Heat release in a diesel engine operating on the gas fuel

The paper studies the combustion process that ensures operation of a tractor diesel engine with external mixture formation to determine type and proportion of the gas fuel added to the tractor diesel engine cylinders with fresh charge providing alteration in the mixture formation from internal to the external. To confirm reliability of the theoretical assumptions, the 4CHN 11.0/12.5 (D-245.5S2) diesel engine was experimentally studied on the RAPIDO SAK N679 load electric brake stand (Germany) with the 250 kW balancing pendulum machine and using specialized equipment for indexing. Alteration from the internal mixture formation in the tractor diesel cylinders to the external occurring at the constant diesel fuel injection rate was theoretically substantiated. For the given load-speed operation mode, the type of gas fuel was determined, i.e. the propane-butane mixture added to the main diesel fuel in an amount of 38% or more by weight. It was experimentally established that addition of up to 40% gas fuel to the diesel fuel completely eliminated the diffusion phase in the combustion process, which indicated transition of the diesel engine operation from the internal mixture formation to the external.