Chemical Engineering
S. Talesh Amiri; R. Shafaghat; O. Jahanian; G. Sadripour
Abstract
For decreasing the fuel consumption of internal combustion engines, and also reducing the emissions, investigation of the effective parameters on power, emissions, and the combustion phasing is important. In this study, the influence of adding water to a Reactivity Controlled Compression Ignition (RCCI) ...
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For decreasing the fuel consumption of internal combustion engines, and also reducing the emissions, investigation of the effective parameters on power, emissions, and the combustion phasing is important. In this study, the influence of adding water to a Reactivity Controlled Compression Ignition (RCCI) engine has been numerically investigated. For this purpose, water with different mass fractions was added to the air-fuel mixture. In order to simulate the engine, AVL Fire software was used. The results show that substituting a portion of gasoline fuel with water, up to 10% mass fraction, raises the combustion chamber pressure. In this condition, the production of hydroxyl free radicals, as one of the characteristics for the start of combustion, occurs earlier. Furthermore, Indicated Mean Effective Pressure (IMEP) remains unchanged. By further increasing the water mass the production of hydroxyl radical decreases, and the high-temperature heat release is delayed; also comparing to when water was not added, average temperature of the combustion chamber reduces, while the amount of CO production does not change. Increasing the number of water moles increases the maximum in-cylinder pressures so that compared to pure gasoline mode, by replacing 20% of gasoline mass with water, the indicated mean effective pressure approximately stays the same.
S. Talesh Amiri; R. Shafaghat; O. Jahanian; A. H. Fakhari
Abstract
To better homogenize the mixture of fuel and air in the combustion chamber and to enhance the controllability of ignition timing in Reactivity Controlled Compression Ignition (RCCI) engines, controlling the start of injection (SOI) timing can be essential. By changing the SOI timing, at some specific ...
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To better homogenize the mixture of fuel and air in the combustion chamber and to enhance the controllability of ignition timing in Reactivity Controlled Compression Ignition (RCCI) engines, controlling the start of injection (SOI) timing can be essential. By changing the SOI timing, at some specific crank angles (CAs), the fuel can impact the edge of the piston bowl and create some difficulties. In this research, initially, efforts are made to recognize the range of SOI timing in which this collision process takes place (in the range of 44-54° bTDC), then, performance and the emission levels of the engine were evaluated in the beginning and end of this interval. The findings suggest that the nitrogen oxides emissions and the maximum in-cylinder mean pressure are higher in SOI of 44° bTDC, as compared to those in the SOI timing of 54°bTDC, although the latter has higher ignition delay and unburnt hydrocarbon (UHC) emission. Moreover, some evaluations were carried out to examine how the temperature of the fuel-air mixture can affect the performance of the engine in this specific range. It was found that as the IVC temperature increases, it rises the indicated mean effective pressure (IMEP), in-cylinder pressure, and NOx emission.
