Characteristics of Emissions from a Portable Two-stroke Gasoline Engine

This work investigates the engine performance and emission characteristics of a portable two-stroke gasoline engine (P2SGE) fueled by unleaded gasoline #92 blended with different 2-stroke engine oil brands (CPC Super Low Smoke Two- Stroke Engine Oil (SLS), CPC Low Smoke Two-Stroke Engine Oil (LS), and MERCURY STAR Two-Stroke Engine Oil (MS)) and operated at idling (0 kW), medium (1.5 kW) and high load (1.9 kW). Experimental results indicate that the emission factors (EFs) of HC and CO decreased with rising P2SGE load when each of the lubricants was used in the gasoline engine, while that of NO_x exhibited an opposite trend. Using different brands of two-stroke engine oil did not influence the fuel consumption (FC) or specific fuel consumption (SFC) of P2SGE under the same engine speed. The mass concentrations and EFs of PM when adding the tested three lubricants were in the order MS ＞ SLS ＞ LS at all loads. 85% of the PM mass emitted from the P2SGE was contributed by carbonaceous matters (EC and OC) in all test conditions. The EFs based on the FC and output energy of PM-bound OC were higher than those of EC at idling condition, while an opposite trend (OC ＜ EC) was observed at the medium (1.5 kW) and high (1.9 kW) engine loads. Additionally, the ratio of OC/EC decreased with increasing engine load, regardless of the difference in 2-stroke engine oil composition. Nap and PA dominated in the mass concentration among 16 investigated PAH homologs, while BaP and BaA mainly contributed the BaP_(eq) concentrations, except using LS at high-load operation. Compared to the use of MS, the reductions of ΣPAHs and ΣBaP_(eq) concentrations were 46.4% and 54.8%, respectively for using SLS, and 59.7% and 49.2%, respectively for using LS.