[1] Emission measurements were made for major gases and PM 2.5 mass for a post PanaMax Class container vessel operating on heavy fuel oil at sea. Additional measurements were made for PM composition, elemental and organic carbon, select hydrocarbons, including PAHs, carbonyls, and n-alkanes. The testing followed the International Standard Organization protocols for emission measurements and operating test cycle. Results showed the weighted emission factor for NO x and PM 2.5 were 19.77 ± 0.28 and 2.40 ± 0.05 g/kWh, respectively. The study provided a rare opportunity to repeat measurements made three years earlier on the same vessel. Emission factors of CO 2 and NO x closely matched the earlier values, suggesting a low deterioration factor. Results showed the black carbon emission factor was 0.007 ± 0.001 g/kWh, an important metric for determining the radiative forcing contribution of marine engines.

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A quasi-steady gas-jet model was applied to examine the spray trajectory in swirling flow during the ignition-delay period in an open-chamber diesel engine timed to start combustion at top dead center. Spray penetration, deflection, and the fractions of too-lean-mixed, burnable, and overpenetrated fuel at the start of combustion were calculated by employing the measured ignition delay and mean fuel-injection velocity. The calculated parameters were applied to correlate the measured exhaust hydrocarbon (HC) emissions. The engine parameters examined were bowl geometry, compression ratio, overall air-fuel ratio, and speed. Both the ignition delay and the relative spray-penetration parameter, defined as the ratio of the spray-penetration distances at the moments of start of combustion and wall impingement, gave good correlations for some of the engine parameters examined but could not explain all the measured trends. However, good correlation of the measured exhaust HC emissions was obtained by using the calculated too-lean-mixed and overpenetrated fuel fractions at the start of combustion. Correlation of the overpenetrated fuel with the measured HC indicated that approximately 2 percent of the fuel mass that overpenetrated before start of combustion emitted from the engine as unburned HC. This could account for 0 to 65 percent of the total HC emission from this engine. Additionally, it was found that the too-lean-mixed fuel could contribute 10 to 30 percent of the total HC emission, as found in a previous study on a somewhat similar engine. The remaining HC emission is caused by other sources such as bulk quenching.

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