Optimization of the main parameters of the diesel engine during its operation on the multicomponent biofuel composition

BACKGROUND: When conducting experimental studies aimed at finding optimal parameters of the diesel engine operating mode, as well as other objects, the issue of reducing the volume of the experiment becomes acute. The use of modern methods of planning, obtaining, processing and analyzing experimental data allows to reduce significantly the number of experiments conducted without notable loss of the reliability of the data obtained. AIMS: The aim of this study is to determine the optimal operating characteristics of the diesel engine, which uses the multi-component bio-fuel composition. METHODS: In order to determine the optimal values of the main parameters, affecting the effective indicators of the 4ChN 11.0/12.5 diesel engine when operating on the multicomponent biofuel composition and a mathematical description of their relationship, a second-order three-factor Box Benken plan was implemented. These factors are effective load, crankshaft rotational speed, and fuel injection advance angle. The diesel engine operation studies were performed on the most stable mixture of the multicomponent biofuel composition, including the following ingredients, wt %: rapeseed oil 34.5; ethanol 31.0; diesel fuel 34.5. The search of a compromise solution for the optimal combination of the levels of studied factors was performed with the method of superimposing of bidimensional sections of the response surfaces of the effective efficiency factor and the specific effective fuel consumption. RESULTS: Adequate models of second-order regression analysis of changes in effective efficiency factor and specific effective fuel consumption have been obtained. The factor space is described and grapho-analytical studies are carried out. The analysis of regression models and bidimensional sections of response surfaces allowed to determine the optimal values of the studied factors. The method for determining the optimal load and speed ranges of the diesel engine operation, using the multicomponent biofuel composition, has been optimized due to the application of the experimental plan and the description of the factor space by mathematical models, while number of experiments was reduced. CONCLUSIONS: The optimal area of the combination of the factors is in the range of varying the rotational speed of the diesel engine crankshaft n=1400...1550 rpm and the effective load Pe=0.68...0.85 MPa at the fuel injection advance angle Ѳinj=23.5 degrees to TDC. Considering the variable nature of the load and speed modes of a diesel engine in a real operation environment, the obtained data are of practical interest.