ANNEX VIIISupplementary provisions
ANNEX VIII CO 2 EMISSIONS AND FUEL CONSUMPTION 1. INTRODUCTION 1.1. This Annex sets out the provisions and test procedures for reporting CO 2 emissions and fuel consumption. 2. GENERAL REQUIREMENTS 2.1. CO 2 emissions and fuel consumption shall be determined over the WHTC and WHSC test cycles in accordance with Section 7.2 to 7.8 of Annex 4B to UN/ECE Regulation No 49. 2.2. The test results shall be reported as cycle averaged brake specific values and expressed in the unit of g/kWh. 3. DETERMINATION OF CO 2 EMISSIONS 3.1. Raw measurement This Section shall apply, if CO 2 is measured in the raw exhaust gas. 3.1.1. Measurement CO 2 in the raw exhaust gas emitted by the engine submitted for testing shall be measured with a non-dispersive infrared (NDIR) analyser in accordance with Section 9.3.2.3 and Appendix 3 to Annex 4B to UN/ECE Regulation No 49. The measurement system shall meet the linearity requirements of Section 9.2 and Table 7of Annex 4B to UN/ECE Regulation No 49. The measurement system shall meet the requirements of Sections 9.3.1, 9.3.4 and 9.3.5 of Annex 4B to UN/ECE Regulation No 49. 3.1.2. Data evaluation The relevant data shall be recorded and stored in accordance with Section 7.6.6 of Annex 4B to UN/ECE Regulation No 49. The traces of the recorded concentrations and the trace of the exhaust gas mass flow rate shall be time aligned with the transformation time as defined in Section 3.1.30 of Annex 4B to UN/ECE Regulation No 49. 3.1.3. Calculation of cycle averaged emission If measured on a dry basis, the dry/wet correction according to Section 8.1 of Annex 4B to UN/ECE Regulation No 49 shall be applied to the instantaneous concentration values before any further calculation is done. The mass of CO 2 (g/test) shall be determined by calculating the instantaneous mass emissions from the raw CO 2 concentration and the exhaust gas mass flow, aligned with respect to their transformation times as determined in accordance with Section 8.4.2.2 of Annex 4B to UN/ECE Regulation No 49, integrating the instantaneous values over the cycle, and multiplying the integrated value with the u values of CO 2 from Table 5 of Annex 4B to UN/ECE Regulation No 49. The following equation shall be applied: (in g/test) where: u CO2 is the ratio between CO 2 density and density of the exhaust gas c CO2,i is the instantaneous CO 2 concentration in the exhaust gas, ppm q m ew,i is the instantaneous exhaust mass flow, kg/s f is the data sampling rate, Hz n is the number of measurements Optionally, the CO 2 mass may be calculated in accordance with Section 8.4.2.4 of Annex 4B to UN/ECE Regulation No 49 by using a CO 2 molar mass ( M CO2 ) of 44,01 g/mol. 3.2. Dilute measurement This Section applies, if CO 2 is measured in the dilute exhaust gas. 3.2.1. Measurement CO 2 in the dilute exhaust gas emitted by the engine submitted for testing shall be measured with a non-dispersive infrared (NDIR) analyser in accordance with Section 9.3.2.3 and Appendix 3 to Annex 4B to UN/ECE Regulation No 49. Dilution of the exhaust shall be done with filtered ambient air, synthetic air or nitrogen. The flow capacity of the full flow system shall be large enough to completely eliminate water condensation in the dilution and sampling systems. The measurement system shall meet the linearity requirements of Section 9.2 and Table 7 of Annex 4B to UN/ECE Regulation No 49. The measurement system shall meet the requirements of Sections 9.3.1, 9.3.4 and 9.3.5 of Annex 4B to UN/ECE Regulation No 49. 3.2.2. Data evaluation The relevant data shall be recorded and stored in accordance with Section 7.6.6 of Annex 4B to UN/ECE Regulation No 49. 3.2.3. Calculation of cycle averaged emission If measured on a dry basis, the dry/wet correction according to Section 8.1 of Annex 4B to UN/ECE Regulation No 49 shall be applied. For systems with constant mass flow (with heat exchanger), the mass of CO 2 (g/test) shall be determined with the following equation: (in g/test) where: c CO2,e is the average background corrected CO 2 concentration, ppm 0,001519 is the ratio between CO 2 density and density of air ( u factor) m ed is the total diluted exhaust mass over the cycle, kg For systems with flow compensation (without heat exchanger), the mass of CO 2 (g/test) shall be determined by calculating the instantaneous mass emissions and integrating the instantaneous values over the cycle. Also, the background correction shall be applied directly to the instantaneous concentration values. The following equation shall be applied: where: c CO2,e is the CO 2 concentration measured in the diluted exhaust gas, ppm c CO2,d is the CO 2 concentration measured in the dilution air, ppm 0,001519 is the ratio between CO 2 density and density of air ( u factor) m ed,i is the instantaneous mass of the diluted exhaust gas, kg m ed is the total mass of diluted exhaust gas over the cycle, kg D is the dilution factor Optionally, the u factor may be calculated with equation 57 in Section 8.5.2.3.1 of Annex 4B to UN/ECE Regulation No 49 by using a CO 2 molar mass ( M CO2 ) of 44,01 g/mol. CO 2 background correction shall be applied in accordance with Section 8.5.2.3.2 of Annex 4B to UN/ECE Regulation No 49. 3.3. Calculation of brake specific emissions The cycle work needed for the calculation of brake specific CO 2 emissions shall be determined in accordance with Section 7.8.6 of Annex 4B to UN/ECE Regulation No 49. 3.3.1. WHTC The brake specific emissions e CO2 (g/kWh) shall be calculated as follows: where: m CO2,cold is the CO 2 mass emissions of the cold start test, g/test m CO2,hot is the CO 2 mass emissions of the hot start test, g/test W act,cold is the actual cycle work of the cold start test, kWh W act,hot is the actual cycle work of the hot start test, kWh 3.3.2. WHSC The brake specific emissions e CO2 (g/kWh) shall be calculated as follows: where: m CO2 is the CO 2 mass emissions, g/test W act is the actual cycle work, kWh 4. DETERMINATION OF FUEL CONSUMPTION 4.1. Measurement Measurement of the instantaneous fuel flow shall be done by systems that preferably measure mass directly such as the following: (a) mass flow sensor; (b) fuel weighing; (c) Coriolis meter. The fuel flow measurement system shall have the following: (a) an accuracy of ± 2 % of the reading or ± 0,3 % of full scale whichever is better; (b) a precision of ± 1 % of full scale or better; (c) a rise time that does not exceed 5 s. The fuel flow measurement system shall meet the linearity requirements of Section 9.2 and Table 7 of Annex 4B to UN/ECE Regulation No 49. Precautions shall be taken to avoid measurement errors. Such precautions shall at least include the following: (a) the careful installation of the device according to the instrument manufacturers’ recommendations and to good engineering practice; (b) flow conditioning as needed to prevent wakes, eddies, circulating flows, or flow pulsations that affect accuracy or precision of the fuel flow system; (c) account for any fuel that bypasses the engine or returns from the engine to the fuel storage tank. 4.2. Data evaluation The relevant data shall be recorded and stored in accordance with Section 7.6.6 of Annex 4B to UN/ECE Regulation No 49. 4.3. Calculation of cycle averaged fuel consumption The mass of fuel (g/test) shall be determined by the sum of the instantaneous values over the cycle, as follows: where: q m f,i is the instantaneous fuel flow, kg/s f is the data sampling rate, Hz n is the number of measurements 4.4. Calculation of brake specific fuel consumption The cycle work needed for the calculation of the brake specific fuel consumption shall be determined in accordance with Section 7.8.6 of Annex 4B to UN/ECE Regulation No 49. 4.4.1. WHTC The brake specific fuel consumption e f (g/kWh) shall be calculated as follows: where: q m f, cold is the fuel mass of the cold start test, g/test q m f, hot is the fuel mass of the hot start test, g/test W act, cold is the actual cycle work of the cold start test, kWh W act, hot is the actual cycle work of the hot start test, kWh 4.4.2. WHSC The brake specific fuel consumption e f (g/kWh) shall be calculated as follows: where: q m f is the fuel mass, g/test W act is the actual cycle work, kWh