Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:10:p19
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 10 (pt 19/30)
Character Range: 572620–575635

calculated and integrated over the cycle. In this case, the instantaneous mass of the diluted exhaust gas shall be calculated as follows.

         For the PDP-CVS system:

         where:

         NP,i = total revolutions of pump per time interval

         For the CFV-CVS system:

         where:

         Δti = time interval, s

         For the SSV-CVS system:

         where:

         Δti = time interval, s

              The real time calculation shall be initialised with either a reasonable value for Cd, such as 0,98, or a reasonable value of Qssv. If the calculation is initialised with Qssv, the initial value of Qssv shall be used to evaluate Re.

              During all emissions tests, the Reynolds number at the SSV throat must be in the range of Reynolds numbers used to derive the calibration curve developed in section 2.4 of Appendix 5 to this Annex.

        4.2.  Determination of raw exhaust gas mass flow

              For calculation of the emissions in the raw exhaust gas and for controlling of a partial flow dilution system, it is necessary to know the exhaust gas mass flow rate. For the determination of the exhaust mass flow rate, either of the methods described in sections 4.2.2 to 4.2.5 may be used.

        4.2.1. Response time

              For the purpose of emissions calculation, the response time of either method described below shall be equal to or less than the requirement for the analyzer response time, as defined in section 1.5 of Appendix 5 to this Annex.

              For the purpose of controlling of a partial flow dilution system, a faster response is required. For partial flow dilution systems with online control, a response time of ≤ 0,3 seconds is required. For partial flow dilution systems with look ahead control based on a pre-recorded test run, a response time of the exhaust flow measurement system of ≤ 5 seconds with a rise time of ≤ 1 second is required. The system response time shall be specified by the instrument manufacturer. The combined response time requirements for exhaust gas flow and partial flow dilution system are indicated in section 3.8.3.2.

        4.2.2. Direct measurement method

              Direct measurement of the instantaneous exhaust flow may be done by systems such as:

              - pressure differential devices, like flow nozzle,

              - ultrasonic flowmeter,

              - vortex flowmeter.

              Precautions shall be taken to avoid measurement errors which will impact emission value errors. Such precautions include the care- ful installation of the device in the engine exhaust system according to the instrument manufacturers' recommendations and to good engineering practice. Engine performance and emissions shall especially not be affected by the installation of the device.

              The accuracy of exhaust flow determination shall be at least ± 2,5 % of reading or ± 1,5 % of engine's maximum value, whichever is the greater.

        4.2.3. Air