EP2933443A1 - Cooling device for a capacitor of a system for a thermodynamic cycle process, system for a thermodynamic cycle process, assembly with an internal combustion engine and a system, motor vehicle, and a method for carrying out a thermodynamic cycle - Google Patents

Abstract

The invention relates to a cooling device (21) for a condenser (15) of a system (7) for a thermodynamic cycle, comprising a cooling medium circuit (23), wherein a conveying device (33) for conveying a cooling medium along the cooling medium circuit (23) is provided, and wherein the cooling medium circuit (23) has a cold branch (35) downstream of a cooling point (37) for the cooling medium and a hot branch (41) upstream of the cooling point (37). It is provided that the conveyor (33) has a variable capacity, and / or that the cooling medium circuit (23) has a connecting line (43) between the warm branch (41) and the cold branch (35), wherein a mixing device (45 ) is provided, through which a variable proportion of cooling medium from the warm branch (41) via the connecting line (43) to the cold branch (35), bypassing the cooling point (37) can be fed.

Description

The invention relates to a cooling device for a condenser of a system for thermodynamic cycle according to claim 1, a system for a thermodynamic cycle according to claim 8, an arrangement of an internal combustion engine and such a system according to claim 10, a motor vehicle with a corresponding arrangement according to claim 11 , and a method for performing a thermodynamic cycle according to claim 13.

Thermodynamic cycles of the type discussed here are known per se. In this case, a working medium is heated in an evaporator, in particular evaporated and then expanded in an expansion device, wherein recorded in the evaporator heat of the working medium is converted into mechanical energy. Subsequently, the working medium is cooled in a condenser, in particular condensed, and in turn fed to the evaporator. The organic Rankine cycle, for example, essentially corresponds to the Rankine cycle, but it is suitable for lower operating temperatures. It is therefore particularly suitable for the use of waste heat, for example of industrial processes or of internal combustion engines. In order to cool the working medium in the condenser, in particular to condense, a cooling device is provided. This may for example be designed as air cooling, wherein a cooling capacity of the cooling device is set in this case by a control of a fan. The disadvantage of this is that the fan has a very high energy consumption. It is also possible that the cooling device provides a direct connection between the condenser and an external heat reservoir, for example in the form of tap water, river water or seawater. In this case, the available cooling capacity for the condenser is fixed so that it is limited to operation at a certain temperature level and thus a certain condensation pressure is. This requires in many operating points of a system for operating the thermodynamic cycle a reduced compared to a possible maximum power output. Also, if the temperature of the working medium at the outlet from the condenser varies with the operating point of the system due to the fixed cooling capacity, it is possible that at certain operating points, in particular in high load ranges of the system, sufficient subcooling of the working medium below its condensation point in the condenser will not be ensured can be, which creates the risk that in a conveyor of the system, which is set up to promote the working medium along the circuit cavitations occur.

The invention has for its object to provide a cooling device by which the disadvantages mentioned are avoidable. The invention is also based on the object to provide a corresponding system, an arrangement of an internal combustion engine and a system, a motor vehicle, and a method for operating a thermodynamic cycle, wherein said disadvantages do not occur.

The object is achieved by providing a cooling device with the features of claim 1. This is designed for cooling a condenser of a system for operating a thermodynamic cycle, very preferably an organic Rankine cycle process - abbreviated to ORC (Organic Rankine Cycle) - wherein the cooling device has a cooling medium circuit. It is provided a conveyor for conveying a cooling medium along the cooling medium circuit. The cooling medium circuit has a cold branch upstream of a cooling point for the cooling medium and a warm branch downstream of the cooling point. The cooling device is characterized according to a first embodiment in that the conveyor has a variable capacity. As a result, the cooling capacity of the cooling device is always adaptable by varying the delivery rate of the conveyor to a current operating point of the system for the thermodynamic cycle, so that the temperature level and thus the condensation pressure in the condenser is always exactly adjustable. Alternatively, it is provided according to a second embodiment that the cooling medium circuit has a connecting line between the warm branch and the cold branch, wherein a mixing device is provided, through which a variable proportion of cooling medium from the warm branch via the connecting line, bypassing the cooling point the cold branch can be fed. As a result, a temperature level of the cooling medium upstream of the capacitor is adjustable, which in turn the cooling capacity of the Cooling device can be adjusted. This is therefore always exactly and exactly adaptable to an operating point of the system in this way.

The cooling point designates a region of the cooling medium cycle in which the cooling medium is cooled, in particular recooled, in which case the heat absorbed in the condenser by the cooling medium is dissipated. The cold branch of the cooling circuit connects the cooling point with the condenser, so that this cooled cooling medium can be supplied, wherein the warm branch connects the condenser with the cooling point, so that in the condenser heated cooling medium of the cooling point can be supplied for cooling. The cooling device is so far not formed as an open system under direct connection of the condenser with the environment or an external heat reservoir, but as a recooled primary cooling circuit, which is cooled even in the area of the cooling point.

In a preferred embodiment of the cooling device, the conveyor is designed as a pump, wherein the delivery rate of the pump is variable by having a variable speed.

A variable proportion of cooling medium from the warm branch which is variable in the mixing device speaks in particular to a ratio of a volume flow of the cooling medium which flows via the connecting line to a volume flow which flows via the cooling point. It is obvious that so, in the mixing device from the cooling point approaching, cold cooling medium with upstream of the cooling point branched off, warm, from the condenser heranströmendem cooling medium can be mixed, so that finally the temperature of the condenser for cooling cooling medium supplied is adjustable.

Particularly preferred is a third embodiment of the cooling device, in which both the conveyor has a variable capacity, and the cooling medium circuit has the connecting line between the warm branch and the cold branch, wherein the mixing device is provided, through which a variable proportion of cooling medium from the warm branch over the connecting line to the cold branch, bypassing the cooling point can be fed. In this way, two degrees of freedom for controlling the cooling capacity are available, so that they can be set very accurately and independently of a temperature level of the cooling point. Thus, the condensation pressure in The capacitor can be precisely adjusted and tuned to all occurring operating points of the system. In order for an optimal power output can be guaranteed in all operating points, and the cooling of the capacitor is not limited by fixed cooling capacity to a certain temperature level and thus a certain condensation pressure. The conveyor has, in particular when it is designed as a variable speed pump, a much lower power consumption than is the case with a fan of an air-cooled condenser. In addition, the cooling capacity of the cooling device proposed here is more precisely adjustable than is the case with air cooling by ambient air through a fan.

An embodiment of the cooling device is preferred, which is characterized in that the conveying device is designed as a controllable conveying device. As a result, the flow of the cooling medium through the cooling medium circuit, in particular the volume flow of cooling medium through the condenser, is particularly precisely adjustable. It is possible that a delivery line of the conveyor is controlled by the volume flow through the condenser. Particularly preferably, the conveyor is designed as a controllable pump. In this case, the speed of the pump is preferably adjustable, which represents a particularly simple embodiment of a controllable conveyor.

An embodiment of the cooling device is also preferred, which is characterized in that the connecting line branches off from the hot branch upstream of a recooling device, wherein the recooling device is set up for cooling the cooling medium in the cooling medium circuit. The connecting line opens downstream of the recooling device in the cold branch. The cooling point of the cooling device is realized in this embodiment by the recooling device, wherein preferably realized with the cooling medium circuit primary cooling circuit is connected heat-transmitting with a secondary cooling circuit. Alternatively, it is possible that the recooling means provides a thermal connection of the cooling medium circuit to an external heat reservoir. The recooling device is preferably designed for using extraneous water or air as the cooling medium, in particular tap water, river water or seawater, or ambient air. In particular, in a marine application of the system, a recirculation by seawater is preferred. By means of the recooling device, the cooling medium in the region of the cooling point can be cooled very efficiently, the waste heat of which can be dissipated to the environment in a simple and cost-effective manner. By doing that the connection line branches off upstream of the recooling device from the warm branch, along the connecting line still uncooled, heated in the condenser cooling medium can be performed. Characterized in that the connecting line opens downstream of the recooling device in the cold branch, at this point, is preferably provided to the mixing device, particularly efficient cold, flowing from the recooling cooling medium with warm, over the connecting line approaching cooling medium can be mixed.

It is also preferred an embodiment of the cooling device, which is characterized in that the connecting line opens upstream of the conveyor in the cold branch. Thus, the mixing device is preferably also arranged upstream of the conveying device, so that it conveys already mixed cooling medium with the temperature set in the mixing device. This proves to be particularly favorable and simpler than control technology, as if the connection line would open downstream of the conveyor in the cold branch, so that the conveyor only promotes cold cooling medium.

An embodiment of the cooling device is preferred, which is characterized in that the mixing device is designed as a three-way mixer, wherein the cold branch extends over a first and a second connection of the three-way mixer, wherein the connecting line into a third Connection of the three-way mixer opens. The part of the cold branch coming from the cooling point opens into a first connection of the three-way mixer, the flow path of the cooling medium continuing from a second connection of the three-way mixer to the condenser. The connection line is connected to the third connection of the three-way mixer so that cooling medium from the first and the third connection is mixed in the mixing device and supplied to the second connection. This represents a particularly simple and cost-effective as well as easy-to-regulate embodiment of the mixing device. This preferably has a first functional position, in which the first terminal is connected to the second terminal, wherein the third terminal is blocked. In this case, the mixing device passes through only cold cooling medium, so far as a minimum temperature of the medium is realized. In a second functional position, the third connection is preferably connected to the second connection, wherein the first connection is blocked. In this case, the mixing device only lets through warm cooling medium, so that in this respect a maximum temperature of the medium is realized. Between these two extremal positions are preferably different Functional positions, particularly preferably a continuum of functional positions, feasible, so that the temperature of the cooling medium through the mixing device is almost arbitrary or arbitrarily adjustable between the minimum fluid temperature and the maximum fluid temperature.

A cooling device is also preferred, which is characterized by a control device which is set up for setting a predefinable absolute or relative temperature level in a condenser of a system for operating a thermodynamic cycle, most preferably an ORC, by controlling the conveyor and / or by driving the mixing device. In this case, the control device is particularly preferably set up for setting the temperature level by controlling both the conveyor and the mixing device. In any case, it is possible with the aid of the control device to set, preferably to control or regulate an absolute or relative temperature level in the condenser very precisely and precisely.

In this case, an absolute temperature level is responsive to an absolute, predetermined temperature which is to be reached in the condenser or immediately downstream of a working medium outlet of the working medium condenser. A relative temperature level preferably responds to a predetermined undercooling of the working fluid in the condenser or immediately downstream of the condenser, hence a predetermined difference in the working fluid temperature to a condensation point of the working fluid in the condenser. By deliberately setting the subcooling, it can be ensured that the working medium does not cavitate in a working medium pump of the system. In addition, by adjusting the absolute or relative temperature level in the condenser or immediately downstream of the condenser, the system power yield can be optimized. This requires, in particular, an exact adjustment of the pressure in the condenser, which can be set very precisely by varying the working medium temperature and therefore by varying the cooling capacity of the cooling device. This pressure acts as a back pressure on the expansion device and therefore determines together with other operating parameters of the system significantly its power output. The cooling capacity, which the cooling device has to apply to set a predeterminable temperature level, varies depending on the operating point of the system, in particular depending on a heat input into the system, since depending on the heat input into the evaporator, a smaller or larger amount of heat must be dissipated in the condenser. It should be using the here Proposed cooling device can be prevented in particular that more heat is dissipated than is necessary to achieve a predetermined supercooling of the working medium. Otherwise, this again has a negative effect on the power output of the system.

Preferably, the control device is set up for specifying the volume flow of the cooling medium via the regulation of the delivery rate of the delivery device and for specifying the cooling medium inlet temperature into the condenser by activating or regulating the mixing device. In this way, by the control device very sensitively the cooling capacity of the cooling device, in particular by combined variation of the delivery rate and the temperature setting in the mixing device, adjustable, in particular controllable or adjustable.

An embodiment of the cooling device is preferred, which is characterized in that the control device is set up to optimize a power output of the system by controlling the conveyor and / or the mixing device. In this case, the control device preferably has a feedback to at least one characteristic of the power output of the system parameters, so that the power output is directly optimized or regulated. As a result, the cooling performance of the cooling device can always be optimally tuned to an existing operating point of the system. Particularly preferably, the control device is set up to optimize a power output of the system by controlling both the conveyor and the mixing device.

The object is also achieved by providing a system for operating a thermodynamic cycle, more preferably an organic Rankine cycle, which is characterized by a cooling device according to one of the previously described embodiments. In the process, the advantages which have already been described in connection with the cooling device are realized for the system. In particular, the system can be controlled by the cooling device at all operating points to an optimal power output.

The system preferably comprises a working fluid circuit along which - in this order - an evaporator, an expansion device, a condenser, and preferably a working fluid pump for conveying working fluid are arranged along the circuit. The cooling device is operatively connected to the condenser for cooling working medium in the condenser.

The system also preferably includes at least one temperature sensor and / or at least one pressure sensor in the condenser or immediately downstream of the condenser - as seen along the working fluid circuit - operatively connected to the controller for controlling the refrigeration device. With the aid of the temperature sensor and / or the pressure sensor, a thermodynamic state of the working medium in the condenser can be detected, and the cooling capacity of the cooling device is adjustable, in particular controllable or controllable.

An exemplary embodiment of the system is preferred, which is characterized in that it is designed to utilize waste heat from an internal combustion engine. In particular for this purpose, an ORC is preferably carried out in the system. It is possible to use waste heat from an exhaust gas flow and / or from a coolant flow of the internal combustion engine. Alternatively, it is possible for the system to be configured to utilize waste heat or heat from another heat source, such as industrial waste heat and / or to use geothermal heat, preferably also by means of an ORC.

Ethanol is preferably provided as the working medium in the system. This is particularly suitable in operating points of the system, which are achieved when using waste heat from the exhaust gas of an internal combustion engine and for an ORC.

The object is also achieved by providing an arrangement with the features of claim 10. This has an internal combustion engine and a system according to one of the embodiments described above. The system with the internal combustion engine for the use of waste heat of the same is operatively connected. The system can be used to convert the waste heat into mechanical and / or electrical energy, which is supplied to the internal combustion engine again, for example, a crankshaft of the internal combustion engine, in particular by means of an electric motor, which is operatively connected to the crankshaft. Alternatively or additionally, it is possible for the energy converted in the system from the waste heat of the internal combustion engine to be supplied to an external consumer or a power grid. It is possible that the power grid is an on-board power supply system of a motor vehicle, which has the arrangement. With the help of Systems, the efficiency of the internal combustion engine by using their waste heat can be significantly increased. This is not dissipated useless to the environment, but rather can be used meaningfully.

The internal combustion engine of the arrangement is preferably designed as a reciprocating engine. In a preferred embodiment, the internal combustion engine is used to drive in particular heavy land or water vehicles, such as mine vehicles, trains, the internal combustion engine is used in a locomotive or a railcar, or ships. It is also possible to use the internal combustion engine to drive a defense vehicle, for example a tank. An exemplary embodiment of the internal combustion engine is preferably also stationary, for example, used for stationary power supply in emergency operation, continuous load operation or peak load operation, the internal combustion engine in this case preferably drives a generator. A stationary application of the internal combustion engine for driving auxiliary equipment, such as fire pumps on oil rigs, is possible. Furthermore, an application of the internal combustion engine in the field of promoting fossil raw materials and in particular fuels, for example oil and / or gas, possible. It is also possible to use the internal combustion engine in the industrial sector or in the field of construction, for example in a construction or construction machine, for example in a crane or an excavator. The internal combustion engine is preferably designed as a diesel engine, as a gasoline engine, as a gas engine for operation with natural gas, biogas, special gas or another suitable gas. In particular, when the internal combustion engine is designed as a gas engine, it is suitable for use in a cogeneration plant for stationary power generation.

The object is also achieved by providing a motor vehicle having the features of claim 11. This is characterized by an arrangement according to one of the embodiments described above. In this case, with regard to the motor vehicle realize the advantages that have already been carried out in connection with the cooling device, the system and the arrangement. The converted by the system energy from the waste heat of the engine can be used meaningful either to support the engine or for other purposes, for example, to supply an on-board network of the motor vehicle, with electrical energy.

Particularly preferred is an embodiment of the motor vehicle, which is designed as a watercraft, in particular as a ship, preferably as a ferry. In this case, waste heat is possible here in a particularly varied manner for operating various systems of the ship, in particular an on-board network or a ship's own power network or for supporting the internal combustion engine. In addition, the recooling device can be realized in a watercraft in a particularly simple and cost-effective manner by using seawater or river water for recooling. Thus, a quasi-inexhaustible heat reservoir is available for the recooling, so that an exact adjustment of the thermodynamic state of the working medium in the condenser does not fail in any case due to a lack of recooling capacity.

Finally, the object is also achieved by providing a method for operating a thermodynamic cycle, more preferably an organic Rankine cycle, having the features of claim 13. The method is in particular provided for operating a system according to one of the previously described embodiments. In this case, the system - seen in this order along a working medium flow in a circuit of the system - an evaporator, an expansion device and a capacitor, wherein it further comprises a cooling device, preferably a cooling device according to one of the preceding embodiments. In the context of the method, a cooling capacity of the condenser is adjusted by controlling a conveyor of the cooling device with variable capacity, and / or by a mixing device for supplying a variable proportion of cooling medium from a warm branch of the cooling device via a connecting line to a cold branch of the cooling device is controlled. Preferably, the cooling capacity of the condenser is adjusted by controlling both the conveyor and the mixing device accordingly. This realizes the advantages that have already been described in connection with the cooling device, the system, the arrangement, the motor vehicle.

As a conveying device, a pump, in particular a pump with variable speed is preferably used in the context of the method, wherein the delivery rate of the pump is adjusted by varying the speed.

An embodiment of the method is preferred, which is characterized in that the delivery rate of the conveyor and / or a functional position of the mixing device is / are regulated. This allows a particularly accurate adjustment of the cooling capacity of the cooling device and thus at the same time the cooling capacity of the capacitor. Preferably, both the delivery rate of the conveyor and the functional position of the mixing device are regulated.

Finally, an embodiment of the method is preferred, which is characterized in that the cooling capacity of the cooling device is regulated to an optimum power output of the system and / or to a specifiable absolute or relative temperature level in the condenser or immediately downstream of the condenser in the working medium. This can be ensured in a particularly suitable and accurate way optimal power output in all operating points of the system.

The description of the cooling device and the system on the one hand and the method on the other hand are to be understood as complementary. In particular, method steps that have been explained explicitly or implicitly in connection with the cooling device or the system, preferably individually or combined with each other steps of a preferred embodiment of the method. Likewise, features of the cooling device or system that have been explicitly or implicitly explained in connection with the method are preferably individually or combined together features of a preferred embodiment of the cooling device or system. The cooling device or the system are preferably distinguished by at least one feature which is caused by at least one method step of the method. The method is preferably characterized by at least one method step, which is caused by at least one feature of the cooling device or of the system.

Figur 1

eine schematische Darstellung eines Ausführungsbeispiels eines Kraftfahrzeugs mit einer Anordnung aus einer Brennkraftmaschine und einem System mit einer Kühleinrichtung;

Figur 2

eine schematische Darstellung eines Ausführungsbeispiels der Kühleinrichtung, und

Figur 3

eine schematische Darstellung einer Ausführungsform des Verfahrens in Form eines Regelkreises.

The invention will be explained in more detail below with reference to the drawing. Showing:

FIG. 1

a schematic representation of an embodiment of a motor vehicle with an arrangement of an internal combustion engine and a system with a cooling device;

FIG. 2

a schematic representation of an embodiment of the cooling device, and

FIG. 3

a schematic representation of an embodiment of the method in the form of a control loop.

Fig. 1 shows a schematic representation of an embodiment of a motor vehicle 1, which has an arrangement 3 of an internal combustion engine 5 and a system 7 for operating a thermodynamic cycle, here in particular an organic Rankine cycle (ORC). The motor vehicle 1 is preferably designed as a ship. Alternatively, however, an embodiment of the motor vehicle 1 as a rail vehicle, mining or construction vehicle, defense vehicle, commercial vehicle or as a passenger car is possible.

The application of the arrangement 3 is not limited to motor vehicles, but this can also be used in other areas, for example in stationary use of the internal combustion engine 5, for example, for operating pumps on a drilling rig for waste heat recovery.

Finally, the system 7 is not limited to use in an arrangement with an internal combustion engine 5. Rather, this can otherwise be used for waste heat, for example, to use industrial waste heat, or for the use of other heat sources, such as geothermal heat.

The system 7 has a working medium circuit 9, along which - seen in the flow direction of the working medium - an evaporator 11, an expansion device 13, and a capacitor 15 are arranged. The working medium can be conveyed by means of a working medium pump 17 along the working medium circuit 9. Ethanol is preferably used as the working medium.

The expansion device 13 is preferably designed as a turbomachine or as a displacement machine, in particular as a turbine, as Hubkolbenexpander, as a vane machine, as Roots expander or as Scrollexpander. However, an embodiment of the expansion device 13 as a screw expander is particularly preferred. The expansion device 13 is operatively connected to a generator 19 for converting mechanical energy obtained in the expansion device 13 into electrical energy.

The evaporator 11 is preferably operatively connected to the internal combustion engine 5 so that waste heat from the exhaust gas and / or the cooling circuit of the internal combustion engine 5, in particular waste heat from the exhaust gas thereof, in the evaporator 11 to the working medium of the system 7 can be fed.

For cooling the working medium in the condenser 15, in particular for the condensation of a cooling device 21 is provided with a cooling medium circuit 23. Preferably immediately downstream of the condenser 15 or in the condenser 15, a sensor device 25 for detecting a temperature and / or a pressure of the working medium in the condenser 15 is provided. In this case, the expression "in the capacitor" always addresses not only a value directly within the capacitor 15, but also a value detected immediately downstream thereof, since these values differ from each other at most in a manner not relevant. The sensor device 25 is operatively connected to a control device 27, which in turn is in turn operatively connected to the cooling device 21 for setting a cooling capacity thereof.

It turns out that, depending on an operating point of the internal combustion engine 5, the waste heat introduced into the evaporator 11 varies. At the same time, an operating point of the system 7 and a cooling capacity of the cooling device 21 necessary for optimum power output thereby vary. This is precisely set with the aid of the cooling device 21 and the control device 27 at each operating point of the system 7 with regard to optimum power output.

Fig. 2 1 shows a schematic representation of an exemplary embodiment of the cooling device 21. Also shown is the condenser 15 and a working medium inlet 29 and a working medium outlet 31 to or from the condenser 15. A dashed line L indicates a system boundary between the condenser 15 and the rest of the system 7.

The cooling device 21 has the cooling medium circuit 23, which is designed as a primary cooling circuit. It is provided here as a pump designed conveyor 33 for conveying cooling medium along the cooling medium circuit 23, wherein the conveyor 33 has a variable capacity, here a variable speed for adjusting a volume flow of the cooling medium in the cooling medium circuit 23. The cooling medium circuit 23 has a cold branch 35 - seen in the direction of the cooling medium flow - downstream of a cooling point 37, which is designed here as a recooling device 39, and a hot branch 41 upstream of the cooling point 37 on. Between the warm branch 41 and the cold branch 35, a connecting line 43 is arranged, and there is a mixing device 45, which is designed here as a three-way mixer 47, through which a variable proportion of a cooling medium from the warm branch 41 on the Connecting line 43 the cold branch 35 can be fed. In this case, a functional position of the mixing device 45 is variably adjustable, so that a variable mixing ratio between the approaching through the connecting line 43, the warm cooling medium and the cold, approaching from the cooling point 37 cooling medium is adjustable.

In this case, the cold branch 35 extends via a first connection 49 to a second connection 51, wherein the connection line 43 opens into a third connection 53 of the three-way mixer 47.

By arrows P is in FIG. 2 the direction of flow of the cooling medium in the cooling medium circuit 23 is indicated, wherein the cooling medium can be conveyed through the conveying device 33 in the indicated flow direction along the cooling medium circuit 23.

It is obvious that here the connecting line 43 branches off from the warm branch 41 upstream of the recooling device 39, wherein it opens downstream of the recooling device 39 in the cold branch, in particular flows upstream of the conveyor 33 in this.

The recooling device 39 is designed for recooling the cooling medium by means of a recooling medium which can be conveyed through a recooling medium pump 55 along a recooling path 57, which is preferably designed as a secondary cooling circuit. As recooling medium seawater is particularly preferably used, in particular in a design of the motor vehicle 1 as a ship. However, if the ship is designed as a river ship, preferably river water is used as recooling medium.

In other applications of the system 7 may alternatively be provided that as recooling medium air, in particular ambient air, or a heat connection with a other, external heat reservoir is used. For example, tap water is also possible as recooling medium.

Incidentally, the cooling medium circuit 23 also has a compensation reservoir 59 for the cooling medium.

In FIG. 2 is also the control device 27 shown, which is operatively connected to the sensor device 25 for detecting a thermodynamic state of the working medium in the condenser 15, in particular for detecting a temperature and / or pressure of the working medium.

In addition, the control device 27 is operatively connected to the mixing device 45 for controlling or regulating its functional position. In this case, by appropriate control of the mixing device 45, a temperature of the cooling medium downstream of the mixing device 45 and thus in particular a cooling medium inlet temperature in the condenser 15 can be controlled, at the same time by appropriate control of the conveyor 33, a volume flow of the cooling medium along the cooling medium circuit 23 and in particular by the capacitor 15 controlled is. Overall, the cooling capacity of the cooling device 21 is thus preferably adjustable depending on an operating point of the system 7. Thus, it is possible to precisely adjust the state of the working fluid downstream of the condenser 15. This is possible in particular by means of the cooling device 21, although the temperature of the recooling medium in the recooling path 57 is typically not controllable or regulatable, but rather predetermined by external circumstances. This is evident when seawater or ambient air is used as the re-cooling medium.

As the cooling medium, water is preferably used in the cooling device 21 and in particular in the cooling medium circuit 23.

Fig. 3 shows a schematic representation of an embodiment of the method in the form of a control loop. In this case, the target value 61 in the control loop is a desired value of a thermodynamic state variable of the working medium in the condenser 15, preferably a desired temperature or a desired subcooling of the working medium. An actual value 63 of the thermodynamic state variable, which is preferably measured by the sensor device 25, is fed back to a comparison element 65, and a control deviation 67 between the target specification 61 and the actual value 63 is determined.

The target specification 61 is preferably taken from a characteristic field which is spanned by at least one operating parameter of the system 7 for characterizing its operating states. Alternatively, it is possible that a constant target specification 61 is selected for the operation of the system 7. In this case, the cooling capacity of the cooling device 21 in particular depends on a heat input in the evaporator 11.

The control deviation 67 is fed to a controller 69, which calculates two values for actuators on this basis, namely a first preset value 71 for a delivery rate of the conveyor 33, in particular a speed of the conveyor 33 designed as a pump, and a second default value 73 for controlling the mixer 45. The two default values 71, 73 act on a controlled system 75, which in this case has, in particular, the mixing device 45 and the conveying device 33, and finally the condenser 15. Preferably, the delivery rate of the conveyor 33 and the functional position of the mixing device 45 are regulated to the default values 71, 73, which is not explicitly shown here. It is in this respect a subordinate regulation.

In the controlled system 75, in turn, a new actual value 63 for the thermodynamic state variable of the working medium in the condenser 15 is established.

Quite generally, a cooling capacity of the condenser 15 of the system 7 is set in the context of the method by the conveyor 33 is driven with variable capacity, in addition to the mixing device 45 for supplying a variable proportion of cooling medium from the warm branch 41 via the connecting line 43 to the cold branch 35 is controlled.

If a constant value is selected for the target specification 61, this is preferably determined so that the system 7 has the highest possible power yield at all operating points. If the target specification 61 is taken from a characteristic map, this preferably has values for the target specification 61 at which the system 7 has its optimum operating point Has power output. Accordingly, the cooling capacity of the cooling device 21 is regulated in particular for optimum performance of the system 7.

Overall, it turns out that with the aid of the method an energy-saving and at the same time very precise control of the cooling capacity of the cooling device 21 is possible, so that the system 7 can be operated with optimum power yield.

Claims (15)

Cooling device (21) for a condenser (15) of a system (7) for a thermodynamic cycle, with a cooling medium circuit (23), wherein a conveyor (33) for conveying a cooling medium along the cooling medium circuit (23) is provided, and wherein the cooling medium circuit (23) a cold branch (35) downstream of a cooling point (37) for the cooling medium, and a hot branch (41) upstream of the cooling point (37), characterized in that the conveyor (33) has a variable capacity, and / or that the cooling medium circuit (23) has a connecting line (43) between the warm branch (41) and the cold branch (35), wherein a mixing device (45) is provided, through which a variable proportion of cooling medium from the warm branch (41 ) via the connecting line (43) the cold branch (35) bypassing the cooling point (37) can be fed. Cooling device (21) according to claim 1, characterized in that the conveying device (33) is designed as a controllable conveying device (33). Cooling device (21) according to one of the preceding claims, characterized in that the connecting line (43) upstream of a recooling device (39), which is adapted for cooling the cooling medium in the cooling medium circuit (23) branches off from the warm branch (41) Connecting line (43) downstream of the recooling device (39) opens into the cold branch (35). Cooling device (21) according to one of the preceding claims, characterized in that the connecting line (43) opens into the cold branch (35) upstream of the conveying device (33). Cooling device (21) according to any one of the preceding claims, characterized in that the mixing device (45) as a three-way mixer (47) is formed, wherein the cold branch (35) via a first and a second connection (49,51) of the three-way mixer (47), wherein the connecting line (43) opens into a third port (53) of the three-way mixer (47). Cooling device (21) according to one of the preceding claims, characterized by a control device (27) which is set up for setting a predeterminable absolute or relative temperature level in a condenser (15) of a system (7) for a thermodynamic cycle by driving the conveyor (33 ) and / or the mixing device (45). Cooling device (21) according to any one of the preceding claims, characterized in that the control device (27) is adapted to optimize a power yield of a system (7) for a thermodynamic cycle by controlling the conveyor (33) and / or by controlling the mixing device (45 ). System (7) for a thermodynamic cycle, in particular for an organic Rankine cycle, characterized by a cooling device (21) according to one of claims 1 to 7. System (7) according to claim 8, characterized in that the system (7) is adapted to the use of waste heat of an internal combustion engine (5). Arrangement (3), comprising an internal combustion engine (5) and a system (7) according to one of claims 8 and 9. Motor vehicle (1), with an arrangement (3) according to claim 10. Motor vehicle (1) according to claim 11, characterized in that the motor vehicle (1) as a watercraft, in particular as a ship, is formed. Method for carrying out a thermodynamic cycle, preferably an organic Rankine cycle, in particular for operating a system according to one of claims 8 and 9, comprising an evaporator (11), an expansion device (13) and a condenser (15), and with a cooling device (21), in particular a cooling device (21) according to one of claims 1 to 7, wherein a cooling capacity of the condenser (15) is adjusted by a conveyor (33) of the cooling device (21) is driven with variable capacity, and / or by a mixing device (45) for supplying a variable Proportion of cooling medium from a warm branch (41) of the cooling device (21) via a connecting line (43) to a cold branch (35) of the cooling device (21) is driven. A method according to claim 13, characterized in that the delivery rate of the conveyor (33) and / or a functional position of the mixing device (45) is / are regulated. Method according to one of claims 13 and 14, characterized in that the cooling capacity is regulated to an optimum power output of the system (7) or to a predeterminable absolute or relative temperature level in the condenser (15).

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