Abstract:
The world now depends mostly on petroleum based fuels but recent concerns over
the environment, increasingly higher price and depletion of the limited reserves of
petroleum fuels have prompted the interest for development of alternative sources
of energy. Vegetable oils seem to be a very promising alternative source of energy
which can be employed in compression ignition (CI) engines. Different countries
of the world are looking in different vegetable oils that grow enormously in that
country. For the present study oil was extracted from sesame seed as it is the
second largest oil producing crop in Bangladesh but not so popular as edible oil
and several engine perfOlll1anCe related properties are tested and compared with
that of diesel fuel. The vegetable oil's volatility and heat content is found lower
but density and viscosity is found higher. Viscosity is considered as the main
obstacles of using them directly as CI engine fiJel. Researchers have reported that
this obstacle can be overcome by preheating, blending or using them as emulsion
or estcrs. In the present study preheating teclmique is employed to the crude
sesame oil and also to the 80% sesame blended with 20% diesel fuel oil and their
effects on engine performance is investigated on a direct injection, 4 stroke, 3
cylinder diesel engine. Engine performance has been evaluated with the help of
both conventional performance parameters and availability analysis. It is observed
that the engine exhibits better results for higher preheating temperature and
performance parameters become comparable with that of diesel when the
preheating temperature reaches 80°C. The perfonnance parameters of the blend
preheated at 100nC become very close to that of diesel fuel. Availability
efficiency shows also similar result but less than brake thermal efficiency. Major
portion of the fuel chemical availability is wasted in uncounted factors and nearly'
15';;, wasted with the exhaust gas which can be directly used for preheating.
Technically diesel fuel can be replaced with preheated sesame oil but the major
obstacle of using them is the high cost of sesame oil relative to diesel fuel.
