City buses are one of the main means of public transport in cities. As they move in a limited and densely populated area and are intensively exploited, it is particularly important that they are environmentally friendly. There are many ways to reduce emissions from city buses, including the use of hybrid propulsion. Another way is to use low-emission fuels. This article presents the results of the emission tests of an 18 m articulated city bus with a serial hybrid drive fuelled comparatively by conventional diesel fuel and oxygenated fuel containing 10% v/v of triethylene glycol dimethyl ether (TEGDME). The emission tests were carried out during the actual operation of the bus on a route in Poznań (Poland) and over the SORT cycles. The obtained test results were compared also with the results obtained for a conventional bus. The reduction in emissions of some exhaust components was found when the hybrid bus was fuelled with oxygenated fuel during its actual operation on the bus route. There was a reduction in CO emissions by ~50% and NO_x emissions by ~10%. Almost identical levels of PM and HC emissions and smoke opacity were observed for both fuels. In the SORT cycles, the differences in the emissions obtained for both types of fuel were small. In general, for the hybrid bus, a lower influence of oxygenated fuel on emissions was recorded than for the conventional bus.

Ethyl alcohol is a known additive to automotive gasoline. In commercially available gasolines, its concentration is between 5 and 10%. Since ethyl alcohol can be considered as a renewable fuel, efforts are being made to further increase its content in gasoline. This article describes the results of comparison experiments on a Euro 5 direct injection spark-ignition car engine fueled with conventional gasoline and gasoline with 30% v/v ethyl alcohol content (E30). The test results showed that a significant share of ethanol in the fuel did not affect most of the regulated emissions of gaseous components (namely: CO, HC, NO), i.e., a three-way catalyst effectively removed these components, regardless of the fuel composition. Slightly lower CO₂ emissions with the E30 fuel were noticeable. A significant difference, however, in lower particulate number emissions for the fuel with high-ethanol content was seen. At high engine load, the use of the E30 fuel resulted in a tenfold reduction in particulate number emissions. This might be considered as a very valuable effect of ethanol since direct injection spark-ignition engines are typically characterized by higher particulate emissions compared to engines equipped with other types of injection systems.

Acoustic and vibration signals taken from engine often provide significant dynamic information on mechanical and thermodynamic system conditions. The failure characteristics with its quantity description point at the nature and intensity of an incorrectness during normal engine operation, giving the basic principles for more accurate process run monitoring and recognition of fault sources influenced on combustion process run.

This article presents the possibility of improving combustion using the effect of releasing hydrogen from a solution with nucleation of gas bubbles. This concept consists in dissolving hydrogen in diesel fuel until the equilibrium state of the solution is reached. At a later stage, the phenomenon is reversed, and this gas is released from the solution during its injection into the combustion chamber with a strong swirl. A characteristic feature of the solution is that when lowering the pressure (opening the atomizers), there is a decrease in the equilibrium thermodynamic potential, which results in the excess, dissolved hydrogen being released spontaneously, and this process is of a volumetric nature. This article is a continuation of the work carried out at Poznan University of Technology on the development of this concept. This article presents the results of tests for the impact of hydrogen dissolved in diesel fuel on the combustion process within a turbulent-flow environment. The tests were conducted in the combustion chamber of an engine equipped with a toroidal combustion chamber and direct injection. During the tests, the following factors were measured: the main indicators of motor operation, emission of hydrocarbons, carbon monoxide, nitrogen oxides, and particulate matters.

The scientific issues that are the subject of this article are related to the assessment of the vibration damping efficiency of an aircraft engine installed on a test stand for the type of vibration isolator used. For this purpose, appropriate empirical tests were carried out on an aircraft...