3.7 Program for the calculation of the exhaust mass flow
3.7.1 The results of both stoichiometric calculation for carbon and oxygen calculations give the total exhaust composition and the exhaust mass flow including the water content.
3.7.2 The formulae in the program are mainly based on wet exhaust.
3.7.3 If dry concentrations(O2 and CO2) are measured, the dry to wet correction factor KWEXH (=Kwx)shall be used.
3.7.4 If the mass balance formula is used without the program, the following dry to wet correction factor shall be used:
3.7.6 The formula in another prepared form:
3.7.7 The general formula for dry/wet correction KWEXH=Kwx different versions are possible.
3.7.8 Formulae(2-44) and (2-44a) and also formula (12) from 5.12.2.3 of this Code are not absolutely exact, because the correction for the combustion water and for the air intake water are not additive.
3.7.9 The exact formula is:
where:
RhoEXH DAC=exhaust density with combustio by dry air(kg/stdm3)
RhoH2O=water vapour density(kg/stdm3)MWH2O/MVH2O
3.7.10 A comparison of formula (12) from 5.12.3 of this Code with formula (2-45)) shows very small differences of the factor Kwx as shown in the following examples:
3.7.11 The formula given as (2-45) is not very practical because in many cases RhoEXH DAC is not known and because the use of the fuel specific factor Ffh is excluded. Therefore the more practical formulae (9), (10), (11), (12), &(13)from 5.12.2.1 to 5.12.3.5 of this Code shall be used; the resulting error of < 0.2%(in most cases) may be neglected.
3.8 Calculation of the fuel specific factors FFD and FFW for exhaust flow calculation
3.8.1 By means of the following formulae:
VEXHW・VH20・VCO2・VO2・VN2・VSO2(2-48)
VEXHD・VCO2・VO2・VN2・VSO2(2-49)
and according to the formulae (2-34), (2-35), (2-37), (2-38), and (2-39), the factors may be given by formula (2-50) and (2-52), respectively:
