The paper presents the application of a three component model to the theoretical studs, 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. [1] upsilon(c)(.)Qc(.)dxi(alpha)=dU(alpha)+dL(alpha)+dQw(alpha). where upsilon(c) is the fuel cyclic dose, Q(c) is the fuel heating value, xi(alpha)=upsilon(calpha)/upsilon(c), upsilon(calpha) is the quantity of burned fuel up tu the moment alpha, U-a is the internal energy, of the working fluid, Q(walpha) is the heat exchanged through the cylinder walls and L-alpha is the mechanical work. The heat release law was assumed tu be a Vibe type one: [2] xi(alpha)=R-c(.)[1-exp(-6.9.A(P)(mp+1))]+(1-R-c)(.)[1-exp(-6.9(.)A(md+1))], where: A(P)=alpha-alpha(d)/alpha(P)-alpha(d) and A=alpha-alpha(d)/alpha(F)-alpha(d); alpha(d) - start of combustion angle; alpha(f) - end of combustion angle; alpha(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.
