Currently, biofuels represent a solution for the European Union in the transportation sector in order to reduce the greenhouse gas (GHG) emissions and the dependency of fossil fuels. Biodiesel from vegetable oils is a solution for countries with low GDP per capita to strengthen the internal agriculture, provide jobs, and reduce the use of fossil fuels. In this study, we model and simulate a temperature regulator designed for the biodiesel transesterification process in a discontinuous batch reactor, using methanol and a homogenous basic catalyst. The simulation was based on the kinetical model of the transesterification reaction and the mathematical model of the reactor. We considered molar ratios of alcohol/oil of 6:1 and 9:1, respectively, to shift the reaction equilibrium towards the production of fatty acid methyl esters. In the design of the simulation, the methanol boiling point was considered a restriction, therefore, temperatures below 65 °C were imposed. The results demonstrate that the increase in temperature results in a decrease in the reaction time and a higher yield, especially for the 6:1 molar ratio reaction, and that the optimum temperature for the batch reactor is of 60 °C. Automatic control improves the performance and costs of production.

This study evaluates the performance and emissions characteristics of a compression ignition engine fueled with biodiesel blends derived from used cooking oil (UO) and sunflower oil (SF) at concentrations of 5%, 10%, 20%, and 50%. Tests were conducted under different load conditions (20%, 50%, and 100%) across engine speeds ranging from 1500 to 3600 rpm, focusing on effective power, torque, brake specific fuel consumption (BSFC), and emissions of NOx, CO, HC, particulate matter (PM), smoke, and CO₂. Consistent engine operating conditions were maintained for all fuel blends. The results indicated that increasing the biodiesel concentration led to a decrease in brake power and torque—up to 3.18% reduction for SF50 compared to diesel—due to the lower calorific value of biodiesel. For SF biodiesel, the BSFC increased with higher biodiesel content, while for UO biodiesel the results varied across concentrations. Emissions analysis revealed lower CO and HC at 2500 rpm for all biodiesel blends relative to diesel, while NOx emissions varied depending on fuel type and concentration. In terms of particles, both PM and smoke were measured, and while PM showed different results across blends, smoke was lower for all blends compared to diesel. Our overall analysis shows that biodiesel blends up to 20% can be effectively used in diesel engines without substantial modifications, offering a balance between performance and reduced emissions.

In general, the efficiency of the currently used aftertreatment solutions is strongly conditioned by the temperature of the exhaust gases. The regeneration capability of the aftertreatment equipment can be improved by intentionally rising the temperature of the exhaust gases. When using technologies like hybrid transmission, engine Start/Stop and cylinder deactivation, the temperature must be also intentionally increased in order to assure a high conversion rate. This paper presents the experimental research regarding to the effects of changing some engine parameters on exhaust gases temperature and performances of a compression ignition engine. The values of these parameters were modified as follows: the coolant temperature was modified 4 times (60, 70, 80 and 90 °C), the injection timing was modified 5 times (25, 20, 15, 10 and 5 °CA before top dead center), the injection strategy was changed 3 times (main injection, one and two pre-injection) and engine speed was modified in the range 1800-2800 rpm. The number of injections and the thermal regime modify the least temperature of the exhaust gases, with values of up to 44 °C. Yet, by the modification of the load, speed and of the injection advance greater temperature of the exhaust gases variations with values of up to 95°C.

The overwhelming parts of the modern Diesel engines for vehicles are supercharged. However, the supercharging process lead to generating a significant amount of NOx emissions. Therefore, the supercharging intensity may be intentionally limited in order to avoid increasing NOx emissions excessively, as these emissions are drastically limited by the Euro 6 pollution standard. By moving from Euro 5 to Euro 6, the NOx emission's permissible limits have been reduced by up to 80%. These reductions of NOx emissions were made possible mainly due to the utilization of the some conventional equipment and procedures presented in the paper. Diesel engine's supercharging could be realized efficiently also with pressure wave compressor (PWC). The paper highlights the possibility of realizing the EGR process directly through the PWC. The concept of supercharging with PWC leads to a significant reduction of NOx, for a significant increase of both the pressure and temperature of the intake air.