Application of a Combustion Model to a Diesel Engine Fueled with Vegetable Oils

抄録

The paper presents the application of a three component model to the theoretical study of the combustion process of a Diesel engine fueled with sunflower oil and sunflower oil-Diesel fuel mixtures. The model assumes that the working fluid consists of three components: the fresh air, the flame and the burned gases.
The combustion model uses the energy conservation equation:
v_c·Q_c·dξ_α=dU_α+dL_α+dQ_wα, [1]
where v_c is the fuel cyclic dose, Q_c is the fuel heating value, ξ_α=v_cα/v_c, v_cα is the quantity of burned fuel up to the moment α, U_α is the internal energy of the working fluid, Q_wα is the heat exchanged through the cylinder walls and L_α is the mechanical work.
The heat release law was assumed to be a Vibe type one:
ξ_α=R_c·[1−exp(−6.9·A^m_P^p+1)]+(1−R_c)·[1−exp(−6.9·A^md+1)], [2]
where:
·A_p=(α−α_d)/(α_P−α_d) and A=(α−α_d)/(α_F−α_d);
·α_d-start of combustion angle;
·α_f-end of combustion angle;
·α_P-end of rapid combustion angle.
Using Eqs. [1] and [2] we have obtained the cylinder pressure during combustion, for the vegetable fuels taken into account; the peak values were confirmed during the experiments.