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Division 2.2.1 Mass of the gaseous emissions

United Kingdom

Original text. Later amendments are not shown.

The exhaust gas mass flow rate shall be measured with a constant volume sampling (CVS) system, which may use a positive displacement pump (PDP), a critical flow venturi (CFV) or a subsonic venturi (SSV).

For systems with constant mass flow (i.e. with heat exchanger), the mass of the pollutants m gas [g/test] shall be determined by means of equation (7-23):

m gas = k h · k · u gas · c gas · m ed (7-23)

where:

  • u gas is the ratio between density of exhaust gas component and density of air, as given in Table 7.2 or calculated by means of equation (7-34) [-]

  • c gas = mean background corrected concentration of the component on a wet basis [ppm] or [% vol] respectively

  • k h = NOx correction factor [-], only to be applied for the NOx emission calculation

  • k = 1 for c gasr,w, i in [ppm], k = 10 000 for c gasr,w, i in [% vol]

  • m ed = total diluted exhaust gas mass over the cycle [kg/test]

For systems with flow compensation (without heat exchanger), the mass of the pollutants m gas [g/test] shall be determined by calculation of the instantaneous mass emissions, by integration and by background correction by means of equation (7-24):

m gas = k h × k × ∑ i = 1 N m ed, i × c e × u gas − m ed × c d × 1 − 1 D × u gas (7-24)

Where:

c e

  • emission concentration in the diluted exhaust gas, on a wet basis [ppm] or [% vol]

    • c d

  • emission concentration in the dilution air, on a wet basis [ppm] or [% vol]

    • m ed, i

  • mass of the diluted exhaust gas during time interval i [kg]

    • m ed

  • total mass of diluted exhaust gas over the cycle [kg]

    • u gas

  • tabulated value from Table 7.2 [-]

    • D

  • dilution factor [see equation (7-28) of point 2.2.2.2] [-]

    • k h

  • NOx correction factor [-], only to be applied for the NOx emission calculation

    • k

  • 1 for c in [ppm], k = 10 000 for c in [% vol]

    • The concentrations c gas, c e and c d can be either values measured in a batch sample (bag, but not allowed for NOx and HC) or be averaged by integration from continuous measurements. Also m ed, i has to be averaged by integration over the test cycle.

    The following equations show how the needed quantities (c e, u gas and m ed) shall be calculated.