Division 2.1.4 NOx correction for humidity and temperature

As the NO_x emission depends on ambient air conditions, the NO_x concentration shall be corrected for ambient air temperature and humidity with the factors k_h,D or k_h,G [-] given in equations (7-9) and (7-10). These factors are valid for a humidity range between 0 and 25 g H₂O/kg dry air.

1. (a)

   for compression-ignition engines

   $k_{\mathrm{h,D}}=\frac{\mathrm{15,698}\times H_a}{1000}+\mathrm{0,832}$

   (7-9)

2. (b)

   for spark ignition engines

   kh.G = 0,6272 + 44,030 × 10– 3 × Ha – 0,862 × 10– 3 × Ha 2

   (7-10)

where:

H _a

humidity of the intake air [g H₂O/kg dry air]