xmlns:atom="http://www.w3.org/2005/Atom" xmlns:atom="http://www.w3.org/2005/Atom"
Table 1 | |||||||
Raw exhaust gas u values and component densities | |||||||
a depending on fuel. | |||||||
b at λ = 2, dry air, 273 K, 101,3 kPa. | |||||||
c u accurate within 0,2 % for mass composition of: C = 66 - 76 %; H = 22 - 25 %; N = 0 - 12 %. | |||||||
d NMHC on the basis of CH2,93 (for total HC the u gas coefficient of CH4 shall be used). | |||||||
e u accurate within 0,2 % for mass composition of: C3 = 70 - 90 %; C4 = 10 - 30 %. | |||||||
Fuel | ρ e | Gas | |||||
---|---|---|---|---|---|---|---|
NOx | CO | HC | CO2 | O2 | CH4 | ||
ρ gas [kg/m3] | |||||||
2,053 | 1,25 | a | 1,9636 | 1,4277 | 0,716 | ||
u gas b | |||||||
Diesel (B7) | 1,2943 | 0,001586 | 0,000966 | 0,000482 | 0,001517 | 0,001103 | 0,000553 |
Ethanol (ED95) | 1,2768 | 0,001609 | 0,00098 | 0,00078 | 0,001539 | 0,001119 | 0,000561 |
CNGc | 1,2661 | 0,001621 | 0,000987 | 0,000528d | 0,001551 | 0,001128 | 0,000565 |
Propane | 1,2805 | 0,001603 | 0,000976 | 0,000512 | 0,001533 | 0,001115 | 0,000559 |
Butane | 1,2832 | 0,0016 | 0,000974 | 0,000505 | 0,00153 | 0,001113 | 0,000558 |
LPGe | 1,2811 | 0,001602 | 0,000976 | 0,00051 | 0,001533 | 0,001115 | 0,000559 |
Table 2 | |||||||
Dilute exhaust gas u values and component densities | |||||||
a depending on fuel. | |||||||
b at λ = 2, dry air, 273 K, 101,3 kPa. | |||||||
c u accurate within 0,2 % for mass composition of: C = 66 - 76 %; H = 22 - 25 %; N = 0 - 12 %. | |||||||
d NMHC on the basis of CH2,93 (for total HC the u gas coefficient of CH4 shall be used). | |||||||
e u accurate within 0,2 % for mass composition of: C3 = 70 - 90 %; C4 = 10 - 30 %. | |||||||
Fuel | ρ de | Gas | |||||
---|---|---|---|---|---|---|---|
NOx | CO | HC | CO2 | O2 | CH4 | ||
ρ gas [kg/m3] | |||||||
2,053 | 1,25 | a | 1,9636 | 1,4277 | 0,716 | ||
u gas b | |||||||
Diesel (B7) | 1,293 | 0,001588 | 0,000967 | 0,000483 | 0,001519 | 0,001104 | 0,000553 |
Ethanol (ED95) | 1,293 | 0,001588 | 0,000967 | 0,00077 | 0,001519 | 0,001104 | 0,000553 |
CNGc | 1,293 | 0,001588 | 0,000967 | 0,000517d | 0,001519 | 0,001104 | 0,000553 |
Propane | 1,293 | 0,001588 | 0,000967 | 0,000507 | 0,001519 | 0,001104 | 0,000553 |
Butane | 1,293 | 0,001588 | 0,000967 | 0,000501 | 0,001519 | 0,001104 | 0,000553 |
LPGe | 1,293 | 0,001588 | 0,000967 | 0,000505 | 0,001519 | 0,001104 | 0,000553 |
The LDS employs the single line spectroscopy principle. The NH3 absorption line is chosen in the near infrared spectral range and scanned by a single-mode diode laser.
The analyser shall be installed either directly in the exhaust pipe (in-situ) or within an analyser cabinet using extractive sampling in accordance with the instrument manufacturers instructions. If installed in an analyser cabinet, the sample path (sampling line, pre-filter(s) and valves) shall be made of stainless steel or PTFE and shall be heated to 463 ± 10 K (190 ± 10 °C) in order to minimise NH3 losses and sampling artefacts. In addition, the sampling line shall be as short as practically possible.
Influence from exhaust temperature and pressure, installation environment and vibrations on the measurement shall be minimised, or compensation techniques be used.
If applicable, sheath air used in conjunction with in-situ measurement for protection of the instrument, shall not affect the concentration of any exhaust component measured downstream of the device, or sampling of other exhaust components shall be made upstream of the device.
The spectral resolution of the laser shall be within 0,5 cm-1 in order to minimise cross interference from other gases present in the exhaust gas.
The FTIR employs the broad waveband infrared spectroscopy principle. It allows simultaneous measurement of exhaust components whose standardised spectra are available in the instrument. The absorption spectrum (intensity/wavelength) is calculated from the measured interferogram (intensity/time) by means of the Fourier transform method.
The FTIR shall be installed in accordance with the instrument manufacturer's instructions. The NH3 wavelength shall be selected for evaluation. The sample path (sampling line, pre-filter(s) and valves) shall be made of stainless steel or PTFE and shall be heated to 463 ± 10 K (190 ± 10 °C) in order to minimise NH3 losses and sampling artefacts. In addition, the sampling line shall be as short as practically possible.
The spectral resolution of the NH3 wavelength shall be within 0,5 cm-1 in order to minimise cross interference from other gases present in the exhaust gas.
Prior to the emissions test, the analyser range shall be selected. Emission analysers with automatic or manual range switching shall be permitted. During the test cycle, the range of the analysers shall not be switched.
Zero and span response shall be determined, if the provisions of point 3.4.2 do not apply for the instrument. For the span response, a NH3 gas that meets the specifications of point 4.2.7 shall be used. The use of reference cells that contain NH3 span gas is permitted.
At the start of the test sequence, the NH3 data collection shall be started, simultaneously. The NH3 concentration shall be measured continuously and stored with at least 1 Hz on a computer system.
At the completion of the test, sampling shall continue until system response times have elapsed. Determination of analyser's drift according to point 3.4.1 shall only be required if the information in point 3.4.2 is not available.
if the zero and span drift specified by the instrument manufacturer in points 4.2.3 and 4.2.4 meets the requirements of point 3.4.1;
the time interval for zero and span drift specified by the instrument manufacturer in points 4.2.3 and 4.2.4 exceeds the duration of the test.
The average NH3 concentration (ppm/test) shall be determined by integrating the instantaneous values over the cycle. The following equation shall be applied:
where:
c NH3,i is the instantaneous NH3 concentration in the exhaust gas, ppm,
n is the number of measurements.
For the WHTC, the final test result shall be determined with the following equation:
c NH3 = (0,14 × c NH3,cold) + (0,86 × c NH3,hot)
where:
is the average NH3 concentration of the cold start test, ppm,
is the average NH3 concentration of the hot start test, ppm.
The analyser shall comply with the linearity requirements specified in Table 7 of Annex 4B to UN/ECE Regulation No 49. The linearity verification in accordance with Section 9.2.1 of Annex 4B to UN/ECE Regulation No 49, shall be performed at least every 12 months or whenever a system repair or change is made that could influence calibration. With the prior approval of the approval authority, less than 10 reference points are permitted, if an equivalent accuracy can be demonstrated.
For the linearity verification, a NH3 gas that meets the specifications of point 4.2.7 shall be used. The use of reference cells that contain NH3 span gas shall be permitted.
Instruments, whose signals are used for compensation algorithms, shall meet the linearity requirements specified in Table 7 of Annex 4B to the UN/ECE Regulation No 49. Linearity verification shall be done as required by internal audit procedures, by the instrument manufacturer or in accordance with ISO 9000 requirements.
The analyser shall have a measuring range and response time appropriate for the accuracy required to measure the concentration of NH3 under transient and steady state conditions.
The analyser shall have a minimum detection limit of < 2 ppm under all conditions of testing.
The accuracy, defined as the deviation of the analyser reading from the reference value, shall not exceed ± 3 % of the reading or ± 2 ppm, whichever is larger.
The drift of the zero response and the related time interval shall be specified by the instrument manufacturer.
The drift of the span response and the related time interval shall be specified by the instrument manufacturer.
The system response time shall be ≤ 20 s.
The rise time of the analyser shall be ≤ 5 s.
A gas mixture with the following chemical composition shall be available:
NH3 and purified nitrogen.
The true concentration of the calibration gas shall be within ± 3 % of the nominal value. The concentration of NH3 shall be given on a volume basis (volume per cent or volume ppm).
The expiration date of the calibration gases stated by the manufacturer shall be recorded.
Other systems or analysers may be approved by the approval authority, if it is found that they yield equivalent results in accordance with Section 5.1.1 of Annex 4B to UN/ECE Regulation No 49.
‘Results’ shall refer to average cycle specific NH3 concentrations.
The mass of the pollutants (g/test) shall be determined in accordance with Section 8.4.2.3 or 8.4.2.4 of Annex 4B to UN/ECE Regulation No 49 with the u values from Table 3.
Raw exhaust gas u values and component densities
The mass of the pollutants (g/test) shall be determined in accordance with Section 8.5.2.3 of Annex 4B to UN/ECE Regulation No 49 with the u values from Table 4.
Dilute exhaust gas u values and component densities
For systems with flow compensation, the u gas values given in Table 4, shall be inserted into equation 62 of Section 8.5.2.3.3 of Annex 4B to UN/ECE Regulation No 49.
The emissions shall be background corrected according to the requirements of Section 8.5.2.3.2 of Annex 4B to UN/ECE Regulation No 49. If the fuel composition is not known, the following stoichiometric factors may be used:
=
13,3
=
11,5
However, the test procedures in Section 7 of Annex 4B to UN/ECE Regulation No 49 and the emission calculations provided in Section 2.1 of this Appendix and in Section 8 of Annex 4B to UN/ECE Regulation No 49 shall apply.