Page 370 - Advances in Eco-Fuels for a Sustainable Environment

Physicochemical fuel properties and tribological behavior of aegle marmelos correa biodiesel 325

biodiesel, Karanja biodiesel, and Jatropha biodiesel are found to be 1°C, 4°C, and
6°C, respectively. The pour points of AMC biodiesel, Karanja biodiesel, and
Jatropha biodiesel are found to be 4°C, 2°C, and 7°C, respectively.
Fuel will be gelled entirely and stop working once the temperature goes below the
pour point temperature. However, the fuel might still work if the temperature goes
below the cloud point. However, when the fuel’s temperature reaches the cloud point
temperature, necessary steps must be taken to prevent the fuel from getting clogged in
the filters. This can be achieved by adding some antigel additives and also blending
the biodiesel with petroleum diesel so that the cloud and pour points are reduced fur-
ther. The greater the percentage of petroleum diesel in the biodiesel-diesel, the lesser
the value of the cloud and pour points of the blend. The antigel additives rec-
ommended for biodiesels are different from the ones that are recommended for diesel.
Cold weather performance of biodiesel can be improved further by adding heaters
all over the fuel passage, such as fuel lines and fuel tanks, etc. Even insulating every
part that comes under contact with heaters and fuels will improve the efficiency of
heaters to a great extent. The cloud and pour points of the biodiesels were found to
increase with increasing weight percentage of saturated long-chain methyl esters
(Long chain increases boiling point whereas branched chain increases are melting
point. Hence, long chain criteria are inversely proportional to melting point and thus
cloud and pour points). As discussed earlier, the weight percentage of long-chain sat-
urated methyl esters/saturated fatty acids decrease in this order: Jatropha, AMC, and
Karanja biodiesel. Hence, it can be concluded that their corresponding cloud and pour
points also decrease in the same order. "Winterization" is a counterprocess for
decreasing cloud and pour points even further by removing saturated methyl esters.
This removal is achieved by cooling the biodiesel to the crystallization point and fil-
tering out the high melting components.
A significant part of saturated methyl esters is removed during the winterization
process, which results in the high yield loss of saturated fatty acid esters; hence,
the winterization process is not an efficient method to solve the cold climate problem.
Moreover, this process alters a lot of physical and chemical properties. Using
branched-chain alcohol instead of methanol during the transesterification process
can significantly reduce the cloud and pour points of biodiesel, but this process also
has its limitations. It is not feasible to complete the reaction with isopropyl alcohol as
it takes too much time to complete the reaction and is also expensive. Another way by
which the cold flow properties of biodiesels can be improved is by blending them with
another biodiesel having a lower cloud and pour point compared to the primary bio-
diesel. In our case, Jatropha biodiesel’s cold flow characteristics can be improved by
blending it with either AMC biodiesel or Karanja biodiesel.

11.3.3.6 Acid number

The acid number indicates the FFA content of transesterified biodiesel. Free fatty
acids are those acids that are not present as triglycerides (fats) in the biodiesel. In
the saponification reaction, the triglycerides hydrolyze to yield fatty acids that react
with the alkali to form soap whereas the free fatty acids directly react with the base
while conducting the experiments to find out the acid value. The weight of free fatty