Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:23:p13
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 23 (pt 13/15)
Character Range: 1932522–1935613

may determine the value of R experimentally using the following procedures.

              4.1.1. Using the applicable bench cycle and ageing bench hardware, age several catalysts (minimum of 3 of the same catalyst design) at different control temperatures between the normal operating temperature and the damage limit temperature. Measure emissions (or catalyst inefficiency (1-catalyst efficiency)) for each exhaust constituent. Assure that the final testing yields data between one- and two-times the emission standard.

              4.1.2. Estimate the value of R and calculate the effective reference temperature (Tr) for the bench ageing cycle for each control temperature according to paragraph 2.3.1.4. of this annex.

              4.1.3. Plot emissions (or catalyst inefficiency) versus ageing time for each catalyst. Calculate the least-squared best-fit line through the data. For the data set to be useful for this purpose the data should have an approximately common intercept between 0 and 6,400 km. See Figure C4 App1/3 for an example.

              4.1.4. Calculate the slope of the best-fit line for each ageing temperature.

    Figure C4 App1/3
    Example of catalyst ageing
4.1.5. Plot the natural log (ln) of the slope of each best-fit line (determined in paragraph 4.1.4. of this appendix) along the vertical axis, versus the inverse of ageing temperature (1/(ageing temperature, deg K)) along the horizontal axis. Calculate the least squared best-fit lines through the data. The slope of the line is the R-factor. See Figure C4 App1/4 for an example.
              4.1.6. Compare the R-factor to the initial value that was used in paragraph 4.1.2. of this appendix. If the calculated R-factor differs from the initial value by more than 5 per cent, choose a new R-factor that is between the initial and calculated values, and then repeat the steps in paragraphs 4.1.2. to 4.1.6. of this appendix to derive a new R-factor. Repeat this process until the calculated R-factor is within 5 per cent of the initially assumed R-factor.

              4.1.7. Compare the R-factor determined separately for each exhaust constituent. Use the lowest R-factor (worst case) for the BAT equation.

              Figure C4 App1/4
       Determining the R-Factor

Annex C4 - Appendix 2

Standard Diesel Bench Cycle (SDBC)
This appendix applies to Level 1A only
              1. Introduction

               For particulate filters, the number of regenerations is critical to the ageing process. For systems that require desulphurisation cycles (e.g. NOx storage catalysts), this process is also significant.

               The standard diesel bench ageing durability procedure consists of ageing an after-treatment system on an ageing bench which follows the SDBC described in this appendix. The SDBC requires use of an ageing bench with an engine as the source of feed gas for the system.

               During the SDBC, the regeneration/desulphurisation strategies of the system shall remain in normal operating condition.

              2. The SDBC reproduces the engine speed