Newswise — RUDN engineers adjusted the operation of a diesel engine running on rapeseed oil. Typically, the second fuel reduces engine performance, but the authors explained how to adjust it so that vegetable and diesel fuels come close in performance. The results were published in the E3S Web Conf.

It is possible to convert a regular diesel engine to vegetable oil, but this will change many features of its performance. For example, the oil is denser and less volatile - this significantly affects fuel injection and the formation of a combustible mixture. RUDN engineers compared how an engine operates on conventional diesel fuel and rapeseed oil. The authors also figured out how to adjust the engine so that the oil's performance characteristics are closer to those of conventional fuel.

“Modern internal combustion engines face the challenge of achieving more environmentally friendly performance. To reduce the toxicity of exhaust gases, they are trying to use alternative fuels, including biofuels. Among them, vegetable oils and their derivatives should be highlighted,” Pablo Vallejo, PhD, Associate Professor of the Department of Power Engineering at RUDN University said.

For the experiment, engineers studied a high-speed small-sized diesel engine of the MD-6 type. It is used, for example, in agricultural machinery. First, the authors compared engine operation on regular diesel fuel and rapeseed oil, discovering the “weak points” of vegetable fuel. After analyzing them, engineers experimentally determined how the engine should be adjusted to minimize differences in engine performance on different fuels.

When converting an engine from diesel fuel to rapeseed oil, the quality of fuel supply and atomization deteriorates. This leads to an increase in specific fuel consumption, deterioration of smoke, and emissions of nitrogen oxides and carbon monoxide.

RUDN engineers found that these negative phenomena can be partially eliminated - to do this, it is necessary to adjust the fuel injection advance angle and optimize the fuel supply system. With these measures, rapeseed oil achieves the characteristics of diesel fuel. One can also improve engine performance by mixing different types of biofuels.

“In addition to adjusting the fuel injection advance angle, you can optimize the fuel supply system. In particular, the geometry of the flow part of the nozzle. Significant potential for improvement is also provided by the transition from pure rapeseed oil to biofuel mixtures and optimization of their composition,” Pablo Vallejo, PhD, Associate Professor of the Department of Power Engineering at RUDN University said.