Fuel crisis and environmental concerns have led to look for
alternative fuels of bio-origin sources such as vegetable oils,
which can be produced from forests, vegetable oil crops and oil
bearing biomass materials. Vegetable oils have energy content
comparable to diesel fuel. Straight vegetable oils posed several
operational problems and durability problems when subjected to
long-term usage in CI engine. These problems are attributed to
higher viscosity and lower volatility. The viscosity can be brought
in acceptable range by (i) converting the vegetable oil into methyl
ester, (ii) blending of oil with diesel fuel, (iii) blending of oil
with alcohols or (iv) increasing the fuel temperature to over 200°C
using exhaust gas waste heat. Reduction of viscosity by blending or
exhaust gas heating saves the chemical processing cost of
transesterification. In this work, performance and emission
parameters of a single-cylinder, four-stroke naturally aspirated,
unmodified diesel engine operating on neem oil and its blends of 5
vol%, 10 vol%, 15 vol% and 20 vol% with ethanol, 1-propanol,
1-butanol and 1-pentanol are evaluated and compared with diesel
operation. The measured performance parameters are brake thermal
efficiency, brake specific fuel consumption and engine exhaust
emission of CO, HC, NOx and smoke intensity.
Significant improvements in performance parameters and exhaust
emissions have been observed for the addition of these organic
compounds with neem oil.