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Potential to reduce the diesel engine emissions of Diesel-Ethanol-Biodiesel blends of high ethanol fraction (DEB blends) has been investigated. Experiments were performed for three DEB blends with oxygen contents of 7.78%, 12.21%, and 14.53% by weight (ethanol content 20%, 30% and 40% by volume) on diesel engines with significantly different engine configurations. The results showed that the HC emissions mainly depend on in cylinder temperatures, and significantly increased for DEB blends at low loads in case of low in cylinder temperature engine. CO emissions are governed by the combination of excess air and in cylinder temperature and oxygen in fuel helped to reduce it when the engine works with richer mixtures. NO emissions are predominantly dependent on excess air compared to the in cylinder temperature and oxygen in fuel has minor effect on it. The effect of oxygen in fuel on smoke reduction is more significant if the engines are working with rich mixtures.

The research work focus on the occurrence of incylinder peak pressure variation and fuel spray characteristics on piston seizure. The study has been carried out for direct injection diesel engine of heavy duty off-highway application. The well optimized and normal combustion results into the peak cylinder pressure variation within 3.5 bar to 4 bar, whereas the abnormal combustion signposts the peak cylinder pressure almost double of normal combustion. The research work has been carried out to study the effect of different peak cylinder pressure variation and its effect on the start of piston seizure. The three different range of peak cylinder pressure variation have been selected for the study. The selected range of peak cylinder pressure depicts normal to abnormal combustion characteristics. The effect on piston motion dynamics and start of piston seizure has been carried out successfully.

Estimation of the ignition delay and concentration of exhaust emissions carries great importance in engine development process. In direct injection (DI) diesel engines, ignition delay has direct effect on startability, noise and pollutant formation. Hydrocarbon (HC) emissions are mainly due to the unburnt or partially burnt fuel leaving the engine exhaust system. In the present work, correlations have been developed for ignition delay and HC emissions. Satisfactory comparison of predicted and experimental values of ignition delay and HC emission under different operating conditions for various engines, widely varying in dimensions, method of aspiration and rated speeds validated the correlations. These correlations are useful as design tools for engine development.

Exhaust gas recirculation (EGR) is an effective means to reduce NOx emissions in Diesel engines. An innovative concept of EGR admission was developed for diesel engine of heavy-duty application. A 4-cylinder, naturally aspirated, water-cooled engine was selected for experimental investigation. One-dimensional simulation software was used to predict emission and performance parameters. The engine model was initially validated with experimental data and then used for parametric study for EGR. The best EGR flow rates were determined for experimental study, to study the effect of EGR on engine emissions. A significant reduction in emissions of NOx with minimal increase in CO and HC emission was achieved. Based on number of experiments and simulations an innovative EGR system was developed to control flow of hot exhaust back into the intake manifold for NOx reduction.

Ethanol is an alternative renewable fuel produced from various agricultural products. Ethanol-diesel emulsion technique is used for the utilization of ethanol in diesel engines wherein ethanol is used without any modification. The performance, combustion and emission characteristics of a direct injection (DI) diesel engine for off-highway application were evaluated using ethanol-diesel microemulsions. The addition of ethanol to diesel fuel simultaneously decreases calorific value, kinematic viscosity and stability of fuel. Ethyl acetate was used as an additive/ingredient to keep the blends in homogeneous and stable state. Blends (D80/E13/EA07; D70/E17/EA13; D60/E23/EA17) were selected for engine experiments based on stability behavior and fuel properties. The results showed no significant power reduction in the engine operation with ethanol-diesel microemulsions.

A major task faced by engine manufacturers all over the world is to upgrade running engine designs with least possible modifications to meet next level of emission norms. This saves the precious lead-time and investments. In addition simplicity of design has to be maintained as far as possible while improving emissions. This is possible only by optimal combinations of FIE and engine. This paper describes such a cost effective up-gradation of an engine from US Tier 1 to US Tier 2 in very short time with minimal design changes. This difficult task was achieved by using latest techniques of simulations, measurements and concurrent engineering. For variable speed application it is desirable to retard injection timing as speed decreases, to compensate gain in absolute time. For constant speed application, retardation at part load is required as more weightage is given at part loads for the emission test cycle.