This paper presents a comparative analysis of the diesel engine performance and emission characteristics, when operating on diesel fuel and various diesel-biodiesel (B10, B20, B40, B60) blends, at various loads and engine speeds. The experimental tests were performed on a four-stroke, four-cylinder, direct injection, naturally aspirated, 60 kW diesel engine D-243. The in-cylinder pressure data was analysed to determine the ignition delay, the Heat Release Rate (HRR), maximum in-cylinder pressure and maximum pressure gradients. The influence of diesel-biodiesel blends on the Brake Specific Fuel Consumption (bsfc) and exhaust emissions was also investigated. The bench test results showed that when the engine running on blends B60 at full engine load and rated speed, the autoignition delay was 13.5% longer, in comparison with mineral diesel. Maximum cylinder pressure decreased about 1-2% when the amount of Rapeseed Methyl Ester (RME) expanded in the diesel fuel when operating at full load and 1400 min -1 speed. At rated mode, the minimum bsfc increased, when operating on biofuel blends compared to mineral diesel. The maximum brake thermal efficiency sustained at the levels from 0.3% to 6.5% lower in comparison with mineral diesel operating at full (100%) load. When the engine was running at maximum torque mode using diesel -RME fuel blends B10, B20, B40 and B60 the total emissions of nitrogen oxides decreased. At full and moderate load, the emission of carbon monoxide significantly raised as the amount of RME in fuel increased.

The paper presents the experimental test results reflecting the comparative changes in the performance efficiency and emissions of the exhaust of a naturally aspirated, four-stroke, single-cylinder, air-cooled diesel engine due to its transition from neat rapeseed oil biodiesel to fuel blends prepared by mixing in various proportion (by volume) rapeseed methyl ester (B) and butanol (Bu). The lubricity properties of biodiesel-n-butanol fuel blends were studied using HFRR method. In contrast to previous works, the undertaken investigation is performed with a totally renewable, binary liquid biofuel blends. The purpose of the research is to reduce simultaneously the production of NOx emissions and the exhaust smoke with respect to neat biodiesel due to potentially improved homogeneity of combustible mixture and particulate matter emissions benefits suggested by the higher oxygen content (21.62wt%) and the relatively lower carbon-to-hydrogen ratio (4.8) of the normal n-butanol. The tests revealed that the brake specific fuel consumption for the binary biodiesel-n-butanol fuel blends is always higher than that neat biodiesel produces under the same loading conditions. Maximum nitrogen oxide (NOx) emissions were obtained with the engine running on neat biodiesel (2290 ppm). At full (100%) load conditions, the lowest NOx emission was obtained with the engine running on a biofuel BBu20 blend. The lowest level of carbon monoxide emissions (CO) was observed, when engine running with the most butanol-oxygenated biofuel blend BBu20.The highest smoke opacity of the exhaust was obtained when the engine was fuelled with neat biodiesel and at full load.

Abstract. This paper presents a comparative experimental study for determining the effect of ethanol on functionality of a high pressure pump of the common rail fuel injection system. For experimental durability tests were prepared two identical fuel injection systems, which were mounted on a test bed for a fuel injection pump. One of the fuel injection systems was feed with diesel fuel; other fuel injection system was fuelled with ethanol-diesel fuel blend. A blend with 12% v/v ethanol and 88% v/v diesel fuel and low sulphur diesel fuel as a reference fuel were used in this study. To determine the effect of ethanol on the durability of the high pressure pump total fuel delivery performance and surface roughness of pump element were measured prior and after the test. Results show that the use of the ethanol-diesel blend tested produced a negative effect on the durability of the high pressure fuel pump. The wear of plungers and barrels when using ethanol-diesel fuel blend caused a decrease in fuel delivery up to 30% after 100 h of operation.

Abstract. The limited fossil fuel reserves and the ecological aspects encourage the scientists to conduct the research on a new alternative renewable energy resource. In the European Union diesel -powered transport machines produce approximately 21 % of the total emissions causing the greenhouse effect and this tendency is in a constant progress. The transport and agriculture sectors are among the largest consumers of the mineral fuels contributing to the environment pollution. The EU directives promote the production and consumption of biofuels, therefore, the member-states have committed to the promotion of biofuels and other renewable fuels instead of using fossil-origin gasoline or diesel fuel. The article presents the experimental test results of the fuel injection processes of diesel and biodiesel fuel blends, when using high-pressure common rail injection system. The injection characteristics were determined using the injection rate measuring instrumentation. The aim of the study was to get insight in the changing behaviour of the injection rate, amount of the fuel injected per cycle, actual injection delay and the duration of the process over the whole variation range of both the injection pressure and the energizing time. The test results showed that the maximum injection rate of diesel -biodiesel fuel blends was lower than that of a neat diesel fuel case. It was observed that density and viscosity of the fuel have a significant effect on the form of injection characteristics. The injection process has significant influence on the combustible mixture formation inside the cylinder of a diesel engine, auto-ignition, combustion, and exhaust emissions.

The paper presents the experimental test results reflecting the comparative changes in the performance efficiency and emissions of the exhaust of a normally aspirated, four-stroke, single-cylinder, air-cooled diesel engine F1L511 occurring due to its transition from neat rapeseed oil biodiesel to operation on renewable fuel blends prepared by mixing in various proportion (by volume) rapeseed methyl ester (RME) and butanol (B). In contrast to previous works, the undertaken investigation was performed with totally renewable binary liquid fuel blends. The purpose of the research was to reduce the production of both exhaust smoke and NOx emissions with respect to neat biodiesel due to potentially improved homogeneity of combustible mixture and particulate matter emissions benefits suggested by the higher oxygen content (21.62 wt %) and the relatively lower carbonto-hydrogen ratio (4.8) of butanol. The three renewable fuel blends B5, B10 and B15 were prepared by mixing 95 vol. % RME/5 vol. % B, 90 vol. % RME/10 % B and 85vol. % RME/15vol. % B, respectively. It was found that the brake specific fuel consumption for the tested biodiesel-butanol fuel blends was always higher than that measured under the same operating conditions with neat biodiesel. The lowest level of carbon monoxide emissions (CO) was also measured with the same biofuel blend B15 at medium (50 % of full) load. While the production of maximum NO x emissions from combustion of blend B15 was 0.6 % lower than that experienced with neat biodiesel under the same test conditions. It is important to note that the lower NO x emissions have been accompanied by the lower smoke opacity from combustion of the most butanol-oxygenated fuel blend B15. Thus, the most problematic issue related with the reduction of both the NO x emissions and the smoke opacity (PM) can be solved quite easy by using for diesel engine powering totally renewable biodiesel-butanol fuel blends.