CN116724167A

CN116724167A - Internal combustion power system with internal combustion engine

Info

Publication number: CN116724167A
Application number: CN202280010382.9A
Authority: CN
Inventors: M·切尔迪克; J·芬克; 贝恩德·赖特尔; F·魏辛格; R·蒙特莫尔
Original assignee: AVL List GmbH
Current assignee: AVL List GmbH
Priority date: 2021-06-11
Filing date: 2022-06-10
Publication date: 2023-09-08
Also published as: AT524859B1; JP2024523078A; AT524859A4; DE112022003032A5; WO2022256857A1

Abstract

The invention relates to an internal combustion power system (1) having an internal combustion engine (2), an exhaust gas line (3) and an AGR assembly (4), the AGR assembly (4) having a circulation section (5) for circulating exhaust gas from the exhaust gas line (3), in particular into a fuel inlet (6) of the internal combustion engine (2), wherein a first reformer (7) for reforming fuel into reformate and an evaporator (8) for evaporating fuel are provided in the circulation section (5), characterized in that a second reformer (9) is provided.

Description

Internal combustion power system with internal combustion engine

Technical Field

The invention relates to an internal combustion power system having an internal combustion engine, an exhaust gas line and an AGR assembly having a circulation section for circulating exhaust gas from the exhaust gas line, in particular to a fuel inlet of the internal combustion engine, wherein a first reformer for reforming fuel into reformate and an evaporator for evaporating fuel are arranged in the circulation section.

The invention also relates to the use of such an internal combustion engine.

Background

In addition to conventional fuels such as diesel and gasoline, alternative fuels such as rapeseed oil or ethanol have been used more and more frequently in recent years in the energy conversion sector to operate correspondingly suitable internal combustion engines. For example, DE 11 2011 101 274T5 describes a system in which the internal combustion engine is operated with ethanol. In particular, an internal combustion engine is described which has a reformer, in which a fuel, such as ethanol, can be reformed into hydrogen and methane in the exhaust gas branch by means of the reformer. The reformate may then be stored in a tank and fed from there to an internal combustion engine. Downstream of the reformer, the AGR assembly is joined to the outlet passage of the exhaust branch, whereby nitrogen oxides can be reduced.

In general, reformers are employed in such internal combustion power systems to convert fuel in order to improve its thermodynamic performance, thus improving internal combustion engine efficiency by recovering heat from the exhaust gases.

It is also known that by increasing the hydrogen concentration in the reformed fuel, the combustion speed and/or combustion period in the cylinder and combustion stability are increased, and the injection period is thereby shortened. In engine assemblies or internal combustion power systems known from the prior art, the required hydrogen is obtained by catalytic reforming of the fuel. Such reformers are directly heated by circulating hot exhaust gases. However, it has been shown that the amount of hydrogen thus obtained is insufficient to sufficiently improve the efficiency. By the method known from the prior art, the AGR rate is limited to about 20% to 30%, although hydrogen required for efficiency improvement can be produced by reforming fuel. Further efficiency improvement cannot be achieved because in the engine assembly of the known gasoline engine, the combustion in the engine operation is deteriorated at a higher AGR rate.

Disclosure of Invention

The present invention is focused on this. The object of the invention is to improve the efficiency of an internal combustion power system having a reformer.

According to the invention, the above-mentioned object is achieved in that a second reformer is provided in an internal combustion engine system of the type mentioned in the introduction.

The advantage thereby obtained is, in particular, that the heat flow in the internal combustion engine can be optimally utilized by arranging the second reformer and that the pressure requirement can be simultaneously optimally met. By means of the AGR-assembly, the exhaust heat energy can be used in an efficient way for the reforming process. By providing two reformers, the reforming process can be performed correspondingly energy-efficient. Thus, the overall efficiency of an internal combustion powertrain equipped with an AGR assembly may be improved and corresponding fuel savings achieved.

The internal combustion engine is in particular designed as a gasoline engine unit, which can be operated, for example, on gasoline.

However, ethanol or an ethanol-water mixture is preferably used as fuel. Hydrogen and methane may be obtained therefrom, in particular by means of a reformer. I.e. the reformate has a mixture comprising hydrogen and methane. Hydrogen and methane may preferably be fed to the internal combustion engine through a recycle section and combusted directly there. The fuel or the motive fuel is in particular liquid. The terms "fuel" and "power fuel" are used synonymously herein.

The AGR assembly refers to an exhaust gas recirculation assembly for returning exhaust gas from an internal combustion engine to the internal combustion engine. The AGR assembly may contain all the functional components required for the same type of exhaust gas recirculation. Internal combustion engine power system refers in particular to a mobile internal combustion engine power system for a motor vehicle, in particular a road vehicle. However, the AGR assembly may also be used stationary, for example, in a power plant with a suitable internal combustion power system.

The AGR assembly or circulation portion may be returned at two different locations, again before or at the fuel inlet: upstream or downstream of the turbine, depending on whether the recycle gas already has a high or low pressure. For this purpose, the control device is preferably arranged in the AGR-assembly, whereby one of the two paths can be selected.

The first reformer is preferably provided with a catalytic coating for reforming the exhaust gas/fuel mixture, in particular designed as a catalytic reformer. The first reformer may have a plate heat exchanger or be designed as a plate reforming heat exchanger. The reformer can thus be used for reforming an exhaust gas/fuel mixture in a space-saving and at the same time large-scale manner. The plates of the plate-type reforming exchanger are provided with a catalytic coating.

In principle, the first and second reformers can also be designed as two parts of the same reformer.

The evaporator is designed in particular as an evaporator heat exchanger and serves for evaporating liquid fuel.

Advantageously, the second reformer is designed as a reforming heat exchanger, wherein a first side of the second reformer is connected to the exhaust gas line and a second side of the reformer is connected to the circulation section. That is, the hot exhaust gas heats the reforming heat exchanger so that the circulating exhaust gas can be reformed by the heat energy. It has proven to be particularly advantageous if the second reformer has a plate heat exchanger or is designed as a plate reforming heat exchanger. The reformer can thus be used for reforming an exhaust gas/fuel mixture in a space-saving and at the same time large-scale manner. The plates of the plate-type reforming exchanger are provided with a catalytic coating on the second side for reforming the recirculating exhaust gases. The second side is advantageously arranged in the AGR-assembly or at least connected thereto.

In one embodiment, it may be advantageously provided that the second reformer is arranged in the exhaust gas line and that the circulation portion of the AGR-assembly passes through the second side of the second reformer. Upstream of the second reformer, the circulation section leads in particular to an evaporator.

It is advantageous here if a first side of the second reformer is arranged in the exhaust gas line, wherein a second side of the second reformer is connected to the circulation section. The second reformer, which is designed as a reforming heat exchanger, is thus arranged in the internal combustion power system in such a way that heat can be exchanged between the AGR-assembly and the exhaust gas line. The exhaust gases in the exhaust gas line are discharged to the outside after the reforming heat exchanger or flow through another exhaust gas treatment component or components. Upstream of the reforming heat exchanger (second reformer), a catalyst is provided in the exhaust gas line, for example. A further exhaust gas treatment component may advantageously be provided in the exhaust gas line downstream of the second reformer before the exhaust gas is discharged to the environment.

It is advantageous if the second reformer is arranged downstream of the first reformer in the circulation section, wherein the second reformer is connected to the exhaust line. That is, the second side of the reforming heat exchanger is disposed in the AGR assembly. Thus, the circulating exhaust gas in the circulating section flows first through the first reformer, then through the second reformer, and is staged for complete reforming by the two reformers. For this purpose, both reformers have a catalytic coating on the AGR side.

Fuel lines for feeding fuel into the internal combustion engine and the evaporator are advantageously provided. Fuel may be supplied to the internal combustion engine through a fuel line. Advantageously, a fuel line branch may be provided upstream of the internal combustion engine, via which liquid fuel may be fed to the evaporator for evaporation in the evaporator. In this case, the evaporator is designed as an evaporative heat exchanger. The energy required for evaporation is provided by the reformed exhaust gas, which is led through the hot side of the evaporation heat exchanger. The fuel is thus fed to the cold side of the reformer.

It is advantageous if a mixer is provided upstream of the first reformer, wherein an evaporation line for conveying evaporated fuel to the mixer is provided between the evaporator and the mixer. The evaporator is provided downstream of the second reformer in the circulation portion so that the reformed exhaust gas is supplied to the evaporator. The supplied fuel is then evaporated in an evaporator by means of the reformed exhaust gas. The fuel in gaseous state is then fed to a mixer arranged in the circulation section upstream of the first reformer. In the mixer, the gaseous fuel is mixed with the exhaust gas taken out of the exhaust gas line and fed to the first reformer to perform steam reforming. This allows the endothermic reaction in the catalyst to be supplied with sufficient energy and to be made more stable, thereby further maximizing the energy recovery effect. In addition, the amount of fuel reformed by the reformer may be increased by the energy supply. Thereby further increasing the hydrogen duty cycle and improving the efficiency of the overall engine assembly. It has been demonstrated within the scope of the invention that the process within the reformer can be directly influenced by the design and arrangement of the catalyst. One special effect is here that by reforming the fuel, the AGR error in the engine assembly can be increased. The AGR rate can thus be raised from a current limit of approximately 30% to a maximum of 45%. In a particularly advantageous way, the AGR rate is thus greater than 30% and up to 45%, preferably between 40% and 45%. The increase in AGR rate is directly dependent on the amount of hydrogen produced by reforming. The arrangement according to the invention allows for the use of system heat to generate sufficient fuel to produce hydrogen. The fuel to which the catalyst is supplied is in the form of a gaseous fuel or a vaporous fuel such as gaseous gasoline or ethanol. Thus, by the design of the engine assembly according to the invention, on the one hand, the fuel supplied to the reformer is increased by increasing the heating value, and on the other hand, the concentration of hydrogen is improved.

It is advantageous to provide heating means for heating the fuel. The heating device is arranged in the fuel line, wherein it is preferably arranged only in the portion of the fuel line that feeds fuel into the evaporator. Thus, the fuel has a prescribed temperature when entering the evaporator, so that the evaporation can be performed more efficiently. It is advantageous here to take the heating energy required for the heating device from the internal combustion engine.

A water pipe for supplying water to the internal combustion engine and perhaps to the evaporator may advantageously be provided. In order to supply water to an internal combustion engine, injectors are provided in particular. The combustion of ethanol in particular can be improved and stabilized by water. If carbon black formation in the evaporator is to be prevented or at least reduced, it is advantageous to supply water to the evaporator in addition to the fuel. It may also be advantageous in principle for the internal combustion engine to operate as an ethanol-water mixture. A separate water pipe is then no longer necessary here.

Advantageously, an AGR cooler is provided downstream of the evaporator. Downstream of the AGR cooler, the circulation part in turn leads to the internal combustion engine.

The exhaust gas line advantageously comprises at least one catalytic converter, in particular designed as a three-way catalytic converter. The catalyst is here arranged in particular upstream of the second reformer. In particular, two three-way catalytic converters are preferably provided, which are preferably connected directly to one another in the exhaust gas line in the flow direction. The exhaust gas downstream of the catalyst has heat still sufficient to activate the catalytic material in the second reformer, i.e. to bring it to operating temperature.

It is particularly advantageous if the second reformer has a coating on both sides, wherein the coatings are different from one another, wherein the first side is designed in particular as a three-way catalyst. For this purpose, the second reformer is advantageously designed as a plate reforming heat exchanger. At least one individual three-way catalyst can therefore be dispensed with. The first side is for this purpose coated with a typical coating for a three-way catalyst, such as for example alumina containing noble metals. The first side of the second reformer thus forms the hot side of the reforming heat exchanger thus constituted. The second side, which forms the cold side, is coated with a catalytic material for performing the reforming process. The reformer is preferably designed for this purpose as a plate heat exchanger with a coating on both sides. It is advantageous here if the reaction on the first side is an exothermic process and the reaction on the second side is an endothermic process, whereby the exhaust gas energy can be used directly for reforming.

The first reformer advantageously has a coating on both sides, wherein the coatings are different from one another, wherein the first side is arranged in the exhaust gas line and is designed in particular as a three-way catalyst. Thereby, the first reformer is also designed as a reforming heat exchanger. The first reformer now corresponds to the second reformer described above in terms of all its components and operation. The first side of the first reformer is preferably arranged in the exhaust gas line upstream of the first side of the second reformer, and the second side of the first reformer is arranged in the AGR assembly downstream of the second side of the second reformer. Two conventional three-way catalysts can therefore be dispensed with.

The use of the internal combustion engine according to the invention is advantageously implemented in a motor vehicle.

Drawings

Other features, advantages and effects come from the embodiments shown below. The figures referred to for this purpose show:

FIG. 1 shows a schematic diagram of an internal combustion power system of the present invention;

FIG. 2 shows a schematic diagram of another internal combustion power system of the present invention;

FIG. 3 shows a schematic diagram of another internal combustion power system of the present invention;

FIG. 4 shows a schematic diagram of another internal combustion power system of the present invention;

FIG. 5 shows a schematic diagram of another internal combustion power system of the present invention;

fig. 6 shows a schematic diagram of another internal combustion power system of the present invention.

Detailed Description

Fig. 1 shows an internal combustion power system 1 according to the invention with an internal combustion engine 2, an exhaust gas line 3 and an AGR-assembly 4. The AGR assembly 4 comprises a circulation portion 5 in which a first reformer 7 and an evaporator 8 are arranged. The evaporator 8 and the first reformer 7 are indirectly connected to each other by means of an evaporation line 12, so that the gaseous fuel can be led to the first reformer 7. The evaporation line does not lead directly to the first reformer 7, but to the mixer 11. In mixer 11, the gaseous fuel is mixed with the recirculating exhaust gases. The recirculating exhaust gases are taken off from the exhaust line 3 downstream of the combustion engine 2 and are led to the mixer 11 in the first part of the recirculation section 5. Downstream of the mixer 11, the mixture of recirculated exhaust gas and gaseous fuel is at least partially reformed in the first reformer 7, for which purpose the first reformer 7 is provided with a catalytic coating.

A fuel line 10 is also provided which carries fuel from the fuel tank K to the internal combustion engine 2 and thus to the evaporator 8. The fuel is evaporated in the evaporator 8 as described above and further processed. A heating device 13 is provided in the fuel line 10, by means of which the fuel for the evaporator 8 can be preheated. The heating device 13 may be in heat transferring contact with the combustion engine 2 as indicated by the double arrow.

The AGR assembly 4 further comprises an AGR cooler 15, wherein the circulation portion 5 is again open to the fuel inlet 6 downstream of the AGR cooler 15. The recirculating exhaust gases can be fed back to the fuel inlet 6 via two different lines 23, 24, for which purpose control means, not shown, are provided in particular downstream of the AGR cooler 15. The first line 23 is a low-pressure line and in turn leads the recirculating exhaust gases indirectly upstream of the turbine 19 towards the internal combustion engine 2 to the fuel inlet. The second line 24 is a high-pressure line and in turn leads the recirculating exhaust gases downstream of the turbine 19, in particular directly to the fuel inlet 6, in the direction of the internal combustion engine 2. Downstream of the internal combustion engine 2, a further turbine 19 is provided, wherein the two turbines 19 are in particular mechanically connected to one another. Upstream of the first turbine 19, an adjusting device 20 for the air flow is provided, by means of which the fuel/air ratio can be adjusted and controlled.

The internal combustion power system 1 also has a second reformer 9, which is designed as a reforming heat exchanger, in particular a plate reforming heat exchanger. Thus, the second reformer 9 has a first hot side arranged in the exhaust gas line 3 or through which the exhaust gas flows and a second cold side arranged in the circulation section 4. The circulated exhaust gas flows from the first reformer 7 into the cold side of the second reformer 9 with a catalytic coating. The coating is activated by the heat of the exhaust gas flowing through the first side of the second reformer 9, so that the recirculated exhaust gas can in particular be completely reformed. The reformed recycle exhaust gas is led downstream of the second reformer 9 to the evaporator 8, where the fuel is evaporated by means of the recycle exhaust gas as described above. Finally, the circulated exhaust gases are returned to the internal combustion engine 6 via the AGR cooler 15.

In the internal combustion power system 1, a three-way catalyst 16 and other components 18 for exhaust gas treatment are provided in addition to the two turbines 19. Air is fed from the air tank L to the internal combustion engine 2 through the first turbine 19. Downstream of the other components 18, the exhaust gases in the exhaust line 3 are discharged to the environment towards the outside a.

Fig. 2 shows a schematic illustration of a further internal combustion engine 1 according to the invention, which largely corresponds to the internal combustion engine of fig. 1, so that components with the same reference numerals are not described in principle. In addition, a water pipe 14 is provided in the internal combustion power system 1, through which water is guided from the water tank W to the internal combustion engine for stable combustion. Alternatively, the water pipe 14 may also guide (dashed line) water to the evaporator 8 to prevent carbon black from being generated during evaporation.

Fig. 3 shows another embodiment of an internal combustion power system 1 according to the invention. The components already described in fig. 1 are not described further here. According to fig. 3, the second reformer 9 is arranged in the AGR-assembly 4.A portion of the exhaust gases in the exhaust line 3 is led to a second reformer 9 where they are used for heat transfer and then returned to the exhaust line 3 (see arrow in fig. 3). The internal combustion power system 1 further comprises two three-way catalysts 16,17, wherein the exhaust gases are fed to the second reformer 9 downstream of the two three-way catalysts 16, 17. For directing a part of the exhaust gases to the second reformer 8, a passive or active flow divider 21 is provided. A second active or passive splitter 22 is arranged downstream of the second reformer 9 in order to merge parts of the exhaust gases again.

The internal combustion engine 1 according to fig. 4 is according to a variant of fig. 3, in which a portion of the exhaust gas is led to the reformer upstream of the second three-way catalyst 17 and returned to the exhaust line 3 downstream of the second three-way catalyst 17. In this case, it is advantageous if the second reformer 9 also has a coating on the first side, wherein it is a second three-way catalyst coating, so that the second three-way catalyst 17 can be designed correspondingly small.

Fig. 5 shows a schematic illustration of a further internal combustion engine 1 according to the invention, wherein components having the same reference numerals as in the previous figures are not described again. The second reformer 9 is here, unlike before, flowed through by the entire exhaust gas in the exhaust gas line 3, wherein the first side of the reforming heat exchanger is coated in such a way that it is itself designed as a three-way catalyst. The second three-way catalyst 17 can be dispensed with. The second side of the reforming heat exchanger is in turn designed as a catalytic reformer. The reaction at the first side of the reforming heat exchanger is an exothermic process and heat is supplied for endothermic reaction at the second side of the reforming heat exchanger. The second reformer 9 is thus designed as a plate-type reforming exchanger coated on both sides, wherein the two coatings are different from each other.

Fig. 6 shows a modification of the internal combustion engine system 1 according to fig. 5. In this case, the first reformer 7 is also designed as a reforming heat exchanger and is coated on both sides. The first side of the first reformer 7 is flown through by the exhaust gas and functions as a three-way catalyst, for which it is coated accordingly. The second side of the first reformer 7 is flowed through by the recirculated exhaust gas and gaseous fuel, where they are reformed, for which purpose this side is provided with a catalytic coating. The reaction at the first side of the first reforming heat exchanger is in turn an exothermic process and provides heat for the endothermic reaction at the second side of the first reforming heat exchanger. The second three-way catalyst 16 may be dispensed with. The first reformer 7 is arranged upstream of the second reformer 9.

In particular, the two embodiments of fig. 5 and 6 have proved advantageous, since the number of components in the internal combustion engine 1 is thereby reduced on the one hand, and on the other hand the heat of the internal combustion engine 1 can be optimally utilized without the different pressure requirements being difficult.

Claims

1. An internal combustion power system (1) having an internal combustion engine (2), an exhaust gas line (3) and an AGR assembly (4), the AGR assembly (4) having a circulation section (5) for circulating exhaust gas from the exhaust gas line (3), in particular into a fuel inlet (6) of the internal combustion engine (2), wherein a first reformer (7) for reforming fuel into reformate and an evaporator (8) for evaporating fuel are provided in the circulation section (5),

it is characterized in that the method comprises the steps of,

a second reformer (9) is provided.

2. Internal combustion power system (1) according to claim 1, characterized in that the second reformer (9) is designed as a reforming heat exchanger, wherein a first side of the second reformer (9) is connected to the exhaust line (3) and a second side of the reformer (9) is connected to the circulation section (5).

3. An internal combustion power system (1) according to claim 2, characterized in that in the circulation section (5) the second reformer (9) is arranged downstream of the first reformer (7), wherein the second reformer (9) is connected to the exhaust line (3).

4. An internal combustion power system (1) according to one of claims 1 to 3, characterized in that a fuel line (10) is provided for supplying fuel to the internal combustion engine (2) and the evaporator (8).

5. Internal combustion power system (1) according to one of claims 1 to 4, characterized in that a mixer (11) is provided upstream of the first reformer (7), wherein a vapor line (12) for supplying gaseous fuel to the mixer (11) is provided between the evaporator (8) and the mixer (11).

6. An internal combustion power system (1) according to claim 5, characterized in that heating means (13) are provided for heating the fuel.

7. An internal combustion power system (1) according to one of the claims 1 to 6, characterized in that a water pipe (14) is provided for supplying water to the internal combustion engine (2) and possibly to the evaporator (8).

8. Internal combustion power system (1) according to one of claims 1 to 7, characterized in that an AGR cooler (15) is provided downstream of the evaporator.

9. Internal combustion power system (1) according to one of claims 1 to 8, characterized in that the exhaust gas line (3) comprises at least one catalytic converter, in particular designed as a three-way catalytic converter (16, 17).

10. Internal combustion power system (1) according to one of claims 1 to 9, characterized in that the second reformer (9) has coatings on both sides, wherein the coatings are different from each other, wherein the first side of the second reformer (9) is designed in particular as a three-way catalyst (17).

11. Internal combustion power system (1) according to claim 10, characterized in that the first reformer (7) has coatings on both sides, wherein the coatings are different from each other, wherein a first side of the first reformer (7) is arranged in the exhaust line (3) and is designed in particular as a three-way catalyst (16).

12. Use of an internal combustion power system (1) according to one of claims 1 to 11 in a motor vehicle.