Numerical analysis of C.I engine to control emissions using exhaust gas recirculation and advanced start of injection

AbstractAs major limitation of diesel engines is the high soot and nitrogen oxide emissions which cannot be reduced totally with only conventional catalytic converters today, varying fuel characteristics became a focus of interest to meet the pollution emission legislations as they require very few or no changes in existing engine model. The present work deals with, numerical analysis of combined effect of Advanced Start of Injection (SOI) and Exhaust Gas Re-circulation (EGR) on performance and emissions which were studied, by performing numerical analysis on a Caterpillar 3401 single cylinder C.I engine model at constant speed using diesel as fuel via three dimensional computational fluid dynamics (CFD) procedures and validated with experimental data. The SOI is advanced from 11° Crank angle bTDC to 14.5° Crank angle bTDC and EGR as a fraction is increased from 0% to 10%. The modified conditions of these parameters resulted in simultaneous reduction of NOx and Soot

Computational optimization of biodiesel combustion using response surface methodology

The present work focuses on optimization of biodiesel combustion phenomena through parametric approach using response surface methodology. Physical properties of biodiesel play a vital role for accurate simulations of the fuel spray, atomization, combustion, and emission formation processes. Typically methyl based biodiesel consists of five main types of esters: methyl palmitate, methyl oleate, methyl stearate, methyl linoleate, and methyl linolenate in its composition. Based on the amount of methyl esters present the properties of pongamia bio-diesel and its blends were estimated. CONVERGETM computational fluid dynamics software was used to simulate the fuel spray, turbulence and combustion phenomena. The simulation responses such as indicated specific fuel consumption, NOx, and soot were analyzed using design of experiments. Regression equations were developed for each of these responses. The optimum parameters were found out to be compression ratio – 16.75, start of injection – 21.9° before top dead center, and exhaust gas re-circulation – 10.94%. Results have been compared with baseline case

Processing and evaluation of nano SiC reinforced aluminium composite synthesized through ultrasonically assisted stir casting process

Aluminium composites were synthesized through an ultrasonically assisted stir casting method by reinforcing 0.5 wt%SiC, 1.0 wt%SiC, 1.5 wt%SiC and 2.0 wt%SiC nanoparticles. Ultrasonication was carried out to the composite melt to refine the grain size and to achieve uniform nano-SiC dispersion in the aluminium matrix. Scanning electron microscopy (SEM) reveals the uniform dispersion of nano-SiC particles in the 0.5 wt%, 1.0 wt% and 1.5 wt% SiC reinforced compose. However, the X-Ray Diffraction (XRD) peaks confirm the Al2Cu intermetallic phases in the Al- 2.0 wt% SiC composite. The mechanical properties of the synthesized composites were significantly enhanced with the incorporation of SiC reinforcements and the maximum hardness and ultimate tensile strength (U.T.S) of 163 BHN and 431 MPa was attained for 1.5 wt% SiC reinforced composite. Nevertheless, the generated brittle agglomeration at 2.0 wt% SiC reinforcements decreases the mechanical properties of the composite due to the variation of thermal expansion coefficients between the matrix and the agglomerations. The yield strength of the fabricated Al– SiC composites was analyzed through different strengthening mechanisms. Results concluded that the yield strength contribution due to thermal mismatch is more influenced followed by the Orowan strengthening and grain refinement strengthening mechanism. In addition to this, the contribution of the strengthening mechanisms was found to be increased with the addition of SiC nanoparticles. Fractography investigation for the fractured tensile specimens reveals the ductile fracture for unreinforced aluminium and brittle fracture for the SiC-reinforced composites due to the presence of cleavage texture of the fractured surfaces of Al–SiC nanocomposites