EP2601389B1 - Expansion device for use in a working medium circuit, and method for operating an expansion device - Google Patents

Description

The invention relates to an expansion device for use in a working fluid circuit according to the features of the preamble of claim 1. Furthermore, the invention relates to a method for operating an expansion device according to the features of the preamble of claim 4. Today's internal combustion engines have an efficiency of up to 40 percent , The losses are mainly released as heat to a coolant and exhaust heat.

In the prior art, there are various methods and devices by means of which electrical and / or mechanical energy is obtained from the exhaust heat and / or the coolant heat.

In this case, thermal energy is converted into mechanical energy by means of a Clausius-Rankine cycle or an Organic Rankine cycle. In such a Clausius-Rankine cycle usually an expansion device is arranged, which is designed as an axial piston machine or as a piston expander. US 2004/255591 A1 shows an expansion device and the associated method for operating this expansion device in a working fluid circuit, wherein within the working fluid circuit, a process flow is performed, which corresponds to that of a Rankine Rank cycle or an Organic Rankine cycle. In this case, the expansion device is designed as Scrollarbeitsmaschine, which can be flowed through in the expansion direction of a circulating in the working fluid circuit working fluid. Two bypass openings and one slide are provided, whereby an expansion ratio of the scrolling machine by means of a slider is provided via the bypass valve. Openings is changeable. By opening the bypass openings an increased absorption behavior of the scroll machine can be displayed.

JP2006046223A shows a Scrollexpander with a fixed scroll plate and a movable scroll. In a modification, a valve for flow control is provided in the feed of the working medium to a fluid space of the scroll expander. In one embodiment, this valve is designed as an electromagnetic valve. When the electromagnetic valve is opened and closed relatively frequently within a short time and the opening and closing interval of this electromagnetic valve is adjusted, the amount of the working fluid supplied from an injection to a fluid space of the scroll expander can be adjusted.

The invention has for its object to provide an improved, in particular energy-efficient expansion device for use in a working fluid circuit and an improved method for operating an expansion device. With regard to the device, the object is achieved by an expansion device for use in a working fluid circuit having the features of claim 1. With regard to the method, the object is achieved by a method for operating an expansion device with the features of claim 4.

Preferred embodiments and further developments of the invention are specified in the dependent claims.

The expansion device for use in a working fluid circuit, wherein within the working fluid circuit, a process flow is feasible, which corresponds to a Rankine Ranking cycle or an Organic Rankine cycle process, is designed as Scrollarbeitsmaschine which is flowed through in the expansion direction of a working fluid circulating in the working fluid ,

According to the invention, several inlets are arranged in a fixed scroll base plate along an expansion path, by means of which working means of the working medium circuit of the expansion device can be fed. In this case, each inlet in the fixed scroll base plate is assigned a separate timing valve, with which the working medium of the working medium circuit of the expansion device is controlled and / or regulated fed. According to the invention, an expansion ratio of the scrolling machine and / or a supply of working means to the scrolling machine is changeable.

Particularly advantageously, by means of the expansion device according to the invention, a rotational movement, for example for driving an electric generator, directly generated.

From this rotational movement results in a low-vibration running of the expansion device, in particular in comparison to an alternating movement of a conventional piston expander, in which the alternating movement also still needs to be converted by means of a frictional transmission in a rotary motion.

In one possible embodiment, the expansion device is characterized by a fixed scroll element, a movable scroll element and an eccentric drive, the fixed scroll element having a fixed scroll base plate and a fixed scroll spiral wall extending from the fixed scroll base plate, the movable scroll element being a movable scroll base plate and a movable scroll spiral wall comprising, extending from the movable scroll base plate, the movable scroll spiral wall and the fixed scroll spiral wall engaging with each other so as to form at least one expansion area between the movable scroll member and the fixed scroll member, the movable scroll member being movable relative to the fixed scroll member by means of the scroll scroll member Exzentertriebs is circularly movable and change the size of the expansion area during this circular motion along an expansion path is derbar. Within such an expansion device is advantageously a number of components compared to conventional expansion devices, which are designed for example as axial piston or piston expander significantly reduced. In particular, the number of moving components is reduced.

Advantageously, a working means of the working medium circuit of the expansion device can be fed centrally.

In one embodiment of the invention, the circulating in the working fluid working means of the expansion device can be fed by means of a central inlet in the fixed scroll base plate. According to the invention, the working medium of the working medium circuit of the expansion device can be supplied by means of a plurality of inlets in the fixed scroll base plate along the expansion path. According to the invention, the working means of the working medium circuit of the expansion device is controlled by means of clock valves and / or regulated fed. According to the invention, each inlet in the fixed scroll base plate is assigned a separate clock valve, which is particularly advantageously separately controllable and / or controllable.

From this variable supply of the working fluid into the expansion device results in a variably adjustable pressure level of the working fluid in the expansion device and a variably adjustable working fluid throughput in the expansion device.

This simple control and / or regulation of the working fluid flow facilitates a system design of the working fluid circuit.

An expansion pressure gradient within the expansion device is dependent on the geometry of the scroll spiral walls. This geometry is thus expediently adaptable in the construction of the expansion device to the respective conditions in the working medium circuit.

The Scrollspiralwände are advantageously formed as Archimedean spiral surfaces, which are arranged rotated by 180 ° clockwise against each other.

It is thus possible with very simple means to vary the working fluid flow in the working fluid circuit and / or in the expansion device independently of a pump throughput of a arranged in the working fluid circuit conveyor unit.

Particularly advantageously, a pressure difference between a high-pressure and a low-pressure region, also referred to below as the expansion gradient, of the working fluid circuit can be reduced and / or adapted by means of an increase in the number of timing valves arranged along the expansion path.

From such a reduction results in numerous advantages, for example, can be avoided by a simultaneous increase in the working fluid flow rate in the working fluid circuit overheating of the working fluid.

Typically, a low expansion gradient is beneficial in the low engine load range, while a high expansion gradient is desirable in the high engine load range. By means of the expansion device a particularly variable expansion of the working means can be realized, whereby the working fluid circuit and / or the expansion device is flexibly adaptable to changing heat quantity entries / is.

In the method for operating an expansion device in a working fluid circuit, wherein within the working fluid circuit, a process sequence is carried out, which corresponds to a Rankine Ranking cycle or an Organic Rankine cycle process, a movable scroll element relative to a fixed scroll element by means of a Exzentertriebs in a Circular motion moves and the size of an expansion area formed between the movable scroll member and the fixed scroll member is changed during this circular motion along an expansion path.

According to the invention, the method for operating an expansion device designed as a scrolling machine with at least one cycle valve is characterized in that an expansion ratio of the expansion device and a supply of working fluid to the expansion device are changed by means of at least one cycle valve.

A working medium flow supplied to the expansion device is advantageously regulated and / or controlled by means of the separately or jointly actuatable clock valves.

By means of the method is particularly advantageously allows a variable expansion of the working fluid in the expansion device.

Thus, almost all, incurred in the operation of an internal combustion engine loss heat energy in the working fluid circuit and in the expansion device can be used, the expansion device is adaptable to different, operating state-dependent incurred loss of heat energy quantities.

As a result, an increase in efficiency of the working medium circuit and the expansion device is achieved as an advantage of the invention. By using the heat loss of the internal combustion engine, the efficiency of the internal combustion engine is further increased.

The expansion device and the method for operating the expansion device can be used particularly advantageously within each operating on the principle of Clausius-Rankine cycle process or the Organic Rankine cycle working fluid circuit to realize optimized waste heat utilization of the internal combustion engine.

Embodiments of the invention are explained in more detail below with reference to drawings.

Fig. 1

schematisch einen Arbeitsmittelkreislauf mit Expansionsvorrichtung,

Fig. 2

schematisch eine Ausführungsvariante einer Expansionsvorrichtung, die nicht alle Merkmale der Erfindung zeigt,

Fig. 3

schematisch eine alternative, erfindungsgemäße Ausführungsvariante der Expansionsvorrichtung, und

Fig. 4

schematisch ein Verfahrensablaufdiagramm vom Betrieb der Expansionsvorrichtung.

Showing:

Fig. 1

schematically a working medium circuit with expansion device,

Fig. 2

1 schematically shows an embodiment variant of an expansion device which does not show all the features of the invention,

Fig. 3

schematically an alternative, inventive variant of the expansion device, and

Fig. 4

schematically a process flow diagram of the operation of the expansion device.

Corresponding parts are provided in all drawings with the same reference numerals.

The expansion device 1 is part of a working fluid circuit AK, in which a working fluid AM is guided and wherein a process performed in the working fluid circuit AK process corresponds to a so-called Clausius-Rankine cycle process or an Organic Rankine cycle process, as in FIG. 1 shown.

This working fluid circuit AK comprises a conveyor unit F, a heat exchanger W, the expansion device 1 and a condenser K.

In the course of the Clausius-Rankine cycle process or the Organic Rankine cycle process, the liquid working medium AM is supplied to the heat exchanger W in a working medium flow from the conveying unit F. In the heat exchanger W, the liquid working fluid AM is heated under constant pressure using the heat loss of an internal combustion engine such that it evaporates.

The heat exchanger W can use, for example, as exhaust gas heat exchanger, exhaust gas recirculation heat exchanger and / or coolant heat exchanger exhaust heat and / or heat of a coolant of the internal combustion engine to heat the liquid working fluid AM and evaporate.

The high-pressure vaporous working medium AM is supplied to the expansion device 1 and is expanded in an adiabatic or almost adiabatic expansion to a vaporous working medium AM at atmospheric pressure. In the expansion device 1, a kinetic energy of the vaporous working medium AM is converted into a mechanical energy.

For example, the generated mechanical energy can be converted in a coupling of the expansion device 1 with an electric generator, not shown in an electrical energy. This electrical energy can z. B. are used to drive an electric motor, not shown, which acts to support the internal combustion engine. Furthermore, the means of the expansion device 1 generated mechanical energy can be supplied directly via not shown arrangements of the internal combustion engine for support.

After the expansion, the vaporous working medium AM is supplied to the condenser K, in which the vaporous working medium AM is isobarically or almost isobarically condensed by means of cooling and thus converted into a liquid state of aggregation, so that the liquid working medium AM can be fed to the conveying unit F on the input side.

In FIG. 2 schematically a variant of the expansion device 1 is shown.

The expansion device 1 is preferably designed as a scrolling machine, which can be flowed through in the expansion direction by the circulating in the working fluid circuit AK working means AM.

For this purpose, the expansion device 1 comprises a fixed scroll element 2 and a movable scroll element 3. The fixed scroll element 2 has a round or disc-shaped fixed scroll base plate 4 and a fixed scroll spiral wall 5 which extends from the fixed scroll base plate 4 in the direction of the movable scroll element 3. An inlet 6.1 is substantially in the middle of the fixed scroll base plate 4, for example, centrally formed and acted upon by the working means AM from the working fluid circuit AK.

The movable scroll member 3 has a circular or disc-shaped movable scroll base plate 7 and a movable scroll spiral wall 8 extending from the movable scroll base plate 7 toward the fixed scroll member 2.

The Scrollspiralwände 5 and 8 are formed as so-called Archimedean spiral surfaces, which are arranged rotated by 180 ° clockwise against each other.

An expansion ratio within the expansion device 1, which designates a pressure difference between a high-pressure and a low-pressure region of the expansion device 1, is dependent on the geometry of the scroll spiral walls 5 and 8. This geometry can thus be suitably adapted in the construction of the expansion device 1 to the respective conditions in the working medium circuit AK.

The fixed scroll spiral wall 5 is engaged with the movable scroll spiral wall 8 so as to form at least one expansion area 9.1 between the fixed scroll member 2 and the movable scroll member 3.

Depending on the geometry of the scroll spiral walls 5 and 8, between the stationary scroll element 2 and the movable scroll element 3 there are further expansion areas 9.2 to 9.5, as in FIG FIG. 1 represented, educable.

These expansion areas 9.1 to 9.5 are variable in size and move in a manner to be described circular along an expansion path between the scroll spiral walls 5 and 8.

The expansion path is the path which each expansion region 9.1 to 9.5 describes during a circular motion of the movable scroll member 3 relative to the fixed scroll member 2.

Arranged on the movable scroll base plate 7 is an eccentric drive, not shown, which on the one hand enables a circular movement of the movable scroll element 3 relative to the stationary scroll element 2 and on the other hand emits mechanical energy in the form of a rotational movement of a shaft (not shown) connected to the eccentric drive.

The eccentric drive is advantageously designed such that the movable scroll element 3 is movable in a circular movement relative to the stationary scroll element 2, wherein the movable scroll element 3 does not perform any rotational movement about its own axes.

The circulating in the working fluid circuit AK working fluid AM is the expansion device 1 by means of the inlet 6.1 can be fed. Not shown in detail this inlet 6.1 is associated with a conventional timing valve, which allows control and / or regulation of the expansion device 1 can be supplied to the working fluid flow. In the context of the present invention, in addition to the inlet 6.1 further inlets are provided with corresponding timing valves along the expansion path. By means of the two outlets 10.1 and 10.2, the expanded working fluid AM from the expansion device 1 can be discharged. These outlets 10.1 and 10.2 are dependent the circular movement of the movable scroll member 3 relative to the fixed scroll member 2 at the respective outer end 11.1 and 11.2 of the scroll spiral walls 5 and 8 periodically formed.

In FIG. 3 schematically an alternative, inventive embodiment of the expansion device 1 is shown.

In addition to the in FIG. 1 6.1 described further inlets 6.2 to 6.5 are arranged in the fixed scroll base plate 4. These inlets 6.2 to 6.5 are arranged along the expansion path such that the expansion areas 9.1 to 9.5 can be acted on during their movement along the expansion path with working means AM from the inlets 6.2 to 6.4.

Not shown in detail each inlet 6.1 to 6.5 is assigned a separate clock valve. By means of these separately or jointly actuable clock valves, an individual control and / or regulation of each of the expansion device 1 by means of the inlets 6.1 to 6.5 can be supplied partial working medium flow.

In FIG. 4 schematically a process flow diagram of the operation of the expansion device 1 is shown.

To illustrate the operating behavior of the expansion device 1 are in FIG. 4 the process steps S1 to S4 shown in a pie chart.

In method step S1, the centrally arranged expansion region 9.1 is acted upon by means of the inlet 6.1 with the high-pressure vaporous working medium AM from the working medium circuit AK. The outlets 10.1 and 10.2 are closed. Between the scroll spiral walls 5 and 8, further expansion areas 9.2 to 9.5 are formed along the expansion path.

By a kinetic energy generated by the expansion or expansion of the working means AM and the resulting force acting on the scroll spiral walls 5 and 8, the movable scroll spiral wall 8 and thus the movable scroll member 3 is excited to orbitally move relative to the fixed scroll member 2 ,

In method step S2, this movement, which rotates in a clockwise direction, is shown after a movement amplitude of 90 °. The expansion areas 9.1 to 9.3 have increased their volume. This results in a, in the following also referred to as expansion, pressure and / or temperature decrease of the working medium AM. The expansion areas 9.4 and 9.5 have reached their greatest volume expansion and the outlets 10.1 and 10.2 are opened. Through the outlets 10.1 and 10.2, the expanded working fluid AM is supplied to the working fluid circuit AK and liquefied in the condenser K.

In method step S3, the circular movement of the movable scroll element 3 is shown after a movement amplitude of 180 °. The expansion areas 9.1 to 9.3 increase the volume during their movement along the expansion path. The outlets 10.1 and 10.2 reach their largest opening cross section and thus support a return flow of the working medium AM into the working medium circuit AK.

In method step S4, the circular movement of the movable scroll element 3 is shown after a movement amplitude of 270 °. As a result of the circular movement of the movable scroll element 3 relative to the stationary scroll element 2, a new expansion area 9.1 'has been created, while the expansion areas 9.1 to 9.3 continue to increase and continue their movement along the expansion path in the direction of the outlets 10.1 and 10.2. The outlets 10.1 and 10.2 are almost completely closed and, as a result, the expansion areas 9.4 and 9.5 are eliminated in the further course of the circular movement of the movable scroll element 3.

After completion of a complete circular movement of the movable scroll element 3 relative to the fixed scroll element 2, the process sequence begins again in method step S1.

With the generated during the expansion of the working medium AM force a shaft, not shown, of the expansion device 1 is driven by means of the eccentric drive. As a result, for example, an electric generator can be driven directly by means of the expansion device 1.

From this rotational movement of the shaft of the expansion device 1 advantageously results in a low-vibration running of the expansion device. 1

Not closer in FIG. 4 can be arranged along the expansion path more inlets 6.2 to 6.5 in the fixed scroll base plate 4. By means of these additional inlets 6.2 to 6.5, the expansion areas 9.1 to 9.5 are acted upon during their circulation with the highly pressurized vaporous working medium AM from the working medium circuit AK.

From this variable supply of the working fluid AM in the expansion device 1 advantageously results in a variably adjustable pressure level of the working fluid AM in the expansion device 1 and / or a variable adjustable working fluid throughput in the expansion device. 1

This simple control and / or regulation of the working fluid flow AM in the expansion device 1 advantageously facilitates a system design of the working fluid circuit AK and the control and / or regulation of the working fluid circuit AK.

LIST OF REFERENCE NUMBERS

1

expansion device

2

fixed scroll element

3

movable scroll element

4

fixed scroll base plate

5

fixed scroll spiral wall

6.1 to 6.5

inlet

7

movable scroll base plate

8th

movable scroll spiral wall

9.1 to 9.5

expansion region

9.1 '

expansion region

10.1, 10.2

outlet

11.1, 11.2

The End

AK

Working agent circuit

AT THE

work equipment

F

delivery unit

K

capacitor

S1 to S4

step

W

heat exchangers

Claims (7)

1. Expansion device (1) for use in a working medium circuit (AK), wherein within the working medium circuit a process sequence can be executed which corresponds to that of a Clausius Rankine cycle or an Organic Rankine cycle, wherein the expansion device (1) is designed as a Scroll machine through which a working medium (AM) circulating in the working medium circuit (AK) can flow in the expansion direction,
   characterised in that
   along an expansion path, several inlets (6.1 to 6.5) are arranged in a stationary Scroll base plate (4), by means of which inlets (6.1 to 6.5) working medium (AM) of the working medium circuit (AK) can be fed to the expansion device (1), wherein each inlet (6.1 to 6.5) in the stationary Scroll base plate (4) is assigned a separate cycle valve whereby the working medium (AM) of the working medium circuit (AK) can be fed to the expansion device (1) under open- and/or closed-loop control.
2. Expansion device (1) according to claim 1,
   characterised in that
   each cycle valve can be controlled separately in an open and/or closed loop.
3. Expansion device (1) according to any of the preceding claims,
   characterised in that
   the expansion device (1) generates mechanical energy which can be fed to an internal combustion engine for support and/or can be converted into electric energy with an electric generator.
4. Method for operating an expansion device (1) according to any of the preceding claims, which is designed as a Scroll machine with at least one cycle valve,
   characterised in that
   by means of at least one cycle valve, an expansion ratio of the expansion device (1) and a feed of working medium (AM) to the expansion device (1) are changed.
5. Method for operating an expansion device (1) according to claim 4,
   characterised in that
   in a low engine load range of the internal combustion engine, a low expansion ratio is set, and in a high load range of the internal combustion engine, a high expansion ratio is set.
6. Method for operating an expansion device (1) according to claim 4,
   characterised in that
   a pressure differential between a high-pressure region and a low-pressure region of the working medium circuit is reduced and/or adjusted by means of increasing the number of cycle valves arranged along the expansion path.
7. Method for operating an expansion device (1) according to claim 4, the expansion device (1) being designed in accordance with claim 2,
   characterised in that
   at least one pressure level in the expansion device (1) is adjusted variably by means of at least one cycle valve.

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