The vegetable oil is an alternative fuel that complements or substitutes for fossil fuels. However, its use in diesel engines gives rise to a number of difficulties, especially at low engine power levels. To resolve these problems, improving the thermal conditions in the engine's combustion chamber is one of the solutions being considered. This study presents the performance and combustion parameters of a LISTER type indirect injection diesel engine incorporating a KALAMA screw (an adaptation of the engine's pre-chamber screw with a "hot spot") and using vegetable oils. The results obtained were compared with those obtained by operating the engine on diesel and oil, this time without the KALAMA screw. The results show an improvement in engine performance (specific consumption, thermal efficiency and exhaust gas temperature), particularly at low load. The reduction in excess fuel consumption (with the KALAMA screw) is of the order of 12% at loads of 13% and 26% of maximum engine power. The ignition delay and combustion times of Jatropha oil are better than, or even similar to, those obtained with diesel. The combustion phenomenology is modified by the use of the KALAMA screw. On the heat release rate curves, there was no peak in the kinetic combustion phase during the tests with the modified screw. On the other hand, the diffusion phase was comparable for all the tests. Evaluation of cyclic dispersion using the COVIMEP study shows an improvement in the regularity of combustion cycles in this type of engine incorporating the KALAMA screw.

Indirect Injection, Pre-Chamber Screw, KALAMA Screw, Hot Spot