In the present study, research was conducted to increase the combustion
efficiency in a diesel engine by adding 100 and 200 ppm aluminum powder to
diesel and biodiesel (produced from 10% spent coffee ground oil and 90% waste
cooking oil) blends. Aluminum powder is a flammable metal. Due to this feature,
it has been used as an additive to liquid fuels in many studies in the
literature. In general, it has been reported that thermal efficiency increases
with the addition of aluminum particles. However, the high explosion sensitivity
of aluminum can affect its stable combustion. In addition, Al is a metal that
can be easily oxidized. Therefore, coating aluminum is considered a good
solution. Stearic acid has been suggested in the literature as a suitable
material for coating aluminum. In this study, stearic acid, a saturated fatty
acid, was used to coat aluminum particles. Stearic acid is a good surfactant,
hydrophobic substance, and plasticizer. It is also a more environmentally
friendly substance compared to its counterparts. In this study, aluminum
particles were coated with stearic acid to increase the combustion efficiency of
Al particles. To make the coating, stearic acid was dissolved in ethanol and
mixed with Al particles. Then, the stearic acid coating was achieved by
self-assembly using the evaporation technique. As a result of experiments
conducted by adding aluminum and stearic acid-coated aluminum to diesel and
biodiesel blends, the thermal efficiencies of DAl200, DAl100, and DSA@Al100
fuels were 2.99%, 3.21%, and 4.59% higher than that of standard diesel fuel,
respectively. Likewise, the thermal efficiencies of B10D90Al200, B10D90Al100,
and B10D90SA@Al100 fuels were 2.73%, 2.99%, and 3.62% higher than that of
standard diesel fuel, respectively.
