(a) This optional carbon balance error verification compares independently calculated quantities of carbon flowing into and out of an engine system. The engine system includes aftertreatment devices as applicable. Calculating carbon intake considers carbon-carrying streams flowing into the system, including intake air, fuel, and optionally DEF or other fluids. Carbon flow out of the system comes from exhaust emission calculations. Note that this verification is not valid if you calculate exhaust molar flow rate using fuel rate and chemical balance as described in § 1065.655(f)(3) because carbon flows into and out of the system are not independent. Use good engineering judgment to ensure that carbon mass in and carbon mass out data signals align.

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(b) Perform the carbon balance error verification after emission sampling is complete for a test sequence as described in § 1065.530(g)(5). Testing must include measured values as needed to determine intake air, fuel flow, and carbon-related gaseous exhaust emissions. You may optionally account for the flow of carbon-carrying fluids other than intake air and fuel into the system. Perform carbon balance error verification as follows:

(1) Calculate carbon balance error quantities as described in § 1065.643. The three quantities for individual test intervals are carbon mass absolute error, ?aC, carbon mass rate absolute error, ?aCrate, and carbon mass relative error, ?rC. Determine ?aC, ?aCrate, and ?rC for all test intervals. You may determine composite carbon mass relative error, ?rCcomp, as a fourth quantity that optionally applies for duty cycles with multiple test intervals.

(2) You meet the carbon balance error verification for a test sequence if all test intervals pass the test-interval criteria. A test interval passes if at least one of the absolute values of the three carbon balance error quantities for test intervals, ?aC, ?aCrate, and ?rC, is at or below its respective limit value in paragraphs (b)(2)(i) through (iii) of this section. You meet the carbon balance error verification for a duty cycle with multiple test intervals if the duty cycle passes the duty-cycle criterion. A duty cycle passes if the absolute value of the composite carbon mass relative error quantity, ?rCcomp, is at or below the limit value in paragraph (b)(2)(iii) of this section. Unless specified otherwise in the standard-setting part, if verification fails for a test sequence, you may repeat the entire test sequence or repeat individual test intervals as described in § 1065.526.

(i) Calculate the carbon mass absolute error limit, L?aC, in grams to three decimal places for comparison to the absolute value of ?aC, using the following equation:

Where:c = power-specific carbon mass absolute error coefficient = 0.007 g/kW.Pmax = maximum power from the engine map generated according to § 1065.510. If measured Pmax is not available, use a manufacturer-declared value for Pmax.Example:c = 0.007 g/kWPmax = 230.0 kWL?aC = 0.007 · 230.0L?aC = 1.610 g

(ii) Calculate the carbon mass rate absolute error limit, L?aCrate, in grams per hour to three decimal places for comparison to the absolute value of ?aCrate, using the following equation:

Where:d = power-specific carbon mass rate absolute error coefficient = 0.31 g/(kW·hr).Pmax = maximum power from the engine map generated according to § 1065.510. If measured Pmax is not available, use a manufacturer-declared value for Pmax.Example:d = 0.31 g/(kW·hr)Pmax = 230.0 kWL?aCrate = 0.31.230.0L?aCrate = 71.300 g/hr

(iii) The carbon mass relative error limit, L?rC, is 0.020 for comparison to the absolute value of ?rC, and to the absolute value of ?rCcomp.

(c) A failed carbon balance error verification might indicate one or more problems requiring corrective action, as follows: