Two-stroke direct fuel injection of gaseous fuels
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Date
2010
Authors
Yew Heng, Teoh
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Abstract
The commonly used carbureted two-stroke engines in developing countries have
high exhaust emission and poor fuel efficiency. To meet more rigid emissions
requirements, two-stroke vehicles are typically phase out in favor of four-stroke
engines. The problems of ubiquitous legacy two-stroke vehicles remain unsolved by
these measures and they are likely to be a major source of transport for many years to
come. A number of technologies are available for solving the problems associated
with two-stroke engines such as catalytic after-treatment and direct fuel injection
(Dl). However, these solutions are relatively high cost and have shown only slow
market acceptance for applications in developing countries. Research in recent years
has demonstrated that direct fuel injection is a well developed and readily deployable
solution to existing two-stroke engines.
Gaseous fuels such as Liquefied Petroleum Gas (LPG) are considered a promising
energy source and in many countries provide fuel cost savings. LPG coupled with DI
two-stroke technologies, is expected to be clean and cost effective retrofit solution
for two-stroke engines. In this research project, direct injection (DI) of Liquefied
Petroleum Gas (LPG) is introduced and tested on a typical two-stroke engine. Results
of in cylinder combustion pressure, fuel mass fraction burned, engine performance
and exhaust emissions are taken and compared for various injection timings from
premixed (early injection) to fully direct injection mode (late injection). Results
show that DI of LPG effectively reduces exhaust hydrocarbon emission by 70% and
can substantially improve the fuel economy by 38% compared with carbureted
gasoline.