# Commission Delegated Regulation (EU) 2017/654 of 19 December 2016 supplementing Regulation (EU) 2016/1628 of the European Parliament and of the Council with regard to technical and general requirements relating to emission limits and type-approval for internal combustion engines for non-road mobile machinery, Division 2.1.6.3: Air flow and air to fuel ratio measurement method

Extent: E+W+S+N.I.

This involves exhaust gas mass calculation from the air flow and the air to fuel ratio. The instantaneous exhaust gas mass flow q mew, i [kg/s] shall be calculated by means of equation (7-17):
q m ew, i = q m aw, i × 1 + 1 A ∕ F st × λ i
(7-17)
with:
A ∕ F st = 138,0 × 1 + α 4 − ε 2 + γ 12,011 + 1,00794 × α + 15,9994 × ε + 14,0067 × δ + 32,065 × γ
(7-18)
λ i = 100 − c COd × 10 − 4 2 − c HCw × 10 − 4 + α 4 × 1 − 2 × c COd × 10 − 4 3,5 × c CO2d 1 + c COd × 10 − 4 3,5 × c CO2d − ε 2 − δ 2 × c CO2d + c COd × 10 − 4 4,764 × 1 + α 4 − ε 2 + γ × c CO2d + c COd × 10 − 4 + c HCw × 10 − 4
(7-19)
where:
qm aw, i wet intake air mass flow rate [kg/s]
A/F st stoichiometric air-to-fuel ratio [-]
λi instantaneous excess air ratio [-]
c COd concentration of CO in the raw exhaust gas on a dry basis [ppm]
c CO2d concentration of CO2 in the raw exhaust gas on a dry basis [per cent]
c HCw concentration of HC in the raw exhaust gas on a wet basis [ppm C1]
α molar hydrogen-to-carbon ratio [-]
δ molar nitrogen-to-carbon ratio [-]
ε molar oxygen-to-carbon ratio [-]
γ atomic sulphur-to-carbon ratio [-]

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Source: https://www.legislation.gov.uk/eur/2017/654/annex/VII/division/2/division/2.1/division/2.1.6/division/2.1.6.3 (the official version)
Page: https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-2/division-2.1/division-2.1.6/division-2.1.6.3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.