EFFECT OF EXHAUST GAS RECIRCULATION AND WATER INJECTION ON DIESEL ENGINE PERFORMANCE AND EXHAUST EMISSIONS

Abstract

The objective of this study is to investigate the impact of the Exhaust Gas Recirculation (EGR) or/and the Water Injection (WI) on the Turbocharged Diesel Engine performance (Brake Power (bp), Brake Specific Fuel Consumption (bsfc), and Brake Thermal Efficiency (BTE)), in addition to examining the effects on exhaust gas emissions such as Nitrogen Oxides (NOX), Carbon Monoxide (CO). A series of experiments were carried out in Sudan University of Science and Technology Laboratories on a Turbocharged Diesel Engine. The experiments results obtained showed that, the brake power decreased in the presence of EGR and continues to decrease as the ratio of EGR is increased, while the power increased by using the low and medium rates of injected water at the mid and high engine speeds. The combination of 5% EGR and low injected water rates increased the engine power. %10 of EGR ratios and less water rates caused a decrease in the power, but still are greater than that obtained by EGR setups. The bsfc increased by using EGR system, while the WI system was found to decrease the bsfc, mostly in the low and medium rates of injected water. Much water rate has led to increase the bsfc strongly and has achieved results between those obtained by the TC and NA engine. Combined 5% EGR and less water rates are shown to decrease the bsfc, and are equal to less than that given by the TC engine particularly at mid and high engine speeds. Increasing EGR ratio to 10% and less water volumes setups have kept the values of the bsfc between the TC and EGR setups. The Brake Thermal Efficiency (BTE) decreased when using the EGR system, while it increased by the low and medium volumes of injected water at the mid and high engine speeds. The BTE given by Combined 5% EGR and less water volumes is found to be greater than those given by the TC engine, mostly at the mid and high engine speeds. Combined 5% and much water caused to decrease the BTE and were found less than those given by the TC engine. The emission of NOX is reduced by the EGR system. WI affected positively in reducing the NOX emission, and as the volume of injected water increased the emission of NOX is decreased. The combined system caused a reduction in the emission of NOX significantly. CO is increased by the EGR system, while the WI is caused to decrease the CO emission. This might be attributable to the water-gas shift reaction, in addition to the positive effect of WI on combustion efficiency. Emission of CO in the presence of the combined setups increased significantly. 5% EGR + WI systems emitted CO more than that obtained by 5% EGR. EGR ratio greater than 5% and WI setups emitted CO greater than that given by EGR setups.