Dry / Wet correction The measured concentration must be converted to a wet basis according to the following formulae, if not already measured on a wet basis. conc(wet) = KW * conc(dry) For the raw exhaust gas: ⎜ K = ⎛⎜ − F ∗ GFUEL ⎞⎟ − K ⎟ W2 and W,r 1 FH ⎝ GAIRD ⎠ F = 1.969 FH ⎛ G ⎞ ⎜1 + ⎝ FUEL ⎟ G AIRW ⎠ For the diluted exhaust gas: K = ⎛ − HTCRAT ∗ CO2%(wet)⎞ − K W,e,1 ⎜1 ⎝ 200 ⎟ W1 ⎠ or ⎛ ⎞ ⎜ (1 − K ⎟ KW,e,2 = ⎜ W1) ⎟ ⎜1 + HTCRAT ∗ CO2%(dry)⎟ ⎝ 200 ⎟⎠ For the dilution air: For the intake air: (if different from the dilution air) KW,d = 1- KW1 KW,a = 1- XX0 XX0 = 1.608 ∗ Hd 1000 + (1.608 ∗ Hd ) KW2 = 1.608 ∗ Ha 1000 + (1.608 ∗ Ha) d a H = 6.220 ∗ Rd ∗ pd H = 6.220 ∗ Ra ∗ pa pB − pd ∗ Rd ∗ 10−2 pB − pa ∗ Ra ∗ 10−2 where: Ha, Hd = g water per kg dry air Rd, Ra = relative humidity of the dilution/intake air, % pd, pa = saturation vapour pressure of the dilution/intake air, kPa pB = total barometric pressure, kPa
