Wojciech Cieślik

Thermodynamical evaluation of usefulness of future hydrocarbon fuels for use in compression ignition engines

AbstractThe paper discusses the issues of the influence of the fuel spray formation on the generation of self-ignition spots and the development of pre-flame processes in the cylinder of a model diesel engine. The investigations were carried out for a standard diesel fuel and two other types of fuel that were mixtures of ethanol, butanol, and diethylether in a variety of proportions. By applying optical methods of analysis, the authors determined the geometrical indexes of the injected fuel spray as well as fuel mass distribution in the longitudinal and transverse cross section of the fuel spray during the injection process. The location and number of the self-ignition spots in the combustion chamber were evaluated on the basis of a comparison under various conditions: in presence of the charge swirl and at the lack of it. Research conducted for the single-cylinder engine confirmed the possibility of the use of diesel-like fuels for compression ignition engines.

Thermodynamic analysis of indexes of operation of the engine with direct fuel injection for idle speed and acceleration

Contemporary requirements for combustion engines are aimed mainly at obtaining significant parameter values of their operation at simultaneously low fuel consumption and reduced exhaust emission. Despite the fact that combustion engines utilize diverse load conditions, the idle speed share in the whole range of their operation is significant. The percentage of combustion engines with spark-ignition direct injection (SI DI) in the total number of spark-ignition engines is increasing. It means that the method of the mixture preparation is an important factor in SI DI engine, also for idle speed. In the tests was analysed the SI engine preparing the mixture with a dose of injected fuel (air-guided type) in conditions of the idle speed. Idle speed control is a critical issue in engine control fields. Essentially, it is a highly nonlinear and time-varying problem. Its performance has a significant impact on fuel economy and emission levels. The engine operation indexes were determined, and with the use of coefficient of variation, the variation of the cycle was estimated. Article contains the three-stage division, taking into account the variable measuring modes where was analysed the work condition during the idling, free acceleration of combustion engine and car acceleration. From numerous operational indexes of the engine operation were selected those, which in the best way characterize engine operation for idle speed.

Thermodynamic indexes of real driving conditions of gasoline and LPG fuelled engine

The aim of the conducted tests was to assess the method of delivering additional fuel dose in transient conditions and to determine the impact of this additional fuel dose on the engine operation conditions. The experimental tests were conducted in typical urban driving conditions. In the study was used system for indicating and acquisition of fast-varying data; the combustion pressure in the first cylinder of the 3-cylinder engine with spark ignition was measured, as well as the voltage on the petrol injectors and the liquefied petroleum gas injector. The post-processing analysis enabled defining engine operation indexes taking into account the aforementioned parameters. Also indicated mean effective pressure, the heat release rate and the amount of the heat released were analysed. In addition, the indexes of transient conditions of engine operation per one cycle were specified: change of the engine speed, of the maximum combustion pressure, of the indicated mean effective pressure and change of the heat release rate.