The study of physiochemical properties and spraying characteristics of hybrid biofuel for compression ignition (ci) engine application
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Date
2018-05
Authors
Mohammad Azhar Fadzil
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Abstract
Straight vegetable oil (SVO) biofuels is one of potentially alternative
petroleum diesel fuel due to its comparable physical properties to that petroleum diesel
fuel. However, the high viscosity and density of SVO limits their direct application in
a CI engine. Therefore, to solve this problem, hybrid biofuels were introduced to
reduce the viscosity and density of SVO. In this study, biofuel of higher chain alcohol
(butanol and pentanol) was blended together with Refined Palm Oil (RPO). A total of
five blends with the mixing ratios of 10%, 20%, 30%, 40% and 50% of both alcohols
were prepared. Key properties of the fuel such as kinematic viscosity, calorific value
and density of the blends were measured and benchmarked against the biodiesel
standards based on ASTM D6751. It was found that viscosity, density and calorific
value of the blends decreased with the increase of alcohols fraction. Optimized blends
which were 50BUT50RPO and 53PEN47RPO have a comparable physiochemical
properties to that diesel fuel. The optimized blends were studied in term of their
spraying characteristic in a common rail injection system. The spray characteristics of
optimized blends were captured and measured. Both blends have a comparable spray
penetration at 1000 bar injection pressure. Meanwhile, the spray angle and width of
optimized blends were smaller in comparison with diesel-based fuel. This is due to the
comparatively higher viscosity and surface tension of hybrid biofuel blends, which
enhanced the friction effect between fuel and the injector nozzle surface and inhibited
the breakup of the liquid jet. Overall, both 50BUT:50RPO and 53PEN:47RPO have a
comparable physiochemical properties and spraying characteristic in comparison with
diesel-based fuel. Hence both hybrid biofuel blends can be used for a compression
ignition (CI) engine application.