WO2020025135A1

WO2020025135A1 - Refrigerant circuit

Info

Publication number: WO2020025135A1
Application number: PCT/EP2018/070919
Authority: WO
Inventors: Oliver Javerschek; Julian KARBINER; Jörg Nickl
Original assignee: Bitzer Kühlmaschinenbau Gmbh
Priority date: 2018-08-01
Filing date: 2018-08-01
Publication date: 2020-02-06
Also published as: EP3830499A1; EP3830500A2; WO2020025770A2; WO2020025770A3

Abstract

The invention relates to a refrigerant circuit (10) comprising: at least one refrigerant compressor (12) which compresses refrigerant fed at a suction connection to high pressure such that a compressor mass flow of the refrigerant compressed to high pressure exits at a pressure connection; at least one heat-emitting heat exchanger (22) on the high-pressure side, having an inlet to which the refrigerant circuit feeds the compressor mass flow and having an outlet from which a cooled total mass flow of refrigerant exits; at least one expansion unit (32); and at least one cooling stage (62) having at least one heat-absorbing heat exchanger to which the refrigerant circuit feeds a main mass flow comprising an expansion pressure mass flow expanded by the expansion unit. The invention also relates to an emergency operation unit (230) associated with the refrigerant circuit.

Description

REFRIGERANT CIRCULATION

The invention relates to a refrigerant circuit, comprising at least one refrigerant compressor, which compresses refrigerant supplied to a suction connection to high pressure, so that a compressor mass flow of the refrigerant compressed to high pressure emerges at a pressure port, at least one high-pressure-side heat-emitting heat exchanger with an inlet at which the refrigerant circuit feeds the compressor mass flow, and with an outlet from which a cooled total mass flow of refrigerant emerges, at least one expansion unit, comprising an expansion compression unit having an expander and a compressor stage, which leads one from the refrigerant circuit in the direction of the suction connection of the refrigerant compressor

Expansion mass flow of the total mass flow expands from high pressure to an expansion pressure, and at least one cooling stage with at least one heat-absorbing heat exchanger, to which the refrigerant circuit supplies a main mass flow comprised by the expansion pressure mass flow expanded by the expansion unit, and which the refrigerant circuit, after leaving the cooling stage, supplies the refrigerant to the suction connection of the refrigerant supplies.

Such refrigerant circuits are known from the prior art.

These always have the problem of operating them as optimally as possible.

This object is achieved according to the invention in a refrigerant circuit of the type described in the introduction in that the refrigerant circuit is assigned an emergency operating unit which comprises a bypass line which bypasses the expansion compression unit and which is functionally assigned to at least one expansion element, and in that the emergency operating unit In the event of a malfunction, in particular an expansion malfunction, the expansion compression unit changes from an inactive state to an active state in which it generates an emergency expansion mass flow for operating the cooling stage by expanding the high-pressure refrigerant by means of the expansion element, which the bypass line prevents Refrigerant circuit for forwarding to the cooling stage.

The advantage of the solution according to the invention can be seen in the fact that the problem is solved by the emergency operating unit according to the invention that in the event of an expansion disturbance of the expansion unit, in particular the expansion compression unit, the refrigerant circuit is no longer functional or can only function to a very limited extent, so that it is insufficient Can provide cooling capacity on the cooling unit and thus the cooling capacity provided by the refrigerant circuit during normal operation is eliminated, which would lead to considerable damage, for example in the case of refrigerant circuits for cooling systems, for example in the case of temperature-sensitive goods.

Such a problem can be avoided by the emergency operating unit according to the invention, since the emergency expansion mass flow generated enables it to continue to provide at least a minimum cooling capacity.

A wide variety of solutions are conceivable with regard to the management of the bypass line.

An advantageous solution provides that the bypass line of the

Emergency operating unit supplies the emergency expansion mass flow directly or indirectly to an expansion line of the refrigerant circuit that receives the expansion pressure mass flow. This is to be understood to mean that the bypass line does not necessarily have to flow directly into the expansion line, but can, for example, also open into the refrigerant circuit before the expansion line, provided that it is ensured that the emergency expansion mass flow is indirectly supplied to the expansion line.

As an alternative or in addition to this, it is preferably provided that the bypass line provides the emergency expansion mass flow during normal operation of the refrigerant circuit that is present under expansion pressure

Expansion pressure mass flow leading line of the refrigerant circuit.

This ensures that the refrigerant circuit with the

Emergency expansion mass flow can be operated at least with a partial output, since the line carrying the expansion pressure mass flow during normal operation is supplied with the emergency expansion mass flow.

No details have so far been given regarding the function of the emergency operating unit.

An advantageous solution provides that the emergency operating unit has a

Expansion disorder of the expansion compression unit detected.

Such an expansion disturbance can be detected, for example, by the expansion element itself.

For this purpose, it is provided, for example, that the emergency operating unit detects a high pressure of the total mass flow or of the expansion mass flow before it enters the expander. In addition, an advantageous solution provides that the emergency operating unit detects a pressure difference between the high pressure of the total mass flow and / or the expansion mass flow before it enters the expander and a line section of the refrigerant circuit which is at expansion pressure.

In this case, the emergency operating unit thus detects a differential pressure, so that it is possible, for example, to use a known pressure relief valve as an expansion element, which, for example, reacts automatically to such a pressure difference and opens automatically when a certain pressure difference is exceeded, thus generating the emergency expansion mass flow.

Another possibility is that the emergency operating unit detects a high pressure of the total mass flow or of the expansion mass flow before it enters the expander with regard to its absolute value.

For this purpose, a pressure sensor is provided, for example.

In order to be able to determine an expansion disturbance of the expansion unit, it is also expediently provided that the emergency operating unit compares the high pressure of the total mass flow or of the expansion mass flow with a reference high pressure before it enters the expander.

A transition of the emergency operating unit from the inactive state to the active state can be realized particularly advantageously when the

Emergency operating unit has a controller that transfers the emergency operating unit from the inactive state to the active state. Such a control, for example, compares the detected high pressure of the total mass flow or the expansion mass flow before it enters the expander with a stored reference pressure, for example.

In order to ensure that a defined operation of the refrigerant circuit is possible in the active state of the emergency operating unit, it is preferably provided that the emergency operating unit comprises at least one shutdown element for turning off the expansion compression unit.

This ensures that, for example, a leak in the expansion compression unit no longer interferes with the function of the refrigerant circuit and faulty operation of the expander and compressor stage does not cause a malfunction in the refrigerant circuit, which may counteract the function of the emergency operating unit or could also disrupt it.

With regard to the arrangement of the shutdown element, the

different solutions possible.

An advantageous solution provides that the shutdown element of the emergency operating unit is arranged either in front of an expander inlet or after an expander outlet, so that there is primarily the possibility of switching off the expander of the expansion compression unit.

In addition, an advantageous solution provides that a switching element is arranged in the bypass line of the emergency operating unit, which produces a direct or indirect connection between an expansion element for generating the supercooling mass flow of the expansion unit and an expansion pressure outlet connection of the expansion unit. This solution has the advantage that an expansion device, which is present in the expansion unit anyway, can be used by the emergency operating unit to generate a supercooling mass flow

Generate emergency expansion mass flow instead of the supercooling mass flow so that no additional expansion element is required.

For example, it is provided that the switching element through the

Control of the emergency operating unit is controllable.

In particular, it is advantageous if the switching element is a switching valve.

Another advantageous solution provides that the switching element is a

3/2 directional control valve that connects either the bypass line or an expander outlet to the expansion pressure outlet connection.

A 3/2-way valve is preferably also used to close the expander outlet when the bypass line is connected to the expansion pressure outlet connection or to close the bypass line when the expander outlet is connected to the expansion pressure outlet connection.

As an alternative or in addition to the previously described embodiments, a further solution to the problem according to the invention provides that a pulsation damper unit is arranged in the refrigerant circuit.

Such a pulsation damper unit has the great advantage that it is able to dampen pulsations, in particular pulsations generated by the expansion compression unit, in order to prevent damage and / or noise in the refrigerant circuit caused by such pulsations. A variant of such a pulsation damper unit provides that it has a damper housing enclosing a damper chamber, in which at least one gas bubble is formed from refrigerant and that the gas bubble leads to a line of the refrigerant circuit

Pulsation transmission line picks up pulsations and is able to dampen them.

In the case of operation of the refrigerant circuit in the transcritical area, this generally leads to the refrigerant being present in the transcritical area and thus transmitting the pulsations in this state.

However, pulsations are more serious if the refrigerant in the

subcritical area in the refrigerant circuit, since the pulsations then spread through the refrigerant present in the liquid state.

For this reason, especially when the refrigerant circuit is operating in the subcritical range, it is provided that the gas bubble is above a refrigerant bath and, in this case in particular, there is liquid refrigerant in the pulsation transmission line, which transmits the pulsations into the refrigerant bath from liquid refrigerant ,

In order to ensure that a gas bubble is present in the pulsation damper unit in all cases, it is preferably provided that the pulsation damper unit is provided with a heater for maintaining the gas bubble made of refrigerant, so that this can also ensure that the refrigerant circuit is operated subcritically there is always a sufficient size of the gas bubble that dampens pulsations in the pulsation damper unit. For example, the pulsation damper unit is heated,

in particular the damper housing of the same, by coupling the heating to a heat transport circuit which extracts heat in the refrigerant circuit to a pressure in the region of high pressure compressed refrigerant.

Another variant of a pulsation damper unit according to the invention provides that the pulsation damper unit has a damper housing with a piston movable in it and two chambers adjacent to the piston on opposite sides and separated from one another by the piston, and that in at least one of the chambers there is a gas bubble made of refrigerant formed.

In this case, the piston serves to dampen at least one of the gas bubbles that form in at least one of the chambers

To have an effect.

It is particularly advantageous if the piston itself in the damper housing is additionally acted upon by elastic elements, for example springs, which hold the piston in an initial position, from which the piston then acts to dampen pulsations against the force of the elastic force Elements can move.

In order to achieve optimum pulsation damping in this case, it is preferably provided that each of the chambers is connected to different flows of refrigerant lines of the refrigerant circuit by means of a pulsation transmission line.

Such a pulsation damper unit thus serves, in particular, to dampen pulsations by using a connection between different flows of refrigerant lines, which for example can also be at different pressure levels,

Pulsations in one of the two lines or in both of these lines to dampen, these lines remain decoupled by the piston, but a pulsation in one of the lines dampens the other of the

Lines can be transmitted and thus, in addition to the piston itself, a damping effect occurs due to the coupling of the different flows of lines carrying refrigerant.

For example, in such a case it is provided that one pulsation transmission line is connected directly or indirectly to an input of the heat-emitting heat exchanger and the other pulsation transmission line is connected directly or indirectly to an output of the heat-emitting heat exchanger.

Furthermore, the damping effect of such a pulsation damper unit can be further improved if at least one pulsation transmission line is coupled to the refrigerant circuit via a throttle.

As an alternative or in addition to the solutions described so far, the task mentioned at the outset is also achieved in that between the

Expansion unit and the cooling stage an intermediate pressure collector is arranged in the bath, a liquid phase of the refrigerant collects and in the gas volume above the bath, a gas phase of the

Refrigerant collects.

In this solution, the liquid phase is preferably fed to the cooling stage for expansion in the expansion element thereof.

In this case, the intermediate pressure collector has the advantage that additional subcooling can be achieved in the intermediate pressure collector by the refrigerant kept at intermediate pressure. In the case of an intermediate pressure collector, it is preferably provided that an additional mass flow is removed from the gas volume of the intermediate pressure collector.

Such an additional mass flow can in particular be via

Feed the expansion device to the suction pressure line.

In addition, there is the possibility that the additional mass flow expanded by the expansion element additionally sub-cools a main mass flow led to the cooling stage in a heat exchanger, so that the main mass flow can be cooled even further.

Furthermore, it is preferably also possible in the context of this solution that the cooling stage is connected to a freezer stage in the form of a booster.

The provision of an intermediate pressure collector and an expansion element for controlling the additional mass flow discharged from the intermediate pressure collector furthermore makes it possible to regulate an intermediate pressure in the intermediate pressure collector to a specific pressure value by means of an intermediate pressure control which controls the expansion element.

In the solutions known from the prior art, regulation is usually carried out to a fixed pressure value of the intermediate pressure, which is in particular independent of the regulation or control of the high pressure in the total mass flow, which is carried out via the control assigned to the expansion unit.

However, the COP (coefficient of performance), i.e. the ratio of cooling power to mechanical power used, in particular in

To improve summer operation or to expand a functional area of the expansion compression unit, in particular in continued operation, several alternatives are conceivable. One solution provides that the intermediate pressure control which controls the expansion element detects the pressure and / or the temperature of the total mass flow in the high-pressure discharge line and the size of the inlet pressure of the compressor stage and controls the intermediate pressure in such a way that a predefined quantity suitable for these is determined Value of the inlet pressure.

Another inexpensive solution provides that the pressure value at which the intermediate pressure in the intermediate pressure collector is regulated by the intermediate pressure control is based on your basic value, for example a value in the range from 30 bar to 45 bar in the case of CO2 as a refrigerant, and additional values with amounts, for example in the range from 0.5 bar to 7 bar in the case of CO2 as a refrigerant.

This solution has the advantage that additional efficiency increases are possible by adapting the intermediate pressure and, for example, thus also due to the reaction on the expansion unit, in particular on an inlet pressure of the compressor stage.

For example, this is done in that the surcharge values have positive values in summer operation and negative values in winter operation, the amounts of the surcharge values being in the range mentioned above.

Furthermore, it is also advantageous if the size of the additional values is dependent on the values of the high pressure that arise when regulating the high pressure.

This means that the size of the surcharge values also varies depending on the resulting values of the control of the high pressure by means of the expansion unit mentioned at the beginning. For example, it is provided that in summer operation the additional values are higher for high values of the high pressure than for low values of the high pressure.

It is also advantageously provided that the

Surcharge values for high high pressure values are smaller than for low high pressure values.

The amounts of the surcharge values are in the range from 0.5 bar to 7 bar.

With regard to the expansion unit itself, no further details have been given, except that it comprises an expansion compression unit with an expander and a compressor stage.

As an alternative or in addition to the solutions described above, a further solution to the above-mentioned object provides an energetically highly efficient refrigerant circuit, the expansion unit being one

Expansion system which has a subcooling unit for subcooling the total mass flow of refrigerant supplied to the expansion unit, the expansion compression unit comprising the expander and the compressor stage, a branch which branches off a subcooling mass flow from the total mass flow supplied to the expansion unit and is connected to a feed line, which leads the supercooling mass flow to an inlet of the subcooling unit, has an expansion element provided in the feed line, which expands the subcooling mass flow to a subcooling pressure, and has a connecting line which supplies the subcooling mass flow emerging from the subcooling unit to the compressor stage, which in turn supplies the subcooling mass flow compressed to a high pressure return, which is at least one high pressure

corresponds to the compressor mass flow to which the supercooling mass flow is supplied. To control the high pressure of the total mass flow, it is particularly advantageous if an electrically operating control is provided which has at least one of the following variables such as: an ambient temperature, a temperature of the expansion unit and / or the expander stage

supplied mass flow of the refrigerant and an input pressure of the compressor stage, and an input pressure of the expansion unit or the expander stage - and thus indirectly the high pressure of the total mass flow - and / or possibly one according to this temperature and / or possibly this input pressure of the compressor stage

Inlet pressure of the compressor stage by controlling the supercooling mass flow by means of the one that is electrically controlled by the controller

Expander.

The advantage of this solution can be seen in the fact that it works with high energy efficiency, since no throttle element is provided in the mass flow supplied to the expander stage in order to adjust the mass flow flowing to the expander stage.

Rather, the mass flow flowing to the expander stage and relevant for the inlet pressure of the expansion unit or the expansion compression unit is set exclusively via the control of the subcooling mass flow by means of the one controlled by the control

Expansion device so that when expanding the mass flow in the

Expander stage a maximum energy recovery takes place, which leads to

Compression of the supercooling mass flow can be used in the compressor stage, so that, at the same time, optimal expansion of the expanded mass flow takes place before it expands.

In particular, the expansion element includes an electrical one

drivable servomotor. A wide variety of solutions are conceivable with regard to the measurement of the temperature of the mass flow of the refrigerant.

One solution provides for the controller to control the ambient temperature and / or the temperature of the mass flow of the refrigerant

Measures input of the supercooling unit and / or before it enters the expander by means of a sensor.

Another solution comprising the temperature of the mass flow of the refrigerant provides for the temperature of the mass flow of the refrigerant to be measured with a sensor before it enters the supercooling unit and before it enters the expander.

Another solution provides that the control system detects the ambient temperature by means of a sensor and either alone or, if necessary, in

Combined with the temperature of the mass flow of the refrigerant before it enters the supercooling unit and / or before it enters the expander for the control of the expansion device.

It is particularly advantageous if the control is an electronic control comprising a processor, which controls the expansion element electrically by means of a control program, since with a processor the various correlations between the measured temperature and that with the

Expansion device to be controlled supercooling mass flow can be realized in a simple manner.

In particular, with this configuration of the control system, there is always the possibility of controlling the expansion element in such a way that the supercooling mass flow emerges from the subcooling unit in the overheated state and thus prevents liquid refrigerant in the subcooling mass flow from emerging from the subcooling unit and being supplied to the expansion stage. In order to monitor the temperature of the subcooling mass flow emerging from the subcooling unit, a sensor connected to the control is provided in a connecting line between the subcooling unit and the compressor stage, by a

To record the inlet pressure of the compressor stage, for example if the same should be regulated.

In the solution described, the control program is in particular designed such that it either has an algorithm for determining the

Control of the expansion device includes or a stored

Correlation table which correlates the setting of the expansion element with the measured temperature of the mass flow supplied.

A particularly favorable solution provides that the branching is arranged between the subcooling unit and the expansion compression unit and branches off the subcooling mass flow from the total mass flow after the subcooling unit.

This solution is energetically advantageous in that the branched subcooling mass flow has also been previously cooled in the subcooling mass unit.

This solution is particularly advantageous in the case of subcritical heat dissipation and permits greater subcooling.

This solution also has the advantage that pulsations originating from the expansion compression unit are damped by the supply line leading away from the branch with the expansion element.

No details have so far been given regarding the design of the supercooling unit. The supercooling unit can be designed differently.

One solution provides that the subcooling unit is designed as a heat exchanger unit and cools the mass flow of refrigerant flowing to the expander stage by the subcooling mass flow conducted in counterflow.

Another advantageous solution provides that the subcooling unit is designed as a collecting container, in which a bath of liquid refrigerant of the subcooling mass flow is formed, which is used for the

Expander stage flowing mass flow of the refrigerant cools through the bath-guiding element, wherein a gas volume forms from the bath, from which the gaseous supercooling mass flow is removed.

This solution has the advantage that, on the one hand, the mass flow guided through the element is optimally subcooled and, on the other hand, the removal of the subcooling mass flow from the gas volume ensures that no liquid refrigerant is supplied to the compressor stage for compression.

No details have so far been given regarding the connection of the expander and the compressor stage.

In principle, the expander and the compressor stage could be coupled, for example, by a generator motor unit.

A particularly advantageous solution, however, provides that the expander and the compressor stage of the expansion compression unit are mechanically functionally coupled.

Such a mechanical functional coupling means that the energy generated in the expander is transmitted directly to the compressor stage via a mechanical connection. On the other hand, this solution also has the advantage that the solution according to the invention, namely the control of the mass flow expanded by the expander, can be controlled in a simple manner via the supercooling mass flow, which is compressed by the compressor stage.

In principle, the expander and the compressor stage can be formed by suitable types of rotatingly driven machines.

A particularly advantageous solution provides that the expander and the compressor stage are formed by a free-piston machine in which at least one free-piston can move freely in a piston chamber.

The expansion compression unit is preferably designed such that it has two piston chambers, in each of which a free piston can be moved.

Furthermore, the free pistons can preferably be moved coupled to one another.

In the free piston machine according to the invention it is preferably provided that a first free piston in the respective piston chamber is a first one

Expansion chamber and a first compression chamber separate.

Furthermore, it is advantageously provided that a second free piston in the respective piston chamber separates a second expansion chamber from a second compression chamber.

In order to operate the two free pistons in an advantageous manner, it is preferably provided that the two free pistons are arranged coaxially with one another in the piston chambers and are movable.

The first piston chamber is expediently separated from the second piston chamber by a separating body. An advantageous operation of the expansion compression unit can be realized if the two expansion chambers are arranged adjacent to the separating body in the piston chambers.

It is further preferably provided that the two compression chambers are arranged on the sides of the respective free pistons opposite the expansion chambers.

In principle, the free pistons can work independently of each other.

An advantageous solution provides, however, that a coupling element coupling the free pistons extends through the separating body and can be moved relative to it, in particular in a sealed manner.

In the simplest case, the coupling element is designed such that it extends through the expansion chambers as far as the respective free piston.

With regard to the inflow of the refrigerant to the expansion chambers, it is preferably provided that these can be controlled by a slide system.

Such a slide system is designed, for example, as an interchangeable slide, so that in a slide position the refrigerant flows into a

Expansion chamber flows and flows out of the other expansion chamber and in the other slide position the refrigerant flows into the other expansion chamber and flows out of the other expansion chamber.

To control the slide system, it is preferably provided that the slide system can be controlled by a slide drive with which the two slide positions can be set. Such a slide drive can be implemented by an electrical control which detects at least one position of the free pistons by means of at least one position sensor assigned to them.

As an alternative to this, an advantageous solution provides that the slide drive is caused by a pressure difference between an expander inlet and a

Expander output is controllable.

The slide drive is preferably designed as a double-acting actuating cylinder, the piston of which is acted upon on the one hand by the pressure at the expander inlet and on the other hand by the pressure at the expander outlet.

To control such a drive unit, it is expediently provided that the slide drive can be controlled by a control slide, which controls the application of pressure to the piston at the expander inlet on the one hand and at the expander outlet on the other hand.

The control slide is preferably designed such that it detects the positions of the free pistons and moves accordingly.

In particular, it is provided that the control slide can be moved by the free pistons.

In order to be able to deliver the expansion unit according to the invention preferably as a single, fully assembled unit and to install it in a refrigerant circuit, it is preferably provided that the expansion unit has one

Has device base on which the supercooling unit and the expansion compression unit is arranged.

Furthermore, it is favorable if the control unit is also arranged on the device base. In addition, it is advantageous for the installation if a high-pressure inlet connection and an expansion pressure outlet connection are arranged on the device base.

Furthermore, it is provided in an advantageous solution that at the

A high-pressure outlet connection is arranged over the device base, via which the compressed supercooling mass flow flows out when the expansion unit is installed.

A further advantageous solution provides that heat exchanger connection units are provided on the base of the device, by means of which several heat exchangers on the high-pressure side can be connected.

In particular, each of the heat exchanger connection units is designed such that it each has a three-way valve and a bypass for the respective heat exchanger, so that the three-way valve enables the flow through the respective heat exchanger to be controlled.

In particular, it is provided that at least one of the heat exchanger connection units is connected to a heat exchanger on the high-pressure side that emits heat to the ambient air.

In principle, it is conceivable within the framework of the solution described so far to operate the cooling stage without its own expansion element and to work in the cooling stage with the mass flow expanded by the expansion unit.

In this case, it is useful if following the cooling level

Phase separator is arranged, the gas phase of which is fed from a suction pressure line to the refrigerant compressor. Such a phase separator has the advantage that it prevents liquid refrigerant from being supplied to the refrigerant compressor for compression.

Another advantageous solution provides that the cooling stage has at least one expansion element, so that it is possible to use it to determine the pressure desired in the cooling stage.

Further features and advantages of the invention are the subject of the following description and the drawing of some

Embodiments.

The drawing shows:

Figure 1 is a schematic representation of a first embodiment of a refrigerant circuit according to the invention with a first embodiment of an expansion unit according to the invention with a first embodiment of an emergency operating unit.

2 shows an enlarged schematic illustration of the first exemplary embodiment of an expansion unit according to the invention with the first embodiment of an emergency operating unit;

3 shows a schematic illustration of a first exemplary embodiment of an expansion compression unit according to the invention;

Fig. 4 is a schematic representation similar to Fig. 3 of a second

Embodiment of an expansion compression unit according to the invention;

5 shows a schematic illustration of a second exemplary embodiment of the refrigerant circuit according to the invention with a second embodiment of an emergency operating unit; 6 shows a schematic illustration of the first exemplary embodiment of the expansion unit with a third embodiment of an emergency operating unit;

Fig. 7 is a schematic representation of the first embodiment of the

Expansion unit with a fourth embodiment of an emergency operating unit;

Fig. 8 is a schematic representation of the first embodiment of the

Expansion unit with a fifth embodiment of an emergency operating unit;

9 shows a schematic illustration of a second exemplary embodiment of an expansion unit according to the invention with a sixth embodiment of an emergency operating unit;

10 shows a schematic illustration of a third exemplary embodiment of an expansion unit according to the invention with the sixth embodiment of the emergency operating unit;

Fig. 11 is a schematic representation of the first embodiment of the

Expansion unit with a seventh embodiment of an emergency operating unit in a first position of a 3/2 way valve;

12 shows a schematic illustration of the first exemplary embodiment of an expansion unit with the seventh embodiment of an emergency operating unit in a second position of the 3/2-way valve;

13 shows a schematic illustration of a fourth exemplary embodiment of an expansion unit; 14 shows a schematic illustration of a third exemplary embodiment of a refrigerant circuit according to the invention;

15 shows a schematic illustration of a fourth exemplary embodiment of a refrigerant circuit according to the invention and

16 shows a schematic illustration of a fifth exemplary embodiment of a refrigerant circuit according to the invention.

A first exemplary embodiment of a refrigeration system according to the invention, shown in FIG. 1, comprises a refrigerant circuit, designated as a whole by 10, in which a refrigerant compressor unit, designated as a whole by 12, is arranged, for example at least one

Refrigerant compressor includes.

The refrigerant compressor unit 12 has a suction port 14 and a pressure port 16, with refrigerant compressed to high pressure PHI usually being present at the pressure port 16.

The term “refrigerant compressed to high pressure” is understood to mean that the refrigerant has the highest pressure present in the refrigerant circuit.

A high-pressure line 18 leads from the pressure connection 16 a compressor mass flow V compressed by the refrigerant compressor unit 12 to high pressure PHI to an inlet 24 of a heat-emitting heat exchanger on the high-pressure side, designated as a whole by 22, which

emits heat in particular to the ambient air and thus cools the refrigerant, so that at an outlet 26 of the high-pressure side heat exchanger 22 there is a total mass flow G of refrigerant cooled by the high-pressure side heat exchanger 22, that of a refrigerant at a high pressure PH2, which is slightly lower than the high pressure PHI due to the heat exchanger 22, leading high-pressure line 28 is fed to a high-pressure regulating expansion unit 32, designated as a whole by 32, which has a high-pressure inlet connection 34 connected to the high-pressure line 28, an expansion pressure outlet connection 36 and one High pressure outlet connection 38 has.

The expansion pressure outlet connection 36, which is at an expansion pressure PE, is connected to an expansion line 42, which in the simplest exemplary embodiment shown in FIG. 1 leads to a cooling stage 62, which in the simplest case has a heat exchanger 64 that absorbs heat for cooling.

In this simplified exemplary embodiment, the heat-absorbing heat exchanger 64 is at the expansion pressure PE, so that no separate expansion valve is connected upstream of this heat exchanger 64.

In order to protect the refrigerant compressor unit 12, the heat-absorbing heat exchanger 64 is followed by a phase separator 72, which is arranged in a suction pressure line 74 and leads from the cooling stage 62 to the suction connection 14 of the refrigerant compressor unit 12 and prevents liquid refrigerant from the refrigerant compressor unit 12 at the suction connection 14 is sucked in.

One therefore flows from the expansion pressure outlet connection 36

Expansion pressure PE is the expansion pressure mass flow EPM through the expansion line 42 to the cooling stage 62 and from the cooling stage 62 in turn via the suction pressure line 74 to the refrigerant compressor unit 12. In this case, the expansion pressure mass flow EPM does not correspond to the total mass flow, but the expansion unit 32 divides the total mass flow G into an expansion mass flow EM and a subcooling mass flow UM, which is generated by the expansion unit 32 at the high pressure outlet connection 38 at a return pressure PR as a subcooling return mass flow URM is returned to a return line 78 and is fed from the latter to the compressor mass flow V before it enters the heat-emitting high-pressure side heat exchanger 22.

The refrigerant circuits 10 according to the invention, which are described below, are all preferably for carbon dioxide, that is to say CO2, or

Ammonia designed so that a transcritical cycle is usually present under common ambient conditions, in which cooling of the refrigerant to a temperature that is above the thaw takes place only before the expansion of the refrigerant by the expansion unit 32, for example by means of the heat exchanger 22. and boiling line or saturation curve isotherms, so that none

Liquefaction of the refrigerant is present.

Only in the case of very low temperatures for cooling the heat-emitting heat exchanger on the high-pressure side is it possible to carry out a subcritical cycle, so that in this case a

Condensation of the refrigerant takes place at a temperature that passes through the refrigerant's thawing and boiling line or saturation curve

Corresponds to isotherms. The first embodiment of the designed according to the invention

Expansion unit 32 comprises, as shown enlarged in FIG. 2, a

Expansion system 30, which has a device base designated as a whole by 82, on which the high-pressure inlet connection 34 of the

Expansion pressure outlet port 36 and the high pressure outlet port 38 are arranged.

Furthermore, in the expansion system 30, an expansion compression unit 84 is connected to the device base 82, which comprises an expander stage 86 and a compressor stage 88, which are integrated in the expansion compression unit 84 and are rigidly coupled to one another.

The expansion compression unit 84 comprises an expander inlet 92 and an expander outlet 94, which is connected to the expansion pressure outlet connection 36, as well as a compressor inlet 96 and a compressor outlet 98, which in turn is connected to the high pressure outlet connection 38.

Furthermore, in the expansion system 30, a subcooling unit 102 is arranged on the device base 82, which in the first exemplary embodiment is designed as a countercurrent heat exchanger and has an input 104 and an output 106 for the mass flow to be cooled, in particular in this case the total mass flow G, and an input 112 and an output 114 for the subcooling mass flow UM which is conducted through the heat exchanger as a countercurrent.

In the expansion system 30, the subcooling mass flow UM is branched off at a branch 116 from the total mass flow G emerging and supercooled at the output 106 of the subcooling unit 102, so that an expansion mass flow EM is led from the branch 116 through a feed line to the expander inlet 92 and the subcooling mass flow UM through Shut-off device 124 and one with an actuator 123 driven expansion element 122 is guided in the feed line 126, in which the supercooling mass flow UM is expanded to a pressure PU, and is then fed to the input 112 of the subcooling unit 102, the subcooling mass flow UM in the subcooling unit 102 in counterflow from the input 104 to the output 106 flowing total mass flow G subcooled and from the outlet 114 by means of a

Connection line 128 is supplied to the compressor input 96.

The mechanical energy released in the expander stage 86 by expansion of the expansion mass flow EM is fed directly to the compressor stage 88 in the expansion compression unit 84 by a mechanical functional coupling, and in this leads to a compression of the supercooling mass flow UM from an inlet pressure EP of the compressor stage 88 to a return high pressure PR, which corresponds to or is higher than the pressure level PHI in the high pressure line 18, so that the subcooling return mass flow URM can be supplied from the high pressure outlet connection 38 to the compressor mass flow V via a high pressure return line 78.

Furthermore, a controller 132 is also provided in the expansion system 30, which, on the one hand, detects the temperature of the mass flow of the refrigerant before its expansion in the expansion stage 86, for example with a sensor 134, which is in particular a temperature sensor and, for example, corresponding to this temperature by means of the actuator 123 Expansion organ 122 controls.

For this purpose, sensor 134 is arranged, for example, between branch 116 and expander 86 as sensor 134i.

Furthermore, the controller is assigned a sensor 135 with which it is able to detect the inlet pressure EP. Alternatively or in addition to this, however, the sensor 134 can also be used as a sensor 1342 between the high-pressure input connection 34 and the supercooling unit 102.

As an alternative or in addition, it is provided in particular that the sensor 134, as the sensor 134 _3, measures the ambient temperature, which in particular decisively influences the temperature of the total mass flow G of the refrigerant at the outlet 26 of the heat exchanger 22 through the ambient air flowing through the heat exchanger 22.

The controller 132 can operate autonomously, for example, so that the controller is part of the expansion system 30 which is installed as an independent unit in the refrigerant circuit.

However, it is also provided that the controller 132 is coupled to an external controller 138 which, as shown in FIG. 1, as an alternative or in addition to the sensors 134, the temperature of the total mass flow G in the high-pressure section 28 and / or the temperature or Pressure in the refrigerant compressor 12 is detected in order to control the actuator 123 directly or indirectly or by means of the control 132.

The expansion element 122 serves to control the supercooling mass flow UM, and thereby the high pressure PH2 at the high pressure input connection 34 and thus also the high pressure PH2 in the high pressure line 28 in accordance with one of the controls 132 and / or the external controller 138, in particular in this one as a file or algorithm

stored relationship as a function of the respectively measured temperature of the refrigerant and thus as a function of the possibilities for cooling the refrigerant on the high pressure PH2, for example as a function of that for cooling in the heat exchanger 22

existing ambient temperature to regulate. The controller 132 and / or the external controller 138 comprise, for example, a processor and a memory in which an algorithm or a

Correlation tables are stored, by means of which a correlation between the settings of the expansion element 122 and the measured ones

Temperatures is stored, so that the settings of the expansion element 122, made by the actuator 123 controlled by the control 132, lead to the high-pressure inlet connection 34 and / or the inlet 104 of the supercooling unit 102 and / or

Expander inlet 92 which sets the high pressure PH2 corresponding to the temperature.

It is possible to regulate the high pressure PH2 by controlling the supercooling mass flow UM, since the mechanical functional coupling of the expander 86 to the compressor stage 88 correlates the expansion mass flow EM directly with the supercooling mass flow UM in accordance with a fixed volume ratio, so that by specifying the Supercooling mass flow UM the expansion mass flow EM can be specified. The subcooling mass flow UM usually comprises approximately 15% to 35% of the total mass flow G, so that the expansion mass flow EM comprises approximately 85% to 65% of the total mass flow G.

In particular, the regulation of the high pressure PH2 takes place in such a way that in the subcooling unit 102 the temperature of the total mass flow G on the hot side, ie at the inlet 104, is only a few Kelvin, for example less than 4 Kelvin, better still less than 3 Kelvin, in particular one up to two Kelvin, above the temperature of the subcooling mass flow UM at the outlet 114 of the subcooling unit 102, in order to substantially completely evaporate the refrigerant in the subcooling mass flow U.

In order to be able to reliably monitor the temperature of the supercooling mass flow UM at the output 114, a sensor connected to the controller 132 is in particular still provided in the connecting line 128. However, it is also possible to detect the input pressure EP by means of the sensor 135 with the control 132 and / or 138 and to regulate it to a suitable value corresponding to the sizes such as pressure and / or temperature of the total mass flow G and the size of the input pressure EP , the suitable values for the quantities mentioned being stored, for example, in the controller 132 and / or 138.

Due to the arrangement of the control 132, the expansion element 122, the subcooling unit 102 and the expansion compression unit 84 on the device base 82, this overall forms a unit that can be installed independently in the cooling circuit 10 and that is present by regulating the high pressure PH2 on the output side of the heat-emitting heat exchanger 22 , which controls the operating states of the refrigerant circuit 10.

As shown in FIG. 3, the expansion compression unit, designated as a whole by 84, is designed as a free-piston machine, which has a cylinder housing 142 in which two piston chambers 144 and 146, which are separate from one another, are arranged, with a movable free piston in each piston chamber 152, 154 is arranged.

The free pistons 152 and 154 divide the respective piston chambers 144 and 146 into expansion chambers 162 and 164 and compression chambers 166 and 168.

Furthermore, the free pistons 152 and 154 are preferably mechanically coupled to one another, in such a way that, at the maximum volume of the first expansion chamber 162, the first piston 152 is positioned such that the first compression chamber 166 has a minimum volume and at the same time the second free chamber piston 154 is such that its expansion chamber 164 has a minimum volume, while the compression chamber 168 has the maximum volume or vice versa. Thus, for example, an increase in volume of the first expansion chamber 162, when it is acted upon by the high pressure at the expander inlet 92, leads to a compression of refrigerant of the supercooling mass flow U in the first compression chamber 166, at the same time to an expulsion of the refrigerant in the second compression chamber 168 in the direction of the expander outlet 94 and for drawing in refrigerant in the second compression chamber 168 via the compressor inlet 96.

Conversely, an action on the second expansion chamber 164 by means of high-pressure refrigerant supplied via the expander inlet 92 compresses the refrigerant in the second compression chamber 168 and thus pushes it out to the compressor outlet 98, while at the same time pushing out the refrigerant in the first Expansion chamber 162 takes place in the direction of the expander outlet 94 and refrigerant is sucked into the first compression chamber 166 via the compressor inlet 96.

The first free piston 152 and the second free piston 154 are preferably arranged coaxially to one another and move in piston chambers 144 and 146 which are likewise arranged coaxially to one another and are separated from one another by a separating body 148, the separating body 148 being sealed by a coupling element 172 which penetrates the

Movement of the two free pistons 152 and 154 couples.

In the simplest case, the coupling element 172 can be designed as a coupling rod which penetrates the separating body 158 and which moves with the free pistons 152, 154 and which is in free contact with the free pistons 152 and 154, that is to say is not firmly connected to them. Characterized in that when refrigerant flows in via the expander inlet 92, the pressure in this expansion chamber 162 or 164 acts on the respective free piston 152 or 154 and at the same time a pressure which is higher in the respective compression chamber 168 or 166 of the other free piston 154 or 152 acts As the pressure at the expander outlet 94 which is present in the respective expansion chamber 164 or 162, a pressure which is higher than that at the expander inlet 92 can be generated in the compression chamber 166 or 168 acted upon by the free piston 152 or 154 applied high pressure, so that the supercooling mass flow U can be compressed to a pressure present at the compressor outlet 98 which corresponds at least to the high pressure PHI at the inlet 24 of the heat-emitting heat exchanger or the pressure in the high pressure line 18, although the high pressure PH2, the expander inlet to Is available due to pressure losses in the heat exchanger 22 is slightly smaller than the high pressure PHI.

To connect the compression chambers 166 and 168 with the

Compressor inlet 96 are from compressor inlet 96

Supply lines 182 are provided which lead to the inlet valves 184 and 186 assigned to the compression chambers 166 and 168, and the compressor outlet 98 is also connected to a pressure line 192 which leads from the outlet valves 194 and 196 assigned to the compression chambers 166 and 168 to the compressor outlet 98.

An alternating connection between the expander inlet 92 and the expander outlet 94 with the expansion chambers 162 and 164 takes place via a slide system 202 which is controlled by the piston position. For example, the slide system 202 comprises a controller 203, which detects the positions of the free pistons 152 and 154 by means of position sensors 204 and 206 and controls an exchangeable slide, designated as a whole by 208, which has two slide positions and one in the slide position by means of an electric drive 207 Expander inlet 92 with the expansion chamber 162 and the expander outlet 94 with the

Expansion chamber 164 and in the other slide position connects the expander inlet to the expansion chamber 164 and the expander outlet 94 to the expansion chamber 162.

As an alternative to this, as shown in FIG. 4, a pressure control of the change-over slide 208 is provided in a slide system 202 ', the drive 207' having a pressure-driven cylinder with a piston 205, which, controlled by an auxiliary slide 209, alternately on the one hand with the pressure at the expander inlet 92 and, on the other hand, the pressure at the expander outlet 94 or vice versa is applied, the auxiliary slide 209 also being designed as a change-over slide and its slide positions being achieved by mechanical detection of the positions of the free pistons 152 and 154 in their end positions facing the separating body 148.

Since, for example, when the expansion compression unit 84 is configured as a free-piston machine, malfunctions thereof can occur, so that no expansion pressure mass flow EPM or a sufficiently large expansion pressure mass flow EPM would be available for the cooling unit 62, cooling capacity would no longer be available on the cooling unit 62, so that Refrigerant circuit 10 would no longer be functional.

In addition, the high pressure PHI and PH2 would rise to a level that would damage the heat exchanger 22 and / or the refrigerant compressor 12. For this reason, the refrigerant circuit 10 is provided with an emergency operating unit 230, which prevents this case.

A first embodiment of an emergency operating unit 230 provided in the expansion system 30 comprises, for example, an additional expansion element 232 which is arranged in a bypass line 234, which in turn is connected in parallel to the expander stage 86, in particular between its expander input 92 and expander output 94, and is designed as a pressure relief valve, which in turn opens when a predeterminable opening pressure PO is exceeded and then acts as an expansion element in the bypass line 234, so that an emergency operation expansion mass flow NEPM is fed to the expansion line 42 through the expansion element in the bypass line 234, which then is supplied in the cooling unit 62 Can absorb heat, so that the refrigerant circuit 10 can continue to run in emergency operation (Fig. 1 and Fig. 2).

The emergency operating expansion mass flow NEPM is selected such that a minimum cooling capacity is available on the cooling unit 62.

In particular when using the free piston machine as expansion compression unit 84, there is the problem of pulsations in the refrigerant circuit 10.

For this reason, in the first exemplary embodiment of the refrigerant circuit 10, parts of the refrigerant circuit 10 adjacent to the expander stage 86, for example to the expansion line 42, are preferably one

Pulsation damper 260 connected, which comprises a damper housing 262 enclosing a damper chamber 264, in which a bladder 266 is formed at least in a subcritical operating state

forms gaseous refrigerant above a refrigerant bath 268 from liquid refrigerant, the refrigerant bath 268 being connected to the expansion line 42, for example, via a pulsation transmission line 272. The bubble 264 made of gaseous refrigerant thus makes it possible to dampen pulsations in the expansion pressure mass flow EPM, which also affect the bath 268 of the refrigerant.

In order to ensure that the bladder 266 made of gaseous refrigerant always forms in the damper housing 262 above the coolant bath 268 made of liquid refrigerant, the damper housing 262 is preferably provided in the region of the region surrounding the bladder 266 with a heater 274 which is provided via a heat transport circuit 276 supplies heat from return line 78 to damper housing 262 to maintain bladder 266 of vaporous refrigerant.

In a second exemplary embodiment of a refrigerant circuit 10 ′ according to the invention, shown in FIG. 5, a second embodiment of the

Emergency operating unit 230 'is not part of the expansion system 30, as in the

Described in connection with the first embodiment of the refrigerant circuit 10 according to the invention, but a unit independent of the expansion system 30, wherein the expansion element 232 designed as a pressure relief valve is arranged in the bypass line 234 ', which in this case connects the high pressure line 28 to the expansion line 42 and thus the entire expansion unit 32 is connected in parallel (Fig. 5).

In the first exemplary embodiment of a refrigerant circuit according to the invention, the first exemplary embodiment of the expansion unit 30 is assigned a third embodiment of an emergency operating unit 230 ", which is designed such that the expansion element 232 is arranged in a bypass line 234", which is the expander stage 86 and one in front of the expander - Input 92 arranged shut-off element 236 is connected in parallel, so that when the expansion element 232 is opened, there is the possibility, through the shut-off valve 236, of decommissioning the expander stage 86 and thus the entire expansion compression unit 84, so that only the emergency operating expansion mass flow NEPM flows from the high-pressure inlet connection 34 to the expansion pressure outlet connection 36.

Because the expander stage 86 is taken out of operation by the shut-off element 236, the compressor stage 88 is also out of operation, so that no supercooling return mass flow URM flows to the high-pressure line 18 via the high-pressure outlet connection 38 and the return line 78.

In this embodiment, it is necessary to actively control the expansion element 232 and the shut-off element 236, for example by means of an emergency operation control 238, which by means of a sensor 242 detects the in the

Refrigerant circuit 10 upstream of the expander stage 86 high pressure PH2, for example, detects the high pressure between the outlet 106 of the supercooling unit 102 and the expander inlet 92 (FIG. 6).

In a fourth embodiment of an emergency operating unit 230 ″, shown in FIG. 7, the shut-off element 236 is not arranged in front of the expander inlet 92, but immediately after the expander outlet 94, and the bypass line 234 ″ is thus the expander stage 86 with the shut-off element 236, which is arranged following the expander output 94, connected in parallel.

In this case too, the controller 238 is provided on the one hand to control the expansion element 232 and the shut-off element 236.

In a fifth embodiment of an emergency operating unit 230 '", shown in FIG. 8, the emergency operating unit 230""comprises the expansion element 237 and the shut-off element 236. This embodiment is the same as the third

Embodiment, the shut-off element 236 arranged in front of the expander inlet 92 to by interrupting the in the expander 86

inflowing expansion mass flow EM the expander stage 86 out of operation, while the bypass line 234 "" the supply line 126, into which the supercooling mass flow UM flows through the

Expansion member 122 enters, and connects the expansion pressure outlet port 36 together.

In this case, there is another one in the bypass line 234 ""

Shut-off element 237 is provided, while the expansion member 122 provided for the expansion of the subcooling mass flow UM also serves as the expansion member for the emergency operating unit 230 "" and therefore the

Emergency expansion mass flow NEPM determined, bypassing the

Expanders 86 is guided to the expansion pressure outlet connection 36.

In this case, too, the emergency operation control 238 is required, which controls the shut-off elements 236 and 237 when the sensor 242 is on

undesirable increase in high pressure PH2 is detected.

In a sixth embodiment of an emergency operating unit 230 "" assigned to a second exemplary embodiment of an expansion unit 32 ', shown in FIG. 9, the emergency expansion unit 230. is likewise formed by the bypass line 234. With the shut-off element 237, while the shut-off element 236 connects directly to the expander outlet 94 is arranged in such a way that the bypass line 234 is led from the supply line 126 to the expansion pressure outlet connection 36 and opens into a bypass line between the shut-off element 236 and the expansion pressure outlet connection 36. In this second exemplary embodiment of the expansion unit 32 ′, the bypass line 272 also leads into this bypass line, which leads to a pulsation damper 260, which is designed in the same way as described in connection with the first exemplary embodiment, in which case the heat transport circuit 276 likewise Is part of the expansion system 30 and extracts heat from a bypass line between the compressor outlet 98 and the high pressure outlet connection 38 and supplies it to the heater 274.

In a third embodiment, shown in FIG. 10, this is

Expansion system 30 with the emergency operating unit 230. according to the sixth

Embodiment provided, so that in this regard, reference can be made in full to the statements on the sixth embodiment.

In contrast to the first exemplary embodiment, a pulsation damper unit 280 is provided between the high-pressure input connection 34 and the high-pressure output connection 38, which has a damper housing 282, in which a piston 284 is arranged, which has a piston

Damper housing 282 separates arranged first chamber 286 from a second chamber 288, wherein for example the first chamber 282 is connected to the high pressure input connection 34 via a first pulsation transmission line 292 and the second chamber 288 is connected to the high pressure output connection 38 via a second pulsation transmission line 294.

The pulsation damper unit 280 is thus able to dampen pulsations propagating to the high-pressure inlet connection 34 or to the high-pressure outlet connection 38 in that the piston transmits pulsation, the piston 284 preferably being mounted between two spring-elastic damping elements 296 and 298 is that in the

Chambers 286 and 288 are arranged. An eighth embodiment of an emergency operating unit 230 shown in FIG

FIGS. 11 and 12 are based in principle on the fifth embodiment of the

Emergency operating unit 230 "", in which case the emergency operating unit 230. has a bypass line 234. which leads from the supply line 126 to a

3/2 directional valve 235 leads, which is able either to connect the expander outlet 94 to the expansion pressure outlet connection 36 and to close the bypass line 234. or the bypass line

234. to connect to the expansion pressure outlet port 36 and the

To close the expander outlet 94, the 3/2 way valve 235 also being controlled by the controller 238, which detects, for example, the high pressure of the expansion mass flow EM before it enters the expander.

In this embodiment too, the expansion element 122, which is actually intended for the expansion of the supercooling mass flow UM, serves as an expansion element for the emergency operation unit 230 in the case of emergency operation.

In a fourth exemplary embodiment of an expansion unit 32 ″ shown in FIG. 13, the expansion unit 32 ″ is modified in such a way that the branch 116 ′ is arranged between the high-pressure inlet connection 34 and the inlet 104 of the supercooling unit 102 and thus the subcooling mass flow UM Flow through the supercooling unit 102 is branched off by the total mass flow G, the shut-off member 124 and the expansion member 122 being provided in the same way as in the previous exemplary embodiments, which are arranged between the branch 116 '"and the inlet 112 for the countercurrent flowing through the subcooling unit 102 ,

This embodiment of the expansion unit 32 '"is also by the

Controller 132 is controlled in the same way as in the first embodiment. This fourth exemplary embodiment can also be used with emergency operating units, for example with an emergency operating unit 230 according to the first

Embodiment, and the expansion element 232, formed as

Pressure relief valve, provided.

The expansion unit 32 '"can also be used with emergency operating units 230',

230 ", 230" ', 230 "", 230th, 230th and 230th and / or also provided with pulsation damper units 260, 280, as described in connection with the above exemplary embodiments of the refrigerant circuit 10, so that in this regard reference is made to the above explanations regarding these emergency operating units.

In a third exemplary embodiment of a refrigerant circuit 10 ″ according to the invention, shown in FIG. 14, those elements which are identical to those of the first exemplary embodiment are provided with the same reference numerals, so that the description of the entire content is based on the

Comments on these in connection with the first exemplary embodiment can be referenced.

However, the third exemplary embodiment is provided with the third embodiment of the emergency operating unit 230 ″, with respect to which reference is made to the previous explanations regarding this third embodiment.

In contrast to the first embodiment, the third leads

In the exemplary embodiment, the expansion line 42 does not go directly to the cooling stage 62, but to an intermediate pressure collector 44, in which a bath 46 of liquid refrigerant is formed at expansion pressure PE, from which liquid refrigerant is supplied to the cooling stage 62 ″ via a liquid line 48, which in FIG in this case not only includes the heat-absorbing heat exchanger 64, but also a shutdown element 68 and an expansion element 66. Furthermore, a gas volume 52 of refrigerant is formed in the intermediate pressure collector 44 above the bath 46, from which an additional mass flow Z is fed to the suction line 74 via an expansion element 54.

Through the intermediate pressure collector 44 there is the possibility of the

Expansion mass flow E at expansion pressure PE into a main mass flow H, which is supplied via the liquid line to the cooling stage 62 ″, and a gaseous additional mass flow Z, which is supplied via the expansion member 54 to the suction pressure line 74, so that the temperature of the cooling stage 62 "reaching main mass flow H by means of

Expansion device 54 is adjustable.

In the third exemplary embodiment, a pulsation damper 260 is also assigned to the high-pressure lead 28, which corresponds to the pulsation damper 260 shown in the first exemplary embodiment of the refrigerant circuit 10 according to FIG. 1 and assigned to the expansion line 42, so that the function of the same is fully explained in the foregoing this can be referred to.

Alternatively, the pulsation damper 260 can also be in the area of the

Expansion unit 32 arranged or even integrated into the expansion system 30.

In a fourth exemplary embodiment of a refrigerant circuit 10 '' according to the invention, shown in FIG. 15, which are identical to those of the first and second exemplary embodiments, are provided with the same reference numerals, so that the description of the same applies to the contents of the same

Comments on the first and second exemplary embodiments can be referred to. In addition to the features of the second exemplary embodiment, the fourth exemplary embodiment is provided with the pulsation damper unit 280, which in this exemplary embodiment is connected in parallel with the heat exchanger 22 and thus dampens pulsations between the high-pressure line 18 and the high-pressure discharge line 28.

The pulsation damper unit 280 is of identical design to that integrated into the third exemplary embodiment of the expansion unit 32 ″

Pulsation damper unit 280 (FIG. 10), so that full reference can be made to the above statements in this regard.

In addition, however, a throttle 302 is also provided between the second pulsation transmission line 294 and the high-pressure line 18 in order to obtain an improved damping effect.

In a fifth exemplary embodiment of a refrigerant circuit 10 ″ according to the invention, shown in FIG. 16, those elements which are identical to those of the first and second exemplary embodiments are provided with the same reference numerals, so that with regard to the description thereof the content of the explanations is the same reference can be made to the first and second exemplary embodiments.

In contrast to the second exemplary embodiment, the additional mass flow Z from the gas volume 52 is not fed directly to the suction pressure line 74 via the expansion element 54, but again through an in the

Provided liquid line 48 subcooler 58, which subcooled the main mass flow H flowing in the liquid line 48 again.

Furthermore, the cooling stage 62 ″ is designed, for example, as a normal cooling stage and, in addition, a deep-freezing stage 212 is also provided, which has a heat-absorbing heat exchanger 214 and a shutdown element 218 and an expansion element 216. The refrigerant expanded in the freezer stage 212 is fed via a suction pressure line 224 to a freezer compressor unit 222, which compresses the refrigerant to such an extent that it can be fed to the suction pressure line 74 for the refrigerant compressor unit 12 for compression to high pressure.

In addition, a subcooler 226 is preferably also provided in the suction pressure line 224 of the freezer compressor unit 212, which subcooles the refrigerant supplied via the liquid line 48 to the freezer stage 212 again before it enters the freezer stage 212, specifically by means of the exiting from the freezer stage 212 and Expanded refrigerants carried in the suction pressure line 224.

In connection with the third, fourth and fifth exemplary embodiment according to FIGS. 14, 15 and 16 of the solution according to the invention, the presence of the intermediate pressure collector 44 was described and also the supply of the additional mass flow Z via the expansion element 54 to the suction pressure line 74 and the regulation of the temperature of the main masses - current H.

This regulation of the temperature of the main mass flow H comprises the regulation of an intermediate pressure PM in the intermediate pressure collector 44 by means of the expansion element 54, which in this case can be controlled via an intermediate pressure control 55.

In principle, in the third, fourth and fifth exemplary embodiment according to FIGS. 14, 15 and 16 it would be possible, on the one hand, for the high pressure PH2 in the high-pressure discharge line to be operated by means of the controls 132 and / or 138 in accordance with an optimal operation of the expansion unit 32 with the respective one To control the temperature of the refrigerant in the high-pressure line 28 and, for example, the respective outside temperature, and to use the intermediate pressure controller 55 to merely define a constant intermediate pressure PM in the intermediate pressure collector 44.

The increase in efficiency of the refrigerant circuit can be achieved by the above-mentioned detection of the inlet pressure EP of the compressor stage 88 by means of the controls 132, 138.

However, the refrigerant circuit 10 according to the invention can also be operated with regard to the achievable COP, that is to say the ratio of cooling power to the mechanical power used, in particular in summer, and with regard to the expansion of the functional operation of the

Optimize the expansion compression unit, particularly in winter operation, so that an additional operating condition-related regulation of the intermediate pressure PM takes place, which affects the inlet pressure EP of the compressor stage 88 on the basis of the volume ratios of the expansion compression unit 84.

In this operating state-related regulation of the intermediate pressure PM, the intermediate pressure PM is regulated, for example, by means of the intermediate pressure controller 55 and the expansion element 54 to a pressure value which, on the one hand, results from a basic value, which is generally defined once, and supplementary values for this basic value which vary depending on the operating state.

For example, the basic value for CO2 as a refrigerant is in the range of 30 bar to 45 bar, so that a value from this range, for example 35 bar, is specified as the basic value, and the additional values for CO2 as refrigerant are in the range of 0 , 5 bar to 7 bar. The surcharge values could in principle be fixed values from the range of surcharge values provided for them, but it is particularly favorable if the surcharge values vary within this range due to the operating state.

In addition, there is preferably a differentiation between summer operation and winter operation, the additional values having positive values in summer operation and negative values in winter operation, so that the values for CO2 as refrigerant in summer operation are in the range from 0.5 bar to 7 bar and at Winter operation is in the range of -0.5 bar to -7 bar.

It is particularly advantageous if the size of the additional values are dependent on the values lying in the control range of the high pressure PH2 and therefore vary depending on the values of the high pressure PH2.

In particular, it is provided that the additional values are higher for high values of the high pressure than for low values of the high pressure.

For example, in the case of CO2 as a refrigerant during summer operation, there are additional values in the range from +0.5 bar to +3 bar, provided the high pressure PH2 has values in the range from 75 bar to 80 bar, and additional values in the range from +3 bar to +7 bar, provided the high pressure PH2 has values in the range greater than 80 bar, preferably values greater than 80 bar to 120 bar.

For example, in summer operation an additional value in the range of 3 bar is used for a high pressure PH2 in the range of 80 bar, while an additional value in the range of 5 bar is used for high pressure PH2 in the range of 90 bar. In the same way, the additional values for winter operation are, for example, in the range from -0.5 bar to -3 bar, provided the high pressure PH2 is in the range from 55 bar to 65 bar and the additional values are in the range from -3 bar to -5 bar, provided the high pressure PH2 is below 50 bar to 40 bar.

In winter operation, in particular, an additional value in the range of -3 bar is used for a high pressure PH2 in the range of 60 bar and an additional value in the range of -5 bar is used for high pressure in the range of 50 bar.

In the examples of summer operation and winter operation mentioned above, the basic value is preferably always the same.

The above control of the intermediate pressure PM thus has the following consequences in summary:

By changing the intermediate pressure PM, the inlet pressure EP changes at the compressor stage 88 and thus a subcooler output of the subcooling unit 102.

If the intermediate pressure PM is increased, the inlet pressure EP at the compressor stage 88 increases and thus the subcooling mass flow UM and thus the subcooling power of the subcooling unit 102 are increased, so that the COP also increases.

If the intermediate pressure PM is reduced, the inlet pressure EP at the compressor stage 88 also drops. However, the pressure difference at the expander stage 86 is increased and thus the functional range of the expansion compression unit 84 is also increased. In an alternative solution according to FIG. 16 it is provided that the

Intermediate pressure control 55 detects the variables, in particular the temperature and / or the pressure of the total mass flow G in the high pressure discharge line 28 and the variable of the inlet pressure EP of the compressor stage 88, and controls the intermediate pressure PM as a function thereof in order to adjust to a predefined and suitable one for the detected variables, for example in the

Intermediate pressure controller 55 to regulate stored value of the input pressure EP.

All compressor units can be any compressor or combination of compressors (parallel, in series, multi-stage).

Likewise, one or more of the compressors can be provided with a power control, which is carried out by switching off compressors, by mechanical power control (for example switching off, in particular cyclical switching off of parts (cylinder banks) of a compressor) or

Speed control of the compressor can be done.

Claims

PATENT CLAIMS

1. refrigerant circuit (10), comprising at least one refrigerant compressor (12), which compresses refrigerant supplied to a suction connection (14) to high pressure (PHI), so that at a pressure connection, a compressor mass flow compressed to high pressure (PHI) (V) of the refrigerant leaks,

at least one high-pressure heat-emitting heat exchanger (22) with an inlet (24) to which the refrigerant circuit (10) feeds the compressor mass flow (V) and with an outlet (26) from which a cooled total mass flow (G) of refrigerant emerges .

at least one expansion unit (32) comprising an expander (86) and a compressor stage (88)

Expansion compression unit (84), which carries an expansion mass flow (EM) of the refrigerant circuit (10) in the direction of the suction connection (14) of the refrigerant compressor (14)

Total mass flow (G) from high pressure (PH2) expanding to an expansion pressure (PE), and at least one cooling stage (62) with at least one heat-absorbing heat exchanger (64), which the refrigerant circuit (10) one of that of the

Expansion unit (32) expanded expansion pressure mass flow (EM) include main mass flow (H) supplies, and

which the refrigerant circuit (10) supplies to the suction connection (14) of the refrigerant compressor (12) after leaving the cooling stage (62), characterized in that the refrigerant circuit (10) is assigned an emergency operating unit (230), which is one of the

Expansion compression unit (84) comprises bypass line (234) and which is functionally assigned to at least one expansion element (232, 122) and that the emergency operating unit (230) in the event of a fault, in particular an expansion disturbance, the expansion compression unit (84) changes from an inactive state to an active state in which it expands the high-pressure refrigerant by means of the expansion element (232, 122) an emergency expansion mass flow (NEPM) to operate the cooling stage (62 ) which the bypass line (234) supplies to the refrigerant circuit (10) for forwarding to the cooling stage (62).

2. Refrigerant circuit according to claim 1, characterized in that the bypass line (234) of the emergency operating unit (230)

Emergency expansion mass flow (NEPM) of an expansion line (42) of the expansion pressure mass flow (EPM)

Refrigerant circuit (10) feeds directly or indirectly.

3. refrigerant circuit according to one of the preceding claims,

characterized in that the bypass line (234) the emergency expansion mass flow (NEPM) one in normal operation of the refrigerant circuit (10) that the expansion pressure (PE)

existing expansion pressure mass flow (EPM) leading line of the refrigerant circuit (10) supplies.

4. refrigerant circuit according to one of the preceding claims,

characterized in that the emergency operating unit (230) detects an expansion disturbance of the expansion compression unit (84).

5. Refrigerant circuit (10) according to any one of the preceding claims, characterized in that the emergency operating unit (230) a high pressure (PH2) of the total mass flow (G) emerging from the outlet (26) of the heat exchanger (22) or the expansion mass flow (EM ) before entering the expander (86).

6. Refrigerant circuit according to one of the preceding claims, characterized in that the emergency operating unit (230) has a pressure difference between the high pressure (PH2) of the total mass flow (G) or the expansion mass flow (EM) before it enters the expander (86) and one line section (42) of the refrigerant circuit (10) located at expansion pressure (PE).

7. Refrigerant circuit (10) according to any one of the preceding claims, characterized in that the emergency operating unit (230) detects a high pressure of the total mass flow (G) or the expansion mass flow (EM) before it enters the expander (86) with respect to its absolute value.

8. refrigerant circuit (10) according to any one of the preceding claims, characterized in that the emergency operating unit (230) the high pressure of the total mass flow (G) or the expansion mass flow (EM) before it enters the expander (86) with a

Compares reference high pressure.

9. refrigerant circuit according to one of the preceding claims,

characterized in that the emergency operating unit (230) has a controller (238) which transfers the emergency operating unit (230) from the inactive state to the active state.

10. refrigerant circuit according to one of the preceding claims,

characterized in that the emergency operating unit (230) comprises at least one switch-off element (235, 236, 237) for switching off the expansion compression unit (84).

11. Refrigerant circuit according to claim 10, characterized in that the shutdown element (235, 236, 237) of the emergency operating unit (230) either before an expander input (92) or after one

Expander outlet (94) is arranged.

12. refrigerant circuit according to one of the preceding claims,

characterized in that a switching element (235, 237) is provided in the bypass line (234) of the emergency operating unit (230) which provides a direct or indirect connection between a

Expansion device (122) for generating the supercooling mass flow (UM) of the expansion unit (32) and an expansion pressure outlet connection (36) of the expansion unit (32).

13. Refrigerant circuit according to claim 12, characterized in that the switching element can be controlled by the controller (238) of the emergency operating unit (230).

14. Refrigerant circuit according to claim 13, characterized in that the switching element is a switching valve.

15. The refrigerant circuit according to claim 12 or 13, characterized in that the switching element (235) is a 3/2 way valve, which connects either the bypass line (234) or an expander outlet to the expansion pressure outlet connection (36).

16. Refrigerant circuit according to the preamble of claim 1 or according to one of the preceding claims, characterized in that a pulsation damper unit (260, 280) is arranged in the refrigerant circuit (10).

17. The refrigerant circuit according to claim 16, characterized in that the pulsation damper unit (260) has a damper housing (262) surrounding a damper chamber (264), in which at least one gas bubble (266) is formed from refrigerant and that the gas bubble (266) has a pulsation transmission line (272) leading to a line (42, 28) of the refrigerant circuit (10)

Absorbs and dampens pulsations.

18. Refrigerant circuit according to claim 17, characterized in that the gas bubble (266) is above a refrigerant bath (268).

19. The refrigerant circuit according to claim 18, characterized in that the pulsation damper unit (260) for maintaining the gas bubble (266) from refrigerant is provided with a heater (274).

20. The refrigerant circuit according to claim 19, characterized in that the heating (274) is coupled to a heat transport circuit (276) which extracts heat in the refrigerant circuit (10) from compressed refrigerant in the region of high pressure (PHI).

21. The refrigerant circuit according to claim 16, characterized in that the pulsation damper unit (280) has a damper housing (282) with a piston (284) movable therein and two mutually opposite sides adjacent to the piston (284) and through the piston (204) from one another has separate chambers (286, 288) and that a gas bubble of refrigerant is formed in at least one of the chambers (286, 288).

22. Refrigerant circuit according to claim 21, characterized in that each of the chambers (286, 288) each by means of a pulsation transmission line (292, 294) with different flows of refrigerant lines (28, 78, 28, 18) of the refrigerant circuit (10) is connected.

23. The refrigerant circuit according to claim 22, characterized in that a pulsation transmission line (294) is connected to an input (24) of the heat-emitting heat exchanger (22) and the other pulsation transmission line (292) is connected to an output (26) of the heat-emitting heat exchanger (22) is.

24. Refrigerant circuit according to one of claims 21 to 23, characterized in that at least one pulsation transmission line (272, 292, 294) is coupled to the refrigerant circuit (10) via a throttle (302).

25. The refrigerant circuit according to the preamble of claim 1 or one of the preceding claims, characterized in that an intermediate pressure collector (44) is arranged between the expansion unit (32) and the cooling stage (62), in the bath (46) of which a liquid phase of the Collects refrigerant and in the gas volume (52) above the bath (46) a gas phase of the refrigerant collects.

26. Refrigerant circuit according to claim 25, characterized in that an additional mass flow (Z) is removed from the gas volume (52) of the intermediate pressure collector (44).

27. The refrigerant circuit according to claim 26, characterized in that the additional mass flow (Z) is supplied to the suction pressure line (74) via an expansion element (54).

28. Refrigerant circuit according to claim 27, characterized in that the additional mass flow (Z) expanded by the expansion element (54) cools a main mass flow (H) guided to the cooling stage (62) in a heat exchanger (58).

29. Refrigerant circuit according to one of claims 25 to 28, characterized

characterized in that an intermediate pressure control (55) which controls the expansion element (54) detects the pressure and / or the temperature of the total mass flow (G) in the high pressure discharge line (28) and the inlet pressure (EP) of the compressor stage (88) and the

Intermediate pressure (PM) controls in such a way that a predetermined value of the input pressure (EP), which is suitable for the detected variables, is set.

30. Refrigerant circuit according to one of claims 25 to 28, characterized

characterized in that an intermediate pressure (PM) in the intermediate pressure collector (44) is regulated to a pressure value which is derived from a basic value, for example a value in the range from 30 bar to 45 bar, and by means of an intermediate pressure control (55) which controls the expansion element (54) Additional values with amounts, for example in the range from 0.5 bar to 7 bar, are determined by the intermediate pressure controller (55).

31. The refrigerant circuit according to claim 30, characterized in that the additional values have positive values in summer operation and negative values in winter operation.

32. The refrigerant circuit according to claim 30 or 31, characterized in that the size of the additional values is dependent on the values of the high pressure which result when the high pressure is regulated.

33. The refrigerant circuit according to claim 32, characterized in that in summer operation the additional values are higher at high values of high pressure (PH2) than at low values of high pressure (PH2).

34. Refrigerant circuit according to claim 32 or 33, characterized in that in winter operation the additional values at high values of the high pressure (PH2) are smaller than at low values of the high pressure (PH2).

35. Refrigerant circuit according to the preamble of claim 1 or according to one of the preceding claims, characterized in that the expansion unit (32) comprises an expansion system (30) which has a supercooling unit (102) for subcooling the total mass flow of the expansion unit (32)

Refrigerant, the expansion compression unit (84) comprising the expander (86) and the compressor stage (88), a branch (116) which branches off from the total mass flow (G) supplied to the expansion unit (32) and a supercooling mass flow (UM) a supply line (126) is connected, which leads the subcooling mass flow (UM) to an input (112) of the subcooling unit (102), a in the

Has supply line (126) provided expansion member (122, 124), which expands the subcooling mass flow (UM) to a subcooling pressure (PU), and has a connecting line (128), which exits the subcooling mass flow (U) from the subcooling unit (102) to the compressor stage (88), which in turn compresses the supercooling mass flow (U) to a recirculation high pressure (PR) which corresponds to at least one high pressure (PHI) of the compressor mass flow (V) to which the subcooling mass flow (U) is supplied.

36. Refrigerant circuit according to the preamble of claim 1 or according to one of the preceding claims, characterized in that the refrigerant circuit (10) has an electrically operating control (132, 138), which has at least one of the following variables such as: an ambient temperature, a temperature of the

Expansion unit (32) and / or the expander stage (86) supplied mass flow of the refrigerant and an inlet pressure (EP) of the compressor stage (88), detected and one corresponding to this temperature and / or, if applicable, this inlet pressure (EP) of the compressor stage (88) Inlet pressure of the expansion unit (32) or the expander stage (84) and / or, if applicable, an inlet pressure (EP) of the compressor stage (88) by controlling the supercooling mass flow (UM) by means of the expansion member (122) which is electrically controlled by the controller (132, 138) ) sets.

37. refrigerant circuit according to one of the preceding claims,

characterized in that the controller (132, 138) the

Measures ambient temperature and / or the temperature of the mass flow of the refrigerant in front of an inlet (104) of the supercooling unit (102) and / or in front of an expander inlet (92) by means of a sensor (134).

38. refrigerant circuit according to one of the preceding claims,

characterized in that the controller (132, 138) a

is an electronic controller (132, 138) comprising a processor, which controls the expansion element (122) electrically by means of a control program.

39. Refrigerant circuit according to claim 35 to 38, characterized in that the branch (116) is arranged between the supercooling unit (102) and the expansion compression unit (84) and after the subcooling unit (102) of the total mass flow (G) the subcooling mass flow (U) branches.

40. Refrigerant circuit according to one of claims 35 to 39, characterized in that the subcooling unit (102) is designed as a heat exchanger and cools the mass flow of refrigerant flowing to the expander (86) by the subcooling mass flow U conducted in countercurrent through it.

41. Refrigerant circuit according to one of the preceding claims,

characterized in that the expander (86) and the compressor stage (88) of the expansion compression unit (84) are mechanically functionally coupled.

42. Refrigerant circuit according to one of the preceding claims,

characterized in that the expander (86) and the compressor stage (88) are formed by a free piston machine in which at least one free piston (152, 154) is freely movable in a piston chamber (144, 146).

43. The refrigerant circuit according to claim 42, characterized in that the expansion compression unit (84) has two piston chambers (144, 146), in each of which a free piston (152, 154) is movable.