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Open Access Publications from the University of California

Impact of Alternative Fuels and Emission Control Systems on Small Engines to Large Ocean Going Vessels

  • Author(s): Yang, Jiacheng
  • Advisor(s): Cocker, David R.
  • Durbin, Thomas D.
  • et al.

Emissions from internal combustion engines (ICEs) pose a big problem to human health and the environment, but they are controllable. This dissertation investigated the emissions from ICEs for a range of applications and the feasibility of reducing their emissions with various cutting edge emissions control systems (ECS) and alternative fuels. This included light-duty vehicles, heavy-duty diesel engines, small off-road diesel engines (SORDEs) and ocean going vessels (OGVs). The control technologies included gasoline particulate filters (GPFs) and scrubbers, and the alternative fuels included various ethanol blends and dimethyl carbonate (DMC).

It is important to investigate and understand the emissions from light-duty passenger vehicles since they represent the largest populations in the vehicle fleet. The rapid growth of gasoline direction injection (GDI) vehicles has increased concerns with particulate matter (PM) emissions. This dissertation investigated the impact of PM emissions from current technology GDI engines with different ECS and alternative fuels. This dissertation also evaluated the toxicity of PM emitted from GDI engines. GPFs were found to have a great potential for PM reduction, with reductions of approximately 98%, and they could be an effective tool to control PM emissions from GDI engines. Also, this dissertation investigated the use of ethanol fuel at various level in flex fuel GDI engines. The results suggested that the use of higher ethanol contents in gasoline could provide significant reductions in PM emissions on the order of 90%. The physical, chemical, and toxicological properties of the PM emissions from current technology GDI vehicles were also investigated in this dissertation via various health assays. Our results showed the toxicity of PM emitted from GDI vehicles was relatively low in comparison to many ambient PM samples.

Diesel engines are the most significant source of NOx and PM. The use of alternative fuels or advanced aftertreatment such as diesel particulate filters (DPFs) and selective catalytic reduction (SCR) have shown significant emissions control capability for diesel engines. The use of sensor technology in monitoring emissions from diesel ICEs has been of great interest in recent years, this dissertation investigated the accuracy of nitrogen oxides (NOx), PM, and particle number (PN) sensors compared to a standard 1065-compliant portable emissions measurement system (PEMS). The results showed comparisons within 10% for NOx, and good comparisons for PM relative to the future 1 mg/mi emissions standard. The PN sensor did show a high bias due to a zero offset current, however, that has been corrected in the latest version of the instrument. This dissertation also investigated a highly oxygenated alternative diesel fuel (DMC) at various blend levels. The results showed a 78% reduction in PM emissions with 30% DMC blend with regular diesel. The reduction of PM was significant and was comparable to the amount of reductions seen for DPFs.

This dissertation also evaluated the feasibility and effectiveness of equipping SORDEs in the range of 25-75 hp with advanced PM and/or NOx control systems. For those small engines, current regulations do not require ECS. Emissions benefits and engine performance with the addition of ECS were evaluated on an engine dynamometer over specific engine duty cycles. With the addition of advanced ECS, reductions of over 95% for PM and 50-70% of NOx were achieved. This information can be used to develop new regulations to control emissions from SORDEs.

Diesel engines in large OGVs are less controlled compare to light-duty passenger vehicles and heavy-duty trucks. The International Maritime Organization (IMO) has set various regulations for large OGVs to control their sulfur, PM, and NOx emissions. This dissertation investigated the performance of a cutting-edge sulfur scrubber ECS for reducing sulfur and PM emissions from a large container vessel. The results showed over a 97% reduction in sulfur species in gaseous phase as SO2, however, only a 2-12% reduction was observed for sulfur species in the particulate phase as sulfuric acid particles. The results from this study could impact regulations and vessel operators decisions on whether to use scrubber systems or switch to low sulfur marine fuels.

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