Introduction (problem statement and relevance). Today, vegetable oils, in particular, rapeseed oil (RO) are widely used types of fuels for diesel engines. The main physicochemical properties of RO are somewhat similar to diesel fuel (DF). However, one can highlight a large fraction of the oxygen content in it, which affects the fuel combustion intensity in diesel cylinders. In this regard, the addition of rapeseed oil is very important to optimize the composition of mixed fuel (MF) for its use in diesel engines. The purpose of the study was optimizing the MF composition and obtaining experimental data of diesel engine effective performance by means of regression analysis.Methodology and research methods. To optimize the MF composition studies were carried out to determine the relative fractions of carbon, hydrogen, oxygen in RO and MF, as well as bench tests of diesel fuel and MF with various RO additives operation, followed by the regression analysis of effective indicators.Scientifi c novelty and results. The effective performance dependences of the diesel engine on the RO content in the MF have been determined. Basing on the obtained load characteristics of the diesel engine, it was concluded that an increase in the average effective pressure from 0.2 to 1.2 MPa, as well as in the share of RO in MF from 0 to 80%, would lead to an increase in the effective specifi c fuel consumption to 383–506 g/kW·h and the decrease in effective effi ciency by 14–28%. On the basis of the regression analysis the maximum values of the optimality criterion indicators D-optimum = 0.98–1.0 with the addition of RO to MF from 45 to 50% were determined.Practical signifi cance. The value of the maximum permissible composition of MF, consisting of 50–55% of diesel fuel and 45–50% of RO and ensuring maximum compliance with the specifi ed conditions of optimality on the diesel engine under consideration has been obtained.

Introduction. The relevance of the study is determined by the need to estimate the influence of mixed fuel, including diesel and biofuel (rapeseed oil), on ecological parameters of an agricultural tractor diesel in working in agricultural fields and transporting. The objective of the study is forecasting, obtaining and comparing the calculated and experimental environmental performance indicators of the Belarus-922 tractor diesel engine using mixed fuel for farming operations. Materials and Methods. To achieve the objective of the study, the quantitative indicators of component structure of rapeseed oil samples of various origins have been defined, a theoretical estimation and the comparison of calculated and experimental environmental performance indicators of tractor diesel engine have been made with the use of the necessary equipment. Results. For the first time, quantitative values of indexes of the component composition of rapeseed oils of various origins have been obtained. The analysis has shown that the most recommended to be used as fuel is the sample with the maximum content of unsaturated acids that will allow providing the maximum speed and combustion efficiency. The calculations show a decrease in working temperature by 200 K as a result of added rapeseed oils that should lead to a reduction of the constant of the reaction speed and concentration of nitrogen oxides approximately by a factor of 2.7. The endogenous origin of nitrogen compounds influences essentially on the concentration of nitrogen oxides in worked-out gases. Discussion and Conclusions. Based on the analysis of nitrogen oxide mechanisms on combustion of rapeseed oils, the calculation of the semi-quantitative reaction rate is theoretically proved and experimentally confirmed.

Íà ñåãîäíÿøíèé äåíü ñâîéñòâàìè ðàïñîâîãî ìàñëà, âëèÿþùèìè íà ïðîöåññû òîïëèâîïîäà÷è â òðàêòîðíîì äèçåëå, ÿâëÿþòñÿ ïëîòíîñòü, êèíåìàòè÷åñêàÿ è äèíàìè÷åñêàÿ âÿçêîñòü, à òàêaeå ïîâåðõíîñòíîå íàòÿaeåíèå. Öåëüþ íàñòîÿùèõ èññëåäîâàíèé ÿâëÿåòñÿ ðàñøèðåíèå ïðåäåëîâ òîïëèâíîé áàçû òðàêòîðíûõ äèçåëåé ïóòåì ïðèìåíåíèÿ ñìåñåâûõ òîïëèâ ñ íåäîñòàòî÷íûìè íèçêîòåìïåðàòóðíûìè ñâîéñòâàìè.  ñâÿçè ñ ýòèì îïðåäåëåíèå îïòèìàëüíîãî ñîñòàâà ñìåñåâîãî òîïëèâà äëÿ ðàáîòû òîïëèâîïîäàþùåé àïïàðàòóðû òðàêòîðíûõ äèçåëåé ÿâëÿåòñÿ âåñüìà àêòóàëüíîé çàäà÷åé. Äëÿ åå ðåøåíèÿ áûëè ïðîâåäåíû òåîðåòè÷åñêèå èññëåäîâàíèÿ ïî îïðåäåëåíèþ âëèÿíèÿ äîáàâîê ðàïñîâîãî ìàñëà íà ñâîéñòâà ñìåñåâîãî òîïëèâà, à òàêaeå èñïûòàíèÿ äèçåëüíîé òîïëèâíîé ôîðñóíêè.  ðåçóëüòàòå èññëåäîâàíèé áûëè îïðåäåëåíû çàâèñèìîñòè âÿçêîñòè ñìåñåâîãî òîïëèâà, äàâëåíèÿ íà÷àëà âïðûñêèâàíèÿ, ãåðìåòè÷íîñòè ïî çàïèðàþùåìó êîíóñó è ãèäðîïëîòíîñòè ðàñïûëèòåëÿ ôîðñóíêè îò äîáàâêè ðàïñîâîãî ìàñëà c ïðèñàäêîé. Íà îñíîâàíèè òåîðåòè÷åñêèõ ðàñ÷åòîâ ïîëó÷åíî çíà÷åíèå âÿçêîñòè ñìåñåâîãî òîïëèâà, óäîâëåòâîðÿþùåé òðåáîâàíèÿ ÒÓ çàâîäà-èçãîòîâèòåëÿ äëÿ òîïëèâíûõ ôîðñóíîê. Àíàëèç ýêñïåðèìåíòàëüíûõ çàâèñèìîñòåé ïîêàçàë, ÷òî ïðè óâåëè÷åíèè äîëè ðàïñîâîãî ìàñëà â ñìåñåâîì òîïëèâå 0 äî 100 % óâåëè÷èëèñü: äàâëåíèå íà÷àëà âïðûñêèâàíèÿ ñ 20,88 äî 21,08 ÌÏà, âðåìÿ äî îòðûâà êàïëè òîïëèâà îò íîñèêà ðàñïûëèòåëÿ ñ 18 ñ äî 104 ñ, à âðåìÿ ñíèaeåíèÿ äàâëåíèÿ óìåíüøèëîñü ñ 5,2 äî 11,3 ñ. Èñïûòàíèÿ ïîêàçàëè, ÷òî íà âñåõ ñîñòàâàõ ñìåñåâîãî òîïëèâà äàâëåíèå íà÷àëà âïðûñêèâàíèÿ, ãåðìåòè÷íîñòü ïî çàïèðàþùåìó êîíóñó, ãèäðîïëîòíîñòü ðàñïûëèòåëåé è ïîäâèaeíîñòü èãëû ðàñïûëèòåëÿ ñîîòâåòñòâóþò òðåáîâàíèÿì ÃÎÑÒ 10579-2017, îäíàêî êà÷åñòâî ðàñïûëèâàíèÿ ñîîòâåòñòâóåò íà ñîñòàâàõ ñìåñåâîãî òîïëèâà ñ äîëåé ðàïñîâîãî ìàñëà äî 60 %. Òàêèì îáðàçîì, ïðèìåíåíèå ïðåäëîaeåííûõ ñîñòàâîâ òîïëèâ ïîçâîëèò óëó÷øèòü íèçêîòåìïåðàòóðíûå ñâîéñòâà ñìåñåâîãî òîïëèâà ñ äîáàâêàìè ðàïñîâîãî ìàñëà, à çíà÷èò, ðàñøèðèòü òîïëèâíóþ áàçó òðàêòîðíûõ äèçåëåé. Êëþ÷åâûå ñëîâà: ñìåñåâîå òîïëèâî, ðàïñîâîå ìàñëî, ñòåíäîâûå èñïûòàíèÿ. Today, the properties of rapeseed oil, affecting the fuel supply processes in a tractor diesel, are density, kinematic and dynamic viscosity, as well as surface tension. The purpose of this research is to expand the limits of the fuel base of tractor diesel engines by using mixed fuels with insufficient low-temperature properties. In this regard, the determination of the optimal composition of mixed fuel for the operation of the fuel supply equipment of tractor diesels is a very urgent task. To solve this problem, theoretical studies were conducted to determine the effect of rapeseed oil additives on the properties of mixed fuels, as well as testing a diesel fuel injector. As a result of the studies, the dependences of the viscosity of the mixed fuel, the pressure of injection beginning, the tightness of the locking cone, and the hydro-density of the spray nozzle on the addition of rapeseed oil with an additive were determined. Based on theoretical calculations, the value of the viscosity of mixed fuel that meets the requirements of the ...

The use of rapeseed oil (RO) in tractor engines and other agricultural machinery in its pure form or a mixture of RO with diesel fuel (DF) imposes a number of limitations associated with some dif-ference in physical and chemical properties. Therefore, the most promising is the use of mixed fuel (MF) consisting of DF and RO. The purpose of these studies is to determine the optimal composi-tion of the MF, consisting of DF and RM by optimizing the approximated dependences of the envi-ronmental indicators of a diesel engine. To solve this problem, bench tests of the operation of the D-245.5S diesel engine (4ChN 11.0 / 12.5) were carried out. The following determined environmental performance indicators of a diesel engine are selected: soot (С), nitrogen oxides (NOx), unburned hydrocarbons (CxHy), carbon dioxide (CO2) and carbon monoxide (CO). The studies were carried out on various compositions of MF, consisting of 80% DF and 20% RO, 55% DF and 45% RO, 20% DF and 80% RO by weight, respectively. As a result of the bench tests, two load characteris-tics were obtained, the one at a speed of n = 1400 min-1 corresponding to the value of the maximum torque, and the second at a speed of n = 1800 min-1 corresponding to the value of the rated power, as well as the external speed characteristic of the D-245.5S tractor diesel engine (4ChN 11.0 / 12.5). The analysis of the obtained experimental data revealed the dependence of environmental indicators on the rotational speed of the diesel engine crankshaft, the average effective pressure and the addi-tion of RO in MF by weight. Using the least squares method, the approximated mathematical de-pendences of the ecological indicators of a diesel engine are determined. The analysis of the ob-tained dependencies showed that: the increase in the crankshaft speed n, the proportion of RO in MF and a decrease in the average effective pressure pe, leads to a decrease in soot С to 4.0%, nitro-gen oxides NOx to 100.0 ppm, unburned hydrocarbons CxHy to 1.0 ppm, carbon dioxide, CO2 up to 2%, and an increase in carbon monoxide CO up to 0.16%. As a result of solving the obtained system of equations for the approximated dependences of environmental indicators, the optimal addition of RO to MF of up to 35% by weight was determined.