Page 401 - Advances in Eco-Fuels for a Sustainable Environment

Engine modification for alternative fuels usage in diesel engine 355

transesterification and esterification process. Transesterification process was carried
out at the molar ratio of 1:5 to 1:25, reaction temperature of 60 °C, reaction time of
60 minutes, stirrer speed of 300 rpm, and catalyst concentration of 0.5 to 2.5 wt. %.
Esterification process was carried out at molar ratio of 1:5 to 1:25 reaction temperature
of 60 °C, reaction time of 240 minutes, stirrer speed of 300 rpm, and catalyst concen-
tration of 3–7 wt.%. The experimental results revealed that optimum biodiesel yield of
93% was obtained at 60 °C, time of 60 min, and 1.5 wt.% of KOH catalyst using
tranesterification process. Efavi et al. [13] extracted oil from Citrullus vulgaris (water-
melon) seed. The reaction conditions were 5:1molar ratio, 60°C temperature, reaction
time 90, 120, 150min, and a different catalyst concentration of 0.13, 0.15, 0.18wt%
NaOH. Results showed that biodiesel yields of 70%, 53%, and 49% were obtained at
0.13, 0.15, and 0.18wt%, respectively. Vicente [14] investigated the biodiesel synthe-
sis from sunflower oil. The process parameters for biodiesel synthesis were optimized
by using the RSM approach. The maximum yield was obtained at a 50°C reaction tem-
perature, a molar ratio of 6:1, and 1.3wt% of catalyst concentration.
Many researchers recommended biodiesel as a substitute fuel for CI engines due to
it being free from sulfur as well as noncorrosive, produces lower exhaust emissions
when related to conventional diesel fuel, and good lubricating properties [5, 15].It
has higher viscosity and higher density, which leads to poor atomization resulting
in higher engine emissions and lower engine performance. To overcome the above
issues, biodiesel was blended with different additives such as alcohols, cetane
improvers, water emulsions, and nanoadditives, as noticed by Qi et al. [16]. Alberto
[17] reported that a biodiesel-alcohol blend reduced the exhaust emissions such as
unburned hydrocarbon, carbon monoxide, and smoke. However, Rakopoulos [18]
observed the drawbacks of pure biodiesel such as low auto ignition temperature,
higher viscosity, and density. Oxygenated additives such as ethanol and propanol
blended with biodiesel have solved those problems. Bhale et al. [19] stated that bio-
diesel has a poor low temperature property when related to diesel fuel. There is a
chances of crystal formation when the fuel temperature reaches below its cloud point.
Results in crystal growth and it enough to plug the diesel engine fuel lines. In order to
achieve the cold flow properties, the biodiesel is blended with either cloud point or
pour point fuel additives. Jeong et al. [20] observed that the biodiesel was produced
from high free fatty acids such as animal fats and vegetable oil through the trans-
esterification reaction. The cold filter plugging point (CFPP) was predicted for differ-
ent fatty acid ester content through an empirical equation based on its fatty acid
content. The results revealed that CFPP of biodiesel was higher than diesel; CFPP
was varied for biodiesels due to the melting point of the raw materials. Gomasta
and Mahla [21] reported the reduction of the flash and fire points by the use of addi-
tives such as alcohols. The value would be less than that of diesel if the ethanol limit is
>20% vol. in the blend.
Increasing public awareness about the environmental and health impacts of exhaust
emissions from diesel engines has stimulated policy makers to execute stringent emis-
sions legislation. Meeting the stringent emissions norms and improving the engine
performance could be achieved through fuel modification or engine modification.
In fuel modification, fuels are blended with alcohols or metal additives. In engine