Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:110:p9
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 110 (pt 9/59)
Character Range: 626274–629184

Annex).

                -          The calculation shall be repeated for at least 5 rise and fall stimuli, and the results shall be averaged. The internal transforma- tion time (< 100 msec) of the reference flowmeter shall be subtracted from this value. This is the "look-ahead" value of the partial flow dilution system, which shall be applied in accordance with section 3.8.3.2 of Appendix 2 to this Annex.

        3.4.  Checking the partial flow conditions

              The range of the exhaust gas velocity and the pressure oscillations shall be checked and adjusted according to the requirements of section 2.2.1 of Annex V (EP), if applicable.

        3.5.  Calibration intervals

              The flow measurement instrumentation shall be calibrated at least every 3 months or whenever a system repair or change is made that could influence calibration.'
  (i)       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 com- ponents 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.

        2.   CALCULATIONS

        2.1.  Carbon flow rate into the engine (location 1)

              The carbon mass flow rate into the engine for a fuel CHαOε is given by:

              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:

              where:

              cCO2,r = wet CO2 concentration in the raw exhaust gas, %
              cCO2,a = wet CO2 concentration in the ambient air, % (around 0,04 %)
              qmew = exhaust gas mass flow rate on wet basis, kg/s
              Mre = molecular mass of exhaust gas

              If CO2 is measured on a dry basis it shall be converted to a wet