Numerical analysis of spray characterization of blends of hydrous ethanol with diesel and biodiesel

The spray characteristics of a fuel greatly influence the combustion as it affects the formation of an air-fuel mixture, which directly impacts the performance and emissions of the engine. This study investigates the physical injection spray characteristics of biofuels to optimize the engine operating parameters for their effective utilization. For the analysis of the spray characteristics of pure diesel (D100), 80% diesel-20% biodiesel (D80B20), 80% diesel-10% biodiesel-10% pure ethanol (D80B10E10), and 80% diesel-10% biodiesel-10% hydrous ethanol (D80B10HE10) are investigated. Computational Fluid Dynamics (CFD) modeling of a constant volume chamber under non-evaporative conditions is performed to conduct numerical analysis. The chamber pressure of 2 and 2.5 MPa and nozzle injection diameter of 0.126 mm, 0.15 mm, and 0.2 mm are considered to conduct the simulations. The variation in spray penetration length is analyzed and discussed for the injection of different fuel blends at different initial conditions. It is observed from numerical results that the high-density fuel blend D80B20 has a penetration length of 10.695% and 15.805% higher than pure diesel and D80B10HE10 blends, respectively. For pure diesel, with an increase in nozzle diameter from 0.126 mm to 0.15 mm and 0.2 mm, the penetration length is increased by 20% and 32%, respectively, and with an increase in pressure from 2 MPa to 2.5 MPa, penetration length is decreased by 14.62%. From this study, it can be concluded that biofuels like biodiesel and hydrous ethanol can be used with diesel in blended form over pure ethanol. Compared to pure ethanol, hydrous ethanol gives cost benefits and better spray characteristics.

Influence of injection strategies on ignition patterns of RCCI combustion engine fuelled with hydrogen enriched natural gas

The depletion of fossil fuel and the concerns for harmful emissions and global warming has instigated researchers to use alternative fuels. Hydrogen (H2) and natural gas (NG) are attractive fuels for internal combustion engines. The dual-fuel combustion strategy is promising to reduce emissions with efficient engine operation. The concern for using NG in this strategy is the lower efficiency at low load conditions and the emission of exhaust gases like carbon monoxide and unburnt hydrocarbon. Mixing fuel with a wide flammability limit and a faster burning rate with NG is an effective method to compensate for the limitations of using NG alone. Hydrogen (H2) is the best fuel added with NG to cover NG limitations. This study investigates the in-cylinder combustion phenomenon of reactivity-controlled compression ignition (RCCI) engines using hydrogen-added NG as a low-reactive fuel (H2 addition to NG on a 5% energy basis) and diesel as a highly reactive fuel. The numerical study was done on a 2.44 L heavy-duty engine using CONVERGE CFD code. Three low, mid, and high load conditions were analyzed in six stages by varying the diesel injection timing from -11 to -21 O after top dead centre (ATDC). The H2 addition to NG had shown deficient harmful emissions generation like carbon monoxide (CO) and unburnt hydrocarbon with marginal NOx generation. At low load conditions, the maximum imep was achieved at the advanced injection timing of -21OATDC, but with the increase in load, the optimum timing was retarded. The diesel injection timing varied the optimum performance of the engine for these three load conditions.