DE102010003906A1 - internal combustion engine - Google Patents

Abstract

In an internal combustion engine (1) with a system (3) for utilizing waste heat of the internal combustion engine (1) by means of the Rankine cycle, comprising a coolant circuit (4) with at least one coolant line (5) through which coolant flows for cooling the internal combustion engine ( 1) and a coolant heat exchanger (7) for cooling the coolant, a circuit with lines (13) with a working medium, in particular water, to form the system (3), a working medium pump (14) for conveying the working medium, at least one evaporator (15 ) for vaporizing the liquid working medium, an expansion machine (18), a condenser (19) for liquefying the vaporous working medium, wherein the condenser (19) as a condenser heat exchanger (20) in the coolant circuit (4) of the internal combustion engine (1) is integrated for liquefaction the working medium by means of a heat transfer from the working fluid to the coolant, vorzugswei se a collecting and surge tank (21) for the liquid working fluid, the Clausius-Rankine cycle process should have a high efficiency in a simple structure of the internal combustion engine (1). This object is achieved in that the condenser heat exchanger (20) in the coolant circuit (4) in the flow direction of the coolant, in particular directly after the coolant heat exchanger (7) is integrated.

Description

The invention relates to an internal combustion engine having a system for utilizing waste heat of the internal combustion engine by means of the Rankine cycle according to the preamble of claim 1 and a method for operating an internal combustion engine having a system according to the preamble of claim 8.

Internal combustion engines are used in various technical applications for converting thermal energy into mechanical energy. In motor vehicles, especially in trucks, internal combustion engines are used to move the motor vehicle. The efficiency of internal combustion engines can be increased by the use of systems for using waste heat of the internal combustion engine by means of the Rankine cycle. The system converts waste heat from the internal combustion engine into mechanical energy. The system comprises a circuit with lines with a working medium, eg. As water, a working medium pump for conveying the working fluid, an evaporator for vaporizing the liquid working fluid, an expansion machine, a condenser for liquefying the vaporous working fluid and a collecting and expansion tank for the liquid working fluid. By using such systems in an internal combustion engine, in an internal combustion engine having such a system as a component of the internal combustion engine, the overall efficiency of the internal combustion engine can be increased.

When using an internal combustion engine with this system in a motor vehicle, d. H. In a mobile application of the internal combustion engine, a coolant circuit of the internal combustion engine is generally used to cool the condenser. The condenser is thus designed as a condenser heat exchanger and integrated into the coolant circuit. The coolant circuit has coolant lines through which coolant flows. The condenser heat exchanger is integrated in the flow direction of the coolant after the internal combustion engine, so that the coolant is passed into the condenser heat exchanger after flowing through the internal combustion engine, wherein the coolant is heated in the internal combustion engine. Only after flowing through the Kondensatorwärmeübertragers the coolant is cooled in a coolant heat exchanger and then re-introduced into the engine. In the coolant line from the condenser heat exchanger to the coolant heat exchanger, a 3/2-way valve is installed, so that from the 3/2-way valve, the coolant can be passed either through the coolant heat exchanger and / or through a bypass coolant line. The bypass coolant line directs the coolant past the coolant heat exchanger directly into the internal combustion engine. The refrigerant conducted into the condenser heat exchanger has a relatively high temperature because the refrigerant has first been heated in the engine and then directly supplied to the condenser heat exchanger. The coolant is cooled after discharging from the condenser heat exchanger in the coolant heat exchanger. The efficiency of the system for converting waste heat of the internal combustion engine into mechanical energy, however, is greater, the lower the temperature of the working medium is immediately after the discharge of the condenser heat exchanger. Thus, such a system formed in a disadvantageous low efficiency.

Therefore, the object of the present invention is to provide an internal combustion engine and a method for operating an internal combustion engine with a system for utilizing waste heat of an internal combustion engine by means of the Rankine cycle process, in which the Rankine cycle process has a high efficiency having a simple structure of the internal combustion engine.

This object is achieved with an internal combustion engine having a system for utilizing waste heat of the internal combustion engine by means of the Rankine cycle process comprising a coolant circuit with at least one coolant line through which coolant flows for cooling the internal combustion engine and a coolant heat exchanger for cooling the coolant, a circuit with lines with a working medium, in particular water, to form the system, a working medium pump for conveying the working medium, at least one evaporator for vaporizing the liquid working medium, an expansion machine, a condenser for liquefying the vaporous working medium, wherein the capacitor integrated as a condenser heat exchanger in the coolant circuit of the internal combustion engine is for liquefying the working fluid by means of a heat transfer from the working fluid to the coolant, preferably a collecting and surge tank for d as liquid working medium, wherein the condenser heat exchanger is integrated into the coolant circuit in the flow direction of the coolant, in particular directly after the coolant heat exchanger.

In the condenser heat exchanger, heat is transferred from the working fluid of the system to the coolant of the coolant circuit, thereby transferring the working fluid from a vaporous to a liquid state of matter, ie, condensing it. Inside the coolant circuit is the temperature of the coolant after passing through and cooling in the coolant heat exchanger lowest. The arrangement of the condenser heat transfer in the coolant circuit in the flow direction of the coolant to the coolant heat exchanger can thus be provided to the condenser heat exchanger coolant at a very low temperature level. The net power or the efficiency of the system is essentially determined by the pressure difference at the expansion machine. This pressure difference is in turn determined by the pressure at the outlet of the condenser and this in turn by the temperature of the working medium after exiting the condenser or the condenser heat exchanger. By the use of coolant, which is introduced immediately after passing through the coolant heat exchanger in the condenser or the condenser heat exchanger, thus the working fluid in the condenser heat exchanger can be cooled particularly strong and thus a particularly high efficiency or a particularly high efficiency of the system can be achieved.

An immediate arrangement of the Kondensatorwärmeübertragers in the flow direction of the coolant after the coolant heat exchanger means preferably that no components are present in the coolant lines between the coolant heat exchanger and the condenser heat exchanger, which change, for. B. more than 0.5 ° C, 1 ° C, 2 ° C, 3 ° C, 5 ° C or 10 ° C, in particular an increase, condition to a greater extent the temperature of the coolant. In particular, the internal combustion engine is not integrated between the coolant heat exchanger and the condenser heat exchanger because the internal combustion engine greatly heats the coolant.

In particular, the condenser heat exchanger is integrated in the coolant circuit in the flow direction of the coolant, in particular directly before the internal combustion engine.

In another embodiment, the coolant circuit has a bypass coolant line for diverting the coolant around the coolant heat exchanger and / or the coolant circuit has only one coolant heat exchanger.

In a supplementary embodiment, the amount of coolant which can be conducted through the coolant heat exchanger and the bypass coolant line can be controlled and / or regulated by means of a control element integrated in the coolant circuit, in particular a 3/2-way valve.

Preferably, the control element can be actuated by means of a temperature sensor and a control and / or regulating device, and preferably the control element is integrated into the coolant circuit in the flow direction of the coolant between the condenser and the internal combustion engine. The temperature sensor is preferably arranged in the coolant line from the control member to the internal combustion engine and thus detects the temperature of the coolant, which is introduced into the internal combustion engine. The bypass coolant line removes coolant from the engine to the coolant radiator and then directs it back to the coolant line from the control member to the engine. This can be controlled and / or regulated by the control member, which amount of coolant flows after exiting the internal combustion engine in the coolant radiator and thus in the condenser heat exchanger and the amount of coolant flowing through the bypass coolant line, after the control member again fed directly to the engine and thus not cooled. Thus, the temperature of the coolant supplied to the engine can be controlled and / or regulated.

In one variant, a coolant circulation pump for conveying the coolant is integrated in the coolant circuit.

The at least one evaporator is expediently designed as an evaporator exhaust gas heat exchanger through which exhaust gas from the internal combustion engine and working medium of the system flows, and / or evaporator exhaust gas recirculation heat exchanger for the heat conduction of heat from the exhaust gas to the working medium. Heat from the exhaust gas is thus transferred from the exhaust gas to the working medium, so that the working medium evaporates.

Method according to the invention for operating an internal combustion engine with a system for utilizing waste heat of an internal combustion engine by means of the Rankine cycle, in particular an internal combustion engine described in this patent application, comprising the steps of: passing coolant through a coolant circuit of the internal combustion engine, heating the coolant in an internal combustion engine Cooling the coolant in a coolant heat exchanger, directing coolant of the coolant circuit and a working medium of the system through a condenser heat exchanger as a condenser, so that heat is transferred from the working fluid to the coolant and condenses the working fluid in the condenser, wherein the coolant after passing through the coolant heat exchanger, in particular exclusively, is passed into the condenser heat exchanger and preferably no or only a slight change in temperature of the Küh occurs. A small one Temperature change of the coolant means that the temperature changes only less than 10 ° C, 7 ° C, 5 ° C, 3 ° C, 2 ° C or 1 ° C.

In a further embodiment, the coolant, in particular exclusively, is passed after passing through the condenser heat exchanger into the internal combustion engine and / or into the coolant heat exchanger, and preferably no or only a slight temperature change of the coolant occurs. A small temperature change of the coolant means that the temperature changes only less than 10 ° C, 7 ° C, 5 ° C, 3 ° C, 2 ° C or 1 ° C.

In particular, it is controlled and / or regulated by a control member as a function of the temperature of the coolant, which amount of the coolant of the coolant passed through the condenser heat exchanger is passed through the internal combustion engine and / or the coolant heat exchanger.

In a further embodiment, the expansion machine is a turbine or a reciprocating piston engine.

In a further embodiment, the system comprises not only an evaporator but also a superheater and the superheater is arranged in a flow direction of the working medium downstream of the evaporator. Preferably, the evaporator and the superheater are a component.

In a further embodiment, the system comprises a recuperator, by means of which heat can be transferred from the working medium after flowing through the expansion machine to the working medium in front of the evaporator.

In a further embodiment of the system as part of the internal combustion engine, the waste heat of the exhaust main flow of the engine and / or the waste heat of the exhaust gas recirculation and / or waste heat of the compressed charge air and / or the heat of a coolant of the engine can be used. The system thus converts the waste heat of the internal combustion engine into mechanical energy, thereby advantageously increasing the efficiency of the internal combustion engine. Preferably, the system comprises a plurality of evaporators.

In a further embodiment, the system comprises a generator. The generator is drivable by the expansion machine, so that the system can thus provide electrical energy or electricity.

In a further embodiment, the working medium of the system is water as pure substance, R245fa, ethanol (pure substance or mixture of ethanol with water), methanol (pure substance or mixture of methanol and water), longer-chain alcohols C5 to C10, longer-chain hydrocarbons C5 (pentane) to C8 (Octane), pyridine (pure or mixture of pyridine with water), methylpyridine (pure or mixture of methylpyridine with water), trifluoroethanol (pure or mixture of trifluoroethanol with water), hexafluorobenzene, at least one silicone oil, silicone oils, a water / ammonia solution and / or a water-ammonia mixture used.

In the following, an embodiment of the invention will be described in more detail with reference to the accompanying drawings. It shows:

1 a highly simplified representation of an internal combustion engine with a system for using waste heat of the internal combustion engine.

In 1 is as reciprocating internal combustion engine 2 trained internal combustion engine 1 presented a system 3 for the use of waste heat of the internal combustion engine 1 Having the Clausius-Rankine cycle process. The internal combustion engine 1 has a charge air compressor 24 on. The charge air compressor 24 sucks fresh air 32 through a fresh air line 23 and compresses the fresh air 32 in a charge air line 27 and one in the charge air line 27 built-in intercooler 28 cools the charge air before feeding to the engine 1 off, adding the heat to cooling air 9 is delivered. Through an exhaust pipe 33 becomes exhaust from the combustion engine 1 slips off and into an exhaust gas turbine 25 , an exhaust aftertreatment unit 31 and one as evaporator exhaust gas heat exchanger 16 trained evaporator 15 cooled on then the exhaust gas 26 directed into the environment. The of the exhaust 26 driven exhaust gas turbine 25 drives the charge air compressor 24 at. It also becomes part of the engine 1 discharged exhaust gas 26 through an exhaust gas recirculation line 29 with an exhaust valve 30 the charge air line 27 supplied and previously through a Verdampferabgasrückführwärmeübertrager 17 directed. That through the exhaust pipe 33 from the internal combustion engine 1 derived exhaust 26 will not pass through the evaporator exhaust gas recirculation heat exchanger 17 directed.

A coolant circuit 4 with coolant lines 5 is flowed through by coolant and used to cool the engine 1 , This is in the coolant circuit 4 a coolant heat exchanger 7 integrated. That of the coolant on the internal combustion engine 1 absorbed heat is in the coolant heat exchanger 7 to the ambient air as cooling air 9 votes. One in the Coolant circuit 4 integrated coolant circulation pump 10 Promotes the coolant in the coolant lines 5 , A fan 8th promotes the cooling air 9 to the coolant heat exchanger 7 and to the intercooler 28 ,

The system 3 has lines 13 with a working medium. In the cycle with the working medium are an expansion machine 18 , a capacitor 19 as a condenser heat exchanger 20 , a collection and equalization tank 21 and a working medium pump 14 and two evaporators 15 integrated. The two evaporators 15 are the evaporator exhaust gas heat exchanger 16 in which the working fluid of waste heat through the exhaust pipe 33 is passed vaporized and the evaporator exhaust gas recirculation heat exchanger 17 in which the working fluid from that through the exhaust gas recirculation line 29 led exhaust gas is evaporated. By means of a 3/2-way valve 22 in the pipes 13 of the system 3 can be controlled and / or regulated, which amount of working fluid through the evaporator exhaust gas heat exchanger 16 and the evaporator exhaust gas recirculation heat exchanger 17 is directed. From a working medium pump 14 is the liquid working fluid from the collecting and expansion tank 21 sucked and raised to a higher pressure level in the circuit, in the evaporator 15 pumped and then evaporates the liquid working fluid in the evaporators 15 and then perform in the expansion machine 13 mechanical work by the gaseous working medium, in particular water, expands and subsequently has a low pressure. In the condenser 19 as a condenser heat exchanger 20 the gaseous working fluid is liquefied and then back to the collecting and expansion tank 15 fed. The of the expansion machine 13 provided mechanical energy can for example be used directly for locomotion of a truck, not shown, or be converted into electrical energy with a generator, not shown.

That from the coolant heat exchanger 7 discharged coolant is directly, ie with substantially no change in temperature, the condenser heat exchanger 20 through the coolant line 5 fed.

For cooling the working medium in the condenser heat exchanger 20 Only coolant is used, which after passing through the coolant heat exchanger 7 in the coolant heat exchanger 7 has been cooled. This can be the capacitor heat exchanger 20 Coolant can be provided at a very low temperature level, thus providing high system performance 3 as a waste-heat recovery system 3 be achieved. With a 3/2-way valve 12 trained controlling body 11 is the temperature of the coolant in the coolant circuit 4 controlled and / or regulated. A bypass coolant line 6 removed from the coolant line 5 from the internal combustion engine 1 to the coolant heat exchanger 7 Coolant and passes this to the 3/2-way valve 12 , At the 3/2-way valve 12 This may be from the coolant line described above 5 removed coolant again the coolant line 5 which are supplied by the 3/2-way valve 12 to the internal combustion engine 1 leads. In this coolant line 5 from the 3/2-way valve 12 to the internal combustion engine 1 is also the coolant circulation pump 10 integrated. The more coolant from the bypass coolant line 6 the coolant line 5 between the internal combustion engine 1 and the coolant heat exchanger 7 is removed, the less refrigerant is through the coolant heat exchanger 7 passed and the more the temperature rises in the coolant and vice versa. An unillustrated temperature sensor in the coolant circuit 4 detects the temperature of the coolant and controls and / or regulates this according to a predetermined setpoint. This temperature sensor, not shown, is preferably in the coolant line 5 from the controller 11 to the internal combustion engine 1 built-in. Suitably, this temperature sensor, not shown, part of the 3/2-way valve 12 , The setpoint for the temperature of the coolant, which is in the coolant line 5 the internal combustion engine 1 is supplied, for example, lies in a range between 85 ° C and 95 ° C.

Will the internal combustion engine 1 used for example in a truck and points at the start of the engine 1 the internal combustion engine 1 a still very low operating temperature, is from the 3/2-way valve 12 the vast majority of the through the coolant line 5 outflowing coolant from the internal combustion engine 1 through the bypass coolant line 6 directed and thus not in the coolant heat exchanger 7 cooled and then immediately back to the internal combustion engine 1 fed. Thus, only a small volume flow flows through the coolant heat exchanger 7 and is strongly cooled. This greatly cooled coolant can thus in the condenser heat exchanger 20 the working medium of the system 3 cool down a lot. After the operating temperature of the internal combustion engine rises, a higher proportion of the combustion engine is released 1 discharged coolant through the coolant heat exchanger 7 passed and thereby the coolant in the coolant heat exchanger 7 cooled less. Nevertheless, the condenser heat exchanger can 20 even at a higher level through the coolant heat exchanger 7 and also with the condenser heat exchanger 20 directed volumetric flow at the coolant in the condenser heat exchanger 20 the working fluid to be cooled to a relatively low temperature, because the condenser heat exchanger 20 directly from the coolant heat exchanger 7 derived cooled coolant is supplied.

In a second, not shown embodiment of the internal combustion engine 1 indicates the coolant circuit 4 two coolant heat exchangers 7 on. In a first main circuit of the coolant circuit 4 is essentially with the first coolant radiator of the internal combustion engine 1 cooled. From the main circuit coolant is removed as a partial flow in an additional circuit and then fed to the second coolant heat exchanger. After passing through the second coolant heat exchanger, the coolant, in particular immediately thereafter, the condenser heat exchanger 20 fed. The first coolant radiator can in the flow direction of the coolant before the condenser heat exchanger 20 according to the embodiment in 1 , but also after the condenser heat exchanger 20 be arranged. To a sufficiently low temperature level of the coolant in the condenser heat exchanger 20 to have available, the coolant is additionally cooled at the second coolant heat exchanger. The coolant supplied to the second coolant heat exchanger is thereby for example directly in the flow direction of the coolant from the first coolant cooler or from the internal combustion engine 1 derived.

Overall, with the internal combustion engine according to the invention 1 significant benefits. That the condenser heat exchanger 20 supplied coolant has a very low temperature level, because the condenser heat exchanger 20 in the flow direction of the coolant immediately after the coolant heat exchanger 7 is arranged. This can increase the net performance of the system 3 for the conversion of waste heat of the internal combustion engine 1 be substantially increased in mechanical energy with a low technical effort.

LIST OF REFERENCE NUMBERS

1

internal combustion engine

2

reciprocating engine

3

system

4

Coolant circuit

5

Coolant line

6

Bypass coolant line

7

Coolant heat exchanger

8th

fan

9

cooling air

10

Coolant circulation pump

11

control element

12

3/2-way valve in coolant circuit

13

management

14

Working fluid pump

15

Evaporator

16

Evaporator exhaust gas heat exchanger

17

Evaporator exhaust gas recirculation heat exchanger

18

expander

19

capacitor

20

Condenser heat exchanger

21

Collection and equalization tank

22

3/2-way valve in system

23

Fresh air line

24

Charge air compressor

25

exhaust turbine

26

exhaust

27

Turbo pipe

28

Intercooler

29

Exhaust gas recirculation line

30

exhaust valve

31

exhaust gas treatment unit

32

fresh air

33

exhaust pipe

Claims (10)

Internal combustion engine ( 1 ) with a system ( 3 ) for the use of waste heat of the internal combustion engine ( 1 ) by means of the Clausius-Rankine cycle, comprising - a coolant circuit ( 4 ) with at least one coolant line through which coolant flows ( 5 ) for cooling the internal combustion engine ( 1 ) and a coolant heat exchanger ( 7 ) for cooling the coolant, - a circuit with lines ( 13 ) with a working medium, in particular water, to form the system ( 3 ), - a working medium pump ( 14 ) for conveying the working medium, - at least one evaporator ( 15 ) for vaporizing the liquid working medium, - an expansion machine ( 18 ), - a capacitor ( 19 ) for liquefying the vaporous working medium, the condenser ( 19 ) as a condenser heat exchanger ( 20 ) in the coolant circuit ( 4 ) of the internal combustion engine ( 1 ) is integrated for liquefying the working medium by means of a heat transfer from the working medium to the coolant, - preferably a collecting and compensating container ( 21 ) for the liquid working medium, characterized in that the condenser heat exchanger ( 20 ) in the coolant circuit ( 4 ) in Flow direction of the coolant, in particular immediately after the coolant heat exchanger ( 7 ) is integrated. Internal combustion engine according to claim 1, characterized in that the condenser heat exchanger ( 20 ) in the coolant circuit ( 4 ) in the flow direction of the coolant, in particular directly, in front of the internal combustion engine ( 1 ) is integrated. Internal combustion engine according to claim 2, characterized in that the coolant circuit ( 4 ) a bypass coolant line ( 6 ) for diverting the coolant around the coolant heat exchanger ( 7 ) and / or the coolant circuit ( 4 ) only one coolant heat exchanger ( 7 ) having. Internal combustion engine according to claim 3, characterized in that by means of a in the coolant circuit ( 4 ) integrated control organ ( 11 ), in particular a 3/2-way valve ( 12 ) passing through the coolant heat exchanger ( 7 ) and the bypass coolant line ( 6 ) controllable amount of coolant is controllable and / or regulated. Internal combustion engine according to claim 3 or 4, characterized in that by means of a temperature sensor and a control and / or regulating device, the control member ( 11 ) and preferably the control member ( 11 ) in the coolant circuit ( 4 ) in the flow direction of the coolant between the condenser ( 19 ) and the internal combustion engine ( 1 ) is integrated. Internal combustion engine according to one or more of the preceding claims, characterized in that in the coolant circuit ( 4 ) a coolant circulation pump ( 10 ) is integrated for conveying the coolant. Internal combustion engine according to one or more of the preceding claims, characterized in that the at least one evaporator ( 15 ) as one of exhaust gas of the internal combustion engine ( 1 ) and working medium of the system ( 3 ) through-flow evaporator exhaust gas heat exchanger ( 16 ) and / or evaporator exhaust gas recirculation heat exchanger ( 17 ) is formed for the heat conduction of heat from the exhaust gas to the working medium. Method for operating an internal combustion engine ( 1 ) with a system ( 3 ) for the use of waste heat of the internal combustion engine ( 1 ) by means of the Clausius-Rankine cycle, in particular an internal combustion engine ( 1 ) according to one or more of the preceding claims, comprising the steps of: - passing coolant through a coolant circuit ( 4 ) of the internal combustion engine ( 1 ), - heating of the coolant in the internal combustion engine ( 1 ), - cooling the coolant in a coolant heat exchanger ( 7 ), - Guiding coolant of the coolant circuit ( 4 ) and a working medium of the system ( 3 ) by a condenser heat exchanger ( 20 ) as a capacitor ( 19 ), so that heat is transferred from the working medium to the coolant and the working medium in the condenser ( 19 ) condensed, characterized in that the coolant after passing through the coolant heat exchanger ( 7 ), in particular exclusively, in the condenser heat exchanger ( 20 ) is conducted and preferably no or only a slight change in temperature of the coolant occurs. A method according to claim 8, characterized in that the coolant, in particular exclusively, after passing through the condenser heat exchanger ( 20 ) in the internal combustion engine ( 1 ) and / or in the coolant heat exchanger ( 7 ) is conducted and preferably no or only a slight change in temperature of the coolant occurs. Method according to claim 9, characterized in that by a control member ( 11 ) is controlled and / or regulated as a function of the temperature of the coolant, which amount of the coolant through the condenser heat exchanger ( 20 ) conducted coolant by the internal combustion engine ( 1 ) and / or the coolant heat exchanger ( 7 ).

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