Improving the Low-Temperature Properties of Fuels with the Addition of Rapeseed Oil for Tractor Diesels

Introduction: When using fuels with rapeseed oil (RSO) additives, it is necessary to comply with the conditions for ensuring uninterrupted fuel supply in accordance with the specified fuel supply law. Violation of this law leads to a violation of the process of mixing and combustion. The supply is influenced by the design of the power system; the operating conditions of the diesel engine and the physico-chemical properties of the fuels used, in particular, pumpability and filterability, which are more related to low-temperature properties. The main cause of violations in the fuel supply, especially during the passage of fuel filters, is the presence of a solid phase in the fuel of various origins. In the case of diesel fuel (DF) with RSO additives, filterability and pumpability deteriorate significantly, since RSO has a higher viscosity compared to DF. Materials and Methods: As the analysis of the available data has shown, the viscosity can be expressed by a polynomial dependence. By presenting the values of the empirical coefficients in the form of a matrix, it is possible to deter- mine their dependence on the concentration of the additive with an interval of varying the proportion of RSO in the fuel from 0 to 50%. Then you can get the viscosity equation depending on the fraction of RSO and the concentration of the additive DIFRON H372 in the fuel. Taking the partial derivative of viscosity from temperature, it is possible to determine the rate of change in viscosity depending on the temperature of the fuel with RSO additives and additives. To determine the maximum rate of increase in the viscosity of fuel with RSO additives, it is necessary to determine the extremum of this function by taking the second derivative. Equating the right part of the resulting expression to zero, determine the turbidity temperature. Results: As a result of the conducted studies, it was possible to determine the discrepancy between the experimental and the calculated values of the viscosity of the third degree polynomials, which did not exceed 3%. A graphical interpretation of the obtained dependence of viscosity on the fraction of RSO and the concentration of the additive DIFRON H372 in the fuel is presented. The turbidity temperatures of the mixture were determined depending on the fraction of RSO and the concentration of the additive in the fuel. Based on the calculated values obtained, a three- dimensional graph of the dependence of fuel turbidity temperatures on the fraction of RSO and the concentration of the DIFRON H372 additive is constructed. Discussion: To expand the limits of the use of fuels with RSO additives, a number of conditions must be met. First, ensuring the possibility of pumping fuel through the power supply system to ensure uninterrupted operation in a wide temperature range. Second, ensuring the filterability of the fuel for the possibility of its mechanical purification from all kinds of impurities in the same temperature range of operation as for pure diesel fuel. It is possible to provide these conditions for fuels with RSO additives by improving their low-temperature properties. There are two main ways to improve low-temperature properties with RSO additives. The first method consists in the fact that before adding RSO to DF, the necessary indicators of low-temperature properties are set and only after that does the process of its mixing take place. The second method boils down to the addition of various additives of a purposeful principle of action, which increase pumpability and, as a result, fluidity and filterability, thereby improving low-temperature properties. However, the effectiveness of these additives depends on their concentration in the fuel with RSO additives, its composition and the presence of surfactants in it. Conclusions: Calculations show that the fuel turbidity temperatures decrease from 279 to 270 K with a decrease in the RSO additive from 50 to 0% and an increase in the concentration of the DIFRON H372 additive from 0 to 2%. For the normal operation of a diesel engine at low temperatures on fuel with RSO additives, it is advisable to use the multi-functional additive DIFRON H372 at up to 2% in order to improve low-temperature properties.