time, the expansion mechanisms AE1, AE2, and AE4 and also the shutoff mechanism A5 remain closed.

If a combined operation of the water heat pump and the air heat pump is achieved, in addition to the chiller expansion mechanism AE1, the heat pump expansion mechanism AE3 is also actively connected by the controller, and both the chiller expansion mechanism and the heat pump expansion mechanism are controlled accordingly to adjust and achieve the target parameters.

In the reheating operation, the cabin feed air flow L fed into the vehicle interior is first cooled by means of the evaporator 3 and then dehumidified for subsequent reheating of the cabin feed air flow L by means of the heat exchanger 4 using the heat extracted from the cabin feed air flow L and the heat fed to the refrigerant by means of the refrigerant compressor 5.

The reheating operation of the refrigerant circuit 1 is performed in different manners according to the heat balance.

When the heat in the reheating operation (hereinafter referred to as a first reheating operation) is excessive, in addition to the cabin feed air flow L that outputs the heat to the cab through the heat exchanger 4, the heat is additionally output to the environment of the vehicle through the external air-refrigerant heat exchanger 6 before the refrigerant is returned again to the refrigerant compressor 5 through the evaporator 3. For this purpose, when closing the shut-off device A1, the refrigerant flows from the heat exchanger 4 into the reheat branch 2.3. Here, the refrigerant is expanded to medium pressure in an air-refrigerant heat exchanger 6 outside the AC and heat pump branch 2.1 by means of a reheat expansion mechanism AE 4. The refrigerant then flows from the AC and heat pump branch 2.1 into the evaporator branch 3.1, where it is expanded to a low pressure in the evaporator 3 by means of the evaporator expansion mechanism AE 2.

Alternatively, the reheat expansion mechanism AE4 may be opened to such an extent that the same high pressure level occurs ideally in the heat exchanger 4 and in the external air refrigerant heat exchanger 6, when the heating power available on the heat exchanger 4 is sufficient.

When heat is absent in the refrigerant circuit 2, that is, when the heating power on the heat exchanger 4 is insufficient, the water chiller 9 is used as a heat source in addition to the evaporator 3. This reheating operation is hereinafter referred to as a second reheating operation.

In this second reheating operation, firstly, when the shut-off device A3 is opened, the heating branch 2.2 and thus the heat exchanger 4 is flowed through by the refrigerant, and then, when the shut-off device A1 is opened, the refrigerant is expanded by means of the associated expansion devices AE1 and AE2 both into the evaporator 3 of the evaporator branch 3.1 and into the water chiller 9 of the water chiller branch 9.1. At the time of the second reheating operation, the heat pump expansion mechanism AE3 and the reheating expansion mechanism AE4 are turned off.

The refrigerant flows back again from the evaporator 3 to the refrigerant compressor 5 through the check valve R1, through the accumulator 10 and the internal heat exchanger 11. The refrigerant from the water chiller 9 flows back to the refrigerant compressor 5 through the accumulator 10 and the internal heat exchanger 11 as well. The heat absorbed in the evaporator 3 and in the water chiller 9 is again output via the heat exchanger 4 together with the heat flow carried in by the refrigerant compressor 5 to the cabin feed air flow L which is fed into the vehicle interior.

Alternatively, in the absence of heat in the refrigerant circuit 2, the air-refrigerant heat exchanger 6 is used either as a heat source in place of the chiller 9 or in parallel with the chiller 9 as an additional heat source.

When the heating power in the refrigerant circuit 2 is sufficient, only the evaporator 3 is flown through by the refrigerant. This reheating operation is called a third reheating operation.

Switching between the operating modes described above is achieved by actuating a single shut-off element, which is either configured as a shut-off valve or as an expansion valve. A switching valve or a multiple-way valve is also used for this purpose. The shut-off means can be controlled electrically and can be adjusted in any intermediate position between 0% of the cross-sectional opening and 100% of the cross-sectional opening and can be held in this intermediate position.

In order to prevent interruption of the heating and/or cooling power during such a switching process, but at least to minimize the interruption and to avoid restarting the refrigeration appliance 1, a different switching process between the above-described operating modes is exemplarily explained next.

The switching strategies described below each use the same concepts for a transition from an operating mode, hereinafter referred to as a first operating mode, to another operating mode, hereinafter referred to as a second operating mode. In this change from the first to the second operating mode, the refrigerant flow is diverted in the branching section of the refrigerant circuit 2. Such branching sections, i.e. the first branching section VZ1, the second branching section VZ2 and the third branching section VZ3, have valve mechanisms with which the refrigerant flow, hereinafter referred to as first refrigerant flow, is diverted from the first guiding section for executing the first operating mode into the second guiding section as second refrigerant flow for executing the second operating mode. The valve mechanism of the branching section that causes the first refrigerant flow is referred to as a first valve mechanism, and the valve mechanism of the branching section that causes the second refrigerant flow is referred to as a second valve mechanism.

Depending on which switching process between the two operating modes is described, the designations "first valve means", "second valve means", "third valve means", "fourth valve means" and "nth valve means" are used for the valve means of the respective branch section involved in the switching, wherein "n" represents the maximum number of valve means present and switchable.

First, the switching of the refrigeration apparatus 1 from the AC operation as the first operation mode to the heat pump operation as the second operation mode will be described.

The first branching section VZ1 participates in this switching process, which has a shut-off means A4 as a first valve means (which effects a first refrigerant flow into the AC and heat pump branch 2.1) and a shut-off means A3 as a second valve means (which effects a second refrigerant flow into the heating branch 2.2). In addition, the throttle mechanism A1 as the third valve mechanism also participates in the switching process.

In addition to the main flow circuit described above, the valve mechanism A5 of the secondary flow is closed before the start of the change of flow direction.

In AC operation as the first operation mode, the first valve mechanism A4 is opened, and the second and third valve mechanisms A3 and A1 are closed. For AC operation, the heat pump expansion mechanism AE3 is of course fully opened, so that the refrigerant can be expanded into the evaporator 3 by means of the evaporator expansion mechanism AE 2.

The switching process is started in such a way that the rotational speed of the refrigerant compressor 5 is constantly maintained at a predetermined rotational speed value or a last set rotational speed value during the switching process.

At the same time as the refrigerant compressor 5 is "fixed" at a constant rotational speed value, or immediately thereafter, the second valve mechanism A3 is opened at a prescribed displacement speed up to a preset target cross section. As the preset target cross section is reached, the closing process of the first valve mechanism A4 is started, wherein the cross section of the first valve mechanism is continuously reduced to a value of zero. Starting from a preset target cross section, the second valve mechanism A3 is fully opened. The time offset between reaching the preset target cross section of the second valve means A3 and starting the closing process of the first valve means A4 is ultimately related to the displacement speed of the valve being actuated, which can be varied according to the drive scheme.

In addition to the time dependence, a movement pattern related to the opening section can also be selected. If the valve means reaches a defined displacement position and thus a corresponding opening section, the closing process of the second valve means can be started. The novel valve mechanism enables precise position feedback, so that the control of the refrigeration system 1 always knows the current valve position and thus the opening section stored by the characteristic curve.

In order to be able to flow through the heating branch 2.2 with the second refrigerant flow, the third valve means A1 is opened, so that the refrigerant either can flow into the chiller branch 9.1 for performing a water heat pump operation and/or can flow into the AC and heat pump branch 2.1 for performing an air heat pump operation.

The third valve means A1 is opened in synchronism with the first valve means A4 section by closing the first valve means A4 at a time offset with respect to the second valve means A3 but soon thereafter. The first valve means A4 and the third valve means A1 are thereby moved in opposite directions in synchronization, so that in an alternative variant the sum of the cross sections of the closed first valve means A4 and the open third valve means A1 corresponds to the initial maximum cross section of the closed first valve means A4. The closing of the first valve mechanism A4 and the opening of the third valve mechanism A1 are started at the same timing.

Advantageously, the heat pump expansion mechanism AE3 is closed synchronously with the closing of the valve mechanism A4 and the opening of the valve mechanism A1, or the heat pump expansion mechanism AE3 is kept on a small open cross section for the case of the following air heat pump operation. The valve mechanism A2 is also opened irrespective of whether the air heat pump operation or the water heat pump operation is performed. Since there is a risk of shorting the flow of refrigerant from the outlet to the inlet of the refrigerant compressor 5 through the valve mechanism A2 before the valve mechanism A4 is completely closed, the valve mechanism A2 is preferably opened directly after the valve mechanism A4 is closed, alternatively is opened quickly to a certain cross-sectional area before being completely closed.

When the first valve mechanism A4 is fully closed and the third valve mechanism A1 and the valve mechanism A2 are fully opened, the switching process from the AC operation as the first operation mode to the heat pump operation as the second operation mode is ended. Thereby, the heat pump operation may be performed by means of the water chiller 9 and/or by means of the air-refrigerant heat exchanger 6 as a heat pump evaporator.

The first branching section VZ1 participates in the reverse switching process, i.e., the switching process from the heat pump operation as the first operation mode to the AC operation as the second operation mode, and has a shut-off mechanism A3 (which realizes the first refrigerant flow into the heating branch 2.2) as the first valve mechanism and a shut-off mechanism A4 (which realizes the second refrigerant flow into the AC and heat pump branch 2.1) as the second valve mechanism. In addition, the valve mechanism A1 and the second valve mechanism A2 as the fourth valve mechanism and the heat pump expansion mechanism AE3 also participate in the switching process.

In the heat pump operation as the first operation mode, the first valve mechanism A3 and the fourth valve mechanism A1 are opened, and the second valve mechanism A4 is closed. In order to achieve heat pump operation, the refrigerant is either expanded into the AC and heat pump branch 2.1 by means of the heat pump expansion mechanism AE3 and/or into the chiller branch 9.1 by means of the chiller expansion mechanism AE 1.

The switching process is likewise started in such a way that the rotational speed of the refrigerant compressor 5 is constantly maintained at a predetermined rotational speed value or at a final set rotational speed value during the switching process.

At the same time as the refrigerant compressor 5 is "fixed" at a constant rotational speed value, or immediately thereafter, the second valve arrangement A4 is opened at a defined displacement speed up to a preset target section, and the closing of the valve arrangement A2 is directly or temporally associated with this displacement process. As the preset target cross section is reached, the closing process of the first valve mechanism A3 is started, wherein the cross section of the first valve mechanism A3 is continuously reduced to the value zero. Starting from the preset target cross section, the second valve mechanism A4 is fully opened. The time offset between reaching the preset target cross section of the second valve means A4 and starting the closing process of the first valve means A3 is only dependent on the displacement speed of the actuated valve means, which can be varied according to the drive scheme.

Finally, the opening section associated with the displacement process is again evaluated by means of the valve characteristic curve and position recognition, and the displacement process is started on the basis of the values obtained.

In order to prevent the refrigerant from flowing back from the AC and heat pump branch 2.1 into the heating branch 2.2 during AC operation, the shut-off means A1 as fourth valve means must of course be closed. In order to avoid short-circuiting with the low-voltage side in AC operation, the same applies to the valve mechanism A2.

The fourth valve means A1 is opened in synchronization with the first valve means A3 section by closing the first valve means A3 later with a time offset with respect to the second valve means A4. Thereby, the first valve mechanism A3 and the fourth valve mechanism A1 are synchronously moved in the same direction into their closed states. Desirably, the closing of the first valve mechanism A4 and the closing of the fourth valve mechanism A1 are started simultaneously. Alternatively, a time offset may also be implemented. At this time, the closing process of the first valve mechanism A3 is started before the fourth valve mechanism A1.

When the first and fourth valve mechanisms A3 and A1 and, if necessary, the valve mechanism A2 are completely closed, the switching process from the heat pump operation as the first operation mode to the AC operation as the second operation mode is ended. Thereby, AC operation can be performed by means of the evaporator 3.

Now, a switching process from the air heat pump operation as the first operation mode to the water heat pump operation as the second operation mode will be described.

When the air heat pump is in operation, the heating branch 2.2 is connected on the upstream side to the high-pressure output of the refrigerant compressor 5 when the shut-off element A3 is opened, and is continuously connected on the downstream side to AC and the heat pump branch 2.1 by means of the heat pump expansion element AE3 via the opened shut-off element A1, wherein the shut-off element A2 of the heat pump recirculation branch 2.4 is also opened. When the water heat pump is in operation, the heating branch 2.2 is connected to the water chiller branch 9.1. During operation of both heat pumps, the evaporator expansion mechanism AE2 and the reheat expansion mechanism AE4 are closed.

The second branch section VZ2 participates in this switching process, which has a heat pump expansion mechanism AE3 (which realizes the first refrigerant flow into AC and heat pump branch 2.1) as a first valve mechanism and a cold water machine expansion mechanism AE1 (which realizes the second refrigerant flow into cold water machine branch 9.1) as a second valve mechanism.

In the air heat pump operation as the first operation mode, the first valve mechanism AE3 is opened to perform its expansion function with a corresponding cross section, and the second valve mechanism AE1 is closed. In order to achieve the water heat pump operation, the refrigerant is expanded into the chiller branch 9.1 by means of a chiller expansion device as the second valve device AE1.

The switching process to the water heat pump operation as the second operating mode is likewise started in such a way that the rotational speed of the refrigerant compressor 5 is constantly maintained at a predetermined rotational speed value or at a last regulated rotational speed value during the switching process.

At the same time as the refrigerant compressor 5 is "fixed" at a constant rotational speed value, or immediately thereafter, the second valve mechanism AE1 is opened at a predetermined displacement speed up to a preset target cross section. As the preset target cross section is reached, the closing process of the first valve mechanism AE3 is started, wherein the cross section of the first valve mechanism AE3 is continuously reduced to a value of zero. Starting from a preset target section, the second valve mechanism AE1 is opened to a theoretical section to satisfy its expansion function. The time offset between reaching the predetermined target section of the second valve element AE1 and starting the closing process of the first valve element AE3 ultimately depends on the displacement speed of the actuated valve, which can be varied according to the drive scheme.

As a result of the extraction of refrigerant from the AC and heat pump branch 2.1, the shut-off means A2 of the heat pump recirculation branch 2.4 remain open, while all other valve means remain in the state they last occupied before the switching process. Thereby, the switching process is completed.

Now, the reverse switching process, i.e., the switching from the water heat pump process as the first operation mode to the air heat pump process as the second operation mode, will be described.

The second branching section VZ2 participates in this switching process, which has a chiller expansion mechanism AE1 as a first valve mechanism (which effects a first refrigerant flow into the chiller branch 9.1) and a heat pump expansion mechanism AE3 as a second valve mechanism (which effects a second refrigerant flow into the AC and heat pump branch 2.1).

The switching process to the air heat pump process as the second operating mode is likewise started in such a way that the rotational speed of the refrigerant compressor 5 is constantly maintained at a predetermined rotational speed value or at a last adjusted rotational speed value during the switching process.

At the same time as the refrigerant compressor 5 is "fixed" at the theoretical rotational speed value, or immediately thereafter, the second valve mechanism AE3 is opened at a predetermined displacement speed up to a preset target cross section. As the preset target cross section is reached, the closing process of the first valve mechanism AE1 is started, wherein the cross section of the first valve mechanism is continuously reduced to a value of zero. Starting from a preset target section, the second valve mechanism AE3 is opened to a section (theoretical section) required for performing the expansion function. The time offset between reaching the predetermined target section of the second valve element AE3 and starting the closing process of the first valve element AE1 ultimately depends on the displacement speed of the actuated valve, which can be varied according to the drive scheme.

Next, the switching of the refrigeration apparatus 1 from the AC operation as the first operation mode to the first reheating operation as the second operation mode will be described.

The first branching section VZ1 participates in this switching process, which has a shut-off means A4 as a first valve means (which effects a first refrigerant flow into the AC and heat pump branch 2.1) and a shut-off means A3 as a second valve means (which effects a second refrigerant flow into the heating branch 2.2). In addition, the reheating expansion mechanism AE4 as the third valve mechanism also participates in the switching process.

In the AC operation as the first operation mode, the first valve mechanism A4 is opened, and the second valve mechanism A3 and the third valve mechanism AE4 are closed. For AC operation, the heat pump expansion mechanism AE3 is of course fully opened, so that the refrigerant can be expanded into the evaporator 3 by means of the evaporator expansion mechanism AE 2.

The switching process is started in such a way that the rotational speed of the refrigerant compressor 5 is constantly maintained at a predetermined rotational speed value or a final rotational speed value that is set during the switching process.

At the same time as the refrigerant compressor 5 is "fixed" at the theoretical rotational speed value, or immediately thereafter, the second valve mechanism A3 is opened at a prescribed moving speed up to a preset target cross section. As the preset target cross section is reached, the closing process of the first valve mechanism A4 is started, wherein the cross section of the first valve mechanism is continuously reduced to zero. Starting from a preset target cross section, the second valve mechanism A3 is maximally opened to a theoretical cross section or fully opened. The time offset between reaching the preset target cross section of the second valve means A3 and starting the closing process of the first valve means A4 is only dependent on the displacement speed of the valve being actuated, which can be varied according to the drive scheme.

In order to be able to flow through the heating branch 2.2 with the second refrigerant flow, the third valve mechanism AE4 is opened to perform a corresponding expansion function, so that the refrigerant for performing the first reheating operation can flow into the reheating branch 2.3.

By subsequently closing the first valve means A4 with a time offset relative to the second valve means A3, the third valve means AE4 is opened in synchronization with the first valve means A4 section. Thus, the first valve means A4 and the third valve means AE4 are moved in opposite directions in synchronization, so that the sum of the cross sections of the closed first valve means A4 and the open third valve means AE4 corresponds to the initial maximum cross-sectional area of the closed first valve means A4. The closing of the first valve mechanism A4 and the opening of the third valve mechanism AE4 are started at the same timing.

In order to prevent a short circuit between the heating branch 2.2 and the suction side of the refrigerant compressor 5, the valve means A5 is closed before the switching process, the valve means A5 causing refrigerant to be drawn out of part of the heating branch 2.2 in AC operation.

When the first valve mechanism A4 is fully closed and the third valve mechanism AE4 is opened up to 100% of the target cross section, the switching process from the AC operation as the first operation mode to the first reheating operation as the second operation mode is ended. Thereby, the first reheating operation can be performed by means of the heat exchanger 4, the external air-refrigerant heat exchanger 6 and the evaporator 3.

The first branching section VZ1 participates in the reverse switching process, i.e., the switching from the first reheating operation as the first operation mode to the AC operation as the second operation mode, and has a shut-off mechanism A3 (which realizes the first refrigerant flow into the heating branch 2.2) as the first valve mechanism and a shut-off mechanism A4 (which realizes the second refrigerant flow into the AC and heat pump branch 2.1) as the second valve mechanism. In addition, the reheat expansion mechanism AE4 as the fourth valve mechanism also participates in the switching process.

In the first reheating operation as the first operation mode, the first valve mechanism A3 and the fourth valve mechanism AE4 are opened, and the second valve mechanism A4 is closed. To achieve AC operation, the second valve arrangement A4 is opened, so that refrigerant can flow into the AC and heat pump branch 2.1 and into the evaporator branch 3.1 when the heat pump expansion arrangement AE3 is opened.

Likewise, the switching process from the first reheating operation as the first operation mode to the AC operation as the second operation mode is started such that the rotational speed of the refrigerant compressor 5 is constantly maintained at a predetermined rotational speed value or a last adjusted rotational speed value during the switching process.

At the same time as the refrigerant compressor 5 is "fixed" at the theoretical rotational speed value, or immediately thereafter, the second valve mechanism A4 is opened at a prescribed movement speed up to a preset target cross section. As the preset target cross section is reached, the closing process of the first valve mechanism A3 is started, wherein the cross section of the first valve mechanism is continuously reduced to a value of zero. Starting from the preset target cross section, the second valve mechanism A4 is fully opened. The time offset between reaching the preset target cross section of the second valve means A4 and starting the closing process of the first valve means A3 is ultimately related to the displacement speed of the valve being actuated, which can be varied according to the drive scheme.

In order to prevent refrigerant from flowing from the reheat branch 2.3 into the heating branch 2.2 during AC operation, the reheat expansion mechanism AE4 as the fourth valve mechanism must of course be closed.

By subsequently closing the first valve means A3 with a time offset with respect to the opening of the second valve means A4, the fourth valve means AE4 is closed in synchronization with the first valve means A3 section. Thereby, the first valve mechanism A3 and the fourth valve mechanism AE4 are synchronously moved in the same direction into their closed state. Simultaneously, the closing of the first valve mechanism A3 and the closing of the fourth valve mechanism AE4 are started. Alternatively, the closing of the reheat expansion mechanism AE4 as the fourth valve mechanism may also be associated with or before the opening process of the second valve mechanism A4 to thereby avoid an unspecified refrigerant flow. Due to the device state and the density of the refrigerant on the fourth valve mechanism AE4, even early actuation and thus the start of the closing process can be taken as an alternative method.

When the first valve mechanism A3 and the fourth valve mechanism AE4 are fully closed, the switching process from the first reheating operation as the first operation mode to the AC operation as the second operation mode is ended. Thereby, AC operation can be performed by means of the evaporator 3. After its end, the valve means A5 is opened and the withdrawal of refrigerant from part of the heat pump branch 2.2 is started thereby.

As a final example of the switching process, the switching of the refrigeration apparatus 1 from the first reheating operation as the first operation mode to the second reheating operation as the second operation mode is described.

The third branching section VZ3 participates in this switching process, which has a reheat expansion mechanism AE4 (which effects a first refrigerant flow into the reheat branch 2.3) as a first valve mechanism and a shutoff mechanism A1 (which effects a second refrigerant flow into the evaporator branch 3.1 and into the chiller branch 9.1) as a second valve mechanism. In addition, the heat pump expansion mechanism AE3 as the fourth valve mechanism also participates in the switching process.

In the first reheating operation as the first operation mode, the first valve mechanism AE4 is at least partially opened, and the second valve mechanism A1 is closed. To achieve the second reheating operation, the reheating expansion mechanism AE4 is completely closed, the shutoff mechanism A1 is completely opened, and the cold water machine expansion mechanism AE1 and the evaporator expansion mechanism AE2 are opened to a preset target cross section to perform the expansion function.

At the same time as the refrigerant compressor 5 is "fixed" at the theoretical rotational speed value, or immediately thereafter, the second valve mechanism A1 is opened at a prescribed movement speed up to a preset target cross section. As the preset target cross section is reached, the closing process of the first valve mechanism AE4 is started, wherein the cross section of the first valve mechanism is continuously reduced to a value of zero. Starting from a preset target cross section, the second valve mechanism A1 is maximally opened to a theoretical cross section or fully opened. The time offset between reaching the preset target section of the second valve arrangement A1 and starting the closing process of the first valve arrangement AE4 ultimately depends on the displacement speed of the actuated valve, which can be varied according to the drive scheme.

In order to be able to flow through the reheat branch 2.3 and then through the AC and the heat pump branch 2.1 with the first refrigerant flow, the fourth valve mechanism AE3 is opened.

By closing the first valve element AE4 subsequently, with a time offset relative to the second valve element A1, the third valve element AE3 is opened in synchronization with the first valve element AE4 in cross section. The closing of the first valve mechanism AE4 and the closing of the fourth valve mechanism AE3 are started at the same timing. Finally, to achieve the extraction of refrigerant from the deactivated AC and heat pump branch 2.1, the valve mechanism A2 is opened.

When the first valve mechanism AE4 and the fourth valve mechanism AE3 are completely closed, the switching process from the first reheating operation as the first operation mode to the second reheating operation as the second operation mode is ended. Thereby, a second reheating operation can be performed by means of the evaporator 3 and the water chiller 9.

The third branching section VZ3 takes part in the opposite switching process, i.e. from the second reheating operation as the first operating mode to the first reheating operation as the second operating mode, the first branching section having a shut-off means A1 as a first valve means (which effects the first refrigerant flow into the evaporator branch 3.1 and into the cold water branch 9.1) and a reheating expansion means AE4 as a second valve means (which effects the second refrigerant flow into the reheating branch 2.3).

In the second reheating operation as the first operation mode, the first valve mechanism A1 is opened, and the second valve mechanism AE4 and the heat pump expansion mechanism AE3 are closed. In addition, in this second reheating operation, the chiller expansion mechanism AE1 and the evaporator expansion mechanism AE2 are adjusted to the theoretical value cross section to perform the expansion function. In the first reheating operation as the second operation mode, the first valve mechanism AE4 and the heat pump expansion mechanism AE3 as the third valve mechanism are opened, and the second valve mechanism A1 is closed.

In order to prevent the refrigerant flow from entering the refrigerant compressor directly during the active flow AC and the heat pump branch 2.1, the valve means A2 is closed before the switching process from the second reheating operation as the first operating mode to the first reheating operation as the second operating mode, and before the start, the rotational speed of the refrigerant compressor 5 is set to the v setpoint rotational speed value or to the last set rotational speed value during the switching process.

At the same time as the refrigerant compressor 5 is "fixed" at the theoretical rotational speed value, or immediately thereafter, the second valve mechanism AE4 is opened at a predetermined displacement speed up to a preset target cross section. As the preset target cross section is reached, the closing process of the first valve mechanism A1 is started, wherein the cross section of the first valve mechanism is continuously reduced to a value of zero. Starting from a preset target section, the second valve mechanism AE4 is opened to a theoretical section for performing the expansion function. The time offset between reaching the preset target section of the second valve element AE4 and starting the closing process of the first valve element A1 ultimately depends on the displacement speed of the actuated valve, which can be varied according to the drive scheme.

In order to achieve a refrigerant flow into the AC and the heat pump branch 2.1 in the first reheating operation, it is of course necessary to open the heat pump thermal expansion mechanism AE3 as the third valve mechanism.

By subsequently closing the first valve element A1 with a time offset relative to the second valve element AE4, the third valve element AE3 is opened in synchronization with the second valve element AE4 in cross section. Thereby, the first valve mechanism A1 and the third valve mechanism AE3 are synchronously moved in the same direction. Simultaneously, the closing of the first valve mechanism A1 and the opening of the fourth valve mechanism AE3 are started.

When the first valve mechanism A1 is fully closed and at the same time the third valve mechanism AE3 is fully opened, the switching process from the second reheating operation as the first operation mode to the reheating operation as the second operation mode is ended. Thereby, the first reheating operation can be performed by means of the evaporator 3 and the external air-refrigerant heat exchanger 6.

In the above-described embodiment, the refrigerant compressor 5 is constantly maintained at the prescribed rotational speed value as the switching process starts until the switching process ends. The defined rotational speed value may correspond to a rotational speed value set prior to the switching or a predefined rotational speed value, which is calculated from a characteristic curve or table stored in the control unit or according to a suitable formula.

Other switching processes of the refrigeration system 1 between the two operating modes can of course also be implemented, the basic process corresponding to the switching process described above.

In this case, for switching from the first operating mode to the second operating mode, the guide branch responsible for this is released by means of the valve mechanism, wherein the valve mechanism is opened before the valve mechanism that implements the first operating mode is closed in a time-staggered manner.

If a further valve means is required for the flow through the guide branch for the second operating mode, the valve means is opened synchronously with the closing section of the valve means for the first operating mode.

If a further valve means is required for preventing the flow of refrigerant through the guide branch which implements the first operating mode, the further valve means is closed in synchronization with the valve means cross section which implements the first operating mode.

In general, the expansion means have different characteristic curves with respect to the shut-off means, that is to say different cross-sectional openings are obtained with the same control signal. However, in the ideal case, all the valve means have approximately the same maximum opening section, which ultimately leads to low flow losses in the shut-off means and which considerably simplifies the maintenance (assembly and disassembly) of the entire system in the expansion means.

The rotational speed of the compressor 5 is fixed at the theoretical rotational speed and always overlaps with the safety function of monitoring the allowable high pressure and high temperature gas temperature.

List of reference numerals

1. Refrigerating apparatus

1.1 Air conditioning equipment

2. Refrigerant circuit of refrigeration device 1

2.1 AC and heat pump branch of refrigerant circuit 2

2.2 Heating branch

2.3 Reheat branch

2.4 Heat pump recirculation branch

2.5 Suction branch

3. Evaporator

3.1 Evaporator branch

4. Heat exchanger, heating regulator

4.1 Heating regulator branch

5. Refrigerant compressor

6. External air refrigerant heat exchanger

7. Electric heating element

9. Water chiller

9.0 Cooling medium circulation of water chiller 8

9.1 Water chiller branch

10. Pressure accumulator

11. Internal heat exchanger

A1 Cut-off mechanism

A2 Cut-off mechanism

A3 Cut-off mechanism

A4 Cut-off mechanism

A5 Cut-off mechanism

Ab1 branching Point

Ab2 branching Point

Ab3 branching Point

AE1 water chiller expansion mechanism

AE2 evaporator expansion mechanism

AE3 heat pump expansion mechanism

AE4 reheating expansion mechanism

L carriage feed air flow

PT1 first pressure temperature sensor

PT2 second pressure temperature sensor

PT3 third pressure temperature sensor

PT4 fourth pressure temperature sensor

PT5 fifth pressure temperature sensor

R1 check valve

R2 check valve

VZ1 first branch section

VZ2 second branching section

VZ3 third branch section

Claims

1. Method for operating a refrigeration system (1) for a vehicle, comprising a refrigeration circuit (2) which can be used for both refrigeration system operation and heat pump operation and has at least one branching section (VZ 1, VZ2, VZ 3) for guiding the refrigerant either into a first guide branch for executing a first operating mode or into a second guide branch for executing a second operating mode,

-For switching the refrigerant circuit (2) between a first operating mode and a second operating mode, a first valve means realizing a first refrigerant flow into the first guiding section and a second valve means realizing a second refrigerant flow into the second guiding section are provided, wherein the first valve means and the second valve means are configured with a variably controllable cross section, and

To switch from the first to the second operating mode, the second valve means is first opened to a preset target cross-section, and the first valve means is closed by reducing the cross-section as the preset target cross-section of the second valve means is reached,

By transferring heat of at least one evaporator (3) arranged in the evaporator branch (3.1) to an external air-refrigerant heat exchanger (6) of the AC and heat pump branch (2.1), a refrigeration device operation as a first or second operating mode is performed by means of the AC and heat pump branch (2.1) of the first or second guide branch as a first branching section,

In order to perform an air heat pump operation, the refrigerant is expanded into an air refrigerant heat exchanger (6) acting as an outside of the heat pump evaporator by means of a heat pump expansion mechanism (AE 3) of the AC and heat pump branch (2.1).

2. The method of claim 1, wherein,

By means of a third valve mechanism, the second refrigerant flow can be caused to flow through the second guide branch, and

3. A method according to claim 1 or 2, wherein the flow of refrigerant through the first guide branch is prevented by means of a fourth valve mechanism, and the first valve mechanism and the fourth valve mechanism are closed in synchronism in section.

4. The method according to claim 1 or 2, wherein,

By transferring heat from at least one heat source (5, 6, 9) to the cabin feed air flow (L) by means of a heat exchanger (4) of the heating branch (2.2), a heat pump operation is performed as a second or first mode of operation by means of the heating branch (2.2) as a second or first guiding branch,

The first and the second guide branch can be connected upstream to the refrigerant compressor (5) by means of a first branching section, wherein the AC and the heat pump branch (2.1) are connected to the refrigerant compressor (5) by means of a first valve means or a second valve means (A4) of the first branching section, and the heating branch (2.2) is connected to the refrigerant compressor (5) by means of a second valve means or a first valve means of the first branching section,

-For performing a refrigeration plant operation, the AC and heat pump branch (2.1) is connected to the evaporator branch (3.1), and

-Causing or preventing refrigerant to flow through the heating branch (2.2) by means of a third valve means or a fourth valve means.

5. Method according to claim 4, wherein, for performing a water heat pump operation, the refrigerant is expanded into the water chiller (9) by means of a water chiller expansion mechanism (AE 1) having a water chiller branch (9.1) of the water chiller (9).

6. The method of claim 4, wherein,

In order to perform an air heat pump operation or a water heat pump operation, the second branching section (VZ 2) is connected to the heating branch (2.2),

-To perform an air heat pump operation as a first or second operation mode, guiding the refrigerant from the heating branch (2.2) into the AC and heat pump branch (2.1) as a first or second guiding branch by means of a first or second valve mechanism configured as a heat pump expansion mechanism (AE 3), and

In order to carry out the water heat pump operation as a second or first operating mode, the refrigerant is guided from the heating branch (2.2) into the cold water machine branch as a second or first guide branch by means of a second or first valve mechanism configured as a cold water machine expansion mechanism (AE 1).

7. The method according to claim 1 or 2, wherein,

By transferring heat of at least one evaporator (3) arranged in the evaporator branch (3.1) to an air-refrigerant heat exchanger (6) outside the AC and heat pump branch (2.1), a refrigeration plant operation is performed by means of the AC and heat pump branch (2.1) connectable to the high-pressure output of the refrigerant compressor (5),

The heating branch (2.2) can be connected to a high-pressure output of the refrigerant compressor (5), by means of which a first reheating operation is performed when the heating branch (2.2) is connected to the reheating branch (2.3) and by means of which a second reheating operation is performed when the heating branch (2.2) is connected to the evaporator branch (3.1),

-By means of the third branching section (VZ 3), the heating branch (2.2) is either connected to a reheating branch (2.3) as a first or second guiding branch for performing a first reheating operation as a first or second operation mode; or with an evaporator branch (3.1) as a second or first guide branch and/or with a water chiller branch (9.1) having a water chiller (9), respectively, for carrying out a second reheating operation as a second or first operation mode; wherein, in a first reheating operation, the refrigerant from the reheating branch (2.3) flows through the AC and the heat pump branch (2.1),

By means of the first or second valve means of the third branching section, the heating branch (2.2) is connected to the reheating branch (2.3),

-The heating branch (2.2) is connected to the evaporator branch (3.1) and/or the cold water machine branch (9.1) by means of a second valve mechanism or a first valve mechanism of the third branching section (VZ 3), and

-Preventing or causing the refrigerant to flow through the AC and heat pump branch (2.1) by means of a fourth or third valve mechanism of the third branching section (VZ 3).

8. The method according to claim 1 or 2, wherein,

By transferring heat of at least one evaporator (3) arranged in the evaporator branch (3.1) to an external air-refrigerant heat exchanger (6) of the AC and heat pump branch (2.1), a refrigerating device operation as a first or second operating mode is performed by means of the AC and heat pump branch (2.1) as a first or second guide branch,

Performing a first reheating operation as a second or first operation mode by means of a heating branch (2.2) and a reheating branch (2.3) connected to the heating branch,

-By connecting the AC and heat pump branch (2.1) with the refrigerant compressor via the first valve means or the second valve means (A4) of the first branching section and connecting the heating branch (2.2) with the refrigerant compressor (5) via the second valve means or the first valve means of the first branching section, the first guiding section and the second guiding section are connected upstream with the refrigerant compressor (5) by means of the first branching section, and

-By means of a third valve mechanism or a fourth valve mechanism, the flow of refrigerant from the heating branch (2.2) into the reheating branch (2.3) is caused or prevented.

9. Method according to claim 1 or 2, wherein for switching the refrigerant circuit (2) between the first and the second operating mode, the refrigerant compressor (5) of the refrigerant circuit (2) is adjusted to a predetermined rotational speed value.