5.12.3 NO_x correction for humidity and temperature

  5.12.3.1 As the NO_x emission depends on ambient air conditions, the NO_x concentration shall be corrected for ambient air temperature and humidity by multiplying with the factors given in formulae (13) and (14).

  5.12.3.2 The standard value of 10.71 g/kg at the standard reference temperature of 25°C shall be used for all calculations involving humidity correction throughout this Code. Other reference values for humidity instead of 10.71 g/kg must not be used.

  5.12.3.3 Other correction formulae may be used if they can be justified or validated upon agreement of the parties involved and if approved by the Administration.

  5.12.3.4 Water or steam injected into the air charger (air humidification) is considered an emission control device and shall therefore not be taken into account for humidity correction. Water that condenses in the charge cooler may change the humidity of the charge air and shall therefore be taken into account for humidity correction.

  5.12.3.5 Diesel engines in general

For diesel engines in general, the following formula for calculating K_HDIES shall be used:

  5.12.3.6 Diesel engines with intermediate air coolers

For diesel engines with intermediate air coolers, the following alternative formula (14) shall be used:

• .1 To take the humidity in the charge air into account, the following consideration is added.

  H sc

  =

  humidity of the charging air, g water per kg dry air in which:

  • H _sc = 6.220·P_sc·100/(P_C - P_sc)
  where:

  P sc	=	saturation vapour pressure of the charging air, kPa
  P C	=	charging air pressure, kPa

• .2 If H _a ≥ H _sc, then H _sc shall be used in place of H _a in formula (14). In this case, G _EXHW in 5.5.2.3 shall be corrected as follows:

  G_{EXHW Corrected} = G_{EXHW(5.5.2.3)} · (1-(H_a - H_sc)/1000)

• .3 If H _a < H _sc, then H _a in formula (14) shall be used as it is.