DE102019211877A1 - Method for operating an internal combustion engine and internal combustion engine, set up to carry out such a method - Google Patents

Abstract

The invention relates to a method for operating an internal combustion engine (1), hydrogen being used as fuel for the internal combustion engine (1), exhaust gas heat from the internal combustion engine (1) being used to generate hydrogen for operating the internal combustion engine (1) from an organic storage fluid to release, in which hydrogen is stored, wherein waste heat of the liquid-cooled internal combustion engine (1) is used to preheat the organic storage liquid.

Description

The invention relates to a method for operating an internal combustion engine and an internal combustion engine which is set up to carry out such a method.

In the context of a method of the type discussed here, an internal combustion engine is operated with hydrogen as fuel. For example from the European patent specification EP 2 925 669 B1 an organic storage liquid is known which can be charged with hydrogen and from which hydrogen can in turn be released if necessary. In order to release the hydrogen from the organic storage liquid, high amounts of heat are regularly necessary, it being possible to provide a separate heating device in order to at least partially provide the required amount of heat. This can for example be an electrical heating device. However, this is laborious, expensive and energetically unfavorable.

The invention is based on the object of creating a method for operating an internal combustion engine and an internal combustion engine which is set up to carry out such a method, the disadvantages mentioned at least partially not occurring.

The object is achieved in that the present technical teaching is provided, in particular the teaching of the independent claims and the embodiments disclosed in the dependent claims and the description.

The object is achieved in particular by creating a method for operating an internal combustion engine, hydrogen being used as fuel for the internal combustion engine, exhaust heat from the internal combustion engine being used to release hydrogen for operating the internal combustion engine from an organic storage liquid in which hydrogen is stored is, and wherein waste heat of the liquid-cooled internal combustion engine is used to preheat the organic storage liquid. Due to the combination of the exhaust gas heat for releasing the hydrogen from the organic storage liquid with the waste heat used to preheat the organic storage liquid, the internal combustion engine itself - even in partial load, low load or idling - can provide enough heat to release the amount of hydrogen from the organic storage liquid that is required for their operation. Additional heating by means of an external heating device is therefore not required; this can therefore be omitted. This saves installation space and costs and is also energy efficient. In particular, the efficiency of the internal combustion engine is advantageously increased. If necessary, a cooler for the internal combustion engine can even be made smaller or omitted, since the waste heat that occurs is absorbed - at least partially - by the organic storage fluid. It is possible that the waste heat is completely absorbed by the organic storage fluid, or that air cooling is sufficient for an engine block of the internal combustion engine to dissipate the heat not absorbed by the organic storage fluid.

Of course, it is also possible for the internal combustion engine to have an additional cooler.

According to the invention, it has been recognized in particular that the exhaust gas heat alone is not sufficient, at least in all operating states of the internal combustion engine, to drive out sufficient hydrogen from the organic storage fluid for the operation of the internal combustion engine. The waste heat from the liquid-cooled internal combustion engine is therefore advantageously also used to preheat the organic storage fluid and thus provide a sufficiently large amount of heat overall to release the hydrogen.

In particular, the exhaust gas heat from the internal combustion engine is used to release hydrogen from the organic storage fluid for the operation of the internal combustion engine - as fuel.

Exhaust heat is understood here to mean, in particular, heat that is taken from the exhaust gas of the internal combustion engine in order to release hydrogen. In this respect, it is possible for exhaust gas from the internal combustion engine to be passed directly through a heat exchanger in which the organic storage fluid also flows, so that heat can be exchanged directly between the exhaust gas and the organic storage fluid. In particular, the exhaust gas can be passed directly through a release device that is set up to release hydrogen. Alternatively, it is possible that the organic storage liquid is passed through an exhaust line section of the internal combustion engine in order to extract heat from the exhaust gas flowing along the exhaust line section. In particular, it is possible for the release device to be designed as part of the exhaust gas piping of the internal combustion engine.

However, according to a preferred embodiment, it is also possible for the internal combustion engine to have an exhaust gas cooling circuit in which an exhaust gas coolant flows. The exhaust gas cooling circuit comprises, on the one hand, an exhaust gas heat exchanger, in which the exhaust gas coolant absorbs heat from the exhaust gas flow, and, on the other hand, the releaser, where the exhaust gas coolant transfers heat to the organic Releases storage fluid to release the hydrogen.

Waste heat from the internal combustion engine is understood here to mean heat that accumulates in an engine block of the internal combustion engine and is removed from the engine block by means of liquid cooling. For this purpose, a coolant flows through the engine block at least in some areas. As will be explained in the following, this cooling liquid can, in a preferred embodiment, be a coolant or the organic storage liquid itself. In particular, the waste heat is not exhaust heat. Rather, the exhaust gas heat is not extracted from the engine block via liquid cooling, but rather through the exhaust gas flowing out along the exhaust gas piping.

The fact that the organic storage fluid is preheated means in particular that its temperature is raised upstream of the releaser, that is to say in the flow direction of the organic storage fluid upstream of the releaser, by supplying the waste heat from the internal combustion engine.

The process of releasing hydrogen therefore takes place in two stages: First, in a first step, the organic storage fluid is preheated using the waste heat from the liquid-cooled internal combustion engine, with the hydrogen then being released from the organic storage fluid in a second step in the releaser using the exhaust gas heat from the internal combustion engine .

According to a development of the invention it is provided that a coolant of a liquid cooling circuit is passed through a heat exchanger in which the organic storage liquid flows in order to preheat the organic storage liquid. In this case, the coolant is not identical to the organic storage liquid, but rather a different liquid. In particular, it is possible to use cooling water - optionally with additives, in particular antifreeze and the like - as the coolant. In this exemplary embodiment, the waste heat from the internal combustion engine is thus indirectly fed to the organic storage liquid, namely conveyed via the coolant of the liquid cooling circuit. It is possible that the heat exchanger is the only cooler of the internal combustion engine, either all of the waste heat from the internal combustion engine being absorbed by the organic storage fluid, or any remaining residual heat being dissipated as radiant heat or by air cooling.

The heat exchanger is preferably arranged downstream of the engine block - in the direction of flow of the coolant through the liquid cooling circuit - and hot coolant flowing out of the engine block thus flows through it. If the internal combustion engine has, in addition to the heat exchanger, a cooler, in particular an outside air cooler, in the liquid cooling circuit through which the coolant flows, the heat exchanger is preferably arranged upstream of the cooler. In this case, the coolant is therefore precooled in particular in the heat exchanger before it is then further cooled in the cooler, in particular in the outside air cooler.

The liquid cooling circuit preferably has a heat exchanger bypass via which the heat exchanger can be bypassed. In particular when starting the internal combustion engine, it can be advantageous to bypass the heat exchanger in order to bring the internal combustion engine up to operating temperature as quickly as possible and not extract any heat from it. Preferably, the coolant can optionally be routed along the heat exchanger bypass, bypassing the heat exchanger or via the heat exchanger, bypassing the heat exchanger bypass, depending on the operating situation or operating state of the internal combustion engine. It is also possible that, in certain operating situations or operating states, the coolant is partly guided via the heat exchanger and partly via the heat exchanger bypass.

According to a development of the invention it is provided that the organic storage liquid is used as a coolant for the liquid-cooled internal combustion engine. This represents a particularly simple embodiment in which an additional liquid cooling circuit and an additional coolant can be dispensed with.

According to a development of the invention it is provided that organic storage liquid depleted of hydrogen - in the following briefly depleted storage liquid - is separated from hydrogen-laden organic storage liquid - in the following briefly loaded storage liquid. A dilution of the loaded storage fluid by the depleted storage fluid can thus advantageously be avoided.

The internal combustion engine preferably has a storage fluid heat exchanger through which, on the one hand, the charged storage fluid flowing to the releaser and, on the other hand, the depleted storage fluid flowing out of the releaser flow. Here, heat is transferred from the depleted storage fluid to the loaded storage fluid. The loaded storage fluid is thus additionally preheated, and the energy efficiency and the efficiency of the internal combustion engine increase increased, since in particular the residual heat of the exhaust gas heat used in the releaser to release the hydrogen is not dissipated unused with the depleted storage liquid, but rather is used to further preheat the loaded storage liquid.

According to a preferred embodiment, cooling of the internal combustion engine is switched from the loaded storage fluid to the depleted storage fluid when a residual amount of the loaded storage fluid is no longer sufficient to cool the liquid-cooled internal combustion engine. It is therefore preferred initially, in particular after a loading or refueling process with hydrogen, to use the loaded storage liquid as a coolant for the liquid-cooled internal combustion engine. As the operating time progresses, the proportion of the loaded storage fluid decreases and the proportion of the depleted storage fluid increases, and at some point during the operation of the internal combustion engine, a remaining amount of the charged storage fluid is no longer sufficient to cool the liquid-cooled internal combustion engine. In this case, it is advantageous to switch to using the depleted storage liquid as a coolant for the liquid-cooled internal combustion engine, so that cooling continues to be guaranteed without having to resort to an additional coolant.

According to a further development of the invention, it is provided that at least temporarily waste heat from the internal combustion engine - in addition to cooling via the organic storage fluid - is dissipated via a cooler. In this way, waste heat peaks in particular can be intercepted if they cannot be completely absorbed by the organic storage fluid. This is possible both with direct cooling of the internal combustion engine by the organic storage fluid, especially when it is used as a coolant, and with indirect cooling of the internal combustion engine via the organic storage fluid, i.e. especially when the waste heat is supplied to the organic storage fluid via another coolant a liquid cooling circuit. The cooler can correspondingly in particular either be flowed through by the other coolant or - at least temporarily - by the organic storage liquid. In particular, the cooler can be switched on if the entire waste heat from the internal combustion engine cannot be absorbed by the organic storage fluid.

In particular, it is possible for the internal combustion engine to have a cooler bypass which is set up to bypass the cooler if necessary. The cooler is preferably bypassed if the entire waste heat from the internal combustion engine can be absorbed by the organic storage fluid. On the other hand, there is a flow through the cooler if the organic storage liquid cannot absorb all of the waste heat from the internal combustion engine. It is preferably also possible for the flow to flow through part of the cooler and another part of the cooler bypass so that the cooler is partially switched on.

According to a development of the invention, it is provided that in a first operating state, when the internal combustion engine is started, the organic storage fluid, bypassing the releaser and bypassing a storage container for the organic storage liquid, that is to say in particular a storage container for the loaded organic storage liquid, in a Storage fluid circuit is passed through an engine block of the internal combustion engine. In this first operating state, on the one hand, at most a small amount of heat is withdrawn from the internal combustion engine, which is absorbed by the storage fluid carried in the storage fluid circuit, with the internal combustion engine and also the storage fluid being warmed up in the storage fluid circuit. The storage fluid circuit preferably does not have a cooler; This results in particularly rapid and efficient warming up of both the internal combustion engine and the storage fluid. Since the organic storage liquid is guided in the storage liquid circuit, bypassing the releaser, no hydrogen can be released in the first operating state.

In this case, the internal combustion engine is preferably operated from a hydrogen buffer store, which - along a fluidic connection between the releaser and the engine block for supplying hydrogen from the releaser to the engine block - for intermediate storage of hydrogen and in particular to compensate for fluctuations in the Hydrogen release is provided.

The first operating state is preferably maintained until the internal combustion engine has reached a predetermined operating temperature or until a temperature measured in the storage fluid circuit, in particular a temperature of the storage fluid flowing in the storage fluid circuit, reaches or exceeds a first predetermined limit value.

The storage fluid circuit is preferably defined and in particular delimited from other fluidic paths along which storage fluid can flow that it includes the engine block; along the Storage fluid circuit is therefore passed through the engine block.

In a second operating state, organic storage fluid is preferably fed to the releaser from the storage fluid circuit, with as much organic storage fluid being removed from the storage container and supplied to the storage fluid circuit as is withdrawn from the storage fluid circuit for the releasing device. The engine block is therefore still primarily cooled by absorbing the waste heat into the storage fluid circuit, although now - in contrast to the first operating state - storage fluid is branched off from the storage fluid circuit to the releaser. Circulation volume flowing out of the reservoir is replaced. As a result, heat is also withdrawn from the storage fluid circuit.

At the same time, depleted storage fluid flowing out of the releaser is preferably fed to a collecting container. The collecting container is provided in particular to receive the depleted storage liquid.

When the storage liquid is loaded with hydrogen, the depleted storage liquid is preferably removed from the collecting container, enriched with hydrogen, and fed back to the storage container as loaded storage liquid. Ultimately, the storage liquid is not used up and can be reused.

In a third operating state, the storage container is preferably at least partially included in the storage fluid circuit. This means that storage liquid now flows out of the storage liquid circuit not only in the direction of the releaser, but also flows back into the storage container, whereby overall the amount of storage liquid flowing out into the releaser and, on the other hand, into the storage container, in particular the storage liquid volume, replaces from the storage container, is thus fed back to the storage fluid circuit. This has the advantage that the storage container is also included as a heat sink in the storage fluid circuit. If the heat dissipation from the storage fluid circuit into the releaser is no longer sufficient to absorb the waste heat from the internal combustion engine, additional heat can be dissipated via the storage container. In this case, it is in particular possible that an entire volume flow of the storage liquid, which flows along the storage liquid circuit and is not branched off for the releaser, is guided via the storage container.

In a fourth operating state, the collecting container - in particular instead of the storage container - is preferably included in the storage liquid circuit, the storage container and the releaser being bypassed by the storage liquid circuit. At the same time, the releaser excluded from the storage fluid circuit is fed with loaded storage fluid from the storage container. In the fourth operating state, the internal combustion engine is no longer cooled with charged storage fluid, but rather with depleted storage fluid, in that the depleted storage fluid is passed along the storage fluid circuit and thus through the engine block. This fourth operating state is assumed in particular when a residual amount of the charged storage fluid is no longer sufficient to cool the liquid-cooled internal combustion engine. In the fourth operating state, the collecting container in particular serves as a heat sink for the storage fluid circuit.

In the fourth operating state in particular, it is possible that a cooler is also included in the storage fluid circuit. This may be necessary if the collecting container is not sufficient as a heat sink to dissipate the waste heat from the engine block, in particular since no more heat is dissipated from the engine block into the release unit in the fourth operating state.

Switching between the various operating states is preferably temperature-controlled, in particular as a function of a temperature of the storage fluid in the storage fluid circuit. In particular, it is preferred to switch from the first operating state to the second operating state when the temperature of the storage liquid reaches or exceeds the first predetermined limit value for the first time. The second operating state is preferably switched to the third operating state if the storage liquid again reaches or exceeds the first predetermined limit value, or if the storage liquid reaches or exceeds a second predetermined limit value, which is preferably higher or lower than the first predetermined limit value, in particular higher than the first predetermined limit value can be selected. The third operating state is preferably switched to the fourth operating state when the storage fluid in the storage fluid circuit again reaches or exceeds the first or second predetermined limit value, or when it reaches or exceeds a third predetermined limit value. This exceeding of the limit value then indicates that the charged storage fluid flowing in the storage fluid circuit is no longer sufficient to dissipate the waste heat from the internal combustion engine. The temperature of the storage liquid is preferably measured upstream of the engine block, in particular immediately upstream of an inlet for the storage liquid in the engine block. After the storage liquid has been reloaded with hydrogen, it is then possible to switch back to the first, second or third operating state, in particular depending on the temperature.

According to a development of the invention, it is provided that additional waste heat from a fuel cell is used to preheat the organic storage liquid. The fuel cell can in particular be provided instead of an alternator or a generator that is otherwise driven by the internal combustion engine, in particular a power take-off of the internal combustion engine, in order to supply auxiliary units of the internal combustion engine with electrical power. The fuel cell has a higher degree of efficiency than the internal combustion engine in combination with such an alternator or a corresponding generator, the fuel cell advantageously being able to be operated with the hydrogen that is already available. The waste heat from the fuel cell can advantageously also be used for preheating and thus also for releasing hydrogen, which is particularly economical and increases the overall efficiency of the internal combustion engine - in particular including the fuel cell. Furthermore, additional hydrogen can advantageously be released by means of the additionally available waste heat from the fuel cell, which in turn is used to operate the fuel cell.

The object is finally also achieved by creating a hydrogen-powered internal combustion engine which has a releaser which is designed to use exhaust heat from the internal combustion engine in order to release hydrogen for operating the internal combustion engine - as fuel - from an organic storage fluid in which hydrogen is stored. The internal combustion engine is also designed to use waste heat from the liquid-cooled internal combustion engine in order to preheat the organic storage liquid. In particular, the internal combustion engine is set up to carry out a method according to the invention for operating the internal combustion engine, or one of the previously described preferred embodiments of the method for operating the internal combustion engine. In connection with the internal combustion engine, there are in particular the advantages that have already been explained in connection with the method.

The releaser preferably has at least one catalyst or at least one catalytic material, in particular a metal-containing catalyst, the catalyst being set up to catalyze a dehydrogenation reaction for dehydrogenating the organic storage liquid. The catalyst preferably has at least one metal selected from a group consisting of: palladium, nickel, platinum, iridium, ruthenium, cobalt, rhodium, copper, gold, rhenium and iron, the metal in particular in finely divided form on a porous, non-polar carrier can be present.

According to a further development of the invention, it is provided that the internal combustion engine has a hydrogen buffer store for released hydrogen. In this way, fluctuations in the hydrogen release in particular can advantageously be compensated for. In particular, the internal combustion engine can be operated with hydrogen when it is started and until it reaches its operating temperature or a predetermined temperature in the storage fluid circuit, which hydrogen is taken from the hydrogen buffer store.

The hydrogen buffer store is preferably fluidically arranged - in a fluidic connection for the passage of hydrogen - between the release device on the one hand and an engine block of the internal combustion engine on the other hand.

The organic storage liquid is preferably a liquid as it is in one of the documents WO 2006/009630 A2 , EP 1 475 349 A2 or EP 2 925 669 B1 is revealed. In particular, the organic storage liquid can preferably be charged with hydrogen by being hydrogenated. The hydrogen can preferably be released from the organic storage liquid in that the organic storage liquid is dehydrogenated by supplying heat and preferably catalytically.

The release of hydrogen from the organic storage liquid takes place preferably in a temperature range from 280 ° C to 320 ° C. Assuming that the organic storage fluid has to be preheated from 25 ° C to 300 ° C so that the dehydrogenation reaction can take place, around 3 kWh / kg of hydrogen to be released are required for heat; furthermore, 9 kWh / kg of hydrogen to be released of reaction heat are required to release the hydrogen.

Hydrogen has an enthalpy of combustion of 33 kWh / kg hydrogen. One can roughly assume that in an internal combustion engine one third of the energy supplied is generated as exhaust gas heat. Thus, a simple calculation shows that for the release of hydrogen per kg Released hydrogen 12 kWh of heat are required, but only 11 kWh / kg of hydrogen are produced as exhaust gas heat when the internal combustion engine is operated. It can thus be safely assumed that the exhaust gas heat alone is not sufficient, at least at all operating points and taking into account the losses that occur in reality, to release sufficient hydrogen for the operation of the internal combustion engine.

Therefore, in the method proposed here, the waste heat from the liquid-cooled internal combustion engine is additionally used to preheat the organic storage fluid, the waste heat in combination with the exhaust gas heat being sufficient to release a sufficient amount of hydrogen from the organic storage fluid for the operation of the internal combustion engine.

• 1 eine schematische Darstellung eines ersten Ausführungsbeispiels einer Brennkraftmaschine zur Durchführung einer ersten Ausführungsform eines Betriebsverfahrens für die Brennkraftmaschine, und
• 2 eine schematische Darstellung eines zweiten Ausführungsbeispiels einer Brennkraftmaschine zur Durchführung einer zweiten Ausführungsform des B etriebsv erfahrens.

The invention is explained in more detail below with reference to the drawing. Show:

• 1 a schematic representation of a first embodiment of an internal combustion engine for performing a first embodiment of an operating method for the internal combustion engine, and
• 2 a schematic representation of a second embodiment of an internal combustion engine for performing a second embodiment of the operating method.

1 shows a schematic representation of a first embodiment of an internal combustion engine 1 which is set up to carry out a first embodiment of an operating method for the internal combustion engine 1 . The internal combustion engine 1 is a hydrogen-powered internal combustion engine, i.e. it is set up to use hydrogen as fuel. The internal combustion engine 1 has a releaser 3 on, which is set up to heat exhaust gas from the internal combustion engine 1 to use hydrogen for the operation of the internal combustion engine 1 to be released from an organic storage fluid in which hydrogen is stored. The internal combustion engine 1 is also set up to remove waste heat from the liquid-cooled internal combustion engine 1 , especially waste heat from a liquid-cooled engine block 5 the internal combustion engine 1 , to be used to preheat the organic storage fluid. By combining the exhaust gas heat with the waste heat from the engine block 5 on the other hand stands - in particular at every operating point of the internal combustion engine 1 - Sufficient heat is available to operate the internal combustion engine 1 to release sufficient amount of hydrogen from the organic storage fluid. There is therefore no need for an additional heating device. This is the efficiency of the internal combustion engine 1 advantageously increased.

The internal combustion engine 1 also has a hydrogen storage tank 7th in which hydrogen released from the organic storage fluid can be temporarily stored. The hydrogen buffer storage 7th is in particular in a fluidic connection between the releaser 3 and the engine block 5 used to feed hydrogen from the releaser 3 to the engine block 5 is set up, arranged.

The internal combustion engine 1 has an exhaust gas cooling circuit 9 in which an exhaust gas coolant flows, which in an exhaust gas heat exchanger 11 Heat from the in an exhaust pipe 13 absorbs flowing exhaust gas, and this heat to the release 3 feeds.

It is also possible that along the exhaust gas cooling circuit 9 the organic storage fluid flows directly to exhaust heat from the exhaust pipe 13 , especially in the exhaust gas heat exchanger 11 to record.

The internal combustion engine 1 also has a fresh air supply line 15th on, along the the engine block 5 Combustion air - especially oxygen - is supplied.

In the first embodiment of the internal combustion engine 1 it is provided that the coolant of a liquid cooling circuit 17th through a heat exchanger 19th is performed, in which the organic storage liquid flows to preheat the organic storage liquid. The heat exchanger 19th is in particular in a fluidic connection between a storage container 21st and the release 3 arranged, which is set up for the passage of the organic storage liquid from the storage container 21st to the release 3 . The coolant flows through the liquid cooling circuit 17th also the engine block 5 , the so far in the liquid cooling circuit 17th is involved. This means that waste heat is released from the engine block 5 absorbed by the coolant and the heat exchanger 19th fed. The heat exchanger 19th is particularly downstream of the engine block 5 in the liquid cooling circuit 17th arranged.

In this exemplary embodiment, the coolant is a substance or mixture of substances that is different from the organic storage liquid, in particular cooling water, optionally with additives.

There is a heat exchanger bypass here 23 provided, with coolant via the heat exchanger bypass 23 along the liquid cooling circuit 17th bypassing the heat exchanger 19th can be performed. By means of a first valve device 25th can be set, preferably controlled or regulated, whether the coolant via the Heat exchanger 19th or bypassing the heat exchanger 19th via the heat exchanger bypass 23 along the liquid cooling circuit 17th flows. A division into partial flows by means of the first valve device is also preferred 25th possible so that the coolant partially passes through the heat exchanger 19th and partly along the heat exchanger bypass 23 flows. In this way, it is particularly sensitive to set how much heat is transferred to the liquid cooling circuit 17th via the heat exchanger 19th is withdrawn. In particular when starting the internal combustion engine 1 can do the heat exchanger 19th be bypassed to allow a quick warm-up of the engine block 5 to enable.

In the embodiment shown here, there is a liquid cooling circuit 17th additionally a cooler 27 provided, which is preferably designed as an outside air cooler. About the cooler 27 can at least temporarily waste heat from the internal combustion engine 1 in addition to cooling via the organic storage liquid.

The liquid cooling circuit 17th has a cooler bypass 29 on over which the cooler 27 can be bypassed if necessary. In the liquid cooling circuit 17th is a second valve device 31 arranged, via which it can be controlled whether the coolant bypassing the radiator 27 along the cooler bypass 29 flows, or via the cooler 27 bypassing the cooler bypass 29 . Preferably, the flow of the coolant can also be divided so that it is partially over the radiator 27 and partly via the cooler bypass 29 flows.

The internal combustion engine is optional 1 another fuel cell 33 - In particular for generating electrical power for ancillary units of the internal combustion engine 1 - Assigned, advantageously also waste heat from the fuel cell 33 is used to preheat the organic storage fluid. The fuel cell 33 for example - as shown in dashed lines - in the liquid cooling circuit 17th be integrated, or in a manner not shown here by a second, separate cooling circuit directly to the heat exchanger 19th be connected.

The release 3 is also set up to separate organic storage fluid depleted of hydrogen from organic storage fluid loaded with hydrogen.

The depleted storage fluid is here in a collecting container 35 guided. The internal combustion engine 1 has a storage liquid heat exchanger 37 on the one hand from that of the releaser 3 coming, depleted storage fluid that goes to the collecting tank 35 flows, and on the other hand from that to the releaser 3 flowing, loaded storage liquid is flowed through. In doing so, heat can be released from the releaser 3 outflowing depleted storage fluid on the in the release 3 flowing loaded storage liquid are transferred. The loaded storage liquid is thus additionally preheated.

2 shows a schematic representation of a second exemplary embodiment of an internal combustion engine 1 which is set up to carry out a second embodiment of the operating method. Identical and functionally identical elements are provided with the same reference symbols, so that in this respect reference is made to the preceding description. In the second embodiment shown here, the liquid cooling circuit is 17th not available, instead the organic storage liquid itself is used as a coolant for the liquid-cooled internal combustion engine 1 , especially for the engine block 5 , used.

A storage fluid circuit is particularly important for this purpose 39 provided along which the organic storage fluid through the engine block 5 is directed. To implement various operating states, the internal combustion engine 1 a plurality of directional control valves, namely a first directional control valve 41 , a second directional control valve 43 , a third directional control valve 45 , and a fourth directional control valve 47 . The first directional control valve 41 is designed in particular as a three-way valve, with a first connection 41.1 in terms of flow - in particular via a first conveyor device 49 , especially a pump - with the reservoir 21st connected is. A second connection 41.2 is with a fourth port 47.4 of the fourth directional control valve 47 fluidically connected. A third connection 41.3 is fluidic with a first connection 43.1 of the second directional control valve 43 connected.

The second directional control valve 43 is also designed as a three-way valve, its second connection 43.2 fluidically with the collecting tank 35 connected is. A third connection 43.3 of the second directional control valve 43 is fluidic - via a second conveyor 51 , preferably a pump - with the engine block 5 connected.

The third directional control valve 45 is preferably designed as a three-way valve, with a first connection 45.1 fluidically with the engine block 5 connected is. A second connection 45.2 of the third directional control valve 45 is fluidically connected to the collecting tank 35 connected, and a third connector 45.3 of the third directional control valve 45 is fluidic with a first connection 47.1 of the fourth directional control valve 47 connected.

The fourth directional control valve 47 is preferably designed as a four-way valve. Its second connection 47.2 is fluidic with the storage liquid heat exchanger 37 connected. A third connection 47.3 of the fourth directional control valve 47 is fluidically connected to the reservoir 21st connected.

In a first operating state of the internal combustion engine 1 are now the directional control valves 41 , 43 , 45 , 47 switched so that the organic storage fluid bypassing the release 3 and bypassing the reservoir 21st in the storage fluid circuit 39 through the engine block 5 is promoted. The organic storage liquid flows from the third connection 41.3 of the first directional control valve 41 over the first connection 43.1 and the third port 43.3 of the second directional control valve 43 and the second conveyor 51 in the engine block 5 , from this over the first connection 45.1 and the third port 45.3 of the third directional control valve 45 to the first connection 47.1 of the fourth directional control valve 47 , and from there via the fourth connection 47.4 back to the second port 41.2 of the first directional control valve 45 where it turns into the third connector 41.3 is diverted. So in particular are the first connection 41.1 of the first directional control valve 41 , the second port 43.2 of the second directional control valve 43 , the second port 45.2 . of the third directional control valve 45 , as well as the second connection 47.2 and the third connector 47.3 of the fourth directional control valve 47 blocked; all other connections are open and connected to one another accordingly.

In particular when starting the internal combustion engine 1 and until the engine block reaches an operating temperature 5 and / or a predetermined limit value for the temperature of the organic storage liquid, the latter is thus circulated, with the engine block 5 at most marginal heat is withdrawn to the organic storage fluid in the storage fluid circuit 39 to heat up. The release 3 no organic storage liquid is supplied in this operating state, so that no hydrogen is released either. The internal combustion engine 1 is in this operating state with hydrogen from the hydrogen buffer storage 7th operated. The release 3 however, it is preferred by the exhaust gas cooling circuit 9 preheated.

In a second operating state, the directional control valves 41 , 43 , 45 , 47 switched so that from the storage fluid circuit 39 organic storage fluid to the releaser 3 is supplied, with from the reservoir 21st just as much organic storage fluid in the storage fluid circuit 39 is tracked, as for the release 3 is removed. In addition to the switching of the directional control valves explained above 41 , 43 , 45 , 47 are now also the second connection for this purpose 47.2 of the fourth directional control valve 47 and the first connection 41.1 of the first directional control valve 41 open. The other previously closed connections are still closed, the previously open connections are still open. In addition, depleted storage fluid is released from the release 3 the collection container 35 - via the storage liquid heat exchanger 37 - fed.

The directional control valves are in a third operating state 41 , 43 , 45 , 47 switched so that the reservoir 21st into the storage fluid circuit 39 is at least partially, preferably completely, included. For this purpose, the third connection is additionally required - preferably as the only change to the interconnection described above 47.3 of the fourth directional control valve 47 opened so that organic storage fluid by the engine block 5 comes here, into the storage container 21st can flow away. The fourth connection 47.4 of the fourth directional control valve 47 and the second port 41.2 of the first directional control valve 41 are preferably so wide open that the reservoir 21st is partially not flowed through when the flow of organic storage liquid is divided. Should, however, the storage container 21st completely into the storage fluid circuit 39 will be included in the fourth connection 47.4 of the fourth directional control valve 47 and the second port 41.2 of the first directional control valve 41 closed. The inclusion of the reservoir 21st into the storage fluid circuit 39 serves to provide an additional heat sink - in addition to the storage liquid heat exchanger 37 -, taking waste heat from the engine block 5 additionally via the storage container 21st can be discharged.

The directional control valves are in a fourth operating state 41 , 43 , 45 , 47 wired so that the collecting tank 35 is included in the storage fluid circuit, at the same time the reservoir 21st and the release 3 be bypassed. This becomes the releaser 3 from the storage container 21st fed.

To implement the corresponding storage fluid flow along the storage fluid circuit 39 are now at the second directional control valve 43 the second port 43.2 and the third connector 43.3 opened and connected to one another fluidically, the first connection 43.1 closed is. At the same time are with the third directional control valve 45 the first connection 45.1 and the second port 45.2 opened and fluidically connected to one another, the third connection 45.3 closed is. Depleted storage fluid thus flows - conveyed by the second delivery device 51 - from the collecting container 35 via the second directional control valve 43 in the engine block 5 , and from this via the third directional control valve 45 back to the collecting container 35 .

To the release 3 loaded storage liquid from the storage container 21st are to be supplied to the first directional control valve 41 the first connection 41.1 and the second port 41.2 opened and connected to one another fluidically, the third connection 41.3 Is blocked. At the fourth directional control valve 47 are the fourth port 47.4 and the second port 47.2 fluidically connected to one another, the first connection 47.1 and the third connector 47.3 are locked. Loaded storage fluid thus flows - conveyed by the first conveying device 49 - from the collecting container 21st via the first directional valve 41 and the fourth directional control valve 47 and via the storage liquid heat exchanger 37 into the release 3 . From this, depleted storage fluid flows over the storage fluid heat exchanger 37 off into the collecting container 35 .

Cooling of the internal combustion engine is preferred in this way 1 switched from the loaded storage liquid to the depleted storage liquid, especially when a residual amount of the loaded storage liquid in the collecting container 21st no longer for cooling the liquid-cooled internal combustion engine 1 , especially for cooling the engine block 5 , sufficient.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 2925669 B1 [0002, 0039]
• WO 2006/009630 A2 [0039]
• EP 1475349 A2 [0039]

Claims (9)

A method for operating an internal combustion engine (1), wherein - Hydrogen is used as fuel for the internal combustion engine (1), wherein - Exhaust heat of the internal combustion engine (1) is used to release hydrogen for the operation of the internal combustion engine (1) from an organic storage liquid in which hydrogen is stored, wherein - Waste heat from the liquid-cooled internal combustion engine (1) is used to preheat the organic storage fluid. Procedure according to Claim 1 , characterized in that the coolant of a liquid cooling circuit (17) is passed through a heat exchanger (19) in which the organic storage liquid flows in order to preheat the organic storage liquid. Method according to one of the preceding claims, characterized in that the organic storage liquid is used as a coolant for the liquid-cooled internal combustion engine (1). Method according to one of the preceding claims, characterized in that organic storage liquid depleted of hydrogen is separated from organic storage liquid loaded with hydrogen, wherein cooling of the internal combustion engine (1) is preferably switched from the hydrogen-loaded storage liquid to the hydrogen-depleted storage liquid if a residual amount of the storage liquid loaded with hydrogen is no longer sufficient to cool the liquid-cooled internal combustion engine (1). Method according to one of the preceding claims, characterized in that at least temporarily waste heat from the internal combustion engine (1) is removed via a cooler (27) in addition to cooling via the organic storage liquid. The method according to any one of the preceding claims, characterized in that - in a first operating state when the internal combustion engine (1) is started, the organic storage liquid bypassing a release (3) and a storage container (21) in a storage liquid circuit (39) by a The engine block (5) of the internal combustion engine (1) is guided, wherein - in a second operating state, organic storage liquid is fed from the storage liquid circuit (39) to the release device (3), the storage liquid circuit (39) from the storage container (21) as much organic storage liquid is supplied as is taken from the storage liquid circuit (39) for the releaser (3), wherein - in a third operating state, the storage container (21) is at least partially included in the storage liquid circuit (39), and wherein - In a fourth operating state, the collecting container (35) enters the storage liquid circuit (39) is obtained, the storage container (21) and the releaser (3) being bypassed, the releaser (3) excluded from the storage fluid circuit (39) being fed from the storage container (21). Method according to one of the preceding claims, characterized in that waste heat from a fuel cell (33) is additionally used to preheat the organic storage liquid. Hydrogen-powered internal combustion engine (1), with - A releaser (3) which is set up to use exhaust gas heat of the internal combustion engine (1) in order to release hydrogen for the operation of the internal combustion engine (1) from an organic storage liquid in which hydrogen is stored, wherein - The internal combustion engine (1) is set up to use waste heat from the liquid-cooled internal combustion engine (1) in order to preheat the organic storage liquid. Internal combustion engine (1) after Claim 8 , characterized by a hydrogen buffer store (7) for hydrogen released from the organic storage liquid.

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