Andrzej Ambrozik, Dariusz Kurczyński and Piotr Łagowski
Modern means of transport are basically powered by piston internal combustion engines. Increasingly rigorous demands are placed on IC engines in order to minimise the detrimental impact they have on the natural environment. That stimulates the development of research on piston internal combustion engines. The research involves experimental and theoretical investigations carried out using computer technologies. While being filled, the cylinder is considered to be an open thermodynamic system, in which non-stationary processes occur. To make calculations of thermodynamic parameters of the engine operating cycle, based on the comparison of cycles, it is necessary to know the mean constant value of cylinder pressure throughout this process. Because of the character of in-cylinder pressure pattern and difficulties in pressure experimental determination, in the present paper, a novel method for the determination of this quantity was presented. In the new approach, the iteration method was used. In the method developed for determining the volumetric efficiency, the following equations were employed: the law of conservation of the amount of substance, the first law of thermodynamics for open system, dependences for changes in the cylinder volume vs. the crankshaft rotation angle, and the state equation. The results of calculations performed with this method were validated by means of experimental investigations carried out for a selected engine at the engine test bench. A satisfactory congruence of computational and experimental results as regards determining the volumetric efficiency was obtained. The method for determining the volumetric efficiency presented in the paper can be used to investigate the processes taking place in the cylinder of an IC engine.
Kazimierz Lejda, Dariusz Kurczyński, Piotr Łagowski, Michał Warianek and Tomasz Dąbrowski
The article describes the test results of the uniqueness of the work cycle of two-cylinder internal combustion piston FIAT 0.9 TwinAir engine, while being powered by 95 octane petrol fuel and LPG gas. The engine was working according to load characteristics. The engine mounted on the test bench was equipped with a sequential LPG gas fuel supply system. The gas fuels differ significantly from the petrol fuels in their physiochemical properties. In order to rationally utilize gas fuels to power internal combustion engines, the knowledge about basic fuel burning process of these fuels is required. The article shows the analysis of individual engine work cycles of the technologically advanced engine in order to evaluate the influence of powering by LPG gas fuel on the rate of uniqueness of its work cycles. The measure of uniqueness of the inter-cylinder processes are the work cycle uniqueness indicators, which are as follows: the maximum work cycle pressure uniqueness indicator, the average measured work cycle pressure uniqueness indicator, the measured pressure work cycle graph uniqueness indicator and the measured pressure work cycle partial graph uniqueness. The carried out research and its analysis has shown that powering the engine with LPG gas has an influence on the engine work cycles and its uniqueness. The burning process of the mixture consisting of air and LPG gas is quicker, which has an effect on the higher speed of pressure increase rate in comparison with the engine being powered by petrol fuel. Achieved maximum in-cylinder pressure values while the engine was powered by LPG gas were higher in comparison with it being fuelled with conventional fuel. This causes an increase of the gas lads on crank-piston system, which are influencing directly the piston with higher heat load, and the thermal load of the engine.