US20120060502A1

US20120060502A1 - Clausius-Rankine cycle

Info

Publication number: US20120060502A1
Application number: US13/068,077
Authority: US
Inventors: Jan Gärtner; Thomas Koch
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2008-11-13
Filing date: 2011-05-02
Publication date: 2012-03-15
Also published as: WO2010054724A2; DE102008057202A1; EP2387655A2; CN102265002B; JP2012508842A; WO2010054724A3; CN102265002A; JP5661044B2

Abstract

In a Clausius-Rankine cycle, in particular for mobile applications, comprising a pump for circulating a liquid working fluid in the Clausius-Rankine cycle and pressurizing the working fluid, a heating device for vaporizing the pressurized liquid working fluid and an expansion device for generating mechanical driving power by expanding the hot, compressed vaporized working fluid, a condenser device for condensing the hot, expanded vaporized working fluid is provided to form again liquid working fluid and the condenser device includes integrated therein a collection volume for collecting and storing liquid working fluid.

Description

This is a Continuation-In-Part application of international patent application PCT/EP2009/007162 filed 6 Oct. 2009 and claiming the priority of German patent application 10 2008 057 202.0 filed 13 Nov. 2008.

BACKGROUND OF THE INVENTION

The present invention relates to a Clausius-Rankine cycle, in particular for mobile applications, preferably in motor vehicles. The invention additionally relates to a motor vehicle with such a Clausius-Rankine cycle.
A Clausius-Rankine cycle is known from DE 102 59 488 A1. It comprises a pump for driving a liquid working fluid in the Clausius-Rankine cycle and for pressurizing the working fluid in a usual manner. Furthermore, a heating device for vaporizing the liquid working fluid under pressure is provided. Additionally, an expansion device for generating mechanical drive power by means of expansion of the hot compressed vapor is provided. The hot expanded vapor can be condensed with the help of a condenser device and can be fed back to the pump as liquid working fluid. The known Clausius-Rankine cycle further has a collection volume for collecting and storing liquid working fluid. With the known Clausius-Rankine cycle, the collection volume is contained in a collection container, which can be coupled to a heat exchanger in a heat-transfer manner in order to preheat the stored liquid working fluid.
Further Clausius-Rankine cycles are for example known from DE 10 2005 061 214 A1, from DE 10 2006 043 518 A1, from DE 10 2004 018 860 A1 and from JP 2008-8224.
It is the object of the present invention to provide an improved embodiment for a Clausius-Rankine cycle of the type mentioned above, which is distinguished in particular in that it requires comparatively little installation space and thus simplifies the realization of mobile uses.

SUMMARY OF THE INVENTION

In a Clausius-Rankine cycle, in particular for mobile applications, comprising a pump for circulating a liquid working fluid in the Clausius-Rankine cycle and pressurizing the working fluid, a heating device for vaporizing the pressurized liquid working fluid and an expansion device for generating mechanical driving power by expanding the hot, compressed vaporized working fluid, a condenser device for condensing the hot, expanded vaporized working fluid is provided to form again liquid working fluid and the condenser device includes integrated therein a collection volume for collecting and storing liquid working fluid.
The condenser device is provided with a corresponding housing for this, which contains the collection volume for storing and for collecting the condensed working fluid. As the Clausius-Rankine requires a condenser device in any case, which has to be installed in such a manner that the liquid working fluid can be fed to the pump in a comparatively simple manner, the construction of the Clausius-Rankine cycle is simplified by the suggested integration of the collection volume into the housing of the condenser device. A separate collection container for accommodating the collection volume therefore is not needed. The Clausius-Rankine cycle altogether thus needs less installation space. The realization of such a Clausius-Rankine cycle in a mobile use, as for example in a motor vehicle, is simplified by its simplified design.
The housing contains a condenser volume in addition to the collection volume in a convenient embodiment. The condenser volume is open towards the collection volume and includes a heat exchanger, through which a cooling fluid is conducted. The collection volume takes up a comparatively large part of the total volume of the housing of the condenser device. The collection volume and the housing are for example adjusted to each other in such a manner that the collection volume comprises at least 30% or at least 50% or at least 60% of the total volume of the housing. Consequently, depending on the embodiment, the condenser volume in the housing of the condenser device may be smaller than the collection volume.
For achieving a high condensing performance, the condenser device is connected to a cooling circuit, in which a cooling fluid circulates.
The Clausius-Rankine cycle conveniently includes a control device. The control device may be designed according to an advantageous embodiment in such a manner that the amount of the working fluid circulating in the Clausius-Rankine cycle can be adjusted therewith, namely in dependence on the momentary operating state of the Clausius-Rankine cycle. This embodiment is based on the knowledge that a different amount of working fluid is necessary in the Clausius-Rankine cycle depending on the operating state or operating point, in order to be able to operate it in an optimum manner. The optimum circulating working fluid amount varies for example in dependence on the drive power to be applied by the expansion device and/or in dependence on the heating power available at the heating device and/or in dependence on pressures and/or temperatures. The control device can now determine, based on the momentary operating state, for example via characteristic performance graphs and/or calculation models, the amount of working fluid necessary, which has to circulate in the Clausius-Rankine cycle for an optimum operation. The efficiency of the Clausius-Rankine cycle can thus be improved.
In a preferred embodiment, the control device can be arranged in such a manner that it adjusts the amount of working fluid circulating in the Clausius-Rankine cycle by changing the condenser performance of the condenser device. This embodiment uses the knowledge that the amount of the working fluid circulating in the Clausius-Rankine cycle depends on the ratio of the gas phase to the liquid phase of the working fluid. The higher the condenser performance of the condenser device, the more liquid working fluid can be made available for the circulation in the Clausius-Rankine cycle.
According to a particularly advantageous further development, the control device can be designed such that it adjusts the condensing performance of the condenser device by changing the amount of the cooling fluid flowing through the heat exchanger with a condenser device which contains a heat exchanger through which a cooling fluid is circulated. The control device hereby considers the correlation between the cooling fluid flow and the condensate formed in the condenser device.
The factor that the collection volume for liquid working fluid is integrated into the housing of the condenser device is in particular advantageous with the previously described embodiments, where the control device adjusts the amount of the working fluid circulating in the Clausius-Rankine cycle, which simplifies the change of the circulating working fluid amount.
The invention will become more readily apparent from the following description of a preferred embodiment thereof with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

The sole FIG. 1 shows a highly simplified circuit diagram of a Clausius-Rankine cycle.

According to FIG. 1, a Clausius-Rankine cycle 1 comprises a pump 2, a heating device 3, an expansion device 4 and a condenser device 5 as components. Furthermore, lines 6 are provided in order to connect the individual components 2, 3, 4, 5 to each other. A line section 6 a thus connects a pressure side of the pump 2 to an input of the heating device 3. A line section 6 b connects an output of the heating device 3 to an input of the expansion device 4. A line section 6 c connects an output of the expansion device 4 to an input of the condenser device 5. A line section 6 d connects an output of the condenser device 5 to the suction side of the pump 2. The Clausius-Rankine cycle is preferably suitable for a mobile use. Accordingly, it can for example be arranged in a motor vehicle. Such a motor vehicle comprises for example an exhaust gas system 7, which can be coupled to the heating device 3 for heat transfer. An exhaust gas flow can for example be guided through the heating device 3 in the form of a heat exchanger. The vehicle can further have a cooling cycle 8, which can for example be coupled to the condenser device 5 for removing heat therefrom. A heat exchanger 9 of the condenser device 5 can for example be integrated into the cooling cycle 8 of the vehicle. The pump 2 serves for driving a liquid working fluid in the Clausius-Rankine cycle 1. The pump 2 simultaneously serves for pressurizing the working fluid. The pump 2 thus pumps the working fluid through the lines and through the individual components 3, 4, 5. The heating device 3 serves for vaporizing the pressurized liquid working fluid under pressure. Heat q_zuis fed to the working fluid for this. Hot, pressurized, that is, compressed vapor or hot compressed vaporous working fluid is generated hereby. The expansion device 5, for example in the form of a turbine, serves for generating mechanical drive power by expansion of the hot compressed vapor. The expansion device 4 drives for example a generator 11 via a drive shaft 10, in order to generate electrical energy. The condenser device 5 serves for condensing the hot expanded vapor. Heat q_abis thereby discharged from the working fluid. The working fluid is cooled in this manner and thus liquefied. The liquid working fluid can then again be fed to the pump 2.
The condenser device 5 has a housing 12, in which the heat exchanger 9 is arranged. A collection volume 13 is additionally integrated into this housing 12, which volume serves for collecting and storing liquid working fluid. The housing also contains a condenser volume 14 in addition to the collection volume 13. The condenser volume is conveniently open towards the collection volume 13. The heat exchanger 9 is for example arranged in the condenser volume 14. The collection volume is at least 30% or 50% or even more than 60% of a total volume of the housing 12. The condenser volume 14 for receiving the heat exchanger 9 is for example at least 35% of the total volume of the housing 12.
The collection volume 13 provided for collecting and holding the liquid working fluid does not always have to be filled completely by liquid working fluid, rather, the amount of working fluid circulating in the Clausius-Rankine cycle can vary. The Clausius-Rankine cycle 1 can in particular have a control device 15, with the help of which the amount of the working fluid circulating in the Clausius-Rankine cycle 1 can be adjusted. The adjustment of the circulating working fluid amount thereby takes place in dependence on momentary operating parameters of the Clausius-Rankine cycle 1, that is, in dependence on a current operating state. The control device 15 obtains corresponding operating parameters in the example via a corresponding signal line 16. The control device 15 can in particular be connected to an engine control device of the vehicle. The control device 15 can also be connected to a suitable sensor system for sensing the necessary operating parameters. The control device 15 cooperates with a control valve 17 in the example, with the help of which the amount of the cooling fluid flowing through the heat exchanger 9 can be adjusted. The control valve 17 is integrated into the cooling cycle at a suitable location for this. The control valve 17 can for example be integrated into a feed line 18 of the cooling cycle 8 as shown. It is also possible to integrate the control valve 17 into a return 19 of the cooling cycle 8. In the example, the control valve 17 is arranged outside of the housing 12 of the condenser device 5. It is also possible to arrange the control valve 17 in the interior of the housing 12 of the condenser device 5.
The control device 15 can thus adjust the amount of the cooling fluid flowing through the heat exchanger 9 by a corresponding actuation of the control valve 17. As the amount of the cooling fluid flowing through the heat exchanger 9 determines the condensing performance of the condenser device 5, the control device 15 can thus indirectly adjust the condensing performance of the condenser device 5. The condensing performance of the condenser device 5 itself is significant for the ratio of gas phase to liquid phase in the condenser device 5 and thus for the amount of liquid working fluid present. The condensing performance of the condenser device 5 correlates insofar with the amount of working fluid circulating in the Clausius-Rankine cycle. The control device 15 can accordingly adjust the amount of the working fluid circulating in the Clausius-Rankine cycle indirectly. The adjustment of the amount of the working fluid circulating in the Clausius-Rankine cycle 1 can thereby take place in the sense of a control or be carried out in the sense of a regulation. With a control, the control device 15 assigns a control signal to the current operating state, with which the control valve 17 has to be actuated, in order to be able to adjust the desired working fluid amount corresponding to calculations or characteristic performance graphs. With a regulation, the control device 15 compares the actual amount of the working fluid currently circulating in the Clausius-Rankine cycle 1 to a target amount of the working fluid, which should circulate in the Clausius-Rankine cycle 1 due to the current operating state. The control valve 17 is then actuated in dependence on a target-actual comparison.

Claims

What is claimed is:

1. A Clausius-Rankine cycle, in particular for mobile applications, preferably in motor vehicles, comprising:

a pump (2) for pumping a liquid working fluid in a Clausius-Rankine circuit (1) and for pressurizing the working fluid,

a heating device (3) in communication with the pump (2) for receiving the pressurized working fluid and for vaporizing the pressurized working fluid,

an expansion device (4) connected to the heating device for expanding the vaporized pressurized working fluid for generating mechanical drive power,

a condenser device (5) including a housing (12) in communication with the expansion device (4) for condensing the hot, expanded working fluid so as to form a condensate that can be fed to the pump (2) as liquid working fluid, and

a collection volume (13) for collecting and storing liquid working fluid which collection volume (13) is integrated into a housing (12) of the condenser device (5).

2. The Clausius-Rankine cycle according to claim 1, wherein the housing (12) includes a condenser volume (14) which is open towards the collection volume (13), and in which a heat exchanger (9) is arranged through which a cooling fluid is conducted.

3. The Clausius-Rankine cycle according to claim 1, wherein the collection volume (13) forms at least 30% of a total volume of the housing (12).

4. The Clausius-Rankine cycle according to claim 1, wherein the condenser device (5) is connected to a cooling cycle (8) in which a cooling fluid circulates.

5. The Clausius-Rankine cycle according to claim 1, wherein a control device (15) for adjusting the amount of the working fluid circulating in the Clausius-Rankine cycle is provided in dependence on the momentary operating state of the Clausius-Rankine cycle (1).

6. The Clausius-Rankine cycle according to claim 5, wherein the control device (15) is designed in such a manner that it adjusts the amount of the working fluid circulating in the Clausius-Rankine cycle by changing the condensing performance of the condenser device (5).

7. The Clausius-Rankine cycle according to claim 5, wherein the control device (15) is designed in such a manner that it adjusts the condensing performance of the condenser device (5) by changing the amount of the cooling fluid flowing through the heat exchanger (9).

8. The Clausius-Rankine cycle according to claim 7, wherein the control device (15) cooperates with a control valve (17) for adjusting the cooling fluid amount flowing through the heat exchanger (9) of the condenser device (5).

9. The Clausius-Rankine cycle according to claim 8, wherein the control valve (17) is arranged in at least one of the cooling cycle (8) and to the condenser device (5), wherein the control valve (17) is in particular in the housing (12) of the condenser device (5).

10. The Clausius-Rankine cycle according to claim 5, wherein the control device (15) adjusts the amount of the working fluid circulating in the Clausius-Rankine cycle (1) in the sense of a regulation or in the sense of a control.

11. A Motor vehicle with a Clausius-Rankine cycle comprising