The final results for the test report shall he determined by following the steps in 5.12.1 to 5.12.4.
5.12.1 Determination of the exhaust gas flow
The exhaust gas flow rate (G EXHW, V EXHW, or V EXHD) shall be determined for each mode according to 5.5.1 to 5.5.3.
5.12.2 Dry/wet correction
When applying G EXHW, V EXHW, G TOTW, or V TOTW the measured concentration, if not already measured on a wet basis, shall be converted to a wet basis according to the following formulae.
conc(wet) = K W･conc (dry) (7)
5.121.1 For the raw exhaust gas:
(8)
(9)
(10)
with:
Ha3, Hd =g water per kg dry air
Ra = relative humidity of the intake air, %
Pa = saturation vapour pressure of the intake air, kPa
PB = total barometric pressure, kPa
Note: Formulae using F FH are simplified versions of those quoted in section 3.7 of appendix 7 of this Code (formulae (2-44) & (2-45)) which when applied give comparable results to those expected from the full formulae.
5.12.2.2 Alternatively:
(11)
MEPC 39/6/1
ANNEX
Page 27
5.12.2.3 For the intake air:
K W1a = 1 - K W2
(12)
5.12.2.4 Formula (8) shall be accepted as the definition of the fuel specific factor F FH. Defined this way, F FH is a value for the water content of the exhaust in relationship to the fuel to air ratio.
5.12.2.5 Typical values for F FH may be found in table 1 of appendix 7 of this Code. Table 1 of appendix 7 of this Code contains a list of For values for different fuels. For dries not only depend on the fuel specifications, but also, to a lesser degree, on the fuel so air ratio of the engine.
5.12.2.6 Section 3.9 of appendix 7 of this Code contains formulae for calculating F FH from the hydrogen content of the fuel and the fusel to air ratio.
5.12.2.7 Formula (8) considers the water from the combustion and from the intake air to be independent from each other and to be additive. Formula (2-45) in section 3.7 of appendix 7 of this Code shows that the two water terms are suit additive. Formula (2-45) is the correct version but it is very complicated and, therefore, the more practical formulae (8) & (11) shall be used.
5.12.3 NOx correction for humidity and temperature
5.12.3.1 As the NOx emission depends on ambient air conditions, the NOx concentration shall be corrected for ambient air temperature and humidity 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.
5.1 2.3.3 Other corrections formulae may he used if they can be justified or validated upon agreement of the panics 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 condensates 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:
