DE102020005212A1 - Process for the recovery of water from an exhaust gas of an internal combustion engine - Google Patents

Abstract

The invention relates to a method for the recovery of water from an exhaust gas of an internal combustion engine (2), comprising the steps: - determining a temperature TAbgs, 1a main exhaust gas mass flow ṁAbg of the internal combustion engine (1); - splitting the main exhaust gas mass flow ṁAbgin a first exhaust gas mass flow ṁAbg, 1 and a second exhaust gas mass flow ṁAbg, 2; - Introduction of the second exhaust gas mass flow ṁAbg, 2 into a condenser (7) for the recovery of water from the second exhaust gas mass flow ṁAbg, 2 in a condensate flow ṁK; - Regulation of the second exhaust gas mass flow ṁAbg, 2 depending on the temperature TAbgs, 1 of the main exhaust gas mass flow ṁAbg

Description

The invention relates to a method and a system for recovering water from an exhaust gas of an internal combustion engine.

The CA2700485A discloses a system for recovering water from an exhaust gas of an internal combustion engine.

• - Ermitteln einer Temperatur T_Abgs,1 eines Hauptabgasmassenstroms ṁ_Abg des Verbrennungsmotors (1);
• - Aufteilen des Hauptabgasmassenstroms ṁ_Abg in einen ersten Abgasmassenstrom ṁ_Abg,1 und einen zweiten Abgasmassenstrom ṁ_Abg,2;
• - Einleiten des zweiten Abgasmassenstroms ṁ_Abg,2 in einen Kondensator (7) zur Rückgewinnung von Wasser aus dem zweiten Abgasmassenstrom ṁ_Abg,2 in einem Kondensatstrom ṁ_K;
• - Regeln des zweiten Abgasmassenstrom ṁ_Abg,2 abhängig von der Temperatur T_Abgs,1 des Hauptabgasmassenstroms ṁ_Abg.

A method according to the invention for the recovery of water from an exhaust gas of an internal combustion engine comprises the steps:

• - Determination of a temperature T _{Abgs, 1 of} a main _{exhaust gas mass flow} ṁ _{Abg of} the internal combustion engine ( 1 );
• - Splitting the main exhaust gas mass flow ṁ _Abg into a first exhaust gas mass flow ṁ _{Abg, 1} and a second exhaust gas mass flow ṁ _{Abg, 2} ;
• - Introducing the second exhaust gas mass flow ṁ _{Abg, 2} into a condenser ( 7th ) for the recovery of water from the second exhaust gas mass flow ṁ _{Abg, 2} in a condensate flow ṁ _K ;
• - Regulation of the second exhaust gas mass flow ṁ _{Abg, 2} depending on the temperature T _{Abgs, 1 of} the main exhaust gas mass flow ṁ _Abg .

Characterized in that the control of the second exhaust gas mass flow ṁ _{Abg, 2} takes place depends on the temperature T _{CLSD, 1} of the main exhaust gas mass flow ṁ _Abg, a high Kondenststrom ṁ _K is made possible.

The second exhaust gas mass flow ṁ _{Abg, 2 is} usually regulated independently of the temperature T _{Abgs, 1 of} the main exhaust gas mass flow ṁ _Abg . Such regulations regulate the second exhaust gas mass flow ṁ _{Abg, 2} such that a fixed temperature T _{Abgs, 2 of} the second exhaust gas mass flow ṁ _{Abg, 2} of 40 ° C., for example, is achieved. In order to achieve this, the second exhaust gas mass flow ṁ _{Abg, 2} is reduced to such an extent that a cooler can cool the exhaust gas mass flow ṁ _{Abg, 2} to the fixed temperature of 40 ° C with a fixed cooling capacity. This has the disadvantageous consequence that only a reduced exhaust gas mass flow ṁ _{Abg, 2} is available for water recovery, whereby the condensate flow ṁ _{K is} also reduced. Accordingly, the rate of water recovery from the exhaust gas decreases.

In contrast, the method according to the invention enables a high rate of water recovery from the exhaust gas of the internal combustion engine. This water can preferably be stored in a water tank and, if necessary, fed to an injection device of the internal combustion engine. This enables manual filling of the tank with water to be advantageously avoided. This enables a reduction in maintenance costs for the internal combustion engine.

• - eine Hauptabgasleitung (3) zum Abführen eines Hauptabgasmassenstroms ṁ_Abg aus dem Verbrennungsmotor (2),
• - einer ersten Temperaturermittlungseinrichtung (11) zum Ermitteln einer Temperatur T_Abgs,1 des Hauptabgasmassenstroms ṁ_Abg,
• - eine erste Abgasteilleitung (5) zum Abführen eines ersten Abgasmassenstroms ṁ_Abg,1 aus der Hauptabgasleitung (3),
• - eine zweite Abgasteilleitung (4) zum Abführen eines zweiten Abgasmassenstroms ṁ_Abg,2 aus der Abgasleitung (3),
• - einen Kondensator (7) zur Rückgewinnung von Wasser aus dem zweiten Abgasmassenstrom ṁ_Abg,2 in einem Kondensatstrom ṁ_K und
• - ein regelbares Ventil (8) zum Regeln des zweiten Abgasmassenstroms ṁ_Abg,2 in Abhängigkeit von der Temperatur T_Abgs,1 des Hauptabgasmassenstroms ṁ_Abg.

A system according to the invention for recovering water from an exhaust gas of an internal combustion engine is designed and set up to carry out and comprises a method according to one of the preceding claims

• - a main exhaust pipe ( 3 ) for discharging a main exhaust gas mass flow ṁ _exhaust from the combustion engine ( 2 ),
• - a first temperature determination device ( 11 ) to determine a temperature T _{Abgs, 1 of} the main _{exhaust gas mass flow} ṁ _Abg ,
• - a first exhaust pipe ( 5 ) to discharge a first exhaust gas mass flow ṁ _{Abg, 1} from the main exhaust line ( 3 ),
• - a second exhaust pipe ( 4th ) to discharge a second exhaust gas mass flow ṁ _{Abg, 2} from the exhaust pipe ( 3 ),
• - a capacitor ( 7th ) for the recovery of water from the second exhaust gas mass flow ṁ _{Abg, 2} in a condensate flow ṁ _K and
• - an adjustable valve ( 8th ) for regulating the second exhaust gas mass flow ṁ _{Abg, 2} depending on the temperature T _{Abgs, 1 of} the main exhaust gas mass flow ṁ _Abg .

The advantages of the method according to the invention also result in the same way for the system according to the invention.

In addition, low production costs for the system are made possible. The reason for this is that the temperature determination device necessary for regulating the second exhaust gas mass flow ṁ _{Abg, 2} and the controllable valve are already present in many internal combustion engines. In all other cases, they can be retrofitted without major financial outlay.

The dependent claims describe advantageous embodiments of the invention.

• 1 schematisch ein erstes Ausführungsbeispiel eines erfindungsgemäßen Systems zur Rückgewinnung von Wasser aus einem Abgas eines Verbrennungsmotors und
• 2 schematisch ein Diagramm für eine Abhängigkeit zwischen der Temperatur T_Abgs,1 des Hauptabgasmassenstroms ṁ_Abg.und dem zweiten Abgasmassenstrom ṁ_Abg,2 .

Preferred exemplary embodiments are explained in more detail with reference to the following figures. It shows

• 1 schematically a first embodiment of a system according to the invention for the recovery of water from an exhaust gas of an internal combustion engine and
• 2 schematically illustrates a diagram for a relationship between the temperature T _{CLSD, 1} of the main exhaust gas mass flow ṁ _Abg .and the second exhaust gas mass flow ṁ _{Abg; 2.}

• - eine Hauptabgasleitung 3 zum Abführen eines Hauptabgasmassenstroms ṁ_Abg aus dem Verbrennungsmotor 2,
• - einer ersten Temperaturermittlungseinrichtung 11 zum Ermitteln einer Temperatur T_Abgs,1 des Hauptabgasmassenstroms ṁ_Abg,
• - eine erste Abgasteilleitung 5 zum Abführen eines ersten Abgasmassenstroms ṁ_Abg,1 aus der Hauptabgasleitung 3,
• - eine zweite Abgasteilleitung 4 zum Abführen eines zweiten Abgasmassenstroms ṁ_Abg,2 aus der Abgasleitung 3,
• - einen Kondensator 7 zur Rückgewinnung von Wasser aus dem zweiten Abgasmassenstrom ṁ_Abg,2 in einem Kondensatstrom ṁ_K und
• - ein regelbares Ventil 8 zum Regeln des zweiten Abgasmassenstroms ṁ_Abg,2 in Abhängigkeit von der Temperatur T_Abgs,1 des Hauptabgasmassenstroms ṁ_Abg .

1 shows an embodiment of a system according to the invention 1 for the recovery of water from an exhaust gas of an internal combustion engine 2 . The system 1 includes:

• - a main exhaust pipe 3 for discharging a main exhaust gas mass flow ṁ _exhaust from the internal combustion engine 2 ,
• - A first temperature determination device 11 to determine a temperature T _{Abgs, 1 of} the main _{exhaust gas mass flow} ṁ _Abg ,
• - a first exhaust sub-line 5 for discharging a first exhaust gas mass flow ṁ _{Abg, 1} from the main exhaust line 3 ,
• - a second exhaust sub-line 4th for discharging a second exhaust gas mass flow ṁ _{Abg, 2} from the exhaust pipe 3 ,
• - a capacitor 7th for the recovery of water from the second exhaust gas mass flow ṁ _{Abg, 2} in a condensate flow ṁ _K and
• - an adjustable valve 8th for regulating the second exhaust gas mass flow ṁ _{Abg, 2} as a function of the temperature T _{Abgs, 1 of} the main exhaust gas mass flow ṁ _Abg .

The first and second exhaust sub-ducts 4th , 5 allow a splitting of the main exhaust gas mass flow ṁ _Abg into a first exhaust gas mass flow ṁ _{Abg, 1} and a second exhaust gas mass flow ṁ _{Abg; 2.}

In this embodiment the controllable valve is 8th within the first exhaust pipe 5 arranged. This enables the second exhaust gas mass flow ṁ _{Abg, 2} to be regulated as a function of the temperature T _{Abgs, 1 of} the main exhaust gas mass flow ṁ _Abg . The regulation is carried out by the control unit 13 . The control unit 13 controls the adjustable valve for this purpose 8th .

• - einen Kühler (6) zum Kühlen des zweiten Abgasmassenstroms ṁ_Abg,2 zu einem gekühlten zweiten Abgasmassenstroms ṁ_Abg,2,k,
• - einer zweiten Temperaturermittlungseinrichtung 12 zum Ermitteln einer Temperatur T_Abgs,2 des gekühlten zweiten Abgasmassenstroms ṁ_Abg,2,k,

The system 1 also includes:

• - a cooler ( 6 ) for cooling the second exhaust gas mass flow ṁ _{Abg, 2} to a cooled second exhaust gas mass flow ṁ _{Abg, 2, k} ,
• - A second temperature determination device 12 for determining a temperature T _{Abgs, 2 of} the cooled second exhaust gas mass flow ṁ _{Abg, 2, k} ,

The system 1 is designed and set up to regulate the second exhaust gas mass flow ṁ _{Abg, 2} by regulating the temperature T _{Abgs, 2 of} the cooled second exhaust gas mass flow ṁ _{Abg, 2, k} .

The first and the second temperature determining device 11 , 12 are temperature sensors that are designed and set up to determine exhaust gas temperatures by measuring.

The first temperature determining device 11 is inside the main exhaust pipe 3 arranged. The second temperature determining device 12 is within the second exhaust pipe 4th arranged. This arrangement enables the temperatures of the exhaust gases to be measured directly.

Alternatively, the first temperature-determining device 11 and / or the second temperature determination device 12 Devices which are designed and set up to determine exhaust gas temperatures by means of a simulation. In a further alternative embodiment is one of the temperature determination devices 11 trained and set up to determine exhaust gas temperatures through simulations. The other temperature detection device 12 however, is designed and set up to determine exhaust gas temperatures by measuring.

The cooler 6 and the capacitor 7th are within the second exhaust pipe 4th arranged. The cooler 6 is upstream of the capacitor 7th arranged.

The cooled second exhaust gas mass flow ṁ _{Abg, 2, k} is in the condenser 7th for the recovery of water from the cooled second exhaust gas mass flow ṁ _{Abg, 2, k} passed into the condensate flow ṁ _K.

This enables direct cooling of the second exhaust gas mass flow ṁ _{Abg, 2} and recovery of water from the cooled second exhaust gas mass flow ṁ _{Abg, 2, k} . Through the cooler 6 if the cooled second exhaust gas mass flow ṁ _{Abg, 2, k has} a lower temperature than the second exhaust gas mass flow ṁ _{Abg, 2} The lower temperature enables an increase in the rate of water recovery from the exhaust gas.

The second exhaust gas mass flow ṁ _{Abg, 2} is increased by reducing the main exhaust gas mass flow ṁ _Abg . This leads to a higher mass flow through the cooler 6 . This _{results in} a higher temperature T _{Abgs, 2 of} the cooled second exhaust gas mass flow, since the cooler 7th when applying a fixed cooling capacity, a larger exhaust gas mass flow can cool down less.

In this embodiment, the regulation of the second exhaust gas mass flow ṁ _{Abg, 2 takes place} by regulating the temperature T _{Abgs, 2 of} the cooled second exhaust gas mass flow ṁ _{Abg, 2, k} time after the determination of the temperatures T _{Abgs, 1} and T _{Abgs, 2} and after Introducing the cooled second exhaust gas mass flow ṁ _{Abg, 2, k} into the cooler 7th .

A function max _sim for the dependence between the temperature T _{Abgs, 1 of} the main _{exhaust gas mass flow} ṁ _Abg and the second Exhaust gas mass flow ṁ _{Abg, 2} is determined by the control unit 13 determined. Alternatively, the determination is made by an additional computer. The max _sim function in this case becomes the control unit 13 made available.

2 is a diagram showing a relationship between the temperature T _{CLSD, 1} of the main exhaust gas mass flow ṁ _Abg .and the second exhaust gas mass flow ṁ _{Abg; 2.} In addition, a function max _sim and support points of the function max _{sim are} shown.

The function max _sim specifies for a temperature T _{Abgs, 1} that second exhaust gas mass flow ṁ _{Abg, 2} at which the condensate flow ṁ _{K is} maximal.

The max _sim function is in the control unit 13 deposited. This enables a quick and uncomplicated determination of the temperature T _{Abgs, 2} depending on the temperature T _{Abgs, 1} and thus an efficient control of the second exhaust gas mass flow ṁ _{Abg, 2} for all temperatures T _{Abgs, 1 of} the main exhaust gas mass flow ṁ _Abg .

Alternatively, only support points of the function are taken into account, for example in a characteristic diagram in the control unit 13 are deposited. However, this would only enable efficient regulation for temperatures T _{Abgs, 1} which match the support points. Therefore, in this alternative, for temperatures T _{Abgs, 1} that lie between two support points, a mathematical averaging is carried out between the surrounding support points in order to determine the temperature T _{Abgs, 2} .

This step takes place before all other steps are carried out.

The control unit 13 determines the max _sim function based on a simulation of physical properties of exhaust gas mass flows. This enables the second exhaust gas mass flow ṁ _{Abg, 2 to be} regulated in such a way that the condensate flow ṁ _K becomes a maximum without the need for additional sensors to determine the function.

In this exemplary embodiment, simulations are carried out for 7 support points. The support points are chosen so that a temperature T _{Abgs, 1} of 723 ° C. is included. This corresponds to the use of the internal combustion engine 2 in a vehicle, for example, a vehicle speed of> 150 km / h. This temperature thus corresponds to full load operation of the internal combustion engine 2 .

Furthermore, a temperature T _{Abgs, 1} of 184 ° C. is included in the support points. This temperature is during a low load operation of the internal combustion engine 2 reached. Further support points are arranged between 183 ° C and 723 ° C.

The control unit 13 determines the function max _{sim in} such a way that it _falls monotonically with increasing temperature T _{Abgs, 1} and / or that it has approximately linear ranges. This enables a simpler calculation of the second exhaust gas mass flow ṁ _{Abg, 2} . This means that regulation can take place quickly and efficiently.

The control unit 13 determines a minimum second exhaust gas mass flow ṁ _{Abg, 2} for which the condensate flow ṁ _K = 0.

This determination takes place for a fixed temperature T _{Abgs, 1} . The minimum second exhaust gas mass flow ṁ _{Abg, 2} is determined in such a way that it has a dew point temperature at this fixed temperature T _{Abgs, 1} . Below this temperature and / or below this exhaust gas mass flow ṁ _{Abg, 2} , condensation of water, that is to say a condensate flow ṁ _K > 0, is made possible.

In this exemplary embodiment, the dew point temperatures for second exhaust gas mass flows ṁ _{Abg, 2 are} determined on the basis of ambient air humidity, an amount of water injected into the internal combustion engine 2 , an amount of fuel injected into the internal combustion engine 2 and / or one from the internal combustion engine 2 sucked air volume determined by a simulation. An ambient humidity, an amount of water injected into the internal combustion engine 2 , an amount of fuel injected into the internal combustion engine 2 and / or one from the internal combustion engine 2 The amount of air sucked in is determined by standard combustion engines anyway. Accordingly, a determination of the dew point temperatures for second exhaust gas mass flows ṁ _{Abg, 2 is} made possible with only low costs.

The control unit 13 determines an optimal second exhaust gas mass flow ṁ _{Abg, 2} depending on the minimum second exhaust gas mass flow ṁ _{Abg, 2} . in such a way that its amount corresponds to a fraction of the amount of the minimum second exhaust gas mass flow ṁ _{Abg, 2} . The fraction is fixed and corresponds to about 60%.

The optimal second exhaust gas mass flow ṁ _{Abg, 2} generally corresponds to about 60% of the minimum second exhaust gas mass flow ṁ _{Abg, 2} . This was determined through a variety of simulations and measurements. The fixed fraction determined in this way enables a very simple calculation of the optimal second exhaust gas mass flow ṁ _{Abg, 2} . Only the dew point temperature for the respective second exhaust gas mass flow ṁ _{Abg, 2 is} required for this determination.

Alternatively, the fraction is between 50% and 70%.

QUOTES INCLUDED IN THE DESCRIPTION

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Patent literature cited

• CA 2700485 A [0002]

Claims (10)

A method for recovering water from an exhaust gas of an internal combustion engine (2), comprising the steps of: determining a temperature T _{Abgs, 1 of} a main exhaust gas _{mass flow} ṁ _{Abg of} the internal combustion engine (1); - Splitting the main exhaust gas mass flow ṁ _Abg into a first exhaust gas mass flow ṁ _{Abg, 1} and a second exhaust gas mass flow ṁ _{Abg, 2} ; - Introducing the second exhaust gas mass flow ṁ _{Abg, 2} into a condenser (7) for the recovery of water from the second exhaust gas mass flow ṁ _{Abg, 2} in a condensate flow ṁ _K ; - Regulation of the second exhaust gas mass flow ṁ _{Abg, 2} depending on the temperature T _{Abgs, 1 of} the main exhaust gas mass flow ṁ _Abg . Procedure according to Claim 1 , comprising the steps of: - cooling the second exhaust gas mass flow ṁ _{Abg, 2} to a cooled second exhaust gas mass flow ṁ _{Abg, 2, k} by a cooler (7); - Determining a temperature T _{Abgs, 2 of} the cooled second exhaust gas mass flow ṁ _{Abg, 2, k} ; - Regulation of the second exhaust gas mass flow ṁ _{Abg, 2} by regulating the temperature T _{Abgs, 2 of} the cooled second exhaust gas mass flow ṁ _{Abg, 2, k} . Method according to one of the preceding claims, comprising the step: - determining a minimum second exhaust gas mass flow ṁ _{Abg, 2} . for which the condensate flow ṁ _K = 0. Procedure according to Claim 3 , comprising the step: determining an optimal second exhaust gas mass flow ṁ _{Abg, 2} as a function of the minimum second exhaust gas mass flow ṁ _{Abg, 2} . Method according to one of the Claims 3 to 4th Comprising the step of: - determining an optimum second exhaust gas mass flow ṁ _Abg, .derart ₂ that he magnitude a fraction of the amount of the minimum mass flow ṁ _Abg second _{exhaust, 2} corresponds. Procedure according to Claim 5 , comprising the step: determining the optimal second exhaust gas mass flow ṁ exhaust _{, 2.} such that the fraction corresponds to about 60%. Method according to one of the preceding claims, comprising the step of: - determining a function _sim max for the dependence between the temperature T _{CLSD, 1} of the main exhaust gas mass flow ṁ _Abg and the second exhaust gas mass flow ṁ _{Abg, 2} Procedure according to Claim 7 , comprising the steps: determining the function max _sim on the basis of a simulation of physical properties of exhaust gas mass flows; and / or determining the function max _{sim in} such a way that it _falls monotonically with increasing temperature T _{Abgs, 1} and / or determining the function max _sim such that it has approximately linear ranges. System (1) for the recovery of water from an exhaust gas of an internal combustion engine (2), designed and set up to carry out a method according to one of the preceding claims and comprising - a main exhaust gas line (3) for discharging a main exhaust gas mass flow ṁ _exhaust from the internal combustion engine (2), - a first temperature detecting means (11) for determining a temperature T _{CLSD, 1} of the main exhaust gas mass flow ṁ _Abg, - a first partial exhaust line (5) for discharging a first exhaust gas mass flow ṁ _{Abg, 1} from the main exhaust line (3), - a second partial exhaust line (4) for Discharge of a second exhaust gas mass flow ṁ _{Abg, 2} from the exhaust pipe (3), - a condenser (7) for the recovery of water from the second exhaust gas mass flow ṁ _{Abg, 2} in a condensate flow ṁ _K and - a controllable valve (8) for regulating the second Exhaust gas mass flow ṁ _{Abg, 2} depending on the temperature T _{Abgs, 1 of} the main exhaust gas mass flow ṁ _Abg . System (1) according to Claim 8 , comprising - a cooler (6) for cooling the second exhaust gas mass flow ṁ _{Abg, 2} to a cooled second exhaust gas mass flow ṁ _{Abg, 2, k} , - a second temperature determining _device (12) for determining a temperature T _{Abgs, 2 of} the cooled second exhaust gas mass flow ṁ _{Abg , 2, k} , - the system (1) being designed and set up to regulate the second exhaust gas mass flow ṁ _{Abg, 2} by regulating the temperature T _{Abgs, 2 of} the cooled second exhaust gas mass flow ṁ _{Abg, 2, k} .

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