DK180561B1

DK180561B1 - An internal combustion engine configured for determining specific emissions and a method for determining specific emissions of an internal combustion engine

Info

Publication number: DK180561B1
Application number: DKPA202070149A
Authority: DK
Inventors: Larsson David; La Seta Angelo
Original assignee: Man Energy Solutions Filial Af Man Energy Solutions Se Tyskland
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2021-06-24
Also published as: CN113356984B; JP2021139367A; JP6938800B2; KR102279489B1; DK202070149A1; CN113356984A

Abstract

An internal combustion engine operating on a given fuel and producing exhaust gas during operation thought combustion of the given fuel with intake air. The engine comprises a controller (50), a sensor (40) configured to detect a concentration of a first exhaust gas component in the exhaust gas, a sensor (41) configured to detect a concentration of a reference gas in the exhaust gas. The reference gas is oxygen or carbon dioxide. The controller (50) is configured to determine the difference in reference gas concentration between the intake air and the exhaust gas, to determine the specific emission of the first exhaust gas component as a function of the detected concentration of the first exhaust gas component and as a function of the determined difference in reference gas concentration between the intake air and the exhaust gas. A method for determining a specific emission of an exhaust gas component of an internal combustion engine. The method comprises detecting a concentration of a first exhaust gas component in the exhaust gas, detecting a concentration of a reference gas in the exhaust gas, the reference gas being oxygen or carbon dioxide, determining the difference in reference gas concentration between the intake air and the exhaust gas, determining the specific emission of the first exhaust gas component as a function of the detected concentration of a first exhaust gas and as a function of the determined difference in reference gas concentration between the intake air and the exhaust gas.

Description

DK 180561 B1 1

AN INTERNAL COMBUSTION ENGINE CONFIGURED FOR DETERMINING SPECIFIC EMISSIONS AND A METHOD FOR DETERMINING SPECIFIC EMISSIONS OF AN INTERNAL COMBUSTION ENGINE

TECHNICAL FIELD The disclosure relates to internal combustion engines that are operated to combust a given fuel with air thereby producing exhaust gas, in particular, large two-stroke uniflow scavenged internal combustion engines with crossheads.

BACKGROUND Large two-stroke turbocharged uniflow scavenged internal combustion engines with crossheads are for example used for propulsion of large oceangoing vessels or as primary mover in a power plant. Not only due to sheer size, these two-stroke diesel engines are constructed differently from any other internal combustion engines. These large two-stroke turbocharged uniflow scavenged internal combustion engines are increasingly being subjected to stricter emission regulations. There is been a fast pace of technological development to meet these emission regulations, e.g. by changing to cleaner fuels, improved fuel injection systems and by adding exhaust gas treatment systems including e.g. selective catalytic reduction, just to mention a few. The emission regulations for these engines define the emission levels as specific emission levels, i.e. the emission levels are limited to a maximum mass produced in the exhaust gas per kilowatt-hour delivered at the shaft of the engine

DK 180561 B1 2 [g/kWh]. Thus, these emission limits are also referred to as brake specific limits.

In practice, the limit is implemented in the form of a total weighted cycle emission limit (g/kWh). Such a limit is for example imposed by the International Maritime Organization (IMO). An example of a component of the exhaust gas that is limited in such a way is Nitrogen Oxides (NOx). Measuring the concentration of NOx, e.g. in parts per million (PPM) in the exhaust gas of a large two-stroke internal combustion engine that is operating e.g. as a prime mover in a marine vessel is relatively simple.

However, converting such a measured NOx concentration in the exhaust gas to a specific value in g/kWh is a daunting task when the engine is not on a testbed.

Thus, in practice, large two-stroke internal combustion engines are tested for emissions on a testbed where the engine is connected to a water brake.

The torque and speed readings from the water brake provide accurate information about the power delivered at the engine shaft.

Such information is not available for an engine that is used as a prime mover in a marine vessel.

Thus, presently large two-stroke engines are certified in a shop test where compliance with NOx regulation is proven once.

The ship/engine is then in compliance if it can prove that neither key “NOx components” nor NOx influencing engine tuning has been modified.

This model fits well for engines that are tuned once and the tuning remains accurate.

IMO Tier III NOx regulation requires NOx reduction technologies that bring NOx emission substantially lower than possible with engine tuning alone.

It is yet to be determined

DK 180561 B1 3 if these NOx reduction systems will prove compliance only once on a shop test, or by continuous monitoring and/or closed-loop control based on continuously measured NOx emissions.

However, there is no simple official method to measure specific NOx emissions in service. Not being able to determine whether the engine in operation fulfills the legal requirements of specific emissions is a problem since an engine manufacturer will wish to optimize the engine operation and in particular the exhaust gas treatment systems to ensure that the legal limits are respected. However, with the legal limits being defined as specific emissions and with the measurements during operation only providing emissions as a concentration in the exhaust gas this is not feasible.

Another complicating factor is that the exhaust gas treatment systems, e.g. for the reduction of NOx in a selected catalytic reduction process need to admit a dosed amount of reductant (e.g. urea), to the exhaust gas. Presently, this is done in a feedforward way which can lead to significant deviations from the optimal levels of reductant admitted due to e.g. different locations for the installation of the reductant pumps and different piping and the resulting different flow of reductant. It would, therefore, be an advantage if the efficiency of the selected catalytic reduction process could be monitored on an operating engine.

JPH10131789 discloses an internal combustion engine and method according to the preamble of the independent claims.

DK 180561 B1 4 This Otto cycle engine uses an oxygen sensor and an NOx sensor for controlling the air-fuel ratio.

SUMMARY It is an object of the invention to provide a system that overcomes or at least reduces the problem indicated above.

The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect, an internal combustion engine is provided, the engine is configured for operating on a given fuel and producing exhaust gas during operation through combustion of the given fuel with intake air, the engine comprising: - a controller, - a sensor configured to detect a concentration of a first exhaust gas component in the exhaust gas, - a sensor configured to detect a concentration of a reference gas in the exhaust gas, the reference gas being oxygen or carbon dioxide, the controller being configured to: - determine the difference in reference gas concentration between the intake air and the exhaust gas, - determine the specific emission of the first exhaust gas component as a function of the detected concentration of the first exhaust gas component and as a function of the determined difference in reference gas concentration between the intake air and the exhaust gas.

DK 180561 B1

By measuring the concentration of a first exhaust gas component in the exhaust gas, and by determining the difference in reference gas concentration between the inlet air and the exhaust gas, and relating this information to the 5 type of fuel used and to the (momentary) fuel efficiency of the engine, an accurate estimate of the amount of emission of the first exhaust gas component per kilowatt-hour produced by the engine can be obtained.

This enables calculating the specific emission for the first exhaust gas component without knowing the exhaust flow or the complete exhaust composition.

This is possible through the insight that the oxygen reduction (or the carbon dioxide increase) is in direct proportion to the energy consumed.

The consumed amount of oxygen per fuel heat unit is almost the same for many fuels, but the engine is preferably configured to take into account the characteristics of the actual fuel that is used in the engine.

For the increase in carbon dioxide, the calculation is more sensitive to the type of fuel used, and if carbon dioxide is used as the reference gas the actual compensation factor for the fuel type needs to be determined.

Thus, knowing the fuel characteristics and knowing the oxygen reduction (or carbon dioxide increase) allows the calculation of an accurate estimate of the amount of energy consumed.

The controller also uses the energy efficiency of the engine as a factor in the calculation, so that the energy produced is calculated accurately.

Hereto, the controller is in an embodiment provided with a lookup table, algorithms or a computer model of the engine to determine the energy

DK 180561 B1 6 efficiency of the engine under the momentary operating conditions. According to a possible implementation of the first aspect, the controller is configured to determine the reference gas concentration in the intake air as a function of the humidity of the intake air. According to a possible implementation of the first aspect, the controller is configured to determine the momentary fuel efficiency of the engine, and wherein the controller is configured to apply the determined fuel efficiency as a factor when determining the specific emission of the first exhaust gas component.

According to a possible implementation of the first aspect wherein the controller preferably is provided with, a lookup table and/or an algorithm and/or with a computer model of the engine to determine the momentary fuel efficiency based on the momentary operating conditions. According to a possible implementation of the first aspect, the controller is configured to apply a fuel factor associated with the given fuel when determining the specific emission of the first exhaust gas component According to a possible implementation of the first aspect, the controller is configured to determine the specific emission of the first exhaust gas component by dividing the detected concentration of the first exhaust gas component in the exhaust gas by the product of the determined difference

DK 180561 B1 7 in reference gas concentration between the intake air and the exhaust gas and an adjustment factor. According to a possible implementation of the first aspect, the adjustment factor comprises a momentary fuel efficiency of the engine determined by the controller. According to a possible implementation of the first aspect, the adjustment factor comprises a fuel factor associated with the given fuel. According to a possible implementation of the first aspect, the controller is configured to determine the specific emission of the first exhaust gas component by dividing the detected concentration of the first exhaust gas component in the exhaust gas by the product of the determined difference in reference gas concentration between the intake air and the exhaust gas, a momentary fuel efficiency of the engine determined by the controller and a fuel factor associated with the given fuel. According to a possible implementation of the first aspect, the first exhaust gas component is one of: CO, CO2, HC, CH4, NOx, SOx, NH3, PM, PN or BC.

According to a possible implementation of the first aspect, the first exhaust gas component is NOx, the engine being configured to operate under control of the controller (50), and the controller being configured to control the operation of the engine as a function of the determined specific NOx emission.

DK 180561 B1 8 According to a possible implementation of the first aspect, the first exhaust gas component is NOx, the engine comprising an NOx treatment system that is configured to be operated under control of the controller, and the controller being configured to control the operation of the NOx treatment system as a function of the determined specific NOx emission.

According to a possible implementation of the first aspect, the NOx treatment system is configured to administer a reductant to the exhaust gas, and wherein the amount of reductant administered to the exhaust gas is controlled by the controller(50) as a function of the determined specific NOx emission.

According to a second aspect there is provided a method for determining a specific emission of a first exhaust gas component of an internal combustion engine, the method comprising: - detecting a concentration of a first exhaust gas component in the exhaust gas, - detecting a concentration of a reference gas in the exhaust gas, the reference gas being oxygen or carbon dioxide, - determining the difference in reference gas concentration between the intake air and the exhaust gas, - determining the specific emission of the first exhaust gas component as a function of the detected concentration of the first exhaust gas and as a function of the

DK 180561 B1 9 determined difference in reference gas concentration between the intake air and the exhaust gas. According to a possible implementation of the second aspect, the method comprises determining the reference gas concentration in the intake air as a function of the humidity of the intake air. According to a possible implementation of the second aspect, the method comprises determining the momentary fuel efficiency of the engine, and applying the determined fuel efficiency as a factor when determining the specific emission of the first exhaust gas component.

According to a possible implementation of the second aspect, the method comprises applying, a lookup table and/or an algorithm and/or a computer model of the engine when determining the momentary fuel efficiency based the momentary operating conditions.

According to a possible implementation of the second aspect, the method comprises applying a fuel factor associated with the given fuel when determining the specific emission of the first exhaust gas component According to a possible implementation of the second aspect, the method comprises determining the specific emission of the first exhaust gas component by dividing the detected concentration of the first exhaust gas component in the exhaust gas by the product of the determined difference in

DK 180561 B1 10 reference gas concentration between the intake air and the exhaust gas and an adjustment factor. According to a possible implementation of the second aspect, the adjustment factor comprises a momentary fuel efficiency of the engine determined by the controller. According to a possible implementation of the second aspect, the adjustment factor comprises a fuel factor associated with the given fuel. According to a possible implementation of the second aspect, the method comprises determining the specific emission of the first exhaust gas component by dividing the detected concentration of the first exhaust gas component in the exhaust gas by the product of the determined difference in reference gas concentration between the intake air and the exhaust gas, a momentary fuel efficiency of the engine determined by the controller and a fuel factor associated with the given fuel. According to a possible implementation of the second aspect, the first exhaust gas component is one of: CO, CO2, HC, CH4, NOx, SOx, NH3, PM, PN or BC.

These and other aspects of the invention will be apparent from and the embodiment described below.

BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed portion of the present disclosure, the invention will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

DK 180561 B1 11 Fig. 1 is an elevated front view of a large two-stroke diesel engine according to an example embodiment, Fig. 2 is an elevated side view of the large two-stroke engine of Fig. 1, Fig. 3 is a diagrammatic representation the large two-stroke engine according to Fig. 1 showing a system for determining a specific emission of the engine, and Fig. 4 is a block diagram illustrating a controller and an algorithm used in the system for determining a specific emission of the engine.

DETAILED DESCRIPTION In the following detailed description, an internal combustion engine will be described with reference to a large two-stroke low-speed turbocharged internal combustion engine with crossheads in the example embodiments.

Figs. 1 and 2 are elevated views of a large low-speed turbocharged two-stroke internal combustion engine with a crankshaft 8 and crossheads 9. The engine can be operated with the Diesel (compression ignited) or the Otto cycle (timed ignition).

Fig. 3 shows a diagrammatic representation of the large low- speed turbocharged two-stroke internal combustion engine of figs 1 and 2 with its intake and exhaust systems. In this example embodiment, the engine has six cylinders in line.

Large low-speed turbocharged two-stroke diesel engines have typically between four and fourteen cylinders in line, carried

DK 180561 B1 12 by a cylinder frame 23 that is carried by an engine frame 11. The engine may e.g. be used as the main engine in a marine vessel or as a stationary engine for operating a generator in a power station.

The total output of the engine may, for example, range from 1,000 to 110,000 kW.

The engine is in this example embodiment a compression-ignited engine of the two-stroke uniflow type with scavenge ports 18 at the lower region of the cylinder liners 1 and a central exhaust valve 4 at the top of the cylinder liners 1. The scavenge air is passed from the scavenge air receiver 2 to the scavenge ports 18 of the individual cylinders 1. A piston 10 in the cylinder liner 1 compresses the scavenge air, fuel is injected through fuel injection valves 31 in the cylinder cover 22, combustion follows and exhaust gas is generated.

When an exhaust valve 4 is opened, the exhaust gas flows through an exhaust duct associated with the cylinder 1 into the exhaust gas receiver 3 and onwards through a first exhaust conduit 19 to a turbine 6 of the turbocharger 5, from which the exhaust gas flows away through a second exhaust conduit via an economizer 20 to an outlet 21 and into the atmosphere.

Through a shaft, the turbine 6 drives a compressor 7 supplied with fresh air via an air inlet 12. The compressor 7 delivers pressurized scavenge air to a scavenge air conduit 13 leading to the scavenge air receiver 2. The scavenge air in conduit 13 passes an intercooler 14 for cooling the scavenge air.

The cooled scavenge air passes via an auxiliary blower 16 driven by an electric motor 17 that pressurizes the scavenge airflow when the compressor 7 of the turbocharger 5 does not

DK 180561 B1 13 deliver sufficient pressure for the scavenge air receiver 2, i.e. in low- or partial load conditions of the engine.

At higher engine loads the turbocharger compressor 7 delivers sufficient compressed scavenge air and then the auxiliary blower 16 is bypassed via a non-return valve 15. The engine is operated with a given fuel, such as for example, marine diesel, heavy fuel oil, (liquified) natural gas, coal gas, biogas, Methanol, Ethanol, Ethane, landfill gas, methane, ethylene or (liquified) petroleum gas (nonexhaustive list), that is supplied by a fuel supply system 30. A fuel supply system 35 includes the required pumps/blowers and fuel valves 31 and is controlled by an electronic control unit 50, via e.g. signal lines.

The electronic control unit 50 is in receipt of engine operating parameters, such as e.g. the crankshaft speed and position through crank position sensor 39, and the humidity of the air in the engine room through humidity sensor 33, also connected e.g. to the electronic control unit 50 by a signal line.

This is a nonexhaustive list of operating parameters, and the electronic control unit 50 may well be in receipt of other engine operating parameters such as e.g. scavenging air temperature and pressure, exhaust gas temperature and pressure, compression pressure as well known by in the art.

A sensor 40 that is configured to detect the NOx concentration, for example in parts per million, is arranged in the exhaust stack.

In an embodiment, the sensor 40 is a commercially available NOx sensor.

DK 180561 B1 14 Another sensor 41 that is configured to detect the concentration of a reference gas in parts per million in the exhaust gas is also arranged in the exhaust stack. The reference gas can be oxygen or carbon dioxide. In the present embodiment oxygen will be used as a prime example for the reference gas. In the present embodiment the sensors 40 and 41 are shown to be in second exhaust conduit 19, i.e. on the low-pressure side of the turbocharger (downstream of the turbine 6), but it should be understood that the sensors 40,41 could also be arranged on the high-pressure side of the turbocharger, i.e. downstream of the turbine 6.

Further, it is not necessary to perform the detection in situ, and it should be understood that a sample could be extracted from the exhaust gas and analyzed at another location.

A single sensor may be capable of sensing both the oxygen concentration in the exhaust gas and the NOx concentration in the exhaust gas and thus, the sensor 40 and the sensor 41 can be formed by one single physical sensor.

In an embodiment (not shown) there is provided another sensor that is configured to detect the presence of a second component of the exhaust gas. It is noted that neither the first nor the second exhaust gas component can be oxygen, since oxygen is not considered to be a component of the exhaust gas that is relevant to be determined as in a specific emission.

DK 180561 B1 15 A signal from the sensor 40 that detects the concentration of NOx in the exhaust gas and a signal from the sensor 41 that detects the concentration of reference gas (oxygen or carbon dioxide) in the exhaust is transmitted to the electronic control unit 50, for example through signal lines. An exhaust gas treatment system 30, for example including an SCR reactor can be provided on the high-pressure side of the turbocharger 5 or on the low-pressure side of the turbocharger

5. In the present embodiment, the exhaust gas treatment system is shown on the high-pressure side of the turbocharger 5, but it should be understood that the SCR reactor can also be arranged at the low-pressure side of the turbocharger 5. The SCR reactor is provided with a stream of reactant, such as e.g. urea. Th amount of reactant added to the exhaust gas in the SCR reactor is controlled by the electronic control unit

50. Similarly, the engine control system (electronic control unit 50) applies in an embodiment specific NOx feedback control of EGR, Water in fuel, direct water injection, low NOx fuels, humid air and/or engine performance adjustments. Fig. 4, shows an algorithm used by the electronic control unit 50 to determine a specific emission of an exhaust gas component of the engine. The electronic control unit 50 is configured to determine the difference in oxygen concentration between the intake air and the exhaust gas. The signal from the humidity sensor 33 allows the electronic control unit 50 to determine the humidity of the air in the engine room and through an algorithm to

DK 180561 B1 16 estimate the oxygen concentration of the air in the engine room, 1.e. the oxygen concentration in the intake air. The algorithm reflects the relation of the function between oxygen content and humidity of ambient air. The oxygen content of dry air is 20,95%. In an embodiment, the algorithm determines the inlet air oxygen concentration [mol%] to be equal to: 20,95 x (100/ (100 + inlet air molar humidity [mol%])) The electronic control unit 50 is further configured to determine the specific NOx emission as a function of the detected concentration of NOx in the exhaust gas and as a function of the determined difference in oxygen concentration between the intake air and the exhaust gas.

In an embodiment, the electronic control unit 50 is configured to determine the momentary fuel efficiency of the engine and configured to apply the determined fuel efficiency as a factor when determining the specific emission for an exhaust gas component, such as e.g. NOx. In order to determine the momentary fuel efficiency, the electronic control unit 50 is provided with a lookup table and/or an algorithm and/or with a computer model of the engine and determines or simulates the momentary fuel efficiency is a function of the momentary operating conditions.

In an embodiment, the electronic control unit 50 is configured to apply a fuel factor associated with then fuel when used determining the specific NOx emission.

DK 180561 B1 17 The fuel factor reflects the heat release for each mass unit of used oxygen for a specific fuel. This factor is also referred to in the art as the Thornton factor. Many fuels that are used in a large two-stroke internal combustion engine, such as diesel oil, heavy fuel oil, methane, methanol, ethane, ethanol, propane and buthane, the fuel factor is approximately 12,8 MJ/kg oxygen consumed. Thus, this value for the fuel factor can be used, regardless of which of the above-listed fuels are used to power the engine.

If carbon dioxide is used as the reference gas, this needs to be reflected in the fuel factor. The fuel factor is different when determining the heat release based on the increase in CO2 between the inlet air and the exhaust gas. The CO2 related fuel factor is more sensitive to the type of fuel used and will need to be adjusted to the specific fuel used. The electronic control unit 50 is configured to determine the specific NOx emission by dividing the detected NOx concentration the product of the determined difference in oxygen concentration between the intake air and the exhaust gas and an adjustment factor. The adjustment factor takes into account the type of fuel used and the fuel efficiency of the engine, in order to arrive at an accurate estimate of the energy delivered at the crankshaft of the engine. Thus, the adjustment factor comprises a momentary fuel efficiency of the engine determined by the electronic control unit 50 and a fuel factor associated with the fuel used to operate the engine.

DK 180561 B1 18 Specifically, as shown in Fig.4 the algorithm determines the specific NOx emission by dividing the detected NOx concentration by the product of the determined difference in oxygen concentration between the intake air and the exhaust gas, the momentary fuel efficiency of the engine determined by the algorithm and a fuel factor associated with the fuel used to operate the engine. The algorithm returns with the specific NOx emission in g/kWh.

In an embodiment, the algorithm uses a corrected O02 concentration in which the inlet oxygen content is corrected for the difference in the number of moles in exhaust and air. This is in an embodiment done by introducing a second fuel constant reflecting the stoichiometric molar ratio between exhaust and inlet air. The actual correction 1s then calculated by algorithm momentarily by linear interpolation between stoichiometric ratio and pure air according to the actual measured exhaust oxygen concentration. However, it should be understood that the corrected 02 concentration can be determined in other ways, well known to the skilled person. In an embodiment the algorithm uses the following equation: Specific NOx [g/kWh] = Measured NOx [ppm]/ (Fuel factor - Engine efficiency - Corrected 02 concentration difference [%]) In another embodiment the algorithm uses the following equation: Specific NOx [g/kWh] = Measured NOx [ppm]/ (Fuel factor Engine efficiency « 02 consumption [%])

DK 180561 B1 19 02 consumed [%]” is 02 concentration reduction percentage. It is applied as 02 concentration reduction, % point, or as 02 concentration reduction % or 02 concentration difference, which can be maximum 20,95 % (when all 02 has been consumed). In an embodiment the fuel factor, or a further correction factor, accounts also for the conversion from exhaust mass flows to molar concentrations used in the embodiment.

The embodiments above have been described using oxygen as the reference gas. It is however understood that carbon dioxide can equally be used as reference gas. When using carbon dioxide as the reference counts the increase in carbon dioxide between the inlet air and the exhaust gas should be determined instead of the reduction in oxygen content between the inlet air and the exhaust gas.

In an embodiment, the electronic control unit 50 is configured to control the operation of the engine as a function of the determined specific NOx emission. This may include e.g. control and the fuel injection timing, the exhaust wvalve timing and the operation of the exhaust gas treatment system 30 as a function of the determined specific NOx emission, preferably to stay within the legal limits. For the NOx treatment system, the control involves the control of the amount of reductant administered to the exhaust gas for the selective catalytic reduction, as a function of the determined specific and NOx emission.

The embodiment has been described above with reference to the first exhaust gas component being NOx. However, it is

DK 180561 B1 20 understood that the exhaust gas component could be any component that is present in the exhaust gas such as for example: carbon monoxide (CO), carbon dioxide (Coz), hydrocarbon (HC), methane (CH4), oxides of sulphur (SOx) (S02 + S03), ammonia NH3, particulate matter (PM), particle number (PN )or black carbon (BC), nonexhaustive list. Further, as mentioned above, a second exhaust gas component can also be measured and the specific missions for the second exhaust gas component can be determined simultaneously with the specific emissions of the first exhaust gas component. The second exhaust gas component can be any of the exhaust gas components listed above.

The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor, control unit or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching,

arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure.

Claims

. DK 180561 B1 PATENTKRAV

Internal combustion engine, which engine is configured to run on a given fuel and produce exhaust gas in operation by combustion of the given fuel with intake air, which engine comprises: - a control unit (50), - a sensor (40) configured to detect a concentration of a first exhaust gas component in the exhaust gas, - a sensor (41) configured to detect a concentration of a reference gas in the exhaust gas, which reference gas is oxygen or carbon dioxide, characterized in that the control unit (50) is configured to: - determine the difference in reference gas concentration between the intake air and the exhaust gas, and - determine the specific emission of the first exhaust gas component as a function of the detected concentration of the first exhaust gas component - as a function of the determined difference in reference gas concentration between the exhaust gas and the exhaust gas.

The engine of claim 1, wherein the control unit (50) is configured to determine the reference gas concentration in the intake air as a function of the humidity of the intake air.

The motor of claim 1 or 2, wherein the control unit (50) is configured to determine the moment of the motor

, DK 180561 B1 fuel efficiency, and wherein the control unit (50) is configured to use the determined fuel efficiency as a factor in determining the specific emission of the first exhaust gas component.

An engine according to claim 3, wherein the control unit (50) is preferably equipped with a look-up table, and / or an algorithm and / or with a computer model of the engine to determine the instantaneous fuel efficiency based on the instantaneous operating conditions.

An engine according to any one of claims 1 to 4, wherein the control unit (50) is configured to use a fuel factor associated with the given fuel in determining the specific emission of the first exhaust gas component.

An engine according to any one of claims 1 to 5, wherein the control unit (50) is configured to determine the specific emission of the first exhaust gas component by dividing the detected concentration of the first exhaust gas component 1 the exhaust gas by the product of the determined difference 1 reference gas concentration between the intake air and the exhaust gas and an adjustment factor.

The engine of claim 6, wherein the adjusting factor comprises an instantaneous fuel efficiency of the engine determined by the control unit.

> DK 180561 B1

An engine according to claim 6 or 7, wherein the adjustment factor comprises a fuel factor associated with the given fuel.

An engine according to any one of claims 1 to 5, wherein the control unit (50) is configured to determine the specific emission of the first exhaust gas component by dividing the detected concentration of the first exhaust gas component in the exhaust gas by the product of the determined difference in reference gas concentration between the intake air and the exhaust gas, an instantaneous fuel efficiency of the engine determined by the control unit (50) and a fuel factor associated with the given fuel.

An engine according to any one of claims 1 to 10, wherein the first exhaust gas component is one of: CO, CO2, HC, CH4, NOx, SOx, NH3, PM, PN or BC.

An engine according to any one of claims 1 to 10, wherein the first exhaust gas component is NOx, which engine is configured to operate under the control of the control unit (50), and wherein the control unit (50) is configured to control the operation of the engine as a function of the specific NOx emission.

An engine according to any one of claims 1 to 10, wherein the first exhaust gas component is NOx, which engine comprises a NOx treatment system (30) configured to operate under the control of the control unit (50), and wherein the control unit (50) ) is configured to control NOx

2 GB 180561 B1 operation of the treatment system (30) as a function of the specific NOx emission.

The engine of claim 11, wherein the NOx treatment system (30) is configured to supply the exhaust gas with a reducing agent, and wherein the amount of reducing agent supplied to the exhaust gas is controlled by the control unit (50) as a function of the determined, specific NOx emission.

A method for determining a specific emission of the first exhaust gas component of an internal combustion engine, which method comprises: - detecting a concentration of a first exhaust gas component in the exhaust gas, - detecting a concentration of a reference gas in the exhaust gas, wherein the reference gas is oxygen or carbon dioxide, characterized by - determining the difference in reference gas concentration between the intake air and the exhaust gas, - determining the specific emission of the first exhaust gas component as a function of the detected concentration of the first exhaust gas and as a function of the determined difference in reference gas concentration between the intake air and the exhaust gas.

The method of claim 14, comprising determining the reference gas concentration in the intake air as a function of the humidity of the intake air.

. DK 180561 B1

A method according to claim 14 or 15, comprising determining the instantaneous fuel efficiency of the engine, and using the determined fuel efficiency as a factor in determining the specific emission of the first exhaust gas component.

A method according to claim 16, comprising using a look-up table and / or an algorithm and / or a computer model of the engine in determining the instantaneous fuel efficiency based on the instantaneous operating conditions.

A method according to any one of claims 14 to 17, comprising using a fuel factor associated with the given fuel in determining the specific emission of the first exhaust gas component.

A method according to any one of claims 14 to 18, which method comprises determining the specific emission of the first exhaust gas component by dividing the detected concentration of the first exhaust gas component 1 the exhaust gas by the product of the determined difference 1 reference gas concentration between the intake air and the exhaust gas. and an adjustment factor.

The method of claim 19, wherein the adjusting factor comprises an instantaneous fuel efficiency of the engine determined by the control unit.

. DK 180561 B1

The method of claim 19 or 20, wherein the adjusting factor comprises a fuel factor associated with the given fuel.

A method according to any one of claims 14 to 21, which method comprises determining the specific emission of the first exhaust gas component by dividing the detected concentration of the first exhaust gas component 1 by the exhaust gas by the product of the determined difference 1 reference gas concentration between the intake air and the exhaust gas. , an instantaneous fuel efficiency of the engine determined by the control unit and a fuel factor associated with the given fuel.

A method according to any one of claims 14 to 23, wherein the first exhaust gas component is one of: CO, CO 2, HC, CH 4, NOx, SOx, NH 3, PM, PN or BC.