Andrzej Ambrozik, Dariusz Kurczyński and Piotr Łagowski
, and O. S. Söğüt, “A Comparative Performance Analysis of Endoreversible Dual Cycle Under Maximum Ecological Function and Maximum Power Conditions,” Exergy, An International Journal , vol. 2, no. 2, pp. 173–185, Jan. 2002. https://doi.org/10.1016/S1164-0235(02)00071-7
 R. Ebrahimi and M. Sherafati, “Thermodynamic Simulation of Performance of a Dual Cycle With Stroke Length and VolumetricEfficiency,” Journal of Thermal Analysis and Calorimetry , vol. 11, no. 1, pp. 951–957, Apr. 2012. https://doi.org/10.1007/s10973-012-2424-1
 W. Pulkrabek
Natural gas has a higher knock suppression effect than gasoline which makes it possible to operate at higher compression ratio and higher loads resulting in increased thermal efficiency in a spark ignition engine However, using port fuel injected natural gas instead of gasoline reduces the volumetric efficiency from the standpoints of the charge displacement of the gaseous fuel and the charge cooling that occurs from liquid fuels. This article investigates the combustion and engine performance characteristics by utilizing experimental and simulation methods varying the natural gas-gasoline blending ratio at constant engine speed, load, and knock level. The experimental tests were conducted on a single cylinder prototype spark ignited engine equipped with two fuel systems: (i) a Direct Injection system for gasoline and (ii) a Port Fuel Injection (PFI) system for compressed natural gas. For the fuels, gasoline with 10% ethanol by volume (commercially known as E10) with a research octane number of 91.7 is used for gasoline via the DI system, while methane is injected through PFI system. The knock suppression tests were conducted at 1500 rpm, 12 bar net indicated mean effective pressure wherein the engine was boosted using compressed air. At 60% of blending methane with E10 gasoline, the results show high knock suppression. The net indicated specific fuel consumption is 7% lower, but the volumetric efficiency is 7% lower compared to E10 gasoline only condition. A knock prediction model was calibrated in the 1-D simulation software GT-Power by Gamma Technologies. The calibration was conducted by correlating the simulated engine knock onset with the experimental results. The simulation results show its capability to predict knock onset at various fuel blending ratios.
Magdalena Szwaja, Paweł Mazuro and Stanisław Szwaja
The main aim of the research was to investigate influence of overlap of the natural gas fuelled spark ignited engine on the following parameters: Indicated Mean Effective Pressure (IMEP), heat rate release including combustion phases (ignition lag, main combustion phase). The content of the study includes results from processing in-cylinder pressure measurements, heat release rate analysis, combustion phases, and finally the conclusions. The tests were carried out on the test bed including the single cylinder research engine with a displacement volume of 550 cm3. The engine was equipped with independent cam phasors for both intake and exhaust valves, but for this investigation, the exhaust valve timing was fixed (the exhaust cam centre line was fixed at -95 crank angle (CA) deg before Top Dead Centre) and intake valve timing was changed (the intake cam centre line was varied from 90 to 150 CA deg after Top Dead Centre). The overlap was changed in the range from 85 to 25 CA deg. 8 tests series were performed, each singular series consisted of 300 consecutive engine combustion cycles. As observed, by varying the valve overlap it contributes to significant change in the peak combustion pressure, peak of heat release rate, and combustion phases. Summing up, variable valve timing affects compression and expansion strokes by changing polytropic indexes due to various amounts of exhaust residuals trapped in the cylinder. It affects not only engine volumetric efficiency but also the heat release rate and IMEP, so it does engine performance. Thus, variable valve timing can be considered as valuable tool that can be applied to the natural gas fuelled internal combustion engine.
VolumetricEfficiency of High Pressure External Gear Pump. Naše More, 57(5-6), pp. 235-240.
Dynatec. 2011. Hydraulic components. Taichuna City, Taiwan.
Hao, X., Zhou, X., Liu, X. and Sang, X. (2016). Flow characteristics of external gear pumps considering trapped volume. Advances in Mechanical Engineering, 8(10), pp. 1-10.
Chrastina, J., Janoško, I. and Polonec, T. (2013). System for monitoring operating parameters of vehicles. Trends in agricultural engineering 2013. Prague: Czech University of Life Sciences Prague, pp. 267