Droplet Combustion Characteristics of Biodiesel–Diesel Blends using High Speed Backlit and Schlieren Imaging

Abstract

This work investigates the effect of blending biodiesel with diesel on the combustion of an isolated fuel droplet. Biodiesel blends substituting diesel oil in different concentrations on volumetric basis, in addition to neat diesel and biodiesel were studied. High speed schlieren and backlighting imaging techniques have been used to track droplet combustion. The results showed that partial substitution of diesel oil by biodiesel at the test conditions led to increasing secondary atomization from the droplet, compared to neat diesel or biodiesel fuel droplets. This in turn enhances evaporation, mixing, and then combustion. Additionally, the results showed that biodiesel has a higher burning rate compared to diesel, and that increasing biodiesel in the blend increases the burning rate of the blend. Nucleation has also been traced to take place inside the droplets of the blends. Moreover, flame size (height and width) has been reduced by increasing biodiesel concentration in the blend.

Analysis on Evaporation Characteristics of Palm Oil Biodiesel using a HSDT Method

“…The wall temperature, the design of the fuel injector nozzle, the use of lubricants, and the kind of fuel itself are just a few of the variables that may have a significant impact on deposit development inside the combustion chamber of real engines. Other than that, Faik et al, [19] also stated that the amount of biodiesel in the blended mixture affects the biodiesel-neat diesel blend fuel evaporation characteristics, such as the evaporation lifetime. This suggests that because biodiesel burns more quickly than base diesel, adding it will result in greater fuel usage.…”

The Effect of Blended Palm Oil Biodiesel Droplet Properties on Evaporation Characteristics

“…Fuel properties have significant impacts on the evaporation characteristics of its droplet on a heated surface. The biodiesel-neat diesel blend fuel evaporation characteristics such as the evaporation lifetime are determined by the percentage of biodiesel in the blended mixture [11]. This implies that adding biodiesel to base diesel will increase fuel consumption due to the increased combustion rate.…”