Emissions of 2-Stroke Scooters with Ethanol Blends 2009-24-0143
A well balanced use of alternative fuels is an important objective for a sustainable development of individual transportation worldwide.
Several countries have objectives to substitute a part of the energy of traffic by ethanol as the renewable energy source.
Investigations of limited and unregulated emissions of two 2-S scooters with gasoline-ethanol blend fuels have been performed in the present work according to the measuring procedures, which were established in the previous research in the Swiss Scooter Network (since 2000).
The investigated fuels contained ethanol (E), in the portion of 5, 10, 15 and 20% by volume.
The investigated 2-S scooters represented a newer and an older 2-stroke technology with carburettor. The newer one was investigated with and without catalyst and the older one only in the original state without catalyst.
Since there is a special concern about the particle emissions of the small engines, the particle mass and nanoparticle measurements were systematically performed.
The nanoparticulate emissions were measured by means of SMPS (CPC) and NanoMet *).
The most important results for application of ethanol blends on 2-S scooters are:
addition of ethanol to the gasoline provokes a leaner tuning of the engine operation,
influence of the leaning effect by means of ethanol depends very much on the basic original tuning,
for the investigated newer 2-S scooter the irregularities of combustion and loss of power were remarkable, with higher ethanol content,
the richer basic tuning of the newer 2-S scooter enabled a satisfactory driveability with E10,
the older 2-S scooter with richer basic tuning was little influenced by ethanol blends: good performances and reduction of CO and of fuel consumption up to E20, no impact on (nano)particles emissions,
at the beginning of operation with ethanol blends some release of particles (residues) from the engine and exhaust system was observed (wash out effect),
with catalyst there is an efficient reduction of CO, HC, PM and NP, the higher share of ethanol can lower the exhaust temperature and due to that lower the catalytic converter efficiency.
The present investigations with ethanol did not concern the durability of parts exposed to the chemical influences of ethanol. Also the cold startability, particularly in extreme conditions was not addressed.