EP2195518A1

EP2195518A1 - Method and device for measuring the emissions of engines

Info

Publication number: EP2195518A1
Application number: EP08801818A
Authority: EP
Inventors: José Luis Miguez TABARES; Santiago Murillo Zapatero; Knut Hoyer
Original assignee: Testo SE and Co KGaA
Current assignee: Testo SE and Co KGaA
Priority date: 2007-09-07
Filing date: 2008-09-03
Publication date: 2010-06-16
Also published as: WO2009033597A8; KR20100065316A; WO2009033597A1; US20110016948A1; DE102007042748B4; US8527179B2; CN101828018A; DE102007042748A1

Abstract

The invention relates to a method and a device for determining specific emissions as an exhaust gas characteristic of an internal combustion engine. Said method is characterised in that the exhaust gas mass flow (3) is determined as the first operating parameter and the engine power output (2) as the second operating parameter, the nitrous oxide mass flow (3) and the engine power output (2) are derived from a respective measured value that deviates from the operating parameter and the exhaust gas characteristic is calculated as a quotient from the corrected exhaust gas mass flow (3) and the engine power output (2).

Description

Method and device for measuring emissions on engines

The invention relates to a method and a device for determining specific nitrogen oxide emissions of an internal combustion engine.

In the course of the ongoing climate debate, rules and regulations on climate protection were introduced for individual transport modes in many areas of passenger and freight transport, which set limit values for exhaust emissions. These limits are typically set to a certain value, e.g. km, kWh or similar based.

Such limits are increasingly being introduced in the field of rail vehicles, but also in shipping. For example, for the shipping sector, the Marpol Convention in Annex VI regulates the exhaust emission of a ship in relation to engine power, eg grams of pollutant per kilowatt of power and hour of operation. Currently, the emission of sulfur oxides (SO _x ) and nitrogen oxides (NO _x ) is regulated.

Other areas such as e.g. stationary motors in a wide variety of applications are similarly regulated, or comparable guidelines and limit values are in preparation.

The compliance with the limit values is usually checked during type approvals, prototype tests, etc. on corresponding test stands on the engines. These test benches are equipped with the complete measuring technology in the form of stationary measuring devices. because the test rig is designed to check the corresponding limit values, characteristic values, factors, etc. But as the verification of compliance with the limits in the field, ie in real operation of the engine, eg in a locomotive or on a ship, is increasingly necessary or required, reliable and mobile measuring systems are necessary to quickly and easily check the on-site Internal combustion engines to ensure compliance with the limits. Often, however, it is difficult or impossible to measure all operating parameters measured on the test bench to determine the emission values directly on site. For example, it is usually not possible to determine the currently delivered power or the current fuel consumption, without making complicated attachments or conversions on the machine itself.

The object of the invention is therefore to provide a method and a device for simple real-time determination of specific exhaust emission figures of an internal combustion engine under real conditions.

This object is achieved in that the emission mass flow, and specific exhaust gas component mass flow is determined as the first operating parameter and the engine power output as a second operating characteristic, the specific exhaust gas mass flow and the engine output from each at least derived or determined from the operating parameter different measure and the specific emission (exhaust gas ratio) is calculated as a quotient of the specific exhaust gas component mass flow and the engine power output. Under a deviating from a performance parameter size is understood in particular one of the operating characteristic physically different measure. Preferably, the exhaust gas component is NO _x . However, the procedure is as well in other exhaust gas components, such as SO _x , can be used.

The fact that the operating parameters are derived from measured quantities that are easier to measure, a method and measuring system can be used, which manages without complicated and complex structures. Such a method can thus be used at any location on different engines and allows the reliable control of the exhaust gas ratio and / or exhaust gas limits in real time.

It is expedient if the determination of the two operating parameters for different load conditions of the engine takes place. If necessary, a total sum is formed via the operating parameters.

It is particularly expedient if the operating parameters belonging to a specific load stage are multiplied by weighting factors adapted to the intended use of the engine before the summation, wherein the weighting factors can be stored, for example, in a table. In this case, it is possible, in particular, to take the individual load levels into consideration differently in the characteristic number. A marine diesel, e.g. runs mainly just under full load, so that the weighting factor here can be higher than at idle, whereas an automobile is operated mainly under part load or less and therefore the pollutant emissions in this load range can be more weighted or must.

The specific exhaust ratio is preferably defined as a corrected specific exhaust gas component mass flow per kilowatt engine performance and ^¬ per hour and simply referred to as specific emission measure.

In a first embodiment of the invention, the engine power determined from the current torque and the engine speed, wherein the torque is determined for example by a strain gauge on the shaft.

A second embodiment of the emission index determination according to the invention provides for calculating the engine power from the fuel mass flow and the specific fuel consumption of the engine, the specific fuel consumption being a value indicated by the manufacturer, e.g. in tabular or diagrammatic form, at which power the engine has which fuel consumption. By determining the instantaneous fuel consumption, the power may e.g. simply read in the table or interpolated based on the table values.

Sometimes, however, it may be difficult or impossible to mount a fuel mass flow sensor on or in the engine supply lines, so it may be useful to calculate the fuel mass flow rate from the mass flow of exhaust gas and the stoichiometric air requirement. By simply considering the reaction equation, it is possible to calculate back from the exhaust gas quantity to the fuel mass flow.

This results in the stoichiometric air requirement from the chemical composition of the fuel, in particular the mass fraction of carbon, hydrogen and possibly sulfur.

The exhaust gas mass flow can also be difficult to measure, and therefore can be calculated back on the Ve ^{'rbrennungsluft-stream} and the excess air factor of the fuel mass flow. The excess air factor takes into account that not all air (oxygen) is necessary for combustion and therefore can not be included in the fuel bill. The excess air factor is determined from the composition of the exhaust gas, in particular the volume concentration of carbon dioxide CO ₂ and possibly CO and possibly the hydrocarbons HC. Here, too, the measurement effort can be reduced by calculating the carbon dioxide content from the oxygen volume concentration.

The combustion air mass flow can be measured with an impeller anemometer or similar measuring device. However, if there is no access to the air intake of the engine, it can also be calculated.

For this purpose, the speed, the displacement and the number of cylinders of the engine, the charge air pressure and the charge air temperature after the intercooler, ie before entering the engine, and the ambient temperature and air pressure and relative humidity determined and calculated from the combustion air mass flow.

When using an engine without intercooler or turbocharger, the corresponding measured values are used analogously, in which case the charge air is given by the intake air and intake air temperature and normal ambient pressure are used instead of charge air temperature and charge air pressure.

Thus, to determine the power, several options are available depending on which type of sensors are available and which points are accessible on the motor. In the worst case, a simple oxygen measurement in the exhaust gas is sufficient, for which a small opening in the exhaust system is sufficient to introduce a thin probe, as well as the determination of charge air pressure and temperature together with the environmental parameters and the engine speed. All other data can then be calculated from these measured values, the fuel Parameters and the known motor data are calculated.

Similarly, it is possible to proceed in the determination of the exhaust-gas component mass flow, in particular of the nitrogen oxide mass flow. Again, the direct determination of the mass flow is sometimes difficult, since a volume flow measurement required for this purpose in larger exhaust gas amines, such as e.g. on ships, is problematic feasible.

Therefore, it is necessary to use a gas sensor to determine the volume concentration, eg of nitrogen oxides, and to calculate the mass flow therefrom. Commercially available NO _x sensors partially determine the concentration in dry exhaust gas, which is why the measurement result is then used for further use with a dry-humid correction factor.

With appropriate measuring methods and sensors, it is generally also possible to measure the O ₂ , NO _x , SO _x and / or HC concentration directly on the moist exhaust gas. An offset to the wet mass flow is then no longer necessary.

This dry-humidification correction factor is determined by the volume concentration of CO and CO ₂ as well as by the ambient conditions such as absolute air pressure, relative humidity and temperature.

The thus formed NO _x concentration in moist exhaust gas is charged together with the moist exhaust gas mass flow to a NO _x - mass flow, the exhaust gas mass flow was already measured or determined during the determination of power and therefore already present as a value or by the same method can be determined.

The present value of the NO _x mass flow will, depending on the application and specifications, with a special NO _x evaluation factor, in order to obtain a value comparable, for example, with test bench values of the engine. This weighting factor is determined by the air temperature and the air pressure of the charge air cooler and the ambient conditions such as absolute air pressure, relative humidity and temperature.

This makes this method universally applicable and easy to carry out, especially in the field. In particular, on a vehicle in operation, such as a ship, it is thereby possible to carry out the measurement of the exhaust gas parameters in the exhaust gas with a simple probe close to the engine, without complex exhaust gas mass flow measurements must be performed in the fireplace. Preferably, the probe has a flange or the like with which it can be fastened to the chimney or the exhaust gas outlet and protrudes into the engine exhaust gases in the fastened position for removing an exhaust gas sample.

The removal of the exhaust gas sample is preferably carried out via a heated or unheated hose, wherein in an unheated hose precautions, for example, as described in DE 196 31 002 C2, taken to prevent a transition of the exhaust gas exhaust gas component.

In addition, the real-time determination of the exhaust gas parameters and KPI allows an optimization of the combustion process in the engine, as can be observed directly and under real-life conditions, as changes in the input parameters and engine settings affect the exhaust gas concentration, which ultimately affects the Have fuel consumption.

According to one embodiment of the invention, provision may be made for the moist exhaust gas to be blown before contact with the sensors. is cooled like. This can be done, for example, in a cold trap or in a gas cooler, which is upstream of the sensors in the flow of the exhaust gas withdrawn. The advantage here is that the investigated exhaust gas components are not bound in the moist exhaust gas.

For easy removal of the exhaust gas sample for the described method can be provided in a device for carrying out the method that the exhaust gas removal probe is present, which has a flange for attachment to the exhaust gas outlet of the engine. This probe is thus fast and non-destructive over a longer period and / or without human effort in the exhaust stream, for example, in the chimney of a ship, fastened.

The method is described below using the example of the determination of the weighted nitrogen oxide index GAS _{NOx in} accordance with the Marpol 73/78 Annex VI, hereinafter simply Marpol, with reference to the drawings.

Show it:

1 is a schematic arrangement for determining the exhaust gas ratio,

2 is a flow chart for determining the weighted nitrogen oxide code,

3 is a flowchart of a first method of engine output determination;

4 shows a flow chart of a first method for the corrected nitrogen oxide mass flow determination,

Fig. 5 is a flowchart of a second method for Engine power takeoff and

6 shows a flowchart of a second method for the corrected nitrogen oxide mass flow determination.

In Fig. 1, a device for determining the nitrogen oxide index is shown, as it can be used for example for measuring on board a ship.

A central component of the system is a measuring device 30, which is connected via a hose to an exhaust gas probe 31 and is suitable for measuring the exhaust gas volume concentrations of the exhaust gas components O ₂ , CO, CO ₂ , NO _x , SO ₂ and HC and other sizes. For this purpose, the measuring device has a pump, which sucks in exhaust gas via the probe tip and pumps it through a sensor path in the measuring device. The measuring device has a modular structure, so that further sensors can simply be plugged into the measuring section if additional measured values, such as SO _x , are required for other or future applications.

In addition, it contains entprechende facilities for the preparation of the sample gas, such. Filter, a module for gas drying, for example, with a gas cooler, etc. The exhaust gas probe 31 and its hose can occasionally filters (eg also on the probe tip) and are designed so that binding of the gas components to be measured on the surfaces, etc. prevented becomes.

In a further embodiment, a combination of probe 30 and the measuring device 31 used as an analyzer is realized as a unit, ie without intermediate hose, which is attached directly to the exhaust duct. The exhaust gas measured values 38 are forwarded to a central measured value acquisition device 32.

Furthermore, the device has measuring devices for ambient 35 and motor parameters 36, which are transmitted by radio or by cable to the central measured value detection device 32. These may e.g. also be read in via an interface to the engine management.

The measurement data in the central measured value acquisition device 32 can be called up by at least one computer 33, which has a suitable program for performing the characteristic number calculation. To calculate the program of the engine and fuel ^¬ manufacturers are occasionally further table data 37 are available. As a result of the calculation, a corresponding measurement protocol 34 can be issued directly. It is also possible to permanently monitor the measurement data with the computer 33 so that a current value of the exhaust gas ratio can be calculated and displayed at any time. It is also conceivable that the display is located directly on the control room or on the command bridge of a ship, so that the flight engineer or the captain can monitor the exhaust emission of the engine at any time. As a result, malfunctions in the engine can be detected at an early stage and greater damage can be avoided.

FIG. 2 shows a flow chart of the method for determining the weighted nitrogen oxide index GAS _NOx 1, which represents the nitrogen oxide mass output in the exhaust gas per kilowatt of power and operating hour. Consequently, the method comprises the determination of the power 2 and of the nitrogen oxide mass flow 3. The power 2 and the nitrogen oxide mass flow 3 are determined at different load stages of the engine and the values are weighted with a weighting factor of 4. The nitrogen oxide code is calculated according to the formula given in step 5:

The weighting factors 4 take into account that a motor, depending on the application, is mainly operated in a specific load range. For ships, this also depends on the type of drive. For example, the diesel engine of a diesel-electric drive will always drive at full speed so that the voltage generated has the correct frequency. Therefore, in a diesel-electric drive the pollutant emissions at low speed is negligible, since the engine is usually not operated in this area. On direct-driven ships, however, the speed is slowed down at low speeds, which is why the pollutant emissions here contributes to a part of the total output.

For example, in one application, the emission can be measured with the described method at 10%, 50% and 100% of the full load of the internal combustion engine and used in the formula.

In another application, for example, the mentioned diesel-electric drives, which must follow other regulations, however, the emission is measured, for example, only at 100% of the full load of the internal combustion engine, and the summation in the above formula is omitted.

Usual are applications in which the emission is measured at between three and five load points, but it can be deviated from these figures given appropriate guidelines or requirements.

The calculation described in step B is also possible transferred other specific ratios and would also be suitable, for example, to calculate the usual in motor vehicles code C0 ₂ output per kilometer. Again, a weighting of different performance levels could be useful.

Power 2 and nitrogen oxide mass flow 3 can be determined by various methods. A first method for power determination is shown in FIG.

To determine the power 2, a torque measurement 6 is provided on the shaft of the motor. For this purpose, for example, a strain gauge is attached to the shaft and converted the measured voltage into a torque. Together with the speed 7 of the motor, the power 2 can be calculated easily according to the formula P ₁ = T ^}% 2π'n, in particular if the shaft parameters are used to convert the measured bridge voltage into the torque.

In the event that the motor drives an electric generator, a determination of the power 2 is alternatively feasible by determining the electric power output of the generator, in particular taking into account the generator efficiency and / or the gear ratio of a arranged between the engine and generator in the drive train transmission ,

However, if a measurement of the torque 6 is not possible because, for example, no access to the shaft and no strain gauges can be attached, a method for determining the power is described in Fig. 4, which does not require the measurement of torque and only makes simple demands on the measurement technique ,

In a first step, the speed 7, the number the cylinder 8, the displacement 9, the charge air pressure 10 and the charge air temperature 11 after the intercooler, as well as the ambient conditions 12 such as absolute air pressure, relative humidity and temperature, the intake air mass flow 13 calculated.

In a second step, which must take place at the same time and under the same conditions, the volume concentration of the carbon dioxide 14 and optionally carbon oxide 15 and possibly of hydrocarbons 16 is measured in the dry exhaust gas. For this purpose, for example, a probe is introduced into the exhaust passage of the engine, through which the exhaust gas is sucked into a measuring device and is passed there via various sensors.

Alternatively, the CO ₂ volume concentration CO ₂ can also be measured from the oxygen concentration O ₂ , measured (in%) and the maximum CO ₂ amount CO ₂ , max that can be produced from the fuel, according to the formula

be calculated.

From the three values, an excess air factor 17 can be calculated, which indicates how much of the intake air was not needed for combustion.

From the intake air mass flow 13 and the excess air factor 17, a combustion air or exhaust gas mass flow 18 is calculated.

In parallel, in a further step, the stoichiometric air requirement 19 is calculated from the specific composition of the fuel 20, the composition being a value given by the fuel manufacturer. The calcula- Therefore, it can also be done in advance and the result can be cached. The interesting components are the carbon, sulfur and Wasserstoffantei-1 in the fuel.

By considering the reaction equation and the molar mass balance, the fuel mass flow 21 can be determined on the basis of the combustion air mass flow 18 and the stoichiometric air requirement 19.

From the fuel mass flow 21, the power 2 of the engine is calculated or interpolated in a final step with the present in tabular form engine manufacturer information on the specific fuel consumption 22.

Figure 5 shows a first method for determining the nitrogen oxide mass flow GNOX, which is required in addition to the power for calculating the nitrogen oxide index. An essential component of the method is the determination of the nitrogen oxide volume concentration 23 in the dry exhaust gas. For this purpose, a sensor in the exhaust stream is necessary, which is advantageously arranged in the same meter, which is also provided for measuring carbon dioxide 14, among other things. In the simplest case, it is sufficient to install a corresponding sensor module in the gas path of the meter, so that the installation cost is very low.

The NO _x concentration must be converted to the volume concentration in moist exhaust gas 25 for further processing with a dry-humidification correction factor 24, which is calculated from the environmental conditions 12 and the carbon oxide concentrations 14, 15 already determined in the performance determination.

In a parallel step, the fuel mass flow 26 is measured, including, for example, an impeller in the Fuel supply is installed or non-invasively measured via clamp-on sensors. The moist exhaust gas mass flow 27 is calculated from the fuel mass flow 26 and the excess air factor 17 already calculated in the power determination and the stoichiometric air requirement 19.

From the moist exhaust gas mass flow 27 and the NO _x concentration 25, the humid NO _x mass flow 28 in the exhaust gas is calculated in a next step.

However, since the nitrogen oxide index must not be affected by environmental influences such as humidity, must in a further step, a NO _x -Feuchtekorrekturfaktor from the already determined in the performance determination ambient conditions 12 and the charge air pressure 10 and the charge air temperature 11 after the intercooler, ie before entry in the engine, to be calculated.

From the moist NO _x mass flow 28 and the NO _x humidity correction factor 29, the NO _x mass flow 3, which is needed to determine the nitrogen oxide characteristic number, is calculated in a last step.

FIG. 6 shows a further method for determining the NO _x mass flow 3, which differs from the method in FIG. 5 only in the determination of the fuel mass flow.

As the fuel mass flow 21, the calculated value from the power determination according to FIG. 4 is adopted here. As a result, it is possible to dispense with a measurement of the fuel mass flow and to simplify the process considerably, since in most cases there is no possibility of subsequently or temporarily attaching a mass flow sensor to a motor. The invention relates to a method and a device for determining the specific emissions as an exhaust gas ratio of an internal combustion engine. The method is characterized in that the emission mass flow, also referred to as the exhaust gas mass flow, in particular the exhaust gas component mass flow 3, wherein the exhaust gas component is preferably NO _x , as a first operating characteristic and the engine output 2 as a second operation Characteristic are determined that the exhaust gas component mass flow 3 and the engine Abydbeleistung 2 are each derived from at least one of the operating characteristic deviating parameter and the exhaust gas ratio as a quotient of the corrected exhaust gas component mass flow 3 and the engine output power. 2 is calculated.

Claims

claims

1. A method for determining specific emissions of an internal combustion engine, characterized in that the emission mass flow (3) as a first operating parameter and the engine output power (2) are determined as a second operating characteristic that the emission mass flow (3) and the engine output power (2) are derived from at least one measurement variable deviating from the operating parameter, and a specific emission is calculated as the quotient of the corrected emission mass flow (3) and the engine output power (2).

2. The method according to claim 1, characterized in that in the determination of the emission mass flow of the exhaust gas component mass flow (3) of a component in the exhaust gas of the internal combustion engine is determined.

3. The method according to claim 2, characterized in that the exhaust gas component is NO _x .

4. The method according to any one of claims 1 to 3, characterized in that the determination of the first and second operating characteristic for different load conditions of the engine is repeated and the specific emission (1) is formed as a quotient of the sums of the operating characteristics.

5. The method according to claim 4, characterized in that the operating characteristics of the different load conditions when summing each with a weighting factor

(4) are multiplied and the weighting factors (4) are adapted to the intended use of the internal combustion engine.

6. The method according to claim 5, characterized in that the weighting factors (4) are stored in a table.

7. The method according to any one of claims 1 to 6, characterized in that the method step for determining the engine power output (2) comprises the following additional steps:

Determination of the current torque (6) of the engine,

• Determination of the current speed (7) of the motor.

8. The method according to any one of claims 1 to 6, characterized in that the method step for determining the engine output power (2) comprises the following additional step:

• Determining the electrical output of a motor driven generator.

9. The method according to any one of claims 1 to 8, characterized in that the method step determining the engine output power (2) comprises the following additional method steps:

Determination of the fuel mass flow (21, 26),

• Determination and / or input of specific fuel consumption (22).

10. The method according to any one of claims 1 to 9, characterized in that the method step determining the exhaust gas component mass flow (3) in the exhaust gas comprises the following additional method step:

• Determination of the wet exhaust gas component mass flow in the exhaust gas (28).

11. The method according to any one of claims 1 to 10, characterized in that the step of determining the exhaust-gas component mass flow (3) in the exhaust gas comprises the following additional method steps:

• Determination of a moisture correction factor

(29).

12. The method according to claim 10 or 11, characterized in that the step of determining the moisture correction factor (29) comprises the following additional method steps:

Determination of the charge air pressure before entry into the engine (10),

Determination of the charge air temperature before entry into the engine (11),

Determination of the environmental conditions (12) characterized by at least absolute atmospheric pressure (P _B ), temperature (T ₃ ) and relative humidity (Ra ⁾ -

13. The method according to any one of claims 10 to 12, characterized in that the method step determining the wet exhaust gas component mass flow (28) in the exhaust gas comprises the following additional method steps:

• Determination of the wet emission mass flow

(27)

• Determination of the exhaust gas component concentration (25) in the moist exhaust gas.

14. The method according to any one of claims 10 to 13, characterized in that the method step determining the exhaust gas component concentration (25) in the moist exhaust gas comprises the following additional method steps: Determination of the exhaust gas component concentration in the dry exhaust gas (23),

• Determination of the dry-humidification correction factor

(24).

15. The method according to claim 14, characterized in that the step of determining the dry-wet correction factor (24) comprises the following additional method steps:

Determination of the CO ₂ concentration in the dry exhaust gas (14),

• Determining the ambient conditions (12), in particular at least the air pressure (p _B ), the temperature

(T _a ) and the relative humidity (R _a ).

16. The method according to claim 14 or 15, characterized in that the method step determining the dry-wet correction factor (24) comprises the following additional method step:

• Determination of CO concentration in dry exhaust gas (15).

17. The method according to any one of claims 13 to 16, characterized in that the step of determining the moist exhaust gas mass flow (27) comprises the following additional method steps:

Determination of the fuel mass flow (26),

Determination of the excess air factor (17),

• Determination of the stoichiometric air requirement (19).

18. The method according to any one of claims 9 to 17, characterized in that the method step determining the fuel mass flow (21, 26) comprises the following additional method steps: Determination of the stoichiometric air requirement (19),

• Determination of the dry air mass flow in the internal combustion engine (18).

19. The method according to claim 17 or 18, characterized in that the method step determining the stoichiometric air requirement (19) comprises the following additional method step:

• Determination or input of the fuel composition (20), in particular the mass fractions of hydrogen, carbon and optionally sulfur (ALF, BET and GAM).

20. The method according to claim 18 or 19, characterized in that the method step determining the dry air mass flow (18) in the internal combustion engine comprises the following additional method steps:

Determination of the intake air mass flow (13),

• determination of excess air factor (17).

21. The method according to claim 20, characterized in that the step of determining the intake air mass flow (13) comprises the following additional method steps:

Determination of the engine speed (7),

Determining the number of cylinders (8) of the engine,

Determination of the displacement (9),

Determination of the charge air pressure before entry into the engine (10),

Determination of the charge air temperature before entry into the engine (11),

• Determination of the ambient conditions (12), in particular absolute air pressure (p _B ), temperature (T ₃ ) and relative humidity (R _a ).

22. The method according to any one of claims 17 to 21, characterized in that the method step determining the excess air factor (17) comprises at least the following additional method step:

Determination of the CO ₂ volumene concentration (14) in the dry exhaust gas.

23. The method according to any one of claims 17 to 22, characterized in that the method step determining the excess air factor (17) comprises at least the following additional method step:

• Determination of CO volume concentration (15) in dry exhaust gas.

24. The method according to any one of claims 17 to 23, characterized in that the method step determining the excess air factor (17) comprises at least the following additional method step:

• Determination of the hydrocarbon concentration (16) in the dry exhaust gas.

25. The method according to any one of claims 15 to 24, characterized in that the method step determining the CO ₂ volume concentration (14) comprises the following method step:

Determination of the oxygen concentration O ₂ in the exhaust gas, in particular for calculating the CO ₂ volume concentration from the maximum CO ₂ quantity CO ₂ , _ma χ of the fuel that can be generated.

26. The method according to any one of claims 1 to 25, characterized in that the moist exhaust gas is cooled suddenly before contact with the sensors.

27. A device for determining specific emissions of an internal combustion engine, in particular for determining the specific emission of the internal combustion engine as the exhaust gas ratio, characterized in that the device comprises means (30, 31, 35, 36) for detecting a first and second operating characteristic, a measured value acquisition unit (32) and a computing unit (33) which is suitable for calculating from the operating parameters the specific emission, in particular an exhaust gas characteristic number (1).

28. The device according to claim 27, characterized in that the device comprises a sensor for determining the oxygen volume concentration in the exhaust gas of the engine.

29. The device according to claim 27 or 28, characterized in that the device comprises a sensor for determining the Cθ ₂ volumenkonzentration in the exhaust gas of the engine.

30. Device according to one of claims 27 to 29, characterized in that the device comprises a sensor for determining the NO _x volumenkonzentration (23) in the exhaust gas of the engine.

31. Device according to one of claims 27 to 30, characterized in that the device comprises a sensor for determining the CO volume concentration in the exhaust gas of the engine.

32. Device according to one of claims 27 to 31, characterized in that the device comprises a sensor for determining the hydrocarbon concentration (16) in Exhaust gas of the engine has.

33. Device according to one of claims 27 to 32, characterized in that the device comprises a sensor for determining the S0 ₂ -volumenkonzentration in the exhaust gas of the engine.

34. Device according to one of claims 27 to 33, characterized in that the device comprises a sensor for determining or means for inputting the rotational speed (7) of the shaft.

35. Device according to one of claims 27 to 34, characterized in that the device comprises sensors for determining or means for inputting the charge air temperature (11) and the charge air pressure (10), in particular on the intercooler.

36. Device according to one of claims 27 to 35, characterized in that the device comprises sensors for determining or means for inputting the ambient temperature (T _a ), the absolute air pressure (p _B ) and the relative humidity (R _a ).

37. Device according to one of claims 27 to 36, characterized in that the exhaust gas removal, a probe is provided which has a flange for attachment to the exhaust gas outlet of the internal combustion engine.

38. Device according to one of claims 27 to 37, characterized in that the sensors for transmitting the measurement data has a radio link to the Meßwerterfassungs- unit (32).

39. Device according to one of claims 27 to 38, characterized in that an interface to the engine management ^¬ and / or process control system of the internal combustion engine is formed.

40. Device according to one of claims 27 to 39, characterized in that means for determining, in particular at least one sensor, and / or means for inputting fuel parameters and / or the specific fuel consumption of the Verbennungsmotors are formed.

41. Device according to one of claims 27 to 40, characterized in that the sensors in a measuring device

(30) are arranged and that for the removal of the exhaust gas, an exhaust gas probe (31) is provided, in particular wherein the measuring device (30) and the exhaust gas probe (31) form a unit.

42. Device according to one of claims 27 to 41, characterized in that for the removal of the exhaust gas sample, a heated or unheated hose is provided.