# 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 2.1.4: NOx correction for humidity and temperature

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

As the NOx emission depends on ambient air conditions, the NOx concentration shall be corrected for ambient air temperature and humidity with the factors kh,D or kh,G [-] given in equations (7-9) and (7-10). These factors are valid for a humidity range between 0 and 25 g H2O/kg dry air.
(a) for compression-ignition engines
k h,D = 15,698 × H a 1000 + 0,832
(7-9)
(b) for spark ignition engines
kh.G = 0,6272 + 44,030 × 10– 3 × Ha – 0,862 × 10– 3 × Ha 2
(7-10)
where:
H a humidity of the intake air [g H2O/kg dry air]

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Source: https://www.legislation.gov.uk/eur/2017/654/annex/VII/division/2/division/2.1/division/2.1.4 (the official version)
Page: https://openlegislation.uk/eu-regulation-2017-654/annex-VII/division-2/division-2.1/division-2.1.4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.