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The following Appendix 6 is added: ‘Appendix 6 CARBON FLOW CHECK 1. INTRODUCTION All but a tiny part of the carbon in the exhaust comes from the fuel, and all but a minimal part of this is manifest in the exhaust gas as CO2. This is the basis for a system verification check based on CO2 measurements. The flow of carbon into the exhaust measurement systems is determined from the fuel flow rate. The flow of carbon at various sampling points in the emissions and particulate sampling systems is determined from the CO2 concentrations and gas flow rates at those points. In this sense, the engine provides a known source of carbon flow, and observing the same carbon flow in the exhaust pipe and at the outlet of the partial flow PM sampling system verifies leak integrity and flow measurement accuracy. This check has the advantage that the components are operating under actual engine test conditions of temperature and flow. The following diagram shows the sampling points at which the carbon flows shall be checked. The specific equations for the carbon flows at each of the sample points are given below. Measuring points for carbon flow check Air Fuel CO2 RAW ENGINE Partial Flow System CO2 PFS 2. CALCULATIONS 2.1. Carbon flow rate into the engine (location 1) The carbon mass flow rate into the engine for a fuel CH α O ε is given by: Text of image qmCf = 12,011 12,011 + α + 15,9994 × ε × qmf where: qmf = fuel mass flow rate, kg/s 2.2. Carbon flow rate in the raw exhaust (location 2) The carbon mass flow rate in the exhaust pipe of the engine shall be determined from the raw CO2 concentration and the exhaust gas mass flow rate: Text of image qmCe = (cCO2,r - cCO2,a 100) × qmew × 12,011 Mre where: If CO2 is measured on a dry basis it shall be converted to a wet basis according to section 5.2 of Appendix 1 to this Annex. 2.3. Carbon flow rate in the dilution system (location 3) The carbon flow rate shall be determined from the dilute CO2 concentration, the exhaust gas mass flow rate and the sample flow rate: Text of image qmCp = (cCO2,d - cCO2,a 100) × qmdew × 12,011 Mre × qmew qmp where: If CO2 is measured on a dry basis, it shall be converted to wet basis according to section 5.2 of Appendix 1 to this Annex. 2.4. The molecular mass (Mre) of the exhaust gas shall be calculated as follows: Text of image Mre = 1 + qmf qmaw qmf qmaw × α 4 + ε 2 + δ 2 12,011 + 1,00794 × α + 15,9994 × ε + 14,0067 × δ + 32,065 × γ + Ha × 10–3 2 × 1,00794 + 15,9994 + 1 Mra 1 + Ha × 10–3 where: Alternatively, the following molecular masses may be used: c CO2,r | = | wet CO2 concentration in the raw exhaust gas, % c CO2,a | = | wet CO2 concentration in the ambient air, % (around 0,04 %) q mew | = | exhaust gas mass flow rate on wet basis, kg/s M re | = | molecular mass of exhaust gas c CO2,d | = | wet CO2 concentration in the dilute exhaust gas at the outlet of the dilution tunnel, % c CO2,a | = | wet CO2 concentration in the ambient air, % (around 0,04 %) q mdew | = | diluted exhaust gas mass flow rate on wet basis, kg/s q mew | = | exhaust gas mass flow rate on wet basis, kg/s (partial flow system only) qmp | = | sample flow of exhaust gas into partial flow dilution system, kg/s (partial flow system only) M re | = | molecular mass of exhaust gas q mf | = | fuel mass flow rate, kg/s q maw | = | intake air mass flow rate on wet basis, kg/s H a | = | humidity of intake air, g water per kg dry air M ra | = | molecular mass of dry intake air (= 28,9 g/mol) α, δ, ε, γ | = | molar ratios referring to a fuel CH α O δ N ε S γ M re (diesel) | = | 28,9 g/mol M re (LPG) | = | 28,6 g/mol M re (NG) | = | 28,3 g/mol’

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Source: EUR-Lex (Cellar) · retrieved 2026-11-10 · Text as adopted (Official Journal); later amendments are not incorporated in this text.