A Study on Combined Effect of Biodiesel, Parametric Optimization and EGR Technique on NOx Reduction from Diesel Engine

Current energy crisis due to rapid depletion of the conventional fuel and environment concerns, have made the world to think about alternate sources of energy and have also prompted an evolution of first, second, and third generation biofuels as alternative energy sources. But one serious problem with these biofuels is that they generally shows an increment in NOx and because of half of the NOx is emitted by automobile sources, control of emission of oxides of nitrogen becomes major issue of research now-a-days. In this research article, an experimental investigation has been conducted to observe the effect of parametric optimization of engine and exhaust gas re-circulation on emission of oxides of nitrogen. In diesel engine, controlling NOx in engine emission, peak combustion temperature plays vital role because NOx formation in diesel engine is highly temperature-dependent phenomenon and takes place at combustion chamber temperature above 2000K. The experiments are conducted with diesel, Jatropha biodiesel blend (50JB50D), and pure biodiesel. For present investigation, injection pressures considered are 160bar, 190bar & 220bar. Experiment was conducted twice, once without EGR & again with hot EGR to measure effect of EGR in NOx reduction at various loading condition of 1, 6, & 11KG. Factors affecting the NOx emission are injection timing, engine load, injection pressure, compression ratio, air-fuel ratio, exhaust gas recirculation, fuel blend. Effect of the injection pressure, fuel blend, engine load and exhaust gas recirculation technique on emission of NOx has been observed in this research. It has observed that highest NOx, emitted from engine with diesel was 451 ppm at 220bar IP and that for blend and pure biodiesel were 460 & 475 ppm, simultaneously. Maximum NOx reduction was 94.34% for pure diesel at 1Kg load 160bar injection pressure and minimum value for that was 80.89% for pure biodiesel at 6Kg load 190bar Injection pressure. With pure diesel, NOx emission was increased by 349 ppm and that for diesel-biodiesel blend & pure biodiesel were 350 & 354 ppm. One possible explanation behind this increment is, more oxygen content of biodiesel which leads to higher combustion temperature.