جستجوی مقالات مرتبط با کلیدواژه « RCCI » در نشریات گروه « مکانیک »

Reactivity-Controlled Compression Ignition (RCCI) is one of the attractive low-temperature combustion strategies because of its high efficiency, reduced fuel consumption, and good potential in reducing emissions. This type of combustion has gained attention in recent years due to global concerns regarding environmental degradation, strict emission regulations, reduction of oil reserves, and rising fossil fuel prices. In this research, an RCCI engine, with a fuel mixture of diesel and gasoline, simulated with the aid of computational fluid dynamics coupled with chemical kinetics. The AVL FIRE software employed for the simulations. The aim was to investigate the impacts of changing the diesel fuel injection timing on combustion and emissions. In this regard, the effects of changing the diesel fuel injection timing in the range of 20 to 40° bTDC on the in-cylinder pressure, heat release rate, combustion phase, and the amount of carbon monoxide, carbon dioxide, nitrogen oxides, and unburned hydrocarbons emissions investigated at a constant engine speed of 1150 rpm. One of the most important results of this study is the reduction of NOX emissions by advancing fuel injection timing to 40° bTDC. Furthermore, with the advancement of diesel fuel injection timing, the combustion starts earlier. By raising the injection duration, the maximum in-cylinder pressure decreases, and the start of combustion delayed. As the fuel injection advances from 20 to 30° bTDC, the produced carbon monoxide decreases, and a further advancement from 30 to 40° bTDC, raises the amount of this pollutant. It is worth noting that the amount of CO2 greenhouse gas has an almost negative relationship with carbon monoxide production.

Reactivity controlled compression ignition (RCCI) is a new combustion mode which a mixture of fuel inside the cylinder is provided by injection of low reactivity fuel in the fuel inlet manifold and multi-stage injection of high reactivity fuel inside the cylinder. By changing the engine input parameters and determining the conditions, this study attempted to approximate a biodiesel dual-fuel (C11H22O2) / natural gas emgine to the combustion phase of reactivity controlled compression ignition (RCCI) to examine and compare the efficiency and output emissions. The understudy influencing factors included the comparison between the biodiesel-natural gas and diesel-natural gas fuels with similar energy generation, relevant strategies, and fuel emission rate. In this research, the 3401E Caterpillar emgine geometry was employed for the numerical simulation by the commercial Converge Software and SAGE combustion model. The results showed that, due to the high Cetane number and high oxygen present in its composition, the biodiesel fuel gave rise to earlier combustion as compared with diesel. The injection time precession, shortened injection time, and increased injection rate in the first phase increased pressure, average temperature, and the heat release rate, and the power and yield of combustion enhanced. Likewise, due to complete combustion, the rates of output emissions, including CO2, HC, and soot, decreased.

Reducing fuel consumption and emissions, as well as increasing the power and efficiency, have always been important in IC engines researches. Due to the positive effects of adding water to the inlet fuel-air mixture through the manifold of a low-temperature engine, the effect of the temperature of water added to the low-reactivity fuel in an RCCI engine with gasoline-diesel dual-fuel has been investigated. The water temperature varies between [20-60]oC. Water is substituted for gasoline with different mass-ratios; so that the reduction of fuel will be equal to the amount of water added. For numerical simulation, the AVL-Fire was used as a couplet with the detailed chemical kinetics code. For validation, numerical results are compared with similar experimental data. The results show that by increasing the mass-ratio of the replaced water up to 10%, the in-cylinder pressure and temperature as well as the NOx increase significantly; but with an increase in mass-ratio to 15%, a decreasing trend is seen. With the increase in the mass-ratio to 20%, it will again lead to an increasing trend; however, at this mass-ratio, the in-cylinder temperature, and the NOx have not increased significantly, despite the increase in power characteristics. Then, considering the mass-ratio of 20%, the evaluation of water temperature increasing shows an improving trend; so that the maximum average in-cylinder pressure is increased and leads to a slight increase in the IMEP. Also, due to the increase in combustion quality, CO is significantly reduced, as well as the ISFC is reduced up to 2%.