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Quality Assurance of Biodiesel by Water Content Determination
Quality problems caused by water in biofuel
While the negative effects of particle contamination in fuels
is well-known, the effects of water contamination were widely
underestimated. Depending on the water content, water exists
as dissolved water, dispersed throughout the oil, as emulsified
microscopic droplets or as a separate phase of free water.
Besides the reduction of the calorific value of the bulk fuel
resulting in slower acceleration, less
power and harder starting, the contamination
with water enhances rust formation and corrosion
of vital fuel system components. At temperatures below 0 °C
the forming of ice crystalls can clog fuel lines
and enhances crystallisation processes within the biodiesel.
The presence of water not only reverses the FAME to fatty
acids, but it significantly promotes the growth of bacteria
and fungi oxidizing the biodiesel to corrosive degradation
products (organic acids). Additionally, water hydrolyses certain
stabilisers, such as phenolic antioxidans, thus overruling
their interceptive character. Resulting oxidation products
can cause disturbances in the injection system
and in the engine itself. In view of this,
the EN 14214 standard specifies a maximum water content of
500 ppm for biodiesel.
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