Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:20:p25
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 20 (pt 25/29)
Character Range: 287110–289972

the engine warm-up.
 Average specific emissions between regeneration phases shall be determined from the arithmetic mean of several approximately equidistant WHTC hot start test results (g/kWh). As a minimum, at least one WHTC hot start test as close as possible prior to a regeneration test and one WHTC hot start test immediately after a regeneration test shall be conducted. As an alternative, the manufacturer may provide data to show that the emissions remain constant (25 per cent or 0.005 g/kWh, whichever is greater) between regeneration phases. In this case, the emissions of only one WHTC hot start test may be used.
 During the regeneration test, all the data needed to detect regeneration shall be recorded (CO or NOx emissions, temperature before and after the after-treatment system, exhaust back pressure, etc.).
  During the regeneration test, the applicable emission limits may be exceeded.
  The test procedure is schematically shown in Figure 2.

       Figure 2
       Scheme of periodic regeneration

 The WHTC hot start emissions shall be weighted as follows:
  (5)
 Where:
n is the number of WHTC hot start tests without regeneration
nr is the number of WHTC hot start tests with regeneration (minimum one test)
 is the average specific emission without regeneration, g/kWh
 is the average specific emission with regeneration, g/kWh
 For the determination of , the following provisions apply:
(a) If regeneration takes more than one hot start WHTC, consecutive full hot start WHTC tests shall be conducted and emissions continued to be measured without soaking and without shutting the engine off, until regeneration is completed, and the average of the hot start WHTC tests be calculated;
(b) If regeneration is completed during any hot start WHTC, the test shall be continued over its entire length.
 In agreement with the Type Approval Authority, the regeneration adjustment factors may be applied either multiplicative (c) or additive (d) based upon good engineering analysis.
(c) The multiplicative adjustment factors shall be calculated as follows:
  (upward) (6)
  (downward) (6a)
(d) The additive adjustment factors shall be calculated as follows:
 kr,u = ew - e (upward) (7)
 kr,d = ew - er (downward) (8)
 With reference to the specific emission calculations in paragraph 8.6.3., the regeneration adjustment factors shall be applied, as follows:
(e) For a test without regeneration, kr,u shall be multiplied with or be added to, respectively, the specific emission e in equations 69 or 70;
(f) For a test with regeneration, kr,d shall be multiplied with or be added to, respectively, the specific emission e in equations 69 or 70.
 At the request of the manufacturer, the regeneration adjustment factors:
(g) May be extended to other members of the same engine family;
(h) May be extended to other engine families using the same