Division 3.2.1.2 Calculation of the NOx humidity correction factor

In order to correct the influence of humidity on the results of oxides of nitrogen, the following calculations apply:

KH = \frac{1}{1 - 0,0329 \times (H - 10,71)}

where:

H = \frac{6,211 \times R_{a} \times P_{d}}{P_{B} - P_{d} \times R_{a} \times 10^{- 2}}

and:

is the specific humidity, grams of water vapour per kilogram dry air;

R_a

is the relative humidity of the ambient air, per cent;

P_d

is the saturation vapour pressure at ambient temperature, kPa;

P_B

is the atmospheric pressure in the room, kPa.

The KH factor shall be calculated for each phase of the test cycle.

The ambient temperature and relative humidity shall be defined as the arithmetic average of the continuously measured values during each phase.