EXPERIMENTAL INVESTIGATIONS ON THE USE OF TRANSIENT ETHANOL-DIESEL FUEL BLEND IN A DIESEL ENGINE: PERFORMANCE AND EMISSION STUDIES

Abstract

The utilization of ethanol as an additive in diesel engines has attracted considerable interest in recent times, owing to its potential to mitigate environmental issues, decrease reliance on fossil fuels, and improve engine performance. This research examines the application of ethanol in diesel engines and investigates its impact on combustion characteristics, engine emissions, and overall efficiency. This study specifically focuses on the integration of ethanol into diesel engines. Nevertheless, it is essential to acknowledge and address certain limitations associated with the use of ethanol and ethanol-diesel blends. These limitations include a low cetane number, phase separation, as well as low lubricity and viscosity values. To overcome the challenge of phase separation, an inline mixer is employed to ensure thorough blending of ethanol and diesel prior to direct feeding into the engine. Furthermore, a cetane number enhancer is mixed with ethanol to mitigate the impact of its low cetane number. Experimental investigations are conducted on a single-cylinder diesel engine, with variations in the concentration of the cetane number enhancer. Various parameters such as combustion pressure, heat release rate, efficiency, specific fuel combustion, and exhaust emissions are measured and subjected to analysis. The experimental findings are then compared to those obtained using pure diesel fuel, allowing for an assessment of the influence of ethanol on combustion, performance, and emission characteristics in diesel engines. The results indicate that the addition of ethanol to diesel fuel leads to a retardation of ignition timing and a decrease in peak pressure. Furthermore, the inclusion of ethanol in combination with diesel fuel reduces the duration of combustion due to increased v ignition delay, resulting in an overall reduction in heat release. However, the incorporation of a cetane number enhancer helps to bring these values closer to those observed with pure diesel fuel. With an increase in load, the Brake Specific Fuel Consumption (BSFC) decreases for all types of fuels. However, when ethanol is added to diesel fuel, the BSFC tends to increase due to the lower calorific value of ethanol. Nonetheless, the introduction of a cetane number enhancer mitigates this increase. On the other hand, the Brake Thermal Efficiency (BTE) demonstrates an increase with increasing load. Similarly, the BTE shows an improvement with the substitution of ethanol and further increases when a cetane number enhancer is incorporated. As the load on the engine increases, there is a corresponding increase in the emission of Smoke and NOx. However, the addition of ethanol to diesel fuel results in a reduction of Smoke and NOx emissions, and this reduction becomes more pronounced with the inclusion of a cetane number enhancer. It is worth noting that the decrease in Smoke and NOx emissions is more significant at higher load conditions. On the other hand, the emissions of CO and HC decrease as the load increases. Nevertheless, when ethanol is substituted for diesel fuel, there is an increase in CO and HC emissions. However, this increment diminishes as the load increases, and the inclusion of a cetane number enhancer slightly reduces these emissions. These findings offer valuable insights for future advancements in the application of alternative fuels, aiding in the design and optimization of engines to maximize the benefits of ethanol as a sustainable and renewable fuel option.