23-03-2012, 03:31 PM
Theoretical Modeling and Experimental Study of Combustion and Performance
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I. INTRODUCTION
DIESEL engines are broadly used in medium and heavyduty
applications because of their lower fuel
consumption, higher brake thermal efficiency and lower
emissions (such as CO and HC) compared with gasoline
engines. Depletion of petroleum derivatives increases the
research interest in the area of alternative fuels.
TRANSESTERIFICATION OF VEGETABLE OIL
The vegetable oil was transesterified using methanol in the
presence of NaOH as a catalyst. The parameter involved in the
processing such as catalyst amount, molar ratio of alcohol to
oil, reaction temperature and reaction time are optimized [27],
[28].
TEST ENGINE AND EXPERIMENTAL PROCEDURE
The experiment was conducted on the four cylinder four
stroke turbocharged water cooled engine with the
specifications shown in Table 2.
Loading
The engine test bed consists of a test engine, hydraulic
dynamometer, measurement instruments and control panel.
The hydraulic dynamometer is water cooled and rated for 112
kW power absorption at 3000 rpm maximum operating speed.
The load on the dynamometer was measured by using a
mechanical dial gauge that was calibrated by using standard
weights just before the experiments.
III. PREPARATION OF TEST FUEL
In this experimental study diesel and biodiesel was used as
a fuel for standard (STD) engine and low heat rejection (LHR)
engine. 20% by volume of biodiesel was taken in a cleaned
vessel, which is mixed with 80% by volume of diesel, and
thus a stable mixture (hereafter the biodiesel blend is simply
referred as biodiesel) was prepared to use in the test engine.
V.CONVERSION OF STANDARD ENGINE (STD) IN TO LOW HEAT REJECTION (LHR) ENGINE
Increasing the coating thickness decreases the volumetric
efficiency and hence work done. In this experimental study
ceramic coating thickness was optimized as 0.5 mm [22], [23].
The engine combustion chamber was coated with partially
stabilized zirconia (PSZ) of 0.5 mm thickness, which includes
the piston crown, cylinder head, valves, and outside of the
cylinder liner. The equal amount of material has been
removed from the various parts of the combustion chamber
and PSZ was coated uniformly. After PSZ coating, the engine
was allowed to run about 10 hours, then test were conducted
on it.
THEORETICAL MODELING
The formula and empirical relations used for diesel cycle
simulation are considered and are explained in the following
chapter. In this analysis the molecular formula for diesel and
bio diesel are approximated, as C10H22 and C19H34O2 [29]. The
combustion model is developed for the C.I engine and suitable
for any hydrocarbon fuel and their blends. The molecular
formula of fuel is given as one of the input to the model along
with the other inputs shown in table.