Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:99:p32
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 99 (pt 32/39)
Character Range: 1243244–1246558

the fuels used by a dual-fuel engine can also change dynamically depending of the operating condition of the engine. As a result special precautions and restrictions are necessary to enable emission testing of these engines.

              A.4.2. Test conditions (Annex 4, section 6.)

              A.4.2.1. Laboratory test conditions (Annex 4, paragraph 6.1.)

              The parameter fa for dual-fuel engines shall be determined with formula (a)(2) in paragraph 6.1. of Annex 4 to this Regulation.

              A.4.3. Test procedures (Annex 4, section 7.)

              A.4.3.1. Measurement procedures (Annex 4, paragraph 7.1.3.)

              The recommended measurement procedure for dual-fuel engines is procedure (b) listed in paragraph 7.1.3. of Annex 4 (CVS system).

              This measurement procedure ensures that the variation of the fuel composition during the test will only influence the hydrocarbon measurement results. This shall be compensated via one of the methods described in section 4.4.

              Other measurement methods such as method (a) listed in paragraph 7.1.3. of Annex 4 (raw gaseous/partial flow measurement) can be used with some precautions regarding exhaust mass flow determination and calculation methods. Fixed values for fuel parameters and ugas-values shall be applied as described in Appendix 6.

              A.4.4. Emission calculation (Annex 4, section 8.)

              The emissions calculation on a molar basis, in accordance with Annex 7 of gtr No. 11 concerning the exhaust emission test protocol for Non-Road Mobile Machinery (NRMM), is not permitted.

              A.4.4.1. Dry/wet correction (Annex 4, section 8.1.)

              A.4.4.1.1. Raw exhaust gas (Annex 4, paragraph 8.1.1.)

              Equations 15 and 17 in Annex 4, paragraph 8.1.1. shall be used to calculate the dry/wet correction.

              The fuel specific parameters shall be determined according to sections A.6.2. and A.6.3. of Appendix 6.

              A.4.4.1.2. Diluted exhaust gas (Annex 4, paragraph 8.1.2.)

              Equations 19 and 20 in Annex 4 paragraph 8.1.2. shall be used to calculate the wet/dry correction.

              The molar hydrogen ratio α of the combination of the two fuels shall be used for the dry/wet correction. This molar hydrogen ratio shall be calculated from the fuel consumption measurement values of both fuels according to section A.6.4. of Appendix 6.

              A.4.4.2. NOx correction for humidity (Annex 4, section 8.2.)

              The NOx humidity correction for compression ignition engines as specified in paragraph 8.2.1. of Annex 4 shall be used to determine the NOx humidity correction for dual-fuel engines.

               (A4.1)

               where:

               Ha is the intake air humidity, g water per kg dry air

              A.4.4.3. Partial flow dilution (PFS) and raw gaseous measurement (Annex 4, section 8.4.)

              A.4.4.3.1. Determination of exhaust gas mass flow (Annex 4, paragraph 8.4.1.)

              The exhaust mass flow shall be determined according to the direct measurement method as described in section 8.4.1.3.

              Alternatively the airflow and air to fuel ratio measurement method according to paragraph 8.4.1.6. (equations 30, 31 and 32) may