Numerical injection characteristics analysis of various renewable fuel blends

This paper deals with the numerical analysis of the influence of bioethanol addition to diesel and biodiesel fuel on the injection process. The considered fuels are; neat mineral diesel, neat biodiesel from rapeseed oil, and bioethanol–diesel and bioethanol–biodiesel blends up to 15% bioethanol concentration (v/v) with an increment of 5%. The flow through a single assembly to one cylinder is investigated numerically by using a one-dimensional mathematical model. The fuels are experimentally investigated in a fuel injection M system at full load (FL), at several pump speeds (1100, 800 and 500 rpm), and at ambient temperature in order to verify the mathematical model. On the basis of the numerical results, the influence of bioethanol addition to diesel and to biodiesel fuel on the injection characteristics, especially on fuelling, injection timing, injection duration, mean injection rate, and maximum injection pressure, is investigated in view of harmful emission reduction. It has been shown that the determined empirical expressions for density, sound velocity and bulk modulus enable satisfactory numerical modeling of the injection process for all tested fuels. The numerically obtained characteristics were generally in good agreement with the experimental ones. The analysis of numerical results shows that for all operating regimens simulated, the addition of bioethanol to biodiesel and to diesel reduces fuelling, injection timing, injection duration, mean injection rate and maximum injection pressure.