Division 2.2.2.2 Dilution factor

The dilution factor D [-] (which is necessary for the background correction and the k _w2 calculation) shall be calculated by means of equation (7-28):

where:

F _S

stoichiometric factor [-]

c _CO2,e

concentration of CO₂ in the diluted exhaust gas on a wet basis [per cent vol]

c _HC,e

concentration of HC in the diluted exhaust gas on a wet basis [ppm C1]

c _CO,e

concentration of CO in the diluted exhaust gas on a wet basis [ppm]

The stoichiometric factor shall be calculated by means of equation (7-29):

Where:

α

molar hydrogen to carbon ratio in the fuel [-]

Alternatively, if the fuel composition is not known, the following stoichiometric factors may be used:

• F _S (diesel) = 13,4

• F_S (LPG) = 11,6

• F_S (NG) = 9,5

• F_S (E10) = 13,3

• F_S (E85) = 11,5

If a direct measurement is made of the exhaust gas flow, the dilution factor D [-] may be calculated by means of equation (7-30):

Where:

• q_{V CVS} is the volumetric flow rate of diluted exhaust gas [m³/s]

• q_{V ew} = volumetric flow rate of raw exhaust gas [m³/s]