Directive 2005/55/EC of the European Parliament and of the Council (repealed)Show full title

4. CALCULATION OF THE GASEOUS EMISSIONS

4.1. Data evaluation

For the evaluation of the gaseous emissions, the chart reading of the last 30 seconds of each mode shall be averaged, and the average concentrations (conc) of HC, CO and NO_x during each mode shall be determined from the average chart readings and the corresponding calibration data. A different type of recording can be used if it ensures an equivalent data acquisition.

For the NO_x check within the control area, the above requirements apply for NO_x, only.

The exhaust gas flow G_EXHW or the diluted exhaust gas flow G_TOTW, if used optionally, shall be determined in accordance with Annex III, Appendix 4, Section 2.3.

4.2. Dry/wet correction

The measured concentration shall be converted to a wet basis according to the following formulae, if not already measured on a wet basis.

For the raw exhaust gas:

and,

For the diluted exhaust gas:

or,

For the dilution air	For the intake air (if different from the dilution air)

where:

H_a, H_d

=

g water per kg dry air

R_d, R_a

=

relative humidity of the dilution/intake air, %

p_d, p_a

=

saturation vapour pressure of the dilution/intake air, kPa

p_B

=

total barometric pressure, kPa

4.3. NO_x correction for humidity and temperature

As the NO_x emission depends on ambient air conditions, the NO_x concentration shall be corrected for ambient air temperature and humidity with the factors given in the following formulae:

with:

A

=

0,309 G_FUEL/G_AIRD - 0,0266

B

=

- 0,209 G_FUEL/G_AIRD + 0,00954

T_a

=

temperature of the air, K

H_a

=

humidity of the intake air, g water per kg dry air

H_a

=

in which

R_a

=

relative humidity of the intake air, %

p_a

=

saturation vapour pressure of the intake air, kPa

p_B

=

total barometric pressure, kPa

4.4. Calculation of the emission mass flow rates

The emission mass flow rates (g/h) for each mode shall be calculated as follows, assuming the exhaust gas density to be 1,293 kg/m³ at 273 K (0 C) and 101,3 kPa:

• 

  [(1)]

• 

  [(2)]

• 

  [(3)]

where NO_{x conc}, CO_conc, HC_conc (1) are the average concentrations (ppm) in the raw exhaust gas, as determined in Section 4.1.

If, optionally, the gaseous emissions are determined with a full flow dilution system, the following formulae shall be applied:

• 

  [(1)]

• 

  [(2)]

• 

  [(3)]

where NO_{x conc}, CO_conc, HC_conc (1) are the average background corrected concentrations (ppm) of each mode in the diluted exhaust gas, as determined in Annex III, Appendix 2, Section 4.3.1.1.

4.5. Calculation of the specific emissions

The emissions (g/kWh) shall be calculated for all individual components in the following way:

The weighting factors (WF) used in the above calculation are according to Section 2.7.1.

4.6. Calculation of the area control values

For the three control points selected according to Section 2.7.6, the NO_x emission shall be measured and calculated according to Section 4.6.1 and also determined by interpolation from the modes of the test cycle closest to the respective control point according to Section 4.6.2. The measured values are then compared to the interpolated values according to Section 4.6.3.

4.6.1. Calculation of the specific emission

The NO_x emission for each of the control points (Z) shall be calculated as follows:

4.6.2. Determination of the emission value from the test cycle

The NO_x emission for each of the control points shall be interpolated from the four closest modes of the test cycle that envelop the selected control point Z as shown in Figure 4. For these modes (R, S, T, U), the following definitions apply:

Speed(R)

=

Speed(T) = n_RT

Speed(S)

=

Speed(U) = n_SU

Per cent load(R)

=

Per cent load(S)

Per cent load(T)

=

Per cent load(U).

The NO_x emission of the selected control point Z shall be calculated as follows:

and:

where,

E_R, E_S, E_T, E_U

=

specific NO_x emission of the enveloping modes calculated in accordance with Section 4.6.1.

M_R, M_S, M_T, M_U

=

engine torque of the enveloping modes

4.6.3. Comparison of NO_x emission values

The measured specific NO_x emission of the control point Z (NO_x,Z) is compared to the interpolated value (E_Z) as follows:

(1)

Based on C1 equivalent.