Method and device for the use of biodiesel in internal combustion engines with diesel cycle

A method for using biodiesel fuel in compression ignition internal combustion engines (2), the biodiesel fuel being present in a light oil diesel biodiesel blend with a percentage of biodiesel greater than 7%, in which the percentage of biodiesel higher than 7% causes an increase in a viscosity of the mixture, the increase in viscosity negatively affecting the cold start of the engine (2), the method comprises reducing the biodiesel concentration in the starting phase of the engine (2), the concentration reduction being obtained by adding light oil diesel to the light oil diesel-biodiesel blend using a mixing valve (8) or by using only light oil diesel using a diverter valve (8a);

• wherein the blend, made up of light oil diesel and biodiesel with a percentage of biodiesel in an amount up to 100%, is contained in a main tank (5);
• wherein the light oil diesel is contained in an auxiliary tank (7);
• wherein the blend is sent to a small and heated tank (6) by means of a first low pressure pump (5a);
• and
• wherein a second and third low pressure pump (6a, 7a) pump, respectively, the blend of light oil diesel-biodiesel from the heated tank (6) and the light oil diesel from the auxiliary tank (7) towards the mixing valve (8) or the diverter valve (8a), thus preparing the blend that will feed the diesel engine (2) through a high pressure pump (9).