27-07-2012, 04:04 PM
Mathematical Correlation for Brake Thermal Efficiency and NOx Emission of CI Engine using Ester of Vegetable Oils
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INTRODUCTION
THE use of plant oil as fuel for CI engine is not new. Dr.
Rudolf Diesel (Inventor of diesel engine) demonstrated
his engine in Paris in 1900 using groundnut oil as fuel. The
plant oil fuels were not accepted much at that time, as they
were more expensive. It was found that all properties of plant
oils were close to diesel except viscosity and volatility [1].
MATERIALS AND METHOD
A. Transesterification of Vegetable Oils:
The formation of methyl esters by transesterification of
vegetable oils requires 3 moles of alcohol stoichiometrically
[3]. However, excess alcohol is required to drive the reaction
close to completion and to obtain a maximum ester yield.
Single step alkali/base catalyzed transesterification process as
discussed in [10] is adopted for converting CSO, SO, JO and
HO to methyl esters of fatty acids.
DEVELOPMENT OF MATHEMATICAL CORRELATION
Brake thermal efficiency (BTE) of the engine is the major
parameter of interest for any fuel used as far as CI engine
performance is concerned. It is the ratio of work output of the
engine to the heat input in general. Expressed as, enthalpy
efficiency in thermodynamics. The BTE of the engine is
influenced by various parameters, while using different fuels
having different properties. The factors which may have
significant impact on BTE are considered for formulation of
mathematical model for the present study and they are namely
brake power, rotational speed of engine, torque developed,
mass of fuel consumed, mass of air required, calorific value of
fuel, densities of fuel and air, viscosity of fuel, heat carried
away by cooling water, compression ratio, length of stroke
and diameter of piston and atmospheric pressure etc. In all 19
variables are identified, and by using Buckingham